AMERICAN INSTITUTE OF CROP ECOLOGY
A RESEARCH ORGANIZATION DEVOTED TO PROBLEMS OF
PLANT ADAPTATION AND INTRODUCTION
WASHINGTON, D. C.
AICE* SURVEY OF USSR AIR POLLUTION LITERATURE
Volume X
THE TOXIC COMPONENTS OF AUTOMOBILE EXHAUST GASES:
THEIR COMPOSITION UNDER DIFFERENT OPERATING CONDITIONS,
AND METHODS OF REDUCING THEIR EMISSION
Edit3d By
M. Y. Nuttonson
The material presented here is part of a survey of
USSR literature on air polh'
conducted by the Air Pollution Sect
AMERICAN INSTITUTE OF CROP ECOLOGY
This surv, uder GRANT 1 R01 AP00786 - APC
OFFICE OF AIR PROGRAMS
of the
U.S. ENVIRONMENTAL PROTECTION
'AMERICAN INSTITUTE OF CROP ECOLOGY
809 DALE DRIVE
SILVER SPRING. MARYLAND 20910
1971
-------
PUBLICATIONS of Hie AMERICAN INSTITUTE OF CROP ECOLOGY
Ktt.
No.
1 UKRAINE-Ecologicol Crop Geography of the Ukraine and the
Ukrainian Agro-Climatic Analogues in North America
2 POLAND-Agricul tural Climatology of Poland ond Its Agro-
Climattt. Analogues in North America
3 C7=CHOSLOVAKIA-Agrieulturol Climatology of Czechoslo-
vakia and It) Agro-Climatic Analogues in North America
4 YUGOSLAVIA-Agriculturol Climatology of Yugoslavia ond Its
Agio-Climatic Analogues in North America
S GREECE—Ecological Crap Geography of Greece and Its Ao.ro-
Climotic Analogues in North America
6 AiaANIA-Ecologicol Plant Geography of Albania, Iff Agri-
cultural Crops and Some North American Climatic Analogues
7 CHINA-Ecologicol Crop Geography of China ond Its Agro-
Climatic Analogues in North America
S GERMANY-Eeologicol Gap Geography of Germany and Its
Agro-Climatic Analogues in North America
*9 JAPAN (l)-Agriculfural Climatology of Japan and Irs Agro-
Climatic Analogues in North America
10 Fl NLANO-Ecological Crop Geography of Finland and Its Agm-
Climatie Analogues in North America
II SWEDEN-Agriculturol Climatology of Sweden and Irs Agro-
Climatic Analogues in North America
12 NORWAY-Ecological Crop Geography of Norway andltsAgm-
Climatic Analogues in North America
13 SIBERIA-Agricullurol Climatology of Siberia, In Natural Belts,
and Agro-Climatic Analogues in North America
14 JAPAN (2)-Ecologicol Crop Geography and Field Practices of
Japan, Japan's Natural Vegetation, and Agro-Climatic
Analogues in North America
IS RYUKYU ISLANDS-Ecological Crop Geography ond Field
Practices of the Ryukyu Islands, Natural Vegetation of the
Ryukyus, and Agro-Climatic Analogues in the Northern
Hemisphere
16 PHENOLOGY AND THERMAL ENVIRONMENT AS A MEANS
OF A PHYSIOLOGICAL CLASSIFICATION OF WHEAT
VARIETIES AND FOR PREDICTING MATURITY DATES OF
WHEAT
(Based on Data of Czechoslovakia and of Same Thermally
Analogous Areas of Czechoslovakia in the United States
Pacific Northwest)
17 WHEAT-CLIMATE RELATIONSHIPS AND THE USE OF PHE-
NOLOGY IN ASCERTAINING THE THERMAL AND PHO-
TOTHERMAl REQUIREMENTS OF WHEAT
(Based on Data of North America and Some Thermally Anal-
ogous Areas of North America in the Soviet Union and in
Finland)
16 A COMPARATIVE STUDY OF LOWER AND UPPER LIMITS OF
TEMPERATURE IN MEASURING THE VARIABILITY OF DAY-
DEGREE SUMMATIONS OF WHEAT, BARLEY, AND RYE
*?
19 BARLEY-CLIMATE RELATIONSHIPS AND THE USE OF PHE-
NOLOGY IN ASCERTAINING THE THERMAl/AND PHO-
TOTHERMAL REQUIREMENTS OF BARLEY
20 RYE-CLIMATE RELATIONSHIPS AND THE USE OF PHENOL-
OGY IN ASCERTAINING THE THERMAL AND PHOTO-
THERMAL REQUIREMENTS OF RYE
21 AGRICULTURAL ECOLOGY IN SUBTROPICAL REGIONS
22 MOROCCO, ALGERIA, TUNISIA-Fhysied Environment and
Agriculture
23 LIBYA and EGYPT-Physical Environment ond Agriculture. . .
24 UNION OF SOUTH AFRICA-PJiydcol Environment and Agri-
culture, WihS Special Reference to Wmter-RoinMI Regions
25 AUSTRALJA-Phy*;ca' Environment and Agriculturo, With Spe-
cial Reference to Winter-Rainfall Regions
26 S. E. CALIFORNIA and S. W. ARIZONA-Hiy"'*1 Environment
and Agriculture of the Desert Regions
27 THAILAND-Physical Environment and Agriculture
28 BUKMA-Physical Environment ond Agriculture
28A BURMA-Diseoses and Pesti of Economic Plants
28B BURMA-Climote, Soils and Rice Culture (Supplementary In-
formation and a Bibliography to Report 2B)
29A VIETNAM, CAMBODIA, LAOS-rnvsical Environment and
Agriculture
29B VIETNAM, CAMBODIA, LAOS-Diseases and Pesfsof Economic
Plants
29C VIETNAM, CAMBODIA, LAOS-Climatalogical Data (Supple-
ment to Report 29A)
30A CENTRAL and SOUTH CHINA, HONG KONG, TAIWAN-
Phyiical Environment and Agriculture $20.00*
308 CENTRAL and SOUTH CHINA, HONG KONG, TAIWAN-
Mojor Plant Pesh and Diseases
31 SOUTH CHINA-lts Agro-Climatic Analogues in Southeast Asia
32 SACRAMENTO-SAN JOAQUIN DELTA OF CALIFORNIA-
Physicol Environment and Agriculture
33 GLOBAL AGROCLIMATIC ANALOGUES FOR THE RICE RE-
GIONS OF THE CONTINENTAL UNITED STATE
34 AGRO-CLIMATOLOGY AND GLOBAL AGROCLIMATIC
ANALOGUES OF THE CITRUS REGIONS OF THE CON-
TINENTAL UNITED STATES
35 GLOBAL AGROCLIMATIC ANALOGUES FOR THE SOUTH-
EASTERN ATLANTIC REGION OF THE CONTINENTAL
UNITED STATES
36 GLOBAL AGROCLIMATIC ANALOGUES FOR THE INTER-
MOUNTAIN REGION OF THE CONTINENTAL UNITED
STATES
37 GLOBALAGROCLIMATICANALOGUESFORTHE NORTHERN
GREAT PLAINS REGION OF THE CONTINENTAL UNITED
STATES
38 GLOBAL AGROCLIMATIC ANALOGUES FOR THE MAYA-
GUEZ DISTRICT OF PUERTO RICO
39 RICE CULTURE ond RICE-CLIMATERELATIONSHIPS With Spe-
cial Reference to the United Slates Rice Areas and Their
Latitudinal and Thermal Analogues in Other Countries
40 E. WASHINGTON, IDAHO, and UTAH-Phyiical Environment
and Agriculture
41 WASHINGTON, IDAHO, and UTAH-The Use of Phenology
in Ascertaining the Temperature Requirements of Wheat
Grown in Washington, Idaho, ond Utah ond in Some of
Their Agro-Climafieally Analogous Areas in the Eastern
Hemisphere
42 NORTHERN GREAT PLAINS REGION-Preliminary Study of
Phonological Temperature Requirements of o Few Varieties
of Wheat Grown in the Northern Great Plains Region and in
Some Agro-Climotically Analogous Areas in the Eastern
Hemisphere
43 SOUTHEASTERN ATLANTIC REGION-Phenological Temper-
ature Requirements of Some Winter Wheat Varieties Grown
in the Southeastern Atlantic Region of the United Stoles and
in Several of Its Latitudinal!/ Analogous Ansas of the Eastern
and Southern Hemispheres of Seasonally Similar Thermal
Conditions
44 ATMOSPHERIC AND METEOROLOGICAL ASPECTS OF AIR
POLLUTION-A Survey of USSR Air Pollution Literature
45 EFFECTS AND SYMPTOMS OF AIR POLLUTES ON VEGETA-
TION; RESISTANCE AND SUSCEPTIBILITY OF DIFFERENT
PLANT SPECIES IN VARIOUS HABITATS, IN RELATION TO
PLANT UTILIZATION FOR SHELTER BELTS AND AS BIO-
LOGICAL INDICATORS-A Survey of USSR Air Pollution
Literature
(Continued on inside of back cover)
-------
AiCE* SURVEY OF USSR AIR POLLUTION LITERATURE
Volume X
THE TOXIC COMPONENTS OF AUTOMOBILE EXHAUST GASES:
THEIR COMPOSITION UNDER DIFFERENT OPERATING CONDITIONS,
AND METHODS OF REDUCING THEIR EMISSION
Edited By
M. Y. Nuttonson
The material presented here is part of a survey of
USSR literature on air pollution
conducted by the Air Pollution Section
AMERICAN INSTITUTE OF CROP ECOLOGY
This survey is being conducted under GRANT 1 RO1 AP00786 - APC
OFFICE OF AIR PROGRAMS
of the
U.S. ENVIRONMENTAL PROTECTION AGENCY
*AMERICAN INSTITUTE OF CROP ECOLOGY
809 DALE DRIVE
SILVER SPRING, MARYLAND 20910
1971
-------
TABLE OF CONTENTS
Page
PREFACE v
Mope of the USSR
Orientation vii
Climatic* Soil and Vegetation Zones viii
Major Economic Areas ix
Major Industrial Centers x
Principal Centers of Ferrous Metallurgy and Main
Iron Ore Deposits xi
Principal Centers of Non-Ferrous Metallurgy and
Distribution of Most Important Deposits of
Non-Ferrous Metal Ores xii
Principal Centers of the Chemical Industry and of
the Textile Industry ... xlii
Principal Centers of Wood-Working, Paper f and Food
Industries xiv
Main Mining Centers ..« xv
Principal Electric Power Stations and Power Systems xvi
HOW TO NEUTRALIZE AUTOMOBILE EXHAUST GASES
I. L. Varshavskly and R. V. Malov 1
Introduction 2
Chapter I. Exhaust Gases of Automobiles
1. Combustion of Fuel in Engines 5
2. Composition of Exhaust Gases 8
3. Effect of the Main Components of
Exhaust Gases on the Human Organism 12
4. Evaluation of the Toxicity of Exhaust
Gases 15
Chapter II. Control of Exhaust Gases
1. Analysis of Exhaust Gases 21
2. Rapid Analysis of Exhaust Gases 26
Chapter III. Methods of Reducing the Formation
of Toxic Components in Exhaust Gases
1. Operating Conditions of Engine 31
2. Engine Adjustment 33
3. Technical Condition of Engine 42
4. Leaning Out of Mixture, Ignition With
High Energy Spark, Flame Ignition 45
5. Vacuum Regulator 48
6. Use of Fuel Additives 49
iii
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Chapter IV. Neutralization of Toxic Components
of Exhaust Gases 55
1. Liquid Neutralizers 55
2. Flame Afterburning of Toxic Components
of Exhaust Gases 61
3. Catalytic Neutralization of Exhaust Gases .. 64
4. Thermocatalytic Neutralization of
Exhaust Gases 75
5. Electric and Ultrasonic Filters 76
6. Crankcase Gases and Control of Their
Toxicity 77
Chapter V. Prospective Automobile Engines and
Extent of Possible Poisoning of the
Atmosphere by Them 81
1. Mechanical Energy Converters 81
2. Nonmechanical Energy Converters 86
Afterword B. S. Stechkin 102
Literature Cited 105
DETERMINATION OF THE COMPOSITION OF EXHAUST GASES FOR
CARBURETOR ENGINES UNDER DIFFERENT OPERATING CONDITIONS
Robert Eberan von Eberhorst 107
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PREFACE
The present volume consists of reports dealing with a nunber of
investigations relating to the composition and to the methods of control
of air pollutants emitted from the exhausts of motor vehicles.
Contamination of the natural environment constitutes a major problem
in all industrial regions and in the urban areas of the Soviet Union. The
rapid development of various industrial enterprises throughout much of the
country and the extensive use of the internal-combustion engine for motor
vehicle transportation contribute greatly to massive qualitative changes in
man's habitat through an ever increasing pollution of air, soil, and streams.
The increase in the concentration of the biologically toxic types of air con-
taminants impairs the well-being of humans and animals, causes injury and
even death to susceptible plant species, and brings about deterioration of
various materials.
The exhaust emissions of the internal-combustion engine, powered by
gasoline or diesel oil, is a dominant source of aerial contamination. The
majority of the current models of automobiles, trucks, and busses used
extensively throughout the country contribute to a severe air-pollution
problem, especially in the large cities. The principal exhaust-emitted toxic
gases are carbon monoxide, -unburned hydrocarbons, and nitric oxides. Also
of considerable importance is the exhaust-emitted particulate matter, of
which the most significant and most toxic contaminants are the lead compounds.
The levels of emission of carbon monoxide, as well as of unburned hydro-
carbons and of nitric oxide, are associated with the speed of operation of
the motor vehicle the levels of the first two being higher at idling or
at low speed and decreasing with acceleration whereas the emission levels of
nitric oxide increase at heavy acceleration and high speeds. The carburetion,
the mechanical and electrical conditions of the engine, the nature of fuel
used, as well as the conditions of motor vehicle operation in reference to load
and speed, are major factors determining the nature and volume of the exhaust-
emitted contaminants whose relative toxicity and adverse effects on a living
organism vary considerably under diverse environmental conditions. The pol-
lution-emission toxicity potential of automotive exhaust gases is, to a large
extent, dependent upon such environmental conditions as the degree of solar
irradiation, wind velocity, vertical profile of temperature, and upon the
temperature inversion phenomenon.
A considerable volume of basic research is conducted in the Soviet
Union on methods of analysis of exhaust-emitted contaminants, on variables
that affect the composition and concentration of these contaminants, and on
the toxic effects of the different components of exhaust emissions. Intensive
studies are being undertaken there in an effort to find suitable means to
reduce the volume and toxicity level of exhaust emissions, with the ultimate
-------
goal of developing an engine with as nearly as possible a pollution-free
exhaust.
Although the material brought together in. this volume deals only with
the problem of air pollution from the exhaust emissions of gasoline-powered
automobiles, some background information on the distribution of the Soviet
industry's production machine may be of interest in connection with that
country's present and potential pollution problems. The planned distribu-
tion of production in the Soviet Union favors effective exploitation of the
natural resources of the USSR, especially in its eastern areas where enormous
natural resources are concentrated, and has led to the creation of large
industrial centers and complexes of heavy industry in many of the country's
economic areas .(see page ix). The many diverse climatic conditions of the
country and its major economic areas as well as the geographical distribu-
tion of the Soviet Union's principal industrial and mining centers and of
its principal electric power stations and power systems can be seen from
the various maps presented as background material in this volume.
It is hoped that the papers selected for presentation in this volume
will be conducive to a better appreciation of some of the air pollution
investigations conducted in the USSR. As the editor of this volume I wish
to thank my co-workers in the Air Pollution Section of the Institute for
their valuable assistance.
M. Y. Nuttonson
November 1971
vi
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ADMINISTRATIVE DWSlONS
SSB
1 R.S f S R
2 Kjrelo f .'ifiii-i S S R
3 Ellonun S S.B
4 Ljrviin S S ft
S Lrthuimin S S R
6 White Russian S $ R
7 IJkM ,..l:,\ -, R
8 Moldavian $ $ R
9. Geor£ papaya *•-.->'
P r-.ir,v '-' ..'^. -,"..*,.) ASSR
Q -.ikji^kj,* ASSR
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CLIMATIC ZONES AND REGIONS* OF THE USSR
00,-r^r-' EZ?>7"S /-[ARCTIC OCEAN?"-..--/^ '\
N- ^^^v> i \ /-X'/ 5 \
^^^1^ I
OF OKHOTSK
Zones: I-arctic, II-subarctic, Ill-temperate, IV-subtropical
Regions: 1-polar, 2-Atlantic, 3-East Siberian, 4-Pacific, 5-Atlantic,
6-Siberian, 7-Pacific, 8-Atlantic-arctic, 9-Atlantic-continental forests,
10-continental forests West Siberian, 11-continental forests East Siberian,
12-monsoon forests, 13-Pacific forests, lA-Atlantic-continental steppe,
15-continental steppe West Siberian, 16-mountainous Altay and Sayan,
17-mountainous Northern Caucasus, 18-continental desert Central Asian,
19-mountainous Tyan-Shan, 20-western Transcaucasian, 21-eastern Transcau-
casian, 22-mountainous Transcaucasian highlands, 23-desert south-Turanian,
24-mountainous Pamir-Alay
(After B. P. Alisov, "Climate of The USSR", Moscow 1956)
SOIL AND VEGETATION ZONES IN THE U.S.S.R.
viii
(After A. Lavrishchev, "Economic Geography
of the U.S.S.R.", Moscow 1969)
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MAJOR ECONOMIC AREAS OF TOE U.S.S.P.
-Western
gl
si Chernozem
IV Volga-Vyalka
V Notlh Caucasian
XI U.i
XII South-Western
XIII Donels-Dnreper
XIV Southern
XV Transcaucasian
VI Volga
VII Ur.ils
VIII Weil Siberian
IX East Siberian
X Far Eastern
XVI Kazakh! Ian
XVII Central Asia,
XVIII Byelorussian
PUNNED DISTRIBUTION OF INDUSTRIAL PRODUCTION IN ORDER
TO BRING IT CLOSER TO RAW MATERIAL AND FUEL SOURCES
An example of the planned distribution of industrial production in the USSR is the creation of large
industrial centers and complexes of heavy industry in many of the country's economic areas: the North-West
(Kirovsk, Kandalaksha, Vorkuta), the Urals (Magnitogorsk, Chelyabinsk, Nizhny Tagil), Western and Eastern
Siberia (Novosibirsk, Novokuznetsk, Kemerovo, Krasnoyarsk, Irkutsk, Bratsk), Kazakhstan (Karaganda, Rudny,
Balkhash, Dzhezkazgan).
Large'industrial systems are being created - Kustanai, Pavlodar-Ekibastuz, Achinsk-Krasnoyarsk,
Bratsk-Taishet and a number of others. Ferrous and non-ferrous metallurgy, pulp and paper, hydrolysis and
saw-milling industries are being established in the Bratsk-Taishet industrial system. The Achinsk-Kras-
noyarsk industrial system is becoming one of the largest centers of aluminum and chemical industries, and
production of ferrous metals, cellulose, paper, and oil products.
Construction of the third metallurgical base has been launched in Siberia, and a new base of ferrous
metallurgy, using the enormous local iron and coal resources, has been created in Kazakhstan. A high-
capacity power system is being organized in the same areas. Non-ferrous metallurgy is being further
developed in Kazakhstan, Central Asia and in Transbaikal areas. The pulp and paper, as well as the timber,
industries are being developed at a fast rate in the forest areas of Siberia and the Far East.
Ferrous metallurgy is also developing in the European part of the country by utilizing the enormous
iron ore resources of the Kursk Magnetic Anomaly and the Ukrainian deposits. Large new production systems
are under construction in the North-West, along the Volga, in the Northern Caucasus and the Ukraine.
(After A. Lavrishchev, "Economic Geography
of the U.S.S.R.", Moscow 1969)
ix
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THE MAJOR INDUSTRIAL CENTERS OF THE USSR
i
x
i
•*:•:•:•:•• --.yM^K^
"*'•'• '.'.'.'.'.'.*.'. •.'.'.'.V.'.y.*.',*.'. •.'.*,
ain centres ol ferrous metallurgy
-ferrous metallurgy
(res ol chemical industry
(After A. Efimov, "Soviet Industry", Moscow 1968)
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PKTNfTTPAT. TFMTFT7
oiling
Smelling ol ferroalloys
_ Mining ol:
iron ores
coking coat
mai>qane\e ore's
11AIM IRON ORE DEPOSITS IN THE U.S.S.5.
(After A. Lavrishchev, "Economic Geography of
the U.S.S.R.", Moscow 1969)
xi
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PRINCIPAL CENTERS OF MO*?-FEi:p.OUS METALLURGY IN THE U.S.S.R.
Metallurgy:
copper ® le.i.l
aluminiuni (HO nickel
O z!nc O 'in
^"-~ ir ~
DISTRIBUTION OF HOST IMPORTANT DEPOSITS OF NON-FERROUS I-STAL OPES
Ni Nickel o,ci
8 Bauiilet
N Nephelines
A Alunites
M Mercury Ottn <
O Cold
Pt Platinum
• Copper ores
O Tin ores
Complex ores
xii
(After A. Lavrishchev, "Economic Geography
of the U.S.S.R.", Moscow 1969)
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PRINCIPAL CENTERS OF THE CHEMICAL INDUSTRY IN THE U.S.S.R.
Gnomical indinlry (d.llerenl bunches)
Oil-refining industry
O Production ol lynlhelic rubber
O Production of mineral fertiliser
PRINCIPAL CENTERS OF THE TEXTILE INDUSTRY IN THE U.S.S.R.
t Poiad ©Melcnk,
VolotKoV
? Brihcitli 8 Vyarma
j fikov 9 Kl>nlty S NiAk^
t K^li.tin tO
xiii
(After A. Lavrishchev, "Economic Geography
of the U.S.S.R.", Moscow 1969)
-------
PRINCIPAL CENTERS OF WOOD-WORKING AND PAPER INDUSTRIES IN THE U.S.S.R.
'
nicpropelrovsk /V
--^_<^ . (•>:
:.Ka*anv-Kf.«noka'rmk
: '.r*:'-V->t?Wi-C-?<>Tc>ron,1;sk=:=
Industry:
Timber-sawing and wood-working
© Paper
Principal lumbering areas 500 o
Forests i , , . , 1
(After A. Lavrishctiev, "Ecor.omic Geography
of the U.S.S.R.", Moscow 1969)
XIV
-------
THE MAIN MINING CENTERS OF THE USSR
MINING
i Oil
A Oat
I Anthracite
Q Lignite
Oil refining
Oil pipes
Gaj pipes
Power stations
(After A. Efiraov, "Soviet Industry", Moscow 1968)
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PRINCIPAL ELECTRIC POWER STATIONS AND POWER SYSTEMS IK THE U.S.S.R.
Principal Electric Power Stations
Thermal Hydro-power
S
Under
and planned
G'oupi of eleclr;c
power itationi
Operating atomic electric power iladoni
Areas ol operation ol single power grids
European part of (he U.S.S.R.
Cenlral Siberia
operation of integrated power grids
Northern Kazalthilan
aucaius U4BWI Central Alia
Orlh-Weit
nd Wol
(Oeolermicheika/a)
10 Dmeprogei
11 Kdkhovka
4 Pldvinai 12 Slarobeihevik
5 Novaya Byelorusikaya 13 Zuycvskaya
6 Dubosiary 14 Shlerovka
7 Kanev 15 Krainodd
8 Kremenchua 16 Kathird
24Nurek
25 Ragunikaya
26 Varzob
Toklogul
28 Alamedi
(After A. Lavrishchev, "Economic Geography
of the U.S.S.R.", Moscow 1969)
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HOW TO NEUTRALIZE AUTOMOBILE EXHAUST GASES
I. L. Varshavskiy and R. V. Malov
Izdatel'stvo "Transport"
Moskva, 1968
p. 3-126
- 1 -
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Introduction
The 20th century is rightly called the century of cybernetics, atomic
energy, and space flights, but it remains first and foremost the century
of the automobile. There may now be no corner left in the world without
automobiles of the most different types, used for the most diverse pur-
poses.
The production of automobiles increases steadily. New, improved
models are being built for use in the most varied areas of the economy.
The world automobile pool of the capitalist countries of 1 January
1966 was characterized by the data listed in Table 1.
Table 1
Continent
Africa • « •
Oceania • • •
Western
Europe ....
America • • *
Total . . .
Automobile Type
Passenger
2.412.200
3.649.800
4.235.300
43.147.400
85.275.900
138.7-17. COO.
Trucks
909.200
1.0-14.900
5. 598. 900
7.121.500
18.393. 2CO
33.070.700
Buses
73.600
21 .500
367.400
3M.OOO
558.300
1 .33-1.800
Total
3.395.000
4.716.200
10.201. fOO
50.582.DHO
104.230.-:00
173.153.100
In 1970, the Soviet Union is planning to raise its production to
600,000-650,000 trucks and 700,000-800,000 passenger cars, i.e., more
than double the 1965 output.
The time has come to give serious consideration to the question of
whether the increase in the number of automobiles is dangerous for man,
considering the fact that the exhaust gases of automobile engines contain
large amounts of poisonous substances. How and to what extent is the at-
mosphere of populated areas and cities polluted by the toxic components of
exhaust gases and to what extent is this harmful to man?
The degree of atmospheric pollution by exhaust gases in cities may be
estimated from the following data.
In the major cities of the U.S.A., the average concentration of carbon
monoxide in atmospheric air is 30-50 mg/m3.* Of this, 60% is produced by
* Different standards for the maximum content of toxic substances in the atmosphere have been adopted
in different countries. They are also given in different units. Appendix 1 lists the sanitary standard"
for maximum contents of noxious substances adopted in the USSR and Appendix 2 gives a table for eonvertine
these units. 6
- 2 -
-------
automobile engines. The combustion of one ton of fuel in the engine's
cylinders, depending on the operating conditions, type of engine and its
adjustment, discharges from 150 to 800 kg of carbon monoxide into the
atmosphere.
Climatic conditions have different effects on the pollution of air with
exhaust gases and in some areas of the world are the cause of great distress
for the population. In London, for example, with its frequent fog and total
want of wind, several cases of mass poisoning of people by automobile exhausts
have been recorded in the last 15 years. One took place toward the end of
1952, when in a matter of a few days about 4000 people died, which considera-
bly exceeded the human losses of the 1866 cholera epidemic and was twice the
number of human victims of the tragic eruption of Vesuvius in 79 A.D., which
buried the antique cities of Pompeii and Herculaneum.
Over Los Angeles (USA), a haze called smog appears on sunny days. It
causes irritation of the eyes and upper respiratory tract in people, destroys
the vegetation, and decomposes the rubber of automobile tire casings. The
origin of the smog remained a puzzle for a long time, then it was found to
be caused by automobile exhaust gases. Under the influence of sunlight, the
various components of exhaust gases (^B^-type hydrocarbons) enter into
photochemical reactions with air and nitrogen oxides, forming a poisonous fog.
Whereas in the USA one of the factors responsible for the appearance
of smog is sunlight, in England, particularly in London, smog occurs on cloudy
days. Its nature is different here, but its formation is directly related
to the presence in air of a large amount of components of automobile exhausts.
The noxious substances present in exhaust gases are found not only in
gas samples taken from the atmosphere of urban thoroughfares but also in the
air of the neighboring public gardens and parks. In cities, cases have been
reported where carbon monoxide on the fourth-floor balcony of an apartment
building was present in a concentration of 28 mg/rn^ and, even in the apart-
ments themselves, in a concentration of 10-20 mg/m^.
Studies made in the last few years have shown that the exhaust gases
contain dangerous carcinogenic substances, in particular, benz(6)pyrene
i
If the engine operates on ethyl gasoline, lead compounds appear in the
exhaust gases. According to experimental data, from 40 to 85% of lead
compounds present in ethyl gasolines are discharged into the atmospheric air,
with the remainder depositing in the cylinders and exhaust system of the
engine. Experiments at the Moscow Scientific Research Institute of Hygiene
ira, Erisman have shown that the combustion of 1 kg of ethyl gasoline in GAZ-51
automobile's during idling discharges into the atmosphere 0.3 g of lead; at a
- 3 -
-------
traveling speed of 15 km/hr, 0.87 g, and at a traveling speed of 40 km/hr,
0.9 g of lead. Long-term studies have shown that in Switzerland, for example,
automobiles discharge about 165 tons of lead compounds into the air.
