高效率雙重熱交換管的數值研究

A numerical study on a high-performance tube-in-tube heat exchanger

董威辰(Tong Wei-Chen)

指導教授 ： 陳文立

共同指導教授 ： 黃景良(King-Leung Wong)

崑山科技大學/工程學院/機械工程研究所/碩士(2008年)

https://doi.org/10.6828/KSU.2008.00061

摘要

在本篇論文為使用數值分析研究在內部管為交錯橢圓管與圓管之
反向流雙管熱交換器。此結果包含在數個重要截面的溫度、壓力分佈與速度向量，以及軸向平均Nu 數分配、整體磨擦係數、熱傳係數與性能係數對管長與雷諾數的變化。本計算結果顯示，引進內部交錯橢圓管可在內部與外部管流內產生軸向的二次流並使熱傳量增加，但磨擦係數也會增加。
一般而言，整體性能係數隨管長與雷諾數的增加而增加。在長管與高雷諾數時交錯橢圓管的表現超過圓管達30%之多，但在某些短管與低雷諾數的條件下交錯橢圓管的表現稍微不如圓管，但差異不大。

關鍵字

雙重管熱交換器 ； 交錯橢圓管 ； 計算流體力學

並列摘要

In this thesis, numerical simulation has been applied on the flows in counter-flow, double-tube heat exchangers with the inner tubes being either alternating horizontal or vertical oval cross section pipes or circular pipes. The
results include temperature and pressure contours and velocity vectors at several selected cross sections, axial averaged Nusselt number distributions and distributions of overall friction coefficient, heat transfer coefficient and
performance factor versus Reynolds number and tube length. The computation shows that the introduction of the inner alternating oval tube produces axial vortices in both the inner and outer tube flows, and the tube’s heat transfer
performance is improved as a result. At the conditions of higher Reynolds number and longer tube, the alternating oval tube performs much better than the circular one, with the performance factor reaching 30% higher at Re=2,000 and tube length=1.266 m. However, at some conditions of lower
Reynolds number and shorter tube length, the alternating oval tube performs slightly worse than its circular counterpart.

並列關鍵字

Double tube heat exchanger ； Alternating oval pipe ； CFD

參考文獻

[1] B.W. Webb and S. Ramadhyani, Conjugate Heat Transfer in a Channel with

Staggered Ribs, Int. J. Heat Mass Transfer, Vol. 28, pp. 1679-1687, 1985.

[2] S. Wang, Z.Y. Guo and Z.X. Li, Heat Transfer Enhancement by Using

Metallic Filament Insert in Channel Flow, Int. J. Heat Mass Transfer, Vol.

44, pp. 1373-1378, 2001.