Critical phenomena and their effect on thermal energy storage in supercritical fluids. (1st November 2017)

• Record Type: Journal Article
• Authors: Hobold, Gustavo M.; da Silva, Alexandre K.
• Is Part Of: Applied energy. Volume 205(2017)
• Page Start: 1447
• Page End: 1458
• Publication Date: 2017-11-01
• Subjects: Energy storage -- Energy density -- Supercritical fluid -- Thermal energy -- Critical phenomena; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2017.09.081
• Languages: English
• ISSNs: 0306-2619

Abstract

Highlights: High power thermal energy storage using supercritical fluids. Influence of property variation on energy and power density. Multi-fluid analysis and generalization for several storage temperatures. Cost, heat transfer and energy density evaluation for high temperature storage. Abstract: Large-scale implementation of concentrated solar power plants requires energy storage systems if fossil sources are to be fully replaced. While several candidates have appeared, most still face major issues such as cost, limited energy density and material compatibility. The present paper explores the influence of property variation in the proximity of the critical point on thermal energy storage using supercritical fluids (sTES) from thermodynamic and heat transfer standpoints. Influence of thermodynamic operational parameters on energy density of isobaric and isochoric sTES and their optima is discussed, showing that the energy density results from a competition between average specific heat and loaded density. Moreover, sTES is shown to be applicable to virtually any storage temperature, depending only on the fluid's critical point. Finally, a heat transfer and energy density comparison to other existing storage mechanisms is presented and supercritical water is shown to be competitive for high temperature thermal energy storage.