• Title/Summary/Keyword: Thermal Radiation Analysis

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Thermal Analysis of a Cryochamber for an Infrared Detector Considering a Radiation Shield (적외선 검출기용 극저온 챔버에서 복사 차폐막을 고려한 열해석)

  • Kim Young-Min;Kang Byung-Ha
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.8
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    • pp.672-677
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    • 2006
  • The steady cooling characteristics of a cryochamber for infrared (IR) detector have been investigated analytically, considering radiation shields. The thermal modeling considers the conduction heat transfer through cold finger, the gaseous conduction due to out-gassing, and the radiation heat transfer. The cooling load of the cryochamber is obtained by using a fin equation. The results obtained indicate that the gaseous conduction plays an important role in determining the steady cooling load. The steady cooling load is increased as the gas pressure is increased. It is also found that the cooling load is substantially decreased with a radiation shield. The most thermal load of a cryochamber occurs through the cold finger.

Analysis of Transient Heat Transfer Characteristics of a Receiver for a Dish Type Solar Thermal System by using CFD (CFD를 이용한 접시형 태양열 집열기의 Transient 열전달 성능 해석)

  • Oh, Sang-June;Lee, Ju-Han;Seo, Joo-Hyun;Lee, Jin-Gyu;Cho, Hyun-Seok;Seo, Tae-Beom
    • 한국신재생에너지학회:학술대회논문집
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    • 2008.10a
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    • pp.167-170
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    • 2008
  • A numerical and experimental studies are carried out to investigate the transient heat transfer characteristics of 5kWth dish type solar air receiver. Measured solar radiation and temperatures at several different locations are used as boundary conditions for numerical simulation. Many parameters' effects (reflectivity of the reflector, the thermal conductivity of the receiver body, transmissivity of the quartz window, etc.) on the thermal performance are investigated. Discrete Transfer Method is used to calculate the radiation heat exchange in the receiver. A transient heat transfer model is developed and the rate of radiation, convection and conduction heat transfer are calculated. Comparing the experimental and numerical results, good agreement is obtained. Using the numerical model, the transient heat transfer characteristics of volumetric air receiver for dish type solar thermal systems are known and the transient thermal performance of the receiver can be estimated.

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Numerical Study on the Thermal Design of Lunar Terrain Imager System Loaded on the Korea Pathfinder Lunar Orbiter (시험용 달 궤도선의 광학탑재체 시스템 열설계에 대한 수치해석적 연구)

  • Kim, Taig Young;Chang, Su-Young;Heo, Haeng-Pal
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.4
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    • pp.309-318
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    • 2019
  • The thermal design of the Lunar Terrain Imager (LUTI) on the Korean Pathfinder Lunar Orbiter (KPLO) was performed and the soundness of the thermal design was verified by thermal analysis. The thermal environment of the lunar mission orbit should be reflected in the thermal design because the IR radiation of the lunar surface is important, unlike the earth orbit. The components or modules exposed to the outside of the satellite are insulated with MLI as much as possible, but the camera tube and the radiator are functionally exposed, so the thermal shield using the concept of radiation shape factor is mounted on the front to mitigate IR radiation. The IR emissivity is important in the front side of the radiator that receives little solar radiation, and components that are susceptible to thermal deformation such as the tube use a radiation heater to minimize the temperature gradient. Through the investigation of computational results, it was confirmed that the thermal design of LUTI is stable in various situations.

Analysis of Maximum Solar Radiation on Inclined Surfaces in Korea (국내 최대 경사면일사량 분석)

  • Jo, Dok-Ki;Yun, Chang-Yeol;Kim, Kwang-Deuk;Kang, Young-Heack
    • 한국태양에너지학회:학술대회논문집
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    • 2009.04a
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    • pp.3-7
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    • 2009
  • The amount of incident rays over inclination according to direction has been widely utilized as important data in installing solar thermal systems. To optimize the incident solar radiation, the slope, that is the angle between the plane surface in question and the horizontal, and the solar azimuth angles are needed for these solar thermal systems. This is because the performance of the solar thermal systems in much affected by angle and direction of incident rays. Recognizing that factors mentioned above are of importance, actual experiment on the moving route of the sun have been performed in this research to obtain the angle of inclination with which the maximum incident rays can be absorbed. After all, the standard for designing highly optimized solar thermal systems will be provided for designers and employees working in the solar collector related industries.

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Temperature variation in steel beams subjected to thermal loads

  • Abid, Sallal R.
    • Steel and Composite Structures
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    • v.34 no.6
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    • pp.819-835
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    • 2020
  • The effects of atmospheric thermal loads on the response of structural elements that are exposed to open environments have been recognized by research works and design specifications. The main source of atmospheric heat is solar radiation, which dominates the variation of the temperature of air, earth surface and all exposed objects. The temperature distribution along the depth of steel members may differ with the geometry configuration, which means that the different-configuration steel members may suffer different thermally induced strains and stresses. In this research, an experimental steel beam was instrumented with many thermocouples in addition to other sensors. Surface temperatures, air temperature, solar radiation and wind speed measurements were recorded continuously for 21 summer days. Based on a finite element thermal analysis, which was verified using the experimental records, several parametric studies were directed to investigate the effect of the geometrical parameters of AISC standard steel sections on their thermal response. The results showed that the overall size of the beam, its depth and the thickness of its elements are of significant effect on vertical temperature distributions and temperature differences.

