Theoretical study of nanofluids behavior at critical Rayleigh numbers

Esfahani, Javad Abolfazli; Feshalami, Behzad Forouzi

doi:10.1007/s10973-018-7582-3

Cited by 7 publications

(7 citation statements)

References 105 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The theoretical enhancement factor, which takes into consideration volume fraction alone is found to decrease with an increase in volume fraction. Some other models as proposed by Kim, Sharma, Abouali, Esfahani, and so forth that project the correlation between

italicf

and nanoparticle volume fraction also conclude that the enhancement factor reduces with volume fraction for different nanofluids, including water–Al 2 O 3 nanofluids, as shown in Table 4 42 …”

Section: Experimental Analysismentioning

confidence: 82%

“…This can be expressed as

R a_{nf} = f R a_{f},

where

f

is the enhancement factor 41,42 given by

f = β_{nf}^{*} ρ *_{nf}^{2} C_{p ‐ nf}^{*} μ *_{nf}^{‐ 1} \times k *_{nf}^{‐ 1},

expressed in terms of the ratio of each property of nanofluid to that of the pure base fluid.…”

Section: Impact Of Rayleigh–bénard Convection On Heat Transfer Effect...mentioning

confidence: 99%

“…The critical Rayleigh number of the nanofluid

{Ra}_{nf}

increases as the volume fraction of nanoparticles in the base fluid is increased, which causes a delay in the onset of natural convection. Depending on the relative values of

italicRa

, the effectiveness of nanofluid varies as shown in Table 2 35,42,51 …”

Section: Impact Of Rayleigh–bénard Convection On Heat Transfer Effect...mentioning

confidence: 99%

See 2 more Smart Citations

Impact of volume fraction and fluid layer thickness on heat transfer effectiveness of water‐based nanofluids

S¹,

Namboothiri

2021

Heat Trans

View full text Add to dashboard Cite

The heat transfer effectiveness of nanofluids is adversely affected by the delay in convection onset. The lesser effectiveness, when compared to that of base fluid, is observed in a range of nanofluid layer thickness. The heat transfer coefficient of water-Al 2 O 3 nanofluid can be enhanced by sustaining the equilibrium between Rayleigh number, temperature, particle volume fraction, and enclosure aspect ratio.

show abstract

italicf

and nanoparticle volume fraction also conclude that the enhancement factor reduces with volume fraction for different nanofluids, including water–Al 2 O 3 nanofluids, as shown in Table 4 42 …”

Section: Experimental Analysismentioning

confidence: 82%

“…This can be expressed as

R a_{nf} = f R a_{f},

where

f

is the enhancement factor 41,42 given by

f = β_{nf}^{*} ρ *_{nf}^{2} C_{p ‐ nf}^{*} μ *_{nf}^{‐ 1} \times k *_{nf}^{‐ 1},

expressed in terms of the ratio of each property of nanofluid to that of the pure base fluid.…”

Section: Impact Of Rayleigh–bénard Convection On Heat Transfer Effect...mentioning

confidence: 99%

“…The critical Rayleigh number of the nanofluid

{Ra}_{nf}

increases as the volume fraction of nanoparticles in the base fluid is increased, which causes a delay in the onset of natural convection. Depending on the relative values of

italicRa

, the effectiveness of nanofluid varies as shown in Table 2 35,42,51 …”

Section: Impact Of Rayleigh–bénard Convection On Heat Transfer Effect...mentioning

confidence: 99%

See 1 more Smart Citation

Impact of volume fraction and fluid layer thickness on heat transfer effectiveness of water‐based nanofluids

S¹,

Namboothiri

2021

Heat Trans

View full text Add to dashboard Cite

show abstract

“…Dhiman and Sharma 14 have investigated the influence of viscosity, which varies with respect to temperature for micropolar fluid in the case of thermal convection, and reported that viscosity influences the stability of the system on the onset of convection. Esfahani and Feshalami 15 studied the RB problem for nanofluids on natural convection. They have considered a few enhancement factors, which advance the onset of natural convection.…”

Section: Introductionmentioning

confidence: 99%

Rayleigh–Bénard and Bénard–Marangoni magnetoconvection in variable viscosity finitely conducting liquids

2021

View full text Add to dashboard Cite

The thermorheological effect on magneto‐Bénard‐convection is studied numerically in fluids with finite electrical conductivity. A nonlinear thermorheological equation is considered in the problem. The results are compared with the classical approach of constant viscosity, which depicts the fact that the effect of increasing the strength of the magnetic field is to delay the onset of convection. The magnetic field is shown to have a rheostatic influence on convective instabilities. The results obtained by the study have possible applications in the field of astrophysics, sunspots, and in space applications under microgravity.

show abstract

“…The effectiveness of nanofluids in heat transfer decreases as the critical Rayleigh number of the base fluid is exceeded . The results of the research conducted on SiO 2 ‐water nanofluid by Esfahani and Feshalami indicate that the Nusselt number and convective heat transfer ratio are reduced for SiO 2 ‐water nanofluid for almost all volume fractions and as a result using SiO 2 as nanoparticle into water (the base fluid) is not desired for natural convection in Rayleigh‐Bénard problem.…”

Section: Introductionmentioning

confidence: 99%

Optimum fluid layer thickness for heat transfer effectiveness using water‐based nanofluids—A numerical estimation

Krishnan¹,

Namboothiri

Mathew³

2019

Heat Trans. Asian Res.

View full text Add to dashboard Cite

Nanofluids are considered to be the novel method for heat transfer in heat pipes and heat exchangers. But its application in microlevel cooling systems is still limited because of the paradox that once convection onsets in the base fluid, the effectiveness of nanofluid as a heat transfer medium will be reduced. The onset of convection in the nanofluid occurs only after its onset in the base fluid which is mostly water. Hence, it is vital to estimate the fluid layer thickness of the base fluid at which convection will just onset. The problem is analyzed using the concept of the critical Rayleigh number. The study of velocity and temperature profiles in the fluid gap also gives an indication of convection in the fluid gap. K E Y W O R D SHeat transfer effectiveness of nanofluids, Rayleigh-Benard convection, Rayleigh number, thermal stability

show abstract

Theoretical study of nanofluids behavior at critical Rayleigh numbers

Cited by 7 publications

References 105 publications

Impact of volume fraction and fluid layer thickness on heat transfer effectiveness of water‐based nanofluids

Impact of volume fraction and fluid layer thickness on heat transfer effectiveness of water‐based nanofluids

Rayleigh–Bénard and Bénard–Marangoni magnetoconvection in variable viscosity finitely conducting liquids

Optimum fluid layer thickness for heat transfer effectiveness using water‐based nanofluids—A numerical estimation

Contact Info

Product

Resources

About