Journal of ILASS-Korea (한국분무공학회지)

Institute for Liquid Atomization and Spray Systems-Korea (한국분무공학회)
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Study on Ammonia Uniformity and DeNOx Analysis in the Urea-SCR System for Construction Machinery

건설기계용 Urea-SCR 시스템의 촉매전단에서 암모니아 균질도 해석 및 DeNOx 성능에 관한 연구

  • 김동환 (한양대학교 대학원 융합기계공학과) ;
  • 박준규 (한양대학교 부설 산업과학연구소) ;
  • 강정호 (자동차부품연구원) ;
  • 문성준 (자동차부품연구원) ;
  • 박성욱 (한양대학교 기계공학부)
  • Received : 2019.01.07
  • Accepted : 2019.03.19
  • Published : 2019.06.30
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Abstract

In this study, the spray atomization characteristics of urea injector used in SCR system for construction machinery was analyzed, and the uniformity index at the front of mixer and NOx conversion efficiency were evaluated through numerical analysis. Spray visualization and droplet size/velocity measurement were performed and the measured results were used to verify the spray analysis model to calculate the uniformity index in the exhaust gas after-treatment system. For the flow analysis, STAR-CCM, a three-dimensional CFD, was used and the uniformity index of the SCR system at the front of the mixer was calculated using the droplet dissociation model and the wall collision model. Finally, the DeNOx performance for the average condition of the NRTC driving mode was calculated to understand the NOx conversion efficiency reflecting the exhaust gas temperature. The simulation results show that the uniformity index at the front of mixer was calculated as 0.862 and DeNOx efficiency was 75.9%.

Keywords

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Fig. 1 Experimental apparatus for spray visualization

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Fig. 2 Experimental apparatus for droplet size and veloc-ity measurement

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Fig. 4 Urea spray tomography images for various injec-tion pressures

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Fig. 3 Urea spray development process for various injec-tion pressures

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Fig. 5 Number of pixels counted at urea spray tomogra-phy images for various injection pressures

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Fig. 8 Geometry of mixer

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Fig. 9 Model validation result of urea spray model

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Fig. 10 Ammonia uniformity index, pressure and tempera-ture distribution

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Fig. 11 NOx generation and NRTC mode estimation for each load

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Fig. 6 Droplet diameter and velocity distribution of urea spray for various injection pressure

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Fig. 7 Comparisons of mean droplet dimeter and velocity for various injection pressure

Table 1. Experimental conditions

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