Cooling vest with optimized PCM arrangement targeting torso sensitive areas that trigger comfort when cooled for improving human comfort in hot conditions

• Published in: Energy and buildings 2017-03, Vol.139, p.417-425
• Main Authors: Itani, Mariam, Ghaddar, Nesreen, Ghali, Kamel, Ouahrani, Djamel, Chakroun, Walid
• Format: Article
• Language: English
• Subjects: Ambient temperature; Computer simulation; Cooling; Cooling vest; Environmental conditions; Labor standards; Optimization; Overall sensation and comfort; Phase change material; Phase change materials; Segments; Skin; Studies; Temperature; Temperature effects; Thermal comfort; Torso
• ISSN: 0378-7788; 1872-6178
• DOI: 10.1016/j.enbuild.2017.01.036

•PCM arrangement in a vest was optimized for minimum weight and for comfort at 3 ambient conditions.•Optimization targeted PCM arrangement over torso segments that can trigger comfort when cooled.•A validated integrated Fabric-PCM and bio-heat model was used to evaluate vest thermal performance.•For acceptable comfort at 3 Met, 8 PCM packets are recommended for use at 28°C and 18 packets at 35°C.•Work period was extended from 0.75 to 2h in the hot condition by having 32 PCM packets in the vest. The objective of this work is to optimize the arrangement of Phase Change Material (PCM) packets in a cooling vest by targeting torso segments that can trigger comfort when cooled. An integrated fabric-PCM and bio-heat simulation model is used in the optimization to predict human segmental core and skin temperatures to determine overall human thermal comfort during moderate activity in hot environment over a specified working period. The variables of the optimization were the number of PCM packets on the upper and lower front and back torso segments. The constraints to be met were: a core temperature not to exceed 38°C, a comfort level not to be less than −1.4 on a comfort scale varying from very uncomfortable at −4 to very comfortable at +4 and a PCM melted mass fraction between 0.85 and 1.0. Three environmental conditions were considered at 28°C, 35°C and 45°C for optimization and the results showed that 8, 18 and 20 PCM packets were needed to provide cooling for the outdoor worker at acceptable comfort level, respectively. At the very high ambient temperature of 45°C and when increasing the PCM packets number to 32 packets, it was shown that the working duration can be extended from 45min recommended by labor standards to two hours similar to duration permitted at 28°C and 35°C.