Environmental Engineering Reference
In-Depth Information
Chapter 4
Enabling Simultaneous Reductions in Fuel
Consumption, NO
x
, and CO
2
via Modeling
and Control of Residual-Affected Low
Temperature Combustion
Greg Shaver
Abstract There are currently 200 million vehicles on the road in the United
States alone, resulting in the consumption of 600 billion liters of fuel each year.
With annual growth rates of vehicle sales and miles driven at 0.8 and 0.5%,
respectively, our domestic challenges are no less than two-fold: increasing
dependence on foreign sources of transportation fuel [1] and the release of
significant amounts of greenhouse and smog-generating chemicals, including
CO
2
and NO
x
[2]. There is a solution - by integrating advanced internal
combustion engines (ICEs) on hybrid powertrains there is a wonderful oppor-
tunity to realize a 50% reduction in fuel consumption by 2020 (Heywood et al.
2003). A significant step to meeting this goal will be the implementation and
coordinated control of a number of exciting, evolving engine technologies:
direct, multi-point fuel injection; flexible intake and exhaust valve actuation
(i.e., variable valve actuation (VVA)); real-time, production-viable in-cylinder
sensing/estimation; cooled exhaust gas recirculation (EGR), and dual-stage
variable geometry turbocharging. Exploring the most capable and cost-
effective mix of these technologies is a key challenge in the ongoing effort to
deliver the most effective engines to end-users (both individuals and industry).
One particularly promising approach leveraging these advances, residual-affected
low temperature combustion (LTC), exhibits a substantial increase in efficiency by
10-15% compared to spark-ignition (SI), and has NO
x
and soot levels that are
dramatically lower than either diesel or SI. However, to date LTC has been difficult
to practically implement because it has no specific initiator of combustion and is
subject to cyclic coupling through the temperature of reinducted or trapped
combustion gases. This chapter details the merits and history of residual-affected
LTC, and the approaches being pursued in academia and industry to meet the
aforementioned hurdles to practical on-road implementation.
