Measurement of the combined heat and water-vapour flow through clothing under transient conditions

A sweating hot plate for the study of combined heat and water-vapor flow through clothing under Transient conditions is described. The results are in good agreement with the mathematical model reported in a previous paper for several model clothing systems. The heat loss through wool clothing was found to be smaller than that through similar polyester clothing during periods of sweating and larger during subsequent periods of drying, because of the effects of absorption of water vapor by hygroscopic materials. A comparison was made of the heat and vapor transmission of the clothing systems by incorporating a vapor-impermeable fabric or the waterproof but vapor-permeable fabric Gore-TEx. Liquid water was observed to condence on the inner surface of both fabrics during periods of sweating but the Gore-TEx dried within a few minutes of the end of the sweating period. Gore-TEx was found to be vapor permeable even at temperatures below 0 degrees C when frost was forming on its inner surface.