This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Experimental Study of SCR in a Light-Duty Diesel Exhaust to Provide Data for Validation of a CFD Model Using the Porous Medium Approach
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 12, 2010 by SAE International in United States
Annotation ability available
Removal of NOx from a light-duty diesel automotive exhaust system can be achieved by SCR reactions using aqueous urea spray as the reductant. Measurements of emissions from such a system are necessary to provide data for CFD model validation. A test exhaust system was designed that featured an expansion can, nozzle and diffuser arrangement to give a controlled flow profile to define an inlet boundary for a CFD model and to approximate to one-dimensional flow. Experiments were carried out on the test exhaust using injection of either ammonia gas in nitrogen or aqueous urea spray. Measurements were made of NO, NO₂ and NH₃ at inlet to and exit from the SCR using a CLD analyzer. The NO and NO₂ profiles within the bricks were found by measuring at the exit from different length bricks. The spray and gas measurements were compared, and insights into the behavior of the droplets upstream and within the bricks were obtained. Approximately half to three-quarters of the droplets from the spray remained as droplets at entry to the first brick. Approximately 200 ppm of ammonia was released from the droplets to react in the first SCR brick. Between 10 and 100 ppm of potential ammonia passed through the first brick as droplets under conditions ranging from NOx-matched spray input to excess spray. The CFD model for the gas cases gave reasonable predictions for long bricks. For short bricks, the space velocity was high and there was breakthrough of all species. Nevertheless, the reaction kinetics used, based on a scheme published in the open literature, were shown to have some ability to describe the species profiles within the bricks.
CitationTamaldin, N., Roberts, C., and Benjamin, S., "Experimental Study of SCR in a Light-Duty Diesel Exhaust to Provide Data for Validation of a CFD Model Using the Porous Medium Approach," SAE Technical Paper 2010-01-1177, 2010, https://doi.org/10.4271/2010-01-1177.
- Lambert, C., Hammerle, R., McGill, R., Khair, M. et al., “Technical Advantages of Urea SCR for Light Duty and Heavy Duty Diesel Vehicle Applications,” SAE Technical Paper 2004-01-1292, 2004.
- Thompson, J., Op De Beeck, J., Joubert, E., and Wilhelm, T. “Case Studies of Urea SCR Integration on Passenger Cars; Monitoring of Urea Inside the Tank During Hot and Cold Environment Test Missions,” SAE Technical Paper 2008-01-1181, 2008.
- Tennison, P., Lambert, C., and Levin, M. “NOx Control Development with Urea SCR on a Diesel Passenger Car,” SAE Technical Paper 2004-01-1291, 2004.
- Koebel, M., Elsener, M., Madia, G. “Reaction pathways in the selective catalytic reduction process with NO and NO2 at low temperature,” Ind. Eng. Chem. Res. 40: 52-59, 2001
- Benjamin, S.F., Roberts, C.A. “Three-dimensional modelling of NOx and particulate traps using CFD: A porous medium approach,” Appl. Math. Modelling 31: 2446-2460, 2007
- Olsson, L., Sjovall, H., Blint, R.J. “A kinetic model for ammonia selective catalytic reduction over Cu-ZSM-5.,” Applied Catalysis B: Environmental 81: 203-217, 2008
- Takada, K., Kusaka, J., Daisho, Y. “Empirical and numerical study of the improvements in NOx reduction by a urea-SCR system attainable by controlling the relative proportions of NO and NO2,” Review of Automotive Engineering, JSAE Technical paper 4-28-1-41, 2007
- Narayanaswamy, K., and He, Y. “Modelling of Copper-Zeolite and Iron-Zeolite Selective Catalytic Reduction (SCR) Catalysts at Steady State and Transient Conditions,” SAE Technical Paper 2008-01-0615, 2008.
- Schmeig, S.J. and Lee, J.-H., “Evaluation of Supplier Catalyst Formulations for the Selective Catalytic Reduction of NOx with Ammonia,” SAE Technical Paper 2005-01-3881, 2005.
- Devadas, M., Krocher, O., Elsener, M., et al. “Influence of NO2 on the SCR of NO with ammonia over Fe-ZSM5,” Applied Catalysis B:Environmental 67: 187-196, 2006
- Benjamin, S.F., Clarkson, R.J., Haimad, N., and Girgis, N.S. “An Experimental and Predictive Study of Flow in Axisymmetric Automotive Exhaust Catalyst Systems,” SAE Technical Paper 961208, SAE Trans. J. Fuels & Lubricants 105: 1008-1019, 1996
- Shah, S.D., Mauti, A., Richert, J.F.O., Loos, M.J. et al., “Measuring NOx in the Presence of Ammonia,” SAE Technical Paper 2007-01-0331, 2007.
- Benjamin, S. F., Roberts, C. A. “The porous medium approach applied to CFD modelling of SCR in an automotive exhaust with injection of urea droplets.” IMechE Conference Internal Combustion Engines: Performance, Fuel Economy and Emissions, London, 2007