• 한국수소및신에너지학회논문집
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• 제31권6호
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• pp.614-621
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• 2020

Recently, as the fine dust is increased and the emission regulations of diesel engines are strengthened, interest in diesel soot filtration devices is rapidly increased. In particular, there is a demand for technology development for higher efficiency of diesel exhaust gas after-treatment devices. As part of this, many studies conducted to increase the exhaust gas treatment efficiency by improving the flow uniformity of the exhaust gas in the DPF and reducing the pressure drop between the inlet and outlet of disel particle filter (DPF). In this study, computational fluid dynamics (CFD) simulation was performed when exhaust gas flows into the canning reduction device equipped with a 13" asymmetric DPF in order to maintain the flow uniformity in the diesel exhaust system and reduce the pressure. In particular, a study was conducted to find the geometry with the smallest pressure drop and the highest flow uniformity by simulating the DPF I/O ratio, exhaust gas temperature, inlet-outlet pressure and flow uniformity according to the geometry and hole size of distributor.

• 방사성폐기물학회지
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• 제2권3호
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• pp.201-209
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• 2004

파일럿 규모의 유리화플랜트에서 일련의 시험을 통해 고온 세라믹 캔들 필터 시스템의 주요 운전 변수 및 성능을 평가하였다. 실증 시험결과 매 시험초기에는 필터 표면 먼지층(Dust cake)의 생성으로 인해 필터 매질에 걸리는 차압이 급격히 상승하였다. 그런 다음 차압은 곧 일정한 범위에서 안정되었고, 표면유속(Face velocity)에 비례하여 계속적으로 변화하였다. 이와 반대로, 필터 투과율(Permeability)은 매시험 초기에 급격히 감소하였다. 필터표면 먼지의 역세정은 공기압 3～5 bar범위 일때 효율적이었다. 필터 입구 및 출구에서 동시에 등속으로 채취한 먼지농도를 바탕으로 필터의 먼지 포집율(Dust collection efficiency)을 평가한 결과 필터 성능은 설계값인 99.9%과 같은 것으로 나타났다. 100시간의 장기시험을 포함한 일련의 실증시험을 수행하는 동안 고온 필터 시스템의 성능에 영향을 주는 특별한 문제점은 발견되지 않았다.

• Journal of Advanced Marine Engineering and Technology
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• 제34권3호
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• pp.360-368
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• 2010

A SCR catalytic filter system is used for reducing $NO_x$ and soot emissions simultaneously from diesel combustors. The amount of ammonia (as a reducing agent) must be controlled with the amount of $NO_x$ to obtain an optimal $NO_x$ conversion. Hence, gas mixing between ammonia and exhaust gases is vital to ensure that the SCR catalyst is optimally used. If ammonia mass distribution is not uniform, slip potential will occur in rich concentration areas. At lean areas, on the other hand, the catalyst is not fully active. The better mixing is indicated by the higher uniformity of ammonia mass distribution which is necessary to be considered in SCR catalytic filter system. The ammonia mass distributions are depended on the flow field of fluids. In this study, the velocity field of gaseous flow is investigated to characterize the transport of ammonia in SCR catalytic filter system. The influence of different injection placements on the ammonia mass distribution is also discussed. The results show that the ammonia mass distribution is more uniform for the injector directed radially perpendicular to the main flow of inlet at the gravitational direction than that at the side wall for both laminar (Re = 640) and turbulent flows (Re = 4255). It is also found that the mixing index decreases as increasing the heating temperature in the case of ammonia injected at the side wall.

