International Journal of Thermal Sciences 46 (2007) 308–317 www.elsevier.com/locate/ijts Wind tunnel simulation of exhaust recirculation in an air-cooling system at a large power plant Zhifu Gu a,∗ , Xuerei Chen a , William Lubitz b , Yan Li a , Wenlin Luo a a State Key Laboratory of Turbulence and Complex Systems, Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing, 100871, People’s Republic of China b Department of Mechanical and Aeronautical Engineering, University of California, Davis, CA, 95616, USA Received 8 August 2005; received in revised form 7 April 2006; accepted 12 April 2006 Available online 5 June 2006 Abstract 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.  2006 Elsevier Masson SAS. All rights reserved. Keywords: Air-cooled condenser; Wind tunnel simulation; Recirculation; Power plant 1. Introduction A lack of an assured supply of water can be an obstacle to the construction of mine-mouth power stations in many areas of the world, particularly in northern China where coal reserves are abundant. Direct Dry Cooling Systems technology is an im- portant solution to minimize power station water consumption. The core device in a Direct Dry Cooling system is an air-cooled condenser (ACC). The ACC uses a space-saving A-frame design installed at level of 40 to 45 m high for a typi- cal 600 MW power plant. The condensers are constructed with rugged galvanized steel elliptical finned tubes, which trans- fer heat consistently and reliably. In an ACC cell, steam ex- hausted from the turbine flows inside the steel elliptical finned tubes, while cooling air is drawn upward across the fins by a large fan that is mounted underneath. The cooling air removes heat from the turbine exhaust steam, causing the steam to con- * Corresponding author. Tel./fax: (+86) 10 6275 6079. E-mail address: guzf@pku.edu.cn (Z. Gu). dense. Fig. 1 shows a typical ACC cell. Under ideal conditions (i.e. with no adverse wind effects) turbine backpressure control is easily maintained by varying the airflow through the con- denser. Fig. 1. Schematic drawing of an ACC cell and platform. 1290-0729/$ – see front matter  2006 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.ijthermalsci.2006.04.007