packageIF97_Utilities

Information

Package description

This package provides high accuracy physical properties for water according to the IAPWS/IF97 standard. It has been part of the ThermoFluid Modelica library and been extended, reorganized and documented to become part of the Modelica Standard library.

An important feature that distinguishes this implementation of the IF97 steam property standard is that this implementation has been explicitly designed to work well in dynamic simulations. Computational performance has been of high importance. This means that there often exist several ways to get the same result from different functions if one of the functions is called often but can be optimized for that purpose.

The original documentation of the IAPWS/IF97 steam properties can freely be distributed with computer implementations, so for curious minds the complete standard documentation is provided with the Modelica properties library. The following documents are included (in directory Modelica/Resources/Documentation/Media/Water/IF97documentation):

• IF97.pdf The standards document for the main part of the IF97.
• Back3.pdf The backwards equations for region 3.
• crits.pdf The critical point data.
• meltsub.pdf The melting- and sublimation line formulation (in IF97_Utilities.BaseIF97.IceBoundaries)
• surf.pdf The surface tension standard definition
• thcond.pdf The thermal conductivity standard definition
• visc.pdf The viscosity standard definition

Package contents

• Package BaseIF97 contains the implementation of the IAPWS-IF97 as described in IF97.pdf. The explicit backwards equations for region 3 from Back3.pdf are implemented as initial values for an inverse iteration of the exact function in IF97 for the input pairs (p,h) and (p,s). The low-level functions in BaseIF97 are not needed for standard simulation usage, but can be useful for experts and some special purposes.
• Function water_ph returns all properties needed for a dynamic control volume model and properties of general interest using pressure p and specific entropy enthalpy h as dynamic states in the record ThermoProperties_ph.
• Function water_ps returns all properties needed for a dynamic control volume model and properties of general interest using pressure p and specific entropy s as dynamic states in the record ThermoProperties_ps.
• Function water_dT returns all properties needed for a dynamic control volume model and properties of general interest using density d and temperature T as dynamic states in the record ThermoProperties_dT.
• Function water_pT returns all properties needed for a dynamic control volume model and properties of general interest using pressure p and temperature T as dynamic states in the record ThermoProperties_pT. Due to the coupling of pressure and temperature in the two-phase region, this model can obviously only be used for one-phase models or models treating both phases independently.
• Function hl_p computes the liquid specific enthalpy as a function of pressure. For overcritical pressures, the critical specific enthalpy is returned
• Function hv_p computes the vapour specific enthalpy as a function of pressure. For overcritical pressures, the critical specific enthalpy is returned
• Function sl_p computes the liquid specific entropy as a function of pressure. For overcritical pressures, the critical specific entropy is returned
• Function sv_p computes the vapour specific entropy as a function of pressure. For overcritical pressures, the critical specific entropy is returned
• Function rhol_T computes the liquid density as a function of temperature. For overcritical temperatures, the critical density is returned
• Function rhol_T computes the vapour density as a function of temperature. For overcritical temperatures, the critical density is returned
• Function dynamicViscosity computes the dynamic viscosity as a function of density and temperature.
• Function thermalConductivity computes the thermal conductivity as a function of density, temperature and pressure. Important note: Obviously only two of the three inputs are really needed, but using three inputs speeds up the computation and the three variables are known in most models anyways. The inputs d,T and p have to be consistent.
• Function surfaceTension computes the surface tension between vapour and liquid water as a function of temperature.
• Function isentropicEnthalpy computes the specific enthalpy h(p,s,phase) in all regions. The phase input is needed due to discontinuous derivatives at the phase boundary.
• Function dynamicIsentropicEnthalpy computes the specific enthalpy h(p,s,,dguess,Tguess,phase) in all regions. The phase input is needed due to discontinuous derivatives at the phase boundary. Tguess and dguess are initial guess values for the density and temperature consistent with p and s. This function should be preferred in dynamic simulations where good guesses are often available.

Version Info and Revision history

• First implemented: July, 2000 by Hubertus Tummescheit for the ThermoFluid Library with help from Jonas Eborn and Falko Jens Wagner
• Code reorganization, enhanced documentation, additional functions: December, 2002 by Hubertus Tummescheit and moved to Modelica properties library.

