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Experimental stability analysis of different water-based nanofluids.

Fedele L, Colla L, Bobbo S, Barison S, Agresti F - Nanoscale Res Lett (2011)

Bottom Line: Different dispersion techniques were considered in this study, including sonication, ball milling and high-pressure homogenization.Both the dispersion process and the use of some dispersants were investigated as a function of the nanoparticle concentration.The high-pressure homogenization was found to be the best method, and the addition of n-dodecyl sulphate and polyethylene glycol as dispersants, respectively in SWCNHs-water and TiO2-water nanofluids, improved the nanofluid stability.

View Article: PubMed Central - HTML - PubMed

Affiliation: Consiglio Nazionale delle Ricerche, Istituto per le Tecnologie della Costruzione, Corso Stati Uniti, I-35127 Padova, Italy. sergio.bobbo@itc.cnr.it.

ABSTRACT
In the recent years, great interest has been devoted to the unique properties of nanofluids. The dispersion process and the nanoparticle suspension stability have been found to be critical points in the development of these new fluids. For this reason, an experimental study on the stability of water-based dispersions containing different nanoparticles, i.e. single wall carbon nanohorns (SWCNHs), titanium dioxide (TiO2) and copper oxide (CuO), has been developed in this study. The aim of this study is to provide stable nanofluids for selecting suitable fluids with enhanced thermal characteristics. Different dispersion techniques were considered in this study, including sonication, ball milling and high-pressure homogenization. Both the dispersion process and the use of some dispersants were investigated as a function of the nanoparticle concentration. The high-pressure homogenization was found to be the best method, and the addition of n-dodecyl sulphate and polyethylene glycol as dispersants, respectively in SWCNHs-water and TiO2-water nanofluids, improved the nanofluid stability.

No MeSH data available.


Nanoparticles' size distribution for water containing 0.1 wt.% TiO2 + 0.2 wt.% PEG. At (thick line) day 1, (dashed line) day 30 for static and day 30 for shaken (dashed-dotted line).
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Figure 6: Nanoparticles' size distribution for water containing 0.1 wt.% TiO2 + 0.2 wt.% PEG. At (thick line) day 1, (dashed line) day 30 for static and day 30 for shaken (dashed-dotted line).

Mentions: On the contrary, the other samples were quite stable. In the case of static solutions, the mean size slightly decreased to around 70 nm after a few days and then it remained stable, indicating only a partial precipitation. However, after a simple mechanical shaking a mean particle size of approximately 130 nm was repeatedly recovered, suggesting the absence of further aggregation phenomena. This result is of interest because it suggests a possible application in devices where the fluids are frequently or continuously stirred, e.g. in plants with forced circulation. All the measurements provided average diameters higher than the 21 nm of the base powder, but the aggregates grew just after preparation, keeping nanometric and constant dimensions even after 30 days. In order to highlight this behaviour, Figure 6 represents the nanoparticle size distribution for water-TiO2 at 0.1 and 0.2 wt.% PEG. After 30 days, while the static sample shows a smaller average diameter than at the first day, the shaken nanofluid gives the same value, i.e. no further aggregation was detected.


Experimental stability analysis of different water-based nanofluids.

Fedele L, Colla L, Bobbo S, Barison S, Agresti F - Nanoscale Res Lett (2011)

Nanoparticles' size distribution for water containing 0.1 wt.% TiO2 + 0.2 wt.% PEG. At (thick line) day 1, (dashed line) day 30 for static and day 30 for shaken (dashed-dotted line).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211367&req=5

Figure 6: Nanoparticles' size distribution for water containing 0.1 wt.% TiO2 + 0.2 wt.% PEG. At (thick line) day 1, (dashed line) day 30 for static and day 30 for shaken (dashed-dotted line).
Mentions: On the contrary, the other samples were quite stable. In the case of static solutions, the mean size slightly decreased to around 70 nm after a few days and then it remained stable, indicating only a partial precipitation. However, after a simple mechanical shaking a mean particle size of approximately 130 nm was repeatedly recovered, suggesting the absence of further aggregation phenomena. This result is of interest because it suggests a possible application in devices where the fluids are frequently or continuously stirred, e.g. in plants with forced circulation. All the measurements provided average diameters higher than the 21 nm of the base powder, but the aggregates grew just after preparation, keeping nanometric and constant dimensions even after 30 days. In order to highlight this behaviour, Figure 6 represents the nanoparticle size distribution for water-TiO2 at 0.1 and 0.2 wt.% PEG. After 30 days, while the static sample shows a smaller average diameter than at the first day, the shaken nanofluid gives the same value, i.e. no further aggregation was detected.

Bottom Line: Different dispersion techniques were considered in this study, including sonication, ball milling and high-pressure homogenization.Both the dispersion process and the use of some dispersants were investigated as a function of the nanoparticle concentration.The high-pressure homogenization was found to be the best method, and the addition of n-dodecyl sulphate and polyethylene glycol as dispersants, respectively in SWCNHs-water and TiO2-water nanofluids, improved the nanofluid stability.

View Article: PubMed Central - HTML - PubMed

Affiliation: Consiglio Nazionale delle Ricerche, Istituto per le Tecnologie della Costruzione, Corso Stati Uniti, I-35127 Padova, Italy. sergio.bobbo@itc.cnr.it.

ABSTRACT
In the recent years, great interest has been devoted to the unique properties of nanofluids. The dispersion process and the nanoparticle suspension stability have been found to be critical points in the development of these new fluids. For this reason, an experimental study on the stability of water-based dispersions containing different nanoparticles, i.e. single wall carbon nanohorns (SWCNHs), titanium dioxide (TiO2) and copper oxide (CuO), has been developed in this study. The aim of this study is to provide stable nanofluids for selecting suitable fluids with enhanced thermal characteristics. Different dispersion techniques were considered in this study, including sonication, ball milling and high-pressure homogenization. Both the dispersion process and the use of some dispersants were investigated as a function of the nanoparticle concentration. The high-pressure homogenization was found to be the best method, and the addition of n-dodecyl sulphate and polyethylene glycol as dispersants, respectively in SWCNHs-water and TiO2-water nanofluids, improved the nanofluid stability.

No MeSH data available.