Search Results

Recent emission and field data from diesel particulate trap buses operating at the New York City Transit Authority (NYCTA) are summarized. As part of the NYCTA Trap Oxidizer Program, transient emission and performance test data were measured from a prototype diesel particulate trap system, which utilizes a Webasto in-line full flow diesel burner to periodically regenerate the ceramic monolith filter. In addition, the progress made during a large scale field test program of 398 new TMC RTS buses powered with Detroit Diesel Corporation (DDC) 6V-92TA bus engines equipped with Donaldson Company, Inc. (DCI) Dual Wallflow Monolith Electric Regeneration Trap System is presented. Discussion includes: trap system hardware and software issues, resulting trap system improvements, impact of the trap system on engine emissions and fuel economy, and potential trap monolith durability issues.

Particulate control technology for heavy-duty diesel engines is of increasing interest. This paper describes a fully automatic, in-line full-flow Burner Diesel Particulate Filter System developed by Kloeckner-Humboldt-Deutz AG (KHD). The system was fully optimized in a transient test cell by ORTECH International for the Detroit Diesel 2-stroke 6V-92TA engine. The important parameters such as the fuel coefficients and exhaust backpressure coefficients were developed in the test cell. Transient emissions tests were conducted showing approximately 85% particulate trapping efficiency. The trap operated fully automatically. Regeneration was triggered when the exhaust backpressure had exceeded a predetermined level for a cumulative period of 3 minutes. The regeneration process on average took approximately 7-½ minutes to complete. The frequency of regeneration was approximately once every 4 hours.

Progress is reported on a project sponsored by the California Air Resources Board (ARB) to evaluate the potential of diesel particulate trap systems for retrofit application to reduce emissions from buses and trucks. A trap system was selected for evaluation based on availability of commercial prototypes at the time of the project. Engine dynamometer testing of this trap system is reported over advanced design bus cycles. The results showed that the system is viable for application to a bus equipped with a Detroit Diesel Corporation 6V-92TA diesel engine, producing satisfactory exhaust backpressure and emission characteristics over a 500 hour test period. Field testing of this system on a transit coach is now ongoing at Southern California Rapid Transit District (SCRTD) and the experience is reported. Emission testing has been conducted regularly at ARB to verify the performance of the trap system.

A diesel particulate trap system using two (2) monolithic ceramic filters and a diesel burner was designed for the 6V-92TA 2-stroke bus engine. The system comprises an electronic controller which controls four (4) valves to direct exhaust flow and burner heat flow. The exhaust passes through one filter, while trapped particulate is being regenerated in the other. The burner control sequence was optimized to avoid overheating of the system components and thermal shock of the traps. The system was tested for 100 hours in a test cell, using the New York Bus Cycle. Engine backpressure showed no noticeable increases from the baseline. The need to reduce particulate emissions from transit coach engines in the U.S.A. is driven by two forces.