SINGLE AND TWO-PHASE LIQUID METAL HEAT TRANSFER UNDER THE INFLUENCE OF A MAGNETIC FIELD

The results of an experimental and theoretical investigation on the effect of a magnetic field on natural convection, nucleate boiling and film boiling are presented. A vertical stainless steel reflux boiler, with a horizontal boiling surface, was operated in a horizontal magnetic field. The test fluid was quadruple distilled mercury and in another series mercury plus 10 ppm titanium and 200 ppm magnesium. Data were obtained at the saturated pressures of 0.0066, 0.026 and 0.1 MPa, while the maximum heat flux was 310 kw/m(\u272). The magnetic fields covered in this work were 0.2, 0.4, 0.8 and 1.26 Tesla. In the natural convection regime, the magnetic field reduced the Nusselt Number by up to 80%. A correlation for this reduction, based on the non-dimensional parameter Ly (TBOND) M/Gr(\u27 1/2), was determined. In the nucleate boiling regime, data were obtained for the pre-aged and aged states, as well as for the S-curve region and for stable boiling. The net effect of the magnetic field was to reduce the heat transfer coefficient by up to 55%. It was also determined that the magnetic field promoted the transition from stable nucleate boiling to film boiling. The theoretical results provide a semi-empirical correlation and an analytical model. The correlation is based on a forced convection analogy (Nu (TURN) Re(\u27m)Pr(\u27n)) and accounts for the magnetic field\u27s influence through the Boiling Magnetic Interaction Number (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) The analytical model is based upon the discrete bubble regime and predicts the bubble population and waiting times. An assessment is made of the influence the magnetic field has on each of the three boiling components; namely, natural convection, transient conduction and microlayer evaporation