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: It is found that viscosity and thermal conductivity are the most prominent parameters responsible for different results of velocity and temperature, and C2H6O2 is regarded as better convectional base fluid compared to H2O.
Abstract: Energy transfer in mixed convection unsteady magnetohydrodynamic (MHD) flow of an incompressible nanofluid inside a channel filled with saturated porous medium is investigated. The channel with non-uniform walls temperature is taken in a vertical direction under the influence of a transverse magnetic field. Based on the physical boundary conditions, three different flow situations are discussed. The problem is modelled in terms of partial differential equations with physical boundary conditions. Four different shapes of nanoparticles of equal volume fraction are used in conventional base fluids, ethylene glycol (EG) (C2H6O2) and water (H2O). Solutions for velocity and temperature are obtained discussed graphically in various plots. It is found that viscosity and thermal conductivity are the most prominent parameters responsible for different results of velocity and temperature. Due to higher viscosity and thermal conductivity, C2H6O2 is regarded as better convectional base fluid compared to H2O.
130 citations
Cites background from "Enhancing thermal conductivity of f..."
...Choi [1] in his pioneering work indicated that when a small amount of nanoparticles is added to common base fluids, it increases significantly the thermal conductivity of the base fluids as well as their convective heat transfer rate....
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TL;DR: In this article, a review of recent researches on the pool boiling heat transfer behavior of nanofluid is presented, where the authors discuss the effects of various parameters on pool boiling.
130 citations
TL;DR: In this paper, the authors measured the vapor absorption rate and heat transfer rate for falling film flow of binary nanofluids, and compared the enhancement of heat transfer and mass transfer under the same conditions of nanometres.
Abstract: The objectives of this study are to measure the vapor absorption rate and heat transfer rate for falling film flow of binary nanofluids, and to compare the enhancement of heat transfer and mass transfer under the same conditions of nanofluids. The key parameters are the base fluid concentration of LiBr, the concentration of nanoparticles in weight %, and nanoparticle constituents. The binary nanofluids are H 2 O/LiBr solution with nanoparticles of Fe and Carbon nanotubes (CNT) with the concentrations of 0.0, 0.01 and 0.1 wt %. The vapor absorption rate increases with increasing the solution mass flow rate and the concentration of Fe and CNT nanoparticles. It is found that the mass transfer enhancement is much more significant than the heat transfer enhancement in the binary nanofluids with Fe and CNT. It is also found that the mass transfer enhancement from the CNT nanoparticles becomes higher than that from the Fe nanoparticles. Therefore, the CNT is a better candidate than Fe nanoparticles for absorption performance enhancement in H 2 O/LiBr absorption system.
129 citations
TL;DR: A review of heat transfer augmentation methods that assist fin and micro-fins in enhancing heat transfer is presented in this article, where the authors describe flow and heat transfer in porous media as a well-modelled passive enhancement method.
Abstract: Different heat transfer enhancers are reviewed. They are (a) fins and microfins, (b) porous media, (c) large particles suspensions, (d) nanofluids, (e) phase-change devices, (f) flexible seals, (g) flexible complex seals, (h) vortex generators, (i) protrusions, and (j) ultra high thermal conductivity composite materials. Most of heat transfer augmentation methods presented in the literature that assists fins and microfins in enhancing heat transfer are reviewed. Among these are using joint-fins, fin roots, fin networks, biconvections, permeable fins, porous fins, capsulated liquid metal fins, and helical microfins. It is found that not much agreement exists between works of the different authors regarding single phase heat transfer augmented with microfins. However, too many works having sufficient agreements have been done in the case of two phase heat transfer augmented with microfins. With respect to nanofluids, there are still many conflicts among the published works about both heat transfer enhancement levels and the corresponding mechanisms of augmentations. The reasons beyond these conflicts are reviewed. In addition, this paper describes flow and heat transfer in porous media as a well-modeled passive enhancement method. It is found that there are very few works which dealt with heat transfer enhancements using systems supported with flexible/flexible-complex seals. Eventually, many recent works related to passive augmentations of heat transfer using vortex generators, protrusions, and ultra high thermal conductivity composite material are reviewed. Finally, theoretical enhancement factors along with many heat transfer correlations are presented in this paper for each enhancer.
129 citations
Cites methods from "Enhancing thermal conductivity of f..."
...A new passive method developed by Choi [101] which is termed “nanofluids” has shown to resolve some disadvantages associated with the suspensions of large particles....
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...The nanofluid thermal conductivity developed model of Jang and Choi [137] took into account the collision between base fluid molecules, thermal diffusion of nanoparticles in fluids, collision between nanoparticles and nanoconvection due to Brownian motion....
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...Of these studies is the study of Yu and Choi [128]....
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TL;DR: This article investigates heat transfer enhancement in free convection flow of Maxwell nanofluids with carbon nanotubes (CNTs) over a vertically static plate with constant wall temperature.
Abstract: This article investigates heat transfer enhancement in free convection flow of Maxwell nanofluids with carbon nanotubes (CNTs) over a vertically static plate with constant wall temperature. Two kinds of CNTs i.e. single walls carbon nanotubes (SWCNTs) and multiple walls carbon nanotubes (MWCNTs) are suspended in four different types of base liquids (Kerosene oil, Engine oil, water and ethylene glycol). Kerosene oil-based nanofluids are given a special consideration due to their higher thermal conductivities, unique properties and applications. The problem is modelled in terms of PDE’s with initial and boundary conditions. Some relevant non-dimensional variables are inserted in order to transmute the governing problem into dimensionless form. The resulting problem is solved via Laplace transform technique and exact solutions for velocity, shear stress and temperature are acquired. These solutions are significantly controlled by the variations of parameters including the relaxation time, Prandtl number, Grashof number and nanoparticles volume fraction. Velocity and temperature increases with elevation in Grashof number while Shear stress minimizes with increasing Maxwell parameter. A comparison between SWCNTs and MWCNTs in each case is made. Moreover, a graph showing the comparison amongst four different types of nanofluids for both CNTs is also plotted.
129 citations
Cites background from "Enhancing thermal conductivity of f..."
...u y q a q q a q a b y a q q a q q a q a b y b q ( , ) ( 1) [ ( )] exp( ( 1) ) ( 1) [ ( )] exp( ) (19) 1 2 0 0 1 0 1 2 0 0 1 1...
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...(19) with respect to spatial variable y, emits...
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