Entropy Generation Due to Viscous Dissipation around a Wells Turbine Blade: A Preliminary Numerical Study

Shehata, Ahmed S.; Saqr, Khalid M.; Shehadeh, Mohamed; Xiao, Qing; Day, Sandy

doi:10.1016/j.egypro.2014.06.099

Cited by 25 publications

(15 citation statements)

References 12 publications

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“…[51]. The best result for S-A, k À u SST and the Realizable k À ε model but the latter one required less time [52]. As For the near-wall treatment in both K-epsilon and S-A models have used the log law of the wall but for k-omega models have used y plus less than one.…”

Section: Numerical Model Validationmentioning

confidence: 97%

Performance analysis of wells turbine blades using the entropy generation minimization method

et al. 2016

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Wells turbine concept depends on utilizing the oscillating air column generated over marine waves to drive a turbine. As a matter of fact, previous researches on the performance analysis of such turbine were based on the first law of thermodynamics only. Nonetheless, the actual useful energy loss cannot be completely justified by the first law because it does not distinguish between the quantity and the quality of energy. Therefore, the present work investigates the second law efficiency and entropy generation characteristics around different blades that are used in Wells turbine under oscillating flow conditions. The work is performed by using time-dependent CFD models of different NACA airfoils under sinusoidal flow boundary conditions. Numerical investigations are carried out for the incompressible viscous flow around the blades to obtain the entropy generation due to viscous dissipation. It is found that the value of second law efficiency of the NACA0015 airfoil blade is higher by approximately 1.5% than the second law efficiency of the NACA0012, NACA0020 and NACA0021 airfoils. Furthermore, it is found that the angle of attack radically affects the second law efficiency and such effect is quantified for NACA0015 for angle of attack ranging from -15° to 25°

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Section: Numerical Model Validationmentioning

confidence: 97%

Performance analysis of wells turbine blades using the entropy generation minimization method

et al. 2016

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“…The entropy generation, due to viscous dissipation, around W-T has been recently examined by the authors in [108,109]. NACA0015 gives a less global entropy generation rate and a higher efficiency rate compared with other airfoils.…”

Section: Flow Through W-tmentioning

confidence: 99%

Wells turbine for wave energy conversion: a review

Shehata

Xiao

Saqr

et al. 2016

Int. J. Energy Res.

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Summary In the past 20 years, the use of wave energy systems has significantly increased, generally depending on the oscillating water column concept. Wells turbine is one of the most efficient oscillating water column technologies. This article provides an updated and a comprehensive account of the state‐of‐the‐art research on Wells turbine. Hence, it draws a roadmap for the contemporary challenges, which may hinder future reliance on such systems in the renewable energy sector. In particular, the article is concerned with the research directions and methodologies, which aim at enhancing the performance and efficiency of Wells turbine. The article also provides a thorough discussion of the use of CFD for performance modeling and design optimization of Wells turbine. It is found that a numerical model using the CFD code can be employed successfully to calculate the performance characteristics of W‐T as well as other experimental and analytical methods. The increase of research papers about CFD, especially in the last 5 years, indicates that there is a trend that considerably depends on the CFD method. Copyright © 2016 John Wiley & Sons, Ltd.

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“…It was noted that at low mass flow rates, the EGR due to HT was dominant; however, the EGR due to fluid friction becomes comparable to the EGR due to HT at high mass flow rates. Some researchers [12][13][14][15][16] worked on the EGR considering the effects of viscous dissipation (VD) in the flow field. Hayat et al [13] investigated the combined effects of VD and Joule heating in flow by rotating disks of variable thickness.…”

Section: Introductionmentioning

confidence: 99%

Effect of Thermophysical Property Variation on Entropy Generation towards Micro-Scale

Chauhan

Kumar

et al. 2020

Journal of Non-Equilibrium Thermodynamics

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In this work, the effect of temperature-dependent thermal conductivity (k(T)) and viscosity (\mu (T)) variation on entropy generation in circular channels with an approach from macro- to micro-scale is numerically investigated. Thermally as well as hydrodynamically fully developed flow of water through the fixed length channels with constant total heat flow rate and total mass flow rate is considered. The effects of k(T) variation and \mu (T) variation on entropy generation are analyzed individually as well as collectively. It is observed that in the case of Constant Property Solutions (CPS) {S_{\mathit{gen},\mathit{tot}}} is maximum at the macro-level; however, in the case of combined k(T) and \mu (T) variations it is maximum at the micro-level. The Bejan number (\mathit{Be}) and irreversibility distribution ratio (φ) are also calculated for asserting the dominance of frictional irreversibility and conduction heat transfer irreversibility. Additionally, the optimum diameter ({D^{\ast }}) corresponding to the optimum number of channels is calculated at minimum total entropy generation. It is observed that {D^{\ast }} is minimum for k(T) variation followed by CPS, \mu (T) variation, and combined k(T) and \mu (T) variations.

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Entropy Generation Due to Viscous Dissipation around a Wells Turbine Blade: A Preliminary Numerical Study

Cited by 25 publications

References 12 publications

Performance analysis of wells turbine blades using the entropy generation minimization method

Performance analysis of wells turbine blades using the entropy generation minimization method

Wells turbine for wave energy conversion: a review

Effect of Thermophysical Property Variation on Entropy Generation towards Micro-Scale

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