指導教授：李雨臺灣大學：應用力學研究所謝秉倫Hsieh, Bin-LunBin-LunHsieh2014-11-302018-06-292014-11-302018-06-292014http://ntur.lib.ntu.edu.tw//handle/246246/264088奈米流體乃懸浮有奈米粒子的液體，其吸引研究者注目的一項原因為其熱傳導係數會因小量粒子的加入而明顯上升，但其機制至今仍未全面明朗。本論文的工作先以暫態熱線法與惠斯通電橋建構實驗架構、並加以驗證，再對以二氧化鈦奈米粒子與去離子水合成的奈米流體進行多項參數下熱傳導係數的量測，共獲致如下結果。改變奈米流體的單體粒子尺寸並不會明顯提高其熱傳導係數；在低體積濃度下，奈米粒子加入之濃度會明顯增加熱傳導係數；奈米流體容易受到老化效應之影響，其熱傳導係數之增益量隨時間而逐漸遞減，其主因為出現群聚之現象所致；當奈米流體的酸鹼值到達近等電位點時，其奈米粒子周圍電雙層之效應會被消除，而使其熱傳導係數達最高值。Nanofluid is a liquid suspended with nano-sized particles. It attracts many researchers because the heat conductivity of nanofluids can be enhanced significantly by adding a tiny amount of nano particles into the liquid. However, the mechanisms for the enhancement are still not fully understood. An experimental apparatus was built successfully in this thesis using transient hot wire method incorporated with Wheatstone bridge. The apparatus was validated and applied to measuring the heat conductivity of -water nanofluids for a variety of parameters. The main findings are as follows. The heat conductivity of nanofluids depends weakly on the monomer size, but increases significantly with the volume fraction of the nanofluids, provided the volume fraction is sufficiently low. Aging effect is significant, which reduces the heat conductivity with time because of the agglomeration of particles. The heat conductivity is maximized when the PH value meets the isoelectric point of the nanofluid.致謝…………………………………………………………………………………….i 摘要……………………………………………………………………………………ii Abstract……………………………………………………………………………….iii 目錄…………………………………………………………………………………...iv 圖目錄………………………………………………………………………………...vi 表目錄………………………………………………………………………………...ix 符號說明………………………………………………………………………………x 第一章 緒論…………………………………………………………………………1 1-1 研究動機與背景…………………………………………………………...2 1-2 文獻回顧…………………………………………………………………...3 1-2.1 等效熱傳導係數….…………………………………………………...3 1-2.2 布朗運動…………………………………………………....................5 1-2.3 奈米粒子體積分率……………………………………………………6 1-2.4 基礎溶液特性…………………………………………………………7 1-2.5 奈米流體實際應用……………………………………………………8 1-3 本文結構…………………………………………………………………...9 第二章 理論………………………………………………………………………..11 2-1 理論基礎…………………………………………………………………..13 2-2 實驗之數學模型…………………………………………………………..14 2-3 披覆絕緣層熱線之數學模型…………………………………………….16 第三章 實驗方法與設備…………………………………………………………..20 3-1 奈米流體之選擇………...………………………………………………..20 3-2 奈米流體配製方法…...…………………………………………………..22 3-3 暫態熱線法裝置...………………………………………………………..24 3-3.1 熱線材料選擇………………………………………………………..24 3-3.2 惠斯通電橋…………………………………………………………..25 3-3.2 實驗架構設計………………………………………………………..25 3-4 實驗架構參數…………………………………………………………….26 3-4.1 白金線電阻與溫度係數量測……………………………….……….26 3-4.2 外部電壓選擇………………………………………………………..28 3-5 確立實驗架構…………………………………………………………….29 3-5.1 實驗數據與理論值比較…………………………………….……….29 3-5.2 超音波震洗時間……………………………………………………..30 3-6 導電度量測……………………………………………………………….31 第四章 實驗結果…………………………………………………………………..32 4-1 濃度及單體粒徑改變下之熱傳導係數增益………...…………………..32 4-2 與文獻結果之比較……………………………………………………….34 4-3 老化效應造成之熱傳導係數變異……………………………………….36 4-4 基礎溶液導電度與熱傳導係數之關聯性……………………………….40 4-5 分析改變基礎溶液酸鹼值與熱傳導係數之關聯性…………………….46 第五章 結論與未來展望…………………………………………………………..49 5-1 結論…………………………...…………………………………………..49 5-2 未來展望………………………………………………………………….50 參考文獻……………………………………………………………………………..512155614 bytesapplication/pdf論文公開時間：2014/08/31論文使用權限：同意有償授權(權利金給回饋學校)二氧化鈦奈米流體暫態熱線法熱傳導係數thesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/264088/1/ntu-103-R01543034-1.pdf