2.2L 디젤 엔진에서 NO<SUB>x</SUB> 흡장률 기반 LNT 재생 조건 결정

천봉수(Bongsu Chun),이정우(Jungwoo Lee),한만배(Manbae Han) 한국자동차공학회 2016 한국 자동차공학회논문집 Vol.24 No.3

This study was carried out to determine an optimal lean NO<SUB>x</SUB> trap (LNT) regeneration condition based on a NO<SUB>x</SUB> storage fraction. The LNT regeneration was performed by an in-cylinder post fuel injection method. A NO<SUB>x</SUB> storage fraction is defined by the ratio of current cumulated NO<SUB>x</SUB> amount in the LNT to the NO<SUB>x</SUB> storage capacity: 0 means empty and 1 fully loaded. In this study five engine operating conditions were chosen to represent the New European Driving Cycle. With various NO<SUB>x</SUB> storage fractions each engine operating condition, the LNT regeneration was executed and then NO<SUB>x</SUB> conversion efficiency, additional fuel consumption, CO and THC slip, peak catalyst temperature were measured. The results showed that there exist an optimal condition to regenerate the LNT, eg. 1500 rpm 6 bar BMEP with below 0.7 NO<SUB>x</SUB> storage fraction in this experimental constraint.

바나듐 계열 촉매를 통한 NO<SUB>X</SUB>의 NH<SUB>3-</SUB>SCR에 관한 실험적 연구

정희찬(Hee-Chan Jeong),심성민(Sung-Min Sim),김영득(Young-Deuk Kim),정수진(Soo-Jin Jeong),김우승(Woo-Seung Kim) 한국자동차공학회 2012 한국 자동차공학회논문집 Vol.20 No.1

The NH<SUB>3-</SUB>SCR characteristics of NOX over a V-based catalyst are experimentally examined over a wide range of operating conditions, i.e., 170-590℃ and 30,000-50,000 h<SUP>-1</SUP>, with a simulated diesel exhaust containing NH₃, NO, NO₂, O₂, H₂O, and N₂. The influences of the space velocity and oxygen concentration on the standard-SCR reaction are analyzed, and it is shown that the low space velocity and high oxygen concentration promote the SCR activity by ammonia. The best deNO<SUB>X</SUB> efficiency is obtained with a NO₂/NOX ratio of 0.5 because of an enhanced chemical activity induced by the fast-SCR reaction, while at the NO₂/NO<SUB>X</SUB> ratios above 0.5 the deNO<SUB>X</SUB> activity decreases due to the slow-SCR reaction. The oxidation of ammonia begins to take place at about 300℃ and the reaction products, such as N₂, NO, NO₂, N₂O, and H₂O, are produced by the undesirable oxidation reactions of ammonia, particularly at high temperatures above 450℃. Also, NO₂ decomposes to NO and O₂ at temperatures above 240℃. Therefore, NO₂ decomposition and ammonia oxidation reactions deteriorate significantly the SCR catalytic activity at high temperatures.

2015년 봄철에 선박으로 관측한 서해상 이차에어로졸 성분의 농도 및 오염 특성

고희정(Hee-Jung Ko),강창희(Chang-Hee Kang),차주완(Joo Wan Cha),류상범(Sang-Boom Ryoo) 한국기상학회 2017 대기 Vol.27 No.1

