Calibration of a model for selective catalytic reduction with ammonia, including NO oxidation, and simulation of NO_x reduction over an Fe–zeolite catalyst under highly transient conditions

Abstract

NOx reduction over an Fe–zeolite catalyst is simulated for highly transient conditions representative of automotive diesel engine operation. A transient 1D convection + 1D diffusion (1D + 1D) model for a single channel of a catalytic converter is developed, including a set of the most recently proposed kinetics for Fe–zeolite catalysts. The parameters specifying the characteristics of the selective catalytic reduction system are introduced, and an efficient calibration procedure is proposed that exploits the specific structure of the experimental dataset, consisting of a total of 90 operating conditions with varying space velocities, temperatures and inlet concentrations. Parameterization of the system is carried out by studying the system response to single step feeds in the inlet ammonia up to steady state (slow transient). Experimental data for highly dynamic ammonia dosing is subsequently employed to assess the model performance at highly transient conditions typical of diesel engine operation. Excellent agreement is reported for a total of 90 operating conditions; differences between the predictions and the experimental data in cumulative converted NOx after 20,000 s of operation are less than 2%.

Experimental and numerical assessment of impingement and mixing of urea–water sprays for nitric oxide reduction in diesel exhaust

“…e.g. [3,4], the processes leading to the availability of NH 3 at the catalyst entrance are considerably less well studied. These encompass the injection of a urea-water solution in a cross-flow configuration, as well as thermolysis and hydrolysis reactions taking place in the hot gas consequently providing the reducing agent.…”

Fluid Dynamic Comparison of AdBlue Injectors for SCR Applications

“…Attempts at modeling, simulation and optimization of SCR systems have been conducted [19,20,21,22,23,24,25,26,27]. Numerical simulations of different urea injection conigurations have been performed [19].…”

“…A model for urea-injection while taking into account interaction with exhaust tubing has also been developed [22,23]. Coupling of spray dynamics and turbulence with chemical reactions in vehicle exhaust gases has been reported too [24,25,26]. In the above cases, experimental data on aspects of SCR systems was either explicitly not available [19], limited to a few sources or had to be generated speciically for the study in question [22,23,27].…”

Experimental Fluid Dynamic Investigation of Urea–Water Sprays for Diesel Selective Catalytic Reduction–DeNOx Applications

“…Attempts at modeling, simulation, and optimization of SCR systems have been conducted. − Numerical simulations of different urea injection configurations have been performed . High speed photography and particle sizing have been employed to determine urea spray pattern parameters, which were used as input for a CFD model .…”

“…High speed photography and particle sizing have been employed to determine urea spray pattern parameters, which were used as input for a CFD model . A model for urea injection while taking into account interaction with exhaust tubing has also been developed. , Coupling of spray dynamics and turbulence with chemical reactions in vehicle exhaust gases has been reported, too. − In the above cases, experimental data on aspects of SCR systems were explicitly not available, were limited to a few sources, or had to be generated specifically for the study in question. ,, …”