• 제목/요약/키워드: radiation cooling

검색결과 387건 처리시간 0.029초

복사 차폐막이 극저온 용기의 부하에 미치는 영향에 관한 실험적 연극 (An Experimental Study on the Effects of a Radiation Shield on the Thermal Load of a Cryochamber)

  • 김영민;박성제;강병하
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2005년도 동계학술발표대회 논문집
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    • pp.365-370
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    • 2005
  • Infrared (lR) detectors are widely used for such applications as thermoelstic stress analysis, medical diagnostics and temperature measurement. Infrared detectors commonly need to be refrigerated below 80 K, and thus a cooling system should be equipped together with the detector system. The cooling load, which should be removed by the cooling system to maintain the nominal operating temperature of the detector, critically depends on the insulation efficiency of the cryochamber housing the detector. Cryochamber considers the conduction heat transfer through a cold finger, the gases conduction and radiation heat transfer. The thermal loads of an infrared detector Cryochamber with radiation shield are investigated experimentally in present study. Since the effect of radiation heat transfer on thermal loads is significant, radiation shields is installed in the cold finger part to protect heat input through radiation. It is found that the thermal load can be substantially reduced by increasing the number of radiation shield.

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케로신을 연료로 하는 10톤급 액체로켓엔진의 냉각 기구에 관한 연구 (A Study on the Cooling Mechanism in Liquid Rocket Engine of 10tf-thrust Level using Kerosene as a Fuel)

  • 한풍규;조원국;조용호
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2003년도 제21회 추계학술대회 논문집
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    • pp.83-88
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    • 2003
  • 케로신과 액체 산소를 추진제로 하며, 10톤을 설계 추력으로 하는 우주 발사체의 2단용 액 체로켓엔진의 재생 냉각 특성 에 대한 해석적 연구를 수행하였다. 또한 보조적인 냉각 방법으로서 노즐 확장부에는 대기로의 복사 방열에 의한 냉각을 적용하였다. 본 연구를 통해, 케로신을 연료로 하는 10톤 추력의 2단용 액체로켓 엔진에서 재생 냉각과 복사 냉각에 의한 냉각 기구만으로는 냉각 방법으로 적합하지는 않다는 것을 확인하였다. 따라서 새로운 냉각 방법으로서 막냉각 기법이 도입되었으며, 액체로켓엔진의 열적 불안정성을 제거하는데 효과적인 냉각방법임을 알 수 있었다.

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복사 차폐막이 설치된 극저온 용기의 열부하 특성에 관한 실험적 연구 (An Experimental Study on the Thermal Load of a Cryochamber with Radiation Shields)

  • 김영민;강병하;박성제
    • 설비공학논문집
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    • 제20권1호
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    • pp.11-16
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    • 2008
  • Infrared (IR) detectors are widely used for such applications as thermoelastic stress analysis, medical diagnostics and temperature measurement. Infrared detectors commonly need to be refrigerated below 80 K, and thus a cooling system should be equipped together with the detector system. The cooling load, which should be removed by the cooling system to maintain the nominal operating temperature of the detector, critically depends on the insulation efficiency of the cryochamber housing the detector. Thermal load of a cryochamber is attributed to the conduction heat transfer through a cold finger, the gases conduction and radiation heat transfer. The thermal loads of an infrared detector cryochamber with a radiation shield are investigated experimentally in present study. Since the effect of radiation heat transfer on thermal loads is significant, radiation shields is installed in the cold finger part to protect heat input through radiation.

An Analysis on Building Shading Plan for a City Hall considering Energy Saving

  • Kim, Jin Lee;No, Sang Tae
    • KIEAE Journal
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    • 제16권2호
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    • pp.5-10
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    • 2016
  • Purpose: Recently, many public office buildings which were built by curtain wall increased rapidly, but the results of the investigation of the government, these buildings have been found that the heating and cooling thermal load is high, and showed low energy efficiency. Method: To evaluate the effects by applying outdoor louver and indoor blind, which can control solar radiation in order to reduce the heating and cooling load of public office building which was built by glass curtain wall. The heating and cooling load was calculated via Energyplus, building and outdoor louver, indoor blind were modeled by Google sketchup connected to Energyplus. Result: The results of this study were as follows; the case of applying various outdoor louver, the heating and cooling load all decreased as compared to the case without applying outdoor louver, the case of applying indoor blind, the heating and cooling load decreased as compared to the case without applying indoor blind, but indoor blind showed low energy performance comparing outdoor louver.

