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Urea-SCR System의 SV에 다른 NOx 저감에 관한 실험적 연구
박용성(Yongsung Park),김남용(Namyong Kim),최동석(Dong-Seok Choi),정혁(Hyuk Jung),김용우(Yongwoo Kim),정홍석(Hong-Seok Jung),김성환(Sung-Hwan Kim),조연근(Yunguen Cho),이성호(Seongho Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The Effect of Space Velocity(SV) on NOx conversion rate was performed to develop NOx reduction after treatment system. Space Velocity is calculated from engine exhaust gas volume and SCR Catalyst volume. Found the Urea injection Duty of maximum efficiency for NOx conversion If increase Space Velocity, NOx Conversion rate is down. Especially, When space velocity is more than 140,000h?¹, NOx conversion rate decrease suddenly. Same case, If Space velocity is lower than 30,000h?¹ NOx conversion rate is down.
지올라이트계 촉매를 이용한 대형디젤자동차용 Urea-SCR 시스템 개발
최동석(Dong-Seok Choi),박용성(Yongsung Park),김남용(Namyong Kim),정혁(Hyuk Jung),이정기(Jungki Lee),이성호(Seongho Lee),김용우(Yongwoo Kim),오승훈(Seung-Hoon Oh) 한국자동차공학회 2007 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-
The development of urea-SCR system was performed to reduce NOx emission from heavy duty diesel engines. Two candidate nozzles (1 hole and 4 hole nozzle) for urea dosing were tested with air-assisted pressures. NOx conversion ratio and NH₃ slip are the main factors to choose the urea dosing nozzle. Urea dosing quantity for overall operating region was determined. NOx conversion ratio was also tested with exhaust temperature and space velocity. The performance of urea-SCR system was estimated as ESC. It was found that NOx conversion ratio is higher as the temperature before SCR catalyst is higher and the space velocity is faster within the temperature of 350℃. Approximately 84% NOx reduction was achieved in the ESC test.
NH₃-SCR 촉매를 이용한 디젤기관에서의 NOx 저감에 관한 연구
박경균(Kyounggyun Park),이원석(Wonseok Lee),이성욱(Seongwock Lee),강호인(Hoin Kang),나완용(Wanyong Rha),손용기(Yonggy Son),임인혁(Inhyuk Im),황재원(Jaewon Hwang) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Diesel engines provide merits in the aspect of higher thermal efficiency and less CO₂ emission, but more problems on PM and NOx emissions. Selective Catalyst Reduction(SCR) technology is well-known to be effective for the reduction of NOx emission. SCR system can be classified into three kinds of NSR, NH₃-SCR and HC-SCR depending on reducing agents in jet spray. Because of poisoning problem of sulfur and unstable gas condition, much stable Urea-SCR system has been preferred to use instead. However, this research used to NH₃ gas instead Urea solution to model gas test. It is general to use NH₃-SCR catalyst for the NOx reduction on a diesel engine. This research focuses on the effects of gas temperature, SV(space velocity) and AR(aspect ratio) of NOx reduction rate. In this experiment was used the model gas which is similar to a diesel exhaust gas. NOx conversion rate is higher than 90% at the temperature of near 400℃ for all cases. As SV is lower, NOx conversion rate is decreased. On the contrary, as AR is higher, NOx conversion rate is increased.
SCR 촉매와 AOC 촉매에서 환원제 분사에 따른 NO<SUB>x</SUB> 저감효율과 NH₃ 변환효율에 관한 실험적 연구
동윤희(Yoonhee Dong),김지훈(Jihun Kim),최정황(Junghwang Choi),조용석(Yongseok Cho),이성욱(Seangwock Lee),나완용(Wanyong Ra),박현대(Hyundae Park) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
As the environmental regulation of vehicle emission is strengthened, investigations for NOx and PM reduction strategies are popularly conducted. Two current available technologies for continuous NOx reduction onboard diesel vehicles are Selective Catalytic Reduction (SCR) using aqueous urea and lean NOx trap (LNT) catalysts. The experiments were conducted to investigate the NOx reduction performance of SCR system which can control the ratio of NO/NO₂, temperature and SV(space velocity), and the model gas was used which is similar to a diesel exhaust gas. The maximum reduction efficiency is indicated when the NO:NO₂ ratio is 1:1 and the SV is 30,000 h?¹ in 300℃. Generally, ammonia slip from SCR reactors are rooted to incomplete conversion of NH₃ over the SCR. In this research, slip was occurred in 6cases (except low SV and NO:NO₂ ratio is 1:1) after SCR. Among 6 case of slip occurrence, the maximum conversion efficiency is observed when SV is 60,000 h?¹ in 400℃.
SCR 촉매와 AOC 촉매에서 환원제 분사에 따른 NO<SUB>x</SUB> 저감효율과 NH₃ 변환효율에 관한 실험적 연구
동윤희(Yoonhee Dong),최정황(Junghwang Choi),조용석(Yongseok Cho),이성욱(Seangwock Lee),이승호(Seongho Lee),오상기(Sangki Oh),박현대(Hyundae Park) 한국자동차공학회 2010 한국 자동차공학회논문집 Vol.18 No.5
As the environmental regulation of vehicle emission is strengthened, investigations for NO<SUB>x</SUB> and PM reduction strategies are popularly conducted. Two current available technologies for continuous NO<SUB>x</SUB> reduction onboard diesel vehicles are Selective Catalytic Reduction (SCR) using aqueous urea and lean NO<SUB>x</SUB> trap (LNT) catalysts. The experiments were conducted to investigate the NO<SUB>x</SUB> reduction performance of SCR system which can control the ratio of NO/NO₂, temperature and SV(space velocity), and the model gas was used which is similar to a diesel exhaust gas. The maximum reduction efficiency is indicated when the NO:NO₂ ratio is 1:1 and the SV is 30,000 h?¹ in 300℃. Generally, ammonia slip from SCR reactors are rooted to incomplete conversion of NH₃ over the SCR. In this research, slip was occurred in 6cases (except low SV and NO:NO₂ ratio is 1:1) after SCR. Among 6 case of slip occurrence, the maximum conversion efficiency is observed when SV is 60,000 h?¹ in 400℃.
