蘇金佳臺灣大學：機械工程學研究所林俊宏Lin, Chun-HungChun-HungLin2007-11-282018-06-282007-11-282018-06-282007http://ntur.lib.ntu.edu.tw//handle/246246/61024本研究係針對板式熱交換器內之波浪型流道，進行局部與平均的熱傳遞性能實驗測試與分析。本實驗中共測試四組具有不同幾何形狀之波浪型流道，而流道表面以大量均勻等溫的熱水維持等壁溫的邊界條件。 流道的幾何參數包括流道波長、波狀角度、波狀部分曲率半徑、直線部分長度與流道寬度等。 本研究以空氣為工作流體，流體流經流道內被加熱，並以T型熱電偶線量測流場內大約數百點的局部溫度。 實驗之控制變因包括流體的雷諾數、波狀角度、流道寬長比、流道直波比等。 實驗所探討流道的熱傳遞性能則包括流體局部溫度與各截面平均溫度、局部與平均紐塞數。 研究結果顯示，局部與平均紐塞數均隨著雷諾數的增加而上升，但局部紐塞數則隨著離流道入口距離的增加而下降。 值得注意的是，熱傳遞在靠近波峰的區域有增強的效果，而局部紐塞數在靠近波峰的區域也有躍升的現象。 局部與平均紐塞數均隨著流道寬長比的增加而微幅增加。 一般而言，局部與平均紐塞數均隨著波狀角度增加而增加，但隨流道直波比的增加而下降。 本研究亦提出在不同操作範圍下之經驗式並與實驗數據做比較。 第二部分是利用柏金漢π理論，針對波浪型彎曲通道之熱傳性能，定義出流道之無因次幾何參數，再透過實驗數據統計分析，最後歸納出無因次參數方程式，藉此找出影響熱傳性能的主要參數。 　　研究結果顯示，影響Nux參數依次為Re、R/Dh、x/Dh、β、局部溫差及局部普蘭托數，若省略影響Nux較小之參數，得到影響Num的參數依次為Re、R/Dh及β。This study performed an experimental investigation into the heat transfer characteristics of the corrugated channels within plate heat exchangers (PHEs). Four flow channels with the different geometry were constructed, and a series of experiments were performed in which air was passed through the channels at flow rates corresponding to Reynolds numbers in the range 300~7000 while the channel surface was maintained at a constant temperature. The channel geometry includes the corrugated angle, the width, the curvature radius of the corrugation part, and the length of straight section of the channel. Starting from the entrance, the air temperatures within the test section monitored with T-type thermocouples. Results indicate that both the local and average Nusselt numbers increase with the Reynolds number. The phenomenon that the local Nusselt number decreases with increasing the distance from the entrance commonly occurs in channel flows. It is worth to notice that the heat transfer is greater at sections near the crest after the entrance region. In general, the local and average Nusselt numbers increase with the increased corrugated angle but decrease with the ratio of the length of the straight part to the curvature radius of corrugation of the channel. Finally, the empirical relations are then developed to describe the correlation between the Nusselt number and the Reynolds number in the laminar and turbulent regimes. In Part II, based on the Buckingham Pi theorem, this study derives dimensionless correlations to characterize the heat transfer performance of the corrugated channel in a plate heat exchanger. The experimental data are substituted into these correlations to identify the flow characteristics and channel geometry parameters with the most significant influence on the heat transfer performance. Simplified correlations by omitting the factors with less influence are then obtained. The results show that Nux is affected primarily by Re, R/Dh, x/Dh, and β. Neglecting the minor effect of factors on Nux, it is shown that Num is determined primarily by Re, R/Dh and β.誌謝………………………………………………………………………I 摘………………………………………………………………………III Abstract………………………………………………………………IV 目……………………………………………………………………...VI 表目錄…………………………………………………………………IX 圖目錄…………………………………………………………………X 符號說明…………………………………………………….……….XIV 第一章 緒論…………………………………………………………1 1.1 研究背景………………………………..……………….1 1.2 板式熱交換器種類與特性…………………………………2 第二章 文獻回顧…………………………………………………….6 2.1 相關文獻回顧………………………………………………6 2.2 研究目的……………………………………………………16 第三章 實驗設備與實驗步驟………………………………………18 3.1 實驗設備……………………………………………………18 3.1.1 空氣系統……………………………………………………18 3.1.2 水循環系統…………………………………………………19 3.1.3 流道測試區…………………………………………………20 3.1.4 量測設備……………………………………………………21 3.1.5 電控系統……………………………………………………22 3.2 實驗操縱變因………………………………………………23 3.3 實驗步驟……………………………………………………24 3.3.1 流道安裝步驟………………………………………………24 3.3.2 溫度量測步驟………………………………………………25 3.4 實驗數據分析………………………………………………26 3.5 實驗應注意事項……………………………………………29 第四章 模擬方法……………………………………………………31 4.1 模擬方法的理論……………………………………………31 4.1.1 Buckingham Π理論的介紹…………………………………31 4.1.2 無因次方程式的推導………………………………………32 4.2 板式熱交換器內波浪型通道的性能模擬…………………33 4.2.1 波浪型通道內之無因次參數群組…………………………33 4.2.2 波浪型通道之無因次方程式………………………………35 第五章 結果與討論…………………………………………………37 5.1 溫度分佈……………………………………………………37 5.1.1 x方向各截面平均溫度…………………………………….37 5.1.2 y方向局部溫度分佈……………………………………….42 5.2 局部紐塞數…………………………………………………44 5.2.1 x方向局部紐塞數………………………………………….44 5.2.2 入口區效應…………………………………………………47 5.3 平均紐塞數…………………………………………………50 5.3.1 單一流道之紐塞數經驗公式………………………………53 5.4 無因次方程式的模擬結果…………………………………55 5.4.1 局部紐塞數與平均紐塞數之探討…………………………55 5.4.2 雷諾數之效應………………………………………………56 5.4.3 流道曲率半徑之效應………………………………………56 5.4.4 位置變化之效應……………………………………………57 5.4.5 流道彎曲角度之效應………………………………………57 5.4.6 局部溫差之效應……………………………………………58 5.4.7 局部普蘭托數之效應………………………………………58 5.4.8 方程式之比較………………………………………………61 第六章 結果與建議…………………………………………………64 參考文獻………………………………………………………………66 附錄A 誤差分析…………………………………………………….149 A.1 各截面平均溫度Tm之誤差分析…………………………149 A.2 熱傳遞係數之誤差分析…………………………………151 A.3 紐塞數之誤差分析……………………………………….152 附錄B 因次分析………………………………………………………153 作者簡介………………………………………………………15417708938 bytesapplication/pdfen-US強制對流彎曲通道紐塞數柏金漢Π理論因次分析forced convectioncorrugated channelNusselt numberBuckingham Πdimension analysisthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/61024/1/ntu-96-D89522017-1.pdf