How to output results after combustion

[Potten]

Hello!

I am working with python 3.5 on a windows computer.

My aim is to write a code, which delivers me the results of a combustion with three different gases in the python console.

I want to get information about the mass flow (kg/s) and the composition of the resulting exhaust stream (molar proportions or mass proportions, temperature, pressure and enthalpy).

My code is so far:

import cantera as ct

# Use GRI-Mech-3.0

gas = ct.Solution('gri30.xml')

gas1 = ct.Solution('gri30.xml')

gas2 = ct.Solution('gri30.xml')

gas3 = ct.Solution('gri30.xml')

Exhaust = ct.Solution('gri30.xml')

# Use Reservoir for fuel

gas1.TPX = 300.0, ct.one_atm, 'CH4:0.9, N2:0.1'

fuel_in = ct.Reservoir(gas1)

# Use Reservoir for air

gas2.TPX = 300.0, ct.one_atm, 'O2:0.21, N2:0.77, AR:0.01'

air_in = ct.Reservoir(gas2) 

# Use Reservoir for H-Atoms for igniter, to enable the combustion reaction

gas3.TPX = 300.0, ct.one_atm, 'H:1.0'

igniter = ct.Reservoir(gas3)

# Combustion Chamber

gas.TPX = 300.0, ct.one_atm, 'N2:1.0'

combustor = ct.IdealGasReactor(gas)

combustor.volume = 10

# Use Reservoir for the resulting exhaust stream

Exhaust = ct.Reservoir(gas)

# MassFlowController to adjust the mass flows

m1 = ct.MassFlowController(fuel_in, Brennkammer, mdot=13.2)

m2 = ct.MassFlowController(air_in, Brenn:kammer, mdot=455)

m3 = ct.MassFlowController(igniter, Brennkammer, mdot=1)

# Connecting the combustion chamber with the exhaust

v = ct.Valve(Brennkammer, Abgas, K=1.0)

# the simulation only contains one reactor

sim = ct.ReactorNet([Brennkammer])

And now i want python to output the results about the properties of the exhaust stream.

In other examples it was possible to call the properties with this command:

Exhaust()

But this didn´t work.

Thank your for reading my problem!

[Bryan W. Weber]

Hi,

What other examples are you referring to, and what was the specific error code or message that you got when you tried Exhaust()?

Best,

Bryan

[Nick Curtis]

Additionally, the state of a Reservoir never changes after initialization.

Hence, the state will always be that of the gas during the call:

Exhaust = ct.Reservoir(gas)

If you want the state of the combustor's exhaust through the valve (and there does seem to be bugs in your code regarding initially naming the combustor 'combustor' and later referring to it as 'Brennkammer'), simply query the state of the combustor, as it its homogeneous, e.g.:

combustor.thermo()

or by extracting the specific quantities of interest

Nick

[Potten]

The example i am referring to is the "combustor" from the examples with this code:

"""

A combustor. Two separate stream - one pure methane and the other air, both at

300 K and 1 atm flow into an adiabatic combustor where they mix and burn.

We are interested in the steady-state burning solution. Since at 300 K no

reaction will occur between methane and air, we need to use an 'igniter' to

initiate the chemistry. A simple igniter is a pulsed flow of atomic hydrogen.

After the igniter is turned off, the system approaches the steady burning

solution.

"""

import math

import csv

import cantera as ct

# use reaction mechanism GRI-Mech 3.0

gas = ct.Solution('gri30.xml')

# create a reservoir for the fuel inlet, and set to pure methane.

gas.TPX = 300.0, ct.one_atm, 'CH4:1.0'

fuel_in = ct.Reservoir(gas)

fuel_mw = gas.mean_molecular_weight

# use predefined function Air() for the air inlet

air = ct.Solution('air.xml')

air_in = ct.Reservoir(air)

air_mw = air.mean_molecular_weight

# to ignite the fuel/air mixture, we'll introduce a pulse of radicals. The

# steady-state behavior is independent of how we do this, so we'll just use a

# stream of pure atomic hydrogen.

gas.TPX = 300.0, ct.one_atm, 'H:1.0'

igniter = ct.Reservoir(gas)

# create the combustor, and fill it in initially with N2

gas.TPX = 300.0, ct.one_atm, 'N2:1.0'

combustor = ct.IdealGasReactor(gas)

combustor.volume = 1.0

# create a reservoir for the exhaust

exhaust = ct.Reservoir(gas)

# lean combustion, phi = 0.5

equiv_ratio = 0.5

# compute fuel and air mass flow rates

factor = 0.1

air_mdot = factor * 9.52 * air_mw

fuel_mdot = factor * equiv_ratio * fuel_mw

# create and install the mass flow controllers. Controllers m1 and m2 provide

# constant mass flow rates, and m3 provides a short Gaussian pulse only to

# ignite the mixture

m1 = ct.MassFlowController(fuel_in, combustor, mdot=fuel_mdot)

