Research on the performance and emission characteristics of the LNG-diesel marine engine

Based on the marine diesel engine using liquefied natural gas (LNG) as an alternative fuel, a control system for a dual fuel engine had been designed with the use of the model-based design (MBD) method to reduce the development time. Without changing the original engine structure, a LNG supply system and electronic control system were added to the engine. All of the performance experiments were carried out according to the propulsion characteristics and load characteristics. The fuel economy and emissions of the dual fuel diesel engine were investigated compared to the original diesel engine. The cost, Braked-specific fuel consumption (BSFC), and hydrocarbon (HC), nitrogen oxides (NOx), carbon monoxide (CO) and particulate matter (PM) contents were tested. The results show that the dual fuel control system could work steadily over a long period of time. Compared to the original diesel engine, the maximum decrease of BSFC was 13.4% at 1300 r min−1. Thus, the maximum saved cost is 124 RMB h−1 according to Chinese prices of diesel fuel and LNG. The PM and NOx emissions decreased significantly, while the CO and HC emissions increased slightly.