This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Application of Automatic Meshing to Urea-Water Injection Simulation for Engine Aftertreatment
Technical Paper
2015-01-1057
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Controlling NOx emissions from vehicles is a key aspect of meeting new regulations for cars and trucks across the world. Selective Catalytic Reduction (SCR) with urea-water injection is a NOx reduction option that many engine manufacturers are adopting. The performance of urea-water spray evaporation and mixing upstream of an SCR catalyst is critical in obtaining reliable NOx reduction. Achieving this goal requires good ammonia and NOx distribution upstream of the SCR catalyst brick. Computational Fluid Dynamic (CFD) simulations of urea-water injection systems have become an important development and diagnostic tool for designers. An effective modeling approach for urea/SCR must include spray distribution, evaporation, urea kinetics, wall interactions and heat transfer. Designers are also interested in reducing mesh generation time to expedite geometry design changes and optimizing mesh size for accuracy and solution time. This paper presents the application of an automatically generated Cartesian meshing CFD approach to urea-water liquid injection systems to guide aftertreatment system design. An application of advanced CFD models with an automatic meshing and mesh refinement is presented for an application case of a large diesel engine exhaust system adapted from the Volvo D13 engine. This paper presents the impacts of two different mixer designs and two exhaust flow rates and compares those results to a system with no mixer. Results focus on the pressure drop across the mixer, the application of the automatic meshing strategy around the mixer and the effectiveness of providing an even ammonia distribution upstream of the SCR section. The urea-water spray conversion is modeled as a multi-component liquid. A modified cut-cell Cartesian method is used that eliminates the need for the computational grid to be morphed with the geometry of interest while still representing the true boundary shape. This approach allows for the use of simple orthogonal grids and completely automates the mesh generation process. The meshing approach also utilizes Adaptive Mesh Refinement (AMR) to resolve the domain near geometric features and in regions near the spray. AMR allows the use of a very fine grid in the vicinity of the spray while keeping the overall cell count relatively low. Results show that the systems with mixers substantially improve the ammonia uniformity at the inlet of the SCR albeit at the cost of a higher pressure drop. Also, the use of a thin blade mixer with some open area achieved ammonia uniformity that was marginally less than a wide blade mixer yet with a much lower pressure drop. Increased exhaust flow rate to full RPM resulted in some degradation of ammonia distribution uniformity for both mixers tested.
Recommended Content
Authors
Topic
Citation
Drennan, S., Kumar, G., Quan, S., and Wang, M., "Application of Automatic Meshing to Urea-Water Injection Simulation for Engine Aftertreatment," SAE Technical Paper 2015-01-1057, 2015, https://doi.org/10.4271/2015-01-1057.Also In
References
- Richards , K. J. , Senecal , P. K. , and Pomraning , E. CONVERGE (Version 2.2.0) Manual Convergent Science, Inc. Madison, WI 2014
- Senecal , P. , Richards , K. , Pomraning , E. , Yang , T. et al. A New Parallel Cut-Cell Cartesian CFD Code for Rapid Grid Generation Applied to In-Cylinder Diesel Engine Simulations SAE Technical Paper 2007-01-0159 2007 10.4271/2007-01-0159
- Senecal , P. K. , Pomraning , E. , Richards , K. , and Som , S. Grid Convergent Spray Models for Internal Combustion Engine CFD Simulations Proceedings of the ASME 2012 Internal Combustion Engine Division Fall Technical Conference, ICEF2012-92043 Vancouver, Canada 2012
- Senecal , P. , Pomraning , E. , Richards , K. , and Som , S. An Investigation of Grid Convergence for Spray Simulations using an LES Turbulence Model SAE Technical Paper 2013-01-1083 2013 10.4271/2013-01-1083
- Som S. , Longman , D. E. , Luo , Z. , Plomer , M. , Lu , T. , Senecal , P. K. , and Pomraning , E. Simulating Flame Lift-Off Characteristics of Diesel and Biodiesel Fuels Using Detailed Chemical-Kinetic Mechanisms and Large Eddy Simulation Turbulence Model J. Energy Resour. Technol. 134 2012
- Rhie , C. M. and Chow , W. L. Numerical Study of the Turbulent Flow Past an Airfoil with Trailing Edge Separation AIAA J. 21 1525 1532 1983
- Birkhold , F. , Meingast , U. , Wassermann , P. , and Deutschmann , O. Analysis of the Injection of Urea-Water-Solution for Automotive SCR DeNOx-Systems: Modeling of Two-Phase Flow and Spray/Wall-Interaction SAE Technical Paper 2006-01-0643 2006 10.4271/2006-01-0643
- Birkhold F. , Meingast U. , Wassermann P. and Deutschmann O. Modeling and Simulation of the Injection of Urea-Water Solution for Automotive SCR DeNOx-Systems Applied Catalysis B: Environmental 70 119 127 2007
- Abidin , Z. , Das , K. , and Roberts , C. 3D-Semi 1D Coupling for a Complete Simulation of an SCR System SAE Technical Paper 2013-01-1575 2013 10.4271/2013-01-1575
- Abu-Ramadan , E. , Saha , K. , and Li , X. Numerical Modeling of the Impingement Process of Urea-Water Solution Spray on the Heated Walls of SCR Systems SAE Technical Paper 2012-01-1301 2012 10.4271/2012-01-1301
- Abu-Ramadan , E. , Saha , K. , and Li , X. Modeling of the Injection and Decomposition Processes of Urea-Water-Solution Spray in Automotive SCR Systems SAE Technical Paper 2011-01-1317 2011 10.4271/2011-01-1317
- AdBlue Technical Leaflet, BASF 2005 http://www.nordpetroli.it/images2009/ADBLUEschedatecnica.pdf
- Kim J.Y. , Ryu S.H. , and Ha J.S. Numerical Prediction on the characteristics of spray-induced mixing and thermal decomposition of urea solution in SCR system Proc. 2004 Fall Technical Conference of the ASME Internal Combustion Engine Division Long Beach, California USA 2004
- Kuhnke Dominik Spray/Wall-interaction Modelling by Dimensionless Data Analysis Shaker Aachen 2004 Ph.D.Thesis
- http://www.oem.dinex.dk/en/system%20integration%20-%20exhaust%20-%20emission/scope%20of%20supply/mixer%20urea%20distribution
- http://volvo9700.com/sites/default/files/volvo-d13-engine-en.pdf