• Title/Summary/Keyword: Air injection

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An Experimental Study for Reducing the Exhaust Hydrocarbon Emission at SI Engine Using Timed Secondary Air Injection (2차 공기 분사에 의한 스파크 점화 가솔린 엔진의 배기 Hydrocarbon 저감에 관한 실험적 연구)

  • 심현성;김세준;정석호
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.7
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    • pp.104-112
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    • 1999
  • An experimental study for reducing the exhaust hydrocarbon emission at spark ignition engine using timed secondary air injection is carried out . In this study, secondary air injection timings and durations are controlled to decrease the hydrocarbon emission and to increase exhaust gas temperature at cold and warm-up engine conditions. The hydrocarbon reduction rate and exhaust gas temperature are compared between timed secondary air injection and continuous air injection. The optimum secondary air injection timing for reducing the hydrocarbon emission is at the exhaust valve open timing. At some engine conditions , the hydrocarbon emissions are decreased to 10% of engine raw values and exhaust gas temperatures increase by 20$0^{\circ}C$ with times secondary air injection . Timed secondary air injection has more hydrocarbon reduction rate that continuous secondary air injection except some engine conditions.

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Evaluation of the Laboratory-Scale Cometabolic Air Sparging Process : Characterization of Indigeneous Microorganism on MTBE Degradation (실험실 규모 Cometabolic Air Sparging 공정 적용 특성 평가 : 토양 내 활성미생물 별 MTBE 분해특성)

  • An, Sang-Woo;Lee, Si-Jin;Chang, Soon-Woong
    • Journal of Soil and Groundwater Environment
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    • v.15 no.1
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    • pp.1-8
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    • 2010
  • Cometabolic air sparging (CAS) is a new and innovative technology that uses air sparging principles but attempts to optimize in situ contaminant degradation by adding a growth substrate to saturated zone. CAS relies on the degradation of the primary growth substrate and cometabolic substrate transformation in the saturated zone and in the vadose zone for volatilized contaminants. In this study, we have investigated to determine MTBE degradation pattern and microbial activity variation if using propane as a primary substrate at the condition of considering air injection rate and air injection pattern. Laboratory-scale two-dimentional aquifer physical model studies were used and the experimental results were represented that the optimal conditions were as air injection rate of 1,000 mL/min and pulsed air injection pattern (15 min on/off). Over 1,000 mL/min air injection rate and continuous air injection pattern was no affected to increase DO concentration. On the other hand, Injection of propane and propane-utilizing bacteria degraded MTBE partially. And also, injection of propane- and MTBE-utilizing bacteria effectively degraded MTBE and TBA production was observed.

Lab-Scale Air/Bio-Sparging Study to Remediate Diesel-Contaminated Soil and Groundwater : The Effect of Air Injection Rate and Pattern (디젤오염 토양 및 지하수 복원을 위한 공기주입정화법 실험실 연구 : 공기주입량과 공기주입방식의 영향)

  • Chang, Soon-Woong;Lee, Si-Jin;Cho, Su-Hyung;Yoon, Jun-Ki
    • Journal of Soil and Groundwater Environment
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    • v.11 no.4
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    • pp.10-17
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    • 2006
  • Laboratory-scale two-dimensional aquifer physical model studies were conducted to assess the effect of air injection rate and air injection pattern on the removal of disel contaminated soil and groundwater by air/bio-sparging. The experimental results were represented that the optimal conditions in this experiment were as air injection rate of 1,000 ml/min and pulsed air injection pattern(15 min on/off). The results of the TPH reduction, DO consumption and $CO_2$ production indicate the effective biodegradation evidence of diesel. Based on our results, The minimal $O_2$ supply and pulsed air injection pattern could effectively enhance the diesel removal and the pulsing air injection had effect on oxygenation in this system. Thus, the cost of operating air/bio-sparging system will be reduced if optimal air injection rate and pulsed air injection pattern are applied to remediate contaminants.

