packageRegions
functions to find the current region for given pairs of input variables
Information
Package description
Package Regions contains a large number of auxiliary functions which are neede to compute the current region
of the IAPWS/IF97 for a given pair of input variables as quickly as possible. The focus of this implementation was on
computational efficiency, not on compact code. Many of the function values calulated in these functions could be obtained
using the fundamental functions of IAPWS/IF97, but with considerable overhead. If the region of IAPWS/IF97 is known in advance,
the input variable mode can be set to the region, then the somewhat costly region checks are omitted.
The checking for the phase has to be done outside the region functions because many properties are not
differentiable at the region boundary. If the input phase is 2, the output region will be set to 4 immediately.
Package contents
The main 4 functions in this package are the functions returning the appropriate region for two input variables.
Function region_ph compute the region of IAPWS/IF97 for input pair pressure and specific enthalpy.
Function region_ps compute the region of IAPWS/IF97 for input pair pressure and specific entropy
Function region_dT compute the region of IAPWS/IF97 for input pair density and temperature.
Function region_pT compute the region of IAPWS/IF97 for input pair pressure and temperature (only ine phase region).
In addition, functions of the boiling and condensation curves compute the specific enthalpy, specific entropy, or density on these
curves. The functions for the saturation pressure and temperature are included in the package Basic because they are part of
the original IAPWS/IF97 standards document. These functions are also aliased to
be used directly from package Water.
Function hl_p computes the liquid specific enthalpy as a function of pressure. For overcritical pressures,
the critical specific enthalpy is returned. An approximation is used for temperatures > 623.15 K.
Function hv_p computes the vapour specific enthalpy as a function of pressure. For overcritical pressures,
the critical specific enthalpy is returned. An approximation is used for temperatures > 623.15 K.
Function sl_p computes the liquid specific entropy as a function of pressure. For overcritical pressures,
the critical specific entropy is returned. An approximation is used for temperatures > 623.15 K.
Function sv_p computes the vapour specific entropy as a function of pressure. For overcritical pressures,
the critical specific entropyis returned. An approximation is used for temperatures > 623.15 K.
Function rhol_T computes the liquid density as a function of temperature. For overcritical temperatures,
the critical density is returned. An approximation is used for temperatures > 623.15 K.
Function rhol_T computes the vapour density as a function of temperature. For overcritical temperatures,
the critical density is returned. An approximation is used for temperatures > 623.15 K.
All other functions are auxiliary functions called from the region functions to check a specific boundary.
Function boundary23ofT computes the boundary pressure between regions 2 and 3 (input temperature)
Function boundary23ofp computes the boundary temperature between regions 2 and 3 (input pressure)
Function hlowerofp5 computes the lower specific enthalpy limit of region 5 (input p, T=1073.15 K)
Function hupperofp5 computes the upper specific enthalpy limit of region 5 (input p, T=2273.15 K)
Function slowerofp5 computes the lower specific entropy limit of region 5 (input p, T=1073.15 K)
Function supperofp5 computes the upper specific entropy limit of region 5 (input p, T=2273.15 K)
Function hlowerofp1 computes the lower specific enthalpy limit of region 1 (input p, T=273.15 K)
Function hupperofp1 computes the upper specific enthalpy limit of region 1 (input p, T=623.15 K)
Function slowerofp1 computes the lower specific entropy limit of region 1 (input p, T=273.15 K)
Function supperofp1 computes the upper specific entropy limit of region 1 (input p, T=623.15 K)
Function hlowerofp2 computes the lower specific enthalpy limit of region 2 (input p, T=623.15 K)
Function hupperofp2 computes the upper specific enthalpy limit of region 2 (input p, T=1073.15 K)
Function slowerofp2 computes the lower specific entropy limit of region 2 (input p, T=623.15 K)
Function supperofp2 computes the upper specific entropy limit of region 2 (input p, T=1073.15 K)
Function d1n computes the density in region 1 as function of pressure and temperature
Function d2n computes the density in region 2 as function of pressure and temperature
Function dhot1ofp computes the hot density limit of region 1 (input p, T=623.15 K)
