應用於筆記型電腦系統之熱擴散平板和被動式熱沉之數值分析

Abstract

近幾年來，筆記型電腦隨著微處理器和系統的功率耗散不斷的上升，高性能的散熱元件像是: 熱管、散熱片、熱擴散平板和風扇不斷的開發及應用在筆記型電腦。但是筆記型電腦的熱量快速的上升，而將電腦的熱量從內部帶走的冷卻系統卻發展非常緩慢。本篇主要在討論使用熱管來冷卻筆記型電腦的散熱系統。那就是: (1)利用熱管將熱帶至熱擴散平板，(2)利用熱管將熱帶至散熱片。 為了解決單一初始溫度的暫態熱傳問題，拉普拉氏轉換的方法很有效的被考慮。然而，最困難和複雜的是在解決偏微分方程式的代數方程式的逆轉換之技術。利用拉普拉氏轉換的定義和傅氏級數的技巧將可以有效的解決逆轉換問題。 本研究主要的目的便是針對筆記型電腦的散熱系統進行研究。使用拉普拉氏轉換和有限傅立葉級數去解暫態熱傳問題。這個解是一個連續的形式，可以計算整個介質任一點的溫度和熱通量。當增加熱擴散板的速度和尺寸，將有效的增加熱的消散。散熱片具最佳化之設計，能達到最大的散熱量，在散熱片的厚度及間距比例約 1:1時。為了方便設計分析及參數之研究，本工作的結果是以因次和無因次的型式表示之。

With the continuing increase of CPU and system power dissipation in notebook personal computers, high performance thermal solutions such as heat pipe, heat sink, thermal spreader, and fans have witnessed an increasing number of applications in the notebook personal computers. But notebook power consumption has been increasing rapidly; cooling techniques to remove the heat generated within the notebook have been evolving relatively slowly. This paper describes various cooling solutions using heat pipes for cooling of notebook personal computer. Namely, (1) heat pipes with heat spreader plate. (2) heat pipes with heat sink and fans. For transient heat transfer problem with uniform initial temperature, the Laplace transformation method is considerably powerful. However, it is difficult and complicated to solve the inverse transform of the subsidiary equation of the given differential equation. The technique of Fourier series can be used in order to obtain the inverse transform. The aim of this research is to analyze the cooling system of notebook personal computer. Using Laplace transform and finite Fourier’s series attempted a solution of governing partial equation for transient conduction in a medium. This solution procedure was a continuous form. The solution can be used to compute the temperature and flux distribution at any point throughout the medium. When increase velocity and size of heat spreader, heat dissipation increased effectively. In optimum design of heat sink, when heat flux approaches the maximum value, the ratio of fin thickness to fin spacing is about 1:1. The results of this work are presented in dimensional and dimensionless form for the convenience of parametric study and design analysis.