Heat and moisture transfer through skin-clothing microclimate

The microclimate between clothing and human skin plays an important role in the heat and moisture exchange between body and ambient environment, which is essential to the thermo-physiological comfort. Despite extensive research on microclimate heat transfer, the sweating process accompanying heat transfer has often been neglected, and the investigation of transport mechanisms is limited. In this study, the heat and moisture transfer from skin to environment was experimentally and numerically simulated with focus on factors such as microclimate thickness (0 mm similar to 40 mm), tilt angle (0 degrees similar to 90 degrees), and airflow direction (parallel and normal to the fabric surface). The skin was represented by a surface with uniform temperature in experiments and numerical simulations, and the fabric was modeled as an air-permeable porous medium in the numerical simulations. The experimentally validated numerical model provided detailed distributions of temperature, vapor concentration, and airflow patterns in the microclimate for both dry and wet skins. The airflow of natural convection featured multiple circulation cells, and their circulation times were calculated and then related to the microclimate transport performance. It was found that natural convection dominates the heat and moisture transfer in thicker microclimates. It was also found that normal airflow was more effective in facilitating the heat and moisture transfer as compared to parallel airflow. The results are useful for developing high-performance clothing optimized for thermal regulation and moisture management, improving comfort and safety in different conditions.