  A detailed mechanism for the four-component RD387 gasoline surrogate
developed by Lawrence Livermore National Laboratory has shown good agreement
with experiments in engine-relevant conditions. However, with 1388 species and
5933 reversible reactions, this detailed mechanism is far too large to use in
practical engine simulations. Therefore, reduction of the detailed mechanism
was performed using a multi-stage approach consisting of the DRGEPSA method,
unimportant reaction elimination, isomer lumping, and analytic QSS reduction
based on CSP analysis. A new greedy sensitivity analysis algorithm was
developed and demonstrated to be capable of removing more species for the same
error limit compared to the conventional sensitivity analysis used in DRG-based
skeletal reduction methods. Using this new greedy algorithm, several skeletal
and reduced mechanisms were developed at varying levels of complexity and for
different target condition ranges. The final skeletal and reduced mechanisms
consisted of 213 and 148 species, respectively, for a lean-to-stoichiometric,
low-temperature HCCI-like range of conditions. For a lean-to-rich,
high-temperature, SI/CI-like range of conditions, skeletal and reduced
mechanisms were developed with 97 and 79 species, respectively. The skeletal
and reduced mechanisms in this study were produced using an error limit of 10%
and validated using homogeneous autoignition simulations over engine-relevant
conditions - all showed good agreement in predicting ignition delay.
Furthermore, extended validation was performed, including comparison of
autoignition temperature profiles, PSR temperature response curves and
extinction turning points, and laminar flame speed calculations. All the
extended validation showed results within the 10% error limit, demonstrating
the adequacy of the resulting reduced chemistry.

Chemical Physics