Heat transfer enhancement using Al2O3 - H2O nanofluid for an electronic liquid cooling system
Université de Sherbrooke, Шербрук, Quebec, Canada Applied Thermal Engineering
(Impact Factor: 2.74).
06/2007; 27(8-9):1501-1506. DOI: 10.1016/j.applthermaleng.2006.09.028
We have experimentally investigated the behaviour and heat transfer enhancement of a particular nanofluid, Al2O3 nanoparticle–water mixture, flowing inside a closed system that is destined for cooling of microprocessors or other electronic components. Experimental data, obtained for turbulent flow regime, have clearly shown that the inclusion of nanoparticles into distilled water has produced a considerable enhancement of the cooling block convective heat transfer coefficient. For a particular nanofluid with 6.8% particle volume concentration, heat transfer coefficient has been found to increase as much as 40% compared to that of the base fluid. It has also been found that an increase of particle concentration has produced a clear decrease of the heated component temperature. Experimental data have clearly shown that nanofluid with 36 nm particle diameter provides higher heat transfer coefficients than the ones of nanofluid with 47 nm particle size.
- "For the nanofluids containing spherical particles, different results on the relationship between the Nusselt number and particle volume concentration have been reported. One is that the Nusselt number is directly proportional to the particle volume concentration[52,53,4]. While Sahin et al.reported that the higher values of the particle volume concentration over 1% badly affect heat transfer. "
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ABSTRACT: Numerical simulations of water-based ZnO nanofluids containing rod-like nanoparticles in a turbulent pipe flow are performed by solving the modified equations of Reynolds averaged Navier-Stokes, turbulence kinetic energy and turbulence dissipation rate with rod-like nanoparticle term, the general dynamic equation for rod-like nanoparticles and the equation describing the probability density functions for the rod-like nanoparticle orientation. Some results are validated by comparing with the available experimental or numerical results. The results show that the friction factor of nanofluids, being larger than that of the pure water, decreases with increasing Reynolds number and particle aspect ratio, and decreases when particle volume concentration Φ is changed from 0.4 v% to 0.93 v% and then increases when Φ is changed from 0.93 v% to 1.3 v%. The heat transfer of nanofluids is higher than that of the pure water. The ratios of Nusselt number for the nanofluid and pure water increase with increasing Reynolds number, particle aspect ratio and volume concentration. The ratios of energy performance evaluation criterion (PEC) for the nanofluids and pure water, PECnf/PECf, are less and larger than unity when Re < 10,000 and Re > 10,000, respectively. The values of PECnf/PECf increase with increasing the particle aspect ratio, and are not monotonously dependent on the particle volume concentration. It is more effective to use nanofluids containing rod-like nanoparticles with larger aspect ratio, at higher Reynolds number and at a suitable particle volume concentration. Finally the expressions of PECnf/PECf as a function of Reynolds number, particle volume concentration and particle aspect ratio are derived based on the numerical data.
Available from: Bhupesh Mahatha
- "Advances in nanoelectronics, nanophotonics, and nanomagnetics; ultrahigh performance cooling is necessary for many industrial technologies. The nanofluids are more stable and have acceptable viscosity with better wetting, spreading, and dispersion properties on solid surface  . Khan and Pop  introduced nanofluids in stretching sheet with effects of Brownian motion and thermophoresis forms. "
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ABSTRACT: The flow of a viscous, incompressiable and electrically conducting nanofluid flow over a stretching sheet under the influence of a transverse magnetic field is investigated taking in to account the effect of non-linear thermal radiation, newtonian heating and partial velocity slip. The nanofluid model considered in the paper incorporates the effect of Brownian motion and thermophoresis. The governing equations, in similarity form, are solved using Matlab's in-built boundary value problem solver “bvp4c”. The nanofluid flow model discussed in the present paper has significant applications in fluid engineering devices where the boundary surface is subjected to convecting heating and the temperature difference between the ambient fluid and the surface is large.
Available from: Krishnayan Haldar
- "A considerable research has been found in the literature to understand the heat transfer enhancement using different water based nanofluids; however most of these studies are limited to either pool boiling or cooling of low temperature substrates [13e19]. For example, Nguyen et al.  investigated the heat transfer potential of watereAl 2 O 3 nanofluid for an electronic liquid cooling system. It has been found that addition of nanoparticles increases the heat transfer coefficient of water by 40%. "
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ABSTRACT: Keywords: Air-assisted atomizer Heat transfer enhancement Nanofluid Run-out table application Spray evaporative cooling a b s t r a c t The study deals with the air-atomized spray cooling using nanofluid as the cooling media for high heat flux applications. The nanofluid has been prepared by commercial Al 2 O 3 particles of diameter less than 13 nm and water. Heat transfer study has been carried out on a pre-heated steel specimen of dimensions 100 mm Â 100 mm Â 6 mm. The initial temperature of the plate which was subjected to air-atomized spray cooling was over 900 C. Various coolants consisting of 0.1% volumetric concentration of water eAl 2 O 3 mixture, with or without a dispersing agent (surfactant) were used for the study. The dispersing agents used are sodium dodecyl sulphate (SDS) and polyoxyethylene (20) sorbitan monolaurate (Tween 20). Inverse heat conduction software INTEMP has been used for estimating the surface heat flux and temperatures taking into account the measured internal temperature histories by the thermocouples during the cooling process. The results obtained using nanofluid coolants are compared with that of the results where pure water (filtered potable water) is used as a coolant. The analyses reveal that the cooling rate, critical heat flux and heat transfer coefficients are significantly enhanced when nanofluids are used as coolants in air-atomized spray process. Also, the nanofluid coolants with dispersing agent shows a better enhancement of heat transfer over that of the nanofluid without the dispersing media. The nanofluid with dispersing agent Tween 20 is found more effective than that of its counterpart. Overall, the percentage enhancement in cooling rate of all these nanofluids compared with pure water (filtered potable water) is 10.2% for watereAl 2 O 3 , 18.6% for watereAl 2 O 3 eSDS, and upto 32.3% for watereAl 2 O 3 eTween 20.
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