A Combined 3D/Lumped Modeling Approach to Ammonia SCR After-treatment Systems: Application to Mixer Designs

Karlsson, Mikael; Wallin, Ulf; Fredholm, S.; Jansson, Jonas; Wahlström, Gert-Ove; Schär, Christoph; Onder, Christopher H.; Guzzella, Lino

doi:10.4271/2006-01-0469

Cited by 16 publications

(6 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Maldistribution results in a decrease in the NO x conversion efficiency and increase in the ammonia slip (Vikas et al, 2012). Karlsson et al (2006) illustrated that it is important to ensure that the ammonia profiles match the NO x profile for good NO x conversion, while evaluating the ammonia distribution of different mixer solutions. A mismatch will definitely have significant adverse effects on the SCR NO x reduction performance or lead to ammonia slip (Karlsson et al 2006).…”

Section: Introductionmentioning

confidence: 99%

“…Karlsson et al (2006) illustrated that it is important to ensure that the ammonia profiles match the NO x profile for good NO x conversion, while evaluating the ammonia distribution of different mixer solutions. A mismatch will definitely have significant adverse effects on the SCR NO x reduction performance or lead to ammonia slip (Karlsson et al 2006). Hsieh et al (2011) argued that unexpected ammonia slip can occur if the ammonia adsorption capability is not well estimated in SCR modeling.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Simulation Study of Ammonia Storage Characteristics of Selective Catalytic Reduction for Diesel Engines

Tan

Huang

et al. 2021

Environmental Engineering Science

View full text Add to dashboard Cite

Non-road machinery is very important, but non-road machinery has problems such as working under complex operating conditions. Agricultural machinery is an important type of non-road machinery, which mainly relies on diesel engines due to their high fuel efficiencies. The exhaust temperature of agricultural machinery changes drastically under different working conditions. This article aims to research on pollution control of non-road machinery. Among the exhaust after treatment technologies, selective catalytic reduction (SCR) technology is a very important method to reduce NO x. In this study, a series of tests was conducted to investigate the effects of temperature and exhaust gas mass flow on the NO x conversion and dynamic ammonia storage space distribution characteristics in simulation models. The genetic algorithm, a kind of global optimization algorithm that can avoid local optimization, was used in the parameter identification process. The simulation results showed that the ammonia storage capacity of SCR catalyst decreases as the temperature of SCR increases. With the decrease in temperature, the NH 3 desorption rate gradually decreased. An uneven distribution of ammonia storage similar to the shape of e was observed in the simulation and this kind of uneven distribution is obvious at low temperature. The effective area of the catalyst is near the inlet of the catalyst. This work presents an approach to help figure out the details in the ammonia storage process. This work provides information about the dynamic ammonia storage characteristics and guide for better SCR design.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Simulation Study of Ammonia Storage Characteristics of Selective Catalytic Reduction for Diesel Engines

Tan

Huang

et al. 2021

Environmental Engineering Science

View full text Add to dashboard Cite

show abstract

“…Vikas et al 8 carried out simulation and optimization research studies on the nozzle shape, the exhaust temperature and the exhaust flow to improve the uniformity of the inlet NH 3 , thus increasing the conversion efficiency and reducing the NH 3 slip. Karlsson et al 9 predicted the uniformity of the flow field and the uniformity of the NH 3 distribution using an SCR system model. Johansson et al 10 have constructed an SCR model by employing Simulink and explored the effects of the NO x uniformity index (UI) and the NH 3 UI on the conversion efficiency of the system by the model.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the selective catalytic reduction structure of a vehicle based on the improvement in the uniformity of the nitrogen oxides distribution

Lin

2017

Proceedings of the Institution of Mechanical Engineers, Part D:

