UM
The effect of inner surface roughness and heating on friction factor in horizontal mini-tubes
Tam L.M.2; Tam H.K.2; Ghajar A.J.3; Ng W.S.2; Wu C.K.2
2014
Source PublicationProceedings of the 15th International Heat Transfer Conference, IHTC 2014
AbstractAccording to the recent literature survey, it was concluded that the friction factor in mini-and micro-tubes could be predicted accurately by using macro-scale theory. However, certain issues should be further investigated. They are: (a) the effect of inner surface roughness and (b) the effect of mini-and micro-tube diameters on the start and end of the transition region. Moreover, only a few studies investigated the effect of heating on friction factor in mini-and micro-tubes, especially, in the transition region. Therefore, an experimental setup was built in this study to measure the pressure drop for the horizontal mini-and micro-tubes under the isothermal and uniform wall heat flux boundary conditions. Distilled water was used as the test fluid. Seven stainless steel minitubes (2000μm to 508μm in inner diameters) with various surface roughness values (1.94μm to 5.30μm) were used as the test section. The experimental results clearly showed the effect of heating and roughness on friction factors in the laminar, transition, and turbulent regions. For the friction factors under isothermal condition, the mini-tubes had a narrower transition range due to the roughness when compared to the macro-tubes. For the friction factor under heating condition, the laminar data and the start of transition were different from the isothermal case. Under heating condition, the narrower transition range due to the roughness was also observed in the mini-tubes. However, the effect of heating was not seen on the end of transition and in the turbulent region.
KeywordConvection Friction factor Inner surface roughness Mini-tube Nano/Micro scale measurement and simulation
URLView the original
Language英語
Fulltext Access
Document TypeConference paper
CollectionUniversity of Macau
Affiliation1.Institute for the Development and Quality
2.Universidade de Macau
3.Oklahoma State University - Stillwater
Recommended Citation
GB/T 7714
Tam L.M.,Tam H.K.,Ghajar A.J.,et al. The effect of inner surface roughness and heating on friction factor in horizontal mini-tubes[C],2014.
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