• Journal of the Korean Society of Visualization
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• v.16 no.3
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• pp.52-58
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• 2018

In this study, an experimental facility has been built to measure the cooling performance of a piezoelectric fan. The facility is composed of a heat source made of $50{\mu}m$ Ni-Cr foil, a piezoelectric fan and a rotary fan for cooling the heat source. For two cases where the foil is vertical or horizontal, the surface temperature on the foil has been measured by an IR camera with and without cooling and the cooling performance of both fans has been analyzed. With cooling by both fans, the rotary fan lowers the surface temperature of the foil as a whole, while the piezoelectric fan lowers the surface temperature at the center of the foil locally. It is also found that the cooling effectiveness of the piezoelectric fan is higher on the horizontal foil than on the vertical foil because the natural convection interferes with the jet from the piezoelectric fan.

• Electrical & Electronic Materials
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• v.8 no.1
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• pp.1-5
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• 1995

In this study, a piezoelectric fan was fabricated using piezoelectric element of 0.13PZN-0.41PZ-0.46PT prepared by extruding method. The sizes of the piezoelectric element and the piezoelectric fan were adjust to utilize commercial ac source(100V, 6OHz). The size of the piezoelectric element was $0.26{\times}19.5{\times}45$mm and the resonant frequency and the electromechanical coupling coefficient were 31.26KHz, 31.58% respectively. The size of the piezoelectric fan was $0.62{\times}19.5{\times}78.5$mm and the maximum displacement was 40mm.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.994-1000
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• 2011

In this study, the piezoelectric fan cooling system is investigated. In order to find the proper geometry and configuration, the numerical model for the flow field and heat transfer investigation is used. A simplified nonlinear deformation model is employed for transient solutions of a piezoelectric fan with the dynamic mesh and user defined function capability. The results show that the cooling is most effective when the length of a piezoelectric fan is 5 cm and the cooling plate is 3 cm. The results can be used to develop a new design method of heat sink for piezoelectric fans.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.272-277
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• 2003

This paper reports the fluid flow and heat transfer around a module cooled by forced air flow generated by a piezoelectric(PZT) cooling fan. A flexible PZT fan with distortion in a fluid transport system of comparatively simple structure which was mounted on a PCB in a parallel-plate channel($450{\times}80{\times}700mm^3$) accelerates surrounding fluid locally. Input voltages of 20-100V and a resonance frequency of 23Hz were used to vibrate the cooling fan. Input power to the module was 4W. The cooling effect using a PZT fan was larger than that of free convection. Fluid flow around the module were visualized by using PIV system. The temperature distribution around heated module were visualized by using liquid crystal film(LCF). We found that the flow type was y-shaped and the cooling effect was increased by the wake generated by a piezoelectric cooling fan.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.693-696
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• 2003

Piezoelectric ceramics were made by a doctor blade methode and piezoelectric fans were fabricated by sandwiched a slim and long metal between two layers of ceramics. A maximum displacement of piezoelectric fan occurs in the resonance frequency of a long metal and the resonance frequency of them is in inverse proportion to the square of a length of metal. The piezoelectric fan made from a wide and thin piezoelectric ceramics($13{\times}0.2{\times}30mm^3$) showed a maximum displacement in all samples, and the maximum displacement was about 20mm in a commercial power (200V, 60Hz of sine wave).

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.1
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• pp.90-94
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• 2005

As the structure of the piezoelectric bimorph cantilever becomes increasingly more complicated, a more accurate and efficient analysis of piezoelectric media is needed. In this paper, the piezoelectric transducer is analyzed by using the three-dimensional finite element method. The validity of the three-dimensional finite element routine is confirmed by comparing the experimental result. The resonance characteristics, such as resonance frequency and anti-resonance frequency, of the piezoelectric cantilever are calculated by the experimentally verified three dimensional finite element method. Subsequently, the characteristics, such as mechanical displacement and impedance, are calculated at the resonance frequency. Besides, to design the piezoelectric bimorph cantilever shape that maximizes displacement at the tip, the ES (Evolution Strategy) algorithm is applied. Finally, optimal design for the fan of the piezoelectric cantilever is fulfilled to obtain maximum displacement at the tip. From these results, the application potentiality of the piezoelectric bimorph cantilever fan is identified.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.7
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• pp.780-788
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• 2004

This paper reports the fluid flow and heat transfer around a module cooled by forced air flow generated by a piezoelectric(PZT) cooling fan. The fluids are locally accelerated by a flexible PZT fan which deflects inside a fluid transport system of comparatively simple structure mounted on a PCB in a parallel-plate channel(450${\times}$80${\times}$700㎣). Input voltages of 20-100V and a resonance frequency of 23㎐ were used to vibrate the cooling fan. Input power to the module was 4W. The fluid flow around the module was visualized by using PIV system. The temperature distributions around a heated module were visualized by using liquid crystal film(LCF). The cooling effect using a PZT fan was independent of the vent area ratios at the channel inlet and was similar to the forced convection cooling. We found that the flow type was Y-shape and the cooling effect was increased by the wake generated by a piezoelectric cooling fan.

• Journal of Power System Engineering
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• v.18 no.1
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• pp.14-21
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• 2014

Piezoelectric fans are thin elastic beams whose vibratory motion is actuated by means of a piezoelectric material bonded to the beam. These fans have found use as a means to enhance convective heat transfer while requiring only small amounts of power. This study presents new types of models with heat sink having air passage and investigates experimentally their heat transfer characteristics. From the comparison results for four models, the heat transfer coefficients of model 1 are approximately 44~66% higher than those of the reference model 0. The model 1 show the best overall performance about heat transfer and cooling capability. As shown in above results, it is necessary to design the heat sink with air pass for cooling of electronic devices, in order to increase the convective heat transfer coefficient of a piezoelectric fan for electronic cooling.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.12 s.255
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• pp.1173-1180
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• 2006

This study deals with fluid flow and heat transfer around a module cooled by forced air flow generated by a piezoelectric(PZT) fan in an enclosure. The fluid flows were generated by a flexible PZT fan which deflects inside a fluid transport system of comparatively simple structure mounted on a PCB in an enclosure($270\times260\times90mm^3$). Input voltages of 30V and 40V, and a resonance frequency of 28Hz were used to vibrate the cooling fan. Input power to the module was 4W. The height in an enclosure was changed 23$\sim$43mm. The fluid flow around the module was visualized by using PIV system. The temperature distributions around a heated module were visualized by using liquid crystal film. As the height in an enclosure and the input voltage of PZT fan increased, the cooling effect of module using a PZT fan increased. We found that the flow type was T- or Y-shape and the cooling effect was increased by the wake generated by a PZT fan.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.275-275
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• 2011