• 제목/요약/키워드: gas lift

검색결과 128건 처리시간 0.025초

가솔린 엔진의 흡기밸브 리프트 변화에 따른 개별실린더 당량비 추정 및 제어 알고리즘에 관한 연구 (A Study on Individual Cylinder Equivalence Ratio Estimation and Control Algorithm for SI Engines)

  • 김준수;오승석;이민광;선우명호
    • 한국자동차공학회논문집
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    • 제19권5호
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    • pp.35-44
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    • 2011
  • In a spark ignition engine, a variable valve lift (VVL) system has been developed for high fuel efficiency and low power loss. However, changes in valve lift cause deviations of cylinder air charge which lead to individual cylinder equivalence ratio maldistribution. In this study, in order to reduce the maldistribution, we propose individual cylinder equivalence ratio estimation and control algorithms. The estimation algorithm calculates the equivalence ratio of each cylinder by using a mathematical engine model which includes air charging, fuel film, exhaust gas, and universal exhaust gas oxygen sensor (UEGO) dynamics at various valve lifts. Based on the results of estimated equivalence ratio, the injection quantity of each cylinder is adjusted to control the individual cylinder equivalence ratio. Estimation and control performance are validated by engine experiments. Experimental results represented that the equivalence ratio maldistribution and variation are decreased by the proposed algorithms.

250kW급 폐열회수 시스템 공정설계에 관한 연구 (A Study on the Engineering Design for 250kW-Grade Waste Gas Heat Recovery)

  • 김경수;방세경;서인호;이상윤;정은익;이중섭
    • 한국기계가공학회지
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    • 제18권5호
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    • pp.90-95
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    • 2019
  • This study aims to gain the design data through the process design of the organic Rankine cycle, which can produce 250kW of electric power through waste heat recovery. In this study, a simulation was conducted using APSEN HYSYS to make the model for the process design of the 250kW-class waste heat recovery system. For the thermodynamic model, the test was conducted with hot water as the heat source, the water steam as the cooling water for the cooler, and the refrigerant R245FA in the cycle. In the final design, it was expected and found from the simulation that the cycle efficiency was 12.62% and that 250kW of power was produced considering the margin of 80%.

소형 공기 양수 펌프의 불규칙한 가스-액체 흐름의 CFD 모델링 (CFD Modeling of Unsteady Gas-Liquid Flow in a Small Scale Air-Lift Pump)

  • 이설송;정효민;정한식
    • 동력기계공학회지
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    • 제16권1호
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    • pp.30-37
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    • 2012
  • 공기 양수 펌프는 재생 에너지 분야, 부식 및 마모 특성의 유체의 활용 등 높은 신뢰성과 낮은 유지보수 비용을 필요로 하는 분야에서 그 사용이 증대되고 있다. 본 연구에서는 소형 공기 양수 펌프의 성능 평가 및 기초 데이터를 얻기 위한 연구로, D=0.012~0.019m, L=0.933m인 배관의 침수 깊이(${\beta}$=0.55,0.60,0.65,0.70)에 따른 수치해석을 수행하였다. 수치 해석 및 실험 결과는 유사성을 뛰었으며, 펌프의 사양과 효율은 공기의 질량 유속 비, 침수 깊이 비와 양수 배관의 길이에 관한 함수로 나타났다. 그리고 최대 물과 공기 질량 유속의 비는 각 배관에서 서로 다른 침수 깊이의 비로 나타났으며, 공기 양수 펌프의 최대 효율이 발생되는 운전조건은 슬러그(slug)와 슬러그 교반 정도(slug-churn flow regime)에 따라 나타남을 알 수 있었다.

