Performance and Regeneration Characteristics of a Cellular Ceramic Diesel Particulate Trap

Fundamental aspects of performance and regeneration of a porous ceramic particulate trap are described. Dimensionless correlations are given for pressure drop vs. flow conditions for clean and loaded traps. An empirical relationship between estimated particulate deposits and a loading parameter that distinguishes pressure drop changes due to flow variations from particulate accumulation is presented. Results indicate that trapping efficiencies exceed 90% under most conditions and pressure drop doubles when particulate accumulation occupies only 5% of the available void volume. Regeneration was achieved primarily by throttling the engine intake air. For various combinations of initial loading level, trap inlet temperature and oxygen concentration, it was found that regeneration rate peaked after 45 seconds from initiation. In most cases, two phases of regeneration were identified: a rapid phase lasting about 90 seconds followed by a slow reaction phase of approximately half an hour during which the residual deposits are incinerated. A regeneration map showing contours of constant regeneration rate is described. Regeneration paths on this map illustrate regions of slow, rapid, and destructive regenerations.