Browse Publications Technical Papers 2005-01-3766

Achievement of Low Emissions by Engine Modification to Utilize Gas-to-Liquid Fuel and Advanced Emission Controls on a Class 8 Truck 2005-01-3766

A 2002 Cummins ISM engine was modified to be optimized for operation on gas-to-liquid (GTL) fuel and advanced emission control devices. The engine modifications included increased exhaust gas recirculation (EGR), decreased compression ratio, and reshaped piston and bowl configuration. The emission control devices included a deNOx filter and a diesel particle filter. Over the transient test, the emissions met the 2007 standards.
In July 2004, the modified engine was installed into a Class 8 tractor for use by a grocery fleet. Chassis emission testing of the modified vehicle was conducted at the National Renewable Energy Laboratory's (NREL) Renewable Fuels and Lubricants (ReFUEL) facility. Testing included hot and cold replicate Urban Dynamometer Driving Schedule (UDDS) and New York Composite (NYComp) cycles and several steady-state points. The objective of the testing was to demonstrate the vehicle's with the modified engine.
Average vehicle NOx emissions from the UDDS cycle were 6.20 g/mi and 4.26 g/mi from cold and hot runs, respectively, with nitrogen dioxide (NO2) emissions ∼50% of the total NOx emissions. Over the NYComp cycle, the cold start emissions were 12.75 g/mi and the hot start emissions were 7.74 g/mi. The carbon monoxide (CO), hydrocarbons (HC), and PM emissions were very low, with average PM less than 0.005 g/mile for hot starts over both cycles.
The test inertia weight was varied from 46,000 lbs to 63,000 lbs to 80,000 lbs on a random basis for repeated hot-start cycles. The NOx emissions varied from 3 to 5 g/mi over the UDDS cycle and from 6 to 8 g/mi over the NYComp cycle.
Steady-state testing was also performed at repeated cruise conditions ranging from 10 to 60 mph. Average NOx emissions on a g/mi basis were the highest for this test matrix at 6.7 g/mi during 10 mph cruise conditions, ∼3 g/mi over 20, 30, 40, and 50 mph cruises, and ∼1.8 g/mi during 60 mph cruise conditions.
The results from this testing showed that the modified engine and emission control systems performed effectively in vehicle operation. The technology performed as expected on two very different test cycles and a range of steady-state speed and load points. The longer-term durability of the technology will be measured after six months with additional chassis testing.


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