A comprehensive mathematical model of heat and moisture transfer for wood convective drying

Abstract

The focus of this study is the development of a specific drying model for the design and operation of drying systems for stacked lumber in drying chambers. Namely, a comprehensive three-dimensional (3D) mathematical model of heat and moisture transfer in stacked wood has been developed, where the wood was subjected to convective drying that accounts for the effect of the surrounding fluid flow. In developing the model, the characteristics of wood and fluid flow, i.e. velocity, pressure, temperature, relative humidity (RH) and moisture content (MC) are described by the conservation equations of mass, momentum and energy as well as thermodynamic relations. The model presented was solved numerically by means of the commercial software COMSOL Multiphysics. The simulation results were validated against experimental data under laboratory conditions. Air current circulation was found to be non-uniform during drying, which accounts for the different rates of temperature and MC in wood. At the initial stage of drying, this difference was relatively large but reduced gradually with the drying process. Meanwhile, the transient gathered phenomenon related to humidity around the stacked wood in the chamber was observed in response to air current circulation and evaporation rate of moisture. Finally, sources of error incurred in numerical calculations and actual detection were identified and discussed.

Моделювання Розподілу Вологості В Процесі Кондиціювання Термічно Модифікованої Деревини Ясена

“…Мета роботи -розроблення математичної моделі розподілу полів вологості за товщиною термічно модифікованої пилопродукції деревини ясена в процесі кон- Аналіз останніх досліджень та публікацій. Різні наближені математичні моделі, такі як модель дифузії Фіка, модель градієнта тиску пари, модель Ликова, Siau модель і модель Watiker використовуються для опису форм переміщення вологи в деревині в процесі сушіння [8,13]. Серед цих моделей тільки модель дифузії Фіка застосовують за ізотермічних умов [7], модель градієнта тиску і модель Ликова використовує водяний потенціал як рушійну силу, Siau модель розглядає хімічний потенціал як рушійну силу [19].…”

Two-dimensional simulation of mechanical stresses during isothermal drying of Eucalyptus nitens wood

“…However, an approximate model for drying above FSP can be used defining an effective diffusion coefficient (Cheng et al 2007), as a model implemented for the drying of softwoods (Salinas et al 2015;Acuña et al 2018) and hardwoods (Sepúlveda et al 2016). Works on a multi-physical approach have also been developed by Zhao and Cai (2017) and Etemogly and Turkan (2019).…”