An experimental study on the thermal conductivity and dynamic viscosity of TiO 2 -SiO 2 nanofluids in water: Ethylene glycol mixture

Nabil, Mahdi; Azmi, W.H.; Hamid, Khalid; Mamat, Rizalman; Hagos, Ftwi Yohaness

doi:10.1016/j.icheatmasstransfer.2017.05.024

Cited by 225 publications

(77 citation statements)

References 59 publications

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“…Several studies have been conducted on the TC of HNF since the pioneering works of Chokpar et al [ 56 ] and Jana et al [ 57 ]. These studies utilized several combinations of NP dispersed in diverse base fluids at different temperatures and volume/mass concentrations or fractions and reported TC enhancements with a rise in temperature and volume/mass concentrations or fractions [ 46 , 58 , 59 , 61 , 62 , 63 , 65 , 75 , 77 , 100 , 101 , 102 ]. It has been established and published that the TCs of HNF are numerically above those of NF [ 65 , 77 , 102 ].…”

Section: Thermophysical Properties Of Nanofluids and Hybrid-nanoflmentioning

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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Section: Thermophysical Properties Of Nanofluids and Hybrid-nanoflmentioning

confidence: 99%

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

et al. 2020

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“…This study conducts visual observation for 21 days for stability analysis of TIO2-Al2O3 hybrid nanofluids. Visual inspection is also followed in previous investigations [50,55,56]. Besides, absorbance value is found through Uv-vis spectral analysis for specifying the stability condition of nanofluids.…”

Section: Stability Of Nanofluidsmentioning

confidence: 99%

Experimental Investigation on the Stability of 40% Ethylene Glycol Based TiO2-Al2O3 Hybrid Nanofluids

Urmi¹,

Rahman²,

Azmi³

et al. 2020

ARFMTS

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This paper is presented to investigate experimentally on the stability of 40% ethylene glycol-based TiO2-Al2O3 hybrid nanofluids. Recently, the research is more highlighted on the thermophysical-properties of nanofluids. Hence, the stability of the hybrid nanofluids thoroughly assessed in this research work. The study uses the two-step method for preparing 40% ethylene glycol-based TiO2-Al2O3 hybrid nanofluids. The experiment is carried out for the various combination of mixture ratios including 20:80, 40:60, 50:50, 60:40 and 80:20 of TiO2-Al2O3 nanoparticles with a volume concentration of 0.1%. The stability assessment of hybrid nanofluids is accomplished through visualisation effect, transmission electronic microscopic observation, UV-Vis spectrophotometry and zeta potential value from particle size analyser. The findings show the optimum mixing ratios of TiO2-Al2O3 nanoparticles in terms of stability which is further confirmed by Zeta potential and absorbency from UV-Vis spectrophotometry. The results from the study reveal that 80:20 ratio of TiO2-Al2O3 nanoparticles possesses the best uniformity for over 21 days without any noticeable settlement of particles in the colloidal suspension. Moreover, 50:50 and 60:40 ratios show modest stability for almost two weeks while 20:80 and 40:60 ratios of TiO2-Al2O3 nanoparticles show minimum stability along with rapid sedimentation in the dispersion. However, it is also evident that the optimum mixing ratio of TiO2-Al2O3 hybrid nanofluids has excellent stability which will lead to further study on the thermal properties of nanofluids and finally motivate engineers to the real-life application of nanofluids.

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“…Various other authors also observed the same result. [34][35][36] Property of the hybrid nanofluid depends upon the base fluid and also on the shape of the nanoparticle considered. However, optimum dynamic viscosity observed for the Al 2 O 3 -CuO hybrid nanofluid with 30%PG binary base fluid at a temperature of 70°C.…”

Section: Effect On Thermal Conductivity and Dynamic Viscosity With mentioning

confidence: 99%

Viscosity and thermal conductivity comparative study for hybrid nanofluid in binary base fluids

Kumar

Sahoo

2019

Heat Trans. Asian Res.

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Thermal conductivity and viscosity analysis of Al2O 3/CuO (50/50) hybrid nanofluid in various mass fractions of ethylene glycol (EG) and propylene glycol (PG) binary base fluid have been investigated in the present work. Hybrid nanofluid with vol. fraction range limited to 1.5% and within the higher temperature range of 50°C to 70°C is considered for thermal conductivity and viscosity analysis. Impact on viscosity and conductivity models with various shape nanoparticles, i.e, spherical, cylindrical, brick, platelets, and blades have been discussed and were compared in EG and PG binary base fluids. Also, the analysis extends to the prediction for the stability with zeta potential and synthesis of spherical shape Al2O3/CuO hybrid nanofluid with X‐ray diffraction (XRD) and scanning electron microscope (SEM). The theoretical analysis revealed that thermal conductivity of Al2O3/CuO hybrid nanofluid in EG binary base fluid is lower compared to in PG binary base fluid. The thermal conductivity is observed to be higher in spherical and cylindrical shape nanoparticle compared to bricks, blades, and platelets shape nanoparticles. Optimum viscosity of Al2O3/CuO hybrid nanofluid is observed at 50%EG and 30%PG of the binary base fluid. Hybrid nanofluid in 30% of PG as binary base fluid results 16.2% higher dynamic viscosity compared to pure PG base fluid for a volume concentration of 2%. Zeta potential measurement results in the stability of spherical Al2O3‐CuO/ (50/50) EG/W hybrid nanofluid, and it may be considered as a heat transfer fluid.

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An experimental study on the thermal conductivity and dynamic viscosity of TiO 2 -SiO 2 nanofluids in water: Ethylene glycol mixture

Cited by 225 publications

References 59 publications

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

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

Experimental Investigation on the Stability of 40% Ethylene Glycol Based TiO2-Al2O3 Hybrid Nanofluids

Viscosity and thermal conductivity comparative study for hybrid nanofluid in binary base fluids

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