• Title/Summary/Keyword: Mass Flow Control

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기체연료 엔진에서 공연비제어를 위한 흡입공기량 추정 (Estimation of Inlet Air Mass Flow for Air-Fuel Raito Control of Gaseous-Fuel Engines)

  • 심한섭;이강윤;선우명호;송창섭
    • 한국자동차공학회논문집
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    • 제9권5호
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    • pp.131-139
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    • 2001
  • Highly accurate control of the air-fuel ratio is important to reduce exhaust gas emissions of the gaseous-fuel engines. In order to achieve this purpose, inlet air mass flow must be measured exactly, and precise engine models are necessary to design engine control systems. In this paper, the effects of water vapor and gaseous fuel that change the air mass flow are studied. The effective air mass ratio is defined as the air mass flow divided by the mixture mass flow, and also it is applied to the estimation of the inlet air mass flow. The presence of the gaseous fuel and the water vapor in the mixture reduces the air partial pressure and the effective air mass ratio of the gaseous-fuel engines. The Experimental results for an LPG engine show that the estimation of the inlet ai mass flow based upon the effective air mass ratio is more accurate than that of the normal air mass flow.

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열간 압연공정의 선단부 통판성 안정화 제어 (Mass-flow Stabilization Control of a Strip Head Part in Hot Rolling Process)

  • 황이철;박철재;백운보
    • 제어로봇시스템학회논문지
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    • 제15권3호
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    • pp.330-336
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    • 2009
  • This paper studies on the new control algorithm for the mass-flow stabilization in strip head part of a hot strip mill. A new strip tension model in the strip head part is derived using the current deviation of two neighboring stands. The current deviation means a difference between a measured current and a lock-on current, where the lock-on current is set up when a strip tension or a looper angle reaches each target value or time is about 0.4sec, respectively. On the basis of the tension calculation model, a mill velocity of a backward stand is controlled to stabilize a strip mass-flow by PI control algorithm. Therefore, the mass-flow control for strip head part is executed from a metal-in time into a foreward stand till the looper works normally. It is known by the results of a computer simulation and an experiment that the proposed control algorithm is very effective in stabilizing the mass flow of the strip head part.

반도체 공정용 차압식 질량 유량 제어 장치의 개발 및 성능 평가 (Development and Evaluation of Differential Pressure Type Mass Flow Controller for Semiconductor Fabrication Processing)

  • 안진홍;강기태;안강호
    • 반도체디스플레이기술학회지
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    • 제7권3호
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    • pp.29-34
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    • 2008
  • This paper describes the fabrication and characterization of a differential pressure type integrated mass-flow controller made of stainless steel for reactive and corrosive gases. The fabricated mass-flow controller is composed of a normally closed valve and differential pressure sensor. A stacked solenoid actuator mounted on a base-block is utilized for precise and rapid control of gas flow. The differential pressure flow sensor consisting of four diaphragms can detect a flow rate by deflection of diaphragm. By a feedback control from the flow sensor to the valve actuator, it is possible to keep the flow rate constant. This device shows a fast response less than 0.3 sec. Also, this device shows accuracy less than 0.1% of full scale. It is confirmed that this device is not attacked by toxic gas, so the integrated mass-flow controller can be applied to advanced semiconductor processes which need fine mass-flow control corrosive gases with fast response.

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캐비테이션 벤튜리의 유량제어 성능 (Performance of Flow Rate Control of a Cavitating Venturi)

  • 조원국;문윤완;김영목
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2002년도 춘계 학술대회논문집
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    • pp.146-151
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    • 2002
  • Characteristics of flow rate control has been studied for a cavitating venturi adopted in a liquid rocket propellant feed system. Numerical simulation has been peformed to give about $10\%$ discrepancy of mass flow rate to the experimental data for cavitating flow regime. Mass flow rate is confirmed to be saturated for pressure difference higher than $3\times10^5$pa when the upstream pressure is fixed to $22.8\times10^5$pa and the downstream pressure is varied. The evaporation amount depends substantially to non-condensable gas concentration. However the mass flow rate characteristic is relatively insensitive to the mass fraction of non-condensable gas. So it is reduced by only $2\%$ when the non- condensable gas concentration is increased from 1.5PPM to 150PPM. From the previous comparison the expansions of the non-condensable gas and the evaporation of liquid are verified to have same effect to pressure recovery.

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열전달 질량유량계 개발 (Development of Thermal Mass Flow Meter)

  • 지대성
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 1999년도 유체기계 연구개발 발표회 논문집
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    • pp.118-122
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    • 1999
  • Thermal mass flow meter was developed using principle of convective heat transfer. The advantage of thermal mass flow meter is measuring mass flow directly, therefore, it is not required to use densitometer or temperature/pressure and DP gages. The final accuracy of this thermal mass flow meter is $\pm1.0{\%}$ or better, reproducibility is $\pm0.2{\%}$, and the response time is 600 ms. The thermal mass flow meter was developed from a single point to multi-points (maximum is 9 points), and the number of points is determined according to desired accuracy and size of piping/duct. Since this thermal mass flow meter adopted microprocessor based design, it is intrinsically accurate, self-error detectable, and has self-diagnosis function. The applications of this thermal mass flow meter are for measurement and control of HVAC air flow, other gas flow, and liquid flow.

