Basic

Base functions as described in IAWPS/IF97

Package Contents

g1

Gibbs function for region 1: g(p,T)

g2

Gibbs function for region 2: g(p,T)

g2metastable

Gibbs function for metastable part of region 2: g(p,T)

f3

Helmholtz function for region 3: f(d,T)

g5

Base function for region 5: g(p,T)

gibbs

Gibbs function for region 1, 2 or 5: g(p,T,region)

g1pitau

Derivative of g w.r.t. pi and tau

g2pitau

Derivative of g w.r.t. pi and tau

g5pitau

Derivative of g w.r.t. pi and tau

f3deltatau

1st derivatives of f w.r.t. delta and tau

tph1

Inverse function for region 1: T(p,h)

tps1

Inverse function for region 1: T(p,s)

tph2

Reverse function for region 2: T(p,h)

tps2a

Reverse function for region 2a: T(p,s)

tps2b

Reverse function for region 2b: T(p,s)

tps2c

Reverse function for region 2c: T(p,s)

tps2

Reverse function for region 2: T(p,s)

tsat

Region 4 saturation temperature as a function of pressure

dtsatofp

Derivative of saturation temperature w.r.t. pressure

tsat_der

Derivative function for tsat

psat

Region 4 saturation pressure as a function of temperature

dptofT

Derivative of pressure w.r.t. temperature along the saturation pressure curve

psat_der

Derivative function for psat

p1_hs

Pressure as a function of enthalpy and entropy in region 1

h2ab_s

Boundary between regions 2a and 2b

p2a_hs

Pressure as a function of enthalpy and entropy in subregion 2a

p2b_hs

Pressure as a function of enthalpy and entropy in subregion 2a

p2c_hs

Pressure as a function of enthalpy and entropy in subregion 2c

h3ab_p

Region 3 a b boundary for pressure/enthalpy

T3a_ph

Region 3 a: inverse function T(p,h)

T3b_ph

Region 3 b: inverse function T(p,h)

v3a_ph

Region 3 a: inverse function v(p,h)

v3b_ph

Region 3 b: inverse function v(p,h)

T3a_ps

Region 3 a: inverse function T(p,s)

T3b_ps

Region 3 b: inverse function T(p,s)

v3a_ps

Region 3 a: inverse function v(p,s)

v3b_ps

Region 3 b: inverse function v(p,s)

Information

This information is part of the Modelica Standard Library maintained by the Modelica Association.

Package description

Package BaseIF97/Basic computes the fundamental functions for the 5 regions of the steam tables as described in the standards document IF97.pdf. The code of these functions has been generated using Mathematica and the add-on packages "Format" and "Optimize" to generate highly efficient, expression-optimized C-code from a symbolic representation of the thermodynamic functions. The C-code has than been transformed into Modelica code. An important feature of this optimization was to simultaneously optimize the functions and the directional derivatives because they share many common subexpressions.

Package contents

  • Function g1 computes the dimensionless Gibbs function for region 1 and all derivatives up to order 2 w.r.t. pi and tau. Inputs: p and T.
  • Function g2 computes the dimensionless Gibbs function for region 2 and all derivatives up to order 2 w.r.t. pi and tau. Inputs: p and T.
  • Function g2metastable computes the dimensionless Gibbs function for metastable vapour (adjacent to region 2 but 2-phase at equilibrium) and all derivatives up to order 2 w.r.t. pi and tau. Inputs: p and T.
  • Function f3 computes the dimensionless Helmholtz function for region 3 and all derivatives up to order 2 w.r.t. delta and tau. Inputs: d and T.
  • Function g5computes the dimensionless Gibbs function for region 5 and all derivatives up to order 2 w.r.t. pi and tau. Inputs: p and T.
  • Function tph1 computes the inverse function T(p,h) in region 1.
  • Function tph2 computes the inverse function T(p,h) in region 2.
  • Function tps2a computes the inverse function T(p,s) in region 2a.
  • Function tps2b computes the inverse function T(p,s) in region 2b.
  • Function tps2c computes the inverse function T(p,s) in region 2c.
  • Function tps2 computes the inverse function T(p,s) in region 2.
  • Function tsat computes the saturation temperature as a function of pressure.
  • Function dtsatofp computes the derivative of the saturation temperature w.r.t. pressure as a function of pressure.
  • Function tsat_der computes the Modelica derivative function of tsat.
  • Function psat computes the saturation pressure as a function of temperature.
  • Function dptofT computes the derivative of the saturation pressure w.r.t. temperature as a function of temperature.
  • Function psat_der computes the Modelica derivative function of psat.

Version Info and Revision history

  • First implemented: July, 2000 by Hubertus Tummescheit
Author: Hubertus Tummescheit,
Modelon AB
Ideon Science Park
SE-22370 Lund, Sweden
email: hubertus@modelon.se
  • Initial version: July 2000
  • Documentation added: December 2002

Equation from:

 [1] The international Association for the Properties of Water and Steam
 Vejle, Denmark
 August 2003
 Supplementary Release on Backward Equations for the Functions T(p,h), v(p,h) and T(p,s),
 v(p,s) for Region 3 of the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of
 Water and Steam