Optimization And Numerical Simulation Study On Structure Of The Wing Wall Of Air Cooling Tower For Indirect Air-cooled Unit

The indirect air cooling system has been widely used in thermal powergenerating units in the region of our country which is imbued with coal but lackof water. Due to its highly dependent on non-contact air cooling to circulatingwater, the environmental wind changes will greatly affect the cooling efficiency.In order to solve the issue that the back pressure for air cooling unit risesand the load declines in summer due to the windy weather, this paper usingporous media model, κ-ε turbulence model and Boussinesq approximationassumption, has conducted numerical simulation research on the operation ofelliptical finned tube and air cooling tower in SCAL type indirect air coolingsystem of a power plant, by means of FLUENT software. Under the differentenvironment wind speeds, the flow resistance of elliptic finned tube, air speedand temperature distribution in and out of the air cooling tower and the totalventilation rate and heat release of the tower is obtained. The bottom of aircooling tower is divided into four areas such as W, Tr, Tl and L area. Theinfluence of wind speed on air flow and heat transfer performance for the fourregions is analyzed, in which the impact of wind speed is described by aparameter called thermal efficiency of the cooling tower.On this basis, it is considered adding cross wing walls to improve the flowfield of air cooling tower and enhance heat transfer performance, and then thenumerical simulation on the effects of the wing wall has been carried out. Thecalculation result shows that adding wing walls can effectively improve thearound flow and eddy phenomenon at T area so as to increase the air flow andheat flux, especially when the wind speed is higher than6m/s, improvement ismore obvious. Meanwhile, the wing walls’ structure parameters including height,width and installation angle are optimized calculated. By comparison it isconcluded that when the parameter for θ, h and b is equal to0°,16.4m and10mrespectively, the effect of wind on cooling tower is minimal while the highestthermal efficiency addition can reach26.52%and the unit back pressure canreduce4.3kPa at most. The simulation on the operation of tower in other seasonsis also conducted. The result shows that the wing walls can not only improve theflow and heat transfer characteristics of air cooling tower so as to reduce the unitback pressure, but also can play the role of effective anti-freezing in winter.