Combustion characteristics of a compression ignition engine fuelled with diesel—ethanol blends

Abstract

Combustion characteristics were analysed in a compression ignition engine fuelled with diesel—ethanol blends with and without a cetane number improver. The results show that, for the same brake mean effective pressure and engine speed, the maximum cylinder pressure P_max, the ignition delay, the premixed combustion duration, and the fraction of heat release in premixed combustion phase will increase, while the diffusive combustion duration, the fraction of diffusive combustion phase, and the total combustion duration decrease with increase in the ethanol fraction in the blends. Meanwhile, the centre of the heat release curve moves close to the top dead centre, and the maximum rate (dQ_b/dφ)_max of heat release and the maximum rate (dp/dφ)_max of pressure rise increase with increase in the ethanol fraction in the blends. The addition of a cetane number improver is beneficial to the decrease in the ignition delay, the cylinder peak pressure, the maximum rate of pressure rise, and the combustion noise when operating on diesel—ethanol blends.