Interphase Reactions Workflow: Lagrangian Multiphase

You can simulate reacting particles using the Lagrangian Multiphase Particle Reaction or Coal Combustion models. Liquid multi-component droplets are supported along with multi-component particles and coal particles.

The steps in this workflow are intended to follow on from the initial steps in the Reacting Flow General Workflow.
  1. For the Physics Continuum that represents the background phase in which the particle reactions occur (the continuous phase), select the following models—in addition to the models that are previously selected, with Auto-Select recommended models activated:
    Group Box Model
    Optional Models Lagrangian Multiphase
  2. Select any further Optional models as necessary.
    For example, if you are simulating reacting flow of solid granular particles such as powders or slurries, select the Discrete Element Model (DEM). See Discrete Element Model Reference.
  3. Define the gas or liquid components in the continuous phase.
    1. Expand the Continua > Continuum > Models > [Multi-Component Gas] node.
    2. Define the species and corresponding material properties.
  4. Add at least one Lagrangian phase. Right-click the Continuum > Models > Lagrangian Multiphase > Lagrangian Phases node and select New.
    If you are simulating only one type of reacting particle, only one Lagrangian phase is required. See Lagrangian Phases.
  5. For each Lagrangian Phase, select the following models, with Auto-Select recommended models activated:
    Group Box Model
    Particle Type
    • Material Particles
    • DEM Particles (when using DEM)
    Material
    • Multi-Component Coal: Designed specifically for simulating coal combustion.
    • Multi-Component Particle: For example, when modeling combustion or devolatilization of a multi-component solid.
    • Multi-Component Liquid: For reactions between a droplet and the surrounding fluid, with or without droplet devolatilization.
    Mass Transfer
    • When Multi-Component Particle or Multi-Component Liquid are selected, select Chemical Reactions
    • When Multi-Component Coal is selected, select Coal Combustion
    Char Oxidation (when Coal Combustion is selected)
    • First-Order Char Oxidation
    • Half-Order Char Oxidation
    • User-Defined Char Oxidation
    Raw Coal Devolitilization (when Coal Combustion is selected)
    • Two-Step Devolitilization
    • User-Defined Devolitilization
    Particle Reaction Type (when Chemical Reactions is selected) Select one or both:
    • Particle Reaction
    • Particle Devolitilization
    Particle Shape (when DEM Particles is selected) any

    (See DEM Particle Types)

    Equation of State
    • Constant Density
    • Polynomial Density
    When Auto-select recommended models is activated, the following additional phase models are included:
    • Pressure Gradient Force
    • Spherical Particles (except with DEM)
    • Energy
    • Species
    • Two-Way Coupling—when the reaction includes interaction with the continuous phase.
  6. Select any additional Lagrangian phase models that are required. See: Lagrangian Phase Models.
    For example:
    • Track File
    • Coal Fuel NOx
    • Particle Radiation
  7. Define the components in the Lagrangian phases.
    1. Expand the [Continuum] > Models > Lagrangian Multiphase > Lagrangian Phases > [Phase] > Models node.
    2. Set the components as described below.
      • For the Multi-Component Particle model:

        Right-click the Multi-Component Particle > Particle Components node and import species or select mixture components from the material database.

      • For the Multi-Component Liquid model:

        Right-click the Multi-Component Liquid > Droplet Components node and import species or select mixture components from the material database.

      • For the Multi-Component Coal model:
        The appropriate species which represent the composition of coal particles are already defined under the Multi-Component Coal > Coal Components node:
        • RawCoal
        • Char
        • Ash
        • H20
    3. If necessary, you can adjust the [Component] > Material Properties.
      For each component (other than RawCoal, Char, and Ash—which are pre-defined specifically for coal combustion), the Molecular Weight material property method is set to Elemental Composition by default. The molecular weight depends on the settings within the Elemental Composition material property node—elemental composition is vital for checking the stoichiometry for a particle reaction.
    4. For DEM particle types, select the [Particle Type] node and specify the required settings.
      For more information on particle types, see:
  8. Define the Particle Reactions.
    • For the Multi-Component Particle or Multi-Component Liquid models:
      1. Right-click the Particle Reaction > Particle Reactions or Particle Devolatilization > Particle Reactions node and select New Particle Reaction.
      2. Expand the Particle Reactions > Reaction node and define the Reactants and Products.

        For Particle Devolatiliziation, reactants can only come from the Lagrangian phase. For Particle Reactions, reactants can come from the Lagrangian phase or the background Fluid. In both cases products can come from either the Lagrangian phase or the background Fluid.

      3. Select the Reaction > Reaction Rate node and select the method that is required for calculating the reaction rate.
    • For the Multi-Component Coal model, the necessary coal combustion reactions are already defined under the [Char Oxidation] node.
  9. Set the parameters of other Lagrangian phase models as required.
    See: Lagrangian Phase Models.
  10. Collapse the Lagrangian Multiphase model node.
  11. Set the parameters of the remaining [Continuum] > Models, as required.
  12. For the continuum, define any necessary parameters for the Reference Values and Initial Conditons.
    • For combustion/devolatilization reactions, make sure that particles reach a high enough temperature to devolatilize and form combustible gaseous fuel. Either set a high initial temperature (around 800K), or temporarily raise the inlet gas temperature or the injection temperature of the coal particles.
    • Make sure that you specify the species mass fraction or species mole fraction for the initial reaction components (in the continuous phase).
  13. Define any necessary Physics Conditions and Values for the Region and Boundaries.
    See: Lagrangian Phase Boundary Conditions.
  14. If necessary, set up Injectors. The injectors allow you to define where, in what direction, and with what frequency, the Lagrangian particles enter the continuous phase.
    See: Working With Injectors.
  15. Return to the Reacting Flow General Workflow.