arXiv subjects

S. Levario-Medina

Publications and source records attributed to S. Levario-Medina.

4 recordsLinked to original sources

arXiv2020

Energetic optimization considering a generalization of the ecological criterion in traditional simple-cycle and combined cycle power plants

The fundamental issue in the energetic performance of power plants, working both as traditional fuel engines and as combined cycle turbine (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 works in an optimal region between maximum power output and maximum efficiency points.

physics.app-ph↗

arXiv2020

Local and global stability analysis of a Curzon-Ahlborn model applied to power plants working at maximum $k$-efficient power

The analysis of the effect of noisy perturbations on real heat engines, working on any steady-state regime has been a topic of interest within the context of Finite-Time Thermodynamics (FTT). The study of their local stability has been proposed through the so-called performance regimes: maximum power output, maximum ecological function, among others. Recently, the global stability analysis of an endoreversible heat engine was also studied taking into account the same performance regimes. We present a study of local and global stability analysis of power plant models (the Curzon-Ahlborn model) operating on a generalized efficient power regime called maximum k-efficient power. We apply the Lyapunov stability theory to construct the Lyapunov functions to prove the asymptotically stable behavior of the steady-state of intermediate temperatures in the Curzon-Ahlborn model. We consider the effect of a linear heat transfer law on the phase portrait description of real power plants, as well as the role of the $k$ parameter in the evolution of perturbations to heat flow. In general, restructured operation conditions show better stability in external perturbations.

physics.app-ph↗

arXiv2019

The $PΦ$-Compromise Function as a criterion of merit to optimize irreversible thermal engines

Several authors have proposed out of equilibrium thermal engines models, allowing optimization processes involving a trade off between the power output of the engine and its dissipation. These operating regimes are achieved by using objective functions such as the ecological function ($EF$). In order to measure the quality of the balance between these characteristic functions, it was proposed a relationship where power output and dissipation are evaluated in the above mentioned $EF$-regime and they are compared with respect to its values at the regime of maximum power output. We called this relationship "Compromise Function" and only depends of a parameter that measures the quality of the compromise. Thereafter this function was used to select a value of the mentioned parameter to obtain the generalization of some different objective functions (generalizations of ecological function, omega function and efficient power), by demanding that these generalization parameters maximize the above mentioned functions. In this work we demonstrate that this function can be used directly as an objective function: the "$PΦ$-Compromise Function" ($C_{PΦ}$), also that the operation modes corresponding to the maximum Generalized Ecological Function, maximum Generalized Omega Function and maximum Efficient power output, are special cases of the operation mode of maximum $C_{PΦ}$, having the same optimum high reduced temperature, then the characteristic functions will be the same in any of the above three working regimes, independent of the algebraic complexity of each generalized function. These results are presented for two different models of an irreversible energy converter: a non-endoreversible and a totally irreversible, both with heat leakage.

cond-mat.stat-mech↗

arXiv2018

Thermal optimization of Curzon-Ahlborn heat engines operating under some generalized efficient power regimes

In order to establish better performance compromises between the process functionals of a heat engine, in the context of finite time thermodynamics (FTT), we propose some generalizations for the well known Efficient Power function through certain variables called < >. 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 objective 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.

cond-mat.stat-mech↗