Application Of Diesel/Methanol Combined Combustion Technology In Low Emission Generator Sets

In recent years,with the rapid development of internal combustion generator sets,the total amount of exhaust pollutants generated during the work process has gradually increased,and has become a source of power mechanical pollution that cannot be ignored.Today,with the increasingly prominent energy and environmental issues,the development of clean and renewable alternative resources has become an inevitable trend.Methanol is considered as one of the most promising alternative fuels for internal combustion engines due to its wide range of sources,high oxygen content and fast burning rate.The Diesel/Methanol Combined Combustion(DMCC)technology proposed by our research group has proved that it can significantly improve engine thermal efficiency and reduce fuel consumption while effectively reducing engine NOx and PM emissions.However,the research about DMCC technology on generator sets has not been reported in China.Therefore,in order to explore the application of DMCC technology in diesel generators,this study was carried out on a high-pressure common rail diesel engine for a generator set,which was modified to run in Diesel/Methanol dual fuel(DMDF)mode.Then,the characteristics of combustion,emission and fuel consumption of the engine under DMCC technology were studied.And the DMCC technical route meeting the current non-road emission regulations was proposed.Based on the testing results and data analysis above,the following conclusions are drawn:1.Applying DMCC technology to the engine of the generator set can significantly improve the combustion efficiency of the engine.Under DMDF mode,the 75% load,the main engine injection timing is postponed,and the effect of the methanol to extend the retardation period makes the combustion heat release time move backward.The pressure and the average temperature in the cylinder are obviously reduced;the heat release rate of the 100% and 50% load is accelerated,the peak of the heat release rate is increased,and the combustion efficiency is significantly improved;The 25% and 10%load,due to the opening of the pre-injection strategy,methanol participates in the preinjection combustion while shortening the retardation period of the main injection diesel,so that the peak of the main combustion exotherm is reduced.The BSFC of the engine is obviously improved.The methanol replacement ratio under each load is lower than the theoretical replacement ratio,and the BSFC is also lower than the pure diesel mode.But in the 10% load,the BSFC is increased due to the poor replacement.2.In the DMDF mode,pollutants and particulates emissions under various load conditions are significantly improved.In addition to the 50% load,the NOx emissions of other working conditions were significantly reduced;except for the 100% load,the PM emissions of other working conditions were reduced.The HC and CO emissions can be substantially eliminated by using an oxidation catalytic converter(DOC).Because of the small MSP under 100% load and the spontaneous combustion of methanol,so that the amount of particulates are slightly higher than the pure diesel mode.In other load,the particle concentration distribution and the number of particles are greatly reduced.By weighted calculation,the CO and PM weighted emissions in the DMDF mode are lower than the regulatory limits,while the NOx +HC weighted emissions are relatively high.3.After optimizing the fuel injection strategy,the weighted NOx,PM,CO and HC emissions from the DMDF engine for the generator set can meet current non-road emissions regulations.By controlling the injection parameters such as the injection pressure of the engine and the main injection time in the DMDF mode,the emissions and fuel consumption characteristics are comprehensively analyzed to obtain the optimal injection strategy for each load condition,which can reduce pollutant emissions and achieve better Fuel economy.