Thermodynamic analysis on medium-high temperature solar thermal systems with selective coatings

Thermodynamics analysis was carried out for solar thermal receivers with different selective coatings. The relation between the energy conversion efficiency of a medium-high temperature solar thermal system, the spectral properties of selective coating and the operating temperature of the receiver were discussed. Furthermore, the relation between the optimum operating temperatures, the exergy efficiencies and the incident solar flux were analyzed for the traditional concentrating system and concentrating beam splitting system, respectively. According to the analysis results for the thermal receiver with blackbody surface and selective coatings, the optimum cutoff wavelength was obtained for the ideal selective coating. An analysis method for the optimum operating temperature calculation was developed for thermal receivers with selective coating. The optimum operating temperature for an actual selective coating was analyzed on the basis of the proposed theory.