Automobiles and equipment driven by internal combustion engines are used
in the mining industry, in shafts, pits, deep quarries, industrial plants,
lumber yards, warehouses, tunnels, and other poorly ventilated facilities.
Here the purification of exhaust gases becomes an even more acute problem,
since, because of the heavy gas contamination of the atmosphere, cases of dis-
ruption of work in a number of quarries lasting up to 12 hours or more have
occurred. The use of special, powerful ventilating devices for the aeration
of these facilities has not yet solved the problem of effective control of
engine exhausts.
To eliminate the damage caused by automobile exhausts or decrease it is
a most pressing problem and one which today is completely solvable. The efforts
of automobile drivers, architects, city planners, medical technicians and staff
of the State Automobile Inspection are aimed at creating conditions of automo-
bile operation which will minimize the pollution of urban air with toxic gaseous
components of exhausts. In major Soviet cities with a heavy automobile traffic,
one-way streets have been introduced, bridges and under passes for pedestrians
have been constructed, and major work in urban planting of greenery is being
carried out. In Moscow, Leningrad and other large cities, the use of ethyl
gasoline has been prohibited. Special devices and systems reducing the forma-
tion of noxious substances or neutralizing those already formed are being devel-
oped. Much can be done by maintaining the engines in good technical condition
and by adjusting and operating them properly.
The program of the CPSU specifies that steps will be taken at the present
time to improve further the living conditions in cities and other populated
areas, including an all-out war on atmospheric pollution. It is already possi-
ble to ensure the presence of pure air in our cities. To this end, it is neces-
sary to determine and enact as soon as possible norms for the maximum content
of the main toxic components of exhaust gases; to construct and introduce into
the national economy new, improved instruments controlling the operation of en*
gines from the standpoint of the degree of pollution of air with exhaust gases;
to use them for the purpose of strictly observing the established norms, and
to take a number of steps toward decreasing the toxicity of the aerosols dis-
charged into the atmosphere.
-------
Chapter I
EXHAUST GASES OF AUTOMOBILE ENGINES
1. Combustion of Fuel in Engines
All internal combustion engines are divided into engines with external
and internal mixing. They form two groups: the first consists of carbure-
tor engines, and the second, of diesel engines.
In carburetor engines, the burned fuel is fed into the working cylinder
in the form of a ready mixture with air. In gas operation, the mixture is
formed in a special mixer. In liquid fuel operation (gasoline is usually
employed), the mixing takes place by introducing the atomized fuel into a
stream of air entering the cylinder. This is done either directly in the
intake manifold by means of injectors or in a special device, the carburetor.
In all cases, a ready (carburized) mixture of a certain composition enters
the cylinder. The mixture is compressed by a piston and ignited by an
electric spark plug. The flame spreads from a local, quaai-point source
through the entire volume of the fuel-air charge.
All carburetor engines operate on the Otto cycle. Ideally, combustion
in these engines should take place at a constant volume of the mixture,
i.e., practically instantaneously. Actually, however, the piston is in
continuous motion, and the combustion process occupies an appreciable fraction
of the cycle. This fraction depends on many factors, but it is determined
chiefly by the composition of the mixture.
In describing the mixture composition, use is made of the concept of
the excess air coefficient <2, representing the ratio of the amount of air
actually entering the cylinder to the amount theoretically required for
complete combustion of a given amount of fuel.
Experiments have shown that, other conditions being equal, the maximum
combustion rate, takes place at a = 0.85-0.9. Thus, in order to bring the
actual working cycle of an engine as close as possible to the ideal Otto
cycle, i.e., to increase the combustion rate, the excess air coefficient
should be within the indicated range. Then the engine power reaches maximum
values, but the fuel combustion takes place with an insufficient amount of
oxygen. As a result, one finds that it is the working cycle of carburetor
engines that predetermines an incomplete combustion of fuel.
The fuels used in engines constitute a complex mixture of the most
diverse compounds of carbon and hydrogen referred to by the collective name
of hydrocarbons. An insufficient amount of oxygen during oxidation causes
-. 5 -
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the presence of toxic products of incomplete fuel combustion in the exhaust
gases: carbon monoxide (CO), oxygen-containing organic compounds such as
aldehydes (formaldehyde, acetaldehyde, acrolein, etc.), hydrocarbons in their
initial form (ethane, ethylene, propane, isobutane, acetylene, etc.), carbon
black, and others.
It should not be assumed that when a - 1 or even a > 1, no products
of incomplete combustion will be formed. The brief time interval occupied
by the combustion process, the presence in the working mixture of gases left
over from the preceding cycle which prevent the access of oxygen to the fuel
molecules, and other factors prevent the complete combustion of fuel to the
end products. As a result, carbon monoxide alone is present in amounts of
up to 12% by volume in the exhaust gases of carburetor engines under certain
operating conditions.
High temperatures and pressures are generated in the engine cylinders
during the combustion of fuel. The nitrogen present in the composition of
air does not remain inert under these conditions. After the bulk of the
fuel has burned, it begins to react with the residual oxygen, forming nitrogen
oxides, which also are strong toxic substances.
All liquid* fuels including gasolines contain a certain amount of sulfur.
According to COST (All-Union State Standard) 2086-56, for example, up to 0.10%
sulfur is allowed in a-74 gasoline, and up to 0.15% in A-66, AZ-66, A-72 and
A-76 gasolines. If the gasolines are produced by refineries having no sulfur-
removing equipment, COST permits a sulfur content of up to 0.3% for A-66 and
AZ-66 gasolines. The sulfur present in the fuels reacts with oxygen and
hydrogen, forming sulfur dioxide and hydrogen sulfide, which are toxic.
The process of fuel combustion may proceed under two typical conditions:
normal and knocking. During knocking, near the walls of the cylinder the
combustion occurs almost instantaneously, causing an abrupt increase followed
by strong fluctuations of the pressure. As a result, a characteristic knock
appears in the engine, and the content of nitrogen oxide in the exhaust
gases increases sharply. The probability of knocking may be decreased by
lowering the compression ratio of the engine, but this affects its power and
efficiency, since the thermal efficiency of the Otto cycle is
1
where e is the compression ratio;
k is the adiabatic exponent (a constant).
The knocking tendency of an engine strongly depends on the quality of
the fuel, whose stability to knocking is characterized by the octane number.
The larger this number,the greater the stability of the fuel to knocking.
- 6 -
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Special additives called antiknock agents are added to gasolines to raise
their octane numbers.
The most common antiknock agent is ethyl fluid with tetraethyllead
(TEL). TEL is a highly toxic substance requiring careful handling. On
entering an engine Cylinder, TEL reacts with oxygen, forming lead compounds.
Recently, under the direction of Academician A. N. Nesmeyanov, a new
antiknock agent less toxic than TEL has been developed - cyclopentaldienyltri-
carbonylmanganese (CTM). Its use in the production of automobile gasolines
is promising. The addition of the manganese additive to gasolines also
decreases the carbon monoxide content of the exhaust gases.
The conditions of fuel combustion in the cylinder promote the formation
of carbon-hydrogen compounds of complex structure, some of which are
carcinogenic, i.e., produce cancers. They are present in the gaseous or li-
quid state in the exhaust gases. If the composition of the gases includes
soot, the carcinogenic substances deposit on its particles. It is in this
form that they are most dangerous, since they can be retained in the human
lungs.
The difference between diesel and carburetor engines is that in the
former, only the clean air necessary for the combustion enters the cylinders
and is then burned therein. The fuel is supplied separately by a nozzle as
the piston approaches the upper extreme position. At that moment the air
pressure in the cylinder is 30-35 kg/cm2, and the temperature is 500-600°C.
Under such conditions, the fuel ignites spontaneously and burns. Fart of
this process takes place while the volume undergoes little change (in the
ideal case when V=const), and part at a nearly constant pressure. This is
the so-called Sabatier cycle.
The process of fuel combustion in diesel engines is very complex.
Processes of vaporization of fuel droplets and oxidation of their vapors,
both partial and total, take place simultaneously in the cylinder. After-
burning of individual fuel droplets takes place during the expansion.
Diesel engines operate at a = 1.4-1.7, and sometimes at a > 2.
The carbon monoxide content of the exhaust gases of a diesel engine is
therefore slight. However, because of the imperfection of the process,
carbon monoxide is present in the gases, its quantity amounting to tenths
of one percent by volume. Aldehydes are present in the exhaust gases,
since their formation is involved in the preparation of the mixture for
ignition. Afterburning of the individual droplets during the exhaust, taking
place at lower pressures and temperatures, leads to the formation of large
amounts of carbon black, which causes the black color of the exhaust gases of
- 7 -
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diesel engines, particularly at large loads. Because of the large amount of
oxygen and nitrogen in the gases, and the fact that the process takes place
at high temperatures and pressures, the conditions for the formation of
nitrogen oxides in diesel engines are more favorable than in carburetor engines.
They are also more favorable for the formation of sulfur dioxide, since the
maximum sulfur content in diesel fuels specified by COST 4749-49 and COST 305-42
for all brands is limited to 0.2% by weight, and oxygen is present in excess.
The conditions are also favor the formation of carcinogenic substances.
There are no lead compounds present in the exhaust gases of diesel engines
since the additives used in diesel fuels contain no lead.
2. Composition of Exhaust Gases
The exhaust gases of internal combustion engines have a large number
of components. Studies made in the Soviet Union have shown that the gases
contain over 60 different substances. The composition of the gases includes;
Nitrogen (N2) as the main part of the exhaust gases;
Oxygen (02);
Carbon dioxide (C02), an end product of oxidation;
Water vapor (H20), an end product of oxidation;
Hydrogen (H2);
Carbon monoxide (CO), a product of incomplete fuel combustion;
Nitrogen oxides, present mainly in the form of two oxides: nitric oxide
(NO) and nitrogen dioxide (N02);
Sulfur dioxide (S02) and hydrogen sulfied (H2S), inorganic gases
present in exhaust gases when sulfur fuels are used;
Oxygen-containing organic compounds, chiefly aldehydes: formaldehyde
(ECHO), acrolein (CH2-CH-CHO), acetaldehyde (CHsCHO), etc;
Hydrocarbons: ethane (C2Hg), methane (CH,), ethylene (CH2-CH2), benzene
(C6Hg), propane (CaHg), acetylene (CH-CH), toluene (CgHsCHs), m-xylene
(C6H4(CH3)2), n-butane (C^HIQ), n-nonane (C9H20), etc;
Lead (Fb) or manganese (mn) and their compounds if antiknock additives
are used;
Complex aromatic hydrocarbons of polycyclic structure (pyrene, anthracene,
benzpyrene, etc.);
Soot.
These substances are present in the exhausts in the gaseous, liquid and
solid states.
- 8 -
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Fig. 1. Soot taken from exhaust gases of
YaAZ-204 engine.
Soot should be considered separately. When the soot content in 1 m of
exhaust gases is 130 rag, they become visible, and when its content is 600 mg
per m3, they turn a medium black. Studies have shown that the majority of
soot particles filtered out of black smoke (87-98%), are in the 0.04-0.50 Mm
range. They in turn consist of finer particles measuring 0.015-0.170 ym.
The particles are round and oval in shape, Individual particles combine
into groups consisting of two, ten, and more particles, and sometimes forming
chains of up to 30 particles, or collect into aggregates of 100-1000
particles.
In accordance with the results of studies conducted at the Central Scienti-
fic Research and Experimental Design Laboratory for Exhaust Purification and
Problems of Automobile and Tractor Power Engineering (LANE), Fig. 1 shows a
sample of soot retained in an exhaust pipe. The photograph was made with an
electron microscope at a total magnification of 35,000. The size distribu-
tion of the soot particles is shown in Fig. 2. The specific surface of all
the soot particles ranges up to 75 m^ per g. Since the visible exhaust
gases correspond to a soot content of 130 mg per mP of gas, it means that the
same volume has a surface area of up to 10 m^ on which carcinogenic substances
can deposit, and that there is an area of up to 45 rsr for exhaust gases of
medium blackness. Therefore, automobile soot is dangerous not only as a
mechanical contaminant for human lungs, but also as an active carrier of
carcinogens.
_ Q _
-------
200 300 tOO 500 BOO 700 BOO
Particle size, A.
Fig. 2. Graphic of distribution of
soot particles present in exhaust
gases of YaAZ-204 engine as a function
of size.
A tentative quantitative composition of exhaust gases is given in Table 2.
Table 2
Components
Nitrogen
Oxyten
Water Vapor
Carbon Dioxide
Carbon. Monoxide
•Nitrogen Oxide
Hydrocarbons
Aldehydes
Soot
Benzpyrene •
Gas Composition, % by Volume
Carburetor
Engines
74—77
0.3—8,0
3,0—5,5
5,0—12,0
5,0—10,0
0.0—0,8
0,2—3,0
0.0-0,2
0,0-0,04 .g/m3
prtolO— 20 flj/3
Diesel Engines
76—78
2—18
0,5 — 4,0
1,0 —10,0
0,01— 0,50
0.0002—0,5000
0.009—0,500
0,001—0,009
0.01— 1,10 g/m5
up to 10 •(/.«*
Remark
Nontoxic
fox *•'
Carcinogenic
Note, y (gamma) is one millionth of a gram.
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The above table is not sufficiently representative, since the composition
of the gases substantially depends on the type of fuel used, its additives,
operating conditions of the engine, its technical condition, conditions of
motion of the automobile, and other factors. Fig. 3 shows the relative
dependence of the components of exhaust gases from a carburetor engine as a
function of the load, and Fig. 4 as a function of the motion of the
"Moskvich-408" automobile traveling over a hard-surface level road. It is
obvious from the figures that the content of the individual componenets may
change severalfold. For example, when the'Moskvich-408" travels at 70 km/hr,
the exhaust gases of its engine contain 0.2-0.3% carbon monoxide. At a
traveling speed of 120 km/hr, this value increases to 67o, and when the engine
is idling, it rises to 7%.
100
91
11
IS
1C
n
10
t
s
4
' t
0
Kit re t€ i
aroon uiox:
de
ides
dde
10 20
*0 SO
Load) $Mni
100
Fig. J>. Changes of the Inter-
relationship of the components
of exhaust gasfs from a car-
buretor engine vs. load.
a
to
troget
"Carbon
)io)iitie
ioa
S5
N
18
IB
IU
12
10
g
6
d
2
0 30 SO \ 90 120
Traveling speed V, km/hr
Fig. 4. Changes in the interre-
lationship of the components of
exhaust gases from engine of
"Moskvich-408f automobile vs.
traveling speed.
Particularly undesirable are forced idling conditions.
A case of this type occurs during engine braking. The amount of carbon
monoxide in the exhaust gases during the engine's operation under such condi-
tions increases sharply, reaching 12% by volume in some cases. For example,
the ZIL 130 engine may discharge up to 40-45 kg of CO per hour in this case.*
* At a speed of 50-55 km/hr, the discharge of carbon monoxide into the atmosphere from a ZIL-130
engine amounts to about 1.5 kg/hr, and an increase of the velocity to 70 km/hr or decrease to 30 km/hr
raises the discharge by a factor of approximately 2.5.
- 11 -
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Jo
•3
Brt
O CO
0
ees ojo aa ON o.is ox ojs am
-------
In acute carbon monoxide poisoning, man experiences extreme weakness,
tinnitus, dizziness, headaches, precardial pain, nausea, and sometimes
vomiting. He loses contact with the surroundings; some people become
drowsy, others excited. Sometimes there are convulsions and frequently the
victim loses consciousness.
In amounts• above 0.01% by volume, carbon monoxide can cause symptoms
of poisoning, and when it is present in the atmosphere in the amount of 0.02%,
its inhalation for several hours :may cause a light poisoning. Inhalation of
air containing 0.12% CO in the course of 30 min causes a weak heartbeat, diz-
ziness, after' 1.5 hr, and headache, nausea and partial loss of consciousness
after 2 hr. A 0.20-0.25% carbon monoxide concentration in air causes
fainting after 30 min.
Nitrogen oxides. Engine exhausts contain two kinds of nitrogen oxides;
nitric oxide (NO), a colorless gas, and nitrogen dioxide (IK^), a reddish-
brown gas with a characteristic odor. When they enter the human body, they
combine with water, forming compounds of nitric and nitrous acids in the
respiratory tract. Poisoning with nitrogen oxides is characterized by
the presence of a latent period: a person who feels normal during work with
dangerous concentrations of nitrogen oxide becomes seriously ill later.
The inhalation of 0.01% nitrogen oxides with air for 0.5-1.0 hr may
cause a serious illness.
In their effect on the human organism, nitrogen oxides are approximately
10 times as dangerous as carbon monoxide.
Nitrogen oxides are irritating to the mucous membranes of the eyes,
nose and mouth.
In addition, nitrogen oxides participate in processes leading to the
formation of smog.
Usually, for convenience of comparison of nitrogen oxide contents,
both gases are treated in toto with conversion to ^05 according to the number
of nitrogen atoms.
Aldehydes are present in the exhaust gases mainly in the form of
formaldehyde and acrolein. Under ordinary conditions, formaldehyde is a
gas with a pungent and unpleasant odor. On cooling, it condenses to a liquid
boiling at -21°C; it irritates all the mucous membranes and injures the
central nervous system. Both acute and chronic poisoning with gaseous
formaldehyde causes inflammation of the respiratory organs.
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When formaldehyde is present in the atmosphere in a concentration of 0.007%,
a light irritation of the respiratory tract and mucous membranes of the eyes
and nose is observed, and at a concentration of 0,18%, a marked irritation
takes place. Formaldehyde is detected by its pungent odor when present in
air in the amount of 0.0002 mg/1.
Acrolein is a gas & liquid at temperatures below 52.5°C.) with the
pungent, irritating odor of burned fats and oils. It is very poisonous. Its
vapor is heavier than air. It has a strong irritating effect on the mucous
membranes, and a general toxic effect. A content of 0.002% acrolein in the
atmosphere is intolerable, 0.00037. is difficult to tolerate, and 0.00008 is
not dangerous for man.
Carbon dioxide. This gas is without color or odor. It is heavier than
air and collects in low areas. A high content of carbon dioxide in the
atmosphere causes rapid breathing in man. It becomes dangerous to life only
at concentrations of 20-25% by volume.
In areas where the accumulation of such high local concentrations of
carbon dioxide in the .atmosphere.is not likely (open spaces), carbon dioxide
should not be classified as a toxic gas.
Sulfur dioxide and hydrogen sulfide have a strong irritating effect on
the mucous membrane of the .eyes and olfactory organs, destroy plants, and
participate in the formation of smogs.
Hydrocarbons. Although the hydrocarbons themselves are toxic, under
the influence of sunlight they enter into further reactions with nitrogen
oxides, forming ozone and peroxides. The latter cause irritation of the eyes,
throat, and nose, and destroy:plants.
Carcinogens. Among the carcinogens present in exhaust gases are benz(o)-
pyrene and many others. Benz(o)pyrene is particularly dangerous.
Studies show that the formation of a malignant tumor requires direct
contact between the carcinogen and live tissues, and the tumor appears, as
a rule, at the site of this contact.
Direct contact can be achieved in practice by smearing various parts of
the body with the carcinogen or by injecting it internally. For this reason,
it was believed for a long time that the inhalation of carcinogenic substances
did not cause lung cancer. Later, however, it was found that when carcinogens
deposited on powder particles enter the lungs, they are given the opportunity
to be retained in the body and to come in contact with its tissues. In the
exhaust gases, the carcinogen carriers may be soot particles. Once a
carcinogen enters the human body, it remains there for the rest of the
- 14 -
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individual's life. Its accumulation up to dangerous concentrations takes
place gradually. This is one of the reasons why despite a general rise in
the standard of living of all mankind and a lengthening of the average human
lifespan, the vigorous development of industry and motor transport in parti-
cular have resulted in an increase of the death rate from lung cancer. In
England, for example, during the period 1900-1952, the cancer death rate
increased 43-fold. The content of carcinogenic substances in air has no
sanitary norms and should have none. These substances should not be present
in air altogether, and it is therefore necessary to limit their discharges.
Soot, like any other foreign dust, contaminates the respiratory tract,
irritates it, and may cause chronic affections of the nasopharynx. On
reaching the lungs, it also causes pulmonary diseases. However, the chief
danger of soot is that it may carry carcinogens.
Lead compounds, which are present in exhaust gases when fluid with TEL
is used, constitute poisons for all the organs and tissues of the body. They
have a particularly adverse effect on the organism of children. Even a
slight poisoning causes a retarded physical development, growth, and weight
gain; nervous diseases appear, and the amount of hemoglobin and erythrocytes
in the blood decreases.
The danger of poisoning with lead compounds is increased by the fact
that as time passes, lead does not escape from the body but, like the carcino-
gens, accumulates up to dangerous concentrations. Lead compounds can enter
the body through the respiratory organs as well as through the skin. As a
result, the use of ethyl gasoline has been prohibited in a number of cities
of the USSR.
The hydrocarbon fuels themselves are also toxic, particularly gasolines,
or more accurately, their vapors. The degree of toxicity of gasoline vapors
may be estimated from the following data: the maximum permissible mean daily
concentration of carbon monoxide in air is 1 mg/m3, and that of gasoline vapor,
1.5 mg/n?.
4. Evaluation of the Toxicity of Exhaust Gases
It is clear from the preceding section that each toxic componenet of
exhaust gases affects the human organism in different ways. The problem is
to evaluate which are worse: the exhaust gases of carburetor engines or
those of diesel engines, idling conditions or maximum loads, the use of
ethyl fluid with TEL or CTM as antiknock additives, etc., when one considers
that in each specific case the gases contain different amounts of individual
substances.
- 15 -
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Frequently in evaluating the harmful action of engine exhausts, use
is made of figures showing the content of one or another toxic component.
However, this is fundamentally incorrect. Thus, for example, one finds
that the small amount of exhausts from the GAZ-20 engine at a rotational
speed of the crankshaft of 1600 rpm, developing a power of 1 hp and con-
taining 3% carbon monoxide by volume in the exhaust gases, contaminates
atmospheric air to the same extent as the several-times larger volume of
exhaust gases of the "Moskvich-401" automobile engine, which develops a
power of up to 14 hp and whose composition of the exhaust gases contains
carbon monoxide in the same concentration of 3%. The contamination of air
with engine exhausts should not be evaluated from the percent composition
of toxic components in the exhaust gases but from the total amount of the
discharged components, taking into account the degree of harmful action of
each. In order to take into consideration the operating conditions of the
engine as well, this quantity should be expressed per unit of power developed
by the engine.
Since 1962, at the Central Scientific Research and Experimental Design
Laboratory of Exhaust Purification and Problems of Automobile and Tractor
Power Engineering (LANE) in evaluating the harmful action of the operation
of a specific engine for given operating conditions, a parameter expressing
the specific toxicity of exhaust gases has been used which is represented
by the expression
llj II
where GJ is the discharge of the given toxic substance "i
from the engine per unit time;
Ne is the effective power developed by the engine;
VCO» vi are sanitary norms of the maximum permissible contents
of carbon monoxide and substance i in air.
The right side of this formula contains the sum of the amounts of all
the noxious substances discharged by the engine during a given time interval
and expressed per unit power, V» £L In order to take into account the dif-
rw-'
ferent toxicities of the substances, each of them is expressed in terms of
the best-studied substance, carbon monoxide, by the ratio —co_ t which shows
'VJ
how many times CO is more or less dangerous than substance i. Since the
USSR has adopted sanitary norms which ensure complete safety to man in a
contaminated atmosphere, standardization using the proposed parameter is the
answer to the problem of evaluating an engine from the standpoint of the
toxicity of its exhaust gases.
- 16 -
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The magnitude of the specific toxicity of exhaust gases makes it possible
to evaluate the degree Of harmful action of the exhausts of any engine
operating under any conditions except idling. In the latter case, Ne=0, and
according to the formula given above, qe loses meaning. Therefore, in
estimating the degree of toxicity of engine exhausts in the case of idling,
a special conventional quantity called the conventional specific toxicity of
idling is introduced. It differs from the specific toxicity of engine exhausts
in that it does not refer to the power developed by the engine, but to the
maximum power that the given engine can develop. The mathematical formula
for its determination is
'max
It now becomes possible to evaluate the degree of general contamination
of atmospheric air with the exhaust gases of any engine operating under any
conditions.
Let us assume, for example, that a carburetor engine devloping a power
of 20 hp discharges the following composition of exhaust gases in the course
of an hour: 30 g of carbon monoxide, 0.9 g of aldehydes, 2.5 g of hydrocarbons
and 0.9 g of nitrogen oxides. Then, taking the following approved sanitary
norms: for CO VQQ w~l mg/m , for aldehydes ^ald = 0.1 rog/111 » for hydro-
carbons Vhyd = 2 mg/m , for nitrogen oxides vniox =0.1 mg/rn^, in the
case of an engine operating under certain given conditions, we have the
following values of the specific toxicity of the exhaust gases:
qg • 1.0 x 30 + 1.0 x 0.9 + 1.0 x 2.5 + 1.0 x 0.9 _ 2.4625 g/hp hr
1.0 x 20 0.1 x 20 2.0 x 20 0.1 x 20
The concept of specific toxicity of exhaust gases permits not only
an evaluation of the engine from the standpoint of contamination of the
atmosphere, but also the determination of the fraction which each toxic
component "contributes" to the overall toxicity of the gases of a specific
engine .
Indeed, if in the example under consideration qe = 2.4625 g/hp hr and
the specific toxicity of the exhaust gases for carbon monoxide alone is
this means that the carbon monoxide fraction in the overal toxicity is
correspondingly equal to
Fig. 6 shows a graph of the distribution of toxicity of carburetor engine
exhausts according to componenets as a function of the excess air coefficient a
- 17 -
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plotted by using the above method. It is evident from the graph that for
rich mixtures, the main toxic component is CO, whose fraction in the overall
toxicity at a = 0.85 is as high as 95%. For lean mixtures, where no
deficiency of oxygen occurs during the combustion, and the conditions are
unfavorable for the formatibn of carbon monoxide, the chief toxic components
are nitrogen oxides.
Fig. 6.
Toxicity (0 of engine exhausts
versus excess air coefficient (X
48 0,9 1,0 1.1
The indicated graph permits the following practical conclusion. If
the engine is adjusted for a rich mixture, then in developing ways of
decreasing the total toxicity of exhaust gases it is necessary first of all
to direct one's attention to the neutralization of carbon monoxide. In
operation on lean mixtures, the main emphasis should be on reducing the
concentration of nitrogen oxides.
wo
80
60
40
20
•
1
>
c
3
4
fc-
.
^
-X.
•
•*>
Fig. 7.
Toxicity (i) of diesel engine exhausts
versus number of revolutions of
crankshaft.
600
BOO
' 1000 n,rpm
- 18 -
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In diesel engines the situation is different. This is evident from
Fig. 7 and 8, which show the distributions of the toxicity of diesel engine
exhaiists over the components as a function of the rotational speed of the
crankshaft (F.ig. 7) and load (Fig. 8). * In operation with a high-speed
external characteristic (see Fig. 7), the main part in the toxicity is played
by soot (75-85%). The relationship changes with the load: the fraction of
nitrogen oxides accounts for 55-70% of the overall toxicity, and the soot
becomes secondary, although its toxicity continues to account for 30-40%.
In both cases, the fraction of carbon monoxide in the overall toxicity is slight,
as is that of the other noxious substances.
Fig. 8. Toxicity co of diesel engine
exhaust vs. load.
It follows that in neutralizing the exhausts of diesel engines, it is
necessary to control primarily the soot and nitrogen oxides.
The indicated graphs do not show carcinogens or lead compounds. Since
carcinogens and lead compounds are not eliminated from the human body, accumu-
lating in the latter up to dangerous concentrations, their presence in any,
even slight, concentrations is dangerqus for man.
* The graphs were plotted under the assumption that the entire mass of the soot discharged remains
in the air for a long tine.
- 19 -
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It should be noted that Soviet laws have prohibited the use of ethyl fluid
with TEL as an antiknock additive in the country's large cities.
