EPA/AA/CTAB-89-01
Technical Report
Resistively Heated Methanoi Dissociator for
Engine Cold Start Assist -
Inter im Report I I
by
Gregory K. Piotrowski
February 1989
NOTICE
Technical Reports do not necessarily represent final EPA
decisions or positions. They are intended to present technical
analysis of issues using data which are currently available.
The purpose in the release of such reports is to facilitate the
exchange of technical information and to inform the public of
technical developments which may form the basis for a final EPA
decision, position or regulatory action.
U. S. Environmental Protection Agency
Office of Air and Radiation
Office of Mobile Sources
Emission Control Technology Division
Control Technology and Applications Branch
2565 Plymouth Road
Ann Arbor, Michigan 48105
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\ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
1° ANN ARBOR. MICHIGAN 48105
OFFICE OF
AIR AND RADIATION
MEMORANDUM
SUBJECT: Exemption From Peer and Administrative Review
FROM: Karl H. Hellman, Chief
Control Technology and Applications Branch
TO: Charles L. Gray, Jr., Director
Emission Control Technology Division
The attached report entitled, "Resistively Heated Methanol
Dissociator for Engine Cold Start Assist - Interim Report II,"
(EPA/AA/CTAB/89-01) describes the evaluation of a methanol
dissociation catalyst that provides a cold start assist for a
light-duty methanol engine. Methanol was boiled in a
steam-heated vessel, superheated and passed to a dissociator
which made use of resistively heated porous silicon carbide
technology. The catalyst used for the methanol dissociation
reaction was a noble metal/rare earth formulation developed by
Nissan Motor Corporation.
Since this report is concerned only with the presentation
of data and its analysis and does not involve matters of policy
or regulations, your concurrence is requested to waive
administrative review according to the policy outlined in your
directive of April 22, 1982.
Concurrence
. Xx>^ ~w
• /_--^_ '
Charles L. Gra'y,Jr/. ,/Dir., ECTD
/ r
Nonconcur rence: Date
Charles L. Gray, Jr., Dir., ECTD
cc: E. Burger, ECTD
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Table of Contents
Page
Number
I . Summary 1
II. Introduction 2
III. Program Design 3
IV. Dissociator Operation 3
V. Supporting Equipment 4
VI. Discussion 5
A. Bench Test Experiments 5
B. Cold Start Experiments 8
C. Examination Of Substrate Following Testing . 10
VII. Test Highlights 11
VII I.Acknowledgments 12
IX. References 13
APPENDIX A - Dissociator Element Specifications .... A-1
APPENDIX B - Hydrogen Content Determination B-1
APPENDIX C - Test Engine Specifications C-1
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I. Summary
A catalyst specifically formulated for the dissociation of
methanof to hydrogen (H>) and carbon monoxide (CO) was
evaluated for the application of a cold start assist for a
light-duty methanol-fueled engine. The dissociated methanol
generating system consisted of a steam-heated methanol boiler,
a gas superheater, and a catalyzed dissociation element. The
dissociation element substrate was resistively heated and
constructed primarily from fibrous silicon carbide.
The objective of this experimentation was to determine the
ability of the catalyst to facilitate the dissociation of
methanol, and to start and idle a 4-cylinder engine on the
product gas from the dissociator.
Hz/CO product gas yield varied between 13 and 15 percent
for a feed flowrate of 2500 grams of methanol per hour.
Dissociator yield was not a function of superheater feed gas
temperature, for feed gas temperatures into the dissociator
between 400° and 700°F. Power to the dissociator was kept
constant at 345 watts during this testing.
H;, CO, non-dissociated methanol, and possibly other
reactor products from the dissociator were piped to the exhaust
gas recirculat ion port of the test engine. This product gas
mixture served as the fuel supply during the engine start
experiments; the stock methanol injectors on the test engine
were disabled prior to this testing.
At an engine temperature of 73°F the product gas mixture
easily started and idled the test engine. The combination of
hot methanol vapor and H2/CO may be too rich to enable
extended idle, however; flowrates between 1800-2500 grams per
hour of feed methanol are difficult to control with the test
apparatus.