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분류세관식 유량제어장치의 설계에 관한 연구 (A Study on the By-Pass Type Mass Flow Controller)

  • 최태민
    • 연구논문집
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    • 통권22호
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    • pp.85-96
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    • 1992
  • A mass flow controller(MFC) is commonly used in the semiconductor industries to control the flow rate of various process gases. The measurement and precise control of the of flow rate the gas are the key for a succesful IC fabrication. To eventually design a reliable MFC, a pre-proto type MFC was built and its flow characteristics were investigated. Most of the functional components of the pre-proto type were built for the present study, but the remainder were adopted from a commercial unit. The flow control characteristics were compared with that of a standard MFC. Major dimensions of an MFC for 0-10 SLM capacity were suggested.

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Lift Enhancement and Drag Reduction on an Airfoil at Low Reynolds Number using Blowing and Distributed Suction

  • Chao, Song;Xudong, Yang
    • International Journal of Aerospace System Engineering
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    • 제2권1호
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    • pp.6-11
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    • 2015
  • An active flow control technique using blowing and distributed suction on low Reynolds airfoil is investigated. Simultaneous blowing and distributed suction can recirculate the jet flow mass, and reduce the penalty to propulsion system due to avoiding dumping the jet mass flow. Energy is injected into main flow by blowing on the suction surface, and the low energy boundary flow mass is removed by distributed suction, thus the flow separation can be successfully suppressed. Aerodynamic lift to drag ratio is improved significantly using the flow control technique, and the energy consumption is quite low.

Thermal-hydraulic simulation and evaluation of a natural circulation thermosyphon loop for a reactor cavity cooling system of a high-temperature reactor

  • Swart, R.;Dobson, R.T.
    • Nuclear Engineering and Technology
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    • 제52권2호
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    • pp.271-278
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    • 2020
  • The investigation into a full-scale 27 m high, by 6 m wide, thermosyphon loop. The simulation model is based on a one-dimensional axially-symmetrical control volume approach, where the loop is divided into a series of discreet control volumes. The three conservation equations, namely, mass, momentum and energy, were applied to these control volumes and solved with an explicit numerical method. The flow is assumed to be quasi-static, implying that the mass-flow rate changes over time. However, at any instant in time the mass-flow rate is constant around the loop. The boussinesq approximation was invoked, and a reasonable correlation between the experimental and theoretical results was obtained. Experimental results are presented and the flow regimes of the working fluid inside the loop identified. The results indicate that a series of such thermosyphon loops can be used as a cavity cooling system and that the one-dimensional theoretical model can predict the internal temperature and mass-flow rate of the thermosyphon loop.

하이브리드 로켓의 추력제어를 위한 산화제 유량제어 연구 (Oxidizer Flow Rate Throttling for Thrust Control of Hybrid Rocket)

  • 김계환;문근환;김진곤;문희장
    • 한국항공운항학회지
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    • 제22권4호
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    • pp.93-98
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    • 2014
  • In this study, control of oxidizer mass flow rate and verification of control system were performed for hybrid rocket thrust control application. Oxidizer flow control system consists of ball valve and stepping motor where gaseous oxygen was used for oxidizer at feeding pressure of 10, 20 and 30 bar. According to experimental results, the oxidizer mass flow rate showed a relatively linear increment as ball valve open angle increases regardless of feeding pressure. In addition, the level of the oxidizer flow rate was kept almost constant at each sequence of flow control with ball valve during the 20 seconds of operation.

다단계 온도 감지막을 가진 고영역 흐름측정용 마이크로 흐름센서 (A Micro-Flow Sensor With Multiple Temperature Sensing Elements for Wide Range Flow Velocity Measurement)

  • 정완영;김태용;서용수
    • 제어로봇시스템학회논문지
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    • 제12궈1호
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    • pp.85-92
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    • 2006
  • A new silicon micro flow sensor with multiple temperature sensing elements was proposed and fabricated in considering wide range flow velocity measuring device. Thermal mass flow sensor measures the asymmetry of temperature profile around the heater which is modulated by the fluid flow. A micro mass flow sensor was normally composed of a central heater and a pair of temperature sensing elements around it. A new 2-D wide range micro flow sensor structure with three pairs of temperature sensing elements and a central heater was proposed and numerically simulated by Finite Difference Formulation to confirm the feasibility of the wide flow range sensor structure. To confirm the simulation result, the new flow sensor was fabricated on silicon substrate and the basic flow sensing properties of the sensor were measured.