Influence of the mixture of gasoline and diesel fuels on droplet atomization, combustion, and exhaust emission characteristics in a compression ignition engine

The purpose of this study was to investigate the fuel properties, droplet atomization, combustion performance, and exhaust emission characteristics of gasoline–diesel direct blended fuels in a four-cylinder diesel engine. The gasoline fuel was blended as a volumetric fraction of conventional diesel fuel. The droplet size of test fuels was measured using a phase Doppler particle analyzer (PDPA), and the combustion and emission characteristics were investigated for a four-cylinder diesel engine with a common-rail injection system and emission analyzer. In this study we found that increasing the gasoline volume fraction decreased the fuel density, kinematic viscosity, and surface tension. The temperature for 10% distillation (T10) decreased as the gasoline fraction increased. The blending of gasoline caused a decrease in droplet size by increasing the small droplets and decreasing the large droplets because the surface tension decreased with the addition gasoline fuel, thereby inducing an increase in droplet instability. On the other hand, gasoline blending resulted in an extension of the ignition delay and the formation of a more homogeneous mixture. These combustion characteristics caused the simultaneous reduction of ISNOx and ISsoot. However, the ISHC and ISCO emissions were slightly increased. The difference in ISHC and ISCO emissions between pure diesel and gasoline blended diesel fuels decreased as the engine load increased. An increase in engine load diminished the effects of gasoline blending on combustion performance and exhaust emissions. ► The effect of gasoline blending on combustion and emission were investigated. ► The addition of gasoline induced the decrease of droplet size of blending fuels. ► The extended ignition delay of blended fuels affected the reduction of emissions. ► At low load, HC and CO increased with the gasoline contents. ► Increasing engine load decreased HC and CO emission by gasoline blending.