Testing and Modeling Thermosyphonic Closed-Loop Magnetohydrodynamic Electrolyte Flow

摘要

An experimental and analytical study is presented of thermosyphonic magnetohydrodynamic (MHD) flow of electrolyte solutions using permanent magnets to produce the magnetic field. For this purpose, a thermosyphonic closed loop MHD flow system is built and tested. The heated upper and cooled lower parts of the loop are constructed from copper pipe coated with varnish on the inside surface. The middle region is made from Plexiglas~(~R) vertical pipes, with copper electrodes placed opposite to each other on the inside, and a transverse magnetic field applied by a set of permanent magnets. Measurements of the induced flow rate and open circuit voltage are reported as a function of driving temperature difference and magnetic field strength. An analytical one-dimensional model of the flow is used to predict the output voltage and flow bulk velocity. The model is extended to account for the electrode design and the Hall effect pertinent to electrolyte solutions. The developed model has captured the important physical and electrical characteristics of the flow and compares well with experimental data. The work has resulted in evaluating the Hall parameter (ωτ) of electrolytic solutions, as a function of temperature and electrical conductivity of the fluid. It is found that (ωτ) can be as large as 100 for electrolytes and causes a significant loss in power output at the electrodes.