  Reactivity Controlled Compression Ignition (RCCI) is a new advanced engine
concept that uses a dual fuel mode of operation to achieve significant
improvements in fuel economy and emissions output. The fuels that are typically
used in this mode include a low- and a high-reactivity fuel in varying
proportions to control ignition timing. As such, understanding the interaction
effects during autoignition of binary fuel blends is critical to optimizing
these RCCI engines. In this work, we measure the autoignition delays of binary
blends of dimethyl ether (C$_2$H$_6$O, DME) and methanol (CH$_4$O, MeOH) in a
rapid compression machine. In these experiments, dimethyl ether and methanol
function as the high- and low-reactivity fuels, respectively. We considered
five fuel blends at varying blending ratios (by mole), including 100% DME-0%
MeOH, 75% DME-25% MeOH, 0% DME-0% MeOH, 25% DME-75% MeOH, and 0% DME-100% MeOH.
Experiments are conducted at an engine-relevant pressure of 30 bar, for the
stoichiometric equivalence ratio. In addition, the experimental results are
compared with simulations using a chemical kinetic model for DME/MeOH
combustion generated by merging independent, well-validated models for DME and
MeOH.