It is difficult to quantify emission control benefits from
the use of dissociated methanol compared to M100 liquid fuel
using the dissociation system described in this report. Only
13 to 15 percent of the feed flowrate of 2500 grams of methanol
per hour was dissociated to H,, and CO. Any emissions control
benefit may be minimized by the presence of large amounts of
unconverted liquid methanol in the H^/CO fuel stream.
Additional testing should be conducted with a fuel mixture much
richer in dissociated product than M100 in order to more
properly define the difference in emission levels between the
two fuels at cold start.
No coking was observed on the walls of the ceramic
substrate following this evaluation. Traces of coke were found
at the interface between the silicon carbide substrate,
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stainless steel wool gaskets, and the stainless steel
electrical contacts. Hot spots caused by areas of high current
density along this interface may have contributed to this
localized coking.
I I. Introduct ion
Light-duty M100 neat methanoI-fueled engines are difficult
to start and run in cold weather because of the high boiling
point of methanoI, methanol's high heat of vaporization (5.5
percent of the heat of combustion compared to less than 1
percent for gasoline), and the increased fuel flow needed for
methanol (about double that of gasoline). Gasoline-fueled
engines start with less difficulty under the same conditions
partly because of the easily ignitable light ends of this fuel
such as butanes, which are vaporized at relatively low
temperatures.
Some state-of-the-art methanol engines require the
addition of gasoline to the fuel to improve their
startabiIity.[1] Other methanol engines utilize separate cold
start systems relying on gasoline or propane for cold start
assist.[2,3] Finally, some researchers have suggested that
stratified-charge combustion will produce reliable cold starts
of a neat methanol-fueled engine at relatively low ambient
condi t ions.[4]
Methanol may be catalytically decomposed to hydrogen and
carbon monoxide gases. Hydrogens' higher flame speed and lower
boiling point may make it an ideal cold start fuel.
Methanol dissociators using resistively heated ceramic and
metal technology for substrates have been evaluated by EPA for
their use in assisting the cold start of methanol-fueled
engines.[5,6,7] The noble metal catalysts employed in these
efforts were platinum and a platinum/palladium mixture. These
catalysts, however, did not provide substantial yields of H2
and CO at lower converter gas temperatures.
A significant problem noted during these earlier
evaluations was the formation of soot in the superheater and
dissociator sections.[6] Coke formation appeared to positively
correlate with operating temperature in the superheater and
dissociator. Temperatures in excess of 900°F invariably led to
sooting of the superheater.
Other researchers working with methanol dissociation have
noted this coking. [8,9] One solution to this problem is the
use of a catalyst that promotes the dissociation reaction at
lower temperatures (less than or equal to 570°F).
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Representatives of Nissan Motor Company, Ltd., presented a
summary of their experience with the "Methanol Reformed Gas
Engine" to EPA on March 13, 1987. [10] One part of this
briefing concerned the results of screening candidate methanol
dissociation catalysts. Some of these catalyst formulations
and their application processes have been patented.[11,12,13]
The catalysts referred to above utilize active components
from the noble metal, rare earth and titanium families applied
to granular or monolithic alumina substrates. A portion of the
March 13, 1987 briefing to EPA concerned a confidential
presentation of catalyst activity as a function of bed
temperature for specific formulations of the catalyst materials
above. This data indicated that several Nissan formulations
could provide substantial dissociative activity at reactor
temperatures below 600°F.
EPA sought permission from Nissan to use a specific
dissociation catalyst formula [14] on a silicon carbide
substrate similar to those tested in references 5 and 6. This
permission was granted;[15] Engelhard Industries agreed to
cooperate in this joint effort by catalyzing the silicon
carbide substrate using the Nissan formulation. An agreement
to provide Engelhard with access to the pertinent catalyst
information was then reached between Nissan and Engelhard to
facilitate this work.
III. Program Design
The testing was conducted in two separate phases:
1. Bench testing; and
2. Cold start and emissions testing at 73°F conditions.
The bench test phase consisted of determining catalyst
yield at control led steady-state feed methanol
flowrate/temperature conditions. The cold start testing was
conducted to determine whether a 4-cyUnder, 1.8-liter engine
could start and idle on the product gas from the dissociator
with no supplemental liquid methanol fuel. If it proved
possible to start and idle the test engine on the dissociator
product alone, the engine would then be emission tested using
alternately M100 liquid methanol from a conventional fuel
injection system and product gas from the dissociator.
