In Hindside 2024 - 1824 Carnot's "Reflexions"
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Also,  Proofs of the Fundamental Laws *  Carnot Cycle Efficiency is Fundamentally Misplaced *

The 200th Sadi Carnot's Reflexions Anniversary (1824-2024):

Sadi Carnot, at age 28, published in 1824, now famous “Réflexions sur la puissance motrice du feu (Reflections on the Motive Power of Fire [1]).” Carnot’s reasoning of “heat engine reversible cycles and their maximum efficiency” is in many ways in par with Einstein’s relativity theory in modern times. It may be among the most important treatises in natural sciences.

No wonder that Sadi Carnot's masterpiece, regardless of flawed assumption, was not appreciated at his time, when his ingenious reasoning of ideal “heat engine reversible cycles” was not fully recognized, and may be truly comprehended by a few, even nowadays. We are often trapped in our own thoughts and words (especially if nonnative) and the subtle holistic meanings are to be read “between the lines.”

2024 Key Reflections on the 1824 Sadi Carnot’s “Réflexions”
M. Kostic
https://doi.org/10.20944/preprints202402.0605.v1

2024 “Key Reflections” on the 1824 “Sadi Carnot’s Réflexions”: This author is not a philosopher nor historian of science, but an engineering thermodynamicist. In that regard and in addition to various philosophical “why & how” treatises and existing historical analyses, the physical and logical “what it is” reflections, as successive Key Points, where a key reasoning infers the next one, along with novel contributions and original generalizations, are presented. We need to keep in mind that in Sadi Carnot’s time (early 1800s) the steam engines were inefficient (below 5%, so the heat in and out were comparable within experimental uncertainty), the conservation of caloric flourished (might be a fortunate misconception), and many critical thermal-concepts, including the conservation of energy (The First Law) were not even established. If Clausius and Kelvin were "fathers of thermodynamics" then Sadi Carnot was the "grandfather" [Kostic, 2023 July 24], or better yet, Sadi Carnot was the "Forefather of Thermodynamics-to-become" [Kostic, 2023 October 29].  ...to be finalized and published in 2024.

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* Carnot Cycle Efficiency is Fundamentally Misplaced 

The Carnot (Ratio) Equality, Qrev/T = constant (as named here in Carnot’s honor, to resound the integral Clausius equality, being its precursor),  is much more important than what it appears at first. Actually, the “Carnot Equality” is probably the most important equation in Thermodynamics and among the most important equations in natural sciences. Carnot’s ingenious reasoning opened the way to the generalization of Thermodynamic reversibility and energy process-equivalency, definition of absolute thermodynamic temperature, and a new thermodynamic material property “Entropy”, as well as the Gibbs Free Energy, one of the most important Thermodynamic functions for the characterization of electro-chemical systems and their equilibriums, thus resulting in the formulation of the universal and far-reaching Second Law of thermodynamics [Kostic: 2008 & 2011 & 2014 & 2020 & 2023].

Note that Carnot erroneously assumed that the same caloric (heat) passes through the engine and extracts (produces) work by lowering its temperature, similar to how the same water flow passes through the water-wheel and produces work by lowering its elevation potential. This error (violating energy conservation), considering the knowledge at the time, in no way diminishes Carnot’s ingenious reasoning and conclusions about limiting, reversible processes and its accurate limitations of heat to work conversion [5].

https://en.wikipedia.org/wiki/Reflections_on_the_Motive_Power_of_Fire * and Historic ASME Landmark
"Carnot stated that motive power is due to the fall of caloric (heat) from a hot to a cold body."

Sadi Carnot (1824) laid ingenious foundations for the Second Law of Thermodynamics and discovery of Entropy before the First Law of energy conservation was even known (Joule, 1843), and long before thermodynamic concepts were established in the second half of the nineteenth century. In historical context, it is hard to comprehend now, how Carnot then, at age 28, ingeniously and fully explained the critical concepts of reversible thermo-mechanical processes and the limits of converting heat to work at inception of the heat engines’ era, when nature of heat was not fully understood. No wonder that Sadi Carnot’s “Réflexions sur la puissance motrice du feu (Reflections on the Motive Power of Fire [4]),” original treatise published in 1824, was not noticed at his time, when his ingenious reasoning of ideal heat engine reversible cycles, is not fully recognized, and may be truly comprehended by a few, even nowadays.

 Elusive Nature of Entropy, Nature of Thermal and Mechanical Energy Transfer and Reflections on the Caloric Theory and Thermal Energy.

"Nothing occurs locally, nor globally in the universe, without mass-energy exchange/conversion and entropy production.
It is crystal-clear (to me) that all confusions related to the far-reaching fundamental Laws of Thermodynamics, and especially the Second Law (Abstract & FULL paper), are due to the lack of their genuine and subtle comprehension." > Sadi Carnot's Reflections <*> Clausius Theory of Heat <*> Kelvin Theory of Heat <

More at "2024 Key Reflections” or UPDATED PDF  Back TO> http://Carnot.MKostic.com *  [More here or Download PDF (39 pp.)]