Experimental Research And Numerical Simulation Of Crosswind Effect On The Performance Of Indirect Air Cooling Tower

With the risk of water resources increasingly heavier and the need of the inland development of the nuclear power, power plant air-cooling system with its excellent water conservation characteristics, gets more and more attentions from the countries all over the world, especially in coal-rich but water-short areas. At present air cooling system mainly includes three forms, such as the direct air-cooling system, the indirect air-cooling system with surface type condenser(Harman system) and the indirect air-cooling system with jet condenser(Heller system).The radiator of Heller air cooling system is fixed up verticality all around the tower. Its heat transfer performance is greatly affected by environmental conditions, especially the crosswinds which may make air inlet uneven, reduce the air flow rate and cooling efficiency, even harm the safe and economic operation of power plant. Therefore, the study of the effects of the crosswinds to the flow and heat transfer performance is essential to the design and optimization of the air cooling tower. But the study of Heller air cooling system is still less, there are almost no system theory researches and reports referred to improvement measures of the air flow field and temperature field.Hence, based on Heller air cooling system, systematic experiment researches of the thermal performance are carried on. The concepts of the heat efficiency coefficient and thermal efficiency improvement coefficient are put forward to analysis the change of the performance under crosswinds. Model test bed is built. The effects of the crosswinds to the flow and heat transfer performance of the air cooling system are researched by hot state model test method. A new idea that adding air leading plates all around the tower and forming a number of limited size channels to eliminate or ease the adverse effect of the crosswinds is put forward. In addition, the computational model of Heller air cooling system is set. According to the infrastructure of air cooling system and the characteristics of environmental wind field, the influence on the cooling performance caused by crosswinds and the improvement effect are investigated by means of numerical simulation.The study results show that the cooling tower flow field and temperature field are in symmetry without crosswinds. The flow and heat transfer performance of Heller air cooling system in different locations will encounter varying degrees of influence under crosswinds. The total air flow rate and the total heat transfer rate are also influenced. Under high crosswinds, airflow from windward side will oppress that from tower side and leeside. Flow a round circular cylinder is formed. At this time, radial wind speed and effective into tower wind speed are small in tower side and leeside, heat transfer effect is poorer. The worst parts of flow and heat are mainly in the tower side. The influence mechanisms of environmental crosswinds and the certainty of heat transfer deterioration parts point out the direction for the further precautions. Adding air leading plates all around the tower is very effective windproof measure which can improve the operating conditions greatly, change negative effect to positive effect. This research offers theoretical support and test numerical reference to the optimizing design, safety and economy of the direct air-cooled power plant and has certain practical value.