The specific toxicity parameters permit an objective evaluation of the
quality of engines from the standpoint of their contamination of the atmosphere
both for engines being operated and those having undergone repair, and even
for new ones being finished in plants.
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Chapter II
CONTROL OF EXHAUST GASES
1. Analysis of Exhaust Gases
Complete chemical analysis of the composition of gas and air samples for
their content of certain components is carried out in specialized laboratories.
The analysis is preceded by the collection of gas samples. The samples are
collected in special containers whose type is determined by the purpose of the
analysis. The gas may be passed for a certain period of time through absorbing
instruments in which the substance being determined is trapped, or it may be
caught in gas collectors (aspirators). To enable the gas to reach the gas
collectors independently, the air in the latter is partly evacuated, i. e., a
vacuum of 10-15 mm Hg is produced. Occasionally, the gas collectors used are
rubber balloons that are filled with the gas by means of squeeze bulbs.
For each specific case, a special health and sanitation commission has
recommended conditions of sampling for the determination of the highest single
and mean daily permissible concentrations. In the study of the toxicity of
automobile exhausts, in order to avoid their dilution by atmospheric air, the
samples are collected directly from the exhaust pipes of the engines.
The samples sent to the laboratory are analyzed. The most diverse methods
of analytical chemistry and corresponding instruments are used in the analysis.
The simplest and yet adequately sensitive is the colorimetric method.
The method is based on the ability of solutions of certain substances to
acquire a color when acted upon by chemical reagents. The color intensity of
the solution increases in proportion to the amount of substance it contains.
In order to determine the amount of the substance studied from the color of the
solution, the intensity of this color is compared with that of the solution
containing a known concentration of the same substance.
For example, in the determination of formaldehyde in a gas, it is first
dissolved in water (by pouring water into the flask containing the gas), a part
of the solution is poured into a test tube, fuchsin sulfurous acid (Schiff s
reagent) is added, and the solution is agitated and allowed to stand for 1 hr.
A small amount of sulfuric acid is then added to the test tube, and the solution
turns blue. This color of the sample is compared with a standard scale consist-
ing of seven samples containing solutions with known amounts of formaldehyde.
Despite what might at first glance be thought to be the inaccuracy of this
method, its sensitivity is sufficiently high. For formaldehyde, it amounts to
1 Y in a volume of 5 ml of solution; for acrolein, 0.002 rag in a volume of 2 ml;
and for nitrogen oxides, 0.05 Y ifl a volume of 3.5 ml.
Since the accuracy of the method depends to some extent on the eye of the
- 21 -
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laboratory technician, i. e., his ability to compare correctly the color inten-
sities, the photocolorimetric method has recently begun to be employed. It
differs from the above-described technique in that light whose intensity is
recorded with a photoelectric cell is passed through the test tubes containing
the samples. The concentration of the substance studied is determined from the
magnitude of the photocurrent. This method is undeniably more accurate and
faster, but it also has disadvantages. For example, at very low concentrations
and hence, weak intensities, the photoelectric cell reacts weakly to the color
change.
The carbon monoxide content of the gases under laboratory conditions is
determined by means of gas analyzers. The TG-5 instrument (Fig. 9) is very
common in the analysis of gases with a low CO content. This gas analyzer con-
sists of two parts: purification and analysis. In the purification part,
foreign impurities are removed from the gas. In the analysis part, carbon
monoxide is burned in a special column on an incandescent platinum spiral. The
amount of carbon dioxide formed by the combustion of CO is then determined
chemically, and from the amount obtained, the carbon monoxide content of the
initial sample is calculated. The sensitivity of the gas analyzer ranges from
0.0014 mg to 0.0028 mg. Operation of the instrument requires a certain experience
and qualifications on the part of the laboratory technician.
1. hs.sfl&isfe
r jtassr*T»M
' ^ 7
; .._..,-.
Fig. 9. The TG-5 Gas Analyzer.
If carbon monoxide is present in the gaseous mixture in concentrations
amounting to a few percent by volume, COST 5439-56 recommends an instrument of
model VTI-2 for the determination of the CO content. In addition to carbon
monoxide, analysis with this instrument permits the determination in the gaseous
- 22 -
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mixture of individual concentrations of oxygen, nitrogen, methane, total concen-
trations of carbon dioxide, sulfur dioxide, hydrogen sulfide and other acid
gases, and also unsaturated hydrocarbons (Cn^) and hydrogen plus saturated
hydrocarbons (CnH2m+2)«
The principle of operation of the instrument is based on a selective
absorption of individual components of the gases by liquid substances. A given
volume of gas is pumped through a liquid absorber, and an individual component
of the gas is absorbed.
The content of this component in the mixture is determined from the change
in the volume of the gas.
In the determination of the hydrogen content plus saturated hydrocarbons
and methane, the gas is additionally burned over copper oxide.
The accuracy of the instrument in the determination by the absorption method
(analysis for the content of acid gases, CnHm, 02) is 0.2%, and in the analysis
by the combustion method (for the content of H2, CnH2m+2> methane CH4), 0.37«.
Operation of the instrument requires certain qualifications on the part of
the laboratory technician.
Recently, automatic and semiautomatic recording instruments for gas analysis
have appeared in laboratory practice. They include primarily chromatographs and
optico-acoustic gas analyzers. Some instruments include electronic parts. In
practice, they have thus far been used mostly in specialized laboratories.
Analysis of gas samples for the content of soot and various solids is
carried out in the following manner. A given volume of gas is passed through a
filter made of paper or a special material packed in a cartridge. A perfect
filter of brand BF, also called the Petryanov filter, is frequently used. At
high temperatures of the exhaust gases, the filter material used may also be
high-temperature ultrafine fiberglass. The solid particles are trapped on the
filter.
The filter material darkens. The degree of darkening of the filter is
compared with a standard scale, from which the solid particle content of the
gas is determined. This method is called the Bosch method.
The components held on the filter material can be removed by chemical means.
Analysis then gives an accurate content of the studied substance present in the
gas. In particular, this method is used .to determine the content of carcinogens
present in the liquid and solid states in the exhaust gases.
A second method of indirect determination of the content of solid particles
in a gas is the Hartridge method. This method is used to determine the smoke
- 23 -
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content of exhaust gases. It essentially consists of shining light through a
definite volume of gas. Part of the light flux will of course be blocked by
the particles suspended in the gas and will not reach the recording cell. From
the difference between the emitted light flux and the flux recorded by the
instrument one can determine the smoke content of the exhaust gases and indirect-
ly the content of particles suspended in the gas.
Fig. 10 gives a comparison of the Bosch and Hartridge units. Since the
Bosch instruments measure the actual amount of particles suspended in the gas,
and the Hartridge instruments the optical density of a given volume of aerosol,
this density being only partly dependent on the dispersed phase, a considerable
scatter is observed on passing from one set of units to the other. This accounts
for the replacement of a curve by an area in the lower part of the figure.
For carburetor engines, the necessity of standardizing the content of carbon
monoxide in exhaust gases has been universally recognized. Standardization of
hydrocarbon emission has been adopted in the U.S.A., where limitations on
nitrogen oxides are also being proposed.
In Europe, the emission of hydrocarbons is determined as a checking figure
supplementary to the data on CO.
For diesel engines, norms for the soot content of exhaust gases have been
the only ones introduced thus far.
a
o
ui
s
CO
ui
1
•o
g
ec
Fig. 10. Comparison of readings of
the Bosch and Hartndge scales.
- 24 -
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The standardization is based on the so-called "driving cycle." The auto-
mobile is operated sucessively in all the runs specified by the cycle. During
the operation, samples of exhaust gas are collected and analyzed for the con-
tent of the components being standardized. 'Data of the analysis are averaged
out, converted by means of special formulas, and a conclusion is reached
concerning the quality of the automobile from the standpoint of the toxicity
of its engine exhausts.
Driving cycles are worked out on the basis of studies of the conditions
of traffic flow in cities.
Two'types of driving cycles are distinguished, the American and the
European. The American driving cycle (septuple repetition of 7-run cycle,
total automobile testing time 15 min) is shown in Table 3, and the European
driving cycle (quadruple repetition of a twenty-six-run cycle, total auto-
mobile testing time 13 min) is shown in Table 4.
For automobiles operated in cities of the USSR, LANE has developed its
own driving cycle which takes into consideration the characteristics of
urban transport. This cycle is being extensively studies at the present time.
Special'driving cycles exist for automobiles used in open quarries, mines,
tunnels, etc.
All the tests are carried out on special stands with revolving drums.
In the USSR, the first such stand was built by LANE at the First Automobile
Complex of the Main Moscow Administration of Motorized Transport.
Table 3
Bun of Automobile •
Idling engine
Acceleration of Automobile
Constant Speed
Deceleration of Automobile
Constant Speed
Acceleration of Automobile
Deceleration of Automobile
Speed,-.
km/hr
_
0^48
48
48-24
24
24—80
80—0
• Acceler-
.ation
m/secZ
_
0,97
0,64
_
0,53
0,9
Duration
of run,
sec
20
14
15
11
15
29
25
ACCUJM-.
lated tun
sec
20
34
49
60
75
104
129
- 25 -
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Table
Xutomobile Run
Idling
Acceleration of automobile
Constant speed
Deceleration of automobile
Deceleration with disengaged engine
Idling
Acceleration of automobile
Gear shifting
Acceleration of automobile
Constant speed
Deceleration of automobile
Deceleration with disengaged engine
Idling
Acceleration of automobile
Gear shifting
Acceleration of automobile
Constant speed
Gear shifting
Acceleration of automobile
Constant speed
Deceleration of automobile
Constant speed
Gear shifting
Deceleration of automobile
Deceleration with disengaged engine
Idling
11
1
1
1
—
. —
1
1-2
2
2
2
—
__
1
1—2
2
2
2-3
3
3
3
3
3-2
2
—
iz
fir
0—15
15
15-iO
10—0
—
0-15
15—30
30
30—10
10-0
—
0—15
15-35
35
35^EO
50
50-35
35
35
35—10
10-0
—
Accelera-
tion,ni/sec2
_
1,04
0,69
0,92
—
0,83
—
0,83
0,69
0,92
_
0,83
—
0,02
_
—
0,52-
___
0,52
.^
0,99
0,92
—
8.
.r+H
|E
stt* <£
7
4
8
2
3
21
5
2
5
14
8
3
21
5
2
9
10
2
8
12
8
13
2
7
3
11
Accumulated
time, sec
7
11
19
21
24
45
50
52
57
71
79
82
103
108
110
119
129
131
139
151
159
172
174
181
184
195
2. Rapid Analysis of Exhaust Gases
In practice, a complete analysis of the composition of exhaust gases is
performed only in testing new engines and special devices for neutralizing
gases, and also when required by the staff of the sanitary inspection. Some-
times it is necessary to make a rapid check of the content of the main toxic
components of a gas in order to get an idea of the adjustment of an engine and
its technical condition. As was pointed out in §4 of Chapter I, such components
are: carbon monoxide for carburetor engines, and soot for diesel engines. In
the Soviet Union, portable instruments have been developed for such analyses.
One such portable instrument is an I-SO indicator constructed by the Scientific
Research Institute for Motor Transport for determining the permissible content
of the total amount of carbon monoxide and hydrocarbons in automobile exhausts
(Pig. 11).
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Fig. 11. I-SO exhaust indicator.
The indicator can operate normally at ambient air temperatures of up to
40° C, and a relative humidity of up to 80%. It weighs 3.5 kg.; the external
dimensions are 206 x 85 x 128 mm. The concentration of toxic components is
measured directly from the automobile.
The indicator can measure the concentration of carbon monoxide plus
hydrocarbons in the range from 0 to 10% by volume. Its comparatively low
sensitivity does not permit its use for the analysis of the composition of
diesel engine exhausts, in which the content of carbon monoxide and hydrocarbons
is relatively low.
tealysis
Fig. 12. Electric diagram of portable
1-90 exhaust indicator.
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The operation of the indicator is based on the measurement of the tempera-
ture elevation of a platinum wire preheated to 400° C, on the surface of which
a catalytic combustion (i. g., accelerated by the platinum catalyst) of carbon
monoxide and hydrocarbons takes place. The main part of the electric circuit
of the instrument (Fig. 12) is an unbalanced direct current bridge to the two
arms of which (RI and R2) platinum elements are connected. One of the arms
(Rl) is the working element and is placed in the chamber through -which the ex-
haust gases are passing, and the second is the reference element (R2) enclosed
in an insulated chamber filled with air. When switch S is in the Reference
position and key K is closed, rheostat Rg establishes a current from the B-power
supply (two flashlight batteries) such that the platinum wires heat up to 400° C,
Before the measurement, the instrument is balanced. Switch S is placed
in the Analysis position, key K is closed, and rheostat R5 is set so that the
current is uniformly distributed between the resistances and does not pass
through the milliammeter roA. If the exhaust gases are then passed through the
chamber with platinum wire R]_, the carbon monoxide and hydrocarbons present in
them will burn on the surface of the wire. The wire temperature will rise,
resulting in an increase of the resistance of element RI. At the same time, the
current distribution will change, and part of it will flow through the milliam-
meter and cause the indicator of the instrument to deflect. The indicator
scale has two zones: green, corresponding to the permissible content of carbon
monoxide and hydrocarbons in the exhaust gases, i. e., 0-2% by volume, and red
(2-10%), prohibiting the operation in a city of an engine with such toxic
exhausts.
The automobile engine exhausts entering the instrument for analysis are
drawn through it by means of a special piston pump. The samples are collected
directly from the exhaust pipe of the automobile. Before entering the measur-
ing chamber, the gases are purified by removing solid and liquid particles and
are diluted with air.
The analysis of the exhaust gases should be carried out in a steady run
of the engine. It then becomes necessary to watch the choke of the carburetor
to make sure that it is fully open. The determination of the carbon monoxide
and hydrocarbon contents is recommended for the following engine runs:
slow idle (up to 600 rpm);
fast idle (2200-2400 rpm).
To determine the permissible content of soot in automobile exhausts, port-
able indicators (soot meters) designed by LANE are employed.
The general appearance of one of the soot meters is shown in Fig. 13. The
soot meter consists of two main parts: a corrugated bulb pump and a filter
cartridge. Before starting the analysis, the instrument is prepared for opera-
tion. To this end, the shaft is pushed downward and the corrugated metallic
- 28 -.-
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bulb pump is compressed and left in this position by means of a catch.
An absolute filter of brand BF is loaded into the filter cartridge.
Fig. 13. Portable instru-
ment of LAME design for
determining the soot con-
tent of exhaust gases.
Fig. 14. Indicator instru-
ment of LANE 55/300 soot
meter.
The analysis consists in the following: the gas sampler is introduced into
the exhaust pipe, and the catch is released. The bulb pump expands and draws
300 cm3 of exhaust gas through the filter at a certain known rate. All the soot
particles deposit on the filter surface, and the filter darkens.
The filter is removed from its cartridge, and the degree of darkening is
compared with the standard scale.
The improved LANE 35/300 soot meter is also portable. It differs from the
one discussed above in that the determination of the amount of soot deposited on
the filter is made with the aid of a special instrument (Fig. 14). The instru-
ment is connected to a photoelectric cell which relates the degree of darkening
of the filter to the magnitude of the photocurrent recorded by the milliammeter.
The scale of the instrument is calibrated in this case so that one can get a
direct reading of the amount of soot contained in a cubic meter of exhaust
gases. A description of the instrument and its comparison with the character-
istics of the German instrument Bosch EFAW-78 are given in Table 5.
- 29 -
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Table 5
Parameters
Accuracy class
Weight of set, kg
Volume of gas sample, cm*
Working diameter of filter, cm
Tine of collection of sample, sec
Filtering material
Breakthrough coefficient for
diesel soot, %
Allowable working temperature of
filter, °C.
LANE 35/300 instrument
1,5
5,0
300
2,0
3,5
BF or FPA-15 cloth made of
ultrafine cellulose acetate
fibers
0,0
Up to 150
Bosch EFAW-78
Instrument
2,0
12,0
330
3,3
1,5
Filter Paper
30,0
Up to 50
- 30 -
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Chapter III
METHODS OF REDUCING THE FORMATION OF TOXIC COMPONENTS IN EXHAUST GASES
1. Operating Conditions of Engine
We shall discuss the toxicity of carburetor engine exhausts as a function
of the conditions of operation by taking the ZIL-130 engine as an example. The
dependence of the specific toxicity of exhaust gases on the engine load has the
following values:
Engine load,
% of maximum power .. 20 30 40 50 60 70 80 90 100
Specific toxic-
ity, g/hp hr* 4.65 3.00 2.00 1.50 1.00 0.60 0.30 0.97 8.00
It is evident that the toxicity of the exhaust gases decreases with in-
creasing load, reaching a minimum at 80% of maximum load, then increases sharp-
ly. This is because a rich mixture is supplied to the engine cylinders under
full power conditions. As a result, the conditions of combustion worsen sub-
stantially, and the content of incomplete combustion products including carbon
monoxide increases in the exhaust gases.
Thus, in order to ensure the minimum toxicity of engine exhausts in
operating an automobile, it is necessary to try to stick to conditions corre-
sponding to a 70-80% engine load and to avoid full power.
Unfortunately, in cities it is impossible to run an automobile under
constant conditions, and to avoid full loads. The conditions change continually,
and a considerable amount of time corresponds to light loads, idling, and
forced idling conditions.
Studies carried out at the Engine Institute of the USSR Academy of
Sciences by Candidate of Technical Sciences V. I. Bernatskiy for the purpose
of determining the predominant operating conditions of the GAZ-21 "Volga"
automobile under urban conditions showed that under load, the engine works
only 57% of the total time. The remaining 43% include idling and forced idling,
the latter amounting to over 16%. How does the operation of the engine under
these conditions affect the air pollution?
* Specific toxicity valves calculated by considering carbon monoxide, nitrogen oxide, hydrocarbons
and aldehydes at a crankshaft speed of 3000 rpm.
- 31 -
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Graphs of the dependence of conventional specific toxicities of idling on
the speed of rotation of the crankshaft for four engines are illustrated in
Fig, 15: three domestic and one 8-cylinder American engine of the Imperial
model, with a rated power of 250 hp at 4500 rpm (compression ratio 10, 11,
V-type arrangement of cylinders). The figure shows that the emission of toxic
substances during idling is considerable. It is noteworthy that a relatively
"clean" engine is the domestic model GAZ-53, and the most unsafe is the American
engine.
q, kg/hp hr.
8 J7
^ J.6
1 V
»
u JJ
o
B
of
•8
•§
* q, kg/hp hr.
'g ««S7
v. fltf«?
4» W»
| Oj®5
<
^
'x
/
/
/
/
^
2
. \
^^
/"
.
N
*H*^^
\
*~*
^
.^
^
.
k
\
\
X
^•P*
S
^<
-. —
Sy
S
*r
-3
^~~
•^_
^-^"
f
^
q, kg/hp hr.
4?
0.6
0,5
0.4
JJO SOD 800 1000 1200 n, rpm
Fig. 15. Conventional specific toxicities for
idling vs. rotational speed of crankshafts of
the engines:
1 - Imperial; 2 - ZIL-130; 3 - ZIL-iaO; 4 - GAZ-53.
The above dependences do not permit one to determine which rotational
speeds of the crankshaft are associated with the cleanest idling, since each
engine has its own dependence with its own characteristics. It may be noted
only that higher rotational speeds of the crankshaft, above 850-900 rpm, in-
crease the noxiousness of the exhaust gases in all the domestic engines studied.
Hence, if the engine is to run idle, the crankshaft speed should be kept low.
Forced idling is particularly undesirable for an engine. In this case the
crankshaft rotates at a higher speed; the carburetor throttle, whose position
corresponds to idling, is closed. A high vacuum is produced in the cylinders,
and a rich mixture is supplied. This causes incomplete combustion and
increased consumption of fuel. Moreover, oil seeps into the cylinders from the
crankcase, and its combustion raises the toxicity of the exhaust gases and
- 32 -
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causes scaling. The spark plugs are splashed with oil and liquid fuel. As a
result, spark failure is observed. Large amounts of fuel vapors which also are
toxic enter the exhaust pipe and hence the atmosphere. For the GAZ-53 engine,
the conventional specific toxicity under forced idling conditions can rise to
as high as 1.2 g/hp hr, which surpasses the conventional specific toxicity
associated with regular idling by a factor of six. In other words, from the
standpoint of poisoning of atmospheric air with products of exhaust gases,
forced idling is six times as dangerous as regular idling.
How can one reduce the time of operation of the engine under these adverse
conditions? First of all, by organizing urfran traffic so that frequent manda-
tory stopping of automobiles is eliminated. This is done, for example, by using
underground pedestrian crossings, elevated roads, and tunnels, by introducing
one-way traffic, by installing automatic traffic lights at intersections, and
by other measures.
Diesel engines also have their own optimum operating conditions correspond-
ing to the minimum toxicity of their exhaust gases: this corresponds to 60-707.
of the maximum load. Full load is undesirable: the exhaust gases turn black
and contain particles of soot, which is one of the main toxic components of the
exhaust gases of a diesel engine. Rapidly changing engine loads, (i. e., during
the so-called racing of the engine) are also unsafe.
2. Engine Adjustment
The power developed by an engine is basically determined by the amount of
fuel supplied to the cylinders. For the same amount of fuel supplied, it is
also possible to adjust the power of the engine over a certain range. In carbu-
retor engines, this is done by altering the composition of the mixture (i. e.,
the excess air coefficient a) and the angle of ignition advance 0. In diesel
engines, the power is adjusted by changing other parameters, in particular,
the angle of injection advance 6 and the injection time T£nj. We shall discuss
the essential features of these adjustments in more detail.
In carburetor engines, for a given fuel feed, the power is primarily deter-
mined by the fuel combustion rate. As already indicated in §1 of Chapter 1,
the highest combustion rate is achieved in this case when a=0.85-0.90. Deviation
from this value in the direction of both lean and rich mixtures results in a
decrease of engine power. The indicated fuel ratio is not optimal from all
points of view. First of all, far from the total heat-generating capacity of
the fuel is utilized here, since the combustion of its major portion does not
reach completion (for a< 1). The efficiency of the engine is relatively low.
Tests show that the most complete utilization of the energy contained in the
fuel takes place when a=» 1.05-1.15. The dependence of the effective perform-
ance indices of a carburetor engine (power and specific fuel consumption) on
the excess air coefficient shows (Fig. 16) that for a given portion of air
- 33 -
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supplied to the cylinders, there are two optimum values of a: one provides for
the development of maximum power by the engine, and the other ensures the best
economy of its operation. In order to decrease the fuel consumption, the engine
is usually adjusted for the economical mixture, and a power adjustment is re-
sorted to only when necessary. This is accomplished by selecting appropriate
carburetor jet tubes or by periodically connecting special carburetor attach-
ments.
Fig. 16. Effective power and
specific fuel consumption of a
carburetor engine vs. mixture
ratio.
All the operating conditions of an engine can be divided into three groups;
idling and small loads; range of medium load; maximum loading and close to
maximum loads.
In the range of idling and small loads, the throttle is not more than 25%
open. Little fuel and air reach the cylinders. In addition, the working mix-
ture is highly diluted with gases left over from the preceding cycle. The
ignition of such a mixture is considerably hindered, and its combustion rate is
slow. If in this case an economical mixture is supplied to the cylinders, the
operation of the engine will be unstable with standard ignition systems; even
misfiring is possible. It is therefore necessary to adjust the engine for a
somewhat richer mixture than the economical mixture. This is accomplished by
means of the idling system of the carburetor.
1 • '
At medium loads (with the throttle 25-85% open) there are no obstacles, to,
the adjustment of the engine for an economical mixture. •'
The engine operates stably at all rotational speeds of the crankshaft and
at a mixture ratio corresponding to a = 1.05-1.15.
-------
When the engine operates at large loads, the question of economy becomes
secondary. It becomes most important to obtain the maximum power from the
engine. For operation under these conditions, the engine is adjusted for a
power mixture. This is achieved by connecting an economizer, which supplies an
additional amount of fuel.
An enriched mixture is supplied not only when the engine operates under
close to maximum loads,1- To impreve the dynamics of the automobile when the
accelerator pedal is abruptly depressed, the mixture is also enriched by the
acceleration pump, but only for a short time.
In order to approximate the ideal Otto cycle and to increase the engine
power, the mixture is not ignited when the piston is located in the extreme
upper position, but slightly earlier. Tests have shown that for various reasons,
particularly because the moving piston may produce a vigorous mixing of the
fuel-air charge, the maximum combustion rate is observed at angles of ignition
advance of 20-40°.
It is natural at this point to ask the question, does a change of these
parameters (excess air coefficient and angle of ignition advance) have an effect
on the toxicity of the exhaust gases of a carburetor engine, and if so, to what
extent?
In order to answer this question, tests were set up at LANE using a single-
cylinder engine to study the effect of changing the adjustment parameters on
the content of individual noxious substances in the exhaust gases. The compres-
sion ratio of the engine was e=8, the number of revolutions n = 1500 rpm, and
the excess air coefficient; -Of=1..27/ The experiments showed that as the angle of
ignition advance changes, the concentrations of carbon monoxide and nitrogen
oxides remain unchanged. This pattern was also confirmed for other values of
the compression ratio (£=7; 9; 10) and excess air coefficient (OX).94; 1.17;
1.25). Hence it was concluded that, to a first approximation, the concentra-
tions of the principal toxic substances and hence the toxicity of the engine
exhausts are independent of the angle of ignition advance. Therefore, in the
daily operation of carburetor engines, the optimum angle of ignition advance
should be set only so as to obtain the maximum power and economy, without
consideration of the toxicity of the exhaust gases.
If, however, we consider the effect of the excess air coefficient on the
content of toxic components in the exhaust gases, the picture changes complete-
ly. The curve representing the dependence of the carbon monoxide content in the
exhausts of the GAZ-51 engine on the excess air coefficient (Fig. 17) at a
rotational speed of the engine crankshaft of n=2200 rpm indicates that when
the engine runs on rich mixtures (00=0.7), the exhaust gases contain up to
8% of carbon monoxide by volume. As one switches to lean mixtures, the CO
content declines sharply, and when o*1.2, it amounts to fractions of 1%. The
content of other noxious substances also changes markedly with a. If we sum
- 35 -
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up the a dependences of all the toxic components (or even their majority),
while at the same time using the "specific toxicity of exhaust gases" intro-
duced by LANE and explained in §4 of Chapter 1, then for the GAZ-51 engine
we shall have a dependence (Fig. 18) which shows that the minimum noxiousness
of the exhaust gases occurs at 0*1.18-1.25.
CO.%
Of US W t.?ij%
Fig. 17. Dependence
of carbon monoxide
content in the exhaust
gases of GAZ-51 engine
on the composition of
the mixture.. Speed of
rotation of engine
crankshaft n = 2200 rpm.
m
ISO
mo
50
\
0.8 0.9 1.0 t.f IJ 1J a
Fig. 18. Mixture-adjusted characteristic
of specific toxicity of exhaust gases of
GAZ-51 engine.
This value of the optimum excess air coefficient is characteristic of a
specific engine developing power at a given rotational speed of the crankshaft.
In order ;to be able to evaluate the performance of the engine from the stand-
point of minimum fouling of the atmosphere by its exhaust in operation under
all types of conditions, and to determine how the engine should be adjusted, a
whole series of dependences characterizing its operation should be obtained.
Such dependences should include the following:
characteristics of minimum toxicity of the exhaust gases, i. e., depend- ~
ences showing what minimum values of the noxiousness of the exhaust gases can be
achieved when the engine is properly adjusted and operates at different loads;/
! i
characteristics of optimum adjustment for toxicity, suggesting how the
engine should be adjusted, i. e., what values of the excess air coefficients a
should be set in relation to the power developed by the engine.
- 36 -
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q, g/hp hr.
VO
100
90
10
W
to
SO
iff
JO
X
n
ts
n
a
v
10
1.0
SO
SO
80
SB 100 N
m »
"max
Fig. 19. Characteristic of minimum toxicity of exhausts of
GAZ-51 engine.
Fig. 19 shows the characteristics of minimum toxicity of exhaust gases of
the 6AZ-51 engine, indicating that when the engine is properly adjusted and its
load is 80% of the maximum power, the specific toxicity of the exhaust gases
which can be achieved is barely above qe = 10 g/hp hr. To reduce the height of
the graph when it is plotted, the vertical axis represents the logarithms of
the specific toxicity of the exhaust gases rather than the straight values of
this toxicity.
