Experimental And Numerical Analysis Of Condensation Heat Transfer Characteristics Of Micro Straight Ribs In Tubes

This paper introduces the development background and research status of the air-cooled island of the power station.By comparing the working medium,tube type,length-to-diameter ratio and heat flux of different radiators,the micro-straight rib tube radiator model is determined and established to simulate the power station In the environment of air-cooled islands,the heat transfer of micro-straight rib round tubes under different inclination angles was experimentally and numerically simulated,and compared with the heat transfer capacity of smooth tubes.In the experiment,a micro-straight rib tube with a length of 1140 mm was used.The inner diameter of the tube was 7 mm,the outer diameter was 8 mm,the rib height was 0.25 mm,the number of teeth was 62,and the rib vertex angle was 15°.In the experiment,the inclination angles of the micro-ribbed tubes were 30°,45°,60°,75°,and 90°,and the heat transfer performance was explored by changing the steam mass flow rate and the air intake on the air side.The range of air Reynolds number is 4000-6000,and the range of condensate Reynolds number is 60-160.The heat transfer capacity under different air Reynolds numbers,heat transfer capacity under different inclination angles,condensation heat transfer coefficient under different steam flow rates,and heat exchange coefficient under different inclination angles were compared.Using the simulation method,the simulated length is 600 mm,the inner diameter of the tube is 7mm,the rib height is 0.25 mm,the number of teeth is 62,the micro-straight rib tube with a rib vertex angle of 15°,and the water vapor of the smooth tube with a length of600 mm and a tube inner diameter of 7mm Condensation heat transfer in the tube.Set a constant wall temperature,select VOF model and Lee model,and simulate the condensation by changing the inclination angle of the tube and the mass flow of the inlet steam.And verify the simulation results and experimental results.Through experiments and numerical simulations,it is obtained that the condensation heat transfer coefficient and the heat transfer amount in the tube will increase with the increase of the air Reynolds number and the steam mass flow rate.Under the same conditions,the heat transfer coefficient of micro-straight rib tubes is 1.2-2.32 times that of smooth tubes.When the angle between the inclination angle and the ground is 30°,the micro straight rib tube will have a maximum condensation heat transfer coefficient.Compared with the vertical tube,the enhanced heat transfer coefficient is 1.3-1.6 times.