Papers Published

1. Pons, M. and Bejan, A., Irreversibility in energy processes: non-dimensional quantification and balance, J. Non-Equilib. Thermodyn. (Germany), vol. 29 no. 2 (2004), pp. 157 - 75 [010] .
   (last updated on 2007/04/06)

   Abstract:
   The concept of thermodynamic efficiency (ratio of real cycle efficiency by Carnot efficiency) is well-known. The concept of numbers of entropy-production and of exergy-loss proposed by A. Bejan are also known, but rarely used. The present study firstly evidences that these two last numbers are actually identical, thus being a common number of irreversibility, independent of the method used for obtaining it. The study also evidences a non-dimensional irreversibility balance that applies to any energy conversion process. This balance correlates the thermodynamic efficiency of a whole process (which in most cases equals the exergetic efficiency) and the numbers of irreversibility of the different components or sub-processes involved in this process. Moreover, the basic additivity of entropy-productions and exergy-losses is maintained in this balance. This balance applies to the basic cycles (heat-engines, refrigerators, heat-pumps and heat-transformers), either workor heat-powered. It also applies to more complex cycles (heat-powered cycles consuming electricity, four-temperature heat-powered cycles, cogeneration processes), thus giving a robust framework for analyzing these cycles

   Keywords:
   cogeneration;entropy;heat engines;heat losses;heat pumps;irreversible thermodynamics;nonequilibrium thermodynamics;refrigeration;