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디젤차량용 DOC 후처리 장치의 성능에 대한 수치적 연구
왕태중(Tae Joong Wang),백승욱(Seung Wook Baek),이제형(Je-Hyung Lee) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Simulation study on DOC (diesel oxidation catalyst) system, which is designed to reduce the gaseous CO, HC, and SOF of diesel PM, was carried out. DOC uses a catalytic reaction, and is now widely applied for reducing diesel emissions to levels required by emission standards. The present study mainly aims at developing a multi-dimensional computational model to analyze the characteristics of DOC as well as simulate it. Mobile DOC system commonly utilizes a honeycomb type of monolith substrate, and reductions of emissions are accomplished by complex coupled chemico-physical mechanism. In this study, catalytic reactions are modeled as Langmuir-Hinshelwood expressions over platinum-based catalysts. Also, to represent heat and mass transfers, the reactor was modeled in two dimensional, axisymmetric domains using porous medium approach. In addition, throughout simulations using the developed code, effects of various system parameters on the DOC performance were investigated.
디젤 SCR 후처리장치 내 공간속도가 NOx 저감에 미치는 영향
왕태중(Tae Joong Wang),백승욱(Seung Wook Baek),강대환(Dae Hwan Kang),길정기(Jung Ki Kil),여권구(Gwon Koo Yeo) 한국연소학회 2006 KOSCOSYMPOSIUM논문집 Vol.- No.-
The present study conducted a numerical modeling on the diesel SCR (selective catalytic reduction) system using ammonia as a reductant over vanadium-based catalysts (V₂O?-WO₃/TiO₂). Transient modeling for ammonia adsorption/desorption on the catalyst surface was firstly carried out, and then the SCR reaction was modeled considering for it. In the current catalytic reaction model, we extended the pure chemical kinetic model based on laboratory-scale powdered-phase catalyst experiments to the chemico-physical one applicable to realistic commercial SCR reactors. To simulate multi-dimensional heat and mass transfer phenomena, the SCR reactor was modeled in two dimensional, axisymmetric domain using porous medium approach. Also, since diesel engines operate in transient mode, the present study employed an unsteady model. In addition, throughout simulations using the developed code, effects of space velocity on the DeNOx performance were investigated.
An Experimental Study on the Performance Characteristics of DOC Equipped in Diesel Passenger Car
Tae Joong Wang(왕태중),Seung Wook Baek(백승욱),Jeong Ho Kang(강정호),Yong Tae Kim(김용태),Je-Hyung Lee(이제형) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Engine-dynamometer experiments covering a wide range of operating conditions were performed for examining the performance of DOC (diesel oxidation catalyst) system. For the fixed two cases of engine speed (1000 and 1500 rpm), the concentrations of CO, HC, Total NOx, NO, and NO₂ were mainly measured at DOC inlet and outlet. Concentration measurements for the emissions were carried out after the system reached its steady-state, and those procedures were repeated with increasing the DOC substrate temperature up to the maximum value of each operating condition. Almost complete conversions of CO were found, and HC conversion efficiencies of 62% to 83% were obtained at all the catalyst temperatures above the light-off. Also, NO and NO₂ conversions showed opposite trends, and only a small amount of the total NOx was reduced over all temperature ranges.
왕태중,백승욱,Wang, Tae-Joong,Baek, Seung-Wook 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.9
The present study is mainly motivated to investigate the vaporization, auto-ignition, and combustion of liquid fuel spray injected into high pressure environment. The unsteady, multi-dimensional models were used for realistic simulation of spray as well as prediction of accurate ignition delay time. The Separated Flow (SF) model which considers the finite rate of transport between liquid and gas phases was employed to represent the interactions between spray and gas field. Among the SF models, the Discrete Droplet Model (DDM) which simulates the spray using finite number of representative samples of discrete droplets was adopted. The Eulerian-Lagrangian formulation was used to analyze the two-phase interactions. In order to predict an evaporation rate of droplet in high pressure environment, the high pressure vaporization model was applied using thermodynamic equilibrium and phase equilibrium at droplet surface. The high pressure effect as well as high temperature effect was considered in the calculation of liquid and gas properties. In case of vaporization, an interaction between droplets was studied through the simulation of spray. The interaction is shown up differently whether the ambient gas field is at normal pressure or high pressure. Also, the characteristics of spray behavior in high pressure environment were investigated through the comparison with normal ambient pressure case. In both cases, the spray behaviors are simulated through the distributions of temperature and reaction rate in gas field.