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Lin Gen Chen - One of the best experts on this subject based on the ideXlab platform.
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Maximum power output of a class of irreversible non-regeneration Heat Engines with a non-uniform working fluid and linear phenomenological Heat transfer law
Science China-physics Mechanics & Astronomy, 2009Co-Authors: Lin Gen ChenAbstract:Maximum power output of a class of irreversible non-regeneration Heat Engines with non-uniform working fluid, in which Heat transfers between the working fluid and the Heat reservoirs obey the linear phenomenological Heat transfer law [q ∝ Δ(T−1)], are studied in this paper. Optimal control theory is used to determine the upper bounds of power of the Heat engine for the lumped-parameter model and the distributed-parameter model, respectively. The results show that the maximum power output of the Heat engine in the distributed-parameter model is less than or equal to that in the lumped-parameter model, which could provide more realistic guidelines for real Heat Engines. Analytical solutions of the maximum power output are obtained for the irreversible Heat Engines working between constant temperature reservoirs. For the irreversible Heat engine operating between variable temperature reservoirs, a numerical example for the lumped-parameter model is provided by numerical calculation. The effects of changes of reservoir’s temperature on the maximum power of the Heat engine are analyzed. The obtained results are, in addition, compared with those obtained with Newtonian Heat transfer law [q ∝ Δ(T)].
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optimal configuration of a class of endoreversible Heat Engines for maximum efficiency with radiative Heat transfer law
Science China-physics Mechanics & Astronomy, 2008Co-Authors: Hanjiang Song, Lin Gen Chen, Fengrui SunAbstract:Optimal configuration of a class of endoreversible Heat Engines with fixed duration, input energy and radiative Heat transfer law (q ∝ Δ(T 4)) is determined. The optimal cycle that maximizes the efficiency of the Heat engine is obtained by using optimal-control theory, and the differential equations are solved by the Taylor series expansion. It is shown that the optimal cycle has eight branches including two isothermal branches, four maximum-efficiency branches, and two adiabatic branches. The interval of each branch is obtained, as well as the solutions of the temperatures of the Heat reservoirs and the working fluid. A numerical example is given. The obtained results are compared with those obtained with the Newton’s Heat transfer law for the maximum efficiency objective, those with linear phenomenological Heat transfer law for the maximum efficiency objective, and those with radiative Heat transfer law for the maximum power output objective.
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endoreversible Heat Engines for maximum power output with fixed duration and radiative Heat transfer law
Applied Energy, 2007Co-Authors: Hanjiang Song, Lin Gen ChenAbstract:Optimal configuration of a class of endoreversible Heat-Engines, with fixed duration and subject to the radiative Heat-transfer law q [is proportional to] [Delta](T4), has been determined. The optimal cycle that maximizes the power output of the engine has been obtained using optimal-control theory, and the differential equations are solved by a Taylor-series expansion. It is shown that the optimal cycle has six branches, including two isothermal branches and four maximum-power branches, without adiabatic branches. The interval of each branch has been obtained, as well as the solutions of the temperatures of the Heat reservoirs and working fluid. A numerical example is given. The results are compared with those obtained using the Newton's Heat-transfer law for maximum power output and those using a linear phenomenological Heat-transfer law for maximum power output.
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endoreversible Heat Engines for maximum power output with fixed duration and radiative Heat transfer law
Applied Energy, 2007Co-Authors: Hanjiang Song, Lin Gen Chen, Fengrui SunAbstract:Abstract Optimal configuration of a class of endoreversible Heat-Engines, with fixed duration and subject to the radiative Heat-transfer law q ∝ Δ( T 4 ), has been determined. The optimal cycle that maximizes the power output of the engine has been obtained using optimal-control theory, and the differential equations are solved by a Taylor-series expansion. It is shown that the optimal cycle has six branches, including two isothermal branches and four maximum-power branches, without adiabatic branches. The interval of each branch has been obtained, as well as the solutions of the temperatures of the Heat reservoirs and working fluid. A numerical example is given. The results are compared with those obtained using the Newton’s Heat-transfer law for maximum power output and those using a linear phenomenological Heat-transfer law for maximum power output.
