http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
선박용 디젤엔진의 미세먼지저감 장치에 다공판과 믹서의 장착이 미치는 영향에 대한 수치해석적 연구
윤병규,조상현,류영현 해양환경안전학회 2019 해양환경안전학회지 Vol.25 No.7
본 논문에서는 선박용 디젤엔진의 미세먼지저감 장치에 장착된 다공판 및 믹서의 형상과 배치에 따른 압력강하와 유동균일도 특성에 대한 연구를 진행하였다. 미세먼지저감 장치에 장착된 다공판 및 믹서는 미세먼지저감 장치 내의 배출가스 및 산화/환원제의 유동균일도를 높여 배출가스 저감 성능을 높이는 긍정적인 효과와 함께 시스템의 배압을 상승시키는 부정적인 효과도 동시에 지니고 있다. 본 연구에서는 5개의 다공판, 1개의 믹서를 Case 별로 조합하여 6개의 사양에 대해서 유동해석을 통해 각각 유동균일도 및 압력 강하를 계산하였으며, 최적의 다공판 및 믹서의 형상과 배치를 선정하였다. This study presents the characteristics of a pressure drop and uniformity index for a particulate matter reduction device with a perforated plate and mixer for marine diesel engines. The perforated plate and mixer equipped on the particulate matter reduction device induce an increase of exhaust gas reduction performance by increasing the uniformity index. Whereas, the perforated plate induces pressure drop increases in the particulate matter reduction device. Therefore to calculate the effect of the uniformity index and pressure drop of the perforated plates and mixer, this study combines several cases using five types of perforated plates and one type of mixer. Consequently, these results were analyzed to determine the optimized type and position of the perforated plate and mixer.
CFD 를 이용한 PZEV 대응 배기 매니폴드의 유동 해석에 관한 연구
김대우(Daewoo Kim),곽호철(Hochul Kwak),박심수(Simsoo Park) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
As the current and future emission regulations become stringent, the research of exhaust manifold and CCC has been the subject of increasing interest and attention. This study is concerned with the systematic approach to improve catalyst flow uniformity and light-off behavior through the basic understanding of exhaust flow characteristics. Computational approach to the unsteady compressible flow for exhaust manifold of conventional cast type, stainless steel bending type and modified bending type and 900 cell CCC system of a 4-cylinder DOHC gasoline engine for PZEV was performed to investigate the flow distribution of exhaust gases. In this study, through calculation, the effects of geometric configuration of exhaust manifold on flow structure and its maldistribution in monolith were mainly investigated to understand the exhaust flow patterns in terms of flow uniformity. Based on the design guidance resulting from this fundamental study, the flow uniformity of stainless steel bending type and modified bending type exhaust manifold was compared with that of the cast type one.
비정상상태 유동해석을 이용한 산소센서 위치선정 및 유동균일도에 관한 연구
최지호(Jiho Choi),김충식(Choongsik Kim),소유미(Yumi So) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Catalyst reduces engine emissions of unburned hydrocarbons, carbon monoxide, and oxides of nitrogen when the engine is operated very close to the stoichiometric air-fuel ratio. Engine operating air-fuel ratio is maintained close to stoichiometric through the use of an oxygen sensor which provides a voltage signal dependent on the oxygen concentration in the exhaust gas stream. To maximize this function of the oxygen sensor, it is important to locate the sensor on the optimized position which the exhaust gas flow from each cylinder of the engine go through. It takes much time and money to find the optimized position by the engine test because it's difficult to judge which cylinders the sensor signals are from and how the mixed fractions are. This study introduces the technique of the placement optimization of the oxygen sensor by using the 3D CFD unsteady state simulation. Also uniformity index on the substrate cross section is predicted under steady state and unsteady state flow conditions respectively.
