Fluids

Fluids

Mass Fraction to PPM

    • Carly
      Subscriber
      Hey
      I want to convert from mass fraction of a species into PPM in a UDF or custom field function. I saw many define it as mass fraction x 10^6 while others define it as mass fraction x density of mixture x 10^6 / density of species. Would you please let me know which one is correct or if there is another way. Thanks
    • DrAmine
      Ansys Employee

      You need to stick to one of the definitions from the literature: ppm mole or ppm weight or ppm volume or..... All definitions are correct you need to select one which fits your needs. You have to make that decision!

    • Dino
      Subscriber

      If volume: PPM = mass fraction * density_mix * 10^6 / density_species


      If weight: PPM = mass fraction * 10^6


      If mole: PPM = mass fraction * 10^6 * MW_mix / MW_species


      In UDF: you can access the mass fraction via C_YI(c, t, i) where i is the species index. C_R(c, t) for the density of the mixture. I did not need to call the molecular weight (MW) before so I am not sure how to access it through the UDF. Hope this helps. 


       


       

    • jacklien
      Subscriber
      I suggest to use ppm to percent calculatornn
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