Title: 1D thermo-fluid dynamic modelling of de-NO_x SCR systems for diesel engine exhaust gas after-treatment

Authors: G. Montenegro, A. Onorati

Addresses: Dipartimento di Energetica, Politecnico di Milano, Via La Masa 34, 20158 Milano, Italy. ' Dipartimento di Energetica, Politecnico di Milano, Via La Masa 34, 20158 Milano, Italy

Abstract: A 1D thermo-fluid dynamic computational model has been developed to simulate the unsteady reacting flows inside the SCR (Selective Catalytic Reduction) after-treatment systems of diesel engines. The standard SCR reaction, extended with a detailed NH₃ adsorption and desorption mechanisms, and two reactions of urea decomposition, namely the thermolysis and hydrolysis, have been taken into account. Calculations under steady-state conditions have been carried out to validate the urea decomposition model, showing a good correlation with the experimental results available in the literature. The adsorption/desorption model has been validated as well, using different catalysts available on the market and comparing the results with experimental measurements. Furthermore, a diesel engine configuration has been considered to test the SCR model under different operating conditions, to point out the effects of flow unsteadiness over the de-NO_x efficiency and also the risk of ammonia slip at the outlet of the SCR device.

Keywords: 1D unsteady flows; reacting flows; selective catalytic reduction; thermo-fluid dynamic modelling; diesel engines; exhaust gas after-treatment; vehicle emissions; CFD; computational fluid dynamics.

DOI: 10.1504/IJVD.2006.009672

International Journal of Vehicle Design, 2006 Vol.41 No.1/2/3/4, pp.285 - 306

Published online: 04 May 2006 *

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