Numerical study of the convective heat transfer coefficient of the hand and the effect of wind

Abstract

This study aimed to investigate the effect of wind speed and direction on the convective heat transfer coefficient of the human hand, considering the specific geometry of human hands. Computational fluid dynamics (CFD) simulation of the heat transfer and airflow between the hand and surrounding environment was performed. The numerical hand form was created from a surface scan of a thermal hand manikin and divided into 18 sections, including the palm, dorsal, wrist, and five fingers, with each section divided into three parts: fingertip, middle digit, and finger root. The numerical simulation results were compared with the experiment data and showed good conformity. The numerical results showed that the local convective heat transfer coefficient of each of the 18 hand sections varied significantly due to the specific local geometry of the hand. The convective heat transfer coefficients of the five fingers are larger than those of the palm, dorsal, and wrist, and the fingertip is the most vulnerable section to heat loss. The convective heat transfer coefficient of the whole hand increased from 4.30 to 26.49 W/(m2·K) when wind speeds increased from 0.05 to 2.0 m/s. Wind directions had little effect on the convective heat transfer coefficient of the whole hand but had a significant impact on different individual hand sections. The CFD model, along with the developed regression equations of convective heat transfer coefficient with wind speed, can be a foundation for further study on the interaction of human hands with various thermal environments to improve thermal comfort and work efficiency.