Development of a piezoelectric heat sink

Abstract

A heat sink with piezoelectric vibrating fins is developed by attaching piezoelectric actuators to the fins of a heat sink, and heat transfer characteristics of the heat sink are experimentally investigated. The fins of the heat sink vibrate like piezoelectric fans. The fins bend to a side when the piezoelectric actuators expand, and the fins bend to the other side when the piezoelectric actuators contract. So the periodic expansion and contraction motions of the piezoelectric actuators make the fins vibrate. The thermal performance of the heat sink changes as the input power change to the piezoelectric actuators or the input frequency change. Particularly, if the input frequency to the fins matches up to the natural frequency of the fins, the vibration amplitude is significantly increased by resonance and the thermal performance also increases. The natural frequency of the fins decreases as the base temperature increase. Thermal expansion and Young’s modulus change cause the natural frequency change. The correlation between temperature and natural frequency is derived. Thermal performance improvement of the heat sink by the vibration of the fins is observed compared to the thermal performance of a natural convection heat sink with static fins under a fixed heat sink geometry condition. Thermal performance curve of the piezoelectric heat sink is similar to the thermal performance curve of a fan mounted heat sink. The thermal resistance of the piezoelectric heat sink is inversely proportional to the input power to the piezoelectric actuators.