분사조건에 따른 가솔린 직접분사용 다공 분사기에서의 LPG 분무특성

Abstract

Liquefied petroleum gas (LPG) is regarded as an alternative fuel for spark ignition engine due to similar or even higheroctane number. In addition, LPG has better fuel characteristics including high vaporization characteristic and low carbon/hydrogen ratio leading to a reduction in carbon dioxide emission. Recently, development of LPG direct injection systemstarted to improve performance of vehicles fuelled with LPG. However, spray characteristics of LPG were not well understood,which is should be known to develop injector for LPG direct injection engines. In this study, effects of operation conditionincluding ambient pressure, temperature, and injection pressure on spray properties of n-butane were evaluated andcompared to gasoline in a multi-hole injector. As general characteristics of both fuels, spray penetration becomes smaller withan increase of ambient pressure as well as a reduction in the injection pressure. However, it is found that evaporation of nbutanewas faster compared to gasoline under all experimental condition. As a result, spray penetration of n-butane wasshorter than that of gasoline. This result was due to higher vapor pressure and lower boiling point of n-butane. On the otherhand, spray angle of both fuels do not vary much except under high ambient temperature conditions. Furthermore, sprayshape of n-butane spray becomes completely different from that of gasoline at high ambient temperature conditions due toflash boiling of n-butane.