Wind tunnel simulation of exhaust recirculation in an air-cooling system at a large power plant

The recirculation of hot exhaust air and its dependence on wind direction was investigated as a cause of reduced efficiency in an air-cooled condenser (ACC). A method of simulating exhaust air recirculation at an ACC platform using a wind tunnel is presented, and applied to a proposed ACC addition at an existing power plant. It was found that wind speed and the height of an ACC platform have a significant impact on recirculation. Wind direction was also found to be significant, due to the interference of the buildings adjacent to the ACC platform. The mechanisms that cause recirculation are presented and analyzed, and the characteristics of the recirculating flow are described. It was found that when considering additions to existing power plants, the distance of the new ACC and power plant from the original buildings and structures has only a minor effect on the recirculation of the added ACC platform. Wind tunnel simulation is recommended in the initial design stage of new or renovated power plants with ACC systems to minimize exhaust recirculation.