Experimental investigation on the effect of vertical vibration on thermal performances of rectangular flat plate.

Highlights • The average heat-transfer coefficient is much higher when the plate is horizontal. • The average heat-transfer coefficient decreases with increasing orientation angle. • The average heat-transfer coefficient increases with increasing oscillation frequencies. Abstract Vibration effects on thermal performances of the rectangular flat plate under natural convection condition are experimentally investigated in both horizontal and slightly inclined from horizontal orientations in multiple angles. The effects of Rayleigh number and vibrational Reynolds number on the average heat-transfer coefficient are also examined. The Aluminium made plate was subjected to sinusoidal vibration in the vertical plane. The test sample was heated under a constant heat flux. The amplitude of vibration was varied from 1.5 to 7.5 mm and the frequency of vibration from 0 to 16 Hz. From the results of the experiments, it is observed that the average heat-transfer coefficient increases linearly with increasing Rayleigh number for different orientation angles. It was also found that the average heat-transfer coefficient is much higher for the cases when the plate is horizontal, and it decreases when the orientation angle value was increased. Such as the average heat-transfer coefficient decreased by approximately 13% for 30° orientation case. The measured result further showed that the average heat-transfer coefficient in the vertical position is lower than the average heat-transfer coefficient in the horizontal position and slightly higher than the other orientation angles (i.e. 30°, 45° and 60°). Finally, it was found that the increases in oscillation frequencies lead to an increase in the average heat-transfer coefficient and the maximum increase was obtained in the horizontal position and higher frequencies. However, the average heat-transfer coefficient decreases with increasing the vibration frequencies when the plate was in the vertical position. [ABSTRACT FROM AUTHOR]