On trade-off for dispersion stability and thermal transport of Cu-Al2O3 hybrid nanofluid for various mixing ratios

•0.5:0.5 is the optimum mixing ratio with enhanced overall hydrothermal properties.•Hybrid nanofluid shows three distinct concentration stratified zones.•Mixing ratio above 0.5:0.5 results in rapid settling due to high settling velocity.•Stability for mixing ratio below 0.5:0.5 is less dependent on...

Full description

Saved in:
Bibliographic Details
Published in:International journal of heat and mass transfer 2019-04, Vol.132, p.1200-1216
Main Authors: Siddiqui, F.R., Tso, C.Y., Chan, K.C., Fu, S.C., Chao, Christopher Y.H.
Format: Article
Language:English
Subjects:
Agglomeration
Aluminum oxide
Heat conductivity
Heat transfer
Hybrid Nanofluid
Mixing ratio
Nanofluids
Nanoparticles
Properties (attributes)
Ratios
Sedimentation
Sedimentation & deposition
Sedimentation Velocity
Stability
Thermal conductivity
Thermophysical Properties
Zeta Potential
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:•0.5:0.5 is the optimum mixing ratio with enhanced overall hydrothermal properties.•Hybrid nanofluid shows three distinct concentration stratified zones.•Mixing ratio above 0.5:0.5 results in rapid settling due to high settling velocity.•Stability for mixing ratio below 0.5:0.5 is less dependent on zeta potential. The dispersion stability and thermophysical properties of metal–metal oxide hybrid nanofluid for various mixing ratios are investigated in this paper. Cu nanoparticles having high thermal conductivity and poor dispersion stability are dispersed in water with Al2O3 nanoparticles that have a high dispersion stability and low thermal conductivity, in mixing ratios 0.3:0.7 (MR-1), 0.5:0.5 (MR-2) and 0.7:0.3 (MR-3) to achieve a Cu-Al2O3 hybrid nanofluid with improved hydrothermal properties. Dispersion stability and thermophysical properties of the hybrid nanofluid were studied for 240 h using various experimental techniques such as zeta/particle size analyser, UV–Vis spectroscopy, transmission electron microscope, sedimentation, thermal analyser and viscometer. The results show that the hybrid nanofluid transforms into low, medium and high concentration stratified zones over time. Also, stability in Cu/Al2O3 single particle nanofluids and MR-3 hybrid nanofluid is related to both sedimentation velocity and zeta potential while sedimentation velocity has the dominating effect on stability of MR-1 and MR-2 hybrid nanofluids. Mixing ratio above MR-2 is identified for rapid settling due to high sedimentation velocity. Also, MR-2 is determined as an optimum mixing ratio to achieve enhanced overall hydrothermal properties for the hybrid nanofluid due to its improved thermal conductivity and relatively better stability.
ISSN:0017-9310
1879-2189
DOI:10.1016/j.ijheatmasstransfer.2018.12.094