A comparative study of occupant thermal modeling

In North America, the ventilation system in indoor environments have been almost exclusively associated with the use of conventional ceiling air distribution systems, where the air is moved via ducts through ceiling diffusers. However, in the past years there has been a growing interest in the application of localized ventilation systems for which numerous studies have been conducted looking at different aspects such as enhanced thermal comfort, improved indoor air quality and lower energy consumption. It has also been determined that a typical localized ventilation system creates a non-uniform thermal environment, which might cause thermal discomfort due to excessive vertical temperature difference, draft, and asymmetric thermal conditions. As an alternative to the experimental measurments, the Computational Fluid Dynamics (CFD) methods have been used to predict the airflow field around the occupant. The correct prediction of the flow field is dependent upon the proper modeling of the occupant body since the actual shape of human body is complicated and its heat distribution is known to be non-uniform. However, past CFD studies on the subject were mainly performed by modeling the occupant as a block with uniform heat distribution, in order to simplify the problem and decrease the computational cost. In the present study, commercially available CFD software, Airpak from Fluent Inc., is used to simulate the occupant body by using a variety of modeling techniques in order to quantify the impact of occupant modeling assumptions on the bouyancy and inertia in induced flow field