• 제목/요약/키워드: Recirculation system

검색결과 419건 처리시간 0.022초

상용 디젤엔진의 저압 순환 EGR 추가에 대한 성능 평가 (Performance Evaluation on the Addition of Low-pressure Loop EGR in a Commercial Diesel Engine)

  • 왕태중;이종윤;심의준;김득상;이동인
    • 한국자동차공학회논문집
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    • 제19권2호
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    • pp.105-110
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    • 2011
  • Through this study, the performance evaluation on the addition of low-pressure loop EGR(Exhaust Gas Recirculation) in a 6.0 L commercial diesel engine was carried out using WAVE modeling and simulation. Since the key technology of advanced diesel engine combustion such as low-temperature combustion is to steadily supply high rates of EGR in a wide operating range, the current study could be effectively contribute to the design and development processes of up-to-date diesel engine systems as real-world reference data. The current simulation results show that the system in which low-pressure loop EGR is added shows almost 2.3 times increase in maximum EGR rate at 1000 rpm as well as almost 1.6 times increase at 2200 and 1600 rpm in comparison with an engine system employing high-pressure loop EGR only. Also, both turbocharger axis speed and charging pressure level did not deteriorate due to the addition of low-pressure loop EGR at 2200 and 1000 rpm, but they were fairly decreased at 1600 rpm.

셀 입구 예열방법에 따른 가압형 고체산화물 연료전지/가스터빈 하이브리드 시스템의 성능 비교 해석 (Comparative Performance Analysis of Pressurized Solid Oxide Fuel Cell / Gas Turbine Hybrid Systems Considering Different Cell Inlet Preheating Methods)

  • 양원준;김재환;김동섭
    • 대한기계학회논문집B
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    • 제29권6호
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    • pp.722-729
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    • 2005
  • Design analysis of the solid oxide fuel cell and gas turbine combined power system is performed considering different methods for preheating cell inlet air. The purpose of air preheating is to keep the temperature difference between cell inlet and outlet within a practical design range thus to reduce thermal stress inside the cell. Three different methods considered are (1) adopting a burner in front of the cell, (2) adopting a preheater (heat transfer from the main combustor) in front of the cell and (3) using recirculation of the cathode exit gas. For each configuration, analyses are carried out for two values of allowable maximum cell temperature difference. Performance characteristics of all cases are compared and design limitations are discussed. Relaxation of the cell temperature difference (larger difference) is proved to ensure higher efficiency. Recirculation of the cathode exit gas exhibits better performance than other methods and this advantage becomes more prominent as the constraint of the cell temperature difference becomes more severe (smaller temperature difference).

제트확산염의 고온공기연소특성에 관한 실험적 연구 (An Experimental Study of the Characteristics with High Temperature Air Combustion in Jet Diffusion Flames)

  • 조은성;대야건;소림수소;정석호
    • 한국연소학회:학술대회논문집
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    • 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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    • pp.89-94
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    • 2003
  • For the development of high efficiency and low emission combustion systems, high temperature air combustion technology has been tested by utilizing preheated air over 1100 K and exhaust gas recirculation. In this system, combustion air is diluted with large amount of exhaust gases ($N_2$, $CO_2$), such that the oxygen concentration is relatively low in the reaction zone, leading to low flame temperature. Since, the temperature fluctuations and sound emissions form the flame are small and flame luminosity is low, the combustion mode is expected to be flameless or mild combustion. Experiment was performed to investigate the turbulent flame structure and $NO_X$ emission characteristics in the high temperature air combustion focused on coflowing jet diffusion flames which has a fundamental structure of many practical combustion systems. The effect of turbulence has also been evaluated by installing perforated plate in the oxidizer inlet nozzle. LPG was used as a fuel. Results showed that even though $NO_X$ emission is sensitive to the combustion air temperature, the present high temperature air combustion system produce low $NO_X$ emission because it is operated in low oxygen concentration condition in excess of dilution.