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optimal configuration of a class of endoreversible Heat Engines with linear phenomenological Heat transfer law q δ t 1
Journal of Applied Physics, 2006Co-Authors: Hanjiang Song, Lin Gen Chen, Fengrui SunAbstract:Optimal configuration of a class of endoreversible Heat Engines with fixed duration, input energy, and linear phenomenological Heat transfer law [q∝Δ(T−1)] has been determined. The optimal cycles that maximize the efficiency and the power output of the engine have been obtained using optimal-control theory, and the differential equations are solved by using Taylor series expansion. It is shown that the optimal cycle for maximum efficiency has eight branches including two isothermal branches, four maximum-efficiency branches, and two adiabatic branches, and that the optimal cycle for maximum-power output has six branches including two isothermal branches, four maximum-power branches, and without an adiabatic branch. The interval of each branch has been obtained, as well as the solutions of the temperatures of Heat reservoirs and working fluid. Numerical examples are given. The obtained results are compared with those obtained with Newton’s Heat transfer law [q∝Δ(T)] for maximum-efficiency and maximum-power...
Fengrui Sun - One of the best experts on this subject based on the ideXlab platform.
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optimal configuration of a class of endoreversible Heat Engines for maximum efficiency with radiative Heat transfer law
Science China-physics Mechanics & Astronomy, 2008Co-Authors: Hanjiang Song, Lin Gen Chen, Fengrui SunAbstract:Optimal configuration of a class of endoreversible Heat Engines with fixed duration, input energy and radiative Heat transfer law (q ∝ Δ(T 4)) is determined. The optimal cycle that maximizes the efficiency of the Heat engine is obtained by using optimal-control theory, and the differential equations are solved by the Taylor series expansion. It is shown that the optimal cycle has eight branches including two isothermal branches, four maximum-efficiency branches, and two adiabatic branches. The interval of each branch is obtained, as well as the solutions of the temperatures of the Heat reservoirs and the working fluid. A numerical example is given. The obtained results are compared with those obtained with the Newton’s Heat transfer law for the maximum efficiency objective, those with linear phenomenological Heat transfer law for the maximum efficiency objective, and those with radiative Heat transfer law for the maximum power output objective.
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endoreversible Heat Engines for maximum power output with fixed duration and radiative Heat transfer law
Applied Energy, 2007Co-Authors: Hanjiang Song, Lin Gen Chen, Fengrui SunAbstract:Abstract Optimal configuration of a class of endoreversible Heat-Engines, with fixed duration and subject to the radiative Heat-transfer law q ∝ Δ( T 4 ), has been determined. The optimal cycle that maximizes the power output of the engine has been obtained using optimal-control theory, and the differential equations are solved by a Taylor-series expansion. It is shown that the optimal cycle has six branches, including two isothermal branches and four maximum-power branches, without adiabatic branches. The interval of each branch has been obtained, as well as the solutions of the temperatures of the Heat reservoirs and working fluid. A numerical example is given. The results are compared with those obtained using the Newton’s Heat-transfer law for maximum power output and those using a linear phenomenological Heat-transfer law for maximum power output.
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optimal configuration of a class of endoreversible Heat Engines with linear phenomenological Heat transfer law q δ t 1
Journal of Applied Physics, 2006Co-Authors: Hanjiang Song, Lin Gen Chen, Fengrui SunAbstract:Optimal configuration of a class of endoreversible Heat Engines with fixed duration, input energy, and linear phenomenological Heat transfer law [q∝Δ(T−1)] has been determined. The optimal cycles that maximize the efficiency and the power output of the engine have been obtained using optimal-control theory, and the differential equations are solved by using Taylor series expansion. It is shown that the optimal cycle for maximum efficiency has eight branches including two isothermal branches, four maximum-efficiency branches, and two adiabatic branches, and that the optimal cycle for maximum-power output has six branches including two isothermal branches, four maximum-power branches, and without an adiabatic branch. The interval of each branch has been obtained, as well as the solutions of the temperatures of Heat reservoirs and working fluid. Numerical examples are given. The obtained results are compared with those obtained with Newton’s Heat transfer law [q∝Δ(T)] for maximum-efficiency and maximum-power...
Hanjiang Song - One of the best experts on this subject based on the ideXlab platform.
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optimal configuration of a class of endoreversible Heat Engines for maximum efficiency with radiative Heat transfer law
Science China-physics Mechanics & Astronomy, 2008Co-Authors: Hanjiang Song, Lin Gen Chen, Fengrui SunAbstract:Optimal configuration of a class of endoreversible Heat Engines with fixed duration, input energy and radiative Heat transfer law (q ∝ Δ(T 4)) is determined. The optimal cycle that maximizes the efficiency of the Heat engine is obtained by using optimal-control theory, and the differential equations are solved by the Taylor series expansion. It is shown that the optimal cycle has eight branches including two isothermal branches, four maximum-efficiency branches, and two adiabatic branches. The interval of each branch is obtained, as well as the solutions of the temperatures of the Heat reservoirs and the working fluid. A numerical example is given. The obtained results are compared with those obtained with the Newton’s Heat transfer law for the maximum efficiency objective, those with linear phenomenological Heat transfer law for the maximum efficiency objective, and those with radiative Heat transfer law for the maximum power output objective.
