A computational study of active heat transfer enhancement of air-cooled heat sinks by actuated plates

Heat transfer performance of air-cooled heat sinks must be improved to meet thermal management requirements of microelectronic devices. The present paper addresses this need by putting actuated plates into channels of a heat sink so that heat transfer is enhanced by the agitation and unsteadiness they generate. A proof-of-concept exercise was computationally conducted in a single channel consisting of one base surface, two fin wall surfaces, and an adiabatic fourth wall, with an actuated plate within the channel. Air flows through the channel, and the actuated plate generates periodic motion in a transverse direction to the air flow and to the fin surface. Turbulence is generated along the tip of the actuated plate due to its periodical motion, resulting in substantial heat transfer enhancement in the channel. Heat transfer is enhanced by 61% by agitating operation for a representative situation. Translational operation of the plate induces 33% more heat transfer than a corresponding flapping operation. Heat transfer on the base surface increases sharply as the gap distance between it and the plate tip decreases, while heat transfer on the fin wall surface is insensitive to the tip gap. Heat transfer in the channel increases linearly with increases of amplitude or frequency. The primary operational parameter to the problem is the product of amplitude and frequency, with amplitude being slightly more influential than frequency. The analysis shows that the proposed method can be used for modern levels of chip heat flux in an air-cooled model forestalling transition to liquid or phase-change cooling.