Study On The Impact Factors Of The Flow Dynamics And Heat Transfer In The Air-cooled Condenser

The air cooling unit used the air as cooling medium, its performance was greatly influenced by the external environment factors, the gas fluxes and the heat transfer efficiency of the air cooling unit were sensitive to the environment conditions. Therefore, it was of great necessity to enhance the heat exchange efficiency through the approach of modifying the structure of air-cooled islands thus improving their external flow fields.Based on the platform of numerical simulation software FLUENT, this paper carried out extensive numerical simulation study on the external flow field of a 600MW direct air-cooled unit, and the main contents and conclusions were listed below:1. Analyzing the heat transfer characteristic of the air-cooled island under different environment conditions, that was the effect of factors including ambient wind velocity, wind direction and ambient temperature on heat transfer amounts and the flow field of the air-cooled island. This study found that the flow field would not be obviously interrupted when ambient wind velocity was below 3m/s, however, when the ambient wind velocity exceeds 3m/s, a few recirculation emerged and increased with the increasing wind speeds. In the case of various wind directions, the wind behind the furnace had greatest effect on the heat exchange efficiency of the air-cooled island which was found to be easily influenced by environment temperature.2. Studying on the overall structure of the air-cooled island via Orthogonal Test method. Based on the analyzing results that the total heat transfer amounts of the air-cooled islands with various combinations of the air-cooled platform, up-windbreak height, down-windbreak height and the arrangement angel of the tunes, this study revealed the optimal structure. The results showed that the air-cooled island displayed the highest heat exchange efficiency, when the up-windbreak height was 9m, the air-cooled platform was 47m, the down-windbreak was 7m, the angel was 55°and the wind behind the furnace was present..3. Considering the fact that the units adjacent the air-cooled island exhibited small ventilation and low heat transfer efficiency, this study present a modified air-cooled island structure whose adjacent units were heightened to improve entry conditions of fans, so the heat transfer efficiency of the whole air-cooled island was enhanced evidently. This would provide instructions for the design of air-cooled islands.