• Title/Summary/Keyword: Inverse Heat Transfer

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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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Performance Evaluation of a Thermo Siphon Type Radiator for LED Lighting System by using an Inverse Heat Transfer Method (역열전달해석기법에 의한 LED 조명용 무동력 냉각사이클링 방열기 성능평가)

  • Kim, E.H.;Kim, H.K.;Seo, K.S.;Lee, M.K.;Cho, C.D.
    • Transactions of Materials Processing
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    • v.20 no.7
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    • pp.473-478
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    • 2011
  • In this study, the performance of a thermo siphon type radiator made of copper for LED lighting system was evaluated by using an inverse heat transfer method. Heating experiments and finite element heat transfer analysis were conducted for three different cases. The data obtained from experiments were compared with the analysis results. Based on the data obtained from experiments, the inverse heat transfer method was used in order to evaluate the heat transfer coefficient. First, the heat transfer analysis was conducted for non-vacuum state, without the refrigerant. The evaluated heat transfer coefficient on the radiator surface was 40W/$m^2^{\circ}C$. Second, the heat transfer analysis was conducted for non-vacuum state, with the refrigerant, resulting in the heat transfer coefficient of 95W/$m^2^{\circ}C$. Third, the heat transfer analysis was conducted for vacuum state, with refrigerant. For the third case, the evaluated heat transfer coefficients were 140W/$m^2^{\circ}C$. Third, the heat transfer analysis was conducted for vacuum state, with refrigerant. For the third case, the evaluated heat transfer coefficients were 140W/$m^2^{\circ}C$ for the radiator body, 5W/$m^2^{\circ}C$. Third, the heat transfer analysis was conducted for vacuum state, with refrigerant for the rising position of radiator pipe, 35W/$m^2^{\circ}C$. Third, the heat transfer analysis was conducted for vacuum state, with refrigerant. For the highest position of radiator pipe, and 120W/$m^2^{\circ}C$ for the downturn position of radiator pipe. As a result of inverse heat transfer analysis, it was confirmed that the thermal performance of the current radiator was best in the case of the vacuum state using the refrigerant.

Analysis of Thermal Loading of a Large LPG Engine Piston Using the Inverse Heat Conduction Method (열전도의 역문제 방법을 이용한 대형 LPG 엔진 피스톤의 열부하 해석)

  • Park Chul-Woo;Lee Boo-Youn
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2006.04a
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    • pp.820-827
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    • 2006
  • The convection heat transfer coefficients on the top surface of a large liquid petroleum liquid injection(LPLi) engine piston are analyzed by solving an inverse thermal conduction problem. The heat transfer coefficients are numerically found so that the difference between analyzed temperatures from the finite element method and measured temperatures is minimized. Using the resulting heat transfer coefficients as the boundary condition, temperature of a large LPLi engine piston is analyzed.

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Evaluation of Heat Transfer Coefficient Distribution by Inverse Analysis (Inverse 해석에 의한 열전달계수 분포의 결정)

  • Kim, Heung-Gyu;O, Su-Ik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.12
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    • pp.3856-3870
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    • 1996
  • The objective of this study is to evaluate heat transfer coefficient distribution during heat treatment by inverse analysis. As a first procedure, the inverse heat transfer formulation by using two dimensional finite element method has been developed. The formulation can handlematerial nonlinearity and allow arbitrary placement and number of sensors. The formulation was verified through application to simulated exact and inexact measurements.

Analysis of Heat Transfer in Cooling of a Hot Plate by Planar Impingement Jet (평면충돌제트에 의한 고온 판 냉각과정의 열전달 해석)

  • Ahn, Dae-Hwan;Kim, Dong-Sik
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.1
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    • pp.17-27
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    • 2009
  • Water jet impingement cooling is used to remove heat from high-temperature surfaces such as hot steel plates in the steel manufacturing process (thermo-mechanical cooling process; TMCP). In those processes, uniform cooling is the most critical factor to ensure high strength steel and good quality. In this study, experiments are performed to measure the heat transfer coefficient together with the inverse heat conduction problem (IHCP) analysis for a plate cooled by planar water jet. In the inverse heat transfer analysis, spatial and temporal variations of heat transfer coefficient, with no information regarding its functional form, are determined by employing the conjugate gradient method with an adjoint problem. To estimate the two dimensional distribution of heat transfer coefficient and heat flux for planar waterjet cooling, eight thermo-couple are installed inside the plate. The results show that heat transfer coefficient is approximately uniform in the span-wise direction in the early stage of cooling. In the later stage where the forced-convection effect is important, the heat transfer coefficient becomes larger in the edge region. The surface temperature vs. heat flux characteristics are also investigated for the entire boiling regimes. In addition, the heat transfer rate for the two different plate geometries are compared at the same Reynolds number.

