scholarly journals A History of Thermodynamics: The Missing Manual

Entropy ◽  
2020 ◽  
Vol 22 (1) ◽  
pp. 77 ◽  
Author(s):  
Wayne M. Saslow
Keyword(s):  
Thermodynamic Temperature ◽  
Ideal Gas ◽  
Absolute Temperature ◽  
Carnot Cycle ◽  
State Function ◽  
Gas Temperature ◽  
Conservation Of Energy ◽  
Engine Efficiency ◽  
Heat Conservation ◽  
History Of

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.

An Easier Approach to Introduce Entropy in Undergraduate Thermodynamics Classes

2018 ◽  
Author(s):  
Yousef Haseli
Keyword(s):  
Temperature Scale ◽  
Thermodynamic Temperature ◽  
Ideal Gas ◽  
Original Method ◽  
Carnot Cycle ◽  
Rational Argument ◽  
The Common ◽  
Shed Light ◽  
Thermodynamic Temperature Scale ◽  
Clausius Inequality

The common tutorial method of teaching entropy is far twisted and complicated. The convention is to first present Carnot corollaries followed by a “rational argument” to justify the corollaries. In the next step, the efficiency of Carnot engine is argued to be solely dependent on the thermal reservoirs temperatures. Then, thermodynamic temperature scale is introduced to show QL/QH equals TL/TH followed by the Clausius inequality, and finally introducing entropy S. It is not surprising why entropy has been one of the most difficult concepts to teach or learn. The way it is taught in textbooks is not straight unlike many other properties and concepts that are comparably much less cumbersome to understand. Interesting to note is that the inventor of entropy; Clausius, derived the famous Carnot efficiency by simply using the p-V diagram of a Carnot cycle operating with an ideal gas. The objective of this article is to shed light to the original method of Clausius and to present a simple and easy-to-digest approach, so students can better understand where entropy is originated from. Furthermore, we will show that the proof of Carnot corollaries is not concrete and certain objections can be raised.

Ideal gas processes – and two ideal gas case studies too

2018 ◽  
Author(s):  
Dennis Sherwood ◽  
Paul Dalby
Keyword(s):  
Case Studies ◽  
Constant Pressure ◽  
Ideal Gas ◽  
Heat Capacities ◽  
Carnot Cycle ◽  
State Function ◽  
Ideal Gases ◽  
First Case ◽  
The Ideal

This chapter brings together, and builds on, the results from previous chapters to provide a succinct, and comprehensive, summary of all key relationships relating to ideal gases, including the heat and work associated with isothermal, adiabatic, isochoric and isobaric changes, and the properties of an ideal gas’s heat capacities at constant volume and constant pressure. The chapter also has two ‘case studies’ which use the ideal gas equations in broader, and more real, contexts, so showing how the equations can be used to tackle, successfully, more extensive systems. The first ‘case study’ is the Carnot cycle, and so covers all the fundamentals required for the proof of the existence of entropy as a state function; the second ‘case study’ is the ‘thermodynamic pendulum’ – a system in which a piston in an enclosed cylinder oscillates to and fro like a pendulum under gravity, in both the absence, and presence, of friction.

scholarly journals On the ambiguity of an ideal gas entropy concept

2020 ◽  
Vol 22 (4) ◽  
pp. 32-42
Author(s):  
V. G. Kiselev
Keyword(s):  
Critical Analysis ◽  
Ideal Gas ◽  
Absolute Temperature ◽  
Carnot Cycle ◽  
Perfect Gas ◽  
Reversible Process ◽  
Thermodynamic Potentials ◽  
Adiabatic Processes ◽  
Isothermal Processes

Based on a critical analysis of the existing characteristics of an ideal gas and the theory of thermodynamic potentials, the article considers its new model, which includes the presence of an ideal gas in addition to kinetic energy of potential (chemical) energy, in the framework of which the isothermal and adiabatic processes in it are studied both reversible and irreversible, in terms of changes in the entropy of the system in question, observed in case. In addition, a critical analysis was made of the process of introducing the concept of entropy by R. Clausius, as a result of which the main requirements for entropy were established, the changes of which are observed in isothermal and adiabatic quasistatic processes, in particular, it was revealed that if in isothermal processes involving one in a perfect gas, the entropy ST is uniquely characterized by the value , regardless of whether the process is reversible or not, then when the adiabatic processes occur, the only requirement made of them is the condition of mutual destruction adiabats in this Carnot cycle. As a result of this circumstance, in fact, in thermodynamics various “adiabatic” entropies are used, namely; const SA = const R ln V  и  C V ln T , and in addition, as established in this paper, CV, which leads, despite the mathematically perfect introduction of the concept of entropy for the Carnot cycle, to the impossibility of its unambiguous interpretation and, therefore, the determination of its physicochemical meaning even for perfect gas. A new concept is introduced in the work: “total” entropy of an ideal gas SS = R ln V + C V , satisfying the criteria of R. Clausius, on the basis of which it was established that this type of entropy multiplied by the absolute temperature characterizes a certain level of potential energy of the system, which can besuccessively converted to work in an isothermal reversible process, with the supply of an appropriate amount of heat, and in the adiabatic reversible process under consideration.

