DETROIT - Delphi Corp. has a new innovation that may help diesel engines comply with the strict new emissions standards that industry experts say are hampering diesel's ability to more quickly penetrate the U.S. market.
Delphi's new onboard diesel-fuel reformer, announced at the annual Society of Automotive Engineers World Congress here, combusts diesel fuel to form a “hydrogen-rich reformate.”
Delphi diesel-fuel reformer.
Injected into the diesel's exhaust stream, it regenerates the exhaust system's oxides of nitrogen (NOx) trap and particulate filter, both of which are vital to making diesel exhaust clean enough to pass new U.S. Tier II and California LEV II emissions levels.
The innovation is important because many existing NOx- and particulate-filter regeneration schemes, widely known as selective catalytic reduction, rely on injection of liquid urea into the exhaust stream. But the urea, held in a tank in the engine bay, requires a new infrastructure or other arrangement to deliver the liquid to diesel-vehicle owners.
The diesel-generated reformate also enables reduced amounts of expensive rare earth metals in the catalysts, says Jean Botti, Delphi business line executive-powertrain. Additionally, the system imparts less of a fuel-economy penalty than other regeneration strategies.
Vehicle Layout with Reformer System
Delphi says early tests with a diesel-engine light truck indicate the diesel reformer allows the vehicle to meet the critical federal Tier II, bin 5 emissions standard.
Botti says the diesel reformer requires no costly tear-ups of existing powertrain packaging. And thanks to the heat the reformate can inject to the overall exhaust temperature, the system can eliminate the need for costly heat-conserving exhaust components.
Delphi says the diesel reformer remains under development, with production-ready systems targeted for large-displacement diesel vehicles when 100% of auto makers' U.S. sales must be Tier II, bin 5-compliant in 2009.