A study on the Evaluation of Heat Transfer Coefficient by Optimization Algorithm (최적화 기법을 활용한 열전달계수의 측정)

  • Kim, J.T.;Lim, C.H.;Choi, J.K.
    • Transactions of Materials Processing
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    • v.15 no.9 s.90
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    • pp.679-685
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    • 2006
  • New method for evaluation of heat transfer coefficient is proposed. In general, many researchers have been studied about inverse problem in order to calculate the heat transfer coefficient on three-dimensional heat conduction problem. But they can get the time-dependent heat transfer coefficient only through inverse problem. In order to acquire temperature-dependent heat transfer coefficient, it requires much time for numerous repetitive calculation and inconvenient manual modification. In order to solve these problems, we are using the SQP(Sequential Quadratic Programming) as an optimization algorithm. When the temperature history is given by experiment, the optimization algorithm can evaluate the temperature-dependent heat transfer coefficient with automatic repetitive calculation until difference between calculated temperature history and experimental ones is minimized. Finally, temperature-dependent heat transfer coefficient evaluated by developed program can used on various heat transfer problem.

Research on the Inverse Heat Conduction Problem for Thermal Analysis of a Large LPG Engine Piston (대형 LPG 엔진 피스톤의 온도 분포 해석을 위한 열전도 역문제에 관한 연구)

  • 이부윤;박철우;최경호
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.11
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    • pp.146-159
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    • 2002
  • An efficient method to predict the convection heat transfer coefficients on the top surface of the engine piston is proposed. The method is based on the inverse method of the thermal conduction problem and uses a numerical optimization technique. In the method, the heat transfer coefficients are numerically obtained so that the difference between analyzed temperatures from the finite element method and measured temperatures is minimized. The method can be effectively used to analyze the temperature distribution of engine pistons in case when application of prescribed-temperature boundary condition is not reasonable because of insufficient number of measured temperatures. A hollow sphere problem with an analytic solution is taken as a simple example and accuracy and efficiency is demonstrated. The method is applied to a practical large liquid petroleum gas(LPG) engine piston and the heat transfer coefficients on the top surface of the piston is successfully calculated. Resulting analyzed temperature favorably coincides with measured temperature.

Improvement of Estimation Accuracy of Thermal Deformation on Machine Tool by Inverse method (역해법에 의한 공작기계의 열변형 예측정도의 향상)

  • Lee, Jong-Du
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.2
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    • pp.126-131
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    • 2001
  • One of the major obstacles in testing or evaluating precisely the thermal behavior of a machine tool is the difficulty in measuring the heat transfer coefficients on the surfaces by a conventional method. This paper presents a new approach based on the inverse method to identify the values of heat transfer coefficients by using temperature changes measured on the surfaces of a machine tool during a short period in its operating. In the present method, a machine tool structure is modeled by the finite element method and the characteristic curves of the temperature change at several points on machine tool surfaces are theoretically derived in the form that they contain the heat transfer coefficient as an unfixed heat source are approximated so that the theoretical characteristic curves of temperature change fit the measured ones as closely as possible.

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Heat transfer coefficients for F.E analysis in warm forging processes (온간 단조 공정에서의 열전달 계수)

  • Kang J. H.;Ko B. H.;Jae J. S.;Kang S. S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.05a
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    • pp.138-143
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    • 2005
  • Finite Element analysis is widely applied to elevated temperature forging processes and shows a lot of information of plastic deformation such as strain, stress, defects, damages and temperature distributions. In highly elevated temperature deformation processes, temperature of material and tool have significant influence on tool life, deformation conditions and productivities. To predict temperature related properties accurately, adequate coefficients of not only contact heat transfer between material and dies but also convection heat transfer due to coolants are required. In most F.E analysis, too higher value of contact heat transfer coefficient is usually applied to get acceptable temperature distribution of tool. For contact heat transfer coefficients between die and workpiece, accurate values were evaluated with different pressure and lubricants conditions. But convection heat transfer coefficients have not been investigated for forging lubricants. In this research, convection heat transfer coefficients for cooling by emulsion lubricants are suggested by experiment and Inverse method. To verify acquired convection and contact heat transfer coefficients, tool temperature was measured for the comparison between measured tool temperature and analysis results. To increase analysis accuracy, repeated analysis scheme was applied till temperature of the tool got to be in the steady-state conditions. Verification of heat transfer coefficients both contact and convection heat transfer coefficients was proven with good accordance between measurement and analysis.

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Effect of Pressure on Interfacial Heat Transfer Coefficient in the Squeeze Casting Process (용탕단조시 가압력에 따른 계면열전달계수의 변화)

  • Kim, Jin-Soo;Ahn, Jae-Young;Han, Yo-Sub;Lee, Ho-In;Hong, Chun-Pyo
    • Journal of Korea Foundry Society
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    • v.14 no.3
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    • pp.248-257
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    • 1994
  • Research in heat transfer and solidification commonly involves experimentation and mathematical modeling with associated numerical analysis and computation. Inverse problems in heat transfer are part of this paradigm. During the solidification of metal casting, an interfacial heat transfer resistance exists at the boundary between the casting and the mold, and this heat transfer resistance usually varies with time. In the case of the squeeze casting the contact heat transfer resistance is decreased by pressure and ideal contact is almost accomplished. In the present work, heat transfer coefficient, which is inverse value of the heat transfer resistance, was used for convenience. A numerical technique, Non-Linear Estimation has been adopted for calculation of the casting/mold interfacial heat transfer coefficient during the squeeze casting process. In this method, the measured temperature data from experiment were used. The computational results were applied to the analysis of heat transfer and solidification.

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