OP-II-3

TEMPERATURE RISE DURING REGENERATION OF DIESELPARTICULATE FILTERSChen K., Martirosyan K.S. and Luss D.OP-II-1Department of Chemical and Biomolecular Engineering, University of Houston,Houston, Texas, USA, 77204, Dluss@UH.eduThe Diesel Particulate Filter (DPF) is the best existing technology for removal ofparticulate matter (PM). It is a wall-flow monolith consisting of many parallel extrudedsquare porous ceramic cells. Every second channel is plugged at alternate ends. Theexhaust gases enter the inlet channels and pass through the porous walls to adjacentoutlet channels. The PM accumulated in the inlet channels is periodically removed bycontrolled combustion. A major technological challenge in the operation of dieselparticulate filters (DPFs) is prevention of the occasional melting of the ceramic filtersduring regeneration (combustion of accumulated particulate matter). The cause ofthis melting is still an open question. Experiments and simulations indicate thatduring stationary regeneration (fixed feed conditions) the temperature rise is notsufficiently high to cause this ceramic Cordierite support melting (melting temperature~1250°C). The reaction engineering literature include many studies of the wrong-waybehavior in which a sudden decrease of the feed temperature to a packed bedreactor lead to a counter-intuitive temperature rise in the down stream section of thereactor. This led us to conjecture that the unexpected melting is due to a transienttemperature excursion caused by a rapid shift of the driving mode of a car fromnormal driving to idle during combustion of the particulate matter. To test thisconjecture we used Infra red imaging to measure the dynamic response of thespatio-temporal temperature on a planar DPF to a sudden change in the feedconditions. Both the experiments and numerical simulations revealed that the peaktransient temperature after the change in the feed conditions was higher than themaximal temperature of the moving regeneration front under either the initial or finalconditions. WE found that amplitude of the transient temperature rise depended onthe direction in which the soot combustion front moved in the reactor and to theperiod between the formation of the combustion temperature front and the rapidchange in the feed conditions.99