臺灣博碩士論文加值系統

本文以三維CFD軟體配合逆算法及實驗溫度來求得方形與H型之板鰭管式熱交換器於矩形流道的混合對流熱流特性，探討入口風速、鰭片間距及鰭片長度之影響。由於空氣流經板鰭管式熱交換器時會產生複雜三維流動，使得鰭片上的熱傳係數非均勻分布，故劃分數個子區域並設定其熱傳係數為常數，使用差分法搭配最小平方法，進行逆向求解，取得逆算之鰭片熱傳參數後，引用相關文獻作比較，接著，以非線性回歸方法取得H型鰭片之關係式；本文利用CFD軟體求得溫度場、流場及熱傳參數，輔以實驗數據與逆算結果對紊流模式及網格劃分進行選用，確保模擬之可信度；結果顯示風速提升將改變紊流模式選用，在較高速時，Enhanced Realizable k-ε比RNG k-ε紊流模式更符合逆算結果；在本研究參數範圍內，隨風速加快、間距增大及長度變小會使熱傳係數提升，對應各參數變化之趨勢也會有所不同；此外，H型與方形鰭片相比，熱傳係數增幅比最高可達18.4%，而其溝槽設計造成局部熱傳增益機制在本文中將被探討。

This study uses three-dimensional computational fluid dynamics (CFD) numerical simulation along with inverse method and experimental temperature data to investigate the mixed convection heat transfer and flow characteristics of H-type finned tube heat exchanger in a rectangular tunnel. The effects of three parameters including inlet velocity Va, fin spacing S and fin length L are examined. The inverse method in conjunction with finite difference method and least-squares scheme are applied to predict the heat transfer characteristics, then compare those with the existing correlations, utilize the non-linear regression technique to obtain the practical correlation for Nusselt number, which is in good agreement with the inverse results. The temperature contour, streamline and heat transfer characteristics are determined by CFD. In order to obtain more accurate and reliable numerical results, the selection of flow models and mesh system must match temperature data and inverse results. It is found that enhanced realizable k-ε turbulence model is more suitable for higher inlet velocity than RNG k-ε. With the increase of inlet velocity and fin spacing, or the decrease of fin length, the heat transfer coefficient increases. The H-type finned tube is performed with an improvement of the heat transfer coefficient by 18.4%. Finally, the thermal-and-flow mechanism of the local heat transfer enhancement around the groove can be observed.

摘要 I
Extend Abstract II
誌謝 XVI
目錄 XVII
表目錄 XIX
圖目錄 XXII
符號說明 XXV
第一章 緒論 1
1-1 研究背景 1
1-2 文獻回顧 3
1-3 研究目的與方法 7
1-4 本文架構 8
第二章 逆算法之理論與建構過程 10
2-1 簡介 10
2-3 鰭片之差分方程組 11
2-2 物理模型與對應邊界 15
2-4 逆向熱傳導問題 18
第三章 實驗操作與逆算結果 21
3-1 簡介 21
3-2 實驗設備 23
3-3 實驗組別與步驟 27
3-4 實驗與逆算結果 30
第四章 三維CFD軟體模擬 52
4-1 簡介 52
4-2 基本假設 53
4-3 計算區域之邊界條件 55
4-4 流動模式之統御方程組 58
4-4-1 Zero-equation紊流模式 59
4-4-2 RNG k-ε紊流模式 60
4-4-3 Realizable k-ε紊流模式 62
4-4-4 近壁處理方法 64
4-5 求解程序與策略分析 67
4-5-1 紊流模式測試 69
4-5-2 網格測試 82
第五章 結果與討論 93
5-1 簡介 93
5-2 入口風速變化的影響 94
5-3 鰭片間距變化的影響 96
5-4 鰭片長度變化的影響 98
第六章 結論與建議 136
6-1 綜合結論 136
6-2 建議與未來發展 138
參考文獻 140

[1]F.E.M. Saboya and E.M. Sparrow, Local and average transfer coefficients for one-row plate fin and tube heat exchanger configurations, ASME J. Heat Transfer, vol. 96, pp. 265-272, 1974.
[2]F.E.M. Saboya and E.M. Sparrow, Transfer characteristics of two-row plate fin and tube heat exchanger configurations, Int. J. Heat Mass Transfer, vol. 19, pp. 41-49, 1976.
