碩士 / 國立雲林科技大學 / 機械工程系碩士班 / 94 / In the present study, nine plate fin-and-tube heat exchangers were tested. In the geomorphic diameter of heat exchangers, the corresponding longitudinal tube pitches and transverse tube pitches for the tested samples were 33 mm and 38.1 mm, respectively. The nominal tube diameter for all the samples were 15.8mm, and there are three different types of the number of tube rows and fin pitches including 2, 4 and 8-rows and 2.12 mm, 2.54 mm and 3.17 mm for fin pitches. The effect of the number of row and fin pitches of the air-side heat transfer and friction performance were experimentally investigated. According to results, it was found that the fin pitch has negligible effect on both heat transfer and friction factor in 2 and 4 rows heat exchangers. However, it was observed the Colburn j-factor at low Reynolds numbers drops down for plate fin-and-tube exchangers at lager number of tube row and smaller fin pitch form this experiment that is the same with Wang’s definition of Maximum phenomena. The lowest j factor compared with the highest within 80% , the mean deviation of j is between 10~30% and f is between 0~20%.
A correlation for fin-and-tube heat exchanger having plain geometry is proposed in this study. We provided a correct factor to upgrade the development correlation. A total of 83 samples containing approximately 739 points for j factor and 593 points for f factor were included the new correlation. The proposed j factor can describe 89.6% of the database within +15%, while the proposed f factor can correlate 86.7% of the database within +15%. The mean deviation of Colburn factor is 7.47 %, and friction factor is 8.22%.
| Identifer | oai:union.ndltd.org:TW/094YUNT5489018 |
| Date | January 2006 |
| Creators | Young-Chang Liu, 劉永銓 |
| Contributors | Ing Youn Chen, 陳英洋 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 69 |
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