Investigation of in-plane heat distribution, thermal stability and mechanical properties of SS-(Fe3O4)/Ti/AlN/Ti/SiO2 as absorber coatings for efficient high temperature concentrated solar power systems

Abstract

Despite numerous achievements recorded so far in developing solar absorber coatings for photothermal applications, the study of the thermal stability in humid and cold environment remains very scarce and the underlaying physics behind the transfer of the absorbed energy to the working fluid has never been investigated. In this perspective, we developed Ti/AlN/Ti/SiO2 film as multilayer selective solar absorber coating (MSSAC) on Fe3O4 modified stainless steel substrate using Direct Current (DC)/Radio Frequency (RF) magnetron sputtering at room temperature. The coating exhibited solar absorptance of 0.969 and thermal emittance of 0.220 in the solar and infrared spectrum regions respectively. The MSSAC was found to be thermally stable up to 500 °C in air. Further increase in annealing temperature to 600 °C resulted to a slight decrease in solar absorptance from 0.969 to 0.953 and a small rise in the emittance value from 0.220 to 0.258. A high humidity test and rapid heating-cooling cycling (RHCC) test revealed the stability of this coating and its potential application in humid (90 mmHg) and cold (− 50 °C) environments. Additionally, the coating shows good adhesion strength even after humidity and RHCC tests. The in-plane heat distribution analysis using thermal infrared imaging camera illustrated that there is a good possible transfer of the absorbed heat to the working fluid due to high surface temperature exhibited by Ti/AlN/Ti/SiO2 coated modified stainless steel (SS) substrate than the other boundary conditions. Overall, these results indicate that the present coating has the potential application in both high temperature, humid and cold environments.