Thermodynamic equipartition for increased second law efficiency

Gregory P. Thiel; Ronan K. McGovern; Syed M. Zubair; John H. Lienhard V

doi:10.1016/j.apenergy.2013.12.033

Thermodynamic equipartition for increased second law efficiency

Gregory P. Thiel
, Ronan K. McGovern
, Syed M. Zubair
, John H. Lienhard V^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

44 Scopus citations

Abstract

In this work, a clear distinction is drawn between irreversibility associated with a finite mean driving force in a transport process and irreversibility associated with variance in the spatial and/or temporal distribution of this driving force. The portion of irreversibility associated with driving force variance is quantified via a newly defined dimensionless quantity, the equipartition factor. This equipartition factor, related to the variance in dimensionless driving force throughout the system, is employed to formulate an expression for second law efficiency. Consequently, the equipartition factor may be employed to identify the improvement in efficiency achievable via system redesign for a reduction in driving force variance, while holding fixed the system output for fixed system dimensions in time and space. It is shown that systems with low second law efficiency and low equipartition factor will have the greatest benefit from a redesign to obtain equipartition. The utility of the equipartition factor in identifying situations where efficiency can be increased without requiring a spatial or temporal increase in system size is illustrated through its application to several simple systems.

Original language	English
Pages (from-to)	292-299
Number of pages	8
Journal	Applied Energy
Volume	118
DOIs	https://doi.org/10.1016/j.apenergy.2013.12.033
State	Published - 1 Apr 2014

Bibliographical note

Funding Information:
The authors would like to thank the King Fahd University of Petroleum and Minerals for funding the research reported in this paper through the Center for Clean Water and Clean Energy at MIT and KFUPM under project number R4-CW-08. The first authors are grateful for support via the MIT Martin Fellowship for Sustainability. Ronan K. McGovern is grateful for support via the Fulbright Science and Technology program sponsored by the US Department of State and also for support from the International Desalination Association’s Channabasappa Memorial Scholarship.

Keywords

Energy efficiency
Entropy generation minimization
Equipartition

ASJC Scopus subject areas

Building and Construction
Renewable Energy, Sustainability and the Environment
Mechanical Engineering
General Energy
Management, Monitoring, Policy and Law

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10.1016/j.apenergy.2013.12.033

Cite this

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title = "Thermodynamic equipartition for increased second law efficiency",

abstract = "In this work, a clear distinction is drawn between irreversibility associated with a finite mean driving force in a transport process and irreversibility associated with variance in the spatial and/or temporal distribution of this driving force. The portion of irreversibility associated with driving force variance is quantified via a newly defined dimensionless quantity, the equipartition factor. This equipartition factor, related to the variance in dimensionless driving force throughout the system, is employed to formulate an expression for second law efficiency. Consequently, the equipartition factor may be employed to identify the improvement in efficiency achievable via system redesign for a reduction in driving force variance, while holding fixed the system output for fixed system dimensions in time and space. It is shown that systems with low second law efficiency and low equipartition factor will have the greatest benefit from a redesign to obtain equipartition. The utility of the equipartition factor in identifying situations where efficiency can be increased without requiring a spatial or temporal increase in system size is illustrated through its application to several simple systems.",

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note = "Funding Information: The authors would like to thank the King Fahd University of Petroleum and Minerals for funding the research reported in this paper through the Center for Clean Water and Clean Energy at MIT and KFUPM under project number R4-CW-08. The first authors are grateful for support via the MIT Martin Fellowship for Sustainability. Ronan K. McGovern is grateful for support via the Fulbright Science and Technology program sponsored by the US Department of State and also for support from the International Desalination Association{\textquoteright}s Channabasappa Memorial Scholarship.",

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N1 - Funding Information: The authors would like to thank the King Fahd University of Petroleum and Minerals for funding the research reported in this paper through the Center for Clean Water and Clean Energy at MIT and KFUPM under project number R4-CW-08. The first authors are grateful for support via the MIT Martin Fellowship for Sustainability. Ronan K. McGovern is grateful for support via the Fulbright Science and Technology program sponsored by the US Department of State and also for support from the International Desalination Association’s Channabasappa Memorial Scholarship.

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N2 - In this work, a clear distinction is drawn between irreversibility associated with a finite mean driving force in a transport process and irreversibility associated with variance in the spatial and/or temporal distribution of this driving force. The portion of irreversibility associated with driving force variance is quantified via a newly defined dimensionless quantity, the equipartition factor. This equipartition factor, related to the variance in dimensionless driving force throughout the system, is employed to formulate an expression for second law efficiency. Consequently, the equipartition factor may be employed to identify the improvement in efficiency achievable via system redesign for a reduction in driving force variance, while holding fixed the system output for fixed system dimensions in time and space. It is shown that systems with low second law efficiency and low equipartition factor will have the greatest benefit from a redesign to obtain equipartition. The utility of the equipartition factor in identifying situations where efficiency can be increased without requiring a spatial or temporal increase in system size is illustrated through its application to several simple systems.

AB - In this work, a clear distinction is drawn between irreversibility associated with a finite mean driving force in a transport process and irreversibility associated with variance in the spatial and/or temporal distribution of this driving force. The portion of irreversibility associated with driving force variance is quantified via a newly defined dimensionless quantity, the equipartition factor. This equipartition factor, related to the variance in dimensionless driving force throughout the system, is employed to formulate an expression for second law efficiency. Consequently, the equipartition factor may be employed to identify the improvement in efficiency achievable via system redesign for a reduction in driving force variance, while holding fixed the system output for fixed system dimensions in time and space. It is shown that systems with low second law efficiency and low equipartition factor will have the greatest benefit from a redesign to obtain equipartition. The utility of the equipartition factor in identifying situations where efficiency can be increased without requiring a spatial or temporal increase in system size is illustrated through its application to several simple systems.

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ER -

Thermodynamic equipartition for increased second law efficiency

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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