Electrohydrodynamic Convective Heat Transfer in a Square Duct

Laminar to weakly turbulent forced convection in a square duct heated from the bottom side is strengthened by ion injection from an array of high voltage points, opposite to the heated strip. Both positive and negative ion injection is activated within the working liquid HFE-7100 (C4F9OCH3), with transiting electrical currents in the order of 0.1 mA. Local temperatures on the heated wall are measured by liquid crystal thermography. The tests are conducted in a Reynolds number range going from 510 to 12100. In any case, heat transfer is dramatically augmented, almost independently from the flow rate. The pressure drop increase caused by the electrohydrodynamically-induced flow is also measured. A profitable implementation of the technique in the design of heat sinks and heat exchangers is foreseen; possible benefits are pumping power reduction, size reduction, and heat exchange capability augmentation.