本文透過實驗量測絕熱封閉空腔內水平鰭片溫度及空氣溫度，並搭配逆算法來估算鰭片平均熱傳系數，再將其結果與套裝軟體模擬比較。本文使用之逆算法為將鰭片分為多個子區域，將二維穩態熱傳導方程式以有限差分法離散，並以最小平方法收斂求得熱傳系數。本文之套裝軟體使用ANSYS ICEPAK 15進行模擬，透過與實驗之量測溫度、熱傳系數比較，得到適合的流動模型與網格，再透過速度流線圖及溫度分布圖分析其熱傳特性，結果顯示不同的網格及流動模式對結果影響甚大，尤其在不同流動模式之空腔內空氣溫度差異更加明顯。在實驗方面，透過改變熱壁與冷壁鰭片之間距及冷壁鰭片上之長度，探討其對空腔內熱傳特性影響。結果顯示，兩鰭片間距增加時，因流體速度增加，熱壁上平均熱傳系數也會上升，但上層空氣溫度之聚熱效果較為明顯。而冷壁鰭片長度增加，熱傳系數會下降，原因為當鰭片長度增加，雖冷壁鰭片可以改變空腔內之空氣溫度分布，增加冷壁吸收之熱量，但也造成了空腔內流體速度的下降，導致熱壁上之鰭片熱傳系數下降。

In this paper, the horizontal fin temperature and air temperature in the adiabatic cavity are measured experimentally, and the inverse scheme is used to estimate the average heat transfer coefficient of the fins, and then the results are compared with the software simulation. The inverse scheme is to divide the fins into multiple regions, discretize the two-dimensional steady-state heat conduction equation by the finite difference method, and use the least square method to converge to obtain the heat transfer coefficient. We use ANSYS ICEPAK 15 to simulate, compare with the measured temperature and heat transfer coefficient of the experiment, obtain a suitable flow model and grid, and then analyze its heat transfer characteristics through the velocity streamline and temperature distribution. By changing the distance between the hot wall and the cold wall fins and the length of the cold wall fins, the influence on the heat transfer characteristics in the cavity is discussed.

[1] F. Harahap, H. Lesmana, I. K. T. Arya Sume Dirgayasa, Measurements of heat dissipation from miniaturized vertical rectangular fin arrays under dominant natural convection conditions, Heat Mass Transfer, vol. 42(2006), pp.1025-1036,.
[2] Thamir K. Ibrahim, Marwah N. Mohammed, Mohammed Kamil Mohammed, G Najafi, Nor Azwadi Che Sidik, Firdaus Basrawi, Ahmed N Abdkka, S.S Hoseini, Experimental study on the effect of perforations shapes on vertical heated fins perforations under forced convection heat transfer, International Journal of Heat and Mass Transfer ,vol.118(2018), pp. 832-846
[3] X. Shi, J.M. Khodadadi, Laminar natural convection heat transfer in a differentially heated square cavity due to a thin fin on the hot wall, International Journal of Heat and Mass Transfer ,vol.125 (2003), pp. 624-634
[4] E. Bilgen, Natural convection in cavities with a thin fin on the hot wall, International Journal of Heat and Mass Transfer ,vol.48 (2005), pp. 3493-3505.
[5] F. Xu, J.C. Patterson, C. Lei, An experimental study of the unsteady thermal flow around a thin fin on a sidewall of a differentially heated cavity, International Journal Heat Fluid Flow, vol. 29 (2008), pp. 1139-1153
[6] F. Xu, J.C. Patterson, C. Lei, Transition to a periodic flow induced by a thin fin on the sidewall of a differentially heated cavity, International Journal of Heat and Mass Transfer, vol. 52 (2009), pp. 620-628
[7] F. Xu, J.C. Patterson, C. Lei, Transient natural convection flows around a thin fin on the sidewall of a differentially heated cavity, J. Fluid Mech., vol. 639 (2009), pp. 261-290
[8] F. Xu, J.C. Patterson, C. Lei, Effect of the fin length on natural convection flow transition in a cavity, International Journal of Thermal Sciences,vol.70 (2013) ,pp.92–101.
[9] J. Ma ,F. Xu, Unsteady natural convection and heat transfer in a differentially heated cavity with a fin for high Rayleigh numbers, Applied Thermal Engineering,vol.99(2016),pp. 625-634
[10] H.T. Chen, M.C. Lin,J.R Chang, Numerical and experimental studies of natural convection in a heated cavity with a horizontal fin on a hot sidewall, International Journal of Heat and Mass Transfer,vol.124(2018),pp.1217-1229
[11] S.A.Nada, Natural convection heat transfer in horizontal and vertical closed narrow enclosures with heated rectangular finned base plate, International Journal of Heat and Mass Transfer,vol. 50(2007),pp. 667-679
[12] C. Benseghir, S. Rahal, Simulation of heat transfer in a square cavity with two fin attached to the hot wall, Energy Procedia vol.18 (2012), pp.1299-1306.
[13] Wael Al-Kouz, Aiman Alshare, Suhil Kiwan, Ahmad Al Muhtady, Ammar Alkhalidi, Ammar Haneen Saadeh, Two-dimensional analysis of low-pressure flows in an inclined spuare cavity with two fins attached to the hot wall, International Journal of Thermal Sciences vol.126(2018), pp. 181-193
[14] E. Sparrow, A. Haji-Sheikh,T. Lundgren, The inverse problem in transient heat conduction , Journal of Applied Mechanics , vol. 31 (1964) , pp. 369-375,.
[15] S. Sunil, J. R. N. Reddy, C. Sobhan, Natural convection heat transfer from a thin rectangular fin with a line source at the base—a finite difference solution, Heat and Mass Transfer, vol. 31, pp. 127-135, 1996.
[16] N. Ainajem, M. Ozisik, A direct analytical approach for solving linear inverse heat conduction problems, ASME Transactions Journal of Heat Transfer, vol. 107, pp. 700-706, 1985.
[17] H. Ay, J. Jang, J. N. Yeh, Local heat transfer measurements of plate finned-tube heat exchangers by infrared thermography, International Journal of Heat and Mass Transfer, vol. 45, pp. 4069-4078, 2002.
[18] J. V. Beck, B. Litkouhi,C. S. Clair Jr, Efficient sequential solution of the nonlinear inverse heat conduction problem, Numerical Heat Transfer, Part A Applications, vol. 5, pp. 275-286, 1982.
[19] 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 Transf. vol. 109 (2017), pp. 378–392.
[20] H.T. Chen, Y.J. Chiu, C.S. Liu, J.R. Chang, Effect of domain boundary set on natural convection heat transfer characteristics for vertical annular finned tube heat exchanger, Int. J. Heat Mass Transf. vol.109 (2017), pp. 668–682.
[21] H.T. Chen, H.C. Tseng, S.W. Jhu, J.R. Chang, Numerical and experimental study of mixed convection heat transfer and fluid flow characteristics of plate-fin heat sinks, Int. J. Heat Mass Transf. vol.111 (2017), pp. 1050–1062.
[22] H.T. Chen, Y.L. Chang, P.Y. Lin, Y.J. Chui, J.R. Chang, Numerical study of mixed convection heat transfer for vertical annular finned tube heat exchanger with experimental data and different tube diameters, Int. J. Heat Mass Transf. vol.118 (2018), pp 931–947