Combined Electrohydrodynamic Conduction Pumping and Dielectrophoresis for Enhancement of Liquid Film Flow Boiling

The research in this paper extends previous liquid film flow boiling studies by including the effect of an additional electrohydrodynamic (EHD) force, namely the dielectrophoretic (DEP) force. Rather than using only EHD conduction pumping of the liquid film to electro-wet the heater surface, a localized non-uniform electric field above the heater surface is also used to generate a dielectrophoretic force for improved vapor bubble extraction during the nucleate boiling regime. The effect of liquid film height and applied potential are studied as a function of heater superheat and heat flux. The study considers the sole and combined effect of DEP with EHD conduction pumping. A brief analytical study is also used to estimate the expected dielectrophoretic force magnitude and explain the results. All of the above studies are also used to quantify the enhancement in heat transfer that can be achieved when heat transport systems are driven or augmented by these electrohydrodynamic phenomena. The results show remarkable enhancement of up to 1217% in heat flux and boiling heat transfer coefficient for a given superheat when both mechanisms are used simultaneously. The experimental data are important for applications in thermal management in terrestrial and micro-gravity conditions.