Development of Advanced Diesel Particulate Filtration Systems

Background

The U.S. Environmental Protection Agency (EPA) regulations require that on-highway diesel vehicles have filtration systems to reduce tail-pipe soot emissions, known as particulate matter (PM). Diesel particulate filtration (DPF) systems are currently the most efficient at directly controlling PM. Argonne researchers, working with Corning, Inc., and Caterpillar, Inc., through a cooperative research and development agreement, are exploiting previously unavailable technology and research results on diesel PM filtration and regeneration processes, aiming to the technology transfer of advanced PM emission control to industry.

Argonne's Research

In operation of DPF systems, the filtration and regeneration of particulate emissions are the key processes to be controlled for high efficiency. Due to difficulties in accessing the micro-scaled structures of DPF membranes and monitoring particulate filtration and high-temperature thermal processes, however, research has been limited to macroscopic observation for the product. Therefore, this research project primarily focuses on examining PM filtration and oxidation processes at a microscopic level. Extensive experiments are being conducted under various engine operating conditions and regeneration schemes.

Recently, Argonne staff has developed a high-resolution micro-imaging system, which is capable of rapid recording and replaying of both still and video digital images. Transient behaviors of filtration and regeneration processes can be examined with this system, also including microstructures of DPF membrane materials. Three-dimensional imaging will also be capable with this system. For extensive experiments, Argonne researchers developed an optically accessible flow/thermal reactor system, where a bisected DPF membrane is placed to collect diesel PM and regenerate the soot deposits. This reactor system was integrated with remote-monitoring pressure/temperature sensors, flow meters, and actuation system.

A variety of experimental parameters are being measured from this reactor system; for instance, morphological and chemical properties of soot and ash deposits, pressure drops, soot oxidation characteristics, membrane pore structures, propagation of thermal reaction zone, and material failure due to thermal reaction.

Argonne's micro-imaging system with a flow/thermal reactor (left) and a digital image of filter pores (right).

May 2008