THE USE OF VOLUME-AVERAGING TECHNIQUES TO PREDICT TEMPERATURE TRANSIENTS DUE TO WATER-VAPOR SORPTION IN HYGROSCOPIC POROUS POLYMER MATERIALS

Volume-averaging techniques developed for modeling drying processes in porous materials offer a convenient framework for analyzing vapor sor ption in porous hygroscopic polymeric materials. Because of the large temperature changes associated with water vapor sorption in these mate rials (from 10 degrees to 20 degrees C), sorption/diffusion processes are best characterized through the coupled differential equations desc ribing both the transport of energy and mass through the porous struct ure. Experimental and numerical results are compared for a variety of natural and man-made porous polymeric materials (textiles) using the v olume-averaging technique. Boundary heat and mass transfer coefficient s and assumptions about thermal radiative properties of the experiment al apparatus are shown to influence results obtained with the numerica l solution method. (C) 1997 John Wiley & Sons, Inc.