• Title/Summary/Keyword: Mass Flow Control

Search Result 483, Processing Time 0.024 seconds

Numerical Analysis for Evaluation of Ejection Capacity Relationship of Safety Valves in Pressure Regulating Station(I) - Flow Analysis and Mass Flow Rate Verification of Pressure Regulator - (정압기지내의 안전밸브 분출용량 관계식 검증을 위한 유동해석(I) - 정압기 유동 해석 및 질량 유량 검증 -)

  • Gwon, Hyuk-Rok;Roh, Kyung-Chul;Kim, Young-Seop;Lee, Seong-Hyuk
    • Journal of the Korean Institute of Gas
    • /
    • v.12 no.2
    • /
    • pp.99-104
    • /
    • 2008
  • Gas pressure regulators in pressure regulating station reduce high-pressure gas in a process line to a lower. Gas pressure regulators are not flow control devices, they are used to control delivery pressure only. For the safety of pressure regulating station, it is essential to study flow regime and characteristics of a safety valves that is connected to a pressure regulator. For this, it is necessary to understand flow characteristics and the flow rate of upstream component part such as gas pressure regulators in regulating station. In the present study, numerical analysis of flow characteristics and the mass flow rate of a pressure regulator is conducted under the several inlet, outlet conditions and open rates. Then, the numerical result of the mass flow rate is verified with experimental equation from manufacture of pressure regulator. Consequently, the numerical result is comparatively good agreement with values from experimental equation.

  • PDF

Variations of Air Temperature, Relative Humidity and Pressure in a Low Pressure Chamber for Plant Growth (식물생장용 저압챔버 내의 기온, 상대습도 및 압력의 변화)

  • Park, Jong-Hyun;Kim, Yong-Hyeon
    • Journal of Bio-Environment Control
    • /
    • v.18 no.3
    • /
    • pp.200-207
    • /
    • 2009
  • This study was conducted to analyze the variations of air temperature, relative humidity and pressure in a low pressure chamber for plant growth. The low pressure chamber was composed of an acrylic cylinder, a stainless plate, a mass flow controller, an elastomer pressure controller, a read-out-box, a vacuum pump, and sensors of air temperature, relative humidity, and pressure. The pressure leakage in the low pressure chamber was greatly affected by the material and connection method of tubes. The leakage rate in the low pressure chamber with the welding of the stainless tubes and a plate decreased by $0.21kPa{\cdot}h^{-1}$, whereas the leakage in the low pressure chamber with teflon tube and rubber O-ring was given by $1.03kPa{\cdot}h^{-1}$. Pressure in the low pressure chamber was sensitively fluctuated by the air temperature inside the chamber. An elastomer pressure controller was installed to keep the pressure in the low pressure chamber at a setting value. However, inside relative humidity at dark period increased to saturation level.. Two levels (25 and 50kPa) of pressure and two levels (500 and 1,000sccm) of mass flow rate were provided to investigate the effect of low pressure and mass flow rate on relative humidity inside the chamber. It was concluded that low setting value of pressure and high mass flow rate of mixed gas were the effective methods to control the pressure and to suppress the excessive rise of relative humidity inside the chamber.

A Study on Flow Analysis at Ball Valve according to Opening and Shutting Angle (개폐 각도에 따른 볼 밸브에서의 유동 해석에 관한 연구)

  • Cho, Jae-Ung;Han, Moon-Sik
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.10 no.2
    • /
    • pp.46-51
    • /
    • 2011
  • This study result is obtained by flow analysis according to opening and shutting angle of ball valve. As opening and shutting angle becomes larger, vortex flow becomes smaller and flow rate becomes increased. And the pressure drop is shown to be smaller at the inlet and outlet of ball. As this angle becomes larger, mass flow rate becomes increased. Its rate becomes increased abruptly in case of opening and shutting angle at more than $60^{\circ}$.This analysis result can be applied usefully with no leak at pipe system field by the optimum control of mass flow rate according to opening and shutting of ball valve.

A Study on Rolling Mill Dynamics Model and Automatic Gauge Control System

  • Kim, Tae-Young;Kwon, Dae-Hyun;Choi, Won-Ho
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 2004.08a
    • /
    • pp.120-125
    • /
    • 2004
  • In the rolling of steel or non-steel metal the most important quality aspect are thickness and flatness. In thickness, there are two important factors. One of them is getting close with accurate goal, nominal gauge, the other is minimize gauge bandwidth, the variation in gauge. In this thesis, we proposed the fuzzy model AGC to minimize gauge variation along the length, developed the rolling mill dynamic model using the math mode of the rolling mill process and the rolling model related with the variety character of the rolling material. We compared the gauge control efficiency of fuzzy model AGC and PI mass flow AGC. We have got a simulation result, that the exit gauge variation of PI mass flow AGC was 2 micron and fuzzy model AGC was 1.2 micron at 1200mpm of rolling speed when each controller was rolling 5 micron of material that is the entry gauge variation.

  • PDF

Characteristics of Laser Aided Direct Metal Deposition Process for Tool Steel (공구강을 이용한 레이저 직접 금속조형 공정의 적층 특성)

  • 장윤상
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2004.10a
    • /
    • pp.327-330
    • /
    • 2004
  • Laser aided direct metal deposition (LADMD) process offers the ability to make a metal component directly from 3-D CAD dimensions. A 3-D object can be formed by repeating laser cladding layer by layer. The key of the build-up mechanism is the effective control of powder delivery and laser power to be irradiated into the melt-pool. A feedback control system using optical sensors is introduced to control laser power and powder mass flow rate. Using H13 tool steel and $CO_2$ laser system, comprehensive analysis are executed to test the efficiency of the system. In addition, the dimensional characteristics of directed deposited material are investigated with the parameters of deposition thickness, laser power, traverse speed and powder mass flow rate.

