散熱基座的熱傳性能分析

Abstract

本文利用數值方法對一般電腦內常用散熱風扇與發熱晶片加上散熱基座之搭配進行研究與分析。本文利用有限體積法求得風扇與散熱鰭片之間的速度分佈，而流場的模擬則採用紊流k-ε模式。在實驗量測部分，利用熱線測速及熱偶設備量測風速及溫度，並與數值計算所得結果對照。結果顯示，一般使用的電腦散熱風扇中心軸會造成流體的停滯，而停滯區域的散熱效果十分不佳。停滯區域會隨著風扇與散熱基座的距離而改變，進而改善散熱效果。而鰭片形狀和位置也會影響流場流動及散熱效果。根據結果得知，如果要得到較佳的散熱效果，除了大幅提高風扇轉速增大風量外，設法減小風扇中心軸下方的停滯區域以及使用形狀較符合流場散熱的散熱鰭片也能達到目的。

This study is to investigate a flow of common used computer fan with heat sink and fin. A finite volume method is employed to solve the flow field between the fan and fins. During the computing process , the k-ε turbulent model is used to solve the governing equation of the flow field. In experimental investigation, hot wire and thermal couple technic is used to measure air velocity and the temperature of the heat sink. According to the above investigation, the flow is almost stay still in the center below the computer fan, and heat transfer is bad in this area. The still area will vary with the distance between the fan and fins. And the form and position of the fins effect the flow field and heat transfer. After analyzing the above phenomenon, besides increasing the fan’s rotating rate, decreasing the still area below the fan and using the fins with good shape are good ways to improve heat transfer.