When you are solving a reacting flow using the finite-rate or eddy dissipation model, you will need to define the standard state enthalpy (also known as the formation enthalpy or heat of formation), for each species . These inputs are used to define the mixture enthalpy as
where is the reference temperature at which is defined. Standard state enthalpies are input in units of J/kg mol in SI units or in units of Btu/lb mol in British units.
For each species involved in the reaction (i.e., each fluid material contained in the mixture material), you can set the Standard State Enthalpy and Reference Temperature in the Materials panel.