Boundary layer analysis and heat transfer of a nanofluid

MacDevette, Michelle; Myers, T.G.; Wetton, Brian

doi:10.1007/s10404-013-1319-1

Cited by 28 publications

(20 citation statements)

References 37 publications

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“… is the heat flux through the solid-fluid boundary and T is the temperature difference between the boundary fluid near the solid surface and the far field fluid. The interpretation of this T varies [33], but commonly it is assumed that the temperature near the solid surface is the same as the temperature of the surface [34]. The temperature of the far field fluid is the average temperature between the inlet and outlet tube [33].…”

Section: Heat Transfer Measurementmentioning

confidence: 99%

“…The interpretation of this T varies [33], but commonly it is assumed that the temperature near the solid surface is the same as the temperature of the surface [34]. The temperature of the far field fluid is the average temperature between the inlet and outlet tube [33]. This assumption is used in this study to give T = Ts,in -Tb,m and then the heat transfer coefficient is: The Nusselt number is defined as [35]: k hD Nu= (9) where D is the diameter of the test section and k is the thermal conductivity of the fluid.…”

Section: Heat Transfer Measurementmentioning

confidence: 99%

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A practical evaluation of the performance of Al2O3-water, TiO2-water and CuO-water nanofluids for convective cooling

Alkasmoul

Al-Asadi

Myers

et al. 2018

International Journal of Heat and Mass Transfer

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The convective heat transfer, pressure drop and required pumping power for the turbulent flow of Al2O3water, TiO2-water and CuO-water nanofluids in a heated, horizontal tube with a constant heat flux are investigated experimentally. Results show that presenting nanofluid performance by the popular approach of plotting Nusselt number versus Reynolds number is misleading and can create the impression that nanofluids enhance heat transfer efficiency. This approach is shown to be problematic since both Nusselt number and Reynolds number are functions of nanofluid concentration. When results are presented in terms of actual heat transfer coefficient or tube temperature versus flow rate or pressure drop, adding nanoparticles to the water is shown to degrade heat transfer for all the nanofluids and under all conditions considered. Replacing water with nanofluid at the same flow rate reduces the convective heat transfer rate by reducing the operating Reynolds number of the system. Achieving a target temperature under a given heat load is shown to require significantly higher flow rates and pumping power when using nanofluids compared to water, and hence none of the nanofluids are found to offer any practical benefits. Declarations of interest: noneNomenclature A Inside surface area of the test section tube (m 2 ) Cp Specific heat (J/kg.K) Pr Prandtl number V Average fluid velocity (m/s) Greek letters  Volume fraction of nanofluids Ratio between the nanolayer thickness surrounding the nanoparticle and the nanoparticle radius Kinematic viscosity (m 2 /s) Density (kg/m 3 ) µ Dynamic viscosity (Pa s)

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Section: Heat Transfer Measurementmentioning

confidence: 99%

Section: Heat Transfer Measurementmentioning

confidence: 99%

A practical evaluation of the performance of Al2O3-water, TiO2-water and CuO-water nanofluids for convective cooling

Alkasmoul

Al-Asadi

Myers

et al. 2018

International Journal of Heat and Mass Transfer

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“…Since D B and D T involve temperature and volume fraction, we apply the notation of [34] so that the governing equations are formulated in terms of the 'diffusion parameters' C B = D B /T and C T = D T /φ. This notation permits the variation of φ, T to be clearly identified in the governing equations.…”

Section: Mathematical Modelmentioning

confidence: 99%

“…This notation permits the variation of φ, T to be clearly identified in the governing equations. Hence, according to [34], the governing equations to describe the flow of a heated, Newtonian nanofluid are…”

Section: Mathematical Modelmentioning

confidence: 99%

Does mathematics contribute to the nanofluid debate?

Myers

Ribera

Cregan

2017

International Journal of Heat and Mass Transfer

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Recent experimental evidence has clearly demonstrated that nanofluids do not provide the greatly enhanced heat transfer predicted in the past. Despite seemingly conclusive proof there is still a great deal of current mathematical research asserting the opposite result. In this paper we scrutinise the mathematical work and demonstrate that the disagreement can be traced to a number of issues. These include the incorrect formulation of the governing equations; the use of parameter values orders of magnitude different to the true values (some requiring nanoparticle volume fractions greater than unity and nanoparticles smaller than atoms); model choices that are based on permitting a reduction using similarity variables as opposed to representing an actual physical situation; presentation of results using different scalings for each fluid.

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“…For example, contradicting numerous experimental studies such as [11,12,15], the international benchmark study of Buongiorno et al [7] suggested that there was no anomalous enhancement of thermal conductivity in the fluid. Furthermore, the analysis of MacDevette et al [19] showed that the model derived in [6], and used by many researchers to show increased heat transfer coefficient, in fact leads to the opposite result. They go on to show that many previous erroneous results stem from 'ad hoc' assumptions or incorrect parameter values.…”

Section: Introductionmentioning

confidence: 97%