• Title/Summary/Keyword: Steady state Heat Transfer

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Characteristics on the Non-Steady Heal Transfer of the STS 304 Hollow Cylinder (STS 304 중공 원통의 비정상 열전달 특성)

  • Lee, Sang-Chul;Kim, Young-Geun;Shim, Kyu-Jin;Bae, Kang-Youl;Chung, Han-Shik;Jeong, Hyo-Min
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1552-1557
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    • 2004
  • This paper introduced about characteristics on the non-steady heat transfer of STS 304 hollow cylinder, In the non-steady state, the specific heat and conductivity are depended on the temperature variations, and these properties affect to the governing equation on heat conduction. But the most of numerical analysis on heat conduction is assumed to constant properties which is conductivity and specific heat. Assuming that conduction is assumed to constant properties which is conductivity and specific heat. Assuming that the properties are reacted sensitively, the numerical results can have the difference of between constant properties with non-constant properties. The main parameters are specific heat and conductivity. The temperature distributions of the STS 304 hollow cylinder became in steady state after 4 minutes in case of the constant properties. As the conductivity in varied with temperature, the temperature distributions became in steady state after 15 minutes. Therefore, a numerical analysis of the non steady state heat transfer will has to apply that conductivity varied with temperature.

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Night Purge Evaluation Using the RTS-SAREK in Office Buildings (RTS-SAREK을 이용한 사무용 건물의 나이트 퍼지 성능 평가)

  • Shin, Dongshin;Park, Sungkeun;Park, Youngsoo;Park, Jisu;Lee, Jinyoung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.12
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    • pp.633-638
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    • 2015
  • This study evaluates the capacity of night purging in office buildings to reduce the cooling load. RTS-SAREK is used to estimate the performance of night purging on the steady state. To overcome steady state RTS program limitations, we added unsteady heat transfer equations. When the ACH (Air Change per Hour) increases, the wall temperature decreases in both the steady and unsteady states. The unsteady heat transfer rate is different from the steady transfer rate, which validates the unsteady calculation. When ACH is low, the heat transfer rate increases continuously with time. When ACH becomes higher, the heat transfer rate increases and decreases with time. When ACH is quite high, there exists a large difference in the heat transfer rate between the steady and unsteady calculations, which emphasizes the importance of the unsteady calculation.

Analysis of Temperature and Total Heat of Heated Glass through Experimental Measurement and Three-Dimensional Steady-State Heat Transfer Analysis (실측실험과 3차원 정상상태 열전달 해석을 통한 발열유리의 온도 및 전열량 분석)

  • Lee, Do-Hyung;Yoon, Jong-Ho;Oh, Myeong-Hwan
    • KIEAE Journal
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    • v.15 no.1
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    • pp.111-116
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    • 2015
  • Heat loss from windows and condensation occuring on its surface due to its lower insulation value causes much discomfort to occupants. In this study, Heated glass was used to make a basic study on prevention of condensation on glass surface for its heating functionality through experimental measurement and simulation analysis of total heat flux on the interior and exterior surface of glass. Error between experimental results and three dimensional steady-state heat transfer analysis were caused firstly, beacuse in the experimental chambers, cold chamber and steady temperature and humidity chamber, air temperature setting was not constant but rather ON/OFF control, and secondly, due to error rate in heat flux meter due to heat flux direction even in stable conditions.

A Study on Heat Transfer Characteristics of Laser Cutting for the CSP 1N Sheet Using High-power CW Nd:YAG Laser (고출력 CW Nd:YAG 레이저를 이용한 CSP 1N 박판 절단공정의 열전달 특성 분석)

  • Ahn, Dong-Gyu;Kim, Min-Su
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.5 no.1
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    • pp.51-58
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    • 2006
  • The objective of this research work is to investigate into heat transfer characteristics of the laser cutting of CSP 1N sheet using high power CW Nd:YAG laser. In order to investigate the heat transfer characteristics, three dimensional quasi stationary and steady-state heat transfer analysis has been carried out. The laser heat source is assumed as a volumetric heat source with a gaussian heat distribution in a plane. Through the comparison of the results of analyses with those of experiments, the proper finite element model has been obtained. In addition, characteristics of the three-dimensional heat transfer and temperature distribution have been estimated by the finite element model. Finally, the minimum temperature at the center for cutting of the material has been estimated.

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A Study on the Heat transfer in Residential Space Wall having Solar Radiation (태양복사열이 투사되는 주거공간 벽면의 열전달에 관한연구)

  • 고영렬;손철수
    • Journal of the Korean housing association
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    • v.15 no.3
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    • pp.93-99
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    • 2004
  • This study was conducted to estimate the solar energy, as an alternative energy evaluating an effect of solar radiation on indoor space of residential building. The basic data of solar radiation which is useful for architectural design was suggested using theoretical and experimental analysis. Accordingly, this study was carried out measuring the solar energy using Explicit Method. These results were compared with the results using steady state heat transfer method. The results of this study are summarized as follows; Based on the results using Explicit Method and steady state heat transfer on the indoor space of building, it was shown that an analysis on heat transfer using Explicit Method is more sensitive to the outdoor environmental changes. The results using Explicit Method to analysis and evaluate the solar radiation should be used for residential building design.

