• 제목/요약/키워드: Heat transfer modeling

검색결과 380건 처리시간 0.022초

화염전달함수를 이용한 연소불안정 모델링 기법 소개 (Introduction to Combustion Instability Modeling Using Flame Transfer Function)

  • 김대식
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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    • pp.71-72
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    • 2014
  • The current paper introduce the flame transfer function calculation results using CFD in order to quantify the heat release fluctuations in a lean premixed gas turbine combustor. Comparisons of the modeled and measured flame shapes were made using the optimized heat transfer conditions.

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Comparison between Water and N-Tetradecane as Insulation Materials through Modeling and Simulation of Heat Transfer in Packaging Box for Vaccine Shipping

  • Dao, Van-Duong;Jin, Ik-Kyu;Hur, Ho;Choi, Ho-Suk
    • 청정기술
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    • 제22권1호
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    • pp.45-52
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    • 2016
  • This study reports on the modeling and simulation of heat transfer in packaging boxes used for vaccine shipping. Both water and n-tetradecane are used as primary insulation materials inside a multi-slab system. The one-dimensional model, which is a spherical model using a radius equivalent to the rectangular geometry of container, is applied in this study. N-tetradecane with low thermal diffusivity and proper phase transition temperature exhibits higher heat transfer resistance during both heating and cooling processes compared to water. Thus, n-tetradecane is a better candidate as an insulating material for packaging containers for vaccine shipping. Furthermore, the developed method can also become a rapid and economic tool for screening appropriate phase change materials used as insulation materials with suitable properties in logistics applications.

액적이탈을 고려한 관내 응축열전달계수 계산 모델 (A modeling of in-tube condensation heat transfer considering liquid entrainment)

  • 권정태;안예찬;김무환
    • 대한기계학회논문집B
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    • 제22권7호
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    • pp.946-955
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    • 1998
  • Local condensation heat transfer coefficients in tubes were calculated by solving momentum and energy equations for annular film with liquid entrainment. The turbulent eddy distribution across the liquid film has been proposed and the calculated heat transfer coefficients were presented. Also turbulent Prandtl number effects on condensation heat transfer were discussed from three Pr$\_$t/ models. Finally, the calculated condensation heat transfer coefficients of R22 were compared with some correlations frequency referred to in open literature. This calculation model considering liquid entrainment predicted well the in-tube condensation heat transfer coefficient of R22 than the model not considering liquid entrainment. The effect of entrainment on heat transfer was predominant for high quality and high mass flux when the liquid film was turbulent.

중온수 흡수식 냉동기의 열전달 면적 최적화 (Optimization of Heat Transfer Area Distribution for a Hot Water Driven Absorption Chiller)

  • 정시영;조광운;이상수
    • 설비공학논문집
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    • 제12권5호
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    • pp.431-438
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    • 2000
  • The major irreversibilities in absorption chillers are associated with the transfer of heat into and out from the machine and irreversible process inside the machine. By modeling only external irreversibilities(endo-reversible), a model was formulated to predict the ideal performance of a single-effect absorption chiller. Its actual performance including both external and internal irreversibilities was calculated with a in-house simulation program. The optimization of heat transfer area distribution was performed for both endo-reversible cycle and actual cycle. The equation of endo-reversible modeling was found to give about 2times higher cooling capacity than the simulation program. At optimal distribution, it was found that heat transfer area of the evaporator was about 30% of total area, that of the generator was 20%, and the rest 50% was for the absorber and condenser. The system COP for endo-reversible cycle was slightly higher than that for actual cycle. In the case of LiBr-water single-effect absorption chiller, the maximum cooling capacity was obtained near the condition that LMTD is same at all heat exchangers.

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Laminar Forced Convective Heat Transfer to Near-Critical Water in a Tube

  • Lee, Sang-Ho
    • Journal of Mechanical Science and Technology
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    • 제17권11호
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    • pp.1756-1766
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    • 2003
  • Numerical modeling is carried out to investigate forced convective heat transfer to near-critical water in developing laminar flow through a circular tube. Due to large variations of thermo-physical properties such as density, specific heat, viscosity, and thermal conductivity near thermodynamic critical point, heat transfer characteristics show quite different behavior compared with pure forced convection. With flow acceleration along the tube unusual behavior of heat transfer coefficient and friction factor occurs when the fluid enthalpy passes through pseudocritical point of pressure in the tube. There is also a transition behavior from liquid-like phase to gas-like phase in the developing region. Numerical results with constant heat flux boundary conditions are obtained for reduced pressures from 1.09 to 1.99. Graphical results for velocity, temperature, and heat transfer coefficient with Stanton number are presented and analyzed.

