Water Vapor Transport Through Textiles and Condensation in Clothes at High Altitudes—Combined Influence of Temperature and Pressure Simulating Altitude

Abstract

A new apparatus is developed to measure the Water vapor permeability resistance of textiles with and without temperature differences imposed on both sides of a specimen. Water vapor resistance is measured for a combination of temperature and pressure that simulates elevated altitudes. The effect of temperature on water vapor resistance is small. while that of pressure is significant, that is, water vapor resistance decreases with increasing simulated altitude due to an increase in the water vapor diffusion coefficient with increasing altitude. The amount of condensation in the specimen tends to increase with increasing simulated altitude. Moreover, water vapor resistance decreases apprecia bly due to increased condensation in the specimen. In addition, the reduced resistance further enhances the amount of condensation. These results indicate that decreased water vapor resistance enhances condensation in clothes and thus may cause further discomfort and a drop in body temperature at high altitudes.

A simple theoretical model of heat and moisture transport in multi-layer garments in cool ambient air

“…The analysis presented in this paper, together with similar analyses published previously by Lotens, et al (1995) and by Fukazawa, et al (2003a), establish a rational basis for analyzing heat and water vapour transport with condensation in a cool garment. In the simplest condition, moisture condenses on the cool inner surface of an impervious outer garment, where latent heat carried by water vapour is converted to sensible heat which is transferred by conduction, convection, and radiation to the environment.…”

“…Lotens, et al verified the essential correctness of their model by showing that computed results were in substantial agreement with three sets of data for human subjects who performed both light and heavy exercise while wearing either a semi-permeable or an impermeable outer garment. Fukazawa, et al (2003b) validated their model by showing that calculated mass fluxes were in good agreement with fluxes measured in a flat-plate apparatus (Fukazawa, et al, 2003a). Temperature, water vapour pressure, and total pressure (which affects the resistance to mass transfer) were varied over a considerable range of conditions.…”

Benchmarking Functionality of Historical Cold Weather Clothing: Robert F Scott, Roald Amundsen, George Mallory

“…The altitude influences the clothing performance in two ways. Firstly there is the effect of altitude on clothing properties [2,3] and secondly the effect of altitude on sustainable activity levels [4].…”

Heat and water vapour transfer of protective clothing systems in a cold environment, measured with a newly developed sweating thermal manikin

“…Note that the comfort threshold of the skin wettedness is 0.6 for these experimental conditions Fig. 4 Experimental condensation mass fluxes are plotted versus the calculated ones using the analytical equation by Fukazawa et al (2003bFukazawa et al ( , 2003c. Good agreement is obtained between experiment and analysis In order to estimate the condensation rate in clothes, and Lotens and Pieters (1995) presented a set of heat and mass balance equations and solved it numerically.…”

“…Good agreement is obtained between experiment and analysis In order to estimate the condensation rate in clothes, and Lotens and Pieters (1995) presented a set of heat and mass balance equations and solved it numerically. More recently, Fukazawa et al (2003bFukazawa et al ( , 2003c derived an analytical equation for the condensation rate in clothes, enabling the amount of condensation to be calculated from given conditions of body surface area, clothes and environment. In Fig.…”