Heat transfer by a piezoelectric fan on a flat surface subject to the influence of horizontal/vertical arrangement

This study presents an experimental work concerning the thermal performance of piezoelectric fans. A total of six piezoelectric fans with various blade geometries are made and tested. The influence of geometric parameters, including the horizontal/vertical arrangement, and location of the piezofan, on the performance of piezofans is examined. It is found that the heat transfer augmentation of the piezofan comes from the entrained airflow during each oscillation cycle and the jet-like air stream at the fan tip, yet these two modes are of the same order of magnitude. The heat transfer performance for vertical arrangement shows a symmetrical distribution and peaks at the center region whereas the horizontal arrangement possesses an asymmetrical distribution and shows an early peak at x/L = 0.25. It is also found that the heat transfer performance for horizontal arrangement is not necessarily lower than that of vertical one. Based on the dimensionless analysis to the test results for the all six fans, a correlation applicable for x/L = 0 is proposed. The mean deviation is 4.8% that can well describe the influence of geometrical parameters.