iapws.iapws08 module

IAPWS standard for Seawater IAPWS08 and related functionality. The module include:

SeaWater: Global module class with all the functionality integrated

Other functionality:

_Tb(): Boiling temperature of seawater
_Tf(): Freezing temperature of seawater
_Triple(): Triple point properties of seawater
_OsmoticPressure(): Osmotic pressure of seawater
_ThCond_SeaWater(): Thermal conductivity of seawater
_Tension_SeaWater(): Surface tension of seawater
_solNa2SO4(): Solubility of sodium sulfate in aqueous mixtures of sodium chloride and sulfuric acid
_critNaCl(): Critical locus of aqueous solutions of sodium chloride

class iapws.iapws08.SeaWater(**kwargs)[source]

Class to model seawater with standard IAPWS-08

Parameters:

T (float) – Temperature, [K]
P (float) – Pressure, [MPa]
S (float) – Salinity, [kg/kg]
fast (bool, default False) – Use the Supplementary release SR7-09 to speed up the calculation
IF97 (bool, default False) – Use the Advisory Note No. 5 with industrial formulation

Returns:

rho (float) – Density, [kg/m³]
v (float) – Specific volume, [m³/kg]
h (float) – Specific enthalpy, [kJ/kg]
s (float) – Specific entropy, [kJ/kg·K]
u (float) – Specific internal energy, [kJ/kg]
g (float) – Specific Gibbs free energy, [kJ/kg]
a (float) – Specific Helmholtz free energy, [kJ/kg]
cp (float) – Specific isobaric heat capacity, [kJ/kg·K]
cv (float) – Specific isochoric heat capacity, [kJ/kg·K]
gt (float) – Derivative Gibbs energy with temperature, [kJ/kg·K]
gp (float) – Derivative Gibbs energy with pressure, [m³/kg]
gtt (float) – Derivative Gibbs energy with temperature square, [kJ/kg·K²]
gtp (float) – Derivative Gibbs energy with pressure and temperature, [m³/kg·K]
gpp (float) – Derivative Gibbs energy with temperature square, [m³/kg·MPa]
gs (float) – Derivative Gibbs energy with salinity, [kJ/kg]
gsp (float) – Derivative Gibbs energy with salinity and pressure, [m³/kg]
alfav (float) – Thermal expansion coefficient, [1/K]
betas (float) – Isentropic temperature-pressure coefficient, [K/MPa]
xkappa (float) – Isothermal compressibility, [1/MPa]
ks (float) – Isentropic compressibility, [1/MPa]
w (float) – Sound Speed, [m/s]
k (float) – Thermal conductivity, [W/m·K]
sigma (float) – Surface tension, [N/m]
m (float) – Molality of seawater, [mol/kg]
mu (float) – Relative chemical potential, [kJ/kg]
muw (float) – Chemical potential of H2O, [kJ/kg]
mus (float) – Chemical potential of sea salt, [kJ/kg]
osm (float) – Osmotic coefficient, [-]
haline (float) – Haline contraction coefficient, [kg/kg]

Notes

Warning if input isn’t in limit:

261 ≤ T ≤ 353

0 < P ≤ 100

0 ≤ S ≤ 0.12

References

IAPWS, Release on the IAPWS Formulation 2008 for the Thermodynamic Properties of Seawater, http://www.iapws.org/relguide/Seawater.html

IAPWS, Supplementary Release on a Computationally Efficient Thermodynamic Formulation for Liquid Water for Oceanographic Use, http://www.iapws.org/relguide/OceanLiquid.html

IAPWS, Guideline on the Thermal Conductivity of Seawater, http://www.iapws.org/relguide/Seawater-ThCond.html

IAPWS, Guideline on the Surface Tension of Seawater, http://www.iapws.org/relguide/Seawater-Surf.html

IAPWS, Revised Advisory Note No. 3: Thermodynamic Derivatives from IAPWS Formulations, http://www.iapws.org/relguide/Advise3.pdf

IAPWS, Advisory Note No. 5: Industrial Calculation of the Thermodynamic Properties of Seawater, http://www.iapws.org/relguide/Advise5.html

Examples

>>> salt = iapws.SeaWater(T=300, P=1, S=0.04)
>>> salt.rho
1026.7785717245113
>>> salt.gs
88.56221805501536
>>> salt.haline
0.7311487666026304

Attributes:

P
T
a
alfav
betas
cp
cv
h
haline
k
ks
m
mu
mus
muw
osm
rho
s
sigma
u
v
w
xkappa

Methods

`__call__`(**kwargs)	Make instance callable to can add input parameter one to one
`calculo`()	Calculate procedure
`derivative`(z, x, y)	Wrapper derivative for custom derived properties where x, y, z can be: P, T, v, u, h, s, g, a
`saline`(T, P, S)	Eq 4

status = 0

msg = 'Undefined'

T = None

P = None

rho = None

v = None

s = None

cp = None

cv = None

h = None

u = None

a = None

alfav = None

betas = None

xkappa = None

ks = None

w = None

k = None

sigma = None

m = None

mu = None

muw = None

mus = None

osm = None

haline = None

kwargs = {'IF97': False, 'P': 0.0, 'S': None, 'T': 0.0, 'fast': False}

calculo()[source]: Calculate procedure

derivative(z, x, y)[source]: Wrapper derivative for custom derived properties where x, y, z can be: P, T, v, u, h, s, g, a

classmethod _water(T, P)[source]: Get properties of pure water, Table4 pag 8

classmethod _waterIF97(T, P)[source]

classmethod _waterSupp(T, P)[source]: Get properties of pure water using the supplementary release SR7-09, Table4 pag 6

classmethod saline(T, P, S)[source]: Eq 4

iapws.iapws08._Tb(P, S)[source]