  • PDF

A Study on Determination of Boron Makeup Flow Rate During the Load Follow Operation (부하추종 운전시 보론 보충 수량 결정에 관한 연구)

  • Song, Yong-Mann;Lee, Un-Chul;Chung, Chang-Hyun
    • Nuclear Engineering and Technology
    • /
    • v.20 no.1
    • /
    • pp.1-8
    • /
    • 1988
  • During power plant operation, the flow rate from the CVCS makeup system is estimated using the continuity equation and mass balance equation, when the primary loop boron concentration change is required due to the power transient. For this purpose, primary loop, pressurizer and VCT(volume control tank)(in CVCS) are modeled by three control volumes which contain each mass and boron concentration. Connecting pipes between primary loop, pressurizer and CVCS are also modeled by time delay. Calculation for 14-2-6-2 (power 100-50-100) load follow case (at EOL, for KNU 7) is made using these models.

  • PDF

Tension Modeling and Looper-Tension ILQ Servo Control of Hot Strip Finishing Mills (열간 사상압연기의 장력 연산모델과 루퍼-장력 ILQ 서보 제어)

  • Hwang, I.C.;Park, C.J.
    • Journal of Power System Engineering
    • /
    • v.12 no.1
    • /
    • pp.72-79
    • /
    • 2008
  • This paper designs a looper-tension controller for mass-flow stabilization in hot strip finishing mills. By Newton's 2nd law and Hooke's law, nonlinear dynamic equations on the looper-tension system are firstly derived, and linearized by a linearization algorithm using a Taylor's series expansion. Moreover, a tension calculation model is obtained from the nonlinear dynamic equations which is called as a soft sensor of strip tension between two neighboring stands. Next, a looper-tension servo controller is designed by an ILQ(Inverse Linear Quadratic optimal control) algorithm, and it is combined with a minimal disturbance observer which to attenuate speed disturbances by AGC and operator interventions, etc.. Finally, it is shown from by a computer simulation that the proposed ILQ controller with a disturbance observer is very effective in stabilizing the strip mass-flow under some disturbances, moreover it has a good command following performance.

  • PDF

Fabrication and Characteristics of a Piezoelectric Valve for MEMS using a Multilayer Ceramic Actuator (적층형 세라믹 엑추에이터를 이용한 MEMS용 압전밸브의 제작 및 특성)

  • 정귀상;김재민;윤석진
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.17 no.5
    • /
    • pp.515-520
    • /
    • 2004
  • We report on the development of a Piezoelectric valvc that is designed to have a high reliability for fluid control systems, such as mass flow control, transportation and chemical analysis. The valve was fabricated using a MCA(multilayer ceramic actuator), which has a low consumption power, high resolution and accurate control. The fabricated valve is composed of MCA, a valve actuator die and an seat die. The design of the actuator dic was done by FEM(finite element method) modeling, respectively. And, the valve seat die with 6 trenches was made. and the actuator die, which possible to optimize control to MCA, was fabricated. After Si-wafer direct bonding between the seat die and the actuator die, MCA was also anodic bonded to the scat/actuator die structure. PDMS(poly dimethylsiloxane) sealing pad was fabricated to minimize a leak-rate. It was also bonded to scat die and stainless steel package. The flow rate was 9.13 sccm at a supplied voltage of 100 V with a 50 % duty ratio and non-linearity was 2.24 % FS. From these results, the fabricated MCA valve is suitable for a variety of flow control equipments, a medical bio-system, semiconductor fabrication process, automobile and air transportation industry with low cost, batch recess and mass production.

A computational approach to the simulation of controlled flows by synthetic jets actuators

  • Ferlauto, Michele;Marsilio, Roberto
    • Advances in aircraft and spacecraft science
    • /
    • v.2 no.1
    • /
    • pp.77-94
    • /
    • 2015
  • The paper focuses on the integration of a non-linear one-dimensional model of Synthetic Jet (SJ) actuator in a well-assessed numerical simulation method for turbulent compressible flows. The computational approach is intended to the implementation of a numerical tool suited for flow control simulations with affordable CPU resources. A strong compromise is sought between the use of boundary conditions or zero-dimensional models and the full simulation of the actuator cavity, in view of long-term simulation with multiple synthetic jet actuators. The model is integrated in a multi-domain numerical procedure where the controlled flow field is simulated by a standard CFD method for compressible RANS equations, while flow inside the actuator is reduced to a one-dimensional duct flow with a moving piston. The non-linear matching between the two systems, which ensures conservation of the mass, momentum and energy is explained. The numerical method is successfully tested against three typical test cases: the jet in quiescent air, the SJ in cross flow and the flow control on the NACA0015 airfoil.

The Quality Control of Mass Concrete mixed with Fly-Asy (플라이애쉬를 혼합한 매스콘크리트의 품질관리)

  • 박칠림;권영호;이상수;김동석;박상준
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 1998.10b
    • /
    • pp.940-945
    • /
    • 1998
  • Recently, serious cracking problems have been reported in this country while the process of actual massive concrete construction. he hydration heat arising from the chemical reaction of cement with water causes temperature differentials in between inside and outside of a structural member, and these temperature differentials induce thermal stresses. In this paper, we described on the practical application and quality control of the mass concrete mixed with fly-ash. This project is investigating adiabatic temperature rise test of concrete, mock-up test in the laboratory, ad B/P before placing the mass concrete in site. As a result, we can be prevent temperature cracking from the cement hydration heat of mass concrete and also can be showed up secure quality control flow chart of mass concrete.

  • PDF