http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
금속폼을 이용한 Partial DPF의 설계 및 전산유체해석 연구
윤천석(Cheon Seog Yoon),조규백(Gyubaek Cho) 한국자동차공학회 2009 한국 자동차공학회논문집 Vol.17 No.1
DPF(Diesel Particulate Filter)s have been used to reduce the most of PM(particulate matters) from the exhaust emissions of diesel engine vehicles. Metal foam is one of promising materials for the DPFs due to its cost effectiveness, good thermal conductivity and high mechanical strength. It can be fabricated with various pore sizes and struct thickness and coated with catalytic washcoats with low cost. In order to design metal foam filter and analyze the flow phenomena, pressure drop and filtration experiment are carried out. Partial DPF which has PM reduction efficiency of more than 50 % is designed in this paper. Also, CFD analysis are performed for different configurations of clean filters in terms of pressure drop, uniformity index, and velocity magnitude at face of filter. Filter thickness and the gap between front and rear filters are optimized and recommended for manufacturing purpose.
인터쿨러용 판형열교환기 내부유로의 유동현상에 관한 전산유체해석
윤천석(Cheon Seog Yoon),한승한(Seunghan Han) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Plate heat exchangers (PHE) have been widely used in different industrial applications, because of high heat transfer efficiency per unit volume. Basic study is performed for the feasibility of PHE to intercooler in automotive. In order to understand the flow phenomena in the plate heat exchanger, a channel which was formed by the upper and lower plate in single plate was considered as calculation domains. Because chevrons attached on the upper plate are brazed with chevrons attached on the lower plate. the flow channel has very complex configuration. This complex geometry was analyzed by Fluent which is general CFD (computational fluid dynamics) S/W. To validate this methodology the proper experimental and theoretical data are collected and compared with numerical results. Finally, due to the lack of experimental values for PHE to intercooler, various chevron angles and air velocities at inlet were tested in terms of physical phenomena. From this point of view, results of velocity vector path lines, static pressure, heat flux. heat transfer coefficient, and Nusselt number are physically reasonable and accepted for the solutions. Thus, the methodology of the flow analysis in the full geometry of the channel was established for the predictions of performance in plate heat exchanger.<br/>
Bench-Flow Reactor System을 이용한 Lean NOx Trap 촉매의 특성 연구
윤천석(Cheon Seog Yoon),김학용(Hakyong Kim),Ke Nguyen 한국자동차공학회 2008 한국 자동차공학회논문집 Vol.16 No.5
The performance of Lean NOx Trap (LNT) based on the catalysts of Pt/K/Ba/γ-Al₂O₃ with proprietary wash coat formulation is studied using a bench flow reactor system. To investigate the effect of temperature and gas hourly space velocity (GHSV) on the nitrogen oxides (NOx) trapping capacity as well as NOx breakthrough time and final ratio of NO₂ to NO of LNT, series of adsorption isotherms are carried out with simulated exhaust gases of the lean burn engines. Since typical operation of LNT requires periodic regeneration with a short rich excursion, where the stored or trapped NOx is released and subsequently reduced to N₂, the effect of the duration of lean and rich phase and type of reductants on the NOx conversion is investigated. NOx storage capacity and breakthrough time obtained from adsorption isotherms shows a volcano-type dependence on the temperature with a maximum NOx storage capacity occurring 350℃ and with a maximum breakthrough time occurring 400℃ at all GHSVs investigated in this study. Also, maximum ratio of NO₂ to NO is obtained at 400℃ with a GHSV of 75,000 hr?¹. Lean/rich cycle of 100 s lean and 5 s rich used with a concentration of 1.33% of H₂ and 4% of CO in the rich phase is found to be optimum at operating temperature of 350℃ and a GHSV of 50,000 hr?¹.
인터쿨러용 판형열교환기 내부유로의 유동현상에 관한 전산유체해석
윤천석(Cheon Seog Yoon),한승한(Seunghan Han) 한국자동차공학회 2004 한국 자동차공학회논문집 Vol.12 No.2
Plate heat exchangers (PHE) have been widely used in different industrial applications, because of high heat transfer efficiency per unit volume. Basic study is performed for PHE to the application of intercooler in automobile. In order to understand the flow phenomena in the plate heat exchanger, a channel which was formed by the upper and lower plate in single plate was considered as calculation domains. Because chevrons attached on the upper plate are brazed with chevrons attached on the lower plate, the flow channel has very complex configuration. This complex geometry was analyzed by Fluent. In order to validate this methodology the proper experimental and theoretical data are collected and compared with numerical results. Finally, due to the lack of experimental values for PHE to the application of intercooler, various chevron angles and air velocities at inlet were tested in terms of physical phenomena. From this point of view, results of velocity vector, path lines, static pressure, heat flux, heat transfer coefficient, and Nusselt number are physically reasonable and accepted for the solutions. From these results, the correlations for pressure drop and Nusselt number with respect to chevron angle and Reynolds number in specific PHE are obtained for the design purpose. Thus, the methodology of the flow analysis in the full geometry of the channel was established for the predictions of performance in plate heat exchanger.
