Effectiveness of the Speed Reduction Strategy on Exhaust Emissions and Fuel Oil Consumption of a Marine Generator Engine for DC Grid Ships

Recent developments in power electronics, energy storage systems, and renewable energy; increased market demands for more efficient and cleaner electric power to meet stricter environmental regulations; and development in gigawatt (GW)-class DC (direct current) transmission systems for transmission of greater power over longer distances than similar alternative current (AC) systems, have supported the development of the DC grid, making it a promising solution for both the onshore and offshore industries. This paper presents an experimental study on the effectiveness of an engine speed reduction strategy on exhaust gas emission and fuel consumption when applied to a 4-stroke generator engine equipped with a cam-driven plunger diesel injection system. The experiments were performed on an 8-cylinder V-type 4-stroke generator engine installed in the MASTC laboratory, which is the only demonstration testbed for the ship’s electric propulsion system in Korea. Experimental results showed that fuel consumption decreased, but emission mass fraction in exhaust gas increased when maintaining engine power while reducing engine speed. This study has shown economic benefits in reducing fuel consumption, but incurred penalties for the emission performance of 4-stroke generator engines equipped with cam-driven plunger diesel injection systems when applying the engine speed reduction strategy.