Visualisation of Ammonia Engine by prechamber igniter

Ammonia is considered more and more as a promising carbon-free fuel for internal combustion engines to contribute to the decarbonization of several sectors where replacing conventional engines with batteries or fuel cells remain unsuitable. However, ammonia properties can induce some challenges for efficient and stable combustion. The objective of this study is to investigate ammonia ignition and combustion development by means of passive prechamber igniter in a single-cylinder spark ignition engine with optical accesses based on natural chemiluminescence imaging to analyze flame development. The engine has a compression ratio of 9.5 and the experiments were conducted at 1000, 1500 and 2000 rpm. The experiments are focused on the lean operating limit as equivalence ratio as a function of the load, just before strong cycle-to-cycle variations and misfiring occurrence. By examining the effects of these strategies on ignition delay, flame propagation and stability, this study aims to identify the local ignition processes to mitigate ammonia’s combustion challenges and if prechamber ignition can enhance combustion efficiency significantly particularly at low load conditions as well as extending the operating limits.