Control-Oriented Modeling and Observer-Based Estimation of Solid and Gas Temperatures for a Diesel Engine Aftertreatment System

Abstract

Diesel oxidation catalysts (DOCs) and diesel particulate filters (DPFs) have become standard components in diesel engine aftertreatment systems to remove carbon monoxide (CO), unburned hydrocarbon (HC), and particulate matter (PM) emissions. Many studies have been focused on improving the performances of DOCs and DPFs, which have been found to be influenced significantly by their respective thermal behaviors. The objective of this research is to develop a control-oriented thermal model for a DOC + DPF aftertreatment system. The control-oriented model is established by considering both thermal inertia of each component and chemical reactions inside it. Engine-out, DOC-out, and DPF-out emissions have been analyzed before simplified empirical models are proposed for the prediction of cared emission species. Experimental validation results show that the control-oriented models are capable of capturing both the gas phase and the solid phase thermal dynamics of a DOC and a DPF. An observer, designed based on the control-oriented solid temperature model and exhaust gas temperature model, can estimate the DOC and DPF gas and solid temperatures accurately in comparison with the measurements. The control-oriented thermal models and observer will be beneficial in the integrated engine and aftertreatment system control.