Prediction of the water evaporation rate of wet textile materials in a pre-defined environment

Abstract

Purpose The water evaporation rate (WER) is not only crucial for fabric drying, but also an important parameter affecting cooling from a body wearing sweat wetted clothing. The purpose of this paper is to predict the WERs of wet textile materials in a pre-defined environment. Design/methodology/approach The maximum water evaporation rate (WERmax) from a saturated surface in a pre-defined environment was first predicted based on the Lewis relationship between the evaporative and the convective heat transfer in this paper. The prediction results were validated by the comparisons with experimental measurements in various environments obtained in this paper and reported in the literature. Findings Experiment results show that the ratios of WERs to WERmax are lower than 100 percent but higher than 50 percent, which confirmed that the prediction of WERmax is reliable. The temperature decrease of the wet material surface due to evaporation was considered to account for the difference between measured WERs and the WERmax, and the WER variation among materials. The lower ratios of WERs to WERmax in the higher wind condition were speculated to be due to the greater temperature decrease caused by the increased evaporation. Practical implications It provides a reliable way to obtain both WERmax and WER (WERmax multiplied by a proper ratio), which can be useful in clothing physiological modeling to predict clothing comfort. Originality/value This study contributes to the understanding of the evaporation process of textile materials.

Vapor-sorption Coupled Diffusion in Cellulose Fiber Pile Revealed by Magnetic Resonance Imaging

“…For example, for the experiments for which this characteristics distance ( ) is 8 mm, the tangential air flux velocity at about 1 cm above the sample is of the In practice, textile drying occurs under a variety of conditions. In laboratory, the evaporation properties may be studied under some ambient humidity without controlling precisely the air flux [5], or with a tangential motion of the fabric with respect to ambient air [1,15]. In some cases the motion of a person wearing clothes is considered [12].…”

“…The current description of these processes relies on empirical models [11][12], global laws [1,[13][14][15][16] or statistical approaches [17], of limited applicability, for describing vapor or heat transfers through fabrics. For example, the mass flux of water evaporating from a surface covered by a textile is often considered to be simply proportional to the vapor pressure difference and to a material coefficient, i.e.…”

“…For example, the mass flux of water evaporating from a surface covered by a textile is often considered to be simply proportional to the vapor pressure difference and to a material coefficient, i.e. the so-called "clothing vapor resistance" [12,[14][15]; an approach which is likely valid in steady state. The heat transfer is then assumed to be simply proportional to this vapor mass flux.…”

Evaporation coefficient determination during the capillary rise

“…20,21 The evaporation from the textile fabric was mainly considered when studying drying or cooling. [22][23][24][25] It was found that the relative air humidity is a main factor of the weather conditions that have principal influence on the evaporation intensity. 26 A thorough model to simulate capillary flow through fabrics while taking evaporation into account is still lacking, according to a comprehensive review of the literature in this area.…”

“…20,21 The evaporation from the textile fabric was mainly considered when studying drying or cooling. 22–25 It was found that the relative air humidity is a main factor of the weather conditions that have principal influence on the evaporation intensity. 26…”