Advances in Hydrogen-Diesel Dual Fuel Engine Technology: A Systematic Review of Emissions and Performance Characteristics

Abstract

To meet the increasing energy needs globally and due to the depletion of fossil fuels, this systematic review aims to examine hydrogen diesel dual-fuel technology as a possible replacement for combustion engines. However, hydrogen is environmentally friendly, highly efficient, and carbon neutral. Still, several unknowns exist regarding the best methods of applying hydrogen in internal combustion engines and the challenges of using hydrogen in practice. This investigation details the energetic performance and emissions of hydrogen-diesel systems at various operating conditions and fills the gaps in knowledge on injection strategies, equivalence ratios, and performance limits. Our methodology involves strict criteria for article selection, clear metrics, and statistical analysis to ensure the robustness of the comparison. Quantitative results show that Brake Thermal Efficiency is improved by 8-15% with hydrogen enrichment at all operating conditions and reaches a maximum of 53.4% at optimal conditions. The optimal hydrogen substitution rate is chosen based on the best tradeoff between the combustion improvement and the volumetric efficiency. The emissions analysis shows that CO (33-48%), CO₂ (25-40%), and HC (78-85%) emissions are decreased dramatically while NOx emissions increase by 6-21% at high loads, which is still an unresolved problem. This study has several novel contributions, including systematic quantification of the effects of hydrogen substitution rates on combustion and resolution of the conflicting trends in NOx emissions by correlating them with specific operational variables. On-demand electrolysis is proposed as a solution to the hydrogen storage problem and an overall assessment of economic feasibility and component durability during the continuous operation of the dual fuel system. The research also considers ethical issues in hydrogen production, focusing on environmental justice, equity, and resource competition. Future research involves advanced control strategies, new NOx mitigation methods, and better electrolyzer designs. This work fills the gap between the theoretical potential of hydrogen and its real application. It provides practical recommendations for improving the efficiency of hydrogen-diesel dual fuel systems and thus reducing carbon emissions in transportation.