열선유속계와 동적배기유동모사장치를 이용한 배기계 유동 및 유동균일도 해석에 관한 연구
전대일(Daeil Jeon),이강영(Gangyung Lee),황인구(In Goo Hwang),박심수(Simsoo Park) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
The CCC (Closed-coupled Catalyst Converter) is important for emission regulations that become stringent, and its distribution has an effect on that. The CCC manifold has complex flow caused by the pulsating flows that are emitted by the exhaust ports. It makes the flow distribution is not uniform. To improve the ability and durability of catalyst, the flow distribution has to be uniform. So measurement of flow distribution is needed. It can be done with computational fluid dynamics. However, such simulations must be verified with experimental data. In this study, conventional manifold of a 4-cylinder engine (with 900 cell CCC system) was performed to investigate the flow characteristic and distribution of exhaust gas. The flow velocity was measured using simulated dynamic flow bench and hot-wire anemometer. The effect of different exhaust ports opening and closing was determined by comparing the flow characteristics.
기상 환원제를 사용하는 선택적 환원촉매에서 유동혼합 개선에 관한 연구
고상철(S.C. Ko),이범호(B.H. Lee),조승환(S.H. Cho),이상헌(S.H. Lee),홍성태(S.T. Hong),이대엽(D.Y. Lee) 한국전산유체공학회 2010 한국전산유체공학회지 Vol.15 No.1
Since emission regulations for vehicles have become more stringent, SCR technology has drawn a strong attention in order to reduce NOx emissions. Optimal design of a reductant injection nozzle and a multi-hole plate located between the cone and catalyst is critical in that the uniform distribution of reductant is necessary to maximize the NOx conversion efficiency and minimize the slip of reductant in SCR. In this work, an LPG fuel(C3H8 in vapor state) was used as a reductant for LPG vehicles. A Realizable k-ε model is used for turbulence, and SCR body is defined as porous media with inertia and viscous resistances measured in this work. Effect of the number of nozzle holes on the flow mixing index was analyzed, which revealed that a four hole nozzle shows the best performance in terms of uniformity of flow. An installment of a multi-hole plate at the entrance of catalyst was evaluated with flow mixing index, uniformity of flow, and pressure drop. A multi-hole plate with gradual hole diameter change in three steps showed the best uniformity of flow within the conditions suggested in this work.
급가감속 운전에 따른 듀얼 모노리스형 촉매변환기 내의 유동 균일도와 압력 강하에 관한 연구
김영득(Young-Deuk Kim),정수진(Soo-Jin Jeong),김우승(Woo-Seung Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Conversion efficiency, durability and pressure drop of automotive exhaust catalysts are dependent on the flow distribution within the substrate. Conventional porous medium approach assuming monolith resistance based on one-dimensional laminar flow for simulating the flow through automotive exhaust catalysts overpredicts the flow uniformity in the monolith. In this study, additional pressure loss accounting for entrance effects due to oblique flow incident on the front face of monolith as a consequence of flow separation and recirculation within the diffuser is considered and incorporation of an additional pressure loss improves the predictions for the maximum flow velocity within the substrate. A numerical study of three-dimensional unsteady incompressible non-reacting flow inside various dual-monolith catalytic converters for the rapid acceleration/deceleration driving has also been conducted.
