In order to establish better performance compromises between the process functionals of a heat engine, in the context of finitetime thermodynamics (FTT), we propose some generalizations for the well known Efficient Power function through certain variables called "Generalization Parameters". These generalization proposals show advantages in the characterization of operation modes for an endoreversible heat engine model. In particular, with introduce the k-Efficient Power regime. For this obejctive function we find the performance of the operation of some power plants through the parameter k. Likewise, for plants that operate in a low efficiency zone, within a configuration space, the k parameter allow us to generate conditions for these plants to operate inside of a high efficiency and low dissipation zone. 05.70-Ln Nonequilibrium and irreversible thermodynamics; 84.60.Bk Performance characteristics of energy conversion system; figure of merit 89.30.-g Fossils fuels and nuclear power.

The fundamental issue in the energetic performance of power plants, working both as traditional fuel engines and as combined-cycle turbines (gas-steam), lies in quantifying the internal irreversibilities which are associated with the working substance operating in cycles. The purpose of several irreversible energy converter models is to find objective thermodynamic functions that determine operation modes for real thermal engines and at the same time study the trade-off between energy losses per cycle and the useful energy. As those objective functions, we focus our attention on a generalization of the so-called ecological function in terms of an ϵ parameter that depends on the particular heat transfer law used in the irreversible heat engine model. In this work, we mathematically describe the configuration space of an irreversible Curzon–Ahlborn type model. The above allows to determine the optimal relations between the model parameters so that a power plant operates in physically accessible regions, taking into account internal irreversibilities, introduced in two different ways (additively and multiplicatively). In addition, we establish the conditions that the ϵ parameter must fulfill for the energy converter to work in an optimal region between maximum power output and maximum efficiency points.

Due to one of the most representative contributions to the energy in diatomic molecules being the vibrational, we consider the generalized Morse potential (GMP) as a typical interaction for one‐dimensional microscopic systems, which describes local anharmonic effects. From the Eckart potential (EP) model, it is possible to find a connection with the GMP model, as well as obtaining the analytical expression for the energy spectrum because it is based on SOtrue(2,1true) algebras. This gives the macroscopic properties such as vibrational mean energy U, specific heat C, Helmholtz free energy F, and entropy S for a heteronuclear diatomic system, as well as with the exact partition function and its approximation for the high temperature region. Finally, a comparison is made between the graphs of some thermodynamic functions obtained with the GMP and the Morse potential (MP) for H Cl molecules.

Electric circuits with transient elements can be good examples of systems where non-steady irreversible processes occur; so in the same way as a steady-state energy converter, we use the formal construction of the first-order irreversible thermodynamic to describe the energetics of these circuits. In this case, we propose an isothermal model of two meshes with transient and passive elements, besides containing two voltage sources (which can be functions of time); this is a non-steady energy converter model. Through the Kirchhoff equations, we can write the circuit phenomenological equations. Then, we apply an integral transformation to linearize the dynamic equations and rewrite them in algebraic form, but in the frequency space. However, the same symmetry for steady states appears (cross effects). Thus, we can study the energetic performance of this converter model by means of two parameters: the “force ratio” and the “coupling degree”. Furthermore, it is possible to obtain characteristic functions (dissipation function, power output, efficiency, etc.). They allow us to establish a simple optimal operation regime of this energy converter. As an example, we obtain the converter behavior for the maximum efficient power regime.

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