Effect of Optimum Side Gap on Uniformity of Final Lumber Products During Kiln DryingProcess

The main objective of this work is to obtain accuratepredictions through numerical simulation modelstowards an optimum drying process of lumber withspecial focus on ۱۰۵×۱۰۵ mm western hemlock planks.The practical objective is to study the effect ofpreviously suggested side gap between adjacent boardsat different air velocities (Re numbers). A Fortranprogram is developed to solve the two dimensionalcoupled heat and mass transfer equations inside thewood during the drying process. The model considersthe changes in air temperature and humidity due to heatand mass transfer to and from the upstream woodsurfaces. The iterative SOR (Successive OverRelaxation) method is modified to increase accuracyand stability. Predictions for drying curves andtemperature are in good agreement with experiments.The effect of different side gap on the drying process isalso examined. Comparison between plots of statisticalparameters for different side gaps is carried out forjudgment about the uniformity of the products. Resultsindicate that without using the extra gap size there existsa considerable difference between the maximum andminimum final average moisture content of the boardsin each row. Based on the uniformity of moisturecontent in final products, it was concluded that thesuggested values, by current author, for optimum sidegap at each Re number can obtain the best uniformity offinal products.