scholarly journals Fundamental laws of nature confirmed by free fall

2021 ◽  
Author(s):  
Grit kalies
Keyword(s):  
Laws Of Nature ◽  
Free Fall ◽  
Mass Conservation ◽  
History Of Physics ◽  
Conservation Of Energy ◽  
History Of ◽  
Real Mass ◽  
Level I ◽  
First Time ◽  
Mass Increase

Abstract The principle of conservation of energy is often demonstrated by means of free fall. In mechanics, states of a body with potential and kinetic energy are energetically compared. Based on the mass concept of relativistic mechanics, energy conservation is considered to be linked with mass conservation. We show that the process of free fall can be interpreted more thoroughly, if the cause-effect principle and the mass concept of thermodynamics are applied. For the first time in the history of physics, the mechanism of energy conversion in free fall can be shown, which is valid for any object, whether body or elementary particle. The phenomenon of falling confirms the following facts to be valid of on a fundamental level: i) The principle of conservation of energy, ii) The equivalence of inertial and gravitational mass, iii) The real mass increase of any object with its velocity, and iv) The continuousness of space and time. At the end of the article we explain why the theory of general relativity is unsuitable to demonstrate the conservation of energy during free fall.

Thermoelasticity

1997 ◽  
Author(s):  
Burak Erman ◽  
James E. Mark
Keyword(s):  
Equation Of State ◽  
Elastic Deformation ◽  
Additional Assumption ◽  
Polymer Network ◽  
Ideal Gas ◽  
Absolute Temperature ◽  
Constant Volume ◽  
Conformational Energy ◽  
Network Chain ◽  
Constant Deformation

The important postulate that intermolecular interactions are independent of extent of deformation leads directly to the conclusion that such interactions cannot contribute to an energy of elastic deformation ΔEel at constant volume. In the earliest theories of rubberlike elasticity, it was additionally assumed that, intramolecular contributions to ΔEel were likewise nil. In this idealization that the total ΔEel is zero, the elastic retractive force exhibited by a deformed polymer network would be entirely entropic in origin. At the molecular level, this would correspond, of course, to assuming all configurations of a network chain to be of exactly the same conformational energy and thus the average configuration to be independent of temperature. Under these circumstances, the dependence of stress on temperature is strikingly simple, as shown, for example, by the equation . . . f* = υkT/V (〈r2〉i/〈r2〉0)(α – α-2) . . . . . . (9.1) . . . that characterizes a polymer network in elongation where, it should be recalled, 〈r2〉i3/2 is proportional to the volume of the network. This additional assumption that 〈r2〉0 is independent of temperature would lead to the prediction that the elastic stress determined at constant volume and elongation α is directly proportional to the absolute temperature. Such network chains would be akin to the particles of an ideal gas, which would obey the equation of state p = nRT(1/V) and thus exhibit a pressure at constant deformation (1/V) likewise directly proportional to the temperature.

scholarly journals The CBR frequency spectrum below 1 GHz recent results and new observations

1992 ◽  
Vol 9 ◽  
pp. 297-298
Author(s):  
G. Sironi ◽  
G. Bonelli ◽  
M. Gervasi
Keyword(s):  
Frequency Spectrum ◽  
Absolute Temperature ◽  
History Of ◽  
The Absolute ◽  
The Universe

AbstractWe are carrying on measurements of the absolute temperature of the CBR at various frequencies near and below 1 GHz, looking for so far undetected deviations from a planckian spectrum. The amplitude and frequency of those distortions can give precious information about the history of the Universe.

scholarly journals A model-based and experimental approach for the determination of suitable variable valve timings for cold start in partial load operation of a passenger car single-cylinder diesel engine

2018 ◽  
Vol 20 (1) ◽  
pp. 141-154 ◽  
Author(s):  
P Maniatis ◽  
U Wagner ◽  
T Koch
Keyword(s):  
Diesel Engine ◽  
Experimental Investigations ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Warm Up ◽  
One Dimensional ◽  
Engine Efficiency ◽  
Residual Gas ◽  
Dimensional Simulation ◽  
Exhaust Gas Temperature