Function dupper1ofTcomputes the high pressure density limit of region 1 (input T, p=100MPa)
Function hl_p_R4b computes a high accuracy approximation to the liquid enthalpy for temperatures > 623.15 K (input p)
Function hv_p_R4b computes a high accuracy approximation to the vapour enthalpy for temperatures > 623.15 K (input p)
Function sl_p_R4b computes a high accuracy approximation to the liquid entropy for temperatures > 623.15 K (input p)
Function sv_p_R4b computes a high accuracy approximation to the vapour entropy for temperatures > 623.15 K (input p)
Function rhol_p_R4b computes a high accuracy approximation to the liquid density for temperatures > 623.15 K (input p)
Function rhov_p_R4b computes a high accuracy approximation to the vapour density for temperatures > 623.15 K (input p)
Version Info and Revision history
First implemented: July, 2000
by Hubertus Tummescheit
Authors: Hubertus Tummescheit, Jonas Eborn and Falko Jens Wagner
Modelon AB
Ideon Science Park
SE-22370 Lund, Sweden
email: hubertus@modelon.se
Initial version: July 2000
Revised and extended for inclusion in Modelica.Thermal: December 2002
## Copyright © EDF 2002 - 2025
## ThermoSysPro Version 4.2Contents
| Name | Description |
|---|---|
 boundary23ofT | boundary function for region boundary between regions 2 and 3 (input temperature) |
 boundary23ofp | boundary function for region boundary between regions 2 and 3 (input pressure) |
 hlowerofp5 | explicit lower specific enthalpy limit of region 5 as function of pressure |
 hupperofp5 | explicit upper specific enthalpy limit of region 5 as function of pressure |
 slowerofp5 | explicit lower specific entropy limit of region 5 as function of pressure |
 supperofp5 | explicit upper specific entropy limit of region 5 as function of pressure |
 hlowerofp1 | explicit lower specific enthalpy limit of region 1 as function of pressure |
 hupperofp1 | explicit upper specific enthalpy limit of region 1 as function of pressure (meets region 4 saturation pressure curve at 623.15 K) |
 slowerofp1 | explicit lower specific entropy limit of region 1 as function of pressure |
 supperofp1 | explicit upper specific entropy limit of region 1 as function of pressure (meets region 4 saturation pressure curve at 623.15 K) |
 hlowerofp2 | explicit lower specific enthalpy limit of region 2 as function of pressure (meets region 4 saturation pressure curve at 623.15 K) |
 hupperofp2 | explicit upper specific enthalpy limit of region 2 as function of pressure |
 slowerofp2 | explicit lower specific entropy limit of region 2 as function of pressure (meets region 4 saturation pressure curve at 623.15 K) |
 supperofp2 | explicit upper specific entropy limit of region 2 as function of pressure |
 d1n | density in region 1 as function of p and T |
 d2n | density in region 2 as function of p and T |
 dhot1ofp | density at upper temperature limit of region 1 |
 dupper1ofT | density at upper pressure limit of region 1 |
 hl_p_R4b | explicit approximation of liquid specific enthalpy on the boundary between regions 4 and 3 |
 hv_p_R4b | explicit approximation of vapour specific enthalpy on the boundary between regions 4 and 3 |
 sl_p_R4b | explicit approximation of liquid specific entropy on the boundary between regions 4 and 3 |
 sv_p_R4b | explicit approximation of vapour specific entropy on the boundary between regions 4 and 3 |
 rhol_p_R4b | explicit approximation of liquid density on the boundary between regions 4 and 3 |
 rhov_p_R4b | explicit approximation of vapour density on the boundary between regions 4 and 2 |
 boilingcurve_p | properties on the boiling curve |
 dewcurve_p | properties on the dew curve |
 hvl_p | |
 hl_p | liquid specific enthalpy on the boundary between regions 4 and 3 or 1 |
 hv_p | vapour specific enthalpy on the boundary between regions 4 and 3 or 2 |
 hvl_p_der | derivative function for the specific enthalpy along the phase boundary |
 rhovl_p | |
 rhol_p | density of saturated water |
 rhov_p | density of saturated vapour |
 rhovl_p_der | |
 sl_p | liquid specific entropy on the boundary between regions 4 and 3 or 1 |
 sv_p | vapour specific entropy on the boundary between regions 4 and 3 or 2 |
 rhol_T | density of saturated water |
 rhov_T | density of saturated vapour |
 region_ph | return the current region (valid values: 1,2,3,4,5) in IF97 for given pressure and specific enthalpy |
 region_ps | return the current region (valid values: 1,2,3,4,5) in IF97 for given pressure and specific entropy |
 region_pT | return the current region (valid values: 1,2,3,5) in IF97, given pressure and temperature |
 region_dT | return the current region (valid values: 1,2,3,4,5) in IF97, given density and temperature |