Two Numerical Methods During Hot Pressing And Drying Of Wood

There are a lot of heat transfer process in the wood processing, and the heat transfer process is an important starting point for the mechanism of material changes in the process of research and in recent years, with the continuous improvement of the technology level and the constant introduction of new heating method, microwave heating and more widely used, the research content is more in-depth. In the wood-based panel production process, hot pressing is an important process influencing the quality and yield of product. In the hot pressing process there are a series of complex physical and chemical changes. So the study of the inverse problem has a wide application background.In this paper, we study two kinds of numerical calculation in the processing of wood, one of the kinds is the coefficient and heat source of a kind of linear heat conduction equation, which is a numerical method to solve the inverse problem of heat conduction equation. The partial differential equations and initial boundary value conditions are discredited by using central difference method, and the iterative equations are obtained by using the step method to solve the temperature values on the grid nodes; through the theoretical analysis, it is concluded that this iterative equation is stable and convergent. Then, we use the least square method to construct the error function, the first order partial derivative of the error function is carried out by first order Taylor expansion, and the first order partial derivative is zero, and the Newton iteration scheme is obtained; Finally, we inversion and calculate. As the application of this method, the numerical solution of the heat source of the heat conduction model of the internal temperature of wood in the course of single microwave heating is solved. The numerical results show that this method has a good approximation effect.Then the numerical solution of the specific heat of the heat transfer model of poplar wood plywood with UF resin was obtained by using this method; the numerical simulation results further show that the method has a good approximation effect. So we get a stable numerical solution for this kind of heat conduction equation. The other one is that the numerical model of wood microwave drying is discussed. Firstly, it introduces one-dimensional dynamic model of microwave wood drying process, and analyzes the dynamic properties with numerical methods. Through the stability analysis we know the equilibrium point of the equation is gradually stable which is confirmed by numerical simulation.