scholarly journals Nature of Heat and Thermal Energy: From Caloric to Carnot’s Reflections, to Entropy, Exergy, Entransy and Beyond

Entropy ◽  
2018 ◽  
Vol 20 (8) ◽  
pp. 584 ◽  
Author(s):  
Milivoje M. Kostic
Keyword(s):  
Energy Transfer ◽  
Internal Energy ◽  
Thermal Energy ◽  
Mechanical Energy ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Generalized Entropy ◽  
Critical Issues ◽  
Thermal Phenomena

The nature of thermal phenomena is still elusive and sometimes misconstrued. Starting from Lavoisier, who presumed that caloric as a weightless substance is conserved, to Sadi Carnot who erroneously assumed that work is extracted while caloric is conserved, to modern day researchers who argue that thermal energy is an indistinguishable part of internal energy, to the generalization of entropy and challengers of the Second Law of thermodynamics, the relevant thermal concepts are critically discussed here. Original reflections about the nature of thermo-mechanical energy transfer, classical and generalized entropy, exergy, and new entransy concept are reasoned and put in historical and contemporary contexts, with the objective of promoting further constructive debates and hopefully resolve some critical issues within the subtle thermal landscape.

Reflections on the Motive Power of Heat II

2010 ◽  
Author(s):  
George J. Mahl
Keyword(s):  
Thermal Energy ◽  
Mechanical Energy ◽  
Second Law Of Thermodynamics ◽  
Electrical Energy ◽  
Rankine Cycle ◽  
Second Law ◽  
Carnot Cycle ◽  
Original Analysis ◽  
Underlying Basis ◽  
The Relationship

This paper explores and challenges the underlying basis of the Second Law of Thermodynamics. The second law of thermodynamics and its related equations define the relationship between thermal energy and its conversion into mechanical work. The second law of thermodynamics and its equations are based on theory developed by analysis of the Carnot cycle, then with a leap of faith, applies this theory and these equations to the Rankine cycle and to the general conversion of thermal energy into mechanical energy. This paper explores the original analysis, which forms the basis of the second law of thermodynamics, and offers new analysis which may form a new understanding of thermodynamics. If proven correct, this new understanding may unlock tremendous resources for the production of mechanical and electrical energy.

First and second laws of thermodynamics: relationship, “inconsistency”, hidden effects

2020 ◽  
pp. 63-73
Author(s):  
A. M. Savchenko ◽  
Yu. V. Konovalov ◽  
A. V. Laushkin
Keyword(s):  
Free Energy ◽  
Internal Energy ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Entropy Of Mixing ◽  
Ideal Mixing ◽  
Laws Of Thermodynamics ◽  
Relationship Of ◽  
The Relationship

The relationship of the first and second laws of thermodynamics based on their energy nature is considered. It is noted that the processes described by the second law of thermodynamics often take place hidden within the system, which makes it difficult to detect them. Nevertheless, even with ideal mixing, an increase in the internal energy of the system occurs, numerically equal to an increase in free energy. The largest contribution to the change in the value of free energy is made by the entropy of mixing, which has energy significance. The entropy of mixing can do the job, which is confirmed in particular by osmotic processes.

Connections Between Stability, Convexity of Internal Energy, and the Second Law for Compressible Newtonian Fluids

2005 ◽  
Vol 72 (2) ◽  
pp. 299-300 ◽  
Author(s):  
Stephen E. Bechtel ◽  
Francis J. Rooney ◽  
M. Gregory Forest
Keyword(s):  
Convex Function ◽  
Bulk Modulus ◽  
Specific Heat ◽  
Internal Energy ◽  
Linear Stability ◽  
Specific Volume ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Isothermal Bulk Modulus ◽  
Rest State

In this note we provide proofs of the following statements for a compressible Newtonian fluid: (i) internal energy being a convex function of entropy and specific volume is equivalent to nonnegativity of both specific heat at constant volume and isothermal bulk modulus; (ii) convexity of internal energy together with the second law of thermodynamics imply linear stability of the rest state; and (iii) linear stability of the rest state together with the second law imply convexity of internal energy.

scholarly journals Teach Second Law of Thermodynamics via Analysis of Flow through Packed Beds and Consolidated Porous Media

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 116 ◽  
Author(s):  
Rajinder Pal
Keyword(s):  
Porous Media ◽  
Entropy Generation ◽  
Power Plants ◽  
Mechanical Energy ◽  
Fluid Velocity ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Packed Beds ◽  
Factors Affecting ◽  
Flow Through

The second law of thermodynamics is indispensable in engineering applications. It allows us to determine if a given process is feasible or not, and if the given process is feasible, how efficient or inefficient is the process. Thus, the second law plays a key role in the design and operation of engineering processes, such as steam power plants and refrigeration processes. Nevertheless students often find the second law and its applications most difficult to comprehend. The second law revolves around the concepts of entropy and entropy generation. The feasibility of a process and its efficiency are directly related to entropy generation in the process. As entropy generation occurs in all flow processes due to friction in fluids, fluid mechanics can be used as a tool to teach the second law of thermodynamics and related concepts to students. In this article, flow through packed beds and consolidated porous media is analyzed in terms of entropy generation. The link between entropy generation and mechanical energy dissipation is established in such flows in terms of the directly measurable quantities such as pressure drop. Equations are developed to predict the entropy generation rates in terms of superficial fluid velocity, porous medium characteristics, and fluid properties. The predictions of the proposed equations are presented and discussed. Factors affecting the rate of entropy generation in flow through packed beds and consolidated porous media are identified and explained.

