Experimental and CFD analysis on the impact of hydrogen as fuel on the behavior of a passenger car gasoline direct injection engine

Abstract

The influence of hydrogen induction on the behavior of a Multi cylinder automotive GDI (Gasoline Direct Injection) engine was studied. An advanced 3D engine simulation was done and validated with experimentally acquired 5% and 10% hydrogen mass coupled with gasoline direct injection. Comparing to the pure gasoline mode, introducing hydrogen showed considerable improvement in engine's BTE (brake thermal efficiency) at all power outputs. The maximum BTE was observed as 27.2%, 30% and 32.5 respectively with pure gasoline, 5% and 10% hydrogen mass shares at the engine's power output of 21 kW. At all power outputs, hydrogen admission was shown to produce a smaller amount hydrocarbon (HC) and carbon monoxide (CO) emissions than pure gasoline operation. At 21 kW engine power the HC was noted as 3360, 2400 and 2050 ppm respectively with Pure Gasoline, 5% and 10% hydrogen mass shares. CFD results on the HC and CO emissions indicated a strong agreement with the experimental results. NOx emission was noted as higher with hydrogen addition (80 and 100 ppm respectively with 5% and 10% hydrogen mass shares) as compared to 60 ppm with pure gasoline mode. High temperature of the gas supported by the CFD due to the rapid combustion of hydrogen was noted as the reason for the higher NOx emissions with hydrogen addition. CFD results on cylinder pressure and HRR matched very well with the experimental results. A small amount of hydrogen added to the gasoline as a fuel supplement might greatly improve BTE while lowering HC and CO emissions. The recommended optimum hydrogen mass share is 10% for the best performance of the above said engine without any modification in engine design.