碩士 / 國立成功大學 / 機械工程學系 / 104 / The present study applies the inverse method and computational fluid dynamics commercial software in conjunction with the experimental method to predict the heat transfer and fluid flow characteristics of annular finned tube heat exchangers. The effects of some physical parameters such as fin spacing, air velocity and tube diameter are examined. Due to the heat transfer coefficient on the fin is non-uniform, the fin is divided into several sub-regions. Later, the inverse method applied finite difference method in conjunction with the least-squares scheme and the experimental data to estimate the heat transfer coefficient on the fins.
The results shows that, there is a low velocity wake region at downstream of the tube. Therefore the heat transfer coefficient at the upstream region of the fin is higher than the downstream region of the fin. The increase of fin spacing and air velocity can improve the cooling effect of the fins. In natural convection, the heat transfer coefficient increases with the increase of the fin to tube diameter ratio. For a fixed air flow velocity, the higher the fins and the closer they are to one another, the lower the heat transfer coefficient on the fin is. Numerical simulation result obtained using zero-equation and RNG k-ε turbulence flow model is more accurate for natural convection and mixed convection respectively.
| Identifer | oai:union.ndltd.org:TW/104NCKU5489089 |
| Date | January 2016 |
| Creators | Yu-JieChiu, 邱毓絜 |
| Contributors | Han-Taw Chen, 陳寒濤 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 122 |
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