Abstract
A heated room is numerically analyzed to study thermal comfort. Cold air flowing in from the inlet gets heated by a heat source (placed just below the inlet), before being distributed throughout the room. The presence of the heat source and a high Rayleigh number causes the flow of air to be buoyant and turbulent. Two RANS based turbulence models, RNG k-ε and k-ω SST turbulence models are used to model turbulence and the Discrete Ordinate (DO) radiation model is used to model radiation heat transfer between different surfaces in the room. In order to account for buoyant air movement, air is approximated as a Boussinesq fluid. Parameters that affect comfort such as comfort temperature, operative temperature, turbulence intensity, velocity and the temperature difference between the head and ankle level are investigated. It is found that the comfort temperature and operative temperature predicted in this study have similar profiles irrespective of the turbulence models. Predicted values of turbulence intensity and velocity were low, which shows a low risk of drought in the occupied zone. The two RANS models give results similar to earlier studies that were performed with different turbulence and radiation models, proving their robustness and viability for a variety of flow problems.
Highlights
Most times, rooms are heated during cold seasons to improve comfort conditions
The comfort temperature predicted by Renormalization Group (RNG) and k-ω shows the same profiles at all the monitoring lines
Predicted comfort and operative temperatures are between 20 °C and 22 °C, which gives a comfortable thermal feeling in the room for a winter climate
Summary
Rooms are heated during cold seasons to improve comfort conditions. The nature of flow in a room is affected by the presence of a heat source as it induces a temperature gradient resulting in a buoyant air movement. This influences the motion of air in the room. Though air velocity is small, flow, in this case, have a high Rayleigh number (Table 1) and have a turbulent character. A high level of turbulence coupled with air movement will increase the rate at which heat is convected away from warm bodies causing unwanted cooling
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