加工参数对三维翅片铜管冷凝换热的影响

Effect of manufacturing parameters on condensation heat transfer of three-dimensional finned tube

犁削-挤压加工成形工艺制造的新型三维外翅片管通过三维翅片、二维沟槽的微作用力增强传热。文中通过实验,研究了在不同加工参数下的三维整体外翅片铜管的传热性能,与光管相比,三维翅片管均能明显地起到强化传热作用。横管外的膜状冷凝时,与努塞尔积分方法求得的管外换热系数理论计算式相比,三维管管外换热系数的常数随给进量增大而减小。随切削深度增加到一定值后出现少许下降,管外换热系数的常数可以拟合为进给量多项式,从而得到了三维翅片管管外换热经验计算式与加工参数的关系。

Three-dimensional finned tubes produced by rolling and ploughing-extrusion method can effectively improve the efficiency of heat transfer by the way of produced micro structure such as three-dimensional fins and grooves, etc. The heat transfer performance of three-dimensional finned tube manufactured at different manufacturing parameters, feed value and cutting depth was experimentally studied. Compared with smooth pipe, three-dimensional tubes all show increased shell-side heat transfer coefficient. As for film-shaped condensation for horizontal-oriented tube, Nussel empirical equation can be used to calculate the heat transfer coefficient of smooth tube. The experimental results for smooth tube have a good agreement with Nussel empirical equation. While for three-dimensional finned tubes, the shell-side heat transfer coefficient constant is larger. It decreases with the increasing of manufacturing parameter, feeding value, and increases with the increasing of manufacturing parameter of cutting depth, but drops a little with the increasing of cutting depth when cutting depth comes to certain value. The shell-side heat transfer coefficient constant of three-dimensional finned tubes is fitted to feeding value so as to obtain an empirical heat transfer equation. It shows that this empirical heat transfer equation presents good relevance with the experimental data.