High Temperature Drying of Wood: Advances in Mass Transfer, Drying Kinetics and Quality Control

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Abstract

High-temperature drying is an advanced wood-drying technology that can reduce drying time and enhance drying efficiency compared with traditional kiln drying. However, moisture flow, drying pressures, machine breakdowns, energy consumption, and environmental issues also pose challenges in the process. This review summarizes the state-of-the-art research on wood drying at elevated temperatures and highlights knowledge gaps that require attention. The main topics include heat and mass transfer methods, moisture transport, changes in mechanical properties, the impact of various drying media, and the role of wood anatomy in influencing drying performance and quality. With a focus on softwood species and high-temperature drying techniques, such as superheated steam and wet air drying, pertinent experimental, numerical, and industrial research published up to mid-2026 was critically assessed. According to the reviewed studies, convective vapour flow is the primary driver of moisture transport at high temperatures, although anatomical features, including density, permeability, and cellular structure, significantly affect drying uniformity and defect formation. Although further advances are required to characterize surface moisture gradients and drying-induced stresses, mathematical models that account for heat, moisture, and pressure transport can predict drying behaviour. This review shows that the best high-temperature drying regimes can considerably reduce drying times without compromising the mechanical properties of the wood. However, high-temperature drying may result in collapse, internal stresses, surface and internal checks, and other quality defects. Superheated steam drying offers higher drying rates and energy efficiency than conventional drying but can lead to higher emissions and greater moisture variability if not properly controlled. Pre-treatments and conditioning phases are effective in minimizing drying strains and improving moisture uniformity. This analysis identifies future research opportunities to develop sustainable, energy-efficient and high-quality wood-drying technologies and offers practical suggestions for improving the high-temperature drying process in industry.

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