Transient heat loss analysis of fabrics using a dynamic sweating guarded hot plate protocol

Abstract

Moisture management is important for the human comfort of clothing, especially while perspiring. Ideally, the fabric chosen for a garment enables moisture to migrate away from the skin surface, facilitating the liquid to be evaporated into the surrounding environment, which causes a cooling sensation for the wearer. This process is influenced by factors such as fiber type, fabric construction, and fabric treatments, all of which impact the resulting wicking and moisture management properties of the fabric. This research explored the heat loss associated with combined water absorption, wicking, and evaporative cooling during wetting of fabrics. A dynamic sweating guarded hot plate was used to measure transitional heat loss as water was introduced at a steady rate over a 65-minute testing period. The results on a cotton and polyester blend fabric as well as a wool fabric indicated that the liquid water absorption and transport processes significantly influence heat loss properties during this transition. However, the results also show novel aspects in the efficiency of cooling associated with the wicking of sweat and different stages of wetting of fabrics leading to different cooling power. Furthermore, this method raises questions as to whether current sweating guarded hot plate technologies are an appropriate representation of human sweat production or that the scalability of sweat production per unit area is limited. This developed testing method can be successful in quantifying the differences in transitional heat loss and will enable testing of fabrics for comfort in changing conditions.