Measured (solid symbols) and predicted (solid lines) el

Investigation of the electrical conductivity of propylene glycol-based ZnO nanofluids. White SB, Shih AJ, Pipe KP - Nanoscale Res Lett (2011) Bottom Line: Electrical conductivity is an important property for technological applications of nanofluids that has not been widely studied.Conventional descriptions such as the Maxwell model do not account for surface charge effects that play an important role in electrical conductivity, particularly at higher nanoparticle volume fractions.These experimental trends are shown to be consistent with an electrical conductivity model previously developed for colloidal suspensions in salt-free media. View Article: PubMed Central - HTML - PubMed Affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109-2125, USA. sbwhite@umich.edu. ABSTRACT Electrical conductivity is an important property for technological applications of nanofluids that has not been widely studied. Conventional descriptions such as the Maxwell model do not account for surface charge effects that play an important role in electrical conductivity, particularly at higher nanoparticle volume fractions. Here, we perform electrical characterizations of propylene glycol-based ZnO nanofluids with volume fractions as high as 7%, measuring up to a 100-fold increase in electrical conductivity over the base fluid. We observe a large increase in electrical conductivity with increasing volume fraction and decreasing particle size as well as a leveling off of the increase at high volume fractions. These experimental trends are shown to be consistent with an electrical conductivity model previously developed for colloidal suspensions in salt-free media. In particular, the leveling off of electrical conductivity at high volume fractions, which we attribute to counter-ion condensation, represents a significant departure from the "linear fit" models previously used to describe the electrical conductivity of nanofluids. No MeSH data available. Related in: MedlinePlus	© Copyright Policy - open-access Related In: Results - Collection License Show All Figures getmorefigures.php?uid=PMC3211435&req=5 Figure 2: Measured (solid symbols) and predicted (solid lines) electrical conductivity of propylene glycol-based ZnO nanofluids with 20-, 40-, and 60-nm diameter particles. Predicted values are based on the colloidal salt-free suspension model given in Equations 3 and 4. A linear fit model (i.e., one which only assumes Case 1 and neglects counter-ion condensation effects) is also shown in dotted lines. Mentions: As shown in Figure 2, increasing the volume fraction by adding nanoparticles significantly increased the electrical conductivity with respect to that of the PG base fluid (K = 0.1 μS/cm). As predicted by Equations 3 and 4, smaller particles yielded a higher electrical conductivity at the same volume fraction. The electrical conductivity of the 20-nm particle suspension reached 9.60 μS/cm at 7% volume fraction, representing a nearly 100-fold increase over the base fluid.

Investigation of the electrical conductivity of propylene glycol-based ZnO nanofluids.

White SB, Shih AJ, Pipe KP - Nanoscale Res Lett (2011)

Bottom Line: Electrical conductivity is an important property for technological applications of nanofluids that has not been widely studied.Conventional descriptions such as the Maxwell model do not account for surface charge effects that play an important role in electrical conductivity, particularly at higher nanoparticle volume fractions.These experimental trends are shown to be consistent with an electrical conductivity model previously developed for colloidal suspensions in salt-free media.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109-2125, USA. sbwhite@umich.edu.

ABSTRACT

Electrical conductivity is an important property for technological applications of nanofluids that has not been widely studied. Conventional descriptions such as the Maxwell model do not account for surface charge effects that play an important role in electrical conductivity, particularly at higher nanoparticle volume fractions. Here, we perform electrical characterizations of propylene glycol-based ZnO nanofluids with volume fractions as high as 7%, measuring up to a 100-fold increase in electrical conductivity over the base fluid. We observe a large increase in electrical conductivity with increasing volume fraction and decreasing particle size as well as a leveling off of the increase at high volume fractions. These experimental trends are shown to be consistent with an electrical conductivity model previously developed for colloidal suspensions in salt-free media. In particular, the leveling off of electrical conductivity at high volume fractions, which we attribute to counter-ion condensation, represents a significant departure from the "linear fit" models previously used to describe the electrical conductivity of nanofluids.

No MeSH data available.

Related in: MedlinePlus

Measured (solid symbols) and predicted (solid lines) electrical conductivity of propylene glycol-based ZnO nanofluids with 20-, 40-, and 60-nm diameter particles. Predicted values are based on the colloidal salt-free suspension model given in Equations 3 and 4. A linear fit model (i.e., one which only assumes Case 1 and neglects counter-ion condensation effects) is also shown in dotted lines.

Related In: Results - Collection

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Figure 2: Measured (solid symbols) and predicted (solid lines) electrical conductivity of propylene glycol-based ZnO nanofluids with 20-, 40-, and 60-nm diameter particles. Predicted values are based on the colloidal salt-free suspension model given in Equations 3 and 4. A linear fit model (i.e., one which only assumes Case 1 and neglects counter-ion condensation effects) is also shown in dotted lines.

Mentions: As shown in Figure 2, increasing the volume fraction by adding nanoparticles significantly increased the electrical conductivity with respect to that of the PG base fluid (K = 0.1 μS/cm). As predicted by Equations 3 and 4, smaller particles yielded a higher electrical conductivity at the same volume fraction. The electrical conductivity of the 20-nm particle suspension reached 9.60 μS/cm at 7% volume fraction, representing a nearly 100-fold increase over the base fluid.