Abstract models for heat engines

Tu, Z. C.

doi:10.1007/s11467-020-1029-6

Cited by 31 publications

(21 citation statements)

References 90 publications

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“…As a straightforward consequence, the thermodynamic optimization of heat devices is receiving nowadays great attention heightened by the contemporary growing importance of saving energy resources in any energy conversion process for heat engines (HE), refrigerators (RE), and heat pumps (HP) [9][10][11]. Common features of optimization criteria are their inherent dependence on the elected model in each case (classical, mesoscopic, or quantum) and that the objective function should be dependent on the stated optimization problem [12][13][14]. Accordingly, appropriate theoretical frameworks have been used and, in all of them, important efforts have been devoted to the derivation of specific trade-offs and upper bounds [15][16][17][18][19] to guide more efficient designs.…”

Section: Introductionmentioning

confidence: 99%

Success versus failure: Efficient heat devices in thermodynamics

et al. 2022

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Classical equilibrium thermodynamics provides, in a general way, upper Carnot bounds for the performance of energy converters. Nevertheless, to suggest lower bounds is a much more subtle issue, especially when they are related to a definition of convenience. Here, this issue is investigated in a unified way for heat engines, refrigerators, and heat pumps. First, irreversibilities are weighted in the context of heat reservoir stability for irreversible engines by using the thermodynamic distance between minimum energy and maximum entropy steady states. Some stability coefficients can be related to a majorization process and the obtention of Pareto fronts, linking stability and optimization by means of efficiency and entropy due to correlations between system and reservoirs. Second, these findings are interpreted in a very simple context. A region where the heat device is efficient is defined in a general scheme and, below this zone, the heat device is inefficient in the sense that irreversibilities somehow dominate its behavior. These findings allow for a clearer understanding of the role played by some well-known figures of merit in the scope of finite-time and -size optimization. Comparison with experimental results is provided.

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Section: Introductionmentioning

confidence: 99%

Success versus failure: Efficient heat devices in thermodynamics

et al. 2022

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“…Its development up to 2012 is comprehensibly reviewed in [8]. Concerning microscopic machines, this period was mainly devoted to generalizations of classical problems: With a few exceptions [9], performance of stochastic heat engines was almost universally studied on the level of mean values with a special focus on the efficiency at maximum power [10][11][12]. Only recently, a systematic attention has been devoted to fluctuations in performance of small heat engines.…”

Section: Introductionmentioning

confidence: 99%

Fluctuations in heat engines

Holubec,

Ryabov

2021

Preprint

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Investigation of fundamental limitations of heat to work conversion at the macroscale gave birth to the second law of classical thermodynamics. Recent years have witnessed an enormous effort to develop and describe microscopic heat engines based on systems as small as individual colloidal particles or quantum dots. At such scales, fluctuations are an inherent part of dynamics and thermodynamics. The fundamentally stochastic character of the second law then yields interesting implications on statistics of output power and efficiency of the small heat engines. The general properties, symmetries, and limitations of these statistics have become revealed, understood, and tested only during the last few years. Will their complete understanding ignite a similar revolution as the discovery of the second law? Here, we review the known general results concerning fluctuations in the performance of small heat engines. To make the discussion more transparent, we illustrate the main abstract findings on exactly solvable models and provide a thorough theoretical introduction for newcomers to the field.

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“…Curzon and Ahlborn [9] took Carnot heat engine as subject and obtained the performance limit η 1 − T L T H . It was generally regarded as the birth symbol of the finite time thermodynamics (FTT) theory [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. In fact, this performance limit was first derived by Moutier [25] and Novikov [26] in 1872 and 1957, respectively.…”

Section: Introductionmentioning

confidence: 99%

A generalized irreversible thermal Brownian motor cycle and its optimal performance

Chen

Ding

et al. 2021

Eur. Phys. J. Plus

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A finite time thermodynamic model of generalized irreversible thermal Brownian motor is proposed, in which heat transfer rate of particles through potential field, heat absorption of particles that overcome external load, the kinetic energy loss of particles, heat flow caused by friction, heat leakage and thermal resistances between reservoir and Brownian motor are considered. The key performance parameters of Brownian motor are derived. The influences of design parameters and irreversible factors on the performances are analyzed. The performance characteristics are determined when the motor operates as a heat engine or a refrigerator. For the Brownian heat engine, the working regions are given when both the power and efficiency are large. By optimizing barrier height and the asymmetry of potential, the performance characteristics under the optimization objectives of maximum power and efficiency are obtained. For the Brownian refrigerator, the working regions are given when both the cooling load and coefficient of performance (COP) are large. By optimizing barrier height and external load, the performance characteristics under the optimization objectives of maximum cooling load and COP are obtained. The results show that external load reduces the drift velocity of particles. There exists an optimal barrier height to maximize the drift velocity or the number of particles. The design parameters influence the drift velocity and heat absorption of the particles and then modulates the performance of system. One can regulate the barrier height to satisfy that the system works in optimal regions in actual design processes. Compared with previous models, the newly established model is universal and the results obtained herein also include the previous ones.

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Abstract models for heat engines

Cited by 31 publications

References 90 publications

Success versus failure: Efficient heat devices in thermodynamics

Success versus failure: Efficient heat devices in thermodynamics

Fluctuations in heat engines

A generalized irreversible thermal Brownian motor cycle and its optimal performance

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