How to use pcsaft - 10 common examples
To help you get started, we’ve selected a few pcsaft examples, based on popular ways it is used in public projects.
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zmeri / PC-SAFT / tests / test_cython.py View on Github 
eAB = np.asarray([0, 0, 2425.67])
k_ij = np.asarray([[0, 0.317, 0],
[0.317, 0, -0.25],
[0, -0.25, 0]])
z = np.asarray([1., -1., 0.])
ref = 55507.23 # source: Rodriguez H.; Soto A.; Arce A.; Khoshkbarchi M.K.: Apparent Molar Volume, Isentropic Compressibility, Refractive Index, and Viscosity of DL-Alanine in Aqueous NaCl Solutions. J.Solution Chem. 32 (2003) 53-63
t = 298.15 # K
s[2] = 2.7927 + 10.11*np.exp(-0.01775*t) - 1.417*np.exp(-0.01146*t) # temperature dependent segment diameter for water
k_ij[0,2] = -0.007981*t + 2.37999
k_ij[2,0] = -0.007981*t + 2.37999
dielc = dielc_water(t)
pyargs = {'m':m, 's':s, 'e':e, 'e_assoc':eAB, 'vol_a':volAB, 'k_ij':k_ij, 'z':z, 'dielc':dielc}
calc = pcsaft_den(t, 101325, x, pyargs, phase='liq')
if print_result:
print('\n########## Test with aqueous NaCl ##########')
print('----- Density at 298.15 K and 101325 Pa -----')
print(' Reference:', ref, 'mol m^-3')
print(' PC-SAFT:', calc, 'mol m^-3')
print(' Relative deviation:', (calc-ref)/ref*100, '%')
assert abs((calc-ref)/ref*100) < 2
# Propane
x = np.asarray([1.])
m = np.asarray([2.0020])
s = np.asarray([3.6184])
e = np.asarray([208.11])
pyargs = {'m':m, 's':s, 'e':e}
t = 85.525 # KeAB = np.asarray([0, 0, 2425.67])
k_ij = np.asarray([[0, 0.317, 0],
[0.317, 0, -0.25],
[0, -0.25, 0]])
z = np.asarray([1., -1., 0.])
t = 298.15 # K
p = 100000. # Pa
s[2] = 2.7927 + 10.11*np.exp(-0.01775*t) - 1.417*np.exp(-0.01146*t) # temperature dependent segment diameter for water
k_ij[0,2] = -0.007981*t + 2.37999
k_ij[2,0] = -0.007981*t + 2.37999
dielc = dielc_water(t)
pyargs = {'m':m, 's':s, 'e':e, 'e_assoc':eAB, 'vol_a':volAB, 'k_ij':k_ij, 'z':z, 'dielc':dielc}
rho = pcsaft_den(t, p, x, pyargs, phase='liq')
dadt_eos = pcsaft_dadt(t, rho, x, pyargs)
# calculating numerical derivative
der1 = pcsaft_ares(t-1, rho, x, pyargs)
der2 = pcsaft_ares(t+1, rho, x, pyargs)
dadt_num = (der2-der1)/2.
if print_result:
print('\n########## Test with aqueous NaCl ##########')
print(' Numerical derivative:', dadt_num)
print(' PC-SAFT derivative:', dadt_eos)
print(' Relative deviation:', (dadt_eos-dadt_num)/dadt_num*100, '%')
assert abs((dadt_eos-dadt_num)/dadt_num*100) < 2e-2t = 85.525 # K
p = 1.7551e-4 # Pa
ref = 16621.0 # source: reference EOS in CoolProp
calc = pcsaft_den(t, p, x, pyargs, phase='liq')
if print_result:
print('########## Test with propane ##########')
print('----- Density at {} K and {} Pa -----'.format(t, p))
print(' Reference:', ref, 'mol m^-3')
print(' PC-SAFT:', calc, 'mol m^-3')
print(' Relative deviation:', (calc-ref)/ref*100, '%')
assert abs((calc-ref)/ref*100) < 2
t = 85.525 # K
p = 1.39e-4 # Pa
ref = 1.9547e-7 # source: reference EOS in CoolProp
calc = pcsaft_den(t, p, x, pyargs, phase='vap')
if print_result:
print('----- Density at {} K and {} Pa -----'.format(t, p))
print(' Reference:', ref, 'mol m^-3')
print(' PC-SAFT:', calc, 'mol m^-3')
print(' Relative deviation:', (calc-ref)/ref*100, '%')
assert abs((calc-ref)/ref*100) < 2
t = 293 # K
p = 833240 # Pa
ref = 11346.0 # source: reference EOS in CoolProp
calc = pcsaft_den(t, p, x, pyargs, phase='liq')
if print_result:
print('----- Density at {} K and {} Pa -----'.format(t, p))
print(' Reference:', ref, 'mol m^-3')
print(' PC-SAFT:', calc, 'mol m^-3')
print(' Relative deviation:', (calc-ref)/ref*100, '%')print('----- Density at 305 K and 101325 Pa -----')
print(' Reference:', ref, 'mol m^-3')
print(' PC-SAFT:', calc, 'mol m^-3')
print(' Relative deviation:', (calc-ref)/ref*100, '%')
assert abs((calc-ref)/ref*100) < 2
