NOTE: www.kostic.niu.edu/ CHANGED TO www.niu.edu/kostic OR https://kostic.niu.edu
Follow-up 2024-1824 Carnot's Legacy:
Internal Energy Quality - Reversible Equivalency
Nature of Heat and Thermal Energy & Reflection on Caloric Heat and Thermal Energy
http://Carnot.MKostic.com
Sadi Carnot's Legacy 1824-2024 Presentations (PPT & PDF>Updated)
at International Colloquium (PolyTechnique.edu) (1drv): →Photo; → R.T.Vidéo
More at http://Carnot.MKostic.com and http://Carnot1824-2024Reflections.MKostic.com
See also: 2LT * Selected Presentations and Proofs of the Fundamental Laws
Engineering Thermodynamics: Fundamentals and Challenges by Milivoje Kostic: PPT →Vidéo
FOLLOW-UP (PDF):
Regarding presentations and comments at the “Sadi Carnot’s Legacy International Colloquium”
at École Polytechnique, France, 16-18 September 2024
Completing this work has been further motivated by presentations and comments
at the “Sadi Carnot’s Legacy International Colloquium”
* Carnot Cycle Efficiency is Fundamentally Misplaced *
Internal energy, in addition to quantity, has quality: The "Pond analogy," is misleading (PDF)
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It is impossible to generate entropy without work dissipation:
Planck's claim of “entropy generation without work dissipation” is disproved by the “Reversible equivalency”
M. Kostic < www.niu.edu/kostic > November 2024
Summary:
Planck challenged the universality of “dissipation of energy as related to the entropy generation concept” by stating, “There are irreversible processes in which the final and initial states show exactly the same form of energy, e.g., the diffusion of two perfect gases, or further dilution of a dilute solution. Such processes are accompanied by no perceptible transference of heat, nor by external work, nor by any noticeable transformation of energy. They occur only for the reason that they lead to an appreciable increase in entropy.” However, it is proven here by the “Reversible equivalency” that any entropy generation is due and must be accompanied by commensurate work dissipation without exception, thus disproving the Planck’s claims. Furthermore, the claim that “final and initial states show exactly the same form of energy” is misplaced and inaccurate, regardless that energy quantity is the same compared to the initial state, but the “form of energy” and its quality, quantified by the respective work potentials or free energy, are not the same, since entropy of the final state is increased by entropy generation and the work potential is diminished by irreversible dissipation.
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Carathéodory’s Second law statement of “adiabatic inaccessibility of certain states”
is equivalent to “inaccessibility of states that require impossible entropy destruction”
M. Kostic < www.niu.edu/kostic > November 2024
Summary:
Carathéodory’s principle, “In the neighborhood of any equilibrium state of a physical system with any number of thermodynamic coordinates, there exist states which are inaccessible by adiabatic processes,” is another definition of the Second law of thermodynamics. Since the “Reversible equivalency” proves that all definitions of the Second law are equivalent; namely, if any definition could be violated then all others could be also violated. Therefore, if the Carathéodory’s principle could be violated, it could be equivalent to any other process with impossible entropy destruction, like adiabatic processes with entropy reduction or spontaneous heat transfer from lower to higher temperature, or spontaneous uphill flow, among others.
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Internal energy, in addition to quantity, has quality depending if work or heat is stored:
The "Pond analogy," based on “complete” irreversible dissipation, is misleading
M. Kostic < www.niu.edu/kostic > November 2024
Summary (DRAFT):
When heat Q and work W are transferred and stored within a material system, its internal energy U will increase for their total amounts (Q+W) but its quality (reflected by its final state, i.e. its work-potential WP or Exergy, the WP increase with reference to the initial state) will depend not only on the sum of work and heat amounts but also on their ratio and the WP dissipation if any or if “complete,” during the storing process; i.e., if heat and work are stored reversibly, partially irreversibly, or “completely” irreversibly, the latter if the transferred WP [including WPQ=Q(1-T/Th), the Carnot’s WPQ of heat Q at Th] is completely dissipated and stored as heat only.
Irreversible heating with higher source temperature and correspondingly lower source entropy, interestingly but unavoidably, will be equivalent to the reversible heating only, since such source heat at Th will inevitably dissipate to the lower system temperature T of the system with commensurate entropy generation, resulting to the final state as with reversibly heating, the latter provided by a variable heat source with minimum required temperature T over maximum entropy for the same heat transferred.
The “Pond analogy” and those “conventional” statements that may imply that “the internal energy and the final state is the same regardless if heat and/or work were transferred to a system” is only valid for the “completely irreversible processes” in simple incompressible systems (where heat could be stored only). Therefore, the “Pond analogy” is not valid in general and hence misleading, since internal energy is the state property and has both, the conserved quantity (First law) and the quality (Second law; the free-energy, or work potential WP, or Exergy) that depend on the work/heat ratio and irreversible dissipation during their storage.
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Regarding presentations and comments at the “Sadi Carnot’s Legacy International Colloquium”
at École Polytechnique, France, 16-18 September 2024:
Planck * Caratheodory * Energy Quality