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1997 PVC emissions results

Established technology finishes first in '97 Propane Vehicle Challenge emissions competition

San Antonio, Texas - May 20, 1997 - Two university teams using gaseous fuel injection technology (Texas Tech University and the University of Waterloo, Ontario), achieved the best overall emissions results in their respective categories of minivans and pickup trucks for the 1997 Propane Vehicle Challenge (PVC). Waterloo's emissions tests helped them to win overall first place for the pickups, while GMI Engineering and Management Institute took overall first place in the minivan category.

The competition, held May 5-19 in San Antonio, College Station, and Austin, Texas, included 17 teams from colleges in Canada, Puerto Rico, and the United States. In the contest to convert their vehicles from gasoline to propane fuel, ten teams chose liquid fuel injection, five gaseous fuel injection, and two gaseous carburetion systems. Emissions tests and fuel economy determinations on the vehicles were carried out in San Antonio at Southwest Research Institute's^® (SwRI^®) Emissions Research Department. Evaluations were based on the federal test procedures used to certify new vehicles. Each vehicle was run on the Horiba electric chassis dynamometer through stop-and-go and freeway simulations.

"Emissions tests were the most heavily weighted test category in the competition," says SwRI Research Engineer Kevin Whitney, PVC coordinator of emissions and fuel economy testing. " Of a possible final total of 1000 points, 200 were awarded for emissions and another 100 for fuel economy tests. This is because part of the competition's purpose is to demonstrate the clean-burning, fuel-efficient qualities of propane. We knew there would be a close relationship between the final emissions scores and the choice of fuel delivery system, but the interdependency was stronger than we had expected."

"In fact we were surprised by some of the results," comments Whitney. "Five teams for example, did not meet 1979 standards in one or more categories and as a result gained no points. Two teams were unable to complete the test for mechanical reasons. Of the remaining teams, six had chosen liquid fuel injection and the other four gaseous fuel injection systems. Gaseous fuel injection is an older, more established technology, and the final results showed teams that chose this technology had fairly successful emissions scores."

There were developmental problems with a number of the liquid fuel injection systems. This technology is generally considered more technically 'advanced' than gaseous fuel technology. The systems occupy less space, provide more potential power, and are easier to meter through fuel injectors; thus providing many advantages. Several teams however, had not anticipated the extreme levels of engine heat and as a result had problems with fuel vaporization.This led to fuel starvation, vapor lock, and ultimately poor emissions. The competition showed that good fuel control, calibration, and thermal management is critical in the success of this technology.

"The two teams that selected gaseous carburetion systems," adds Whitney, "had difficulty controlling their air/fuel ratios and achieving a stoichiometric mixture. One team ran the engine very rich, the other very lean. In both cases emissions were high and their scores low."

In the fuel economy tests, The University of Texas at El Paso (UTEP), a liquid fuel system team, won the minivan section of this competition. The University of Tennessee won in the pickup category. UTEP had developed an innovative fuel distribution 'spider' to keep the liquid propane cool and prevent vapor lock. Because of this, the team not only scored perfect marks in the 'hot start' event, but were awarded a prize for the competition's most innovative engine component.

"We wanted to be involved in the Propane Vehicle Challenge for a number of reasons," says Charles Hare, Director of SwRI's Emissions Research Department. "A major goal of our organization is to promote cleaner air. We also think it's important to give students hands-on experience with the difficulty of calibrating and controlling engines for low emissions as is expected for alternative-fuel vehicles that enter the consumer market. The student teams were not all able to test their vehicles using advanced equipment in the design stages, but now they have all had that opportunity."

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