Nonuniversality of heat-engine efficiency at maximum power

Lee, Sang Hoon; Um, Jaegon; Park, Hyunggyu

doi:10.1103/physreve.98.052137

Cited by 14 publications

(24 citation statements)

References 34 publications

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“…Despite their limited practical value, QHEs are pivotal to reveal fundamental limits on the operation of quantum machines from a thermodynamical perspective. Accordingly, many proposals to realize them can be found in the literature [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], some of which take into account finite-time engine cycles [22][23][24][25][26]. In addition, the effects of the profound quantum nature of the QHE such as such as cooperativity [27][28][29][30][31], coherence and correlations [32][33][34] on the performance of QHEs have also been investigated.…”

Section: Introductionmentioning

confidence: 99%

Spin quantum heat engines with shortcuts to adiabaticity

Çakmak

Müstecaplıoğlu

2019

Phys. Rev. E

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We consider a finite-time quantum Otto cycle with single and two-spin-1/2 systems as its working medium. In order to mimic adiabatic dynamics at a finite time, we employ a shortcut-to-adiabaticity technique and evaluate the performance of the engine including the cost of the shortcut. We compare our results with the true adiabatic and non-adiabatic performances of the same cycle. Our findings indicate that the use of the shortcutto-adiabaticity scheme significantly enhances the performance of the quantum Otto engine as compared to its adiabatic and non-adiabatic counterparts for different figures of merit. *

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Section: Introductionmentioning

confidence: 99%

Spin quantum heat engines with shortcuts to adiabaticity

Çakmak

Müstecaplıoğlu

2019

Phys. Rev. E

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“…Because of their potential use in high efficiency devices, the performance of QD heat engines has been studied extensively by theorists. 31,33,[115][116][117][118][119][120] QD heat engine consists of a single level quantum dot, with orbital energy ϵ, and it exchanges electrons with a cold left lead at temperature T l and chemical potential μ l , and with a hot right lead at temperature T r and chemical potential μ r (Figure 4). The quantum dot is either empty (state 1) or filled (state 2).…”

Section: Quantum Dot As a Heat Engine And Non-universality Of Empmentioning

confidence: 99%

Optimization and Efficiency Studies of Heat Engines: A Review

Aneja

2020

JoARMET

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This review aims to study the various theoretical and numerical investigations in the optimization of heat engines. The main focus is to discuss the procedures to derive the efficiency of heat engines under different operating regimes (or optimization criteria) for different models of heat engines such as endreversible models, stochastic models, low-dissipation models, quantum models etc. Both maximum power and maximum efficiency operational regimes are desirable but not economical, so to meet the thermo-ecological considerations, some other compromise-based criteria have been proposed such as Ω criterion (ecological criterion) and efficient power criterion. Thus, heat engines can be optimized to work at an efficiency which may not be the maximum (Carnot) efficiency. The optimization efficiency obtained under each criterion shows a striking universal behaviour in the near-equilibrium regime. We also discussed a multi-parameter combined objective function of heat engines. The optimization efficiency derived from the multi-parameter combined objective function includes a variety of optimization efficiencies, such as the efficiency at the maximum power, efficiency at the maximum efficiency-power state, efficiency at the maximum criterion, and Carnot efficiency. Thus, a comparison of optimization of heat engines under different criteria enables to choose the suitable one for the best performance of heat engine under different conditions.

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“…In this study, we consider the case T 1 > T 2 and µ 1 < µ 2 < E. The transition rate of an electron from the lead 1 (2) to the dot is q (ǫ) and the corresponding reverse rate isq (ǫ). Then, this system can be described by the following master equation [9,[11][12][13][14]: where P oc and P un are probabilities of occupied and unoccupied states of the quantum dot, respectively. Here, we assume the local detailed balance conditions for the transition rates such that…”

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confidence: 99%

Carnot Efficiency and Zero-Entropy Production Rate Do Not Guarantee Reversibility of a Process

Lee

et al. 2019

J. Korean Phys. Soc.

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Thermodynamic process at zero-entropy-production (EP) rate has been regarded as a reversible process. A process achieving the Carnot efficiency is also considered as a reversible process. Therefore, the condition, 'Carnot efficiency at zero-EP rate' could be regarded as a strong equivalent condition for a reversible process.Here, however, we show that the detailed balance can be broken for a zero-EP rate process and even for a process achieving the Carnot efficiency at zero-EP rate in an example of a quantum-dot model. This clearly demonstrates that 'Carnot efficiency at zero-EP rate' or just 'zero-EP rate' is not a sufficient condition for a reversible process.

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Nonuniversality of heat-engine efficiency at maximum power

Cited by 14 publications

References 34 publications

Spin quantum heat engines with shortcuts to adiabaticity

Spin quantum heat engines with shortcuts to adiabaticity

Optimization and Efficiency Studies of Heat Engines: A Review

Carnot Efficiency and Zero-Entropy Production Rate Do Not Guarantee Reversibility of a Process

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