Study On Multi-physics Couping Calculation For Microwave Assisted Biodiesel

With the increasingly serious energy crisis and environmental pollution,biodiesel,a new type of green energy,has developed rapidly,and its preparation technology and production process are particularly important.Microwave heating has the advantages of selectivity,rapidity,energy saving,and easy control over traditional heating methods,it has become a hot research topic in industrial applications.However,there is uneven heating during microwave heating,and hot spots and thermal runaway occur when heating certain chemical reactions,resulting in burning of reactants or destruction of reaction generators,or even causing explosions,hindering the widespread application of microwave energy.However,as a common numerical method to study the microwave heating process,multi-physical field coupling calculation and simulation prediction can be carried out for electromagnetic field,temperature field and fluid field involved in the heating process,so as to guide the actual production.Therefore,in this paper,the preparation of biodiesel as the background,the stationary and mixing process of microwave heating biodiesel are calculated respectively by the multi-physics coupling calculation.By analyzing the distribution of electromagnetic field,temperature field distribution,concentration distribution,the experimental measurement results and the variation coefficient of each field,the optimum process conditions of preparation of biodiesel is got,and they are verified by experiments,the experimental results are consistent with the multi-physics coupling calculation results.The optimal conditions of preparing of biodiesel are: the microwave power is 700 w,the ratio of alcohol to oil is 6:1,the reaction temperature is 60.0 ° C,the dosage of catalyst is 2.0% and the mixing speed is 30 rpm.These work will provide certain theoretical guidance for the practical application of microwave energy and the production of biodiesel.The main content of this paper are as follows:(1)The frequency domain-transient one-step solution method is used to couple the electromagnetic field equations,heat transfer equations,fluid flow equations and chemical reaction kinetics The transient physical quantities of the interaction process during the heating process are solved.(2)In the stirring state,aiming at the domain missing problems caused by the geometric model of assembly,the method of using mobile grid technology is proposed to establish the strong coupling calculation model of electromagnetic field disturbance that can reflect the changes of temperature,concentration and position at the same time.(3)The coupling calculation of multiple physical fields was carried out for the process of microwave heating biodiesel under static and stirring conditions.By analyzing the electric field distributions,temperature distributions and concentration field distributions,the optimal process conditions for the preparation of biodiesel were obtained,and were verified by experiments.