0.1
Fig. 20. Characteristics of optimum
adjustment for the GAZ-51 engine:
1 - for toxicity; 2 - for economy.
_ 37 _
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The indicated characteristics can be obtained in automobile plants and
large service centers with test stands. This work is complex and time-
consuming. After correlating a large amount of experimental material, LANE
was able to set forth a series of recommendations which should be followed
in the daily practice of adjusting engines.
Usually, every engine today has known characteristics of its optimum
adjustment for economy, obtained in the plant. Such characteristics for the
GAZ-51 engine in its standard version (compression ratio e=6.2; displacement
V=3.48 1), operating at a crankshaft speed of 2000 rpm, are illustrated in
Fig. 20.
The same graph shows the characteristics of optimum toxicity adjustment
for the same engine, obtained at LANE. Comparison of the curves shows that
under part-load conditions, the optimum values of a for toxicity are approx-
imately 0.1 greater than for fuel consumption, i. e., they are shifted toward
leaner mixtures.
Adjustment for conditions close to maximum power for both minimum toxicity
and minimum specific consumption of fuel coincide. This is also observed at
other rotating speeds of the crankshaft and in other engines. From this one
can draw a practical conclusion. In order to minimize the toxic engine exhaust
components that poison the atmosphere, the engine should be adjusted for leaner
mixtures in the range of part loads (on the average, for values of a 0.1 greater
than those required by the principle that the best economy of its operation
must be achieved), leaving the adjustment for the specific fuel consumption
unchanged in the range of loads close to the maximum.
This recommendation should be followed for all carburetor engines not
equipped with special devices (catalytic neutralizers) for flame less afterburn-
ing of carbon monoxide present in the exhaust gases.
If the engine has a catalytic neutralizer, its adjustment for the excess
air coefficient may be different. Dependences of the specific toxicity of the
exhaust gases of a single-cylinder experimental engine obtained at LANE and
calculated only in terms of nitrogen oxides at different angles of ignition ad-
vance are shown in Fig. 21. The engine had a compression ratio e=7.5. The
characteristics were plotted at a rotating speed of the crankshaft n = 1200 rpm
and a volumetric efficiency DV = 0.75. A distinctive feature of the graph is
the fact that the given values of emission of nitrogen oxides were not referred
to a unit of effective shaft power developed by the engine but to a unit of
indicated power, i.e., the power of operation of the gases in the cylinder it-
self. In qther words, the mechanical loss in the engine was not considered.
This is entirely immaterial in an analysis of the nature of the variation of
exhaust toxicity with the excess air coefficient.
It is evident from the figure that the maximum specific emission (i. e.,
per unit of indicated power) of nitrogen oxides corresponds to a = 0.95-1.1
-------
for all values of the angle of ignition advance. As the mixture becomes
leaner or richer, the specific emission of nitrogen oxides by the engine
decreases. It is noteworthy that a greater decrease is associated with
rich mixtures. Thus, in order to obtain the minimum content of nitrogen
oxides in the engine exhausts, it is desirable to switch to richer mix-
tures. Although the carbon monoxide content of the exhaust will thus be
increased, this is allowable for an engine equipped with a catalytic
neutralizer.
f.t at
Fig. 21. Dependence of the indicated toxicity (re-
ferred to the indicated power) of exhaust gases of
a single-cylinder experimental engine in terms of
nitrogen oxides on the mixture ratio at different
angles of ignition advance.
- 39 -
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In summarizing the above, it should be noted that in providing the engine
with a catalytic neutralizer, from the standpoint of achieving the lowest total
toxicity of its exhaust gases, it is advisable to adjust the engine in the
range of small loads for somewhat richer mixtures corresponding to a = 0.8-0.9.
Since this recommendation implies a higher fuel consumption, it should
be used only in individual cases. This applies primarily to the use of auto-
mobiles in poorly ventilated spaces (quarries, underground shafts, warehouses,
etc.), when it is not necessary to consider the economy of operation of the
engine.
The most important point in this case is to achieve the lower toxicity
of the exhaust gases.
In diesel engines, the main adjustment parameters are the angle of in-
jection advance 8, characterizing the start of the fuel feed, and the mixture
ratio.
The time of the start of fuel injection greatly affects the process of
fuel combustion. If the injection of the fuel is premature, a considerable
part of it manages to vaporize, ignite, and burn up before the piston has
reached the extreme upper position. The pressure in the cylinder increases
rapidly and reaches high values, but this does not result in an increase of
engine power, since the heat loss to the cooling water increases, and the gas
pressure only interferes with the gradual motion of the piston. Late injec-
tion of fuel causes most of the latter to burn up while the volume above the
piston expands. Thus, the maximum combustion pressure, average pressure per
cycle, and engine power decrease, while the fuel consumption increases. Every
diesel engine has its own optimum angle of injection advance, whose setting,
other things being equal, ensures the development of maximum power and the
best economy of the engine. The magnitude of the optimum angle of injection
advance depends on many factors, particularly on the grade of fuel employed,
and may vary over wide limits. For example, it is equal to 15° for the
YaAZ-204 engine. The magnitude of the optimum angle of injection advance is
usually indicated in the engine certificate.
As was shown by the studies, from the standpoint of the conditions favor-
ing the development of the greatest power and best economy of operation, the
optimum angle of injection advance, adjusted on the engine, also turns out to
be optimal from the standpoint of the minimum total toxicity of its exhaust
gases.
The toxicity of the exhausts of diesel engines is determined to a large
extent by the composition of the mixture. Incomplete combustion in such engines
begins at excess air coefficients greater than in carburetor engines. It is
chiefly manifested in the appearance of soot in the exhausts. The excess air
coefficient of diesel engines is decreased with increasing fuel feed, since
the amount of entering air is practically constant for the same rotating speed
of the crankshaft.
- 4C -
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In the practical operation of diesel engines, when the composition of the
working mixture is evaluated quantitatively, instead of the concept of the
excess air coefficient, use is sometimes made of the quantity "fuel-air," repre-
senting the ratio of the amount of fuel injected into the cylinders to the
amount of admitted air. Its relationship to the excess air coefficient is
expressed by the formula 6 1
cl
a " p~ x ,
Gf \0
where IQ is the amount of air theoretically required for the combustion of 1 kg
of fuel (for diesel fuel IQ~ 14.3 kg of air per 1 kg of fuel).
If little fuel is supplied to the cylinders, the exhaust gases are practi-
cally colorless. As the fuel feed increases and reaches a certain value, con-
siderable soot appears in the exhausts, and their color turns black.
Numerous studies have established that from the standpoint of sanitary
considerations, it is most desirable to run diesel engines at a = 1.30-1.40.
As ot decreases to 1.1-1.2, the power of the engine increases, but at the same
time the fuel consumption rises and the toxicity of the exhausts increases
considerably.
Usually, plant tests of diesel engines record characteristics 1 (Fig. 22),
i. e., the smoking limit, representing the dependence of the power developed by
the engine on the rotating speed of the crankshaft, i. e., Ne = f (n). Each
point of this curve corresponds to values of Ne and n characterized by a smoky
emission of gases. In order to prevent the diesel engine from running under
such conditions, the displacement of the controlling part of the fuel pump
(usually the control lever) is restricted mechanically to limit the increase
of the fuel supply by installing a stop. Thus, the maximum power which can
be reached while the engine is running is obtained by installing a control of
the stop. The relationship of the maximum operational values of the power to
the rotational speed of the crankshaft is determined in this case by a fixed
setting of the control element in the indicated position and is represented by
a dependence referred to as the external operating speed characteristic is
located below the smoking limit characteristics.
Fig, 22. Smoking limit chara9ter-
istie (1) and external operating
speed characteristic (2) of a
diesel engine.
- 41 -
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Frequently, diesel engines smoke because the manufacturing plants and some-
times individual automobile drivers reduce the gap between the maximum permis-
sible operating power of a diesel engine and the power at which black smoke
appears in the exhausts. Since the above-described characteristics are close
to each other, any slight malfunction of the engine (impairment of atomization,
maladjustment of valves, clogging of air filters, etc.) or change in the
operating conditions of the automobile (moving to a mountainous area where the
air is more rarefied than normal air) causes the appearance of a large amount
of soot in the exhausts.
The installation of limiters of control elements of the fuel pump should
be followed closely so as not to permit their arbitrary readjustment.
3. Technical Condition of Engine
Analysis of the malfunctions and wear of automobile engines has shown that
the technical condition of automobiles has a considerable effect on the composi-
tion of their exhaust gases. It is evident from Fig. 23 that in terms of carbon
monoxide, the exhaust gases of an old engine are 2-4 times as toxic as those of
a new one. It is noteworthy that the highest toxicity corresponds to slow
speeds of the automobile, i. e., those at which the automobiles travel in large
cities a considerable part of the time.
CCD, %
\
o to ?a jo uo .
u, km/hr
Fig. 25. Carbon monoxide content in the exhaust
of a carburetor engine versus speed of automobile:
1 - used engine; 2 - new engine
The factors having the greatest influence on the toxicity of exhaust gases
are malfunctions of the fuel system, chiefly the carburetor. Therefore, any
malfunction causing a change of a (most frequently in the direction of its de-
crease) immediately affects the overall toxicity of the exhausts.
- 42 -
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Table 6
Traveling Speed
of Automobiie ,
km/hr
. 15
20
30
40
50
Carbon Monoxide Content, % bv Volume
Engine in Good Technical Condition
With Properly
Adjusted Carburetor
1,5
1,5
0~2
0,2
0,2
1,2
With Carburetor
Causing Excessive
Fuel Consumption
4.5
4,0
2J8
3,2
Table 6 lists data on carbon monoxide concentrations in the exhaust gases
of a ZIL-120 carburetor engine. The engine, which was in good technical condi-
tion, was sucessively tested with two carburetors:
a) properly adjusted;
b) producing an excessive fuel consumption.
A change in the composition of the mixture may be caused by the following
factors:
clogging of main and auxiliary fuel jets;
sticking of carburetor choke;
clogging of air filter;
malfunction of carburetor float.
Defects of the piston rings, cylinder sleeves, and valve seats cause loss
of compression, and hence, an impairment of the normal process of combustion
leading to an increase in the content of toxic products of incomplete combustion
in the exhaust gases. Furthermore, part of the gases break into the crankcase
and, after mixing with the oil vapor, also escape into the atmosphere. The
minimum amount of gases breaks through during idling and at low rotational
speeds of the crankshaft, and the maximum when the choke is wide open. In
the range from 800 to 2800 rpm, an average of 48 1/min of gases break through
in a new GAZ-51 engine with a wide-open choke. In a medium-used engine, this
figure increases to 75 1/min (a 1.55-fold increase) and in a worn engine it
goes up to 123 1/min (a 2.55-fold increase over the initial value).
The electrical system of the automobile must be constantly checked and
maintained in good technical condition.
- 43 -
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Contamination of the spark plugs and malfunctions of the ignition system
may cause spark failure. Then the unignited fuel-air mixture and the combus-
tion products left over in the cylinder from the last cycle are completely
ejected into the atmosphere. Gasoline vapor also is toxic, particularly the
vapor of ethyl gasoline.
An impairment of the valve adjustment or malfunctions in the gas distri-
bution system also cause an increase in the toxicity of the exhaust gases.
In diesel engines, the factors increasing the toxicity of the exhausts
are:
1. clogging of the air filter;
2. defects of cylinder sleeves, and piston rings, and wear of valve
seats, causing a decrease of compression;
3. malfunctions or maladjustment of the gas distribution system;
4. clogging of the exhaust pipe, which increases the exhaust counter-
pressure, impairs the course of the combustion process, and leads
to a sharp increase of the soot content in the exhaust gases;
5. malfunctions of the feed system, including leakage of injectors,
clogging of nozzle openings, sticking of injector valves, break-
down of injector valves springs, etc.
Of particular importance for the composition of the exhaust gases is
the condition of the injectors. Table 7 shows the degree of change of the
composition of exhaust gases as a function of the replacement of old injec-
tors by new ones in the engine of an MAZ-525 dump truck operating under
close to maximum load.
Table 7
Components of
Exhaust Gases
Oxygen
Nitrogen
Carbon Dioxide
Carbon Monoxide
Acrolein
Formaldehyde
Content of Components, %
' by,Volmne. with the
Fnl 1 n«l ntr Trn AAf m*c»
. Old
18,05
80,05
1,35
0,34
0,003
0.0001
New
10,96
82,50
6[jO
OiD9
0(0006
Hone
Change in
the Content
of Components,
% .of 'Initial
Volume
61
103
480
26
20
—
- 44 -
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4. Leaning Out of Mixture, Ignition With High Energy Spark, Flame Ignition
As was shown in §2 of the present chapter, the toxicity of exhaust gases
of carburetor engines may be reduced by switching to operation with leaner
mixtures than required by the conditions of maximum economy developed by the
engines. However, it la known from practical operation of automobiles that
actual adjustment of engines usually tends to enrich the mixtures. This is
done because, when very lean mixtures containing little fuel are used, the
mixture may fail to be ignited by the spark. Therefore, drivers, erroneously
trying to increase the reliability of the engine's operation and ignoring the
economy let alone the toxicity of the exhaust gases, adjust the carburetor for
a rich mixture. This is entirely superfluous, however. Modern engines with
sufficiently high compression ratios operate stably when the carburetor is
adjusted for economically optimal values of the excess air coefficient over
the entire range of variation of the engine power. Furthermore, experiments
have shown that with special ignition, the engine can run satisfactorily on
still leaner mixtures, even at excess air coefficient values greater than a = 2.
However, in order to obtain a stable and reliable operation of the engine
on very lean mixtures, it is necessary to make sure in some way that when the
spark is supplied to the cylinder, there will be the possibility of generation
of a strong initial combustion source from which the flame will be able to
spread freely over the entire volume of the fuel-air charge.
To date, two fundamentally different methods of producing such sources
have been developed. The first consists in creating a high energy spark. The
second provides for a change of the engine construction such that a small volume
of a rich, easily igniting mixture is produced in the immediate vicinity of the
standard ignition spark plug before the spark is producedt The combustion of
this volume forms an intense and powerful ignition source which makes it possi-
ble to burn very lean mixtures as well. The method includes a laminar distri-
bution of the mixture and prechamber-flame ignition. There are many designs
of prechamber-flame ignition. They differ from one another in the methods of
feeding the fuel to the prechamber, methods of mounting on the engine, etc.,
but the principle of their operation is the isame.
Experimental studies conducted at LANE have made it possible to compare
the change of the toxicity of carburetor engine exhausts by using three types
of ignition: standard, high energy spark, and prechamber-flame ignition. All
the experiments were performed on the same GAZ-51 engine.
An ignition system developed by the Scientific Research Institute of Auto-
matic Instruments (SRIAI) was used to ignite a mixture with a high energy
spark. It consists of a system of battery ignition with semiconductor commuta-
tion of the primary circuit. Large inductive resistances which made it possible
to raise the voltage at the spark plug electrodes to 30,000 V and increase the
discharge time to 0.003 sec were introduced into the commutation system. The
- 45 -
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prechamber-flame ignition used was the one developed at the Central Scientific
Research and Experimental Design Institute of Fuel Apparatus of Tractor and
Stationary Engines. Its technical characteristics are: volume of prechamber
1.5 cm3, automatic mixture supply valve actuated by pressure difference. The
mixture is formed in the float chamber of the carburetor through enrichment of
the fuel with light, rapidly evaporating fractions. In order to modify the
engine to a prechamber-flame ignition system, the carburetor must be replaced,
and adapters with prechambers screwed onto the spark plugs.
The advantages and disadvantages of all the enumerated ignition systems can
be readily compared in terms of the characteristics of minimum toxicity of
exhaust gases (Fig. 24) plotted by taking into account the main standardizable
toxic components of the aerosol. The characteristics were plotted on a semilog
scale, i. e., the loads in percent were laid off along the horizontal axis,
and logarithms of the values of the specific toxicity of the exhaust were laid
off along the vertical axis. The shape of the curves defining these relation-
ships was found to remain unchanged.
q, g/hp hr.
in-
"maxi*
Fig, 24. Characteristics of minimum toxicity of exhaust
gases of GAZ-51 engine obtained by using different ignition
systems:
1 - standard ignition; 2 - ignition with high energy spark;
3 - prechamber-flane ignition.
Comparison of minimum toxicity characteristics shows that leaning out of
a mixture with simultaneous intensification of ignition strongly depresses
the toxicity of the engine exhausts at part loads. The best results are ob-
tained with a high energy spark ignition system according to the SRIAI circuit,
which reduces the total toxicity of the gases by a factor of 2-3. A somewhat
lesser effect is obtained by using prechamber-flame ignition. In this case,
the toxicity of the exhausts is reduced by a factor of 1.8-2.5 as compared
with the standard system. The better result obtained by using high energy
- 46 -
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spark ignition is explained by the fact that it lacks the additional source of
formation of carbon monoxide which in the prechamber-flame ignition is consti-
tuted by the initial, small, but highly enriched volume of the fuel-air charge.
Engines with prechamber-flame ignition and the SRIAI intensified ignition
system are completed under laboratory conditions.
Inasmuch as the use of the prechamber-flame ignition principle, in addi-
tion to reducing the toxicity of the exhaust gases, results in a 3-5% rise in
the economy of engine operation, many automobile factories in this country,
particularly ZIL (Plant im. Likhachyev) and GAZ [Gor'kiy Motor Vehicle Plant
(im. V. M. Molotov)], are developing engines with prechamber-flame ignition.
Thus, the changeover to lean mixtures makes it possible to decrease the
toxicity of the exhaust gases of carburetor engines in terms of the components
which are standardizable at the present time. However, how can this rule
always be followed if it is known that all modern carburetors are adjusted in
such a way that they give a rich mixture in the range of 80-100% of throttle
opening? Is it possible to switch to lean mixtures in this case?
It is possible indeed. However, the engine design must specify the devices
that could compensate for the power loss that must take place in the changeover
to lean mixtures in the range of large engine loads. One such device can be
the super-charger, mounted in the intake system.
In this case, while the total amount of gasoline supplied to the cylinder
is maintained constant, a is increased by force-feeding a large amount of air
under pressure.
The power losses which must be offset by pressure charging in certain
engines are given in Table 8. Here a leaning out of the mixture to a=1.12 is
assumed.
Table 8
Engine
GAZ-60
GKZ-212
ZTL-120
ftltrjji
Rotating
Speed of
Crankshaft
1000
2000
1000
2000
3000
1200
1600
2000
Maximum
Power
0,85
0,90
0,95
0,95
0,90
0,87
0,93
0,88
Power Decrease
u«
HP
2,4
4,4
1,4
1.4
10,7
-7,4
10,4
10,8
t
15,2
12,6
8,5
4,0
20,8
14,2
14,4
13,4
- 47 -
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It is obvious from Table 8 that in the changeover to lean mixture, from
4 to 217» of the power thus lost must be compensated for. Experiments show
that pressure charging makes it possible to accomplish this. Without risking
the appearance of knocking, pressure charging can provide a power increase of
up to 26%. LANE also established that:
In order to achieve a low-toxicity and economic operation of a multi-
cylinder carburetor engine in the load range of 85-100%, a changeover to lean
mixtures with compensation of the power loss by pressure charging is desirable;
Engines with an adequate distribution of the mixture over the cylinders
make it possible to lean out the mixture to cc=1.2 at full power, and those
with a poor mixture distribution, to ct=1.12. Thus the power is preserved by
pressure charging, and the toxicity of the exhaust gases decreases by a
factor of 12 in engines with a good mixture distribution and 10 in those with
a poor distribution.
It should be noted that when a pressure-charging supercharger is installed
on an engine, it is necessary to change the gas distribution phases to some ex-
tent, since, during the increase of the pressure of the fuel-air mixture enter-
ing the cylinder at the instant of valve overlap, a certain seepage of the
fresh mixture into the exhaust pipe is possible.
5. Vacuum Regulator
In order to improve the economy of operation of an engine and decrease the
toxicity under forced idling conditions, it was proposed in this country back
in the 1940"s that a device be introduced into the carburetor design which
automatically disconnects the idling jet as soon as the engine is shifted to
forced idling. As was pointed out by Academician Ye. A. Chudakov, "Comrades
Rubets, Kravtsov and Varenov, who proposed such an attachment for domestic
introduction, called it a vacuum stabilizer." Later this name was changed.
Since the use of the vacuum stabilizer yields a certain economy of gasoline,
it received the name of idling economizer.
Fig. 25. Diagram of Vacuum
Regulator (AESRl).
- 48 -
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For the same purposes, the Automobile Engine Scientific Research Institute
(AESRI) designed a vacuum regulator also called the coasting valve. Its prin-
ciple of operation is analogous to that of the idling economizer.
The purpose of this regulator is to admit an additional amount of air
into the intake system of the engine operating under forced idling conditions.
A diagram of the vacuum regulator is shown in Fig. 25. Valve 5 separates
two cavities: 6, connected to the intake manifold, and 8, connected with the
atmosphere. Cavity 3 above the valve communicates through channel 4 with the
cavity of the intake manifold. Diaphragm 7 is the element that opens the
channel. Screw 1, which changes the initial tension of spring 2, is used to
adjust the vacuum in the intake manifold at which the valve should open.
The vacuum regulator operates in the following manner. As the pressure
in the intake manifold drops below the value corresponding to idling, dia-
phragm 7 rises (the total pressure exerted on it from the top is less than
from the bottom) and opens the valve. An additional amount of air enters the
intake manifold, and the vacuum in the latter decreases (the pressure increases),
The vacuum also decreases in cavity 3 above the valve, since this cavity is
connected with the intake manifold via channel 4. The valve is closed by the
action of the spring.
6.. Use of Fuel Additives
The complete combustion of fuel and hence a reduction in the content of
certain toxic components (carbon monoxide, aldehydes, hydrocarbons, soot and
other components) in the exhaust gases can be achieved by diluting the fuel
with special agents, i. e., additives altering the course of the oxidation
reactions of hydrocarbons. The additives may be alcohols, their mixtures, in-
dividual homogeneous petroleum distillation products, or complex compounds of
the most diverse substances, added to fuels in amounts ranging from a fraction
of a percent to several tens of percent.
For carburetor engines, the most effective of those known at the present
time are mixtures of different alcohols. They have been studied at the All-
Union Scientific Research Institute of Petroleum Refining (AUSRIPR). Some
results of experiments on the determination of the effectiveness of adding
a mixture of alcohols to standard A-72 gasoline, conducted for the purpose of
decreasing the content of carbon monoxide in engine exhausts, are shown in
Table 9. The experiments were set up under bench conditions using GAZ-21D
and MZMA-407 engines operating at 50% of maximum load and at a crankshaft
speed of 2000 rpm.
_ 49 -
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It is evident from Table 9 that a substantial reduction of the carbon
monoxide content of the exhaust gases can be achieved by adding an alcohol
mixture to the gasoline. In some cases, carbon monoxide is completely ab-
sent from the gases.
Table 9
Fuel
A-72 gasoline
?ame
A-72+4% alcohols
Sane
A-72+8%aJcohols
Saae
A-72-J- 12% slpohols
Sate.-
A-72+16%alooh61s
Sane
A-72+20% aloabols
A-72+24% alcohols
Engine
^ASi-21fl
,'^iZMA '--407
•VZM. -407
GAZ-2U
,JJZMA -407
GAfc-2lH
/KaiA •' -407
GA2-21H
;X«IA -407
HAM -407
Excess
Air
Coef-
ficient
a
0,910
0,978
0,927
0,954
0,950
0,950
0.945
0,946
0,965
0,950
0,935
Carbon Monoxide
Content or Exhaust
Gases. %
By
Volume
1.20
1,07
0,80
0,65
0.60
0.40
0,50
0.12
0,40
0,0
0.20
0.0
*or.
VjtlupB1 of
100
100
67
61
50
38
42
11
33
0
17
0
Similar results were obtained for gasolines of other brands.
Apparently, the addition of a mixture of alcohols to gasolines decreases
the content of not only carbon monoxide in the exhaust gases, but also of
other products of incomplete fuel combustion, in particular, aldehydes. No
direct experiments with a complete chemical analysis of the composition of the
exhaust gases have as yet been set up. There is reason to believe that the
addition of alcohols can lower the content of carcinogenic substances in the
exhaust gases. It should be noted that the addition of alcohols further re-
duces the formation of deposits in the engines, increases their power, and
improves the economy of operation by an average of 5%. At the present time,
the problem of the usefulness of adding alcohol mixtures to gasoline is being
comprehensively studied.
In developing additives to diesel fuels, attention is focused primarily
on reducing the soot in the exhaust gases, i. e., decreasing their smoke
content.
Additives are being developed in many countries. In particular, an addi-
tive under the brand name of SLD has been developed in Belgium, which among
other components includes 19% barium, 1.5% sulfur, and 32.5% sulfur slags. In
liquid form, the additive is added in amounts of 0.25 to 1.0% of the fuel volume,
-50 -
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The company tested the additive for 240 hr in a single-cylinder four-
stroke prechamber test engine with a compression ratio e=i9 and displace-
ment 7=553 cm3. During the tests, the dimensions of the moving parts of the
engine (piston rings, cylinder sleeve, etc.) were measured, chemical analysis
of the lubricating oil was carried out, and the content of soot, carbon monox-
ide, aldehydes, and nitrogen oxides in the exhaust gases was determined.
60 60 60. 100 120
WO ISO WO 220 240
Engine running time,- hr.
Fig. 26. - Change in the smoke content of ejshjaust gases:
1 - without additives; 2 - with SID additives
It was found that dilution of the fuel with the SLD additive has no adverse
effect on the lubricating oil, does not clog up the fuel feed system, does not
increase the wear of the moving parts, and does not affect the content of
carbon monoxide, aldehydes, and nitrogen oxides in the exhaust gases. At the
same time, the smoke content of the latter decreases by a factor of 10 or
more. Fig. 26 shows the curves advertised by the company and representing the
change of the smoke content of exhaust gases during the operation of an engine
when the SLD additive is used. The smoke content values are given in Hartridge
units.
Laboratory samples of the most varied liquid additives were tested at LANE.
The test results for one of them (containing barium), conducted on two automo-
bile engines, the two-stroke Y.aAZ-204 and four-stroke YalE-236 engine, are
shown in Figs. 27 and 28 and Table 10.
The figures show photographs of absolute BF filters through which were
passed equal volumes of exhaust samples taken from the exhaust manifolds
of the engines.
- 51 -
-------
I
Ul
t,'3 Rpra
fa
1
'~;:
fw®f~!"
Fig. 27. Condition of BF filters
of KaMZ-236 engine operating on
fuel with and without additive.
-------
1pm of
Irank-
shfftt
1500
one—
Power,
/hp
Darkeninj^f^Filter
Diesel Fuel Diesel Fuel
Without With
_A(MiHva Md.it ive.
tifa\#^MJ8&\!&*
s^fe$&$&&
•'•*i-/B'k'v i/iSf^ • •'•''-• ' v
- •? «£$ ; ' jf f|pz> ;| : v> ' )
Fig. 28. Condition of BF filters
of YaAZ-204 engine operating on
fuel with and without additive.
In the Soviet Union, effective antismoking, metal-containing additives
have been developed by the Institute for Chemistry of Additives, Academy of
Sciences of the Azerbaijan SSR. Their use decreases the smoke content of
diesel engine exhausts and lowers the emission of carcinogenic substances
into the atmosphere by up to 60%.
A positive solution to the problem of widespread adoption of additives
in the national economy should also be preceded by a comprehensive analysis
of a large number of specific problems. These include:
Study of the effect of additives on the content of all or most of the
toxic components of exhaust gases. It may also happen that the addition of
some additive to the fuel will cause the appearance in the gases of new noxious
substances which earlier had been absent;
Study of the effect of additives on the power, economic and other indices
of operation of engines;
Study of the effect of additives on the parts and systems of the engines
and on the lubricating oil;
Development of the technology of industrial production of additives;
Development of industrial equipment for the production of additives in
necessary amounts and equipment for their storage;
Estimation of the cost of production of additives and calculation of the
capital investment necessary for constructing the plants or individual plant
sections.
