Solar thermal energy has shown remarkable growth in recent years — incorporating many new technologies into new applications . Nanofluids — suspensions of nanoparticles in conventional fluids — have shown promise to make efficient volumetric-absorption solar collectors [2–4]. It has also been shown that concentrated light energy can efficiently cause localized phase change in a nanofluid . These findings indicate that it may be advantageous to create a ‘direct, volumetric nanofluid steam generator’. That is, a solar collector design which could minimize the number of energy transfer steps, and thus minimize losses in converting sunlight (via thermal energy) to electricity. To study this, we use a testing apparatus where concentrated laser light at 532 nm — a wavelength very near the solar spectrum peak — is incident on a highly absorbing sample. The highly absorbing samples compared in this study are black dyes, black painted surfaces, and silver nanofluids — with de-ionized water as a base fluid. Each of these samples converts light energy to heat — to varying degrees — in a localized region. This region is monitored simultaneously with a digital camera and an infrared camera. The resulting observed temperature profile and bubble dynamics are compared for these fluids. For pure water with a black backing, some very high temperatures (>300 °C) are observed with a laser input of ∼75 W/cm2. Using a similar absorption potential, we observed higher temperatures in the nanofluids when compared to black dyes. A simplified boiling heat transfer analysis based on these results is also presented. We also noticed differences in bubble size and growth rates for the different samples. Overall, this study represents a proof-of-concept test for a novel volumetric, direct steam generator. These results of this test indicate that it may be possible to efficiently generate steam directly in a controlled, localized volume — i.e. without heating up passive system components.
- Advanced Energy Systems Division and Solar Energy Division
Characterization of a Nanofluid Volumetric Solar Absorber / Steam Generator
- Views Icon Views
- Share Icon Share
- Search Site
Taylor, RA, Phelan, P, Adrian, R, Gunawan, A, & Otanicar, T. "Characterization of a Nanofluid Volumetric Solar Absorber / Steam Generator." Proceedings of the ASME 2011 5th International Conference on Energy Sustainability. ASME 2011 5th International Conference on Energy Sustainability, Parts A, B, and C. Washington, DC, USA. August 7–10, 2011. pp. 1927-1936. ASME. https://doi.org/10.1115/ES2011-54062
Download citation file: