## Solver: coalChemistryFoam Description

coalChemistryFoam is a Lagrangian, transient solver developed for simulating compressible, turbulent flows with a focus on coal combustion processes. It incorporates models specific to coal chemistry, such as devolatilization and char combustion. The solver takes into account the thermal processes involved in coal combustion, including the effects of radiation, which are crucial for accurate temperature predictions.

This solver uses the PIMPLE algorithm to solve the pressure-velocity coupling in the gas phase (continuous phase). The continuous fluid phase is solved using an Eulerian approach, employing the standard Navier-Stokes equations: continuity, momentum, species transport, and energy equations. The current flow field is utilized to evolve the solid particles and update their parameters. This two-way coupling is essential for accurately predicting the combustion characteristics, pollutant formation, and the overall efficiency of coal-fired systems.

The solver is capable of handling combustion and chemical reactions. It supports turbulence models, including RANS and LES.

Particle motion is solved using the Lagrangian framework, where the motion of each particle is computed by integrating Newton’s second law of motion. Forces such as gravity, drag, and lift are considered.

The primary application of the solver is in modeling gasification in fluidized beds. However, it should be noted that the second phase must be sufficiently dilute, ensuring that particle-particle interactions and the effects of the particle volume fraction on the gas phase are negligible. In practice, these considerations imply that the discrete phase must be present at a fairly low volume fraction, usually less than 10-12%.

## Solver: coalChemistryFoam Features

**Transient****Compressible****Multiphase - Lagrangian Particles**

- Species Transport
- Lagrangian Particles:
- Coal Reacting Particles

- Chemical Reactions
- Devolatilization, Surface Reaction, Evaporation and Boiling
- Combustion Modeling

- Laminar and Turbulent (RANS, LES, DES)
- Multicomponent (mixture)
- Perfect Gas Model
- Pressure-Based Solver
- Rotating Objects:
- Multiple Reference Frames (MRF)

- Passive Scalar
- Porosity Modeling
- Heat Transfer
- Heat Source
- Radiation
- Buoyancy
- Source Term (explicit/implicit)
- Transonic Flow
- PIMPLE Algorithm
- Solution Limiters:
- Velocity Damping
- Pressure Limit
- Temperature Limit

## Solver: coalChemistryFoam Application

**Energy:**

- Fluidized Bed Combustion (dilute flows)

## Solver: coalChemistryFoam Species & Reactions Solvers Comparison

Species & Reactions Solvers In this group, we have included compressible (pressure-based) solvers that can be used to simulate: **Species Transport**, **Multicomponent Gas Mixtures**, **Chemical Reactions**, **Combustion**.

**Multicomponent**

- simpleReactingParcelFoam steady-state, multiphase particle clouds
- reactingParcelFoam transient, multiphase particle clouds

**Spray**

- sprayFoam transient, liquid particles only, dedicated to fuel spray combustion
- sprayDyMFoam extension of sprayFoam with DyM

**Coal**

- simpleCoalParcelFoam steady-state, coal particles only
- coalChemistryFoam transient, coal particles only

**Gas***

- reactingFoam fluids with minor density fluctuations (caused by pressure variance), no buoyancy
- rhoReactingFoam fluids with density variations due to reactions, no buoyancy
- rhoReactingBuoyantFoam extension of rhoReactingFoam with buoyancy forces

- * All solvers in this group are transient

- DyM - Dynamic Mesh

## Solver: coalChemistryFoam Results Fields

This solver provides the following results fields:

**Primary Results Fields**- quantities produced by the solver as default outputs**Derivative Results**- quantities that can be computed based on primary results and supplementary models. They are not initially produced by the solver as default outputs.

**Primary Results Fields**

Velocity | \(U\) [\(\frac{m}{s}\)] |

Pressure | \(p\) [\(Pa\)] |

Temperature | \(T\) [\(K\)] |

Species Mass Fraction | \(Y_i\) [\(-\)] |

**Derivative Results**

Density | \(\rho\) [\(\frac{kg}{m^{3}}\)] |

Vorticity | \(\omega\) [\(\frac{1}{s}\)] |

Mach Number | \(Ma\) [\(-\)] |

Courant Number | \(Co\) [\(-\)] |

Peclet Number | \(Pe\) [\(-\)] |

Stream Function | \(\psi\) [\(\frac{m^2}{s}\)] |

Q Criterion | \(Q\) [\(-\)] |

Wall Functions (for RANS/LES turbulence) | \(y^+\) [\(-\)] |

Wall Shear Stress | \(WSS\) [\(Pa\)] |

Wall Heat Flux | \(\phi_q\) [\(W/m^2\)] |

Turbulent Fields (for RANS/LES turbulence) | \(k\) \(\epsilon\) \(\omega\) \(R\) \(L\) \(I\) \(\nu_t\) \(\alpha_t\) |

Volumetric Stream | \(\phi\) [\(\frac{m^{3}}{s}\)] |

Passive Scalar | \(scalar_i\) [\(-\)] |

Forces and Torque acting on the Boundary | \(F\) [\(N\)] \(M\) [\(-\)] |

Force Coefficients | \(C_l\) [\(-\)] \(C_d\) [\(-\)] \(C_m\) [\(-\)] |

Average, Minimum or Maximum in Volume from any Result Field | \(Avg\) \(Min\) \(Max\) |