The Effect of Hydrogen Addition on a RCCI Engine Performance Fueled with Natural GasDiesel Fuel at Low Load Range

The aim of this study is to evaluate the effect of hydrogen addition on a heavy-duty diesel engine performance and emission under RCCI combustion fueled with natural gas and diesel fuel. For this purpose, a single-cylinder heavy-duty diesel engine is used to operate at a low-load range from 5.6 to 7.7 bar gross IMEP, constant engine speed, and a fixed amount of diesel fuel. Furthermore, in order to reduce hydrocarbon fuels consumption, hydrogen is gradually added to natural gas while the total fuel energy content is kept to be constant. The results show that by adding hydrogen to natural gas in the RCCI engine at 5.6, 6.3, and 7.7 bar gross IMEP, the hydrogen energy share would be enhanced up to 35.7%, 23.70%, and 9.93%, respectively. And also, the overall hydrocarbon fuels consumption per cycle can be reduced up to 45.23%, 29.26%, and 12.07%, respectively. Although CO and UHC emissions decrease drastically, NOx increases significantly with the addition of hydrogen compared to RCCI combustion fueled with natural gas and diesel fuel.