| With the depletion of oil resources,the development of new types of clean and renewable energy has become a new research trend and hotspot.Vegetable oil,as a substance that can be burned,its composition determines that the impact of vegetable oil on the environment is far less than the existing fossil fuels.Most importantly,vegetable oil is derived from plants,and most plants can be processed to obtain vegetable oils.The advantages of a wide variety of sources and renewable make it worthy of being studied.This paper selects the tung oil,a common non-edible vegetable oil in China,as the study object.The micro-emulsification technology is used to prepare the mixed fuels of vegetable oil,diesel oil and ethanol at different proportions,and the differences in physical and chemical properties are determined.Through the combination of spray test and numerical simulation,the spray characteristics of different proportions of vegetable oil and ethanol mixed with diesel oil were studied.Through the spray characteristics test,the penetrating distance,spray cone angle,Soot mean diameter and characteristic diameter of the prepared four kinds of micro-emulsion fuels and diesel fuels were evaluated respectively.The results showed that the penetration distance of the micro-emulsion fuel was greater than Diesel,spray cone angle is less than diesel.The number of droplets with larger diameter after atomization is larger than that of diesel.The average diameter of Sauter is also larger than that of diesel.Therefore,the atomization effect is not as good as that of diesel.Based on the measurement results,different proportions of tung oil and ethanol are separately added to the micro-emulsion fuel.Effect on atomization.The simulation part first introduced the basic concepts,methods and principles of computational fluid dynamics.Then the multiphase flow model and the turbulence model were used to simulate the flow process in the injection hole.The results showed that the pressure of the five fuels at the injection hole was rapidly reduced.The velocity first increases sharply and then slowly decreases.In the flow process,the five fuels will have different degrees of cavitation.Five kinds of fuel outlet velocity,liquid volume fraction and mass flow rate are calculated as the fog.The initial conditions of the field simulation.The atomization process of the spray in air was simulated using the discrete phase model.The simulationresults of penetration distance and Socket mean diameter of the five fuels were obtained.The simulation results were basically consistent with the experimental results and proved that the simulation model was established accurately,and based on the simulation results,the changes of the velocity of the five fuel droplets in the fog field were analyzed.This study shows that the use of micro-emulsification technology can effectively reduce the disadvantages of vegetable oil as a fuel with too high viscosity,but the spray characteristics test results and simulation results show that the atomization effects of the four micro-emulsion fuel blends are not as good as the diesel atomization effect.Comprehensive macro and micro spray characteristics evaluation parameters concluded that the atomization effect of TD30E20 is closest to diesel. |
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