網格式鰭片尺寸與含油冷媒物性之沸騰性能參數研究

A Boiling Study of Mesh-Size and Properties of Refrigerant Mixture Oil on Mesh-cover fins

吳忠駿(Chung-Chun Wu)

指導教授 ： 簡良翰

國立臺北科技大學/機電學院/能源與冷凍空調工程系碩士班/碩士(2009年)

https://doi.org/10.6841/NTUT.2009.00083

摘要

本研究主旨探討在含油冷媒中以不同的網格數目纏繞於鰭片管上之池沸騰熱傳性能研究。本實驗工作流體為R-134a，測試之飽和溫度為5℃與10℃，使用之潤滑油為EMKARATE RL -150S，含油濃度為1%與2%；鰭片管之鰭片密度為60FPI，鰭片高為0.2mm與0.4mm；而纏繞網格目數分別有#80目紅銅與#100目黃銅，其纏繞後之網格孔隙寬範圍約0.15~0.32mm。實驗結果發現：鰭片管纏繞 #80 ~ #100目的網格後，可使鰭片表面形成許多大小適當的氣孔，並且氣體較易殘留於渠道內，而大幅度增加熱傳性能。當飽和溫度5℃與10℃時，在含油濃度1%與2%，所有測試管中以60FPI (Fins Per Inch)、鰭片高0.4mm之鰭片管纏上#100目黃銅網格效果最佳；相對於為纏網格之60FPI鰭片管在含油濃度1%之熱傳性能，飽和溫度為5℃與10℃時，其平均熱傳性能分別提升2.77與2.57倍。同一熱傳管在含油率1%之熱傳性能高於含油率0%或2%；但在含油濃度2%時，纏繞 #80目紅銅，熱傳性能高於純冷媒與含油濃度1%。含油濃度1~2 %時，被#100目黃銅網格纏繞之鰭片高由0.2mm增加為0.4mm時，其熱傳性能在飽和溫度5℃與10℃時分別增加1.52與1.76倍。本實驗結果顯示鰭片管纏繞#80~#100目的網格後，可在含油環境下發揮高沸騰效率之特性，適用於高效率空調主機之蒸發器。

關鍵字

氣泡 ； 沸騰 ； 網格 ； 鰭片 ； 測試管 ； 含油濃度

並列摘要

This study investigates a new enhanced boiling surface, which is made by wrapping wire mesh on finned tubes. Pool boiling performance of the new enhanced tubes has been tested in Refrigerant-134a and an R-134a/lubricant (1% and 2% lubricant mass fraction) mixture at 5oC and10oC saturation temperatures. Brass or copper mesh of 80 and 100 meshes per inch was wrapped on finned tubes of 60 FPI (fins per inch). The fin heights were either 0.2 mm or 0.4 mm. The test results show that the mesh covered fin tubes significantly enhanced the boiling performance by forming many pores of proper sizes on the surface and sustaining vapor in the tunnels formed by the mesh and fins. For 1% and 2% lubricant concentration, the enhanced surface formed by wrapping one layer of #100 (100 mesh per inch) brass mesh on the 0.4 mm fin height, 60 FPI tube results in the best boiling performance at 5, and 10oC. The boiling heat transfer coefficient of this surface is enhanced by 2.77 and 2.57 folds in average as compared with the fin tube without mesh at 5oC and 10oC saturation temperature. For each tube, the boiling heat transfer coefficient in 1% lubricant/R-134a mixture is generally greater than that in pure R-134 or 2% lubricant concentration, but the enhanced surface formed by one layer of #80 (800 mesh per inch) copper mesh had a greater performance for 2% lubricant concentration than pure R-134a or 1% lubricant cencentration.

並列關鍵字

bubble ； boiling ； mesh ； fin ； tube ； R-134a/lubricant mixture

參考文獻

[3] Kedzierski, M. A., 2001, “The Effect of Lubricant Concentration Miscibility and Viscosity on R134a Pool boiling,” Int. J. of Refrigeration, Vol., 24, no. 4, pp. 348-366.

[4] 黃浩林、簡良翰2008“網格式鰭片之蒸發性能研究“國立台北科技大學碩士學位論文

[6] Chien, L. H., and Webb, R. L., 1998, “Parametric studies of nucleate pool boiling on structured surfaces, part I: Effect of tunnel dimensions,” Journal of Heat Transfer, Vol. 120, pp. 1042-1048.

[7] Chien, L. H., and Webb, R. L., 1998, “Parametric studies of nucleate pool boiling on structured surfaces, part II: Effect of pore diameter and pore pitch,” Journal of Heat Transfer, Vol. 120, pp. 1049-1054.

[8] Webb, R. L., 2004, “Odyssey of the Enhanced Boiling Surface,” J. of Heat Transfer, 126 (6): 1051-1059.