Journal of ILASS-Korea (한국분무공학회지)

Institute for Liquid Atomization and Spray Systems-Korea (한국분무공학회)
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A Study on the Improvement of Diesel NOx Conversion Efficiency by Increasing the Ammonia Amount Adsorbed in a SCR Catalyst

디젤엔진 요소수 분사 SCR 시스템에서 촉매 내 암모니아 흡장량의 증가에 따른 NOx 저감효율 향상 특성에 관한 연구

  • 김양화 (울산대학교 일반대학원 기계자동차공학과) ;
  • 임옥택 (울산대학교 기계공학부) ;
  • 김홍석 (한국기계연구원 그린동력연구실)
  • Received : 2020.09.15
  • Accepted : 2020.10.16
  • Published : 2020.12.31
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Abstract

Nowadays, urea SCR technology is considered as the most effective NOx reduction technology of diesel engine. However, low NOx conversion efficiency under low temperature conditions is one of its problems to be solved. This is because injection of UWS (Urea Water Solution) is impossible under such a low temperature condition due to the problem of insufficient of urea decomposition and urea deposits. In several previous studies, it has been reported that appropriate control of the amount of ammonia adsorbed on SCR catalyst can improve the NOx conversion efficiency under low temperature conditions. In this study, we tried to find out how much the NOx conversion efficiency increases with respect to the amount of ammonia adsorbed on the catalyst, and what the temperature conditions that the ammonia slip occurs. This study shows the results of 8 times repeated WHTC test with a diesel engine, in which UWS was injected with NH3/NOx mole ratio of '1'. Through this study, it was found that 13% of the NOx conversion efficiency of WHTC increased while the θ (ammonia adsorption rate) increased from "0%" to "22%". In addition, it is found that in cases of high θ value, the significant improvement of NOx conversion efficiency at low temperatures presented during the beginning period of WHTC and at high temperature and transient conditions presented during last part of WHTC test. The NH3 slip occurring condition was 250℃ of catalyst temperature and 10% of θ, and the amount of NH3 slip increased as the temperature and θ are increased.

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References

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