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endoreversible Heat Engines for maximum power output with fixed duration and radiative Heat transfer law
Applied Energy, 2007Co-Authors: Hanjiang Song, Lin Gen ChenAbstract:Optimal configuration of a class of endoreversible Heat-Engines, with fixed duration and subject to the radiative Heat-transfer law q [is proportional to] [Delta](T4), has been determined. The optimal cycle that maximizes the power output of the engine has been obtained using optimal-control theory, and the differential equations are solved by a Taylor-series expansion. It is shown that the optimal cycle has six branches, including two isothermal branches and four maximum-power branches, without adiabatic branches. The interval of each branch has been obtained, as well as the solutions of the temperatures of the Heat reservoirs and working fluid. A numerical example is given. The results are compared with those obtained using the Newton's Heat-transfer law for maximum power output and those using a linear phenomenological Heat-transfer law for maximum power output.
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endoreversible Heat Engines for maximum power output with fixed duration and radiative Heat transfer law
Applied Energy, 2007Co-Authors: Hanjiang Song, Lin Gen Chen, Fengrui SunAbstract:Abstract Optimal configuration of a class of endoreversible Heat-Engines, with fixed duration and subject to the radiative Heat-transfer law q ∝ Δ( T 4 ), has been determined. The optimal cycle that maximizes the power output of the engine has been obtained using optimal-control theory, and the differential equations are solved by a Taylor-series expansion. It is shown that the optimal cycle has six branches, including two isothermal branches and four maximum-power branches, without adiabatic branches. The interval of each branch has been obtained, as well as the solutions of the temperatures of the Heat reservoirs and working fluid. A numerical example is given. The results are compared with those obtained using the Newton’s Heat-transfer law for maximum power output and those using a linear phenomenological Heat-transfer law for maximum power output.
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optimal configuration of a class of endoreversible Heat Engines with linear phenomenological Heat transfer law q δ t 1
Journal of Applied Physics, 2006Co-Authors: Hanjiang Song, Lin Gen Chen, Fengrui SunAbstract:Optimal configuration of a class of endoreversible Heat Engines with fixed duration, input energy, and linear phenomenological Heat transfer law [q∝Δ(T−1)] has been determined. The optimal cycles that maximize the efficiency and the power output of the engine have been obtained using optimal-control theory, and the differential equations are solved by using Taylor series expansion. It is shown that the optimal cycle for maximum efficiency has eight branches including two isothermal branches, four maximum-efficiency branches, and two adiabatic branches, and that the optimal cycle for maximum-power output has six branches including two isothermal branches, four maximum-power branches, and without an adiabatic branch. The interval of each branch has been obtained, as well as the solutions of the temperatures of Heat reservoirs and working fluid. Numerical examples are given. The obtained results are compared with those obtained with Newton’s Heat transfer law [q∝Δ(T)] for maximum-efficiency and maximum-power...
Koji Okuda - One of the best experts on this subject based on the ideXlab platform.
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work output and efficiency at maximum power of linear irreversible Heat Engines operating with a finite sized Heat source
Physical Review Letters, 2014Co-Authors: Yuki Izumida, Koji OkudaAbstract:: We formulate the work output and efficiency for linear irreversible Heat Engines working between a finite-sized hot Heat source and an infinite-sized cold Heat reservoir until the total system reaches the final thermal equilibrium state with a uniform temperature. We prove that when the Heat Engines operate at the maximum power under the tight-coupling condition without Heat leakage the work output is just half of the exergy, which is known as the maximum available work extracted from a Heat source. As a consequence, the corresponding efficiency is also half of its quasistatic counterpart.
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efficiency at maximum power of minimally nonlinear irreversible Heat Engines
EPL, 2012Co-Authors: Yuki Izumida, Koji OkudaAbstract:We propose the minimally nonlinear irreversible Heat engine as a new general theoretical model to study the efficiency at the maximum power η* of Heat Engines operating between the hot Heat reservoir at the temperature Th and the cold one at Tc (Tc≤Th). Our model is based on the extended Onsager relations with a new nonlinear term meaning the power dissipation. In this model, we show that η* is bounded from the upper side by a function of the Carnot efficiency ηC≡1−Tc/Th as η*≤ηC/(2−ηC). We demonstrate the validity of our theory by showing that the low-dissipation Carnot engine can easily be described by our theory.
