Dissertation Defence: Heat and Moisture Transfer in Skin-Clothing-Environment System
June 17 at 9:00 am - 1:00 pm
Ruoyao Li, supervised by Dr. Sunny Li, will defend their dissertation titled “Heat and Moisture Transfer in Skin-Clothing-Environment System” in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mechanical Engineering.
An abstract for Ruoyao Li’s dissertation is included below.
Examinations are open to all members of the campus community as well as the general public. This examination will be offered in hybrid format. Registration is not required to attend in person; however, please email sunny.li@ubc.ca to receive the Zoom link for this exam.
Abstract
Clothing plays an important role in regulating heat and moisture exchange between the human body and the ambient environment. Heat and moisture transport through clothing systems is complex because it is governed by the coupled effects of fabric properties, air gap microclimates, clothing geometry, and environmental conditions. These interactions are difficult to isolate experimentally and are not fully captured by standard fabric tests alone. To address this limitation, this dissertation develops an experimentally validated numerical model to investigate coupled heat and moisture transfer in skin-clothing-environment systems.
An important contribution of this thesis is the development of the numerical model that represents fabrics as porous and air-permeable media rather than impermeable layers. This approach allows air penetration, viscous shear, and inertial effects within fabric layers to be incorporated into the analysis. The model also accounts for heat conduction, convection, radiation, and moisture transfer. The model was validated using measurements from a sweating guarded hotplate, supporting its use for parametric analysis.
The research progresses from simplified skin-clothing microclimates to more realistic clothing configurations. In planar microclimates, the results showed that increasing air gap thickness can shift heat and moisture transfer from conduction- and diffusion-dominated behavior to natural convection. When fabric folds and loose clothing were represented using wavy microclimates, airflow direction, wave geometry, and fabric permeability were found to alter heat loss by changing local airflow patterns. In multilayer clothing systems, air gap distribution and fabric arrangement strongly influenced thermal resistance, with fabric permeability having a greater effect than thermal conductivity under wind exposure. Torso-scale experiments and simulations further showed that heat and moisture transfer vary across the body because of local differences in air gap size, fabric type, garment fit, and moisture distribution.
Overall, this dissertation contributes to a better understanding and prediction of heat and moisture transfer in clothing systems. The findings clarify transport mechanisms in porous clothing layers and provide guidance for the design of sportswear and functional garments with improved thermal comfort and moisture management.