IV. Dissociator Operation
Methanol may be dissociated to hydrogen and carbon
monoxide via the reaction:
i > 2H2 < g > +• C0( g >
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The dissociator described below accomplished this reaction
by a three-step process. First, methanol was vaporized in a
boiler and the vapor stream flowed to a superheater. The
vaporized methanol was then superheated and the hot gas passed
to a catalyzed and heated dissociator. The hot methanol vapor
was dissociated in this final stage and passed into the test
engine intake manifold. A detailed description of each part of
the process is given below.
A. Boiler Unit
The boiler was a 5-gallon capacity, type 316 stainless
steel pressure vessel. The vessel was fitted with a steam
heating coil, pressure relief valve, liquid temperature
monitor, and pressure gauge. The boiler was filled with
approximately three gallons of methanol prior to each test and
sealed; no provision was made for adding fuel to the vessel
following the commencement of a test.
Liquid temperature and pressure inside the boiler were
maintained at approximately 190-195°F and 30 psig respectively
during testing. Fuel feed rate was determined indirectly; the
filled vessel was carefully weighed prior to and at the end of
testing, and the test process timed.
B. Superheater
The superheater was constructed from a 3-foot-long section
of 1-inch diameter 304 stainless steel pipe. This pipe section
was heated by wrapping it with a ceramic bead insulated
nichrome wire heater that utilized 120-volt alternating
current. Power to the heater was controlled by a thyristor.
C. Catalytic Dissociator
The superheated methanol vapor passed through a porous
silicon carbide substrate which had been coated with the
catalyst to be evaluated. The substrate was resistively heated
by passing direct current through it. This catalyzed heater
acted as the methanol dissociator.
The substrate was shaped in the form of a hollow
cylinder. Methanol vapor flowed radially through the porous
heater walls; the dissociation reaction occurred as the vapor
contacted the hot catalyzed walls. Element specifications are
given in Appendix A.
V. Supporting Equipment
H2 composition in the product gas mixture was determined
by gas chromatography. A GOW-MAC Model 69-550 gas chromatograph
was used, and its operation is detailed in Appendix B.
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test engine used for this experimentation wa
single-overhead camshaft, 1.8-liter di
Details and engine specifications are pr
C.
The test engine used for this experimentation was a Nissan
CA18E, single-overhead camshaft, 1.8-liter displacement
engine. Details and engine specifications are provided in
Append i x
Emissions characterized as hydrocarbons were measured with
a Beckman Model 400 flame ionization detector. A FID response
factor of 76 percent was used.[16]
Exhaust formaldehyde was measured using a dinitrophenyI-
hydrazine (DNPH) technique.[17] Exhaust carbonyls including
formaldehyde are drawn through DNPH-coated cartridges forming
hydrazone derivatives. These derivatives are separated from
the remaining unreacted DNPH by high performance liquid
chromatography (HPLC). A spectrophotometer in the
chromatograph effluent stream drives an integrator which
determines formaldehyde derivative concentration.
VI. Discussion
A. Bench Test Experiments
The bench test experiments were conducted to determine
catalyst yield under specific inlet gas temperature
conditions. Catalyst yield is defined as the percentage of
feed methanol converted to H2 and CO gases.
The methanol flowrate from the boiler during dissociator
operation varied between 2400-2500 grams per hour; this was
calculated to be close to the flowrate necessary to start and
idle an engine of the same displacement as our test
engine.[18] The temperature of the methanol vapor into the
dissociator was an important parameter because it indicates the
degree of superheating for a given methanol flowrate.
Methanol was heated in the boiler to 195°F and passed to
the superheater. Current to the heating coils in the
superheater was controlled to superheat the methanol vapor to
various temperatures over the range 400°F to 700°F. Power to
the dissociator was supplied by a Power Mate alternating
current to direct current converter; this device allows a
maximum power output of 1000 watts. The maximum power level
attained with the dissociator was 345 watts; 15 amps current at
23 volts. Electrical resistance across the dissociator and its
electrical leads was measured at 2.5 ohms.
