Cantera/Reaction Rate Source Terms
From charlesreid1
Notes
- Reaction rates are a functon of TPX, thermodynamic state of gas
- phase object wraps an equation of state and wraps kinetic object
- use phase to obtain reaction rates
- Definition of reaction rate
- for a component: sum over each reaction rate
- Cantera phase object - calls
- production rate for component i
- production rate for reaction j
- production rate for ij
- species production rate for component i
- species production rate for reaction j
- species production rate for ij
Definition of Rates
Species Production Rate
In a differential, perfectly uniform control volume in which a chemical reaction is the only phenomena occurring, the species rate of production (species i) can be defined as the change in moles of i with time:
$ \frac{d c_i}{dt} = R_i \qquad i = 1 \dots N_{sp} $
where:
- $ c_i $ is molar volume (units of $ \frac{\text{mol}}{\text{m}^3} $)
- $ R_i $ is the volume-specific species rate of production (units of $ \frac{\text{mol}}{\text{m}^3 \text{s}} $)
Reaction Production Rate
A species production rate can be further broken up into its contributions from each reaction. These rates of production are stoichiometric and known as the reaction rates of production:
$ R_i = \sum_{j=1}^{N_{rxns}} \nu_{ij} \mathfrak{R}_j $
where:
- $ \nu_{ij} $ - stoichiometric coeff of species i in rxn j
- $ \mathfrak{R}_j $ - volume-specific stoichiometric reaction rate for reaction j
Phases
Gas Only: Volumetric Reaction Rates
Volumetric reaction rate is: (volume) x (rate of production per unit volume)
Rate of production per unit volume is: (stoichiometric coefficient) x (rate of production of reaction)
Gas and Surface: Surface Reaction Rates
Surface reaction rates are: (area) x (rate of production per unit area)
Rate of production per area is: (mass cat) x (surface area per mass cat) x (surface density of active sites) x (fractional coverage of surface species) x (rate of production of surface reaction)