三维变形管与三维内肋管在管式空气预热器上的应用研究

本研究对比分析了三维内肋管及三维变形管的结构特点和强化传热机理,在相同工况下,揭示了光滑圆管、三维内肋管及三维变形管用于管式空气预热器时的传热性能和流动阻力性能,三维内肋管和三维变形管传热性能均优于光滑圆管,三维变形管管内传热系数和流动阻力系数随短长轴B/A的减小而增大,三维内肋管可增加每米肋数、肋宽和肋高以强化传热效果,但流体流动阻力也将增加,低Re下,三维变形管管内综合传热性能优于三维内肋管,三维变形管管外自支撑而防止管束振动的特点可以实现在管内外的冷热流体纯逆流动,提出一种传热温差高的逆流三维变空间管式空气预热器,在相同工况条件下,空气预热器重量减轻,体积减小约65%,节省大量的生产和运输成本以及安装空间,三维变形管空气预热器在烟气余热利用中具有推广应用价值。

Study of the Applications of Three-dimensional Deformed Tubes and Three dimensional Internally Ribbed Tubes in Tubular Air Preheaters

Abstract:Contrasted and analyzed were the structural features of three dimensionally deformed tubes and three dimensional internally ribbed tubes and the mechanism governing their intensified heat transfer.Under the same operating condition,the heat transfer and flow resistance performance of a smooth round tube,three-dimensional internally ribbed tube and three-dimensionally deformed tube were comprehensively revealed when they were applied in a tubular air preheater.It has been found that the heat transfer performance of the three-dimensional internally ribbed tube and three-dimensionally deformed tube will all be superior to that of the smooth round tube.The heat transfer coefficient and flow resistance coefficient inside the three-dimensionally deformed tube will increase with a decrease of the ratio of lengths of the short and long axis B/A.For the three-dimensional internally ribbed tube,to increase the number of ribs in each meter,rib width and height can enhance the heat transfer,however,the flow resistance of the fluid will also increase.When Re is low,the comprehensive heat transfer performance of the three-dimensionally deformed tube will be superior to that of the three-dimensional internally ribbed tube.The specific features of the three-dimensionally deformed tube which is supported from the outside by itself to prevent from vibration of tube bundles can realize a pure counter flow of the cold and hot fluid inside and outside the tube.On this basis,a counter flow three-dimensional space-variable tubular air preheater with a big heat transfer temperature difference was proposed.Under the same operating condition,the air preheater will reduce its weight,minimizing its volume by around 65% and saving a large amount of production and transportation costs as well as installation space.The three-dimensionally deformed tube type air preheater will certainly enjoy its popularization and application value in utilization of waste heat from flue gases.