Implementation of Real-Time Active Regeneration Injection Strategy in ThermaCat™ Diesel After-Treatment System 2012-28-0008

Diesel particulate filters are widely used to reduce PM emission from both legacy and new diesel engines. Many commercial DPF technologies have delivered PM reduction in excess of 90%. However, implementation of successful regeneration strategies is the key to a robust and durable system. ThermaCat™ is an active regeneration diesel after-treatment system which has implemented a novel technique of real-time filter regeneration injection strategy. This paper discusses the control logic of the injection strategy; development and implementation of the system; laboratory-based emission testing; and field durability testing conducted on the system.

The active regeneration injection strategy implemented in this system, monitors certain system parameters such as exhaust backpressure, catalyst inlet temperature, engine speed and a non-dimensional calculated value "L" in real time. An array of different "L" values at increasing exhaust backpressure and filter space velocity, called "injection matrix," accompanied with an inbuilt control algorithm is used by the system ECU to decide when and how much of diesel fuel to inject in the engine exhaust stream to initiate filter regeneration events. Laboratory testing of the system with degreened catalyst and aged catalyst was conducted to evaluate its performance from emission reduction perspective. The aging of the system was conducted for 1000 hours on roads using a diesel delivery truck over a period of 8 months. Recorded data from the field durability showed multiple events of successful filter regenerations using the control strategy.

Experimental data from engine dynamometer-based testing showed more than 95% reduction in PM. ThermaCat™ system installed on the delivery truck for 1000 hours field durability showed successful implementation of the regeneration injection strategy. Snapshots of filter regeneration events along with filter temperature and pressure profiles are provided in this paper.