- 53 -
-------
Table 10
8
X
+>
1
1
2
3
4
5
6
7
Operajjifg^Conditions
Power, Ne,
hp
.Idling
.ZdljjDg-.
XOfl
28
; 28
56
56
84
84
112
112
56
72
72
Rota-
tional
Speed of
'rank—
shaft ,rpn
1400
1400
1400
1400
1400
1400
1400
1400
1400
1400
1400
1200
1200
Exhaust
Counter-
Pressure
mm HjO
500
500
.566
566
667
667
800
SOO
900
900
5000
COOO
6000
Content of Ex-
haust Gases, in
Hartridre units
Fuel
Without
Additive
S3"
4.5
3.5
3.5
5,0
5.5
20.0
20,0
43.5
.. 47.5
17.0
58,0
44,0
Fuel
With
Additive
—
_
_
_
_
-
3,5
3,5
6,0
7.5
2.5
19,0
13,5
Decrease
of Smoke
Content,
fl£
7>
—
—
—
—
_
_
82,5
82.5
85.0 -
84,0
85,5
67,0
69.0
Note. In experiments Dos. 6 and 7, the increased exhaust
counterpressure «as reduced by interposing a specially
mounted gate valve.
These problems are being solved at the present time, and there is good
reason to believe that definitive conclusions will be reached in the imme-
diate future.
- 54 -
-------
Chapter IV
NEUTRALIZATION OF TOXIC COMPONENTS OF EXHAUST GASES
One of the most common methods of purification of noxious gases consists
in passing them through various devices. The latter either trap the toxic
substances by precipitating (absorbing) them on the surface of the filler or
dissolving them in liquids, or chemically bind the noxious components of the
gases first, then trap the products of the chemical reactions.
Occasionally, in order to ensure the occurrence of these processes, it
is necessary to subject the gases to the action of electric or ultrasonic
fields. Accordingly, the devices are then called electric or ultrasonic.
There are designs that actively affect the components of exhaust gases.
Such designs can be used to complete the combustion of unburned components of
the gases and to carry out various chemical transformations of individual sub-
stances.
The degree in development of such devices is so advanced that it theo-
retically permits the creation of such designs that remove a gas of any com-
position to achieve any degree of purity.
From the standpoint of their principle of operation, all the devices for
neutralizing engine exhausts are divided into two major groups. Those which
merely block noxious substances are called filters. However, when used to
actively effect changes in the component aerosols (afterburning of unburned
components, chemical transformation of noxious substances, etc.), such devices
are called neutralizers. The latter neutralize noxious substances, i* e.,
convert them into products which do not affect human health.
1. Liquid Neutralizers
Historically, liquid neutralizers were the first devices to find applica-
tion in the partial detoxication of exhaust gases. They were developed especi-
ally in the mining industry, where they have been and continue to be installed
on heavy-duty automotive equipment.
Their principle of operation is simple. The aerosol is passed through
water or an aqueous solution of various chemical reagents where a part of the
noxious substances (mostly in the solid state) is simply blocked mechanically,
precipitating as a deposit, another part dissolves, and a third part is tied
up chemically. At the same time, this causes the gas to cool down.
We shall consider the interaction of certain toxic components of exhaust
gases with water and aqueous solutions of chemical reagents.
-------
Aldehydes dissolve in water, light ones easily, and heavy ones (in parti-
cular, acrolein CH2-CH-CHO) with more difficulty. As the temperature of the
water rises and the latter becomes saturated, the solubility declines. As a
result, after saturation, the water no longer dissolves aldehydes. If in addi-
tion, for whatever reasons, the water temperature rises, the aldehydes will
begin to volatilize from the solution.
When the exhaust gases pass through aqueous solutions of salts, the alde-
hydes combine chemically, then the products of the reactions dissolve in the
solutions. For example, the reaction between formaldehyde (HCOH) and an aqueous
solution of sodium sulfite (Na2SC>3) proceeds as follows:
Na2SO3 -f HCOH+H20 -» NaOH -f CH2(NaSO3) OH,
where CH2(NaSC>3)OH is retained in the solution on the chemical reagent.
Nitric oxide is poorly soluble in water, while nitrogen dioxide is readily
soluble, forming nitric and nitrous acids.
2NO2-J- HaO «± HNOj-fHNOj.
The reaction is reversible, i. e., can proceed in both directions, causing
an incomplete absorption of the dioxide. When the acids reach a certain concen-
tration, the reaction shifts to the left, and the product of the reaction is
the dioxide.
The oxide and dioxide are readily absorbed by aqueous solutions of a
number of salts. In all of these reactions, an equilibrium is established be-
tween the initial and final products, similar to the one above. For this
reason, the absorption of nitric oxide is incomplete. The degree of absorption
of nitric oxide may be evaluated from the following data: one part of ferrous
sulfate dissolved in two parts of water absorbs three volumes of nitric oxide;
a saturated volume of ferric chloride absorbs 23 volumes of nitric oxide.
Both nitric oxide and nitrogen dioxide react well with strong aqueous
solutions of acids and alkalis, which unfortunately strongly corrode the equip-
ment and necessitate careful handling.
Soot (particularly coarse particles) is retained when a gas passes through
water and aqueous solutions of chemical reagents, settling out as a deposit.
When the solution is swirled, the deposit may be churned up. The soot particles
are then caught by the passing gas and are carried away into the atmosphere.
Carbon monoxide reacts with neither water nor aqueous solutions of chemi-
cal reagents employed in practice. At the present time, studies are being
made to find solutions retaining carbon monoxide.
- 56 -
-------
It follows from the above that the use of water in liquid neutralizers is
very limited. It can be used only as an emergency filler, when for whatever
reasons, the entire stock of chemical reagents has been depleted where liquid
neutralizers are used. Furthermore, the service period of the neutralizer
must be shortened*
Aqueous solutions of sodium sulfate (Na2S03), sodium carbonate (^2003),
sodium bicarbonate (NaHCO^), ferrous sulfate (FeSO^), sodium hydroxide (NaOH),
copper acetate [CH-j(CuO)2 ], their mixtures, and other solutions have been
studied in various concentrations as chemical reagents for neutralizing ex-
haust gases. Analysis of the test results made it possible to select the most
effective solutions. These were found to be ten-percent aqueous solutions of
N82S03 or NaHC03 or Na2S03 with an admixture of 0.5% hydroquinone (CfcHgC^),
which prevents premature oxidation of the main chemical reagent. By passing
the exhaust gases through these solutions, a complete neutralization of alde-
hydes and up to 70% of nitrogen oxides was achieved in the course of 8 hrs.
Further use of the solution is possible, but the neutralization occurs at a
slower rate. The solution should be replaced.
A high degree of neutralization of exhaust gases is also provided by a
ten-percent solution of ferrous sulfate (FeS04) with an admixture of 0.5%
hydroquinone. It allows a neutralization of 100% of the aldehydes and 70%
of nitrogen oxides present in the gases. However, the performance of this
solution is unstable. Under certain operating conditions of the engine,
especially those characterized by a high content of nitrogen oxides in the
exhaust gases, the solution ceases to absorb them altogether.
~-T~- ~- 9
Fig. 29. Liquid neutralizer made by
Salzhutter Co.
- 57 -
-------
Liquid neutralizers are used for detoxicating the exhaust gases of diesel
engines, since the main toxic component of carburetbr engines is carbon monoxide,
i. e., a component to which liquid neutralizers are insensitive. One of the
most perfect modern liquid neutralizers is one produced by a West German company,
Salzhtitter (Fig. 29). The neutralizer consists of main tank 1 into which 70 1
of the chemical reagent is poured, and auxiliary tank 8 with 200 1 of pure
water. To increase the cooling surface of the tanks, they are corrugated and
covered with a porous coating. The path of the gas is indicated by arrows.
The gas traverses the solution, a set of angle brackets 4 which separate the
moisture droplets, and escapes into the atmosphere through outlet 5. As the
neutralizer continues to be used, the amount of water in the solution of the
chemical reagent decreases as a result of evaporation. The concentration of
the solution increases, and its level drops. Tube 7, connecting the main tank
with the auxiliary one, becomes exposed, and the auxiliary tank automatically
delivers a certain amount of water to the solution, thus diluting it. This
water is added until the level of the solution has covered the lower section
of connecting tube 7. Orifice 6 is used to pour in the neutralizer, plug 10
is for draining the spent solution, and stopcocks 2 and 3 are used to control
the level. The inner chambers of the apparatus are cleaned by removing the
soot and scale through a hand hole. The neutralizer is mounted on a diesel-
electric self-propelled wagon used in the mining industry.
At LANE, this neutralizer was tested on a stand with an YaAZ-204V engine.
The chemical reagent used was a 10% solution of NA2S03 containing 0.5% hydro-
quinone. The tests showed that depending on the operating conditions of the
engine, a 90-100% removal of aldehydes and 35-70% removal of nitrogen oxides
from the exhaust gases is achieved. After the neutralizer, the exhaust gases
were practically colorless and had cooled down to temperatures no higher than
140° C. The temperature of the reagent solution was no higher than 70°. The
neutralizer operated continuously for 8 hrs, after which the solution had to
be replaced and water had to be added.
In collaboration with the State Experimental Institute of Design and
Construction for the Coal-Machinery Industry, LANE developed a combination
neutralizer for the engine of the VS-15 self-propelled wagon (YaAZ-204V diesel
engine), the chief element of which was a liquid neutralizer. To remove car-
bon monoxide from the exhaust gases, the general scheme also included a special
low-temperature catalytic neutralizer through which the gases were passed be-
fore entering the main tank containing the chemical reagent (see §3 of this
chapter). The neutralizer was tested under road conditions. Under the most
unfavorable operating conditions of the engine, the content of nitrogen oxides
in the exhaust gases past the li{£uid neutralizer did not exceed1 0.315 mg/1
for a content of nitrogen oxides of 0.478 mg/1 (degree of purification, 35%).
The retention of aldehydes was practically total. Under most operating
conditions of the engine, the exhaust gases were colorless and acquired a
color only when the engine was raced.
-58 -
-------
During the construction of the Leningrad subway, tests were carried out
on another liquid neutralizer developed at LANE (Fig. 30) specifically for TGK
diesel locomotive with a 1D6 diesel engine. The diagram of the installation
of the neutralizer on the locomotive is shown in Fig. 31. The tests were per-
formed under the following operating conditions of the locomotive: parked,
idle revolutions of the engine crankshaft; shunting speed of 30 km/hr; cruis-
ing speed of 60 km/hr. While moving, the locomotive was without load and with
a load of 32 tons. The tests showed a satisfactory operation of the neutra-
lizer. The exhaust gases contained almost no smoke, but did contain a large
amount of moisture, mainly in the vapor state. Carryover of moisture droplets
was observed only during cruising (when the locomotive traveled at 50 km/hr
on a segment of road with a slope of 0.009). A sharp reduction of the toxic
components of the exhaust gases took place. Even when the neutralizer was
filled only with water, the aldehyde content decreased by 507..
view of B
Gas
Intake
Fig. 30. Liquid -neutralizer of exhaust
gases of ID6 diesel engine:
1 - control stopcock; 2 - damper;
3 - water guard; 4 - wall of water guard;
5 - cyclonej 6 - ejector tube; 7 - drain
plug; 9 - sight hole.
Fig. 31. Diagram of installation of LANE liquid neutralizer on
TGK diesel locomotive:
1 - engine; 2 - neutralizer; 3 - replenishing tank with water;
4 - connecting hose.
- 59 -
-------
Liquid neutralizers have earned the right to be mounted on diesel loco-
motives, self-propelled equipment, stationary power plants, etc. In some
cases, namely, in closed spaces exposed to explosion hazard, they are simply
irreplaceable, since, by simultaneously acting as coolers, they substantially
lover the temperature of the exhaust gases. The main disadvantages of this
type of devices are:
Large weight and outside dimensions;
Insensitivity to neutralization of carbon monoxide;
Complexity of servicing due to the frequent replacement of the reagent
solution (as a rule, every eight hours of operation) and a periodic time-
consuming cleanout of the inner chambers to remove the scale and soot
(at least once every two weeks);
High cost of the chemical reagent;
Difficulties arising at subzero temperatures of the surrounding medium
because of the possibility of freezing of the solution.
ft
Fig. 32. Diagram of liquid neutralizer (designed by the Leningrad
Mining Institute im. Plekhanov) for exhaust gases of diesel engine
of MAZ-205 truck:
1 - gas intake; 2 - overflow stopcock; 3 - replenishing tank with
water, capacity 45 1; 4 - replenishing orifice; 5 - water guards;
6 - gas exit; 7 - metal turnings; 8 - main tank, capacity 55 1;
9 - collector; 10 - drain plug; 11 - compartments.
These disadvantages account for the fact that liquid neutralizers thus
far have not been commonly used in motor transport. Nothing has been pub-
lished abroad on their use for detoxicating the exhaust gases of mass-produced
automobiles. In the Soviet Union, a small original model of a neutralizer
has been constructed at the Leningrad Mining Institute im. Plekhanov (Fig. 32).
Neutralizers of this type were installed on MAZ-205 dump trucks hauling
rock from the excavation of by-pass tunnels during the construction of the
Nurek Hydroelectric Power Plant built by "Tadzhikgidrospetsstroy" (Tajik Trust
for the Reinforcement of Foundations and Structures of the Ministry of Electric
- 60 -
-------
Power Plants of the USSR) and in other areas, and were connected only when
the trucks were moving Inside the tunnels. Thus, the conditions of opera-
tion of the dump trucks (periodically leaving and entering the tunnels)
predetermined the repeated short-term operation of the neutralizers, causing
a moderate temperature of the reagent solution in relatively small Quantities
of it. The climatic conditions of the construction site excluded freezing
of the solution.
Work on improvement of liquid neutralizers continues. There are still
many other ways of decreasing their weight and size, and eliminating a num-
ber of other drawbacks.
2. Flame Afterburning of Toxic Components of Exhaust Gases
The method of flame afterburning is based on the ability of the toxic
fuel components of exhaust gases (carbon monoxide, aldehydes, hydrocarbons,
etc.) to oxidize at high temperature and in the presence of free oxygen in
a gas mixture. Nitrogen oxides are not neutralized by flame afterburners.
A vigorous oxidation reaction of aldehydes requires a minimum temperature of
550°C and in the case of carbon monoxide and hydrocarbons, around 700°C.
In carburetor engines, whose exhaust gases contain large amounts of carbon
monoxide, flame afterburning can be carried out under certain operating con-
ditions of the engines without the presence of a steadily acting high-temper-
ature, strong open-flame source. The exhaust gases, first diluted with air
(one must bear in mind that their initial oxygen content is low) , can be
ignited periodically by an electric spark. The combustion then proceeds on
its own. A high flame temperature is sustained by the heat evolved during
the combustjiofi of the toxic components (the combustion of 1% by volume of
CO contained in the gas mixture raises the temperature by approximately 100°C).
A stable combustion will not always be sustained in this case. When the
engine operates on leaned-out mixtures, the heat of the oxidation reactions of
toxic components is no longer sufficient to sustain the flame, and therefore
an additional amount of fuel must be added to the afterburner. In order to
provide for a more stable operation of the neutralizer under variable operating
conditions of the engine, the neutralizer design is made to include a heat
exchanger to which air is supplied before entering the combustion chamber.
The heat exchanger is heated by the gases during their combustion or before
they are discharged into the atmosphere. An automatic by-pass valve is in-
stalled in the heat exchanger to protect it from overheating when the engine
operates on rich mixtures. Fig. 33 shows a diagram of a flame neutralizer.
Exhaust gases 1 enter afterburner 3, which has two ejectors supplying initial
air 2 and secondary air 4; the latter is heated in the heat exchanger 7. Com-
bustion takes place in chamber 6, and spark plug 5 provides the ignition.
Flame neutralizers of exhaust gases for carburetor engines have been
developed and tested mostly abroad, particularly in the U.S.A. The tests have
-------
shown their inefficient and extremely unstable operation. In order to obtain
a stable combustion, the combustion chamber is placed as close as possible
to the exhaust valve, where the temperature of the exhaust gases is suffi-
ciently high. Sometimes it is built directly into the exhaust manifold of
the engine (Fig. 34).
Fig. 33. Diagram of flame neutralizer of carburetor engine
exhausts.
Fig. 34. Diagram of flame neutralizer of carburetor engine exhausts,
built into the exhaust manifold:
1 - intake of extra air; 2 - release of gases; 3 - heat insulation;
4 - mixing chamber; 5 - combustion chamber; 6 - spark plug.
Closely related to the principle of flame afterburning is the method,
developed in the U.S.A., of supplying extra air to the points of direct re-
lease of the exhaust gases from the cylinders. Here the extra air is
supplied to the seats of the exhaust valves (in some designs even through
the valve stems). In this case, owing to the high temperature of the
exhaust gases, the chemical oxidation reaction of a series of incomplete
combustion products (in particular, aldehydes) is achieved at full engine
load without the presence of additional ignition. Such designs of exhaust
systems are used on engines of automobiles produced by General Motors,
Ford, etc.
- 62 -
-------
In diesel engines, the afterburning of the unburned components of exhaust
gases is possible only when they are passed through an open-flame source
generated for this purpose. The best-known designs of flame neutralizers
are those for MAZ-205 (Fig. 35) and MAZ-525 (Fig. 36) automobiles. With a
correct automatic adjustment of the systems of the flame neutralizer and a
successful design of its parts one can achieve a stable afterburning of the
aldehydes, carbon monoxide and hydrocarbons present in the exhaust gases.
However, this is not an easy problem to deal with.
Its solution requires the use of complex, fast-response automatic systems
providing for a stable combustion of the extra fuel in the pulsating flow of
exhaust gases with o>l for all the operating conditions of the engine.
Fig. 35. Diagram of flame neutralizer of exhaust gases from
diesel engine of MAZ-205 dump truck (designed by the Ural Scien-
tific Research and Design Institute for the Copper Industry):
1 - vaporizer; 2 - spark plug; 3 - diesel fuel supply; 4 - burner;
5 - combustion chamber; 6 - catalyst (copper); 7 - intake-exhaust
nozzle; 8 - intake of exhaust gases from engine; 9 - regenerator;
10 - supply of compressed air from automobile compressor.
The chief drawbacks of flame neutralizers are:
Insensitivity to nitrogen oxides. Moreover, the presence of an addition-
al flame source occasionally also creates an additional source of formation
of nitrogen oxides;
Poor neutralization of soot;
Increase in the content of all toxic products of incomplete combustion in
the exhaust gases when the operating conditions of the burner deviate from the
rated conditions.
Additional consumption of fuel: in carburetor engines under certain
conditions, and in diesel engines invariably. This consumption may reach
large amounts and exceed several times the fuel consumption required for the
operation of the engine (for no-load operation);
High temperatures of the neutralizer parts and units, necessitating the
use of heat-resisting steels and excluding the possibility of using flame
- 63 -
-------
neutralizers in spaces where an explosion hazard exists;
Instability of operation during changes of the load on the engine be-
cause of flame blowoffs;
Need for automation, a separate fuel supply system, and an air supply
system to sustain a stable flame.
The use of flame neutralizers does not hold much promise.
1—|9a6 fromf
—ff*$t.
Iengine
Fuel
Gas • Scour .edging- ff
Fig. 36. Diagram of flame ejection-vortex neutralizer (designed
by the Ural Scientific Research and Design Institute for the Copper
Industry) of exhaust gases of MAZ-525 dump truck:
1 and 5 - openings; 2 - reflectors; 3 - jet tube; 4 - shell;
6 - snail; 7 - combustion chamber; 8 - radial clearance; 9 - hous-
ing; 10 - neater; 11 - valve.
3. Catalytic Neutralization of Exhaust Gases
As we know, .the rate of chemical reactions, including oxidation and re-
duction reactions that take place during neutralization of exhaust gases, can
be increased several tens and even hundreds of times if they are carried out
in the presence of a catalyst, i. e., a substance reacting with the initial
product and forming with it intermediate compounds which decompose to yield
the end products and the catalyst. Thus, although the chain of reactions
proceeds via the catalyst, the latter is not consumed. This principle under-
lies the operation of catalytic neutralizers.
The exhaust gases pass through a unit filled with a catalyst. In the
presence of the latter, the unburned components rapidly oxidize to the final
oxides. Nitrogen oxides ean be reduced to nitrogen and oxygen on special
catalysts. If the neutralizer is designed for carburetor engines, the gases
are first diluted with air.
Research aimed at creating catalytic neutralizers has proceeded mainly
along the lines of seeking a catalyst which would meet the requirements of
use in an automobile, i. e., capable of operating in the gas temperature
range from 100 to 900°C, mechanically strong, not poisoned by the components
of the exhaust gases, and catalyzing the detoxication reactions of most toxic
components of exhaust gases.
- 64 -
-------
The theory of catalysis does not as yet permit a purely theoretical
selection of a suitable catalyst for a given reaction under given reaction
conditions. The selection is usually made experimentally.
A large number of catalysts were tested with exhaust gases. Pure
metals, theit oxides and other materials were employed. The best results
were obtained with platinum.
Platinum was initially used in the pure form, then experiments were
started with thin films of platinum on a porous refractory support (con-
sisting mostly of aluminum oxide A^O-j). It was found to be an efficient
catalyst for the oxidation reactions of carbon monoxide, aldehydes, and
hydrocarbons. At temperatures of the order of 300°C, platinum also has a
catalytic effect on reduction reactions of nitrogen oxides. All lead com-
pounds are catalytic poisons for pure platinum, i.e., inactivate the cata-
lyst. Thus, if there are no special recommendations in the operating in-
structions, catalytic neutralizers with platinum elements are categorically
excluded for use with engines operating on ethyl gasoline.
Considerable research on the development of catalytic neutralizers
has been carried out by the French company Oxy-France, which has patented
many designs. One of its series SB models for carburetor engines of 1 to
150 hp (Fig. 37) consists of one or two welded housings connected in paral-
lel, packed with rod-shaped catalytic elements ("oxycates") of irregular
cross section.
The labeling of the neutralizers is as follows: the letters SB indicate
that the neutral!zer is designed for carburetor engines; the number following
the letters indicates the quantity of catalytic elements. To check the oper-
ation of the neutralizer, a thermocouple is installed at its exit and con-
nected to an indicator dial in the driver cab, showing the temperature of
the exhaust gases.
The neutralizer can be installed in the automobile in any position.
At the same time, it acts as a muffler. The guaranteed service life of the
catalytic rods is 2500 bars. The company claims good performance character-
istics of the neutralizers.
Data on the operation of a warm SB-4 neutralizer installed in place of
a muffler in a new adjusted carburetor engine of 25 hp at 2500 rpm are
listed in Table 11.
LANE has developed its own neutralizer designs for the various brands
of domestic automobiles. The technology of fabrication of porous supports
and their coating with platinum was developed by the L. Ya. Karpov Physico-
chemical Institute.
The catalytic elements are used in two forms: tubules and beads.
- 65 -
-------
I
ON
Fig. 37. SB catalytic
neutralizer (built by
Oxy-France Co.) of carbu-
retor engine exhausts.
-------
Table 11
Rotational
Speed 67
Crankshaft,
rpm
500
2500
2500
2500
1500
1500
1500
2800
Load,
*
0,0
100
75
50
100
75
50
0,0
Engine
hp
0,0
25,4
19,0
12,7
14,6
11,0
7,27
4,34
Gas Temper-
ature, *C
Before) After
Neutralizer
190
590
600
515
500
510
410
150
370
610
430
370
620
3:0
300
350
CO Content, % by
Volume
Before
After
Neutralizer
10,0
4,0
0,15
0,25
7,0
0,1
0,125
0,2
0,04
0,02
0,001
0,001
0,02
0,001
0,001
0,001
Degree
of
'urifica-
tion, %
99,6
99,5
99,3
99,6
99,7
99,0
99,2
99,5
Tubules are mounted on fine wires (if damaged, the element remains on the
wire and does not lose its efficiency), and beads are poured into cartridges.
The consumption of platinum per kg of catalytic elements is 4 g for the
tubules and 2 g for the beads.
The neutralizers are labeled KKT or KNG - catalytic neutralizer of ex-
haust gases of carburetor engines with tubular or granular (spherical)
elements. The letters are followed by an indication of the flow rate of the
gas (nm3/hr) neutralized by the given model.
In the latest models of neutralizers with spherical elements, the
numbers have been used to denote the power of the engine for which the
neutralizer is designed, and the letters were changed to NK. Fig. 38 shows
a general view of an NK neutralizer.
Bench and running tests of the neutralizers, performed on domestic
carburetor engines and automobiles, showed that they:
achieve a practically complete removal of carbon monoxide from the
exhaust gases under all the operating conditions of a warm engine;
partly remove nitrogen oxides from the exhausts, and in some cases
as much as 50%; . .
afterburn 80-90% of the hydrocarbons present in the engine exhausts.
The data cited refer to the operation of a warm neutralizer.
If the neutralizer is cooled, and the engine is idling, i.e., charac-
terized bv a relatively low temperature of the exhaust gases, the efficiency
of the neutralize" when the engine is started and during the initial warmup
is practically nil.
- 67 -
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isV-•?-"•'•' ;
-------
Fig. 39. NKD catalytic
neutralizer (designed by
1ANE) of diesel engine
exhausts.
Experience in the operation of catalytic neutralizers shows that they
perform efficiently only at exhaust temperatures of 225°C and above. As a
result of this temperature limit, the warmup time of a cold unit, even in
four-stroke diesel engines, may be as long as 25 min (longer in two-stroke
engines).
Because of the low carbon monoxide content of exhaust gases, the neces-
sary temperature conditions of a warm neutralizer are not automatically
maintained when the engine is idling or operates at small loads, as in the
case of carburetor engines. This limits the time of allowed idling of a
diesel engine and of its operation at the small loads following larger loads,
i. e., the time during which an efficient neutralization of the toxic com-
ponents of exhaust gases is maintained, to 5-10 min.
An efficient operation of the catalytic neutralizer during idling and
at part loads on the engine can be achieved by preheating the exhaust gases
before they enter the neutralizer. Electric preheating is technically
feasible.
A system including electric preheating was developed at LANE. Results
of its testing with a two-stroke YaAZ-204V diesel engine showed that an
efficient operation of the neutralizer under all operating conditions of
the engine is achieved by expending 12.2 kW of power (the temperature of the
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exhaust gases is then raised by 60-70°C, being dependent on the rotational
speed of the crankshaft).
However, siich a system is very cumbersome and can be recommended only
for transport power plants equipped with an electric generator of sufficient
output. In particular, it was used for neutralizing the exhaust gases of a
YaAZ-204V diesel engine installed as the main engine of a VS-15 diesel-
electric self-propelled car designed by the State Experimental Institute of
Design and Construction for the Coal-Machinery Industry.
:The temperature of the exhaust gases can also be raised by increasing
the exhaust counterpressure. Results of experiments at LANE performed on a
YaAZ-204V idling diesel engine with a gate valve mounted in front of the
neutralizer showed that an increase of the counterpressure to 1.44 kg/cm2
ensures an efficient operation of the neutralizer even during idling, since
the temperature of the exhaust gases rises to 250°C and higher (Fig. 40).
However, the development of an additional exhaust counterpressure causes a
large increase of the smoke content. This is not observed in four-stroke
diesel engines. A check of the degree of temperature elevation of the
exhaust gases caused by an increase of counterpressure showed that an effec-
tive operation of the neutralizer during idling can be obtained at a counter-
pressure of 5000-5700 mm H20. At LANE, positive results were obtained with
a method whereby the temperature of the gases was raised by feeding a portion
of them into the intake manifold.
mo tm
rpm
Fig. 40. Dependence of temperature t
of the exhaust gases, flow rates of
air Ga and Fuel Gf of YaAZ-20W engine
on the exhaust resistances
1 - with gate valve open; 2 - with gate
valve closed.
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It should be noted that the use of these methods is restricted, since
an increase of exhaust counterpressure and by-passing of the exhaust result
in an increase of the fuel consumption, a decrease of the coefficient of
admission, and a number of other undesirable consequences. The method does
not constitute a solution to the problem.
