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.
