Development and experimental validation of a 3D numerical model based on CFD of the human torso wearing air ventilation clothing

摘要

Building energy demands can be reduced significantly with the use of personal cooling clothing where only the microclimate around body is cooled instead of cooling the entire building or rooms using HVAC systems. In the present study, a three-dimensional numerical model of a virtual thermal manikin wearing an air ventilation cooling clothing with actual dimensions and shape was developed to determine heat transfer between the human body and the environment. The actual geometric model was developed based on data obtained from 3D body scanning experiments. Governing fluid flow and energy equations were solved along with the standard k-ε turbulence model. Experiments were carried out to determine accuracy of the developed numerical model. Validation studies were performed by comparing numerical results with experimental results obtained by conducting both thermal manikin experiments and human trials. Good agreement between the two was found. Fluid flow and temperature distribution in the clothing microclimate, local heat flux and convective heat transfer coefficients at various locations in the human body, the sensible heat transfer between the human body and environment and the effect of fan air flow rate on body cooling performance were also analyzed. Maximum heat transfer or cooling was observed in the lower back segment of the body with convective heat transfer coefficient 38.62 W/ m~2K. Overall, torso heat transfer was found to be 273.44 W/m~2 which corresponds to 154.73 W cooling power and 0.24 cooling efficiency of the air ventilation clothing at 20.0 ± 0.5 ℃, 65 ± 5% and 0.4 ± 0.1 m/s. It was noted that the area-weighted average torso heat flux increased as the fan air flow rate increased.