POPROP_s
The procedure POPROP_s provides the thermodynamic properties of potassium on or under the vapor dome.
Call POPROP_s(T, x: h, s, v, y2, y4, MW, P_sat)
Inputs:
T: Temperature
x: Quality (mass of vapor/total mass)
Outputs:
h: Enthalpy
s: Entropy
v: Specific volume
y2: Mole fraction of dimer (K2)
y4: Mole fraction of tetramer (K4)
MW: Molar mass
P_sat: Saturation pressure
Note that the procedure operates in whatever unit system EES is set to (including molar units). The composition of potassium vapor varies with its state and includes Na, Na2, and Na4 and therefore its molar mass also varies. The mole fraction of K (the monomer) is y1 = 1 - y2 - y4. The companion function POPROP_ns provides properties outside of the vapor dome.
The properties come from the POPROP procedure listed in Sodium-NaK Engineering Handbook, Volume 1.
To get the properties of saturated liquid potassium, set x = 0:
$UnitSystem SI Mass kJ C kPa
T = 1200 [C]
x = 0
Call POPROP_s(T, x: h, s, v, y2, y4, MW, P_sat)
{Solution: h = 1182 [kJ/kg], s = 3.080 [kJ/kg-K], v = 0.001818 [m^3/kg], y2 = 0, y4 = 0, MW = 39.10 [kg/kmol], P_sat = 1749 [kPa]}
To get the properties of saturated vapor potassium, set x = 1:
$UnitSystem SI Mass kJ C kPa
T = 1200 [C]
x = 1
Call POPROP_s(T, x: h, s, v, y2, y4, MW, P_sat)
{Solution: h = 2839 [kJ/kg], s = 4.205 [kJ/kg-K], v = 0.1453 [m^3/kg], y2 = 0.1588, y4 = 0.02458, MW = 48.20 [kg/kmol], P_sat = 1749 [kPa]}
To get the properties of potassium with x = 0.5:
$UnitSystem SI Mass kJ C kPa
T = 1200 [C]
x = 0.5
Call POPROP_s(T, x: h, s, v, y2, y4, MW, P_sat)
{Solution: h = 2011 [kJ/kg], s = 3.642 [kJ/kg-K], v = 0.07355 [m^3/kg], y2 = 0.07113, y4 = 0.01101, MW = 43.18 [kg/kmol], P_sat = 1749 [kPa]}