Experimental discharge analysis of a high-temperature thermal energy storage system made of alumina blocks

Thermal energy storage (TES) systems working at very high temperatures play a crucial role in the development of more efficient solar thermal power plants. Sensible heat storage in solids is the most mature TES technology. This work presents a novel lab-scale TES system made of stacked alumina blocks, which resist high temperature and thermal shock. The alumina blocks are perforated by hexagonal channels arranged as a honeycomb. With initial temperatures as high as 800 ° C , discharge tests are conducted for different flow rates of compressed air. Discharge times range from 2 h 1 min (at 480 L/min) to 5 h 9 min (at 120 L/min). Experimental data show the temperature segregation throughout the storage media. The system pressure drops are very low, with the highest measured being 224 Pa, at 1200 L/min. Measurements are compared with results from a 1D transient model, which tends to slightly underestimate the air temperature. The lab-scale experiments demonstrate the feasibility of the alumina TES system for integration into dispatchable high-temperature Concentrated Solar Power plants. • Lab-scale sensible heat storage system based on solid blocks. • New alumina block with honeycomb hexagonal air channels. • Discharge tests conducted at temperatures up to 800 ° C. • Experimental measurements show temperature segregation and reduced pressure drop. • Application to dispatchable and cost-effective concentrated solar thermal plants.