Experimental study of bank aerodynamics of atmospheric spray cooling systems

Abstract

Atmospheric spray cooling systems are alternatives to cooling ponds and cooling towers for rejecting condenser heat of steam-electric power plants. This study concerns the flow of the atmospheric wind over the confining banks of the system, and concentrates on the effects of bank height and geometry on the profiles of wind velocity and turbulent diffusivity incident to the sprays and the possibility of flow separation which may substantially degrade thermal performance. The literature of flow over similar geometries is reviewed. A wind-tunnel study was performed on a scale reduced 90 : 1 wherein both 1 : 3 and right-angle banks of two bank heights were analyzed. The full-scale equivalent bank heights were 2.3 m (7.5 ft) and 6.8 m (22 ft). Measurements were also taken with sprays modeled with wire mesh of equivalent aerodynamic blockage. The atmospheric boundary layer was approximately simulated through the use of a counter wall jet, screens and artificial aerodynamic surface roughness. The resultant profiles of wind velocity, Reynolds turbulent stress and turbulence kinetic energy are presented and compared. The Reynolds stress and turbulence kinetic energy are indicative of the level of turbulent diffusivity, important in atmospheric dispersion of heat and humidity. Field measurements were alsomore » taken of mean wind velocity for three bank geometries at the Quad-Cities Nuclear Station. However, these data were more limited and less controlled than the wind-tunnel results. The 1 : 3 slope bank cases resulted in no apparent flow separation although the velocity and turbulent stress were reduced near the base of the banks, especially for the higher bank case. In the case of the right-angle banks, flow separation occurred extending downwind approximately 1.5 bank heights. It is suggested that the spacing from the base of the bank to the first row of modules be greater than 1.5 bank heights.« less