Modeling moisture and heat transfer during superheated steam wood drying considering potential evaporation interface migration

Abstract

In the present study, a mathematical model with a moving evaporation interface was constructed to quantitatively assess the mechanisms of moisture and heat transfer during superheated steam wood drying. In this model, the unsaturated Darcy flow of free water was considered as Fick diffusion. By modeling the interface evaporation rate and volume evaporation rate, the model (1) characterized the moving water evaporation interface; (2) quantified the dynamic alterations of wet/dry regions; and (3) predicted the change regularity of real-time temperature, moisture content, interface evaporation rate, volume evaporation rate, vapor density, and relative humidity at specific locations during the wood drying. Compared with the superheated steam drying experiments using camphorwood (Cinnamomum camphora (L.) Presl) and teak (Tectona grandis L.f) specimens in different sizes, it was suggested that the developed model was able to accurately predict their drying processes, and the parameters calculated from the model contributed to the optimization of a superheated steam drying technique for teak.