Missing enthalpy test case: lower pressure to vapourize liquid solution about flash-separation HOT 2 CLOSED

From steam tables:

Change in enthalpy from water at 120 ºC, 0.2 MPa (liquid) to 110 ºC, 0.10 MPa (vapour) is 39,498.32 J/mol.

Steps: water from 120 to 110 C: -762.44 J/mol
vapourize the water: 40714.5 J/mol

Gives 39952 J/mol (+1% of steam table value)

from flash-separation.

For the above example, the heat of vapourization is the same both for the forward and reverse direction.

However, does the stream change temperature or pressure first? If it changes pressure first, then the enthalpy of the temperature change is -342 J/mol for steam in the forward direction. If it changes temperature first, then the enthalpy of the temperature change is -762 J/mol for water in the forward direction.

Maybe we should just make an assumption and go with it? This could be problematic!

In our simulator I think it is more reasonable to say that we change pressure first, then temperature.

from flash-separation.