Evaporative cooling and heat transfer in functional underwear

Purpose ‐ The purpose of this investigation is to measure seven different underwears on a sweating torso with differing relative air humidity (30, 50, 80 and 95 per cent RH) and at a fixed ambient temperature of 30°C to determine the influence of the water vapour partial pressure of the environment on the moisture transport properties of various materials. Design/methodology/approach ‐ All measurements in this investigation were accomplished with the authors' sweating torso which simulates the thermal- and humidity release of the human body. Four different sweating rates (50, 75, 100 and 150?g/h*torso) were selected for this investigation. Findings ‐ It was established that the partial pressure difference did not correlate directly with the evaporative cooling. In general, higher evaporation rates were observed in the dry climate conditions. However, with low-sweat rates, the highest relative humidity (95 per cent) generally resulted in greater evaporative cooling than the lowest surrounding humidity conditions (30 per cent). In this investigation, a blended fabric made of PES/Vinal exhibited the most efficient evaporative cooling for all the sweat rates, as well as for the four relative humidity conditions chosen. Research limitations/implications ‐ All received results are based on a surrounding temperature of 30°C (summer climate), for other temperatures the results may be different. Originality/value ‐ The investigation shows that both the relative humidity and the sweat rate have a major influence on the heat loss.