Hey,
I understand that you are encountering an error when trying to call ‘REFPROP’, but your model runs well when you comment it out.
A “.dll” file, as well as several other MATLAB files, must be downloaded separately for the primary installation of ‘REFPROP’, please use the link below to see the installation instructions:
Please click the hyper-linked files on this webpage to download these files and move them into your ‘REFPROP’ installation folder (C:/Program Files (x86)/REFPROP).
Once these files are in your folder, execute the following commands to determine if your installation is set up correctly:
>> refpropm('T','P',101.325,'Q',0,'WATER')
>> waterTables = twoPhaseFluidTables([25,4000],[0.01,15],25,25,60,'water','C:\Program Files\REFPROP\')
Hope this helps!