Abstract
This paper demonstrates the difference between the entropy generation number method proposed by Bejan and the method of entropy generation per unit amount of heat transferred in analyzing the thermodynamic performance of heat exchangers, points out the reason for leading to the above difference. A modified entropy generation number for evaluating the irreversibility of heat exchangers is proposed which is in consistent with the entropy generation per unit amount of heat transferred in entropy generation analysis. The entropy generated by friction is also investigated. Results show that when the entropy generated by friction in heat exchangers is taken into account, there is a minimum total entropy generation number while the NTU and the ratio of heat capacity rates vary. The existence of this minimum is the prerequisite of heat exchanger optimization.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Balic, B. and Selulic, D. “A Crossflow Compact Heat Exchanger of Minimum Irreversibility,” (in Serbo-Croatian) Termotehnika,4, pp.34–42, (1978).
Bejan, A., “The Concept of Irreversibility in Heat Exchanger Design: Counterflow Heat Exchangers for Gas-to-Gas Application,”Transactions of the ASME J. of Heat Transfer,99, pp.374–380, (1977).
Bejan, A. “General Criterion for Rating Heat Exchanger Performance,”Int. J. Heat Mass Transfer,21, pp.655–658, (1978).
Bejan, A. “Second Law Analysis in Heat Transfer,”Energy,5, pp.721–732, (1980).
Bejan, A. and Pfister, P.A. Jr., “Evaluation of Heat Transfer Augmentation Techniques Based on Their Impact on Entropy Generation,”Lett. Heat Mass Transfer,7, pp.97–106, (1980).
Bejan, A., «Entropy Generation Through Heat and Fluid Flow», Wiley-Interscience, New York, Chap. 7, (1982, 1994).
Bejan, A. “Second-Law Aspects of Heat Transfer Engineering,” in T.N. Veziroglu and Bergles, eds., Multi-Phae Flow and Heat Transfer III, 1A, Elsevier. Amsterdam, pp.1–22, (1984).
Bejan, A. «Advanced Eng. Thermodynamics», New York: J. Wiley, (1988).
Bergles, A.E. Bllumenkrantz, A.R. and Taborek, J. “Performance Evaluation Criteria for Enhanced Heat Transfer Surfaces,” Heat Transfer V-II 1974, The Japan Soc. Mech. Engr, pp.234–238, (1973).
Bergles, A.E. Bunn, R.L. and Junkhan, G.H. “Extended Performance Evaluation Criteria for Enhanced Heat Transfer Surfaces,”Letters Heat Mass Transfer,1, pp.113–120, (1974).
de Costa, C.E.S.M. and Saboya, F.E.M. “Second Law Analysis for Parallel Flow and Counterflow Heat Exchangers,” Proc. 8th Braz. Congr. Mech. Eng., Sao Jose dos Campos, S,P., Brazil, Dec., pp.185–187, (1985).
Demirel, Y. “Thermodynamic Optimization of Convective Heat Transfer in a Packed Duct,”Energy,20, No.10, pp.959–967, (1995).
Guo, Z.Y., «Thermofluid Dynamics», (in Chinese), Tsinghua University Press, (1992).
Huang, S.Y. The Heat Exchanger for Capturing Energy from Waste Heat (ORC Technology) VDI-Ber, No.539, pp.623–629, (1984).
Lanzhou Petroleum Machinery Institute, «Heat Exchangers», (in Chinese),1, China Petroleum and Chemical Engineering Press.
Ni, Z.W., “Second Law Analysis of Thermodynamics and Evaluation Method of Heat Exchanger,”J. of Engineering Thermophysics,6, No.4, pp.311–314, (1985).
Sarangi, S. and Chowdhury, K. “On The Generation of Entropy in a Counterflow Heat Exchanger,”Cryogenic,22, pp.63–65, (1982).
Sekulic, D.P. and Baclic, B.S. Enthalpy Exchange Irreversibility, Faculty of Technical Science, No.15, University of Nov., Sad. Yugoslavia, pp.113–123, (1984).
Sekulic, D.P. “Entropy Generation in A Heat Exchanger,”Heat Transfer Eng.,7, Nos.1–2, pp.83–88, (1986).
Sekulic, D.P. “Unequally Sized Passes in Two-Pass Crossflow Heat Exchangers: A Note in The Thermodynamic Approach to the Analysis,” Faculty of Technical Science, No.16, University of Nov. Sad. Yugoslavia, (1985-1986).
Sekulic, D.P., “The Second Law Quality of Energy Transformation in a Heat Exchanger,”ASME J. of Heat Transfer,112, pp.295–300, (1990).
Sekulic, D.P. and Nerman, C.V. “One Approach to Irreversibility Minimization in Compact Crossflow Heat Exchanger Design,”Int. Commun. Heat Mass Transfer,13, pp.23–32, (1986).
Zhukauskas, A.A., «Convective Heat Transfer in Heat Exchangers», Science Press, Moscow, (1982).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Xu, Z.M., Yang, S.R. & Chen, Z.Q. A modified entropy generation number for heat exchangers. J. of Thermal Science 5, 257–263 (1996). https://doi.org/10.1007/BF02653232
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02653232