Development And Experimental Study Of Z6170 Marine Dual Fuel Engine With Dual Electric Control

With the increasingly stringent emission regulations and the increasing shortage of energy in the world,high efficiency,energy saving and environmental protection have become the leading direction of the development of internal combustion engine technology.Liquefied natural gas has the characteristics of high energy density,low emission and easy transportation,which is considered as the most promising clean fuel for engine.In the future ship manufacturing,LNG/diesel dual fuel engine has become the development direction of new ship power at home and abroad for its advantages of convenient production and modification,flexible fuel selection,high thermal efficiency,good environmental protection and economy.By means of theoretical analysis and bench test,the performance and emission characteristics of LNG/diesel dual fuel engine in common working modes are studied in this paper.The performance of dual fuel engine in diesel mode and dual fuel mode was studied under E3 mode and D2 mode,and the emission characteristics of NOx,CO2,THC and CO in diesel mode and dual fuel mode were studied under E3 mode.The results show that:(1)When E3 and D2 cycles operate in dual fuel mode,the power is the same as that of diesel mode,the boost pressure and the temperature of the vortex are slightly increased,the maximum explosion pressure and thermal efficiency are decreased,the replacement rate of dual fuel mode is greatly increased,and the load point of dual fuel mode is reduced from 25%to 10%,which widens the operation range of dual fuel mode.(2)Emission characteristics of E3 cycle:NOx and CO2 emissions of diesel mode are higher than those of dual fuel mode;THC and CO emissions of dual fuel mode are significantly higher than that of diesel mode;With the advance of fuel injection time,NOx and CO2 emissions increase,while THC and co decrease;With the increase of fuel substitution rate,THC and CO emissions deteriorated rapidly,while NOx and CO2 emissions decreased;The change of natural gas injection time has no obvious effect on NOx,and the advance and lag of natural gas injection time cause the deterioration of THC and CO.(3)Calculation of specific emission of exhaust pollutants:the calculation results of specific emission of NOx+NMHC and CO in E3 working cycle,diesel mode and dual fuel mode of test engine all meet the requirements of the second stage limit of exhaust pollutants of marine engine which has not been implemented yet..