Experimental investigation on effects of oxygen enriched air on performance, combustion and emission characteristics of a methanol fuelled spark ignition engine

The present experimental investigation deals with the study of the effect of oxygen enriched intake air on performance, emission and combustion characteristics of a methanol (M100) fuelled spark ignition engine. The oxygen in the intake air of the engine fuelled with methanol was enriched from 23% (by mass) with base oxygen to 26.5%, 38.7% and 60.4%. The brake thermal efficiency increased drastically with methanol with 38.7% and 60.4% enriched air by 9.9% and 20.5% respectively. The peak pressure and cumulative heat release with the highest enriched air (60.4%) are higher about 2 and 1.27 times than base oxygen percentage (23% by mass). The ignition delay and combustion duration decreased by 35.24% and 57.8% respectively. Carbon monoxide (CO) and hydrocarbon (HC) emissions with the highest enriched air decreased substantially by 48.59% and 30.9%. However, nitrogen oxides (NOx) emission increased drastically by 112.2% with 38.7% of oxygen but it decreased by 31.5% with 60.4% oxygen enriched air which is lower than base oxygen. A notable conclusion emerged from this study is that a methanol fuelled engine with the oxygen enriched air (60.4%) could emit very lower emissions (CO, HC, NOx) along with improved thermal efficiency compared to base oxygen (23% by mass).