The effects of microwave on the performance and emission characteristics of a diesel engine operating on pure hydrogen

Abstract

Reducing emissions from diesel engines remains an important challenge for sustainable and environmentally friendly transportation. Hydrogen is a promising alternative fuel due to its clean combustion; however, ignition stability still limits its wider internal combustion engine applications. This study investigates the use of hydrogen fuel, combined with microwave-ignition to improve combustion efficiency and achieve zero-carbon emissions. We employed hydrogen as the primary fuel in computational fluid dynamics simulations of a single-cylinder diesel engine model. Microwave energy was introduced as an ignition source and the effects of injection timing, microwave power, and oxygen concentration on combustion characteristics were evaluated. Both direct and premixed injection strategies were analyzed to compare their effects on ignition behavior and overall combustion performance. The findings showed that the highest indicated power was achieved at an injection advance of 31 degrees CA (Crank Angle). In order to prevent knocking under these conditions, the microwave power needed to be at least 3.1 kW. Overall, the results indicate that microwave-assisted hydrogen combustion can significantly improve combustion stability and efficiency, highlighting its potential as a low-emission combustion strategy.