Table 1 presents a summary of test conditions for the
catalyst yield evaluation.
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Table 1
Test Conditions For Catalyst Yield Determination
Test cell temperature
Boiler liquid temperature
Boiler pressure
Methanol flowrate from boiler
Gas temperature out of superheater
Gas temperature out of dissociator
Power to dissociator
73°F
195°F
35 psig
2400-2500 grams/hour
410-710°F
316-365°F
345 watts
Tedlar sample bags were( used to collect the product vapor
from the dissociator; the collected vapor was then fed to the
gas chroma tograph by evacuating the sample bag to the
chromatograph column. Unreacted methanol vapor was condensed
in the sample bag and volumetrically measured to ensure its
inclusion in the yield calculation.
A graph of superheated vapor temperature versus product
yield is given below in Figure 1.
FIGURE 1
METHANOL DISSOCIATION CATALYST YIELD-
VERSUS GAS TEMPERATURE INTO DISSOCIATOR
— H2/CO PRODUCT YIELD
16
YIELD IN PERCENT
14
12
10
8
6 -
4 -
2
-i—i—i—i—i—i—i—i—i—i—\—i—i—i—i—i—i
400
460
500 660 600 660
INLET GAS TEMPERATURE (DEG. F)
•2500 G/HR METHANOL FEED FLOWRATE
700
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Product yield proved to be only slightly dependent on
dissociator inlet gas temperature. A 300 degree increase in
inlet gas temperature from 410°F to 710°F, increased the methanol
conversion rate only 2 percent, from 13 to 15 percent.
The data in Figure 1 suggests that the yield may be limited
by factors other than energy supplied by the superheater.
Effective substrate surface area may be a problem here; the
fibrous silicon carbide may not provide a surface area as
effective for the catalytic activity required as alumina-coated
monoliths or packed bed ceramic substrates, for example. Vapor
flow inside the dissociator was not studied; flow through the
catalyzed fiber walls may occur in such a manner as to make less
than optimum use of the total catalyzed surface area. Flow
conditions through the walls may allow certain sections of the
exposed to higher volumetric flowrates of the hot
other sections (uneven flow distribution through the
The flow of vapor may also cause certain sections of
fibers to experience greater catalytic
sections of the same fibers (geometry
conditions on parts of individual fibers).
be limited by an insufficient amount of
catalyst material coated on the substrate to carry the reaction
to a greater degree of completion in the residence time of the
gas in the dissociator.
wal I to be
vapor than
substrate).
individual substrate
activity than other
resulting in stagnant
Activity might
also
Power to the resistively heated dissociator substrate was
kept constant at 345 watts during the testing. High power levels
for dissociator operation were considered desirable in order to
provide sufficient energy for the endothermic dissociation to
proceed to a high degree of completion.
Oissociator outlet gas
sampling. A graph of gas
temperature at the outlet of
temperature was also measured during
temperature at the inlet versus gas
the dissociator is given in Figure 2.
FIGURE 2
GAS TEMPERATURE AT DISSOCIATOR
OUTLET VERSUS INLET GAS TEMPERATURE*
400
300
200
100
OUTLET GAS TEMPERATURE (DEG. F)
400 460 500 660 600 660 700 760
INLET GAS TEMPERATURE (DEG. F)
•2500 G/HR METHANOL FEED FLOWRATE
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Outlet gas temperature from
positively correlate with increases
the superheater. Instead outlet
relatively constant at approximately
the dissociator did not
in temperature of gas from
gas temperature remained
350°F during testing.
Energy supplied by the resistively heated substrate may be
a very important limiting factor for the dissociation
reaction. Karpuk [19], in a private communication to EPA,
calculated a power requirement of 2256 watts to dissociate 2000
grams per hour of methanol . Our calculations of this
requirement show it to be 2230 watts, essentially the same.
Significant heat transfer from the dissociator housing to the
atmosphere may be occurring despite our efforts to insulate
this housing. If the endothermic reaction is power limited, it
may be necessary to reduce the feed flowrate of methanol to
improve percent product yield at lower temperatures with the
current dissociator system.
B.