Urea-SCR 촉매가 코팅되는 전기히터 시스템의 NOx저감 성능에 관한 연구
최현하(Huunha Choi),김홍석(Hongsuk Kim),정용일(Yongil Jeong),임인혁(In-hyuk Im),박정한(Jeonghan Park),황재원(Jae-Won Hwang) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
It is well known that a urea-SCR system can reduce NOx emissions of a diesel engine effectively. But the urea-SCR technology does not shows a good NOx reduction performance at low temperature exhaust gas conditions. This study introduces a newly developed urea-SCR catalyst coated electrical heater system. This system can reduce NOx emissions of a diesel engine effectively even though at low temperature exhaust gas conditions by increasing the surface temperature of SCR catalyst electrically. The study compares the NOx reduction performance of the newly developed urea-SCR system with a conventional system. This study shows that the new urea-SCR system has high performance and low NH₃ slip at the low temperature exhaust gas conditions.
LNT의 기하학적 형상이 NOx 전환 효율에 미치는 영향에 대한 수치적 연구
심성민(Sung-Min Shim),김영득(Young-Deuk Kim),정수진(Soo-Jin Jeong),김우승(Woo-Seong Kim) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The lean NOx trap (LNT) is one of the promising technologies for the NOx reduction of gasoline lean bum and diesel engines to meet more stringent future emission regulations such as EURO 5 or 6. The adsorption sites in the wash coat take up NOx from engine exhaust gas during the lean condition and store NOx as nitrates. After running at the lean condition for a period of time, LNT is operated under the rich condition for a few seconds. Therefore, adsorbed NOx is released from the BaO sites and then reduced on the Pt sites. In this paper, a one-dimensional two-phase model of an adsorptive catalytic monolith reactor has been used to predict the performance of LNT in terms of NOx and CO conversion efficiency. The parametric investigations are numerically performed to examine the effect of the volume of LNT with various lengths and cross-sectional areas, GHSV(Gas Hourly Space Velocity), and geometric parameters such as cell density and wall thickness on the performance of LNT. An increase of GHSV decreases the NOx and CO conversion efficiency.
이성욱,조용석,M. SONG,H. KIM,J. PARK,백두성 한국자동차공학회 2012 International journal of automotive technology Vol.13 No.3
Particulate matter in diesel engine exhaust, particularly nano-particles, can cause serious human health problems including diseases such as lung cancer. Because diesel nano-particle issues are of global concern, regulations on particulate matter emissions specify that not only the weight of particulate matter emitted but also the concentration of nanoparticles must be controlled. This study aimed to determine the effects on nano-particle and PM emissions from a diesel engine when applying a urea-SCR system for NOx reduction. We found that PM weight increases by approximately 90% when urea is injected in ND-13 mode over the emission without urea injection. Additionally, PM weight increases as the NH3/NOx mole ratio is increased at 250 oC. In SEM scans of the collected PM, spherical particles were observed during urea injection, with sizes of approximately 200 nm to 1 μm. This study was designed to determine the conditions under which nano-particles and PM are formed in a urea-SCR system and to relate these conditions to particle size and shape via a quantitative analysis in ND- 13 mode.
The optimal volume of a combined system of LNT and SCR catalysts
서충길,Byungchul Choi,Hwanam Kim,Myung Taeck Lim 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.3
This paper aims to find the optimal volumes of the LNT (Lean NOx Trap) and SCR (Selective Catalytic Reduction) catalysts for higher de-NOx performance and suppression of N_2O and NH_3 in a combined system of LNT + SCR. The basic characteristics of the LNT catalyst were identified first at various space velocities (SV), and then the effects of the variation in volume of the combined system were investigated. The NOx conversion, NH3 production, and N_2O emissions were evaluated of four differently sized LNT–SCR systems. Considering all together the NOx conversion, cost of the precious metal, NH3 slippage, and N_2O generation, the optimal volume ratio of LNT and SCR catalysts was found to be 1:1 for the LNT–SCR system.
The optimal volume of a combined system of LNT and SCR catalysts
Seo, C.K.,Kim, H.,Choi, B.,Lim, M.T. Korean Society of Industrial and Engineering Chemi 2011 Journal of industrial and engineering chemistry Vol.17 No.3
This paper aims to find the optimal volumes of the LNT (Lean NOx Trap) and SCR (Selective Catalytic Reduction) catalysts for higher de-NOx performance and suppression of N<SUB>2</SUB>O and NH<SUB>3</SUB> in a combined system of LNT+SCR. The basic characteristics of the LNT catalyst were identified first at various space velocities (SV), and then the effects of the variation in volume of the combined system were investigated. The NOx conversion, NH<SUB>3</SUB> production, and N<SUB>2</SUB>O emissions were evaluated of four differently sized LNT-SCR systems. Considering all together the NOx conversion, cost of the precious metal, NH<SUB>3</SUB> slippage, and N<SUB>2</SUB>O generation, the optimal volume ratio of LNT and SCR catalysts was found to be 1:1 for the LNT-SCR system.