Cooling vest incorporated with phase change materials (PCMs): how much benefit is there?

The aim of this study was to investigate torso cooling benefit of various PCM vests in a simulated warm environment (Ta= 34 °C, RH=56 %, Va=0.4 m/s). A pre-wetted cotton torso fabric skin was used to simulate sweating on a thermal manikin (Tmanikin=34 °C). Six conditions were tested: nude fabric skin (Fabric Skin), Vest A without (VA) and with frozen gels with a melting temperature (Tm) of 0 °C (VA+Gel), Vest B without (VB) and with PCMs of Tm=21 °C (VB+PCM21) and Vest B with PCMs of Tm=24 °C (VB+PCM24). Cooling benefits for the three vests were: 10 W/m2 (VA+Gel), -49 W/m2 (VB+PCM21) and -52 W/m2 (VB+PCM24). The restricted evaporation rates were: 97 g/h (VA+Gel), 80 g/h (VB+PCM21), and 75 g/h (VB+PCM24). Torso fabric skin temperature was reduced by 1.6 °C (VA+Gel), 1.2 °C (VB+PCM21) and 0.2 °C (VB+PCM24). The results revealed that all the cooling vests presented negative benefits in a simulated work activity and environmental condition. The observed positive benefit could be only found on reducing local torso skin temperature