Influence of hydrogen addition on the performance and emissions of gasoline engine

• Gasoline engine performance has been investigated with Gasoline-hydrogen fuel. • Four fuel samples of gasoline-hydrogen have been adopted in this study. • Hydrogen improved knock limit by 4% and 8% with 10% and 15% addition. • Hydrogen addition significantly decreased NOₓ emissions by 77% at 15%. • At high hydrogen ratios and engine speeds, BSFC increased, BTE decreased. To support the gradual shift toward hydrogen-enriched hybrid combustion engines, this study examines the changes in engine performance, combustion characteristics, and emission profile of a gasoline engine when hydrogen is added. Experimental tests for pure gasoline were collected to establish baseline performance data with a laboratory test rig equipped with a single-cylinder, air-cooled gasoline engine operating between 1400 rpm and 3600 rpm at full load, while hydrogen addition was investigated separately through Diesel-RK numerical simulations. Hydrogen addition to gasoline was evaluated at volumetric ratios of 5%, 10%, and 15%. The analysis focused on brake power, torque, brake-specific fuel consumption, brake thermal efficiency, and nitrogen oxide (NOₓ) emissions. The results showed that adding 5% hydrogen improved brake power by 8% and reduced brake-specific fuel consumption by 7.5% compared to pure gasoline. Torque values increased by 17% and 22% as the hydrogen content in blends grew from 10% to 15%, respectively. The octane number required to prevent knocking decreased by 4% through 10% hydrogen addition and by 8% with 15% hydrogen. Using fuel blends containing 5%, 10%, or 15% hydrogen reduced nitrogen oxide emissions to 40%, 65%, and 77%, respectively. However, at high engine speeds, brake power and thermal efficiency decreased when provided with excessive hydrogen addition, caused by air–fuel mismatch and incomplete combustion processes.