陳瑤明Chen, Yau-Ming臺灣大學:機械工程學研究所陳俊男Chen, Chun-NanChun-NanChen2010-06-302018-06-282010-06-302018-06-282008U0001-1107200813350600http://ntur.lib.ntu.edu.tw//handle/246246/187081近年來隨著高功率電子元件等產品對散熱器之熱傳需求不斷提升，如何藉由高性能毛細結構來提升迴路式熱管熱傳能力，是一個重要的課題。本研究旨在添加孔洞成型劑於鎳粉中進行燒結，製造出具雙孔徑分布之毛細結構並探討在迴路式熱管內，雙孔徑毛細結構不同孔洞變化下的熱傳性能與行為。研究方法藉由改變孔洞成型劑粒徑(32~88μm)、含量(20~25vol%)以及燒結溫度(650~750℃)，搭配使用二水準因子設計的統計方法，分析出各參數對迴路式熱管的熱傳能力之影響程度與趨勢，並建立統計經驗模型，以找出最佳的雙孔徑毛細結構參數。最後，再與單孔徑毛細結構做熱傳性能的比較。究結果顯示孔洞成型劑的含量對迴路式熱管熱傳能力的影響程度最大，貢獻百分比為76.8%，其次是孔洞成型劑粒徑貢獻百分比為15.6%，而燒結溫度影響不明顯，貢獻度僅0.2%。並且在孔洞成型劑粒徑縮小、含量增多的情況下，可獲得性能較佳的雙孔徑毛細結構。透過經驗模型之建議，最佳的雙孔徑毛細結構參數為：孔洞成型劑粒徑範圍在20~32μm，孔洞成型劑含量25vol%，燒結溫度750℃。際測試結果在熱沉10℃與容許溫度85℃下，結果顯示最佳之雙孔徑毛細結構其總熱傳量可達570W、熱阻為0.08℃/W，比起單孔徑毛細結構的熱傳性能350W、熱阻為0.22℃/W，整體性能具有相當的提升。此外，雙孔徑毛細結構最高熱傳傳係數可達68 KW/m2.℃，與單孔徑毛細結構熱傳係數10 KW/m2.℃相比約提升6.8倍。針對最佳雙孔徑毛細結構明顯先升後降的趨勢，於不同熱通量下可將之分為三個階段，較低熱通量時(約130KW/m2以下)熱傳係數變化平緩，相似於單孔徑毛細結構性能變化。而隨著熱通量之增加(約130~210KW/m2)薄膜蒸發面積得以延伸，導致熱傳係數急速增高。在高熱通情況下(約210KW/m2以上)推測液體薄膜經蒸發已部分乾涸，造成性能逐漸衰退。In recent years, the high-power electronic devices cause the increasing demand of heat dissipation. Thus, how to improve the heat transfer capacity of a loop heat pipe (LHP) by the wick structure will be an important topic. The purpose of this article is to discuss the heat transfer performance and behavior of biporous wick which made by the mixture of nickel powders and pore former. The study was conducted following a statistical method using a two-level factorial plan involving three variables: the particle of pore former (32~88μm), the pore former content(20~25vol%),and sintering temperature (650~750℃). Moreover, the empirical model was built to determine the optimized parameter combination of the biporous wick. Finally, the heat transport capability of the LHP between monoporous wicks and biporous wicks has been investigated. The results showed that the pore former content is a primary effect (percent contribution is 76.8%) for performance of LHP. Particle size of pore formers is minor effect (percent contribution is 15.6%), and sintering temperature is a little effect. The better parameters of biporous wick is tend to have smaller particle size of pore former, more pore former contents. The best parameters of the biporous wick is obtained with the empirical model: The range of particle size of pore former is 20~32μm, pore former content is 25vol%, and sintering temperature is 750℃. Experimental results showed that, at the sink temperature of 10℃ and the allowable evaporator temperature of 85℃, the maximum heat transfer capacity of the best biporous wick achieved 570W and the minimum total thermal resistance was 0.08℃/W. Comparing to a monoporous wick for 350W and 0.22℃/W. In addition, the heat transfer coefficient in the evaporator of the best biporous wick reached to a maximum value of 68KW/m2•℃, which was approximately 6.8 times higher than that of the monoporous wick. With the increase of the imposed heat flux, the heat transfer coefficient of the best biporous wick increases to a maximum value and then decreases afterwards. The special heat transfer curve can be divided into three different regions. In lower heat flux(below 130KW/m2), the heat transfer performance of biporous wick is almost like that of a monoporous wick. The biporous wick had an increased surface area available for thin film evaporation at higher heat flux(130~210KW/m2). Therefore, the heat transfer coefficient reaches rapidly a maximum value. In high heat flux (above 210KW/m2), the performance of biporous wick decay gradually because the dryout starts to occur in the wick.誌謝 i要 iibstract iii錄 iv目錄 vii目錄 ix號說明 x一章 緒論 1.1前言 1.2文獻回顧 5.3研究目的 8二章 實驗原理與理論分析 10.1迴路式熱管操作原理 10.1.1毛細限制 12.1.2啟動限制 13.1.3液體過冷限制 13.1.4補償室體積限制 14.2迴路式熱管理論分析 14.2.1流動壓降分析 14.2.2熱阻分析 15.2.2-1 蒸發器熱阻 15.2.2-2 冷凝器熱阻 16三章 實驗設備與方法 18.1雙孔徑毛細結構的設計與製作 18.1.1不同種類的雙孔徑毛細結構 18.1.2雙孔徑毛細結構材料 19.1.3雙孔徑毛細結構製造設備 20.1.4雙孔徑毛細結構製造方法 21.2雙孔徑毛細結構的參數量測 23.2.1孔隙度的量測 23.2.2孔徑分布的量測 23.2.3滲透度的量測 24.3迴路式熱管性能測試設備 25.4迴路式熱管之性能評估與誤差分析 27四章 實驗設計方法 29.1因子的種類 29.2模型種類 30.2.1二水準因子設計 30.2.2中央合成設計 31.3反應曲面 32.4變異數分析 33.5實驗方法與步驟 35.5.1設計因子的選擇 36.5.2設計因子的範圍 37.5.3雙孔徑毛細結構的實驗設計 39五章 結果與討論 42.1實驗與統計分析 42.1.1變異數分析 42.1.2雙孔徑毛細結構的反應曲面分析 47.1.3追蹤性實驗 48.2 雙孔徑毛細結構之熱傳分析 51.2.1雙孔徑毛細結構內參數的影響 51.2.1-1孔洞成型劑粒徑的影響 51.2.1-2孔洞成型劑含量的影響 53.2.2 單孔徑毛細結構與雙孔徑毛細結構性能分析與探討 56六章 結論 61.1結論 61.2建議 62考文獻 63錄 662684384 bytesapplication/pdfen-US迴路式熱管雙孔徑毛細結構單孔徑毛細結構熱傳係數biporous wick, monoporous wickLoop heat pipeheat transfer coefficientthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/187081/1/ntu-97-R95522117-1.pdf