MIXTURE property

[yuycsmart]

Description

The issue of calculated property values mismatch upon reordering the components. [Description of the issue] The property results by defining new mixtures is different from the property results by using the refprop software. For example, the air composition(nitrogen/argon/oxygen---0.7812/0.0092/0.2096), the results by using C++ are 32(Wm) ,-119℃ (TC), 5.043MPa (PC); but by using the refprop software the results are 29(Wm) ,-140℃ (TC), 3.85MPa (PC).

I totally follow the refprop example _C++,the diffrerance is reasonable or there is something wrong, please tell me why,thanks.

Expected behavior: [What you expect to happen] Tell me why, I totally follow the refprop example _C++. Actual behavior: [What actually happens] The property results by defining new mixtures is different from the property results by using the refprop software.

Versions

REFPROP Version: [REFPROP version you are using] 9.1 Operating System and Version: [OS you are running REFPROP on] Windows 7 Access Method: [How you are accessing REFPROP (i.e. Python, other wrapper)] C++

Additional Information

none If possible, please post examples and/or screenshots of the issue.

[ianhbell]

Please post your C++ code so that we can see what you did.

[ibell]

Seems like there is something wrong with your C++ code. The fact that the molar mass is different is a serious issue, suggesting a non-trivial error. That the critical point location is different suggests an alternative error.

In Python (should be like C++), I do:

from ctREFPROP.ctREFPROP import REFPROPFunctionLibrary
RP = REFPROPFunctionLibrary('/home/ian/refprop')
RP.SETPATHdll('/home/ian/refprop')
print(RP.REFPROPdll('NITROGEN*ARGON*OXYGEN','','M;TC;PC', 0,0,0,0,0,[0.7812,0.0092,0.2096]))

results:

28.958600656, 132.82329394807982, 3850.035229536823

full output:

REFPROPdlloutput(z=array('d', [0.7812, 0.0092, 0.2096, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]), Output=array('d', [28.958600656, 132.82329394807982, 3850.035229536823, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0, -9999990.0]), hUnits='g/mol', iUCode=4294967282, x=array('d', [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]), y=array('d', [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]), x3=array('d', [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]), q=-9999990.0, ierr=4294966980, herr='[CRTHMX warning -316] The true critical point is unknown.  Estimated values based on previous fits of the critical lines were returned.  For a Type I binary mixture, the values are generally close.  For other Type I mixtures the values are rough estimate')

[yuycsmart]

The C++ code is the same with REFPROP software example. I use .cpp and .h to compute the pure fluid and there is nothing wrong, but using the mixture example, the result is wrong. For example, the R410A:

     char *FLD_PATH;  
    FLD_PATH = "C:\\Program Files\\REFPROP\\fluids\\";
      strcpy(hf,FLD_PATH);
      strcpy(hfmix,FLD_PATH);
 //...initialize the program and set the pure fluid component name
      i=2;
      strcpy(hf,"r32.fld");
      strcat(hf,"|r125.fld");
      strcpy(hfmix,"hmx.bnc");
      strcpy(hrf,"DEF");
      strcpy(herr,"Ok");
      x[0]=0.69761;
      x[1]=0.30239;

    //...Call SETUP to initialize the program
      SETUPdll(i, hf, hfmix, hrf, ierr, herr, refpropcharlength*ncmax,refpropcharlength,lengthofreference,errormessagelength);
    if (ierr != 0) printf("%s\n",herr);

    double wm,ttp,tnbp,tc,pc,dc,zc,acf,dip,rgas;
  //....long info_index=1;
       INFOdll(i,wm,ttp,tnbp,tc,pc,dc,zc,acf,dip,rgas);
       printf("WM,TC,PC    %10.4f,%10.4f,%10.4f\n",wm,tc-273.15,pc/1000.0); 

   for air composition:
      i=3;
     strcpy_s(hf,"nitrogen.fld");
     strcat_s(hf,"|argon.fld");   
     strcat_s(hf,"|oxygen.fld");
     strcpy_s(hfmix,"hmx.bnc");
     strcpy_s(hrf,"DEF");
      strcpy_s(herr,"Ok");
      x[0]=0.7812;     //Air composition
      x[1]=0.0092;
      x[2]=0.2096;   

  //...Call SETUP to initialize the program
      SETUPdll(i, hf, hfmix, hrf, ierr, herr, refpropcharlength*ncmax,refpropcharlength,lengthofreference,errormessagelength);
    if (ierr != 0) printf("%s\n",herr);

    double wm,ttp,tnbp,tc,pc,dc,zc,acf,dip,rgas;
  //....long info_index=1;
       INFOdll(i,wm,ttp,tnbp,tc,pc,dc,zc,acf,dip,rgas);
       printf("WM,TC,PC    %10.4f,%10.4f,%10.4f\n",wm,tc-273.15,pc/1000.0); 

The results for r32/r125(0.69761/0.30239) are : 120.0214(WM), 66.0230(TC-℃), 3.6177(PC-MPa), while by using REFPROP software, the results for R410A are 72.585414(WM), 71.3440(TC-℃), 4.9012(PC-MPa).

The results for nitrogen/argon/oxygen(0.7812/0.0092/0.2096) are 31.9988(WM), -118.5690(TC-℃), 5.0430(PC-MPa), while by using REFPROP software, the results for air are 28.965(WM), -140.62(TC-℃), 3.786(PC-MPa).

I don't know why. Thanks for helping me.

[ianhbell]

I cleaned up the formatting of your issue...

The key problem is that you are not getting what you think you are getting. The INFOdll function (https://refprop-docs.readthedocs.io/en/latest/DLL/legacy.html#f/_/INFOdll) returns properties of the pure fluids in the mixture, not the mixture itself.

[yuycsmart]

Understand. INFOdll(i,wm,ttp,tnbp,tc,pc,dc,zc,acf,dip,rgas): i means the number of the composition.

I have another question, that is how to get the R410A_eta; by using r32/r125(0.69761/0.30239) or call mixture file-- R410A.MIX. The results are same ot not.

TRNPRPdll(T, D, z, eta, tcx, ierr, herr, herr_length)

Thanks.

[ianhbell]

Try it! R410A.MIX is only a predefined mixture. It still uses the mixture model, so defining the mixture with specified composition or with R410A.MIX should be identical (if not that is a bug and please report it). Make sure you use mole fractions in TRNPRPdll (and the units of mol/L for density).

[yuycsmart]

Thanks, I find why and know the answers. Thanks again.

[ianhbell]

If you are satisfied, please close the issue in the web interface.