An experimental and modelling study of the combustion and emission characteristics for gasoline-diesel dual-fuel engines

In this study, the combustion and emissions characteristics of gasoline-diesel dual-fuel operation were investigated both experimentally and numerically. Gasoline fuel was injected through an intake port, and diesel fuel was injected directly into the combustion chamber to trigger combustion. The tested concentrations of diesel fuel were 30 per cent and 40 per cent, and it was found that a smaller amount of diesel fuel forms a more homogeneous mixture. Numerical calculations were performed for selected injection timings (i.e. -20 degrees crank angle (CA) after top dead centre) for increased understanding of the combustion regime of dual-fuel combustion using the KIVA code coupled with the primary reference fuels mechanism. The injection timings of the diesel fuel were swept from -40 degrees to +3 degrees CA. The results showed that gasoline-diesel dual-fuel operation exhibited significant reductions in soot and nitrogen oxide emissions by suppressing the formation of locally rich mixtures or high-temperature regions. However, the carbon monoxide and hydrocarbon emissions were increased for a wide range of injection timings.