• Title/Summary/Keyword: 밸브성능

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Design and Performance Test of a Closed Loop Thermal Control System for Thermal Vacuum Chamber (열진공 챔버용 폐회로 열제어시스템 설계 및 성능평가)

  • Seo, Heejun;Cho, Hyokjin;Park, Sungwook;Moon, Gueewon;Jung, Sanghun;Huh, Hwanil
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.1
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    • pp.88-97
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    • 2016
  • A closed loop thermal control system simulates space thermal environment to verify the satellites' functionality in extremely cold/hot temperature. It is composed of a cryogenic blower, thermal shroud, heater, cryogenic valves. This paper presents an overview of closed loop thermal control system's design parameter and test results for control parameter. A capacity of blower is calculated through energy balance equation and an advantage/disadvantage for a shroud material and a type was analysed. The thermal control system is controlled by a constant density of fluid in the system. A requested performance of closed loop thermal control system was verified by measuring a homogeneity and stability of shroud through control parameter such as density and RPM of blower.

A Study on Performance Characteristics of a Dehumidifier with Multi-layer Type Heat Exchangers Varying Frontal Air Velocity (다층형 열교환기를 이용한 제습기의 전면 풍속 변화에 따른 성능 특성에 관한 연구)

  • Ku, Hak-Keun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.7
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    • pp.2323-2327
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    • 2010
  • The experimental apparatus consists of dehumidifier with multi-layer type heat exchangers to remove the moisture from automatic equipments, semiconductors, and manufacturing processes under the low temperature environment, and chemical production lines which are likely to take moisture. The major components of this system are four evaporators with different fin pitch, two compressors, two condensers and an expansion valve. In this study, the performance characteristics of dehumidifier is analyzed by the variations of frontal air velocity in the first heat exchanger(evaporator). The cooling capacity of each heat exchanger is acquired by the enthalpy calculating from measuring point of temperature and relative humidity of the first heat exchanger from 1.0m/s to 4.0m/s with increasing interval 0.5m/s, and the front air velocity. As a result, it is found that cooling capacity of the first heat exchanger showed the best cooling capacity when its frontal air velocity is 2.0 m/s.

Study on improvement of efficiency of gas filter at the natural gas valve station (천연가스 공급기지내 가스필터 성능개선에 관한 연구)

  • Cho Y.B.;Jeon K.S.;Her J.Y.;You K.H.
    • Journal of the Korean Institute of Gas
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    • v.2 no.1
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    • pp.47-52
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    • 1998
  • To eliminate foreign substance like metal rust and sand in natural gas pipeline, 250um strainer filter is used present in Korea Gas Corporation. But particles smaller than 250um passing the filter have bad effects to the valves and the measuring equipments. In order to eliminate small paticle in the pipeline, it is necessary to cut down the pore size of filter When we cut down the pore size of filter, the pressure difference between the front of filter and that of the rear part is increasing and disturb normal condition of gas supply. So it is very important to control the condition between the pore size of filter and the pressure difference. In this study, using head loss coefficient K, the estimation method of efficiency of gas filter according to the pore size and the pressure difference is presented.

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A Study on the Performance Characteristics of the Soft Ice Cream Machine Run by Refrigerant Mixture (R-290/R-32) (혼합냉매(R-290/R-32)를 사용하는 소프트 아이스크림 제조기의 성능 특성에 관한 연구)

  • Kim, Nea-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.2
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    • pp.719-725
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    • 2017
  • Frozen milk products are commonly made in small refrigeration machines. R-502 has long been used as a refrigerant for soft ice cream machines, but it is being replaced with R-404A due to the issue of ozone layer depletion. However, R-404A has high global warming potential, so it also needs to be replaced. In this study, a mixture of R-290 and R-32 was considered as a new refrigerant. An optimization and performance evaluation of the mixture were conducted for a freezer volume of 2.8 liters. The focus of the optimization was the appropriate refrigerant charge and the opening of the expansion valve. At the optimized conditions, ice cream was produced in 6 minutes and 24 seconds with the mixture, and the COP was 0.83. For R-404A, the ice cream production time was 6 minutes and 22 seconds, and the COP was 0.90. The results may be used for the design of food refrigeration machines and to optimize other refrigeration cycles.

