Local entropy production in turbulent shear flows: a high-Reynolds number model with wall functions

Kock, Fabian; Herwig, Heinz

doi:10.1016/j.ijheatmasstransfer.2003.11.025

Cited by 508 publications

(213 citation statements)

References 15 publications

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“…It is linked to the amount of available work and can be used to evaluate sources of irreversibilities [7]. In the case of single phase, non-reacting and single component fluid flow with Fourier heat conduction, the second law of thermodynamics can be expressed in the form of the local imbalance of entropy given as [36]:…”

Section: Entropy Principle and Irreversibilitymentioning

confidence: 99%

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Thermal Transport and Entropy Production Mechanisms in a Turbulent Round Jet at Supercritical Thermodynamic Conditions

Ries

Janicka

Sadiki

2017

Entropy

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Abstract:In the present paper, thermal transport and entropy production mechanisms in a turbulent round jet of compressed nitrogen at supercritical thermodynamic conditions are investigated using a direct numerical simulation. First, thermal transport and its contribution to the mixture formation along with the anisotropy of heat fluxes and temperature scales are examined. Secondly, the entropy production rates during thermofluid processes evolving in the supercritical flow are investigated in order to identify the causes of irreversibilities and to display advantageous locations of handling along with the process regimes favorable to mixing. Thereby, it turned out that (1) the jet disintegration process consists of four main stages under supercritical conditions (potential core, separation, pseudo-boiling, turbulent mixing), (2) causes of irreversibilities are primarily due to heat transport and thermodynamic effects rather than turbulence dynamics and (3) heat fluxes and temperature scales appear anisotropic even at the smallest scales, which implies that anisotropic thermal diffusivity models might be appropriate in the context of both Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) approaches while numerically modeling supercritical fluid flows.

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Section: Entropy Principle and Irreversibilitymentioning

confidence: 99%

“…Focusing on Navier-Stokes-Fourier fluid flow, the entropy production rate by viscous dissipation reads [6,36]:…”

Section: Entropy Principle and Irreversibilitymentioning

confidence: 99%

Thermal Transport and Entropy Production Mechanisms in a Turbulent Round Jet at Supercritical Thermodynamic Conditions

Ries

Janicka

Sadiki

2017

Entropy

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“…Given the non-uniform distribution of the heat flux on the receiver's absorber tube, the entropy generation has been determined numerically and locally using the methodology proposed by Kock and Herwig [45,46]. The entropy generation rates are determined from the known velocity and temperature fields obtained from the computational fluid dynamics analysis.…”

Section: Determination Of Local Entropy Generation Ratesmentioning

confidence: 99%

“…The entropy generation due to the fluid friction irreversibility (S ''' gen ) F is given by [45,46]  …”

Section: Determination Of Local Entropy Generation Ratesmentioning

confidence: 99%

Thermal performance and entropy generation analysis of a high concentration ratio parabolic trough solar collector with Cu-Therminol®VP-1 nanofluid

Mwesigye

Huan

Meyer

2016

Energy Conversion and Management

201

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This paper presents results of a numerical study on the thermal and thermodynamic performance of a high concentration ratio parabolic trough solar collector using Cu- Above a certain Reynolds number, further increase in the Reynolds numbers makes the entropy generation higher than that of a receiver with only the base fluid. Key wordsConcentration ratio, entropy generation, nanofluid, parabolic trough receiver, thermal efficiency. †

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“…These entropy generation rates were obtained locally from temperature and velocity fields obtained from the numerical analysis. The entropy generation rates were determined according to the general equations presented by Herwig, 2004, Kock andHerwig, 2005).…”

Section: Entropy Generation Analysismentioning

confidence: 99%

Influence of optical errors on the thermal and thermodynamic performance of a solar parabolic trough receiver

et al. 2016

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HIGHLIGHTS• Effect of optical errors on performance of a parabolic trough receiver is presented.• Actual heat flux profiles were obtained using Monte Carlo ray tracing and presented.• Thermal and thermodynamic analysis of the receiver is determined numerically.• Effect of optical errors on heat flux and temperature distribution is investigated.• Influence of optical errors on receiver entropy generation rates is presented. ABSTRACTThis paper presents results of an investigation covering the influence of optical errors on the thermal and thermodynamic performance of a solar parabolic trough system. The optical performance was evaluated by using Monte Carlo ray tracing for slope errors and specularity For the range of parameters considered, the intercept factor reduces by up to 21% while the overall thermal efficiency reduces by up to 17% as optical errors increase. Receiver thermodynamic performance is shown to deteriorate as slope errors increase.

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Local entropy production in turbulent shear flows: a high-Reynolds number model with wall functions

Cited by 508 publications

References 15 publications

Thermal Transport and Entropy Production Mechanisms in a Turbulent Round Jet at Supercritical Thermodynamic Conditions

Thermal Transport and Entropy Production Mechanisms in a Turbulent Round Jet at Supercritical Thermodynamic Conditions

Thermal performance and entropy generation analysis of a high concentration ratio parabolic trough solar collector with Cu-Therminol®VP-1 nanofluid

Influence of optical errors on the thermal and thermodynamic performance of a solar parabolic trough receiver

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