# Jakob Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Jakob number, abbreviated as Ja, a dimensionless number, is the ratio of sensible latent heat absorbed or released during liquid vapor phase change.

## Jakob Number formula

 $$\large{ Ja = \frac{ c_p \; \left( T_s \;-\; T_{sat} \right) }{\Delta h_f} }$$

### Where:

$$\large{ Ja }$$ = Jakob number

$$\large{ c_p }$$ = constant pressure at specific heat

$$\large{ \Delta h_f }$$  = evaporation enthalpy change

$$\large{ T_{sat} }$$ = temperature saturation point

$$\large{ T_s }$$ = total stagnation temperature