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Properties of six different types of nanofluids
Al2O3 + H2O
9.1980 × 10−4
TiO2 + H2O
CuO + H2O
Al2O3 + EG
1.6100 × 10−2
TiO2 + EG
CuO + EG
ε = 0.72, diameter of Cu powder = 470 μm, length of plate = 0.04 m, permeability = 7 × 10−9, T (ambient) = 293 K, T
= 324 K, d
= 10 nm, ϕ =0.04.
The reason for this behavior is the higher values of effective
thermal diffusivity and lower values of volumetric heat capacity
ratio of water-based nanofluids than EG-based nanofluids, as given
in Table 3. .
The values of parameters taken in the calculations are given in
The comparative study of different nanofluids is shown in Figure 9
and Table 3.
From Figure 9 and Table 3, it is concluded that there is only a
small change in the value of Nusselt numbers (average and local) as
well as skin friction coefficients for nanofluids having the same
base liquid (H2O/EG).
From Table 3, it is also clear that for the EG-based nanofluids,
the value of effective RaK is larger than the water-based
nanofluids, but still, the value of the average Nusselt number for
water-based nanofluids is larger than that of EG-based nanofluids.
Uddin, Ziya; Harmand, SouadJournal: Nanoscale Research Letters
Issue 1DOI: 10.1186/1556-276X-8-64Published: 2013-12-01Institution(s):
Université de Lille Nord de France, TEMPO/DF2T, UVHC
The unsteady natural convection heat transfer of nanofluid along a vertical plate embedded in porous medium is investigated. The Darcy-Forchheimer model is used to formulate the problem. Thermal conductivity and viscosity models based on a wide range of experimental data of nanofluids and incorporating the velocity-slip effect of the nanoparticle with respect to the base fluid, i.e., Brownian diffusion is used. The effective thermal conductivity of nanofluid in porous media is calculated using copper powder as porous media. The nonlinear governing equations are solved using an unconditionally stable implicit finite difference scheme. In this study, six different types of nanofluids have been compared with respect to the heat transfer enhancement, and the effects of particle concentration, particle size, temperature of the plate, and porosity of the medium on the heat transfer enhancement and skin friction coefficient have been studied in detail. It is found that heat transfer rate increases with the increase in particle concentration up to an optimal level, but on the further increase in particle concentration, the heat transfer rate decreases. For a particular value of particle concentration, small-sized particles enhance the heat transfer rates. On the other hand, skin friction coefficients always increase with the increase in particle concentration and decrease in nanoparticle size.
This table is from the article titled "Natural convection heat transfer of nanofluids along a vertical plate embedded in porous medium"
(from Nanoscale Research Letters), which is copyrighted by Uddin and Harmand; licensee Springer. For more information on the
copyright for this table, please refer to the full table caption and to the
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