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)

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

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)

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)

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