Characterization of Windshield Effectiveness in Improving Air Cooled Condenser Performance Under High Winds and its Impact on Steam Turbine Power Output

Large mechanical draft Air-Cooled Condensers (ACC) are prone to a decay of efficiency and to fan blade load fluctuations that largely increase in the case of high-speed winds and strongly depend on wind directions. A common and relatively simple strategy used to mitigate such wind losses is the installation of partially porous screens made of specialized fabric that acts as wind breakers. A previous numerical study defined a CFD methodology able to quantify the ACC cooling capacity deficit due to wind and identified a ground installed vertical windshield in the shape of a cross as the most effective means to recover such losses under the most critical wind conditions. In this paper, the same CFD model was used to characterize the windshield performance under different wind conditions covering a large range of wind speeds and directions. Furthermore, the analysis is expanded coupling the ACC heat transfer predicted by CFD with a thermodynamic model of the steam cycle that permitted to compute the thermal equilibrium between the steam and air side. Feeding the thermodynamic model with appropriate weather forecasts, it was possible to compute the expected extra annual production thanks to the windshield installation. Providing installation costs and energy selling prices, the developed tool permits a reasonable estimate of the payback period for the investment in windshields which proved to vary largely depending on the energy selling price but was always less than a year for the selected locations.