Nanofluid optical property characterization: towards efficient direct absorption solar collectors

Robert A. Taylor, Patrick Phelan, Todd P. Otanicar, Ronald Adrian, Ravi Prasher

Research output: Contribution to journalArticle

314 Citations (Scopus)

Abstract

Suspensions of nanoparticles (i.e., particles with diameters < 100 nm) in liquids, termed nanofluids, show remarkable thermal and optical property changes from the base liquid at low particle loadings. Recent studies also indicate that selected nanofluids may improve the efficiency of direct absorption solar thermal collectors. To determine the effectiveness of nanofluids in solar applications, their ability to convert light energy to thermal energy must be known. That is, their absorption of the solar spectrum must be established. Accordingly, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (0.25 to 2.5 μm). A simple addition of the base fluid and nanoparticle extinction coefficients is applied as an approximation of the effective nanofluid extinction coefficient. Comparisons with measured extinction coefficients reveal that the approximation works well with water-based nanofluids containing graphite nanoparticles but less well with metallic nanoparticles and/or oil-based fluids. For the materials used in this study, over 95% of incoming sunlight can be absorbed (in a nanofluid thickness ≥10 cm) with extremely low nanoparticle volume fractions - less than 1 × 10-5, or 10 parts per million. Thus, nanofluids could be used to absorb sunlight with a negligible amount of viscosity and/or density (read: pumping power) increase.

Original languageEnglish (US)
JournalNanoscale Research Letters
Volume6
Issue number1
DOIs
StatePublished - Jan 2011

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solar collectors
Solar collectors
Optical properties
Nanoparticles
optical properties
extinction
nanoparticles
sunlight
coefficients
Fluids
Graphite
solar spectra
fluids
solar energy
Liquids
liquids
Thermal energy
approximation
thermal energy
accumulators

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Nanofluid optical property characterization : towards efficient direct absorption solar collectors. / Taylor, Robert A.; Phelan, Patrick; Otanicar, Todd P.; Adrian, Ronald; Prasher, Ravi.

In: Nanoscale Research Letters, Vol. 6, No. 1, 01.2011.

Research output: Contribution to journalArticle

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