Secado De Madera Al Vacío

THE DRYING OF RED OAK AT VACUUM PRESSURE(



Agustín Pérez Ricardez[1], Juan Rivera Suárez1 , Luis Aviña Berumen[2]





ABSTRACT

The defects can be reduced, compared to that oftraditional drying, by vacuum drying of red oak. In this work we present a mathematical model to predict the red oak wood drying kinetics. The mathematical model considers molecular diffusion andtwo-dimensional flow of humidity. The experimental work was carried out in controlled conditions of temperature and relative humidity to estimate the effective diffusion coefficient and moisture content inthe wood. An "Arrhenius" type expression was employed for temperature dependence of diffusion coefficient.

Key words: diffusion, red oak, vacuum pressure, wood drying

INTRODUCTIONTraditionally, the drying sequences for soft wood are used for the drying of hard wood, that which generate defects in the wood, like cracks, fissures, warped and diamond form, reducing the commercial valuein the wood (Pérez et al., 2001). The wood hard drying at vacuum pressure is an alternative not much studied, to eliminate defects in controlled conditions, obtaining quality wood (Pérez et al.,2003). It is attractive to dry thick wood at vacuum pressure, where the drying time using conventional methods, it is increased in an exponential form (Keey, 2000; Pérez et al., 2000). This work presentsan extension of the traditional drying models, to predict the lumber drying kinetic of red oak with square traverse section at vacuum pressure. This model assumes diffusive control as well asbidirectional moisture flow, equilibrium conditions in the entire sample surface at the drying chamber conditions and variable diffusion coefficient in the whole range of the content of humidity in the woodand residual humidity.

THEORY

We were considered a square structure for the samples and the physical structure, those which had the next dimensions: 0.3m*0.04m*0.05m, for this reason we...