6

Abstract—This paper investigates the use of alternative gaseous fuels in port fuel injection (PFI) spark ignition (SI) engines by means of Lotus Engine Simulation (LES) program. To this aim, the engine model for a commercial automotive SI engine was constructed and engine performances were determined for gasoline and alternative gaseous fuels i.e., compressed natural gas (CNG) and liquefied petroleum gas (LPG). The results show that brake thermal efficiency increases, while engine performance and fuel consumption decreases for methane and propane compared to gasoline at the same conditions. Engine performance improves when equivalence ratio is increased at a little quantity for gaseous fuels, while the fuel consumption remains almost stable. Engine performance also increases with increasing compression ratio for methane and propane, thus closer/equal performance values are obtained to gasoline. In this case, the brake specific fuel consumption decreases notable and significant increases are gained in brake thermal efficiency. Keywords—Alternative fuels, port fuel injection, spark ignition engine, engine performance, fuel consumption. I