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What is Concentric Annulus flow?
What is Concentric Annulus flow?
This is the type of flow where there is a pipe within another pipe, making an annulus (think doughnut!) shape.
Convection heat transfer can take place from the inner tube to the outer, or the outer tube to the inner. This is represented by the convection coefficients:
Where o and i is outer and inner, and Tm is the mean temperature
The Nusselt numbers for each side are given by:
Where the hydraulic diameter
Special Cases
Nusselt numbers for fully developed laminar flow in a circular tube annulus with one surface insulated and the other at a constant temperature
0
0.05
0.10
0.25
0.5
≈1.00
-
17.46
11.56
7.37
5.74
4.86
3.66
4.06
4.11
4.23
4.43
4.86
For fully developed turbulent flow, you can use the normal circular tube correlations with Dh instead of D.
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