A conceptual study of a liquid metal alloy in a disk-shaped magnetohydrodynamics conversion system

Abstract

The use of solar-heated liquid metal in a magnetohydrodynamics (MHD) generator provides an alternative and direct conversion method for electric power generation. This prompted the present study to conduct a three-dimensional numerical analysis for a liquid Ga68In20Sn12 flow exposed to several uniform magnetic field intensities (Bo of 0.5 T, 1T and, 1.41 T) within a disk channel geometric boundary. The aim is to study the influence of the external magnetic fields on the generator performance and the fluid flow stability at a high Reynolds number (Re) and Hartmann number (Ha) using the Ansys Fluent software. The simulation results show that at Re of ≈ 2.44e6, the fluid velocity decreases inside the generator regardless of Bo. When Bo of 1T and 1.41T are applied, the velocity magnitude decreases and spreads within the disk channel and walls due to high Ha values (5874 and 8282). The fluid pressure increases from the nozzle pipe inlet to the disk channel and decreases towards the outlet. The induced current density in the radial direction, jx, increases within the disk channel and near the inner electrode edge as Bo increases. A significant observation is that the current densities obtained for Bo of 1T and 1.41T cases are higher than in other cases. The numerical analysis obtained in this study showed that the Bo of either 1T or 1.41T is needed to achieve the required flow stability, current density, and output powers.