The use of carbon-neutral fuels instead of conventional fuels in gasoline direct
injection (GDI) engines is beneficial to global decarbonization. However, the
application of renewable non-petroleum fuels in GDI engines is still unclear due
to their different physicochemical properties. Acetone-Butanol-Ethanol (ABE) is
a promising low-carbon alternative fuel for GDI engines, but its high viscosity
and latent heat cause pool firing during cold start. The existing flash boiling
technology can solve this problem. This study explores the effects of flash
boiling on spray characteristics, flame propagation, soot, and emissions of
gasoline-ABE blend in a constant volume combustion chamber (CVCC) without
airflow. Optical windows, high-speed camera recording, in-chamber pressure
measurement, Fourier transform infrared spectroscopy (FTIR), and transmission
electron microscope (TEM) were used to analyze flame spreading, combustion
characteristics, exhaust gases, and soot morphology. Flash boiling was performed
at a superheat index of 0.3 and compared with the subcooled spray at 30°C. The
results show that the flash boiling injection of ABE blends can effectively
solve the problem of cold start. The peak heat release rate and peak pressure of
gasoline-ABE mixtures during combustion are improved under flash boiling
conditions, which shortens the ignition delay period and makes the flame front
more concentrated and uniform, thus improving the flame stability. Additionally,
flash boiling atomization can significantly reduce the emissions of aldehydes,
hydrocarbons (HC), nitrogen oxides (NOx) and polycyclic aromatic hydrocarbons
(PAHs). Compared with gasoline, ABE has a better inhibitory effect on HC and
PAHs. Additionally, the formation of PAHs can be greatly reduced by optimizing
the fuel-air mixture. The reduction of PAHs leads to the decrease of soot
aggregates and primary particles. In conclusion, our study highlights the
potential of flash boiling to reduce harmful emissions, making ABE a more viable
alternative to gasoline.