Reaction engineering approach for modeling single wood particle drying at elevated air temperature

Abstract

Abstract In this paper, a semi-empirical drying model for convective drying of a single wood particle at elevated temperature is developed based on the reaction engineering approach (REA). The parameter of this model is determined and verified against both experimental and numerical data. The method proposed to identify the REA model parameter operates as follows: the evolution of the moisture content of a single wood particle over time is measured accurately by using a magnetic suspension balance. A continuum-scale model that takes into account major transport mechanisms relevant to wood particle drying is developed within the frame of volume averaging approach. Continuum model predictions are successfully assessed against the measurements conducted at four different inlet gas temperatures. A set of numerical simulation results obtained at 120\u202f°C is used to deduce the REA model parameter. The fact that the REA model can fairly well reflect the experimental data at higher drying temperatures, i.e. 140\u202f°C, 160\u202f°C and 180\u202f°C, is used to evaluate the accuracy of the REA model parameter. The REA model is also assessed using the continuum model simulations which are obtained for particles of different dimeters (2–20\u202fmm) in a wide range of drying conditions (initial moisture content varies between 0.3\u202fkg water/kg dry solid and 0.6\u202fkg water/kg dry solid and air velocity between 0.005\u202fm/s and 5\u202fm/s). The results indicate that the REA model parameter is insensitive to variations of the drying conditions with an exception of inlet air velocity. The developed REA model can thus be considered as a simple predictive tool for drying of wood particles in a wide range of process conditions.