DTRM Radiation Model, Atrium Natural Ventilation

Description

Natural Ventilation in Atrium, Radiation, DTRM, CFD Simulation, ANSYS Fluent, Training

Description

In this project, we perform the numerical simulation of natural ventilation inside an atrium building considering DTRM radiation heat transfer using ANSYS Fluent software. The model of the current project is related to the interior space of a simple atrium building, which has three stories of rooms on two sides.

There is an airflow inlet in the lower part of each room on different stories. Also, on the wall opposite the entrances, there is a panel for air exits.

This outgoing airflow from each story moves upward in the central part of the atrium building. Finally, this air exits the final outlet panel at the highest point of the atrium. Inside the central atrium building and each room are various heat sources (including thermal, electrical equipment, etc.). Also, the exterior of the building is designed as glass and is directly exposed to the sun.

Thermal energy can be transferred by conduction and convection methods. However, it is assumed that radiation heat transfer also occurs in this project. This project aims to investigate the effect of heat transfer in different ways and the effect of solar radiation on natural air conditioning.

We designed the geometry of the model in 3D using Design Modeler software. The computational domain of the model is related to the interior space of a simple atrium building. This building has a central part and two three-story buildings on both sides. Each of these stories has an entrance and exit. Then we meshed the model using ANYS Meshing software. The meshing is unstructured, and 709511 cells are generated.

DTRM Methodology

For this simulation, we used the radiation model to define radiation rays. Radiation heat transfer is one of the methods of heat transfer (such as conduction and convection). All materials at a specific temperature release heat from themselves to the environment, called radiation heat transfer. Radiation heat transfer is used in cases such as flame with a significant environmental temperature.

There are different methods for the radiation model in ANSYS Fluent software. We use the Discrete Transfer Radiation Model (DTRM) in this project. The primary assumption of the DTRM is that the radiation leaving the surface element in a certain range of solid angles can be approximated by a single ray.

Also, we used Solar Ray Tracing to apply the effect of solar radiation on the model. It is enough to determine the data about solar radiation for the model. The current model is related to the building in the southwest direction located in Montreal city in Canada, and is examined at 13:00 on July 15.

These input data determine the amount of direct and diffuse irradiation and the direction of solar rays.

DTRM Conclusion

After the conclusion, we obtained the contours related to temperature, pressure, velocity, and density. We also presented velocity vectors. The results show that the air inside the rooms is heated by heat sources defined on the floor of each story.

However, the natural ventilation system in the atrium building causes the air to leave the exit part of each story and be transferred to the central part of the atrium. Then this air leaves the upper part of the atrium building. This causes the proper circulation of the airflow inside the building.

This CFD Project is the 4th episode of the Radiation Model Training Course.