Combined Impact of Alcohol-Fuel Properties on Performance and Emissions Characteristics with Low-Temperature Combustion in a Diesel Engine

Abstract

Low-temperature combustion (LTC) is a new combustion mode, and low cetane number fuels may be more appropriate for the LTC. Fuel properties play important roles both in the physical process of fuel-air mixing and the chemical process of combustion in the cylinder of diesel engines. Alcohol additives in diesel will definitely change its fuel properties. In this paper, an experiment was conducted to investigate the combined impact of alcohol fuel properties on the performance and emissions characteristics of a diesel engine operated at the LTC mode. A total of 20% ethanol, 20% propanol, and 20% n-butanol by volume were added in the diesel (represented as E20, Pr20, and Bu20), respectively, at different exhaust gas recirculation (EGR) rates. The results show that when the EGR rate reaches up to 35%, the CA50 phase obviously retards for E20, while the corresponding EGR rates are 40% for Pr20 and 45% for Bu20. The effects of fuel properties on cycle-to-cycle variations may be random or stochastic. Medium EGR rates may be the best choice for the LTC. Fuel properties have little effect on CO, THC, and NOx emissions. But E20 can reduce soot emissions greatly within medium EGR regions. That is, E20 may be more proper as diesel LTC fuel.