An experimental investigation of high-load conditions using micro-pilot diesel injection with diesel/propane dual-fuel combustion in a light-duty CI engine

Dual-fuel combustion can achieve near-zero NOx and PM emissions with higher indicated thermal efficiency under mid-load conditions. However, it has low combustion efficiency because of the THC slip caused by the crevice effect. In addition, under the high-load condition, the maximum pressure rise rate (MPRR) drastically increases (over 10 bar/deg) because of the simultaneous auto-ignition of gaseous fuels, and the noise vibration harness (NVH) problem occurs. There is a limitation to substituting a high ratio of volatile fuels such as gaseous fuels because high-volatility fuels have poor reactivity for the auto-ignition. However, a higher ratio of gaseous fuel must be introduced to decrease PM emissions and save diesel fuel. Therefore, it is important to investigate the potential of using the gaseous fuel in a dual-fuel combustion to widen the high-load conditions with stabilized combustion, low MPRR and low emissions.