Development Of Combustion Analysis System And The Performance Study On Methanol-gasoline Dual Fuel Engine

“Energy crisis” and environmental contamination have been the hot issues nowadays as well as the primary problems for the industry development of the internal combustion engine.A relative better approach to these problems is to develop novel alternative fuels.The methanol is regarded as one of the desirable alternative fuel because of cheap price、high oxygen content and fast flame propagation properties.The combined injection mode of methanol inlet injection and direct injection in gasoline cylinder can better realize the mixed combustion of methanol and gasoline.While the combustion analysis system enables the real-time in-cylinder pressure measurement and the combustion process analysis,which is an important proof for of the research and development of the composite injection system.Hence,taking methanol/gasoline dual fuel engine as the research object and combining the characteristics of dual fuel engine,this paper developed a set of cylinder pressure data acquisition and combustion analysis system suitable for dual fuel engine,so as to study the performance of the methanol/gasoline dual-fuel engine.By comparing the method of combustion heat release rate calculation,the calculation of combustion analysis conducted by indicator diagram was clarified in this work.Conducted on the Lab VIEW software platform,the combustion analysis system was developed through the existing experimental equipment.The important attributes of the hardware were taken as the input parameters of the software so that the software input parameters could be modified to achieve the adaptation with the hardware.Data acquisition sub-VI was used to realize the function of acquiring and processing the data,and program reuse was realized to the maximum extent.The midline compression method was used to calibrate the upper and lower dead points,and Lab VIEW and MATLAB were combined to process the iterative calculation of a large number of data.According to the calculation principle of combustion heat release rate,combustion parameters like combustion heat release rate,burning temperature,CA50 and some other ones were computed by combining the different low calorific value and circulating oil supply of dual fuels,and the applicability of the system was verified through experiments via the developed combustion analysis system.In order to explore the influence of methanol-gasoline dual fuel on engine performance,a simulation model was built based on GT-POWER,and a computational model was verified by using the data collected by the combustion analysis system developed in this paper.The research showed the following results: with the increase of MPI ratio,the peak cylinder pressure increased,the corresponding crankshaft turning angle was advanced,and the combustion duration gradually reduced.With the increase of ignition advance angle,the internal combustion heat release was advanced,the combustion duration decreased,and the flame development period decreased at first and then increased.With the increase of excess air coefficient,the peak cylinder pressure decreased under different MPI ratios,the dynamic performance decreased,and the economy improved slightly.Under different loads,with the increase of MPI ratio,the equivalent specific fuel consumption decreased.In the compound injection mode,the injection of methanol into the inlet could effectively improve the incylinder combustion and reduced the fuel consumption.