Radiation: Office Ventilation and Heating by Solar Radiation

Description

This simulation models office ventilation and heating by solar radiation using ANSYS Fluent software. The problem is carried out and investigated through CFD analysis.

This project investigates the ventilation, air circulation, and heat transfer within a room. The heat is emitted by people, objects, and electrical equipment inside the room. The thermal energy from human activity, the thermal energy from a working computer, and the heat emitted by light bulbs are all treated as sources of heat generation. The person, acting as a heat source, produces a constant heat of 1928 W/m³, while the computer produces a constant heat of 7285.7 W/m³, and each lamp produces a constant heat of 26356.5 W/m³.

This project also investigates the effect of continuous air circulation inside the room. In addition, a glass window is included on one of the walls to study the effect of solar radiation. The glass surface faces the solar rays to improve heat transfer by solar radiation. The side walls of the room and its floor exchange heat with the outside environment by convection. The ambient air temperature is assumed to be 300 K, and the convection heat transfer coefficient is 19 W/m²·K.

The geometry of the present model is drawn using Design Modeler software. The model consists of a room with a volume beneath it. The room contains a human, a computer, two lamps, and other objects, with a dedicated window designed on one of its side walls. The model is then meshed using ANSYS Meshing software. The mesh is unstructured, and 309,156 cells have been created.

Methodology

The main goal of this project is the thermal analysis and investigation of the different modes of heat transfer. Some of the modeled objects generate heat, so a heat source is defined for them to represent the heat emitted. In this way, the heat source represents the heat produced per unit volume.

Solar ray tracing is also used to investigate the effect of solar radiation. To characterize the quality of the solar radiation, the direct and diffuse solar irradiation must be specified. Another mode of heat exchange with the surrounding medium is convection. To apply this method, the free-stream temperature of the environment and the convection heat transfer coefficient must be defined.

Conclusion

After the simulation, contours of temperature and velocity are obtained, along with the velocity vectors and streamlines inside the office. The vectors and flow lines clearly show the circulation of airflow within the office, indicating the proper operation of the air conditioning system in balancing the temperature inside the room. The temperature contours show how heat is transferred throughout the model, with a clear rise in temperature around the heat sources.