Experimental Research On Power And Economy Of Gasoline Engine Based On Fuel Configuration

Gasoline components have a crucial impact on engine performance.The automotive industry mostly focuses on the effects of gasoline components on engine emissions.There is still lack of research on power performance and economy.And there is a problem of fragmentation between the engine and the refinery.Therefore,this article explores the gasoline configuration to fit engine power and fuel economy,and establishes the correlation between gasoline components and the engine,providing a reference for the next stage of fuel standard development.The main content of this article is focused on the following two parts:A self-built 2.0T turbocharged direct injection gasoline engine is used to study the aromatics and naphthene in gasoline.First,the qualitative and quantitative studies of aromatics are performed;Aromatic hydrocarbons with different numbers of carbon atoms and monomers with different numbers of methyl groups were studied by single factor experiments;Define the content range of aromatics and study the different proportions of aromatics(mesitylene).Then,explore the effect of naphthene(cyclohexane)on engine performance and compare with the mesitylene characterized by aromatics to explore the possibility of naphthene replacing aromatics,while reducing emissions of benzene and polycyclic aromatic hydrocarbons(PAHs),and provide evidence for further optimization of fuel configuration.The contents of this part are as follows:(1).The effects of C9~+、C8、and C7 aromatics with different carbon numbers on engine performance were studied.As the number of aromatic carbon atoms decreases,the peak pressure of the cylinder and the peak of the heat release rate increase,and full-load torque of the engine increases.Under low speed and low load,the fuel consumption rate gradually decreases as the number of carbon atoms decreases,and the average fuel saving rate of C7 compared to C8 is 1.49%.(2).Toluene has the highest torque at full load,which is about 4%-5%higher than basic fuel.Mesitylene has a limit torque increase rate of 5.6%.The xylene torque is slightly higher than the base fuel by an average of 2N·m.In terms of fuel economy:The fuel consumption of toluene is reduced by about 4.01%-4.32%compared with xylene,and the average reduction of mesitylene is 3.84%-5.2%compared with xylene.(3).Under full load,as the proportion of mesitylene increases,the peak pressure and heat release rate in the cylinder decrease,and the torque decreases;under low load,a high proportion of mesitylene can advance the combustion start point and shorten the combustion duration,increase combustion constant volume.(4).Under full load,the cyclohexane torque is higher2.5%than mesitylene on average.Under low load,the peak heat release rate and the peak pressure in cylinder are higher than mesitylene,and the combustion duration becomes shorter,improved fuel economy.The ignition advance angle determined by the engine ECU’s self-adjusted knock feedback control system is delayed under large loads,which causes the combustion phase to be postponed,and the peak pressure and peak heat release rate in cylinder are somewhat decline.Based on the experiments conclusions and data analysis methods,for improving the power of high-power engines and economic goals under the common operating conditions(<2400r/min,<100N·m)are proposed.The contents of this part are as follows:(1).In order to improve the fitting accuracy of the experimental data,the full-load torque data of each fuel is fitted by a spline function;The fuel consumption rate of each operating point is fitted by the BP neural network improved by the genetic algorithm,fit correlation coefficient is above 0.99 to verify the reliability of the fit.Under this analysis method,the single factor sensitivity analysis is used to draw the conclusion:a.The sensitivity of dynamics:aromatic monomers with different methyl numbers>aromatics(mesitylene)content>aromatic carbon number.b.Fuel economy:aromatic monomers with different methyl numbers>aromatic carbon number>aromatics(mesitylene)content.(2).Based on the analysis of sensitive factors and the conclusions obtained from experiments,multi-factor collaborative optimization is considered.It is preferred that the component with a fast burning speed and a small molecular weight be combined with other components to put forward a gasoline configuration optimization strategy:Toluene+high alkenes fuel;Toluene+high naphthene fuel;Toluene+xylene+mesitylene mix aromatic fuel to optimize aromatic structure.With the goal of improving engine power and fuel economy under small and medium loads.Conclusion as below:The power of the three fuels are improved compared with the commercially available gasoline.At low and medium speeds,the torque of toluene+high alkenes fuel is increased by 3.6%-4%,and the average operating conditions increase by about2.96%;The average of toluene+high naphthene fuel is increased by about 1.93%;Mixed aromatics fuel is increased about 1.025%overall operating conditions.In terms of fuel economy:In the low-speed and low-load area:the average fuel saving rate of toluene+high alkenes fuel reaches 2.06%;The limit fuel saving rate of toluene+high naphthenic fuel can reach 3.2%,and the average fuel saving rate of low and medium loads is about 1.26%;Mixed aromatics fuel internal fuel saving rate is 1.08%under load of 40%.All three fuels improve fuel economy in low speed and low load areas.