하절기 단일 수목의 열 환경 관측을 통한 서열완화 효과 해석 (Analysis of Passive Cooling Effect of the Tree by Field Observations in the Summer)

  • 최동호;이부용
    • 한국태양에너지학회 논문집
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    • 제26권4호
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    • pp.109-118
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    • 2006
  • The tree is regarded as an sustainable architectural outdoor design element which reduce urban heat island effect by its solar shading and evapotranspiration. This study carried out field observations of measuring thermal environment of selected tree and its ambience to determine passive cooling effects. Results from the field observations are as below; Tree-shading effect to the thermal environment can not be properly evaluated by merely measuring air temperature differences between tree-shaded space and unshaded space for the maximum temperature difference is less than $1.5^{\circ}C$. The differences of longwave radiation and shortwave radiation between tree-shaded space and unshaded space are measured. Shortwave radiation is considered as a main thermal comfort determining factor for the difference of the shortwave radiation is much bigger than that of longwave radiation. By thermal infrared image analysis, the surface temperature of the tree under strong solar radiation is measured same as ambient air temperature. By which the evapotranspiration is considered to retard tree surface temperature raising effectively.

여름철 일사를 고려한 투명 투과체 공간의 열환경 특성에 관한 사례연구 (A Case Study on Thermal Performance for Transparent Glazing Space Considering Solar Radiation in Summer)

  • 류영희;서혜수;이민정;남지연;송미나;전정윤
    • KIEAE Journal
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    • 제3권1호
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    • pp.31-36
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    • 2003
  • Recently, buildings with transparent glazing on exterior walls have increased. The transparent glazing on exterior walls gives an impression of opening through introducing external environment's elements to inside of the building, and has various merits and so on, but has defects in controling indoor environments. Especially, the excess of solar radiation in summer increases cooling load causing discomforts to occupants providing radiant environment with high temperature. Cooling load mainly depends on electricity comparing to heating load and intents to centralize specific time. So it is necessary to work out a countermeasure. In this study, showed P building with transparent glazing on exterior walls as a case, investigated indoor thermal performance, numerical analysis of P building in summer through comparing dry-sauna which is represented as radiant environment with high temperature. In the results of this study, transparent glazing space has radiant environment with high temperature such as dry-sauna because of the excess of solar radiation. Accordingly countermeasures are considered in building planning. As concrete methods, there are adiabatic effects using double glazing, use of sunscreen, blind, ventilation facilitation using natural draft, decrease of surface temperature through evaporation cooling and cooling coils.

케로신과 액체산소를 추진제로 하는 10톤급 액체로켓엔진의 재생냉각 특성 평가 (Evaluation on the Regenerative Cooling Characteristics in Liquid Rocket Engine of 10tf-thrust using Kerosene and Liquid Oxygen as a Propellant)

  • 한풍규;조원국;조용호
    • 한국항공우주학회지
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    • 제32권4호
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    • pp.111-117
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    • 2004
  • 케로신과 액체산소를 추진제로 하며, 10톤을 설계 추력으로 하는 우주 발사체의 2단용 액체로켓엔진의 재생 냉각 특성에 대한 해석적 연구를 수행하였다. 또한 보조적인 냉각 방법으로서 노즐 확장부에는 대기로의 복사 방열에 의한 냉각을 적용하였다. 본 연구를 통해, 케로신을 연료로 하는 10톤 추력의 2단용 액체로켓엔진에서 재생냉각과 복사 냉각에 의한 냉각 기구만으로는 소재의 열 및 열구조적인 불안정성과 냉각채널에서의 과다한 압력강하에 의해 적합하지 않다는 것을 확인하였다.

