Heat and Moisture Transfer Modeling and Performance Evaluation of Hygroscopic Fabrics for Thermal Comfort Across Different Body Parts in Extreme Heat

Abstract

High-temperature environments with elevated heat and humidity present significant challenges to maintaining thermal comfort, particularly during prolonged exposure. This study evaluates hygroscopic cooling fabrics for body part specific thermal regulation under such extreme conditions. A comprehensive numerical model was developed using Laplace transforms to analytically solve transient, coupled heat and moisture transfer equations in a multilayer fabric–skin system. The model incorporates human thermoregulation, including metabolic heat generation and sweat evaporation, and was applied to simulate thermal responses for the torso, forearm, and thigh regions. Synthetic datasets, calibrated from literature, were used for preliminary validation, while controlled experiments with a sweating thermal manikin (40–45 °C, 85–95% RH) assessed fabrics composed of natural fibers and advanced hygroscopic materials. Results indicated that linen, the best-performing fabric, reduced steady-state skin temperature by up to 3.5 °C and improved evaporative cooling efficiency by approximately 30% compared to conventional textiles, with the torso showing the highest cooling benefit. The Laplace-domain approach enabled efficient handling of discontinuous boundary conditions, with inverse transformation providing time-domain predictions for different body regions. These findings demonstrate the potential of region-targeted application of hygroscopic fabrics validated through modeling and experimental analysis to enhance thermal comfort and mitigate heat stress in high-temperature, high-humidity environments, offering practical solutions for occupational and protective clothing design.