Mixing and evaporation analysis of a high-pressure SCR system using a hybrid LES-RANS approach
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2017-02
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Language
en
Pages
15
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Energy, Volume 120, pp. 827-841
Abstract
A hybrid Large Eddy Simulation (LES) - Reynolds-Averaged Navier-Stokes (RANS) method (HLR) has been applied to simulate an engine related selective catalytic reduction (SCR) system. Typical SCR systems utilize low pressure urea injection together with a mixer for vapor field homogenization. Simultaneously, it is also desirable to reduce spray-wall interaction to avoid urea crystallization. The present study considers an SCR system where a high pressure (150 bar) urea spray is injected towards hot exhaust gases in exhaust pipe. The system has been shown to work well in a previous experimental study but detailed characterization of the system is missing. The novelty of the present study rises from: 1) the creation of phase diagrams with single droplet simulations that predict the optimum operation regions for the SCR system, 2) validation of the HLR method in a high Reynolds number (Re=49,900) compressible pipe flow, 3) the use of HLR simulations in an engine SCR system for the first time, and 4) the detailed characterization of the present SCR system. As a result of the study, new non-dimensional timescale ratios are proposed to link the droplet size and liquid injection velocity to the exhaust pipe dimensions in future SCR systems.Description
Keywords
Computational Fluid Dynamics, Hybrid LES-RANS, NO reduction, SCR spray design, Selective Catalytic Reduction (SCR), Urea mixing
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Citation
Kaario, O T, Vuorinen, V, Zhu, L, Larmi, M & Liu, R 2017, ' Mixing and evaporation analysis of a high-pressure SCR system using a hybrid LES-RANS approach ', Energy, vol. 120, pp. 827-841 . https://doi.org/10.1016/j.energy.2016.11.138