[3]E.C. Rosman, P. Carajilescov and F.E.M. Saboya, Performance of one- and two-row tube and plate fin heat exchanger, ASME J. Heat Transfer, vol. 106, pp. 627-632, 1984.
[4]R. Romero-Mendez, M. Sen, K.T. Yang and R. McClain, Effect of fin spacing on convection in a plate fin and tube exchanger, Int. J. Heat Mass Transfer, vol. 43, pp. 39-51, 2000.
[5]M. Tutar and A. Akkoca, Numerical analysis of fluid flow and heat transfer characteristics in three-dimensional plate fin-and tube heat exchangers, Numer. Heat Transfer A, vol. 46, pp. 301-321, 2004.
[6]B. Şahin, A. Akkoca, N.A. Öztürk and Akilli, Investigation of flow characteristics in a plate fin and tube heat exchanger model composed of single cylinder, Int. J. Heat Fluid Flow, vol. 27, pp. 522-530, 2006.
[7]B. Şahin, N.A. Öztürk, C. Ozalp and C. Canpolat, PIV measurements of flow through normal triangular cylinder arrays in the passage of a model plate-tube heat exchanger, Int. J. Heat Fluid Flow, vol. 61, pp. 531-544, 2016.
[8]C.C. Wang and K.Y. Chi, Heat transfer and friction characteristics of plain fin-and-tube heat exchangers, Part I: New experimental data, Int. J. Heat Mass Transfer, vol. 43, pp. 2681-2691, 2000.
[9]C.C. Wang and K.Y. Chi, Heat transfer and friction characteristics of plain fin-and-tube heat exchangers, Part II: Correlation, Int. J. Heat Mass Transfer, vol. 43, pp. 1651-1659, 2000.
[10]H.T. Chen and W.L. Hsu, Estimation of heat-transfer characteristics on a vertical annular circular fin of finned-tube heat exchangers in forced convection, Int. J. Heat Mass Transfer, vol. 51, pp.1920-1932, 2008.
[11]H.T. Chen, J.C. Chou and H.C. Wang, Estimation of heat transfer coefficient on the vertical plate fin of finned-tube heat exchangers for various air speeds and fin spacings, Int. J. Heat Mass Transfer, vol. 50, pp. 45-57, 2007.
[12]H.T. Chen and J.R. Lai, Study of heat-transfer characteristics on the fin of two-row plate finned-tube heat exchangers, Int. J. Heat Mass Transfer, vol. 50, pp. 45-57, 2012.
[13]C.H. Huang, I.C. Yuan and H. Ay, A three-dimensional inverse problem in imaging the local heat transfer coefficients for plate finned-tube heat exchangers, Int. J. Heat Mass Transfer, vol. 46, pp. 3629-3638, 2003.
[14]C.H. Huang, I.C. Yuan and H. Ay, An experimental study in determining the local heat transfer coefficients for the plate finned-tube heat exchangers, Int. J. Heat Mass Transfer, vol. 52, pp. 4883-4893, 2009.
[15]B. Watel, S. Harmand and B. Desmet, Influence of flow velocity and fin spacing on the forced convective heat transfer from an annular-finned tube, JSME Int. J., Ser. B, vol. 42, pp. 56-64, 1999.
[16]C.W. Lu, J.M. Huang, W.C. Nien and C.C. Wang, A numerical investigation of the geometric effects on the performance of plate finned-tube heat exchanger, Energy Conversion Management, vol. 52, pp. 1638-1643, 2011.
[17]M.S. Mon and U. Gross, Numerical study of fin-spacing effects in annular-finned tube heat exchangers, Int. J. Heat Mass Transfer, vol. 47, pp. 1953-1964, 2004.
[18]A. Kumar, J.B. Joshi, A.K. Nayak and P.K. Vijayan, 3D CFD simulations of air cooled condenser-III: Thermal–hydraulic characteristics and design optimization under forced convection conditions, Int. J. Heat Mass Transfer, vol. 93, pp. 1227-1247, 2016.
[19]H.T. Chen, Y.S. Lin, P.C. Chen and J.R. Chang, Numerical and experimental study of natural convection heat transfer characteristics for vertical plate fin and tube heat exchangers with various tube diameters, Int. J. Heat Mass Transfer, vol. 100, pp. 320-331, 2016.
