[evcelica]

It is just a curve fit for specific heat at Zero pressure with respect to temperature. So those coefficients in that equation are the a1 through a5 values.

RCO2 is the specific gas constant. CPo is specific heat at zero pressure.

I would make your own curve fit depending on your temperature range.



Also, using an .rgp file would be more accurate, I don't know how much difference it would make though, and it would be much more involved if you have never done it before.

[Fresher]

Thank you very very much,evcelica.

I think I know what you've suggested.These days,I've found a paper in which the Zero Pressure Coefficients Method is used,and the working fluid is the mixture of R245fa and R123.

But I still wonder what "the Zero Pressure Coefficients Method" means.Does it mean that when you exactly set the pressure at 0Pa,you will get a equtation of CPo/RCO2 varying with the temperature?And how does it make sense?Is there any theory about it?


My friend told me how to use Matlab getting data from Refprop.In the code,I have to set a constant,such as pressure or temperature.But during the real flow process,the temperature and pressure are all variable.If the Zero Pressure Coefficients Method means setting the pressure at 0Pa,it will be easy.

In addtion,this paper compares the result using this method with that using an .rgp file.So,I also want to know how to import an .rgp file.As you can guess,I've never done it before.It's a little bit difficult for me,but I still want to try.Can you teach me more precisely about it?

My another friend told me that it probably involved the Interpolation method.I don't know if it works.

I'll ppreciate it.

[evcelica]

In Refprop you could set the pressure to zero. But there is also a property it will give you called "Cp0" which is the same thing, and you could set the pressure to anything, and Cp0 will give you Cp at 0 pressure.


There are instructions on this site for making an rgp file. I use NIST_TO_RGP.

It is on the ANSYS customer portal website if you have an account:
https://support.ansys.com/AnsysCusto...ns/CFX/2042746

[Fresher]

Originally Posted by evcelica

In Refprop you could set the pressure to zero. But there is also a property it will give you called "Cp0" which is the same thing, and you could set the pressure to anything, and Cp0 will give you Cp at 0 pressure.


There are instructions on this site for making an rgp file. I use NIST_TO_RGP.

It is on the ANSYS customer portal website if you have an account:
https://support.ansys.com/AnsysCusto...ns/CFX/2042746

Thanks a lot,evcelica.I'll have a try as you've suggested.Thank you very much.