Heavy-Duty Truck Engine Emissions Research

Modern diesel trucks no longer produce visible smoke, but diesel exhaust continues to come under heavy scrutiny for producing nitrogen oxides (NOx) and particulate matter (PM). NOx contributes to the formation of atmospheric ozone, and particulate matter, very small (nanometer-sized) carbon-based particles, is believed to be a health hazard. A trade-off exists between these two exhaust emission in which reducing PM increases NOx and vice versa. Argonne engineers have found and patented a way to reduce both NOx and PM simultaneously with late-cycle air/oxygen-enriched air injection technology. As a result of this invention, Argonne and Caterpillar Inc., established a CRADA program to explore new technologies for reducing diesel engine exhaust emissions.

KIVA Model	Results of Late-Cycle Air Injection

The program with Caterpillar began in 1998 by using a two-phase approach for reducing the engine exhaust emissions with late-cycle air/oxygen enriched air injection. In Phase I, the concept was studied with the help of a computational fluid dynamics (CFD) model, KIVA-3. Phase II involves verifying the modeling results experimentally. To do this, a single-cylinder version of Caterpillar's popular on-highway truck engine (model 3406E) has been installed at Argonne's Powertrain and Emissions Research Laboratory.

Caterpillar Engine

Results

The KIVA-3 studies show that when late-cycle air injection characteristics are optimized, the technology can reduce PM emissions by 70% while simultaneously reducing NOx emissions by 40%. This reduction was achieved without sacrificing overall engine efficiency. Experimental verification of these findings on the single-cylinder Caterpillar research engine is currently under way.

Future Plans

Verification of the KIVA model will lead to more in-depth study of optimizing the air injection system and devising, innovative ways to physically introduce the air into the engine's combustion chamber. The KIVA model and the experimental facility will continue to be used to provide further insight into the mechanisms controlling this modified combustion process.