In
the effort to mitigate the depletion of fossil fuels and climate
change, biodiesels are considered to be one of the most suitable substitutes
for petro-diesel in compression ignition engine applications. As a
follow up to prior modeling studies for gasoline and jet surrogate
fuel components (Zhang, X.; Mani Sarathy, S. Fuel, 2021, 286, 119361), this work proposes
a lumped kinetic model for both saturated and unsaturated C5–C19 fatty acid methyl esters (FAMEs) based on
the same methodology. The present lumped model includes 52 FAME fuel
components, covering a wide range of biodiesel surrogate fuel components,
as well as components typically found in biodiesels. This methodology
decouples the combustion of FAME fuels into two stages: the pyrolysis
of fuel molecules and the oxidation of pyrolysis intermediates. Lumped
reaction steps are used to describe the (oxidative) pyrolysis of each
fuel molecule, while a detailed model (Aramcomech 2.0) is adopted
as the base mechanism to describe the subsequent conversion of these
key intermediates. Rate rules adopted for all the FAME fuels are consistent.
The present lumped model is validated against experimental data from
20 pure FAMEs and six diesel/biodiesel surrogates, including around
130 sets of validation data. In general, the present lumped model
satisfactorily captures most of these validation targets. This lumped
model performs comparably with the detailed models developed in the
literature under combustion conditions. Combined with the lumped model
for 50 hydrocarbon fuels developed in previous work by this group,
the lumped kinetic model for FAME fuels developed here can be used
to predict the pyrolysis and combustion chemistry of diesel/biodiesel
surrogates in CFD simulations after necessary model reduction for
the base model. Also, the stoichiometric parameters of the lumped
reactions for various pure FAMEs can be used as the database for data
science study in FGMech development for real biodiesels.