The Drying Kinetics and Equilibrium Moisture Content of MDF Fibers

Abstract

An experimental device was constructed to study the drying kinetics of wood fibers under controlled conditions. The device consisted of a drying chamber in which a net basket filled with the fiber material was connected to a load cell. The drying medium was then forced through the basket at controlled levels of humidity and temperature.Experiments were performed with spruce fibers and the drying medium at varying temperature (50-170 C) and relative humidity (1-86%). In general, the drying rate increased with increasing temperature and decreasing relative humidity. A constant drying rate period was observed in all cases. The critical moisture content was approximately 1.25. The characteristic drying curve has a slight downward concave shape. The equilibrium moisture contents obtained at ambient temperature agree well with data in the literature.

Drying Kinetics of Poplar (Populus Deltoides) Wood Particles by a Convective Thin Layer Dryer

“…An increase in the air temperature and air velocity resulted in an increase in the drying rate and consequently a decrease in the drying time. Previous studies have reported similar trends (Ertekin and Yaldiz, 2004;Fritzell et al, 2009;Ghazanfari et al, 2006). As can be seen, drying rate at the initial stage of the drying period is rather low, which may be due to the activation energy and increase of the temperature of wood water content.…”

Mathematical Modeling of Heat, Mass, and Momentum Transport in MDF Fiber Drying

“…Because the particle diameter studied is small and a simple drying model is desired, the drying rate in the falling drying rate period is assumed to decrease in a linear fashion. Fritzell et al [12] concluded that the characteristic drying curve of MDF fibers was only slightly concave downwards. A linear approximation would therefore be justified.…”

“…The critical moisture content, X c , was set to 1.25 [12] and the equilibrium moisture content was evaluated according to Eq. (17) [12] …”

“…The model is numerically solved using the Ansys-CFX 11.0 (Canonsburg, PA) commercial CFD code and a two-fluid Eulerian model. Drying kinetics and moisture equilibrium data from Fritzell et al [12] were used as input to the drying model. The relative humidity of the air and temperature profile were validated using experimental data obtained from Pang.…”

Heat of sorption: A comparison between isotherm models and calorimeter measurements of wood pulp

“…Further isotherms models [11] for pulp commonly reported in the literature, but not used in our work are the Halsey equation [23] , Smith equation [24] , Simpson Rosen equation [25] , Hailwood Horrobin equation [26] and Iglesias equation [27] .…”