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박판 딤플 성형을 위한 유한요소해석 및 성형성 평가 (Finite Element Analysis and Formability Evaluation for Dimple Forming with Thin Sheet Metal)

  • 허성찬;서영호;구태완;송우진;김정;강범수
    • 소성∙가공
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    • 제16권8호
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    • pp.621-628
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    • 2007
  • Nowadays, Exhaust Gas Recirculation(EGR) Cooler is one of the most favorite systems for reducing the generation amount of $NO_x$ and other particle materials from vehicles burning diesel as fuel. Efficiency of the system is mainly dependent on its heat transfer efficiency and this ability is affected by net heat transferring area of the system. For that reason, several types of heat transfer tube such as dimple, wrinkle and spiral types that have large net area are used. However, it is difficult to manufacture the rectangular tube with dimpled type structure because it experiences too much strain around the rectangular tube surface during the forming process. For that reason, in this study, numerical simulation for forming process of non-symmetric dimple shape on a thin sheet metal was carried out. Furthermore, theoretical forming limit curves(forming limit diagram, forming limit stress diagram) were proposed as criteria of formability evaluation. From the results of finite element simulation in view of stress and strain distribution, it is found that the designed process has robustness and feasibility to safely manufacture the dimpled rectangular tube.

직분식 소형 과급 디젤엔진에서 EGR이 배기배출물에 미치는 영향 (The Effect of EGR on Exhaust Emissions in a Direct Injection Diesel Engine)

  • 장세호;고대권
    • 한국자동차공학회논문집
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    • 제13권5호
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    • pp.188-194
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    • 2005
  • The direct injection diesel engine is one of the most efficient thermal engines. For this reason DI diesel engines are widely used for heavy-duty applications. But the world is faced with very serious problems related to the air pollution due to the exhaust emissions of diesel engine. So, that is air pollution related to exhaust gas resulted from explosive combustion should be improved. Exhaust Gas Recirculation(EGR) is a proven method to reduce NOx emissions. In this study, the experiments were performed at various engine loads while the EGR rates were set from $0\%$ to $30\%.$ The emissions trade-off and combustion of diesel engine are investigated. The brake specific fuel consumption rate is very slightly fluctuated with EGR in the range of experimental conditions. The ignition delay increased with increasing EGR rate. The maximum value of premixed combustion for the rate of heat release is increased with increasing EGR rate. NOx emissions are decreased with increasing EGR rate at high load and high speed. It was found that the exhaust emissions with the EGR system resulted in a very large reduction in oxides of nitrogen at the expense of higher smoke emissions.

가솔린 엔진의 스로틀 밸브 출구에서 유동측정 (Flow Measurements at the Exit of a Throttle Valve in Gasoline Engines)

  • 김성초;김철;최종근;위화복
    • 한국자동차공학회논문집
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    • 제10권2호
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    • pp.1-8
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    • 2002
  • The flow and combustion patterns have been investigated inside the gasoline engine cylinder with the swirl or tumble flow, whereas the air flow characteristics, which are generated in the part of intake system before entering into the intake manifold, have not been known completely. It is necessary to analyze the flow field in the intake system consisting of air rater, throttle valve and intake manifold. The throttle valve, used to control the intake air flow rate, is important because it makes various mass flow rate and flow patterns. Three-dimen-sional How characteristics such as velocities, turbulent intensities and Reynolds shear stresses are measured by the hot wire anemometer at the exit of the throttle valve with the variation in the valve opening angle($15^{\circ}$, $45^{\circ}$, $75^{\circ}$ and $90^{\circ}$) and the Reynolds numbers (45000, 70000 and 140000). There are a lot of changes in flow characteristics at $75^{\circ}$ due to the large recirculation flow comparing with those of the other cases, and the streamwise velocity is especially enforced strongly below the valve shaft. The other component velocities are relatively large near the centerline parallel to the valve shaft. The effects of the Reynolds number on the flow field are not severe.

접선류 막분리 시스템에 의한 이눌린 수용액의 분리 동특성 (Dynamic Characteristics for the Separation of Inulin Solution in Membrane Filtrsition System of Tangential Flow)

  • 허병기;배천순이기정목영일
    • KSBB Journal
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    • 제5권1호
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    • pp.69-74
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    • 1990
  • 이눌린, 물 및 알콜로 구성된 용액에서 물과 알콜의 투과플럭스와 막투과 압력, 이눌린 농도, 재순환속도 사이의 함수관계를 millipore사의 랩카\ulcornerV시스템을 사용하여 구명하여 보았다. 본 연구의 결과에 의하면 NMWL이 1000이고 이눌린 농도가 1wt%내지 5wt%, 막투과 압력이 $0.4kgf/\;{\textrm{cm}^2}$내지 $3.2kgf/\;{\textrm{cm}^2}$, 재순환 속도가 4ml/sec인 경우에는 투과플럭스와 막투과 압력 및 이눌린농도 사이의 함수관계가 다음식으로 표현되는 겔분모델로 잘 해석됨을 알 수 있었다. Jv=(0.0022P + 0.0003) lu \frac{3p\;+\;2.1}{C_b}$

