The duality of heat exchangers to act as both heat conductors and insulators when considering heat exchanger performance is studied from the viewpoint of entropy generation. By defining an appropriate index of the entropy generation rate, it is clarified that the performance paradox pointed out by Bejan can be resolved. The case of a balanced counter-flow system was examined and it has been shown that a heat exchanger can be regarded as both a heat conductor and a heat insulator in terms of entropy generation.

Issue Section:
Technical Notes
Keywords:
heat exchangers, heat conduction, thermal insulation, entropy, Analytical, Heat Transfer, Heat Exchangers, Second Law, Thermodynamics
Topics:
Entropy, Flow (Dynamics), Heat exchangers, Heat
1.
Bejan, A., 1995, Entropy Generation Minimization, CRC Press, Boca Raton, FL, pp. 124–126, Chap. 5
2.
Bejan, A., 1997, Advanced Engineering Thermodynamics, John Wiley and Sons, Inc., New York, pp. 604–609, Chap. 11
3.
Kakac¸, S., and Liu, H., 1998, Heat Exchangers: Selection, Rating, and Thermal Design, CRC Press, New York, pp. 59–61, Chap. 2
Copyright © 2003
 by ASME
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