碩士 / 國立臺灣海洋大學 / 輪機工程系 / 93 / The purpose of this study is to investigate the fully developed laminar flow and convective heat transfer in internally finned tube heat exchangers numerically. The boundary condition of uniform outside wall temperature is assumed. Parameters of the thickness, length, and quantity of fins and thermal conductivity ratio between fin and working fluid are varied to see the change of friction factor as well as Nusselt number.
In the analysis, it is assumed that the fin shape is very close to the real fin configuration. To overcome the coding difficulty in mixed-type boundary conditions, the flow domain was divided into two regions. With each region, the velocity and temperature profile were continuous at the specified adjacent position in the flow. After nondimensionalizing the two-dimensional governing equations for the fully developed laminar flow in internally finned tubes, the flow and temperature fields are solved. Then, the two-dimensional temperature profiles of internal fins are obtained. In this work, the numerical approach employs the finite difference method with S.O.R technique.
The results show that the heat transfer improves significantly if more fins are used; however, the pressure drop turns out to be large in this heat exchanger. As the fin number is smaller than fourteen, there appears a maximum Nusselt number at about 0.8 of the dimensionless fin length. Various velocity and temperature distributions are presented to show this effect. It is expected that the results can be of some help in the prospective design of this heat exchanger.
| Identifer | oai:union.ndltd.org:TW/093NTOU5484006 |
| Date | January 2005 |
| Creators | Jui-Ching Hsiao, 蕭瑞慶 |
| Contributors | Rong-Hua Yeh, 葉榮華 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 82 |
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