Experimental study of thermo-convection performance of hybrid nanofluids of Al2O3-MWCNT/water in a differentially heated square cavity

Giwa, Solomon O.; Sharifpur, Mohsen; Meyer, Josua P.

doi:10.1016/j.ijheatmasstransfer.2019.119072

Cited by 112 publications

(50 citation statements)

References 39 publications

(72 reference statements)

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“…Consequently, the electrical conductivity of the nanofluids was directly proportional to the volume concentration and temperature, which was consistent with earlier studies reported in the literature for mono-particle and hybrid nanofluids [ 14 , 38 , 45 , 46 , 47 , 48 ]. At 55 °C and 1.5 vol%, maximum electrical conductivity (4139 μS/cm) was obtained which was considerably higher than the values of 19.0 μS/cm (for Fe 3 O 4 /water nanofluid at 0.6 vol% and 60 °C) and 1127–1265 μS/cm (Al 2 O 3 -MWCNT (80:20)/DIW nanofluid at 0.1 vol% and 50 °C) reported by Bagheli et al [ 49 ] and Giwa et al [ 38 ], respectively. However, Giwa et al [ 48 ] published a range of 640–4570 μS/cm for Al 2 O 3 -Fe 2 O 3 (75:25)/DIW nanofluid (at 0.75 vol% and 50 °C), which had a maximum value slightly higher than that reported for MWCNT-Fe 2 O 3 (20:80)/DIW nanofluid in the present work.…”

Section: Resultssupporting

confidence: 91%

“…The nanofluid types, size of nanoparticles, volume/weight concentration or fraction, mixing ratio (for hybrid nanofluid), and temperature used in the various studies may be responsible for the variation in the results. However, a comparison of the works of Kumar et al [ 44 ] and Bagheli et al [ 49 ] with those of Giwa et al [ 38 ] and Giwa et al [ 48 ] supported the finding in the present study for MWCNT-Fe 2 O 3 /DIW nanofluid with regard to the augmentation of electrical conductivity because of the hybridization of bi-nanoparticles.…”

Section: Resultssupporting

confidence: 85%

“…In comparison to previous studies, Bagheli et al [ 49 ] (Fe 3 O 4 /water nanofluid; 60 °C and 0.5 vol%), Sundar et al [ 47 ] (nanodiamond-nickel/water nanofluid; 0.1 vol% and 65 °C), Kumar et al [ 44 ] (MWCNT/water nanofluid; 0.6 vol% and 50 °C), Mehrali et al [ 43 ] (nitrogen-doped graphene/water nanofluid; 60 °C and 0.06 wt%), Adio et al [ 14 ] (EG-based MgO nanofluid; 0.5 vol% and 25 °C), Giwa et al [ 38 ] (Al 2 O 3 -MWCNT (80:20)/DIW nanofluid; 0.1 vol% and 50 °C), and Giwa et al [ 48 ] (Al 2 O 3 -Fe 2 O 3 (75:25)/DIW nanofluid; 0.75 vol% and 50 °C) measured enhancements of 360%, 853.15%, 1814.96%, 190.57%, 6000%, 134.12–255.34%, and 163.37–1692.16%, respectively, for the electrical conductivity of different mono-particles and hybrid nanofluids. The nanofluid types, size of nanoparticles, volume/weight concentration or fraction, mixing ratio (for hybrid nanofluid), and temperature used in the various studies may be responsible for the variation in the results.…”

Section: Resultsmentioning

confidence: 99%

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Experimental Investigation on Stability, Viscosity, and Electrical Conductivity of Water-Based Hybrid Nanofluid of MWCNT-Fe2O3

et al. 2021

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The superiority of nanofluid over conventional working fluid has been well researched and proven. Newest on the horizon is the hybrid nanofluid currently being examined due to its improved thermal properties. This paper examined the viscosity and electrical conductivity of deionized water (DIW)-based multiwalled carbon nanotube (MWCNT)-Fe2O3 (20:80) nanofluids at temperatures and volume concentrations ranging from 15 °C to 55 °C and 0.1–1.5%, respectively. The morphology of the suspended hybrid nanofluids was characterized using a transmission electron microscope, and the stability was monitored using visual inspection, UV–visible, and viscosity-checking techniques. With the aid of a viscometer and electrical conductivity meter, the viscosity and electrical conductivity of the hybrid nanofluids were determined, respectively. The MWCNT-Fe2O3/DIW nanofluids were found to be stable and well suspended. Both the electrical conductivity and viscosity of the hybrid nanofluids were augmented with respect to increasing volume concentration. In contrast, the temperature rise was noticed to diminish the viscosity of the nanofluids, but it enhanced electrical conductivity. Maximum increments of 35.7% and 1676.4% were obtained for the viscosity and electrical conductivity of the hybrid nanofluids, respectively, when compared with the base fluid. The obtained results were observed to agree with previous studies in the literature. After fitting the obtained experimental data, high accuracy was achieved with the formulated correlations for estimating the electrical conductivity and viscosity. The examined hybrid nanofluid was noticed to possess a lesser viscosity in comparison with the mono-particle nanofluid of Fe2O3/water, which was good for engineering applications as the pumping power would be reduced.

