# Bejan Number - Heat Transfer

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Bejan number - heat transfer, abbreviated as Be, a dimensionless number, is the pressure drop along a channel of length.

## Bejan Number - Heat Transfer formula

$$\large{ Be = \frac{ \Delta p \; l^2 }{ \mu \; \alpha } }$$
Symbol English Metric
$$\large{ Be }$$ = Bejan number $$\large{dimensionless}$$
$$\large{ l }$$ = length of channel $$\large{ft}$$ $$\large{m}$$
$$\large{ \mu }$$  (Greek symbol mu) = dynamic viscosity $$\large{\frac{lbf-sec}{ft^2}}$$ $$\large{ Pa-s }$$
$$\large{ \Delta p }$$ = pressure drop $$\large{\frac{lbf}{in^2}}$$ $$\large{Pa}$$
$$\large{ \alpha }$$  (Greek symbol alpha) = thermal diffusivity $$\large{\frac{ft^2}{sec}}$$  $$\large{\frac{m^2}{s}}$$