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This paper describes the results of a liquefied petroleum gas (LPG) fleet test conducted using para-transit, medium-duty vehicles. The vehicles were part of an active municipal fleet providing daily service on varying operating routes. Over a period of nine months, each vehicle was fueled with a series of butane/propane mixtures. The mixtures tested were HD5 LPG as the baseline fuel, 20 percent butane/80 percent propane, 30 percent butane/70 percent propane, and a final blend of 50 percent butane/50 percent propane by volume. The test vehicles showed improved fuel economy as the butane content increased in the fuel mixture, even without modification to existing LPG fuel systems. The improved fuel performance was consistent with the higher energy content of butane, compared to an equal volume of propane. The vehicles displayed no symptoms of performance or maintenance problems that would be related to operation of the fuel mixtures.

This paper describes experiments conducted to determine Federal Test Procedure (FTP) exhaust emissions, ozone-forming potentials, specific reactivities, and reactivity adjustment factors for several butane/propane alternative fuel blends run on a light-duty EHC-equipped gasoline vehicle converted to operate on liquefied petroleum gas (LPG). Duplicate emission tests were conducted on the light-duty vehicle at each test condition using appropriate EPA FTP test protocol. Hydrocarbon speciation was utilized to determine reactivity-adjusted non-methane organic gas (NMOG) emissions for one test on each fuel.

This paper describes experiments conducted to determine the regulated emissions, ozone-forming potentials, specific reactivities, and reactivity adjustment factors for eight butane and propane alternative fuel blends run on a light-duty vehicle, emission certified to be a California transitional low emission vehicle (TLEV) and converted to operate on liquefied petroleum gas (LPG). Duplicate EPA FTP emission tests were conducted with each fuel. Hydrocarbon speciation was utilized to determine reactivity-adjusted non-methane organic gases (NMOG) emissions for one test on each fuel. Results showed that all eight fuels could allow the converted vehicle to pass California ultra-low emission vehicle (ULEV) NMOG and oxides of nitrogen (NOx) standards. Six of the eight fuels could allow the vehicle to pass ULEV carbon monoxide (CO) standards. BUTANE has been an important gasoline blending component for many years.

California intends to improve its air quality with the introduction of California Phase 2 Reformulated Gasoline (CP2 RFG) into the current fleet of vehicles in 1996. A prior study demonstrated that this fuel change alone can reduce Non-Methane Organic Gas (NMOG) emissions and Reactivity Weighted Emissions (RWE) by 34% and 28%, respectively, relative to the 1990 Auto/Oil Air Quality Improvement Research Program (AQIRP) Industry Average Gasoline (RF-A).1 Beyond CP2 RFG, California plans to progressively reduce vehicular emissions specifications between the years 1993 and 2003, which should force vehicle manufacturers to develop Advanced Technology Vehicles (ATV's) to maintain compliance. This study measured the emissions of 31 ATV's produced by six domestic and foreign vehicle manufacturers. CP2 RFG was found to be just as effective at reducing hydrocarbon mass emissions, Reactivity Weighted Emissions (RWE), and toxics in ATV's as in the current fleet of vehicles.

A test program was undertaken to demonstrate that a realistic gasoline could reduce both hydrocarbon mass and reactivity of vehicle exhaust emissions and simultaneously reduce toxics, carbon monoxide, and nitrogen oxide emissions. In order to evaluate the effect of RVP and aromatics, four highly reformulated gasolines were blended from existing refinery streams with RVP at a nominal 8 and 7 psi and aromatics at a nominal20 and 10 vol%. The emissions performance of these fuels were measured in a fleet of ten 1990 California vehicles. When compared to industry average gasoline, each of the four gasoline test blends demonstrated substantial emission reductions in criteria pollutants and toxics. Estimates of the cost and emission benefit of these gasolines were used to evaluate the cost-effectiveness of these formulations for California.