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研究生: 許庭瑋
Ting-wei Hsu
論文名稱: 以紅外線熱像分析冷媒R410A在板式熱交換器內之蒸發熱傳性能
指導教授: 楊建裕
口試委員:
學位類別: 碩士
Master
系所名稱: 工學院 - 能源工程研究所
Graduate Institute of Energy Engineering
論文出版年: 2012
畢業學年度: 101
語文別: 中文
論文頁數: 84
中文關鍵詞: 板式熱交換器分佈不不均入口分佈器紅外線熱像
外文關鍵詞: Plate heat exchanger, mal-distribution, inlet port distributor, Infrared photograph
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  • 板式熱交換器作為蒸發器時,入口處的兩兩相冷冷媒因慣性力力與重力力 的作用,造成流流道入口的冷冷媒分佈不不均,為了了降降低此現象,目前多於 入口處裝置入口分佈器。但產生單一流流道內分佈不不均勻的問題,而入 可分佈器可藉由改變不不同的開孔方向改善單一流流道中兩兩相冷冷媒流流動 分佈不不均勻的問題。本研究利利用紅外線熱像儀觀察板片之溫度度場,並 且進一步分析在板式熱交換器內設置分佈器之後對於冷冷媒蒸發溫度度 場的影響。從板片表面溫度度場觀察結果可知,接近冷冷媒側流流道入出口 處之過熱面積會小於遠離離冷冷媒側入出口處之過熱面積,而此種現象在 設置入口分佈器以後則不不明顯。
    若若固定過熱段與飽和段的熱傳量量比例例,冷冷媒雷雷諾諾數數越高則過熱面 積越小,原因是冷冷媒飽和段的熱傳機制主要被核沸騰主導。在相同的 熱傳量量下,同向流流動的過熱段面積較逆向流流大,原因是過熱段的兩兩側 流流體溫差較小。從局部熱傳係數數分析結果得知,設置分佈器以後熱傳 係數數較低(約減少 14%),此實驗結果歸因於冷冷媒流流經分佈器的時候所 造成的壓降降以及乾度度上升。在冷冷媒飽和段熱傳量量減少的情況下,其熱 傳係數數也相對減少。


    Because the inertia force and gravity is different among liquid and vapor, there is flow mal-distribution in a header of plate heat exchanger when the refrigerant is two phase fluid. In order to reduce this phenomenon, some people install distributor in the header of exchanger, but the opening direction of distributor will affect refrigerant flow distribution in a channel. In this research an experimental study to visualize temperature distribution in the plate heat exchanger that in order to observe the effect of installing the optimum distributor in the plate evaporator. From temperature visualization results, the area of superheat near the side of refrigerant port is larger than that of near the side of water. This phenomenon is not obvious in the case of installed distributor.
    If fix the ratio of heat among the single phase region and the two phase region, area of superheat become smaller when refrigerant rate become larger. The reason is that the main heat transfer mechanism in two phase region is nucleate boiling heat transfer. The area of superheat in counter flow case is smaller than parallel flow case. The reason is that the logarithmic mean temperature of single phase in the counter flow case is larger than the parallel case. Heat transfer coefficient in the case of installed distributor is smaller than the case of uninstalled distributor (about 14% reduced). This phenomenon is attributed to the pressure dropping and vapor quality rising when refrigerant flow through the distributor.

