Performance Comparison Of Circle Tube And Flat Tube Radiator In Air Cooling Island Of Power Plant

Air cooling island radiator is one of the important equipment of direct air cooling system of power station,its function is to condense the steam from the steam turbine into water.At present,the common radiators used in the air cooling island of the power station are a single row of flat tubes,which is brazed with a snakelike fin radiator and multi row elliptical tubes radiator with elliptical fins.The circle tube radiator with straight fins,and with the same volume and pressure drop as a single row of flat tube radiator,is designed in this study,and the total heat transfer coefficient of the radiator is studied by numerical method.First of all,under the condition that the circle tube radiator has the same volume with the flat tube radiator,the geometric parameters of the fin of the circle tube radiator are designed.Secondly,in order to better compare with the flat tube radiator,the best aspect ratio of the circle tube radiator with plain fin is found,the pressure drop with the aspect ratio is very close to the flat tube radiator’s.Based on this aspect ratio,the inlet wind speed at the air side of the radiator is changed,and the total heat transfer coefficient of the flat fin radiator under different working conditions is obtained by numerical simulation.Finally,the inner wall of the circle tube radiator with plain fin is expanded,The total heat transfer coefficient K is obtained by numerical simulation,and compare the heat transfer coefficient K with the heat transfer coefficient of the flat tube radiator’s with corrugated fins and dimpled fins,respectively.Under the condition that the pressure drop is approximately the same,the volume is equal,the total heat transfer area of the radiator is equal and the operating parameters are the same,the total heat transfer coefficient K of the circle tube radiator with plain fins and the flat tubes with two different shapes fins are increased with the increase of the inlet velocity of the radiator,the total heat transfer coefficient K of the circle tube radiator with plain fins is bigger than the K value of the flat tube radiator with corrugated fins about 8.44%~26.25%,the total heat transfer coefficient K of the circle tube radiator with plain fins is bigger than the K value of the flat tube radiator with dimpled fins about 3.31%~24%.But with the increase of the inlet velocity of the radiator,the gap between the total heat transfer coefficient K value of the tow radiators shows a narrowing trend.In this study,the inlet wind speed range of the radiator is studied,the total heat transfer coefficient K of the circle tube radiator with plain fins is always bigger than the total heat transfer coefficient K of the two flat tube radiators.