The Experts below are selected from a list of 2178 Experts worldwide ranked by ideXlab platform

Fengrui Sun - One of the best experts on this subject based on the ideXlab platform.

  • Angular speed-dependent performance of generalized irreversible Carnot Engine
    2011
    Co-Authors: Qinghua Xiao, Lingen Chen, Fengrui Sun
    Abstract:

    On the basis of a generalized irreversible Carnot Engine model with the losses of heat resistance, heat leakage and internal irreversibility, the angular speed-dependent performance of the Engine is analyzed and optimized with Newton’s heat transfer law Q∝Δ(T) between the working fluid and the heat reservoirs. The relations among the dimensionless power output, efficiency and the angular speed of the heat Engine, the optimal angular speed corresponding to the maximum power output and the maximum efficiency are derived. Numerical examples show the effects of the heat leakage and the internal irreversibility on the angular speed-dependent performance of the Engine. The results can provide guidelines for selecting appropriate working point of heat Engines.

  • ecological performance of an endoreversible Carnot heat Engine with complex heat transfer law
    International Journal of Sustainable Energy, 2011
    Co-Authors: Lingen Chen, Fengrui Sun
    Abstract:

    The optimal ecological performance of an endoreversible Carnot Engine, in which the transfer between the working fluid and the heat reservoirs obeys a complex heat transfer law, including generalized convective heat transfer law and generalized radiative heat transfer law, Q∝ (Δ T n ) m , is derived by taking into account an ecological optimization criterion as the objective function, which consists of maximizing a function representing the best compromise between the power output and entropy generation rate of the heat Engine. The obtained results include the optimal ecological performance of the endoreversible Carnot heat Engine with various heat transfer laws obtained in many studies.

  • Performance of an irreversible quantum Carnot Engine with spin 1∕2
    The Journal of chemical physics, 2006
    Co-Authors: Lingen Chen, Fengrui Sun
    Abstract:

    The purpose of this paper is to investigate the effect of quantum properties of the working medium on the performance of an irreversible Carnot cycle with spin 1∕2. The optimal relationship between the dimensionless power output P* versus the efficiency η for the irreversible quantum Carnot Engine with heat leakage and other irreversible losses is derived. Especially, the performances of the Engine at low temperature limit and at high temperature limit are discussed.

  • performance of an irreversible quantum Carnot Engine with spin 1 2
    Journal of Chemical Physics, 2006
    Co-Authors: Lingen Chen, Fengrui Sun
    Abstract:

    The purpose of this paper is to investigate the effect of quantum properties of the working medium on the performance of an irreversible Carnot cycle with spin 1∕2. The optimal relationship between the dimensionless power output P* versus the efficiency η for the irreversible quantum Carnot Engine with heat leakage and other irreversible losses is derived. Especially, the performances of the Engine at low temperature limit and at high temperature limit are discussed.

  • exergy based ecological optimization of linear phenomenological heat transfer law irreversible Carnot Engines
    Applied Energy, 2006
    Co-Authors: Lingen Chen, Xiao-qin Zhu, Fengrui Sun
    Abstract:

    The optimal exergy-based ecological performance of a generalized irreversible Carnot-Engine with losses due to heat-resistance, heat leakage and internal irreversibility, in which the heat-transfer between the working fluid and the heat reservoirs obeys a linear phenomenological heat-transfer law, is derived by taking an exergy-based ecological optimization criterion as the objective. This consists of maximizing a function representing the best compromise between the power output and entropy-production rate of the heat Engine. A numerical example is given to show the effects of heat leakage and internal irreversibility on the optimal performance of the generalized irreversible heat-Engine. The results provide theoretical guidance for the design of practical Engines.

Lingen Chen - One of the best experts on this subject based on the ideXlab platform.

  • Angular speed-dependent performance of generalized irreversible Carnot Engine
    2011
    Co-Authors: Qinghua Xiao, Lingen Chen, Fengrui Sun
    Abstract:

    On the basis of a generalized irreversible Carnot Engine model with the losses of heat resistance, heat leakage and internal irreversibility, the angular speed-dependent performance of the Engine is analyzed and optimized with Newton’s heat transfer law Q∝Δ(T) between the working fluid and the heat reservoirs. The relations among the dimensionless power output, efficiency and the angular speed of the heat Engine, the optimal angular speed corresponding to the maximum power output and the maximum efficiency are derived. Numerical examples show the effects of the heat leakage and the internal irreversibility on the angular speed-dependent performance of the Engine. The results can provide guidelines for selecting appropriate working point of heat Engines.

