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標題: 一個蛇行熱交換器之熱效率與第二定律效率之分析
Effectiveness and Second-Law Efficiency of a Serpentine Heat Exchanger
作者: 白凱莉
Pai, Kai-Li
關鍵字: serpentine heat exchanger
second-law efficiency
出版社: 機械工程學系所
引用: 1.J.Y. San, W.M. Worek, Z. Lavan, “Second-Law analysis of a two- dimensional regenerator”, Energy, Vol. 12, pp. 485-496, 1987. 2.P. Naphon, S. Wongwises, “A study of the heat transfer characteristic of a compact spiral coil heat exchanger under wet-surface conditions”, Experimental Thermal and Fluid Science, Vol. 29, pp. 511-521, 2005. 3.J.R. Burns, R.J.J. Jachuck, “Condensation studies using cross-corrugated polymer film compact heat exchanger”, Applied Thermal Engineering, Vol. 21, pp. 495-510, 2001. 4.J.Y. Jang, M.T. Wang, “Transient response of cross flow heat exchangers with one fluid mixed”, Heat and Fluid Flow, Vol. 8, pp. 182-186, 1987. 5.N.E. Wijeysundera, J.C. Hartnett, S. Rajaseker, “The effectiveness of a spiral coil heat exchanger”, International Communications in Heat and Mass Transfer, Vol. 23, pp. 623-632, 1996. 6.J.Y. San, C.L. Jan, “Second-law analysis of a wet cross flow heat exchanger”, Energy, Vol. 25, pp. 939-955, 2000. 7.T.J. Rennie, V.G.S. Raghavan, “Numerical studies of a double-pipe helical heat exchanger”, Applied Thermal Engineering, Vol. 26, pp. 1266-1273, 2006. 8.D.G. Prabhanjan, G.S.V. Raghavan, T.J. Rennie, “Comparison of heat transfer rates between a straight tube heat exchanger and a helically coiled heat exchanger”, International Communications in Heat and Mass Transfer, Vol. 29, pp. 185-191, 2002. 9.T.J. Rennie, V.G.S. Raghavan, “Experimental studies of a double-pipe helical heat exchanger”, Experimental Thermal and Fluid Science, Vol. 29, pp. 919-924, 2005. 10.P.K. Sahoo, Md.I.A. Ansari, A.K. Datta, “A computer based iterative solution for accurate estimation of heat transfer coefficients in a helical tube heat exchanger”, Journal of Food Engineering, Vol. 58, pp. 211-214, 2003. 11.V. Kumar, S. Saini, M. Sharma, “Pressure drop and heat transfer in tube-in-tube helical heat exchanger”, Chemical Engineering Science, Vol. 61, pp. 4403-4416, 2006. 12.S. Wongwises, M. Polsongkram, “Condensation heat transfer and pressure drop of HFC-134a in a helically coiled concentric tube-in-tube heat exchanger”, International Journal of Heat and Mass Transfer, Vol. 29, pp. 4386-4398, 2006. 13.C.Y. Park, P. Hrnjak, “Effect of heat conduction through the fins of a microchannel serpentine gas cooler of transcritical CO2 system”, International Journal of Refrigeration, Vol. 30, pp. 389-397, 2007. 14.B.A. Qureshi, S.M. Zubair, “Second-law-based performance evaluation of cooling towers and evaporative heat exchangers”, International Journal of Thermal Sciences, Vol. 46, pp.188-198, 2007. 15.A. Gupta, S.K. Das, “Second law analysis of crossflow heat exchanger in the presence of axial dispersion in one fluid”, Energy, Vol. 35, pp. 664-672, 2007. 16.S.Y. Wu, X.F. Yuan, Y.R. Li, L. Xiao, “Energy transfer effectiveness on heat exchanger for finite pressure drop”, Energy, Vol. 32, pp. 2110-2120, 2007. 17.W.M. Kays, A.L. London, Compact Heat Exchangers ( 3rd edition ), Mcgraw-Hill, 1984. 18.Y.A. Cengel, Heat Transfer ( 2nd edition ), Mcgraw-Hill, 2003. 19.A. Bejan, Advanced Engineering thermodynamics, John Wiley and Sons, 1988. 20.林俊憲,“一個蛇形管式交叉流熱交換器之性能測試”,碩士論文,中興大學機械系,2008。
摘要: 本研究採用一維之熱傳模式對一種蛇行熱交換器進行模擬分析,於分析模式中,管道外側之流體考慮為不混合之狀態,而於兩個相鄰之平行管道間流動,管道內側之流體則考慮為混合之狀態,而於矩形管道內持續地由入口回繞至出口。此熱交換器之熱效率可表示為整體熱容率比值(Ct*)、整體熱傳單位數(Ntuo)與管排數之函數,針對熱效率進行分析時發現,對一個固定之Ct*值而言,熱交換器之熱效率會隨著Ntuo值之上升而呈現先上升後微降之狀態。本研究亦針對此熱交換器進行熱力學第二定律之分析,以尋求最佳之操作條件,研究之結果顯示,當管內流體流經熱交換器後之出口溫度愈高,且管外流體流出熱交換器後之出口溫度愈低,此時熱交換器之第二定律效率會較大,且在一個固定之Ntuo値下,最佳之Ct*值約位於1.0之處。研究中亦分析兩個熱交換器經逆向串聯成ㄧ個新的熱交換器組之性能,分析之結果並與單個交換器之性能比較,結果顯示,此熱交換器組之熱效率與第二定律效率兩者均會明顯地上升。
This work adopted a one-dimensional model to analyze the performance of a serpentine heat exchanger which is composed of rectangular tubes. The fluid outside the tube is considered to be unmixed and it flows between two neighboring parallel tubes. The fluid inside the tube is considered to be mixed and it flows in a serpentine manner from the inlet to the exit. The effectiveness of the heat exchanger (ε) is presented as a function of ratio of heat capacitance rates (Ct*), overall number of transfer units (Ntuo) and number of tubes. For a fixed Ct* value, the initially increases with the Ntuo value. As the Ntuo value is large, it would slightly decrease with an increase of the Ntuo value. The second-law efficiency was also evaluated to search for optimum operating conditions. As the exit temperature of the tube-side fluid is higher and the exit temperature of the shell-side fluid is lower, the heat exchanger has a higher second-law efficiency value. For a fixed Ntuo value, the optimum Ct* value was found to be around 1.0. This work also analyzed the overall performance of two serpentine heat exchangers connected in series and in counterflow arrangement. As compared with a single serpentine heat exchanger, both the ε and the second-law efficiency can be largely upgraded.
其他識別: U0005-1408200814202000
Appears in Collections:機械工程學系所



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