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[thermo] Add IAPWS as alternative backend to existing Water wrapper

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While the current 'liquid-water-IAPWS95' thermo model only implements liquid
(and supercritical) states, the underlying IAPWS formulation can be extended
beyond in future revisions.

- avoid 'liquid' as part of the nomenclature
- YAML phase name is updated to `water-iapws95`
- Instead of creating a new wrapper, `iapws95` is added as an alternative
  backend to the existing `Water` class
This commit is contained in:
Ingmar Schoegl
2020-08-28 20:36:03 -05:00
committed by Ray Speth
parent 1880e2402c
commit 4ba894df55
5 changed files with 72 additions and 83 deletions
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2
data/liquidvapor.yaml
View File

@@ -25,7 +25,7 @@ phases:
T: 300.0
P: 1.01325e+05
pure-fluid-name: water
- name: liquid-water
- name: water-iapws95
elements: [O, H]
species: [H2O]
thermo: liquid-water-IAPWS95

120
interfaces/cython/cantera/liquidvapor.py
View File

@@ -4,64 +4,48 @@
from . import PureFluid, _cantera
def Water():
def Water(backend='default'):
"""
Create a `PureFluid` object using the equation of state for water and the
`WaterTransport` class for viscosity and thermal conductivity.
The object returned by this method implements an accurate equation of
state for water that can be used in the liquid, vapor, saturated
liquid/vapor, and supercritical regions of the phase diagram. The
equation of state is taken from
The object returned by this method implements an accurate equation of state
for water, where implementations are selected using the *backend* switch.
W. C. Reynolds, *Thermodynamic Properties in SI: graphs, tables, and
computational equations for forty substances.* Stanford: Stanford
University, 1979. Print.
For the ``default`` backend, the equation of state is taken from
whereas formulas for transport are taken from
W. C. Reynolds, *Thermodynamic Properties in SI: graphs, tables, and
computational equations for forty substances.* Stanford: Stanford
University, 1979. Print.
J. V. Sengers, J. T. R. Watson, *Improved International Formulations for
the Viscosity and Thermal Conductivity of Water Substance,* J. Phys. Chem.
Ref. Data, 15, 1291, 1986.
which can be used in the liquid, vapor, saturated liquid/vapor, and
supercritical regions of the phase diagram.
For more details, see classes Cantera::PureFluid, tpx::water and
Cantera::WaterTransport in the Cantera C++ source code documentation.
The ``iapws95`` backend implements an IAPWS (International Association for
the Properties of Water and Steam) formulation for thermodynamic properties
taken from
J. V. Sengers, J. T. R. Watson, *Improved International Formulations for
the Viscosity and Thermal Conductivity of Water Substance,* J. Phys.
Chem. Ref. Data, 15, 1291, 1986.
which currently only implements liquid and supercritical regions.
For more details, see classes Cantera::PureFluid, tpx::water,
Cantera::WaterSSTP and Cantera::WaterTransport in the Cantera C++ source
code documentation.
"""
class WaterWithTransport(PureFluid, _cantera.Transport):
__slots__ = ()
return WaterWithTransport('liquidvapor.yaml', 'water',
transport_model='Water')
if backend == 'default':
return WaterWithTransport('liquidvapor.yaml', 'water',
transport_model='Water')
if backend == 'iapws95':
return WaterWithTransport('liquidvapor.yaml', 'water-iapws95',
transport_model='Water')
def LiquidWater():
"""
Create a `PureFluid` object using the IAPWS Formulation 1995 for
thermodynamic properties and the `WaterTransport` class for viscosity
and thermal conductivity.
The object returned by this method implements an accurate equation of
state for water that can be used in the liquid and supercritical regions
of the phase diagram. The equation of state is taken from
W. Wagner, A. Pruss, *The IAPWS Formulation 1995 for the Thermodynamic
Properties of Ordinary Water Substance for General and Scientific Use,*
J. Phys. Chem. Ref. Dat, 31, 387, 2002.
whereas formulas for transport are taken from
J. V. Sengers, J. T. R. Watson, *Improved International Formulations for
the Viscosity and Thermal Conductivity of Water Substance,* J. Phys. Chem.
Ref. Data, 15, 1291, 1986.
For more details, see classes Cantera::PureFluid, Cantera::WaterSSTP and
Cantera::WaterTransport in the Cantera C++ source code documentation.
"""
class WaterWithTransport(PureFluid, _cantera.Transport):
