碩士 / 國立成功大學 / 機械工程學系碩博士班 / 97 / The finite difference method in conjunction with the least-squares scheme and experimental temperature data is proposed to predict the average overall heat transfer coefficient, heat transfer rate, and wet fin efficiency on a vertical annular circular fin of annular-finned tube heat exchangers for various fin spacings and a quantities of spray. The overall heat transfer coefficient on this annular circular fin is assumed to be non-uniform. Thus the whole plate fin is divided into several sub-fin regions in order to predict the average overall heat transfer coefficient、heat transfer rate and wet fin efficiency from the knowledge of the measured temperatures. The unknown overall heat transfer coefficient on each sub-fin region can be assumed to be constant. The results show that the average overall heat transfer coefficient increases with increasing the fin spacing, and the wet fin efficiency decreases with increasing the fin spacing in natural convection. The average overall heat transfer coefficient and wet fin efficiency can approach their corresponding asymptotical value obtained from a single annular circular fin for the fin spacing above a certain value. The heat transfer rate seems to increase with increasing the fin spacing.
In forced convection, the heat transfer rate and the average overall heat transfer coefficient increase with increasing the quantities of spray, and the wet fin efficiency decreases with increasing the quantities of spray. When air speed and quantities of spray are fixed, the average overall heat transfer coefficient increase with increasing the fin spacing, and the wet fin efficiency decreases with increasing the fin spacing. The average overall heat transfer coefficient and wet fin efficiency can approach their corresponding asymptotical value obtained from a single annular circular fin for the fin spacing above a certain value. When air speed and quantities of spray are fixed, the heat transfer rate increase with increasing the fin spacing .In order to evidence the accuracy and reliability for the present inverse scheme, we make a comparison to the present results and previous results.
| Identifer | oai:union.ndltd.org:TW/097NCKU5490036 |
| Date | January 2009 |
| Creators | Yi-Yu Chen, 陳一裕 |
| Contributors | Han-Taw Chen, Jenq-Shing Chiou, 陳寒濤, 邱政勳 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 80 |
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