Measuring the Drying Kinetics and Mass Transfer Coefficients of Hornbeam Wood (Carpinus betulus) from Nooshahar Region

Abstract

In this research, drying kinetics and mass transfer coefficients (permeability and diffusion) of hornbeam wood (Carpinus betulus) from Nooshahar region were investigated. For this purpose, several boards with two nominal thicknesses of 2.5 an 5 cm were prepared from a freshly cut log. The boards were dried inside a laboratory kiln at the dry bulb temperature of 40°C and relative humidity of 50% to the final moisture content of 6%. The pattern of moisture loss, thermal diffusion, final moisture gradient along the board thickness, transverse permeability and diffusion coefficients were then measured. The results showed that by increasing of board thickness, the rate of moisture loss decreased, particularly in the hygroscopic range and the moisture gradient increased, but the thermal diffusion was not affected. The transverse permeability and diffusion coefficient of hornbeam wood was 2.91 × 10 -19 m 2 and 3.29 × 10 -9 m 2s-1, respectively. Overall, it can be concluded that due to low transverse permeability coefficient of hornbeam wood, this species is difficult to be impregnated in common wood preservation process. In contrast, due to low diffusion coefficient, hornbeam wood is recommended for applications where high resistant to water vapor diffusion is required.

Keywords

• Hornbeam wood
• Permeability
• Diffusion
• Drying kinetics