Advancing sensible heat storage: A novel transient heat transfer model for concrete-based TES modules for CSP applications

Concentrating solar power (CSP) plays a crucial role in renewable energy systems, offering high-temperature heat for electricity generation and industrial processes while supporting the transition to sustainable energy. Thermal energy storage (TES) improves the reliability and dispatchability of CSP systems. Among the sensible heat storage options, concrete emerges as a cost-effective and eco-friendly alternative that warrants further investigation. This study introduces a comprehensive mathematical model for simulating the transient thermal behaviour of concrete-based TES modules. The model accommodates diverse geometries, supports a wide range of heat transfer fluids (HTFs) in all flow regimes, and accounts for heat losses to the environment, factors that are often overlooked in prior research. The mathematical framework was incorporated into a software platform called OpenModelica and will later be included in a tool developed by the authors to evaluate the performance of CSP plants. Before this integration takes place, the model undergoes validation, which is the primary focus of this study. The model was validated through two case studies, one theoretical and the other experimental, each involving different operational conditions, geometries, HTFs, and materials. The theoretical case confirmed that the model could capture the key physical phenomena governing transient heat transfer in the storage module. A comparison between the simulation results and experimental data revealed a strong agreement in temperature, heat flow, and total energy transmitted, with temperature errors within the IEC 60751 standard and total energy transfer errors ranging from −6.15 % to +5.69 %. These findings highlight the potential of concrete-based TES to enhance the performance of CSP systems, contributing to reliable and sustainable energy solutions.