| Summary: | 博士 === 國立臺灣大學 === 機械工程學研究所 === 100 === This research presents the performance and the applications of a multiple-vibrating fan cooling system composed of one piezoelectric (PZT) fan and four magnetic fans. The system takes advantage of both the resonant effect and the magnetic repulsive force to make five fans vibrate simultaneously by using one PZT plate. The vibrating fans are able to generate forced convective flow and enhance the cooling ability of the fan cooling system. The work first investigates the optimum arrangement and the suitable operating conditions of a single PZT fan cooling system. The effects of the operating frequency, the fan amplitude, the fan arrangement, the power consumption and the dimensionless PZT-convection number (M_p) and "Ri (Gr/" 〖〖"Re" 〗_"PZT" 〗^"2" ) have been analyzed. Further, a three-dimensional model has been built by using CFD-RC to account for the flow field around a vibrating fan. The results can be applied to a multiple-vibrating fan cooling system.
The performance of a multiple-vibrating fan cooling system can be demonstrated by the fan amplitude and the cooling ability. Because the system is composed of five fans whose amplitudes are each proportional to the generated flow rate, the total amplitude of the fans can be used to estimate the flow rate of the five-fan system. The experimental results show that the total amplitude of the multiple-vibrating fan cooling system is 32 mm at a power consumption of 0.03 W. However, the amplitude of the single PZT fan cooling system is only 8 mm at the same power consumption. The system was embedded into a heat sink heated by a 20 W dummy heater. The temperature of the heat sink surface was maintained at 67 ℃ in a steady state. After turning on the system for 10 minutes under the conditions of 36.4 Hz and 50 V, the heat sink surface dropped from 67 ℃ to 50 ℃ at a power consumption of 0.03 W.
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