Toward achieving a low-carbon/carbon-neutral society, there is an increasing need for engines that can use new fuels such as hydrogen and ammonia. Ammonia is attracting attention as a marine fuel, which should be easy to handle, because of its characteristic of easily liquefying when pressurized. However, it has issues such as the presence of unburned ammonia and N₂O, which has a greenhouse effect, in the exhaust gas when used as a marine engine fuel. To address these issues, we conducted three-dimensional combustion CFD analysis, combustion tests using a small engine, and catalyst matching for an exhaust gas after-treatment device, aiming to reduce unburned ammonia, N₂O, and NOx emissions. The results from the performance evaluation at the after-treatment device outlet suggested that an 89% reduction in greenhouse gas emissions, compared to diesel oil single-fuel firing of the base diesel engine, is possible.
