Hydrogen–ammonia fuel blends for diesel engine performance, emissions, vibration–acoustic dynamics, and <scp>GEP</scp> optimization

Abstract This study examines the performance, combustion, emission, vibration, and acoustic behavior of a Common Rail Direct Injection (CRDI) engine fueled with diesel and hydrogen–ammonia dual‐fuel blends (FS1–FS4) at 4–8 L/min flow rates. The FS4 blend (8 L/min NH 3 + 8 L/min H 2 ) achieved the highest brake thermal efficiency of 31.55%, which is 34.4% higher than diesel, and reduced brake‐specific energy consumption by 12.4%. Cylinder pressure increased to 72.68 bar and the maximum heat release rate improved by 15.7%. In emission analysis, NO x levels increased slightly by 3.42%, while CO and HC emissions decreased by 14.6% and 11.3%, respectively, compared to diesel. Vibration and exhaust noise levels fell by 11.29% and 4.5%, demonstrating smoother operation. Gene expression programming (GEP) accurately predicted performance and NO x trends with R 2 = 0.996–0.998, confirming model reliability. The results highlight the promise of hydrogen–ammonia blends, particularly FS4, for improving energy efficiency, lowering fuel consumption, and reducing mechanical stress while maintaining acceptable emission trade‐offs in CI engines.