  • ecological performance of an endoreversible Carnot heat Engine with complex heat transfer law
    International Journal of Sustainable Energy, 2011
    Co-Authors: Lingen Chen, Fengrui Sun
    Abstract:

    The optimal ecological performance of an endoreversible Carnot Engine, in which the transfer between the working fluid and the heat reservoirs obeys a complex heat transfer law, including generalized convective heat transfer law and generalized radiative heat transfer law, Q∝ (Δ T n ) m , is derived by taking into account an ecological optimization criterion as the objective function, which consists of maximizing a function representing the best compromise between the power output and entropy generation rate of the heat Engine. The obtained results include the optimal ecological performance of the endoreversible Carnot heat Engine with various heat transfer laws obtained in many studies.

  • Performance of an irreversible quantum Carnot Engine with spin 1∕2
    The Journal of chemical physics, 2006
    Co-Authors: Lingen Chen, Fengrui Sun
    Abstract:

    The purpose of this paper is to investigate the effect of quantum properties of the working medium on the performance of an irreversible Carnot cycle with spin 1∕2. The optimal relationship between the dimensionless power output P* versus the efficiency η for the irreversible quantum Carnot Engine with heat leakage and other irreversible losses is derived. Especially, the performances of the Engine at low temperature limit and at high temperature limit are discussed.

  • performance of an irreversible quantum Carnot Engine with spin 1 2
    Journal of Chemical Physics, 2006
    Co-Authors: Lingen Chen, Fengrui Sun
    Abstract:

    The purpose of this paper is to investigate the effect of quantum properties of the working medium on the performance of an irreversible Carnot cycle with spin 1∕2. The optimal relationship between the dimensionless power output P* versus the efficiency η for the irreversible quantum Carnot Engine with heat leakage and other irreversible losses is derived. Especially, the performances of the Engine at low temperature limit and at high temperature limit are discussed.

  • exergy based ecological optimization of linear phenomenological heat transfer law irreversible Carnot Engines
    Applied Energy, 2006
    Co-Authors: Lingen Chen, Xiao-qin Zhu, Fengrui Sun
    Abstract:

    The optimal exergy-based ecological performance of a generalized irreversible Carnot-Engine with losses due to heat-resistance, heat leakage and internal irreversibility, in which the heat-transfer between the working fluid and the heat reservoirs obeys a linear phenomenological heat-transfer law, is derived by taking an exergy-based ecological optimization criterion as the objective. This consists of maximizing a function representing the best compromise between the power output and entropy-production rate of the heat Engine. A numerical example is given to show the effects of heat leakage and internal irreversibility on the optimal performance of the generalized irreversible heat-Engine. The results provide theoretical guidance for the design of practical Engines.

Ozgur E Mustecaplioglu - One of the best experts on this subject based on the ideXlab platform.

  • a photonic Carnot Engine powered by a spin star network
    EPL, 2017
    Co-Authors: Deniz Turkpence, Ferdi Altintas, Mauro Paternostro, Ozgur E Mustecaplioglu
    Abstract:

    We propose a spin-star network, where a central spin-(1/2), acting as a quantum fuel, is coupled to N outer spin-(1/2) particles. If the network is in thermal equilibrium with a heat bath, the central spin can have an effective temperature, higher than that of the bath, scaling nonlinearly with N. Such temperature can be tuned with the anisotropy parameter of the coupling. Using a beam of such central spins to pump a micromaser cavity, we determine the dynamics of the cavity field using a coarse-grained master equation. We find that the central-spin beam effectively acts as a hot reservoir to the cavity field and brings it to a thermal steady state whose temperature benefits from the same nonlinear enhancement with N and results in a highly efficient photonic Carnot Engine. The validity of our conclusions is tested against the presence of atomic and cavity damping using a microscopic master equation method for typical microwave cavity-QED parameters. The role played by quantum coherence and correlations on the scaling effect is pointed out. An alternative scheme where the spin-(1/2) is coupled to a macroscopic spin- particle is also discussed.