The PM<SUB>10</SUB> and PM<SUB>2.5</SUB> particles over the Yellow Sea of Korea were collected by shipborne observation during two cruises in spring, 2015. Their water-soluble ionic components such as NH<SUB>4</SUB><SUP>+</SUP>, Na<SUP>+</SUP>, K<SUP>+</SUP>, Mg<SUP>2+</SUP>, Ca<SUP>2+</SUP>, SO<SUB>4</SUB><SUP>2−</SUP>, NO<SUB>3</SUB><SUP>−</SUP>, Cl<SUP>−</SUP>, F<SUP>−</SUP>, CH<SUB>3</SUB>COO<SUP>−</SUP>, HCOO<SUP>−</SUP>, and CH<SUB>3</SUB>SO<SUB>3</SUB><SUP>−</SUP> were analyzed, in order to examine the pollution characteristics of the secondary aerosol components. The comparative study of particle size distribution has resulted that NH<SUB>4</SUB><SUP>+</SUP>, nss-SO<SUB>4</SUB><SUP>2−</SUP>, nss-Mg<SUP>2+</SUP>, nss-K<SUP>+</SUP>, HCOO<SUP>−</SUP>, and CH<SUB>3</SUB>SO<SUB>3</SUB><SUP>-</SUP> species mostly existed in fine particle mode. Meanwhile, nss-F-and sea-salt species were distributed in both fine and coarse particle mode, NO<SUB>3</SUB><SUP>−</SUP>, nss-Ca<SUP>2+</SUP>, CH<SUB>3</SUB>COO<SUP>-</SUP> species were rich in coarse particle mode. The concentrations of secondary pollutants (nss-SO<SUB>4</SUB><SUP>2−</SUP>, NO<SUB>3</SUB><SUP>−</SUP>, NH<SUB>4</SUB><SUP>+</SUP>) increased in fine particles, and those of natural components (nss-Ca<SUP>2+</SUP>, Sea-salt) increased in coarse particles. NH<SUB>4</SUB><SUP>+</SUP> exists as the form of (NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB> and NH<SUB>4</SUB>NO<SUB>3</SUB>, and mostly as (NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB> in fine particles. NH<SUB>4</SUB>NO<SUB>3</SUB> has lower content compared to (NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB>, and it mostly existed in fine particles at Yellow Sea I and in coarse particles at Yellow Sea Ⅱ. The concentration ratios of NO<SUB>3</SUB><SUP>−</SUP>/nss-SO<SUB>4</SUB><SUP>2−</SUP> for Yellow Sea I and Yellow Sea Ⅱ were 0.52 and 0.16 in coarse particles, and they were 0.64 and 0.38 in fine particles, respectively, showing that the stationary source emissions were more important than mobile source emissions in Yellow Sea II (except Passage II-4).

일반 공기 및 순산소 연소 조건에서 Fuel-NO<SUB>x</SUB> 생성 특성의 비교

우민호(Mino Woo),박권하(Kweon Ha Park),최병철(Byung Chul Choi) 대한기계학회 2013 大韓機械學會論文集B Vol.37 No.5

10 %의 암모니아가 첨가된 메탄 연료의 비예혼합 확산화염에서, 산소/이산화탄소 및 산소/질소의 산화제 내에 산소 비율의 변화에 따른 질소산화물(NO_x)의 생성 특성을 실험 및 수치해석적으로 조사하였다. 동축류 제트 화염의 실험에서, 산소/이산화탄소의 산화제인 경우, 측정된 NO_x 은 산소비율의 증가에 따라 약간 증가하는 경향을 보였다. 반면에, 산소/질소의 산화제인 경우, NO_x 은 0.7의 산소 비율에서 최대로 측정되었으며, 산소 비율에 따라 비단조적인 경향을 보였다. 결과적으로, 암모니아가 첨가된 메탄 화염에서 배출되는 NO_x 는 일반 공기의 조건보다 순산소 연소 조건의 경우가 더 크게 측정되었다. 한편, 다양한 산화제의 조건에 대하여 NO_x 생성 특성을 분석하기 위해서, 동일한 화학반응 메커니즘을 적용하여 1차원 및 2차원의 수치해석을 수행하였다. 그 결과, 산소/질소의 산화제에서 2차원의 수치해석 결과가 실험적으로 측정된 NO_x 의 배출 특성을 비교적 잘 예측하였다. Nitric oxide (NO_x) formation characteristics in non-premixed diffusion flames of methane fuels have been investigated experimentally and numerically by adding 10% ammonia to the fuel stream, according to the variation of the oxygen ratio in the oxidizer with oxygen/carbon dioxide and oxygen/nitrogen mixtures. In an experiment of coflow jet flames, in the case of an oxidizer with oxygen/carbon dioxide, the NO_x emission increased slightly as the oxygen ratio increased. On the other hand, in case of an oxygen/nitrogen oxidizer, the NO_x emission was the maximum at an oxygen ratio of 0.7, and it exhibited non-monotonic behavior according to the oxygen ratio. Consequently, the NO_x emission in the condition of oxyfuel combustion was overestimated as compared to that in the condition of conventional air combustion. To elucidate the characteristics of NO_x formation for various oxidizer compositions, 1D and 2D numerical simulations have been conducted by adopting one kinetic mechanism. The result of 2D simulation for an oxidizer with oxygen/nitrogen well predicted the trend of experimentally measured NO_x emissions.

