Concentrated Solar Power (CSP) offers clean energy production using the abundance of solar irradiation and transforming it into thermal energy. State of the art CSP plants enable continuous energy generation by using thermal energy storage systems. For high operation temperatures and solar to electricity efficiency, a viable solution was developed employing solid particles as a heat transfer medium to operate a Brayton sCO₂ cycle .
In this innovative approach, solid particles transfer heat by falling onto the heat exchanger tubes containing supercritical CO₂. Such tubes are exposed to a complex load regime of erosion, which occurs at the interfaces of the external tube surface, coupled with oxidation. Secondly, creep is of concern, influenced by the supercritical CO₂ at the inner tube wall.
To comprehensively understand the atmospheric impact of CO₂ on the creep behavior of materials, four different high-strength, high-temperature applications were selected for testing. Among these alloys are Sanicro25, Inconel 617B, Inconel 740, and Haynes 282. Creep experiments were conducted over a wide range of loads in both laboratory air and industrial-grade CO₂ at 700°C. Samples were analyzed using optical microscopy and EPMA after rupture.
The results indicate that, under the test conditions, the creep behavior does not show a significant difference between air and industrial grade CO₂. However, small changes suggest a discernible difference between CO₂ and air environments. These differences are expected to become more pronounced at higher temperatures and longer exposure times, highlighting the need for long-term testing.
The degradation mechanisms are studied via their cross sections, enabling an in-depth analysis of the metal-atmosphere interaction under various environmental conditions at 700°C. This investigation enables a comprehensive understanding of how different factors contribute to potential damage in the proposed system.