Hitachi - Medupi Power Station
Medupi is a dry-cooled coal-fired power station under construction in Lephalale, South Africa. The boilers will be cooled by a natural draft flowing through the boiler houses. The number and the efficiency of the ventilators on the roof had to be tested to ensure that the design would operate within specification. Using the ANSYS Workbench™ environment, the detailed ventilator designs could be assessed. The ANSYS Fluent™ solver was used to determine the discharge coefficients of the ventilators. This information was then used as boundary conditions on the full scale model of the boiler-house natural ventilation. Figure 1 displays the typical flow through one of the ventilator designs from which the discharge coefficient was calculated.
Fig. 1 Contours of velocity magnitude through the ventilator.
After the discharge coefficient was verified, it was applied at the outlet boundary on the full 3D model which represented the location of the ventilator. Figure 2 shows the mesh on the equipment inside the boiler building. Figure 3 displays the flow through the building with the ventilator coefficients applied. Figure 4 shows the temperatures on the equipment.
Fig. 2 Mesh on the equipment inside the boiler building.
Fig. 3 Contours of velocity on a cross section through the boiler building.
Fig. 4 Contours of temperature on the equipment inside the boiler building.
The ventilator design could be verified using ANSYS CFD before manufacturing and installation, providing validation of their operation and design confidence to the client. The final results provided valuable insight into the thermal conditions inside the building, as well as a confirmation of the air quality (mean age of air) throughout the building and the overall number of air changes (ACH).