Optimized Study On Structure And Process Parameters Of Wood Drying Kiln With Combined Steam Dehumidification

Wood drying is an important process for improving the physical and mechanical performance of wood, and for raising utilization ratio of wood resources. Structure requirement of wood drying equipment and the complexity of the changes of process parameters make the researches and improvement of wood drying system become more and more complicated. Therefore, a feasible structure of wood drying equipment and a new computing method of process parameters are desperately needed to adapt to this change.In the process of drying, the uniformity of wind speed is the main parameter to guarantee wood drying. To solve the problem of the uneven distribution of the internal wind speed of wood-drying kilns, the author tries to improve the uneven distribution of wind speed by optimizing wood drying kiln’s structure and process parameters to guarantee a better airflow circulation with which timber of good quality can be produced, and the basis for the production of wood drying can be provided.Having analyzed the influence of various factors of the internal drying system on the quality and efficiency of wood drying process, the circulating mode of wood drying medium and thermal-mechanical coupling equation and fluid-structure interaction equation of drying system were obtained. Based on the analysis of multiple field coupling problems and boundary conditions of wood drying kilns, with the drying kiln model established with Fluent software, the rules of the distribution of the internal wind speed were obtained and the distribution of wind speed was improved by optimizing deflector’s angle, physical dimension and process parameters.Perturbation stochastic finite element method was used to optimize the deflector’s angle, and the optimized wind speed trace map was attained with CFD technology. The results showed that the wind speed of the gap gradient of wood piles of each layer was basically the same.With GA(genetic algorithm) used to establish target function of the system, and weighting factors adopted to show the influence of each factor on the wind speed of drying process, physical dimension of wood drying kilns and drying process parameters were optimized for better wood drying. After resetting the initial parameters of the optimized system model, wind speed cloud chart of circulating medium was obtained by simulation. The simulation results showed that the flow uniformity of the circulating medium was improved, which verified the reasonableness of the optimized physical dimension and process parameters.Through simulation analysis, and the comparison of experiment data, it comes to the conclusion that the wind speed distribution uniformity of internal flow field of wood-drying kiln was improved and the moisture content difference of interior and surface layer was relatively small after the installation of the deflectors at an appropriate angle, the restructuring of physical dimensions of kilns and the changes of drying process parameters. The data provide the basis for improving the quality of wood drying, which shows a great prospect for industrial applications.