Experimental Investigation on the Effect of Blending Ethanol on Combustion Characteristic and Idle Performance in a Gasoline Rotary Engine

Rotary engine is an ideal electric vehicle range extender. However, the combustion chamber of rotary engine is very narrow and long at the top dead center, which is detrimental to fuel combustion performance. In order to improve its economic and emission performance, this paper built an ethanol/gasoline dual-fuel rotary engine test bench, and the combustion and emission performance of gasoline rotary engine under five ethanol blending ratios were studied. The experimental results showed that, when the fuel pulse width is not adjusted, since the calorific value of ethanol is lower than that of gasoline and the latent heat of vaporization of ethanol is higher than that of gasoline, the addition of ethanol in gasoline lowers the peak pressure. When the ethanol blending ratio reaches 30 vol%, the pressure curve shows a distinct double peak. Under the theoretical air-fuel ratio condition, mixing ethanol in gasoline increases the heat release rate, shortens the combustion duration while prolonging delay period. After blending ethanol, HC, CO and NOx emissions have been reduced under various operating conditions. Excessive ethanol blending ratio increases NOx emissions and increases cycle variation coefficient. When the ethanol blending ratio is 15 vol%, it has better power ability while maintaining low cycle variation coefficient and emissions.