하절기 복사환경 관측을 통한 수목과 일사차폐 막 구조물의 자연냉각효과 (Analysis of Passive Cooling Effect of Membrane Shading Structure and the Tree by Field Observations in the Summer)

  • 최동호;이부용
    • 한국태양에너지학회 논문집
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    • 제27권4호
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    • pp.137-146
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    • 2007
  • This study is about the passive cooling effects of three outdoor solar shading facilities as trees, pergola with wistaria vine and membrane shading structure, which are expected to provide cool spots in the summer. Field observations of measuring thermal environment of selected facilities is executed. Thermal environment measuring was categorized as short wave radiation, long wave radiation, net radiation, globe temperature, surface temperature measured by infrared camera. Heat transfer mechanism is analyzed with overall data from field measurement. Results from this study are as below; 1) Radiation balance measured on shaded surface under membrane shading structure was 17%($86W/m^2$) of the unshaded surface radiation balance($511W/m^2$). 2) Surface temperature comparison between vegetation and membrane of the shading structure is performed at 3 o'clock in the afternoon. Surface temperature of vegetation was same as air temperature and that of membrane was $5^{\circ}C$ higher than air temperature. Vegetation transpiration is considered as the causing factor which make those differences. 3) Results from this study could be used as fundamental data for reducing heat island phenomena and continuos research on this subject would be needed.

동도금 EP방열판에 의한 소형LED조명등 방열 (Heat Radiation of LED Light using eu Plating Engineering Plastic Heat Sink)

  • 조영태
    • 한국생산제조학회지
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    • 제20권1호
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    • pp.81-85
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    • 2011
  • Recently, the electronic parts are to be thinner plate, smaller size, light weight material and CPU, HDD and DRAM in all the parts have been produced on the basis of the high speed and greater capacity. Also, conventional goods have replaced a LED (Light-Emitting Diode) in lighting products so; such industry devices need to have cooling. To maximize all the performance on the heat-radiated products, the area of heat-radiated parts is required to be cooled for keeping the life time extension and performance of product up. Existing cooling systems are using radiant heat plate of aluminum, brass by extrusion molding, heat pipe or hydro-cooling system for cooling. There is a limitation for bringing the light weight of product, cost reduction, molding of the cooling system. So it is proposed that an alternative way was made for bringing to the cooling system. EP (Engineering Plastic) of low-cost ABS (Acrylonitrile butadiene styrene Resin) and PC (Polycarbonate) was coated with brass and the coating made the radiated heat go up. The performance of radiant heat plate is the similar to the existing part. We have studied experimentally on the radiated heat plate for the light-weight, molding improvement and low-cost. From now on, we are going to develop the way to replace the exiting plate with exterior surface of product as a cooling system.

대구의 여름철 야간 냉각량과 기상요소와의 관련성 연구 (A Study on the Relationship between the Summertime Night Cooling Rate and Meteorological Elements in Daegu)

  • 김하영;김해동
    • 한국환경과학회지
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    • 제30권10호
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    • pp.821-831
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    • 2021
  • The relationship between night cooling rate and meteorological elements was investigated over the past five years (2016-2020), using weather data from the new (Daegu(143)) and old (Shinam(860)) Daegu Regional Meteorological Agency located in the suburban and urban regions, respectively. There was a correlation between the total daily amount of solar radiation (Stot) and the night cooling rate in the both regions. However, a higher correlation was observed at the new Daegu Regional Meteorological Agency station (Daegu(143)). In particular, data from the new Daegu Regional Meteorological Administration's observatory, which experiences a low thermal storage effect caused by artificial structures, showed a higher correlation between nighttime cooling and weather factors. The reason for this is that the lesser the heat storage effect caused by the artificial structures, the better the effect of surface radiation cooling on temperature reduction. These findings confirm that the correlation between night cooling and weather factors can be used to assess the impact of artificial structures in cities.