Cooling vests with phase change material packs: the effects of temperature gradient, mass and covering area.

Phase change material (PCM) absorbs or releases latent heat when it changes phases, making thermal-regulated clothing possible. The objective of this study was to quantify the relationships between PCM cooling rate and temperature gradient, mass and covering area on a thermal manikin in a climatic chamber. Three melting temperatures (24, 28, 32 degrees C) of the PCMs, different mass, covering areas and two manikin temperatures (34 and 38 degrees C) were used. The results showed that the cooling rate of the PCM vests tested is positively correlated with the temperature gradient between the thermal manikin and the melting temperature of the PCMs. The required temperature gradient is suggested to be greater than 6 degrees C when PCM vests are used in hot climates. With the same temperature gradient, the cooling rate is mainly determined by the covering area. The duration of the cooling effect is dependent on PCM mass and the latent heat. STATEMENT OF RELEVANCE: The study of factors affecting the cooling rate of personal cooling equipment incorporated with PCM helps to understand cooling mechanisms. The results suggest climatic conditions, the required temperature gradient, PCM mass and covering area should be taken into account when choosing personal PCM cooling equipment.