GIS 내 금속입자의 부상전압과 부분방전특성 연구 (Lift-Off Voltage and Partial Discharge Characteristics of Free Metallic Particles in GIS)

  • 윤진열;한상옥
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제48권2호
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    • pp.127-132
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    • 1999
  • Both motion of free metallic particles from which most GIS internal failures are caused and partial discharges from the particles were examined using EHV GIS test chamber. Effects from particle length and gas pressure which are main factors to lead to breakdown failure were investigated theoretically and experimentally. Magnitude of both lift-off voltage and partial discharge inception voltage were measured respectively and, through these measurements, this paper showed the possibility of predicting breakdown fault and of taking action to prevent the fault in advance. The measurement of partial discharge when the particles began to move could be adopted to decide minimum sensitivity in developing predictive diagnostic equipments. Both the amount of apparent discharge and real discharge in GIS were examined theoretically and experimentally, then experimental results were analyzed on the basis of the theory.

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SOI CMOS-Based Smart Gas Sensor System for Ubiquitous Sensor Networks

  • Maeng, Sung-Lyul;Guha, Prasanta;Udrea, Florin;Ali, Syed Z.;Santra, Sumita;Gardner, Julian;Park, Jong-Hyurk;Kim, Sang-Hyeob;Moon, Seung-Eon;Park, Kang-Ho;Kim, Jong-Dae;Choi, Young-Jin;Milne, William I.
    • ETRI Journal
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    • 제30권4호
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    • pp.516-525
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    • 2008
  • This paper proposes a compact, energy-efficient, and smart gas sensor platform technology for ubiquitous sensor network (USN) applications. The compact design of the platform is realized by employing silicon-on-insulator (SOI) technology. The sensing element is fully integrated with SOI CMOS circuits for signal processing and communication. Also, the micro-hotplate operates at high temperatures with extremely low power consumption, which is important for USN applications. ZnO nanowires are synthesized onto the micro-hotplate by a simple hydrothermal process and are patterned by a lift-off to form the gas sensor. The sensor was operated at $200^{\circ}C$ and showed a good response to 100 ppb $NO_2$ gas.

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산소부화와 희석제에 따른 비예혼합 화염의 안정성 (Effect of Diluents and Oxygen-Enrichness on the Stability of Nonpremixed Flame)

  • 배정락;이병준
    • 대한기계학회논문집B
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    • 제26권10호
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    • pp.1458-1464
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    • 2002
  • $CO_2$ is well known greenhouse gas which is the major source of global warming. Reducing $CO_2$ emission in combustion process can be achieved by increasing combustion efficiency, oxygen enriched combustion and recirculation of the emitted $CO_2$ gas. Stability of non-premixed flame in oxygen enriched environment will be affected by the amount of oxygen, kind of diluents and fuel exit velocity. The effects of these parameters on flame liftoff and blowout are studied experimentally oxidizer coflowing burner. Experiments were divided into three cases according as where $CO_2$gas was supplied. - 1) to coflowing air, 2) to fuel with 0$_2$-$N_2$ coflow, 3) to coflowing oxygen. Flame in air coflowing case was lifted in turbulent region. Flame lift and blowout in laminar region with the increase in $CO_2$ volume fraction in $CO_2$-Air mixture makes flame lift and blowout in laminar region. Increase in oxygen volume fraction makes flame stable-i.e. flame liftoff and blowout occur at higher fuel flowrates. Liftoff height was non-linear function of nozzle exit velocity and affected by the $O_2$ volume fraction. It was found that the flame in $O_2$-$N_2$ coflow case was more stable than $O_2$-$CO_2$ case, Liftoff heights vs (nozzle exit velocity/laminar burning velocity)$^{3.8}$ has a good correlation in $O_2$-$CO_2$ oxidizer case.

