Boiling heat transfer in the presence of electric fields

The effects of a non-uniform, radial D.C. electric field on the natural convection and nucleate boiling regimes in saturated pool boiling and on the peak heat flux phenomenon were determined for trichlorotrifluoroethane, carbon tetrachloride, dichloromonofluoromethane and chloroform using as a heat transfer surface a 0.02 inch diameter platinum wire. Bubble departure diameters for the nucleate boiling region were measured by photographic means as a function of the electric field intensity at the heat transfer surface. The application of an electric field was found to have a significant effect on the natural convection mode of heat transfer and also the peak heat flux phenomenon. Three fold increases in the peak heat flux are not uncommon. The high dielectric constant fluids exhibit a greater increase in heat transfer per unit electric stress. The experimental increases in the peak heat flux phenomenon were quantitatively and mechanistically explained by the model of an electrically stabilized Helmholtz-Taylor hydrodynamic condition. The use of an equivalent electric field postulation was found to be useful for interpreting data obtained using non-uniform electric fields. Complete boiling curves were obtained for the four fluids as a function of the electric field intensity at the heat transfer surface

Mass transfer into cylindrical liquid films measurement of liquid diffusivities

This thesis was undertaken to augment and validate the previous work of Ratcliff and Reid(7) in the area of diffusion of immiscible liquids. Their novel approach to this particular problem of liquid diffusion led the author to consider an experimental technique that has been used in gas-liquid studies. A short vetted-wall column was used to determine the rate of mass transfer of benzene and toluene into thin cylindrical films of water. A general analytical solution for the rate of mass transfer has been derived and is given below. This solution was checked using the system benzene-water. G=3.63(Π(ρω-ρβ)g/μl)1/6 R2/3 L1/2 D1/2AB Q1/3 CRo The calculated diffusivity from the experimental results for the system benzene-water with the author\u27s above derived equation gave a result which was approximately thirteen percent lower than that reported by Ratcliff and Reid(7) in their study of the same system using spherical films of water. The system toluene-water was also studied and data is presented