RT Journal Article
T1 Thermo-economic optimization of a novel confined thermal energy storage system based on granular material
A1 Cano Pleite, Eduardo
A1 Hernández Jiménez, Fernando
A1 García Gutiérrez, Luis Miguel
A1 Soria Verdugo, Antonio
AB Concentrated solar power is a suitable technology for production of green electricity. However, to attain a uniform electricity production, concentrated solar power should be coupled with large Thermal Energy Storage (TES) systems. Among the different technologies of TES systems, storage of sensible heat in granular material is widely used due to its simple operation. These TES systems store energy as an increase of temperature of a large mass of small solid particles, through which a fluid circulates exchanging heat. TES systems are typically operated in a fixed bed regime, maximizing their exergy output, thus limiting the maximum allowable velocity of the fluid flow. In this work, a novel confined bed is proposed to mechanically prevent the motion of the solid particles conforming the TES system even for high fluid velocities, to guarantee that the exhaust temperature of the fluid is maximum during a discharge process. In this novel confined bed, a thermocline evolves from bottom to top of the system, separating the low and high temperature of the bed during the discharge process. An analytical model was applied to describe the evolution of the thermocline and the effect of the different operating parameters on the thermocline thickness.The effect of the thermocline thickness was combined with a thermo-economic analysis of a confined bed TES system proposed for a case of study. The new confined bed here proposed was optimized considering thermodynamics aspects, namely the fluid exergy increment in the bed, and economic factors, specifically the total investment cost of the TES system. The optimization resulted in low values of the fluid velocity, between 0.2 and 0.4 m/s, but still higher than the minimum fluidization velocity of sand particles of 750 mum, justifying the requirement of a confined bed, and low bed aspect ratios, between 0.25 and 0.9, to prevent excessively high fluid pressure drops. However, the bed aspect ratio increases significantly for higher granular material particle sizes, up to a ratio of bed height to diameter of 3 for a particle size of 10 mm and a TES demand time of 6 h.
PB Elsevier
SN 1359-4311
YR 2023
FD 2023-04-01
LK https://hdl.handle.net/10016/38895
UL https://hdl.handle.net/10016/38895
LA eng
NO This research was funded by the Spanish Government under the project STORESOL, reference number PID2019-109224RA-100. Eduardo Cano-Pleite also acknowledges support from the CONEX-Plus program funded by Universidad Carlos III de Madrid and the European Union's Horizon 2020 program under the Marie Sklodowska-Curie grant agreement No. 801538.
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RD 30 jun. 2024