The Transient Storage and Blow-Out of Diesel Particulate In Practical Exhaust Systems

Previous work on the transient storage of particulate in diesel exhaust systems (SAE 2000-01-0508) was carried out mainly at conditions where storage in the exhaust would dominate the process. The test involved a preconditioning of the engine the previous day with about 4 hours of engine idling. This ensured that the exhaust had a significant level of deposits. The following day low power cold starts were investigated and the movement of particulate between the two silencer boxes was determined as well as the net blow out of deposited particulate. Continuing deposition if particulate was also shown even in the presence of net blow out.

The present work extends this previous work to higher power blow out conditions. Also investigated was the preconditioning of the engine at high power the previous day so that the exhaust was in a much cleaner condition. The previous tests were then repeated. This showed that deposition in the exhaust pipe was greater, but that blow out of particles still occurred at high power conditions. It took typically 30 minutes before the deposition and release of particles in the exhaust stopped occurring. This coincided with the exhaust reaching an equilibrium temperature after the cold start.

The work was carried out using four simultaneous constant temperature exhaust particulate sampling systems.