Performance improvement of natural draft dry cooling system by water flow distribution under crosswinds

Abstract

The cooling performance of natural draft dry cooling system may be deteriorated by ambient winds, so effective measures need to be taken against the adverse wind effects. In this work, a three-dimensional numerical model of a typical natural draft dry cooling system coupled with the condenser is developed to investigate the thermo-flow performance improvement of natural draft dry cooling system by circulating water flow distribution, in which the finned tube bundles are dealt with the heat exchanger model to take both the air and circulating water into account. The flow and temperature fields, heat rejection of each sector, outlet water temperature of air-cooled heat exchanger and the corresponding turbine back pressures are obtained. The results show that appropriate water flow distribution can significantly improve the thermo-flow performances of natural draft dry cooling system, while the improper one may deteriorate the cooling performance more seriously at low wind speeds. Based on the entransy dissipation theory, the optimized heterogeneous water distributions are provided under five certain wind conditions by using the numerical-theoretical iterative method.