Feasibility evaluation and optimization of liquefied petroleum direct injection (LPDI) conversion engine for low pollutant emission vehicles

Abstract

Owing to environmental regulations and energy issues, the development of low-emission and high-efficiency vehicles is required. Liquefied petroleum gas (LPG) is a representative low-pollutant fuel and the third most commonly used fuel for internal combustion engines worldwide. In this study, we propose to convert the existing gasoline direct injection (GDI) to liquefied petroleum direct injection (LPDI) as the simplest way to reduce pollutant emissions from the exhaust gases of internal combustion engine vehicle (ICEV). The conventional GDI engine fuel system was converted to an LPG system, and the pollutant emissions and three-way catalyst conversion efficiency were analyzed. As a result of fuel conversion, a phenomenon occurred in which the three-way catalyst did not operate normally under some operating conditions. By calibrating the fuel pressure signal by signal converter to increase the pressure in the high pressure fuel rail, the three-way catalyst was normalized. Finally, by adjusting the fuel rail pressure of the LPDI conversion engine, the optimization was performed, and the engine performance was evaluated.