• Title/Summary/Keyword: distribution of temperature

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Simulation for Improvement of Temperature Distribution Inside Refrigerator (냉장고 고내 온도산포 개선에 관한 전산모사)

  • Gao, Jia-Chen;Kim, Jae-Yeol
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.18 no.12
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    • pp.98-103
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    • 2019
  • With the increasing need for environmental protection, it is particularly important to improve the energy saving and reliability of refrigerators. Generally, the cold air flowing into the freezer compartment transits to the bottom of the refrigerating compartment, which can lead to uneven temperature distribution. This paper proposes two design solutions for improving the temperature distribution problem. Of these, the optimal refrigeration design was selected and tested using Computational Fluid Dynamics (CFD) modeling and simulation. The results showed improved uniformity of the temperature distribution inside the refrigerator, thus benefitting food storage while reducing energy consumption.

The Effect of Various Processing Conditions on Temperature Distribution in Steam-air Retort (스팀-에어 레토르트의 온도분포에 미치는 공정 변수 영향)

  • Lee, Sun-Young;Shin, Hae-Hun;In, Ye-Won;Cho, Hyung-Yong
    • Food Engineering Progress
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    • v.23 no.2
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    • pp.87-93
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    • 2019
  • Temperature distribution studies were performed in steam-air retort to investigate the influence of various processing conditions (come-up time, sterilization temperature, and internal pressure throughout the steam-air retort). Retort temperature data were analyzed for temperature deviations during holding phase, maximum temperature difference between test locations at the beginning and after 1, 3, and 5 min of the holding phase, and box-and-whiskers plots for each location during the holding phase. The results showed that high sterilization temperature led to a more uniform temperature distribution than low sterilization temperature (pasteurization). In pasteurization condition, the temperature stability was slightly increased by increasing pressure during the holding phase. On the other hand, the temperature stability was slightly decreased in high sterilization temperature condition. Programming of the come-up phase did not affect the temperature uniformity. In addition, the slowest cold spot was found at the bottom floor during the holding phase in all conditions. This study determined that the temperature distribution is affected by retort processing conditions, but the steam-air retort needs more validation tests for temperature stability.

Observational Study of Thermal Characteristics by Distribution Ratio of Green Area at Urban in Summer Season (하절기 관측을 통한 도시의 지역별 공간녹지분포율에 따른 열환경 특성 연구)

  • Jung, Im-Soo;Choi, Dong-Ho;Lee, Bu-Yong
    • Journal of the Korean Solar Energy Society
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    • v.31 no.3
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    • pp.8-16
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    • 2011
  • The objective of this study is to analyze the characteristic of thermal environment in the summer season by conducting the field observation of temperature, relative humidity, and globe temperature in some parts of the city. Observation point was divided to a densely populated area, a residential area, a green area, a waterfront green area and a suburban district by the distribution ratio of green area. In this study, the correlation between maximum temperature and globe temperature, study on index for intensity of the tropical night and the temperature distribution characteristic of measurement points by the distribution ratio of green area were analyzed. The results of this study are as follows. (1) The difference between temperature and globe temperature by the distribution ratio of green area is confirmed. The difference of nighttime is more clearly that of daytime. (2) The average temperature and globe temperature of the densely populated area($29.2^{\circ}C$, $33.7^{\circ}C$) are higher than that of the waterfront green area($27.9^{\circ}C$, $32.0^{\circ}C$) by $1.3^{\circ}C$ and $1.7^{\circ}C$, respectively. (3) The number of tropical nights has different days of tropical nights by the distribution ratio of green area of 17days for the Daegu weather station, 14days for adensely populated area, 14days for a residential area, 6days for a green area, 2days for a waterfront green area, and 2days for a suburban district. (4) The results of the slope of trend line for the effects of the temperature on globe temperature change and the intercept for the size of the impact of radiant energy gained around by the analysis of the correlation between the maximum temperature and globe temperature can be utilized objective evaluation index of the each point's artificial effects.

