On the Effectiveness and Economy of Operation of ART-EGR Systems that Reduce Diesel Emissions

This manuscript describes recent design developments and extensive testing of ART-EGR systems (Aerodynamically Regenerated Traps with Exhaust Gas Recirculation). Such systems have been proven to drastically reduce the emissions of particulates (by up to 99%), NO_x (by up to 50%) and unburned volatile hydrocarbons (typically by 30-70%). Such emission reductions, however, are associated with increased fuel consumption. In this work extensive design modifications were implemented to minimize the fuel consumption penalty caused by the ART-EGR system.

All plumbing and valving gear has been redesigned to maximize the flow of regeneration air through the primary filter monolith. An expansion chamber integrated with the ART system, downstream of the primary filter, increased the flow of the regeneration air. At the exit of the expansion chamber, a secondary filter/burner retained and oxidized the soot. The secondary filter/burner is a small silicon carbide monolith, which is electrically heated. Tests conducted with computerized data acquisition and a completely automated ART-EGR system demonstrated the system's impact on the performance and fuel efficiency of the test vehicle. This work resulted in an optimized aerodynamic regeneration system that reduced main filter back pressures to levels half of those previously presented. EGR at low loads caused no significant increase in fuel consumption, however, at higher loads EGR inflicted a large loss. Tests with a larger electrically heated burner resulted in successful soot burning and main filter regeneration with a notable fuel economy penalty. Some alternate burning systems are considered.