Coupling effects of steady-state heat and water vapor transfer through fabrics

Abstract

In order to measure thermal and water vapor resistance of fabrics under non-isothermal conditions, the sweating guarded hot plate was modified. A nitrogen stream was used to sweep the water vapor away. The water vapor flux across the sample was determined by detecting the relative humidity of the outgoing nitrogen stream. The water vapor resistance was then calculated first. The dry heat loss for calculating thermal resistance was obtained by subtracting the evaporative heat loss from the total heat losses. The thermal resistance was determined accordingly. The thermal and water vapor resistance values of four fabrics were determined simultaneously by this test method. The results indicated that the total and intrinsic thermal resistance values of four fabrics measured in the presence of water vapor transfer were lower than those obtained without water vapor transfer. In addition, the total and intrinsic water vapor resistance values obtained under the non-isothermal condition were higher than those under the isothermal condition. © 2014, SAGE Publications. All rights reserved.