Performance Analysis of a Spark Ignition Hydrogen/Ammonia DUAL Fuel Engine

This paper proposes ammonia as a combustion inhibitor to control the combustion process in pure hydrogen engines. A three-dimensional spark ignition engine simulation model is established, coupled with a hydrogen/ammonia chemical reaction mechanism. The reliability of the model is verified using experimental data. The influence of different excess air coefficients (EACs) on hydrogen engine power, combustion, and emission performance is studied under ammonia blending conditions. The results show that the indicated thermal efficiency (ITE) increases as the EAC grows, while the mean indicated pressure and indicated power decrease. The ammonia blending ratio (ABR) of 30% improves the mean indicated pressure and the ITE of the hydrogen engine when the EAC is in the range of 1.4–1.6. The improvement is most significant at the EAC of 1.4, with increases of 4.18% and 4.58%, respectively. However, the heat release rate peak is reduced by 40%. When the EAC exceeds 1.6, ammonia blending reduces the mean indicated pressure. As the EAC grows, the in-cylinder pressure and heat release rate decrease, resulting in a prolonged burning period. When the EAC is 1.4, adding 30% ammonia causes the crankshaft angle corresponding to peak pressure to approach the top dead centre. Increasing the EAC and blending ammonia can reduce in-cylinder combustion temperatures. When the EAC exceeds 1.8, hydrogen engines under both ABRs can achieve near-zero nitrogen oxide emissions.