촉매삽입형 Urea-SCR 머플러 다공튜브 형상변화에 따른 NOx 저감 특성에 관한 연구
문남수(Namsoo Moon),이상규(Sangkyoo Lee),고상철(Sangchul Ko),이지근(Jeekeun Lee) 대한기계학회 2014 大韓機械學會論文集B Vol.38 No.12
Urea-SCR 머플러 시스템 입구와 촉매 전단에 설치된 다공튜브는 우레아 수용액 분무의 균일분포, SCR 촉매 활용도 증대 및 암모니아 슬립을 방지하기 위해 사용되고 있다. 다공튜브의 오리피스 면적비 변화가 머플러 챔버 내부유동 특성에 끼치는 영향이 상용 소프트웨어를 이용하여 해석적으로 조사되었다. 다공튜브 오리피스 면적비 변화는 촉매 전단에 설치된 챔버 내부의 벌크 선회유동 형성과 촉매전단 속도분포의 균일도 지수에 큰 영향을 끼침을 보였다. 해석결과를 검증하기 위해 엔진실험이 ESC 및 ETC 모드에서 수행되었다. 엔진 실험결과 다공튜브 길이방향으로 보다 많은 유량이 흐르는 모델이 가장 높은 NOx 저감 효율을 나타냈으며, 이것은 높은 균일도지수 및 강한 선회유동을 나타내는 해석 결과와 일치됨을 알 수 있었다. A multi-perforated tube is generally installed between the muffler inlet and in front of selective catalytic reduction (SCR) catalysts in the integrated urea-SCR muffler system in order to disperse the urea-water solution spray uniformly and to make better use of the SCR catalyst, which would result in an increase nitrogen oxide (NOx) reduction efficiency and a decrease in the ammonia slip. The effects of the multi-perforated tube orifice area ratios on the internal flow characteristics were investigated analytically by using a general-purpose commercial software package. From the results, it was clarified that the multi-perforated tube geometry sensitively affected the generation of the bulk swirling motion inside the plenum chamber set in front of the SCR catalyst and to the uniformity index of the velocity distribution produced at the inlet of the catalyst. To verify the analytical results, engine tests were carried out in the ESC and ETC modes. Results of these tests indicated that the larger flow model in the longitudinal direction showed the highest NOx reduction efficiency, which was a good agreement with the analytical results.
비정상상태 유동해석을 이용한 Maniverter Design Optimization에 관한 연구
소유미(Yumi So),민선기(Sunki Min),황명진(Myungjin Hwang) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
The catalytic converter reduces the emissions of unburned hydrocarbons, carbon monoxide and oxides of nitrogen. Overall catalytic converter efficiency is influenced by how the flow distributes across the substrate inlet face, even if the inlet gases are well mixed. Highly non-uniform substrate inlet flow may provide incomplete HC, CO, and NOx conversion because the converter chemistry only uses a portion of the available catalyst surface area. Engine operating air-fuel ratio is maintained close to stoichiometric through the use of an oxygen sensor which provides a voltage signal dependent on the oxygen concentration in the exhaust gas stream. So, it’s important to find the optimal oxygen sensor location for the AFIM (airfuel ratio imbalance monitor) system which requires the oxygen sensor to see exhaust gases from cylinder evenly. This study recognizes the dual roles of gas mixing and flow uniformity in determining HC, CO and NOx conversion in the substrate. Also, it predicts the AFIM performance for the specified oxygen sensor type and location using 3D CFD analysis. As a result, this approach is used to optimize the manifold runner and converter inlet design through the analysis.
동적유동모사장치를 이용한 PZEV 기준 대응용 배기계의 유동 분포 측정을 위한 실험적 연구
김인수(Insu Kim),명차리(Cha-Lee Myung),박심수(Simsoo Park),인치범(Chi-Bum In),여권구(Gwon koo Yeo) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
As the current and future automobile emission regulations become stringent, the research of exhaust manifold and CCC has been the interesting and remarkable subject. The design of a CCC manifold is a formidable task due to the complexity of the flow distribution caused by the pulsating flows that are emitted by the exhaust ports. Measurement of flow distribution can be done with computational fluid dynamics (CFD). However, such simulations must be verified with selected experimental data. In this study, conventional casting type and stainless steel bending type of a 4-cylinder engine(with 900 cell CCC system) was performed to investigate the flow distribution of exhaust gases. Pressure was measured using simulated dynamic flow bench and 5-hole pitot probe. And then the flow uniformity of bending type exhaust manifold compared with that of the casting type. Based on the experimental data, this study verified exhaust system optimization for the better use of catalytic converter.