Heat transfer and bubbles movement of two-side and one-side heating subcooled flow boiling in vertical narrow channels
- Authors: Pan, Liang-Ming , Jen, Tien-Chien , He, Chuan , Xin, Ming-dao , Chen, Qing-hua
- Date: 2006
- Subjects: Subcooled flow boiling , Bubble behaviour , Heat transfer
- Type: Article
- Identifier: uj:5267 , http://hdl.handle.net/10210/14936
- Description: The channels employing hydraulic diameters between 200 m and 3 mm are referred to as minichannels 1 . Compared with conventional channels from the view of the heat transfer, narrow and microchannels have significant heat transfer enhancement characteristics 2,3 . With a smooth internal surface and scouring by flowing fluid, the dirt formed on the surface of the channel wall can be easily removed and the fouling problem is not as serious as the deformed channels. Moreover, heat transfer elements can be easily assembled to compact devices. Since the innovative work of Ishibashi et al. 2 , narrow channels have been adopted extensively in engineering applications, e.g., microelectronic cooling 4,5 , advanced nuclear reactor 6,7 , cryogenic, aviation, and space technology. Because the bubble size has approached the dimension of the channel, the size of the flow channel plays a critical role on the flow boiling heat transfer. This results in that the bubble in the narrow channel acts very differently from those in the non-narrow channel.
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Heat transfer performance in 3D internally finned heat pipe
- Authors: Liao, Quan , Jen, Tien-Chien , Chen, Qing-hua , Li, Longjian , Cui, Wenzhi
- Date: 2007
- Subjects: Heat pipes , Heat transfer , Finned tubes
- Type: Article
- Identifier: uj:5276 , http://hdl.handle.net/10210/14945
- Description: An experimental study of heat transfer performance in 3D internally finned steel-water heat pipe was carried out in this project. All the main parameters that can significantly influence the heat transfer performance of heat pipe, such as working temperature, heat flux, inclination angle, working fluid fill ratio (defined by the evaporation volume), have been examined. Within the experimental conditions (working temperature 40 C–95 C, heat flux 5.0 kw/m2–40 kw/m2, inclination angle 2–90 ), the evaporation and condensation heat transfer coefficients in 3D internally finned heat pipe are found to be increased by 50–100% and 100–200%, respectively, as compared to the smooth gravity-assisted heat pipe under the same conditions. Therefore, it is concluded that the special structures of 3D-fins on the inner wall can significantly reduce the internal thermal resistance of heat pipe and then greatly enhance its heat transfer performance.
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