Study of Kiln Drying Process of Lumber- The Effect of OptimumSide Gap on Uniformity of Final Products

The main objective of this work is to obtain accurate predictions through numericalsimulation models towards an optimum drying process of lumber with special focuson ۱۰۵×۱۰۵ mm western hemlock planks. The practical objective is to study theeffect of previously suggested side gap between adjacent boards at different airvelocities (Re numbers). A Fortran program is developed to solve the twodimensional coupled heat and mass transfer equations inside the wood during thedrying process. The model considers the changes in air temperature and humidity dueto heat and mass transfer to and from the upstream wood surfaces. The iterative SOR(Successive Over Relaxation) method is modified to increase accuracy and stability.Predictions for drying curves and temperature are in good agreement with experiments.The effect of different side gap on the drying process is also examined. Comparisonbetween plots of statistical parameters for different side gaps is carried out forjudgment about the uniformity of the products. Results indicate that without using theextra gap size there exists a considerable difference between the maximum andminimum final average moisture content of the boards in each row. Based on theuniformity of moisture content in final products, it was concluded that the suggestedvalues, by current author, for optimum side gap at each Re number can obtain the bestuniformity of final products.