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研究生:陳彥仲
研究生(外文):Yan-ZhongChen
論文名稱:相變化奈米膠囊懸浮液在具毫米流道熱沉與熱源之自然對流迴路內熱傳特性實驗研究
論文名稱(外文):Heat Transfer Experiment on a Natural Circulation Loop of Water-based Suspensions of Phase Change Nanocapsules with Minichannel Heatsink and Heatsource
指導教授:何清政
指導教授(外文):Ching-Jenq Ho
學位類別:碩士
校院名稱:國立成功大學
系所名稱:機械工程學系碩博士班
學門:工程學門
學類:機械工程學類
論文種類:學術論文
論文出版年:2012
畢業學年度:100
語文別:中文
論文頁數:80
中文關鍵詞:相變化奈米膠囊懸浮液毫米流道自然對流迴路
外文關鍵詞:Phase Change NanocapsulesSuspensionsMinichannelNatural Circulation Loop
相關次數:
  • 被引用被引用:1
  • 點閱點閱:128
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  • 下載下載:7
  • 收藏至我的研究室書目清單書目收藏:0
本研究主旨在於以實驗量測方式探討具毫米流道熱源及熱沉的自然對流迴路,選用純水及相變化奈米膠囊懸浮液作為工作流體,了解其自然對流熱傳特性及相變化材料應用效果。
實驗中所使用的毫米流道尺寸寬0.8mm、高1.2mm,其水力直徑為0.96mm,而在加熱段的毫米流道共有23條,底部熱傳面積為48×50mm2,以等熱通量方式加熱,冷卻段為確保能帶走熱量則設定為34條,底部熱傳面積為58×105mm2,以等壁溫方式冷卻。自然對流迴路尺寸架構設定高為630mm,寬為220mm,而自然對流實驗之修正萊利數範圍介於3.99×〖10〗^7~3.21×〖10〗^8間。相變化奈米膠囊的製作是使用核心材料二十烷及外殼材料尿素甲醛混合,其比例為1:1,並利用介面縮合聚合法來包覆膠囊,其中使用界面活性劑SLS及超音波粉碎機振動24小時來達成乳化的動作,再加入外殼材料調整酸鹼值並搭配均質機攪拌來完成包覆,之後將其溶液烘乾以供後續調配膠囊懸浮液,而調配之工作流體重量百分濃度有0%、0.1%、0.5%、1%。
藉由量測結果得知,相變化奈米膠囊粒徑範圍介於50~375nm間,平均粒徑為150nm,其相變化潛熱值達107.6J/g,包覆率為43.7%。熱傳實驗結果顯示,膠囊懸浮液在加熱段時,當其為1%重量濃度,可以產生熱壁平均熱傳係數增益最大值22%,而紐賽數也較純水提升16%;在冷卻段時,可以產生冷平均熱傳係數增益最大值18%,而紐賽數也較純水提升22%。由實驗結果可發現,相變化奈米膠囊懸浮液在1%的濃度時,對於熱阻及熱傳增益能發揮相當大的助益。


In this study, experiments were conducted to obtain a better understanding of heat transfer characteristics of water-based suspensions of phase change material nanocapsules in a natural circulation loop with minichannel heat sink and heat source. With the core material of n-Eicosane and the shell of urea-formaldehyde resin, the phase change material nanocapsules of a mean particle size of 150nm were fabricated successfully and then dispersed in pure water as the based fluid to form the water-based nanofluids having the mass fractions of the nanocapsules in the ranges of 0.1-1 wt.%. Of the natural circulation loop, the heat sink and heat source sections were fabricated from copper consist of 26 and 34 rectangular minichannels, respectively, each of which has a width of 0.8 mm, a depth of 1.2 mm, a length of 50 mm with a hydraulic diameter of 0.96 mm. While the adiabatic sections of the circulation loop were constructed using PMMA circular tubes of 4 mm and 6 mm in inner and outer diameters.The experiments were performed with the modified Rayleigh numbers ranged from 3.99×〖10〗^7 to 3.21×〖10〗^8. The experimental results clearly indicate that water-based suspensions of phase change nanocapsules can markedly enhance the heat transfer performance of the natural circulation loop.
中文摘要........................................ I
英文摘要........................................ II
致謝........................................... III
目錄........................................... IV
圖目錄......................................... VI
表目錄......................................... VII
符號說明........................................ VIII
第一章 緒論..................................... 1
1-1 前言....................................... 1
1-2 文獻回顧.................................... 2
1-3 研究動機與目的............................... 3
1-4 論文架構.................................... 4
第二章 相變化奈米膠囊製備及相關熱物理性質量測.......... 5
2-1 相變化奈米膠囊製備............................ 5
2-1-1 PCM乳化液製備............................. 6
2-1-2外殼預聚物製備.............................. 6
2-1-3 相變化膠囊之包覆........................... 7
2-1-4 後續處理.................................. 7
2-2 奈米膠囊相關熱物理性質量測..................... 8
2-2-1 膠囊外型及粒徑分布量測 ...................... 8
2-2-2 相變化潛熱及比熱量測........................ 9
第三章 實驗方法與數據處理......................... 12
3-1 實驗迴路及量測儀器........................... 12
3-1-1 自然對流迴路.............................. 12
3-1-2 毫米流道................................. 13
3-1-3實驗迴路維護............................... 14
3-2 工作流體................................... 14
3-3 工作流體熱物理性質........................... 15
3-4 實驗準備及啟動流程........................... 16
3-5 數據處理................................... 17
第四章 結果與討論................................ 21
4-1自然對流迴路壁面溫度分布....................... 22
4-2加熱段及其熱量輸入之影響....................... 23
4-2-1 不同加熱功率之加熱壁面溫度分布及趨勢探討....... 23
4-2-2 加熱段熱阻分析............................ 24
4-2-3 加熱段紐賽數分析........................... 25
4-3冷卻段及其壁溫之影響.......................... 25
4-3-1 不同冷壁溫度之加熱壁面溫度分布及趨勢探討....... 25
4-3-2 冷卻端熱阻分析............................ 27
4-3-3 冷卻段紐賽數分析.......................... 28
4-4相變化奈米膠囊質量濃度之影響................... 28
4-4-1 膠囊懸浮液之平均熱傳係數增益比分析........... 28
4-4-2 膠囊懸浮液之冷壁平均熱傳係數增益比分析......... 29
4-4-3 系統熱阻分析.............................. 30
第五章 結論與未來工作............................ 31
5-1 結論...................................... 31
5-2 未來研究方向................................ 33
使用圖表....................................... 35
參考文獻....................................... 73
附錄.......................................... 77

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