A perpetuum mobile of second kind is possible

2016 ◽  
pp. 3583-3584
Author(s):  
Kalev Jaik
Keyword(s):  
Low Temperature ◽  
Thermal Energy ◽  
Energy Resource ◽  
Second Law Of Thermodynamics ◽  
Second Law

 Great and important discoveries befall there seldom, but this one is just such a discovery. The discovery is in physics which disproves the validness of the second law of thermodynamics and several others up to now conceptions of the physics, and can open a new and inexhaustible energy resource for the mankind --- the low temperature thermal energy of the environment. In short is my discovery such that against the principles of the up to now physics and the second law of thermodynamics is a perpetuum mobile of the second kind possible, and entropy is not irreversible.

Thermodynamics-Based Control of Network Systems

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Jordan M. Berg ◽  
D. H. S. Maithripala ◽  
Qing Hui ◽  
Wassim M. Haddad
Keyword(s):  
Thermal Energy ◽  
Thermal Equilibrium ◽  
Laws Of Nature ◽  
Second Law Of Thermodynamics ◽  
Control Algorithms ◽  
Second Law ◽  
Distributed Consensus ◽  
Network Systems ◽  
Consensus Control ◽  
Laws Of Thermodynamics

The zeroth and first laws of thermodynamics define the concepts of thermal equilibrium and thermal energy. The second law of thermodynamics determines whether a particular transfer of thermal energy can occur. Collectively, these fundamental laws of nature imply that a closed collection of thermodynamic subsystems will tend to thermal equilibrium. This paper generalizes the concepts of energy, entropy, and temperature to undirected and directed networks of single integrators, and demonstrates how thermodynamic principles can be applied to the design of distributed consensus control algorithms for networked dynamical systems.

On the kinetic theory of wave propagation in random media

1973 ◽  
Vol 274 (1242) ◽  
pp. 523-549 ◽  
Keyword(s):  
Wave Propagation ◽  
Energy Transfer ◽  
Scattering Theory ◽  
Random Media ◽  
Order Approximation ◽  
Random Medium ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Conservation Of Energy ◽  
Transfer Processes

This paper considers the theory of the multiple scattering of waves in extensive random media. The classical theory of wave propagation in random media is discussed with reference to its practical limitations, and in particular to the inability of the lowest order approximation to the Bethe-Salpeter equation, which describes the propagation of correlations, to account for conservation of energy. An alternative kinetic theory is formulated, based on the theory of energy transfer processes in random media. The proposed theory satisfies conservation of energy and the Second Law of Thermodynamics. It is illustrated by a consideration of three problems each of which is difficult or impossible to treat by classical scattering theory. These involve the transmission of energy through a slab of random medium; the scattering theory of geometrical optics; and scattering by a randomly inhomogeneous half-space.

scholarly journals The second law of thermodynamics as variation on a theme of Carathéodory

2021 ◽  
Vol 477 (2253) ◽  
pp. 20210425
Author(s):  
Joe D. Goddard
Keyword(s):  
Energy Balance ◽  
State Space ◽  
Internal Energy ◽  
Second Law Of Thermodynamics ◽  
Irreversible Processes ◽  
Second Law ◽  
Classic Work ◽  
Axiomatic Foundation ◽  
Convexity Properties ◽  
Definition Of

This paper revisits the second law of thermodynamics via certain modifications of the axiomatic foundation provided by the celebrated 1909 work of Carathéodory. It is shown that his postulate of adiabatic inaccessibility represents one of several constraints on the energy balance that serve to establish the existence of thermostatic entropy as a foliation of state space, with temperature representing a force of constraint. To achieve the thermostatic version of the second law, as embodied in the postulates of Clausius and Gibbs, work principles are proposed to define thermostatic equilibrium and stability in terms of the convexity properties of internal energy, entropy and related thermostatic potentials. Comparisons are made with the classic work of Coleman and Noll on thermostatic equilibrium in simple continua, resulting in a few unresolved differences. Perhaps the most novel aspect of the current work is an extension to irreversible processes by means of a non-equilibrium entropy derived from recoverable work, which generalizes similar ideas in continuum viscoelasticity. This definition of entropy calls for certain revisions of modern theories of continuum thermomechanics by Coleman, Noll and others that are based on a generally inaccessible entropy and undefined temperature.

scholarly journals On the Assumption of the Independence of Thermodynamic Properties on the Gravitational Field

Symmetry ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 930
Author(s):  
Corti
Keyword(s):  
Gravitational Field ◽  
Thermodynamic Properties ◽  
Internal Energy ◽  
Center Of Mass ◽  
Second Law Of Thermodynamics ◽  
Ideal Gas ◽  
Thermodynamic Efficiency ◽  
Second Law ◽  
Cyclic Process ◽  
Carnot Cycle

A reversible cyclic process is analyzed in which the center of mass of an ideal gas is raised in a gravitational field during both an expansion phase and a subsequent contraction phase, with the gas returning to its initial height in a final step. When the properties of the gas are taken as uniform, the thermodynamic efficiency of this cycle is able to exceed that of a corresponding Carnot cycle, which is a violation of the second law of thermodynamics. The source of this discrepancy was previously claimed, when analyzing a similar heating and cooling of a sphere, to be the assumed independence of the internal energy on the gravitational field. However, this violation is only apparent since all of the effects of the gravitational field were not incorporated fully into the thermodynamic analysis of the cycle. When all the influences of the gravitational field are considered, no possible violation of the second law can occur. The evaluation of the entropy changes of the gas throughout the cycle also highlights other key inconsistencies that arise when the full effects of the gravitational field are neglected. As the analysis of the cycle provided here shows, the assumption of the independence of the internal energy, as well as other thermodynamic properties, on the gravitational field strength can still be invoked.

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