  • A photonic Carnot Engine powered by a quantum spin-star network
    EPL (Europhysics Letters), 2017
    Co-Authors: Deniz Turkpence, Ferdi Altintas, Mauro Paternostro, Ozgur E Mustecaplioglu
    Abstract:

    We propose a spin-star network, where a central spin-$1/2$ is coupled with XXZ interaction to $N$ outer spin-$1/2$ particles, as a quantum fuel. If the network is in thermal equilibrium with a cold bath, the central spin can have an effective temperature larger than the bath one and scaling nonlinearly with $N$. The nonlinearity can be tuned to $N^2, N^3$ or $N^4$ with the anisotropy parameter of the coupling. Using a stream of central-spin particles to pump a micromaser cavity, we calculate the dynamics of the cavity field using a coarse-grained master equation. Our study reveals that the central-spin beam effectively acts as a hot reservoir to the cavity field and brings the field to a thermal steady-state whose temperature benefits from the same nonlinear enhancement with $N$, and results in a highly efficient photonic Carnot Engine. The validity of our conclusions is tested against the presence of atomic and cavity damping using a microscopic master equation method for typical microwave cavity-QED parameters. An alternative equivalent scheme where the spin-$1/2$ is coupled to a macroscopic spin-$(N/2)$ particle is also discussed.

  • Quantum fuel with multilevel atomic coherence for ultrahigh specific work in a photonic Carnot Engine.
    Physical review. E, 2016
    Co-Authors: Deniz Turkpence, Ozgur E Mustecaplioglu
    Abstract:

    We investigate scaling of work and efficiency of a photonic Carnot Engine with a number of quantum coherent resources. Specifically, we consider a generalization of the "phaseonium fuel" for the photonic Carnot Engine, which was first introduced as a three-level atom with two lower states in a quantum coherent superposition by M. O. Scully, M. Suhail Zubairy, G. S. Agarwal, and H. Walther [Science 299, 862 (2003)SCIEAS0036-807510.1126/science.1078955], to the case of N+1 level atoms with N coherent lower levels. We take into account atomic relaxation and dephasing as well as the cavity loss and derive a coarse-grained master equation to evaluate the work and efficiency analytically. Analytical results are verified by microscopic numerical examination of the thermalization dynamics. We find that efficiency and work scale quadratically with the number of quantum coherent levels. Quantum coherence boost to the specific energy (work output per unit mass of the resource) is a profound fundamental difference of quantum fuel from classical resources. We consider typical modern resonator set ups and conclude that multilevel phaseonium fuel can be utilized to overcome the decoherence in available systems. Preparation of the atomic coherences and the associated cost of coherence are analyzed and the Engine operation within the bounds of the second law is verified. Our results bring the photonic Carnot Engines much closer to the capabilities of current resonator technologies.

Deniz Turkpence - One of the best experts on this subject based on the ideXlab platform.

  • a photonic Carnot Engine powered by a spin star network
    EPL, 2017
    Co-Authors: Deniz Turkpence, Ferdi Altintas, Mauro Paternostro, Ozgur E Mustecaplioglu
    Abstract:

    We propose a spin-star network, where a central spin-(1/2), acting as a quantum fuel, is coupled to N outer spin-(1/2) particles. If the network is in thermal equilibrium with a heat bath, the central spin can have an effective temperature, higher than that of the bath, scaling nonlinearly with N. Such temperature can be tuned with the anisotropy parameter of the coupling. Using a beam of such central spins to pump a micromaser cavity, we determine the dynamics of the cavity field using a coarse-grained master equation. We find that the central-spin beam effectively acts as a hot reservoir to the cavity field and brings it to a thermal steady state whose temperature benefits from the same nonlinear enhancement with N and results in a highly efficient photonic Carnot Engine. The validity of our conclusions is tested against the presence of atomic and cavity damping using a microscopic master equation method for typical microwave cavity-QED parameters. The role played by quantum coherence and correlations on the scaling effect is pointed out. An alternative scheme where the spin-(1/2) is coupled to a macroscopic spin- particle is also discussed.

  • A photonic Carnot Engine powered by a quantum spin-star network
    EPL (Europhysics Letters), 2017
    Co-Authors: Deniz Turkpence, Ferdi Altintas, Mauro Paternostro, Ozgur E Mustecaplioglu
    Abstract:

    We propose a spin-star network, where a central spin-$1/2$ is coupled with XXZ interaction to $N$ outer spin-$1/2$ particles, as a quantum fuel. If the network is in thermal equilibrium with a cold bath, the central spin can have an effective temperature larger than the bath one and scaling nonlinearly with $N$. The nonlinearity can be tuned to $N^2, N^3$ or $N^4$ with the anisotropy parameter of the coupling. Using a stream of central-spin particles to pump a micromaser cavity, we calculate the dynamics of the cavity field using a coarse-grained master equation. Our study reveals that the central-spin beam effectively acts as a hot reservoir to the cavity field and brings the field to a thermal steady-state whose temperature benefits from the same nonlinear enhancement with $N$, and results in a highly efficient photonic Carnot Engine. The validity of our conclusions is tested against the presence of atomic and cavity damping using a microscopic master equation method for typical microwave cavity-QED parameters. An alternative equivalent scheme where the spin-$1/2$ is coupled to a macroscopic spin-$(N/2)$ particle is also discussed.

