Analysis of hybrid electric vehicle performance and emission applied to LPG fuel system

Abstract

Global carbon neutrality policies have intensified regulations on automotive emissions. CO2 and particulate number (PN) are major pollutants, with CO2 contributing to global warming and particulates affecting human health. Despite the increase of electric vehicles, internal combustion engines remain prevalent owing to their mature technology, infrastructure and economic efficiency. Liquefied petroleum gas (LPG) is a promising alternative fuel with lower CO2 and PN emissions. LPG direct injection (LPDI) technology improves fuel efficiency and reduces emissions compared to current LPG vehicles. However, vapor-lock issues at high temperatures must be addressed. Hybrid electric vehicles (HEV), combining internal combustion and electric motors, improve fuel efficiency, reduce emissions and serve as a transitional technology prior to electric vehicle (EV). In this study, a conventional 2-liter gasoline hybrid electric vehicle is converted to an LPDI-HEV using LPG. The experimental results showed that the engine output was within 5 % of an equivalent level. In real vehicle tests with the hybrid system applied, CO2 emissions were confirmed to be within a 3% difference, indicating an equivalent level, while PN emissions were significantly reduced. Although the LPDI HEV has lower fuel efficiency compared to the gasoline direct injection hybrid electric vehicle (GDI) HEV, it was found to be 12 % more economical when considering costs. This study also assesses the economic viability and environmental benefits of converting GDI HEV to LPDI HEV in urban taxi applications, providing policy insights for sustainable transportation. © 2024