Presently, the automotive industry is undergoing a paradigm shift towards the optimisation of fossil fuel utilisation, with a concomitant transition to renewable alternatives. The research community has a vested interest in the field of renewable fuels, particularly with regard to their reduced emissions profile. The present study utilises AVL Fire software to simulate a four-cylinder, four-stroke engine with a displacement of 2.4 litres, operating at 1600 rpm. The fuel for this engine is diesel, with hydrogen and ammonia introduced as additives. The fuel blends that were tested included H2/diesel, H75-A25/diesel, H25-A75/diesel, ammonia diesel, and pure diesel with 5% EGR. Each cycle of the diesel engine injects a total mass of 162 mg, with an additional 15 mg of combined hydrogen and ammonia, thereby reducing the total amount of diesel fuel utilised. Furthermore, the study employs two injectors for a two-stage fuel injection process, whereby the primary fuel is injected directly, while hydrogen and ammonia are injected indirectly into the air intake. The present study investigated the effects of diesel fuel additives on power, torque, pressure, temperature, combustion efficiency and the heat transfer coefficient. The findings indicated that hydrogen exhibited superior combustion efficiency in comparison to ammonia-diesel blends, as evidenced by 11% higher peak pressures and a 16% increase in temperature. Furthermore, hydrogen-rich blends have been shown to exhibit significantly enhanced heat transfer and temperature profiles, demonstrating superior performance in terms of combustion intensity and overall efficiency when compared with ammonia. The stability of combustion is consistent across different fuel types; however, hydrogen consistently exhibits superior performance metrics. It is evident that there is an absence of exhaust peaks mid-crank (600–750°), with the most pronounced levels being observed in H₂5–A₇₅ fuels. HCN has been observed to have a maximum in ammonia-rich fuels and a minimum in H2 fuels. It is evident that the prevailing tendencies demonstrate a predilection for CO₂ in comparison to CO, a phenomenon that can be attributed to the observed shifts in fuel chemistry.

Keywords