Study On The Laminar Burning Characteristics Of Methanol And Dissociated Methanol

Energy shortage and environmental pollution have become the main restrictive factors of human development.Finding alternative fuels is a simple and effective method to solve this problem.The physico and chemical properties of methanol is similar to gasoline,and the raw materials of producing methanol is extensive,the price of methanol is cheap and the combustion products are also relatively clean,so methanol is an alternative fuel with a good application prospect.As an important basic characteristic of fuel,laminar burning velocity has great significance for studying fuel combustion and verification of chemical reaction mechanism.In this paper,the constant volume combustion bomb experiment system with the schlieren method was used to measure the laminar burning velocity of methanol under the conditions of equivalence ratio of 0.6-1.6,pressure of 2bar-10 bar,and temperature of 368 K and 398 K.Two method is used to dealing the iamge,one is dividing region by threshold value,the other one is edge detection.When extracting the flame radius,random Hough transform method,least square method and equivalent area method are respectively adopted and the results are compared.Dividing region by threshold value and then use equivalent area method to extract radius is more suitable to this paper.Analyzed the influence of initial conditions on the laminar burning velocity of methanol and the instability of flame.Get the conclusion the laminar burning velocity of methanol will first increases and then decreases with the increase of equivalence ratio,increases with the increase of temperature,and decreases with the decrease of pressure.The increase of equivalence ratio and pressure will cause an increase of the instability of flame,and a small change of temperature has almost no effect on the instability of flame.Several mechanisms are use to simulate the laminar burning velocity of methanol based on the Chemkin.The results obtaind by the UCSD mechanism and the Burke mechanism are in good agreement with the experimental data.Use the results of UCSD mechanism and the experimental data to establish a data set,train the data set by machine learning and then get an empirical formula,the empirical formula can be used to predict the laminar burning volocity of methanol under the condition of pressure 1-10 bar,temperature 298K-398 K,and equivalence ratio 0.6-1.6.Simulate and calculate the laminar burning velocity of incompletely dissociated methanol by Chemkin,and analyze the influence of the degree of dissociation on the laminar burning velocity and explore the reasons why the degree of dissociation affects the laminar burning velocity by sensitivity analysis and free radical concentration analysis.The laminar burning velocity increases with the increase of the degree of dissociation,and the increasing of the degree of dissociation will raise the mole fraction of free radicals in the reaction system,so that the burning velocity will be enhanced.