__slots__ = ()
return WaterWithTransport('liquidvapor.yaml', 'liquid-water',
transport_model='Water')
raise KeyError("Unknown backend '{}'".format(backend))
def Nitrogen():
@@ -73,9 +57,9 @@ def Nitrogen():
liquid/vapor, and supercritical regions of the phase diagram. The
equation of state is taken from
W. C. Reynolds, *Thermodynamic Properties in SI: graphs, tables, and
computational equations for forty substances* Stanford: Stanford
University, 1979. Print.
W. C. Reynolds, *Thermodynamic Properties in SI: graphs, tables, and
computational equations for forty substances* Stanford: Stanford
University, 1979. Print.
For more details, see classes Cantera::PureFluid and tpx::nitrogen in the
Cantera C++ source code documentation.
@@ -92,9 +76,9 @@ def Methane():
liquid/vapor, and supercritical regions of the phase diagram. The
equation of state is taken from
W. C. Reynolds, *Thermodynamic Properties in SI: graphs, tables, and
computational equations for forty substances* Stanford: Stanford
University, 1979. Print.
W. C. Reynolds, *Thermodynamic Properties in SI: graphs, tables, and
computational equations for forty substances* Stanford: Stanford
University, 1979. Print.
For more details, see classes Cantera::PureFluid and tpx::methane in the
Cantera C++ source code documentation.
@@ -111,9 +95,9 @@ def Hydrogen():
liquid/vapor, and supercritical regions of the phase diagram. The
equation of state is taken from
W. C. Reynolds, *Thermodynamic Properties in SI: graphs, tables, and
computational equations for forty substances* Stanford: Stanford
University, 1979. Print.
W. C. Reynolds, *Thermodynamic Properties in SI: graphs, tables, and
computational equations for forty substances* Stanford: Stanford
University, 1979. Print.
For more details, see classes Cantera::PureFluid and tpx::hydrogen in the
Cantera C++ source code documentation.
@@ -130,9 +114,9 @@ def Oxygen():
liquid/vapor, and supercritical regions of the phase diagram. The
equation of state is taken from
W. C. Reynolds, *Thermodynamic Properties in SI: graphs, tables, and
computational equations for forty substances* Stanford: Stanford
University, 1979. Print.
W. C. Reynolds, *Thermodynamic Properties in SI: graphs, tables, and
computational equations for forty substances* Stanford: Stanford
University, 1979. Print.
For more details, see classes Cantera::PureFluid and tpx::oxygen in the
Cantera C++ source code documentation.
@@ -149,11 +133,11 @@ def Hfc134a():
vapor, saturated liquid/vapor, and supercritical regions of the phase
diagram. Implements the equation of state given in:
R. Tillner-Roth and H. D. Baehr. *An International Standard Formulation for
The Thermodynamic Properties of 1,1,1,2-Tetrafluoroethane (HFC-134a) for
Temperatures From 170 K to 455 K and Pressures up to 70 MPa.* J. Phys.
Chem. Ref. Data, Vol. 23, No. 5, 1994. pp. 657--729.
http://dx.doi.org/10.1063/1.555958
R. Tillner-Roth, H. D. Baehr. *An International Standard Formulation for
The Thermodynamic Properties of 1,1,1,2-Tetrafluoroethane (HFC-134a) for
Temperatures From 170 K to 455 K and Pressures up to 70 MPa.* J. Phys.
Chem. Ref. Data, Vol. 23, No. 5, 1994. pp. 657--729.
http://dx.doi.org/10.1063/1.555958
For more details, see classes Cantera::PureFluid and tpx::HFC134a in the
Cantera C++ source code documentation.
@@ -170,9 +154,9 @@ def CarbonDioxide():
liquid/vapor, and supercritical regions of the phase diagram. The
equation of state is taken from
W. C. Reynolds, *Thermodynamic Properties in SI: graphs, tables, and
computational equations for forty substances.* Stanford: Stanford
University, 1979. Print.
W. C. Reynolds, *Thermodynamic Properties in SI: graphs, tables, and
computational equations for forty substances.* Stanford: Stanford
University, 1979. Print.
For more details, see classes Cantera::PureFluid and tpx::CarbonDioxide in
the Cantera C++ source code documentation.
@@ -189,9 +173,9 @@ def Heptane():
liquid/vapor, and supercritical regions of the phase diagram. The
equation of state is taken from
W. C. Reynolds, *Thermodynamic Properties in SI: graphs, tables, and
computational equations for forty substances.* Stanford: Stanford
University, 1979. Print.
W. C. Reynolds, *Thermodynamic Properties in SI: graphs, tables, and
computational equations for forty substances.* Stanford: Stanford
University, 1979. Print.
For more details, see classes Cantera::PureFluid and tpx::Heptane in the
Cantera C++ source code documentation.

