Abstract

In this study, the thermal and hydraulic performances of three curved-rectangular vortex generators (VG_1, VG_2, and VG_3) in a compact fin-and-tube heat exchanger were numerically investigated. The secondary flow theory and field synergy principle were employed to characterize the effects of VGs on the flow characteristics and hence the heat transfer enhancement. The thermal and volume goodness enhancement factors were utilized to evaluate the overall performance of VG configurations on the engineering aspects. Results reveal that the secondary flow and synergy between the flow and temperature fields are significantly promoted by applying VGs, by which the heat transfer performance is enhanced. By increasing the tube row number from 3 to 5, the global Nusselt number increases for all the VG cases due to the improved thermal mixing of air flow and fin efficiency. However, in terms of the per-tube heat rejection enhancement, the configuration with tube row number of 3 is most effective for all the VG designs. Results indicate that VG_2 has achieved the best balance between the thermo-hydraulic and volume goodness criterions. The obtained thermal and volume goodness enhancement factors by VG_2 reach as high as 1.42 and 1.24, respectively, manifesting its potential for the development of high-performance and compact fin-and-tube heat exchangers.

摘要

在这项研究中，对紧凑型翅片管式换热器中的三个弯曲矩形涡流发生器（VG_1、VG_2 ​​和 VG_3）的热力和水力性能进行了数值研究。采用二次流动理论和场协同原理来表征 VG 对流动特性的影响，从而增强传热。利用热和体积优度增强因子来评估 VG 配置在工程方面的整体性能。结果表明，VGs的应用显着促进了流场和温度场之间的二次流动和协同作用，从而提高了传热性能。通过将管排数从 3 增加到 5，由于气流和翅片效率的热混合得到改善，所有 VG 情况下的全局努塞尔数都会增加。然而，就每管散热增强而言，管排数为 3 的配置对所有 VG 设计最有效。结果表明，VG_2 ​​实现了热工水力和体积优良标准之间的最佳平衡。VG_2 ​​获得的热和体积良性增强因子分别高达 1.42 和 1.24，显示了其开发高性能和紧凑型翅片管换热器的潜力。结果表明，VG_2 ​​实现了热工水力和体积优良标准之间的最佳平衡。VG_2 ​​获得的热和体积良性增强因子分别高达 1.42 和 1.24，显示了其开发高性能和紧凑型翅片管换热器的潜力。结果表明，VG_2 ​​实现了热工水力和体积优良标准之间的最佳平衡。VG_2 ​​获得的热和体积良性增强因子分别高达 1.42 和 1.24，显示了其开发高性能和紧凑型翅片管换热器的潜力。