Enhancing thermal conductivity of fluids with nano-particles
01 Jan 1995-Vol. 231, pp 99-105
About: The article was published on 1995-01-01 and is currently open access. It has received 7263 citations till now. The article focuses on the topics: Thermal conductivity & Nanoparticle.
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TL;DR: In this paper, a model for predicting the effective thermal conductivity of nanofluids is proposed, which takes into account some additional effects including volume fraction, thickness, thermal conductivities of the interfacial layer and particle size.
Abstract: A model for predicting the effective thermal conductivity of nanofluids is proposed. It has been documented that the interfacial layer at the solid (particle)/liquid interface and particle size is one of the major mechanisms for enhancing the thermal conductivity of nanofluids. Comparing with other classical models, the proposed model takes into account some additional effects including volume fraction, thickness, thermal conductivity of the interfacial layer and particle size. The proposed model is found to be better than the existing models since the predicted effective thermal conductivity of different types of nanofluids are closer to the experimental results.
345 citations
Cites background from "Enhancing thermal conductivity of f..."
...Since nanofluids studies emerged in 1995 at the Argonne National Laboratory, USA (Choi, 1995), experimental results of the thermal conductivity of nanofluids were reported to be significantly higher than those of base fluids as well as the theoretical predictions by existing models....
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TL;DR: In this paper, the effects of Rayleigh number (103≤Ra≤106) and water, nanofluid, and hybrid nanoparticles as the working fluid on temperature fields and heat transfer performance of the enclosure are investigated.
Abstract: This paper numerically examines laminar natural convection in a sinusoidal corrugated enclosure with a discrete heat source on the bottom wall, filled by pure water, Al2O3/water nanofluid, and Al2O3-Cu/water hybrid nanofluid which is a new advanced nanofluid with two kinds of nanoparticle materials. The effects of Rayleigh number (103≤Ra≤106) and water, nanofluid, and hybrid nanofluid (in volume concentration of 0% ≤ ϕ ≤ 2%) as the working fluid on temperature fields and heat transfer performance of the enclosure are investigated. The finite volume discretization method is employed to solve the set of governing equations. The results indicate that for all Rayleigh numbers been studied, employing hybrid nanofluid improves the heat transfer rate compared to nanofluid and water, which results in a better cooling performance of the enclosure and lower temperature of the heated surface. The rate of this enhancement is considerably more at higher values of Ra and volume concentrations. Furthermore, by applying ...
343 citations
Additional excerpts
...Choi [3] presented the benefit of using the nanoparticles dispersed in a base fluid in different thermal systems to enhance the heat transfer rate....
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TL;DR: In this article, the effects of the nanoparticle volume fraction, Reynolds number, expansion ratio and power law index on Hydrothermal behavior of nanofluid fluid between two parallel plates is studied.
336 citations
TL;DR: In this paper, a comprehensive review is conducted on the simultaneous application of nanofluids and porous media for heat transfer enhancement purposes in thermal systems with different structures, flow regimes, and boundary conditions.
333 citations
Cites background from "Enhancing thermal conductivity of f..."
...Nanofluid (Nanosuspension), introduced by Choi in 1995 [1], mainly consists of two...
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TL;DR: In this paper, a review of the thermal conductivity of nanofluids is presented, focusing on the experimental data, proposed mechanisms responsible for its enhancement, and its predicting models.
Abstract: Nanofluids—fluid suspensions of nanometer-sized particles—are a very important area of emerging technology and are playing an increasingly important role in the continuing advances of nanotechnology and biotechnology worldwide. They have enormously exciting potential applications and may revolutionize the field of heat transfer. This review is on the advances in our understanding of heat-conduction process in nanofluids. The emphasis centers on the thermal conductivity of nanofluids: its experimental data, proposed mechanisms responsible for its enhancement, and its predicting models. A relatively intensified effort has been made on determining thermal conductivity of nanofluids from experiments. While the detailed microstructure-conductivity relationship is still unknown, the data from these experiments have enabled some trends to be identified. Suggested microscopic reasons for the experimental finding of significant conductivity enhancement include the nanoparticle Brownian motion, the Brownian-motion-induced convection, the liquid layering at the liquid-particle interface, and the nanoparticle cluster/aggregate. Although there is a lack of agreement regarding the role of the first three effects, the last effect is generally accepted to be responsible for the reported conductivity enhancement. The available models of predicting conductivity of nanofluids all involve some empirical parameters that negate their predicting ability and application. The recently developed first-principles theory of thermal waves offers not only a macroscopic reason for experimental observations but also a model governing the microstructure-conductivity relationship without involving any empirical parameter.
328 citations