• Title/Summary/Keyword: 가변압축장치

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A Study on the Cycle Analyzing and Intake Valve Control by the Miller Method with a High Expansion into Low-Speed Diesel Engine (저속 디젤기관에서 고팽창의 밀러방식에 의한 사이클 해석 및 흡기밸브제어에 대한 연구)

  • Jag, Tae-Ik
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.8
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    • pp.1100-1106
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    • 2009
  • Recently, there are quite a lot of attention is drown on the researches related to of Miller method applied high expansion cycle. For this study, high expansion cycles are formed and analyzed with the base view point of thermodynamics, and the features of each factors are also investigated. As a result of analysis, the expansion-compression ratio is expected with a decrease of effective compression ratio as intake valve closing time retarded, however, the decrease of mean effective pressure and its output is accompanied with the counterflow of intake air. Accordingly, as the consequence of such failure, it is expected that an alternative is needed for the realization of high expansion cycles, and the improvement over thermal efficiency. To materialize such cycle, the control system to delay the closing time of intake valve was designed and VVT, the 3 S/B low speed diesel engine, is applied to evaluate the efficiency. The result of the trial shows that there was no significant errors.

에어컨용 냉매압축기

  • 이승갑;소순갑;최영민
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.31 no.11
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    • pp.8-14
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    • 2002
  • 가정용 룸에어컨이나 가정, 점포, 사무실에 사용하는 패키지에어컨은 쾌적한 주거 사무공간을 실현할 수 있기 때문에 최근 10년 동안에 광범위하게 보급되었고, 그 기술도 해마다 진보하고 있다. 그림 1에서 나타나듯이 2001년 가정용 룸에어컨의 국내생산 수량은 연간 600만대 수준이며, 패키지에어컨은 연간 약 80만대 수준이다. 2001년 기준으로 에어컨의 국내시장규모는 약 130만대로 세대 보급률이 약 40%에 도달하고 있다. 비록 패키지에어컨은 생산 수량면에서는 룸에어컨과 비교할 수 없지만, 한대의 냉방능력이 룸에어컨의 수배에서 수십배로 크기 때문에 전력에너지소비, 환경 등에 미치는 영향은 룸에어컨과 비견될 수 있다. 공조장치 보급에 따른 환경, 에너지 측면에서의 사회적 영향과 관심이 점차 커지고 있고, 이것을 개선하기 위한 기술개발이 활발하게 진행되고 있다. 에어컨을 포함한 공조장치의 다수는 효율이 좋은 증기 압축식 냉동사이클로써 구성되어 있으며, 증기 압축식 사이클에서 냉매가스를 압축하여 순환시키는 심장역할을 하고 있는 것이 압축기이다. 또한 압축기는 공조장치 전체의 전력소비의 80%에서 90%을 차지하고 있어 에너지절감 기술개발과 환경기술개발의 포인트가 되는 기구이다. 최근에 에어컨용 냉매압축기의 기술적인 개발동향을 정리하면 다음과 같은 경향으로 진행되고 있다. (1)오존층 파괴 지수가 제로인 친환경 HFC계와 자연냉매용 밀폐형 압축기기술 (2)로터리압축기의 성능향상 및 대용량화 기술 (3)압축기용 모터의 DC화통에 의한 모터 효율 향상 및 압축기 효율 향상 기술 (4)스크롤압축기의 압축비 변화의 대응, 고효율 유지, 대용량화 등 성능향상기술 (5)로터리, 스크롤, 왕복동 압축기를 이용한 용량가변기술 본 논고에서는 룸에어컨과 패키지에어컨에서 사용되고 있는 밀폐형 압축기에 대해서 그림 2에서 나타내고 있는 냉방능력 10tons(120,000Btu/h) 이하를 중심으로 상기의 최근 기술 동향을 간략하게 소개하고자 한다.

