High-frequency translational agitation with micro pin-fin surfaces for enhancing heat transfer of forced convection

Abstract

An advanced air cooling scheme that combines both active and passive cooling components is proposed and its thermal performance is demonstrated with single channel heat transfer experiments. The active cooling component, a piezoelectric translational agitator, generates strong air turbulence using a blade oscillating at a high frequency near either plain or micro pin-fin surfaces in the channel. The translational agitation of the blade is realized using an oval loop shell amplifier with a piezoelectric stack actuator. The micro pin-fin surfaces were fabricated by the LIGA photolithography technique. Single channel heat transfer experiments show promising results in the combined system with the micro pin-fin surface and the agitator. For instance, the combined system heat transfer coefficients were 250% of those on smooth surfaces without agitation. The channel flow rate was 40LPM and the Reynolds number was 3300. Measurements are presented that assess, pin fin and agitation effects on thermal performance of the proposed active heat sink system for several channel flow rates. Based on these single channel test results, a multi-channel, full-size, active heat sink system utilizing micro pin fins and translational agitators is proposed, and its thermal performance is estimated.