Influence of Combustion Duration on the Performance and Emission Characteristics of a Spark-Ignition Engine Fueled with Pure Methanol and Ethanol

[Image: see text] In this research, we estimated and summarized the effects of combustion duration on the performance and emission characteristics of a spark-ignition engine using pure methanol and ethanol as fuels, which have not been previously presented. From the results, we demonstrated that an increase in combustion duration causes a decrease in peak firing temperature and peak firing pressure and an increase in trapped residual gas. The level of trapped residual gas when using ethanol as fuel is higher than that of methanol fuel. The indicated mean effective pressure (IMEP) and brake mean effective pressure (BMEP) increase to maximum values and then decrease with increasing combustion duration, while the brake specific fuel consumption (BSFC) reaches a minimum value and then increases. The optimal BSFC improved to 33.31% when the engine used ethanol fuel instead of methanol. The increase in combustion duration helps to reduce NO(x) and HC emissions, but an increase in CO emissions is observed.