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Stability and rheology of dilute TiO2-water nanofluids.

Penkavova V, Tihon J, Wein O - Nanoscale Res Lett (2011)

Bottom Line: In this study, a series of dilute TiO2 aqueous dispersions were prepared and tested for the possible presence of the AWS effect by means of a novel viscometric technique.The resulting stable nanofluid samples were dilute, below 0.7 vol.%.No case of important slip contribution was detected: the Navier slip coefficient of approximately 2 mm Pa-1 s-1 would affect the apparent fluidity data in a 100-μm gap by less than 1%.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, Rozvojova 135, 165 02 Prague 6, Czech Republic. wein@icpf.cas.cz.

ABSTRACT
The apparent wall slip (AWS) effect, accompanying the flow of colloidal dispersions in confined geometries, can be an important factor for the applications of nanofluids in heat transfer and microfluidics. In this study, a series of dilute TiO2 aqueous dispersions were prepared and tested for the possible presence of the AWS effect by means of a novel viscometric technique. The nanofluids, prepared from TiO2 rutile or anatase nanopowders by ultrasonic dispersing in water, were stabilized by adjusting the pH to the maximum zeta potential. The resulting stable nanofluid samples were dilute, below 0.7 vol.%. All the samples manifest Newtonian behavior with the fluidities almost unaffected by the presence of the dispersed phase. No case of important slip contribution was detected: the Navier slip coefficient of approximately 2 mm Pa-1 s-1 would affect the apparent fluidity data in a 100-μm gap by less than 1%.

No MeSH data available.


Related in: MedlinePlus

Examples of SEM images of dried samples. The representative photographs were selected for each tested sample. In contrast to the samples (a, b), the samples (c, d) contain a major part of the nanopowder in the form of fine particles. In addition, the long-time ultrasonification, see sample (d), breaks-up the remaining clusters apparent in sample (c). The specification of A3 nanopowder is given in Table 1.
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Figure 6: Examples of SEM images of dried samples. The representative photographs were selected for each tested sample. In contrast to the samples (a, b), the samples (c, d) contain a major part of the nanopowder in the form of fine particles. In addition, the long-time ultrasonification, see sample (d), breaks-up the remaining clusters apparent in sample (c). The specification of A3 nanopowder is given in Table 1.

Mentions: The series of images in Figure 6 illustrates the influence of the dispersion procedure and base solution on the texture of several dispersions of the nanopowder A3. The photographs were obtained using the SEM imaging technique (Cameca SX100), applied to the samples of the dried drops. In conclusion, the particles of the nanopowder A3 were better dispersed in the acidic solution than in the neutral or alkaline one (compare Figure 6a, b, c). The clusters remaining in the acid dispersion were broken up during the ultrasonic treatment (compare Figure 6c, d).


Stability and rheology of dilute TiO2-water nanofluids.

Penkavova V, Tihon J, Wein O - Nanoscale Res Lett (2011)

Examples of SEM images of dried samples. The representative photographs were selected for each tested sample. In contrast to the samples (a, b), the samples (c, d) contain a major part of the nanopowder in the form of fine particles. In addition, the long-time ultrasonification, see sample (d), breaks-up the remaining clusters apparent in sample (c). The specification of A3 nanopowder is given in Table 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211337&req=5

Figure 6: Examples of SEM images of dried samples. The representative photographs were selected for each tested sample. In contrast to the samples (a, b), the samples (c, d) contain a major part of the nanopowder in the form of fine particles. In addition, the long-time ultrasonification, see sample (d), breaks-up the remaining clusters apparent in sample (c). The specification of A3 nanopowder is given in Table 1.
Mentions: The series of images in Figure 6 illustrates the influence of the dispersion procedure and base solution on the texture of several dispersions of the nanopowder A3. The photographs were obtained using the SEM imaging technique (Cameca SX100), applied to the samples of the dried drops. In conclusion, the particles of the nanopowder A3 were better dispersed in the acidic solution than in the neutral or alkaline one (compare Figure 6a, b, c). The clusters remaining in the acid dispersion were broken up during the ultrasonic treatment (compare Figure 6c, d).

Bottom Line: In this study, a series of dilute TiO2 aqueous dispersions were prepared and tested for the possible presence of the AWS effect by means of a novel viscometric technique.The resulting stable nanofluid samples were dilute, below 0.7 vol.%.No case of important slip contribution was detected: the Navier slip coefficient of approximately 2 mm Pa-1 s-1 would affect the apparent fluidity data in a 100-μm gap by less than 1%.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, Rozvojova 135, 165 02 Prague 6, Czech Republic. wein@icpf.cas.cz.

ABSTRACT
The apparent wall slip (AWS) effect, accompanying the flow of colloidal dispersions in confined geometries, can be an important factor for the applications of nanofluids in heat transfer and microfluidics. In this study, a series of dilute TiO2 aqueous dispersions were prepared and tested for the possible presence of the AWS effect by means of a novel viscometric technique. The nanofluids, prepared from TiO2 rutile or anatase nanopowders by ultrasonic dispersing in water, were stabilized by adjusting the pH to the maximum zeta potential. The resulting stable nanofluid samples were dilute, below 0.7 vol.%. All the samples manifest Newtonian behavior with the fluidities almost unaffected by the presence of the dispersed phase. No case of important slip contribution was detected: the Navier slip coefficient of approximately 2 mm Pa-1 s-1 would affect the apparent fluidity data in a 100-μm gap by less than 1%.

No MeSH data available.


Related in: MedlinePlus