iapws 1.0.5

Python implementation of standard from The International Association for the Properties of Water and Steam (http://www.iapws.org)

Python implementation of international-standard IAPWS. The available standard are:

IAPWS-IF97
IAPWS-95
IAPWS-06 for Ice

dependences

• python 2x;3x, compatible with both versions

• Numpy-scipy: library with mathematic and scientific tools

install

In debian you can find in official repositories in testing and sid. In stable you can install using pip:

pip install iapws

In ubuntu it’s in official repositories from ubuntu saucy (13.10)

In other SO you can download from its webpage in pypi and unzipped in python folder dist-packages. This is the recommended options to have the latest version.

TODO

• Add IAPWS-08 for seawater

• Add IAPWS-05 for Heavy water

IAPWS-IF97

Class to model a state for liquid water or steam with the Industrial Formulation IAPWS-IF97

Incoming properties:

• T, Temperature, K

• P, Pressure, MPa

• h, Specific enthalpy, kJ/kg

• s, Specific entropy, kJ/kg·K

• x, Quality, [-]

Definitions options:

• T, P (Not valid for two-phases region)

• P, h

• P, s

• h, s

• T, x (Only for two-phases region)

• P, x (Only for two-phases region)

Properties:

• P, Pressure, MPa

• T, Temperature, K

• g, Specific Gibbs free energy, kJ/kg

• a, Specific Helmholtz free energy, kJ/kg

• v, Specific volume, m³/kg

• rho, Density, kg/m³

• x, quality, [-]

• h, Specific enthalpy, kJ/kg

• u, Specific internal energy, kJ/kg

• s, Specific entropy, kJ/kg·K

• cp, Specific isobaric heat capacity, kJ/kg·K

• cv, Specific isochoric heat capacity, kJ/kg·K

• Z, Compression factor. [-]

• gamma, Isoentropic exponent, [-]

• alfav, Isobaric cubic expansion coefficient, 1/K

• kt, Isothermal compressibility, 1/MPa

• alfap, Relative pressure coefficient, 1/K

• betap, Isothermal stress coefficient, kg/m³

• joule, Joule-Thomson coefficient, K/MPa

• deltat, Isothermal throttling coefficient, kJ/kg·MPa

• region, Region

• v0, Ideal specific volume, m³/kg

• u0, Ideal specific internal energy, kJ/kg

• h0, Ideal specific enthalpy, kJ/kg

• s0, Ideal specific entropy, kJ/kg·K

• a0, Ideal specific Helmholtz free energy, kJ/kg

• g0, Ideal specific Gibbs free energy, kJ/kg

• cp0, Ideal specific isobaric heat capacity, kJ/kg·K

• cv0, Ideal specific isochoric heat capacity, kJ/kg·K

• w0, Ideal speed of sound, m/s

• gamma0, Ideal isoentropic exponent [-]

• w, Speed of sound, m/s

• mu, Dynamic viscosity, Pa·s

• nu, Kinematic viscosity, m²/s

• k, Thermal conductivity, W/m·K

• alfa, Thermal diffusivity, m²/s

• sigma, Surface tension, N/m

• epsilon, Dielectric constant, [-]

• n, Refractive index, [-]

• Prandt, Prandtl number, [-]

• Tr, Reduced temperature, [-]

• Pr, Reduced pressure, [-]

Usage:

from iapws import IAPWS97
sat_steam=IAPWS97(P=1,x=1)                #saturated steam with known P
sat_liquid=IAPWS97(T=370, x=0)            #saturated liquid with known T
steam=IAPWS97(P=2.5, T=500)               #steam with known P and T
print(sat_steam.h, sat_liquid.h, steam.h) #calculated enthalpies

IAPWS-95

Class to model a state for liquid water or steam with the General and Scientific Formulation IAPWS-95

Incoming properties:

• T, Temperature, K

• P, Pressure, MPa

• rho, Density, kg/m3

• v, Specific volume, m3/kg

• h, Specific enthalpy, kJ/kg

• s, Specific entropy, kJ/kg·K

• x, Quality, [-]

• l, Optional parameter to light wavelength for Refractive index, mm

rho and v are equivalent, only one can be defined Definitions options:

• T, P (Not valid for two-phases region)

• T, rho

• T, h

• T, s

• T, u

• P, rho

• P, h

• P, s

• P, u

• rho, h

• rho, s

• rho, u

• h, s

• h, u

• s, u

• T, x (Only for two-phases region)

• P, x (Only for two-phases region) Very slow

Properties:

• P, Pressure, MPa

• Pr, Reduced pressure, [-]

• T, Temperature, K

• Tr, Reduced temperature, [-]

• x, Quality, [-]