Cold Start Experiments
A cold start of the 73°F overnight-soaked engine was
attempted using only the product gas from the dissociator as
the fuel source. (Prior to testing the engine main fuel
injectors were disconnected.) Test conditions are given in
Table 2.
Table 2
Test Conditions For Cold Start Experiments
Test cell temperature
Boiler liquid temperature
Boiler pressure
Methanol flowrate from boiler
Gas temperature out of superheater
Gas temperature out of dissociator
Power to dissociator
73°F
190-195°F
20 psig
2400 grams/hour
450 °F
335°F
345 watts
Approximately 12 feet of plastic tubing connected the
dissociator to the EGR port. A valve to allow emissions
sampling and a flame arrestor were also located in this line.
These restrictions, however, did not combine to reduce fuel
flow to the point that engine performance at idle was
noticeably affected. Although the fuel entry passageway to the
combustion chambers was not standard (via EGR chamber to intake
runners) it proved sufficient to allow a start and idle at the
cond it i ons i n Tab Ie 2.
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Product gas from the dissociator was fed to the EGR port
for 3 seconds prior to a crank attempt. The engine immediately
started. The idle was rough, however, possibly signifying a
fuel/air imbalance; spark from the ignition system was present
during crank and run periods. Wetting of the plugs was noticed
following rough idle periods that ended with engine stalls.
The engine may be operating in an improperly rich mode
during an extended idle. Heating of the boiler, superheater,
and dissociator cannot be regulated in a manner that would
provide instantaneous changes in fuel flowrate to accommodate
changes in fuel flow requirements. Dumping part of the fuel
flow to the stack scrubber with a three-way bypass valve by
hand was tried; the response was improved, yet this improvement
was not sufficient to prevent engine laboring.
Two other factors combined to change the fuel mixture from
those mentioned in reference 6. First, substantially more
H2/CO was produced at lower temperatures with the catalyst
tested here than from other noble metal catalysts evaluated at
similar feed methanol flowrates. Second, a practical, onboard
methanol dissociator would not be provided with a blanket of
nitrogen or other inert gas in the dissociator to prevent
undesirable combustion reactions from occurring. Previously
N2 was added over the boiler to prevent these reactions and
to act as a carrier gas to increase the quantity of methanol
flow from the boiler. It was recently noticed that feed
methanol flowrates similar to the rates in references 5 and 6
could be attained through changes in boiler operating
temperature and pressure, rather than with the addition of
Nj . These engine tests were conducted without the addition
of N2 to better simulate actual onboard conditions. The
elimination of this additional diluent N2 caused the fuel/air
mixture to be somewhat richer than the mixture in references 5
and 6.
Emission results are presented in Table 3. Levels of
emissions characterized as hydrocarbons and formaldehyde were
measured in order to determine whether the choice of fuel
systems influenced pollutant emission levels. The test cycle
was a cold start followed by a 5-minute idle. HC and HCHO
emissions are expressed in average rates of grams per minute
and milligrams per minute, respectively. Oxides of nitrogen
(NOx) and CO emissions were not measured with the M100 liquid
fuel system due to problems with the analyzers.
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Table 3
Emission Levels Over Cold Start and Idle (73°F)
HC HCHO CO NOx
Fuel System Configuration (g/min) (mg/min) (g/min) (g/min)
Methanol injectors 3.68 1.0 N/A N/A
functioning
Oissociator fuel system 2.38 0.8 1.45 0.02
Emissions of HC were slightly lower with the dissociator
system than from the injector-fed liquid fuel system. This
difference may be due to improved starting performance caused
by the methanol and H2/CO fuels admitted to the engine in a
hot gaseous state rather than as atomized liquid. HCHO
emissions with the dissociator were relatively unchanged from
liquid fuel system levels. NOx emissions with the dissociator
were 0.02 grams per minute; engine coolant temperature however
did not exceed 110°F during the test cycle. NOx and CO
emissions with the liquid fuel system were not measured due to
problems with the analyzers.
A trend toward lower HC and HCHO emissions with partial
dissociation of the methanol fuel was observed. These
decreases in emissions may not be definitive, however; the
engine was tested only three times using the dissociator as the
fuel supply system. Additional testing would have to be
conducted in order to more properly define the difference in
emission levels.
