Numerical study of encapsulated phase change material integration in structured thermal energy storage systems for concentrated solar power

The integration of encapsulated phase change materials (PCM) into structured thermocline thermal energy storage (TES) systems presents a promising solution for enhancing the performance of concentrating solar power (CSP) plants. This study investigates the effects of PCM layer thickness (PCM width), melting temperature gap, and cutoff temperature differences on energy accumulation for H380, KOH and NaNO3 as PCMs. A comprehensive one-dimensional and unsteady numerical model, validated against experimental data and used to simulate various configurations, was developed. The results indicate that an optimal PCM layer thickness of 5–10% of the bed height, combined with low cutoff temperature differences (10–20 °C), significantly enhances energy storage efficiency. For most cases, the optimal melting temperature is found to be 5 °C below the cutoff temperature difference from the hot/cold temperature. Maximum energy increases of 45.69% for KOH, 41.71% for NaNO3, and 36.88% for H380 were achieved at low cutoff temperature differences (10 °C) compared to a reference case without PCM. • One-dimensional model for numerical simulation. • NaNO3, KOH and H380 studied as a phase change material. • PCM layer width as a percentage of bed height studied. • Cutoff temperature difference for each PCM layer width studied. • Melting temperature distance from hot/cold temperatures studied.