Experimental investigation of heat transfer enhancement in an open-channel flow with dielectric fluid using electrohydrodynamic conduction pumps concept

Abstract

This study investigated the use of electrohydrodynamic (EHD) conduction pumping for heat transfer enhancement in an open-channel containing a free-surface dielectric fluid film. An experimental test was performed to determine how the heat transfer in the fluid film over the electrode pairs is influenced by the film thickness, applied voltage, temperature, pump-induced flow rate, and whether the effects of mechanical pumping and conduction pumping align in the same or in opposite directions (co-current vs. counter-current). The experimental results showed that in both co-current and counter-current modes, with the increase in the applied voltage and the emergence of circulation in the main flow, the created flow rate and circulations amplified each other’s effect, thereby increasing the heat transfer coefficient. With further increase in the applied voltage, the combined effect of more developed vortex structures and the applied flow rate had a neutralizing and even negative impact on the heat transfer. With the application of higher voltages, the vortex structures were further strengthened and even affected the film’s free surface, leading to another increasing trend in heat transfer.