표면 거칠기가 가스 포일 스러스트 베어링의 성능에 미치는 영향 (Effects of Surface Roughness on the Performance of a Gas Foil Thrust Bearing)

  • 황성호;김대연;김태호
    • Tribology and Lubricants
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    • 제39권2호
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    • pp.81-85
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    • 2023
  • This study presents an experimental investigation of the effects of surface roughness on gas foil thrust bearing (GFTB) performance. A high-speed motor with the maximum speed of 80 krpm rotates a thrust runner and a pneumatic cylinder applies static loads to the test GFTB. When the motor speed increases and reaches a specific speed at which a hydrodynamic film pressure generated within the gap between the thrust runner and test GFTB is enough to support the applied static load, the thrust runner lifts off from the test GFTB and the friction mechanism changes from the boundary lubrication to the hydrodynamic lubrication. The experiment shows a series of lift-off test and load-carrying capacity test for two thrust runners with different surface roughnesses. For a constant static load of 15 N, thrust runner A with its lower surface roughness exhibits a higher start-up torque but lower lift-off torque than thrust runner B with a higher surface roughness. The load capacity test at a rotor speed of 60 krpm reveals that runner A results in a higher maximum load capacity than runner B. Runner A also shows a lower drag torque, friction coefficient, and bearing temperature than runner B at constant static loads. The results imply that maintaining a consistent surface roughness for a thrust runner may improve its static GFTB performance.

합성가스의 충돌제트 연소장에서 고신장율 부상 예혼합화염 연소 특성 연구 (A Study on Combustion Characteristics of Synthetic Gas Air Lifted Premixed Flames with High Strain Rate in an Impinging Jet Combustion Field)

  • 강기중;박태준;황철홍;이기만
    • 한국연소학회지
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    • 제16권4호
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    • pp.31-37
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    • 2011
  • This paper presents both experimental and numerical investigation of the combustion characteristics of stretched premixed lift-off flames using synthetic gas($H_2$/CO) in an impinging burner. We used "Spin code" for numerical analysis. An ICCD camera was employed to measure flame location and flame thickness. The impinging surface temperature was affected by local strain rate K, equivalence ratio, and composition ratio of fuel. In spite of the difference of boundary conditions in experimental and numerical results, the tendencies of surface temperatures were agreed. From result of this work, we also found that flame location and flame thickness directly related to surface temperature are greatly affected by local strain rate K.

Influence of Tank Inner Side Dielectric Coating on the Particle Behaviour and Flashover Voltage in SF\ulcorner Gas Insulated System

  • Lee, Bang-Wook;Koo, Ja-Yoon
    • Journal of Electrical Engineering and information Science
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    • 제2권3호
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    • pp.77-81
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    • 1997
  • In his work, the influence of wire type conducting particles on the insulation reliability of GIS has been systematically investigated when the epoxy resin based dielectric coating was made on he inner side of outer electrode. For this purpose, coaxial cylinder-type electrode was adopted in 362 kV chamber and various sizes of Cu conducting particle were used under different gas pressures. In order to elucidate the coating effect on the gas insulation, different thickness of dielectric coating has been considered and then the lift-off voltage and flashover voltages have been measured. The results shown that the dielectric coating has a remarkable influence by restraining the movement of particle in GIS system, and thus GIS insulation reliability is noticeably improved.

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내부순환식 기포탑 반응기 상에서 MEA (monoethanolamine) 용액에 의한 이산화탄소 분리 및 메탄회수 (Methane Recovery and Carbon Dioxide Stripping by MEA Solution the Autocirculation Bubble Lift Column Reactor)

  • 이인화;김선일;박주영
    • 공업화학
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    • 제18권3호
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    • pp.239-244
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    • 2007
  • 이산화탄소 분리 및 메탄 회수를 동시에 수행하기 위한 배출구가 두 개로 분리된 내부순환식 기포탑 반응기를 이용하여 $CO_2$ 분리용 흡수제인 모노에탄올아민(MEA)의 최적조건을 도출하였다. 5 wt% MEA 수용액에서 이산화탄소의 흡수 및 탈기 반응 시 pH 변화, 공기주입량에 따른 이산화탄소 탈기량 및 메탄 함량변화를 관찰하였다. 또한 액상수위 및 초기 MEA 흡수액 온도변화에 따른 이산화탄소 흡수 및 메탄 회수율을 측정하였다. 최적반응조건은 정상상태에서 액상수위 40 mm, 공기주입량은 1.5 L/min, 흡수액의 온도 $25^{\circ}C$이었다