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.