The Effects of the STS 304 Hollow Cylinder Property Variations on the Non-Steady Heat Conduction (STS 304 중공 원통의 물성치 변화가 비정상 열전도에 미치는 영향)

  • Lee, S.C.;Choi, H.G.;Seo, J.S.;Jeong, H.M.;Chung, H.S.
    • Journal of Power System Engineering
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    • v.8 no.2
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    • pp.39-44
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    • 2004
  • The effects of the STS 304 hollow cylinder property variations on the non-steady heat conduction are considered in this paper. In the non steady state, the specific heat and conductivity are depended on the temperature variations, and these properties affect to the governing equation on heat conduction. But the most of numerical analysis on heat conduction is assumed to constant properties which is conductivity and specific heat. Assuming that the properties are reacted sensitively, the numerical results can have the difference of between constant properties with non constant properties. The main parameters are specific heat and conductivity. The temperature distributions of the STS 304 hollow cylinder became in steady state after 4 minutes in case of the constant properties. As the conductivity is varied with temperature, the temperature distributions became in steady state after 15 minutes. Therefore, a numerical analysis of the non steady state heat transfer is so important in case of varying temperature.

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Steady-state finite element analysis of three-dimensional extrusion of sections through square die (평금형을 통한 3차원 압출의 정상상태 유한요소해석)

  • 이승훈;이춘만
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1998.03a
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    • pp.231-234
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    • 1998
  • This study presents steady-state finite element analysis of three-dimensional hot extrusion of sections through square dies. The objective of this study is to develop a steady-state finite element method for hot extrusion through square dies, and to provide theoretical basis for the optimal die design and process control in the extrusion technology. In the present work, steady-state assumption is applied to both analyses of deformation and temperature. The analysis of temperature distribution includes heat transfer. Convection like element is adopted for the heat transfer analysis between billet and container, and also billet and die. Distributions of temperature, effective strain rate, velocity and mean stress are discussed to design extrusion die effectively.

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Calculation of Heat Transfer Coefficients by Steady State Inverse Heat Conduction (정상상태의 열전달계수 예측을 위한 최적화기법의 열전도 역문제에 관한 연구)

  • 조종래;배원병;이부윤
    • Journal of Advanced Marine Engineering and Technology
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    • v.21 no.5
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    • pp.549-556
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    • 1997
  • The inverse heat conduction problems is the calculation of surface heat transfer coefficients by utilizing measured temperature. The numerical technique of finite element analysis and optimizition is introduced to calculate temperatures and heat transfer coefficients. The calculated heat transfer coefficients and temperature distribution are good agreement with the results of direct analysis. The inverse method has been applied to the control valve of nuclear power plant.

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Comparative Study of the Steady State and Transient TSP Techniques in the Heat Transfer Measurement by an Inclined Impingement Jet (경사 충돌 제트 열전달 실험에서 정상 상태와 천이 TSP 기법의 비교 연구)

  • Jo, Yong-Hwa;Nho, Young-Cheol;Lee, Yong-Jin;Kwak, Jae-Su
    • The KSFM Journal of Fluid Machinery
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    • v.15 no.1
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    • pp.5-12
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    • 2012
  • In this paper, the heat transfer coefficient measurement techniques using TSP(temperature sensitive paint) were introduced and the results of a comparative study on the heat transfer coefficient measurement by steady state and transient TSP techniques were discussed. The distributions of heat transfer coefficient by a single $60^{\circ}$ inclined impingement jet on a flat surface were measured by both techniques. Tested Reynolds number based on the jet diameter (d) was 30,000 and the distance between jet exit and target plate (L) was fixed at 10d. Results showed that the measured Nusselt number by both techniques indicated significant difference except near the center of impingement jet. Also, the heat transfer coefficients measured by the transient TSP technique were affected by the reference temperature of the jet. Based on the measured data, characteristics of both TSP techniques were analyzed and suggestions for applying them were also given.

Experimental Study on the Heat Transfer Characteristics under the Supercritical Pressures (초임계압 열전달 특성에 관한 실험 연구)

  • Kang, Kyoung-Ho;Youn, Young-Jung;Park, Jong-Kuk;Choo, Yeon-Jun;Chun, Se-Young;Song, Chul-Hwa
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.2242-2247
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    • 2008
  • A series of experiments have been performed in a vertical tube of 9.4 mm inner diameter using the Freon, HFC-134a as working fluid medium under the supercritical pressure range. Two kinds of experiments, i.e. steady-state and pressure transient, have been carried out. As for the steady-state heat transfer experiment, the mass flux was in the range between 600 and $2000\;kg/m^2s$ and the maximum heat flux was $160\;kW/m^2$. The selected pressures were 4.1, 4.3 and 4.5 MPa which correspond to 1.01, 1.06 and 1.11 times the critical pressure, respectively. In the pressure transient experiments, the inlet pressures were varied from 3.8 to 4.5 MPa and vice versa in the pressure transient simulations. In this study, heat transfer correlation and criterion for the heat transfer deterioration are suggested under the supercritical pressures. And also heat transfer characteristics during the pressure transient are examined.

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