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研究生:戴智雄
研究生(外文):Chih-Hsiung Dai
論文名稱:氣流分佈對開放式冷藏櫃均溫性之影響
論文名稱(外文):The effect of air distributions on the uniform temperature at an open type refrigerated display cabinet
指導教授:蔡瑞益蔡瑞益引用關係
指導教授(外文):Ruey-Yih Tsai
學位類別:碩士
校院名稱:中原大學
系所名稱:機械工程研究所
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:2009
畢業學年度:97
語文別:中文
論文頁數:100
中文關鍵詞:數值模擬氣簾背板開孔展示櫃
外文關鍵詞:perforated back panelair curtainsimulationdisplay
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本文中實驗所使用之垂直開放式冷藏櫃,尺寸大小為長0.6公尺、寬0.91公尺、高1.9公尺。利用不同背板開孔分佈,探討開放式冷藏櫃均溫性之較佳化,由結果顯示開放式展示櫃若要有較佳均溫性,背板開孔數量和位置需要與出風氣簾相互搭配。開放式冷藏櫃一般高溫大多位於下層層板,以本文中較佳之背板開孔分佈與原始背板開孔分佈比較,其第四層棚架至第六層棚架內溫度大約都較原始背板開孔分佈低1℃,而第一層至第六層櫃內溫差亦較原始背板分佈小,故整體展示櫃均溫效果較佳。因此若展示櫃能設計足夠風量及適當的背板開孔分佈,加強對於開放式展示櫃下層高溫區之冷卻效應,將可以改善整體展示櫃之均溫性。本文中蒸發溫度增加1℃,對於開放式展示櫃冷藏系統循環性能係數(COP)約改善7.79%。
In this paper, the vertical open-type refrigerated display cabinet is used for experimental. The size is 0.6m (L) 0.91 m (W) 1.9 m (H). The present work is to study different porous opening types for back panel flow inlet to sustain the uniformity of temperature distributions inside the display cabinet. The results show that the suitable number and position of back panel pores accompanied with discharging air curtain will reduce the temperature gradient inner the cabinet. Usually, the higher temperature occurs at the lower level. In order to compare the original distribution of back panel pores and the better selected types studied in this case, the temperature of level four to six decreases about 1℃ for the newly design types of back panel porous distribution. The temperature difference between levels one to six becomes smaller than the original design and shows better cooling performance of the whole display cabinet system. Hence, to provide enough flow rate and figure out the suitable back panel porous distribution will enhance the cooling effect for the lower level zone, and improve the temperature sustaining condition. In this paper, for every 1℃ increase in evaporation temperature that can be achieved in display cabinet, the coefficient of performance (COP) of refrigeration system connected to the display cabinet can be improved by 7.79%.
目錄
中文摘要………………………………………………………………..Ⅰ
ABSTRACT………………………………………………………….....Ⅱ
致謝…………………………………………………………………… Ⅳ
目錄…………………………………………………………………… Ⅴ
圖目錄………………………………………………………………… Ⅷ
表目錄……………………………………………………………….…XII
符號說明…………………………………………………………...…XIII
第一章 導論…………………………………………………………… 1
1-1 前言與簡介………………………………………………...…1
1-2 文獻回顧…………………………………………………...…3
1-2-1 冷卻負荷…………………………………………...…3
1-2-2 熱捲入因素………………………………………...…4
1-2-3 環境溫度及相對濕度的重要性…………………...…4
1-2-4 出風速度影響……………………………………...…5
1-2-5 開放櫃背板開孔影響……………………………...…6
1-2-6 噴流面長寬比和紊流強度對開放櫃的影響……...…6
1-2-7 混合流體模型……………………………………...…7
1-3研究動機與目的…………………………………………...…8
1-4本文架構…………………………...………………………...…9
第二章 問題描述與實驗……………………………………..………. 10
2-1 問題描述…………………………………………………….10
2-2 實驗方法…………………………………………………….11
2-2-1實驗器材……………………………………………...11
2-2-2量測方法……………………………………………...11
2-2-3實驗取值截面之測試………………………………...12
第三章 統御方程式的建立……………………………………………18
3-1基本假設……………………………………………………..18
3-2統御方程式…………………………………………………..18
3-3紊流模式……………………………………………………..20
3-4紊流強度……………………………………………………..21
3-5捲入率………………………………………………………..22
3-6邊界條件……………………………………………………..22
第四章 數值方法………………………………………………………25