17
interfaces/cython/cantera/test/test_purefluid.py
View File

@@ -357,8 +357,17 @@ class TestPureFluid(utilities.CanteraTest):
co2 = ct.CarbonDioxide()
self.assertEqual(co2.phase_of_matter, "gas")
def test_liquidwater(self):
w = ct.LiquidWater()
def test_water_backends(self):
w = ct.Water(backend='default')
self.assertEqual(w.thermo_model, 'PureFluid')
w = ct.Water(backend='iapws95')
self.assertEqual(w.thermo_model, 'Water')
with self.assertRaisesRegex(KeyError, 'Unknown backend'):
ct.Water('foobar')
def test_water_iapws(self):
w = ct.Water(backend='iapws95')
self.assertNear(w.critical_density, 322.)
self.assertNear(w.critical_temperature, 647.096)
self.assertNear(w.critical_pressure, 22064000.0)
@@ -382,9 +391,9 @@ class TestPureFluid(utilities.CanteraTest):
self.assertEqual(w.phase_of_matter, "liquid")
w.TP = w.T, w.P_sat
self.assertEqual(w.phase_of_matter, "liquid")
with self.assertRaisesRegex(ct.CanteraError, "violates model assumptions"):
with self.assertRaisesRegex(ct.CanteraError, "Not implemented"):
w.TP = 273.1599999, ct.one_atm
with self.assertRaisesRegex(ct.CanteraError, "violates model assumptions"):
with self.assertRaisesRegex(ct.CanteraError, "Not implemented"):
w.TP = 500, ct.one_atm

14
src/thermo/WaterSSTP.cpp
View File

@@ -282,18 +282,14 @@ void WaterSSTP::setPressure(doublereal p)
dens = 1000.;
} else if (!m_allowGasPhase) {
throw CanteraError("WaterSSTP::setPressure",
"Pressure p = {} lies below the saturation "
"pressure\n(P_sat = {}), which violates model "
"assumptions.", p, pp);
"Not implemented: pressure p = {} lies below\n"
"the saturation pressure (P_sat = {}).", p, pp);
}
}
double dd = m_sub.density(T, p, waterState, dens);
if (dd <= 0.0) {
throw CanteraError("WaterSSTP::setPressure",
"error: T = {}, p = {}, psat = {}\n"
"density_guess = {}, density_fail = {}",
T, p, pp, dens, dd);
throw CanteraError("WaterSSTP::setPressure", "Error");
}
setDensity(dd);
}
@@ -344,8 +340,8 @@ void WaterSSTP::setTemperature(const doublereal temp)
{
if (temp < 273.16) {
throw CanteraError("WaterSSTP::setTemperature",
"Temperature T = {} lies below the triple point "
"temperature,\nwhich violates model assumptions.",
"Not implemented: temperature T = {} lies below\n"
"the triple point temperature (T_triple = 273.16).",
temp);
}
Phase::setTemperature(temp);

2
test_problems/cathermo/testWaterTP/testWaterSSTP.cpp
View File

@@ -21,7 +21,7 @@ int main()
#endif
double pres;
try {
ThermoPhase* w = newPhase("liquid-water.xml");
ThermoPhase* w = newPhase("liquidvapor.yaml", "water-iapws95");
(dynamic_cast<WaterSSTP*>(w))->allowGasPhase(true);
/*