A Review of the System-Intrinsic Nonequilibrium Thermodynamics in Extended Space (MNEQT) with Applications

The review deals with a <i>novel approach</i> (MNEQT) to nonequilibrium thermodynamics (NEQT) that is based on the concept of internal equilibrium (IEQ) in an enlarged state space <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline&quo...

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Main Author: Purushottam D. Gujrati
Format: Article
Language:English
Published: MDPI AG 2021-11-01
Series:Entropy
Subjects:
Online Access:https://www.mdpi.com/1099-4300/23/12/1584
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author Purushottam D. Gujrati
author_facet Purushottam D. Gujrati
author_sort Purushottam D. Gujrati
collection DOAJ
description The review deals with a <i>novel approach</i> (MNEQT) to nonequilibrium thermodynamics (NEQT) that is based on the concept of internal equilibrium (IEQ) in an enlarged state space <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi mathvariant="fraktur">S</mi><mi mathvariant="bold">Z</mi></msub></semantics></math></inline-formula> involving <i>internal variables as additional state variables</i>. The IEQ macrostates are unique in <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi mathvariant="fraktur">S</mi><mi mathvariant="bold">Z</mi></msub></semantics></math></inline-formula> and have no memory just as EQ macrostates are in the EQ state space <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi mathvariant="fraktur">S</mi><mi mathvariant="bold">X</mi></msub><mo>⊂</mo><msub><mi mathvariant="fraktur">S</mi><mi mathvariant="bold">Z</mi></msub></mrow></semantics></math></inline-formula>. The approach provides a clear strategy to identify the internal variables for any model through several examples. The MNEQT deals directly with system-intrinsic quantities, which are very useful as they fully describe irreversibility. Because of this, MNEQT solves a long-standing problem in NEQT of identifying a unique global temperature <i>T</i> of a system, <i>thus fulfilling Planck’s dream of a global temperature for any system</i>, even if it is not uniform such as when it is driven between two heat baths; <i>T</i> has the conventional interpretation of satisfying the Clausius statement that the <i>exchange macroheat</i><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>d</mi><mi mathvariant="normal">e</mi></msub><mi>Q</mi></mrow></semantics></math></inline-formula><i>flows from hot to cold</i>, and other sensible criteria expected of a temperature. The concept of the generalized macroheat <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>d</mi><mi>Q</mi><mo>=</mo><msub><mi>d</mi><mi mathvariant="normal">e</mi></msub><mi>Q</mi><mo>+</mo><msub><mi>d</mi><mi mathvariant="normal">i</mi></msub><mi>Q</mi></mrow></semantics></math></inline-formula> converts the Clausius inequality <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>d</mi><mi>S</mi><mo>≥</mo><msub><mi>d</mi><mi mathvariant="normal">e</mi></msub><mi>Q</mi><mo>/</mo><msub><mi>T</mi><mn>0</mn></msub></mrow></semantics></math></inline-formula> for a system in a medium at temperature <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>T</mi><mn>0</mn></msub></semantics></math></inline-formula> into the <i>Clausius equality</i><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>d</mi><mi>S</mi><mo>≡</mo><mi>d</mi><mi>Q</mi><mo>/</mo><mi>T</mi></mrow></semantics></math></inline-formula>, which also covers macrostates with memory, and follows from the extensivity property. The equality also holds for a NEQ isolated system. The novel approach is extremely useful as it also works when no internal state variables are used to study nonunique macrostates in the EQ state space <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi mathvariant="fraktur">S</mi><mi mathvariant="bold">X</mi></msub></semantics></math></inline-formula> at the expense of explicit time dependence in the entropy that gives rise to memory effects. To show the usefulness of the novel approach, we give several examples such as irreversible Carnot cycle, friction and Brownian motion, the free expansion, etc.
