• 제목/요약/키워드: Air injection

검색결과 1,200건 처리시간 0.026초

2차 공기분사 및 냉각수제어에 의한 SI 엔진의 탄화수소 배기저감 (SI Engine Hydrocarbon Emissions Reduction with Secondary Air Injection and Coolant Control)

  • 박기수;조영진;박심수
    • 한국자동차공학회논문집
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    • 제8권4호
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    • pp.51-58
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    • 2000
  • It is well known that the majority of the emissions measured from vehicle exhaust in the US Federal Test Procedure(FTP-75) are emitted during the first 60 seconds. This paper describes an experimental study on SI engine emissions reduction after cold start with interval secondary air injection and coolant control. Secondary air injection after cold start to reduce exhaust emissions causes an exothermic reaction at the exhaust port and gives sufficient air to the catalyst. For that reason engine-out emissions oxidized in the exhaust port and the rapid heating of a catalytic converter after cold start with CSAI and ISAI are estimated. The influence of the coolant temperature on SI engine emissions has been estimated. In the present studycoolant control of the cylinder head tempeature is used to investigate the effect of coolant temperature on SI engine emissions. The results show that engine-out hydrocarbon and carbon monoxide emissions are considerably reduced with interval secondary air injection and coolant control.

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터보과급디젤기관의 급가속 운전시 압축기출구에의 공기분사가 응답성능에 미치는 영향 (The Effects of Air Injection in Compressor Exit on the Response Performance of a Turbocharged Diesel Engine under the Operating Conditions of Rapid Acceleration.)

  • 박상규;최낙정
    • Journal of Advanced Marine Engineering and Technology
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    • 제24권6호
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    • pp.110-119
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    • 2000
  • In this paper, an experimental study is carried out under the operating conditions of low speed and rapid acceleration in order to investigate and improve the response characteristics of a turbocharged diesel engine with radial turbine driven by exhaust gas. A rapid acceleration for investigating the response performance is applied to the fuel-pump rack of the engine from 0-10% to 0-40% in steps of 10%, and accelerating time of 1, 2 and 3 seconds is applied to the engine. Further experiment for improving the low speed torque and acceleration performance is also performed by means of injecting air into the inlet manifold at compressor exit during the period of low speed and application of a rapid acceleration. The effects of air injection on the response performance are represented at subjected engine speed with the changes of response performance factors such as air injection pressure, air injection period, accelerating rate, accelerating time and load. From the experimental results obtained throughout this study, it is shown that air injection into the inlet manifold at compressor exit is closely related to the improvement of low speed and acceleration performance of a turbocharged diesel engine.

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연속식 공기세정 관형막 투과특성 (Permeation Characteristics of the Tubular Membrane with Continuous Air Cleaning System)

  • 박미자;정건용
    • 멤브레인
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    • 제23권2호
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    • pp.185-188
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    • 2013
  • 본 연구는 정밀여과용 관형 분리막 모듈 내에 자체 설계한 기체분사형 노즐을 장착하여 막오염 감소 효과에 따른 투과유속을 측정하였다. 원료 용액으로는 0.1 wt% yeast 입자를 사용하였으며 공기 주입에 따른 막오염 감소 효과를 확인하기 위하여 공기를 주입하지 않은 경우와 주입한 경우의 투과유속을 비교 분석하였다. 공기를 주입하지 않았을 경우 투과유속은 지속적으로 감소하였지만 공기를 주입할 경우 투과유속은 공기를 주입하지 않은 경우와 비교하여 30% 이상 향상됨을 확인하였다.