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efficiency at maximum power of minimally nonlinear irreversible Heat Engines
arXiv: Statistical Mechanics, 2011Co-Authors: Yuki Izumida, Koji OkudaAbstract:We propose the minimally nonlinear irreversible Heat engine as a new general theoretical model to study the efficiency at the maximum power $\eta^*$ of Heat Engines operating between the hot Heat reservoir at the temperature $T_h$ and the cold one at $T_c$ ($T_c \le T_h $). Our model is based on the extended Onsager relations with a new nonlinear term meaning the power dissipation. In this model, we show that $\eta^*$ is bounded from the upper side by a function of the Carnot efficiency $\eta_C\equiv 1-T_c/T_h$ as $\eta^*\le \eta_C/(2-\eta_C)$. We demonstrate the validity of our theory by showing that the low-dissipation Carnot engine can easily be described by our theory.
Kay Brandner - One of the best experts on this subject based on the ideXlab platform.
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Quantum jump approach to microscopic Heat Engines.
Physical Review Research, 2020Co-Authors: Paul Menczel, Christian Flindt, Kay BrandnerAbstract:Modern technologies could soon make it possible to investigate the operation cycles of quantum Heat Engines by counting the photons that are emitted and absorbed by their working systems. Using the quantum jump approach to open-system dynamics, we show that such experiments would give access to a set of observables that determine the trade-off between power and efficiency in finite-time engine cycles. By analyzing the single-jump statistics of thermodynamic fluxes such as Heat and entropy production, we obtain a family of general bounds on the power of microscopic Heat Engines. Our new bounds unify two earlier results and admit a transparent physical interpretation in terms of single-photon measurements. In addition, these bounds confirm that driving-induced coherence leads to an increase in dissipation that suppresses the efficiency of slowly driven quantum Engines in the weak-coupling regime. A nanoscale Heat engine based on a superconducting qubit serves as an experimentally relevant example and a guiding paradigm for the development of our theory.
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thermodynamic geometry of microscopic Heat Engines
Physical Review Letters, 2020Co-Authors: Kay Brandner, Keiji SaitoAbstract:We develop a general framework to describe the thermodynamics of microscopic Heat Engines driven by arbitrary periodic temperature variations and modulations of a mechanical control parameter. Within the slow-driving regime, our approach leads to a universal trade-off relation between efficiency and power, which follows solely from geometric arguments and holds for any thermodynamically consistent microdynamics. Focusing on Lindblad dynamics, we derive a second bound showing that coherence as a genuine quantum effect inevitably reduces the performance of slow engine cycles regardless of the driving amplitudes. To show how our theory can be applied in practice, we work out a specific example, which lies within the range of current solid-state technologies.
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universal coherence induced power losses of quantum Heat Engines in linear response
Physical Review Letters, 2017Co-Authors: Kay Brandner, Michael Bauer, Udo SeifertAbstract:We identify a universal indicator for the impact of coherence on periodically driven quantum devices by dividing their power output into a classical contribution and one stemming solely from superpositions. Specializing to Lindblad dynamics and small driving amplitudes, we derive general upper bounds on both the coherent and the total power of cyclic Heat Engines. These constraints imply that, for sufficiently slow driving, coherence inevitably leads to power losses in the linear-response regime. We illustrate our theory by working out the experimentally relevant example of a single-qubit engine.
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optimal performance of periodically driven stochastic Heat Engines under limited control
Physical Review E, 2016Co-Authors: Michael Bauer, Kay Brandner, Udo SeifertAbstract:We consider the performance of periodically driven stochastic Heat Engines in the linear response regime. Reaching the theoretical bounds for efficiency and efficiency at maximum power typically requires full control over the design and the driving of the system. We develop a framework which allows us to quantify the role that limited control over the system has on the performance. Specifically, we show that optimizing the driving entering the work extraction for a given temperature protocol leads to a universal, one-parameter dependence for both maximum efficiency and maximum power as a function of efficiency. In particular, we show that reaching Carnot efficiency (and, hence, Curzon-Ahlborn efficiency at maximum power) requires to have control over the amplitude of the full Hamiltonian of the system. Since the kinetic energy cannot be controlled by an external parameter, Heat Engines based on underdamped dynamics can typically not reach Carnot efficiency. We illustrate our general theory with a paradigmatic case study of a Heat engine consisting of an underdamped charged particle in a modulated two-dimensional harmonic trap in the presence of a magnetic field.
