Study On Microwave Drying Technology And Device Optimization Of Soybean

Soybeans,as the bean variety with the highest nutritional value,are in great demand in China.The newly harvested soybeans cannot be safely stored.It is a very important part to dry the soybeans during the harvest.Natural drying,hot air drying,freeze-drying,spray drying and other drying methods have great limitations.Microwave drying as a new drying method generates a heat source in the material under the action of electromagnetic waves,and the temperature gradient and moisture gradient inside the material can be transferred from inside to outside,which is of high drying efficiency,improving material quality and other advantages.This paper took soybeans as raw material,based on the change of drying efficiency(moisture content),explored the changes of internal observation index water activity and external observation index waist burst rate of soybeans at the same time,in order to find out the process parameters that can effectively improve the drying efficiency in many aspects and do not damage the quality of soybeans at the same time,so as to achieve the purpose of long-term storage.The research can provide data support for the industrial production of agricultural products such as soybeans and lay a theoretical foundation for the optimal design of subsequent microwave drying devices.The main research contents and conclusions are as follows:(1)Characteristic indexes and numerical simulation of soybeans microwave dryingBased on the theory of microwave drying,this paper analyzed the principle and drying characteristics of microwave drying and heating materials,and proved the excellence of microwave in drying soybeans and other materials;The characteristic indexes of the results of microwave drying materials are discussed,each index will be taken as the evaluation standard of drying efficiency and quality of soybeans;Finally,according to the heat and mass transfer mechanism of microwave drying,COMSOL software is used to simulate the electromagnetic field distribution law of soybeans cavity and soybeans itself in the process of microwave drying,and the distribution of soybeans temperature and moisture concentration are obtained,which provide a theoretical basis for the subsequent microwave drying experiment of soybeans,and lay a theoretical foundation for the research of drying efficiency and internal quality of agricultural products.(2)Study on water activity characteristics of Soybeans after microwave dryingBased on the theoretical research of microwave drying,a single factor experiment was designed.Different drying processes were used to dry soybeans.The process conditions of different drying efficiency and water activity of soybeans were obtained in the process of microwave drying.In order to analyze the effects of different process conditions on soybeans water activity(AW)and water content,three mathematical models of exponential function,sinusoidal function and rational function are constructed to describe the results of soybeans microwave drying process.The curve fitting of the results of drying process is analyzed and compared,and finally the curve function that can accurately simulate the drying efficiency and water activity of soybean drying process is obtained,The results can provide reference for the follow-up study on the characteristics of water activity of soybean and the technological conditions for prolonging the storage time of food.(3)Optimization of microwave drying technology of soybeansBased on the theoretical research of microwave drying,a single factor experiment of microwave drying was designed to obtain the influence relationship between different process parameters on soybeans moisture content and waist burst rate,which was used as the basis of subsequent experiments.The microwave vacuum drying experiment was conducted by orthogonal experiment to determine the moisture content and waist burst rate of soybeans at different single drying time,tempering stages and tempering times,and make range analysis to obtain the best drying conditions at this time.At the same time,an improved particle swarm optimization algorithm is proposed.The particle optimization of experimental parameters is carried out with the help of multiple regression mathematical model,and the best technological conditions of soybeans drying are also obtained.Finally,the experiment was designed to compare two groups of different technological parameters,and the experimental results show that the latter is better.The research results are of certain significance for improving the drying efficiency and quality of soybean,and provide theoretical and data support for the industrialized application of soybean microwave drying and soybean deep processing.(4)Design and optimization of microwave drying experimental deviceBased on the microwave drying theory and the above experimental results,an experimental device for microwave drying characteristics of soybeans is optimized by using microwave drying and mechanical design technology.The experimental device is composed of feeding mechanism,air supply mechanism and microwave generator,drying and rotation mechanism.The specific working mode and innovation of the experimental device are described in detail.The vibrating plate is installed in the guiding stage of the device to reduce soybeans adhesion and control the blanking speed;Install the timing switch and set the drying and slow drying area to reduce the cracks in the continuous drying process of soybeans;The exhaust fan is installed to implement microwave hot air coupling drying,recover and utilize the heat energy generated in the microwave drying process,and improve the energy utilization rate and drying efficiency.