Abstract
Potential of a dual-fuel engine of hydrogen ignited using diesel pilot was explored at a high load of 1.2MPa in IMEP by 3D-CFD. The CFD results have shown that ignition timing of hydrogen can be well controlled by optimizing the injection timing and quantity of diesel pilot, and mild burn with low NOx can be obtained by large amount of EGR gas. In the case of the homogenous distribution of hydrogen, that was conducted by early injection of hydrogen, the indicated thermal efficiency can reach 48.5%, that is the same level with a diesel engine. At the same time, engineout NOx can be drastically reduced to 50ppm (1/4 level of diesel) even at high load of 1.2MPa (IMEP) with a high ratio of EGR gas. Furthermore, hydrogen diffusive combustion conducted by the late injection (around TDC) of hydrogen with diesel pilot was explored by 3D-CFD. It has been indicated that thermal efficiency of the diffusive combustion, that is free from preignition, can be pushed to around 55% by increasing compression ratio.
