Heat Transfer Characteristics of Magneto-thermal Convection And Its Visualization with Thermosensitive Liquid Crystal

Abstract

We developed an original observation system and measurement equipment of the Raleigh-Benard model (aspect ratio 2.17) in a solenoidal superconducting magnet to visualize magneto-thermal convection in situ from the side view. The working fluid of convection was an aqueous gadolinium nitrate solution of 0.15 mol/kg (paramagnetic substance), and the isothermal contour of convection was visualized by the addition of thermosensitive liquid crystal (TLC). We succeeded in visualizing the horizontal isothermal illuminant of TLC,which revealed the realization of a quasi-weightless condition in the Raleigh-Benard model. The volume of heat transfer in this system was measured, and then the Rayleigh number (Ra) and Nusselt number (Nu) were experimentally determined. We identified that the heat transfer on convection was enhanced by the downward magnetic force and suppressed by the upward magnetic force, as compared with Raleigh-Benard convection.