Boosting the performance of quantum Otto heat engines

Chen, Jinfu; Sun, C. P.; Dong, Huafeng

doi:10.1103/physreve.100.032144

Cited by 40 publications

(32 citation statements)

References 63 publications

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“…Similarly, harmonic quantum Otto engines reach the Curzon-Ahlborn efficiency in the quasistatic limit [8,9]. More recently, it was demonstrated that the efficiency of endoreversible Otto engines at maximal power depends on the equation of state, i.e., the nature of the working medium [10][11][12][13][14] and the specific implementation of the power stroke [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Endoreversible Otto Engines at Maximal Power

Smith

Pal

Deffner

2020

Journal of Non-Equilibrium Thermodynamics

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Despite its idealizations, thermodynamics has proven its power as a predictive theory for practical applications. In particular, the Curzon–Ahlborn efficiency provides a benchmark for any real engine operating at maximal power. Here we further develop the analysis of endoreversible Otto engines. For a generic class of working mediums, whose internal energy is proportional to some power of the temperature, we find that no engine can achieve the Carnot efficiency at finite power. However, we also find that for the specific example of photonic engines the efficiency at maximal power is higher than the Curzon–Ahlborn efficiency.

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Section: Introductionmentioning

confidence: 99%

Endoreversible Otto Engines at Maximal Power

Smith

Pal

Deffner

2020

Journal of Non-Equilibrium Thermodynamics

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“…Since the last century, with the maturity of quantum theory and its related technologies, people started to pay attention to the performance of quantum heat engines working in micro-scale within the framework of quantum thermodynamics [ 4 , 5 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Series of the quantum effect, such as coherence, entanglement, quantum phase transition, etc., of the working substance or heat source have been studied to realize better heat engines [ 13 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. On the other hand, with the development of non-equilibrium thermodynamics [ 2 , 3 , 28 ], the optimization of actual heat engines under the framework of finite-time thermodynamics attracted a wide range of attention [ 29 , 30 , 31 , 32 , 33 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of Finite-Size Heat Source’s Heat Capacity on the Efficiency of Heat Engine

2020

Entropy

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Heat engines used to output useful work have important practical significance, which, in general, operate between heat baths of infinite size and constant temperature. In this paper, we study the efficiency of a heat engine operating between two finite-size heat sources with initial temperature difference. The total output work of such heat engine is limited due to the finite heat capacity of the sources. We firstly investigate the effects of different heat capacity characteristics of the sources on the heat engine’s efficiency at maximum work (EMW) in the quasi-static limit. Moreover, it is found that the efficiency of the engine operating in finite-time with maximum power of each cycle is achieved follows a simple universality as η=ηC/4+OηC2, where ηC is the Carnot efficiency determined by the initial temperature of the sources. Remarkably, when the heat capacity of the heat source is negative, such as the black holes, we show that the heat engine efficiency during the operation can surpass the Carnot efficiency determined by the initial temperature of the heat sources. It is further argued that the heat engine between two black holes with vanishing initial temperature difference can be driven by the energy fluctuation. The corresponding EMW is proved to be ηMW=2−2.

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“…The Otto cycle (see Fig. 1) has been widely studied due to its analytic tractability [12,[16][17][18][21][22][23][24][25][26][27]. It has been reported that the quantum Otto engine can also be used as a precise thermometer [28] and the Otto engine with the finite power and the quasi-static efficiency can be achieved by the shortcut-to-adiabaticity technique [16].…”

Section: Introductionmentioning

confidence: 99%

Finite-time quantum Otto engine: Surpassing the quasistatic efficiency due to friction

Lee¹,

Ha²,

Park³

et al. 2020

Phys. Rev. E

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In finite-time quantum heat engines, some work is consumed to drive a working fluid accompanying coherence, which is called 'friction'. To understand the role of friction in quantum thermodynamics, we present a couple of finite-time quantum Otto cycles with two different baths: Agarwal versus Lindbladian. We exactly solve them and compare the performance of the Agarwal engine with that of the Lidbladian one. Particularly, we find remarkable and counterintuitive results that the performance of the Agarwal engine due to friction can be much higher than that in the quasi-static limit with the Otto efficiency, and the power of the Lindbladian engine can be non-zero in the short-time limit. Based on additional numerical calculations of these outcomes, we discuss possible origins of such differences between two engines and reveal them. Our results imply that even with equilibrium bath, a non-equilibrium working fluid brings on the higher performance than what an equilibrium one does.

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Boosting the performance of quantum Otto heat engines

Cited by 40 publications

References 63 publications

Endoreversible Otto Engines at Maximal Power

Endoreversible Otto Engines at Maximal Power

Effect of Finite-Size Heat Source’s Heat Capacity on the Efficiency of Heat Engine

Finite-time quantum Otto engine: Surpassing the quasistatic efficiency due to friction

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