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간접분사식 디젤기관에서 Mono-Ether 계열 함산소연료(Ethylene Glycol Mono-n-Butyl Ether)의 적용에 관한 연구 (A Study on Application of Mono-Ether Group(Ethylene Glycol Mono-n-Butyl Ether) Oxygenated Fuel in an IDI Diesel Engine)

  • 최승훈;오영택
    • 동력기계공학회지
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    • 제9권3호
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    • pp.15-20
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    • 2005
  • In this paper, the effect of oxygen component in fuel on the exhaust emissions has been investigated for an indirect injection diesel engine. It was tested to estimate change of engine performance and exhaust emission characteristics for the commercial diesel fuel and oxygenated blended fuel which has four kinds of mixed ratio. And, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission have been investigated. Ethylene glycol mono-n-butyl ether(EGBE) contains oxygen component 27% in itself, and it is a kind of effective oxygenated fuel of mono-ether group that the smoke emission of EGBE is reduced remarkably compared with commercial diesel fuel, that is, it can supply oxygen component sufficiently at higher loads and speeds in diesel engine. It was found that simultaneous reduction of smoke and NOx was achieved with oxygenated fuel(10vol-%) and cooled EGR method(10%).

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뱀장어(Anguilla japonica) 적정 사육관리를 위한 양식기술 현황 (State of Aquaculture Management for Optimal Rearing of Eel Anguilla japonica)

  • 손맹현;김강웅;김경덕;김신권
    • 한국수산과학회지
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    • 제44권4호
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    • pp.359-365
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    • 2011
  • This study was conducted to investigate the production, elver stocking, rearing facilities and rearing method of eel culture to determine aquaculture management conditions for optimal rearing of eel Anguilla japonica. The production of eel culture was evaluated by the proportion of eels from the main inland fin fish species production in Korea. Elver stocking was assessed by the elver stocking densities of pond and recirculation culture. Rearing facilities were investigated according to the rearing tank size proportion of the pond and recirculation culture. We selected sample farms by region and by size. We visited sample farms and recorded the number of elvers stock for pond area, size of tanks, feed and feed quantity, and the size and number of harvest eels. The production capacity of Jeollanam-do and Jeollabuk-do were 71.9% and 21.3% respectively. This production quantity represented 93.2% of the total Korean eel production quantity. In Jeollanam-do, there are 236 eel farms, 202 pond farms, and 34 recirculation aquaculture facilities. The elvers' first density data by each aquaculture method revealed that elvers' first density varied more in recirculation system farms, as compared to pond aquaculture. In intensive pond farms, the elvers' first density decreased as the size of farm increased. There was a correlation between the size of tank(x) and the facility of a water wheel for dissolved oxygen in pond culture systems(y=0.022x-0.494; $R^2$=0.860). Another strong correlation was found between the weight of eel(x) and eel density(y) in pond culture systems(y=283.5x-0.27; $R^2$=0.992). Finally, there was a strong correlation between the length of eel(x) and the weight of eel(y) in intensive pond culture(y=0.0005x-3.2783; $R^2$=0.9775). The final survival rate did not differ significantly among pond sizes and culture types.

Media를 충전(充塡)한 간접폭기식(間接曝氣式) 침지여상(浸漬濾床)에 의한 BOD제거 특성에 관한 연구 (A Study on the BOD Removal Characteristics of Aerobic Submerged Biofilter)

  • 양상현;권영호
    • 대한토목학회논문집
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    • 제14권3호
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    • pp.669-678
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    • 1994
  • 침지여상에 폐수를 부하하여 간접포기 강제순환 방식으로 처리하는 system에 대하여 그 유기물 제거 특성을 실험적으로 연구했다. 실험은 침지여상에 네트링(random형(型) plastic media), 입체철망(module형(型) plastic media) 및 잔자갈의 특성이 다른 세가지 media를 충전하고, pH, 수온(水溫)을 고정한 상태에서 $BOD_5$ 용적부하와 순화비를 변동하여 실시하므로서 여재(media) 종류가 $BOD_5$ 제거효율에 미치는 특성을 규명했다.

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