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Comparison of Two Heat Transfer Enhancing Tubes for Boiling Heat Transfer
|關鍵字:||micro-carved cross helical threads;微刻紋線;fin;heat transfer coefficient;boiling;鰭片;熱對流係數;沸騰蒸發||出版社:||機械工程學系所||引用:|| B.W. Webb and S. Ramadhyani, Conjugate Heat Transfer in a Channel with Staggered Ribs, Int. J. Heat Mass Transfer, Vol. 28, pp. 1679-1687, 1985.  S. Wang, Z.Y. Guo and Z.X. Li, Heat Transfer Enhancement by Using Metallic Filament Insert in Channel Flow, Int. J. Heat Mass Transfer, Vol. 44, pp. 1373-1378, 2001.  S.B. Uttarwar and M.R. Rao, Augmentation of Laminar Flow Heat Transfer in Tubes by Means of Wire Coil Inserts, J. Heat Transfer, Vol. 107, pp. 930-935, 1985.  J.H. Royal and A.E. Bergles, Augmentation of Horizontal In-Tube Condensation by Means of Twisted-Tape Inserts and Internally Finned Tubes, J. Heat Transfer, Vol. 100, pp. 17-24, 1978.  J.L. Fernandez and R. Poulter, Heat Transfer Enhancement by Means of Flag-type Insert in Tubes, Int. J. Heat Mass Transfer, Vol. 30, pp. 2603-2609, 1987.  G.H. Junkhan, A.E. Bergles, V. Nirmalan and T. Ravigururajan, Investigation of Turbulators for Fire Tube Boilers, J. Heat Transfer , Vol. 107, pp. 354-360, 1985.  D.L. Gee and R.L. Webb, Forced Convection Heat Transfer in Helically Rib-Roughened Tubes, Int. J. Heat Mass Transfer, Vol. 23, pp. 1127-1136, 1980.  E.M. Sparrow, K.K. Koram and M. Charmchi, Heat Transfer and Pressure Drop Characteristics Induced by a Slat Blockage in a Circular Tube, J. Heat Transfer, Vol. 102, pp. 64-70, 1980.  R.L. Webb, E.R. Eckert and R.J. Goldstein, Heat Transfer and Friction in Tubes with Repeated-Rib Roughness, Int. J. Heat Mass Transfer, Vol. 14, pp. 601-617, 1971.  R. Sethumadhavan and M.R. Rao, Turbulent Flow Heat Transfer and Fluid Friction in Helical-Wire-Coil-Inserted Tubes, Int. J. Heat Mass Transfer, Vol. 26, pp. 1833-1845, 1983.  M. Molki and K.L. Bhamidipati, Enhancement of Convective Heat Transfer in the Developing Region of Circular Tubes Using Corona Wind, Int. J. Heat Mass Transfer, Vol. 47, pp. 4301-4314, 2004.  D.W. Zhou, Heat Transfer Enhancement of Copper Nanofluid with Acoustic Cavitation, Int. J. Heat Mass Transfer, Vol. 47, pp. 3109-3117, 2004.  W.Y. Cheng, C.C. Wang, Y.Z. Robert and L.W. Huang, Film Condensation of HCFC-22 on Horizontal Tubes, Int. Comm. Heat Mass Transfer, Vol. 23, No. 1, pp. 79-90, 1996.  V. Zimparov, Enhancement of Heat Transfer by a Tombination of a Single-Start Spirally Corrugated Tubes with a Twisted Tape, Exp. Thermal Fluid Sci, Vol. 25, pp. 535-546, 2002.  S.Y. Won and P.M. Ligrani, Comparisons of Flow Structure and Local Nusselt Numbers in Channels with Parallel-and Crossed-Rib Turbulators, Int. J. Heat Mass Transfer, Vol. 47, pp. 1573-1586, 2004.  S. Nozu, H. Honda and S. Nishida, Condensation of a Zeotropic CFC114-CFC113 Refrigerant Mixture in the Annulus of a Double-Tube Coil with an Enhanced Inner Tube, Exp. Thermal Fluid Sci., Vol. 11, pp. 364-371, 1995.  M. Goto N. Inoue and N. Ishiwatari, Condensation and Evaporation Heat Transfer of R410A inside Internally Grooved Horizontal Tubes, Int. J. Heat Mass Transfer, Vol. 24, pp. 628-638, 2001.  