Problem 14.04 Heat Effect Upon Mixing of Methane and Dodecane at Elevated Temperature and Pressure Using SRK

1600 kg/hr of methane is mixed with 170 kg/hr of dodecane. The inlet temperature of both streams is 160 °C, and each enter at a pressure of 2 MPa. The mixing process is isobaric. What is the temperature of the combined stream? Use the SRK EOS with no binary interaction parameters.

Solution

This is a straightforward calculation. The energy of both streams is combined; and the outlet pressure is known. The calculation only requires calculating the inlet energy of both streams, adding it up, and finding the mole fractions of the outlet.

[12]:
from thermo import ChemicalConstantsPackage, SRKMIX, FlashVL, CEOSLiquid, CEOSGas
from chemicals import ws_to_zs, mixing_simple

constants, correlations = ChemicalConstantsPackage.from_IDs(['methane', 'dodecane'])
eos_kwargs = dict(Tcs=constants.Tcs, Pcs=constants.Pcs, omegas=constants.omegas)
liquid = CEOSLiquid(SRKMIX, HeatCapacityGases=correlations.HeatCapacityGases, eos_kwargs=eos_kwargs)
gas = CEOSGas(SRKMIX, HeatCapacityGases=correlations.HeatCapacityGases, eos_kwargs=eos_kwargs)
flasher = FlashVL(constants, correlations, liquid=liquid, gas=gas)

P1 = P2 = 2e6
T1 = 160+273.15

ws = [1600, 170]
zs = ws_to_zs(ws=ws, MWs=constants.MWs)

methane_H = flasher.flash(T=T1, P=P1, zs=[1, 0]).H()
dodecane_H = flasher.flash(T=T1, P=P1, zs=[0, 1]).H()
H = zs[0]*methane_H + zs[1]*dodecane_H

res = flasher.flash(P=P2, H=H, zs=zs)
print(f'The outlet temperature is {res.T-273.15:.4f} °C')
The outlet temperature is 150.2259 °C