# Dimethyl ether
m = np.asarray([2.2634])
s = np.asarray([3.2723])
e = np.asarray([210.29])
dpm = np.asarray([1.3])
dip_num = np.asarray([1.0])
pyargs = {'m':m, 's':s, 'e':e, 'dipm':dpm, 'dip_num':dip_num}
ref = 16110. # source: DIPPR correlation
calc = pcsaft_den(240, 101325, x, pyargs, phase='liq')
if print_result:
print('\n########## Test with dimethyl ether ##########')
print('----- Density at 240 K and 101325 Pa -----')
print(' Reference:', ref, 'mol m^-3')
print(' PC-SAFT:', calc, 'mol m^-3')
print(' Relative deviation:', (calc-ref)/ref*100, '%')
assert abs((calc-ref)/ref*100) < 2
# Binary mixture: methanol-cyclohexane
#0 = methanol, 1 = cyclohexane
x = np.asarray([0.0550, 0.945])
m = np.asarray([1.5255, 2.5303])
s = np.asarray([3.2300, 3.8499])
e = np.asarray([188.90, 278.11])
volAB = np.asarray([0.035176, 0.])
eAB = np.asarray([2899.5, 0.])# # print(' PC-SAFT:', calc, 'J mol^-1 K^-1')
# # print(' Relative deviation:', (calc-ref)/ref*100, '%')
# Dimethyl ether
m = np.asarray([2.2634])
s = np.asarray([3.2723])
e = np.asarray([210.29])
dpm = np.asarray([1.3])
dip_num = np.asarray([1.0])
cnsts = np.asarray([57431., 94494, 895.51, 65065, 2467.4]) # constants for Aly-Lee equation (obtained from DIPPR)
pyargs = {'m':m, 's':s, 'e':e, 'dipm':dpm, 'dip_num':dip_num}
ref = 102.2 # source: DIPPR correlation
p = 100000.
t = 240.
rho = pcsaft_den(t, p, x, pyargs, phase='liq')
calc = pcsaft_cp(t, rho, cnsts, x, pyargs)
if print_result:
print('\n########## Test with dimethyl ether ##########')
print('----- Heat capacity at 240 K -----')
print(' Reference:', ref, 'J mol^-1 K^-1')
print(' PC-SAFT:', calc, 'J mol^-1 K^-1')
print(' Relative deviation:', (calc-ref)/ref*100, '%')
assert abs((calc-ref)/ref*100) < 3print(' Relative deviation:', (dadt_eos-dadt_num)/dadt_num*100, '%')
assert abs((dadt_eos-dadt_num)/dadt_num*100) < 2e-2
# Water
m = np.asarray([1.2047])
e = np.asarray([353.95])
volAB = np.asarray([0.0451])
eAB = np.asarray([2425.67])
p = 100000.
t = 290.
s = np.asarray([2.7927 + 10.11*np.exp(-0.01775*t) - 1.417*np.exp(-0.01146*t)])
pyargs = {'m':m, 's':s, 'e':e, 'e_assoc':eAB, 'vol_a':volAB}
rho = pcsaft_den(t, p, x, pyargs, phase='liq')
dadt_eos = pcsaft_dadt(t, rho, x, pyargs)
# calculating numerical derivative
der1 = pcsaft_ares(t-1, rho, x, pyargs)
der2 = pcsaft_ares(t+1, rho, x, pyargs)
dadt_num = (der2-der1)/2.
if print_result:
print('\n########## Test with water ##########')
print(' Numerical derivative:', dadt_num)
print(' PC-SAFT derivative:', dadt_eos)
print(' Relative deviation:', (dadt_eos-dadt_num)/dadt_num*100, '%')
assert abs((dadt_eos-dadt_num)/dadt_num*100) < 2e-2
# Dimethyl ether
m = np.asarray([2.2634])
s = np.asarray([3.2723])print('----- Density at 274 K and 101325 Pa -----')
print(' Reference:', ref, 'mol m^-3')
print(' PC-SAFT:', calc, 'mol m^-3')
print(' Relative deviation:', (calc-ref)/ref*100, '%')
assert abs((calc-ref)/ref*100) < 2
# Acetic acid
m = np.asarray([1.3403])
s = np.asarray([3.8582])
e = np.asarray([211.59])
volAB = np.asarray([0.075550])
eAB = np.asarray([3044.4])
pyargs = {'m':m, 's':s, 'e':e, 'e_assoc':eAB, 'vol_a':volAB}
ref = 17240. # source: DIPPR correlation
calc = pcsaft_den(305, 101325, x, pyargs, phase='liq')
if print_result:
print('\n########## Test with acetic acid ##########')
print('----- Density at 305 K and 101325 Pa -----')
print(' Reference:', ref, 'mol m^-3')
print(' PC-SAFT:', calc, 'mol m^-3')
print(' Relative deviation:', (calc-ref)/ref*100, '%')
assert abs((calc-ref)/ref*100) < 2
# Dimethyl ether
m = np.asarray([2.2634])
s = np.asarray([3.2723])
e = np.asarray([210.29])
dpm = np.asarray([1.3])
dip_num = np.asarray([1.0])
pyargs = {'m':m, 's':s, 'e':e, 'dipm':dpm, 'dip_num':dip_num}def test_cp(print_result=False):
"""Test the heat capacity function to see if it is working correctly."""
