cell walls. In the drying processes, only free, bound
and vapor phase water are removed. Evaporation occurs
through e7ective liquid/vapor sorption isotherms
and complex transport phenomena, such as free water
capillarity, surface di7usion of bound water and di7usion
and convection of water vapors. The role played
by moisture transport phenomena is dependent on the
heating conditions. Extensive literature on slow drying
(temperatures below the normal boiling point of water),
carried out for applications in the timber industry
and aimed at the achievement of structural wood stability
from the green condition, indicate (for instance
[2,3]) that free water capillarity and di7usion of bound
water play a controlling role, with liquid-phase Cows
two or three orders of magnitude larger than the vapor
Cuxes.
bound water which is hygroscopically held by the cell
walls, water vapors in the void space and, nally, constitutive
water in the chemical composition within the