Abstract
Keywords:
Liquid Phase LPG injection, Start phase, Leakage fuel recirculation system, Activated carbon, Fast response THC analyzer, Gas chromatography, SULEV, Zero evaporative emissions
Abstract
The liquefied petroleum gas (LPG), mixture of propane and butane, has potential for reducing the toxic hydrocarbon emissions and ozone formation due to its chemical composition. However, conventional mixer systems have problems to meet the future low emission standards because of the difficulty in controlling the precise air/fuel ratio according to mileage accumulation. Liquid Phase LPG injection (LPLi) system has the advantage of more precise mixture control and higher engine performance than those of conventional mixer type. However, LPLi system has difficulty in meeting the stringent future emission regulations because of the leakage phenomena at the injector tip that produces excessive amount of THC emission during cold and hot restart phase of LPLi engine. The main focus of this paper is the development of leakage fuel recirculation system with activated carbon canister to eliminate the leaked fuel at intake system. Leaked fuel level was quantified using fast response THC analyzer and gas chromatography. THC concentration during cold and hot restart stage was reduced over 50% and recirculation system has the effective measure to meet the SULEV standard of LPLi Engine.