Global Journal of Science Frontier Research, A: Physics and Space Science, Volume 23 Issue 1

New Applications of Non-Equilibrium Thermodynamics V. A. Etkin Abstract- We propose to extend the existing theory of irreversible processes (TIP) to include reversible real processes associated with the performance of useful work. This is achieved by the fact that the main quantities used by this theory, thermodynamic forces and fluxes, are derived not from the principle of increasing entropy, but rather from the law of the conservation of energy. This way of constructing TIP prevents the occurrence of thermodynamic inequalities and allows one to substantiate all its provisions without invoking the postulates and considerations of a molecular-kinetic and statistical-mechanical nature. This opens up the possibility of further reducing the number of empirical coefficients and expanding the scope of TIP applicability to nonlinear systems and states that are far from equilibrium, as well as to energy conversion processes which are primarily of interest to power engineers, technologists, biophysicists and astro-physicists. At the same time, the unity of the laws of transformation of all forms of energy and the difference between their equations, reciprocity relations and efficiency criteria from the generally accepted ones are proved. On this basis, a theory of similarity of power plants is proposed and their universal load characteristics are constructed, which make it possible to take the next step towards bringing the results of the thermodynamic analysis of their efficiency closer to reality. Keywords: thermodynamics, irreversibility, transfer and transformation, interrelation and similarity of processes, effects of superposition. I. I ntroduction n the history of science there are frequent cases when a new theory brought in significant change in the natural science paradigm. The last part of the twentieth century was no exception; as this paradigm shift occurred in the fundamental theories of the thermodynamics of irreversible processes (TIP). Researchers from many countries contributed to its creation [1-11]. It enriched the theoretical thought of the twentieth century with the "principle of reciprocity" of heterogeneous phenomena, sometimes called the "fourth law of thermodynamics", and explained the many effects that arise at the junctions of fundamental disciplines due to the simultaneous occurrence of several non-static processes. However, later on, interest in this theory began to fade. To a large extent this is due, in our opinion, to the fact that the basic quantities underlying this theory, thermodynamic forces X i and fluxes J i , are included on the basis of the principle of entropy increase, which exclude from consideration the reversible component of real processes. Yet it is precisely this component, connected to the execution of useful external work W e, which is of interest primarily in fields related to energy, technology, biophysics and astrophysics. This drawback can be eliminated by switching to finding these forces and fluxes on a basis of a more general law of conservation of energy. We shall consider the advantages that non equilibrium thermodynamics gains as a result. II. P reventing the T ransformation of E quations of T hermodynamics into I nequalities It is known that the equations of the 1st and 2nd laws of classical thermodynamics of open systems are combined in the form of the Gibbs relation[12]: dU = TdS - pdV + Σ k μ k dN k (1) This relation connects the internal energy U of the object (or system) under study with its entropy S , volume V and the number N k of moles of the k th substances, as well as with the generalized potentials ψ i conjugated with them (the chemical potentials of these substances is represented by μ k , absolute temperature by T and pressure p by . ), This then becomes the inequalities: Q ≠ TdS ; W p ≠ pdV ; W k ≠ μ k dN k (2) This happens because in non-equilibrium systems the parameters S , V , N k change not only as a result of external energy exchange, but also as a result of internal relaxation processes (the number of moles N k is due to chemical reactions; the volume V corresponds to the expanded form in a vacuum while not performing work; the entropy S is due to friction and other irreversible processes.) As a result, the energy exchange of the system with the environment can no longer be found on the basis of changes in these parameters, and the mathematical apparatus of thermodynamics based on equation (1) turns out to be inapplicable. This disadvantage can be eliminated by going directly to the fluxes of these energy carriers across the boundaries of the system. For this we use the law of conservation of energy in the form proposed by N. Umov (1873) [13]: dU/dt= −∮ · f , (3) I 1 Year 2023 9 © 2023 Global Journals Global Journal of Science Frontier Research Volume XXIII Issue ersion I VI ( A ) Author: Togliatti State University (Russia). e-mail: etkin.v@mail.ru