國際太空站專用電腦之散熱分析與設計改良

Abstract

本研究是針對反物質磁譜儀（AMS：Alpha Magnetic Spectrometer）之物理實驗計畫中，一台國際太空站專用電腦（ACOP：Astronaut Crew Operations Post）進行溫度與流場之分析與改良。主要研究方向與目標，是為了AMS實驗工作之順利，要使電腦更加可靠地運作，所以依照太空站之規格，利用模擬分析之方法，改善電腦的散熱設計，提出使其散熱更加優化之建議。 首先對ACOP的初始工程型進行量測，獲得不同流場條件下，各重要位置之溫度值以及出口之流速，藉此驗證設計時之預估結果，並討論不同流場對溫度場的影響。 本研究所採用之模擬分析軟體為Flotherm 4.2，對目前ACOP初始設計進行模擬分析，藉由初步模擬計算結果，來評估其熱設計上的缺失，再提出具體的改良對策。從模擬結果中發現，依照改良對策所進行，可以改善各發熱元件附近的溫度，將ACOP整部電腦的最高溫度值，控制在先前設計的最高溫度之下，證明此改良設計有效地增加了散熱能力。 在分析之後，提出了以下幾點改良之建議：(1)若將後側直立電路主板開孔，使電路板之處改成為開放空間，讓冷卻氣流可以流入幫助散熱，也就是增加強制對流的機制於電路板上，由模擬計算結果，可以知道比初始設計最多降低16 ℃。(2)將後側隔板換到另一側，讓硬碟接觸到溫度更低的冷卻氣流，可幫助硬碟的溫度更加下降1~2℃。(3)電路板內部銅箔摻雜使用2盎司之銅膜，藉此改善電路板本身的傳導性，由模擬計算之結果，發現原先溫度最高的電路板中央，降低了2~39 ℃，對於熱最集中的部位有非常大的改善。

This research focuses on the analysis and improvement of the thermal design of ACOP（Astronaut Crew Operations Post）computer launched to the ISS（International Space Station）in AMS（Alpha Magnetic Spectrometer）experiment. In order to make computers operate as reliably as possible, it was proposed that a more ideal design based on specification of ISS by using simulation software to improve the thermal design of the ACOP computer. This thesis firstly is to measure the preliminary ACOP EM（Engineering Model） and derive the temperature of each important part and the velocity of outlet air. With the testing result, the prediction of EM’s design could be verified, and it can be discussed that the influence on temperature distribution in different flow condition. The Flotherm 4.2 simulation software is adopted to make a thermal analysis of the initial design of ACOP computer. By considering the problems of the thermal design, it was proposed that several concrete modifications based on the simulation results. The simulation proved the following modifications will lower the temperature of ACOP computer which proves that the newer design increase heat dissipation. After analyzing ACOP computer, it have been derived the following conclusions and recommendations. The major three conclusions can be drawn from the modifications： 1.The opening on the backside circuit board: the opening provides the forced cooling air around the circiut boards. By adding the heat dissipation path, the temperature of circuit boards of ACOP computer can be lowered by 16 ℃ at most. 2.The placement of the air flow separator: arrange the separator to the other side. The H.D.D. （Hard Disk Driver）would be cooled by the cooler air which resulted in a temperature decrease of 1~2 ℃ compared to the original design. 3.The quantity of copper doping of the circuit board: after adding the copper doping of the circuit boards to 2 oz every layer, the conductivity of the circuit boards is proved to be upgraded and also causes a temperature decrease of 2~39 ℃.