Radiative energy and exergy analyses of spectrally-selective surfaces for CSP systems

Abstract

This work presents a new methodology for calculations of spectral radiative energy and radiative exergy to evaluate the performances of concentrated solar power (CSP) systems. Spectral radiative properties and the operating temperature of selective surfaces, along with the temperature of the environment, are taken into account in analyses. The fundamental expressions needed for the spectral radiative energy and exergy analyses are introduced first. Then, the two approaches are used to assess the spectral performance of five selective coatings. The spectral analysis is performed in the wavelength range of 250 nm to 20,000 nm, while thermal analysis is carried out for the temperature range of 325 K to 800 K. NREL 6A coating was found to result in the highest radiative energy and radiative exergy for both efficiencies and gains, and for the best thermal stability compared to the other coatings.