The Study of Friction and Heat Transfer Characteristics of Microchannel Flows.
| Autor: | Guan Ru Chen, 陳冠儒 |
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| Rok vydání: | 2000 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 88 The object of this research thesis is to investigate the behavior of nitrogen flow in micro-channels and its characteristics of friction as well as heat transfer. By solving the problems numerically and comparing the results with theoretical solutions and experimental data, we can validate the accuracy of our results. The proposed model assumes the flow is a continuum but employs a slip condition on the channel wall. When the channel size becomes smaller and smaller, the phenomenon of gaseous flow gets more complicated. At this time we should consider the flow not only as a continuum but also as a slip flow. The experimental data show that the friction factor is smaller than that in larger channels, and the heat transfer efficiency is better. Similar results appear in our research. So that we may say the assumption of slip flow is proper. Also the results show that the slip boundary, which is the result of incomplete momentum and energy exchanges between the impinging gas molecules and the walls, has decisive effects on velocity and therefore the mass flow rate of the flow. The adoption of the compressible boundary-layer equations in the numerical solutions is much more efficient than solving the compressible Navier-Stokes equations, yet the accuracy is satisfactory. The present work discusses only the laminar flow region, it can’t be used to explain the flow behavior in turbulent flow region. For the future work, some turbulent models can be added to the numerical program to simulate turbulent flows. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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