Mathematical Modeling of Kiln Drying of Softwood Timber: Model Development, Validation, and Practical Application

Abstract Mathematical modeling of wood drying is a powerful tool to better understand and quantify the effects of wood properties as well as the effects of drying and post-drying treatment conditions on drying and thus the wood drying models can be used to improve drying quality. The models that have been developed can be divided into three categories: models for drying a single board, models for drying a kiln-wide stack, and models for drying stress and deformation. The single-board drying model employs comprehensive heat and moisture mass transfer equations and can be used to investigate the influence of wood variability. The kiln-wide drying model, which is based on the transfer processes between wood and the drying medium, is able to examine the influence of drying schedules and wood properties. The stress model can predict stress development in drying and stress relief in final steam conditioning and post-kiln treatment. An integrated model can be used to optimize drying schedules and develop strategies for high-quality dried timber. Keywords: Board deformationDrying modelDrying stressKiln stackMoisture contentSchedule optimizationSingle board ACKNOWLEDGEMENTS The author thanks Tony Haslett, project manager of Ensis, New Zealand, and Professor Lianbai Gu, Najing University of Forestry, China, for their valuable comments and suggestions in preparing the article.