DETCHEM Batch Driver

This document describes the configuration directives that are available for use with the DETCHEM Batch driver.

The batch code simulates homogeneous gas-phase and heterogeneous surface reactions in a batch reactor. The user can specify his own time-dependent pressure, volume and temperature profiles. In case of missing temperature profile, isenthalpic or adiabatic analysis can be performed.

SI units are used exclusively throughout the program. Be sure to convert all values before importing data into CaRMeN. When referring to chemical species, use the correct capitalization, i.e. Ar instead of AR. Not doing so will lead to simulation errors since the species names will not be recognized.

Driver Name

This driver is available under the name detchem_batch.

Output Resources

This driver outputs three tabular data resources. The primary key in each is time.

• mole_fractions - The species mole fractions as function of time.
• mass_fractions - The species mass fractions as function of time.
• moles - The species moles as function of time.

Parameters

The following parameters are available. Note how the three parameters temperature, pressure and volume can either be defined as a top-level parameter or embedded within the initial object. However, each parameter must only appear once! In general, the parameters set in the top-level object are externally set values, while those set under the initial object are determined as a result of the simulation.

# The time to integrate to.
integration_time: 2.3 # s

# An object that defines the initial conditions of the reactor.
initial:
  # The initial temperature (for adiabatic conditions).
  # Cannot be used in conjunction with an externally set temperature.
  temperature: 429    # K
  # The initial pressure. Cannot be used in conjunction with an externally set pressure profile.
  pressure: 1e5       # Pa
  # The initial volume. Cannot be used in conjunction with an externally set volume profile.
  volume: 0.5e-3      # m3
  # The composition of the gas at t = 0.
  # The keys represent the species and the values represent the mole fraction.
  mole_fractions:
    CH4: 0.05163
    H2O: 0.053796
    # An asterisk can be used to denote the remainder to unity. It must be enclosed in quotes!
    Ar: "*"

# The pressure in the reactor. Cannot be used in conjunction with the initial.pressure setting.
# If a number is given, then this pressure is taken as a constant value throughout the whole simulation.
pressure: 0.5e5       # Pa
# If tabular data is given, then the data is used as a pressure profile.
# The $resource macro is typically used for this.
pressure:
  $resource: ./pressure_profile.csv

# The temperature in the reactor. Cannot be used in conjunction with the initial.temperature setting.
# If a number is given, then this temperature is taken as a constant value throughout the whole simulation.
temperature: 600      # K
# If tabular data is given, then the data is used as a temperature profile.
# The $resource macro is typically used for this.
temperature:
  $resource: ./temperature_profile.csv

# The volume of the reactor. Cannot be used in conjunction with the initial.volume setting.
# If a number is given, then a constant value is used.
volume: 0.5e-3        # m3
# If tabular data is given, then the data is used for the volume profile.
# The $resource macro is typically used for this.
volume:
  $resource: ./volume_profile.csv


# An object that describes the properties of the disk surface
surface:
  temperature: 1008   # K

# A complex object type describing the chemical model.
# Use the chemical-model loader to produce a resource with the correct structure,
# then access it using the $resource macro as shown here.
chemical_model:
  $resource: ./chemical_model


#
# Optional parameters follow below.
# The given values are the default values used when the parameter is omitted.
#

# The ratio of catalytically active surface area and geometrical surface area.
f_cat_geo: 1          # dimensionless

# An object describing the properties of the washcoat. Currently, only the effectiveness model
# is supported. Please file a feature request at https://gitlab.com/carmenjs/carmen/issues
# if you also need detailed washcoat models. The default is not to consider a washcoat model.
# Although the washcoat key itself is optional, the properties within the washcoat are not.
washcoat:
  thickness: 4e-5     # m  
  pore_diameter: 1e-8 # m
  tortuosity: 3       # dimensionless
  porosity: 0.6       # dimensionless
  # A list of diffusion limiting species used in the effectiveness factor model.
  diffusion_limiting_species:
    - CH4
    - H2O

# Settings pertaining to the numerical solution.
solver:
  absolute_tolerance: 1e-18
  relative_tolerance: 1e-6
  initial_integration_step_size: 1e-10
  max_integration_step_size: 10

# Settings for the solution of chemical source terms of surface reactions
chem_surf:
  initial_integration_step_size: 1e-10
  integration_time: 10.0
  max_integration_step_size: 1.0
  absolute_tolerance: 1e-20
  relative_tolerance: 1e-6