Optimization of hydrogen premixing and alcohol additives for improved efficiency, emissions, and economics in a dual-fuel engine using watermelon seed oil–diesel blend: RSM–TOPSIS approach

This study aims to investigate the impact of benzyl alcohol and ethyl alcohol blending with hydrogen premixing on compression ignition engine characteristics. The fuel samples are prepared by blending benzyl alcohol/ethyl alcohol at 20 and 40% with equally blended watermelon seed oil-diesel fuel. Central composite methods are used to prepare the two experimental matrixes, one with benzyl alcohol and the other with ethyl alcohol, with a blending ratio of 0 to 40% and a percentage loading of 50 to 100% in the presence of hydrogen (10 LPM). A response surface model found satisfactory for the confidence level of 95%. Blending benzyl alcohol at 40% elevates thermal efficiency by 11.90%, exergy efficiency by 15.52%, sustainability index by 9.75%, carbon dioxide by 4.46%, nitrogen monoxide by 40.46%, and enviroeconomic loss by 4.46%. Conversely, this blend reduces entropy generation by 4.66%, carbon monoxide by 52.28%, hydrocarbon by 15.45%, smoke by 27.77%, thermoeconomic loss by 59.83%, and exergoeconomic loss by 12.68%. Blending of ethanol up to 40% abates the thermal efficiency by 6.34%, exergy efficiency 5.5%, carbon dioxide by 14.86%, carbon monoxide by 18.83%, hydrocarbon by 43.56%, nitrogen monoxide by 6.35%, smoke by 2.77%, enviroeconomic loss by 9.73%, and elevates the thermoeconomic loss by 25.5% and exergoeconomics loss by 12.23%. TOPSIS is used to identify the optimal blending ratio and loading conditions. The TOPSIS results indicate that a 40% benzyl blending ratio and 75% loading conditions yield the best operating conditions. Higher BSNO emissions limit this study, but future studies can investigate mitigations. This constraint recommends future studies should investigate EGR and SCR for BSNO emission reduction.