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spelling doaj.art-6b35c194afc8421ebc8c6fb6f18c43492023-11-23T08:10:15ZengMDPI AGEntropy1099-43002021-11-012312158410.3390/e23121584A Review of the System-Intrinsic Nonequilibrium Thermodynamics in Extended Space (MNEQT) with ApplicationsPurushottam D. Gujrati0Department of Physics, The University of Akron, Akron, OH 44325, USAThe review deals with a <i>novel approach</i> (MNEQT) to nonequilibrium thermodynamics (NEQT) that is based on the concept of internal equilibrium (IEQ) in an enlarged state space <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi mathvariant="fraktur">S</mi><mi mathvariant="bold">Z</mi></msub></semantics></math></inline-formula> involving <i>internal variables as additional state variables</i>. The IEQ macrostates are unique in <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi mathvariant="fraktur">S</mi><mi mathvariant="bold">Z</mi></msub></semantics></math></inline-formula> and have no memory just as EQ macrostates are in the EQ state space <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi mathvariant="fraktur">S</mi><mi mathvariant="bold">X</mi></msub><mo>⊂</mo><msub><mi mathvariant="fraktur">S</mi><mi mathvariant="bold">Z</mi></msub></mrow></semantics></math></inline-formula>. The approach provides a clear strategy to identify the internal variables for any model through several examples. The MNEQT deals directly with system-intrinsic quantities, which are very useful as they fully describe irreversibility. Because of this, MNEQT solves a long-standing problem in NEQT of identifying a unique global temperature <i>T</i> of a system, <i>thus fulfilling Planck’s dream of a global temperature for any system</i>, even if it is not uniform such as when it is driven between two heat baths; <i>T</i> has the conventional interpretation of satisfying the Clausius statement that the <i>exchange macroheat</i><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>d</mi><mi mathvariant="normal">e</mi></msub><mi>Q</mi></mrow></semantics></math></inline-formula><i>flows from hot to cold</i>, and other sensible criteria expected of a temperature. The concept of the generalized macroheat <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>d</mi><mi>Q</mi><mo>=</mo><msub><mi>d</mi><mi mathvariant="normal">e</mi></msub><mi>Q</mi><mo>+</mo><msub><mi>d</mi><mi mathvariant="normal">i</mi></msub><mi>Q</mi></mrow></semantics></math></inline-formula> converts the Clausius inequality <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>d</mi><mi>S</mi><mo>≥</mo><msub><mi>d</mi><mi mathvariant="normal">e</mi></msub><mi>Q</mi><mo>/</mo><msub><mi>T</mi><mn>0</mn></msub></mrow></semantics></math></inline-formula> for a system in a medium at temperature <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>T</mi><mn>0</mn></msub></semantics></math></inline-formula> into the <i>Clausius equality</i><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>d</mi><mi>S</mi><mo>≡</mo><mi>d</mi><mi>Q</mi><mo>/</mo><mi>T</mi></mrow></semantics></math></inline-formula>, which also covers macrostates with memory, and follows from the extensivity property. The equality also holds for a NEQ isolated system. The novel approach is extremely useful as it also works when no internal state variables are used to study nonunique macrostates in the EQ state space <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi mathvariant="fraktur">S</mi><mi mathvariant="bold">X</mi></msub></semantics></math></inline-formula> at the expense of explicit time dependence in the entropy that gives rise to memory effects. To show the usefulness of the novel approach, we give several examples such as irreversible Carnot cycle, friction and Brownian motion, the free expansion, etc.https://www.mdpi.com/1099-4300/23/12/1584unique-nonunique macrostatesystem-intrinsic and medium-intrinsic propertiesinternal equilibriumextended state spaceentropy with and without memoryentropy generation
spellingShingle Purushottam D. Gujrati
A Review of the System-Intrinsic Nonequilibrium Thermodynamics in Extended Space (MNEQT) with Applications
Entropy
unique-nonunique macrostate
system-intrinsic and medium-intrinsic properties
internal equilibrium
extended state space
entropy with and without memory
entropy generation
title A Review of the System-Intrinsic Nonequilibrium Thermodynamics in Extended Space (MNEQT) with Applications
title_full A Review of the System-Intrinsic Nonequilibrium Thermodynamics in Extended Space (MNEQT) with Applications
title_fullStr A Review of the System-Intrinsic Nonequilibrium Thermodynamics in Extended Space (MNEQT) with Applications
title_full_unstemmed A Review of the System-Intrinsic Nonequilibrium Thermodynamics in Extended Space (MNEQT) with Applications
title_short A Review of the System-Intrinsic Nonequilibrium Thermodynamics in Extended Space (MNEQT) with Applications
title_sort review of the system intrinsic nonequilibrium thermodynamics in extended space mneqt with applications
topic unique-nonunique macrostate
system-intrinsic and medium-intrinsic properties
internal equilibrium
extended state space
entropy with and without memory
entropy generation
url https://www.mdpi.com/1099-4300/23/12/1584
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