spontarelliam / iapws

python libray for IAPWS standard calculation of water and steam properties

iapws

Python implementation of standard from IAPWS (http://www.iapws.org/release.html). The available standard are:

IAPWS-IF97
IAPWS-95
IAPWS-06 for Ice
IAPWS-08 for seawater
IAPWS-05 for Heavy water

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

Improve convergence in two phase region for IAPWS95 and D2O class

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 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

IAPWS-05 for Heavy water

Same properties as for IAPWS-95 Reference state set at liquid at normal boiling point (1 atm)

Usage:

from iapws import D2O
sat_liquid=D2O(T=370, x=0)            #saturated liquid with known T
print(sat_liquid.h) #calculated enthalpy

IAPWS-08 for seawater

Incoming properties:

• T: Temperature, K
• P: Pressure, MPa
• S: Salinity, kg/kg

S is the Reference-Composition Salinity as defined in Millero, F.J., R. Feistel, D.G. Wright and T.J. McDougall, "The composition of Standard Seawater and the definition of the Reference-Composition Salinity Scale", Deep-Sea Res. I 55, 50 (2008).

Calculated 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
• 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
• gt: Derivative Gibbs energy with temperature, kJ/kg·K
• gp: Derivative Gibbs energy with pressure, m³/kg
• gtt: Derivative Gibbs energy with temperature square, kJ/kg·K²
• gtp: Derivative Gibbs energy with pressure and temperature, m³/kg·K
• gpp: Derivative Gibbs energy with temperature square, m³/kg·MPa
• gs: Derivative Gibbs energy with salinity, kJ/kg
• gsp: Derivative Gibbs energy with salinity and pressure, m³/kg
• alfa: Thermal expansion coefficient, 1/K
• betas: Isentropic temperature-pressure coefficient, K/MPa
• kt: Isothermal compressibility, 1/MPa
• ks: Isentropic compressibility, 1/MPa
• w: Sound Speed, m/s
• mu: Relative chemical potential, kJ/kg
• muw: Chemical potential of H2O, kJ/kg
• mus: Chemical potential of sea salt, kJ/kg
• osm: Osmotic coefficient, [-]
• haline: Haline contraction coefficient, kg/kg

Usage:

from iapws import SeaWater
state = SeaWater(T=300, P=0.101325, S=0.001)    #Seawater with 0.1% Salinity
print(state.cp)     # Get cp