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研究生:盧柏伸
研究生(外文):Po-Shen Lu
論文名稱:利用最小平方有限元素法探討三維熱交換器中散熱圓管同軸及交錯排列對熱流場之影響
論文名稱(外文):Application of least-squares finite element method on the study of flow and heat transfer in a 3-D heat exchangers with in-lined and staggered tubes
指導教授:鄧志浩鄧志浩引用關係
指導教授(外文):Jyh-Haw Tang
學位類別:碩士
校院名稱:中原大學
系所名稱:土木工程研究所
學門:工程學門
學類:土木工程學類
論文種類:學術論文
論文出版年:2006
畢業學年度:94
語文別:中文
論文頁數:75
中文關鍵詞:最小平方有限元素法熱傳平板鳍片熱交換器
外文關鍵詞:plate-fin and tube heat exchangersLeast-squares finite element methodheat transferHeat exchanger
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中文摘要
本文主要模擬三維熱交換器中散熱圓管同軸或交錯排列之熱流場影響,其數值方法是利用最小平方有限元素法(LSFEM)進行數值分析。本研究針對同軸和交錯兩種散熱圓管〈4排〉不同的排列方式進行模擬,在固定鳍片間距為〈8 fins/in〉下,模擬過程中假設流體為穩態流場、不可壓縮流體,並且在層流的狀態下〈Re=200至600〉通過熱交換器。觀察兩種不同管排列方式對壓降、壓力係數、熱傳係數、局部紐賽數的影響。
由數值模擬結果證明,在平均熱傳係數上,散熱圓管以交錯排列的方式下,交錯排列的平均熱傳係數比同軸排列高10-30%,此外,在不同雷諾數下,與高雷諾數相比,低雷諾數的影響較大。在壓降方面,散熱圓管以交錯排列的方式下,交錯排列比同軸排列有較高的壓降;在散熱圓管表面同軸排列和交錯排列的壓力係數的變化,在90度左右有所差異,且此區域,交錯排列比同軸排列第二根至第四根散熱圓管表面的局部紐賽數高25%-50%。整體上,數值結果與實驗測量相符。
ABSTRACT
A numerical calculation procedure based on the least-squares finite element method (LSFEM) is employed to study the fluid flow and heat transfer in a 3-D heat exchangers with in-lined and staggered multiple–row (4 rows) tubes.
In this study, the fin pitch of the heat exchanger is 8 fins per inch and the fluid flow is assumed steady, incompressible, and laminar with Reynolds number ranging from 200 to 600.
In this paper the pressure drop, pressure coefficient, heat transfer coefficient, local Nusselt number and average Nusselt number for different geometric arrangements have been examined in detail.
The numerical results demonstrate that the average heat transfer coefficient of staggered arrangement is 10%-30% higher than that of the in-line one; also, it is effected more at low Reynolds number than at the high Reynolds number. The distribution of pressure drop of staggered array is higher than that of in-lined array. The variation of pressure coefficient at tube surface is dramatically for both the staggered and in-line arrangements for the angle less than 90 degree. The local Nusselt number of staggered array is higher 25%-50% than that of in-lined array for the tube row 2 to 4. Overall, the numerical results are in good agreement with the experimental measurement.
目錄
中文摘要 ………………………………………………I
英文摘要 ………………………………………………Ⅱ
致謝 ……………………………………………………Ⅲ
目錄 ……………………………………………………Ⅳ
圖目錄 …………………………………………………Ⅵ
符號說明 ………………………………………………Ⅸ
第一章 序論
1-1 研究動機 …………………………………………1
1-2 研究目的與方法 …………………………………2
1-3 文獻回顧 …………………………………………4
第二章 理論分析
2-1 歷史回顧 …………………………………………7
2-2 理論推導 …………………………………………8
2-3 控制方程式………………………………………10
第三章 模式建立與邊界條件給定
3-1 模型建立與網格產生……………………………21
3-2 邊界條件給定……………………………………23
3-3壓力係數與熱傳係數的計算 ……………………24
第四章 結果分析與討論
4-1三維熱交換器之流場分析及比較 ………………26
4-2散熱圓管表面之壓力係數與局部紐賽分佈 ……31
第五章 結論與建議
5-1 結論………………………………………………33
5-2 建議………………………………………………33
參考文獻………………………………………………35
圖目錄
圖3.1同軸排列散熱圓管之熱交換器示意圖[19] ………………………38
圖3.2交錯排列散熱圓管之熱交換器示意圖[19] ………………………38
圖3.3同軸排列之對稱的區域 ……………………………………………38
圖3.4交錯排列之對稱的區域 ……………………………………………38
圖3.5同軸排列散熱圓管之尺寸示意圖 …………………………………39
圖3.6交錯排列散熱圓管之尺寸示意圖 …………………………………39
圖3.7同軸排列散熱圓管之網格示意圖 …………………………………40
圖3.8交錯排列散熱圓管之網格示意圖 …………………………………40
圖3.9圓管周圍網格示意圖 ………………………………………………41
圖3.10同軸排列散熱圓管之邊界條件示意圖……………………………42
圖3.11交錯排列散熱圓管之邊界條件示意圖……………………………43
圖 4.1 同軸排列 z=0.5H 之速度分佈圖…………………………………44
圖 4.2 交錯排列 z=0.5H 之速度分佈圖…………………………………44
圖4.3同軸排列散熱圓管x-y平面之速度〈u〉向量分佈圖……………45
圖4.4交錯排列散熱圓管x-y平面之速度〈u〉向量分佈圖……………45
圖4.5同軸排列散熱圓管x-z平面之速度〈u〉向量分佈圖……………46
圖4.6交錯排列散熱圓管x-z平面之速度〈u〉向量分佈圖……………46
圖 4.7同軸排列 z=0.5H 之流線分佈圖 …………………………………47
圖4.8同軸排列 z=0.1H 之流線分佈圖 …………………………………47
圖4.9交錯排列 z=0.5H 之流線分佈圖 …………………………………48
圖4.10 交錯排列 z=0.1H 之流線分佈圖…………………………………48
圖4.11圓表面的壓力示意圖………………………………………………49