대형경유자동차의 NO₂/NO<SUB>X</SUB> 비율과 NO<SUB>X</SUB> 배출특성에 관한 연구

정택호(Taek Ho Chung),김선문(Sun Moon Kim),문선희(Sun Hee Mun),홍희경(Hee Kyoung Hong),이승환(Seoung Hwan Lee),서석준(Seok Jun Seo),김정화(Joung Hwa Kim),정성운(Sung Woon Jung),김인구(In Gu Kim),이종철(Jong Chul Lee),이종태(Jong Tae 대한환경공학회 2019 대한환경공학회지 Vol.41 No.4

대형경유자동차에서 배출되는 NOx는 국내 NOx 배출량 중 높은 비율을 차지하고 있으며, NO₂는 인체에 유해하며 대기환경을 오염시키는 물질로 알려져 있다. 본 연구에서는 대형경유트럭과 대형경유버스에서 배출되는 NOx를 실시간으로 측정하였으며, 다양한 조건에 따른 NO₂/NOx 비율과 NOX 배출특성을 파악하였다. 실시간으로 NOx의 농도를 측정한 결과 NO와 NO₂의 농도는 높은 출력을 요구하는 가속구간에서 증가하는 것으로 나타났다. 시험모드별 대형트럭의 NOX 배출량은 WHVC>NIER 9>UDDS 순으로 낮은 평균속도에서 높게 배출되었다. 반면, 대형버스의 NOx 배출량은 평균속도가 증가할수록 높게 배출되는 것을 확인하였다. 엔진 상태에 따른 대형트럭과 버스의 NOX 배출량은 엔진 미가열조건에서 23%, 78% 높게 배출되었다. 대형트럭과 대형버스의 NO₂/NOx 비율은 엔진 가열조건에서 각각 0.7~1.0%, 7.7~7.8%로 확인되었다. 본 연구의 결과는 도로변대기측정망의 NO₂ 농도 산정을 위한 기초자료로 활용될 것으로 기대한다. NOx emitted from heavy-duty diesel vehicles has a high percentage of domestic emissions in Korea. It is known that the NO₂ emission was polluted the atmospheric environments and was harmful to humans. Therefore, investigation on NO₂//NOx Ratio and NOx Emission Characteristics of Heavy-Duty Diesel Vehicles were carried out. In this study, NOx emissions from heavy-duty trucks and buses were measured by chassis dynamometer for heavy-duty vehicle in real time. Also, NO₂/NOx ratio and NOx emission characteristics were analyzed by emission analyzer according to various conditions. It is revealed that NO and NO₂ concentrations were increased in the acceleration section from results of NOx concentration in real time. The NOx emissions of heavy-duty trucks in test mode was confirmed a high level in order the average speed, but NOx emissions of heavy-duty buses were increased as the average speed increased. The NO₂/NOx ratio of heavy duty trucks and buses was 0.7~1.0% and 7.7~7.8% at hot start engine condition. The results of this study will contribute to be used as basic data for the estimation of NO₂ concentration in the roadside air monitoring network.

디젤 산화촉매의 귀금속 함량에 따른 NO₂ 배출량 변화 특성

김훈명(Hoonmyung Kim),박용성(Yongsung Park),최승환(Seunghwan Choi),이광구(Gwang-Goo Lee) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.4

Emission characteristics of NO₂ are carefully investigated with the contents of precious metal in diesel catalyst system, which consists of oxidation catalyst and diesel particulate filter in a single can. The diesel engine is tested by three types of experimental methods. From the NO₂ conversion test at the rated RPM, the conversion rate of NO<SUB>x</SUB> into NO₂ decreases in lower precious metal case (Catalyst B) compared with base case (Catalyst A). The increase rate of NO₂ is calculated using the measured NO<SUB>x</SUB>(NO, NO₂) concentrations in ETC mode test. It is lowered by 6 % in Catalyst B because of its larger light-off time. BPT test consisting of 10 load stages at the rated RPM shows that balance point temperature of PM increases with the lower content of precious metal. All the experimental results consistently indicate that it is possible to satisfy NO<SUB>x</SUB> regulation by properly lowering content of precious metal in diesel catalyst system.

NH₃-SCR 방법에 의한 디젤 배기 내 De-NO<SUB>x</SUB> 과정에서의 DOC에 의한 영향과 저감 성능 변화

정승채(Seung-chai Jung),윤웅섭(Woong-sup Yoon) 한국자동차공학회 2008 한국 자동차공학회논문집 Vol.16 No.5

Diesel NO<SUB>x</SUB>, reduction by NH₃-SCR in conjunction with the effective oxidation precatalyst was analytically investigated. Physicochemical processes in regard to NH₃-SCR NO<SUB>x</SUB> reduction and catalytic NO-NO₂ conversion are formulated with detailed descriptions on the commanding reactions. A unified model is correctly validated with experimental data in terms of extents of NO<SUB>x</SUB> reduction by SCR and NO-NO₂ conversion by DOC. The present deterministic model based on the rate expressions of Langmuir-Hinshelwood reaction scheme finds a conversion extent directly. A series of numerical experiments concomitant with parametric analysis of the NO<SUB>x</SUB> reduction was conducted. NO<SUB>x</SUB> reduction is promoted in proportion to DOC volume ar lower temperatures and an opposite holds at lower space velocity and intermediate temperatures. NO<SUB>x</SUB> conversion is weakly correlated to the space velocity and the DOC volume at higher exhaust temperature. In DOC-SCR system, the NO<SUB>x</SUB> reduction efficiency depends on the NH₃/NO<SUB>x</SUB> ratio.