2단 연소에 의한 NO 배출 저감에 관한 연구 (Reduction of NO Emission by Two-Stage Combustion)

  • 유현석;최정환;오신규
    • 대한기계학회논문집
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    • 제19권2호
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    • pp.591-596
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    • 1995
  • In order to investigate the reduction of NO emissions, natural gas was fueled for two-stage combustion apparatus. NO and CO emissions were described by five variables: total air ratio, primary air ratio, secondary air injection position, secondary air injection velocity, and swirl ratio. It was mainly observed that, as the primary air ratios of 0 and 0.4 NO emission decreased with increasing the secondary air injection position and secondary air injection velocity. The effect of weak swirl on NO emission was found to be insignificant.

공연비 변화가 MILD 연소 특성에 미치는 영향에 관한 해석적 연구 (A numerical study of the air fuel ratio effect on the combustion characteristics in a MILD combustor)

  • 하지수;김태권;심성훈
    • 대한환경공학회지
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    • 제32권6호
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    • pp.587-592
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    • 2010
  • 연소과정 중에 발생하는 질소산화물을 저감하는 기술인 MILD 연소에 대하여 공연비를 변화시키면서 나타나는 연소 특성을 수치해석을 통하여 연구하였다. 작은 크기의 공기분출속도(10 m/s)에서는 공기가 연소로 내 상부영역까지 침투하지 못한다. 반면에 공기분출속도가 30 m/s인 경우에는 공기유동이 연료유동을 억제하고 상부영역까지 흘러간다. 이론공기량에 해당하는 공기분출속도 18 m/s에서는 10 m/s 보다 상대적으로 상부영역까지 침투하였다. 이러한 유동 양상으로 공기분출속도가 작은 10 m/s에서는 연소반응대가 공기노즐 측에 치우쳐 나타나고 30 m/s에서는 연료노즐 측에 형성되었다. 공기분출속도 16, 18, 20 m/s에서는 공기노즐과 연료노즐 중간 영역에서 연소반응대가 형성되었다. 연소로 내 최대온도와 NOx 생성은 공기분출속도가 10 m/s, 30 m/s인 경우 보다 이론공기량이거나 이에 가까운 16, 18, 20 m/s에서 낮게 나타났다. 본 연구로부터 MILD 연소로에서 이론공기량 조건이 NOx를 저감하는 최적의 조건이라는 것을 밝혔다.

압축공기를 사용한 사출성형품의 싱크마크 저감 및 가스 벤팅에 관한 연구 (Study on sink-mark reduction and gas venting of injection molded parts using compressed air)

  • 이세호;이호상
    • Design & Manufacturing
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    • 제18권3호
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    • pp.71-80
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    • 2024
  • Sink marks are a common defect that occurs due to differences in shrinkage in areas with significant thickness variations in injection-molded parts. In this paper, we investigated the reduction of sink marks and the improvement of gas venting in injection molding processes using External Gas Injection (EGI). A mold was designed with considerations for EGI core pins, O-ring grooves to prevent gas leakage, and ejector-pin sealing. The sink marks were then examined through a series of experiments. When the delay time for injecting compressed air was set to 2.2 seconds, the depth of the sink marks was minimized. However, when the delay time was either too short or too long, the depth of the sink marks increased. There was almost no difference in the depth of the sink marks at discharge pressures of 30 and 50 bar of compressed air, but the sink marks were significantly reduced at a discharge pressure of 70 bar. Under the conditions of a 2.2-second delay time and a supply pressure of 70 bar, the smallest depth, 0.594 ㎛, was observed when the supply time was between 6 and 7 seconds. This represents a reduction of approximately 94% compared to the sink mark depth of 10.078 ㎛ observed with conventional injection molding. To verify the gas venting effect of compressed air injection, an experiment was conducted using non-dried PC. The silver streaks that appeared on the exterior of the molded part were completely eliminated when the air supply pressure was set to 20 bar. This indicates that by injecting compressed air into the mold cavity before injecting the resin, the appearance quality of the injection-molded part can be improved without the need to dry the resin in advance.

