• Title, Summary, Keyword: Air flow control

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Dynamic Response Improvement Method for Combustion Air Flow Control in Coal Fired Power Plant (석탄 화력발전소 연소공기량 제어 동특성 개선방안)

  • Yu, Kwang-Myung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.26 no.8
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    • pp.88-95
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    • 2012
  • When controling combustion air flow in coal fired power plant the furnace safety must be considered first prior to plant efficiency. therefore it is very important to set air flow demand exactly for safe operation and maintenance. This paper analyze air flow control loop in power plant and introduce the method to improve dynamic response time. Simulation result shows this scheme is adoptable and provide better performance.

A Study on the Dehumidification Control to Prevent Condensation for Radiant Floor Cooling (바닥복사냉방의 결로방지를 위한 제습제어에 관한 연구)

  • 김용이;김광우
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.2
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    • pp.137-143
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    • 2003
  • In the forming of an integrated system of radiant floor cooling and dehumidifying, chilled coil can be used for cooling and dehumidification. Therefore, it is necessary to find the efficient control method which can eliminates latent load efficiently. This study has been conducted to find this method by dividing the dehumidification system into 3 types according to the control variables and analyzing characteristics of each system. To prevent the floor surface condensation, the amount of condensation can be manipulated by water temperatures, water flow rates in chilled coil, and air flow rates passing by it. So dehumidification system control can be divided into constant air flow control and variable air flow control. Regarding dehumidification control, variable air flow control, which eliminates latent load rather than sensible load, is preferable to constant flow control.

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

  • 심한섭;이강윤;선우명호;송창섭
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.5
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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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A/F Control of an MPI Engine on Transient Conditions with an Intergration type Ultrasonic Flow Meter (적분형 초음파 유량계를 이용한 MPI 엔진의 비정상상태 공연비 제어)

  • 김중일;장준석;고상근
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.9
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    • pp.36-47
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    • 1999
  • Three-way catalyst converter, cleaning up the exhaust gas contamination of SI engine, has the best efficiency when A/F ratio is near the stoichiometry . The feedback control using oxygen sensors in the exhaust manifold has limits caused by the system delays. So the accurate measurement of air flow rate to an engine is essential to control the fuel injection rate especially on transient condition like the rapid throttle opening and closing. To measure the rapid change of flow rates. the air flow meter for the engine requires quick response, flow reversal detection, and linearity . Tjhe proposed integration type air flow meter (IFM), composed of an ultrasonic flow meter with an integration circuit, has significantly improved the measurement accuracy of air mass inducted through the throttle body. The proposed control method estimated the air mass at the cylinder port using the measured air mass at the throttle . For the fuel dynamic model, the two constant fuel model is introduced . The control parameters from air and fuel dynamics are tuned to minimize the excursion of the air fuel ratio. As a result A/F ratio excursion can be reduced within 5% when throttle rapidly opens and closes at the various engine conditions.

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CFD Analysis on the Internal Air Flow Control in a Wax Spin Coater of Silicon Wafer Polishing Station (실리콘 웨이퍼 연마장비용 왁스 스핀코팅장치의 내부기류 제어에 관한 전산유동해석)

  • Kim, Kyoung-Jin;Kim, Dong-Joo;Park, Joong-Youn
    • Journal of the Semiconductor & Display Technology
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    • v.10 no.1
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    • pp.1-6
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    • 2011
  • In this paper, the air flow induced by the rotating flat disk is numerically investigated in a hope to better understand the air flow structures inside the wax spin coater for a silicon wafer polishing station. Due to the complex inner geometry of actual spin coater such as the casing around the rotating ceramic block and servo motor, recirculation of air flow is inevitably found on the coating target if the internal space of spin coater is closed at the bottom and it could be the possible source of contamination on the wax coating. By numerical flow simulation, we found that it is necessary to install the air vent at the bottom and to apply the sufficient air suction in order to control the path of air flow and to eliminate the air recirculation zone above the spinning surface of coating target.

An Experimental Measurement on Transient Thermal Response in a PI-Controlled VAV System

  • Kim, Seo-Young;Moon, Jeong-Woo;Kim, Won-Nyun
    • International Journal of Air-Conditioning and Refrigeration
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    • v.11 no.1
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    • pp.10-16
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    • 2003
  • The present study performs an experimental measurement on transient thermal response of an air-conditioned space by a variable air volume (VAV) system with a PI(pro-portional-integral) control logic. A thermal chamber with a PI controlled VAV unit is constructed to verify the previously suggested stratified multi-zone model. The effects of thermal parameters and control parameters such as supply air temperature and PI control factor are investigated by implementing the thermal chamber test. The experimental results obtained show that transient behavior of the air-conditioned space-temperature is in good accordance with the simulation results of the stratified thermal model.

