Study On Lower The Outlet Temperature Of Natural Draft Wet Cooling Tower

Based on the theory and relative theories of heat and mass transfer between air and water of the cooling tower,this paper built the three-dimension numerical model of the cooling tower with the software FLUENT. Use different numerical models for the zones with different characteristics of heat and mass transfer. In the rain zone and spray zone,the discrete phase model(DPM)was used to simulate the heat and mass transfer between the water and the air. In the fill zone, based on the Poppe model, the user defined function(UDF)is used to add source terms into the control equations to simulate heat and mass transfer between air and water.According to the natural draft wet cooling tower of a 1000 MW power unit in a power plant, this paper analyze the flow and heat transfer of the cooling tower.Considering the low heat transfer efficiency of the central region, this paper proposed the method of installing water collecting plate in the rain zone. This paper simulated different plant inner diameter and install height. What's more, another plan is presented that installing several catheter channels in the rain zone, which can make a part of air flowed into the central region of cooling tower directly.This paper simulated different structure size and number of catheter channels. Calculation showed that the outlet water temperature can decreased by 0.53?with the best type. Use different length channels in the cooling tower. Calculation showed that the outlet water temperature can drop 0.66?with the best type of installing ten catheter channels with different length of 35 m and45m structure.