Enthalpy calculations are wrong (bad bounding?) about flash-separation HOT 8 CLOSED

For change of enthalpy of liquid water at 20 ºC to steam at 150 ºC:

Enthalpy change from 20 – 100 ºC for liquid water:
6058.49 J / mol
Enthalpy change from 100 – 150 ºC for steam:
1714.43 J / mol
Heat of vapourization for a mole of water:
40660 J / mol

Total enthalpy change:
48432.92 J / mol

from flash-separation.

Once we are passing the test in e6e89e2, I think we just need the following tests to validate that our math is right for the enthalpy calculations:

• inlet as subcooled liquid and outlet in VLE (and reverse: inlet in VLE and outlet as subcooled liquid)
• inlet as superheated vapour and outlet in VLE (reverse: inlet in VLE and outlet as superheated vapour)
• inlet and outlet both in VLE

from flash-separation.

For change of enthalpy of liquid water at 20 ºC to 50/50 mixture of water and steam at 100 ºC:

Enthalpy change from 20 – 100 ºC for liquid water:
6058.49 J / mol
Heat of vapourization for a mole of water:
40660 J / mol

Total enthalpy change:
6058.49 + (40660/2) = 26,388.49 J / mol

from flash-separation.

For change of enthalpy of one mole of water in VLE (50/50 water/steam) at 100 ºC to steam at 150 ºC:

Heat of vapourization of water:
40660 J / mol
Enthalpy change from 100 – 150 ºC for steam:
1714.43 J / mol

Total enthalpy change:
(40660/2) + 1714.43 = 22,044.43 J / mol

from flash-separation.

For change of enthalpy of one mole of water in VLE (75/25 water/steam) at 100 ºC to VLE (25/75 water/steam) at 100 ºC:

Heat of vapourization of water:
40660 J / mol

Total enthalpy change:
(40660/2) = 20,330 J / mol

from flash-separation.

I think we have full test coverage for pure species enthalpy calculations right now and should be able to validate if we're doing the right thing for the enthalpy calculations. We'll need to add in some binary mixtures as well though to test that our multiple-species logic is reasonable.

from flash-separation.

For a mixture of water and cyclohexane:
Mole ratio of 0.75 to 0.25
Molar flow rate: 2 mol/s

Enthalpy change with temperature change from 20 ºC to 150 ºC:

Water enthalpy change:
Enthalpy change from 20 – 94.75 ºC for liquid water:
5663.5 J / mol = 8495.25 J
Enthalpy change from 94.75 – 150 ºC for steam:
1891.2 J / mol = 2836.8 J
Heat of vapourization for a mole of water:
40660 J / mol = 60990 J

Total water enthalpy change:
20.75(5663.5+1891.2+40660) = 72322.05 J

Cyclohexane enthalpy change:
Liquid from 20 – 94.75 ºC:
12409.2 J / mol = 6204.6 J
Vapour from 94.75 – 150 ºC:
8196.95 J/mol = 4098.475 J
Heat of vapourization:
31690.4 J/mol = 15845.2 J

Total cyclohexane enthalpy change:
20.25(12409.2+8196.95+31690.4) = 26148.3 J

Total enthalpy change:
72322.05+26148.3 = 98470.35 J

High: 100439.75 Low: 96500.94

from flash-separation.

All the tests are now passing!!

from flash-separation.