Numerical study on channel-flow convection heat transfer enhancement with piezoelectric fans under various operating conditions

Piezoelectric fans have been widely considered for electronics cooling as a stand-alone cooling device with its advantages over conventional rotary fans, such as low power consumption, low noise level, and small form factor. However, the application of the piezoelectric fans as a supplemental device in an existing forced-convection condition is rare in the literature. In this study, a transient numerical simulation is carried out to investigate the impacts of the piezoelectric fan, operating at various conditions and locations, on the convection heat transfer of a heated surface in an airflow channel. The mean-to-peak displacements and the operating frequencies of the piezoelectric fan are varied from 3.4 to 7.8 mm and from 90.3 to 180.6 Hz, respectively, for case studies. As a result, when the piezoelectric fan is operated at the front-end location with its maximum displacement and frequency, about 70 % of heat transfer improvement is achieved over the channel flow condition without the piezoelectric fan operation. Furthermore, the Q-criterion analysis is used to visualize vortical structures generated by the piezoelectric fan operating at three relative locations from a heated surface. It is found that the vortical structures carry most of the kinetic energy, creating a significant enhancement of the convective heat transfer in the channel.