DDC: EGR+DPF+SCR=Bin3

Diesel Fuel News, Sept 2, 2003 by Jack Peckham

Newport, R.I. -- Detroit Diesel Corp. (DDC) has gotten inside U.S. EPA Tier 2/Bin 3 emissions limits with a light-truck diesel engine employing exhaust gas recirculation (EGR), urea-selective catalytic reduction (SCR) and a diesel particulate filter (DPF).

This scheme--being tested on a Dodge Dakota light truck--still faces a "cost issue," as DDC engineer Brian Bolton told Diesel Engine Emissions Reduction (DEER) conference here.

"Last year, we were at Bin 6" EPA Tier 2 emissions levels, "But this year we've reduced engine-out NOx through cold-start [control scheme] and multi-mode combustion--we're now very close to Bin 9 engine-out," he said.

"With urea-SCR, we got inside Tier 2/Bin 3 on NOx with 40% better fuel economy compared to the gasoline engine, and no ammonia slip," he said. DDC believes it could get 50% better fuel economy than the comparable gasoline engine by adjusting its control scheme for slightly higher Bin 5 emissions, he added.

In separate tests on a DaimlerChrysler "Neon" small car, the latest diesel engine could achieve Bin 8/Tier 2 without any NOx aftertreatment, although the car requires a DPF. Adding SCR to this car allows Bin 3 compliance even with the low exhaust temperatures typical of small passenger cars like Neon, he said. Bonus: This diesel Neon achieved between 63-67 miles per gallon.

But even with these huge fuel economy gains, most U.S. car buyers aren't so impressed by diesels. Issue: The initial price premium. "The incentive to the buyer is missing, so cost reduction is where we're focused," he said.

While no urea infrastructure exists in North America, "we'd like to follow on the heels of heavy-duty urea infrastructure development" as is proposed by DaimlerChrysler for the U.S. market (see Diesel Fuel News 8/18/03, pl).