Efficiency enhancement of complex thermal energy storages under multiple transient loads
Abstract
This paper presents a numerical investigation and performance optimization of a large-scale, stratified thermal energy storage system integrated into a public research building. The system combines multiple renewable heat sources — including solar thermal collectors and a photovoltaic-powered power-to-heat unit — with various thermal heating loads. The methodology integrates both simultaneous and sequential building energy demand and generation modeling with transient CFD simulations in OpenFOAM® to analyze internal mixing and thermocline dynamics. A generally applicable performance evaluation is based on the internal temperature distribution, the temporal evolution of temperature gradients, Reynolds and Richardson number under various operating scenarios. Results confirm that carefully matched inlet temperatures and injection heights significantly enhance stratification stability. The best performance was observed during summer operation with reduced charging temperatures to better fit stratification levels while maintaining thermal power, and during winter with increased temperatures at reduced volumetric flow rates. These adjustments result in thermoclines up to 22% thinner during summer and up to 42% thinner during winter compared to sequential operation.
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| Titel | Efficiency enhancement of complex thermal energy storages under multiple transient loads |
|---|---|
| Medien | Journal of Energy Storage |
| Band | 175 |
| Verfasser | Robin Fick, Prof. Dr. Robert Honke, Dieter Brüggemann |
| Seiten | 123110 |
| Veröffentlichungsdatum | 23.06.2026 |
| Projekttitel | OUR-E |
| Zitation | Fick, Robin; Honke, Robert; Brüggemann, Dieter (2026): Efficiency enhancement of complex thermal energy storages under multiple transient loads. Journal of Energy Storage 175, 123110. DOI: 10.1016/j.est.2026.123110 |