Evaluation Method for the Wet Comfort of Hygroscopic Cooling Fabrics

Several effective methods to precisely evaluate the comfort of hygroscopic cooling fabrics transitioning from a wet to dry state were previously lacking. This study employed the heated plate method to mimic bare skin. We integrated a refitted YG606 II Thermal Resistance Tester with a heating control unit to simulate the human body's thermoregulation following light activity at a basal metabolic rate. This apparatus recorded the heating curves of hygroscopic cooling fabrics in their wet state to monitor temperature variations during drying. We introduced five objective evaluation parameters (Area, FWHM, K1, K2, WCI) based on the temperature differences between the heated plate and wetted fabric samples to differentiate levels of wet comfort among various fabrics. Twelve types of hygroscopic cooling fabrics, varying in material, structure, and hygroscopic properties, were selected from the market to assess the reliability of these parameters. The findings confirmed that these parameters effectively discern variations in wet comfort across the fabric samples. The parameters for cooling capacity (Area) and cooling rate (K1, K2) are critical in evaluating the role of liquid water in fabric on wet comfort, while cooling duration assesses the impact of the fabric's drying process on human comfort. Furthermore, the wet comfort index (WCI) correlated significantly with perceptions of dampness and coldness; a higher WCI value indicated a sharp, transient discomfort due to dampness and coldness, whereas a lower value suggested a mild, sustained sensation of wetness and coldness. The preference for these contrasting sensations varies by context. This research could facilitate the development of predictive models for wet comfort by evaluating the cooling capacity and wet comfort index of textiles in their wet state, thereby aiding fabric researchers and manufacturers in enhancing the thermal-wet comfort of hygroscopic cooling fabrics.