Impact of axial power distribution on thermal-hydraulic characteristics for thermionic reactor

  • Dai, Zhiwen;Wang, Chenglong;Zhang, Dalin;Tian, Wenxi;Qiu, Suizheng;Su, G.H.
    • Nuclear Engineering and Technology
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    • v.53 no.12
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    • pp.3910-3917
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    • 2021
  • Reactor fuel's power distribution plays a vital role in designing the new generation thermionic Space Reactor Power Systems (SRPS). In this paper, the 1/12th SPACE-R's full reactor core was numerically analyzed with two kinds of different axial power distribution, to identify their impacts on thermal-hydraulic and thermoelectric characteristics. In the benchmark study, the maximum error between numerical results and existing data or design values ranged from 0.2 to 2.2%. Four main conclusions were obtained in the numerical analysis: a) The axial power distribution has less impact on coolant temperature. b) Axial power distribution influenced the emitter temperature distribution a lot, when the core power was cosine distributed, the maximum temperature of the emitter was 194 K higher than that of the uniform power distribution. c) Comparing to the cosine axial power distribution, the uniform axial power distribution would make the maximum temperature in each component of the reactor core much lower, reducing the requirements for core fuel material. d) Voltage and current distribution were similar to the axial electrode temperature distribution, and the axial power distribution has little effect on the output power.

Temperature distribution during heavy oil thermal recovery considering the effect of insulated tubing

  • Zhang, Songting
    • Geomechanics and Engineering
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    • v.19 no.6
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    • pp.523-532
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    • 2019
  • Based on the formation characteristics, wellbore parameters and insulated tubing (IT) parameters of the Shengli oilfield, Shandong, China, a geomechanical model is built to predict the temperature distributions of the wellbore and formation. The effects of the IT heat conductivity coefficient (HCC), well depth and IT joint on the temperature distribution of the IT, completion casing, cement sheath, and formation are investigated. Results show the temperature of the formation around the wellbore has an exponentially decreasing relation with the distance to the wellbore. The temperature of the formation around the wellbore has an inverse relation with the IT HCC when the temperatures of the steam and the formation are given. The temperature of the casing outer wall is mainly determined by the steam temperature and IT HCC rather than by the initial formation temperature. The temperature of the casing at the IT joint is much larger than that of the other location. Due to the IT joint having a small size, the effects of the IT joint on the casing temperature distribution are limited to a small area only.

A Diagnostic Technique for Distribution Transformers using Top Oil Temperature (최상부 유온을 이용한 배전용 변압기의 진단 기법)

  • Choe, Do-Hyeok;Yun, Yong-Han;Min, Gyeong-Rae;Kim, Jae-Cheol
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.49 no.5
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    • pp.242-251
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    • 2000
  • In this paper, we argued the possibility of the diagnostic technique for distribution transformers using the top oil temperature rising above the ambient temperature. The proposed diagnostic technique used the reference top oil temperature rising at rated current. We determined the emergency value of the transformer using the limitation of the top oil temperature rising and calculated the loss of life. The top oil temperature rises because of the load currents. In this point, the proposed diagnostic technique was explained. The proposed system measures the load current, top oil temperature and ambient temperature. With the diagnostic device, we tested the top oil temperature rising of t재 transformers. Then the loss of life was calculated by the top oil temperature.

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Isothermal Distribution Map on the Korean Peninsula to Improve the Accuracy of the Environmental Planning (국토환경계획 정도(精度) 향상 목적의 지형고도속성을 반영한 한반도 등온분포도 작성)

  • Kim, Won-Joo;Lee, Gwan-Gyu
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.11 no.3
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    • pp.87-93
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    • 2008
  • In order to manage national environment effectively, one has to understand its ecological traits. The difference of temperature determines ecological traits of each respective region. In other words, temperature differentials on surface make a great impact on botanical structure. Currently, isothermal data-produced by meteorological stations based upon time series analysis-are widely used to plan and manage national environment. Nonetheless, the isothermal data do not reflect real surface temperature of regions. Because of numerous mountainous terrains in the Korean peninsula where temperature varies widely according to altitude, the range of temperature distribution-that reflects altitudinal change-has to be paid special attention. This study aims at expressing in space isothermal distribution that is necessary to plan and manage national environment effectively. In addition, not just South Korea, but also North Korea was included for isothermal distribution. As a result, this study corrected established isothermal lines up to date and demonstrated that altitude, latitude, and distance from coastal lines greatly influence temperature distribution of the Korean peninsula.

