Spectrally Selective Solar Absorbers with High-temperature Insensitivity

TL;DR

This paper presents multilayer tungsten, silica, and alumina solar absorbers that maintain high efficiency and spectral selectivity at temperatures exceeding 600°C, suitable for high-temperature solar thermal applications.

Contribution

It introduces spectrally selective, thermally stable solar absorbers that are angular insensitive and polarization-independent, demonstrating high performance at elevated temperatures.

Findings

Achieved 88.1% absorptance at solar wavelengths

Maintained high absorption over 600°C after annealing

Enabled effective operation in high-concentration CSP systems

Abstract

It is of significance to incorporate spectral selectivity technology into solar thermal engineering, especially at high operational temperatures. This work demonstrates spectrally selective solar absorbers made of multilayer tungsten, silica, and alumina thin films that are angular insensitive and polarization-independent. An overall absorptance of 88.1% at solar irradiance wavelength, a low emittance of 7.0% at infrared thermal wavelength, and a high solar to heat efficiency of 79.9% are identified. Additionally, it shows the annealed samples maintain an extremely high absorption in solar radiation regime over at least 600 C and the solar absorbers after thermal annealing at 800 C still work well in a CSP system with an even high concentration factor of over 100.