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.

Highlights

  • In the past decades, electrically conducting fluid such as liquid metal under externally applied magnetic field has become the subject of various engineering and industrial applications

  • This study has investigated the flow of liquid Ga68In20Sn12 in a disk-shaped MHD channel under different cases of B0

  • (1.) At high Reynolds number (Re), the fluid velocity decreases along the nozzle pipe and disk channel regardless of B0

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Summary

Introduction

Electrically conducting fluid such as liquid metal under externally applied magnetic field has become the subject of various engineering and industrial applications. Zhang et al [13] experimentally investigated the liquid Galinstan (Ga 68 %, In 20 %, and Sn 12 %) based mini channel cooling for high heat flux thermal devices Their results showed that liquid Galinstan driven by a high-efficiency direct current electromagnetic pump (DC-EMP) dissipate heat with a heat flux of 300 W/cm, heat power of 1500 W, and a pressure of 100 kPa. Taheri et al [14] use a numerical finite volume method (FVM) and artificial neural network (ANN) to compute the flow at the entrance length of a laminar MHD rectangular channel at different values of the Reynolds numbers, Re, (600 < Re < 1100) and Ha (4 < Ha < 10).

Liquid Galinstan flow cycle
Disk MHD generator geometry and material properties
Governing equations
The three-dimensional modelling of the disk MHD generator
Disk MHD generator modelling results
Pressure gradient
Current density
Literature Present study
Findings
Conclusion
Full Text
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