19 May 2006
The California Air Resources Board (ARB) has verified Johnson Matthey’s Partial Continuously Regenerating Technology (PCRT) emission control system for 1991 to 1993 model year diesel engines used in on-road applications. The PCRT system achieved a 50% reduction in particulate matter emissions, qualifying it for a Level 2 verification. The device must be operated with ultra low sulfur diesel fuel (15 ppm S).
The PCRT device utilizes a metallic “flow-through filter” substrate (by Emitec) regenerated by an upstream oxidation catalyst. Development and field trials of the PCRT system were described in the recent SAE paper #2006-01-0213.
Under the conditions of the verification, the PCRT applications must have a duty cycle with an average temperature profile greater than 240°C for 40% of the operating cycle. If exhaust temperatures are too low, the PCRT—contrary to “closed” particulate filters—will not plug, but the PM emission control efficiency will decrease.