径向错列翅片管内凝结对流换热数值模拟分析

采用数值模拟方法,对径向错列翅片管内含不凝结气体水蒸气的凝结对流换热及阻力特性进行了综合分析。将编写的自定义函数(UDF)导入ANSYS FLUENT软件,对新型强化管传热性能和阻力性能进行了数值模拟,并根据管长方向壁面上蒸汽质量分数的变化情况,讨论分析了凝结过程中翅片管传热性能的变化规律。分析结果表明:与光管相比,内翅片管的强化传热效果随翅数增多、翅片换热接触面积增大而更加显著;另一方面,翅片管的流动阻力相应增大,对管路换热产生不良影响。在所研究翅型范围内16翅y=2x~2型翅片管综合强化换热效果更优;此外随着换热过程的持续,蒸汽凝结逐渐放缓;入口速度增大导致水蒸气凝结不充分,对换热效果的提升有一定制约。

Numerical simulation of the convective and condensation heat transfer process in a novel staggered internally finned tube

The convective and condensation heat transfer and flow processes of the water vapor with non-condensable gas in radial direction staggered internally finned tubes were numerical investigated. The User Defined Function(UDF) was compiled into ANSYS Fluent to analyze the heat transfer and flow resistance performance of tubes.The vapor mass change on the wall along the tube length was obtained to discuss the heat transfer performance of the tube. The results show that the proposed finned tube gains a preferable heat transfer performance with more fins and larger cross-sectional area of fins. However, the flow resistance of finned tubes increases remarkably compared with the smooth one,which is harmful to the heat transfer performance. Within the scope of this research, finned tube shaped of y=2x2 with 16 fins possesses a preferable comprehensive performance. Additionally, the condensation rate declines during the heat transfer process. The increase of inlet velocity leads to insufficient condensation of water vapor and exerts an adverse impact on the performance improvement.