Numerical analysis of cooling effect of hybrid cooling clothing incorporated with phase change material (PCM) packs and air ventilation fans

Hybrid personal cooling garment incorporating phase change materials (PCMs) and ventilation fans is developed recently and found to be effective from the standpoint of cooling effect and thermal comfort of wearers under different environmental conditions. In the present study, a numerical model is developed to analyse heat and moisture transfer through the hybrid personal cooling garment and understand underlying physical mechanisms. The clothing heat and moisture transfer model is coupled with a multi node human thermoregulation model to be able to determine human thermo-physiological responses under dynamic environmental conditions. The multi-node Tanabe's model is modified to take into account PCMs and non-PCMs covered parts in body segments Apparent heats capacity method is used to deal with the phase change behaviour. The moisture barrier effect of PCM packs along with the evaporation and condensation at the surface of PCM packs are also considered. Results obtained from the newly developed numerical model are compared with the human trial data. Mean skin temperature and core temperature obtained from the numerical model are found to be in good agreement with the experimental results. The model is further used to analyse temperature and moisture distributions within the clothing and heat transfer through hybrid personal cooling clothing. Significantly lower clothing system temperature, core and mean skin temperatures are obtained for hybrid personal cooling clothing as compared to air ventilation clothing. Effects of PCMs and air ventilation are also analysed on heat transfer through the hybrid personal cooling clothing. Furthermore, performance of various personal cooling approaches involving PCMs and air ventilation is compared with the normal clothing under the warm environmental condition. It is found that the hybrid personal cooling clothing exhibits better cooling performance as compared to clothing with other cooling approaches involving either only PCMs or only air ventilation fans. (C) 2018 Elsevier Ltd. All rights reserved.