殼管式熱交換器-熱源簡化模擬分析｜國立清華大學博碩士論文庫

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研究生：	張宏祥
論文名稱：	殼管式熱交換器-熱源簡化模擬分析
指導教授：	潘欽馮玉明
口試委員:	林清發
學位類別：	碩士 Master
系所名稱：	原子科學院 - 核子工程與科學研究所 Nuclear Engineering and Science
論文出版年：	2012
畢業學年度：	100
語文別：	中文
論文頁數：	155
中文關鍵詞：	殼管式熱交換器、FLUENT 、UDF 、孔隙度、計算流體力學
外文關鍵詞：	shell-and-tube heat exchanger, porous, UDF, FLUENT, Computational Fluid Dynamics (CFD)
相關次數：	點閱：2 下載：0
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本研究論述一殼管式熱交換器之熱源簡化模擬分析及其結果。核能電廠內核能級熱交換器包含蒸汽產生器、餘熱移除(Residual Heat Removal, RHR)系統熱交換器等，而核能級熱交換器尺寸往往龐大並且內部管路非常複雜，模擬所需電腦資源非常龐大，並且所耗時間非常多，因此本篇構想了一簡化式熱交換器之模擬研究，不但可以達到模擬之成果，並讓電腦資源及時間的使用更為經濟。
本文建立單一U形管與孔隙度熱交換器兩獨立模型，並撰寫五個使用者設定函數(UDF, User Defined Function)程式輔助CFD_FLUENT軟體運算，使兩獨立模型可互相進行資料交流，達到兩者熱交換的目的。根據研究結果，本篇所設計之簡化熱交換器，以新穎的熱源模擬方式，可因應不同U形管(管側端) 入口溫度及流量，在孔隙度熱交換器(殼側端)有相對應之熱源分佈，並達到理想之效益(effectiveness)分析，省下大量的電腦資源與模擬運行時間。
本文首先檢視簡化式熱交換器運算的結果，並與實體模型熱交換器的結果相互比較，進而探討管側與殼側兩端不同的入口溫度與流量對熱交換器效益的影響。研究成果顯示，增加管側進口溫度可迅速提升效益至高值，而效益也會因管側或殼側流量的不同，而有不同的變化趨勢。

This study conducts a simplified computer simulation about a shell-and-tube heat exchanger. A nuclear power plant has many different complicated heat exchangers, for example, the Residual Heat Removal system heat exchanger. Unfortunately, the size of these nuclear power plant heat exchangers is usually huge and with very complicated design. As we conduct a computer simulation as these one heat exchangers by computer, we often use a lot of computer resources, and spend much time. Therefore, we develop a simplified simulation. It not only can achieve the same objective, but also can significantly use less resources and time to simulate. Indeed, we demonstrate that this simplified simulation can significantly use less time than the full-scale simulation to achieve the same results employing the same computer.
The essence of this research is the simplified computer simulation. We build two independent models of a single U-tube and a porous heat exchanger and develop five User Defined Function programs (UDF) to make two models communicate with each other. The simulation is conducted using CFD_FLUENT. According to the U-tube (tube-side) situation, this simplified computer simulation can apply a source distribution to the porous heat exchanger (shell-side). After testing simulation through reasonable comparison with full-scale simulation, we employ it to study the heat exchanger effectiveness.
The simulation results reveal that the heat exchanger effectiveness significantly increases with increase the inlet temperature of tube side and has different tendencies with
iii
different tube side or shell side flow rate.

摘要 ..................................................................................................................................... i
ABSTRACT ........................................................................................................................ ii
致謝 ................................................................................................................................... iv
目錄 ................................................................................................................................... vi
表目錄 ............................................................................................................................... ix
圖目錄 ............................................................................................................................... xi
第一章 緒論 ....................................................................................................................... 1
1.1 研究背景與目的 .................................................................................................. 1
1.2 餘熱移除系統(RHR)介紹 ................................................................................... 3
1.2.1 餘熱移除系統熱交換器簡介 ................................................................... 4
1.3 文獻回顧 .............................................................................................................. 6
1.3.1 殼管式熱交換器 ....................................................................................... 6
1.3.2 孔隙度之相關研究 ................................................................................... 7
1.4 論文架構 .............................................................................................................. 9
第二章 理論模式與數值方法 ......................................................................................... 10
2.1 數值模擬軟體簡介 ............................................................................................ 10
2.2 基礎理論與統御方程式 .................................................................................... 14
2.3 數值方法 ............................................................................................................ 20
2.3.1 分離式求解器之求解過程 ..................................................................... 21
vii
2.3.2 有限體積法 ............................................................................................. 23
2.3.3 SIMPLE 演算法 ...................................................................................... 23
2.3.4 UDF簡介 ................................................................................................. 29
2.4 FLUENT 數值模擬設定流程圖 ........................................................................ 30
第三章 模型建立與運行 ................................................................................................. 31
3.1 研究流程與架構 ................................................................................................ 31
3.2 模型設計與網格建立 ........................................................................................ 34
3.3 格點測詴與壁面網格y+值測詴 ........................................................................ 41
3.4 孔隙度流阻係數計算與設定 ............................................................................ 43
3.5 實體模型與孔隙度模型比對 ............................................................................ 48
3.6 孔隙度模型之程式運行架構 ............................................................................ 54
3.7 User Defined Function (UDF)輔助程式撰寫 ..................................................... 56
3.7.1 Extfile UDF .............................................................................................. 56
3.7.2 tube_temp UDF ........................................................................................ 57
3.7.3 source UDF ............................................................................................... 57
3.7.4 HX_temp UDF ......................................................................................... 59
3.7.5 Tin UDF .................................................................................................... 59
3.8 FLUENT程式設定 ............................................................................................. 60
3.9 正常運轉模式與其它參數分析 ........................................................................ 63
3.9.1 正常運轉模式 ......................................................................................... 63
3.9.2 其他參數分析 ......................................................................................... 64
viii
3.10 模擬運行時間比較 .......................................................................................... 65
3.11 模擬結果 .......................................................................................................... 67
3.11.1 總壓降圖 ............................................................................................... 67
3.11.2 流場分佈圖 ........................................................................................... 68
3.11.3 溫度分佈圖 ........................................................................................... 68
第四章 結果與討論 ......................................................................................................... 71
4.1 無管壁之U形管模型與孔隙度熱交換器模型 ............................................... 71
4.1.1 正常運轉模式 ......................................................................................... 71
4.1.2 其它參數分析 ......................................................................................... 75
4.2 有管壁之U形管模型與孔隙度熱交換器模型 ............................................... 83
4.2.1 正常運轉模式 ......................................................................................... 83
4.2.2 其他參數分析 ......................................................................................... 84
第五章 結論與未來建議 ................................................................................................. 93
參考文獻 ........................................................................................................................... 95
附錄1. Extfile UDF 輔助程式碼 .................................................................................... 97
附錄2. tube_temp UDF程式碼 ....................................................................................... 98
附錄3. source UDF程式碼 ........................................................................................... 107
附錄4. HX_temp UDF程式碼 ...................................................................................... 138
附錄5. Tin UDF程式碼 ................................................................................................ 149
                                

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