[20]H.T. Chen, Y.J. Chiu, C.S. Liu, J.R. Chang, Numerical and experimental study of natural convection heat transfer characteristics for vertical annular finned tube heat exchanger, Int. J. Heat Mass Transfer, vol. 109, pp. 378-392, 2017.
[21]V. Glazar, A. Trp and K. Lenic, Numerical study of heat transfer and analysis of optimal fin pitch in a wavy fin-and-tube heat exchanger, Heat Transfer Eng., vol. 33(2), pp. 88-96, 2012.
[22]B. Lotfi, M. Zeng, B. Sundén and Q.W. Wang, 3D numerical investigation flow and heat transfer characteristics in smooth wavy fin-and-elliptical tube heat exchangers using new type vortex generators, Energy, vol. 73, pp. 233-257, 2014.
[23]Y. Jin, G.H. Tang, Y.L. He and W.Q. Tao, Parametric study and field synergy principle analysis of H-type finned tube bank with 10 rows, Int. J. Heat Mass Transfer, vol. 60, pp. 241-251, 2013.
[24]H. Wang, Y.W. Liu, P. Yang, R.J. Wu and Y.L. He, Parametric study and optimization of H-type finned tube heat exchangers using Taguchi method, Appl. Therm. Eng., vol. 103, pp. 128-138, 2016.
[25]J.Y. Yun and K.S. Lee, Influence of design parameters on the heat transfer and flow friction characteristics of the heat transfer with slit fins, Int. J. Heat Mass Transfer, vol. 43, pp. 2529-2539, 2000.
[26]L. Ma, F. Li and J. Liu, Experimental research on H-type elliptical finned tubes in low temperature boiler gas flue, Int. J. Simulation: Systems, Sci. and Tech., 2016.
[27]M.B. Cutlip and M. Shacham, Problem Solving in Chemical and Biochemical Engineering with POLYMATH, Excel, and MATLAB, Prentice Hall, Israel, 2008.
[28]M.N. Özişik and H.R.B. Orlande, Inverse Heat Transfer: Fundamentals and Applications, Taylor ＆ Francis, New York, 2000.
[29]A.N. Tikhonov and V.Y. Arsenin, Solution of Ill-posed Problems, V.H. Winston ＆ Sons, Washington, DC, 1977.
[30]O.M. Alifanov, Inverse Heat Transfer Problem, Springer-Verlag, Berlin, 1994.
[31]J.V. Beck and B. Blackwell, C.R. St. Clair, Inverse Heat Conduction: Ill-Posed Problems, Wiley Interscience, New York, 1985.
[32]A. Bejan, Heat Transfer, John Wiley ＆ Sons, Inc., pp. 53-62, 1993.
[33]林子祥，預測板鰭式熱沉於各種矩形外殼內之熱傳特性，國立成功大學機械工程學系，碩士論文，2015。
[34]H. Chen, Q. Zhao, Y.Wang, H. Ma, Y. Li and Z. Chen, Experimental study on heat transfer and resistance characteristics of H-type finned tube, Int. Conference on Industrial Electronics Applications, pp. 362-366, 2015.
[35]林詠翔，具不同管徑之板鰭管式熱交換器的熱傳特性研究，國立成功大學機械工程學系，碩士論文，2016。
[36]曾竑嘉，具各種鰭片形狀之板鰭管式熱交換器的自然對流熱傳特性的數值與實驗研究，國立成功大學機械工程學系，碩士論文，2017。
[37]Q. Chen and W. Xu, A zero-equation turbulence model for indoor airflow simulation, Energy and Buildings, vol. 28, pp. 137-144, 1998.
[38]V. Yakhot, S.A. Orszag, S. Thangam, T.B. Gatski and C.G. Speziale, Development of turbulence models for shear flows by a double expansion technique, Physics of Fluids A, vol. 4, pp. 1510-1520, 1992.
[39]T.H. Shih, W.W. Liou, A. Shabbir, Z. Yang and J. Zhu, A New k-ε Eddy Viscosity Model for High Reynolds Number Turbulent Flows - Model Development and Validation, Computers Fluids, vol. 24(3), pp. 227-238, 1995.
[40]B.E. Launder and D.B. Spalding, The numerical computation of turbulent flows, Computer Methods in Applied Mechanics Eng., vol. 3, pp. 269-289, 1974.