碩士 / 國立臺北科技大學 / 能源與冷凍空調工程系碩士班 / 97 / 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.
| Identifer | oai:union.ndltd.org:TW/097TIT05703008 |
| Date | January 2009 |
| Creators | Chung-Chun Wu, 吳忠駿 |
| Contributors | 簡良翰 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 70 |
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