A numerical study of heat and moisture transport around a standing human body in a room

Thermal comfort of a human body in an indoor environment is often determined by six factors, including air speed, dry-bulb temperature, and relative humidity, mean radiant temperature, clothing, and metabolic rate. Those factors play the important role to determine the thermal load estimated by the heat balance among the metabolic rate, mechanical work, respired vapor loss, evaporative heat loss from skin, and heat loss by convective and radiative heat transfer. As a result, Fang's thermal comfort index, PMV (Predicted Mean Vote), can be calculated by a function of thermal load. The objective of this study is to develop a theoretical model to estimate the evaporative heat loss from a human body's skin based upon the predicted distribution of moisture around a human body. Coupling the energy equation with the moisture transport equation, an evaporative source term was embedded in the energy equation to account for the evaporative heat loss from skin. By using the CFD software, ANSYS FLUENT, the novel developed model was incorporated into the UDF (User Defined Function) to predict the heat and moisture transport around a naked human body with medium metabolic rate and moisture standing in a room ventilated by a single air inlet and a single air outlet. The errors of the average skin temperature between new and traditional equations were dropped by 0.262% .The simulation results indicated good agreement of the predicted skin temperatures of a human body with those predicted by the model available in literature, revealing the accuracy of the newly developed model in this study.