<div class="section abstract"><div class="htmlview paragraph">Surrogate fuels that reproduce the characteristics of full-boiling range fuels
are key tools to enable numerical simulations of fuel-related processes and
ensure reproducibility of experiments by eliminating batch-to-batch variability.
Within the PACE initiative, a surrogate fuel for regular-grade E10 (10%vol
ethanol) gasoline representative of a U.S. market gasoline, termed PACE-20, was
developed and adopted as baseline fuel for the consortium. Although extensive
testing demonstrated that PACE-20 replicates the properties and combustion
behavior of the full-boiling range gasoline, several concerns arose regarding
the purity level required for the species that compose PACE-20. This is
particularly important for cyclo-pentane, since commercial-grade cyclo-pentane
typically shows 60%<b>–</b>85% purity. In the present work, the effects of
the purity level of cyclo-pentane on the properties and combustion
characteristics of PACE-20 were studied. Chemical kinetic simulations were
performed to predict the effects of cyclo-pentane impurities on the properties,
octane rating, and autoignition reactivity under homogeneous charge
compression-ignition conditions of PACE-20. From the numerical results,
cyclo-pentane with 85% purity or higher is required to reasonably match both the
research octane number and motor octane number of the target gasoline. Finally,
homogeneous charge compression-ignition engine simulations show that impurities
have only a modest effect on reactivity at naturally aspirated conditions, but
cyclo-pentane purity is critical to properly replicate the pressure dependency
of the reactivity.</div></div>