黃文傑，圓管內部突出環節之熱傳增強，國立中興大學機械工程研究所 碩士論文，2004。  王培堂，圓管內部連續突出環節對水流與管壁間之熱傳增強，國立中興大學機械工程研究所，碩士論文，2005。  M.-Y. Wen and C.-Y. Ho, Evaporation Heat Transfer and Pressure Drop Characteristics of R-290, R-600, and a Mixture of R-290/R-600 in the Three-lines Serpentine Small-tube Bank , J. Appl. Thermal Eng., Vol. 25, pp. 2921-2936, 2005.  E.P. Bandarra Filho and P.E.L. Barbieri, Flow Boiling Performance in Horizontal Microfinned Copper Tubes With the Same Geometric Characteristics, Exp. Therm. and Fluid Sci., Vol.35, pp. 832-840, 2011.  D. Khoeini, M.A. Akhavan-Behabadi, A.Saboonchi, Experimental Study of Condensation Heat Transfer of R-134a Flow in Corrugated Tubes With Different Inclinations, Int. J. Heat and Mass Transfer, Vol.39, pp. 138-143, 2012.  J.P. Solano, P.G. Vicente, A.Viedma, The Influence of Artificial Roughness Shape on Heat Transfer Enhancement: Corrugated Tubes, Dimpled Tubes and Wire Coils, J. Appl. Thermal Eng., Vol.35, pp. 196-201, 2012.  王啟川， 熱交換器設計(Ι)，第二版，五南圖書出版公司，2003.  S.J. Kline, F.A. McClintock, Describing Uncertainties in Single-sample Experiments, Mech. Eng., Vol.75, pp. 3-8, 1953.||摘要:||
本研究探討內部具微刻紋線(with micro-carved cross helical threads)及內部具鰭片模組(with fin-module insert)之兩支圓管之熱傳特性，實驗中以R-22冷媒在管內沸騰蒸發時，對兩者之熱傳性能分別進行量測。此實驗以直徑3 mm之矽膠電熱線纏繞於測試銅管之外壁，以進行等熱通量之加熱，在0.15、0.25、0.35、0.43 l/min四種不同之冷媒體積流率下及蒸發溫度固定在-12℃~-13℃之範圍內，分別對每一支測試管進行管壁溫度之量測，然後以量測之結果計算冷媒與管壁間相變化熱對流係數之大小，經獲得此兩支測試管之熱傳性能後，並將其與內部光滑 (smooth) 圓管之熱傳性能進行比較。由量測之結果發現，無論是內部具微刻紋線之圓管或內部具鰭片模組之圓管，在不同之冷媒體積流率下，其管壁溫度與冷媒蒸發溫度之溫差，均比內部光滑圓管之溫差為低，且分佈較均勻，因此兩者之熱對流係數亦均比內部光滑圓管之熱對流係數為大。在所考慮之四種冷媒蒸發量下，內部具鰭片模組之測試管為內部平滑圓管之1.76～2.4倍，內部具微刻紋線之測試管為內部平滑圓管的1.36～1.73倍。由以上量測分析之結果可以得知，兩支測試管均具有熱傳增強之效果，兩者均可改善蒸發器之熱傳性能。
This work investigated the heat transfer performance of two tubes. One is with a fin-module insert and the other is with internal micro-carved cross helical threads. In the experiment, R-22 refrigerant was the working fluid. The boiling heat transfer characteristics of the two test tubes were measured respectively. The external surfaces of the test tubes were wrapped with silicone electric-resistance heating wires for achieving a constant surface heat flux condition. The diameter of the wires is 3 mm. At the evaporation temperature in the range -12℃~-13℃and the volumetric flow rate of the refrigerant at 0.15、0.25、0.35、0.43 l/min, the heat transfer performance of the two tubes were tested. The acquired heat transfer data were compared to those of a smooth tube. The result shows that, at all the considered volumetric flow rates, the temperature differences between tube wall and refrigerant for the two test tubes are smaller than that for the smooth test tube. This means the heat transfer coefficients of both test tubes are higher than that of the smooth tube. The average heat transfer coefficients of the tube with fin-module insert are in the range 1.76～2.4 times of those of the smooth tube and the tube with internal micro-carved cross helical threads are in the range 1.36～1.73 times. Thus the heat transfer is enhanced for both test tubes. This implies that the two test tubes can be used to improve heat transfer performance of evaporators in refrigeration systems.
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