  • Quantum fuel with multilevel atomic coherence for ultrahigh specific work in a photonic Carnot Engine.
    Physical review. E, 2016
    Co-Authors: Deniz Turkpence, Ozgur E Mustecaplioglu
    Abstract:

    We investigate scaling of work and efficiency of a photonic Carnot Engine with a number of quantum coherent resources. Specifically, we consider a generalization of the "phaseonium fuel" for the photonic Carnot Engine, which was first introduced as a three-level atom with two lower states in a quantum coherent superposition by M. O. Scully, M. Suhail Zubairy, G. S. Agarwal, and H. Walther [Science 299, 862 (2003)SCIEAS0036-807510.1126/science.1078955], to the case of N+1 level atoms with N coherent lower levels. We take into account atomic relaxation and dephasing as well as the cavity loss and derive a coarse-grained master equation to evaluate the work and efficiency analytically. Analytical results are verified by microscopic numerical examination of the thermalization dynamics. We find that efficiency and work scale quadratically with the number of quantum coherent levels. Quantum coherence boost to the specific energy (work output per unit mass of the resource) is a profound fundamental difference of quantum fuel from classical resources. We consider typical modern resonator set ups and conclude that multilevel phaseonium fuel can be utilized to overcome the decoherence in available systems. Preparation of the atomic coherences and the associated cost of coherence are analyzed and the Engine operation within the bounds of the second law is verified. Our results bring the photonic Carnot Engines much closer to the capabilities of current resonator technologies.

Sumiyoshi Abe - One of the best experts on this subject based on the ideXlab platform.

  • General Formula for the Efficiency of Quantum-Mechanical Analog of the Carnot Engine
    Entropy, 2013
    Co-Authors: Sumiyoshi Abe
    Abstract:

    An analog of the Carnot Engine reversibly operating within the framework of pure-state quantum mechanics is discussed. A general formula is derived for the efficiency of such an Engine with an arbitrary confining potential. Its expression is given in terms of an energy spectrum and shows how the efficiency depends on a potential as the analog of a working material in thermodynamics, in general. This non-universal nature results from the fact that there exists no analog of the second law of thermodynamics in pure-state quantum mechanics where the von Neumann entropy identically vanishes. A special class of spectra, which leads to a common form of the efficiency, is identified.

  • Efficiency of the general quantum-mechanical Carnot Engine
    arXiv: Statistical Mechanics, 2012
    Co-Authors: Sumiyoshi Abe
    Abstract:

    A quantum-mechanical analog of the Carnot Engine reversibly working at vanishing temperature, shortly termed the quantum-mechanical Carnot Engine, is discussed. A general formula for the efficiency of such an Engine with an arbitrary confining potential is presented. Its expression is purely given in terms of the structure of the energy spectrum. Dependency of the efficiency on the form of a potential as an analog of the working material in thermodynamics implies nonuniversality of the Engine. This may be due to the absence of the second-law-like principle in pure-state quantum mechanics.

  • Role of the superposition principle for enhancing the efficiency of the quantum-mechanical Carnot Engine.
    Physical review. E Statistical nonlinear and soft matter physics, 2012
    Co-Authors: Sumiyoshi Abe, Shinji Okuyama
    Abstract:

    The role of the superposition principle is discussed for the quantum-mechanical Carnot Engine introduced by Bender, Brody, and Meister [J. Phys. A 33, 4427 (2000)]. It is shown that the efficiency of the Engine can be enhanced by the superposition of quantum states. A finite-time process is also discussed and the condition of the maximum power output is presented. Interestingly, the efficiency at the maximum power is lower than that without superposition.

  • Maximum-power quantum-mechanical Carnot Engine.
    Physical Review E, 2011
    Co-Authors: Sumiyoshi Abe
    Abstract:

    In their work [J. Phys. A 33, 4427 (2000)], Bender, Brody, and Meister have shown by employing a two-state model of a particle confined in the one-dimensional infinite potential well that it is possible to construct a quantum-mechanical analog of the Carnot Engine through changes of both the width of the well and the quantum state in a specific manner. Here, a discussion is developed about realizing the maximum power of such an Engine, where the width of the well moves at low but finite speed. The efficiency of the Engine at the maximum power output is found to be universal independently of any of the parameters contained in the model.