Analysis Thermal Performance of PV/Thermal Collector with Dye-sensitized Solar Cell Module (염료감응형태양전지 모듈 적용 PVT 집열기의 열적 성능 분석)

  • Jang, Han-Bin;Mun, Jong-Hyeok;Gang, Jun-Gu;Kim, Jin-Hui;Kim, Jun-Tae
    • Proceedings of the Korean Society for Emotion and Sensibility Conference
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    • 2009.11a
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    • pp.273-276
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    • 2009
  • Photovoltaic-thermal(PVT) collectors are a combination of photovoltaic modules with solar thermal collectors, forming one device that receives solar radiation and produces electricity and heat simultaneously. Of various PV modules, dye-sensitized solar cell(DSC) is a relatively new type of solar cell technology that can transmit light while they can generate electricity. With this aspect, DSC can be applied into solar thermal collectors. The object of this study is to evaluate the thermal performance of PVT collector with DSC. The thermal performance of the DSC PVT combind collector was measured in outdoor conditions with the solar radiation of over $700W/m^2$. In this study, the PVT collector with the 30% light transmittance of DSC achieved its thermal efficiency of about 36%.

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Characterization of Electron Beam Cured Epoxy Acrylate (에폭시 아크릴레이트의 전자선 영향 평가)

  • Shin, Jin-Wook;Oh, Byung-Hwan;Ko, Keum-Jin;Jeun, Joon Pyo;Kang, Phil Hyun
    • Journal of Radiation Industry
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    • v.4 no.3
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    • pp.271-276
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    • 2010
  • Epoxy resin has wide application in various industrial fields because of their good mechanical strength, superiority adhesion and low shrinkage etc. And the typical curing method for epoxy resins is thermal and press compaction. However, a curing method was used electron beam process in this study. Epoxy acrylate was fabricated from mixture of epoxy, acrylic acid, tetraphenylporphyrin (TPP) and hydroquinone monomethyl ether (MEHQ) with mole ratios. Then electron beam irradiation effect on the curing of the epoxy acrylate resin was investigated various absorption dose in nitrogen atmospheres at room temperature. The dynamic mechanical and thermal properties of the irradiated epoxy acrylate resins were characterized using dynamic mechanical analysis (DMA) and thermogravimetric analyzer (TGA). And the tensile and flexural strength were measured by an universal tensile machine (UTM).

γ-ray Radiation Induced Synthesis and Characterization of α-Cobalt Hydroxide Nanoparticles

  • Kim, Sang-Wook;Kwon, Bob-Jin;Park, Jeong-Hoon;Hur, Min-Goo;Yang, Seung-Dae;Jung, Hyun
    • Bulletin of the Korean Chemical Society
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    • v.31 no.4
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    • pp.910-914
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    • 2010
  • A novel synthetic route has been developed to prepare $\alpha$-cobalt hydroxide with intercalated nitrate anions. It was successfully synthesized by $\gamma$-ray irradiation under simple conditions, i.e., air atmosphere, without base. Under $\gamma$-ray irradiation, it leads to the formation of layered cobalt hydroxynitrate compounds which have small crystalline size and have the role of a generator of hydroxyl anion. Structural and morphological characterizations were performed by using power X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and high resolution transmission electron microscopy (HR-TEM). The component and thermal stability of the sample were respectively measured by Fourier transform infrared (FT-IR) spectroscopy, elemental analysis, and thermal analyses, including thermogravimetry (TG) and differential thermal analysis (DTA).

Heat and mass transfer of a second grade magnetohydrodynamic fluid over a convectively heated stretching sheet

  • Das, Kalidas;Sharma, Ram Prakash;Sarkar, Amit
    • Journal of Computational Design and Engineering
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    • v.3 no.4
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    • pp.330-336
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    • 2016
  • The present work is concerned with heat and mass transfer of an electrically conducting second grade MHD fluid past a semi-infinite stretching sheet with convective surface heat flux. The analysis accounts for thermophoresis and thermal radiation. A similarity transformations is used to reduce the governing equations into a dimensionless form. The local similarity equations are derived and solved using Nachtsheim-Swigert shooting iteration technique together with Runge-Kutta sixth order integration scheme. Results for various flow characteristics are presented through graphs and tables delineating the effect of various parameters characterizing the flow. Our analysis explores that the rate of heat transfer enhances with increasing the values of the surface convection parameter. Also the fluid velocity and temperature in the boundary layer region rise significantly for increasing the values of thermal radiation parameter.

The Effect of the Materials of an Outer Wall and the Paved Street on Human Thermal Comfort in a Housing Complex in Pohang City (포항시의 집합 주거공간에 있어서 외장재 및 도로 구성재료가 인체 온열 쾌적성에 미치는 영향)

  • Jeong, Chang-Won;Kim, Kyung-Dae;Choi, Young-Sik
    • Journal of the Korean Society of Industry Convergence
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    • v.4 no.3
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    • pp.319-327
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    • 2001
  • The objective of this study is to clarify the effect of thermal radiation environments on human thermal comfort, depending on different canyon types and surface materials on the human thermal comfort in a housing complex in Pohang city, Korea. For this purpose, the operative temperature and new effective temperature were calculated based on the modified mean radiant temperature of canyon models variated by the existence of direct radiation existence, surface materials, and the width and length of the street spaces in a housing complex. These indices for the canyon have been calculated from the meteorological data of Pohang city, which include air temperature, relative humidity, air velocity, global solar radiation and cloud. And the monthly averages of these climate factors measured at noon have been used. The results are as follows: (1) It is revealed that the short-wave radiosity reached the human body is affected by direct solar radiation and surface materials, and the long-wave radiosity by canyon types. (2) The existence of direct solar radiation, the kinds of surface materials and canyon types affect operative temperature($OT_n$) and new effective temperature($ET^*{_n}$). (3) The analysis of the human heat balance in the canyon indicates that the influence of radiation on human body is marc likely to be affected by the existence of direct solar radiation on human model.

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