This study investigates the impact of hydrogen energy share and excess air ratio on the combustion characteristics of an ammonia-hydrogen jet ignition engine at compression ratios of 11.5 and 17.3 under 800 rpm and approximately 6 bar IMEP. The results indicate that, when passive jet ignition is used for both compression ratio conditions, a high hydrogen energy share is required to achieve stable combustion and high indicated thermal efficiency. Specifically, at the compression ratio of 11.5, a higher ammonia concentration is needed for stable combustion compared to the compression ratio of 17.3. Additionally, the range of excess air for stable combustion is narrower at the compression ratio of 17.3. The use of hydrogen as the auxiliary fuel for active jet ignition significantly reduces the overall hydrogen energy share required to achieve stable combustion.
The global transition to alternative power sources, particularly fuel cells, hinges on the cost-effective production and distribution of hydrogen fuel. While green hydrogen produced through water electrolysis using renewable energy sources holds immense promise, it currently falls short of meeting the burgeoning demand for hydrogen. To address this challenge, alternative methods, such as steam reforming and partial oxidation of hydrocarbon fuels with integrated carbon capture, are poised to bridge the gap between supply and demand in the near to midterm. Steam reforming of methane is a well-established technology with a proven track record in the chemical industry, serving as a dependable source of hydrogen feedstock for decades. However, to meet the demand for efficient hydrogen storage, handling, and onboard reforming, researchers are increasingly exploring liquid hydrocarbon fuels at room temperature, such as methanol and ethanol.