Batch Reactor

The batch model simulates a constant volume batch reactor. The code integrates the following governing equation

\[\frac{d(\rho_k)}{dt} = \dot{s_k} M_k A_{sv} + \dot{\omega_k}M_k\]

\[\rho = \sum \rho_k\]

\[p = \frac{\rho RT}{\bar{M}}\]

Here $\rho_k$ is the mass density of species $k$ defined as $\rho Y_k$, where $Y_k$ is the mass fraction of species $k$ and $\rho$ is the density (kg/m$^3$) of the mixture. $M_k$ is the molecular weight of species $k$ (Kg/mol), $\dot{s}_k$ is the molar production rate (mol/m$^2$-s) of species $k$ due to surface reactions, $\dot{\omega}_k$ is the molar production rate (mol/m$^3$-s) of species $k$ due to gas phase reactions, and $A_{sv}$ is the surface area to volume (1/m).

Running the code

The code is invoked by using the following method.

On the Julia REPL

julia>using ReactionEngine
julia>batch("batch.xml","../lib/")

Input file

The method takes file_name as the argument. The file_name points to the input XML file. The structure of the XML input file is shown below.

?xml version="1.0" encoding="ISO-8859-1"?>
<batch>
    <gasphase>CH4 H2O H2 CO CO2 O2 N2</gasphase>
    <molefractions>CH4=0.25,H2O=0.25,N2=0.5</molefractions>
    <T>1073.15</T>
    <p>1e5</p>
    <Asv>10</Asv>
    <time>10</time>
    <surface_mech>ch4ni.xml</surface_mech>
</batch>

The meaning of different tags is specified below.

• <batch> : The root XML tag for batch
• <gasphase> : list of gas-phase species. The species names must be separated by white spaces or tab
• <molefractions> : inlet mole fraction of the gas-phase species. Instead of mole fractions, mass fractions may also be specified. In that case, the tag must be <massfractions>. You must ensure that the sum of mass or mole fractions specified is unity. There are no internal checks to ascertain this.
• <T>: operating temperature in K
• <p>: initial pressure in Pa
• <Asv> : Surface area to volume ratio (1/m)
• <time> : integration time in s
• <surface_mech> : name of the surface reaction mechanism

Output

The code generates two output files in the same directory where the input file batch.xml is present. The file gas_profile.dat contains the mole fraction of the gas phase species as a function of time. The file surf_profile.dat contains the surface coverages of adsorbed species as a function of time. In addition to these two files, the code also generates terminal output, which shows integration progress. The terminal output is nothing by the integration time.

An example terminal output is shown below.

julia> batch("test/batch/batch.xml")
0.000000e+00
5.380030e-12
7.322192e-12
1.091965e-11
1.389281e-11
..
..
..
9.889415e+00
9.983973e+00
1.000000e+01
Solver Integration: Success

A sample output of gas_profile.dat is shown below.

         t           T           p         rho         CH4         H2O          H2          CO         CO2          O2          N2
0.0000e+00  1.0732e+03  1.0000e+05  2.5240e-01  2.5000e-01  2.5000e-01  0.0000e+00  0.0000e+00  0.0000e+00  0.0000e+00  5.0000e-01
5.3800e-12  1.0732e+03  1.0000e+05  2.5240e-01  2.5000e-01  2.5000e-01  2.8224e-17  2.8064e-31  3.6828e-43  3.5083e-34  5.0000e-01
7.3222e-12  1.0732e+03  1.0000e+05  2.5241e-01  2.5000e-01  2.5000e-01  7.2345e-17  5.7521e-31  5.7355e-42  1.1037e-33  5.0000e-01
1.3893e-11  1.0732e+03  1.0000e+05  2.5241e-01  2.5000e-01  2.5000e-01  5.7775e-16  5.2239e-29  1.5426e-39  2.3067e-32  5.0000e-01
1.7496e-11  1.0732e+03  1.0000e+05  2.5241e-01  2.5000e-01  2.5000e-01  1.2389e-15  2.4341e-28  1.3782e-38  6.7062e-32  5.0000e-01
...
...
9.8894e+00  1.0732e+03  1.0205e+05  2.5241e-01  2.3492e-01  2.2984e-01  3.5247e-02  4.9651e-03  5.0865e-03  3.8647e-17  4.8994e-01
9.9840e+00  1.0732e+03  1.0206e+05  2.5241e-01  2.3483e-01  2.2971e-01  3.5461e-02  4.9881e-03  5.1229e-03  1.5330e-17  4.8988e-01
1.0000e+01  1.0732e+03  1.0207e+05  2.5241e-01  2.3481e-01  2.2969e-01  3.5498e-02  4.9920e-03  5.1290e-03  1.8337e-17  4.8987e-01

A sample output of surf_profile.dat is shown below.

         t           T        (NI)       H(NI)       O(NI)     CH4(NI)     H2O(NI)     CO2(NI)      CO(NI)      OH(NI)       C(NI)     HCO(NI)      CH(NI)     CH3(NI)     CH2(NI)
0.0000e+00  1.0732e+03  6.0000e-01  0.0000e+00  0.0000e+00  0.0000e+00  4.0000e-01  0.0000e+00  0.0000e+00  0.0000e+00  0.0000e+00  0.0000e+00  0.0000e+00  0.0000e+00  0.0000e+00
5.3800e-12  1.0732e+03  6.0842e-01  2.9832e-04  3.2879e-05  1.1712e-09  3.9101e-01  2.7168e-33  5.9257e-21  2.3256e-04  1.0792e-12  2.3196e-23  8.8535e-13  4.6995e-11  8.9031e-12
7.3222e-12  1.0732e+03  6.1140e-01  4.1988e-04  5.9207e-05  1.1838e-09  3.8782e-01  5.7960e-32  1.8386e-20  3.0147e-04  2.8680e-12  8.2649e-23  1.6840e-12  5.9925e-11  1.4892e-11
1.0920e-11  1.0732e+03  6.1683e-01  6.6111e-04  1.2488e-04  1.1946e-09  3.8197e-01  1.7656e-30  2.0089e-19  4.1135e-04  9.6114e-12  3.6587e-22  3.4522e-12  7.8856e-11  2.6942e-11
...
...
...
9.8894e+00  1.0732e+03  7.7820e-01  1.0109e-01  3.5083e-02  1.4451e-09  5.2625e-04  5.6835e-06  8.4964e-02  1.2547e-04  9.1985e-06  6.5892e-13  3.1341e-11  4.1784e-10  2.2512e-10
9.9840e+00  1.0732e+03  7.7791e-01  1.0137e-01  3.4840e-02  1.4442e-09  5.2584e-04  5.6713e-06  8.5216e-02  1.2498e-04  9.2286e-06  6.6385e-13  3.1254e-11  4.1700e-10  2.2450e-10
1.0000e+01  1.0732e+03  7.7787e-01  1.0141e-01  3.4799e-02  1.4441e-09  5.2576e-04  5.6693e-06  8.5259e-02  1.2490e-04  9.2337e-06  6.6469e-13  3.1239e-11  4.1686e-10  2.2439e-10