Investigations on combustion characteristics of lean burn SI engine fuelled with Ethanol and LPG

Abstract

This paper presents an effective experimental approach that can be applied to stationary single cylinder LPG fuelled lean burn SI engine. This approach has been applied to operate the engine under different equivalence ratio at wide open throttle condition. Experiments were conducted at a constant speed of 1500 rpm and at compression ratio of 10.5:1. In this study the effects of adding small amount of ethanol (5%, 10% and 20%) along with LPG were investigated. Ethanol on volume basis was injected along with carburetted LPG. A maximum brake thermal efficiency of 28.5% with 10% ethanol addition for LPG were observed at an equivalence ratio of 0.7. The ethanol addition with LPG extended the lean limit as compared to pure LPG. Also, it was observed that 10% Ethanol addition resulted in reduced HC and CO emissions due to oxygen present in the ethanol. The combustion parameter shows increased heat release rate and reduced cyclic variations with 10% ethanol addition. The optimal ethanol blend with LPG was found to be 10% for better performance and reduced emissions.