Local and overall convective heat transfer coefficients for human body with air ventilation clothing: Parametric study and correlations

Convective heat transfer coefficient associated with various human body parts plays an important role in the prediction of physiological responses with the help of human thermoregulation models. The primary goal of this work is to develop correlations for the convective heat transfer coefficients associated with various segments and whole torso of the human body in sleeve opening (SO), collar opening (CO), and both sleeve and collar opening (SCO) scenarios of air ventilation clothing. For this, a 3D CFD model of the air ventilation clothing is developed and validated with experimental data. Detailed parametric study is performed to analyze effect of openings in the air ventilation clothing, air flow rate, fan diameter and inlet (ambient) air temperature on the local and overall convective heat transfer coefficients. Results indicate that the area-weighted average convective heat transfer coefficient associated with whole torso is 36% and 5% higher in the case of CO and SCO, respectively, as compared to the SO case. The convective heat transfer coefficient is highest in the lower-back segment and lowest in the upper-chest segment of the body for SO and SCO scenarios. Whereas in CO scenario, the upper-chest segment has the highest and stomach segment has the lowest convective heat transfer coefficients. Effects of fan diameter and inlet air temperature are found to be least significant on the convective heat transfer co-efficients as compared to the effect of opening and air flow rate. Further, correlations for segment-wise and whole torso convective heat transfer coefficients are proposed in the present work.