MHD sloshing instability in liquid metal batteries


MHD sloshing instability in liquid metal batteries

Horstmann, G. M.; Weber, N.; Weier, T.

Liquid metal batteries (LMBs) are discussed today as a cheap grid scale energy storage, as required for the deployment of fluctuating renewable energies. LMBs incorporate stratified three-layer fluid systems consisting of two liquid metal electrodes separated by a thin molten salt electrolyte. Due to the high electrical conductivities of the liquid metals, LMBs are highly susceptible for becoming unstable by MHD interactions of magnetic fields induced by internal and external currents. Besides the Tayler instability and the electrovortex instability, the so-called sloshing instability, also known as the metal pad roll instability in aluminum reduction cells, was identified as a key instability mechanism capable to cause short-circuits. Dimensionless stability parameters derived from inviscid two-layer systems can predict the onsets for sloshing and short-circuits with some success for a limited parameter range, but the two-layer description is far from perfect. To quantify the two-layer limitations, a three-layer dispersion relation was derived and deviations from the two-layer system were discussed. On this basis it is planned to extract three-layer stability criteria additionally including viscous damping to predict instability onsets in direct dependence of the geometrical parameters and material properties of LMBs. Further to this, three-layer experiments are under development aiming to measure the interaction and stability of interfacial waves using Doppler Ultrasound Velocimetry (DOP) and Magnetic Field Tomography (MFT) for checking the validity of different stability criteria.

Keywords: MHD; Sloshing; Liquid Metal Battery

  • Poster
    MHD Days 2016, 30.11.-02.12.2016, Göttingen, Deutschland

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Publ.-Id: 24402