Future vehicles will increasingly be required to improve their
efficiency, reduce both regulated and CO₂ emissions, and maintain
acceptable levels of driving, safety, and noise performance. To
achieve this high level of performance, they will be configured
with more advanced hardware, sensors, and control technologies that
will also enable their operation on a broader range of fuel
properties. These capabilities offer the potential to design future
vehicles to operate on the most widely available and GHG-reducing
fuels.
In previous studies, fuel flexibility has been demonstrated on a
compression ignition bench engine and vehicle equipped with an
advanced engine management system, closed-loop combustion control,
and air-path control strategies. An unresolved question is whether
engines of this sort can operate routinely on market gasoline while
achieving diesel-like efficiency and acceptable emissions and noise
levels.
This paper describes initial engineering and experimental steps
to assess this potential. Using an advanced diesel bench engine
having a higher compression ratio, optimized valve timing, and
flexible fuel injection, the engine could be operated on a European
market gasoline over full to medium part loads. The combustion was
found to be highly sensitive to EGR rates, however, and the
simultaneous optimization of all regulated emissions and combustion
noise was a considerable challenge. An advanced glow plug was
tested to improve low load performance but did not extend the
engine operating range as much as expected.