Biodiesel, HSD, and JP-8 Combustion Process and Emission Characteristics in a Dual-Stage Fuel Injection Condition

Abstract

This research was focused on an investigation of the effect of injection dwell time in a dual-stage injection on the combustion and emission characteristics of biodiesel using an optically accessible single-piston diesel engine. In addition, the results from biodiesel combustion and emission characteristics were compared to those of fossil fuels such as HSD and JP-8 using combustion process visualization as well as emission analyzer. Regarding combustion characteristics, JP-8 showed the highest peak in-cylinder pressure and rate of heat release in comparison to biodiesel and HSD because the higher lower heating value and vaporization characteristics of JP-8 improved premixed combustion. However, the IMEP of JP-8 was lower than the corresponding pressure of HSD. From the viewpoint of emissions, biodiesel had reduced emissions of NOx, HC, CO, and CO2 compared to fossil fuels regardless of the injection dwell time. The natural luminosity combustion images indicated that the biodiesel fuel had a shorter ignition delay, and the combustion progress of JP-8 was accelerated due to superior vaporization, although the initial combustion was slightly delayed in the second injection phase compared to biodiesel and HSD.