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Open AccessArticle

A History of Thermodynamics: The Missing Manual

Department of Physics, Texas A&M University, College Station, TX 77843-4242, USA
Entropy 2020, 22(1), 77; https://doi.org/10.3390/e22010077
Received: 19 December 2019 / Revised: 30 December 2019 / Accepted: 31 December 2019 / Published: 7 January 2020
(This article belongs to the Collection Foundations and Ubiquity of Classical Thermodynamics)
We present a history of thermodynamics. Part 1 discusses definitions, a pre-history of heat and temperature, and steam engine efficiency, which motivated thermodynamics. Part 2 considers in detail three heat conservation-based foundational papers by Carnot, Clapeyron, and Thomson. For a reversible Carnot cycle operating between thermal reservoirs with Celsius temperatures t and t + d t , heat Q from the hot reservoir, and net work W, Clapeyron derived W / Q = d t / C ( t ) , with C ( t ) material-independent. Thomson used μ = 1 / C ( t ) to define an absolute temperature but, unaware that an additional criterion was needed, he first proposed a logarithmic function of the ideal gas temperature T g . Part 3, following a discussion of conservation of energy, considers in detail a number of energy conservation-based papers by Clausius and Thomson. As noted by Gibbs, in 1850, Clausius established the first modern form of thermodynamics, followed by Thomson’s 1851 rephrasing of what he called the Second Law. In 1854, Clausius theoretically established for a simple Carnot cycle the condition Q 1 / T 1 + Q 2 / T 2 = 0 . He generalized it to i Q i / T g , i = 0 , and then d Q / T g = 0 . This both implied a new thermodynamic state function and, with appropriate integration factor 1 / T , the thermodynamic temperature. In 1865, Clausius named this new state function the entropy S. View Full-Text
Keywords: thermodynamics; energy; heat; temperature; entropy thermodynamics; energy; heat; temperature; entropy
MDPI and ACS Style

Saslow, W.M. A History of Thermodynamics: The Missing Manual. Entropy 2020, 22, 77.

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