디젤 NO<SUB>x</SUB> 후처리 장치에 있어서 암모니아 SCR 시스템 혼합영역 내 가스유동의 유입열 수치모델링에 관한 연구

배명환; 샤이풀

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Selective catalytic reduction(SCR) is known as one of promising methods for reducing NO_x emissions in diesel exhaust gases. NO_x emissions react with ammonia in the catalyst surface of SCR system at working temperature of catalyst. In this study, to raise the reacting temperature when the exhaust gas temperature is too low, a heater is located at the bottom of SCR reactor. At an ambient temperature, ammonia is radially injected perpendicular to the exhaust gas flow at inlet pipe and uniformly mixed in the mixing area after being impinged against the wall. To predict the turbulent model inside the mixing area of SCR system, the standard k - ε model is applied. This work investigates numerically the effects of induced heat on the gaseous flow. The results show that the Taylor-Gortler type vortex is generated after the gaseous flow impinges the wall in which these vortices influence the temperature distribution. The addition of heat disturbs the flow structure in bottom area and then stretching flow occurs. Vorticity strand is also formed when heat is continuously increased. Constriction process takes place, however, when a further heat input over a critical temperature is increased and finally forms shed vortex which is disconnected from the vorticity strand. The strong vortex restricts the heat transport in the gaseous flow.

#Ammonia SCR System (암모니아 SCR 시스템) #Diesel NO< #SUB> #x< #/SUB> # After-treatment Device(디젤NO< #SUB> #x< #/SUB> # 후처리 장치) #Numerical Modeling(수치모델링) #Induced Heat(유입열) #Gaseous Flow(가스유동) #Working Temperature(작동온도) #Vortex(와류)