Experimental Results of Gradual Porosity Wire Mesh Absorber for Volumetric Receivers

Abstract

Concentrated Solar Power (CSP) market is focused in the cost reduction by means of increasing efficiencies and reducing the investment, installation and, operation and maintenance costs. In Concentrated Solar Power with Central Receiver (CR) technologies, one option for increasing efficiency is to raise the temperature of the working fluid. The CSP-CR technology working with volumetric air receiver shows a high potential to improve efficiencies by allowing higher operating temperatures (above the limit of commercial power tower plants). However, most of the different volumetric receivers tested during the last three decades did not match the predicted nominal conditions, working at lower efficiencies than expected. Other challenges still remain unsolved, like absorber durability, and the specific cost. In order to identify high-efficient configurations and geometries for the absorbers used as volumetric receivers, CIEMAT-PSA (funded by SOLGEMAC project) has developed a lab-scale test bed used for the evaluation of open volumetric receivers. The main goal of the installation is to identify different configurations and geometries that improve the thermal efficiency of the reference open-loop volumetric receivers: Phoebus-TSA for metallic materials and SOLAIR for ceramic ones. The initial tests of the installation are focused on characterized the TSA and the SOLAIR absorbers. Then, a comparison with the newer designs will be made in order to improve the reference absorbers. First results with the SOLAIR absorber made of recrystallized SiC with an open porosity of 49.5%, for a mean air outlet temperature varying from 266-to-623 °C, moves from 89-to-56% thermal efficiency. For the newer designs, CIEMAT-PSA has AISI 310 commercial wire meshes with different characteristics. The wire ranges from 0.13-to-1.00 mm, and the mesh size varies from 0.20-to-4.00 mm. With different combinations of the meshes, several prototypes will be analyzed.