Developing Small Dual-Fuel Diesel Engine to Control Marine Pollution by Reducing NOx Emission for Application in Fishing Vessels

Using natural gas for fueling a ship growing extensively since environmental issues become one of the priorities in the shipping industry. The ship uses natural gas as the main fuel commonly called as a gas-powered ship. Gas has lower specific prices compare with any type of diesel fuel. But due to handling, storage, and distribution costs then gas prices for ships become higher even still a bit cheaper than diesel fuels. Besides prices, technically gas is cleaner so it may give the lower emission levels. Dual fuel technology is the best choice in occupied gas as ship fuel due to the existence of the IGF Code. Established Dual-fuel diesel engine is very expensive and available for big power capacity. This research develops a small dual-fuel diesel engine from a conventional engine with power less than 10 HP. The piston crown is a part of the engine that was modified so that the engine can use natural gas in the best performances as the conventional one. NOx as the most hazard emission in the diesel combustion process is controlled to be as the lowest as possible. The quality of air may be significantly affected by those small engine pollutions because of the large number of vessels in that dense environment in the typical fishery villages. In conclusion, the modified dual-fuel diesel engine capable of reducing NOx emission by up to 31% at a practical safe operation of 50% dual-fuel. The higher gas portion gives a lower NOx emission level.