View full text Add to dashboard Cite

As the sensor probe occupies a small proportion of the cross-sectional area of the pipe, the concentration of nitrogen oxides measured by the sensor may not reflect the average concentration of nitrogen oxides at the measured section when the uniformity of the nitrogen oxides is poor. The uniformity of the nitrogen oxides at the measured section is influenced by the structure of the selective catalytic reduction system of the vehicle, and particularly by the structure of the variable cross-section behind the catalyst. In this paper, a model of the selective catalytic reduction system is established to explore the rules for influencing the uniformity of the nitrogen oxides. The conclusion shows that the uniformity of the nitrogen oxides is influenced by five structure factors, which are as follows: the nozzle location; the structure of the mixing chamber; the exhaust velocity; the pipe-diameter ratio of the variable-cross-section structure; the distance between the measured section and the catalyst and the catalyst outlet. When the nozzle is further away from the catalyst inlet and the mixing chamber is designed as a cone-shaped guide plate, the uniformity of the nitrogen oxides is better. When the relative flow velocity is greater than 4.5–7.5 s−1, the uniformity of the nitrogen oxides is positively related to this factor; otherwise, the uniformity stays invariant. When the pipe-diameter ratio of the variable cross-section is 0.34, the uniformity of the nitrogen oxides is the best. The distance between the measured section and the catalyst outlet is logarithmically related to the uniformity of the nitrogen oxides. Based on the laws for the parameters influencing the uniformity of the nitrogen oxides, the structure of selective catalytic reduction in a vehicle can be optimized to improve the objectivity of the measurements, thereby guaranteeing the accuracy of the vehicle’s on-board diagnostic system, in which the nitrogen oxides sensor is applied.

show abstract

“…The maldistribution of the SCR inlet temperature, flow velocity and gaseous concentrations is reported to have effects on the aftertreatment system performance 2–8 by decreasing the NO x efficiency up to 20% and increasing slip of NH 3 up to 150 ppm. The uniformity index (UI) has been used to quantify and evaluate the maldistribution levels in aftertreatment systems 5,9 with values reported in the range of 0.71–0.95.…”

Section: Introductionmentioning

confidence: 99%

A study of the effects of NH₃ maldistribution on a urea-selective catalytic reduction system

Song

Naber

Johnson

2014

International Journal of Engine Research

View full text Add to dashboard Cite

The maldistribution of urea/NH3 at the selective catalytic reduction inlet and the resulting NH3/NOx ratio variation have been reported to have negative effects on the NOx conversion efficiency and NH3 slip in heavy-duty diesel applications. Maldistribution is caused by incomplete mixing and decomposition of the injected urea water solution within the exhaust flow in the aftertreatment system. How NH3 and the NH3/NOx ratio are distributed at the selective catalytic reduction inlet in an engine aftertreatment system and how the resultant maldistribution affects the system performance and the kinetics are presented in this combined experimental and modeling study. The distribution profiles of the selective catalytic reduction inlet NH3 and NH3/NOx ratio were determined through engine experiments. The NH3 maldistribution effects on the selective catalytic reduction performance and kinetics were quantified by using a multi-channel one-dimensional model that takes into consideration the NH3 maldistribution. It was determined that the NH3 maldistribution is a major factor causing the difference in catalyst performance in the engine exhaust as compared to the laboratory reactor environment, and these results explain specific differences in the model calibrations determined from the laboratory reactor and engine data. Improving the selective catalytic reduction inlet NH3 uniformity can improve the NOx conversion efficiency by up to 7% and reduce NH3 slip by 10–20 ppm. A single-channel one-dimensional selective catalytic reduction model calibrated to the engine data that accounts for the NH3 maldistribution phenomena can be applied for the development of on-board diagnostic and control strategies.

show abstract

A Combined 3D/Lumped Modeling Approach to Ammonia SCR After-treatment Systems: Application to Mixer Designs

Cited by 16 publications

References 6 publications

Simulation Study of Ammonia Storage Characteristics of Selective Catalytic Reduction for Diesel Engines

Simulation Study of Ammonia Storage Characteristics of Selective Catalytic Reduction for Diesel Engines

Optimization of the selective catalytic reduction structure of a vehicle based on the improvement in the uniformity of the nitrogen oxides distribution

A study of the effects of NH₃ maldistribution on a urea-selective catalytic reduction system

Contact Info

Product

Resources

About

A Combined 3D/Lumped Modeling Approach to Ammonia SCR After-treatment Systems: Application to Mixer Designs

Cited by 16 publications

References 6 publications

Simulation Study of Ammonia Storage Characteristics of Selective Catalytic Reduction for Diesel Engines

Simulation Study of Ammonia Storage Characteristics of Selective Catalytic Reduction for Diesel Engines

Optimization of the selective catalytic reduction structure of a vehicle based on the improvement in the uniformity of the nitrogen oxides distribution

A study of the effects of NH3 maldistribution on a urea-selective catalytic reduction system

Contact Info

Product

Resources

About

A study of the effects of NH₃ maldistribution on a urea-selective catalytic reduction system