一种新型变截面换热管强化传热性能

针对工程中广泛存在的管内层流换热传热系数低的问题进行了强化传热研究，并在传热强化理论的指导下，开发了一种新型变截面换热管。分别建立不同参数下的新型变截面换热管和普通圆管模型，采用大型CFD分析软件FLUENT借助数值模拟的方法，研究新型变截面换热管结构对管内层流换热的影响。研究结果表明，该新型变截面换热管在层流情况下可较大程度地强化管内换热，而其流阻增加较小，具有良好的综合强化传热性能。在本文研究的范围内，变截面换热管的Nu和η均随L₁/d_i或L₂/d_i的减小而增大，且η>2.22。计算结果为强化管内层流换热提供了一定的指导和理论依据。

Heat transfer enhancement of heat tube with variable cross-section

The issue of heat transfer enhancement is analyzed for the widely existed problem of the low heat transfer coefficient of laminar convective heat transfer in tubes. A new type of tube with variable cross-section is introduced under the directions of the heat transfer enhancement principles. Models of new tubes with variable cross-section under different parameters and general round tube are established. With large CFD analysis software FLUENT, and the influence on laminar convective heat transfer in tubes of new variable cross-section heat exchange tubes are investigated. Results show that the new tubes with variable cross-section could markedly enhance the laminar convective heat transfer of the tube side with less additional increase of flow resistance, and has a better synthetic performance of heat transfer enhancement. Within the scope of this study, Nu and η of new heat tubes both increase with the decrease of L₁/d_i or L₂/d_i, and η of new heat tubes is greater than 2.22. The results provide a certain guidance and theoretical basis for the enhancement of laminar convective heat transfer in tubes.