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The purpose of this paper is to investigate the effect of air and vapor permeability of jacket materials on ventilation, heat and moisture transfer.

Clothing ventilation (V), thermal insulation (I) and vapor resistance (R _e ) of three jackets made of different materials (normal textile, PVC and “breathable” membrane coated textile), worn on an articulated thermal manikin in a controlled climate chamber, were measured under various conditions, respectively. The various conditions of microenvironment ventilation were created by making the manikin stand and walk, combined with three wind speeds of <0.2, 0.4 and 2.0 m/s, respectively.

In the condition without any forced convection, the air permeability makes no big difference to dry and evaporative heat transfer among the jackets, while the vapor permeability plays a big role in the evaporative heat loss. In the condition with forced convection, the dry heat diffusion is strongly coupled to the evaporative heat transfer in air and vapor permeable textile material.

The effects of ventilation on heat and moisture transfer varies because of different ways of ventilation arising: penetration through the fabric is proven to be the most effective way in vapor transfer although it does not seem as helpful for dry heat diffusion.

The achievements in this paper deepens the understanding of the process of the dry and evaporative heat transfer through clothing, provides clothing designer guidance to choose proper materials for a garment, especially work clothing.

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.

The maximum water evaporation rate (WER_max) 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.

Experiment results show that the ratios of WERs to WER_max are lower than 100 percent but higher than 50 percent, which confirmed that the prediction of WER_max 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 WER_max in the higher wind condition were speculated to be due to the greater temperature decrease caused by the increased evaporation.

It provides a reliable way to obtain both WER_max and WER (WER_max multiplied by a proper ratio), which can be useful in clothing physiological modeling to predict clothing comfort.

This study contributes to the understanding of the evaporation process of textile materials.