Thermal modelling of the high temperature treatment of wood based on Luikov's approach

Abstract

SUMMARYA 3D, unsteady-state mathematical model was used to simulate the behaviour of wood during high temperature treatment. The model is based on Luikov's approach and solves a set of coupled heat and mass transfer equations. Using the model, the temperature and moisture content profiles of wood were predicted as a function of time for different heating rates. Parallel to the modelling study, an experimental study was carried out using small birch samples. The samples were subjected to high temperature treatment in a thermogravimetric system under different operating conditions. The experimental results and the model predictions were found to be in good agreement. The results show that the distributions of temperature and moisture content are influenced appreciably by the heating rate and the initial moisture content.

Examining the Suitability of the Reaction Engineering Approach (REA) to Modeling Local Evaporation/Condensation Rates of Materials with Various Thicknesses

“…The REA shown in Eq. (12) serves as the local evaporation rate. The mass balance of water in the vapor phase (water vapor) is expressed as [42,43,45,63] @C…”

“…[10][11][12][13][14][15][16][17] Diffusion-based models usually implement effective diffusivity to lump several phenomena during drying, including liquid diffusion, vapor diffusion, capillary flow, and evaporation=condensation. Effective diffusivity was reported to be generated from several sets of experiments followed by optimization procedures in order to establish the effective diffusivity as a function of temperature and=or moisture content.…”

“…[10] This approach was used by several researchers to describe several drying processes and a good agreement with experimental data was shown. [12,20] Nevertheless, the coefficients need to be generated from several sets of experiments followed by optimization procedures.…”

Comparison of different models for the high-temperature heat-treatment of wood

“…The time step was 360 s. In the simulations, the computation time for a typical run was 16 minutes. The details of the model are given elsewhere [16,17]. The thermophysical properties and parameters of the model used in the simulations are shown in Tables 1 and 2.…”

Some investigations on moisture injection, moisture diffusivity and thermal conductivity using a three-dimensional computation of wood heat treatment at high temperature

“…Younsi and coworkers showed the necessity of solving Navier-Stokes equations in the surroundings of the wood sample in order to get more information about the boundary conditions for the transport equations in the medium and then solve the complete thermal problem [25,32,33]. In order to analyze the conjugate problem of heat and moisture transport in wood, the authors used the classical Luikov model [28] for the numerical formulation of the problem in wood part [34,35]. Moreover, Sanga et al [36] solved the diffusion model for transient heat and mass transfer processes to analyze the drying of a shrinking solid surrounded by a non-shrinking material using microwave energy.…”