Development and Performance Test of Gas Safety Management System based on the Ubiquitous Home (u-home 가스안전관리시스템 개발 및 성능시험)

  • Park, Gyou-Tae;Lyu, Geun-Jun;Kim, Young-Gyu;Kim, Yeong-Dae;Jee, Cha-Wan;Kwon, Jong-Won;Kim, Hie-Sik
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.48 no.3
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    • pp.13-20
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    • 2011
  • In this paper, we proposed a system to raise gas safety management by using the wireless communication module and intelligent gas safety appliances. Our designed systems configure a micom-gas meter, an automatic extinguisher, sensors, and a wallpad. A micom-gas-meter monitors gas flow, gas pressure, and earthquake. An automatic fire extinguisher checks gas(combustible) leaks and temperature of $100^{\circ}C$ and $130^{\circ}C$. Sensors measure smoke and CO gas. In our novel system, a micom-gas meter cut off inner valve with warnings, an automatic fire extinguisher cut off middle valve and spray extinguishing materials, and sensors generate signals for smoke and CO when occurring gas risk. Gas safety appliances and sensors takes safety measures, and transmit those signal to a wallpad. The wallpad again transmit signal like events to a control server. Users can connect web pages for gas safety through B-ISDN and control and manage them. We hereby devised scenarios for gas safety and risk management, and demonstrated their effectiveness through experiments.

A Study of the Fluidic Characteristics of High-Pressure Fuel Pumps for GDI Engines (GDI 고압펌프의 유동특성에 관한 연구)

  • Lee, Sangjin;Noh, Yoojeong;Liu, Hao;Lee, Jae-Cheon;Shin, Yongnam;Park, Yongduk;Kang, Myungkweon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.39 no.5
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    • pp.455-461
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    • 2015
  • A high-pressure fuel pump is a key component in a gasoline direct injection (GDI) engine; thus, understanding its flow characteristics is essential for improving the engine power and fuel efficiency. In this study, AMESim, which is a hydraulic analysis program, was used to analyze the performance of the high-pressure fuel pump. However, since AMESim uses a one-dimensional model for the system analysis, it does not accurately analyze the complicated flow characteristics. Thus, Fluent, computational fluid dynamics (CFD) software, was used to calculate the flow rates and net forces at the intake and discharge ports of the high-pressure fuel pump where turbulent flow occurs. The CFD analysis results for various pressure conditions and valve lifts were used as look-up tables for the AMEsim model. The CFD analysis results complemented the AMEsim results, and thus, improved the accuracy of the performance analysis results for the high-pressure fuel pump.

FEA(Finite Element Analysis) Study for Electronic Hydrogen Regulator of Confidentiality Improvement (전자식 수소레귤레이터 기밀성 향상을 위한 FEA 연구)

  • Son, Won-Sik;Song, Jae-Wook;Jeon, Wan-Jae;Kim, Seung-Mo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.9
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    • pp.175-181
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    • 2019
  • In the case of a conventional single stage decompression regulator used for large depressurization in the hydrogen fuel cell system of a fuel cell electric vehicle (FCEV), problems can arise, such as pulsation, slow response, hydrogen brittleness, leakage, high weight, and high cost due to high decompression. Most of these problems can be overcome easily using two decompression mechanisms (two-stage structures). In addition, a wide outlet-pressure control range can be secured if an electronic solenoid is applied to the second decompression. Accordingly, it is necessary to improve the precision of the outlet pressure of a two-stage pressure-reducing regulator and develop techniques, such as leakage prevention, durability, light weight, and price reduction. Therefore, to improve the outlet pressure accuracy and prevent leakage, the structural part before and after decompression to improve the air tightness were divided and the analysis was carried out assuming that the valve part was closed (open ratio: 0%) after each initial internal pressure application.

