Personal cooling garments with phase change material packages - A critical review of challenges, solutions and recent progress

Personal cooling plays a prominent part in alleviating heat stress and improving working efficiency for outdoor workers especially with the increasingly serious global warming. The cooling garments with phase change material (PCM) packages (PPCGs) utilize phase-change latent heat of PCM packs which are embedded in the pockets distributed in different parts of the garment to absorb heat from the body and the micro-environment. Compared to other types of cooling garments, the PPCGs have particular advantages of energy-saving, low-cost, high simplicity and portability. Nevertheless, there are still some critical challenges of this cooling system which obstruct its further development and wide application. This paper provides a detailed review on the challenges and corresponding technological solutions of the PPCGs for personal cooling applications in hot environments. Aiming at the problems of intrinsic drawbacks of PCMs, high humidity in the micro-environment and limited cooling period, the heat-dissipation principle of the human-PPCG-environment system and key factors influencing the cooling performance are analyzed as explanation of the above problems and theoretical basis of the following possible solutions. Subsequently, the corresponding solving strategies are given in view of the three prominent challenges. The solutions of hybrid system integrating PCMs with other cooling technologies and combination of PCMs with different melting temperatures provide innovative ideas for cooling performance improvement and manifest obvious effect on one of these challenges, whereas further research is also needed. Finally, an outlook of the PPCG is presented related to the challenges and developing routes.