低功率靜電式離子風振動電子散熱裝置

Abstract

本研究是提出一個氣冷式電子散熱的新方向，改善一般風扇散熱的缺點，透過高壓靜電產生的靜電吸附力，讓彈性金屬片產生類似於壓電風扇的機械振動，同時運用其導電性質，當作高壓電的導電電極，使高壓電極與接地的鋁質散熱片中間的空氣解離，產生複合型的振動離子風來增強熱傳效率。實驗設計以7.5 W功率加熱，在0~20 kV電壓範圍內，調整高壓電極葉片和鋁質散熱片之間的電極間距 Dv = 5 mm~20 mm，局部熱傳係數可提昇為7.23~24.91 (W/m2K)，因施加負高壓和正高壓不同極性時，會改變電暈放電的電流值，實驗在-14 kV操作電壓，電極間距Dv = 10 mm的條件下，最佳熱傳係數可達27.08 (W/m2K)，最後比較振動式散熱、離子風散熱與複合式振動離子風散熱的散熱效能，散熱效能表現最好的是EHD式離子風散熱，在7.5W的供應熱源下，下降溫度達44.9 □C，平均電流為71.33 □A, 消秏功率 713 mW, 而靜電式振動離子風的複合式散熱效應，下降溫度43 □C，電流只有21.27 □A，為212.7 mW，秏用功率不到離子風散熱的三分之一，靜電式振動離子風散熱是整體效能中最節能的，加上振動的效應擴大散熱範圍，在低功率下達到接近於離子風的散熱效能，另外有量測振動頻率和振幅與操作電壓的關係，並評估其運用在電子散熱上的可行性。

關鍵字：電液動力學(EHD)、離子風、靜電致動器、壓電風扇

This study is to propose a novel concept to augment natural convection in association with electronic cooling. It can be used as a supplement to general fan cooling. The mechanical vibrations through the high-voltage make use the electrostatic adsorption force will vibrate the metal blade to act as the piezoelectric fan. With the use of the metal blade along with the high–voltage electrode will generate ionic wind between the electrode and the ground- aluminum heat sink. As a result, the local heat transfer coefficient can be obtained in the range of 7.23~24.91 (W/m2K) for an electrode-spacing Dv = 5 mm~20 mm when operated at the voltages of 1~20 kV. Different polarity of the voltage will change the current value of the corona discharge. The local heat transfer coefficient = 27.08 (W/m2K) can be obtained at an operating voltage of -14 kV at an electrode-spacing Dv of 10 mm. We also compare the performance of vibrating cooling, EHD cooling and Electrostatic ion wind vibration cooling . For a 7.5W heat source, the best performance can be achieved via electrostatic ion wind vibration cooling with power consumption being less than one-third of EHD cooling. And the decreased temperature of Electrostatic ion wind vibration cooling is 43 □C which is almost identical to 44.9 □C of EHD cooling. These enhancements are due to the effect of the vibration of metal blade. Besides, the vibration frequency and the amplitude of the operating voltage are also reported in this study.

Keywords: Electro-hydraulic dynamics (EHD), Ion wind, Electrostatic actuator, piezoelectric fan.