Development of Decompressed Dryer for Mushroom (버섯의 감압건조기 개발)

  • 김영민;김유호;조영길;최희석;조광환
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • 2003.07a
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    • pp.267-272
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    • 2003
  • 본 연구에서는 버섯의 건조시간을 줄여 건조 후 버섯의 품질을 향상시키기 위하여 버섯의 감압건조기를 개발하였으며 연구 결과는 다음과 같다. 가. 버섯의 감압건조기의 시작기를 제작하였고, 시작기의 구조는 건조실, 감압블로워, 흡ㆍ배기구 솔레노이드 밸브, 제습장치, 송풍기, 전기히터로 구성되어 있으며, 건조실의 내부 압력이 표준대기압-900hPa, 열풍온도는 상온에서 5$0^{\circ}C$까지 조절할 수 있도록 제작하였다. 나. 시작기를 이용하여 표고버섯을 대상으로 건조특성시험을 실시한 결과, 열풍온도 5$0^{\circ}C$, 건조실 내부압력 900-940hPa에서 건조시간은 11.5h으로 대기압과 비교하여 6.5h 단축되는 것으로 나타났다. 또한, 건조 전ㆍ후의 색차, 수축률, 복원률의 품위가 우수한 것으로 나타났으며 F-test 유의성 검증 결과, 5%의 유의수준에서 갓주름의 색차, 갓직경의 수축률, 복원률에서 유의차가 있는 것으로 나타났다. 다. 열풍온도 5$0^{\circ}C$, 건조실 내부압력 900-940hPa로 표고버섯과 아가리쿠스에 대하여 건조성능시험을 실시한 결과, 표고버섯의 경우 건조시간은 13h으로 열풍식 농산물 건조기와 비교하여 건조시간이 4.5h 단축되는 것으로 나타났으며, 아가리쿠스의 경우 건조시간이 17.5h로 나타났다. 라. 성능시험 결과, 시작기가 열풍식 농산물건조기와 비교하여 건감률, 색택, 수축률, 복원률 등의 품위가 전반적으로 우수한 것으로 나타났다. 마. 시작기의 건조비용을 분석한 결과, 건조시간은 단축되었지만 시설투자비가 높아 건조비용이 표고버섯의 경우 2,461원/kg으로 열풍식 농산물건조기 보다 13% 높은 것으로 나타났지만, 추후 고품질 건조버섯 생산을 위한 기초자료로 활용이 가능할 것으로 판단된다.라갈수록 낮은 온도분포를 나타내고 있는 것은 상부에는 외부공기가 유입되면서 온도가 떨어지는 반면 하부에는 외부공기 유입이 적기 때문으로 사료된다. 또한 열풍실의 길이방향 위치별 온도 분포에서도 같은 현상으로 나타났고, 버너쪽과 송풍기쪽의 온도편차는 나타나지 않아 균일 건조를 기대할 수 있다. 마. 열풍온도를 45$^{\circ}C$로 설정하고 조사거리와 방사체 길이를 각각 119, 1,470mm로 하여 벼의 건조성능시험을 열풍건조기(대비구)와 비교시험 결과 시험구에서 건감률, 건조소요에너지가 각각 0.58%(w.b.), 470kcal/kg - water로 대비구보다 각각 건감율은 23% 높았고, 건조소요에너지는 2%의 절감되었다. 바. 건조기에서 발생되는 소음은 버너쪽 근처에서는 대비구 94.12㏈의 87%에 불과하였으나, 거리가 멀어질수록 차이는 크지 않았다. 이것은 버너에서 멀어질수록 외부적인 요인이 소음에 영향을 미쳤기 때문인 것으로 생각된다. 사. 시작기와 대비구간의 경제성에서 시작기의 구입가격이 20% 비싸기 때문에 시간당 고정비가 높았으나, 건조성능이 우수하여 건조비용이 69,350원/톤으로 대비구보다 14% 절감되는 것으로 나타났다.작용하는 것으로 사료된다.된다.정량 분석한 결과이다. 시편의 조성은 33.6 at% U, 66.4 at% O의 결과를 얻었다. 산화물 핵연료의 표면 관찰 및 정량 분석 시험시 시편 표면을 전도성 물질로 증착시키지 않고, Silver Paint 에 시편을 접착하는 방법으로도 만족한 시험 결과를 얻을 수 있었다.째, 회복기 중에 일어나는 입자들의 유입은 자기폭풍의 지속시간을 연장시키는 경향을 보이며 큰 자기폭풍일수록 현저했다. 주상에서 관측된 이러한 특성은 서브스톰 확장기 활동이 자기폭풍의 발달과 밀접한 관계가 있음을 시사한다.se that were all

