Abstract:

Significance Heat stress is one of the main health and safety threats for occupational workers when they engage in high-intensity physical labor in hot work scenes, and personal cooling garments (PCG) have been developed to reduce the risk of heat stress and heat-related injuries in hot environments. The cooling effect of PCG is chiefly evaluated by indicators such as cooling duration, cooling rate and human thermal and wet comfort, which are comprehensively affected by factors such as cooling media, basic garments, environment and human activities, reflecting the complexity of the functional design. However, previous studies focused on the cooling mechanism of the cooling media, ignoring supercooling caused by excessive cooling. In addition, basic garments carrying the cooling system for improving cooling effect and human thermal and wet comfort have not been fully considered. This has affected the establishment of the functional design method and system of PCG. Therefore, it is necessary to refine the design essentials for different media to meet different cooling needs, so as to establish a more accurate procedure for the functional PCG design.

Progress Researchers have conducted in-depth research on the factors that affect the cooling effect of PCG and human thermal and wet comfort, from the perspectives including environment, cooling media, basic garments and human activity. The functional design of PCG are considered from two aspects, i.e. the cooling media and the basic garments attached to them. Comparative studies on the characteristics of different types of cooling media, including the cooling methods, advantages and disadvantages of ventilation, liquid and phase change materials. The amount, temperature, humidity and mixed use of the cooling media have a great impact on the cooling effect of PCG and the thermal and wet comfort of the human body. However, insufficient attention was paid to the supercooling of the human body caused by excessive cooling, in contrast to the much increased attention to the cooling time of the cooling system. The auxiliary heat dissipation and moisture removal effect of basic garment fabric and structure design on PCG cannot be ignored as stressed by the researchers, were the fabric performance in heat insulation, air permeability, elasticity and moisture permeability, as well as the clothing structure design attributes such as clothing openings, styles and dimensions are all important. However, there is a lack of in-depth research on the configuration of fabrics and structures.

Conclusion and Prospect The functional design of personal cooling garments can be carried out from two aspects: cooling media and basic garments. The optimization cooling media design can be carried out in association of the media quantity, characteristic parameters, and mixed applications. The quantity and characteristic parameters of each cooling medium have primary and secondary effects on the cooling effect of PCG, and they can be adjusted according to the cooling demands. Under the premise of complementary advantages, the selection of hybrid cooling media should associated to appropriate application scenarios and appropriate cooling strategies. In the design of basic garments, the heat insulation performance, air permeability, elasticity, moisture permeability of fabrics, as well as the opening, style and size design of clothing should be considered separately, and the selection of fabrics and style structures should be adapted to the cooling media. In the future, the configuration design of basic clothing fabric performance and clothing structure under different cooling media can be deeply explored, and accurate design parameters for the configuration of cooling media and basic garments under different environments and different human activity levels can be provided through numerical parameterization research. At the same time, the improvement of cooling efficiency of system has also become the development focus of the PCG functional design.

Key words: personal cooling garment, functional design, cooling medium, basic garment, cooling effect, thermal-wet comfort