Effects of ethanol–diesel–biodiesel blends on combustion and emissions in premixed low temperature combustion

Abstract

In this study, the effect of ethanol on combustion and emissions in premixed low temperature combustion (LTC) was investigated in a four cylinders heavy-duty diesel engine. The biodiesel was used as an additive to prevent the stratification of ethanol and diesel blends. The premixed LTC is achieved by the medium level of EGR and the prolonged ignition delay. Compared with diesel fuel, ethanol–diesel–biodiesel blends have lower NOx emissions due to lower combustion temperature, resulting from the higher latent heat of vaporization. Unfortunately, the lower combustion temperature also leads to the higher HC and CO emissions. Smoke emissions for ethanol blends decrease obviously because of higher oxygen content and longer ignition delay. The oxygen in ethanol also has a favorable impact on the reduction of smoke emissions, which is obvious in high loads. Thus, the upper load limit of LTC mode is extended. Compared with diesel fuel, 20 vol.% ethanol in diesel and biodiesel blends (BDE20) has lower NOx and smoke emissions and higher brake thermal efficiency in LTC.