Characterization of light-induced, volumetric steam generation in nanofluids

Robert A. Taylor, Patrick Phelan, Ronald Adrian, Andrey Gunawan, Todd P. Otanicar

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

Solar thermal energy has shown remarkable growth in recent years [1]. At the same time, research has shown that nanofluids - suspensions of nanoparticles in conventional fluids - can potentially enhance the efficiency of these solar thermal systems [2-7]. The fundamental advantage of this type of collector is that it can be designed to minimize the number of energy transfer steps, thereby reducing losses in converting sunlight (via thermal energy) to electricity. To investigate the inherent advantages of an optically tailored nanofluid system, we have experimentally tested the feasibility of volumetrically absorbing, direct steam collection mediums. In this study, we use a transparent testing apparatus where concentrated laser light at 532 nm (a wavelength very near the solar spectrum peak) is incident on optically absorbing mediums (samples). The samples compared in this study are black dyes, black painted surfaces, and nanofluids - with de-ionized water as a base fluid for each. Each of these converts laser light energy to heat in a localized region. The heated region is monitored with a digital camera and an infrared camera, simultaneously. Resulting temperature profiles and bubble dynamics are compared for the different samples. For pure water with a black backing, high temperatures (>300 °C) are observed with a laser input of ∼287 W/cm 2. For the same laser input, nanofluids show lower peak temperatures as compared to water with a black backing, but up to 50% more vapor generation. Vapor bubbles are seen to be larger in pure water as compared to nanofluids or black dyes. These results indicate volumetric absorbers (notably nanofluids) provide a more effective coupling between light energy and liquid-to-vapor phase change than surface absorbers. That is, our results indicate that a well-designed volumetric absorbing, direct steam nanofluid collector can potentially enhance the efficiency of the light-to-steam conversion in a solar thermal system.

Original languageEnglish (US)
Pages (from-to)1-11
Number of pages11
JournalInternational Journal of Thermal Sciences
Volume56
DOIs
StatePublished - Jun 2012

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steam
Steam
Lasers
backups
Vapors
Thermal energy
thermal energy
accumulators
water
lasers
Water
absorbers
bubbles
Dyes
dyes
vapors
Fluids
solar spectra
digital cameras
fluids

Keywords

  • Boiling
  • Energy
  • Energy conversion
  • Extinction
  • Heat transfer
  • Light
  • Nanofluid
  • Nanoparticle
  • Radiation
  • Solar
  • Thermal
  • Volumetric

ASJC Scopus subject areas

  • Engineering(all)
  • Condensed Matter Physics

Cite this

Characterization of light-induced, volumetric steam generation in nanofluids. / Taylor, Robert A.; Phelan, Patrick; Adrian, Ronald; Gunawan, Andrey; Otanicar, Todd P.

In: International Journal of Thermal Sciences, Vol. 56, 06.2012, p. 1-11.

Research output: Contribution to journalArticle

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