圖4.12 同軸排列 z=0.5H 之壓力分佈圖…………………………………50
圖4.13 交錯排列 z=0.5H 之壓力分佈圖…………………………………50
圖4.14 同軸排列 z=0.5H 之溫度分佈圖…………………………………51
圖4.15 同軸排列 z=0.1H 之溫度分佈圖…………………………………51
圖4.16 交錯排列 z=0.5H 之溫度分佈圖…………………………………52
圖4.17 交錯排列 z=0.1H 之溫度分佈圖…………………………………52
圖4.18同軸排列整體散熱圓管之速度分佈圖 ……………………………53
圖4.19同軸排列整體散熱圓管之壓力分佈圖 ……………………………54
圖4.20同軸排列整體散熱圓管之溫度分佈圖 ……………………………55
圖4.21交錯排列整體散熱圓管之速度分佈圖 ……………………………56
圖4.22交錯排列整體散熱圓管之壓力分佈圖 ……………………………57
圖4.23交錯排列整體散熱圓管之溫度分佈圖 ……………………………58
圖4.24 同軸排列 z=0.1H 之局部紐賽數分佈圖 …………………………59
圖4.25 交錯排列 z=0.1H 之局部紐賽數分佈圖 …………………………59
圖4.26 同軸排列散熱圓管表面之壓力係數分佈曲線圖 …………………60
圖4.27 交錯排列散熱圓管表面之壓力係數分佈曲線圖 …………………60
圖4.28 同軸排列散熱圓管表面之局部紐賽數分佈曲線圖 ………………61
圖4.29 交錯排列散熱圓管表面之局部紐賽數分佈曲線圖 ………………61
圖4.30 同軸排列散熱圓管表面之壓力係數分佈曲線圖[19] ……………62
圖4.31 交錯排列散熱圓管表面之壓力係數分佈曲線圖[19] ……………62
圖4.32 同軸排列散熱圓管表面之局部紐賽數分佈曲線圖[19] …………63
圖4.33 交錯排列散熱圓管表面之局部紐賽數分佈曲線圖[19] …………63
圖4.34交錯排列散熱圓管之平均熱傳係數分佈曲線圖 …………………64
圖4.35同軸排列與交錯排列之平均熱傳係數分佈曲線圖 ………………64
參考文獻
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4. M. Fujii, T. Fujii and T. Nagata, ”A numerical analysis of laminar flow and heat transfer of air in an in-line tube bank”, Numer. Heat Transfer 7, 89-102 (1984).
5. T. S. Wung and C. J. Chen, ”Finite analytic solution of convective heat transfer for tube arrays in crossflow-I. Flow field analysis ”, ASME J. Heat Transfer 111, 633-640 (1989).
6. T. S. Wung and C. J. Chen, ”Finite analytic solution of convective heat transfer for tube arrays in crossflow-II. Heat transfer analysis”, ASME J. Heat Transfer 111, 641-48 (1989).
7.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 96, 265-272 (1974).
8. 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 19, 41-49 (1976).
9. F. E. M. Saboya and E. M. Sparrow, ”Experiments on a three-row fin and tube heat exchanger”, J. Heat Transfer 98, 26-34 (1976).

10. D. G. Rich, ”The effect of fin spacing on the heat transfer and friction performance of multi-row plate fin-and-tube heat exchangers”, ASHRAE Trans. 17, 137-145 (1973).
11. D. G. Rich, ”The effect of the number of tube rows on the heat transfer performance of smooth plate and fin and tube heat exchangers”, A SHRAE Trans. 81, 307-317 (1975).
12. F. C. McQuiston, ”Correlation for heat, mass and momentum transport coefficients for plate-fin-tube heat transfer surfaces with staggered tube”, ASHRAE Trans. 84, 294-309 (1978).
13. D. L. Gray and R. L. Webb, ”Heat transfer and friction correlations for plate fin-and-tube heat exchangers having plain fins”, Proceedings of the Ninth International Heat Transfer Conference, San Francisco (1986).
14. F. C. McQuiston and J. D. Parker, Heating, ”Ventilating and Air
Conditioning Analysis and Design”, John Wiley, New York (1994).
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16. H. Yamashita, G. Kushida and R. Izumi, ”Fluid flow and heat transfer in a plate-fin and tube heat exchanger (Analysis of fluid flow around a square cylinder situated between parallel plates)”, Bull. JSME, 29(258),4185-4191 (1986).
17. A. Bastini, M. Fiebig and N. K. Mitra, ”Numerical studies of a compact fin-tube heat exchanger”, Proceedings of the EUROTHERM Seminar No.18, Design and Operation of Heat Exchangers, 27 February-1 March, pp. 154-163.Hamburg, Germany (1991).

18. F. Zdravistch, C. A. J. Fletcher and M. Behnia, ”Laminar and turbulent heat transfer predictions in tube banks in cross flow”, Proceedings of the Int. Conference on Fluid and Thermal Energy Conversion, pp. 29-34,12-15 December, Kutta-Denpasar, Indonesia (1994).
19. J. J. Jang, M. C. Wu, and W. J. Chang ,”Numerical and Experimental Studies of Three-Dimensional Plate-Fin-and Tube Heat Exchangers”, Int. J . Heat Mass Transfer, vol. 43, no. 14, pp. 3057–3066, (1996).
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