Contents - Index

POPROP_ns

The procedure POPROP_ns provides the thermodynamic properties of potassium outside of the vapor dome (superheated vapor or subcooled liquid)

Call POPROP_ns(T, P: h, s, v, y2, y4, MW, phase)

Inputs:

T: Temperature 

P: Pressure

Outputs:

h: Enthalpy

s: Entropy

v: Specific volume

y2: Mole fraction of dimer (K2)

y4: Mole fraction of tetramer (K4)

MW: Molar mass

Phase: Indicates the phase (-100 = subcooled liquid, +100 = superheated vapor)

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 K, K2, and K4 and therefore its molar mass also varies.  The mole fraction of K (the monomer) is y1 = 1 - y2 - y4.  The companion function POPROP_s provides properties inside the vapor dome.

The properties come from the POPROP procedure listed in Sodium-NaK Engineering Handbook, Volume 1.  The properties of subcooled liquid are approximated assuming that potassium liquid is incompressible.

To find the saturation pressure for potassium at 1200 [C] use POPROP_s:

$UnitSystem SI Mass kJ C kPa

T = 1200 [C]

x = 0.5

Call POPROP_s(T, x: , , , , , , P_sat)

{Solution: P_sat = 1749 [kPa]}

To get the properties of subcooled liquid potassium, set the pressure to a higher value than the saturation pressure and call POPROP_ns:

P_sc=1.5*P_sat

Call POPROP_ns(T, P_sc: h_sc, s_sc, v_sc, y2_sc, y4_sc, MW_sc, phase_sc)

{Solution: h_sc = 1184 [kJ/kg], s_sc = 3.080 [kJ/kg-K], v_sc = 0.001818 [m^3/kg], y2_sc = 0, y4_sc = 0, MW_sc = 39.10 [kg/kmol], phase_sc = -100}

To get the properties of superheated vapor potassium, set the pressure to a lower value than the saturation pressure and call POPROP_ns:

P_sh=0.5*P_sat

Call POPROP_ns(T, P_sh: h_sh, s_sh, v_sh, y2_sh, y4_sh, MW_sh, phase_sh)

{Solution: h_sh = 2959 [kJ/kg], s_sh = 4.413 [kJ/kg-K], v_sh = 0.3227 [m^3/kg], y2_sh = 0.09628, y4_sh = 0.004518, MW_sh = 43.40 [kg/kmol], phase_sh = +100}