An active heat sink system with piezoelectric translational agitators and micro pin fin arrays

Conventional heat sink systems with blowers or fans are approaching maximum thermal management capability due to dramatically increased heat dissipation from the chips of high power electronics. In order to increase thermal performance of air-cooled heat sink systems, more active or passive cooling components are continually being considered. One technique is to agitate of the flow in the heat sinks to replace or aid conventional blowers. In the present study, an active heat sink system that is coupled with a piezoelectric translational agitator and micro pin fin arrays on the heat sink surfaces is considered. The piezoelectric translational agitator generates high frequency and large displacement motion to a blade. It is driven by an oval loop shell that amplifies the small displacement of the piezo stack actuator to the several-millimeter range. The blade, made of carbon fiber composite, is easily extended to a multiple-blade system without adding much mass. The micro pin fin arrays were created with the LIGA photolithography technique. The cooling performance of the heat sink system was demonstrated in single-channel and multiple-channel test facilities. The singlechannel test results show that the active heat sink with the agitator operating at a frequency of 686 Hz and peak-To-peak displacement of 1.4 mm achieved a low thermal resistance of 0.053 C/W in a channel with a 7.9 m/sec flow velocity. Different configurations of the translational agitator with multiple blades were fabricated and tested in a 26-channel, full-size heat sink. Vibrational characteristics are also provided.