Performance improvement of CSP particle receivers by depositing spinel absorber coatings

Abstract

The challenging development/modification of particles to meet the requirements of thermal stability, high absorptance and mechanical resistance with minimal economical cost is a key point to attain for the next particle receivers of concentrated solar power plants. The properties of the particles influence the performance of the system, since the concentrated solar radiation is absorbed and stored in these solid materials. In this work, resulting from the studies carried out within the HORIZON 2020 COMPASsCO2 project, the deposition of black-coloured transition-metal oxides with spinel-like structure coatings on different particles is proven. Five different particles (state-of-the-art and innovative) developed by Saint-Gobain have been coated, studied and compared. The coating deposition was adapted to the dip-coating methodology, ensuring high and good reproducibility. The composition of solid particles as well as the composition of the precursor solution, the curing methodology and the number of deposited spinel layers demonstrate that they have a great influence on the solar absorptance value and the abrasion resistance. Therefore, it is essential to find the perfect balance between all these different parameters in order to achieve the best performance of the particles. The addition of silica nanoparticles in the precursor solution provides rougher layers with enhanced absorptance, up to 0.980, on newly developed particles with excellent thermal stability and abrasion resistance.