Contact

Dr. Norbert Weber
Magnetohydrodynamics
norbert.weberAthzdr.de
Phone: +49 351 260 3112

Dr. Tom Weier
Magnetohydrodynamics
t.weierAthzdr.de
Phone: +49 351 260 2226, +49 351 260 2013
Fax: +49 351 260 12226, +49 351 260 12013, +49 351 260 2007

Eye catcher

Electro-vortex flow

Electro-vortex flow may appear when currents converge or diverge inside a liquid conductor. It is a well known phenomenon in arc welding, vacuum arc remelting, aluminium electrolysis and electro slag remelting. In liquid metal batteries, electro-vortex flow will typically appear near the current collectors (fig. 1). It drives a flow away from the walls. Electro-vortex flow can be highly beneficial for enhancing mass transfer in liquid metal batteries. However, it should not be too strong in order to avoid a deformation of the electrolyte layer.

EWS Prinzip FMB EWS Experiment
Fig. 1: Sketch of electro-vortex flow in a liquid metal battery. Fig. 2: Experiment on electro-vortex flow.

The direction and magnitude of the electro-vortex flow can efficiently be controlled by the placement, conductivity and diameter of the feeding cables of the battery. At HZDR we optimise these parameters in order to increase mass transfer in the cathode of the cells. We conduct both experiments (fig. 2) as well as numerical simulation (fig. 3).

EVF lateral wire

Fig. 3: A lateral current supply will drive a horizontal electro-vortex flow in the cathode.

A recently developed solver for electro-vortex flow allows for computing the current distribution in the whole battery, including the feeding lines. In contrast to the experiments it allows exploring the influence of the Earth magnetic field, as well. If no vertical fields are present, the flow in the battery would be purely poloidal (fig. 4, left). However, already the very small Earth magnetic field leads to a helical or swirling flow (fig. 4, right).

EWS ohne Bz EWS mit Bz

Fig. 4: The Earth magnetic field transforms the original poloidal flow (left) into a helical flow (right).

Publications


Contact

Dr. Norbert Weber
Magnetohydrodynamics
norbert.weberAthzdr.de
Phone: +49 351 260 3112

Dr. Tom Weier
Magnetohydrodynamics
t.weierAthzdr.de
Phone: +49 351 260 2226, +49 351 260 2013
Fax: +49 351 260 12226, +49 351 260 12013, +49 351 260 2007