In neutralizers for diesel engines, particularly two-stroke engines,
contamination of the catalytic elements with soot, tars, coke, and oil
droplets is possible, causing their operational failure. The catalysts are
regenerated by roasting in a furnace or by using a welding-torch flame at
a temperature of 500°C.
In order to eliminate these disadvantages, catalytic elements have
recently been used which operate in the so-called "boiling" bed (also called
fluidized, suspended, and turbulent bed)i widely employed in the metallurgical,
chemical, petroleum and other industries.
In essence, the new method consists in transforming a catalyst bed by
a stream of gas to a suspended state in which its individual particles are
in random motion. The entire mass of material behaves like a boiling fulid.
There is not even any separation of the individual particles of different
size and weight, i. e., the light particles do not rise in the bed, and the
heavy ones do not descend.
Owing to this vigorous motion of the catalytic elements, the formation
of scale on their surfaces is prevented, and they clean themselves. More-
over, the rate of the exchange between the gas and the catalyst increases.
There is a considerable (fivefold or greater) decrease in the hydraulic
resistance of the bed as compared to that observed in a stationary bed of the
same thickness. This decreases the power loss of the engine and reduces the
soot content of its exhaust gases.
A disadvantage of the operation of a catalyst in a fluidized bed is its
increased wear. However, this disadvantage can be eliminated by using a
catalyst of increased mechanical strength.
A fluidized catalyst bed was first used in engine exhaust neutralizers
by the staff of the Sverdlovsk Mining Institute.
In 1962, the leading manufacturer of catalytic neutralizers, the French
company Oxy-France, began the production of series DN units operating with
a fluidized bed catalyst.
Fig. 41 shows the design of one of them, the DN-300 model.
The neutralizer can operate only in the horizontal position and consists
of three main parts:
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The center - a reactor in the form of a rectangular steel housing divided
into separate compartments two-thirds filled with spherical catalytic elements
3-5 ram in diameter and closed off with screens on the top and bottom;
A lower housing distributing the exhaust gases over the intake screen of
the reactor;
An upper housing acting as the gas collector.
- 72 -
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All the parts are joined with yokes. The joints are sealed with asbestos
cord of square cross section placed in special grooves.
The company manufactures neutralizers operating with a fluidized bed
catalyst arid neutralizers for carburetor engines. They are labeled with
Indices NE. Some of these designs are in vertical versions.
According to the French data, when the neutralizers under consideration
operate with engines in sound condition, they achieve the following total
neutralization of toxic components of exhaust gases: series NE from 80 to 90%,
and series DN from 70 to 857..
In the Soviet Union, a DN-200 neutralizer was tested on an YaMZ-236
four-stroke diesel engine. The tests showed that:
At engine loads greater than 50% of maximum load, there is a removal
of all aldehydes and 70-80% carbon monoxide from the exhaust gases, and the
carbon monoxide content of the gases past the neutralizer does not exceed
0.03% by volume at all rotational speeds of the crankshaft;
In the load range from 25 to 50% of maximum load, there is a 50-60%
removal of aldehydes and 35-50% removal of carbon monoxide from the exhaust
gases; the concentration of aldehydes in the gases'past the neutralizer does
not exceed 0.011 mg/1, and that of carbon monoxide, 0.026% by volume;
At loads of the cool engine from idling to 25% of maximum load, there
is practically no neutralization of the exhaust gases.
LANE also has developed designs of neutralizers with catalytic elements
operating in a Sluidized bed. The labeling KNDSh was adoped for these models.
Numerous institutes (Karpov Physicochemical Institite, Institute of
Chemical Sciences of the Kazakh Academy of Sciences, and others) are continuing
research on the development of a cheaper catalyst capable of replacing
platinum.
Fig. 42 illustrates curves showing the change of the carbon monoxide
content of exhaust gases from a "Moskvich-407" engine, after they have passed
through neutralizers filled with platinum or recently developed nonplatinum
elements, as a function of the power'developed by the engine. The curves
pertain to crankshaft speeds of 1000, 1500, 2000 and 2500 rpm.
The tests were made on an NK-150 neutralizer developed by LANE and
differing from earlier designs in the oval shapes of the housing and reactors.
This was done for the purpose of more conveniently fitting the neutralizer to
the automobile. The weight of the equipped neutralizer was 6 kg, and the
outside dimensions were 646 x 252 x 163 mm. A volume of 1.34 1 of catalytic
elements was poured into the reactor.
The curves of the graphs make it possible to compare the performance of
neutralizers with platinum and nonplatinum elements. The comparison shows
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that only under conditions corresponding to a crankshaft rotating at 1000 rpm
is the efficiency of operation of noiiplatinum catalytic elements markedly be-
low that of the platinum ones. This is explained by the fact that the minimum
temperature of efficient operation of nonplatinum elements is higher than that
of platinum elements, and the conditions at n = 1000 rpm correspond to rela-
tively low exhaust temperatures.
a) n=100Qrpn n=1500rpm
Platiaua elements
n=2000rpm n=2500rpm
i
'^
1
o.
3
•4
J
I
1
f.
^
mmf
SH.
3 i
*-
^.
^
•w
X
*•
^
V V «
V
X
.
f
»*»
•^
"n
-*
•**
^n
I
C?
•^
a>
•^
s
)
^
t
s
^
a
«•»
**n
^**
•^*
>>
a a a
^
b
3
U
^
it
)ii
>»»
k?
''^
•s».
ts a B
H.op-ylatinug elements
v a&aoa
Engine power, N._
_:• *'
Fig. 42. Graph of ohMga of carbon monoxide content in exhaust
gases of "Moskvich-tOT' engine after passage through NK-150
catalytic neutralizer.
The average efficiency of neutralization under the indicated conditions
ranges from 80% to a virtually complete neutralization for the alumina-platinum
catalyst, and from 65% to a virtually complete neutralization for the non-
platinum catalyst. Thus* the new elements can sucessfully replace platinum
ones. Tests of units with the new elements are being continued.
For the low exhaust temperatures observed in diesel engines, LANE tested
hopcalite (a mixture of 60% active manganese dioxide MnO£ and 40% copper oxide
GuO) as the catalyst under laboratory conditions. The experiments showed
that It neutralizes carbon monoxide very well under all operating conditions
of the diesel engine, but is marked by a low mechanical strength. Ways of
increasing Its strength are being sought. Hopcalite was used in a combined
neutralizer of exhaust gases of an YaAZ-204V diesel engine installed on a
VS-15 diesel-electric car. The combined neutralizer consists of two units:
a liquid unit and a low temperature catalytic unit filled with hopcalite.
This neutralizer was discussed In §1 of this chapter.
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4. Thermocatalytic Neutralization Of Exhaust Gases
The chief disadvantage of a catalytic neutralizer is that it operates
efficiently starting at a certain temperature of the exhaust gases (225°C).
It is natural therefore to try to develop a composite design of the unit, in
which the gases would first be preheated in a flame afterburner, resulting
in a partial afterburning of the unburned toxic components, and would
finally be neutralized on the catalyst.
Neutralizes operating on this principle have been named thermocatalytic
neutralizers. Their development was started at the Sverdlovsk Mining Institute.
One of its designs, intended for the neutralization of exhaust gases of a
D12A diesel engine installed on an MAZ-525 dump truck, is illustrated in Fig.
43.
The neutralizer consists of two units connected in series - flame pre-
heater of gases 4 and catalytic neutralizer 6. Burner 5 without a nozzle
generates a flame in the preheater. When passing over spiral conduit 1 of
the preheater, the fuel vaporizes and enters the combustion chamber while
being vigorously mixed with the air supplied by fan 3, which is driven inde-
pendently. The fuel-air mixture is ignited either by the heated spiral of
plug 2, or by the flame front under steady combustion conditions.
The combustion in the chamber has an autonomous course that is inde-
pendent of the operating conditions of the engine; and thus a steady combustion
is achieved. When the engine runs at large'loads, in order to economize
the fuel and keep the unit from overheating, the fuel supply to the chamber
is automatically shut off.
The preheated gas enters cyclone 7, attached to the outer wall of reaction
chamber 9. Here the fine solid and liquid particles of soot, tars, oil, etc.,
which earlier had not burned completely, undergo the final stage of combustion.
The coarse particles are thrown against the walls and are collected in hopper
11. The cyclone also recovers the heat evolved by the catalytic oxidation
processes. The exhaust gases, warmed up and purified after the removal of the
solid and liquid particles that they contained, enter reaction chamber 12
of the catalytic neutralizer.
Here they traverse the catalyst beds: lower fluidized bed 10 and upper
8, which is at rest. The purpose of the lower bed is to neutralize a large
portion of the toxic components. The upper bed completes the neutralization
process and prevents the escape of fine catalyst particles from bed 10.
Tests of the above neutralizer demonstrated its stable operation and,
when an active catalyst was used, a satisfactory neutralization of the toxic
products of incomplete fuel combustion. The hydraulic resistance of the
neutralizer slightly exceeded the resistance of a standard muffler.
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The neutrallzer simultaneously acted as a noise muffler.
Designs of thennocatalytic neutralizers are being developed in which the
combustion is arranged directly in the flow of exhaust gases, with the oxygen
present in the aerosol used as the oxidant. Composite neutralizers with
nozzle burners, with trapping of soot in a special filter that simultaneously
burns it up, etc., also are being worked on.
The chief drawbacks hindering the adoption of thermocatalytic and
composite neutralizers in automobiles are as follows:
Complexity of design;
Necessity of additional consumption of fuel;
High temperatures of certain parts;
Large consumption of catalyst operating in the fluidized bed because
of its low mechanical strength;
Large weight and overall size.
v
Gas
Fig. 43. Thermocatalytic neutralizer (designed by Sverdlovsk
Mining Institute) for exhaust gases of D12A diesel engine.
5. Electric And Ultrasonic Filters
The principle of operation of electric filters consists in the elec-
trolysis of the solid and liquid particles present in the gases in suspension,
- 76 -
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followed by their deposition on the electrodes. This method has been fairly
popular in industrial gas purification. In practical detoxication of exhaust
gases, electric filters are seldom used, since their efficient operation re-
quires cumbersome gas coolers by means of which the toxic components are
converted to the liquid and solid states.
In 1961, a neutralizer operating in the following manner was developed
and tested in Switzerland. First, the exhaust gases were cooled in a special
cooler to 30°C. Some toxic components such as a portion of the hydrocarbons,
acrolein, and many of others deposited on the walls of the cooling chamber.
The gas then entered the electric filter. In its ionizing compartment, the
particles suspended in the gas interacted with ions of oxygenj nitrogen
and other gaseous components, an electric charge was produced, and the particles
were directed into the trapping compartment, where they deposited on the
electrodes in a high-voltage electric field.
According to the statements of the authors of this invention, for a
consumption of 15 W of power, the filter completely trapped soot and other
solid particles, there being a very low hydraulic resistance. After 500 hrs
of operation, the filter required washing and drying.
Lately, the Industrial use of ultrasound has been increasing. In
particular, it is used to remove noxious impurities from furnace fumes.
Ultrasonic waves cause a rapid vibration of the solid particles suspended in
the gas, causing their agglomeration, coarsening, and hence, an easy trapping.
Thus far, ultrasound has found no direct applications in the neutralization
of engine exhausts, However, there are very good reasons to assume that
it can be used, if not directly for the purification of gases, then at least
for the acceleration of certain processes associated with purification. For
example, in liquid neutralizers, ultrasound can be used for speeding up the
chemical dissolution of toxic gas components, coarsenging solid particles
in solution to make them settle faster to the bottom, and preventing their
escape with gases.
6. Crankcase Gases And Control Of Their Toxicity
With the exception of the intake stroke, the pressure in the crankcase
is much lower than in the engine cylinders. As a result, part of the fuel-air
mixture and exhaust gases escape through various leaks from the combustion
chamber into the crankcflse. These gases mixed with oil and fuel vapors are
called crankcase gases.
The gases escaping from the cylinders consist, on the average, of 807.
of the fuel-air mixture and 20% of exhaust gases. This composition is ex-
plained by the fact that the seeping of gases from the cylinder takes place
chiefly at high pressures In the combustion chamber, i. e., at the end of
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compression during combustion and at the start of expansion. Moreover,
additional conditions favoring the escape of gases are produced when there
is a change in the direction of motion of the piston in the extreme upper
position, when the piston rings shift in the grooves. In a new engine, gas
leaks are slight, but they gradually increase as the engine is used.
The adverse effect of crankcase gases is that they dilute the crank-
case oil, increase the explosion hazard, are the chief source of water
formation in the crankcase, and decrease the useful life of the oil by
contaminating it and raising the acidity. The crankcase gases together
with the exhaust gases poison the atmosphere when released. It has been
found that crankcase gases account for about 40% of the total hydrocarbons
emitted by automobile engines.
Forced ventilation of the crankcase has long been used in the automobile
industry as the chief method of controlling the adverse effect of crankcase
gases. The main requirement of this method is as follows: the gases must
be eliminated before their temperature drops to a value at which the fuel
and water vapors which they contain begin to condense and descend into the
oil.
The gases can be sucked out by creating a vacuum in the intake system
of the engine and by utilizing the fluid energy of the fuel-air mixture.
Accordingly, the following three systems of forced crankcase ventilation
are used, involving suction of gases into:
the air filter;
the intake manifold (past the carburetor);
the air filter and the intake manifold.
The graph (Fig. 44) showing the operation of the system of suction
of crankcase gases into the air filter shows that as the speed of the auto-
mobile rises, there is an increase in the escape of gases into the crankcase
(curve 4) and in the amount of air entering the air filter from the crankcase
(curve 1). However, during idling and at small loads, the crankcase venti-
lation is insufficient in this system. Here the crankcase gases will escape
into the atmosphere through the oil hole.
This disadvantage is eliminated in a system where the gases enter the
intake manifold. A graph of its operation (Fig. 45) shows that during idling
and at small loads, an adequate ventilation of the crankcase is achieved
(curve 1). However, »t large loads on the engine, when the amount of crank-
case gases increases (curve 3), the momentum of the jet of the fuel-air
mixture is insufficient for the suction of all the gases. A portion of them
escapes into the atmosphere through the oil holes.
The combination of the two systems makes it possible to achieve the
suction of crankcase gases under all operating conditions of the engine.
-------
In practice, the suction systems are connected to each other with a
control valve in-between which prevents the gases from entering the intake
manifold from the air filter. Thus, the crankcase is ventilated by a system
connecting it to the intake manifold, but under all conditions of large loads
this system is connected to the system in which the crankcase is vented into
the air filter.
0.03
0 16 32
80 #v,km/hr
Fig. 44, Graph of the operation of a system of
gas suction fron orankcase into air filter:
1 - admission of total amount of crankcase gases
and air into air filter vs. traveling speed of
automobile; 2 - amount of crankcase gases escap-
ing through oil hole; 3 - amount of fresh air
entering the air filter; 4 - emission of crank-
case gases vs. the traveling speed of automobile.
0 (S 32 48 61 80 16 .
Fig. 45. Graph of the operation of the system of
suction of gases from the crankcase into the intake
manifold:
1 - admission of the total amount of crankcase gases
and air into the intake manifold vs. traveling speed
of automobile; 2 - amount of fresh air entering the
intake manifold; 3 - emission of crankcase gases vs.
traveling speed of the automobile; 4 - amount of
crankcase gases escaping through oil hole.
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Pig. 46. Operation of combined system of
gas suction from the crankcase into the air
filter and into the intake manifold:
1 - admission of total amount of crankcase
gases and air into the air filter and into
the intake oanifold vs. traveling speed of
automobile; 2 - admission of total amount
of crankcase gases and air into the air
filter along vs. traveling speed of auto-
mobile; 3 - emission of crankcase gases vs.
traveling speed of automobile; 4 - admission
of total amount of crankcase gases and air
into the intake manifold alone vs. travel-
ing speed of automobile; 5 - amount of
fresh air admitted.
0 32 6& 96 128 ISO 132
V,km/nr
A graph (Fig. 46) of the operation of the composite unit shows its
satisfactory operation in all engine runs. Other combined systems also
exist. In particular, suction of the crankcase gases into the exit
manifold or neutralizer is employed.
-.BO -
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Chapter V
PROSPECTIVE AUTOMOBILE ENGINES AND EXTENT OF POSSIBLE POISONING OF THE
ATMOSPHERE BY THEM
Scientific research laboratories, design organizations, and industrial
enterprises in many countries throughout the world are studying and testing
improved designs of internal combustion engines as well as fundamentally new
energy sources. In addition to the analysis of such indices as power, econo-
my, complexity of construction, cost, etc., considerable attention is given
to the degree of possible contamination of the air reservoir by the engines.
All prospective engines can be divided into two major groups: mechanical
energy converters whose design is dependent on moving parts, and nonmechani-
cal converters which transform one of the forms of energy (chemical, thermal,
nuclear) directly into electrical energy in the absence of parts that
rotate or execute a translational motion. The present chapter discusses
the diagrams and explains the principles of action of certain improved and
new automobile engines being developed. It should not be assumed that sooner
or later they will all be adopted in automotive engineering. It is quite
possible that some of the experimental designs will never leave the
laboratory.
1. Mechanical Energy Converters
Piston-type internal combustion engines. Piston engines are currently
the main transport engines.. One of the ways: of radically improving them
which will reduce the toxicity of the exhaust gases is to reorganize their
working process. This can involve the use of the latest achievements in
physics and chemistry. The possibility of using energy sources other than
ignition plugs to ignite the working mixture is not excluded. In particular,
there are no fundamental objections to the use of laser beams. An efficient
ignition and improved atomization of the fuel should increase the extent of
combustion and reduce the emission of toxic substances.
Good results can be obtained by developing a laminar distribution of the
fuel-air mixture. The process consists essentially in producing a distribu-
tion in the combustion chamber whereby a rich-mixture zone is produced only
in the vicinity of the ignition source (for example, a plug), and as the
distance from this source increases, a lean-mixture zone is formed. In this
case, the combustion occurs with a high degree of completeness. The toxicity
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of the exhaust components being currently standardized decreases. The first
test of this arrangement of the process is the creation of prechamber-flame
ignition.
To achieve a pollution-free operation of engines, closed and semiclosed
cycles have been developed. In the former case, the fuel and the oxidizer
are separately supplied to the engine. The combusion products are separated.
A portion of them (carbon monoxide, aldehydes, hydrocarbons, etc.) is
returned to the cylinders for additional combustion, and another is collected
in special cylinders. Similar systems have already been used in the submarines
of a number of nations. Their chief disadvantages are bulkiness and a high
cost. A basic diagram of a closed cycle system is shown in Fig. 47.
A
Fig. 47. Basic diagram of system operating on a closed
cycle: 1 - mixer} 2 - fuel cylinder; 3 - oxidizer_
cylinder! 4 - cylinder for end products of combustion;
5 - engine; 6 - pump; 7 - component separator.
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For automobile engines, usually operated under conditions where there
is no deficiency of oxygen for the combustion of fuel, the above system may
be simplified (Pig. 48). In operation on a semiclosed cycle, the oxygen for
combustion is taken from the atmosphere: nitrogen, carbon dioxide, and water,
which are not harmful to man, are discharged.
The difficulty in building engines operating on closed and semiclosed
cycles lies in the development of separators of the exhaust components.
Rotor (volumetric) internal combustion engines. A diagram of the
operation of one type of rotor engine with a planetary motion of the rotor
is illustrated in Fig. 49. Other types do not differ from this type in
operating principle. The working cycles of rotor engines do not differ from
those of piston engines. The chief advantage of rotor engines lies in the
absence of reciprocating parts, which makes it possible to substantially
increase the rotational speed of the shaft and decreases the weight and
overall size of the engine.
Fuel
Air
Fig. 48. Basic diagram 'of a
semiclosed cycle system:
1 - engine; 2 - mixer; 3 - com-
ponent separator; 4 - pump.
Since in rotor engines the rate of change of the volume of its expanding
gas can be controlled by means of attachments, this should affect the
composition of the exhaust gases. The presence of centrifugal forces in
the zone of formation of the working mixture also simplifies the creation
of a laminar distribution of the mixture, which should result in a better
arrangement of the combustion process and in a reduction of the toxicity of
the exhaust gases.
Gas-turbine engines. Some foreign companies are already preparing
automobiles powered by gas-turbine engines for production. Experimental
-------
models of such automobiles are also being tested in the Soviet Union. In
automobile construction, the engines which have found applications have been
mainly in the 200-1000 hp range.
Fig. 49. Diagram of operation of the rotor engine:
a - intake; b - compression; c - ignition; d - power
stroke (expansion); e - exhaust.
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The specific weight of a modern gas-turbine engine (weight per unit
power) and its size are smaller than those of piston engines, but the cost
of a gas turbine engine is higher. From the standpoint of reduction of
the toxicity of exhaust gases, the gas-turbine engines are more acceptable
than piston engines with regard to the components being Standardized at
the present time. Such engines can operate .stably on lean mixtures, which
have lower combustion temperatures. This reduces the content of carbon
monoxide, soot hydrocarbons and other toxic compounds in the exhaust gases,
with the exception of nitrogen oxides.
Jet engines. Regardless of the type of jet engine, they all operate
on the same principle: hot gases are ejected from nozzles into the atmosphere
at a high velocity. This produces a thrust which increases with the amount
of gases ejected and with the ejection velocity.
The motive power acts directly on the automobile, so it is no longer
necessary to transmit the tractive effort from the engine to the wheels. As
a result, the force moving the automobile is independent of the friction
between the tires and the road surface. This is an obvious advantage of
the jet engines.
However, the fact that a-powerful gas flow is required to produce a
sufficient moving force cancels out this advantage. The overall size and
weight of the jet assembly turn out to be very large. The high ejection
velocity of the gases is not permissible from the standpoint of traffic
safety considerations.
Stirling engine. In 1816, the Scottish clergyman Robert Stirling
invented a new external combustion piston engine. It was characterized by
a very large overall size and a low efficiency. Improvement of the engine
proceed at a very slow pace. In 1855, the Stirling engine bad an efficiency
of 5-7%, power of 2 hp, weight of 4 tons, and occupied 21 nr of space. It
seemed as though it would never be developed. However, starting in 1937, inter-
est in this engine was reawakened, first in Holland and later in the USA.
Recent studies of the engine made by the General Motors Co. showed that:
The efficiency of the engine can reach 50%, which is far above the
efficiency of gas turbines (25-28%), best models of carburetor engines,
(28-30%) and best models of diesel engines (32-40%), but the specific weight
of this engine is higher than that of the other engines;
The engine operates satisfactorily at constant loads, but the rotational
speed of its shaft has thus far been moderate;
The engine operates without noise on different fuels: solid, liquid,
and gaseous.
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The engine can be made to work without poisoning the atmosphere with
exhaust gases.
The engine has a working piston 1 (Fig. 50) and a displacing piston 4,
both located in the same cylinder.
The piston rods are located one within, the other and connected to a
crankgear. The upper part of the cylinder is steadily heated by any suitable
heat source (combustion chamber with solid, liquid or gaseous fuel, electric
heater, etc.), while the lower part is steadily cooled by a cooler 2. Accord-
ingly, the space within the cylinder is divided into two cavities: one hot 5,
and the other cool 3; heat exchanger 6 increases the economy of operation of
the engine, and cavity 7 acts as a buffer.
The engine operates in the following manner:
Stroke I - cooling. The displacing piston is located in the hot space,
and the working piston is in its lowest position. Much of the gas is cooled
in the cold cavity;
Stroke II - compression. The working piston moves upward, compressing
the cool gas;
Stroke III - heating. The displacing piston moves downard. The
cool gas is transferred to the space above it, being first warmed up in
the heat exchanger. The gas is heated in the hot cavity;
Stroke IV - expansion (working stroke). The hot gas expands, doing use-
ful work, while at the same time heating the heat exchanger. The working
piston, by transferring the gas located under it into the buffer cavity and
compressing it, stores up energy for the next compression of the working gas.
At a symposium of engine specialists held in the USA in October 1963
it was noted that the Stirling engine will not find any rapid practical
applications in automotive engineering, since it has a number of essential
disadvantages. However, its use in the automobile has not been excluded.
Since the heating of the hot cavity takes place on the outside and is
not directly connected with the course of the working process within the
cylinder, it becomes possible to ensure the combustion of any hydrocarbon
fuel with a minimum ejection of toxic substances.
2. Nonmechanical Energy Converters
A radical means of reducing the poisoning of the air reservoirs of
cities and industrial plants is to replace automobiles with carburetor and
diesel engines by electrically driven vehicles.
- 86 -
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Fig. 50. _ Diagram of operation of Stirling engine:
1 - working piston; 2 - cooler; 3 - cold cavity; 4 - displacing piston;
5 - hot cavity; 6 - heat exchanger; 7 - buffer cavity: I - cooling;
II - compression; III - heating; IV - working stroke (expansion).
Obviously, electrically driven trolley buses and electric rail transport
cannot constitute a serious rival to automobile transportation because of its
limited maneuverability and the high capital investment required by the
trunk lines.
In the USSR, the first attempts to replace automobiles by electrically
driven public transportation vehicles date back to the 1930's, when on the
suggestion of the eminent Soviet electrical enginer G. I. Babat, the first
studies anywhere on the use of high-frequency wireless transmission of
energy to transport vehicles were carried ou't. Babat's "hf-mobiles" had
receiving induction units, and the trunk lines were equipped with high-frequency
underground! power communications. By storing up excess electrical energy
in chemical storage batteries, the hf-mobiles were able on ordinary thorough-
fares to switch from one specially equipped line to another. The first high-
frequency lines were tested in the USSR in the 1940's. However, for various
reasons the hf-mobiles were not widely adopted.
- 87 -
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At the present time, the prospects of using electrically powered
transportation are chiefly dependent on the development of high-efficiency,
self-contained sources of electrical energy. These sources, based on
principles of direct conversion of various forms of energy into electrical
energy, are commonly called nonmechanical converters. It is understandable
that the power plant of an electric car as a whole, equipped with a power
source and an electric motor, is not nonmechanical. Nonmechanical converters
include physical sources: magnetohydrodynamic, thermoelectric, and thermionic
generators, and also chemical energy sources: storage batteries and fuel cells.
Magnetohydrodvnamic generators of electric energy (MHD generators).
As we know, if a conductor is moved in a magnetic field, an electric current
will be induced in it. This is the principle underlying the operation of most
modern electric generators. The conductor in motion is not necessarily metallic.
It can also be an electroconductive liquid, and even gases. Although gases in
the natural state poorly conduct electric current, they can be transformed
into good conductors when subjected to ionization. A completely ionized gas,
i.e., one in which there are no neutral molecules or atoms, is called a plasma.
In order to obtain a plasma, a high gas temperature is required, sometimes
as high as millions of degrees. This is very hard to achieve. It is equally
difficult to hold it in any conduit, i.e., the walls of the container simply
cannot withstand such temperatures.
However, in order to use a gas as the conductor of an electric current,
there is no need to convert it to a plasma, since a gas ionization of 0.1%
(one out of every 1000 gas molecules is dissociated) is sufficient to produce
a conductivity in the gas equal to about one-half that of a plasma. However,
even in order to produce a gas with 0.1% ionization, a temperature of the
order of 2750°C, is required. This is the chief obstacle to a possible
application of MHD generators toautomobiles. The most probable area of appli-
cation of such generators is a generators of current in high-output electric
power plants. The installation of MHD generators in diesel locomotives and
tractor-trailer combinations is possible* '
A basic diagram of an MHD generator assembly is shown in Fig. 51. Atmospheric
air compressed to 5 kg/cur with a compressor is supplied to the combustion
chamber through a heat exchanger. From the latter, the mixture of air and
combustion products, at a temperature of about 2750°C, which gives a degree
of gas ionization of 0.1%, enters the MHD generator through a supersonic
nozzle, expanding to an excess pressure of 0.1 kg/cm^. At this point, a
magnetic field acts on the gas. The electric current which is thus produced
is picked up by the electrodes bathed by the gas. From the MHD generator,
the gases at a temperature of the order of 2000°C are directed into the
heat exchanger, then released into the atmosphere. Experimental models of MHD
generators operating at lower temperatures have been constructed.
- 88 -
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Transfer of
electrical
energy to
0 external
cirouit
Exhaust
intake
Fig. 51. Diagram of open-cycle MHD generator assembly
operating on hydrocarbon fuel:
1 - combustion chamber; 2 - heat exchanger; 3 - compressor.
