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Dimensionless multiplier correcting the conductive Heat Transfer Coefficient to account for the Natural Thermal Convection effects in the Annulus:
| (1) |
U = \epsilon_a \cdot \frac{ \lambda_a}{d_{ti} \cdot \ln \frac{d_{ci}}{d_t} }
|
The most popular empirical correlations are:
| (2) |
\epsilon = \begin{cases}
1, & \mbox{if } \ {\rm Ra} < 10^3
\\
0.18 \cdot {\rm Ra}^{0.25}, & \mbox{if } \ {\rm Ra} > 10^3
\end{cases} |
|
| (3) |
\epsilon = \begin{cases}
1, & \mbox{if } \ {\rm Ra} < 10^3
\\
0.105 \cdot {\rm Ra}^{0.3}, & \mbox{if } \ 10^3 < {\rm Ra} < 10^6
\\
0.4 \cdot {\rm Ra}^{0.2}, & \mbox{if } \ {\rm Ra} > 10^6
\end{cases} |
|
See also
Physics / Thermodynamics / Heat Transfer / Heat Transfer Coefficient (HTC) / Heat Transfer Coefficient (HTC) @model
[ Rayleigh number ]
