  Concentrating solar power, particularly parabolic trough system with solar
concentrations less than 50, requires spectrally selective solar absorbers that
are thermally stable at high temperatures of 400degC above to achieve high
efficiency. In this work, the solar-thermal performance of a selective
multilayer metafilm absorber is characterized along with a black absorber for
comparison by a lab-scale experimental setup that measures the steady-state
absorber temperature under multiple solar concentrations. Heat transfer
analysis is employed to elucidate different heat transfer modes and validate
the solar-thermal experiment. Due to the superior spectral selectivity and
excellent thermal stability, the metafilm absorber deposited on the
cost-effective stainless steel foil could achieve the solar-thermal efficiency
57% at a steady-state temperature of 371degC under 10 suns during the lab-scale
experiment with losses, while a highest efficiency of 83% was projected under
the same conditions for practical solar thermal applications. The results here
will facilitate the research and development of novel solar materials for
high-efficiency solar thermal energy conversion.
