We have an exciting announcement about badges coming in May 2025. Until then, we will temporarily stop issuing new badges for course completions and certifications. However, all completions will be recorded and fulfilled after May 2025.
Fluids

Fluids

Topics related to Fluent, CFX, Turbogrid and more.

ERROR: Latent heat cannot be less than zero!

    • abdullahhassan
      Subscriber

      Hi,

      I am having an issue in ANSYS simulation. I am trying to do condensation of water vapor to water liquid but when I initialize the solution, it says latent heat cannot be less than zero. 

      I tried to search online & it comes to my knowledge that it is related to enthalpy. 

      as enthalpy of liquid is -2.858e+08 and 

      enthalpy for vapor is -2.418e+08 at standard temperature. so change in enthalpy is coming negative which means the latent heat is less than zero. 

      Can anyone help me, how to resolve this issue or what values I need to choose for enthalpies in this case.

       

      NOTE: I already did the simulation for water boiling/evaporation and I didn't face such issue in that particular case. 

    • Rob
      Forum Moderator

      If you're using the Evaporation/Condensation model the To and From phase matters. I always have to check the manual, but if you currently have the vapour in the To field switch that to the From field. 

    • abdullahhassan
      Subscriber

      I understand that, what I am trying to do is Condensation of water vapor at 100 C, 

      for this case 

      From phase should be "from vapor' 

      to phase should be like " to liquid".

      when I did this, it said latent heat can not be less than zero. 

      but when I do the opposite 

      from = liquid

      to = vapor 

      system doesn't shows any warning. Infact it also did the condensation upon putting water vapor at inlet volume fraction as 1. 

       

       

      I don't understand that. can you please help

    • Rob
      Forum Moderator

      It's because Fluent doesn't know which material is gas and which is liquid. All Fluent does is look at the material data and then add/remove energy based on the formation enthalpy. To get around this, the To and From phase definitions matter: hence my comment about checking. 

       

Viewing 3 reply threads
  • The topic ‘ERROR: Latent heat cannot be less than zero!’ is closed to new replies.