Learning Forum

[James Khreibani]

I have two streams of supercritical water feeding a species model as a NIST RG. One is high pressure, and one is lower pressure. I want to model the interaction between the high and low pressure streams. I can simulate the process using VOF which seems to be very computationally expensive and slow. I tried modeling as a species model but was informed that water could not be modeled as a mixed-species model (HP and LP) although the fluid conditions are identical. Is it correct to model through VOF or is there a better method?

[Rob]

VOF is for phase models where you track the free surface. Species is for a single phase where the materials mix.  From your description if both streams are water in the same phase do you even need multiple species? 

[James Khreibani]

They are the same species however i want to model the interaction of the high pressure and low pressure and track how each stream behavies when mixed. In reality the high pressure may have some impurities but i want to keep the analysis simple to start with out mixed supecritical fluids which may not even be possible using the NIST Refprop database.

[Rob]

The properties will be based on the cell conditions, so you can have inlets at different pressures & temperature. The complication comes with phase change and phase interaction, and it's not clear if you need to worry about that. 

[James Khreibani]

The specific error I keep getting: REFPROP_error (117) from function: setup [SETUP error 117] Estimation of mixing parameters is not possible for most mixtures containing water, hydrogen, neon, carbon monoxide, flourine, methanol, or ethanol.

[James Khreibani]

Any thoughts on this issue?

[Rob]

I had a week off.  A mixture should use the averaged properties from the individual species, what have you set for the mixture?