Solar Chimney for a Room HVAC

Description

This project simulates the HVAC performance of a room fitted with a solar chimney using ANSYS Fluent. The model consists of two main parts: the interior of the room and a sloping solar chimney mounted on the room's ceiling. As a passive, sun-driven ventilation device integrated into the building envelope, the solar chimney is a natural subject for architectural engineering, where the goal is to improve indoor comfort and air quality through the building's own design rather than mechanical systems.

The solar chimney has glass plates on its side surfaces that are in contact with the outdoor environment. As a transparent medium, the glass admits solar energy, while a plate at the back of the chimney acts as a heat-absorbing surface. The absorbing surface behind the chimney is assumed to be held at a constant temperature of 335.15 K. The glass surface exposed to the outdoor environment, in contrast, exchanges heat with its surroundings by convection: the ambient air temperature is 308.15 K, and the convective heat transfer coefficient is 8 W/m²K. In addition, the solar energy absorbed inside the chimney is represented as a constant volumetric heat source of 15,000 W/m³.

Methodology

The 2D geometry was created in Design Modeler and comprises two parts: a room measuring 2 m × 3 m, and a solar chimney 2 m long, inclined at 45 degrees to the room's ceiling, with a width of 0.15 m. Meshing was performed in ANSYS Meshing using a structured grid of 42,846 elements.

The airflow enters through the inlet at the bottom of the room under a pressure-inlet boundary condition. Air at 308.15 K is drawn into the room by the heat generated within the solar chimney and then carried out to the external environment, establishing a continuous, buoyancy-driven ventilation path through the space.

Conclusion

On completion of the solution, two-dimensional contours of pressure, temperature, and velocity were obtained, along with pathlines and velocity vectors.

In addition, the temperature distribution across the chimney was plotted at a point midway along its length (1 m from the inlet and outlet), together with the velocity variation across the chimney outlet section. The transverse temperature profile at a point 1 m from the chimney inlet, over the 0.15 m thickness, was extracted and compared against the corresponding temperature profile reported in a reference paper, providing validation of the simulation.

As the results demonstrate, the heat of the solar chimney successfully induces natural airflow that ventilates the room passively — drawing fresh air in at the base and expelling it through the inclined chimney — illustrating how a solar chimney can be integrated into an architectural design to enhance indoor ventilation with minimal energy input.