미소 챔버 내 복사열전달을 수반한 열유동 해석 (Thermal analysis inside a small chamber including radiation)

  • 이형식;도기정;이상호
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2006년도 하계학술발표대회 논문집
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    • pp.194-198
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    • 2006
  • In this study, numerical modeling was performed to analyze air flow including radiation heat transfer inside a small chamber. Characteristics of heat transfer between source plate and target through glass are investigated for various surface temperature of heat source plate with buoyancy effect due to gravity force. Conduction heat transfer through the glass is considered and heat source plate is assumed to be a black body. Target surface temperature is largely affected by the radiation heat transfer. It can also be seen that as the source temperature increases target surface is dominated by radiation rather than convective heat transfer by air.

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극초음속 유동에서의 표면 촉매 재결합: 수치해석적 기법 리뷰 (Surface Catalytic Recombination in Hypersonic Flow: A Review of the Numerical Methods)

  • 김익현;양요셉
    • 산업기술연구
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    • 제43권1호
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    • pp.33-41
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    • 2023
  • This paper provides a general overview of surface catalytic recombination in hypersonic flow. The surface catalytic recombination phenomena is elaborated in terms of its general overview and numerical modeling associated with it. The general overview of the surface catalytic recombination phenomena describes the elementary surface reactions for the surface catalytic and the role of the surface catalytic recombination efficiency in the heat transfer determination. In the numerical modeling, the surface catalytic recombination is described based on the stagnation-point boundary layer analysis, and finite-rate surface reaction modeling. Throughout this overview manuscript, a general understanding of this phenomena is obtained and can be used as foundation for deeper application with the numerical computational fluid dynamics (CFD) flow solver to estimate the surface heat transfer in the hypersonic vehicles.

3D Modeling of a Fabric based on its 3D Microstructure Image and Application of the Model of the Numerical Simulation of Heat Transfer

  • Lee, Hyojeong;Lee, Heeran;Eom, Ran-i;Lee, Yejin
    • 패션비즈니스
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    • 제20권3호
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    • pp.30-42
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    • 2016
  • The objective of this study was to perform 3D solid modeling from 3D scanned surface images of cotton and silk in order to calculate the thermal heat transfer responses using numerical simulations. Continuing from the previous methodology, which provided 3D surface data for a fabric through optical measurements of the fabric microstructure, a simplified 3D solid model, containing a defined unit cell, pattern unit and fabric structure, was prepared. The loft method was used for 3D solid-model generation, and heat transfer calculations, made for the fabric, were then carried out using the 3D solid model. As a result, comprehensive protocols for 3D solid-model generation were established based on the optical measurements of real fabric samples. This method provides an effective means of using 3D information for building 3D models of actual fabrics and applying the model in numerical simulations. The developed process can be used as the basis for other analogous research areas to investigate the physical characteristics of any fabrics.

백신 수송용 포장재 내부에서 열 전달의 모델링 및 시뮬레이션 (Modeling and Simulation of Heat Transfer inside the Packaging Box for Vaccine Shipping)

  • 다오 반 둥;최호석;이성찬;배윤성
    • Korean Chemical Engineering Research
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    • 제46권3호
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    • pp.604-609
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    • 2008
  • 본 연구에서는 세계보건기구의 기준을 만족시키기 위한 포장재 개발을 목적으로 백신 수송용 장방형 포장재 내부열 전달에 대한 모델링 및 시뮬레이션을 수행하고 이를 실험결과와 비교하였다. 장방형의 박스를 구형 박스로 전환하여 구상한 1차원 모델은 냉각공정의 경우에는 실험 결과와 비교적 잘 일치하는 결과를 보였으나, 가열공정에서는 실험결과와 상당한 차이를 보여주었다. 이는 가열공정을 계산할 때, 포장재 외부에서의 경계조건을 적절히 고려해주지 못한 결과로 사료된다. 그러나, 본 연구를 통하여 상전이 물질을 함유한 다층 벽을 통한 열 전달의 문제를 전산 모사할 수 있는 기본적인 알고리즘을 성공적으로 개발할 수 있었다.

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

  • 김진수;안재영;한요섭;이호인;홍준표
    • 한국주조공학회지
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    • 제14권3호
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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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