    目 錄 摘要 i Abstract ii 目錄 iii 表目錄 vi 圖目錄 vii 符號說明 x 第一章 前言 1 1.1 研究動機與背景 1 1.2 研究目的 2 第二章 文獻回顧 5 2.1集管中分佈不均勻的現象 6 2.2流道中分佈不均勻的現象 8 2.3熱傳係數計算 12 2.4 文獻總結 13 第三章 實驗方法 22 3.實驗系統 22 3.2實驗量測設備 23 3.2.1 流量量測 23 3.2.2 壓力量測 23 3.2.3 壓差量測 24 3.2.4 溫度量測 24 3.2.5 資料擷取系統 25 3.3 實驗步驟 25 3.3.1建立水熱傳係數經驗式 25 3.3.2紅外線熱像儀校正 26 3.3.3以紅外線拍攝蒸發溫度場 26 3.4 數據換算 28 3.4.1建立水側熱傳係數經驗式 28 3.4.2蒸發溫度場分析方法 32 3.4.2.1飽和段和過熱段分界的判斷方法 32 3.4.2.2局部熱傳係數計算 33 第四章 實驗結果與討論 48 4.1實驗參數 48 4.2不同Rer之逆向流溫度場(分佈器開口方向:4點半鐘) 49 4.3不同流動方向之溫度場(逆向流、同向流) 49 4.4無分佈器和有分佈器之逆向流溫度場 50 第五章 結論 60 參考文獻 61 附錄 65 表 目 錄 表 2.1 水Re=309時各區域流量佔總流量的百分比(曾廣彬[2010]) 14 表 3.1 測試板片幾何參數與尺寸 34 表 3.2 實驗儀器誤差 35 表 4.1 實驗參數 53 表 4.2 實驗參數 53 圖 目 錄 圖 1.1 殼管式熱交換器 3 圖 1.2 板式熱交換器(王啟川 [2007]) 3 圖 1.3 板式熱交換器流體流動示意圖(Alfa Laval) 3 圖 1.4 流體在板片溝槽內之交叉流動(Focke and Knibbe [1984]) 4 圖 1.5 入口流道分佈器示意圖(Alfa Laval) 4 圖 2.1 常見各式板片形狀(王啟川 [2007]) 14 圖 2.2 山型紋板片幾何形狀(王啟川 [2007]) 15 圖 2.3 流體在板片溝槽內之交叉流動(Focke及Knibbe [1986]) 15 圖 2.4 水-空氣兩相流譜圖(Vlasogiannis et al. [2002]) 16 圖 2.5 水-空氣中子照(Asano et al. [2004]) 17 圖 2.6 冷媒R-141b中子照(Asano et al. [2004]) 17 圖 2.7 水-空氣中子照相拍攝結果(Asano et al. [2005]) 18 圖 2.8 冷水流道內的溫度分佈(Jain et al. [2007]) 19 圖 2.9 K050板片的截面位置。(曾廣彬[2010]) 20 圖 2.10 局部熱傳係數分佈圖(a) Re=1060 (b) Re=2120 (c) Re=3980 21 圖 3.1 溫度場觀察系統示意圖 36 圖 3.2 K050 原型板式熱交換器 37 圖 3.3 K050 觀察型板式熱交換器 37 圖 3.4 (a) 含有分佈器的板片(b)分佈器局部方大圖 37 圖 3.5 小型環控箱立體圖 38 圖 3.6 K050 噴上黑漆的板片 39 圖 3.7 流量計的校正曲線圖 39 圖 3.8 (a)蒸發器入口壓力轉換器的校正曲線圖 40 圖 3.8 (b)膨脹閥入口壓力轉換器的校正曲線圖 41 圖 3.9 蒸發器入出口差壓轉換器的校正曲線圖 42 圖 3.10 水入口RTD的校正曲線圖 43 圖 3.11 紅外線熱像儀的校正曲線圖 44 圖 3.12 資料擷取系統示意圖 44 圖 3.13 畫上分析線的熱像 45 圖 3.14 過熱段分界的判斷方法 46 圖 3.15 局部熱傳係數計算方法 47 圖 4.1 有分佈器逆向流動在不同雷諾數之溫度分佈比較 54 圖 4.2 有分佈器在不同流動方向溫度分佈之比較 55 圖 4.3 不同流動方向溫度變化之示意圖 56 圖 4.4 逆向流溫度分佈(Rer=1500) (a)無分佈器 (b)有分佈器 57 圖 4.5 逆向流溫度分佈(Rer=1000) (a)無分佈器 (b)有分佈器 57 圖 4.6 逆向流溫度分佈(Rer=500) (a)無分佈器 (b)有分佈器 58 圖 4.7 局部熱傳係數分佈(Rer=1500) 59 圖 4.8 流道中兩相冷媒流動示意圖 59

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