3 replies to this topic

[shahidulislam48]

Hello,

 

As far as I know, Cp/Cv is a parameter for gas. But during the simulation in ASPEN HYSYS if I pick up a liquid stream and enter necessary parameters like P, T and mole or mass fraction then it shows the corresponding parameters of liquid and I also get the value of Cp/Cv.

 

I am not really getting the point about this parameter in case of liquid.

 

I need help regarding this.

 

Many Thanks

 

[shan]

Cp:  Specific heat at constant pressure.

Cv:  Specific heat at constant volume.

 

For ideal liquid (volume does not vary with pressure), Cp = Cv and Cp/Cv =1.  However, I believe that your liquid specified in Hysys is not the ideal liquid.  You may prove this by increasing your original liquid stream pressure by 1000 psi to see if the value of stream Act. Liq. Flow is still identical with the value of your original liquid stream.  Therefore, Cp>Cv, Cp/Cv>1.  

[serra]

I am not sure about real usefulness of ratio cp/cv for liquid phase,

however you can probably export (separately)  values of cp, cv, isothermal compressibility, speed of sound etc. for liquid phase,

I have a different software (PRODE PROPERTIES) which exports the same properties for both gas and liquid phase,

probably your software does the same.

When calculating properties for liquid phases (for example cv) make sure to select a suitable model,

there are threads at cheresources discussing this topic

(i.e. errors with different EOS models)

[shahidulislam48]

Thanks shan, serra for your valuable information.