The toxicity of the gases discharged by such an assembly will probably
be similar to that of the exhaust from gas turbines.
Thermoelectric generators of electrical energy. As we know, most metals
are good conductors of electricity. This is because, even at room temperature,
the metals contain many free electrons whose ordered motion in a given direction
cdnstitutes an electric current. If no voltage is applied to a metal rod,
the free electrons move in random fashion. If one end of the rod is heated
and the other cooled, the electrons in.the former will move faster than in
the latter. As a result, a preferential motion of electrons from the hot end
to the cold will be established, and an electric current will be generated
in the rod. This current cannot be picked up by an external circuit if the
rod and the conductor are made of the same material. Indeed, an electric cur-
rent with a direction opposite to that in the rod will also be generated in
the conductor with one hot and one cold end. However, if the rod and the
conductor are made of different metals with different numbers of free electrons,
the rate of their motion from the hot end to the cold will be different, and
a slight net current will flow along the closed circuit. This effect was
discovered as long ago as 1821. It is used in the manufacture of various
thermocouples (the electromotive force generated on heating is proportional
to the temperature difference between the hot and cold junctions). The use
of the Seebeck effect proved impossible for the creation of high-output power
sources. Attempts to connect individual thermocouples in series have been
unsuccessful. As the number of the connected couples increases, there is a
marked increase in the total electrical resistance of the circuit.
- 89 -
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Nevertheless, after a long selection of different materials, a thermo-
electric battery with an efficiency of 3% was successfully assembled in 1950.
The situation changed radically with the discovery and development of
semiconductors. For the same temperature difference, a thermoelectromotive
force is generated in semiconductors that is 40 times (or more) greater than
the thermoelectromotive force in metals. Depending on the nature of conduc-
tion, semiconductors are divided into three types: n-type, p-type, and intrin-
sic semiconductors. n-Type semiconductors contain many free electrons. They
are the carriers of negative charges. On the contrary, in p-type semiconductors
there is a deficiency of electrons. A crystal lattice site where an atom lack-
ing an electron is located has a positive charge and is called a "positive hole",
If the atom borrows an electron from a neighboring atom of the crystal, it
becomes neutral, and the atom which has lost the electron becomes the "positive
hole". Thus, the "positive hole" effectively moves through the material of
the semiconductor, and for this reason p-type semiconductors are frequently
called carriers of positive charges. Intrinsic semiconductors are carriers
of both negative and positive charges.
By selecting appropriate semiconductors, thermoelectric generators with
an efficiency of up to 107» have been successfully constructed.* A basic
diagram of one of the generators operating on hydrocarbon fuel is illustrated
in Fig. 52.
Combustion products
Cooler
Fuel
Air
Cooler
Fig. 52. Diagram of thermoelectric generator operating on hydro-
carbon fuel. The heat of escaping combustion products is not used.
1 - p-type semiconductors 2 - insulator; 5 - n-type semiconductor;
A - cooler; 5 - injector.
* This value of the efficiency refers only to the generator. When the generator is used in an
automobile, it is necessary to take into account the energy loss in transmission to the wheels.
- 90 -
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There are also generators operating on nuclear fuels.
If the heat of the combustion of hydrocarbon fuels is used for heating
semiconductors, the toxicity of the emitted products of such units will be
the same as in the case of gas-turbine engines.
Thermionic generators of electricl energy. If a metal is heated
intensely and placed in a vacuum, part of the free electrons may acquire a
considerable energy, overcome the forces of attraction of other molecules,
and escape from the metal. This effect is called thermionic emission or, in
honor of its discoverer, the Edison effect. The energy required for an
electron to break away from the metal surface is called the work function.
Haated oathode
Anode
Escape to exT
ternal circuit
Fig. 53. Diagram of operation of^simplest
diode radio tube. The same principle governs
the operation of the thermoelectronic generator.
The Edison effect is utilized in diode radio tubes (Fig. 53). Two
electrodes, a cathode and an anode, are placed in an evacuated bulb (the
tube is therefore called a diode). The cathode is heated. The electrons
whose energy exceeds the work function of the cathode leave the latter in
the direction of the anode. Here they overcome the potential barrier corre-
sponding to the work function of the anode, i.e., give up part of the energy
in order to "enter" the material of the anode. This energy is converted to
heat which heats the anode. Since the work function of the cathode is
usually higher than that of the anode, the excess energy in the form of an
electric current is removed by the external circuit. If the radio tube is
treated as a thermionic converted of the thermal energy heating the cathode
into electrical energy, its efficiency is very low and equal to approximately
0.00001%. This is not very import in radio equipment, where the required
current intensity does not exceed a few microamperes.
- 91 -
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Thermionic generators, used for the industrial generation of electric
power, operate on the same principle. However, their efficiency has now
reached approximately 20%. This is accomplished by the following methods:
The cathode material selected has a large work function. The cathode
is heated to high temperatures, of the order of 2000-2200°C. Only refractory
metals are used & suitable material is one in which after 1000 hr of operation
at the working temperature, the layer thickness due to vaporization decreases
by not more than 0.127 mm);
The material chosen for the anode has a small work function. The anode
is cooled so that its working temperature is 550-HOO°C below the cathode
temperature;
The space charge is eliminated, and neutralized. Each electron which
has escaped from the cathode is surrounded by electrons which have left
earlier. The electrons repel one another, and as a result, many electrons
return to the cathode without reaching the anode. The charge of the escaped
electrons is termed the space charge. To eliminate it, the cathode and
anode are placed as close to each other as possible (in 1960, the American
company General Electric produced converters with interelectrode distances
of 0.0127 mm and less), or an additional electrode is placed between them
which imparts a high velocity to the electrons. The space charge is neutralized
by introducing into the bulb vapors of cesium, whose molecules readily ionize
on colliding with the electrons. A plasma cloud is thus formed which consists
of positively charged cesium ions, ftxfcind* from the cathode to the anode, and
neutralizes the space charge.
As in the case of thermoelectric generators, the use of thermionic gen-
erators in automobiles is still problematic. However, because they can have
higher efficiencies, they should be given priority. Their best prospects
are for application in the atomic industry.
From the standpoint of poisoning of the atmosphere, units employing
thermionic generators are similar to those with thermoelectric generators.
Electric automobiles with storage batteries. Designs of storage-battery-
powered automobiles have been adequately developed. At the present time, there
are about 40,000 electric care with lead storage batteries being operated in
the world, excluding local electric transport (streetcars and trolleys). The
main unit of an electric car is the storage battery.
The characteristics of modern storage batteries are listed in Table 12.
- 92 -
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Table 12
Type of Storage Battery
Lead
Iron-nickel
Cadmium-nickel, lamellar
Cadmium-nickel," sealed,
nonlamellar '
Silver-cadmium
Silver-zinc
Nickel-zinc
Air-zinc
Specific
Power for
;5-Hour
>ischarge.
W/kg
-4 '
3,5—4
4—4,2
9—10
18—23
20—25
10-13
20—30
Specific
Energy for
5-Hour. '
Discharge,
W hr/kg'
20—25
18-20
18-25
25—40
60—90
80— IfiO
60—70
100—150
Number of
Discharge-
Cnarge ,
Cycles
Up to 1000
Up to 1800
Up:to2000
1500—3000
200—300
300—400
Up to200
No Data
Capacity for Discharge
Under Forced Conditions
Good
Poor
Satisfactory
Good
Satisfactory
Good
Good
Good
Cost,
Relative
Units
1
1.2-1.5
4
20-25
5
6
2—3
He Data
As is evident .from the table, the silver-zinc storage batteries, which
are the best of .the commonly used batteries from the standpoint of specific
characteristics in long-term operation, are tens of times inferior to mass-
produced heat engines. However, the basis for the use of chemical storage
batteries as energy sources for electric cars in large cities is the fact
that .because of the capacity of storage batteries for fast recharges, an
electric source can be used whose power, is 4-5 times smaller than the power
produced by heat engines. A number of American experts hold that despite
their high cost, silver-zinc storage battereis can find applications in
mass-produced machines: their cost is due to the high content of silver
(up to 30% by weight), but 99% of the silver can be recovered and used again.
Special nickel-
-------
automobile transportation can actually count on the heaviest, but at the
same time the cheapest, lead and iron-nickel batteries. Depending on their
mineral resources different countries will prefer the former or the latter.
Thus, in Great Britain, which operates more than one-half of the existing
electric cars, lead batteries are chiefly employed.
In the Soviet Union, the traction systems used are mainly iron-nickel
storage batteries.
Among the new. storage batteries, the most promising is for use in
traction are nickel-zinc and air-zinc types. The latter have characteristics
that are equal to those of silver-zinc batteries, but they should be only
twice as expensive as lead batteries in mass production. According to
literature data, air-zinc batteries are being developed in the U.S.A. and
England.
In 1966, reports appeared in the literature on fundamentally new types
of storage batteries being developed in the U.S.A: sodium-sulfur and lithimi-
chlorine types; In these batteries, the electrodes are in the molten state,
and the electrolyte is a solid ion-conducting oxide matrix. Sodium-sulphur
and lithium-chlorine storage batteries are operated at working temperatures
of several hundred degrees (500-600°C.). The specific power and specific
energy are as high as 70-80 W/kg and 300-400 W hr/kg, which is sufficient to
run a medium-class electric car without recharging over distances of 150-200
km under urban conditions. The specific characteristics of molten electro-
chemical systems allow forced charging rates.
In practice, such storage batteries can be charged up in a few minutes.
The companies Ford and Chrysler, which have developed the sodium-sulphur
and lithium-chlorine storage batteries,, propose to market experimental
electric cars with such batteries in 1970-71.
Electtic cars powered by storage batteries do not contaminate atmospheric
air,
Fuel cells. Perfectly pure water is a poor conductor of electric
current. However, it can be changed into an adequate conductor by dissolving
a small amount of inorganic acids or salts. Why is this so?
Let us assume that sulfuric acid (ILSO^) is dissolved in water. When
it comes in contact with water, the electrically neutral sulfuric acid mole-
cule breaks up into three ions: two positively charge hydrogen ions (H+) '
and one sulfate ion bearing a double negative charge (SO^).
- 94 -
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This process, called dissociation, is represented by the formula
H2S04 -" 2H+ + S04".
If a voltage is applied to the electrodes, the positively charged ions
will migrate toward the cathode, and the negative ones toward the anode
(Fig. 54). The solution will thus conduct an electric current.
When the sulfate ion reaches the anode, it will give up to the latter
its two "excess" electrons, forming an electrically neutral group of atoms
S04, which will immediately react with water to yield sulfuric acid and oxygen
2S0
2H20
2H2S04
Oxygen will be evolved in the gaseous form at the anode* and the sulfuric
acid molecule will again dissociate into ions.
^
/
;/
Fig. 54. Diagram of electrolysis.
As they approach the cathode., the hydrogen ions acquire the excess electrons
located in this region, are neutralized, and the gaseous hydrogen thus
produced will begin to be evolved at the cathode.
The mechanism of this process is called electrolysis. Its end result
is the decomposition of the solvent (water) into hydrogen and oxygen. Electri-
cal energy is required to drive this process.
If the reverse process is carried out, i.e., electrodes are immersed into
a sulfuric acid solution and oxygen is supplied to the anode and hydrogen to
the cathode, water will be formed from the oxygen and hydrogen molecules,
and the process itself will be associated with the generation of electric
current in the external circuit.
- 95 -
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Fig. 55. Diagram of the simplest hydrogen-oxygen fuel cell:
A - oxygen under pressure; B - electrolyte; C - hydrogen
under pressure.
A diagram of such a model of hydrogen-oxygen cell is shown in Fig. 55.
Hydrogen and oxygen are supplied under pressure to porous platinum
electrodes. On passing through the electrode, the oxygen molecules capture
electrons from the surface of the pores in the metal, change into negatively
charged ions, enter the electrolyte, and move to the other electrode. Here
they give up their electrons and combine with hydrogen molecules, forming
water. This reaction, which takes place in the pores of the electrode, is
associated with the evolution of energy, which is expended on the generation
of a flow of electrons, i.e., of an electric current.
The above-described device is called a fuel cell. It operates silently
with an efficiency close to 100%. Its working temperature is 150-200°C. The
electrode material used may be platinum, nickel and other metals, and the
electrolytes may be solutions of sulfuric acid, potassium hydroxide, etc.
The gases used do not have to be hydrogen and oxygen. The characteristics
of modern prospective fuel cells are listed in Table 13.
- 96 -
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Table 13
TyVe of Element
Fuel'
Hydrogen
Hydrazine
•ettenol
Propane
Oxidizer
Oxygen
Air
Oxygen'
Air
Oxygen
Air .'
Oxygen
Air
: 'Specific Character-
istics in 1966, kg/kW
In Long-term
Operation
20—25
25-35
20—35
25—35
50-CO
70—80
80—100
100—120
At. Peak.
Perform-
ance
10-15
13-18
10-12
12—15
30
35-40
Specific
Charac--
teristici
expected
on 1979,
kg/kW •
8—10
10—12
7—9
9—10
30
32—35
Specific
Charac-
teristics
expected
in .1975,
kg/kW
4-5
5-6
4—5
5-6
18—20
20—25
•>
To date, the hydrogen-oxygen fuel cells have been the ones most
thoroughly developed. Their adoption in transportation is hindered mainly
by their high cost due to the use of high purity hydrogen and precious
metals in the electrode catalyst.
Of great interest for the development of tractive fuel cells is the
cracking of hydrocarbon fuels (for example, methanol) and the cracking of
ammonia, which are processes resulting in the formation of hydrogen. The
optimum oxidizer is atmospheric oxygen. In the U.S.A. , England and France,
nonprecious catalysts such as oxides and other compounds of certain metals
are used to accelerate the process.
Another promising trend in the development of fuel cells for transporta-
tion is aimed at perfecting a cell with a liquid fuel, chiefly hydrazine
and methanol.
The direct oxidation of kerosene, gasoline, and diesel fuel is still
in the stage of laboratory testing.
Considering the insufficiently high specific characteristics of modern
chemical energy sources of define interest at the present time is the
combined utilization of low power internal combustion engines and chemical
storage batteries. These energy sources operate under buffer conditions,
- 97 -
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with the storage battery serving as the source of traction and the heat
engine constantly charging it. This combined power plant (CPP), under
development at LANE, permits a sharp reduction in the emission of toxic
components into the atmosphere.
There are also other systems.
Atomic engines. At the present time, nuclear energy is liberated by
the fission of nuclei (in atomic bombs and power plants), by the fusion of
nuclei (in hydrogen bombs) or as a result of the radioactivity of certain
substances.
In the next 20-30 years, the fusion of nuclei will scarcely become a
controlled thermonuclear reaction, and it is premature to discuss the prospects
of automotive atomic engines operating on this principle.
To achieve the reaction of nuclear fission, to start the reaction and
keep it going, a large critical mass is required, and the reactor itself
must have a reliable shield weighing several tons. The use of the nuclear
fission reaction becomes warranted only in the production of power tens
and hundreds of times greater than the amounts required today for generating
the motive power of an automobile.
Table
Type
SUAP 1A
SNAP 7D
SNAP 13
Power, W
125,0
60,0
12,5
Service
life,
months
12
12
4
Radioactive Substance
Used
Cesium 144
Strontium 90
Curium 242
It would be premature at the present time to discuss the prospects for
the use in automobiles of devices operating on the energy evolved by the
radioactivity of certain elements. Thus far, they have been applied only
in thermoelectric semiconductor converters with germanium or silicon cells
having efficiencies of 0.1-1.0%, and also in thermionic converters with
efficiencies of 15-20%. The power of these batteries is very low and as a
rule does not exceed 500 W. As an example, Table 14 lists the main parameters
of SNAP type thermobatteries produced by the American company Martin Marietta.
- 98 -
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Table 15
Converter
Carburetor engine
(degree of compression
e = &5)
Thermoelectric
Converter
Thermionic eon vertejt
•Fuel -cell
§
u-g <
1,3
1200
850
300
1800
1160
—
i—l QJ
gf«H.
B.S
3£
0,57
0,21
0,17
0,08
0,35
0,15
0.0)
Overall
Efficiency
0,30
_
0,04—0,05
0,04—0,05
0,15
0,6—0,7
Specific
Power,
hp/kg
1.0
0.2
0,03
0,03
(0.65)
10,65)
0,18
Note. Thermal efficiency - ratio of converted heat energy to
input energy} overall efficiency - ratio of shaft energy to input
energy. The overall efficiency takes into account all the losses,
and the thermal efficiency, only the cycle losses.
The data given in parentheses are tentative.
The value of the specific power of a thermoelectric converter,
equal to 0.2 hp/kg, corresponds to the specific power of a single
cell, equal to 0.03 hp/kg - the specific power of the entire
assembled converter.
To conclude the chapter, we present comparative Table 15 of mechanical
and nonmechanical energy conversion devices, which permits an evaluation of
the present efficiency of some of the devices described. Table 15 was taken
from materials of official U.S. publications.
Table 16 lists the sanitary norms for the contents of toxic substances
in the atmosphere and Table 17, their concentration indices.
-------
Table 16
Sanitary Norms of Maximum Content of Toxic Substances in Atmospheric Air
s
o
Component
Acrolein
Formaldehyde
Carbon Dioxide
Carbon Monoxide
Sulfur. Dioxide
'Hydrocarbons
Uotal)
Nitrogen Oxide
('total
Soot
Benz(
#.By
Volume
13.10-6
2,9.10-a
"g
sW
*^/
0,13
0,029
Maximum Permissible Con-
centrations 'at Work Static
ng/1
0.7.10-'
1.10-3
*By
Volume
3.10-5
8,15.10-5
tM
*a
-/ m •
/— \
ikn
0,3
0,815
Not specified
520.10-*
19.10-6
5,2
0,19
20.10-3
10.10-*
175. 10-3
38,2. 10-a
17,5
3,82
For Gasoline
100.10-3
N205
6,8.10-"*
1
0,068) 5.10-'
1
7.32.10-5
7,32
Uaximum Permissible Concen-
is trations in Bine Attaoaphene
mg/1
0,7.10-3
i.io-»
*By.
Volume
3.10-8
8,15.10-5
VI
HA
Sg.
»»/s
^\
H,§
0,3
0.815
For mine shafts
9,0
20.10-3
10.10-3
0,5 "
175.10-5
38.2.10-s
5000
17,5
3,82
For Methane
4,8
0,75
7500
In terms of N0>>
-i.io-s
20.10-5
2,0
' Far eoal dust containing no '-free SiO?
5.10-5
—
—
15.10-5
Emission standards 'being established
— 1 — I 10.10-M — | — | 10.10-*
— 1 —
* The content of benz(o)pyrene is usually given iny/m', y being one millionth of a gram.
-------
Table 17
Concentration Indices of Toxic Components
of Exhaust Gases.
Soxib Component
Carbon monoxide
Acrolein
Formaldehyde
Sulfur dioxide
Hydrocarbons (total)
in terns of nexspp
Nitrogen oxides
(in terns of nitrogen
pent oxide)
# by Volume
-mg/1
11,45
22,50
12,30
26,60
35,2
44,1
npja
.pRs
iillibi
1COOO
10000
10000
100CO
10000
100000
1 IK/1
#By
Volume-
0,0873
0,0445
0,0815
0,0376
0,0285
0,0227
paWs
•per.
iillior
873
445
815
376
285
227
1 ppm.C parts
oer million)
*By.
Volume
)
0,0001
0,0001
0,0001
0,0001
O.OCOI
0,0001
ng/1
0,001145
0,00225
0,001230
0,00266
0,00352
0,001-11
- 101 -
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AFTERWORD
Academician 8. S. Stechkin
Hero of Socialist Labor, recipient of the Lenin Prize, and member of the Scientific Council
on the Problem of Protection of the Air Reservoir from Pollution by Noxious Substances,
of the State Committee on Science- and'^Piohnology of the Council of Ministers of the USSR.
The crowding of automobiles in urban areas makes it necessary, in
addition to creating favorable conditions for the flow of traffic with a
minimum loss of time, to provide parking spaces, develop a system of service
and filling stations, and solve the problems of pollution of air by the toxic
substances of exhaust gases and traffic noise in cities and suburbs. These
problems should be solved as part of urban planning problems as well as in
meeting the requirements of urban transportation.
The problem of decreasing the toxic exhausts of automobiles has been
particularly pressing in the1 last few years.
According to published data, in 1962, automobiles in die U.S.A. dis-
charged 90 million tons- of carbon monoxide, 12 million tons of hydrocarbons,
4.5-13,5 million tons of nitrogen oxides and hundreds of thousands of tons
of aldehydes, sulfur compounds, organic acids, soot, and lead compounds intd
the atmosphere.
A survey of European cities for 1960-65 showed that the average carbon
monoxide concentration In Paris was 45.6 mg/m^, in Marseilles 68.98 mg/m^,
in Zurich and Basel, 40 mg/m3. Comparing the above data with the average
maximum permissible concentration of carbon monoxide, 1 mg/m^ of air, one
can see how serious the problem of control of toxic automobile exhausts
really is. In some cities of die Soviet Union, the content of toxic com-
ponents of automobile exhausts in air is lower than in U.S. and European
cities, but it also exceeds the permissible norm.
One of the methods used to reduce the emission of carbon monoxide and
hydrocarbons from an engine has been to lean out the air-gasoline mixture.
Numerous studies have shewa that when the mixture is leaned out to an excess
air coefficient a = 1.05-1.15, the emission of carbon monoxide decreases to
a few tenths of one percent, instead of the 5-10% in power adjustments.
The road leading to the solution of the problem of cleaning up internal
combustion engines appeared to be clear. However, studies carried out in the
last few years at LANE under the direction of Prof. I. L. Varshavskiy showed
that precisely at these excess air coefficients, the formation of nitrogen
oxides and their emission into the atmosphere increases by almost a factor
of 10. Since die maximum permissible concentration of nitrogen oxides in the
atmosphere of cities is ten times less dian that of carbon monoxide, the prob-
lem, .of'reducing^ die total toxic!ty of the exhaust gases of automobile engines
cannot be solved by the above-indicated leaning-out limits.
- 102 -
-------
As pointed out in this book, according to Varshavskiy's recommendations,
the usual engine power adjustments should be made corresponding to the
minimum emissions of nitrogen oxides, and large amounts of the emitted carbon
monoxide and hydrocarbons should be subjected to flame less afterburning in
catalytic neutralize™, or overleaning of the mixture should be achieved by
special methods (laminar distribution of the mixture in the cylinder, intensi-
fied electric ignition, prechamber-flame ignition) down to a limit where the
total specific toxicity will be minimal, and the power decrease will be offset
by supercharging. He also recommends other methods such as water injection.
The future will show which methods will prove the most constructive,
reliable, and economical.
The last few years have seen an emphasis on the problem of replacement
of automobiles with internal combustion piston engines by electric cars with
electrochemical energy sources that facilitate the control of air pollution
and noise.
The technical and economic indices of electric cars depend primarily on
the properties of their electrochemical energy sources - storage batteries or
fuel cells. Today, however, the weight per kilowatt of power (for a five-hour
operation) for lead, iron-nickel and nickel-cadmium storage batteries is
approximately 250 kg/kW, for silver-zinc and for air-zinc storage batteries
being developed,. 35-55 kg/kW, and for fuel cells: operating on oxygen and
hydrogen, 20-25 kg/kV, on air and hydrogen, 30-35 kg/kW, and on methanol and
air, 70-80 kg/kW.
Modern carburetor automobile engines have a weight of 2-3 kg/kW, and
diesels, 3-7 kg/kW. We can see that the main index of a transport engine in
terms of modern electrochemical energy sources is one or two orders of magni-
tude less than that of an internal combustion engine.
In addition, fuel cells have not yet been perfected to the point where
they can be used in Industry.
The above factors combined with other causes will postpone the replacement
of automobiles by electric cars for many years. Thus, research aimed at
decreasing the emission of toxic components by automobiles and internal com-
bustion engines into the atmosphere of cities and industrial centers is
very timely and pressing. Since the cost and weight factors of chemical
sources of energy do not permit the conversion of most automobiles to electric
traction in the next 10-15 years, it is desirable, in addition to studying
ways of decreasing the toxicity of automobile exhausts, to expand the research
being currently conducted under the direction of Prof. I. L. Varshavskiy, aimed
at the creation of a combined power plant (CPP), which I have advocated for
several years now, involving the combined use of a low power internal combus-
tion engine operating under steady conditions and a buffer storage battery.
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When traction electric motors require a greater power than that supplied
by the internal combustion engine, the buffer storage battery operates in
parallel with the internal combustion engine, and when the energy expended by
the heat engines decreases (coasting, parking or stopping at a traffic light),
the storage battery is charged. It is important to note that an internal
combustion engine operating constantly under steady conditions can be special-
ly constructed. Recent progress in high speed engines makes it possible to
construct the motors for the OFF system with a required power of 6-12 kW, ro-
tational speed of the crankshaft of 8000-10,000 rpm at a very low average pis-
ton speed, and with complete utilization of the effects of air vibration at
the intake and exhaust. The high rotational speed of the engine crankshaft
makes it possible to increase the compression ratio without risking the appear-
ance of knocking and, with intensified ignition, to achieve a stable operation
of the engine at a >1.35 under steady conditions, resulting in the absence of
carbon monoxide and minimum amounts of nitrogen oxides. A one-liter capacity
at high rotational speeds will be sufficient despite the high value of the
excess air coefficient a .
In the future, the system with a OFF can also be used when the heat engine
is replaced by a fuel cell.
One of the necessary elements of a OFF is a system controlling the inter-
nal combustion engine, which should be turned on or off depending on the
degree of charge of the buffer storage battery and the power required by the
traction electric motor.
Theoretical and structural studies of power plants for various types of
passenger automobiles carried out at IANE have shown that if one considers a
passenger car weighing 0.6 ton with a driving range of 60 km, the total weight
of the internal combustion engine, generator, buffer battery, traction electric
motor, control system and fuel system with stored fuel will be 78.5 kg, which
is 13.1% of the total weight of the automobile, and in the case of a light
taxicab weighing 2 tons and having a daily range of 250 km, the total weight
of the above units and systems will be 242 kg, i.e., 12,1% of the total weight
of the taxicab.
Comparison of data on an automobile with an internal combustion engine
and an electric car with a OFF shows that the latter vehicle has fully accept-
able characteristics and may be regarded as one of the possible variants for
replacing the automobile in cities.
No books have thus far been published in the USSR on the problem of con-
trol of the toxicity of automobile exhausts and internal combustion engines.
Individual articles in periodicals have appeared only in the last few years,
and in 1966, a collection printed in a small edition was published containing
reports of Soviet scientists at a Moscow symposium (with the participation of
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experts from member countries by the Council of Mutual Assistance) of the
Scientific Council on the. Problem of "Protection of the Air Reservoir from
Pollution with Noxious Substances" of the State Committee on Science and
Technology of the Council of Ministers of the USSR. For a major nationwide
social problem such as the protection of the air reservoir this is obviously
not enough. I, therefore, give herewith my unqualified support to the publi-
cation by the "Transport" Press of the book "How to Neutralize Automobile
Exhaust Gases" by Doctor of Technical Sciences Prof. I. L. Varshavskiy,
Honored Scientist and Engineer of the RSFSR, and Candidate of Technical
Sciences R. V. Malov.
LITERATURE CITED
BHTKOJIOB H. 3., H H K H T it H B. C. nponerpHBaHHe Kapbcpou.
M., rocropTexti3AaT, 1963.
BapuiaucKHft H. Jl., SoJiorapeBCKHii JI. C., HrHa-
TOBHq H. B. ToKCHMHOCTfa H TOKCHieCKaH XapaKTCpHCTHKa 3BTOMO-
fiHJm. C6. «ToKCH, 1967, ffe 3.
. BapuiascKHft H. JI., M a . 1967, K° 6.
BapmascKHH H. Jl., Ma^HHOBCKiift K. H., 3o no ta-
pe BCKH ft Jl. C. O B03.fl.yxe goAbUIHX ropOAOD. tCtaHAapTH H K3He-
CTBO», 1966, M 7.
