Equilibrium thermodynamics of wood moisture revisited: presentation of a simplified theory
2016
Willems, Wim
The equilibrium moisture content (EMC) of a wood specimen is known to be a function of the (absolute) temperature T and humidity h of the environment. In the present paper, it is directly derived from equilibrium thermodynamics that EMC is more specifically a function of the water chemical potential μ=RT ln h (Polanyi’s postulate). It is shown that wood moisture thermodynamics then becomes considerably simplified, allowing the calculation of the energy of wood-water interactions from the data of a single-temperature moisture adsorption. A critical comparative analysis on the theoretically calculated adsorption enthalpy and published data, obtained from isosteric and calorimetric measurements, is given. It is deduced from the theory that all bound moisture is non-freezing and that the heat capacities of bound and free wood moisture are equal.
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