Significance of PCM arrangement in cooling vest for enhancing comfort at varied working periods and climates: Modeling and experimentation

Abstract

Personal cooling vests that incorporate phase change material (PCM) have been utilized to improve thermal sensation of people working outdoors in different fields (firefighting, construction, military, police, etc.). In this study, an integrated fabric-PCM and bio-heat model was validated through human subject testing to determine the extent to which it could detect thermal and comfort responses when varying the arrangement of a fixed number of PCM packets in the cooling vest. The modeling approach was utilized for given PCM melting temperature to determine the number of packets needed and their optimal arrangement at moderate (35 °C) and hot (40 °C) environments for 45, 60 and 90 min working durations. The findings showed that when full coverage of the torso is not needed, optimal arrangements were those having full back coverage with the remaining packets on the upper front. Lower front cooling did not show significant improvement in comfort over upper front cooling. That effect was more evident when lower front PCM packets were used at the 40 °C hot environment. As the working duration increased, less differences were detected in skin temperatures and comfort between the optimal and worst cases since a higher PCM coverage area was necessary.