# Benzene
x = np.asarray([1.])
m = np.asarray([2.4653])
s = np.asarray([3.6478])
e = np.asarray([287.35])
cnsts = np.asarray([55238., 173380, 764.25, 72545, 2445.7]) # constants for Aly-Lee equation (obtained from DIPPR)
pyargs = {'m':m, 's':s, 'e':e}
ref = 140.78 # source: Equation of state from Polt et al. (1992) (available at https://webbook.nist.gov/chemistry/fluid/)
p = 100000.
t = 330.
rho = pcsaft_den(t, p, x, pyargs, phase='liq')
calc = pcsaft_cp(t, rho, cnsts, x, pyargs)
if print_result:
print('\n########## Test with benzene ##########')
print('----- Heat capacity at 330 K -----')
print(' Reference:', ref, 'J mol^-1 K^-1')
print(' PC-SAFT:', calc, 'J mol^-1 K^-1')
print(' Relative deviation:', (calc-ref)/ref*100, '%')
assert abs((calc-ref)/ref*100) < 3
# Toluene
x = np.asarray([1.])
m = np.asarray([2.8149])
s = np.asarray([3.7169])
e = np.asarray([285.69])
cnsts = np.asarray([58140., 286300, 1440.6, 189800, 650.43]) # constants for Aly-Lee equation (obtained from DIPPR)
pyargs = {'m':m, 's':s, 'e':e}# Acetic acid ---------
m = np.asarray([1.3403])
s = np.asarray([3.8582])
e = np.asarray([211.59])
volAB = np.asarray([0.075550])
eAB = np.asarray([3044.4])
pyargs = {'m':m, 's':s, 'e':e, 'e_assoc':eAB, 'vol_a':volAB}
den = pcsaft_den(t, p, x, pyargs, phase='liq')
ref = -7038.004 # J mol^-1
calc = pcsaft_gres(t, den, x, pyargs)
if print_result:
print('Acetic acid, liquid:\t\t', calc, ref, (calc-ref)/ref*100, 'J/mol')
assert abs((calc-ref)/ref*100) < 1e-2
den = pcsaft_den(t, p, x, pyargs, phase='vap')
ref = -2109.459 # J mol^-1
calc = pcsaft_gres(t, den, x, pyargs)
if print_result:
print('Acetic acid, vapor:\t\t', calc, ref, (calc-ref)/ref*100, 'J/mol')
assert abs((calc-ref)/ref*100) < 1e-2print(' Reference:', ref, 'mol m^-3')
print(' PC-SAFT:', calc, 'mol m^-3')
print(' Relative deviation:', (calc-ref)/ref*100, '%')
assert abs((calc-ref)/ref*100) < 2
# Propane
x = np.asarray([1.])
m = np.asarray([2.0020])
s = np.asarray([3.6184])
e = np.asarray([208.11])
pyargs = {'m':m, 's':s, 'e':e}
t = 85.525 # K
p = 1.7551e-4 # Pa
ref = 16621.0 # source: reference EOS in CoolProp
calc = pcsaft_den(t, p, x, pyargs, phase='liq')
if print_result:
print('########## Test with propane ##########')
print('----- Density at {} K and {} Pa -----'.format(t, p))
print(' Reference:', ref, 'mol m^-3')
print(' PC-SAFT:', calc, 'mol m^-3')
print(' Relative deviation:', (calc-ref)/ref*100, '%')
assert abs((calc-ref)/ref*100) < 2
t = 85.525 # K
p = 1.39e-4 # Pa
ref = 1.9547e-7 # source: reference EOS in CoolProp
calc = pcsaft_den(t, p, x, pyargs, phase='vap')
if print_result:
print('----- Density at {} K and {} Pa -----'.format(t, p))
print(' Reference:', ref, 'mol m^-3')
print(' PC-SAFT:', calc, 'mol m^-3')pcsaft
The PC-SAFT equation of state, including dipole, association and ion terms.
