Reducing NOx Emissions From Diesel Engines
Compact Membrane Systems, Inc.
325 Water Street
Wilmington, DE 19804
Telephone: 302-999-7996
http://www.compactmembrane. com
Environmental Problem
Nitrogen oxides (NOx) lead to acid rain and con-
tribute to unhealthy ground-level ozone and smog,
often leading to severe respiratory problems among
affected communities. Diesel engines produce unac-
ceptably high levels of NOx at high loads, and NOx
from nonroad diesel engines represents an increasing
percentage of the environmental pollution in nonat-
tainment regions (areas that do not meet primary
environmental standards), where more than 90 mil-
lion Americans live. Economical, easy-to-integrate
solutions are needed to meet the NOx reduction
goals of the Clean Air Act.
SBIR Technology Solution
A promising new method of reducing NOx emis-
sions involves the recycling of exhaust gas in a
process called exhaust gas recycle (EGR). ECR sends
captured exhaust gas back into the combustion
chamber of the engine, thereby increasing fuel
economy and reducing emissions: a 25% ECR leads
to a 50% reduction in NOx. There are some prob-
lems, however, associated with the process, includ-
ing: (1) extra pumping and cooling of the EGR
stream, (2) engine wear from recirculating engine
soot, and (3) high feed air water vapor levels. These
issues can be avoided by the use of nitrogen-
enriched air (NEA), which reduces the diesel com-
bustion temperature and, in turn, the amount of
NOx emitted in the engine exhaust. The NOx
reductions achieved through NEA are similar to
those accomplished through the EGR process, while
simultaneously avoiding the pumping, cooling,
wear, and water vapor issues associated with EGR.
With support from EPA's SBIR Program, Compact
Membrane Systems, Inc. (CMS), in cooperation
with its commercialization partners, has developed
stable fluoropolymer membranes to nitrogen enrich
the turbocharged intake air to diesel engines.
Cooled turbocharged air is processed by an NEA
membrane to supply NEA to the diesel engine
intake. NEA reduces the diesel combustion temper-
ature; in turn, the amount of NOx produced and
emitted in the engine exhaust is greatly reduced.
CMS membrane modules are designed for very
high flux, harsh operating conditions, stable per-
formance, and production of NEA in the range of
79.5% up to 84%. As a result of EPA's SBIR funding
and collaborations with downstream partners and
commercial membrane manufacturers, CMS has
made large advances in demonstrating and com-
mercializing NEA membranes for NOx reduction in
diesel engines, particularly for truck, generator,
marine, and locomotive platforms.
Commercialization Information
Working with major industrial gas companies (e.g.,
Praxair and Air Liquide) and their membrane divi-
sions (IMS and MEDAL), CMS has produced large,
SBIR Success Stories
commercial-sized membrane modules. In collabo-
ration with Caterpillar, these large commercial-sized
modules have operated successfully in excess of 1
million on-road miles on five Class 8 diesel trucks.
Independent laboratory testing of the membrane
systems showed them to have excellent fouling
resistance to ingested dust and durability to an
excess of 1 million pressurization cycles while oper-
ating at high temperature (85°C) and high pressure
(30 psig). Caterpillar tests over a broad cycle
showed that the membranes exceeded the target
NOx emission reduction of 50%.
CMS' successful field demonstration with Caterpillar
in combination with support from EPA's SBIR
Program has led to additional opportunities that
presently are under commercial/developmental
evaluation. Low-speed marine diesel CMS mem-
branes on Scandinavian ferries and ships have been
tested and achieved the target 30% NOx reduction
with less than 5% fuel penalty.

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The retrofitting of installed emergency generators
with CMS NEA membranes is being evaluated, and
the membranes show promise for creating cost sav-
ings from peak electric power rates. Stand-alone
membrane units driven by a vacuum pump have
been developed, offering an alternative to retro-
fitting machinery with minimal or no downtime.
These additional programs have successfully com-
pleted the feasibility phase.
Company History and Awards
CMS was founded in 1993, based on membrane
technology acquired from E.I. DuPont. CMS is locat-
ed in Wilmington, Delaware. CMS' focus is on the
research, development, and commercialization of
membranes and thin films composed of fluorinated
polymers with exceptional gas transport properties
and chemical resistance. The firm holds numerous
patents for its technology.
In 1998, 2000, and 2007, CMS received the
Tibbetts Award as an Outstanding Small Business in
the State of Delaware. This award is given by the
U.S. Small Business Administration to firms judged
to exemplify the best in small business innovation
and research. The company's goal is to become, in
combination with its partners, the world market
leader of amorphous perfluoropolymer membranes
for gas transport (including NEA).
Although CMS products are focused on perfluo-
ropolymers, the company serves a broad range of
markets that can utilize the unique features of CMS
membranes. The California Air Board certified CMS'
membrane cartridge to capture escaping gasoline
vapors at pumps and tank vents and return the
gasoline to underground storage tanks.
SBIR Impact
¦ Economical, easy-to-integrate solutions are needed to meet the nitrogen oxides
(NOx) reduction goals of the Clean Air Act.
Compact Membrane Systems, Inc. (CMS) demonstrated that a high-productivity
nitrogen-enriched air membrane can be used to reduce diesel engine NOx emissions
by 50%.
CMS has successfully field demonstrated commercial-sized membrane modules
with Caterpillar. In these on-road tests, the membranes exceeded the target NOx
reduction of 50%.
The NEA membrane system approach also allows for a stand-alone unit,
conserving costs and time needed for retrofitting equipment.
SBIR Success Stories

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