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In Forced Fluid Convection the Nusselt number becomes dependant on Reynolds number
and Prandtl number :
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| body | --uriencoded--\mbox%7BNu%7D = f (\mbox%7BRe%7D, \mbox%7BPr%7D) |
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| {\rm Nu}=3.66 + \frac{ 0.065 \cdot {\rm Re} \cdot {\rm Pr} \cdot {D/L} }{ 1 + 0.04 \cdot ({\rm Re} \cdot {\rm Pr} \cdot {D/L})^{2/3} } |
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Laminar flow in pipeline |
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| {\rm Nu}=\frac{ (f/8) \, ({\rm Re} - 1000) {\rm Pr} }{ 1 + 12.7 \, (f/8)^{1/2} \, ({\rm Pr}^{2/3} -1) } |
is Darcy friction factor | |
laminar the Nusselt number (Nu) becomes also dependant on friction with wall, quantifiable by Darcy friction factor | LaTeX Math Inline |
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body | f | , and can be estimated through empirical correlation (Gnielinski0.5| %7B\displaystyle 3000\leq \mathrm |
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%7BPr%7D 2000 %7B\displaystyle 3000 %7BRe%7D 5\cdot 10%5e%7B6%7D%7D| |
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| {\rm Nu}=0.3 + \frac{0.62 \, \mbox{Re}^{1/2} \, \mbox{Pr}^{1/3} }
{\left[ 1+ (0.4/\mbox{Pr})^{2/3} \right]^{1/4}}
\left[ 1 + \left( \frac{\mbox{Re}}{282000} \right)^{5/8}\right]^{4/5} |
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| body | --uriencoded--\mbox %7BRe%7D \cdot \mbox %7BPr%7D \geq 0.2 |
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Accuracy | LaTeX Math Inline |
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| body | --uriencoded--\sim 20 \%25 |
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See also
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Physics / Thermodynamics / Heat Transfer
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