碩士 / 中原大學 / 機械工程研究所 / 86 / In the present study 59 samples of fin-and-tube heat exchangers having different type of fin configurations were test. The effects of the number of tubes, fin pitches and tube diameters on the thermal-hydraulic characteristics wereinvestigated. Results are presented as Colburn j factor and fanning friction factor f against Reynolds number ReDc based on the fin collar diameter Dc in the range of 300 to 8,000. It's found that heat transfer performances were strongly related to the flow characteristics. Furthermore, fin pitchplays the most important role on the vortex formation. The "maximum phenomenon" of the Colburn j factors for multi-row coilsat low Reynolds numbers is related to the smaller fin spacing and vortex formation. The louver surface can break and renew the thermal boundaryof the air flow. Consequently, higher heat transfer and friction are expected as compared to those for the fin with plain surface. Based on the test results, general correlations for plain and louver fin-and-tube heat exchangers were proposed. These correlations have demonstrated their capabilities to predict the available data satisfactorily.
| Identifer | oai:union.ndltd.org:TW/086CYCU0489003 |
| Date | January 1998 |
| Creators | Chi Kuan-yu, 紀冠宇 |
| Contributors | Chang Yeon-pun, 張永鵬 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 0 |
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