How do you specify the latent heat for gas-liquid phase change in Fluent software?
The standard state enthalpies of vapor and liquid phase are set such that their difference equals to latent heat of vaporization. The unit of standard state enthalpy is kj/kmol, and usually the latent heat value is available in kj/kg. While specifying it here, multiply that value by molecular weight.
We recommend using the saturation temperature as the reference temperature. You can use the values of standard state enthalpy and other material properties at this saturation temperature for vapor and liquid or building their difference, which leads to the latent heat at the saturation temperature.
If the values of standard state enthalpy, as well as the isobaric heat capacities, are known at another temperature, we can set this known temperature as reference temperature and employ the related enthalpy and other material property values. In this case, we have to provide the system pressure.