4-1 CFD-ACE套裝軟體介紹…………………..………………..26
4-2 CFD-RC的應用…………………..………...………………..27
4-3鬆弛係數與收斂標準…………….………...………………..31
4-3-1鬆弛係數…………………………...…………………31
4-3-2收斂標準…………………………...…………………33
4-4解題流程………………………….………...………………..33
4-5格點方佈……………………………………………………..33
第五章 結果與討論……………………………………………………39
5-1模擬和實驗之驗證…………………………………………..39
5-2討論不同背板開孔型式均溫性研究………………………..40
5-3探討不同蒸發溫度之研究…………………………………..43
5-4總風速於較佳開孔背板之研究…………………..…………45
5-4-1總風速1.4m/s…………………………………………46
5-4-2總風速1.5m/s…………………………………………47
第六章 結論與建議……………………………………………………76
6-1結論…………………………………………………………..76
6-2建議…………………………………………………………..78
參考文獻…...…………………………………………………………...79
附錄……………………………………………………………………..83

圖目錄
圖2-1 開放式冷藏櫃示意圖…………………………………………..14
圖2-2 實驗用開放式冷藏櫃原型機……...…………………….……..14
圖2-3 實驗系統之環控室庫體構造…………………………………..15
圖2-4 T型熱電偶線……………………………….………….….…..15
圖2-5 SIERRA-600系列之熱敏式風速偵測器…..………….….…..16
圖2-6 實驗之開放式展示櫃內熱電偶線分佈情形…..………..……..16
圖2-7 開放式冷藏櫃量測及取值截面示意圖…..…….....……….…..17
圖3-1 邊界條件示意圖…..………….…………………………….…..24
圖4-1 CFD-ACE之流場計算流程圖…..………….…….……..….…..35
圖4-2 模擬之空間及開放展示櫃之模型圖圖…..……...……..….…..36
圖4-3 開放式冷藏櫃網格分佈圖(X-Y)…..………….……..….…..37
圖4-4 開放式冷藏櫃網格分佈圖(Y-Z)…..………….……..….…...38
圖5-1 實驗和模擬氣簾速度驗證比較…..……..….……..…………...51
圖5-2 實驗和模擬氣簾溫度驗證比較…..………….………………...52
圖5-3 實驗和模擬棚架內溫度驗證比較…..………….…..…..……...52
圖5-4 展示櫃前方氣流捲入情形…..………………...…..…………...53
圖5-5 展示櫃側邊氣流捲入情形…..……………..….…..…………...53
圖5-6 展示櫃全封背板速度場……......................................................54
圖5-7 展示櫃全封背板溫度場…..........................................................54
圖5-8 展示櫃全封背板棚架內紅外線熱影像圖……………………..55
圖5-9 展示櫃全封背板棚架內溫度場……………………………......55
圖5-10 展示櫃原始背板棚架內紅外線熱影像圖……………………56
圖5-11 展示櫃原始背板棚架內溫度場…………………………........56
圖5-12 展示櫃case 1背板棚架內紅外線熱影像圖………………….57
圖5-13 展示櫃case 1背板棚架內溫度場……………………...…......57
圖5-14 展示櫃case 2背板棚架內紅外線熱影像圖………………….58
圖5-15 展示櫃case 2背板棚架內溫度場……………………………58
圖5-16 展示櫃case 3背板棚架內紅外線熱影像圖………………….59
圖5-17 展示櫃case 3背板棚架內溫度場……………………………59
圖5-18 展示櫃case 4背板棚架內紅外線熱影像圖………………….60
圖5-19 展示櫃case 4背板棚架內溫度場……………………………60
圖5-20 展示櫃case 5背板棚架內紅外線熱影像圖………………….61
圖5-21 展示櫃case 5背板棚架內溫度場……………………………61
圖5-22 展示櫃case 6背板棚架內紅外線熱影像圖………………….62
圖5-23 展示櫃case 6背板棚架內溫度場……………………………62
圖5-24 開放式展示櫃實際開孔背板示意圖……………...…..……...63
圖5-25 開放式展示櫃實際開孔背板局部示意圖…………………....63
圖5-26 開放式展示櫃開孔背板示意圖…………………………..…..64
圖5-27 開放式展示櫃原始開孔背板示意圖…………...………...…..65
圖5-28 開放式展示櫃較佳化開孔背板示(case 6)意圖………..……..66
圖5-29 實驗不同背板開孔型式之氣簾速度比較………………..…..67
圖5-30 實驗不同背板開孔型式之氣簾溫度比較………………..…..67
圖5-31 實驗不同背板開孔型式之棚架內溫度比較………..….….....68
圖5-32 模擬不同背板開孔型式之氣簾速度比較…...………..….…..68
圖5-33 模擬不同背板開孔型式之氣簾溫度比較………….....….…..69
圖5-34 模擬不同背板開孔型式之棚架內溫度比較…..……………..69
圖5-35 較佳背板開孔於不同蒸發溫度下與原始之氣簾速度比較....70
圖5-36 較佳背板開孔於不同蒸發溫度下與原始之氣簾溫度比較....70
圖5-37 較佳背板開孔於不同蒸發溫度下與原始之棚架內溫度比較64
圖5-38 較佳背板開孔於原始速度及溫度下之棚架內溫度場……....64
圖5-39 較佳背板開孔於蒸發器總風速1.4m/s及溫度增加1℃與原始狀態氣簾速度之比較………………………..………………..72
圖5-40 較佳背板開孔於蒸發器總風速1.4m/s及溫度增加1℃與原始狀態氣簾溫度之比較…………………………..……………..72
圖5-41 較佳背板開孔於蒸發器總風速1.4m/s及溫度增加1℃與原始狀態棚架內溫度之比較………………………..……………..73
圖5-42 較佳背板開孔於蒸發器總風速1.5m/s及溫度增加1℃與原始狀態氣簾速度之比較…………………………..……………..73
圖5-43 較佳背板開孔於蒸發器總風速1.5m/s及溫度增加1℃與原始狀態氣簾溫度之比較……………………………..…………..74
圖5-44 較佳背板開孔於蒸發器總風速1.5m/s及溫度增加1℃與原始狀態棚架內溫度之比較…………………………………..…..74
圖5-45 兩種不同蒸發溫度之理想冷凍循環比較圖……………..…..75
圖5-46 銘騰三呎開放式冷藏櫃耗能圓餅圖……………..…………..75

表目錄
表5-1各背板開孔情形…………………………………..……...…….50
表5-2增加蒸發溫度1℃於各總風速速度與原始蒸發溫度及速度Tcapture、α之比較………………………………………………50
表5-3 R-22之特性表(部分)…………………………..……......…….51
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