Improvement approaches for the combustion process of recent diesel natural gas dual fuel engines – A technical review

Ship main engine exhaust gas emissions are a worldwide concern. Dual fuel diesel engines are a type of ship main engine that complies with MARPOL Annex VI. Low exhaust emissions and operational cost are the main advantages of using natural gas as fuel. Moreover, the use of natural gas improves lean combustion process; it results in fewer exhaust emissions and improves performance. Some technical adjustments are required to achieve maximum efficiency. This paper has reviewed various technical approaches to understand the combustion phenomenon of natural gas dual fuel engine diesel with experimental and numerical studies. Gaseous fuel/air mixture phenomena, pilot-fuel injection, and flame propagation processes that occur in the cylinder chamber are reviewed. Some improvements to the variation of test parameters of dual fuel diesel engines are highlighted to determine the characteristics. Additionally, the impact of natural gas-diesel dual fuel engines for performance and emissions is accurately described.