Keywords
thermal convexity
steady state
How to Cite
Abstract
This paper deals with the thermal convexity of heat exchangers in steady state: (Th,c(x)=γh,c(x)Tc,in+(1- γh,c(x))Th,in with 0 ≤ γh,c(x) ≤ 1). This method assesses the spatial distribution of the thermal convexity factors of both fluids along a tubular heat exchanger in counter-current flow and co-current flow arrangement. Analytical expressions of the thermal convexity coefficients are in exponential form. According to the flow configuration two linear functions are proposed for the hot and the cold fluid. The slope of these two functions corresponds to the exponential factor. The estimations of the exponential factor thanks to the steady state convexity coefficient profile provide results that are in good agreement with those obtained from correlations.
References
Kakaç S and Liu H. Heat Exchanger: Selection, Rating, and Thermal design, edn CRC Press LLC 2002.
Shah R. Advances in science and technology of compact heat exchangers. Heat Transfer Eng 2006; 27(5): 3-22. http://dx.doi.org/10.1080/01457630600559462
Serth RW. Heat Exchangers. In Serth RW, Lestina T, Eds. Process Heat Transfer. 2nd ed San Diego: Academic Press 2014; 67-100. http://dx.doi.org/10.1016/B978-0-12-397195-1.00003-0
Claesson J. Correction of logarithmic mean temperature difference in a compact brazed plate evaporator assuming heat flux governed flow boiling heat transfer coefficient, International J. of Refrigeration 2005; 28: 573-578. http://dx.doi.org/10.1016/j.ijrefrig.2004.09.011
Cui X, Chua KJ, Islam MR and Yang WM. Fundamental formulation of a modified LMTD method to study indirect evaporative heat exchangers, Energy Conversion and Management 2014; 88: 372-381. http://dx.doi.org/10.1016/j.enconman.2014.08.056
Noie SH. Investigation of thermal performance of an air-to-air thermosyphon heat exchanger using ε-NTU method. Appl Thermal Eng 2006; 26: 559-567. http://dx.doi.org/10.1016/j.applthermaleng.2005.07.012
Ranong CN and Roetzel W. Steady-state and transient behaviour of two heat exchangers coupled by a circulatingflowstream. International J of Thermal Sci 2002; 41: 1029-1043. http://dx.doi.org/10.1016/S1290-0729(02)01390-X
Fakheri A. Heat exchanger efficiency, ASME J. Heat Transfer 2007; 129(9): 1268-1276. http://dx.doi.org/10.1115/1.2739620
Fakheri A. Efficiency analysis of heat exchangers and heat exchanger network. Int J of Heat and Mass Transfer 2014; 76: 99-104. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2014.04.027
Patankar SV and Spalding DB. In Heat exchangers, ed Afgan and Schlinder. 155-175. McGraw-Hill: New York 1974.
Rohsenow WM, Hartnett JP and Ganic EN. Handbook of heat transfer applications, edn Mc Graw Hill: New York 1985.
Incropera FP and DeWitt DP. Fundamentals of Heat and Mass Transfer 4th ed, John Wiley: New York 1996.
Kays WM and London AL. Compact Heat Exchangers, 3d ed., McGraw Hill: New York 1998.
Sieder EN and Tate GE. Heat Transfer and Pressure Drop of Liquids in Tubes. Ind Eng Chem 1936; 28(12): 1429-1435. http://dx.doi.org/10.1021/ie50324a027
Jacob LM. Heat Transfer, Vol 1, John Wiley: New York 1964.
Kawamura H. Analysis of Transient Turbulent Heat Transfer in an Annulus: Part I: Heating Element with a Finite (Nonzero) Heat Capacity and no Thermal Resistance. Trans JSME 1973; 39(324): 2498-2507. http://dx.doi.org/10.1299/kikai1938.39.2498
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Copyright (c) 2015 M.A. Abdelghani-Idrissi, D. Seguin, L. Vernières, N. Mouhab