Effects of ambient temperature step changes on the heat storage and release in thermal protective clothing

Ambient temperature steps between typical non-work and hot work environments will lead to clothing heat storage and release, which is crucial for human health and thermal comfort. In this study, the influence of five types of ambient temperature steps (from 0ºC/5ºC/10ºC/15ºC/20ºC to 40ºC to 0ºC/5ºC/10ºC/15ºC/20ºC) on the heat storage and release in clothing was investigated using a thermal manikin. A moving and temperature-controlled refrigerated incubator was constructed to realize the temperature step conditions. Results showed that ambient temperature step magnitude was positively related to heat storage and release. Some 80% of the amount of heat storage would be completed in around 10 min after the temperature steps. Increasing the inner clothing layer weight and specific heat capacity for local clothing at the chest, thigh and calf improved their heat storage against the large temperature step conditions. As for the abdomen, its heat storage was the largest. However, the clothing layer configuration impacted its heat release, so it was necessary to guide the heat transfer to the skin. The heat storage in the outer layer was increased by 2% to 39% due to adding the inner layer of the garment. The stored heat discharged completely until the temperature step magnitude exceeded 32.5°C. A multiple linear regression formula was proposed to obtain the clothing average heat storage by considering ambient temperature step magnitude and clothing insulation. The results of this study could contribute to the optimization of thermal protective clothing and improvement of the research on human thermal comfort.