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Physics Research InternationalVolume 2010 2010, Article ID 341016, 10 pages

Research Article

Academic Institute for Training Arab Teachers AITAT, Beit Berl College, Doar Beit Berl 44905, Israel

Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark

Received 19 September 2010; Accepted 1 November 2010

Academic Editor: Steven Sherwood

Copyright © 2010 Mahmoud Huleihil and Bjarne Andresen. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A finite-time generic model to describe the behavior of real refrigeration systems is discussed. The model accounts for finite heat transfer rates, heat leaks, and friction as different sources of dissipation. The performance characteristics are cast in terms of cooling rate versus coefficient of performance . For comparison purposes, various types of refrigeration-heat pump systems are considered: the thermoelectric refrigerator, the reverse Brayton cycle, and the reverse Rankine cycle. Although the dissipation mechanisms are different e.g., heat leak and Joule heating in the thermoelectric refrigerator, isentropic losses in the reverse Brayton cycle, and limits arising from the equation of state in the reverse Rankine cycle, the characteristic curves have a general loop shape. There are four limiting types of operation: open circuit in which both and vanish in the limit of slow operation; short circuit in which again and vanish but in the limit of fast operation; maximum ; maximum . The behavior of the considered systems is explained by means of the proposed model. The derived formulae could be used for a quick estimation of and the temperatures of the working fluid at the hot and cold sides.





Autor: Mahmoud Huleihil and Bjarne Andresen

Fuente: https://www.hindawi.com/



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