| 摘要 |
A cooling tower is provided with a crown inwardly tapered towards the upper discharge opening defined by the upper rim of the crown to create a pressure differential greater on the inside than on the outside of the crown to inhibit cold air break-ins in still air or winds of low velocity. The cooling tower shell is tapered inwardly in the crown region and the angle between the tangent to the internal contour and the vertical in said crown region of the shell is preferably chosen to be not smaller than results from the following equation: <IMAGE> (1) in which alpha is the angle in question, g is the acceleration due to gravity, rho a and rho i are the gas densities inside (i) and outside (a) of the cooling tower, z is the vertical coordinate, do and d(z) are the diameters of the internal shell contour at the level z=o and z, respectively, and wo is the gas velocity at the level z=o. By this equation, the cooling tower designer may provide for shell contours which for all sizes of cooling towers on the one hand safely prevents cold air penetration and on the other hand warrants a minimum of draft losses in operation of the cooling tower. To reduce the effect of side winds of high velocity, the crown may carry a wind-deflector ring with an upwardly-inclined deflecting surface to inhibit the creation of a vortex over the tower.
|
