# Jakob Number

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:

Units |
English |
Metric |

\(\large{ Ja }\) = Jakob number | \(\large{ dimensionless }\) | |

\(\large{ c_p }\) = constant pressure at specific heat | \(\large{\frac{lbf}{in^2}}\) | \(\large{Pa}\) |

\(\large{ \Delta h_f }\) = evaporation enthalpy change | \(\large{\frac{Btu}{lbm}}\) | \(\large{\frac{kJ}{kg}}\) |

\(\large{ T_{sat} }\) = temperature saturation point | \(\large{F }\) | \(\large{ K }\) |

\(\large{ T_s }\) = total stagnation temperature | \(\large{F }\) | \(\large{ K }\) |