Abstract
This study presents a concept for direct cooling. Attaching the piezoelectric actuators to the copper fins can improve the heat transfer rate by the method of vibration. The single piece named piezoelectric fan with various piezoelectric patch geometries and bonding glues are made and tested. It is found that the decay of performance is reduced with the shear strength of glues and tip displacement is increased with the hardness of glues. The maximum tip displacement and tip velocity are 10.9 mm and 2.3 m/s respectively as driven by a 100 V power source. For the fin array with five pieces plates, the heat load is conducted. It is found that the convection heat transfer coefficient can enhance 9 % under natural convection with a 5 W heat load. The heat dissipation with vibrating fins is not as good as expected owing to a small tip displacement, low overall surface efficiency and great contact resistance. The tip displacement can be improved by fixing the fins and base completely with a thermally conductive adhesive between them. The results reveal that the thermal resistance reduces 33 % and heat transfer coefficient enhances 64 % under natural convection. The overall surface efficiency can reach to be 0.9 by increasing the fin thickness to 0.28 mm (fin length is 55 mm). If the fin system can always remain an in-phase vibration condition with the fins manufactured as an integral part and the resonant frequency controlled precisely, the heat transfer performance will be enhanced markedly.