• v, Specific volume, m³/kg

• rho, Density, kg/m³

• h, Specific enthalpy, kJ/kg

• s, Specific entropy, kJ/kg·K

• u, Specific internal energy, kJ/kg

• g, Specific Gibbs free energy, kJ/kg

• a, Specific Helmholtz free energy, kJ/kg

• cp, Specific isobaric heat capacity, kJ/kg·K

• cv, Specific isochoric heat capacity, kJ/kg·K

• cp_cv, Heat capacity ratio, [-]

• w, Speed of sound, m/s

• Z, Compression factor, [-]

• fi, Fugacity coefficient, [-]

• f, Fugacity, MPa

• gamma, Isoentropic exponent, [-]

• alfav, Thermal expansion coefficient (Volume expansivity), 1/K

• kappa, Isothermal compressibility, 1/MPa

• alfap, Relative pressure coefficient, 1/K

• betap, Isothermal stress coefficient, kg/m³

• betas, Isoentropic temperature-pressure coefficient, [-]

• joule, Joule-Thomson coefficient, K/MPa

• Gruneisen, Gruneisen parameter, [-]

• virialB, Second virial coefficient, m³/kg

• virialC, Third virial coefficient, m⁶/kg²

• dpdT_rho, Derivatives, dp/dT at constant rho, MPa/K

• dpdrho_T, Derivatives, dp/drho at constant T, MPa·m³/kg

• drhodT_P, Derivatives, drho/dT at constant P, kg/m³·K

• drhodP_T, Derivatives, drho/dP at constant T, kg/m³·MPa

• dhdT_rho, Derivatives, dh/dT at constant rho, kJ/kg·K

• dhdP_T, Isothermal throttling coefficient, kJ/kg·MPa

• dhdT_P, Derivatives, dh/dT at constant P, kJ/kg·K

• dhdrho_T, Derivatives, dh/drho at constant T, kJ·m³/kg²

• dhdrho_P, Derivatives, dh/drho at constant P, kJ·m³/kg²

• dhdP_rho, Derivatives, dh/dP at constant rho, kJ/kg·MPa

• kt, Isothermal Expansion Coefficient, [-]

• ks, Adiabatic Compressibility, 1/MPa

• Ks, Adiabatic bulk modulus, MPa

• Kt, Isothermal bulk modulus, MPa

• Hvap, Vaporization heat, kJ/kg

• Z_rho, (Z-1) over the density, m³/kg

• IntP, Internal pressure, MPa

• invT, Negative reciprocal temperature, 1/K

• hInput, Specific heat input, kJ/kg

• mu, Dynamic viscosity, Pa·s

• nu, Kinematic viscosity, m²/s

• k, Thermal conductivity, W/m·K

• sigma, Surface tension, N/m

• alfa, Thermal diffusivity, m²/s

• Pramdt, Prandtl number, [-]

• epsilon, Dielectric constant, [-]

• n, Refractive index, [-]

• v0, Ideal gas Specific volume, m³/kg

• rho0, Ideal gas Density, kg/m³

• h0, Ideal gas Specific enthalpy, kJ/kg

• u0, Ideal gas Specific internal energy, kJ/kg

• s0, Ideal gas Specific entropy, kJ/kg·K

• a0, Ideal gas Specific Helmholtz free energy, kJ/kg

• g0, Ideal gas Specific Gibbs free energy, kJ/kg

• cp0, Ideal gas Specific isobaric heat capacity, kJ/kg·K

• cv0, Ideal gas Specific isochoric heat capacity, kJ/kg·K

• cp0_cv, Ideal gas Heat capacity ratio, [-]

• gamma0, Ideal gas Isoentropic exponent, [-]

Usage:

from iapws import IAPWS95
sat_steam=IAPWS95(P=1,x=1)                #saturated steam with known P
sat_liquid=IAPWS95(T=370, x=0)            #saturated liquid with known T
steam=IAPWS95(P=2.5, T=500)               #steam with known P and T
print(sat_steam.h, sat_liquid.h, steam.h) #calculated enthalpies

IAPWS-06 for Ice Ih

There is too implemented a function to calculate properties of ice Ih from 2009 revision, in this case only let temperature and pressure as input for calculate properties, the function return a dict with the properties available:

• P, Pressure, MPa

• T, Temperature, K

• v, Specific volume, m³/kg

• rho, Density, kg/m³

• g, Specific Gibbs free energy, kJ/kg

• a, Specific Helmholtz free energy, kJ/kg

• h, Specific enthalpy, kJ/kg

• u, Specific internal energy, kJ/kg

• s, Specific entropy, kJ/kg·K

• cp, Specific isobaric heat capacity, kJ/kg·K

• alfa, Cubic expansion coefficient, 1/K

• beta, Pressure coefficient, MPa/K

• kt, Isothermal compressibility, MPa

• ks, Isentropic compressibility, MPa

Usage:

from iapws import _Ice
ice=_Ice(273.15, 0.101325)            #Ice at normal melting point
print(ice["rho"])                     #Calculated density