EQUILIBRIUM MOISTURE CONTENT OF CELLULOSIC MATERIALS AT HIGH TEMPERATURE

Abstract

ABSTRACT At the high drying rates now obtainable in high intensity drying; solids may reach quite high temperatures for very short drying times. Frequently the temperature stability of solids precludes measurement of their adsorption equilibrium moisture content at these elevated temperatures. A thermodynamic method is presented for calculating equilibrium moisture content at high temperature from measurements made at low temperature. The method, based on Gibbs surface excess free energy theory, involves no parameters requiring experimental measurement and eliminates the need for empirical extrapolations. Although demonstrated for three fibrous cellulosic materials, viscose yarn, cotton and kraft wood pulp, the procedure is applicable to any absorbent - water system. The examples show that the method is practical and convenient for application.