結合離子風與靜電振動增強散熱之數值模擬

Abstract

針對一新設計的靜電振動離子風散熱裝置，本研究發展出一套利用有限體積法對電場與流場耦合之數值方法。此設計透過高壓靜電產生的靜電吸附力，讓彈性金屬片產生類似壓電風扇的機械振動，並結合離子風效應達到複合式的振動離子風散熱效果藉此增強熱傳效率。實驗針對發熱片中心散熱效率做探討，模擬之結果與實驗比較後發現兩者整體趨勢上接近，但是模擬之發熱片中心溫度普遍相較實驗值來的低，此誤差源自於發熱片面上熱源給定的方式僅單面為熱源，沒有考慮其餘面散熱至環境之能量，所以與實際實驗情形不同所產生。最後我們將不擺動離子風散熱方法與複合式振動離子風散熱方法以發熱片中心溫度做比較，發現不擺動離子風擁有較好的散熱效率，但複合式散熱卻擁有較低的消耗功率而且依然達到接近於不擺動離子風的散熱效能，而從模擬結果以整體發熱片面上平均溫度做比較，發現複合式振動離子風的散熱效率普遍優於不擺動離子風，因為受到振動效應擴大散熱範圍的影響，複合式振動離子風散熱裝置在整體發熱片上反而擁有較好的表現。

Regarding a new design of electrostatic vibration to ion wind cooling device,with use of finite volume method a numerical method is developed to simulate the flow field coupling with electric field. The mechanical vibrations through the high-voltage make use the electrostatic adsorption force will vibrate the metal blade to act as the piezoelectric fan.The proposed electrostatic force-induced vibration cooling design features a hybrid effect which combines electrostatic vibration and ion wind.The ion wind by electrostatic vibration can enhance heat transfer efficiency. Compared with experiment results, the numerical results are the approximate trend, but the temperature at middle of heater is generally lower. The main error is caused by that in the simulation case we only consider one side of the heater as heat source without considering the energy loss from other sides. In the simulation case, the condition of heat loss is different with the real case. In the end, we compare with the temperature of only corona wind cooling and electrostatic force-induced vibration hybrid cooling at the middle of heater.The corona wind cooling has better performance than hybrid cooling at the middle of heater,but hybrid cooling still have close performance with corona wind and lower power consumption.Observe the average surface temperature of heater from the results of simulation,the hybrid cooling performance compare well with corona cooling due to the effect of the electrostatic force-induced vibration.