The theoretical efficiency limits for a combined cycle under the condition of maximum power output

Özkaynak, Süleyman

doi:10.1088/0022-3727/28/10/005

Cited by 10 publications

(12 citation statements)

References 7 publications

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“…A usual way to include internal irreversibilities in the evaluation of the power output of the cycle is based on the idea by Özkaynak et al 31,32 and Chen 33 for Carnot-like cycles. If we denote Q C the heat release to the cold reservoir at temperature T C and Q H the heat absorbed from the hot at temperature T H , we can write the Clausius inequality as an equality by introducing a term I R Ͼ 1 in such a way that…”

Section: A Internal Irreversibilitiesmentioning

confidence: 99%

Theoretical and simulated models for an irreversible Otto cycle

Curto-Risso

Medina

Hernández

2008

Journal of Applied Physics

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We show in this work that a finite-time-thermodynamics model of an irreversible Otto cycle is suitable to reproduce performance results of a real spark ignition heat engine. In order to test our model we have developed a computer simulation including a two-zone combustion model and compared the evolution of the performance parameters of the simulated engine as functions of the rotational speed ͑͒ with those obtained from a simple theoretical scheme including chemical reactions. A theoretical Otto cycle with irreversibilities arising from friction, heat transfer through the cylinder walls, and internal losses properly reproduces simulation results by considering extreme temperatures and mass inside the cylinder as functions of. Furthermore we obtain realistic values for the parameters characterizing global irreversibilities, their evolution with , and a clearer understanding of their physical origin not always well established in theoretical models.

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Section: A Internal Irreversibilitiesmentioning

confidence: 99%

Theoretical and simulated models for an irreversible Otto cycle

Curto-Risso

Medina

Hernández

2008

Journal of Applied Physics

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“…Ghasemkhani et al [65] performed multiobjective optimization of combined Carnot HE. Some scholars [110][111][112][113][114][115][116][117][118] have also studied performance characteristics of combined Carnot HEs with various loss issues and different optimization objectives. For quantum energy systems, Meng et al [119] modeled a three reservoirs endoreversible combined quantum Carnot HE with one as intermediate heat reservoir and Chen et al [120] modeled irreversible two-stage combined HE with quantum gases.…”

Section: Introductionmentioning

confidence: 99%

Modeling and Performance Optimization of an Irreversible Two-Stage Combined Thermal Brownian Heat Engine

Chen

Ding

Chen

et al. 2021

Entropy

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Based on finite time thermodynamics, an irreversible combined thermal Brownian heat engine model is established in this paper. The model consists of two thermal Brownian heat engines which are operating in tandem with thermal contact with three heat reservoirs. The rates of heat transfer are finite between the heat engine and the reservoir. Considering the heat leakage and the losses caused by kinetic energy change of particles, the formulas of steady current, power output and efficiency are derived. The power output and efficiency of combined heat engine are smaller than that of single heat engine operating between reservoirs with same temperatures. When the potential filed is free from external load, the effects of asymmetry of the potential, barrier height and heat leakage on the performance of the combined heat engine are analyzed. When the potential field is free from external load, the effects of basic design parameters on the performance of the combined heat engine are analyzed. The optimal power and efficiency are obtained by optimizing the barrier heights of two heat engines. The optimal working regions are obtained. There is optimal temperature ratio which maximize the overall power output or efficiency. When the potential filed is subjected to external load, effect of external load is analyzed. The steady current decreases versus external load; the power output and efficiency are monotonically increasing versus external load.

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“…In order to obtain a more realistic combined cycle model, Chen [ 42 ] established a generalized irreversible combined HE model considering thermal resistance, heat leakage loss, and internal irreversibility. Then, different performance evaluations and research methods have been taken into account, including power output [ 43 , 44 , 45 , 46 , 47 ] and entransy loss [ 48 , 49 ]. Iyyappan and Johal [ 50 ] analyzed the linear irreversible two-stage combined HE with low dissipation.…”

Section: Introductionmentioning

confidence: 99%

Performance Analysis and Optimization for Irreversible Combined Carnot Heat Engine Working with Ideal Quantum Gases

Chen

Meng

et al. 2021

Entropy

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An irreversible combined Carnot cycle model using ideal quantum gases as a working medium was studied by using finite-time thermodynamics. The combined cycle consisted of two Carnot sub-cycles in a cascade mode. Considering thermal resistance, internal irreversibility, and heat leakage losses, the power output and thermal efficiency of the irreversible combined Carnot cycle were derived by utilizing the quantum gas state equation. The temperature effect of the working medium on power output and thermal efficiency is analyzed by numerical method, the optimal relationship between power output and thermal efficiency is solved by the Euler-Lagrange equation, and the effects of different working mediums on the optimal power and thermal efficiency performance are also focused. The results show that there is a set of working medium temperatures that makes the power output of the combined cycle be maximum. When there is no heat leakage loss in the combined cycle, all the characteristic curves of optimal power versus thermal efficiency are parabolic-like ones, and the internal irreversibility makes both power output and efficiency decrease. When there is heat leakage loss in the combined cycle, all the characteristic curves of optimal power versus thermal efficiency are loop-shaped ones, and the heat leakage loss only affects the thermal efficiency of the combined Carnot cycle. Comparing the power output of combined heat engines with four types of working mediums, the two-stage combined Carnot cycle using ideal Fermi-Bose gas as working medium obtains the highest power output.

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The theoretical efficiency limits for a combined cycle under the condition of maximum power output

Cited by 10 publications

References 7 publications

Theoretical and simulated models for an irreversible Otto cycle

Theoretical and simulated models for an irreversible Otto cycle

Modeling and Performance Optimization of an Irreversible Two-Stage Combined Thermal Brownian Heat Engine

Performance Analysis and Optimization for Irreversible Combined Carnot Heat Engine Working with Ideal Quantum Gases

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