Combustion and emission characteristics of IC engines fueled by hydrogen and hydrogen/diesel mixtures and multi-objective optimization of operating parameters

“The present study considers combustion of hydrogen in IC engines. In general, the work focuses on simulating the engine performance and emissions at different operation parameters, and using optimization techniques. Task I work deals with the engine performance and emissions of a single cylinder spark-ignition (SI) engine fueled by hydrogen. The engine was simulated at different equivalence ratios, exhaust gas recirculation (EGR) and ignition timing. The results indicate that NOx emissions, engine power, and efficiency are reduced by increasing EGR level, and increased with increasing equivalence ratio and advanced ignition timing. The best operating conditions for hydrogen engines were obtained by solving the multi-objective problem of maximizing engine power and efficiency while minimizing the NOx. Task II deals with the engine performance and emissions of dual-fuel CI engines fueled by a hydrogen/diesel mixture. The engine was simulated under conditions of various hydrogen levels (%) by energy, diesel injection timing, and EGR levels (%). More hydrogen present inside the engine cylinder led to lower soot emissions, higher thermal efficiency, and higher NOx emissions. Ignition timing delayed as the hydrogen rate increased, due to a delay in OH radical formation. Exhaust gas recirculation (EGR) method and diesel injection timing were considered as well, due to their potential effects on the engine outputs. To obtain the best possible maximum efficiency along with lower NOx and soot emissions, optimization methods in (Task III) for the operating parameters were considered. Multi-objective problem with conflicting objectives was solved by using regression analysis, artificial neural networks, and genetic algorithms”--Abstract, page iv