• 한국연소학회지
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• 제8권1호
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• pp.9-16
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• 2003

Carbon soot emission from combustion processes, especially from diesel engines, is a subject of growing concern since soot is known to seriously affect human health. Efforts have been made to oxidize soot particles utilizing Non-Thermal Plasma(NTP) techniques. When oxygen is carried into a plasma device, electrons generated by the plasma dissociate the oxygen, resulting in the formation of oxygen atoms. These highly activated atoms, called O radicals, are known as strong oxidizing agent. This paper presents concentration variations of CO and $CO_2$ at the exit of the plasma device, resulting from the soot oxidation by O radicals, with variations of inlet oxygen concentration, gas temperature, and gas flow rate. Based on the data, Arrehenious rate constants of reactions between C(s)+O and C(s)+O+O were proposed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1998년도 제13차 학술회의논문집
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• pp.468-473
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• 1998

A mathematical model was developed for a continuous re-actor in which free radical polymerization of methyl methacrylate (MMA) occurred. Elementary reactions considered in this study were initiation, propagation, termination, and chain transfers to monomer and solvent. The reactor model took into account the density change of the reactor contents and the gel effect. A control system was designed for a continuous reactor using extended Kalman filter (EKF) based non-linear model predictive controller (NLMPC) to control the conversion and the weight average molecular weight of the polymer product. Control input variables were the jacket inlet temperature and the feed flow rate. For the purpose of validation of the control strategy, on-line digital control experiments were conducted with densitometer and viscometer for the measurement of the polymer properties. Despite the com-plex and nonlinear features of the polymerization reaction system, the EKF based NLMPC performed quite satisfactorily for the property control of the continuous polymerization reactor.

• 해양환경안전학회지
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• 제28권6호
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• pp.1092-1099
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• 2022

대기오염물질과 온실가스 배출량을 저감 시키기 위한 배기 후처리 장치에 대한 연구는 활발히 진행 중이지만 그 중 선박용 입자상물질/질소산화물(PM/NOx) 동시저감 장치에서는 엔진에 미치는 배압 및 필터 담체 교체에 대한 문제가 발생하고 있다. 본 연구에서는 PM/NOx를 동시저감 할 수 있는 일체형 장치의 최적 설계를 위해 장치 내부 유동과 입·출구 압력을 통한 배압의 변화를 연구하여 적절한 기준을 제시하였다. Ansys Fluent를 활용하여 디젤미립자필터(DPF) 및 선택적촉매환원법(SCR)에 다공성 매체 조건을 적용하였고 공극률은 30 %, 40 %, 50 %, 60 % 및 70 %로 설정하였다. 또한, 엔진 부하에 따른 Inlet 속도를 경계 조건으로 7.4 m/s, 10.3 m/s, 13.1 m/s 및 26.2 m/s로 적용하여 배압에 미치는 영향을 분석하였다. CFD 분석 결과, 장치의 입구 온도 보다 입구 속도에 따른 배압의 변화율이 크고 최대 변화율은 27.4 mbar였다. 그리고 모든 경계 조건에서의 배압이 선급 기준인 68 mbar를 초과하지 않았기 때문에 1800 kW 선박에 적합한 장치로 평가되었다.

• 청정기술
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• 제26권1호
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• pp.22-29
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• 2020

최근 미세먼지 증가로 인하여 디젤엔진의 배출 규제가 강화됨에 따라 디젤 매연여과장치에 관심이 급증하게 되었으며, 특히 디젤 배기가스 후처리 장치의 고효율화에 대한 기술개발이 더욱 요구되고 있다. 이에 대한 일환으로서 디젤매연여과장치(diesel particulate filter, DPF) 내 배기가스의 유동 균일도를 향상시키고 배압을 낮추어서 배기가스처리 효율을 높이는 연구가 많이 되고 있다. 본 연구에서는 ANSYS Fluent를 이용하여 직경 12"의 DPF와 디젤산화촉매(diesel oxidation catalyst, DOC)를 장착한 디젤 매연여과장치에서의 배기가스의 유속과 온도, DPF IO ratio, Ash와 PM양에 따른 배압에 미치는 영향을 시뮬레이션 하여 배압을 낮추는 최적화 연구를 하였다. 결과로서 배기가스의 온도와 유속이 낮을수록 배압이 낮아졌으며, PM양이 Ash양보다 배압에 더 큰 영향을 주는 것으로 나타냈다. 또한 비대칭 DPF가 대칭 DPF에 비해 배압이 더 낮게 나타냈으나, 유동 균일도의 경우는 다양한 변수에 관계없이 일정하게 나타냈다. european stationary cycle (ESC), european transient cycle (ETC) 조건에서 PM의 정화효율은 비대칭, 대칭 DPF 관계없이 유사하나, particle number (PN)의 정화효율에서는 비대칭 DPF가 대칭 DPF에 비해 높게 나타냈다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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• pp.62-67
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• 2009

