Spirit flow-x Function Reference page 208

Flow-X─ Function Reference
4-208
Flow-X General functions - fxIAPWS_IF97_C
Function inputs
Name
Temperature
Pressure
Phase
Function outputs
Status
Density
Enthalpy
Region
Saturation pressure
Dynamic viscosity
Ratio of specific
heats
Remark
Optional tag name, tag description and
tag group
The phase (water or steam) can be
calculated automatically or be set to
either steam or water.
1: Auto-select (calculate from t and p
inputs)
2: Steam
3: Water
If 'Steam' or 'Water' is selected, while the
combination of temperature and pressure
indicates the opposite phase, then the
function uses either the saturation
pressure (region 4) or the boundary
pressure (intersection regions 2 and 3)
instead of the input pressure for its
calculations.
Remark
0: Normal
1: Input argument out of range
2: Calculation error
3: No convergence
Energy flow = Mass flow * Enthalpy
Actual IAPWS-IF97 region
0: Combination of t and p is outside the valid range
1: Water
2: Steam
3: Pressurized water
4: At the saturation line
5: High temperature steam (1472 ≤ T ≤ 3632 °F)
Saturation pressure at the input temperature.
Note: only calculated up to the critical temperature of
647.096 K (+- 705 °F), set to 0 for higher temperatures
The dynamic viscosity is required for flow rate
calculations based on a differential pressure
measurement (e.g. orifice)
Equals the ratio of the specific heats cp / cv
cp : specific heat at constant pressure
cv : specific heat at constant volume
This ratio can be used as the isentropic exponent
value (also called 'kappa') when the real value is
unknown.
The isentropic exponent is required for flow rate
calculations based on a differential pressure
measurement (e.g. orifice)
EU Range Default
°F 0 .. 4000 0
psia 0..15000 0
1
EU Fallback
lbm/ft3 0
btu/lbm 0
- 0
psia 0
lbm/ft.s 0
- 0