Study of an innovative multiple fan system with one piezoelectric actuator embedded in a circular heat sink

In recent years, piezoelectric fans and their feasibility of cooling electronic devices have been widely studied. Nonetheless, there is few study about using piezoelectric fans to generate radial air flow. In this study, a radial multiple fan system (RMFS) was developed for the thermal management of high power LEDs. This system used one piezoelectric actuator and the magnetic repulsive force to activate up to 20 passive fans, which featured low power consumption and a large cooling area. The RMFS was embedded in a circular heat sink in order to evaluate its thermal performance. To find the optimal design of the RMFS, some geometry parameters were investigated. Besides, the performance of different designs was compared with commercially available axial fan. The results showed that design E had the better thermal performance because of its relatively large frequency and amplitude. The thermal resistance and the percentage improvement under 15 W heat flux were 0.84 K/W and 41.9 %, respectively. Moreover, a dimensionless number for the RMFS (MRMFS) was defined to assess the enhancement of the convective heat transfer coefficient. In design E, MRMFS was 2.1 when the power consumption of the RMFS was only 0.2 W.