变管径空冷凝汽器空气侧换热特性研究及优化

针对四排等管径圆管直接空冷凝汽器冬季因换热不均易产生冻结的情况,提出了采用变管径翅片管束的思想。用计算流体力学(CFD)方法,对变管径翅片管束的流动换热特性进行数值模拟。研究发现,变管径翅片管束相比于等管径翅片管束,换热均匀性大幅提升,综合性能也有所提高;为提高该类换热器换热性能,将管束排布方式由近等边变化到近等速,凝汽器综合性能增大而换热均匀性变化不明显;在近等速排列变管径管束的翅片上加装涡发生器,综合性能进一步提高,换热均匀性对雷诺数的敏感性有所改变。

Research and Optimization of Air Side Heat Transfer Characteristics of Air Cooled Condenser with Variable Diameter Tube

In view of the freeze due to the uneven heat transfer of the four row tube direct air cooled condenser, the idea of using variable diameter finned tube bundles was put forward. Using the method of computational fluid dynamics (CFD), the numerical simulation of heat transfer characteristics of a variable diameter finned tube bundles was conducted. It is found that the comprehensive performance and heat transfer uniformity of variable diameter finned tube bundles are improved compared with the equivalent diameter finned tube bundles. At the same time, in order to improve the poor thermal performance of this type of heat exchanger, the condenser performance increases but heat transfer uniformity does not change significantly when finned tube bundles changes from nearly equilateral arrangement to nearly isokinetic arrangement. Moreover, the comprehensive performance of air cooled condenser is further improved and the sensitivity of heat transfer uniformity to Reynolds number changes after the addition of vortex generator.