선택적 환원 촉매(SCR)에서 배출가스 특성에 따른 NO<SUB>x</SUB> 변환효율 및 환원제(NH₃) 분사량 최적화에 관한 실험적 연구

오준석(June-Seok Oh),윤여빈(Yu-Bin Yoon),송춘섭(Chun-Sub Song),박영준(Young-Joon Park),이성욱(Seang-Wock Lee),조용석(Yong-Seok Cho) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4

The selective catalytic reduction(SCR) system is potentially a highly-effective means of NO<SUB>x</SUB> reduction for diesel engine. Generally, SCR makes use of a reductant added to the exhaust gas that can be used for reacting NO and NO₂ to N₂. The reductant, ammonia(NH₃) generated from a liquid urea-water solution. De-NO<SUB>x</SUB> process in the SCR, the ideal ratio of NH₃ molecules to NO<SUB>x</SUB> molecules is 1:1 for high efficiency of NO<SUB>x</SUB> reduction. The SCR system has good NO<SUB>x</SUB> reduction performance in the temperature window of about 250 to 400℃, low space velocity also leads an increase of NO<SUB>x</SUB> reduction efficiency, due to long residence time in the catalyst. This paper reviews a laboratory study to evaluate the effects of NO<SUB>x</SUB>-NH₃ concentrations, gas temperature and space velocity on the NO<SUB>x</SUB> reduction efficiency of the SCR. The maximum reduction efficiency is indicated when the NH₃ to NO<SUB>x</SUB> ratio is 1.2 and the space velocity is 30,000 h?¹ in 300℃. However, under various exhaust conditions, NH₃ injection amount need to be controlled for a high NO<SUB>x</SUB> conversion efficiency because of reducing unnecessary NH₃ consumption. Based on results of the rig-test, this study suggests the control strategy of NH₃ injection for optimizing NO<SUB>x</SUB> reduction efficiency.

SCR 관련 단품 및 c-DPF 내 Soot 퇴적량에 따른 SCR 촉매의 NO<SUB>x</SUB>정화 효율 변화에 관한 연구

김형식(Hyoung Sik Kim),전종익(Jong Ik Jeon),최창은(Chang Eun Choi),김원근(Won Kun Kim) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11

In this study, the parameters of SCR system which effect on NOx conversion efficiency have been investigated. The NOx sensor located in front of SCR catalyst and the urea injector dosing urea solutions to the SCR catalyst play important roles in NOx conversion efficiency of SCR system. First, NOx conversion efficiency has been decreased when NOx sensor reads engine out NOx emission lower than the actual engine out NOx emission, because it brings about the lack of urea injection quantity. Second, the NOx conversion efficiency has been also decreased when urea injector doses less amount of urea solution than the system required. Finally, Applying the aged catalyst system (DOC, c-DPF, SCR) and the soot loading amount in c-DPF also have effects on the change of NOx conversion efficiency.

양자 폭포 레이저 흡수 분광법을 이용한 다중 선강도를 갖는 NO & NO₂ 가스 농도 계측에 관한 연구

맹새롬(Saerom Maeng),소성현(Sunghyun So),유미연(Miyeon Yoo),김대해(Daehae Kim),황정호(Jungho Hwang),이창엽(Changyeop Lee) 한국에너지기후변화학회 2018 에너지기후변화학회지 Vol.13 No.1

As the interest in ultrafine particle increases, researches on the mechanism of the secondary fine particle, which is generated by chemical reaction with other materials in the air, are active. Most of secondary fine particles are produced by the main generation mechanism with nitrogen oxides (NOx, NO & NO₂). The NOx is generated by energy and power plant systems in our surrounding such as vehicle, exhaust, power plant, and incineration plant, etc.. Normally, NOx is measured by the chemiluminescent method specified by clean air conservation act. However, this method can measure not each molecule such as NO, NO₂ but total NOx only. Therefore, for analyzing reaction accurately, both NO and NO₂ must be analyzed in real time, and the absence of such technology is the one of the reasons that has a limitation of the secondary fine particle generation mechanism analysis. In this paper, NO and NO₂ gas concentrations have been measured separately with multi-line strength absorptions using quantum cascade laser (QCL) in the mid-infrared region. At this time, The center wavelengths of the lasers used are 1851 cm<SUP>-1</SUP>(NO gas) and 1612 cm-1 (NO₂ gas).