Experimental study on using PCMs of different melting temperatures in one cooling vest to reduce its weight and improve comfort

Abstract

This study aims at evaluating experimentally phase change material (PCM) cooling vest performance when incorporating two types of PCM with different melting temperatures with varied PCM placement on the lower, upper, front and back of the torso. Experiments on a thermal manikin were conducted to assess cooling rate observed with the various PCM arrangements while experiments on six male subjects were conducted to assess associated physiological and comfort votes after exercising for 45min.The main findings of manikin testing were that an improved cooling effect can be achieved by covering the upper torso with PCM packets at 28°C melting temperature while covering the lower torso with the 18°C packets. Human subject testing established that similar improvements in thermal comfort and sensation levels could be attained when covering the back or lower torso segments with 18°C instead of covering all the torso. In addition, a maximum reduction in local skin temperatures of 5.45±1°C was achieved accompanied with a reduction of 64W in body heat storage. Covering the chest and upper back segments with the 18°C packets suppressed sweat production and improved wetness sensation. Finally, 16% lower vest weight might be possible with prolonged working periods of two hours at 35°C.