Experimental and Modeling Study of NO and NO2 Storage and Release Characteristics of a Diesel-Cold Start Catalyst

A 2013 6.7L Cummins ISB (209 kW) diesel engine was used to quantify the NO, NO2, and NOx storage and release performance of the diesel cold start catalyst (dCSC (TM)). The NOx storage experiments were performed over a range of temperatures from 80 to 250 degrees C and NOx release experiments were performed at temperatures from 200 to 450 degrees C. A 2-D diesel cold start catalyst (d-CSC) model was developed to predict NO, NO2 storage, and release characteristics along with the temperature distribution within diesel cold start catalyst (d-CSC) and the pressure drop across the d-CSC. This d-CSC model was calibrated using eight runs of experimental data that consisted of storage temperatures ranging from 80 to 250 degrees C and release temperatures ranging from 200 to 450 degrees C. The validation results show that the new d-CSC model can predict 200-s NOx storage and total NOx release capacity with a maximum root mean square (RMS) error of 0.02 and 0.10 NO2 g/L of substrate, respectively. The NO2/NOx ratio RMS error was within 24%. The RMS temperature errors for storage and release phases were within 3 degrees C and the pressure drop model error was within 0.2 kPa. It is found that the dCSC (TM) shows significant low temperature NOx storage capability with a peak storage occurring from 125 to 150 degrees C. The rapid NOx release was observed at temperatures above 200 degrees C which is well within the operating range of the aftertreatment system after cold start period.