Experimental study on a phase change cooling garment to improve thermal comfort of factory workers

This study focuses on the effect of phase change cooling garment (PCCG) on thermal comfort of factory workers in hot indoor environment. Participants were asked to perform two physical activities: packing and standing. Physiological parameters (including heart rate, blood pressure, oxygen saturation, skin temperature and ear canal temperature) were measured and subjective questionnaires (involving overall and local thermal sensation, thermal comfort, thermal satisfaction, etc.) were collected. Cognitive ability tests were conducted. The results showed that the PCCG reduced the mean skin temperature and local skin temperature of the cooling parts effectively. The mean skin temperature decreased approximately 1 °C during packing, and 1.6 °C during standing, which indicated that the cooling effect declined with the increase of metabolic rate. For the other measured physiological parameters, the use of PCCG had little effect on them. Both the local and overall thermal sensation decreased significantly when using the PCCG, and the decrement also dropped as metabolic rate increased. Other subjective votes were also significantly improved. The working efficiency was increased by 19%. Most of the subjects had no cold stimuli sensation when put on the PCCG. The results of cognitive ability tests showed that, the use of PCCG had no effect on the task error rate, while the completion time was decreased. The reduction in mean skin temperature and thermal sensation was correlated in the two activities, separately. For workers exposed to hot environment, the PCCG improved their thermal comfort and working efficiency effectively, while the effectiveness was related to activity level.