refprop

[jacbenimble]

Hello,

I was wondering if anyone has ever completed an application accessing REFPROP from NIST.

I have used other DLL’s with the CIN tool but can not seem to make this REFPROP DLL work.

If anyone has a code snippet showing the settings of the CIN tool that is using REFPROP, it would be greatly appreciated.

[Travis_M.]

Hello Jackbenimble,

It sounds like you are able to call other DLLs properly, so I am assuming that there is no problem from the LabVIEW end of things.  I searched and found a link to a patch for the software I believe you are trying to call here.  If you have any questions on exactly how to call third party DLLs please let us know -- I am more than happy to provide some documentation and help on that.

Hope that link helps.  Have a great afternoon!

Regards,

[gsussman]

Any new developments on this front?

I also need to access the Refprop DLL and can't seem to get the calling convention down. I have done a bunch of other DLL/labview interfaces before, however this one does not seem to conform to the normal rules of LabVIEW and dll calls.

[Travis_M.]

Hello,

I don’t know about the specific problems with this DLL, but LabVIEW is only able to call with C or STDCALL (WINAPI) calling convention.  The DLL seems to have a known issue (linked above) with some installation issues.  I do not know if the customer above was able to get the software working, but please let us know if you have any questions on how to use the Call Library Function Node VI in LabVIEW with either calling convention.

Have a great day!

[jacbenimble]

Yes, I was able to get this to work. I e-mailed Dr. Lemmon and he was more than happy to provide examples of his code being called by LabView. I am passing them on just as received. If you make more VIs, would you please forward them, or post them. We would all find some benifit in the shared work. Thanks John

[gsussman]

I spoke to a guy at NIST yesterday. He was able to send me a copy of a couple of VIs that somebody cobbled together to initialize and make one function call. Hopefully within the next couple of weeks (time permitting) I will have time to clean up those calls as well as implement some of the other calls in a more standard driver format.

The problem with Refprop is not with the dll, per se, but more due to the somewhat cryptic way the parameters are entered.

I plan on submitting my finished VIs back to NIST for inclusion with the next version of Refprop that will be releasing sometime early next year.

[gsussman]

Jack.....it looks like you got the same VIs I did, and from the same guy by the way.

When I get my code together I will post it with NIST as possibly on my FTP site.

[Will_Crowe]

I was able to get Labview to call on Refprop for properties of a single pure fluid, but haven't been able to do this for a mixture. There seems to be a discrepency between the calls documented in the help file, and those in the Labview DLL call.

Has anyone been able to call on properties of a mixture from Labview?

[gsussman]

The attached zip file contains VIs in LV 7.1 format that shoud give you a leg up on getting going with Refprop.

The code supports pure fluids as well as mixtures, but only a couple of the calculations functions (SATP, SATT, TPFLSH), however it should give you a good baseline for working out any of the other Refprop functions.

[Will_Crowe]

Thank you for those VI's.

However, I still seem to have the same problem, namely how to get properties of a mixture back from the Refprop DLL. The "refrigerant file" input in your VI is a single string which can take a single refrigerant (pure fluid) name. When I try to enter a mixture name into this string control, nothing is returned.

In the DLL descriptions that come with Refprop (for theSETUP subroutine) it names one of the inputs as "hfiles" and refers to this as an "array of file names specifying fluid/mixture components for each of the nc components". However, the control is a string control, not an array, so I can't figure out how you enter in several fluid names, to make up a mixture. I also don't know where you specify which mixture (the name, eg. R404A) that you want.

If I could just get these calls right, I think everything else would be OK. Certainly I can get labview to call in properties for a single fluid very easily, but I can't work it for a mixture.

I really appreciate your help,

Will