Microwave Biological Coupling Law And Thermal Effects Based On Poplar's Different Texture Direction

In modern society,people live in the ocean of the electromagnetic wave.The microwave electromagnetic field is widely used in the communications,medical treatment,food processing,chemical pharmacy and material processing.Electromagnetic waves can bring convenience to people's life,but also bring harms.The electromagnetic wave as a kind of high frequency electromagnetic wave that interacts with the polar molecules in the human body when the body is radiated by the microwave,which causes the polar molecules to move in the direction of billions of times for per second,and then produce a lot of heat to injure one's body.However,electromagnetic wave can also improve our lives if we can make good use of it.Microwave has many characteristics,such as selective,adjustable frequency,adjustable power and others,that can help us to selectively kill cancer cells which in the human body and restore the health of the human.However,the interaction between the electromagnetic wave and biomass is very complex,due to the phenomenon of interference and diffraction of the electromagnetic waves.There is less research for the law of the interaction between the electromagnetic wave and biomass,therefore,it is necessary to explore the biological effects of microwave,which can provide useful theoretical basis for the use of microwave radiation and protection.This paper takes the poplar as the object for research,to explore the principle of interaction between electromagnetic wave and organisms.Two methods have been used on this basis,such as experimental research and finite element analysis to study the uniformity of temperature distribution of the microwave wood drying and the law of the interaction between microwave and organisms.The microwave energy is so high to form local high temperature in poplar,that easy to cause partial carbonization,and lead to the phenomenon of low quality and cracking of wood drying.Therefore,it's necessary to explore the uniformity of temperature distribution of microwave wood drying.In this paper,the temperature distribution uniformity of microwave poplar drying was studied from three aspects.(1)Two methods of finite element analysis and experimental are used to explore the law of temperature distribution of the inner polar,the loss of moisture and the utilization efficiency of energy based on the direction of microwave radiation along the wood texture.The research shows:? When the direction of microwave electromagnetic field is parallel to the direction of wood texture,the wood have showed the most uniform heating,the best temperature distribution uniformity and the highest microwave energy utilization.? The internal moisture transport channel of wood can quickly open up by the method of longitudinal feeding,which can improve the efficiency of the drying process and save energy.? It is consistent of the results by finite element analysis and experimental exploration method,although the wood is anisotropic,the finite element method can simulate the temperature distribution of poplar during microwave drying process to be closer to the true value.And finite element analysis makes the research results more intuitive visualization to provide a theoretical basis the latter study.(2)The theoretical calculation and finite element method is adopted to explore the change of microwave penetration depth and microwave energy utilization with the increasing of moisture content of polar when microwave direction is parallel to wood grain direction.The research shows:? The penetration depth decreases with the increase of the moisture content of polar.When the moisture content of poplar wood increased from 30%to 110%,the penetration depth of microwave with 2.45 GHz decreased from 22.30 cm to 3.64 cm,and the penetration depth microwave with 0.915 GHz decreased from 60.32 cm to 9.85 cm.The results provides theoretical guidance for microwave drying.? Meanwhile,the internal temperature uniformity of poplar wood became worse after the water content increased.In order to improve the uniformity of the microwave drying of the wood,the thickness of the wood should be within the range of the microwave penetration depth during the drying process.(3)Two methods of the finite element analysis and experimental investigation are used to investigate the temperature distribution uniformity of poplar in different positions in the microwave cavity.The research shows:It is found that the experimental results of the temperature distribution uniformity in different positions of microwave resonator are consistent with the results of finite element simulation.When the poplar is placed in the center of the microwave cavity or in the back of the cavity,it can make better temperature distribution of the wood,quickly the moisture content reduced of the wood,and high quality drying effect.