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Development of Variable Guide Vane Actuator System for Testing of Aircraft Gas Turbine Engine (항공용 가스터빈 리그시험용 가변정익 구동시스템 개발)

  • Kim, Sun Je;Jeong, Chi Hoon;Ki, Taeseok
    • Journal of the Korean Society of Propulsion Engineers
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    • v.23 no.3
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    • pp.9-17
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    • 2019
  • Variable guide vanes(VGVs) that consist of link mechanisms and an actuator system are required for an aircraft gas turbine engine to adjust the incidence angle of stator vanes. In this study, we developed a VGV actuator system for three-stage VGVs with two hydraulic actuators. The requirements for the actuator system were derived by analyzing the link mechanisms and air loads, and a hydraulic power-pack was developed based on these requirements. Through a load test using the actuator test-rig and the application of synchronizing control logic with proper control gains, the actuator system could be developed and verified.

Measurement and Modeling of Bubble Points for Binary Mixtures of Carbon Dioxide and N,N-Dimethylformamide (이산화탄소와 디메틸포름아마이드 혼합물의 기포점 측정 및 모델링)

  • Jung, Joon-Young;Lee, Byung-Chul
    • Clean Technology
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    • v.17 no.1
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    • pp.19-24
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    • 2011
  • The bubble point pressures of binary mixtures of carbon dioxide ($CO_2$) and N,N-dimethylformamide (DMF) were measured by using a high-pressure experimental apparatus equipped with a variable-volume view cell, at various $CO_2$ compositions in the range of temperatures above the critical temperature of $CO_2$ and below the critical temperature of DMF. The experimental bubble point pressure data were correlated with the Peng-Robinson equation of state (PR-EOS) to estimate the corresponding dew point compositions at equilibrium with the bubble point compositions. The experimentally measured bubble point pressures gave good agreement with those calculated by the PR-EOS. The variable-volume view cell equipment was verified to be an easy and quick way to measure the bubble point pressures of high-pressure compressible fluid mixtures.

Analysis of flow rate of variable displacement compressor ECV in automobile air conditioning control system (자동차 공조장치의 가변압축기 ECV 유량 분석)

  • Jeong, Yeong Jun;Cho, Haeng Muk
    • Journal of Energy Engineering
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    • v.22 no.4
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    • pp.394-398
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    • 2013
  • At present, using of electromagnetic control valve (ECV) in external variable displacement swash plate type compressor is a common issue. Solenoid operated ECV controls vehicle air conditioning system through a pulse width modulation (PWM) input signal that supplied from an external source. Different port pressure controls the swash plate movement inside the compressor at certain angles that finally determines the refrigerant flow rate to the vehicle compartment for passengers comfort. In this paper, crankcase pressure flow (Pc flow) is calculated with some ECV samples with corresponding to amount of variable supply of current ranges from 0.20Amp to 0.95Amp.

A Cell-based Compression Technique of the Spatial Data for the Mobile GIS (모바일 GIS를 위한 셀 기반의 공간 데이터 압축 기법)

  • Lee, Ki-Young;Lim, Keun;Choi, Gyoo-Seok
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.8 no.6
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    • pp.49-54
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    • 2008
  • Recently, with the development of wireless communications and GIS, interest about mobile computing is rising. In this case, the GIS needs to be placed in a constricted environment than the environment of server computing. For this reason large amounts of spatial data must be compressed into the mobile device. The compression technique of the spatial data is difficult and must be processed in the correct order because the size of the data is unpredictable. Therefore, in this paper, the cell-based compression technique of the spatial data for mobile GIS is presented. This paper includes the process of transformation of spatial data from a certain server to a mobile device by cell-based compression technique. In this paper, the cell-based compression technique of the spatial data has been proven practically efficient.

