Based On The Simple Algorithm For Air Drying Of The Coupling Field And Numerical Simulation

Gas flow drying is an approach of convective desiccation. Firstly the heated gas enters into the equipment; the material which needs for being dried is transported by the hot gas. Then the convection is taken place during the whole procedure. Therefore, the moisture will be evaporated away due to the heat transfer. Finally the drying purpose is achieved.According to the heat and mass transfer phenomenon in the pneumatic drying, it is a complicated multiphysics problem. The exchange of heat and mass between the gas flow and the material is carried out during the conveying process. The material which contains the moisture obtains the heat from the hot gas and the temperature will rise. When it achieves the evaporation point, the water will change the phase form liquid to gas and is combined with mixture hot gas. Thus, the particle mass and humidity will decrease. At the same time, the humidity of hot gas will increase and its temperature will go down. All of this will certainly change the pressure, velocity, density, diffusion coefficient and concentration of the fluid field. And this kind of change will definitely influence the water evaporation phenomenon again.The SIMPLE algorithm was originally put forward by Patankar and Spalding. It was traditionally employed as a numerical scheme to solve the heat transfer issue of the single phase flow. In the recent years, this numerical method has been further developed to solve the multiphase flow by Crowe etc. In this algorithm, pressure field is considered as an important factor of determining the velocity field. Then the velocity field will affect other scalar variables, like temperature, moisture, concentration etc. The calculated temperature, moisture, concentration will turn back to affect the density, diffusion coefficient etc. And these parameters will also change the pressure, velocity field. Therefore, solving the fluid flow problem by this algorithm is an iterative procedure and finally it achieves convergence.The theoretical models of the numerical simulation are introduced in this article to describe the multiphase flow. According to the disperse phase model, the numerical method based on the SIMPLE method is used and successfully solve the multiphysics of straight pipe pneumatic drying. Based on the above work, the numerical simulation of the swirling drying system has been done to verify the feasibility of the new system. The research work of the paper relates to some subjects like computational fluid dynamics, pneumatic conveying, multiphase flow and computational engineering. It would be guidance for the numerically solving multiphase flow problem and reference to the industrial drying applications...