Reflections on the Motive Power of Fire and on Machines Fitted to Develop that Poweris a scientific treatise written by theFrenchmilitary engineerSadi Carnot.[1][2][3][4][5]Published in 1824 in French asRéflexions sur la puissance motrice du feu et sur les machines propres à développer cette puissance,the short book (118 pages in the original) sought to advance a rational theory ofheat engines.At the time, heat engines had acquired great technological and economic importance, but very little was understood about them from the point of view ofphysics.
Carnot'sReflectionsis now widely regarded as a key document in the development ofmodern thermodynamics,and Carnot himself (who published nothing else during his lifetime) has often been identified as the "father of thermodynamics". The book introduced such concepts asthermodynamic efficiency,reversible processes,thethermodynamic cycle,andCarnot's theorem.
Overview
editThe book is considered the founding work ofthermodynamics.[2]: viii It contains the preliminary outline of thesecond law of thermodynamics.Carnot stated thatmotive poweris due to the fall ofcaloric(chute de calorique) from a hot to a cold body, which he analogized tothe workdone by awater wheeldue to a waterfall (chute d'eau).[6]
Despite the fact that the caloric theory of heat was incorrect, Carnot's work brought together three insights that remain relevant and were used by his successors to develop the concept ofentropy:
- The "fall of heat" from a high temperature to a lower temperature is where the work comes from.
- Analyzing a cycle, rather than an open system, is the correct way to analyze a heat engine.
- The concept of a reversible process.
Similar to how theReflectionswas the precursor to the second law, English physicistJames Joule's 1843 paperMechanical equivalent of heatwas the precursor to thefirst law of thermodynamics.In his essay, Carnot also derived the result that later came to be known as theClausius-Clapeyron relation.[7]
Influence
editCarnot's essay received very little attention during Carnot's lifetime. Carnot published nothing else and died in 1832, at the age of 36. However, in 1834 a French mining engineer,Émile Clapeyron,published aMemoir on the Motive Power of Heatthat presented Carnot's analysis graphically.[4]
The German physicistRudolf Clausiuslearned of Carnot's work through Clapeyron's memoir. Clausius corrected Carnot's theory by replacing the conservation of caloric with thework-heat equivalence(i.e., energy conservation). Clausius also put the second law of thermodynamics into mathematical form by defining the concept ofentropy.That work appeared in 1850 in Clausius'sMechanical Theory of Heat.[8]
Another highly influential commentary on Carnot's essay (also through Clapeyron's memoir) was published in 1849 by William Thomson (the futureLord Kelvin), in a paper titledAn Account of Carnot's Theory of the Motive Power of Heat.In that paper, Kelvin said of Carnot's derivation of what would later be called the "Clausius-Clapeyron equation" that "nothing in the whole range of Natural Philosophy is more remarkable than the establishment of general laws by such a process of reasoning."[9]
Because of their respective commentary's on Carnot's essay, modern textbooks on thermodynamics usually introduce a "Clausius statement" and a "Kelvin statement" of the second law of thermodynamics. These statements appear to be different, but they can be shown to be logically equivalent, by an argument based on the Carnot cycle.
See also
editReferences
edit- ^Carnot, Sadi(1824).Réflexions sur la puissance motrice du feu et sur les machines propres à développer cette puissance(in French). Paris: Bachelier.
- ^abCarnot, Sadi(1890).Thurston, Henry(ed.).Reflections on the Motive Power of Heat.Translated byThurston, Henry.New York: J. Wiley & Sons.OL14037447M.(full text of 1897 ed.) (Full text of 1897 edition on Wikisource
)
- ^Carnot, Sadi(1899)."Reflections on the Motive Power of Heat and on Engines Suitable for Developing this Power".InMagie, William Francis(ed.).The Second Law of Thermodynamics: Memoirs by Carnot, Clausius, and Thomson.Translated byMagie, William Francis.Harper & Brothers.OL7072574M.
- ^abCarnot, Sadi;Clapeyron, E.;Clausius, R.(1960). Mendoza, Eric (ed.).Reflections on the Motive Power of Fire – and other Papers on the Second Law of Thermodynamics.New York: Dover Publications.ISBN978-0-486-44641-7.
- ^Carnot, Sadi;Fox, Robert (1986),Reflections on the Motive Power of Fire: a Critical Edition with the Surviving Scientific Manuscripts,Manchester University Press; Lilian Barber Press, New York,ISBN978-0-936508-16-0
- ^La Mer, Victor K. (January 1954)."Some Current Misinterpretations of N. L. Sadi Carnot's Memoir and Cycle".American Journal of Physics.22(1): 20–27.Bibcode:1954AmJPh..22...20L.doi:10.1119/1.1933600.ISSN0002-9505.
- ^Feynman, Richard(1963)."Illustrations of Thermodynamics".The Feynman Lectures on Physics.California Institute of Technology.Retrieved13 December2023.
This relationship was deduced by Carnot, but it is called the Clausius-Clapeyron equation.
- ^Rudolf Clausius(1867).The Mechanical Theory of Heat – with its Applications to the Steam Engine and to Physical Properties of Bodies.London: John van Voorst, 1 Paternoster Row. MDCCCLXVII.
- ^Thomson, William(1849). "An Account of Carnot's Theory of the Motive Power of Heat; with Numerical Results deduced from Regnault's Experiments on Steam".Transactions of the Edinburgh Royal Society.16(5): 541–574.doi:10.1017/S0080456800022481.
External links
edit
- Reflections on the Motive Power of Fire(1824), analysed onBibNum(click "À télécharger" for English analysis)
- Kostic, M (2011). "Revisiting The Second Law of Energy Degradation and Entropy Generation: From Sadi Carnot's Ingenious Reasoning to Holistic Generalization".AIP Conf. Proc.AIP Conference Proceedings.1411(1): 327–350.Bibcode:2011AIPC.1411..327K.CiteSeerX10.1.1.405.1945.doi:10.1063/1.3665247.American Institute of Physics, 2011.ISBN978-0-7354-0985-9.Abstract at:[1].Full article (24 pages[2]), also at[3].