Thermal cycling test of solid particles to be used in concentrating solar power plants

Abstract

Durability and reliability of solid particles to be used in concentrating solar power tower plants is crucial for the project viability. Solid particles materials to be implemented in concentrating solar power plants are thermal aged and thermal cycled in this study to evaluation of solid particles at high temperatures. A homemade device has been developed to perform accelerated-durability tests, that allows emulation of thermal cycling stress from days to years, and even evaluate the 11,000 cycles expected to be reached during 20 years' plant's lifetime in less than four months. A detailed description of the operation of this device is included in this paper. In addition, current solar absorptance, chemical composition, physical properties, thermal characteristics, and morphologic analysis of the samples before and after thermal treatments have been performed. The materials under the study are the most reliable solid particles reported in CSP field: silicon carbide (SiC) and CarboHSP® 30/60. Characterization results show that SiC is more affected on its durability by thermal cycling than by constant temperature aging treatment while CarboHSP® is affected by temperature aging rather than thermal cycling. SiC reacts with oxygen to form SiO2 on the surface, with a positive effect in its solar absorptance. Nevertheless, with thermal cycles, SiC particle surface becomes damaged and the reaction continues with more new exposed surface. Meanwhile, CarboHSP® reduces its solar absorptance with high temperature only due to changes in its surface chemical composition. However, thermal cycling shows no negative effect in CarboHSP® properties.