C. Examination of Substrate Following Testing
Following the cold start testing, the superheater and
dissociator were disassembled to check for signs of coking and
subsequent catalyst poisoning. This particular catalyst
formulation was evaluated in order to determine its
effectiveness during operation at lower temperatures less
likely to promote the undesirable coking react ion.[20] Signs
of coking would obviously be given serious consideration with
regard to catalyst durability given the limited amount of
testing conducted here.
The walls of the substrate were visibly free of any
carbonaceous matter; no coking was observed on either the inner
or outer walls of the hollow cylinder. Traces of coke were
noticed at the interface between the nichrome flame-sprayed
ceramic, the stainless steel wool gaskets, and the stainless
steel electrical contacts.
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Current density may be uneven across the flame-sprayed
ceramic surface. Several rust/corrosion spots were noticed on
the flame-sprayed surface; any unevenness in the physical
characteristics of the interface could have caused areas of
increased current density across the interface. Areas of
higher current density would also be areas of higher
temperature. Temperature was not measured at the
ceramic-to-metal interface. It is possible that the interface
temperature significantly exceeded the measured gas
temperatures. The fiber substrates are very porous; it is
possible therefore that some of the dissociated CO contacting
the interface was brought to a high enough temperature to
undergo decomposition to coke.[21]
Earlier in this report it was stated that electrical
resistance across the dissociator, to include its electrical
contact system, was measured at 2.5 ohms. Resistance over the
substrate alone was measured at various points on the
flame-sprayed ends of the hollow cylinder. These measured
resistances varied between 2.0 and 10.5 ohms.
This variation in resistance may be caused by an uneven
flame spray on the ends of the hollow cylindrical ceramic
substrate. Flame-sprayed metal absorbs into the porous
ceramic. The flame-spray process also must be carefully
controlled to prevent cracking of the sprayed ceramic surface
because of differences in thermal expansion coefficients
between the ceramic and the metal. The ceramic-to-metal
interface should be improved to reduce the possibility of hot
spots developing at the bond surface that could promote
undesirable side chemical reactions.
VII. Test Highliqhts
1. The catalyst evaluated converted 15 percent of a
stream of 2400 grams per hour of methanol to H2/CO gaseous
fuel. Temperature of the feedstream into the dissociator
reactor was 410-710°F during this testing.
2. The dissociation catalyst substrate was resistively
heated; power was supplied to the dissociator at a rate of 345
watts during testing. Gas temperature out of the dissociator
remained relatively constant, at approximately 350°F during
testing. This temperature did not change as inlet gas
temperature for a constant mass flowrate feedstream of
2400-2500 grams per hour varied between 410-710°F.
3. A 1.8-liter test engine was cold started and idled
on the product gas stream from the dissociator alone. Extended
idle periods were characterized by rough engine performance;
plug wetting was noted after several stalls. The engine
appeared to be operating in a very rich mode at idle with the
dissociator. Methanol flowrates between 1800-2500 grams per
hour are difficult to control with the tested dissociator
apparatus, however.
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4. Pol lutant emissions from the test engine were
measured over a cycle consisting of a cold start and a 5-minute
no-load idle with the dissociator as the sole fuel source.
Pollutants characterized as hydrocarbons and formaldehyde were
measured at 2.38 grams per minute and 0.8 milligrams per
minute, respectively. CO and NOx emissions over the same cycle
were measured at 1.45 and 0.02 grams per minute, respectively.
5. No coking was observed on the walls of the ceramic
substrate following this evaluation. Traces of coke were found
at the interface between the silicon carbide substrate,
stainless steel wool gaskets, and the stainless steel
electrical contacts. Hot spots caused by areas of high current
density along this interface may have contributed to this
I oca Ii zed cok i ng.
VIII.AcknowIedgmen t s
The silicon carbide substrate used in this experimentation
was provided by Coloroll, pic., a United Kingdom corporation.
The dissociation catalyst formulation evaluated here was
developed by the Nissan Motor Company, Ltd. The catalysis of
the silicon carbide substrate was done by Engelhard
Industries. The test engine was also provided by Nissan Motor
Company, LTD.
