• Title/Summary/Keyword: New Effective Temperature

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Influence of the Effective Thermal Thansport Length on the Heat Transfer Characteristics of a Liquid-Metal Heat Pipe for High-temperature Solar Thermal Devices (유효열이송거리가 고온 태양열기기용 액체금속 히트파이프의 열전달 특성에 미치는 영향)

  • Park, Cheol-Min;Boo, Joon-Hong;Kim, Jin-Soo;Kang, Yong-Heack
    • 한국태양에너지학회:학술대회논문집
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    • 2008.11a
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    • pp.220-225
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    • 2008
  • Cylindrical stainless-steel/sodium heat pipe for a high-temperature solar thermal application was manufactured and tested for transient and steady-state operations. Two layers of stainless-steel screen mesh wick was inserted as a capillary structure. The outer diameter of the heat pipe was 12.7 mm and the total length was 250 mm. The effective heat transport length, the thermal load, and the operating temperature were varied as thermal transport conditions of the heat pipe. The thermal load was supplied by an electric furnace up to 1kW and the cooling was performed by forced convection of air The effective thermal conductivity and the thermal resistance were investigated as a function of heat flux, heat transport length, and vapor temperature. Typical range of the total effective thermal conductivity was as low as 43,500 W/m K for heat flux of 176.4 kW/$m^2$ and of operating temperature of 1000 K.

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Estimating the cooling effect of see breeze along canals and outdoor thermal comfort on urban heat load in summer (해풍(海風)을 이용한 하계(夏季) 도시열환경(都市熱環境)의 풍도(風道)계획과 인체의 쾌적성에 관한 연구)

  • Jeong, Chang-Won;Yoon, In;Choi, Young-Sik
    • Journal of the Korean Society of Industry Convergence
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    • v.2 no.1
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    • pp.19-25
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    • 1999
  • A new urban design method from the viewpoint of climate is considered to be desired for urban life. The authors verified on an environmental planning based on new urban design concept which introduced the effect of sea breeze blowing along canals. The field observation of urban thermal environment were carried out to examine the cooling effects of a river through city. The observations were conducted to find the effect of a sea breeze and climate in summer along canals. Effective distance from the sea and cooling effect of the sea breeze on urban temperature was analyzed. The thermal index using outdoor environment was modified with New Effective Temperature ET*. On the basis of the observation. Human thermal comfort is relieved and affected by sea breeze blowing along canals. The canals were utilized as the trail on which sea breeze blows towards the center of city. From these results, The wind trail is one of the effective passive design method from the viewpoint of urban climate.

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Human Solar Heat Load and Thermal Comfort in an Outdoor Environment (건축외부공간에 있어서 인체의 일사열부하(日射熱負荷) 및 열적(熱的) 쾌적성(快適性)에 관한 실험적 연구)

  • Jeong, Chang-Won;Yoon, In
    • Journal of the Korean Society of Industry Convergence
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    • v.1 no.2
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    • pp.65-74
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    • 1998
  • The purpose of this paper is to investigate the mount of relief of human solar heat load and thermal comfort in outdoor environment in summer, Six different types of sites, T garden and its neighboring area in Japan, were selected as the experiment sites. The experiments were conducted from 22 to 29 August, 1994 to find the relationship between climatic conditions and human responses, Climatic conditions, subjects's thermal sensation and skin temperature were measured. Radiant heat exchange on the human body was estimated on the basis of the measured air and surface temperature and solar radiation. Thermal index Operative Temperature and New Effective Temperature was modified with the effect of the radiant heat exchange. Human thermal comfort and skin temperature is affected by the solar radiation and the sky factor in an outdoor environment. The effect of tree shade was verified on thermal comfort, The mount of relief of human solar heat load is relation to the existence of shade a solar radiation and the sky factor. The urban garden is one of the effective design element in an urban environmental planning.

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Impact of fuel temperature on nuclear core design calculations

  • Dusan Calic;Luka Snoj;Marjan Kromar
    • Nuclear Engineering and Technology
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    • v.56 no.9
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    • pp.3668-3685
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    • 2024
  • The operation of a nuclear power plant relies on precalculated nuclear design predictions based on core calculations of various reactor states. The fuel temperature is a crucial factor in determining the reactor fuel behavior, but assessing the temperature variation in a fuel pellet taking into account neutron transport is challenging. Detailed simulation of the temperature behavior within the fuel pellet can be obtained by coupling of Monte Carlo neutron transport codes with thermal-hydraulics solvers. However, this approach is not practical for standard nuclear design calculations, and computationally cheaper and faster methods must be used. In nuclear core simulators, a concept of a single "effective temperature" that yields the same neutron response as in the case of the actual temperature shape is mainly applied. This paper evaluates various fuel temperature models used in nuclear core simulation calculations, ultimately recommending a new effective temperature model that considers the burnup correction.

New vanadate-phosphate phosphors for lighting application

  • Toda, Kenji
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.125-126
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    • 2009
  • In this study, we report the room temperature synthesis and luminescence properties of white-light-emitting Rb(V,P)$O_3$. The vanadate phosphor, RbV$O_3$, was synthesized by simple mixing of $RbCO_3$ and $V_2O_5$ at room temperature in air. New direct room temperature solidstate reaction is a cost-effective method to synthesize the above luminescent materials.

