Abstract
The suitability of stainless steel 316L and Inconel 625 for use in a latent heat thermal energy storage (TES) system was investigated. A NaCl–NaF eutectic mixture with a melting temperature of 680 °C was used as the phase change material (PCM). Containers were filled with the PCM prior to heating to 750 °C, then examined after 100 and 2500 h of high-temperature exposure by analyzing the material surface and cross-section areas. A small amount of corrosion was present in both samples after 100 h. Neither sample suffered significant damage after 2500 h. The undesirable inter-granular grain boundary attack found in SS316L samples was in the order of 1–2 µm in depth. On Inconel 625 sample surface, an oxide complex formed, resisting material dissolution into the PCM. The surface morphology of tested samples remained largely unchanged after 2500 h, but the corrosion pattern changed from an initially localized corrosion penetration to a more uniform type. After 2500 h, the corrosion depth of Inconel 625 remained at roughly 1–2 µm, indicating that the corrosion rate decelerated. Both materials demonstrated good compatibility with the chosen NaF–NaCl eutectic salt, but the low corrosion activity in Inconel 625 samples shows a performance advantage for long term operation.
Highlights
One of the main challenges limiting the widespread implementation of solar and wind energies for grid-scale electricity generation is the transient nature of the renewable energy resources.One promising technology is solar thermal power generation because surplus solar radiation can be stored directly as thermal energy without costly conversion losses
The dissolution of the chemical elements of the vessel materials into the phase change material (PCM) can be better characterized by conducting a chemical analysis on the molten salt
The compatibility of stainless steel 316L and Inconel 625 to NaCl–NaF eutectic mixture was studied to determine the suitability for use in a latent heat thermal energy storage (TES) system
Summary
One of the main challenges limiting the widespread implementation of solar and wind energies for grid-scale electricity generation is the transient nature of the renewable energy resources. Thermal energy storage (TES) has been implemented at operational concentrating solar power (CSP) plants using the sensible heat of a large amount of molten salt [1,2,3]. Kuravi et al [2] provided a list of materials that are suitable for use in TES systems based on the type of PCM salt utilized and the operating temperatures. These materials include (but are not limited to) AISI 1015 carbon steel, AISI K01200, stainless steel. To be representative of a system, the test of the material samples was operated at operated at 750 °C
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