Procedure to calculate the boiling temperature of seawater

Parameters:

P (float) – Pressure, [MPa]
S (float) – Salinity, [kg/kg]

Returns:

Tb – Boiling temperature, [K]

Return type:

float

References

IAPWS, Advisory Note No. 5: Industrial Calculation of the Thermodynamic Properties of Seawater, http://www.iapws.org/relguide/Advise5.html, Eq 7

iapws.iapws08._Tf(P, S)[source]

Procedure to calculate the freezing temperature of seawater

Parameters:

P (float) – Pressure, [MPa]
S (float) – Salinity, [kg/kg]

Returns:

Tf – Freezing temperature, [K]

Return type:

float

References

IAPWS, Advisory Note No. 5: Industrial Calculation of the Thermodynamic Properties of Seawater, http://www.iapws.org/relguide/Advise5.html, Eq 12

iapws.iapws08._Triple(S)[source]

Procedure to calculate the triple point pressure and temperature for seawater

Parameters:

S (float) – Salinity, [kg/kg]

Returns:

prop –

Dictionary with the triple point properties:

Tt: Triple point temperature, [K]

Pt: Triple point pressure, [MPa]

Return type:

dict

References

IAPWS, Advisory Note No. 5: Industrial Calculation of the Thermodynamic Properties of Seawater, http://www.iapws.org/relguide/Advise5.html, Eq 7

iapws.iapws08._OsmoticPressure(T, P, S)[source]

Procedure to calculate the osmotic pressure of seawater

Parameters:

T (float) – Tmperature, [K]
P (float) – Pressure, [MPa]
S (float) – Salinity, [kg/kg]

Returns:

Posm – Osmotic pressure, [MPa]

Return type:

float

References

IAPWS, Advisory Note No. 5: Industrial Calculation of the Thermodynamic Properties of Seawater, http://www.iapws.org/relguide/Advise5.html, Eq 15

iapws.iapws08._ThCond_SeaWater(T, P, S)[source]

Equation for the thermal conductivity of seawater

Parameters:

T (float) – Temperature, [K]
P (float) – Pressure, [MPa]
S (float) – Salinity, [kg/kg]

Returns:

k – Thermal conductivity excess relative to that of the pure water, [W/mK]

Return type:

float

Notes

Raise NotImplementedError if input isn’t in limit:

273.15 ≤ T ≤ 523.15

0 ≤ P ≤ 140

0 ≤ S ≤ 0.17

Examples

>>> _ThCond_Seawater(293.15, 0.1, 0.035)
-0.00418604

References

IAPWS, Guideline on the Thermal Conductivity of Seawater, http://www.iapws.org/relguide/Seawater-ThCond.html

iapws.iapws08._Tension_SeaWater(T, S)[source]

Equation for the surface tension of seawater

Parameters:

T (float) – Temperature, [K]
S (float) – Salinity, [kg/kg]

Returns:

σ – Surface tension, [N/m]

Return type:

float

Notes

Raise NotImplementedError if input isn’t in limit:

0 ≤ S ≤ 0.131 for 274.15 ≤ T ≤ 365.15

0 ≤ S ≤ 0.038 for 248.15 ≤ T ≤ 274.15

Examples

>>> _Tension_Seawater(253.15, 0.035)
-0.07922517961

References

IAPWS, Guideline on the Surface Tension of Seawater, http://www.iapws.org/relguide/Seawater-Surf.html

iapws.iapws08._solNa2SO4(T, mH2SO4, mNaCl)[source]

Equation for the solubility of sodium sulfate in aqueous mixtures of sodium chloride and sulfuric acid

Parameters:

T (float) – Temperature, [K]
mH2SO4 (float) – Molality of sufuric acid, [mol/kg(water)]
mNaCl (float) – Molality of sodium chloride, [mol/kg(water)]

Returns:

S – Molal solutility of sodium sulfate, [mol/kg(water)]

Return type:

float

Notes

Raise NotImplementedError if input isn’t in limit:

523.15 ≤ T ≤ 623.15

0 ≤ mH2SO4 ≤ 0.75

0 ≤ mNaCl ≤ 2.25

Examples

>>> _solNa2SO4(523.15, 0.25, 0.75)
2.68

References

IAPWS, Solubility of Sodium Sulfate in Aqueous Mixtures of Sodium Chloride and Sulfuric Acid from Water to Concentrated Solutions, http://www.iapws.org/relguide/na2so4.pdf

iapws.iapws08._critNaCl(x)[source]

Equation for the critical locus of aqueous solutions of sodium chloride

Parameters:

x (float) – Mole fraction of NaCl, [-]

Returns:

prop –

A dictionary withe the properties:

Tc: critical temperature, [K]

Pc: critical pressure, [MPa]

rhoc: critical density, [kg/m³]

Return type:

dict

Notes

Raise NotImplementedError if input isn’t in limit:

0 ≤ x ≤ 0.12

Examples

>>> _critNaCl(0.1)
975.571016

References

IAPWS, Revised Guideline on the Critical Locus of Aqueous Solutions of Sodium Chloride, http://www.iapws.org/relguide/critnacl.html