Experimental investigation of thermophysical properties, entropy generation and convective heat transfer for a nitrogen-doped graphene nanofluid in a laminar flow regime

2016 ◽  
Vol 27 (2) ◽  
pp. 717-727 ◽  
Author(s):  
Mohammad Mehrali ◽  
Emad Sadeghinezhad ◽  
Marc A. Rosen ◽  
Amir Reza Akhiani ◽  
Sara Tahan Latibari ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Laminar Flow ◽  
Convective Heat Transfer ◽  
Flow Regime ◽  
Convective Heat ◽  
Thermophysical Properties ◽  
Nitrogen Doped ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

Flow and Convective Heat Transfer Characteristics of Nanofluids With Various Shapes of Alumina Nanoparticles

2009 ◽  
Author(s):  
Kyo Sik Hwang ◽  
Hyo Jun Ha ◽  
Seung Hyun Lee ◽  
Hyun Jin Kim ◽  
Seok Pil Jang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Convective Heat Transfer ◽  
Flow Regime ◽  
Convective Heat ◽  
Circular Tube ◽  
Al2o3 Nanoparticles ◽  
Heat Transfer Characteristics ◽  
Laminar Flow Regime ◽  
Transfer Characteristics

This paper is to investigate flow and convective heat transfer characteristics of nanofluids with various shapes of Al2O3 nanoparticles flowing through a uniformly heated circular tube under fully developed laminar flow regime. For the purpose, Al2O3 nanofluids of 0.3 Vol.% with sphere, rod, platelet, blade and brick shapes are manufactured by a two-step method. Zeta potential as well as TEM image is experimentally obtained to examine suspension and dispersion characteristics of Al2O3 nanofluids with various shapes. To investigate flow characteristics, the pressure drop of Al2O3 nanofluids with various shapes are measured. In order to investigate convective heat transfer characteristics, the effective thermal conductivities of Al2O3 nanofluids with various shapes, the temperature distribution at the tube surface and the mean temperature of nanofluids at the inlet are measured, respectively. Based on the experimental results, the convective heat transfer coefficient of Al2O3 nanofluids with various shapes is compared with that of pure water and the thermal conductivity of Al2O3 nanofluids with various shapes. Thus, the effect of nanoparticles shape on the flow and convective heat transfer characteristics flowing through a uniformly heated circular tube under fully developed laminar flow regime is experimentally investigated.

Free Convective Heat Transfer in a Liquid-Filled Vertical Annulus

1985 ◽  
Vol 107 (3) ◽  
pp. 596-602 ◽  
Author(s):  
V. Prasad ◽  
F. A. Kulacki
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Laminar Flow ◽  
Prandtl Number ◽  
Convective Heat Transfer ◽  
Flow Regime ◽  
Convective Heat ◽  
Radius Ratio ◽  
Number Range ◽  
Vertical Annulus

An experimental study of convective heat transfer in liquid-filled vertical annulus of radius ratio κ = 5.338 has been conducted for the height-to-gap width ratio A = 0.5, 1, and 1.5. By using water, heptane, and ethylene glycol as the test fluids, a Rayleigh number range of 8 × 106 < Ra < 3 × 1010, and a Prandtl number range of 4 < Pr < 196 have been covered. Curvature effects on the temperature field are significant and result in a lower effective sink temperature for the boundary layer on the isothermally heated inner wall. The Nusselt number Nu thus increases with radius ratio κ. However, the slope of ln (Nu) versus ln (κ) curve is not a constant, and decreases with an increase in κ. The effect of Prandtl number is weak. In the laminar flow regime, the Nusselt number is weakly dependent on the aspect ratio when Nu and Ra are considered in terms of the annulus height L. The start of laminar flow regime is delayed with an increase in radius ratio. For A = 0.5, κ = 5.338, the critical Grashof number is GrL = 7 × 104, which decreases with an increase in A. Turbulence is initiated when the local Grashof number Grx ≃ 4 × 109.

Forced Convective Heat Transfer of Nanofluids in Microchannels

2006 ◽  
Author(s):  
Jung-Yeul Jung ◽  
Hoo-Suk Oh ◽  
Ho-Young Kwak
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Laminar Flow ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Flow Regime ◽  
Convective Heat ◽  
Volume Fraction ◽  
Convective Heat Transfer Coefficient ◽  
Laminar Flow Regime

Convective heat transfer coefficient and friction factor of a nanofluid in rectangular microchannel were measured. An integrated microsystem consisting of a single microchannel on one side and two localized heaters and five polysilicon temperature sensors along the channel on the other side were fabricated. Aluminum dioxide (Al2O3) nanofluids with various particle volume fractions were used in experiment to investigate the effect of the volume fraction of the nanoparticles to the convective heat transfer and fluid flow in microchannels. The convective heat transfer coefficient of the Al2O3 nanofluid in laminar flow regime was measured to be increased up to 15% compared to the distilled water at a volume fraction of 1.8 volume percent without major friction loss. The Nusselt number measured increases with increasing the Reynolds number in laminar flow regime. A new type of convective heat transfer correlation was proposed to correlate experimental data of heat transfer coefficient for nanofluids in microchannels.

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