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The Natural Gas Vehicle (NGV) Challenge '92, was organized by Argonne National Laboratory. The main sponsors were the U.S. Department of Energy the Energy, Mines, and Resources - Canada, and the Society of Automotive Engineers. It resulted in 20 varied approaches to the conversion of a gasoline-fueled, spark ignited, internal combustion engine to dedicated natural gas use. Starting with a GMC Sierra 2500 pickup truck donated by General Motors, teams of college and university student engineers worked to optimize Chevrolet V-8 engines operating on natural gas for improved emissions, fuel economy, performance, and advanced design features. This paper focuses on the results of the emission event, and compares engine mechanical configurations, engine management systems, catalyst configurations and locations, and approaches to fuel control and the relationship of these parameters to engine out and tailpipe emissions of regulated exhaust constituents.

The cyclic and steady-state vehicle emissions, fuel economy, performance, and cold start behavior of an automobile equipped with a direct injection methanol engine are compared with those of three other comparable vehicles. One of the comparable vehicles was powered by a gasoline-fueled engine, and the other two were Diesels. One of the Diesel-powered vehicles was naturally aspirated and the other was turbocharged. All evaluations were made using the same road load horsepower and equivalent test weight. All the evaluations were conducted at low mileage. The emissions of the methanol vehicle are compared to California low emission vehicle standards, and to the emissions of another methanol vehicle.

A woven fiber Diesel particulate filter has been developed which demonstrates good low-mileage soot-trapping and regeneration efficiencies. The fiber filters are wound around electric heating elements, which provide uniform energy in close proximity to the soot-laden fiber during regeneration. The filters are loaded with particulate to a target backpressure and energized one at a time with intermittent particulate loading to the target backpressure between successive filter regenerations. These design features were utilized to help minimize regeneration power requirements, and maximize mileage accumulation between regenerations. Regenerations are performed with unbypassed exhaust flow and can be accomplished under high vehicle speed operation as well as under idle conditions. The passenger car system contains four filters which are approximately 20 inches long and 3.0 inches in diameter.

The possibility of high sulfate emissions from future emission control systems prompted an evaluation of a low sulfate system designed to meet 1981 emission standards. An air injected oxidation catalyst was added to a Volvo “Lambda-Sond” emission control system. After baseline determination of gaseous and sulfate emissions, the air injection system was modified to reduce sulfates. Optimization tests determined the best air injection schedule for sufficient CO control while limiting sulfate production. A sulfate reduction of 99 percent was achieved. The system was then durability tested for 64,400 km.