The characteristics of ammonia storage and the development of model-based control for diesel engine urea-SCR system

This paper investigates the characteristics of ammonia storage in actual SCR catalyst, which indicates that space velocities (SV), the exhaust temperature and NH3:NOx ratio (NSR) have different impacts on the saturated ammonia storage and saturated time. Thus, this paper proposes an embeddable SCR model consisting of a nonlinear ammonia storage model (NAS model) and a multiple variable resistancecapacitance model with time-delay (MVRC model), in order to quantify the ammonia storage and system-out NOx concentration. After that, a model-based ammonia storage control strategy was developed to strike a better balance between high NOx reduction efficiency and low ammonia slip. (C) 2015 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.