Surface wave model of electrohydrodynamically coupled minimum film boiling

Abstract Strong uniform or non-uniform electric fields enhance film boiling heat transfer in insulating and conducting dielectric liquids. One mechanism proposed in explanation of this effect is electrohydrodynamic coupling at the vapor/liquid interface. This coupling is predicted to manifest itself in decreased film boiling wavelengths, increased bubble release rates, and increased heat flux at the minimum film boiling point. Wavelength and heat flux data for pure highly insulating Freon-113 and for a conducting mixture of Freon-113 and methanol with ac electric fields are compared to the predictions of an existing electrohydrodynamic surface wave model. The pure Freon-113 data correlate with some success to a perfectly insulating theoretical model, and the Freon-113/methanol mixture data correlate reasonably to a perfectly conducting model. In general, the predicted dependence of wavelength and heat flux at the minimum film boiling point on applied voltage are verified by the experimental data. More specifically, the order-of-magnitude differences in the voltages required for strong electrohydrodynamic coupling for the insulating and conducting liquids, as predicted by consideration of charge relaxation, are borne out by experiment. The failure of similar arguments in predicting the magnitude of the surface wave coupling for insulating liquids with dc applied electric fields is also discussed.