경막외강 스테로이드 주입 시 발생한 기뇌증 -증례 보고- (Pneumocephalus after Epidural Steroid Injection -A case report-)

  • 정성규;박경희
    • The Korean Journal of Pain
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    • 제14권2호
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    • pp.276-279
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    • 2001
  • Epidural steroid injection is one method of releiving chronic back pain. However, problems with the loss of resistance to air technique include the possible subarachnoid or subdural injection of air resulting in headache, venous air embolism, and the introduction of air bubbles into the epidural space. Pneumocephalus is a rare complication of epidural block for epidural steroid injection. We report a case of a 58-year-old woman who developed a severe headache and posterior nuchal pain with incomplete oculomotor palsy due to pneumocephalus occuring after an epidural steroid injection.

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액분사 사이클을 이용한 공기 열원 열펌프의 사이클 시뮬레이션 (Cycle Simulation of an Air Source Heat Pump Using Liquid Injection)

  • 김욱중;홍용주;남임우;강원일;공용상
    • 설비공학논문집
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    • 제12권3호
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    • pp.244-250
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    • 2000
  • An air source heat pump using liquid injection technique, which can be applied for very low temperature climate, has been simulated to examine the design options. Comparison between the simulation and experiment has been carried out to validate the simulation method. Effects of various design parameters such as liquid injection rate and injection pressure are Investigated to optimize the performance of the heat pump. Finally, optimal liquid infection rate and injection pressure to maintain sufficient heating capacity and moderate discharge refrigerant temperature are suggested when the heat pump was operated at very low outdoor temperature.

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촉매가 장착된 가솔린엔진에서 동기화된 2차공기분사에 의한 배기 탄화수소 저감 (Reducing Exhaust Hydrocarbon at Gasoline Engine with Catalytic Converter using Synchronized Secondary Air Injection)

  • 심현성;민경덕;정석호
    • 한국자동차공학회논문집
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    • 제9권2호
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    • pp.67-74
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    • 2001
  • A synchronized secondaty air injection method has been developed to hydrocarbon emission by injecting secondary air intermittently into exhaust port. The method has been tested in a single cylinder spark-ignition engine operating at cold-steady / cold-start conditions. Effects of air injection timing, intake pressure and engine air-fuel ratio have been investigated at cold-steady condition. Also, hydrocarbon emission and exhaust gas temperature with catalytic conberter are compared with a continuous SAI method and base condition at cold-start condition. Resules show that hydrocarbon reduction rate and exhaust gas temperature are sensitive to the timing of synchronized SAI. At cold-steady condition, HC emission is minimum at engine air-fuel ratio of 10. At cold-start condition, the accumulated hydrocarbon emission during the first 120 s decreases about 56% and 22% with the synchronized and continuous SAI, respectively, compared to that of base condition.

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Numerical Simulation Study on Combustion Characteristics of Hypersonic Model SCRamjet Combustor

  • Won, Su-Hee;Eunju Jeong;Jeung, In-Seuck;Park, Jeong-Yeol
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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    • pp.42-47
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    • 2004
  • Air-fuel mixing and flame-holding are two important factors that have to be considered in the design of an injection system. Different injection strategies have been proposed with particular concern for rapid air-fuel mixing and flame-holding. Two representative injection techniques can be applied in a supersonic combustor. One of the simplest approaches is a transverse(normal) injection. The cavity flame holder, an integrated fuel injection/flame-holding approach, has been proposed as a new concept for flame holding and air-fuel mixing in a supersonic combustor. This paper describes numerical efforts to characterize the flame-holding and air-fuel mixing process of a model scramjet engine combustor, where hydrogen is injected into a supersonic cross flow and a cavity. The combustion phenomena in a model scramjet engine, which has been experimentally studied at University of Queensland and Australian National University using a free-piston shock tunnel, were observed around the separation region of the transverse injector upstream and the inside cavity. The results show that this flow separation generates recirculation regions which increase air-fuel mixing. Self-ignition occurs in the separation-freestream and cavity-fteestream interfaces.

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