Biot Number

Written by Jerry Ratzlaff. Posted in Dimensionless Numbers

Biot Number is a dimensionless number which is the ratio of internal thermal resistance of solid to fluid thermal resistance.   This is used for heat transfer between fluids and solids.

FORMULA

\(Bi=\frac{hl_c}{k}\)

\(Bi=\frac{h_D l_c}{D}\)

Where:

\(Bi\) = biot number

\(h\) = film coefficient or heat transfer coefficient or convective heat transfer coefficient

\(l_c\) = characteristic length

\(k\) = thermal conductivity of the body

\(c_m\) = mass transfer coefficient

\(c_d\) = diffusion coefficient