2P-MA Heat Exchanger Block Not Stable

Hi, I have recently attempted to implement the 2P-MA heat exchanger block in the Simscape Fluids toolbox and the results were very unstable.

For the first case, where it is used as an evaporator, it seems fine.

For the second case, where it is used as a condenser, the results were constantly fluctuating.

What is causing this problem? I have checked the mathematical model given on the webpage and that does not seem to be the issue here.

On a side note, were these component models validated using experimental data?

Answer 1

[Juan Sagarduy]

Hello Tech

When looking at your diagram, i believe that the model is over-constrained on both 2p and MA end sides. You should prescribe the conditions at the inlet of both 2P and MA as u did, but the conditions at the outlet will be determined by the heat exchanged. It is quite difficult to set the thermodynamic conditions consistently.

Hope this helps Br Juan

[Tech Logg Ding]

Dear Juan,

Thank you very much for your reply. Just to follow up on that, how can I leave the outlets unconstrained? What block would you recommend for that?

Thank you.

Regards,

Ding

[Juan Sagarduy]

Try with simple reservoirs on both outlets with atmospheric pressure. Let the gas and 2-phase fluid circulate and exchange heat.

The enthalpy on the sinks should converge to the values you expect, as well as the vapor quality become low.

If not then flow values or heat exchanger parameters need to be reviewed.

My 2c / Juan