Temperature Dependence of Efficiency Droop in GaN-based Blue Light-emitting Diodes from 20 to 80℃

  • Ryu, Guen-Hwan;Seo, Dong-Joo;Ryu, Han-Youl
    • Current Optics and Photonics
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    • v.2 no.5
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    • pp.468-473
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    • 2018
  • We investigate the temperature dependence of efficiency droop in InGaN/GaN multiple-quantum-well (MQW) blue light-emitting diodes (LEDs) in the temperature range from 20 to $80^{\circ}C$. When the external quantum efficiency (EQE) and the wall-plug efficiency (WPE) of the LED sample were measured as injection current and temperature varied, the droop of EQE and WPE was found to be reduced with increasing temperature. As the temperature increased from 20 to $80^{\circ}C$, the droop ratio of EQE was decreased from 16% to 14%. This reduction in efficiency droop with temperature can be interpreted by a temperature-dependent carrier distribution in the MQWs. When the carrier distribution and radiative recombination rate in MQWs were simulated and compared for different temperatures, the carrier distribution was found to become increasingly homogeneous as the temperature increased, which is believed to partly contribute to the reduction in efficiency droop with increasing temperature.

Overload Criterion of Mineral-Oil-immersed Distribution Transformers Rated 100kVA and Less Using the Characteristics of Top-Oil Temperature Rising (최상부 유온 상승 특성을 이용한 100kVA 이하 유입식 배전용 변압기의 과부하 판정 기준)

  • Yun, Sang-Yun;Kim, Jae-Chul;Park, Chang-Ho
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.51 no.11
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    • pp.559-567
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    • 2002
  • This paper presents the general recommendations for the overload criterions of mineral-oil-immersed distribution transformers rated 100kVA and less. For this purpose, we analyze the characteristics of top-oil temperature rising for mineral-oil-immersed power distribution transformer rated 100kVA and less, manufactured in Korea, In order to analyze the characteristics of top-oil temperature rising due to the distribution transformer loading, we performed experiments at KERI (Korea Electrical Research Institute) from December 2000 to May 2001. The restraint of ambient temperatures for the experiment results is solved using the results of foreign standards. Finally, we present the overload criterions of distribution transformer for summer and winter season, respectively.

A Study on the Hot Spot Temperature in 154kV Power Transformers

  • Kweon, Dong-Jin;Koo, Kyo-Sun;Woo, Jung-Wook;Kwak, Joo-Sik
    • Journal of Electrical Engineering and Technology
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    • v.7 no.3
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    • pp.312-319
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    • 2012
  • The life of a power transformer is dependent on the life of the cellulose paper, which influenced by the hot spot temperature. Thus, the determination of the cellulose paper's life requires identifying the hot spot temperature of the transformer. Currently, however, the power transformer uses a heat run test is used in the factory test to measure top liquid temperature rise and average winding temperature rise, which is specified in its specification. The hot spot temperature is calculated by the winding resistance detected during the heat run test. This paper measures the hot spot temperature in the single-phase, 154kV, 15/20MVA power transformer by the optical fiber sensors and compares the value with the hot spot temperature calculated by the conventional heat run test in the factory test. To measure the hot spot temperature, ten optical fiber sensors were installed on both the high and low voltage winding; and the temperature distribution during the heat run test, three thermocouples were installed. The hot spot temperature shown in the heat run test was $92.6^{\circ}C$ on the low voltage winding. However, the hot spot temperature as measured by the optical fiber sensor appeared between turn 2 and turn 3 on the upper side of the low voltage winding, recording $105.9^{\circ}C$. The hot spot temperature of the low voltage winding as measured by the optical fiber sensor was $13.3^{\circ}C$ higher than the hot spot temperature calculated by the heat run test. Therefore, the hot spot factor (H) in IEC 60076-2 appeared to be 2.0.