Stationary open systems: A brief review on contemporary theories on irreversibility

Open systems are very important in science and engineering for their applications and the analysis of the real word. At their steady state, two apparently opposed principles for their rate of entropy production have been proposed: the minimum entropy production rate and the maximum entropy production, useful in the analysis of dissipation and irreversibility of different processes in physics, chemistry, biology and engineering. Both principles involve an extremum of the rate of the entropy production at the steady state under non-equilibrium conditions. On the other hand, in engineering thermodynamics, dissipation and irreversibility are analyzed using the entropy generation, for which there exist two principle of extrema too, the minimum and the maximum principle. Finally, oppositions to the extrema principle have been developed too. In this paper, all these extrema principles will be analyzed in order to point out the relations among them and a synthesis useful in engineering applications, in physical and chemical process analysis and in biology and biotechnology will be proposed.