Nusselt number tray—air

For horizontal surfaces the Nusselt number is defined by [13]

Symbol
$\mathrm{Nu}_{tray}$
Formulas
$0.54{\mathrm{Ra}_{ext}}^{0.25}$tray top cover—air (CA)
$0.27{\mathrm{Ra}_{ext}}^{0.25}$tray bottom—air (BA)
$0.68+\frac{0.67{\mathrm{Ra}_{ext}}^{0.25}}{\left(1+\left(\frac{0.492}{\mathrm{Pr}_{gas}}\right)^{\frac{9}{16}}\right)^{\frac{4}{9}}}$tray side—air (SA)
Related
$\mathrm{Pr}_{gas}$