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Nusselt number, gas to duct

Symbol
$\mathrm{Nu}_{gd}$
Formulae
$none$Riser closed at both ends (Hartlein & Black)
$none$Riser open at both ends, $Ra$ >= 10^5 (Hartlein & Black IIa)
$0.63\left(\mathrm{Gr}_{gd} \mathrm{Pr}_{gas}\right)^{0.25}$Riser open at both ends, 0.1 ≤ $Ra$ < 10^5 (Hartlein & Black IIb)
$\frac{1}{6.92} \left(\mathrm{Gr}_{gd} \mathrm{Pr}_{gas}\right)^{0.28}$Riser open at top and closed at bottom, $10^{4.95} ≤ Gr \cdot Pr ≤ 10^{6.15}$ (Hartlein & Black)
$none$Riser closed at both ends (Anders)
$\frac{1}{9.07} \mathrm{Gr}_{gd} \mathrm{Pr}_{gas}$Riser open at both ends, $Gr \cdot Pr < 10$ (Anders)
$0.62\left(\mathrm{Gr}_{gd} \mathrm{Pr}_{gas}\right)^{0.25}$Riser open at both ends, otherwise (Anders)
$\frac{\mathrm{Gr}_{gd} \mathrm{Pr}_{gas}}{400}$Riser open at top and closed at bottom, $Gr \cdot Pr < 200$ (Anders)
$0.35\left(\mathrm{Gr}_{gd} \mathrm{Pr}_{gas}\right)^{0.28}$Riser open at top and closed at bottom, otherwise (Anders)
Related
$\mathrm{Gr}_{gd}$
Grashof number, gas to duct
$\mathrm{Pr}_{gas}$
Prandtl number for gas
Used in
$h_{conv,gd}$
Convection heat transfer coefficient, gas to duct [W/(K.m$^2$)]
$W_{conv,gd}$
Convection heat transfer, gas to duct [W/m]