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Catalysis for Clean Diesel Power
Dr.
Aleksey Yezerets
Cummins Inc.
ABSTRACT
Despite
extensive research in the area of alternative propulsion sources for
ground transportation, such as fuel cells and hybrid electric
systems, diesel engines remain the most promising solution for
energy efficiency. This is due to their unparalleled power density
and fuel/CO2 efficiency. Recent studies indicate that
diesels represent more fuel-efficient option than gasoline-electric
hybrids, except for light vehicles in a very congested urban
driving.
Broader introduction of diesel
engines in the US has been delayed by the increasingly stringent
environmental regulations, such as 2007/2010 US EPA emissions
standards. These are associated with a number of fundamental
challenges for the respective catalytic emissions reduction systems,
due to the necessity to selectively reduce NOx in the net oxidizing
environment over a broad range of conditions, as well as poor
reactivity of diesel soot towards oxidation under typical exhaust
conditions. Furthermore, such systems need to be actively
controlled, either continuously or in a periodic manner, based on
their short-term history, long-term degradation factors, and driving
conditions. This effectively leads to a need for sophisticated,
often kinetic models-based control algorithms. Implementation of
such active systems requires detailed quantitative understanding of
their performance and degradation. It also often demands development
of nontrivial gas analysis approaches, especially for the inherently
non-steady-state, periodically operated devices.
Substantial progress in this area
has recently culminated in commercialization of several diesel
catalytic technologies; however the respective scientific and
engineering challenges rapidly evolve and expand as well, driven by
the ever tightening emissions regulations worldwide, on-board
catalyst diagnostics requirements and ambitious goals for further
fuel efficiency improvements.
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