Hydrogen has been expected as a promising alternative fuel for automotive engine applications in these days. As most suitable engine application of hydrogen, the authors propose direct injection (DI) diesel engines, which have higher thermal efficiency and lower wall heat losses due to its combustion located in the center of combustion chamber with air insulation layer. However, in the case of a diesel engine fueled with hydrogen, its higher auto-ignition temperature gives a very unstable operation. Therefore, the authors propose the methodology for raising the ambient gas temperature by adding a small quantity of Dimethyl ether (DME) to intake air. In addition, the intermediate products formed through the reactions of DME have possibilities of making auto-ignition of hydrogen jet easier and more stable. The authors have attempts to figure out the characteristics of combustion, engine performance and emission behavior in the hydrogen fueled DI diesel engine with DME intake addition. It was obtained that high performance, stable operations and low emission in engine experiments.
