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研究生:林弘毅
研究生(外文):LIN, HONG-YI
論文名稱:表面改質熱交換器之冷凝熱傳與壓降可視化研究
論文名稱(外文):Experimental Investigations of Condensation Heat Transfer and Pressure Drop Visualization on Surface Modified Heat Exchanger
指導教授:吳友烈
指導教授(外文):WU, YU-LIEH
口試委員:楊愷祥吳世國
口試委員(外文):YANG, KAI-SHINGWU, SHIH-KUO
口試日期:2020-07-29
學位類別:碩士
校院名稱:國立勤益科技大學
系所名稱:冷凍空調與能源系
學門:工程學門
學類:其他工程學類
論文種類:學術論文
論文出版年:2020
畢業學年度:108
語文別:中文
論文頁數:72
中文關鍵詞:熱交換器濕盤管冷凝
外文關鍵詞:Heat exchangerWet coilCondensation
相關次數:
  • 被引用被引用:0
  • 點閱點閱:159
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  • 收藏至我的研究室書目清單書目收藏:0
本研究探討不同鰭片表面及鰭片間距之鰭管式熱交換器在不同風速及相對濕度條件下對熱傳率及壓降之影響,並利用濕盤管分析方法探討表面改質前後鰭片表面冷凝液膜厚度與熱質傳間之關係。
實驗結果顯示乾盤管狀態下,表面改質對熱交換器的熱傳及壓降皆無影響,在小鰭片間距的濕盤管狀態下,疏水表面熱交換器與純銅熱交換器相比熱傳率提升14 %,高風速條件下冷凝液滴成長緩慢,疏水表面的排水效果降低,熱傳提升效率隨風速提高逐漸降低,表面改質對壓降影響部分,疏水表面之滴狀冷凝會填滿空氣流道形成水橋,導致疏水表面之熱交換器壓降皆遠大於純銅表面熱交換器,但疏水表面具有較佳液滴滑落頻率,在相同時間內與純銅表面相比,疏水表面的表面刷新頻率較純銅表面高。
This study explored the influences of fin-tube heat exchangers with various types of fin surface and fin spacing on thermal conductivity and pressure drop under different air velocities and levels of relative humidity. In addition, the wet-coil method was adopted to examine the relationship between heat and mass transfer and the thickness of condensate film on fin surface before and after surface modification. A microscope was employed to perform a visualization analysis on condensate droplets and to observe the growth rate and thickness of condensate film on fin surface. The experiment results showed that for the dry coil, surface modification had no influence on thermal conductivity and pressure drop of heat exchangers. For the wet coil with small fin spacing, compared with the pure-copper heat exchanger, the thermal conductivity of the hydrophobic-surface heat exchanger increased by 14%. As the air velocity increased, the growth of condensate droplets slowed down, the drainage effect of the hydrophobic surface reduced, and thermal conductivity decreased. Regarding the influence of surface modification on pressure drop, condensate droplets on the hydrophobic surface filled the air channel to form a water bridge. Accordingly, the pressure drop of the hydrophobic-surface heat exchanger was much greater than those of the copper-surface heat exchanger. However, compared with the pure-copper surface, the hydrophobic surface exhibited more satisfactory droplet-sliding frequency and, for the same duration, a higher surface-refreshing frequency.
摘要 i
Abstract ii
誌謝 iv
目錄 v
圖目錄 viii
表目錄 xi
符號說明 xii
第一章 緒論 1
1-1前言 1
1-2文獻回顧 2
第二章 研究相關理論 10
2-1熱傳模式 10
2-2冷凝模式 11
2-3接觸角 12
2-4接觸角遲滯 13
2-5濕盤管分析 14
2-4冷凝面積比 24
第三章 實驗規劃與建構 25
3-1實驗方法 25
3-1-1實驗規劃與架構 25
3-2實驗參數 27
3-2-1乾盤管 27
3-2-2濕盤管 27
3-3鰭片表面改質方法 28
3-4實驗樣品規格 29
3-5不準度計算 31
第四章 研究結果討論與分析 34
4-1表面接觸角量測 34
4-1-1銅鰭片表面 34
4-1-2疏水(PDMS)鰭片表面 34
4-2鰭片間距Fp=1.0mm冷凝熱傳實驗結果 35
4-2-1乾盤管熱傳實驗分析結果 35
4-2-2濕盤管熱傳實驗分析結果 36
4-2-3不同相對濕度對熱交換器之壓降實驗結果 39
4-2-4不同鰭片表面對熱交換器之動態壓降分析 54
4-2-5不同鰭片表面對冷凝面積比之影響 55
4-2-6不同相對濕度對濕鰭片效率之影響 56
4-3鰭片間距Fp=3.0mm冷凝熱傳實驗結果 57
4-3-1乾盤管熱傳實驗分析結果 57
4-3-2濕盤管熱傳實驗分析結果 58
4-3-3不同相對濕度對熱交換器之壓降實驗結果 60
第五章 結論與建議 66
5-1結論 66
5-2建議 67
第六章 參考文獻 68

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