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Numerical Investigations of a Counter-Current Moving Bed Reactor for Thermochemical Energy Storage at High Temperatures

1
Institute of Engineering Thermodynamics, DLR, Linder Höhe, 51147 Köln, Germany
2
Institute of Engineering Thermodynamics, DLR, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany
*
Author to whom correspondence should be addressed.
Energies 2020, 13(3), 772; https://doi.org/10.3390/en13030772
Received: 27 January 2020 / Revised: 4 February 2020 / Accepted: 5 February 2020 / Published: 10 February 2020
(This article belongs to the Section Energy Storage and Application)
High temperature storage is a key factor for compensating the fluctuating energy supply of solar thermal power plants, and thus enables renewable base load power. In thermochemical energy storage, the thermal energy is stored as the reaction enthalpy of a chemically reversible gas-solid reaction. Metal oxides are suitable candidates for thermochemical energy storage for solar thermal power plants, due to their high reaction temperatures and use of oxygen as a gaseous reaction partner. However, it is crucial to extract both sensible and thermochemical energy at these elevated temperatures to boost the overall system efficiency. Therefore, this study focuses on the combined extraction of thermochemical and sensible energy from a metal oxide and its effects on thermal power and energy density during discharging. A counter-current moving bed, based on manganese-iron-oxide, was investigated with a transient, one-dimensional model using the finite element method. A nearly isothermal temperature distribution along the bed height was formed, as long as the gas flow did not exceed a tipping point. A maximal energy density of 933 kJ/kg was achieved, when ( Mn , Fe ) 3 O 4 was oxidized and cooled from 1050 ° C to 300 ° C . However, reaction kinetics can limit the thermal power and energy density. To avoid this drawback, a moving bed reactor based on the investigated manganese-iron oxide should combine direct and indirect heat transfer to overcome kinetic limitations. View Full-Text
Keywords: moving bed; thermochemical energy storage; redox reaction moving bed; thermochemical energy storage; redox reaction
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MDPI and ACS Style

Preisner, N.C.; Bürger, I.; Wokon, M.; Linder, M. Numerical Investigations of a Counter-Current Moving Bed Reactor for Thermochemical Energy Storage at High Temperatures. Energies 2020, 13, 772.

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