| With the rapid development of economy and society,energy and environmental problems have gradually become two key issues faced by human beings,which has brought severe challenges to the sustainable development of the automobile industry in the future.The efficient and clean combustion process of internal combustion engine points out the direction for the development of automobile industry in the future.In this paper,based on the constant volume combustion bomb,an experimental study is carried out on the combustion completeness of fuel-air homogeneous mixture under the theoretical equivalence ratio from the point of view of fuel components and thermo-atmosphere.Taking the fuel combustion efficiency as the evaluation index of combustion completeness,the synergistic effect of fuel composition and thermo-atmosphere on fuel combustion completeness is analyzed,and combined with the emission characteristics of fuel,an optimization scheme of fuel components is proposed to improve the combustion completeness of the fuel.At first,the fuel components are chosen by learning about the research results at home and abroad.I choose n-heptane,iso-octane and toluene and mixed them according to their volume ratio at 1:1:1 to get TRF fuel,which is the basic fuel in this experiment.At the same time,toluene,ethanol,ETBE,cyclopentanone,diisobutylene and furan were chosen as additive fuels.Mixed with the base fuel according to the volume ratio of 10%,the optimized fuel components of this experiment are obtained.the final fuel includes the base fuel TRF and six kinds of optimized fuel.As for the boundary conditions of this experiment,I choose the low load area with poor fuel combustion completeness as the optimized object.According to the different fuel components and thermo-atmosphere,the poor fuel combustion completeness under this low load condition is optimized.So,in this experiment,1.6MPa is chosen as the initial inlet pressure and 50? is chosen as the initial inlet temperature.Besides,the homogeneous mixture under the theoretical equivalence ratio is used to carry out combustion and emission study under six groups of uniform steady thermo-atmosphere of 50?,80?,110?,140?,170? and 200?.During the experiment,the pressure and temperature changes of the combustion process in the combustion bomb,as well as the emissions of CO,HC,NOx and PM in the combustion were recorded.Then,after obtaining the data of the experiment,in order to calculate the combustion efficiency of fuel components,this paper discusses the method of combustion efficiency.The method gets the combustion efficiency based on energy balance.Then I establish the calculation model through the analysis of the actual combustion process of mixture in the combustion chamber,and give a complete mathematical description of this method.Then,the mathematical expression of combustion efficiency calculation method based on energy balance is obtained.Furthermore,according to the data of the experiment,the combustion efficiency calculation method based on energy balance and the combustion efficiency calculation method based on emission analysis are compared and analyzed.Then the application effect is discussed.The method of combustion efficiency which are more accurate and reliable is determined.This method can provide theoretical support for the analysis of fuel combustion characteristics.Finally,the calculation method of combustion efficiency determined above is used to analyze the data of experiment.The synergistic effect between fuel components and thermo-atmosphere on the combustion completeness of the fuel is discussed.Combined with the emissions of CO,HC,NOx and PM,the fuel components with good combustion completeness and emission characteristics in a wide temperature range are determined.Finally,an optimization scheme of fuel components is proposed to improve the combustion completeness of the fuel.The results show that:(1)The combustion completeness of the fuel is affected by the combustion thermo-atmosphere.It can be seen that the increase of temperature can promote the oxidation of fuel,so that the fuel has higher combustion efficiency and the combustion completeness of the fuel has been significantly improved.The combustion efficiency of fuel is more than 85% in the temperature range of 170?-200?.Especially at 200?,the combustion efficiency of several fuel components is close to or exceeds 90%.(2)The combustion completeness of the fuel also depends on the difference of fuel components.In the basic fuel,the equal volume addition of toluene and diisobutene can improve the combustion efficiency,and show a good effect under different thermo-atmosphere.When the temperature is 80 ?,the addition of the two fuels increases the combustion efficiency from 75.9% to 82.7% and 84% respectively,while when the temperature is 170 ?,the same change of fuel composition increases the combustion efficiency from 87.9% to 89.9% and 93.4% respectively.The improvement of combustion efficiency of toluene and diisobutene at different thermo-atmosphere shows that toluene and diisobutene have better adaptability to different temperatures in promoting the complete combustion.The two fuels can maintain great combustion completeness in a wide temperature range.(3)For the point of the combustion completeness of the fuel,the equal volume addition of toluene and diisobutene can obviously improve the combustion efficiency,and they show a good improvement in combustion thermo-atmosphere of different temperatures.therefore,they can maintain great combustion completeness in a wide temperature range.However,the fuel component with toluene does not perform well in terms of emission.The NOx and PM emission of toluene is higher than that of other fuel components in different combustion thermo-atmosphere.These make it difficult to become an ideal fuel.With the addition of fuel diisobutene,the fuel has a great performance in CO,HC and NOx emissions,and its addition has an inhibitory effect on the formation of PM.Under different combustion thermo-atmosphere,the mass concentration of the PM emissions has always been maintained in a relatively low range.Therefore,it can be considered that among the several added fuels chosen in this experiment,diisobutene is an ideal fuel component to improve the combustion completeness,which provides a reference for the optimization of fuel components in the future. |
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