This paper describes the characteristics of scroll type stirling engine receiver. Scroll type stirling engine operated scroll compressor and expander instead of piston. Pass dimension of the receiver was $14(W){\times}14(H)$ mm and total pass length was 5,049 mm. External dimension of the receiver was $300{\times}300mm$. The experimental facility consisted of parabolic dish concentrator, compressor to supply air, triplex air filter, and flowmeter. In this study, basic experimental conditions were set at a inlet pressure of 5 bar and volume flow rate of $25m^3/hr$. As a result, air temperature in receiver at each measuring position of point 1, 2, 3 were $241^{\circ}C$, $465^{\circ}C$, and $542^{\circ}C$ respectively at inlet pressure of 5.5 bar and volume flow rate of $24.6m^3/hr$. As DNI increasing, heat transfer coefficient of the receiver changed from $695W/m^2K$ to $827W/m^2K$. Average heat transfer coefficient of receiver in the experiment was $798W/m^2K$. In addition, receiver efficiency became about 83%.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1146-1151
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• 2004

Measurements of OH chemiluminescence in an atmospheric pressure, laboratory-scale dump combustor at equivalence ratios ranging from 0.63 to 0.89 were reported. The signal from the first electronically excited state of OH to ground state was detected through a band-pass filter with an ICCD. The objectives of this study are two: One is to see the effects of equivalence ratio on global heat release rate and local Rayleigh index distribution. To get the local Rayleigh index distribution, the line-of-sight images were inverted by tomographic method, such as Abel de-convolution. Another aim is to investigate the validity of using OH chemiluminescence acquired with an ICCD as a qualitative measure of local heat release. For constant inlet velocity and temperature, the overall intensities of OH emission acquired at different equivalence ratio showed periodic and higher value at high equivalence ratio. OH intensity averaged over one period of pressure increased exponentially with equivalence ratio. Local Rayleigh index distribution clearly showed the region of amplifying or damping the combustion instability as equivalence ratio increased. It could provide an information/insights on active control such as secondary fuel injection. Finally, local heat release rate derived from reconstructed OH images were presented for typical locations.

• Journal of Korean Society for Atmospheric Environment
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• 제18권E3호
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• pp.165-174
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• 2002

A dual -column biofilter system with two different composts was used to investigate the macro-kinetics of dim-ethyl disulfide (DMDS) degradation. The biofilter columns were filled with compost mixtures up to one meter, The gas How rate and DMDS concentration to the biofilters were varied to study their effect on the removal characteris-tics of DMDS. It was found that the biodegradation of DMDS was governed by zero-order reaction -limited macro-kinetics for inlet DMDS concentrations between 10 and 55 ppmv. The overall average zero-order kinetic coeffi-cient for DMDS removal by compost was 0.50 ($\pm$0.1) ppm/sec for both compost mixtures studied. Variations in individual kinetic coefficients were observed due to varying environmental conditions, such as pH and temperature. The kinetic coefficients determined are specific to the system discussed in this work. During high acidity conditions in the filter beds, methyl mercaptan (MM) was observed in the gas samples collected. Appearance of MM was pro-bably due to decreased microbial activity in the lower portions of the biofilter. Considering the neutral pH range required and the presence of methyl mercaptan, it is likely that the microorganisms present in the biofilters used in this research are similar to the T. thioparus (strain E6) species.