Forced Convection during Cooling of Power Supply Box using Pulsation Flow with Piezoelectric Fan

Abstract

AbstractForced convection flow of air through power supply box with piezoelectric fan of nine identical electrical devices has been numerically investigated. This work simulates a practical situation in which periodic temperature is generated in an electrical device as a result of its periodic input voltage. The finite volume method has been adopted to solve the governing equations. The effects of important parameters such as pulsation flow frequencies and temperature modulation frequency on heat transfer rates were investigated in details for Re = 500 corresponding to velocity of 0.39 m/s. The piezoelectric vibration amplitude is fixed at 0.2 and frequencies are varied in the range of [0–3] corresponding to [0–287] Hz. We have found that the time averaged Nusselt number for each electrical device depends on the pulsation frequency and heat modulation, and it is always larger than that in the steady‐state case. The results show that there exists a short band of frequencies which the enhancement of heat transfer of all electrical devices is higher than 55% compared with that of steady state. In addition, the heat transfer is maximum when heated pulsation frequency in the device is set as St = 3.0 corresponding to frequency of 58.5 Hz of input voltage. The combined pulsation flow by piezoelectric fan and heated pulsation by input voltage show vigorous heat transfer through electrical devices blocks and the heat transfer enhancement was observed in relatively narrow bands of frequencies. The efficiency of piezoelectric fan is expressed by the maximum temperature of the ninth electrical device which not exceed 80°C for time‐averaged velocity of 0.556 m/s and vibration frequency of 34.75 Hz of piezoelectric fan. The pressure drop and power pumping of piezoelectric fan are obtained for different Reynolds numbers. We found that the power loss was 4.6 times higher than for the piezoelectric fan at Re = 500. Good agreement between our numerical simulations of piezoelectric fan and experimental results available from the literature is obtained. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.