Contents

Name	Description
BaseIF97	Modelica Physical Property Model: the new industrial formulation IAPWS-IF97
iter
waterBaseProp_ph	Intermediate property record for water
waterBaseProp_ps	Intermediate property record for water
rho_props_ps	Density as function of pressure and specific entropy
rho_ps	Density as function of pressure and specific entropy
T_props_ps	Temperature as function of pressure and specific entropy
T_ps	Temperature as function of pressure and specific entropy
h_props_ps	Specific enthalpy as function or pressure and temperature
h_ps	Specific enthalpy as function or pressure and temperature
phase_ps	Phase as a function of pressure and specific entropy
phase_ph	Phase as a function of pressure and specific enthalpy
phase_dT	Phase as a function of pressure and temperature
rho_props_ph	Density as function of pressure and specific enthalpy
rho_ph	Density as function of pressure and specific enthalpy
rho_ph_der	Derivative function of rho_ph
T_props_ph	Temperature as function of pressure and specific enthalpy
T_ph	Temperature as function of pressure and specific enthalpy
T_ph_der	Derivative function of T_ph
s_props_ph	Specific entropy as function of pressure and specific enthalpy
s_ph	Specific entropy as function of pressure and specific enthalpy
s_ph_der	Specific entropy as function of pressure and specific enthalpy
cv_props_ph	Specific heat capacity at constant volume as function of pressure and specific enthalpy
cv_ph	Specific heat capacity at constant volume as function of pressure and specific enthalpy
regionAssertReal	Assert function for inlining
cp_props_ph	Specific heat capacity at constant pressure as function of pressure and specific enthalpy
cp_ph	Specific heat capacity at constant pressure as function of pressure and specific enthalpy
beta_props_ph	Isobaric expansion coefficient as function of pressure and specific enthalpy
beta_ph	Isobaric expansion coefficient as function of pressure and specific enthalpy
kappa_props_ph	Isothermal compressibility factor as function of pressure and specific enthalpy
kappa_ph	Isothermal compressibility factor as function of pressure and specific enthalpy
velocityOfSound_props_ph	Speed of sound as function of pressure and specific enthalpy
velocityOfSound_ph
isentropicExponent_props_ph	Isentropic exponent as function of pressure and specific enthalpy
isentropicExponent_ph	Isentropic exponent as function of pressure and specific enthalpy
ddph_props	Density derivative by pressure
ddph	Density derivative by pressure
ddhp_props	Density derivative by specific enthalpy
ddhp	Density derivative by specific enthalpy
waterBaseProp_pT	Intermediate property record for water (p and T preferred states)
rho_props_pT	Density as function or pressure and temperature
rho_pT	Density as function or pressure and temperature
h_props_pT	Specific enthalpy as function or pressure and temperature
h_pT	Specific enthalpy as function or pressure and temperature
h_pT_der	Derivative function of h_pT
rho_pT_der	Derivative function of rho_pT
s_props_pT	Specific entropy as function of pressure and temperature
s_pT	Temperature as function of pressure and temperature
cv_props_pT	Specific heat capacity at constant volume as function of pressure and temperature
cv_pT	Specific heat capacity at constant volume as function of pressure and temperature
cp_props_pT	Specific heat capacity at constant pressure as function of pressure and temperature
cp_pT	Specific heat capacity at constant pressure as function of pressure and temperature
beta_props_pT	Isobaric expansion coefficient as function of pressure and temperature
beta_pT	Isobaric expansion coefficient as function of pressure and temperature
kappa_props_pT	Isothermal compressibility factor as function of pressure and temperature
kappa_pT	Isothermal compressibility factor as function of pressure and temperature
velocityOfSound_props_pT	Speed of sound as function of pressure and temperature
velocityOfSound_pT	Speed of sound as function of pressure and temperature
isentropicExponent_props_pT	Isentropic exponent as function of pressure and temperature
isentropicExponent_pT	Isentropic exponent as function of pressure and temperature
waterBaseProp_dT	Intermediate property record for water (d and T preferred states)
h_props_dT	Specific enthalpy as function of density and temperature
h_dT	Specific enthalpy as function of density and temperature
h_dT_der	Derivative function of h_dT
p_props_dT	Pressure as function of density and temperature
p_dT	Pressure as function of density and temperature
p_dT_der	Derivative function of p_dT
s_props_dT	Specific entropy as function of density and temperature
s_dT	Temperature as function of density and temperature
cv_props_dT	Specific heat capacity at constant volume as function of density and temperature
cv_dT	Specific heat capacity at constant volume as function of density and temperature
cp_props_dT	Specific heat capacity at constant pressure as function of density and temperature
cp_dT	Specific heat capacity at constant pressure as function of density and temperature
beta_props_dT	Isobaric expansion coefficient as function of density and temperature
beta_dT	Isobaric expansion coefficient as function of density and temperature
kappa_props_dT	Isothermal compressibility factor as function of density and temperature
kappa_dT	Isothermal compressibility factor as function of density and temperature
velocityOfSound_props_dT	Speed of sound as function of density and temperature
velocityOfSound_dT	Speed of sound as function of density and temperature
isentropicExponent_props_dT	Isentropic exponent as function of density and temperature
isentropicExponent_dT	Isentropic exponent as function of density and temperature
ThermoFluidSpecialprotected
hl_p	Compute the saturated liquid specific h(p)
hv_p	Compute the saturated vapour specific h(p)
sl_p	Compute the saturated liquid specific s(p)
sv_p	Compute the saturated vapour specific s(p)
rhol_T	Compute the saturated liquid d(T)
rhov_T	Compute the saturated vapour d(T)
rhol_p	Compute the saturated liquid d(p)
rhov_p	Compute the saturated vapour d(p)
dynamicViscosity	Compute eta(d,T) in the one-phase region
thermalConductivity	Compute lambda(d,T,p) in the one-phase region
surfaceTension	Compute sigma(T) at saturation T
isentropicEnthalpy	Isentropic specific enthalpy from p,s (preferably use dynamicIsentropicEnthalpy in dynamic simulation!)
isentropicEnthalpy_props
isentropicEnthalpy_der	Derivative of isentropic specific enthalpy from p,s
dynamicIsentropicEnthalpy	Isentropic specific enthalpy from p,s and good guesses of d and T

Revisions

Intermediate release notes during development

Currently the Events/noEvents switch is only implemented for p-h states. Only after testing that implementation, it will be extended to dT.