Surroundings-based and system-based heat and work definitions: Which one is the most suitable?

Anacleto, Joaquim; Ferreira, J.M.

doi:10.1016/j.jct.2007.06.004

Cited by 6 publications

(14 citation statements)

References 9 publications

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“…However, as previously mentioned, there are different definitions of Q and W that are currently subject of debate [e.g. [4][5][6][7][8][9][10][11][12][13][14][15][16][17], in particular when irreversible processes are under study.…”

Section: Common Heat and Work Definitionsmentioning

confidence: 99%

“…This result shows that there subsist in the literature non-equivalent definitions of heat and work, which means that the transfer of energy cannot be univocally categorized as heat or work. Since such definitions do not violate the First Law, this law cannot be the solely criterion to decide which definitions are correct [10].…”

Section: Common Heat and Work Definitionsmentioning

confidence: 99%

See 1 more Smart Citation

On thermodynamical work and heat definitions and their consistency regarding the second law

Anacleto

Pereira

Gonçalves

2010

Rev. Bras. Ensino Fís.

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We start by presenting an overview of the various definitions of heat and work found in the literature. Then, we consider several examples for analysis and show that the theory of Thermodynamics requires a precise definition of such quantities. The comparison regarding the Second Law of the system-based and surroundings-based definitions of heat and work is undertaken leading to the conclusion that the definitions of such concepts should be based on variables external to the system.

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Section: Common Heat and Work Definitionsmentioning

confidence: 99%

Section: Common Heat and Work Definitionsmentioning

confidence: 99%

On thermodynamical work and heat definitions and their consistency regarding the second law

Anacleto

Pereira

Gonçalves

2010

Rev. Bras. Ensino Fís.

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“…Although the mathematics required to deal with its laws and concepts is not complex, the aforementioned subtleties make thermodynamics a difficult teaching and learning subject. These difficulties have, however, stimulated interesting discussions [1][2][3][4][5][6][7][8][9][10][11] whose aim is to make thermodynamics unambiguous and attractive, thus reinforcing its formative role for physics and engineering students.…”

Section: Introductionmentioning

confidence: 99%

When an adiabatic irreversible expansion or compression becomes reversible

2009

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This paper aims to contribute to a better understanding of the concepts of a reversible process and entropy. For this purpose, an adiabatic irreversible expansion or compression is analysed, by considering that an ideal gas is expanded (compressed), from an initial pressure P i to a final pressure P f , by being placed in contact with a set of N work reservoirs with pressures decreasing (increasing) in a geometric or arithmetic progression. The gas entropy change S is evaluated and it is clearly shown that S > 0 for any finite N, but as the number of work reservoirs goes to infinity the entropy change goes to zero, i.e. the process becomes reversible. Additionally, this work draws attention to the work reservoir concept, which is virtually ignored in the literature, and to its analogy with the commonly used heat reservoir concept. Finally, it complements and reinforces an earlier study dealing with irreversible cooling or heating so that the synergy created by the two studies is important from both theoretical and educational standpoints.

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“…Examples of interactions are usually presented with the purpose of explaining heat and work concepts as energy transfer resulting, respectively, from a difference in temperature and from the forces acting on a moving system boundary. This approach has the advantage of being intuitive but, according to some recent publications [1,2], could be quite restrictive. The relevance of the concepts of heat and work in expressing interactions between the system and its surroundings is emphasized by their role in the formulation of the well-established laws of thermodynamics, namely, of the first and second laws.…”

Section: Introductionmentioning

confidence: 99%

“…Since thermodynamics is a mature science, it is surprising that such concepts are still the subject of debate in the literature. Indeed, recent publications have contributed to clarify and establish general and standardized heat and work definitions [1][2][3][4][5][6][7][8][9]. Such definitions are not incompatible with the usual intuitive ones, but they have wider applicability in spite of, in some situations, being counter-intuitive and having unexpected properties.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamical interactions: subtleties of heat and work concepts

Anacleto

2008

Eur. J. Phys.

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This paper focuses on the determination of the final equilibrium state when two ideal gases, isolated from the exterior and starting from preset initial conditions, interact with each other through a piston. Depending on the piston properties, different processes take place and also different sets of equilibrium conditions must be satisfied. Three cases are analysed, namely, when (case 1) the piston is a heat conductor and free to move, (case 2) the piston allows heat conduction but its position is fixed, and (case 3) the piston is free to move but it is adiabatic (so no heat can be exchanged). Cases 1 and 2 have straightforward solutions, but it is shown that case 3 leads to an undeterminable final state. Even though this last situation seems to be strange and difficult, mechanical and thermodynamical analyses are performed. It is shown that the determinability of the final state depends on whether friction is considered or not. Carried out numerically, both analyses provide consistent results and not only do they enable an interesting and useful discussion regarding the concepts of energy, heat, work and entropy, but they also reinforce some ideas which were recently published.

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Surroundings-based and system-based heat and work definitions: Which one is the most suitable?

Cited by 6 publications

References 9 publications

On thermodynamical work and heat definitions and their consistency regarding the second law

On thermodynamical work and heat definitions and their consistency regarding the second law

When an adiabatic irreversible expansion or compression becomes reversible

Thermodynamical interactions: subtleties of heat and work concepts

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