def iterate_to_solve_Z(self, T, P, phase) -> float:
"""
:param T: temperature in K
:param P: pressure in Pa
:param phase: phase [vapor or liquid]
:type phase: str
:return: compressibility factor
"""
beta = self.beta_expr(T, P)
q = self.q_expr(T)
if phase == 'liquid':
Z_nm1 = beta
func = self.Z_liquid_RHS
elif phase == 'vapor':
Z_nm1 = 1.
func = self.Z_vapor_RHS
else:
raise Exception('Phase {} not found!'.format(phase))
Z_n = func(Z_nm1, beta, q)
while percent_difference(Z_n, Z_nm1) > self.tol:
Z_nm1 = Z_n
Z_n = func(Z_nm1, beta, q)
return Z_n
def __init__(self,
dippr_no: str = None,
compound_name: str = None,
cas_number: str = None,
T_min_fit: float = None,
T_max_fit: float = None,
n_points_fit: int = 1000,
poly_order: int = 2):
from scithermo import os, ROOT_DIR
file = os.path.join(ROOT_DIR, 'vapor_viscosity.csv')
my_header = [
'Cmpd. no.', 'Name', 'Formula', 'CAS no.', 'Mol. wt. [g/mol]',
'C1', 'C2', 'C3', 'C4', 'Tmin [K]', 'Val at Tmin', 'Tmax [K]',
'Val at Tmax'
]
self.dippr_no = dippr_no
self.compound_name = compound_name
self.cas_number = cas_number
found_compound = False
self.units = 'Pa*s'
with open(file, 'r') as f:
header = next(f).rstrip('\n').split(',')
assert header == my_header, 'Wrong header!'
for line in f:
vals = line.rstrip('\n').split(',')
if vals[0] == self.dippr_no or vals[
1] == self.compound_name or vals[3] == self.cas_number:
assert not found_compound, 'Input compound found twice in table!'
found_compound = True
(self.dippr_no, self.compound_name, self.formula,
self.cas_number) = vals[:4]
(self.MW, self.C1, self.C2, self.C3, self.C4, self.T_min,
self.mu_T_min, self.T_max,
self.mu_T_max) = map(float, vals[4:])
assert found_compound, 'No compound was found in table! for {}, {}, {}'.format(
self.dippr_no, self.compound_name, self.cas_number)
# test that values are consistent
if percent_difference(self.mu_T_min, self.eval(self.T_min)) > 0.1:
raise Exception('Inconsistent data for {}'.format(
self.compound_name))
if percent_difference(self.mu_T_max, self.eval(self.T_max)) > 0.1:
raise Exception('Inconsistent data for {}'.format(
self.compound_name))
self.T_min_fit = T_min_fit
self.T_max_fit = T_max_fit
if self.T_min_fit is None:
self.T_min_fit = self.T_min
if self.T_max_fit is None:
self.T_max_fit = self.T_max
self.T_fit = np.linspace(self.T_min_fit, self.T_max_fit, n_points_fit)
assert self.T_min <= self.T_min_fit < self.T_max, 'Minimum temp not in correct range: {} !<= {} !<= {}'.format(
self.T_min, self.T_min_fit, self.T_max)
assert self.T_min < self.T_max_fit <= self.T_max, 'Max temp not in correct range: {} !< {} !<= {}'.format(
self.T_min, self.T_max_fit, self.T_max)
self.poly_order = poly_order
y = self.eval(self.T_fit)
self.coeffs = np.polyfit(self.T_fit, y, self.poly_order)
ssxm, ssxym, ssyxm, ssym = np.cov(self.T_fit, y, bias=1).flat
self.R2 = ssxym * ssxym / (ssxm * ssym)
assert self.R2 > 0.98, 'Poor fit to polynomial, R2 is only %3.2f' % self.R2
self.mu = np.poly1d(self.coeffs)
def test_cp_star_Tmax(self):
for i in compounds_to_test:
I = CpStar(compound_name=i, T_ref=300., **self.kwargs)
self.assertTrue(
percent_difference(I.Cp_Tmax, I.eval(I.T_max)) < self.tol)
def test_cp_ig_Tmax(self):
for i in compounds_to_test:
I = CpIdealGas(compound_name=i, **self.kwargs)
self.assertTrue(
percent_difference(I.Cp_Tmax, I.eval(I.T_max)) < self.tol)
def get_max_percent_difference(self):
"""Get largest percent difference"""
y_fit = self.Cp_poly(self.T_fit)
pd = [percent_difference(i, j) for i, j in zip(y_fit, self.Cp_fit)]
return max(pd)
def get_numerical_percent_difference(self):
"""Calculate the percent difference with numerical integration obtained by :ref:`scipy`"""
integral_poly_fit = self.cp_integral(self.T_min_fit, self.T_max_fit)
integral_numerical, err_numerical = self.numerical_integration(
self.T_min_fit, self.T_max_fit)
return percent_difference(integral_poly_fit, integral_numerical)