Research On Flow Characteristics Of Direct Air Cooling System

The resistance is produced when air flows through an A-frame direct air-cooled condenser, it is of benefit to the optimal design and operation of direct air cooled system to investigate the resistance characteristics in various structural parameters and analyze the reasons. Moreover, ambient winds seriously affect the thermo-hydraulic performances of direct air-cooled system, it is significant to install windbreak equipment to weaken the bad influence of ambient wind on ACCs.Flow resistance characteristics of air inlet, inlet grid, outlet walkways, fin tubes inclination, fin tubes outlet and steam distribution tubes outlet are obtained in this paper. The results show that the resistance from air inlet is small, there would make no influence on resistance of air inlet when air-cooled platform height changes. With increasing the compactness of inlet grid and outlet walkways and distances from which to fan inlet and exit, flow resistance increases. It is found that the finned tubes inclined arrangement losses are independent of the average air velocity through the heat exchanger. The flow losses increase with a decrease in the oblique angel of heat exchanger. Some correlations based on the simulative results are established to illustrate the mutual relationship between various variables clearly.On the bases of the windbreak device layout and structure parameters, air-cooled units inlet temperature distribution were presented by means of CFD simulations. The flow rate and heat rejection of air-cooled system at various wind speeds and in wind directions of 0° and -90° were calculated and compared with those of air-cooled condensers without windbreak. The results show that the installation of windbreak under air-cooled platform improves the flow rate of air-cooled units from windward side and controls the exhaust plume recirculation from both sides effectively. By optimizing the windbreak equipment further, the adverse effects on downstream air-cooled units is lowered with air flow rate of upstream air-cooled units increasing and exhaust plume recirculation weakening at the same time. It provides a new approach to the flow and heat transfer optimization of direct air-cooled system in a power plant by studying the influence of windbreak equipment with different structures on air-cooled system performance.