Lab-Scale Biosparging Study to Remediate Diesel-Contaminated Soil and Groundwater : the effect of air injection rate and pattern

  • 조수형;이시진;권순열;장순웅
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • pp.462-466
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    • 2003
  • This study was conducted to examine the potential of biosparging process in removing diesel contaminated soil and groundwater. The experiment was carried out lab-scale biosparging reactor and the biodegradation rate of diesel was evaluated as function of air injection rate and pattern. When renter was operated as air injection rate of 1000$m\ell$/min and pulsed air injection(15min pulse, 15min downtime), DO concentration in the renter was higher than another operating condition. The evidence for biodegradation of diesel was the $O_2$ utilization and $CO_2$ product following the cessation of sparging. Especially, air injection rate of 2000$m\ell$/min and pulsed air injection(15min pulse, 15min downtime) enhanced the diesel biodegradation during the operating. After 120day, the biodegradation rate of diesel was decreased as the lack of carbon source.

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Permeation Characteristics of the Tubular Membrane Module Equipped wtih the Air Injection Nozzle Tube (공기주입 노즐관이 장착된 관형막의 투과특성)

  • Park, Mi Ja;Chung, Kun Yong
    • Membrane Journal
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    • v.27 no.1
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    • pp.43-52
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    • 2017
  • The air injection nozzle tube was inserted inside of the tubular membrane module to reduce membrane fouling and improve the permeate flux. The average pore size of membrane was $0.1\;{\mu}m$ and the yeast was used as a foulant. All of permeate experiments were started without air injection for the module equipped with the nozzle tube, then carried out continuously with air injection. Finally, the nozzle tube was removed from the module and the permeate was measured without air injection. The measured permeate fluxes were compared to examine the effect of air injection. The fluxes for air injection were consistently maintained or increased. The fluxes of no-air injection with the nozzle tube were greater than those of the empty tubular module. As operating pressure decreased to 0.4 bar, the flux enhancement of air injection based on no-nozzle case increased to 21%. Flux enhancements of air injection were above 30% as the gas/liquid two-phase flow was changed from the stratified-smooth to the intermittent pattern due to increase of gas flowrate.

Modeling of coupled liquid-gas-solid three-phase processes due to fluid injection

  • Zang, Yong-Ge;Sun, Dong-Mei;Feng, Ping;Stephan, Semprich
    • Geomechanics and Engineering
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    • v.13 no.1
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    • pp.1-23
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    • 2017
  • A coupled liquid-gas-solid three-phase model, linking two numerical codes (TOUGH2/EOS3 and $FLAC^{3D}$), was firstly established and validated by simulating an in-situ air flow test in Essen. Then the coupled model was employed to investigate responses of multiphase flow and soil skeleton deformation to compressed air or freshwater injection using the same simulation conditions in an aquifer of Tianjin, China. The simulation results show that with injecting pressurized fluids, the vertical effective stress in some area decreases owing to the pore pressure increasing, an expansion of soil skeleton appears, and land uplift occurs due to support actions from lower deformed soils. After fluids injection stops, soil deformation decreases overall due to injecting fluids dissipating. With the same applied pressure, changes in multiphase flow and geo-mechanical deformation caused by compressed air injection are relatively greater than those by freshwater injection. Furthermore, the expansion of soil skeleton induced by compressed air injection transfers upward and laterally continuously with time, while during and after freshwater injection, this expansion reaches rapidly a quasi-steady state. These differences induced by two fluids injection are mainly because air could spread upward and laterally easily for its lower density and phase state transition appears for compressed air injection.

Analysis of the Gas Flow Field of Primary Combustion Chamber with the Conditions of Secondary Air Injection (2차 공기 주입 조건 변화에 따른 소형 소각로 내부의 유동장 분석)

  • Choi, Byung-Dae;Kim, Sung-Joon
    • Journal of Industrial Technology
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    • v.22 no.A
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    • pp.9-17
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    • 2002
  • This analysis is aimed to find out how the conditions of secondary air injection affects the residence time and the turbulence energy of flue gas and flow field in a small incinerator. A commercial code, PHOENICS, is used to simulate the flow field of an Incinerator. The computational grid system is constructed in a cartesian coordinate system In this numerical experiment, an independent numerical variable is the conditions of secondary air injection and dependants are the residence time of flue gas and the mean value of turbulence energy in a primary combustion chamber. The flow field and the distribution of turbulence energy are analysed to evaluate the residence time of flue gas and the turbulence energy The computational results say that the tangential injection of secondary air make the residence time much longer than the radial injection and that the radial injection of secondary make turbulence much stronger than the tangential injection.