BapuiaBCKHH H. JI., SoJiorapeBCKuA JI. 'C, 4>peH-
K6Ab A. H. O BblflCfleHHK OKIICJ1OB 330T3 B ABIfraTeiflX C BHCUlltHM
cneceo6pa30BaHueM, HcnoJibayiomux raaosoe Tonfliiso. «ra3osaa npo-
BapmaacKHfi H. JI. H Ap. IIpHMeiieHHe
pecueMTHoro Meto.ua RJIX onpeAeJieniiff coAepxaniiR KaHueporeHHoro
yrfleBOAOpOAa 3,4-6eH3nHpeHa B OTpa6oTaBiunx raaax AfiseJihiiux ABII-
rareneft. c)Kyp»taji npHKa^AHoft cneKTpocKon«H», T. II, 1965.-
BapuiascKHft H. Jl. H • AP- Kata^HtHiecKan omictKa otpa-
6oTaBiuHx raaoB KapGioparopHbix ABiirare^efi Ha a.nio.MO-n^aTifHOBWx
9jieMeiiTax, BwnoJiHCHHbix B ^opue uiapiiKOB. HaBecTim AH ApM. CCP,
cepiia TCXH. uayK, T. 18, 1965, KB 6.
B a p ui a B c k H ft H. JI. KoiicrpyKTOpu npeAflararor sAopoube.
«3AOpOBbe», 1964, M? 8.
BapiuaocKiifi H. JI. MCJIOBCK u cro ropoA. «3AOpoBbe», I960,
'
JI. B... CaAOBHHKOB n.. 51., OpaiiK-Ka-
M e H c n K H ft. OKii(vienne asora npn ropciiun. HSA-BO AH CCCP,
M.— 'Jl,. 1947.
JKaBOpoiiKon H. M. riiApaBJimiccKiie OCHOBU cKpy66ep»oro
npouecca H TenflonepeAa'ia B cKpy66epax. HSA-BO
-------
M a n o B P. B,, H r u a T o D n KHBaHne OTpa6oraB-
IIIHX raaoB TpaKiopHoro AHae^n flT-20. cTpaKTOpu H ceAbx03MauiHHU».
1965, W« 2.
Ma^oa P. B. H MajiaCoB B. F. K Bonpocy CHiixceHHX TOK-
CHIHOCTII OTpaCoraBiiiiix raaos tpancnopTHWx cpeAcrs ropHOAofi
mefi upoMbiuieHHocTH. HsBecTHsr AH ApM. CCP, cepHH TCXH.
T. 1-7, 1964, tfi 2.
M a a o B P. B. H AP- Paapa6oTKa H HcnurauHe
OTpafiotaBuiHX rasos AHS&nb-aJieKTpimecKHX caMOXOAnux saroHOB. «Fop-
Hbifi xypua;!*, 1965, X: 12.
COKO^HK A. C. KHuertmecKaH HHTepnperamiH M-npouecca.
C6. cCropaHHe H CMeceo6pa30B3Hiie B AH3e/mx». HSA-BO AH CCCP,
1960.
4»HJiaTOB C. C., Kjoques K. B., BaciuibeB M. B. Hau-
CKaune pauHOHa^bHHX HCTOAOB 6opb6w c BHXJIOIIHHMH raaanii iia
Kapbepnoit aBTorpaHcnopre. cFopHufi >KypHa^>, 1960, Ns 5.
MyaaKOB E. A. HaCpaHHbie Tpyftu. T. 1, M., 1961.
Ill a 6 a A JI. M., A H K y H FI. n. 3arpfl3HeuHe atMoccJiepiioro
eosAyxa KanueporeiiHUM semecrBOM 3,4-6eH3niipeKOM. M., «McArii3»,
1959.
- 106 -
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DETERMINATION OF THE COMPOSITION OF EXHAUST GASES FOR CARBURETOR ENGINES
UNDER DIFFERENT OPERATING CONDITIONS
Robert Eberan von Eberhorst
From Scientific Reeearch Institute of Information for the Automobile Industry
(NIINAVTOPRQM). Reference Department, Moscow, p. 3-23, (1966).
In connection with the increased use of internal combustion engines in
industry, engineers steadily encounter problems whose solutions become more
complex with each passing year. The consumption and pollution of air are a
phenomenon accompanying the combustion process. The level of air pollution
because of automobile exhaust gases already has become the chief problem of
the day, since a heavy air pollution has a deleterious effect on man, animals
and the plant world*
Given below is a report on some basic problems of exhaust gases (as
sources of air pollution).
The world consumption of energy [1] has been steadily rising in the last
two decades (along a nearly straight line, Fig. 1). At the present time,
it is equivalent to 4,5 billion tons in standard coal units (SCU) per year
(7000 kcal/kg). The energy obtained from crude oil and natural gas has long
surpassed the energy obtained from coal.
Steeper curves illustrate the growth in the volume of motor transport. The
Increase in automobiles In the German Federal Republic (12,5 million automobiles;
yearly Increase, 6,5%) .considerably exceeds the increase in the U, S, A. (93
million automobiles; Increase 3,7%), since Europe is still at an early stage
of motorization* Recently, an article written by a scientist has appeared
in the world press stating that in the next century, automobiles will exhaust
the supply of air on our planet. It is probable that 100 years hence, there
will again be held a congress of FISITA at which the engineers will be dealing
with urgent problems connected with automobiles that will not be running on
gasoline. According to the author's calculations, the supply of air will
suffice for another 117,000 years (for a combustion of 4.5 billion tons of
SCU per year). Considering the increase in automobiles, one can determine
to what extent the undesirable emission products of internal combustion
engines should be reduced in order to preserve the present level of air
purity. For example, in the course of the next decade, the noxious impuri-
ties of automobile exhaust gases in the German Federal Republic (GFR) will
have to be cut by 40% while preserving the current level of production.
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Year
Fig. 1. Growth of the world consumption of energy
and nunter of autoaobilesj right - required reduction
of emission products A E to keep the air pollution
level unchanged in the course of 10 years:
1 - world consuaption of energy; 2 - number of auto-
mobiles in the OSAt 3 - number of automobiles in the
GFR:
+A Ktz - voltme of motor transport
+^ EV - world consumption of energy
Effect of the Operation "of ar Mo tor
on the Emission of 00, CH, and NO with Exhaust Gases
The most harmful component in the exhaust gases of. a carburetor engine
is carbon monoxide CO, since it is very toxic. CO is the product of combustion
of carbon, which is contained in gasoline and in atmospheric oxygen, and '
theoretically, in the presence of excess air X>1, carbon monoxide should be
neutralized (Fig. 2).
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ZCH NO
200
$6 '0,7 0,8 0.9 10 IJ U 1.3 »,«
Excess coefficient X
total admission 0.93 atm. _______ 0,78 atm.
Fig. 2. Exhaust gas components CO, CH, NO for a one-
cylinder four-stroke carburetor engine; number of revolu-
tions n = 1800 rpm.
Instead of CO, harmless carbon dioxide C02 is formed. The C02 remains
harmless until it completely displaces the oxygen of air. Unfortunately, an
engine operating on gasoline with a 10-20% deficiency of air develops the
maximum average pressure as a result of a high combustion rate, with the for-
mation of 3.5-7.0% of CO (by volume). The CO content of the exhaust gas,
which is almost independent of the design of the engine, fuel or type of
carburetion, depends on the composition of the mixture and also on the degree
of admission. The CO Content in the exhaust gases of the engine is 1000 times
greater than in air with a CO content that man can still tolerate for 8 hr.
The so-called MAC (maximum concentration of noxious gases at a work station)
is 0.01% a 100 cn»3/m3 CO. Thus it is necessary to point out a steady and
heavy pollution of air with the exhaust gases. The maximum content of CO,
30 cm3/m3f has been recorded in the streets of Paris and London.
This situation now exists in many places, but we should not lose heart,
because:
an increase in the maximum quantity of CO will not take place in the
future, since highways are designed for & given number of automobiles;
according to medical data [5], chronic poisoning with carbon monoxide
is not dangerous, since when fresh air is supplied, the headache goes away
and the sluggishness disappears, both of these symptoms being manifestations
of light poisoning with this gas.
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The problem of air hygiene in Europe has first priority. Of major interest
is the driver himself, who is subjected to the action of CO more than anyone
[6], The carbon monoxide content of the driver's blood hemoglobin may rise to
4.5% CO-Hb; whereas in the blood hemoglobin of a traffic controller after 5
hr of work, the carbon monoxide content is only 1.6% CO-Hb (nonsmoking traffic
controller). In the case of a smoking traffic controller, however, at the end
of the working day, the CO content of the hemoglobin is 3.65% CO-Hb. The per-
missible carbon content of hemoglobin is 15% CO-Hb.
A major importance is attributed to unburned hydrocarbons CH in the exhaust
gases in Los Angeles, California, after it was demonstrated that as a result
of photochemical reactions in sunlight under certain meteorological conditions,
hydrocarbons promote the formation of smog. The unburned hydrocarbons are
given in ppm (parts per million), i. e., in cm^/m^, and are referred to hexane
C6H14. Their content in the exhaust gas is explained by effects of cooling
of the combustion chamber walls. The minimum CH values are reached at
X = 1.2-1.3; a sharp increase in a lean mixture with X «= 1.3 is explained by
a slow combustion and missing of the engine. CH emissions depend on the form
of the combustion chamber, with a definite role being played by the ratio of
surface to volume.
At this point one must also mention the fact that a modern automobile
carburetor engine with an excess air X = 1.05-1.15 is characterized by a
minimum fuel consumption.
Less closely studied are nitrogen oxides NxOy, which as a result of
oxidation of atmospheric nitrogen are formed in the engine at a high tempera-
ture. The maximum concentrations are observed at X**1.0.
Nitric oxide NO is very toxic; its MAC is only 25 cm^/m^, but in large
cities of the GFR, values no higher than 0.4 cnP/m^ have been reported [7],
which can hardly be accounted for solely in terms of automobile exhaust. In
Los Angeles, a maximum of 0.3 carfm* is already being used in the calculations.
The nitric oxide content of exhaust gases has not yet been determined.
Results of bench tests were used to compile graphs of average pressure
which clearly show lines of constant value of C0% - CH cm3/m^ (Fig. 3).
All the measured quantities are valid only for one cylinder of multi-
cylinder engines,. The crosshatched portion of the graph shows that the value
of the exhaust established in California has increased. As a rule, different
cylinders have different values; so that the percentage value of the total
emission of combustion products . is considered to be the average. The latter
is determined by considering the type of carburetion [8], ripple in the in-
take 'manifold [9] and type of mixture in the intake system* In normal opera-
tion, the composition of the mixture supplied to the individual cylinders is
entirely different than during acceleration or braking, since, as a result of
a partial condensation in the intake manifold, this always leads to the
formation of extra fuel. This applies primarily to carburetor engines.
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CH (parts per million)
kra/kr
WHO
rpm of engine
Fig. 3. Graphs of CH and CO for the fourth cylinder of a four-cylinder four-stroke carburetor
engine.
Even the same automobiles under the same operating conditions show
different contents of CO In the exhaust gases. This was revealed by an
analysis of the composition of the exhaust gases of 80 medium cars [10].
The analysis showed the values of. CO to be distributed in the range of
1-127. (Fig. 4).
The composition of the exhaust gases of individual automobile engines
varies with the design of the engine, its aize, adjustment, and maintenance.
In order to approach the problem of the quantity of noxious components of
exhaust gases, it Is necessary to proceed from the "pattern of movement"
characteristic of the traffic flow. Such a "pattern of movement" is current-
ly being studied on passenger cars in large German cities 17J.
Amount of Exhaust Gases Associated with Speed Shifting
The amount of exhaust gases associated with simple speed shifting for
a given automobile Is clearly illustrated in the graph (Fig. 5). The fuel
consumption in 1/100 km at an average traveling speed Is also shown.
The following relationship exists between the fuel consumption B, air
- Ill -
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•>/)
10
(
-
^
"I
'
K:
<
—
k
\
N
^
s
"».
•-
*-,
%H
20
W
7
1
i 2 it 6 g 10 izy.co y 1
Idline t_L
s
\
4
k-
V,
s
1
•G
d
W
10
f 4» 6 8 W '/.CO
Acceleration from 40 km/hr
6 8 %CO
Braking from 60 km/hr.
Fig. 4. Curves of CO distribution in exhaust gases of
80 cars with a displacement of 1.2-1.5 1 under different
operating conditions.
Ate?
Vn'SO
- length of path
traveled
Acceleration = braking
B = 1.0 m/sec2
20 25 30 35
Average speed of automobile V, km/kr
5. Fuel conBunption and exhaust gases during shifting of speeds
0-50-0-50-0 km/hr.
- 112 -
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consumption L and the quantity of exhaust gas A (dry) at * 1.0:
9339 x B (1/hr) . L x (1/hr); 0.94 x L = (1/hr) = A (1/hr)/
Neither the percent volume nor the amount of CO and CH emitted per unit
time constitutes an index of air pollution. The ratio of the amount of exhaust
gas to the path traveled in cnr/m or I/km is a unit of measurement of air
pollution. This dimension (cm3/m or I/km) is'the average amount of gas dis-
charged by the automobile into the atmosphere. It is also used for the exhaust
components CO, CH, etc. Changes in the velocity of the automobile as a
function of time are:
engine idling when the automobile is stationary (time TI);
acceleration in m/sec2 (T£);
uniform speed of 50 km/hr (13);
deceleration Bv • B^ m/sec2 (T£);
time of run T1 « 2X2+13.
The variable Ti/T1 (idling: time of run), TS/T! (50 km/hr; time of run),
and also the traveled path S are the parameters of the curves. The amount of
exhaust gases, i. e., the air pollution, is minimum at a constant speed of
50 km/hr (Tl/T1 = 0; T3/T1 = 1.0 (on the graph, 3.7 cm2). Transport operating
on liquid fuel at a maximum average speed causes least air pollution. The
construction of roads and traffic control may aid considerably in obtaining
clean air. The duration of idling (Ti/T^ » 0) and also frequent stops con-
siderably increase the amount of exhaust gases (on the graph, 11.6 cm2).
California Tests
The test cycle in California consists of seven stages, each of which was
carried out with different loads on the engine and different numbers of revo-
lutions per minute (curves 0-13, Fig. 6).
The percent content of CO and CH in the exhaust gases was recorded at
each stage. Calculation of the average content of CO and CH was carried out
in units of weight, which take into account the duration of the stage and
magnitude of the flows at each stage.
The permissible content of noxious components in accordance with recent
determinations obtained from tests carried out in California amounts to the
following: for engines with a displacement of 820-1640 cm3, 2.37. CO and
410 cm3/m3 CH; for engines with a displacement Of 1640-2290 cm3, 2.07. CO and
350 cm3/m3 CH; for engines from 2290 cm3 and up, 1.5% CO and 275 cm3/m3 CH.
As a result of gradation of the percent values, the quantity of exhaust
gases of engines with different displacements was taken into account.
According to standards VDJ2282, the maximum amount of CO for 4.57» idling
- 113 -
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at a constant speed of 33-757° of the maximum speed, 2-47», can no longer serve
as the standard for air pollution. The total amount of CO can be determined
if the fuel consumption and volume content of CO are known.
Engine rpm
Fig. 6. Graph of operation of engine tested in California.
Thus, the maximum value is W = 0.783 (C0%) N. The individual stages of
variable motion in the California tests are related to the average fuel con-
sumption, in this case 0.2-2.0 cm^/sec. The areas shown on the time diagram
(Fig. 7) represent the fuel consumed and at the same time the amount of exhaust
gases at the various stages. At each testing stage, the percent content of
CO and CH is different. If one multiplies the amount of exhaust gas by the
volume percent of CO and CH, one obtains the total amount of emitted gases
in the form of the areas shown in Fig. 7.
From the above diagram it is evident that the largest amount corresponds
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to acceleration areas 2 and 6, the maximum discharge of unburned hydrocarbons
being observed during the braking period 7. The content of noxious components
during idling is considered insignificant.
Fig. 7. Total amount of exhaust gases recorded during tests in
California: 1 - idling; 2 - acceleration 0-48 km/hr; 3 - constant
speed of 48 ka/hr; A - braking, 48-24 km/hr; 5 - constant speed
oH>4 km/hrt 6 - acceleration, 24-80 Whr; 7 - braking, 80-0
km/hr. B - amount of fuel; A - exhaust gases. For the exhaust
gas with N - consumption standard (1/100 km) F (en2) = 0.783 N.
Content of CO and CH in the Engine Exhaust During Idling
A 5° opening of the butterfly valve has almost no effect on the idling
speed, and a slight turn of the mixture control screw substantially increases
the CO content of the exhaust gases (Fig. 8).
When the opening of the butterfly valve is 5°, 1/4 of a turn of the
mixture control screw is enough to increase the percent content of CO from
S.5 to 6.3% in the exhaust gases. As is evident from the graph during idling
of the engine, the lean mixture contains the lowest percentage of CO.
At the maximum idling speed, the CO content of the exhaust gases is
lowest. Such a state is best for the engine s operation.
Th* loint^stock company 0AMTC, which deals with problems of pollution of
air w£h gases, has printed a graph (Fig. 9) showing that the adjustment of
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the operation of an idling engine can'be improved. By adjusting the carbu-
retor on 4831 automobiles of 6 brands, CO was successfully reduced in the
exhaust gases by approximately 3%. Comparison with general data leads to
the conclusion that the CO content was reduced by 1/3.
Adjustment of idling also affects the partial load of the engine and the
traction when the butterfly valve is closed. This was established as a re-
sult of seven tests conducted in California (Fig. 10). The idling operation
of the engine was adjusted so that the CO content of the exhaust gases was
1.2-7.2%.
\|) - angle of turn of mixture control screw
—" of turn of butterfly valve.
KWlNm5/hr **s
-------
I . I
(Bef ore (adjustment
After adjustment
1 >1,5
%co
Fig. 9. Graph of CO content of exhaust gases during.,idling oper^
ation of engine, plotted by the joint-stock company OAMTC (Austria),
taking into account the tests conducted in September 1965 on 4831
automobiles.
CO Contt&tt of Exhaust Gases Discharged into the Atmosphere
In the presence of excess air, practically'no CO is detected in the
exhaust gases of a carburetor engine . However, as the excess air increases,
the average pressure decreases. This dependence is illustrated in the diagram
(Fig. 11) in the form of areas.
The shapes of the curves of the working cycles, which alternate during
stationary operation of the engine, are always different. The torque of
numerous working cycles is measured on an engine test stand, no vibrations
being recorded. Statistical treatment of a series of successive diagram p-V
areas shows the recurrence period to be correct. The recurrent working
cycles are never similar. **.,_** * T.J it
The maximum and minimum working areas are shown in the diagram of Fig. 12.
In the presence of the maximum excess of air (A = 1.51), despite advanced
ignition, there la a perceptible retarded combustion.
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Results of California tests
Fig. 10. Diagram of average CO content for
different adjustments of idling engine and re-
sults of California tests conducted on an auto-
nobile with a 1.2 1 displacement.
Pig. 11. Fluctuations of the indicator diagram
at different A in stationary operation; VZ - ignition advance.
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There are two causes of the fluctuation of the working areas:
irregularity in the supply of fuel to the combustion chamber during
each working cycle;
the combustion process depends on the homogeneity of the combustible
mixture.
Recording of the flame front with ion probes 14] showed that the local
combustion rate varies considerably from one cycle to the next. The CO con^
tent of the exhaust gases also varies from One cycle to the next, and hence,
its sum deviates from the theoretical value, which at X = 1 should be equal
to zero. Actually, however, a 1 to 2% CO content was recorded for this
number X » 1. This is explained by the frequency of the dependence and
scatter of the X values of the individual working cycles (which is not
measured).
i,07
Excess coefficient = 0.91.
Fig. 12. Maxiatm fluctuations of the indicator diagram based
on Fig. 11.
The recurrence frequency and height determine the average value of CO,
since there are no "negative" values. In the presence'of multicylinder
engines with an inadequate distribution of the mixture, there are even more
deviations from theory. The crosshatched surfaces of Fig. 13 should be re-
garded as the efficiencies of the engine relative to the production of CO.
The maximum power of a carburetor engine is reached in the presence of
a 15% deficiency of air. The better one can differentiate between the
scattering of the working cycles and the deviations of individual cylinders,
the closer the optimum power comes to the proportional composition of the
mixture corresponding to the excess air coefficient X = 1. This is and
continues to be the purpose of complete combustion.
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0,7
0.9
II
Air coefficient, X
Fig. 15. CO content of exhaust gases of one-cylinder (left) and
nnlticylinder (right) four-stroke carburetor engine:
1 - CO (theoretical); 2 - carburetor without correction for air
consumption? 3 - carburetor with correction for air consumption;
A - injection into intake aanifoldj 5 - vaporizer.
Among the constructive possibilities of reducing the scattering of the
working cycles, one must particularly emphasize the adjustment of fuel in-
jection. The known advantage of adjusting the injection relative to the
power and consumption before the carburetor amounts, on the one hand, to a
slight throttling of the engine, and on the other hand, to an exact propor-
tioning of the fuel mixture necessary for each cycle. The condensation of
fuel in the intake pipe does not occur thanks to an adjustment of the Injec-
tion. The amount of vapors which increases the CO content of exhaust gases
becomes less if the nozzle is located near the valves. A static determina-
tion of the Indicated mean pressure Pmi at a distance of 90 mm gave a
considerably narrower band of scattering of the points than at a distance
of 360 mm, particularly In the presence of the maximum excess of air (Fig. 14),
The next measure that can be used to reduce the scattering of the
working cycles and hence the content of unburned products In the exhaust
gases Is the turbulence In the combustion chamber. The turbulence can be
caused by the rotating generator In the intake pipe. More effective should
be the counterturbulence, which arises during compression at a minimum
volume of the combustion chamber.
Even a primitive rotating generator In the intake pipe can be used to
reduce the scattering of maximum pressure for any proportional composition
of the mixture.
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Excess coefficient X
Fig. 14. Band of scattering of indicated mean
pressure for nozzle located at 90 and 360 mm from t
the intake valve as a function of the excess air
coefficient Xs
1 - injection at a distance of 90 an from the
intake valve;
2 - injection at a distance of 560 mm from the
: intake valve.
mean pressure
If the coefficient of change V .preflflUre BcaLLering x 100% pertains to
the thermal increase of pressure (maximum pressure minus the pressure at the
end of the compression stroke), the difference is sufficiently obvious
(Fig. 15).
The change of charge in the automobile engine is very difficult to
control during changes of power, but this would undoubtedly lead to a re-
duction in the emission of noxious exhaust gases.
The problem facing engine specialists is to learn how to control the
processes of carburetion and combustion of noxious Cities polluting the
a^spheric air and to use an afterburning system which would neutralize the
exhaust gases.
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— Without rotatibn
"— With rotation
t -i ^Oite
• , ' — • —4"*
Excess coefficient X
Fig. 15. Change V of maximum pressure
of • compression as a function of X).
= pressure
Conclusion
The growing demand for energy in transportation calls for progress in
the control of the purity of atmospheric air. The paper discusses the
dependence between the noxious products of exhaust gases of automobile
carburetor engines and the conditions of operation of the engines.
The maximum content of exhaust gases depends on the size of the engine
and fuel consumption. An irregular combustion process in the individual
cylinders and an inadequate distribution of the mixture in multicylinder
engines also affect the emission products.
- 122 -
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LITERATURE CITED
I. Erdol - Fcrderung, Verarbeitu'ig, Verbranch, £ae - Haga-
»in 4/1958.
2. Tataactien and Zahlen, Jahrbucli dea VDi, 1965.
3. Automcbile Facta and Figures, ',965, /JU.
4. Blue M. Xonnenmann 1VE. fH «fitn, 1965 ( »ird in Heft 9
'TZ/J96S ver6ffentl:.cht ) .
5* Hogger. D.t Li'fthygiene, Neue Zuricher Zeitunt TeehniV,
20- Januar, 1966.
6. Chovin t.l Bcrichte aua demLaboratorium Municipal Parie,
November, 1964.
7. Luther H. Lohn»r. F.: Hoglichkeiten einer Bntgiftung der
Abgase vou Ottomotoren, Brdol und Kohle, Dezember,1965.
8. Dies. f. Linzar 1VK 1963 (IT! Wien ).
9. Dies. VT. Etrandatatter 1VK 1965 ( TH Wien ) ,
tO. Bias. P.'Reaele 1VK 1964, DKF 178 ( TH Wian ).
- 123 -
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46 THE SUSCEPTIBILITY OR RESISTANCE TO GAS
AND SMOKE OF VARIOUS ARBOREAL SPECIES
GROWN UNDER DIVERSE ENVIRONMENTAL
CONDITIONS IN A NUMBER OF INDUSTRIAL RE-
GIONS OF THE SOVIET UNION-A Survey of USSR
: Air Pollution Literature
47 METEOROLOGICAL AND CHEMICAL ASPECTS
OF AIR POLLUTION; PROPAGATION AND DIS-
PERSAL OF AIR POLLUTANTS IN A NUMBER OF
AREAS IN THE SOVIET UNION-A Survey of USSR
Air Pollution Literature
48 THE AGRICULTURAL REGIONS OF CHINA
49 EFFECTS OF METEOROLOGICAL CONDITIONS
AND RELIEF ON AIR POLLUTION; AIR CON-
TAMINANTS - THEIR CONCENTRATION,
TRANSPORT, AND DISPERSAL-A Survey of USSR
Air Pollution Literature
51. MEASUREMENTS OF DISPERSAL AND
CONCENTRATION. IDENTIFICATION. AND
SANITARY EVALUATION OF VARIOUS AIR
POLLUTANTS. WITH SPECIAL REFERENCE TO
THE ENVIRONS OF ELECTRIC POWER PLANTS
AND FERROUS METALLURGICAL PLANTS
-A Survey of USSR Air Pollution Literature
62 A COMPILATION OF TECHNICAL REPORTS ON
THE BIOLOGICAL EFFECTS AND THE PUBLIC
HEALTH ASPECTS OF ATMOSPHERIC
POLLUTANTS - A Survey of USSR Air Pollution
Literature
S3 GAS RESISTANCE OF PLANTS WITH SPECIAL
REFERENCE TO PLANT BIOCHEMISTRY AND TO
THE EFFECTS OF MINERAL NUTRITION - A
Survey of USSR Air Polution Literature
50. AIR POLLUTION IN RELATION TO CERTAIN
ATMOSPHERIC AND METOROLOGICAL
CONDITIONS AND SOME OF THE METHODS
EMPLOYED IN THE SURVEY AND ANALYSIS
OF AIR POLLUTANTS-A Survey of USSR Air
Pollution Literature
Reprinh from various periodicals.
A INTERNATIONAL COOPERATION IN CROP IMPROVEMENT
THROUGH THE UTILIZATION OF THE CONCEPT OF
AGROCLIMATIC ANALOGUES
(The Use of Phenology, Meteorology and Geographical
Latitude for the Purposes of Plant Introduction and the Ex-
change of Improved Plant Varieties Between Various
Countries.)
B SOME PRELIMINARY OBSERVATIONS OF PHENOLOGICAL
DATA AS A TOOL IN THE STUDY OF PHOTOPERIODIC
AND THERMAL REQUIREMENTS OF VARIOUS PLANT
MATERIAL
*C AGRO-CLIMATOLOGY AND CROP ECOLOGY OF THE
UKRAINE AND CLIMATIC ANALOGUES IN NORTH
AMERICA
D AGRO-CLIMATOIOGY AND CROP ECOLOGY OF PALES-
TINE ANp TRANSJORDAN AND CLIMATIC ANA-
LOGUES IN THE UNITED STATES
c .USSR-Some Physical and Agricultural Characteristic! of the
Drought Area and Its Climatic Analogues in the United States
F THE ROLE OF BIOCLIMATOLOGY IN AGRICULTURE WITH
SPECIAL REFERENCE TO THE USE Of THERMAL AND
PHOTO-THERMAL REQUIREMENTS OF PURE-LINE VARI-
ETIES OF PLANTS AS A BIOLOGICAL INDICATOR IN
ASCERTAINING CLIMATIC ANALOGUES (HOMO-
CLIMES)
*Outof Print.
Requests fbi studies should be addressed t» the
American Institute of Crap Ecology, 809 Dole
Drive, Silver Spring, Maryland 20910.
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