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Effect of Hydrogen Purge Mode on the Polymer Electrolyte Membrane Fuel Cell (PEMFC) Performance under Dead-ended Anode Operation (양극 닫힌계 작동에서 수소 배출 방법에 의한 고분자전해질 연료전지 성능 영향)

  • Kim, Junseob;Kim, Junbom
    • Applied Chemistry for Engineering
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    • v.30 no.6
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    • pp.687-693
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    • 2019
  • As the hydrogen fuel cell market is expanded starting from hydrogen electric vehicle and power generation field, the demand for fuel cells and hydrogen increases recently. Therefore, research works on fuel cell durability and fuel efficiency are required in order to activate the fuel cell market and commercialization. A dead-ended anode system was used in this study to optimize the fuel cell performance and fuel efficiency. The effect of purge condition according to the applied current and hydrogen supply pressure on the fuel cell performance were evaluated. In addition, the influence of water back diffusion on the different electrolyte membrane thickness was analyzed. The accumulated water was purged with a solenoid valve in the case of 3% voltage decrease in the dead-ended anode system. The experiment was performed with the hydrogen supply pressure of 0.1~0.5 bar and purge duration of 0.1~1 second. A maximum fuel efficiency of 98.9% was achieved under the purge duration of 0.1 s and hydrogen supply pressure of 0.1 bar with a NR 211 (25.4 um) membrane. However, the fuel cell performance decreased in a long-term operation due to some frequent flooding. The fuel efficiency and purge interval increased due to decreased back diffusion rates of the water and nitrogen with a NR 212 (50.8 um) membrane.

A Case Study on the Risk Analysis for the Installation of Measurement Error Verification Facility in Hydrogen Refueling Station (수소 충전소 계량오차 검증 설비 설치를 위한 위험성 분석 사례 연구)

  • Hwayoung, Lee;Hyeonwoo, Jang;Minkyung, Lee;Jeonghwan, Kim;Jaehun, Lee
    • Journal of the Korean Institute of Gas
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    • v.26 no.6
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    • pp.30-36
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    • 2022
  • In commercial transactions of energy sources using hydrogen charging stations, high-accuracy flow meters are needed to prevent accidents such as overcharging due to inaccurate measurements and to ensure transparency in hydrogen commercial transactions through accurate measurements. This research developed a Corioli-type flowmeter prototype and conducted a risk assessment to prevent accidents during a process change comparison experiment for existing charging stations to verify the measurement performance. A process change section was defined for the installation of measurement facilities for empirical experiments and HAZOP was conducted. In addition, JSA was also conducted to secure the safety of experimenters, such as preventing valve mis-opening during empirical experiments. Measures were established to improve the risk factors derived through HAZOP, and work procedures were established to minimize human errors and ensure the safety of workers through JSA. The design change and system manufacturing for the installation of the metering system were completed by reflecting the risk assessment results, and safety could be confirmed through the performance comparison test of the developed meter prototype. The developed prototype flow meter showed a total of 30 flow measurements under the operating conditions of 70 MPa, and the average error was -1.58% to 3.96%. Such a metering error was analyzed to have the same performance as a flow meter installed and operated for commercial use.