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%

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Experimental Investigation on Stability, Viscosity, and Electrical Conductivity of Water-Based Hybrid Nanofluid of MWCNT-Fe2O3

et al. 2021

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“…With the use of Al 2 O 3 -MWCNT (90:10)/DIW NF, the coefficient of heat transfer and Nu were augmented by 9.8% and 19.4%, respectively. Additionally, Giwa et al [ 157 ] worked on the thermo-convection behavior in a square enclosure filled with DIW-based HNF (Al 2 O 3 -MWCNT). They experimented with DIW-based Al 2 O 3 :MWCNT (80:20–20:80) NF for 0.1 vol.% at Ra of 1.65 × 10 8 –3.80 × 10 8 .…”

Section: Convective Heat Transfer Performance Of Nanofluidsmentioning

confidence: 99%

Experimental Research and Development on the Natural Convection of Suspensions of Nanoparticles—A Comprehensive Review

et al. 2020

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Suspensions of nanoparticles, widely known as nanofluids, are considered as advanced heat transfer media for thermal management and conversion systems. Research on their convective thermal transport is of paramount importance for their applications in such systems such as heat exchangers and solar collectors. This paper presents experimental research on the natural convection heat transfer performances of nanofluids in different geometries from thermal management and conversion perspectives. Experimental results and available experiment-derived correlations for the natural thermal convection of nanofluids are critically analyzed. Other features such as nanofluid preparation, stability evaluation and thermophysical properties of nanofluids that are important for this thermal transfer feature are also briefly reviewed and discussed. Additionally, techniques (active and passive) employed for enhancing the thermo-convection of nanofluids in different geometries are highlighted and discussed. Hybrid nanofluids are featured in this work as the newest class of nanofluids, with particular focuses on the thermophysical properties and natural convection heat transfer performance in enclosures. It is demonstrated that there has been a lack of accurate stability evaluation given the inconsistencies of available results on these properties and features of nanofluids. Although nanofluids exhibit enhanced thermophysical properties such as viscosity and thermal conductivity, convective heat transfer coefficients were observed to deteriorate in some cases when nanofluids were used, especially for nanoparticle concentrations of more than 0.1 vol.%. However, there are inconsistencies in the literature results, and the underlying mechanisms are also not yet well-understood despite their great importance for practical applications.

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“…Also two layers study by Hussein et al [28]. The experimental study within nanofluid enclosure investigations by researchers [29,30]. Solomon et al [31] experimental study on the influence of the aspect ratio of square cavity on natural convection heat transfer with Al2O3/Water nanofluids.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Mixed Convection on a Rotating Circular Cylinder in a Cavity Filled With Nanofluid and Porous Media

Abdulsahib

Al‐Farhany

2020

QJES

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The present study, experimentally investigated the mixed convection in a square enclosure partitioned in two layers. The experiments were performed with Al2O3–water nanofluid (upper layer) and superposed porous medium (lower layer) with an adiabatic rotating cylinder at the center of the cavity. The boundary conditions of the experimental study were; the upper and lower walls were assumed adiabatic, the right wall was heated, and the left wall was cooled. Experimentally, 15 K-type thermocouples and thermal imaging camera were employed to measure the temperatures distribution inside the cavity when the concentration of nanoparticles (ɸ = 0.06), the temperature difference (∆T) between the cold and hot walls was (6, 8, and 10) °C, and angular rotational velocity (-50, -25, 0, 25, and 50) rpm. The results of experimental data showed that in general, the distribution of temperatures was very well along the upper half of the enclosure, while in the lower half the temperature distribution was confined near the hot wall region. When the circular cylinder rotates in counter-clockwise, it noted that the effect of speed is evident in the downside of the cylinder, while the temperature distribution in the left upper part of the enclosure decreasing. When the circular cylinder rotates in the clockwise direction, the results showed that the effect of cylinder rotation was around cylinder only. Moreover, the results demonstrated that the increasing temperature difference leads to a noticeable increment in the intensity of the flow.

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Experimental study of thermo-convection performance of hybrid nanofluids of Al2O3-MWCNT/water in a differentially heated square cavity

Cited by 112 publications

References 39 publications

Experimental Investigation on Stability, Viscosity, and Electrical Conductivity of Water-Based Hybrid Nanofluid of MWCNT-Fe2O3

Experimental Investigation on Stability, Viscosity, and Electrical Conductivity of Water-Based Hybrid Nanofluid of MWCNT-Fe2O3

Experimental Research and Development on the Natural Convection of Suspensions of Nanoparticles—A Comprehensive Review

Experimental Investigation of Mixed Convection on a Rotating Circular Cylinder in a Cavity Filled With Nanofluid and Porous Media

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