殼管式熱交換器-熱源簡化模擬分析

張宏祥

指導教授 ： 潘欽 ； 馮玉明

國立清華大學/原子科學院/核子工程與科學研究所/碩士(2012年)

https://doi.org/10.6843/NTHU.2012.00363

摘要

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。

關鍵字

殼管式熱交換器 ； FLUENT ； UDF ； 孔隙度 ； 計算流體力學

並列摘要

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.

並列關鍵字

shell-and-tube heat exchanger ； porous ； UDF ； FLUENT ； Computational Fluid Dynamics (CFD)

參考文獻

[3] H. Li and V. Kottke, "Analysis of local shellside heat and mass transfer in the shell-and-tube heat exchanger with disc-and-doughnut baffles," International Journal of Heat and Mass Transfer, vol. 42, pp. 3509-3521, 1999.

[4] S. Wang, J. Wen, and Y. Li, "An experimental investigation of heat transfer enhancement for a shell-and-tube heat exchanger," Applied Thermal Engineering, vol. 29, pp. 2433-2438, 2009.

[5] Y. Li, X. Jiang, X. Huang, J. Jia, and J. Tong, "Optimization of high-pressure shell-and-tube heat exchanger for syngas cooling in an IGCC," International Journal of Heat and Mass Transfer, vol. 53, pp. 4543-4551, 2010.

[6] S. Ergun, "Fluid Flow through Packed Columns," Chem. Eng. Prog., vol. 48, pp. 89-94, 1952.

[8] S. L. Lee and J. H. Yang, "Modeling of Darcy-Forchheimer drag for fluid flowacross a bank of circular cylinders," International Journal of Heat and Mass Transfer, vol. 40, pp. 3149-3155, 1997.