ERROR neqsim.thermo.phase.PhaseEos - Failed to solve for molarVolume within the iteration limit

[maksymmoroz11]

Hello!

I have similar issue that has been mentioned in #241 and #267 and I haven't components with mole fraction 0.
I have used code from example but have written my gas composition from the real task:

import neqsim
from neqsim.neqsimpython import jNeqSim
from neqsim.thermo.thermoTools import *
import matplotlib.pyplot as plt


fluid0_HC = fluid('umr')
fluid0_HC.addComponent('nitrogen',2.5)
fluid0_HC.addComponent('CO2',4.5)
fluid0_HC.addComponent('methane',79.45)
fluid0_HC.addComponent('ethane',10)
fluid0_HC.addComponent('propane',2.5)
fluid0_HC.addComponent('i-butane',0.3)
fluid0_HC.addComponent('n-butane',0.5)
fluid0_HC.addComponent('22-dim-C3',0.01)
fluid0_HC.addComponent('i-pentane',0.05)
fluid0_HC.addComponent('n-pentane',0.05)
fluid0_HC.addComponent('n-hexane',0.05)
fluid0_HC.addComponent('benzene',0.02)
fluid0_HC.addComponent('c-hexane',0.02)
fluid0_HC.addComponent('n-heptane',0.02)
fluid0_HC.addComponent('toluene',0.01)
fluid0_HC.addComponent('n-octane',0.01)
fluid0_HC.setMixingRule("HV", "UNIFAC_UMRPRU")
thermoOps = jNeqSim.thermodynamicOperations.ThermodynamicOperations(fluid0_HC)
thermoOps.calcPTphaseEnvelope()

plt.plot(list(thermoOps.getOperation().get("dewT")),list(thermoOps.getOperation().get("dewP")), label="dew point")
plt.plot(list(thermoOps.getOperation().get("bubT")),list(thermoOps.getOperation().get("bubP")), label="bubble point")
plt.title('PT envelope')
plt.xlabel('Temperature [K]')
plt.ylabel('Pressure [bar]')
plt.legend()
plt.show()

When I tried to get PT envelope with exactly code I showed above with toluene in mixture I met an eror:
[main] ERROR neqsim.thermo.phase.PhaseEos - Failed to solve for molarVolume within the iteration limit.
and get obviously wrong PT envelope:
.

But when I commented string with toluene adding, I didn't met any errors and got correct PT envelope:

I also met this error earlier with different gas composition and when I will reproduce it, I can send that code.
Could you please explain what is the root of this error and could you give limitations of gas composition NeqSim have, if they exist?

[maksymmoroz11]

Hello!

Today I again got this error when I tried to got PT envelope with gas composition given above without toluene but with 0.03 % of n-octane instead of 0.01 %:

import neqsim
from neqsim.neqsimpython import jNeqSim
from neqsim.thermo.thermoTools import *
import matplotlib.pyplot as plt

fluid0_HC = fluid('umr')
fluid0_HC.addComponent('methane', 79.45)
fluid0_HC.addComponent('ethane', 10)
fluid0_HC.addComponent('propane', 2.5)
fluid0_HC.addComponent('i-butane', 0.3)
fluid0_HC.addComponent('n-butane', 0.5)
fluid0_HC.addComponent('i-pentane', 0.05)
fluid0_HC.addComponent('n-pentane', 0.05)
fluid0_HC.addComponent('22-dim-C3', 0.01)
fluid0_HC.addComponent('benzene', 0.02)
fluid0_HC.addComponent('c-hexane', 0.02)
fluid0_HC.addComponent('n-hexane', 0.05)
fluid0_HC.addComponent('n-heptane', 0.02)
fluid0_HC.addComponent('n-octane', 0.03)
fluid0_HC.addComponent('nitrogen', 2.5)
fluid0_HC.addComponent('CO2', 4.5)
fluid0_HC.setMixingRule("HV", "UNIFAC_UMRPRU")

thermoOps = jNeqSim.thermodynamicOperations.ThermodynamicOperations(fluid0_HC)
thermoOps.calcPTphaseEnvelope()

plt.plot(list(thermoOps.getOperation().get("dewT"))[:30],list(thermoOps.getOperation().get("dewP"))[:30], label="dew point")
plt.title('PT envelope')
plt.xlabel('Temperature [K]')
plt.ylabel('Pressure [bar]')
plt.legend()
plt.show()

[EvenSol]

I will look into it.

It seems like getting the data using the following code will help:
plt.plot(list(thermoOps.getOperation().get("dewT2")),list(thermoOps.getOperation().get("dewP2")), label="dew point")
plt.plot(list(thermoOps.getOperation().get("bubT2")),list(thermoOps.getOperation().get("bubP2")), label="bubble point")

But this should be updated in a future version (so we dont have to check for data in more than one way).