A graphic approach to include dissipative-like effects in reversible thermal cycles

González-Ayala, Julián; Arias-Hernandez, L. A.; Angulo‐Brown, F.

doi:10.1140/epjb/e2017-80001-4

Cited by 5 publications

(2 citation statements)

References 29 publications

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“…Thus, the heat-leak is the part of the dissipated heat to the cold reservoir that has not an endoreversible origin in the CL model. The term Q endo c, loss is very similar to the one obtained in the so-called "geometric dissipation" [61], where a dissipation-like term can be attached to a reversible cycle if one subtracts the heat released by a Carnot cycle from the heat released by the reversible cycle, when both cycles operate between the same heat reservoirs and with the same heat input.…”

Section: Correspondence Between the Re's Variables Of Both Modelsmentioning

confidence: 70%

Entropy generation and unified optimization of Carnot-like and low-dissipation refrigerators

et al. 2018

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The connection between Carnot-like and low-dissipation refrigerators is proposed by means of their entropy generation and the optimization of two unified, compromise-based figures of merit. Their optimization shows that only a limited set of heat transfer laws in the Carnot-like model are compatible with the results stemming from the low-dissipation approximation, even though there is an agreement of the related physical spaces of variables. A comparison between two operation regimes and relations among entropy generation, efficiency, cooling power. and power input are obtained, with emphasis on the role of dissipation symmetries. The results extend previous findings for heat engines at maximum power conditions.

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Section: Correspondence Between the Re's Variables Of Both Modelsmentioning

confidence: 70%

Entropy generation and unified optimization of Carnot-like and low-dissipation refrigerators

et al. 2018

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“…In this context, the combined cycle power plants in whose construction coexist two thermodynamic cycles from the same source of heat, have turned out to have a greater amount of available energy. Although in practice, the amount of non useful energy generated compared to the used one continues to be a big problem, it can be modulated (reduced) by paying attention to the operation regimes [10,11,12] with which this type of power plants can be operated. These regimes are normally associated with operation and design parameters that measure qualitatively the internal and external irreversibilities.…”

Section: Introductionmentioning

confidence: 99%

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

Levario-Medina,

Valencia-Ortega,

Barranco-Jiménez

2020

Preprint

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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. Several irreversible models of energy converters have been studied under different contexts of non-equilibrium thermodynamics, their purpose is to find objective thermodynamic functions that determine more realistic bounds for real energy converters and at the same time reduce energy losses per cycle. As these objective functions characterize specific operation regimes, we focus our attention in one generalization of the so-called ecological function in terms of a generalizing parameter ( ) which can be related not only to a large number of accessible operation modes, but also to parameters representing both internal and external irreversibilities in models of power plants. In this work, we conclude the characteristic loops in the power output-efficiency space can be sketched, for either of the two irreversible heat engine models considered with heat leak. We found out that from a set of loops related to the physical constraints, the above systems work as heat engines and their operating conditions lie in 3 particular zones. The optimum zone featured by high power output and high efficiency is characterized through a relation between the irreversibility degrees and the constraints-parameters.

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Ecological efficiency of finite-time thermodynamics: A molecular dynamics study

et al. 2018

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We present a molecular dynamics simulation of a two-dimensional Carnot engine. The optimization of this engine is achieved through the velocity of the piston, allowing not only the optimization of power output but also some other figures of merit involving entropy production. The maximum power and maximum ecological efficiencies are computed. It is shown that the near ideal gas working substance displays an endoreversible Carnot-like engine behavior. This can be considered as a prove of the validity of the Carnot-like endoreversible model. An effective reversible cycle different than the Carnot one is obtained, in agreement with the endoreversible hypothesis flexibility. We compare the efficiencies stemming from an ideal gas approximation with those of the simulation, and then we propose a suitable approximation to an endoreversible heat engine and to a reversible Joule-Brayton cycle which fits very well to the simulation results. Finally, we show that the maximum ecological efficiency η=1-τ^{3/4}, which is also very close to the upper bound of the low-dissipation heat engine under maximum ecological (and Omega) conditions, is close for describing the dynamics of the simulated cycle under maximum power and maximum ecological conditions in the so-named heat engine operability region.

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A graphic approach to include dissipative-like effects in reversible thermal cycles

Cited by 5 publications

References 29 publications

Entropy generation and unified optimization of Carnot-like and low-dissipation refrigerators

Entropy generation and unified optimization of Carnot-like and low-dissipation refrigerators

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

Ecological efficiency of finite-time thermodynamics: A molecular dynamics study

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