Regarding SinglePhaseProperty call in MATLAB Unit Op

[djweber]

Hello there,

I am having trouble getting vapor phase properties for my membrane distillation unit (which has a unsaturated liquid stream). When I make the property call and test it inside the CAPE-OPEN MATLAB interface in AspenPlus, I get this error:

Error: Error using CapeOpenUnitMex, Failed to set temperature on material: The specified phase is not present in material object

This error suggests that there is no vapor phase property able to be calculated; however I can go to the properties section and calculate property just fine at the same conditions and hard code it in.

Also, in COFE, I run the same code and get no error; it calculates the vapor phase property in the code just fine. I even have the permeate pressure set in both simulators such that there should be a liquid and vapor phase recognized in the "material object."

And lastly, as a quick side question. When I am trying to find single phase properties with a mixture with dissolved salts; say viscosity; will it calculate mixture viscosity based on given conditions and return a single value; or will it attempt to give the viscosity of each component (in which I would get an error since the viscosity of salt is illogical).

Thank you very much for your time and help,
Dylan Weber

[jasper]

The thermo specification states that a phase needs to be present as soon as T, P or X are imposed, to facilitate non-equilibrium property calculations. Which version of AspenPlus is this?

Viscosity is a mixture property. It is a scalar. If you do want the pure compound values, just calculate viscosity at a composition that corresponds to a pure compound.