changes.mady.by.user Arthur Aslanyan (Nafta College)
Saved on Nov 25, 2019
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\mbox{Nu}_D= \left[ 0.825 + \frac{0.387 \, \mbox{Ra}_D^{1/6}}{ \left[ 1+ (0.492/\mbox{Pr})^{9/16} \right]^{8/27}} \right]^2
Churchill and Chu
All All flow regimes in regimes in pipelines
\mbox{Nu}_L= 0.68 + \frac{0.663 \, \mbox{Ra}^{1/4}}{ \left[ 1+ (0.492/\mbox{Pr})^{9/16} \right]^{4/9}}
Laminar flowsflow
\mbox{Nu}_L= \left[ 0.6 + \frac{0.387 \, \mbox{Ra}^{1/6}}{ \left[ 1+ (0.559/\mbox{Pr})^{9/16} \right]^{8/27}} \right]^2
{\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} }
Mills
Laminar flow in pipeline with diameter
{\rm Nu}=0.023 \cdot \mbox{Re}_D^{3/4} \cdot \mbox{Pr}^n
Dittus-Boelter
Turbulent flow in pipeline
{\rm Nu}=\frac{ (f/8) \, ({\rm Re} - 1000) {\rm Pr} }{ 1 + 12.7 \, (f/8)^{1/2} \, ({\rm Pr}^{2/3} -1) }
Gnielinski
Transitional flow and turbulent flow in rough pipeline
{\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}
Churchill–Bernstein
All flow regimes in pipelines
Accuracy