The Combustion Performance Experiment Study Of Marine Medium-speed Diesel-NG Dual-fuel Engine

In recent years, with the continuous rapid development of shipping transportation, it makes the demand for marine engines increase, and results in stimulating demand for energy and growing environmental pollution problems, so looking for alternative energy has been imminent. At the same time, people pay more attention on natural gas for numerous sources, higher calorific value, lower pollution etc.This topic is intended for the higher cylinder pressure of dual-fuel engine in the higher load and substitution rate conditions, which had been transformed by 6210ZLDS diesel engine during the test. I keep on a series of experimental researches. During the study, two solutions been used to reduce the higher cylinder pressure of dual-fuel engine, the first scheme is EGR system, it could reduce the burning speed by extending the ignition delay to reduce the maximum cylinder pressure, due to the few application in marine engines, so in this scenario, I recalculate and design a marine EGR cooler by the reference on vehicle engine EGR cooler and test requirements. We carry on the cooling capacity test, flow regulator test and experiment with the machine, through the experiments we could verify the EGR cooler cooling capacity, flow regulation ability and the effects on higher cylinder pressure of the dual-fuel engines. The second program is improving the fuel pump plunger for marine engine by adding a spiral groove at the low load, making dual-fuel engine in dual fuel mode, with the increase of substitution rate, the supply advance angle could be delayed, so we could reduce the higher cylinder pressure in dual fuel mode.The results showed that the cooling area based on the theoretical calculation provides a good theoretical basis for the design of EGR cooler, this kind of EGR cooler has sufficient cooling capacity, could satisfy the test requirements, through the test, we find that the EGR system could reduce the higher cylinder pressure and the effect is obvious; The second program, we find that in pure diesel mode, the oil advance angle gradually postpones with the reduction of the amount of fuel injection in the low load, while in the dual-fuel mode, the improved fuel pump plunger plays an significant role in reducing the higher cylinder explosion pressure.