# note that this connects two reactors with different reaction mechanisms and

# different numbers of species. Downstream and upstream species are matched by

# name.

m2 = ct.MassFlowController(air_in, combustor, mdot=air_mdot)

# The igniter will use a Gaussian time-dependent mass flow rate.

fwhm = 0.2

amplitude = 0.1

t0 = 1.0

igniter_mdot = lambda t: amplitude * math.exp(-(t-t0)**2 * 4 * math.log(2) / fwhm**2)

m3 = ct.MassFlowController(igniter, combustor, mdot=igniter_mdot)

# put a valve on the exhaust line to regulate the pressure

v = ct.Valve(combustor, exhaust, K=1.0)

# the simulation only contains one reactor

sim = ct.ReactorNet([combustor])

# take single steps to 6 s, writing the results to a CSV file for later

# plotting.

tfinal = 6.0

tnow = 0.0

Tprev = combustor.T

tprev = tnow

states = ct.SolutionArray(gas, extra=['t','tres'])

while tnow < tfinal:

    tnow = sim.step()

    tres = combustor.mass/v.mdot(tnow)

    Tnow = combustor.T

    if abs(Tnow - Tprev) > 1.0 or tnow-tprev > 2e-2:

        tprev = tnow

        Tprev = Tnow

        states.append(gas.state, t=tnow, tres=tres)

states.write_csv('combustor.csv', cols=('t','T','tres','X'))

I want to adapt this example to my problem. First I would like to create a combustion chamber where air, fuel and pure oxygen gets into a reactor and get burn. After this, the exhaust gas goes into a turbine, where the gas expands (high pressure turbine). After the turbine the exhaust gets into a second combustion chamber with additional fuel and oxygen and the exhaust gas goes into the low pressure turbine where it expands another time.

My aim is to plot the composition of the exhaust gas and the influence of additional oxygen in the combustion chambers for the resulting efficiency of this process.

When i try Exhaust():

    Abgas1()

TypeError: 'cantera._cantera.Reservoir' object is not callable

[Potten]

Thank you! Sorry i translated the code from german into english. "Brennkammer" means "combustion chamber", i forgot to change it into english.

[Ray Speth]

Hi,

I recently re-wrote this example to get rid of some things that I think tended to mislead users. Please see the updated version at https://cantera.org/examples/python/reactors/combustor.py.html. This may be a better basis for the problem you are trying to model.

Regards,

Ray

[Potten]

Hello. I saw your new example, but i dont understand how to output the results of the combustion in a simple way like:

print(Exhaust.report())

This dont work. In this very simple example it is possible:

import cantera as ct

gas = ct.Solution('gri30.xml')

#Gas A is air with constant enthalpy and pressure

A = ct.Quantity(gas, constant='HP')

A.TPX = 300.0, ct.one_atm, 'O2:0.21, N2:0.78, AR:0.01'

#Gas B is methane with constant enthalpy and pressure

B = ct.Quantity(gas, constant='HP')

B.TPX = 300.0, ct.one_atm, 'CH4:1'

#Gas C is oxygen with constant enthalpy and pressure

C = ct.Quantity(gas, constant='HP')

C.TPX = 300.0, ct.one_atm, 'O2:1'

M = A + B + C

M.equilibrate('TP')

#Output of the results of the exhaust gas

print(M.report())

This works. But i have to use a igniter and i want to use a combustion chamber, MassflowController and Reservoir...

Isn´t there a possibility to get me the results just in the console, without plotting them or to use excel?

Thank you very much!

[Ray Speth]

Hi,

Did you read Nick's post? He already gave you the answer.

Regards,

Ray

[Potten]

Hello, yes i have tried this.

But python gives me the the characteristics from the initial conditions of the combustion chamber:

gas.TPX = 300.0, ct.one_atm, 'N2:1.0'

combustor = ct.IdealGasReactor(gas)

combustor.volume = 10

combustor.thermo()

But i think there should be the results of the combustion. Do i have a thinking error about this?