A manipulation of the charge exchange allows controlling the amount of residual gas during engine warm-up. The residual gas during the warm-up phase leads to an increase of the exhaust gas temperature and supports to reach the exhaust after-treatment system operating temperature faster. In addition, the warm residual gas increases the combustion chamber temperature, which reduces the HC and CO emissions. However, fuel consumption increases. For that reason, such heating measures should be the best compromise of both, exhaust gas temperature increase and engine efficiency, in order to provide efficient heating strategies for passenger car diesel engines. Therefore, simulative and experimental investigations are carried out at the Institute of Internal Combustion Engines of the Karlsruhe Institute of Technology to establish a reliable cam design methodology. For the experimental investigations, a modern research single-cylinder diesel engine was set up on a test bench. In addition, a one-dimensional simulation model of the experimental setup was created in order to simulate characteristics of valve lift curves and to investigate their effects on the exhaust gas temperature and the exhaust gas enthalpy flow. These simulations were based on design of experiments (DoE), so that all characteristics can be used sustainably for modeling and explaining their influences on the engine operation. This methodology allows numerically investigating promising configurations and deriving cam contours which are manufactured for testing. To assess the potential of these individual configurations, the results obtained were compared with each other as well as with the series configuration. Results show that the combination of DoE and one-dimensional simulation for the design of camshaft contours is well suited which was also validated with experimental results. Furthermore, the potential of residual gas retention by favorable configurations with a second event already revealed in various publications could be confirmed with respect to exhaust gas temperature increase and engine efficiency.

Emanuel Swedenborg: Psychologist

1912 ◽  
Vol 58 (242) ◽  
pp. 448-464
Author(s):  
Hubert J. Norman
Keyword(s):  
Planetary Motion ◽  
The Sun ◽  
Market Place ◽  
Place Making ◽  
Conservation Of Energy ◽  
History Of Thought ◽  
Average Person ◽  
Emanuel Swedenborg ◽  
History Of ◽  
The Brain

If there is one fact which stands out more plainly than any other when one considers the life and work of Emanuel Swedenborg it is this—that whatever value may be attached to the writings of the later or visionary period of his life, there is no doubt they have served to obscure his eminence as a clear-sighted scientific investigator during the earlier part of his existence. That this is so can hardly be denied even by the most enthusiastic Swedenborgian, for if the average person be asked what associations the name of Swedenborg conjures up, he will at once reply that he was a man who saw visions and dreamed dreams, who said that he saw the heavens opened unto him, and who wrote an account of the same in a work entitled Heaven and Hell. A further effort of association will perchance link his name with those of Jacob Boehme, of St. Theresa, of Mahomet, and of others who have exhibited similar symptoms; but, except in rare instances, any conception of his scientific attainments even in the most meagre degree is almost non-existent. He is passed over practically without comment by most of the historians of philosophy or of psychology; and his fate has for the most part been to suffer from the uncritical eulogies of enthusiastic disciples, or from the criticism of those whose knowledge of him is limited to the later period of his life with which his mystical writings are associated. In both cases he has suffered—and the term is used advisedly even in the first instance—because scientific men have been repelled from studying one whom they have conceived as immersed in the business of describing visions of the hereafter and consequently as hardly being likely to have given much time to the concrete realities with which science should deal. Most of the discussions as to Swedenborg's place in the history of thought have centred round the later period of his life; and the mental trouble which came upon him in the midst of his scientific activities and altered the whole course of his intellectual career, sore affliction as it was during his lifetime, has not yet ceased to cling to his name, and to militate against his recognition as one of the clearest thinkers of his time, or indeed of any time. Rational psychology owes a great debt to him; like many debts it has remained long unpaid. This, too, whilst many an inferior thinker has had his wares cried in the market-place, making of real obscurity an appearance of profoundity. It is not proposed herein to deal with Swedenborg in a more comprehensive way than as a psychologist; to do more would necessitate such an acquaintance with science and with technology as but few possess. For it was Swedenborg who “introduced the calculus into Sweden. … He began the science of crystallography. He reasoned out before Franklin the identity of lightning and electricity. He anticipated Laplace in the discovery that planets and planetary motion are derived from the sun. He discovered the animation of the brain. The law of the conservation of energy seems to have been anticipated in his doctrine of action and reaction equal and necessary to life.” So says a writer in a recent authoritative work (1); and even if the claims be debatable, it is obvious than any discussion of them would but serve to obscure our more immediate purpose, which is to deal with Swedenborg as an exponent of psychology.

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