iapws._utils module

Miscelaneous internal utilities. This module include:

getphase(): Get phase string of state

_fase: Base class to define a phase state

deriv_H(): Calculate generic partial derivative with a fundamental Helmholtz free energy equation of state

deriv_G(): Calculate generic partial derivative with a fundamental Gibbs free energy equation of state

iapws._utils.getphase(Tc, Pc, T, P, x, region)[source]

Return fluid phase string name

Parameters:

Tc (float) – Critical temperature, [K]
Pc (float) – Critical pressure, [MPa]
T (float) – Temperature, [K]
P (float) – Pressure, [MPa]
x (float) – Quality, [-]
region (int) – Region number, used only for IAPWS97 region definition

Returns:

phase – Phase name

Return type:

str

class iapws._utils._fase[source]

Class to implement a null phase

Attributes:

Gruneisen
IntP
Ks
Kt
Prandt
Z
Z_rho
a
alfa
alfap
alfav
betap
betas
cp
cp_cv
cv
dhdP_T
dhdP_rho
dhdT_P
dhdT_rho
dhdrho_P
dhdrho_T
dpdT_rho
dpdrho_T
drhodP_T
drhodT_P
epsilon
f
fi
g
gamma
h
hInput
joule
k
kappa
ks
kt
mu
n
nu
rho
s
u
v
w

iapws._utils.deriv_H(state, z, x, y, fase)[source]

Calculate generic partial derivative \(\left.\frac{\partial z}{\partial x}\right|_{y}\) from a fundamental helmholtz free energy equation of state

Parameters:

state (any python object) – Only need to define P and T properties, non phase specific properties
z (str) – Name of variables in numerator term of derivatives
x (str) – Name of variables in denominator term of derivatives
y (str) – Name of constant variable in partial derivaritive
fase (any python object) – Define phase specific properties (v, cv, alfap, s, betap)

Notes

x, y and z can be the following values:

P: Pressure

T: Temperature

v: Specific volume

rho: Density

u: Internal Energy

h: Enthalpy

s: Entropy

g: Gibbs free energy

a: Helmholtz free energy

Returns:: deriv – ∂z/∂x|y
Return type:: float

References

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

iapws._utils.deriv_G(state, z, x, y, fase)[source]

Calculate generic partial derivative \(\left.\frac{\partial z}{\partial x}\right|_{y}\) from a fundamental Gibbs free energy equation of state

Parameters:

state (any python object) – Only need to define P and T properties, non phase specific properties
z (str) – Name of variables in numerator term of derivatives
x (str) – Name of variables in denominator term of derivatives
y (str) – Name of constant variable in partial derivaritive
fase (any python object) – Define phase specific properties (v, cp, alfav, s, xkappa)

Notes

x, y and z can be the following values:

P: Pressure

T: Temperature

v: Specific volume

rho: Density

u: Internal Energy

h: Enthalpy

s: Entropy

g: Gibbs free energy

a: Helmholtz free energy

Returns:: deriv – ∂z/∂x|y
Return type:: float

References

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