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Evaluation of Korean Thermal Sensation in Office Buildings During the Summer Season (여름철 사무실내 한국인의 온열감 평가)

  • Bae, G.N.;Lee, C.H.;Lee, C.S.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.7 no.2
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    • pp.341-352
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    • 1995
  • In this study, thermal parameters were measured and 213 occupants were also questioned in three office buildings located in Seoul during the summer season. Predicted mean vote-predicted percentage of dissatisfied(PMV-PPD) and standard new effective temperature(SET*) were used for evaluating Korean thermal sensation. The distribution of thermal sensation vote(TSV) and percentage of dissatisfied(PD) is very similar to that of PMV and PPD. By regression analysis, the following regression equation was obtained; TSV=0.339SET*-8.583. In this case, neutral temperature and comfort range are $25.3^{\circ}C$, $23.8{\sim}26.8^{\circ}C$ respectively. Present experimental results obtained from the field study is less sensitive to the temperature change than those obtained from the climate chamber study in Korea. But, thermal sensations are similar to each other near the neutral point. The neutral temperature and comfort range obtained by this experiment are higher than those of ANSI/ASHRAE Standard 55-1974 about $1.4{\sim}1.8^{\circ}C$.

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A study on characteristics of thermal comfort for artificial environmental experiment in winter (동계 인공환경실험에 의한 온열쾌적특성 연구)

  • 박종일;김경훈;정성일
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.10 no.6
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    • pp.721-731
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    • 1998
  • Recently, many researchers are studying the relation between thermal environment and human comfort. The purpose of this study was to obtain basic data which are necessary to determine the thermal comfort sensation and physiological responses for men in winter indoor environment. From January to February 1998, subject experiment was 40 times proceeded under twenty different conditions of air temperature and relative humidity with early-twenty male university students. We examined subjective evaluation, Electrocardiogram(ECG), Electroencephalogram(EEG) of subjects. The results of this study can be summarized as follows : The comfort zone of people in winter was achieved at Standard new effective temperature($SET^*$) $ 25.2^{\circ}C$, PMV range was obtained by Fanger's statistical calculation was -0.27<PMV<+0.62, TSV range obtained subjects vote was -0.76<TSV<+0.36. The largest difference of skin temperature was found at the calf area as air temperature changes. vote rate of human body presented calflongrightarrowheadlongrightarrowforearmlongrightarrowchestlongrightarrowabdo men in turn. Heart rate was decreased at low $SET^*$ and heart rate was increased at high $SET^*$ But there was no change at EEG.

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Characteristics of Thermal Environments and Evaluation of Thermal Comfort in Office Building in Summer (여름철 사무실내 온열환경 특성 및 쾌적성 평가)

  • Lee, C.H.;Bae, G.N.;Choi, H.C.;Lee, C.S.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.6 no.3
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    • pp.206-217
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    • 1994
  • In this study, indoor thermal parameters were measured to investigate the characteristics of thermal environments and 212 occupants were questioned to evaluate Korean thermal comfort in office building in summer. Thermal and comfort sensations were estimated using PMV(Predicted Mean Vote) and ET* (New Effective Temperature) which are most widely used nowadays. Comparing this experimental result with international standards and that of other research, Korean thermal responses were discussed. It was found that TSV(Thermal Sensation Vote) is more sensitive than PMV to the variation of temperature and that the measured percentage of dissatisfied is higher than PPD(Predicted Percentage of Dissatisfied) in real office building environments. By regression analysis, the following regression equation has been obtained: TSV=0.461ET*-11.808 and neutral temperature is $25.6^{\circ}C$ in this case. Thermal comfort range based on 80% satisfaction is also $24.0{\sim}26.8^{\circ}C$, which is about $1^{\circ}C$ higher than that of ANSI/ASHRAE Standard.

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Characteristics of Thermal Comfort in Environment Chamber for Winter

  • Kim, Kyung-Hoon;Park, Jong-Il;Song, Yong-Gil
    • International Journal of Air-Conditioning and Refrigeration
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    • v.8 no.1
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    • pp.73-83
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    • 2000
  • The purpose of this study is to analyze and characterize the correlation of the thermal comfort sensation with physiological responses for men in winter indoor environment. A number of experiments were conducted under twenty different environmental conditions with college male students. Clinical information on each participant was reported in terms of electrocardiogram (ECG), electroencephalogram (EEG) and self-centered evaluation. The comfort zone in winter is found, throughout the study, at Standard New Effective Temperature (SET$T^+$) of 25.2$^{\circ}C$, Predicted Mean Vote (PMV) between 0.27 and 0.62, and Thermal Sensation Vote (TSV) in the range of -0.76 and 0.36. The largest difference in skin temperature is measured at the calf area with respect to air temperature changes. Skin sensitivity to environment temperature is explained as calf, head, chest and abdomen in descending order. Change in heat rate is analyzed to be in parallel with that of SET$T^+$.

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Performance Characteristics of a Liquid-Metal Heat Pipe for igh-temperature Solar Thermal Devices Depending on the Operating Conditions (고온 태양열기기용 액체금속 히트파이프의 작동조건에 따른 성능 특성)

  • Park, Cheol-Min;Lee, Jung-Ryun;Boo, Joon-Hong;Kang, Yong-Heack
    • 한국신재생에너지학회:학술대회논문집
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    • 2009.06a
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    • pp.247-250
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    • 2009
  • Sodium heat pipe for high-temperature solar thermal application was manufactured and tested for transient and steady-state operations. Total length of the heat pipe was 650 mm and the outer diameter was 12.7 mm. Thermal performance was compared experimentally for two different cooling methods of the forced and the natural convection cooling in the heat pipe condenser. During the experiment, the maximum temperature was about 1300K, and different cooling methods were applied to the condenser region to charge the operating temperature. The effective thermal conductivity and the thermal resistance were investigated as a function of heat flux, heat transport length, and operating temperature.

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