Research On Flow And Heat Transfer Characteristics Of 1000MW Direct Air-Cooled Condenser

The application of traditional wet-cooled condensers are limited and directair-cooled condensers(DACC) are widely and increasingly used in northernChina, where the coal mine mainly distributes upon, but water is short anddominates the price of electricity power.The finned-tube is the key element of heat transfer of DACC. R_esearches onthe flow and heat transfer performance of DACC is of great importance in thedesign and operation of DACC. Under different windward velocity, the flow andheat transfer performances of the finned-tube have been calculated and analyzedbased on CFD(Computational Fluid Mechanics). The relationships betweenpressure drop, fractional coefficient, heat exchange capacity, convectioncoefficient, outlet temperature, finned-tube temperature and windward velocity,and also the dimensionless relationship between N_usselt number and R_enoldsnumber are presented. The results can provide a theoretical basis for the optimaldesign of DACC.Physical and mathematical models were established for the finned-tube andthe DACC's unit, and upon which the rules of flow and heat transferperformances affected by environment under the TRL operating mode in summer ,and the influence of the adjoining units were studied. The worst operatingcondition of DACC that is the gale in summer was emphasized, and under thiscondition the problem of bad heat transfer performance of the units on the edgeof DACC was analyzed. Methods were given and also a new type of guide flowdevice was created to improve the problem. The results of the numericalsimulation show that the length of apron has limited benefit to the gale condition,but the new type of guide flow device improves the problem well.