Thermally driven convection in Li||Bi liquid metal batteries

Abstract

Liquid Metal Batteries (LMBs) are a promising concept for cheap electrical energy storage at grid level. These are built as a stable density stratification of three liquid layers, with two liquid metals separated by a molten salt. In order to ensure a safe and efficient operation, the understanding of transport phenomena in LMBs is essential. With this motivation we study thermal convection induced by internal heat generation. We consider the electrochemical nature of the cell in order to define the heat balance and the operating parameters. Moreover we develop a simple 1D heat conduction model as well as a fully 3D thermo-fluid dynamics model. The latter is implemented in the CFD library OpenFOAM, extending the volume of fluid solver, and validated against a pseudo-spectral code. Both models are used to study a rectangular 10×10 cm Li||Bi LMB cell at three different states of charge.

Modeling discontinuous potential distributions using the finite volume method, and application to liquid metal batteries

“…Specifically, we would like to extend the model by convection [18,19], heat transfer [73,77] and electrode kinetics.…”

Efficient mixing by swirling electrovortex flows in liquid metal batteries

“…Previous studies on thermal convection in LMBs (Shen & Zikanov 2016; Köllner, Boeck & Schumacher 2017; Personnettaz et al. 2018) suggest that the bottom alloy layer is in stable thermal stratification and that it is only weakly entrained by viscosity. Shen & Zikanov (2016) and Personnettaz et al.…”

“…Shen & Zikanov (2016) and Personnettaz et al. (2018) both report velocities in the alloy that are below in a centimetre-scale device. This is likely not enough to both oppose solutal buoyancy and enhance mixing during discharge.…”

Magneto-hydrodynamics of multi-phase flows in heterogeneous systems with large property gradients

“…The thermal-fluid dynamics of a multi-phase mixture is fully described by the fluid velocity, pressure, chemical species fraction and temperature fields through the conservation laws for linear momentum, composition and energy transport. This results in the following one-fluid formulation of the Navier–Stokes equation for the fluid velocity, for more details see 22 , 47 , 48 : where is the velocity, is the mass density, P is the fluid pressure, and is the viscous stress tensor and is given by, …”