제어를 위한 Lean NOxTrap의 흡장 및 환원 모델링

Abstract

A control oriented model of the Lean NOx trap (LNT) was developed to determine the timing of NOx regeneration. The LNT model consists of NOx storage and reduction model. Once NOx is stored (NOx storage model), at the right timing NOx should be released and then reduced (NOx reduction model) with reductants on the catalyst active sites, called regeneration. The NOx storage model simulates the degree of stored NOx in the LNT. It is structured by an instantaneous NOx storage efficiency and the NOx storage capacity model. The NOx storge capacity model was modeled to have a Gaussian distribution with a function of exhaust gas temperature. NOx release and reduction reactions for the NOx reduction model were modeled as Arrhenius equations. The parameter identification was optimally performed by the data of the bench flow reactor test results at space velocity 50,000/hr, 80,000/hr, and temperature of 250 - 500°C. The LNT model state, storage fraction indicates the degree of stored NO x in the LNT and thus, the timing of the regeneration can be determined based on it. For practical purpose, this model will be verified more completely by engine test data which simulate the NEDC transient mode.