本文主旨為利用數值方法模擬內含懸浮微粒之矩型熱虹迴路之共軛熱傳現象，藉以探討懸浮相變化 (PCM) 微粒對矩形熱虹系統熱傳特性之影響。數值模擬所考慮相關參數及其範圍為：管壁外徑比 ro = 1 ~ 1.5 、管壁與流體熱傳導係數比 = 0.1 ~ 100，次冷參數 Sc = 0 ~ 2，PCM微粒之體積濃度 cv = 0 ~ 0.1，修正萊里數 Ra* = 107 ~ 1010，修正史蒂芬數 Ste* = 0.01 ~ 0.1，PCM微粒半徑比 rp = 0.01 ~ 0.046。結果發現在不考慮管壁熱傳導效應下濃度、修正萊里數及修正史蒂芬數對迴路熱傳影響甚鉅，而次冷參數則可用來控制溫度分布範圍。至於管壁熱傳導效應，則顯示迴路內藉懸浮流體輸送熱量比例隨ro值增加而降低，導致上述無因次化參數影響變小；而迴路整體溫度呈現隨 增加而降低之趨勢。

This study aims to investigate numerically the conjugate heat transfer characteristics of phase-change-material (PCM) suspensions in a rectangular loop of thermosyphon. Wall conduction of the loop as well as the axial conduction of PCM suspensions are taken into account. Numerical simulations have been undertaken for the pertinent dimensionless parameters in the ranges as follows: the loop wall radius ratio ro = 1 ~ 1.5, the thermal conductivity ratio of wall to the suspending fluid = 0.1 ~ 100, the sub-cooling factor Sc = 0 ~ 2, the concentration of PCM particles cv = 0 ~ 0.1, the modified Rayleigh number Ra* = 107 ~ 1010, the modified Stefan number Ste* = 0.01 ~ 0.1, and the radius ratio of PCM particle rp = 0.01 ~ 0.046. The result show that the convection heat transfer behaviors of PCM suspensions in the rectangular loop can be strongly affected by the modified Rayleigh number, the modified Stefan number, as well as the concentration of PCM particles. Contribution due to the PCM suspensions to the heat transfer at the cold section of the loop is found to degrade markedly with the increase of the wall thickness. Moreover, the increase of the thermal conductivity ratio tends to lower the temperature of the entire loop system.

1. D. Japilse, “Advances in thermosyphon technology,” Advances in Heat Transfer, edited by T. F. Irvine, Jr.and J. P. Hartnett, Vol. 9, Academic Press, New York, pp. 1-111, 1973.
2. B. J. Huang and R. Zelaya, ‘‘Heat transfer behavier of a rectangular thermosyphon loop,’’ ASME J. of Heat Transfer, Vol. 110, pp. 487-493, 1988.
3. M. A. Bernier and B. R. Baliga, ‘‘A 1-D/2-D model and experiment results for a closed-loop thermosyphon with vertical heat transfer sections,’’ Int. J. Heat Mass Transfer, Vol. 35, No. 11, pp. 2696-2982, 1982.
4. A. Mertol, R. Greif and Y. Zvirin, ‘‘Two-dimensional study of heat transfer and fluid flow in a natural convection loop,’’ ASME J. of Heat Transfer, Vol.104, pp. 508-514, 1982.
5. A. Metrol and R. Greif, ”A review of natural circulation loops,” Natural Convection, edited by S. KaKac, W. Aung, and R. Viskanta, Hemisphere Publishing, New York, pp. 1033-1071, 1985.
6. R. Greif, “Natural circulation loops”, ASME J. Heat Transfer, Vol. 110, pp. 1243-1258, 1988.
7. Y. Su and Z. Chen, ‘‘2-D numerical study on a rectangular thermosyphon with vertical or horizontal heat transfer sections,’’ Int. J. Heat Mass Transfer, Vol. 38, No. 17, pp. 3313-3317, 1995.
8. C. J. Ho, S. P. Chiou and C. S. Hu, ‘‘Heat transfer characteristics of a rectangular natural circulation loop containing water near its density extreme,’’ Int. J. Heat Mass Transfer, Vol. 40, No. 15, pp. 3553-3558, 1997.
9. M. Misale and M. Forgheri, “Influence of pressure drops on the behavior of a single-phase natural circulation loop：preliminary results,” Int. Comm. Heat Transfer, Vol. 26, No. 5, pp. 597-606, 1999.
10. M. Misale, P. Ruffino and M. Forgheri, “The influence of the wall thermal capacity and axial conduction over a single-phase natural circulation loop：2-D numerical study,” Heat and Mass Transfer, Vol. 36, pp. 533-539, 2000.
11. B. P. Leonard, ‘‘A stable and accurate convective modeling procedure based on quadratic upstream interpolation,’’ Comput. Meth. Appl. Mech. Engng., Vol. 19, pp.59-98, 1979.
12. 許恆毅，”內含相變化微粒之封閉熱虹迴路熱傳特性研究”，國立成功大學機械工程研究所碩士論文，2000。
13. M. Goel, S. K. Roy and S. Sengupta, “Laminar forced conduction heat transfer in micro-capsulated phase change material suspensions,” Int. J. Heat Mass Transfer, Vol. 37, No. 4, pp. 593-604, 1994.
14. P. Charunyakorn, S. Sengupta and S. K. Roy, ‘‘Forced convection heat transfer in microencapsulated phase change material slurries：flow in circular ducts,’’ Int. J. Heat Mass Transfer, Vol. 34, No. 3, pp. 819-833, 1991.
15. 黃朝揚，”矩形容器內含懸浮相變化微粒之自然對流研究”，國立成功大學機械工程研究所碩士論文，2001