Investigation of flow and heat transfer around internal channels of an air ventilation vest

Abstract

The effects of a fabric’s ventilation and cooling are important to human comfort in the design of clothes. Persons in a high-temperature situation can experience imbalance of thermoregulation, which in turn results in the symptoms of heat exhaustion and heat stroke. The purpose of this research was to achieve cooling enhancement by designing air ventilation vests as an effective measure to control human thermoregulation in hot environs. In this study, the Taiwan Textile Research Institute devised a new air ventilation vest characterized by seven internal flow channels. The computational fluid dynamics software ANSYS/Fluent® was applied using the three-dimensional conservation equations of mass, momentum and energy to simulate the airflow and heat transfer phenomena within the internal channels. The incompressible turbulent flow was also treated with a standard k-ɛ two-equation model for turbulence closure. We compared the predicted steady axial velocities at the centers of channel exits with the measured data for software validation. The simulated results were employed to investigate the complicated flowfield and heat transfer phenomena around internal channels of the air ventilation vest. In practice, the design with the outlet arranged along the airflow direction produces a higher flow rate due to a relatively lower flow resistance, and thereby achieves better air-cooling outcomes. To enhance the cooling performance, simulations were also conducted to examine the influences of channel outlet design, inlet temperature and velocity on the convective heat transfer coefficient distributions over the inner channel surface of the vest.