Modeling of heat and mass transfer during high temperature treatment of aspen

A three-dimensional and unsteady-state mathematical model, which accounts for simultaneous heat and mass transfer taking place during the high temperature treatment of wood, has been developed. It was validated by comparing the predictions with the experimental data. In the model, the coupled heat and mass transfer equations proposed by Luikov are solved, and the temperature and moisture content profiles within wood are predicted as a function of time for different heating rates. For the model validation, an experimental study was carried out with aspen under different operating conditions. The samples were heated to high temperatures using a thermogravimetric system. The weight loss and the temperature distribution within the sample were monitored and registered during the experiment. The model can use constant or variable thermo-physical properties. The temperature and moisture content of the wood predicted by the model using variable properties were compared with those predicted by the same model using constant properties as well as with the experimental data. The experimental and model results are in good agreement, and it was shown that the accuracy of the model depends on the accuracy of the properties. After the model validation was completed, a parametric study was carried out.