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Measurement of Bubble Points of Dimethyl Carbonate and Carbon Dioxide Mixtures (디메틸카보네이트와 이산화탄소 혼합물의 기포점 측정)

  • Ahn, Joon-Yong;Lee, Byung-Chul
    • Applied Chemistry for Engineering
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    • v.20 no.1
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    • pp.94-98
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    • 2009
  • The bubble point pressures of dimethyl carbonate and carbon dioxide mixtures were measured by using a high-pressure experimental apparatus equipped with a variable-volume view cell, at various $CO_2$ compositions in the range of temperatures above the critical temperature of $CO_2$ and below the critical temperature of dimethyl carbonate. The experimental bubble point pressure data were correlated with the Peng-Robinson equation of state (PR-EOS) to estimate the corresponding dew point compositions at equilibrium with the bubble point compositions. The experimentally measured bubble point pressures gave good agreement with those calculated by the PR-EOS. The variable-volume view cell equipment was verified to be an easy and quick way to measure the bubble point pressures of high-pressure compressible fluid mixtures.

Study of Application of Impulse Turbine with Staggered Blades to Improve the Performance for Wave Energy Conversion (파력발전용 임펄스터빈의 효율 향상을 위한 Staggered Blade의 적용에 대한 연구)

  • Moon, Jae-Seung;Shin, Seung-Ho;Hyun, Beom-Soo;Kim, Gil-Won;Hong, Key-Yong
    • Journal of Navigation and Port Research
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    • v.31 no.10
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    • pp.845-852
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    • 2007
  • An OWC-type Wave Energy Conversion passes through 3 steps energy conversion process. This paper deal with the impulse turbine with staggered blade to improved performance by numerical analysis using commercial CFD code, FLUENT Maximum value of axial airflow velocity during exhalation is higher than that during inhalation This paper deal with special-type of Impulse Turbine so-called "Staggered Blade" for more efficiency to making air flow direct to on pressure side. Also, this paper has proposed special-type turbine with self-pitched blade more efficient.

Ultra-narrow linewidth single frequency DFB laser with FBG ring cavity (극미세선폭 단일모드 FBG 고리구조 공동 DFB 레이저)

  • 김준원;진용옥;최규남
    • Korean Journal of Optics and Photonics
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    • v.13 no.3
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    • pp.235-239
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    • 2002
  • A novel ultra-narrow linewidth DFB laser in the extended FBG ring cavity having kHz linewidth is presented. The method of linewidth compression was realized by introducing an extended fiber ring cavity into the cavity between the external FBG and the Bragg grating inside a DFB laser diode. Optimum optical feedback control was achieved by using an optical circulator and a variable optical attenuator to prevent mode hopping induced by spatial hole burning. To prove the validity of the proposed scheme, a self-heterodyne measurement set-up with fiber delay line of 63 km was utilized for the ultra-narrow linewidth measurement. A 3 dB linewidth of less than 3 kHz was demonstrated, which is resolution limited performance. This linewidth is equivalent to 3 dB linewidth of 2$\times$10$^{-8}$ nm.

A study on the transient characteristics during speed up of inverter heat pump (회전수 상승폭 변화에 따른 인버터열펌프의 비정상 운전특성)

  • 황윤제;김호영
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.10 no.4
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    • pp.495-507
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    • 1998
  • The transient characteristics of a 4.0㎾ inverter driven heat pump was investigated by theoretical and experimental studies. The heat pump used in this study consists of a high side scroll compressor and $\Phi$7 compact heat exchangers with two capillary tubes. A series of tests was peformed to examine the transient characteristics of heat pump in heating and cooling mode when the operating speed was varied from 30Hz to 102Hz. One of the major issues that has not been addressed so far is transient characteristics during speed modulation. A cycle simulation model has been developed to predict the cycle performance under frequency rise-up conditions, and the results of theoretical study were compared with the results of experimental study. The theoretical model was driven from mass conservation and energy conservation equations to predict the operation points of refrigerant cycle and the performances at various operating speeds. For transient conditions, the simulated results are in good agreement with the experimental results within 10%. The transient cycle migration of the liquid state refrigerant causes a significant dynamic change in system. Thus, the migration of refrigerant is the most important factor whenever An experimental analysis is performed or A simulation model is developed.

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