DDC 'consent decree' test of SCR engine a flop

Diesel Fuel News, August 5, 2002

According to U.S. DOJ and EPA officials at a diesel engine "consent decree" briefing last month (see related story above), a DDC engine fitted with a urea-SGR system for a low-NOx demonstration program ran into major problems. While the system achieved less than 1.0 grams/bhp-hr NOx on a transient test with less than 50 ppm ammonia slip, the catalyst substrate failed.

This was "possibly caused by excessive HC [hydrocarbon emission] although this is in dispute with Siemens," the SCR system provider, EPA's briefing report said. Other big problems included "plugging of the urea injector, general inability of suppliers to deliver the system and reluctance of fleets to participate" in the demonstration program, EPA said. In contrast, Mack and Volvo SCR demonstration programs are moving ahead, under their "consent decree" SCR demonstration programs, EPA said. "Mack expects two SCR-equipped refuse trucks and eight SGR highway trucks to be in service by late 2002," whil e Volvo plans a fleet demonstration of 30 vehicles equipped with both SCR and diesel particulate filters (DPFs), the EPA report said.