MATHEMATICAL-MODELING OF ELECTRICALLY HEATED MONOLITH CONVERTERS - ANALYSIS OF DESIGN ASPECTS AND HEATING STRATEGY

The design aspects and heating strategy of an electrically heated conv erter have been analyzed using the transient monolith model developed and verified in our previous studies. The results of model calculation s presented here quantify the beneficial effects on cold-start emissio n performance of increasing the power level and heating time, decreasi ng the volume of the resistively heated element, and preheating the co nverter prior to engine start. It is also shown that a feedback contro ller based on converter-bed temperature measurements provides a conven ient means of modulating power supply during actual operation of elect rically heated converters. Just as in conventional unheated monolith c onverters, catalyst deactivation is predicted to cause significant det erioration of heated converter performance; increasing the maximum pow er level for the controller appears to be an effective way of compensa ting for performance deterioration due to catalyst deactivation.