Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/1872
標題: 圓管內部連續突出環節對水流與管壁間之熱傳增強
Heat Transfer Enhancement of Repeated Rids in a Circular Tube with Water as the Working Fluid
作者: 王培堂
Wang, Pei-Tang
關鍵字: heat transfer enhancement;熱傳增強;internal rib;Nusselt number;Reynolds number;correlation;內部突出環節;紐塞數;雷諾數;迴歸分析
出版社: 機械工程學系
摘要: 
本實驗研究之目的在於探討圓管中突出環節對水與管壁間熱傳之影響。圓管內具有突出物時,通常會破壞流體流動時之穩定性,因而增加流體與管壁之接觸,進而增強熱傳之效果。此實驗中所採用之測試銅管共計十支,其節徑與內徑比(p/d)值之大小為∞、5.72、5、4.29、2.86、1.43、0.75、0.5及0.304等九種,突出環節深度與內徑比(e/d)之值為0、0.075、0.057、0.05、0.0643、0.0286、0.015及0.143等八種,研究中針對每一支測試管進行量測,以探討不同雷諾數(Re)、p/d與e/d值情況下,Nu值及摩擦阻力係數(f)值之變化情形,量測之結果除了與內部光滑圓管之熱傳性能進行比較外,並經迴歸分析,將Nu與f表示為Re、p/d與e/d之函數。在低雷諾數之操作狀態下,具內部環節管之熱傳增強效果較佳,但隨著雷諾數之增加,其熱傳增強效果會隨之降低。由實驗分析得知p/d值不可太大,否則其熱傳增強效果將不佳。由此研究之結果顯示,此具環節圓管較佳之操作範圍,其e/d值應小於0.075,而p/d值則應小於1.43,如此可使Nu值增加的比率接近於f值增加的比率。

This work deals with the effect of internal repeated ribs in a circular tube on the heat transfer between water and inner wall. With the presence of the internal ribs, the flow stability would be destroyed. This increases the contact between the flow and inner wall, thus the heat transfer is enhanced. Totally ten test tubes, with the values of p/d in the range 0.304 - ∞ and e/d in the range 0 - 0.143, were tested. The obtained heat transfer data were compared to those of a smooth tube. The effects of Re, p/d and e/d on the heat transfer enhancement were investigated. The Nu and f individually were expressed as functions of Re, p/d and e/d through a correlation analysis. For operations with low Reynolds number, the heat transfer enhancement appears quite pronounced. However, this enhancement effect decreases with an increase of the Reynolds number. The result shows that the value of p/d must not be too large for an effective heat transfer enhancement. Based on the result, it shows that, for efficient operations, the values of e/d and p/d individually should be less than 0.075 and 1.43.
URI: http://hdl.handle.net/11455/1872
Appears in Collections:機械工程學系所

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