Effect of DPF Properties on Maximum Temperature Rise following a DTI

The particulate matter (PM) emitted by a diesel engine is collected and then combusted in a diesel particulate filter (DPF). A sudden decrease of the engine load of DPF undergoing regeneration, referred to as a drop to idle (DTI), may create a transient temperature peak much higher than under stationary feed conditions. This transient temperature rise may cause local melting or cracking of the filter. We report here the dependence of the maximum temperature following a DTI on the DPF properties and its dependence on the operating conditions.

The simulated impact of changes in DPF properties on peak regeneration temperature following a DTI is qualitatively similar to their impact under stationary operation. (1) The maximum DTI temperature and temperature gradient can be decreased by preheating the DPF before igniting the PM. (2) A decrease of the inlet gas temperature and/or a two-step regeneration can decrease the maximum DTI regeneration temperature. (3) The peak DTI regeneration temperature decreases upon an increase of either the filter wall thickness or the solid volumetric heat capacity. (4) When the DPF heat transfer is under axial heat Peclet number (Eqn. (4)) control, the peak temperature decreases upon an increase of the solid conductivity and/or a decrease of the filter aspect ratio (L/D). (5) The peak DTI temperature is a nonlinear function of the cell density. (6) The dependence of the maximum temperature gradient on the maximum regeneration temperature is not always monotonic.