An Experimental Study on Performance Improvement of Automotive Air Handling System (자동차용 공기분배장치의 성능개선에 관한 실험적 연구)

  • Yoo, Seong-Yeon;Lee, Dae-Woong;Kim, Jin-Hyuck
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.19 no.9
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    • pp.622-629
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    • 2007
  • Compact semi-center type automotive air handling system(AHS) is developed in this study and it's performance is compared with the conventional 3-pieces type air hand-ling system. The pressure drop is measured at component level and system level, and air flow rate and air distribution of discharge air through each ducts from air handling system are measured. System level characteristics of pressure drop at face and windshield discharge mode and air flow rate are investigated, and also temperature control linearities are tested. The volume of the air handling system package is reduced about 20%. And air flow rate increase about 5 to 20% compared to the conventional 3-pieces type air handling system at each discharge mode with significantly improved air pressure drop both component and system level. Also, air distribution and temperature controllability meet to evaluation criteria.

Analysis of Supply Airflow Control by a Stratified Thermal Model in a VAV System

  • Kim, Seo-Young;Moon, Jeong-Woo;Cho, Hyung-Hee
    • International Journal of Air-Conditioning and Refrigeration
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    • v.9 no.3
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    • pp.46-56
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    • 2001
  • The present study concerns the numerical simulation of a supply airflow control in a variable air volume (VAY) system. A stratified thermal model (multi-zone model) is suggested to predict a local thermal response of an air-conditioned space. The effects of various thermal parameters such as the cooling system capacity, the thermal mass of an air-conditioned space, the time delay of thermal effect, and the building envelope heat transmission are investigated. Further, the influence of control parameters such as the supply air temperature, the PI control factor and the thermostat location on a VAV system is quantitatively delineated. The results obtained show that the previous homogeneous lumped thermal model (single zone model) may overestimate the time taken to the set point temperature. It is also found that there exist the appropriate ranges of the control parameters for the optimal airflow control of the VAV system.

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Experimental Study of the Superheat and Control of the Refrigerant Flow-Rate in the Evaporator of a Multi-type Air-Conditioning System (멀티형 공조시스템의 증발기 과열도에 관한 실험적 연구 및 냉매유량 제어)

  • 김태섭;홍금식;손현철
    • 제어로봇시스템학회:학술대회논문집
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    • pp.221-221
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    • 2000
  • The heat exchange part in a modern multi-type air-conditioning system employs multiple-pass heat exchangers. The heat-transfer performance of an each pass in such an exchanger depends strongly on the length of the two-phase region and the mass flow of the refrigerant. The total length and diameters of the pipes, the exit conditions, and the arrangement of each pass as well as the geometrical shape of the distributor at the branching sections are considered to be major factors affecting the heat-transfer performance. The refrigerant commonly used in these systems is HCFC-22. The two objectives of this paper are to investigate the characteristics of the refrigerant flow rate and the superheat in the evaporator of a multi-type air-conditioning system for a single or simultaneous operating conditions and to control the superheat and the refrigerant flow rate of the evaporator.

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Study on the control of fuel-air ratio ofgas swirl burner (가스 스월버너의 공연비 제어에 관한 연구)

  • Kim, I.K.;Kim, Y.S.;Kim, Y.H.;Kim, K.S.;Kim, J.W.
    • 한국연소학회:학술대회논문집
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    • pp.129-138
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    • 1999
  • In this paper, our main issue is that establishing the control procedure of continuous gas flow rate according to combustion fan RPM. For this, first, we decide the optimum operating condition of gas swirl burner through analysis of combustion characteristics - thermal efficiency, combustion efficiency and exhaust gases such as CO, $CO_{2}$, $O_{2}$, $NO_{x}$ and THC. Second, fuel gas flow rate of gas valve is decided with considering excess air ratio and combustion fan RPM is decided by the target of combustion air flow rate. Finally, experimental operating equation is acquired by regression for gas valve and combustion fan. This equation is the control equation of continuous gas flow rate and always gas flow rate is decided by combustion fan operating RPM.

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