Advances in wood drying research and development

Wood drying is a key operation of wood processing to ensure that the wood retains its \nphysical integrity and stability in remanufacturing and in use. However, in industrial drying \nvarious drying defects still occur, which include uneven moisture content between and \nwithin boards, board distortion, residual drying stresses that may induce internal and external checking, and wood collapse. This paper presents a review on advances in wood drying \nresearch and development, which lay foundation for better understanding of the drying \nprocess, mechanisms of drying defect occurrence and affecting factors. In particular, recent \nprogresses in understanding drying stress development and wood collapse formation during \ndrying are presented in more details. Based on these advances, inter-linkage and interactions are analyzed among wood physical and microstructural properties, moisture movement in wood during drying, stress development and reversal, and wood collapse \nformation. Following this, drying schedule improvements and novel drying technologies are \npresented with targets to mitigate the drying defects, reduce energy consumption and \nincrease the productivity. Application of artificial intelligence for modeling and control of \nthe timber drying is also briefly described. Finally, recommendations are made for future \nstudies and practical implementation.