Investigation on Convective Heat Transfer and Flow Features of Nanofluids
01 Feb 2003-Journal of Heat Transfer-transactions of The Asme (American Society of Mechanical Engineers)-Vol. 125, Iss: 1, pp 151-155
TL;DR: In this article, an innovative new class of heat transfer fluids can be engineered by suspending metallic nanoparticles in conventional heat-transfer fluids, which are expected to exhibit high thermal conductivities compared to those of currently used heat transfer fluid, and they represent the best hope for enhancing heat transfer.
Abstract: Low thermal conductivity is a primary limitation in the development of energy-efficient heat transfer fluids that are required in many industrial applications. In this paper we propose that an innovative new class of heat transfer fluids can be engineered by suspending metallic nanoparticles in conventional heat transfer fluids. The resulting {open_quotes}nanofluids{close_quotes} are expected to exhibit high thermal conductivities compared to those of currently used heat transfer fluids, and they represent the best hope for enhancement of heat transfer. The results of a theoretical study of the thermal conductivity of nanofluids with copper nanophase materials are presented, the potential benefits of the fluids are estimated, and it is shown that one of the benefits of nanofluids will be dramatic reductions in heat exchanger pumping power.
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TL;DR: In this paper, the authors examined the natural convection in an enclosure that is filled with a water-Al2O3 nanofluid and is influenced by a magnetic field, based upon numerical predictions, the effects of pertinent parameters such as the Rayleigh number (103,≤,Ra,≤ 107), the solid volume fraction (0.06), and the Hartmann number ( 0.1), on the flow and temperature fields and the heat transfer performance of the enclosure were examined.
438 citations
TL;DR: In this article, the onset of convection in a horizontal layer of a porous medium saturated by a nanofluid is studied analytically, and it is found that the critical thermal Rayleigh number can be reduced or increased by a substantial amount depending on whether the basic nanoparticle distribution is top-heavy or bottom-heavy, by the presence of the nanoparticles.
434 citations
TL;DR: In this article, a single-and two-phase model with either constant or temperature-dependent properties is employed to develop laminar forced convection flow of a water-Al2O3 nanofluid in a circular tube, submitted to a constant and uniform heat flux at the wall.
434 citations
Cites background from "Investigation on Convective Heat Tr..."
...Experimental results were obtained on convective heat transfer for laminar and turbulent flow of a nanofluid inside a tube in [14, 28, 29]....
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TL;DR: In this article, aqueous-based nanofluids are formulated in such a way that they are found very stable and are used to investigate their heat transfer behavior under the natural convection conditions.
430 citations
TL;DR: In this article, a review of the fluid flow and heat transfer characteristics of nanofluids in forced and free convection flows and potential applications of nanopharticles is presented.
Abstract: Research in convective heat transfer using suspensions of nanometer-sized solid particles in base liquids started only over the past decade. Recent investigations on nanofluids, as such suspensions are often called, indicate that the suspended nanoparticles markedly change the transport properties and heat transfer characteristics of the suspension. This second part of the review covers fluid flow and heat transfer characteristics of nanofluids in forced and free convection flows and potential applications of nanofluids. Opportunities for future research are identified as well. Keywords: Nanofluids; Nanoparticles; Heat transfer; Thermal conductivity.
430 citations
Cites background from "Investigation on Convective Heat Tr..."
...Previous studies with nearly spherical nanoparticles (aspect ratio, α≈1) (Pak and Cho, 1998; Xuan and Li, 2003; Wen and Ding, 2004b) showed an enhancement of the convective heat transfer of up to 60%....
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...(aspect ratio, α≈1) (Pak and Cho, 1998; Xuan and Li, 2003; Wen and Ding, 2004b) showed an enhancement of the convective heat transfer of up to 60%....
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...Xuan and Li (2003) experimentally investigated flow and convective heat transfer characteristics for Cu-water based nanofluids through a straight tube with a constant heat flux at the wall....
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References
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Book•
01 Jan 1985
TL;DR: In this article, the physical concepts and methodologies of heat and mass transfer are explained for advanced undergraduate engineering majors, using a systematic method for problem solving and discusses the relationship of heat transfer to many important practical applications through examples and problems.
Abstract: This book, designed for advanced undergraduate engineering majors, explains the physical concepts and methodologies of heat and mass transfer. It uses a systematic method for problem solving and discusses the relationship of heat and mass transfer to many important practical applications through examples and problems. A and significant contribution is the extensive use of the First Law of thermodynamics.
4,113 citations
TL;DR: In this article, the authors used a Brookfield rotating viscometer to measure the viscosities of the dispersed fluids with γ-alumina (Al2O3) and titanium dioxide (TiO2) particles at a 10% volume concentration.
Abstract: Turbulent friction and heat transfer behaviors of dispersed fluids (i.e., uttrafine metallic oxide particles suspended in water) in a circular pipe were investigated experimentally. Viscosity measurements were also conducted using a Brookfield rotating viscometer. Two different metallic oxide particles, γ-alumina (Al2O3) and titanium dioxide (TiO2), with mean diameters of 13 and 27 nm, respectively, were used as suspended particles. The Reynolds and Prandtl numbers varied in the ranges l04-I05 and 6.5-12.3, respectively. The viscosities of the dispersed fluids with γ-Al2O3 and TiO2 particles at a 10% volume concentration were approximately 200 and 3 times greater than that of water, respectively. These viscosity results were significantly larger than the predictions from the classical theory of suspension rheology. Darcy friction factors for the dispersed fluids of the volume concentration ranging from 1% to 3% coincided well with Kays' correlation for turbulent flow of a single-phase fluid. The Nusselt n...
3,730 citations
3,019 citations
"Investigation on Convective Heat Tr..." refers background in this paper
...Hamilton and Crasser (1962) have developed a more elaborate model for the effective thermal conductivity of twocomponent mixtures as a function of the conductivity of the pure materials, the composition of the mixture, and the shape of the dispersed particles....
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TL;DR: In this paper, a transient hot-wire method was used to measure the thermal conductivity of a small amount of nanoparticles and the experimental results showed that these nanoparticles have substantially higher thermal conductivities than the same liquids without nanoparticles.
Abstract: Oxide nanofluids were produced and their thermal conductivities were measured by a transient hot-wire method. The experimental results show that these nanofluids, containing a small amount of nanoparticles, have substantially higher thermal conductivities than the same liquids without nanoparticles. Comparisons between experiments and the Hamilton and Crosser model show that the model can predict the thermal conductivity of nanofluids containing large agglomerated Al{sub 2}O{sub 3} particles. However, the model appears to be inadequate for nanofluids containing CuO particles. This suggests that not only particle shape but size is considered to be dominant in enhancing the thermal conductivity of nanofluids.
2,811 citations
TL;DR: In this article, the authors proposed two different approaches for deriving heat transfer correlation of the nanofluid, and investigated the mechanism of heat transfer enhancement of the nano-fluid.
2,355 citations