Thermodynamic analysis of a high temperature multi-layered sensible-latent thermal energy storage

The present work provides a thorough literature review of the main high temperature sensible and latent materials suitable for a multilayered thermal energy storage system to be integrated into innovative concentrated solar power applications. Furthermore, a thermodynamic comparative analysis of six different multilayered packed-bed thermal energy storage configurations, including three selected high-temperature metallic phase change materials (Al-12.2Si, Al-20Si, andCu-Si27-Mg17) is presented. For each multilayered storage configuration, the overall impact of the phase change material layer thickness on the performance has been analyzed. As expected, the major improvements are enabled by the addition of a high-temperature phase change material at the top of the multi-layered thermal energy storage. Indeed, the discharge phase duration could be extended for 2 hours, while the energy output increases by about 5%. Furthermore, the addition of a lower melting temperature phase change material layer below the topping high temperature one grants a further slight energy output enhancement. However, this seems to be not valuable enough when considering the increased level of complexity and costs induced by such a storage unit design. The study confirms that a larger amount of phase change materials leads to a lower discharge efficiency due to a wider temperature difference between the heat transfer fluid and the storing media during phase change. The performed study reveals that the Cu-17Mg-27Si/rock multilayered thermal energy storage is worth continuing exploring, especially in terms of experimental tests to assess possible corrosion issues and different encapsulation and coating solutions that might considerably affect the lifetime of the system. Technoeconomicanalyses should be also performed to assess the economic viability of the integration of multilayered TES systems in innovative concentrated solar power plant layouts.QC 20201216