디젤엔진 배출가스의 질소산화물 저감을 위한 Solid SCR용 가스분사 시스템의 전산유체해석 연구
이호열(Hoyeol Lee),윤천석(Cheon Seog Yoon),김홍석(Hongsuk Kim) 한국자동차공학회 2014 한국 자동차공학회논문집 Vol.22 No.5
CFD(computational fluid dynamics) model is developed to simulate direct injection of ammonia gas phase from ammonia transporting materials into the SCR catalyst in the exhaust pipe of the engine with solid SCR. Configurations of one-hole and four-hole nozzle, circumferential type, porous tube type, and the effect of mixer configurations which commonly used in liquid injection of AdBlue are considered for complex geometries. Mal-distribution index related to concentration of ammonia gas, flow uniformity index related to velocity distribution, and pressure drop related to flow resistance are compared for different configurations of complex geometries at the front section of SCR catalyst. These results are used to design the injection system of ammonia gas phase for solid SCR of target vehicle.
Solid SCR용 암모니아 저장물질인 Calcium Ammine Chloride의 합성방법 및 물질분석 연구
신종국(Jong Kook Shin),윤천석(Cheon Seog Yoon),김홍석(Hongsuk Kim) 한국자동차공학회 2015 한국 자동차공학회논문집 Vol.23 No.2
Solid materials of ammonia sources with SCR have been considered for the application of lean NOx reduction in automobile industry, to overcome complex problems of liquid urea based SCR. These solid materials produce ammonia gas directly with proper heating and can be packaged by compact size, because of high volumetric ammonia density. Among ammonium salts and metal ammine chlorides, calcium ammine chloride was focused on this paper due to low decomposition temperature. In order to make calcium ammine chloride in lab-scale, simple reactor and glove box was designed and built with ammonium gas tank, regulator, and sensors. Basic test conditions of charging ammonia gas to anhydrous calcium chloride are chosen from equilibrium vapor pressure by Van’t Hoff plot based on thermodynamic properties of materials. Synthetic method of calcium ammine chloride were studied for different durations, temperatures, and pressures with proper ammonia gas charged, as a respect of ammonia gas adsorption rate(%) from simple weight calculations which were confirmed by IC. Also, lab-made calcium ammine chloride were analyzed by TGA and DSC to clarify decomposition step in the equations of chemical reaction. To understand material characteristics for lab-made calcium ammine chloride, DA, XRD and FT-IR analysis were performed with published data of literature. From analytical results, water content in lab-made calcium ammine chloride can be discovered and new test procedures of water removal were proposed.
디젤엔진 배출가스 질소산화물 저감을 위한 Solid SCR의 반응률에 관한 연구
이호열(Hoyeol Lee),윤천석(Cheon Seog Yoon),김홍석(Hongsuk Kim) 한국자동차공학회 2013 한국 자동차공학회논문집 Vol.21 No.6
Liquid urea based SCR has been used in the market to reduce NOx in the exhaust emission of the diesel engine vehicle. This system has several problems at low temperature, which are freezing below -12°C, solid deposit formation in the exhaust, and difficulties in dosing system at exhaust temperature below 200°C. Also, it is required complicated exhaust packaging equipment and mixer due to supply uniform ammonia concentration. In order to solve these issues, solid urea, ammonium carbonate, and ammonium carbamate are selected as ammonia sources for the application of solid SCR. In this paper, basic research on reaction rate of three ammonia-transporting materials was performed. TGA (Thermogravimetric Analysis) and DTA (Differential Thermal Analysis) tests for these materials are carried out for various heating conditions. From the results, chemical kinetic parameters such as activation energy and frequency factor are obtained from the Arrhenius plot. Additionally, from test results of DSC (Differential Scanning Calorimeter) for these materials, chemical kinetic parameters using the Kissinger method are calculated. Activation energies of solid SCR from this experiment are compared with proper data of literature study, then obtained data of this experiment are used for the design of reactor and dosing system for candidate vehicle.