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Stability of premixed double concentric jets flame with a recirculation zone (재순환역을 수반하는 동축분류예혼합화염에 관한 연구)

  • 이등헌일;송규근
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.11 no.1
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    • pp.145-153
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    • 1987
  • Stability limits of a double concentric jets flame and the structure of recirculation zone formed behind a thick burner rim were investigated. To control the flame stability, swirled secondary air flow ranging 0.13-0.71 of swirl number, and air, fuel, and mixture gas injection from an injection coaxial slit set on burner rim were examined. Flame stability limits, flame shapes, lengths of recirculation zone, temperature distributions, residence times, air ratios in the recirculation zone were measured. The following results were obtained. (1) Lean limits were considerably widened by a strong swirl because the recirculation zone was enlarged. (2) At fuel injection as well as mixture injection, lean limits were also extended. But, air injection had no effect on stability limits. (3) Injected gas seems to diffuse into the recirculation zone through its outer boundary surrounded the secondary air. Therefore, chemical structure in the recirculation zone with air injection coincides with that without injection. (4) Injection position had no effect on flame stability limits.

An Experimental Study on the Improvement of Turbocharger Lag by Means of Air Injection in a Turbocharged Diesel Engine

  • Choi, Nag-Jung;Oh, Seong-Mo
    • Journal of Advanced Marine Engineering and Technology
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    • v.34 no.7
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    • pp.951-962
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    • 2010
  • An experimental study was performed to investigate the improvement of response performance of a turbocharged diesel engine under the operating conditions of low speed and fast acceleration. In this study, the experiment for improving the low speed and acceleration performance is performed by means of injecting air into the intake manifold of compressor exit during the period of low speed and application of a fast acceleration from low speed. The effects of air injection into the intake manifold on the response performance were investigated at various applicant parameters such as air injection pressure, accelerating rate, accelerating time, engine speed and load. The experimental results show that air injection into the intake manifold at compressor exit is closely related to the improvement of turbocharger lag under low speed and accelerating conditions of a turbocharged diesel engine. During the rapid acceleration period, the air injection into the intake manifold of turbocharged diesel engine indicates the improvement of the combustion characteristics and gas pressure in the cylinder. At low speed range of the engine, the effect of air injection shows the improvement of the pressure distribution of turbocharger and combustion pressure during the period of gas exchange pressure.

Effect of Air Velocity on Combustion Characteristics in Small-Scale Burner

  • Laryea, Gabriel Nii;No, Soo-Young
    • Journal of the Korean Society of Combustion
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    • v.10 no.1
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    • pp.1-6
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    • 2005
  • This paper presents the combustion characteristics of hydrocarbon fuel from a conventional pressure-swirl nozzle of a small-scale burner. The nozzle has orifice diameters of 0.256 mm and liquid flow rates ranging from 50 to 64 mL/min were selected for the experiments. The furnace temperature distribution along the axial distance, the gas emission such as CO, $CO_2$, NOx, $SO_2$, flue gas temperature, and combustion efficiency were studied. The local furnace and flue gas temperatures decreased with an increase in air velocity. At injection pressures of 1.1 and 1.3 MPa the maximum furnace temperatures occurred closer to the burner exit, at an axial distance of 242 mm from the diffuser tip. The CO and $CO_2$concentrations decreased with an increase in air velocity, but they increased with an increase in injection pressure. The effect of air velocity on NOx was not clearly seen at low injection pressures, but at injection pressure of 1.3 MPa it decreased with an increase in air velocity. The effect of air velocity on $SO_2$ concentration level is not well understood. The combustion efficiency decreased with an increase in air velocity but it increased with an increase in injection pressure. It is recommended that injection pressure less than 0.9 MPa with air velocity not above 8.0 m/s would be suitable for this burner.

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