Nanofluid optical property characterization: towards efficient direct absorption solar collectors
Robert A Taylor1, Patrick E Phelan, Todd P Otanicar
1Arizona State University, Tempe, AZ, USA. Rataylo2@asu.edu.
Nanoscale Research Letters
|June 30, 2011
Summary
Nanofluids efficiently absorb over 95% of solar energy with minimal nanoparticle concentration, offering a promising solution for solar thermal collectors without significantly increasing fluid viscosity or density.
Area of Science:
- Materials Science
- Renewable Energy
- Optical Physics
Background:
- Nanofluids, suspensions of nanoparticles (<100 nm) in liquids, exhibit altered thermal and optical properties.
- Nanofluids show potential for enhancing direct absorption solar thermal collector efficiency.
Purpose of the Study:
- To evaluate the light absorption capabilities of nanofluids for solar energy applications.
- To compare model predictions with spectroscopic measurements of extinction coefficients.
Main Methods:
- Spectroscopic measurements of extinction coefficients from 0.25 to 2.5 μm.
- Approximation of effective nanofluid extinction coefficient by summing base fluid and nanoparticle coefficients.
Main Results:
- The approximation method showed good agreement for water-based graphite nanofluids but less accuracy for metallic nanoparticles and oil-based fluids.
- Over 95% solar spectrum absorption achieved with nanofluid thickness ≥10 cm and low nanoparticle volume fractions (<1 × 10-5).
Conclusions:
- Nanofluids can effectively absorb solar radiation at very low concentrations.
- Potential for utilizing nanofluids in solar applications with negligible impact on fluid properties like viscosity and density.