The author appreciates the efforts of James Martin,
technician, Standards Development and Support Branch, Emission
Control Technology Division, who greatly assisted the author
with this project. Jim was also largely responsible for the
setup of the engine used for this testing.
In addition, the author appreciates the efforts of
Jennifer Criss and Marilyn Alff of the Control Technology and
Applications Branch, ECTD, for typing, formating, and editing
this report.
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IX. References
1. "Development of Methanol Lean Burn System," Katoh,
K. Y. Imamura, and T. Inoue, SAE Paper 860247, February 1986.
2. "Interim Report On Durability Testing of Low Cost
Catalysts for Methanol-Fueled Vehicles," Wagner, R. and L.
Landman, EPA/AA/CTAB/TA/84-4, August 1984.
3. "Using Methanol Fuels In Light-Duty Vehicles,"
Brown, D. , F. Golden, E. Gons, R. Potter, SAE Paper 872071,
November 1987.
4. "Unassisted Cold Starts to -29°C and Steady-State
Tests of a Direct-Injection Stratified-Charge (DISC) Engine
Operated On Neat Alcohols," Siewert, R. and E. Groff, SAE Paper
872066, November 1987.
5. "Evaluation of Coloroll Methanol Dissociator For
Cold Start Assist Application," Piotrowski, G., EPA/AA/CTAB/
87-08, December 1987.
6. "Resistively Heated Methanol Dissociator For Engine
Cold Start Assist-lnterim Report," Piotrowski, G.,
EPA/AA/CTAB/88-02, March, 1988.
7. "Resistively Heated Metal Monolith As A Cold Start
Assist For A Methanol Engine - Interim Report," Piotrowski, G.,
EPA/AA/CTAB/88-11, December, 1988.
8. "Study of the Methanol Reformed Gas Engine," Hi rota,
T., Japan Society of Automotive Engineers Review, March 1981.
9. "Dissociated Methanol Citation: Final Report,"
Finegold, J., G. Glinsky, and G. Voecks, SERI/TR-235-2083,
DE85000505, August 1984.
10. Briefing to C. Gray, Jr., U.S. EPA by Nissan Motor
Company, March 1987.
11. "High Activity Catalyst For Reforming Of Methanol
And Process Of Preparing Same," Masuda, K. to Nissan Motor
Company, Ltd., United States Patent No. 4,499,205, dated
February 12, 1985.
12. "Catalyst For Reforming Of Methanol And Process Of
Preparing Same," Masuda, K. to Nissan Motor Company, Ltd.,
United States Patent No. 4,501,823, dated February 26, 1985.
13. "Catalyst For Reforming Of Methanol And Process Of
Preparing Same," Eto, Y., to Nissan Motor Company, Ltd., United
States Patent No. 4,511,673, dated April 16, 1985.
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X. References (cont'd)
14. Letter from He 11 man, K. H., U.S. EPA, to Kawajiri,
H., Nissan Research and Development, Inc., February 16, 1988.
15. Letter from Kawajiri, H., Nissan Research and
Development, Inc., to Hellman, K. H., U.S. EPA, April 4, 1988.
16. FID Methanol Response, Memo, Edward A. Barth,
OAR/OMS/ECTD/TEB, Ann Arbor, Ml, August 1987.
17. Formaldehyde Measurement In Vehicle Exhaust At MVEL,
Memo, Gil key, R. L., OAR/OMS/EOD, Ann Arbor, Ml, 1981.
18. Dissociated Methanol Fuel Requirements to Start A
Four-Cylinder Engine, Memo from Gregory K. Piotrowski,
OAR/OMS/ECTD/CTAB, Ann Arbor, Ml, 1986.
19. Private Communication, Karpuk, M. E., to U.S. EPA,
1987.
20. "Engine Cold Start With Dissociated Methanol,"
Greiner, L. and E. Likos, Proceedings of the Third
International Symposium on Alcohol Fuels Technology, May 29-31,
1979.
21. "Dissociated Methanol Test Results," Finegold, J.
G., and J. T. McKinnon, SERI/TP-235-1582, April 1982.
22. Fundamentals p_f Gas Analysis by Gas Chromatography,
Thompson, B., Varian Associates, Inc., Palo Alto, CA, 1977.
23. Basic Gas Chromatography, McNair, H. , Bonelli, E.,
Consolidated Printers, Berkeley, CA, 1968.
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APPENDIX A
DISSOCIATOR ELEMENT SPECIFICATIONS
The dissociator substrate consists of a highly porous
ceramic to which electric current is applied. The fluid to be
heated is passed through the void spaces in the material. Heat
transfer is encouraged by the very large surface area of the
ceramic (the material contains greater than 80 percent void
space).
Specification ranges for certain properties of the
material used in the dissociator are given below. The exact
specifications for the dissociator material are proprietary to
the manufacturers of the elements, Coloroll, pic., Havenside,
Boston, Lincolnshire, U.K.
Property Range of Values
Power density 10-1600 W/cm3
Normal range 10-300 W/cm3
Power dissipation 0.01-0.75 W/cm2
Heatup/response time Milliseconds
Heat transfer surface/volume 400-750 cm2/cm3
Operating temperature Up to 1000°C
Material density 0.1-0.5 gin/cm3
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APPENDIX B
HYDROGEN CONTENT DETERMINATION
Background
The basis for gas chromatographic separation is the
distribution of a sample between two phases. One of these
phases is a stationary bed, and the other is a gas which
percolates through the stationary bed. An inert carrier gas
carries the components to be separated through a column
containing the stationary phase. The active component of the
stationary phase selectively retards the sample components
according to their distribution coefficients, until they form
separate bands in the carrier gas. These component bands leave
the column in the gas stream and are recorded as a function of
time by a detector.
If the stationary phase is a solid, this particular gas
chromatographic technique is referred to as gas-solid
chromatography. Common packings used are silica gel, molecular
sieve and charcoal. Gas-solid chromatography was used in this
experimentation, and the details of the procedure are given
below. More complete explanations of gas chromatographic
technique are provided by Thompson and McNair.[22,23]
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APPENDIX B
HYDROGEN CONTENT DETERMINATION (CONT'D)
Specificat ions:
Chromatograph model
Detector:
Operating principle
Temperature control
Carrier gas
Detector elements
Noise
Drift
Injection:
Number of ports
Control
Operating temperature
Column Oven:
Temperature range
Control
Co Iumn:
Gas flow system:
The rmaI conduc t i v i t y
bridge control:
Electrical :
Power requirements
Circuit breaker
Physical:
GOW-MAC Model 69-550
Thermal conductivity type
Ambient to 300°C
N2
Four (4) rhenium tungsten elements
10-micro volts maximum
40-micro volts/hour maximum
Two
Solid-state, variable-voltage
phase control
Ambient to 300°C
Ambient to 300°C
Solid-state time apportioning
5' x 1/4" molecular sieve
Dual-column with dual-inject ion
ports and exits
Continuous current adjust 50-300
mA. Bridge zero adjust.
Attenuator for bridge output, 10
posi t ions to 512.
105-125 volts, 50/60 H,
7 amps
Two-section construction. Upper
section houses column oven,
detector and vaporizers. Lower
section contains power supply,
bridge control circuit and
temperature controllers.
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APPENDIX B
HYDROGEN CONTENT DETERMINATION (CONT'D)
Compressed Gas Auxiliaries:
Zero gas N2
Span gas 40 percent H2/60 percent N2
Output:
Stripchart recorder So I tech model 3318
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APPENDIX C
TEST ENGINE SPECIFICATIONS
Manufacturer
Basic engine designator
Displacement
Cylinder arrangement
VaI vet rain
Combustion chamber
Bore x stroke
Compress i on ratio
Compression pressure
Fuel control system
EGR
Valve clearance
Idle speed
Eng i ne oil
Fuel
Engine cranking speed
Nissan Motor CO., LTD.
CA18E
1809 cc
4-cyIinder, in-Iine
Single-overhead camshaft
Semi-spherical, 2 spark plugs
per cyIinder
83 mm x 83.6 mm
11.0
17.0 kg/square cm (350 rpm, 80°C)
EIectron i caI Iy controI Ied fueI
inject ion
EGR not used
0.30 mm HOT, intake and exhaust
700 rpm
Special formulation supplied by
Nissan for methanol engine
operat ion.
M100 neat methanol
240 rpm
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