陳瑤明臺灣大學:機械工程學研究所王維星Wang, Wei-HsingWei-HsingWang2010-06-302018-06-282010-06-302018-06-282009U0001-0608200914275800http://ntur.lib.ntu.edu.tw//handle/246246/187154迴路式熱管是一種利用相變化進行散熱的高效能熱傳裝置，擁有熱傳距離長、熱阻小、熱傳量大的優勢，在配合解決電子產品散熱問題而小型化的同時，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。研究旨在探討將雙孔徑毛細結構(Bidispersed Wick)應用於迴路式熱管(Loop Heat Pipe)時，孔洞球粒徑對系統性能的影響，並與單孔徑毛細結構進行熱傳性能與特徵的比較。實驗首先利用混煉的造粒技術製造出孔洞球，並藉由孔洞球間的堆積來形成連通性的孔道，配合孔洞球內鎳粉鍵結產生的小孔，藉以形成具大、小孔徑分佈的毛細結構。黏結劑方面選用聚丙烯、石蠟、以及硬脂酸組成多成分黏結劑，黏結劑含量選擇分別為以下三種: 50vol%、60vol%、70vol%，而黏結劑中聚丙烯、石蠟、硬脂酸的比例則是選擇40:55:5、50:45:5，配合熱脫脂燒結升溫曲線於700℃進行燒結，進行雙孔徑毛細結構製程參數對於成型效果影響的討論。製程結果顯示黏結劑含量以60vol%而黏結劑成分間比例聚丙烯、石蠟、硬脂酸為40:55:5對於雙孔徑毛細結構有較佳的成型結果。　雙孔徑毛細結構實際熱測試結果在熱沉10℃與容許溫度85℃的條件下，最高總熱傳量可達550W、最低系統總熱阻為0.13℃/W，比起單孔徑毛細結構的總熱傳量400W、熱阻為0.19℃/W，整體性能具有顯著的提升。此外，實驗結果也顯示雙孔徑毛細結構中孔洞球粒徑減小能夠增強最高熱傳量並降低系統總熱阻，然而過小的孔洞球粒徑(53~62μm)反而降低了熱傳性能，推測原因是由於孔洞球堆積的更緊密而造成滲透度降低，進而影響了蒸氣的排除。　最後，將雙孔徑毛細結構與單孔徑毛細結構進行熱傳特徵現象比較可以發現，應用雙孔徑毛細結構之最高蒸發氣熱傳係數可達23 kW/m2.℃，與單孔徑毛細結構之蒸發器熱傳係數8 kW/m2.℃相比可提升近3倍。針對雙孔徑毛細結構熱傳係數顯著提升的現象，推測原因為隨著輸入熱通量增加，雙孔徑毛細結構內的蒸氣薄膜蒸發面積得以延伸，進而提高熱傳係數。由於本研究目前僅探討了雙孔徑毛細結構中孔洞球粒徑對熱傳性能的影響，若能夠將其他的參數如燒結溫度、鎳粉粒徑等進行更深入的探討，對於迴路式熱管熱傳性能都將能有更大的提升潛力。Loop heat pipe (LHP) is an effective phase-change cooling device which can achieve long-distance transport, low thermal resistance, and high heat transfer capacity. Improving the heat transfer capacity of LHP by a wick structure will be an important topic. The purpose of this study is to investigate the bidispersed wicks’ heat transfer performance of different cluster sizes and to compare their heat transfer characteristics with a monoporous wick on a LHP. The experiment used the granulation mixing method to create clusters and formed connective pores between clusters. The bonding nickel powder produces smaller pores inside the cluster to make a bidispersed wick.To discuss the manufacturing parameters’ effect on bidispersed wicks, we select binder composed of polypropylene(PP), paraffin wax(PW), stearic acid(SA), as well as multi-component binder composition in this experiment,. Three binder contents were choosed as the following: 50vol%, 60vol%, 70vol%. And the bonding elements PP, PW, SA were choosed in the ratios of 40:55:5, 50:45:5. The bidispersed wicks were debinded and sintered with the sintering curve under the fixed temperature of 700 ℃. The results presented that bidispersed wicks formed better shape with the binder content of 60vol% and the ratio between the binder elements PP, PW, SA of 40:55:5. Experimental results revealed that, at the sink temperature of 10℃ and the maximum allowable evaporator temperature of 85℃, the maximum heat transfer capacity of the best bidispersed wick achieved 550W and the minimum total system thermal resistance was 0.13℃/W. Comparing to a monoporous wick for 400W and 0.19℃/W, overall performance has significantly improved. In addition, the experimental results also showed that the maximum amount of heat transfer can be enhanced and the total system thermal resistance can be reduced by reducing the cluster size, but too small cluster sizes(53~62μm) would reduce the heat transfer performance contrarily. This results may be explained that closer accumulation causeing by too small cluster sizes reduced permeability, which impacted the evacuation of the vapor. Finally, by comparing the heat transfer characteristics can be seen that the heat transfer coefficient in the evaporator of the best bidispersed wick reached to a maximum value of 23kW/m2•℃, which was approximately 3 times higher than that of the monoporous wick. The significant enhancement of the heat transfer coefficient of bidispersed wicks can be explained that the wick had increased the surface area available for the thin film evaporation with increasing heat flux. Therefore, the heat transfer coefficient reaches a maximum value. The future work will consider more parameters such as sintering temperature, nickel particle size etc. , the loop heat pipe heat transfer performance shall be upgraded with greater potential.摘要 ibstract iii錄 v目錄 viii目錄 x號說明 xi一章 緒論 1.1前言 1.2文獻回顧 6.3研究目的 8二章 實驗原理與理論分析 9.1迴路式熱管操作原理 9.1.1毛細限制 11.1.2啟動限制 12.1.3液體過冷限制 12.1.4補償室體積限制 13.2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 14.2.2-1 蒸發器熱阻 15.2.2-2 冷凝器熱阻 15三章 實驗設備與方法 17.1毛細結構原料與製造設備 17.1.1毛細結構原料 17.1.2毛細結構製造設備 18.2毛細結構製造方法 20.2.1黏結劑之選擇 20.2.2脫脂 21.2.3製造步驟 23.3毛細結構主要參數 28.3.1孔隙度量測 28.3.2有效半徑量測 30.3.3滲透度量測 32四章 實驗設備與方法 33.1實驗設備 33.2實驗方法 36.2.1迴路式熱管安裝步驟 36.2.2迴路式熱管測試步驟 36.2.3迴路式熱管之性能評估與誤差分析 37.3實驗規劃 38五章 結果與討論 39.1製程結果 39.1.1黏結劑比例之影響 39.1.2熱脫脂燒結升溫曲線之影響 42.2 迴路熱管性能測試結果 45.2.1孔洞球粒徑對雙孔徑毛細結構的熱傳性能影響 45.2.2單孔徑毛細結構與雙孔徑毛細結構性能分析與探討 49六章 結論 53.1結論 53.2建議 54考文獻 55錄 584865100 bytesapplication/pdfen-US迴路式熱管雙孔徑毛細結構黏結劑熱脫脂loop heat pipebidispersed wickbinderdebindingthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/187154/1/ntu-98-R96522119-1.pdf