[Nick Curtis]

import cantera as ct
gas = ct.Solution('gri30.cti')
gas.TPX = 1000, 101325, 'CH4:1.0, O2:2, N2:7.52'

reac = ct.IdealGasReactor(gas)

net = ct.ReactorNet([reac])
while reac.thermo.T < 2000:
    net.step()

print(reac.thermo.report())
>>>gri30:

       temperature         2001.48  K

          pressure          214058  Pa

           density        0.336755  kg/m^3

  mean mol. weight         26.1799  amu

                          1 kg            1 kmol

                       -----------      ------------

          enthalpy      9.2271e+05        2.416e+07     J

   internal energy      2.8707e+05        7.515e+06     J

           entropy          9850.9        2.579e+05     J/K

    Gibbs function     -1.8794e+07        -4.92e+08     J

 heat capacity c_p          1490.3        3.902e+04     J/K

 heat capacity c_v          1172.7         3.07e+04     J/K

                           X                 Y          Chem. Pot. / RT

                     -------------     ------------     ------------

                H2      0.0351107       0.00270355         -22.0827

                 H      0.0027195      0.000104702          -8.4894

                 O    0.000679828      0.000415465         -13.6308

                O2       0.084289         0.103023         -30.4935

                OH     0.00204784       0.00133034         -28.9939

               H2O       0.111414        0.0766679         -43.4514

               HO2     0.00016421       0.00020703         -40.1019

              H2O2    4.14408e-06      5.38426e-06         -54.8496

                 C    4.43048e-07      2.03264e-07          7.53443

                CH    4.63596e-06       2.3054e-06         -1.53622

               CH2    8.55893e-05      4.58576e-05         -13.5255

            CH2(S)    1.09497e-05      5.86673e-06         -12.5558

               CH3     0.00360062       0.00206779         -25.6781

               CH4     0.00955996       0.00585823         -37.8731

                CO      0.0614565        0.0657535         -36.3901

               CO2     0.00675976        0.0113635         -59.5984

               HCO    7.11854e-05      7.89032e-05         -38.5498

              CH2O     0.00100584       0.00115362         -45.2821

             CH2OH    9.52767e-06      1.12943e-05         -49.2433

              CH3O    6.99475e-06      8.29171e-06          -45.232

             CH3OH    4.25563e-05      5.20855e-05         -58.9961

               C2H    2.44261e-06      2.33532e-06         -9.90511

              C2H2     0.00111783       0.00111177         -23.9056

              C2H3    6.72616e-05      6.94862e-05         -27.0914

              C2H4     0.00134764        0.0014441          -38.199

              C2H5    2.86918e-05        3.185e-05         -42.7849

              C2H6    9.51156e-05      0.000109247         -52.7478

              HCCO    8.19721e-05      0.000128467         -35.4301

             CH2CO    0.000916381       0.00147144         -47.2138

             HCCOH    5.49974e-06      8.83097e-06         -44.5993

                 N    7.28482e-08      3.89751e-08         -8.35374

                NH    7.26305e-09      4.16549e-09         -22.1606

               NH2    1.09851e-09       6.7231e-10         -36.7093

               NH3    7.76261e-10      5.04973e-10         -52.1228

               NNH    9.23365e-09      1.02358e-08         -35.0776

                NO    3.50072e-07      4.01236e-07         -38.0037

               NO2     4.1206e-10      7.24105e-10         -53.5524

               N2O    6.51679e-08      1.09558e-07         -43.4912

               HNO    1.22198e-09      1.44762e-09          -45.189

                CN    1.14749e-09      1.14038e-09         -21.8046

               HCN    8.40918e-07      8.68083e-07         -35.2611

              H2CN    3.89026e-09      4.16571e-09         -37.4326

              HCNN    5.21435e-09      8.17257e-09         -28.5332

              HCNO    3.32003e-09      5.45626e-09         -45.4474

              HOCN    1.05831e-09      1.73927e-09         -57.0582

              HNCO    1.11704e-08      1.83578e-08         -61.1488

               NCO    6.39464e-09       1.0263e-08         -44.4023

                N2       0.677233         0.724664         -26.5756

              C3H7    8.68906e-08       1.4301e-07         -59.7416

              C3H8    2.69106e-07      4.53273e-07         -69.7248

            CH2CHO    6.16433e-06      1.01354e-05         -51.9671

            CH3CHO    5.16087e-05      8.68424e-05         -61.9413

     [   +1 minor]              0                0

[Potten]

Hello, thank you very much!

while reac.thermo.T < 2000:
    net.step()

What does exactly the "net.step()" command? Is there a loop running in the reactor until the temperature of 2000 K is reached?

Is there another possibility for this command? I want the loop to stop until the state of the cumbustion is steady-state. For example to plot me the results if the composition is constant.

Greets

[Bryan W. Weber]

Hi,

Did you look in the documentation? https://cantera.org/documentation/docs-2.4/sphinx/html/cython/zerodim.html?highlight=step#cantera.ReactorNet.step and https://cantera.org/documentation/docs-2.4/sphinx/html/cython/zerodim.html?highlight=steady%20state#cantera.ReactorNet.advance_to_steady_state should have your answers.

Best,

Bryan