Multiphysics Simulation Study Of Microwave Partitioned Controllable Continuous Flow Tubular Reaction System

Due to the shortage of primary energy reserves and the deterioration of the ecological environment,the application and development of renewable energy is imperative.Biodiesel has become a focus of attention due to its advantages such as green environmental protection and wide source of raw materials.Microwave continuous flow reactors can reduce esterification reaction time and improve biodiesel yield,making them an emerging equipment for preparing biodiesel.However,the reaction safety and temperature difference of materials during microwave continuous flow heating are still unresolved issues.Therefore,this dissertation designed a microwave continuous flow reactor based on zone controllability to explore the working mechanism and influence rules of materials under microwave continuous heating environment,in order to improve the microwave heating effect in different areas of the cavity.This dissertation coupled electromagnetic fields,laminar flow,and temperature fields,and used multi-physical field simulation methods to numerically calculate Maxwell’s equations,flow field equations,and heat transfer equations.By studying the influence of the shape and distribution of flow components,types of microwave sources,cavity materials,and material types on the microwave heating characteristics of materials in different regions of the cavity,a zoning control method for microwave continuous flow reactors is proposed,and obtained the key factors affecting the microwave zone heating of materials in the reactor.The main research content and conclusions are as follows:(1)Electromagnetic and thermal characteristics of a microwave continuous flow reactor coupled with multi-layer flow elements.The effects of material volume,material spacing,waveguide position,microwave power and material flow rate on microwave energy utilization and heating effect of materials were discussed through multi physical field coupling calculation;The changes in material spacing and waveguide position resulted in asynchronous differences in the microwave heating effect of the double layer materials in the reactor cavity;Increasing the microwave power increased the difference of heating effect of the two-layer materials in the reactor,while increasing the material flow rate or controlling the inflow of materials at a non synchronous flow rate improved this difference.(2)Analysis of influencing factors on electromagnetic thermal characteristics in microwave continuous flow reactors.Exploring the influence of waveguide rotation,material type,cavity material,and wall thickness on the temperature rise effect of materials in different regions as an indicator,it is concluded that vertical feeding of waveguide microwave in a microwave continuous flow reactor can improve the heating uniformity of materials in different regions of the cavity;There were also differences in the direction of waveguide rotation for obtaining the optimal temperature rise effect in different regions of the cavity with different materials;The temperature rise of alcohol oil mixture II was most sensitive to changes in power and flow rate,while the temperature uniformity of methanol was most sensitive to changes in power and flow rate.(3)Electromagnetic and thermal characteristics of microwave continuous flow reactors based on microstrip antennas.A microstrip array antenna that can be used for microwave heating is designed.Through the discussion of the structural parameters and process parameters,the heating effect of materials in different areas in the microwave continuous flow reactor with microstrip antenna as the microwave source is studied.It is concluded that the optimal size of the microstrip antenna array for the materials in the reactor to obtain the best heating efficiency is:the microstrip antenna array mode is 3*2,and the element spacing of the antenna array isλ_w=0.53,the antenna array is located in the center of the reactor,and the antenna substrate thicknessλ_d=0.0943;Compared to the position of the material in the cavity,the effect of material spacing on the microwave heating effect of the material in the reactor is more significant;Increasing the working voltage or reducing the viscosity of materials can improve the heating efficiency of materials,and increasing the flow rate or viscosity of materials can improve the heating uniformity of materials in different regions of the cavity.