General performance characteristics of real heat engines

Gordon, J. M.; Huleihil, Mahmoud

doi:10.1063/1.351755

Cited by 153 publications

(130 citation statements)

References 12 publications

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“…The next step of refinement for thermodynamic description of the Earth as a heat engine would be to include a parallel leaky wire (conduction) to the Curzon-Ahlborn engine as for the cases in figures 1, 2 and 4. This case has the interesting property that the maximum efficiency does not coincide with the maximum entropy production (Gordon & Huleihil 1992).…”

Section: Discussionmentioning

confidence: 99%

Time-dependent, irreversible entropy production and geodynamics

Regenauer-Lieb

Karrech

Chua

et al. 2010

Phil. Trans. R. Soc. A.

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We present an application of entropy production as an abstraction tool for complex processes in geodynamics. Geodynamic theories are generally based on the principle of maximum dissipation being equivalent to the maximum entropy production. This represents a restriction of the second law of thermodynamics to its upper bound. In this paper, starting from the equation of motion, the first law of thermodynamics and decomposition of the entropy into reversible and irreversible terms, 1 we come up with an entropy balance equation in an integral form. We propose that the extrema of this equation give upper and lower bounds that can be used to constrain geodynamics solutions. This procedure represents an extension of the classical limit analysis theory of continuum mechanics, which considers only stress and strain rates. The new approach, however, extends the analysis to temperature-dependent problems where thermal feedbacks can play a significant role. We apply the proposed procedure to a simple convective/conductive heat transfer problem such as in a planetary system. The results show that it is not necessary to have a detailed knowledge of the material parameters inside the planet to derive upper and lower bounds for self-driven heat transfer processes. The analysis can be refined by considering precise dissipation processes such as plasticity and viscous creep.

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Section: Discussionmentioning

confidence: 99%

Time-dependent, irreversible entropy production and geodynamics

Regenauer-Lieb

Karrech

Chua

et al. 2010

Phil. Trans. R. Soc. A.

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“…Heat leakage is of primary importance for the performance of heat engines as has been shown by Andresen et al [17] and pursued by Patria et al [18]; Chen et al also used models with heat losses to develop the general performance characteristics of engines as was first shown by Gordon and Huleikil [19]. Two characteristic points show up clearly on the curve representing power output versus first law efficiency.…”

Section: Finite Time Thermodynamics (Ftt)mentioning

confidence: 99%

Optimal Thermodynamics—New Upperbounds

Feidt

2009

Entropy

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This paper reviews how ideas have evolved in this field from the pioneering work of CARNOT right up to the present. The coupling of thermostatics with thermokinetics (heat and mass transfers) and entropy or exergy analysis is illustrated through study of thermomechanical engines such as the Carnot heat engine, and internal combustion engines. The benefits and importance of stagnation temperature and irreversibility parameters are underlined. The main situations of constrained (or unconstrained) optimization are defined, discussed and illustrated. The result of this study is a new branch of thermodynamics: Finite Dimensions Optimal Thermodynamics (FDOT).

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“…Similar to the characteristics of the real conventional irreversible heat engines [39][40][41][42][43], the curves of P * versus η are all closed loop-shaped ones and there exist two important points of states: the maximum power point (η P * ,P * max ) and the maximum efficiency point (η max ,P * η ). When the Brownian heat engine is operating in the regions U ≤ U η and U ≥ U P * , the power output will increase with the increase of efficiency.…”

Section: Power Versus Efficiency Characteristic Without External Forcementioning

confidence: 99%

Power and efficiency performances of a micro thermal Brownian heat engine with and without external forces

Ding¹,

Chen²,

Sun³

2010

Braz. J. Phys.

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Power and efficiency performances of a thermal Brownian heat engine, which consists of Brownian particles moving in a periodic sawtooth potential with and without external forces and contacting with alternating hot and cold reservoirs along the space coordinate, are studied in this paper. The performance characteristics are obtained by numerical calculations. It is shown that due to the heat flow via the change of kinetic energy of the particles, the Brownian heat engine is always irreversible and the efficiency can never approach the Carnot efficiency. The influences of the operation parameters, i.e. barrier height of the potential, asymmetry of the potential and temperature ratio of the heat reservoirs on the power output, the efficiency and the current performances of the Brownian heat engine are investigated in detail by numerical analysis. When there is no external force, the power output versus efficiency characteristic curves are closed loop-shaped ones, which are similar to those of real conventional irreversible heat engines; whereas when the external force is considered, the power output versus efficiency characteristic curves of the heat engine changed into open loop-shaped ones. Furthermore, the limited regions of the external force and barrier height of the potential are explored by analyzing the current property of the model. It is shown that by reasonable choice of the parameters, the Brownian heat engine can be controlled to operate in the optimal regimes.

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General performance characteristics of real heat engines

Cited by 153 publications

References 12 publications

Time-dependent, irreversible entropy production and geodynamics

Time-dependent, irreversible entropy production and geodynamics

Optimal Thermodynamics—New Upperbounds

Power and efficiency performances of a micro thermal Brownian heat engine with and without external forces

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