Design optimization for an LPG automobile engine

Previous attempts to convert conventional gasoline engines into Liquefied P etroleum Cas (LPG) engines have always proved futile due to lack of perform ance and incompatible emission levels. It is easily recognized that LPG and liquid gasoline require very different combustion conditions. Thus, an eng ine system designed for gasoline does not necessarily meet the required con ditions for LPG operation. In addition, then is no readily available means to determine the proper operation conditions for an LPG engine, In this pap er, we propose a design optimization methodology based upon now visualizati on technique. The experimental results proved that the flow speed serves as a good measurement for the mass flow rate in the LPG engine system. The te st system based on the proposed design achieved very good performance and w as able to met the Taiwan Environmental Protection Agency (EPA) emission st andards.