Effect of the fuelling strategy on the combustion and emission characteristics of a gasoline–diesel dual-fuel engine

Since improving the energy efficiency and reducing the air pollution are two of the largest issues in the automobile industry, many researchers have developed various combustion and emission technologies to solve these challenges. Among these various technologies, the gasoline–diesel dual-fuel method is of interest to improve the thermal efficiency and to reduce the emissions in diesel engines. The gasoline allows formation of a premixed fuel–air mixture without early ignition owing to its high evaporation rate and low reactivity. In order to investigate the effect of gasoline on the dual-fuel combustion and emission characteristics, combustion of gasoline–diesel blend fuels was simulated in a compression ignition engine by using the KIVA-3V code. For the multi-fuel simulations, a modified KIVA-3V code with a discrete multi-component model was used to represent the multi-fuel evaporation processes. This study showed that the gasoline in the dual-fuel blend improved the fuel–air mixing process to form homogeneous mixtures for the two different injection strategies: port fuel injection and direct injection of gasoline. In addition, the combustion characteristics of gasoline–diesel blend fuel were discussed by comparing them with those of the conventional diesel fuel. The gasoline in the dual-fuel blend increases the indicated power because of the release of high fuel energy and decreases the soot emissions. In this study, various gasoline-to-diesel ratios and various injection timings were used in order to enhance the understanding of the dual-fuel engine. The present study showed that low emissions and a high indicated power were achieved as the gasoline content is increased up to a certain value. However, an increase in the gasoline content in the dual fuel caused the autoignition and the combustion performance to deteriorate.