Study Of Windbreakers For Twin-tower Natural Draft Dry Cooling System Under Crosswinds

Indirect dry cooling system in thermal power plants uses ambient air as cooling medium to cool the circulating water in air-cooled heat exchanger.Under the condition of wind,ambient winds will significantly affect the thermo-hydraulic performance of air-cooled heat exchanger and cooling tower.With the gradual expansion in the scale of air cooled power station,the construction of air cooling tower group is also very common.The research on the thermo-hydraulic performance of the tower group and the measures to restrain the adverse effects caused by environmental wind is becoming more and more concerned.By establishing the three-dimensional numerical model of the typical SCAL indirect air cooling system in a 2*200MW unit,including air-cooled heat exchanger and cooling tower,the thermo-flow characteristics of indirect dry cooling system under in windy conditions are achieved.The pressure and temperature fields of cooling air as well as the heat rejections of all sectors at various wind conditions are presented.What's more,the MHEM(Macro Heat Exchanger Model)in the commercial software Fluent is applied instead of the traditional Radiator model because the former is more suitable for heat exchanger with regular shape.According to the impact of environmental wind on natural draft dry cooling system,with two air cooling towers and air-cooled heat exchanger bundles vertically arranged around and combined with single tower wall design experience,three wind-breaker design schemes of A-C based on three typical wind direction are introduced.The three kinds of schemes with the corresponding to the wind cooling tower and air flow,pressure and temperature distribution field as well as the heat rejections of all sectors under the three schemes are compared both qualitatively and quantitatively with the prototype.It is found that the installation of windbreakers mainly affects the pressure distribution inside and outside of the cooling tower,thereby affecting the air flow and heat transfer of radiator.Flow and heat transfer performance of the indirect air cooling system,especially the crosswind side sector are effectively improved.In addition,the heat transfer characteristics of the two towers are different due to the their interaction.The individual program deteriorates the heat transfer performance of some sector,which needs to be further improved.Combined with the results of the above work,a Scheme D of 2*7-piece-windbreaker is designed to adapt to different wind directions.By contrast,it is concluded that the Scheme D is superior in air mass rate and heat rejections at different wind direction.