The main focus nowadays for the development of future vehicle
powertrain systems is the improvement in fuel efficiency alongside
the reduction of pollutant emissions and greenhouse gasses, most
notably carbon dioxide.
The automotive community is already engaged in seeking solutions
to these issues, however, the ideal solution, namely zero emission
vehicle is still regarded as being a long way from fruition for the
mass market. In the meantime steps are being taken, in terms of
engineering development, towards improved fuel efficiency and
sustainability of relatively conventionally powered vehicles.
One approach to the decarbonization of road vehicles is to
supplement existing fossil fuels with sustainable biofuels.
The present study examines the effect of a variety of
gasoline/alcohol fuel blends on the performance of spark ignition
engine vehicles and the potential of suitable "near to
market" technology, using a combination of dynamometer
measurements for a high technology downsized engine, running on a
variety of fuel blends, and a detailed vehicle simulation model.
Fuel consumption, and hence CO₂ emissions, results are presented
for the technology and fuel combinations over a number of
legislative and "real world" drive-cycles.
Vehicle simulation was also used to investigate vehicle
transient response, which is key to successful engine downsizing. A
model was developed, and is presented here, to enable the
assessment of the influence of the torque build-up of a
turbocharged engine upon vehicle performance. The successful
implementation of this model allowed results from transient engine
dynamometer testing to be translated into vehicle acceleration
times.
The outcome of this analysis provides a recommendation for
suitable fuel and technology combinations for the development of
passenger car engines, for the near- to mid-term time frame, that
deliver a significant reduction in CO₂ while maintaining
"driveability." It is shown that tank-to-wheel reductions
of up to 38% in CO₂ emissions are possible with currently available
technologies across the NEDC drive-cycle. The correct biofuel
blends with RON levels between 100 and 102 offer the majority of
the benefits and are shown to enable significant further
tank-to-wheel CO₂ reduction potential.