# 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

 $$\large{ Be = \frac{ \Delta p \; l^2 }{ \mu \; \alpha } }$$

### Where:

 Units 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 $$\large{\frac{ft^2}{sec}}$$ $$\large{\frac{m^2}{s}}$$