• Title/Summary/Keyword: Comprehensive Heat Transfer Model

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A study on the radiative heat transfer analysis in a laminar diffusion flame (층류확산화염의 출사열전달 해석에 관한 연구)

  • 이도형;최병륜
    • Journal of Advanced Marine Engineering and Technology
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    • v.13 no.3
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    • pp.48-55
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    • 1989
  • The purpose of present study is to evaluate both the radiative heat loss from a flame and the local formation and oxidation rate of soot. The present paper describes a comprehensive mathematical model to deal with combustion and radiative heat transfer simultaneously. The involved radiative heat transfer model was based on the "heat ray tracing method" originally proposed by Hayasaka et al.. Some predicted results were compared with the experiments.periments.

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DEVELOPMENT OF A GENERAL PURPOSE THERMO/FLUID FLOW ANALYSIS PROGRAM NUFLEX WITH WALL IMPINGEMENT AND HEAT TRANSFER ANALYSIS MODEL OF LIQUID FILM (충돌분무와 액막의 열전달 해석모델을 고려한 범용 열/유체 프로그램 NUFLEX의 개발)

  • Kim, H.J.;Ro, K.C.;Ryou, H.S.;Hur, N.
    • Journal of computational fluids engineering
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    • v.13 no.2
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    • pp.68-72
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    • 2008
  • NUFLEX is a general purpose thermo/fluid flow analysis program which has various physical models including spray. In NUFLEX, spray models are composed of breakup and collision models of droplet. However, in case of diesel engine, interaction between wall-film and impingement model considering heat transfer is not coded in NUFLEX. In this study, Lee & Ryou impingement & wall-film model considering heat transfer is applied to NUFLEX. For the verification of this NUFLEX program, numerical results are compared with experimental data. Differences of film thickness and radius between numerical results and experimental data are within 10% error range. The results show that NUFLEX can be used for comprehensive analysis of spray phenomena.

Development of a general purpose thermo/fluid flow analysis program NUFLEX with heat transfer analy sis model of impinging liquid film (충돌분무 액막의 열전달 해석모델을 고려한 범용 열/유체 프로그램 NUFLEX의 개발)

  • Kim, Hyun-Jeong;Ro, Kyoung-Chul;Ryou, Hong-Sun;Hur, Nahm-Keon
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.71-74
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    • 2008
  • NUFLEX is a general purpose thermo/fluid flow analysis program which has various physical models including spray. In NUFLEX, spray models are composed of breakup and collision models of droplet. However, in case of diesel engine, interaction between wall-film and impingement model considering heat transfer is not coded in NUFLEX. In this study, Lee & Ryou impingement & wall-film model considering heat transfer is applied to NUFLEX. For the verification of this NUFLEX program, numerical results are compared with experimental data. Differences of film thickness and radius between numerical results and experimental data are within 10% error range. The results show that NUFLEX can be used for comprehensive analysis of spray phenomena.

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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
    • Journal of Fashion Business
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    • v.20 no.3
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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.

A Numerical Study on Beat Transfer from an Aluminum Foam Heat Sink by Impinging Air Jet in a Confined Channel (충돌 공기제트에서 국한 유로 내 발포 알루미늄 방열기의 열전달 수치해석)

  • Lee, Sang-Tae;Kim, Seo-Young;Lee, Kwan-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.6
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    • pp.883-892
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    • 2002
  • A numerical study has been carried out to investigate the flow and heat transfer from an aluminum foam heat sink in a confined channel. A uniform heat flux is given at the bottom of the aluminum foam heat sink, which is horizontally placed on the heated surface. The channel walls are assumed to be adiabatic. Cold air is supplied from the top opening of the channel and exhausted to the channel outlet. Comprehensive numerical solutions are acquired to the governing Wavier-Stokes and energy equations, using the Brinkman-Forchheimer extended Darcy model and the local thermal non-equilibrium model f3r the region of porous media. Details of flow and thermal fields are examined over wide ranges of the principal parameters; i.e., the Reynolds number Re, the height of heat sink h/H, porosity $\varepsilon$and pore diameter ratio $R_{H}$.

Analysis of Heat Transfer Characteristics in the Thermally Developing Region of a Porous Channel by LTNE Model (LTNE 모델을 이용한 다공성 채널 입구영역에서의 열전달 특성 해석)

  • Lee, Sang-Tae;Lee, Kwan-Soo;Kim, Seo-Young
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.7
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    • pp.983-990
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    • 2002
  • A numerical analysis has been carried out on forced convection heat transfer in the developing region of a porous channel. The channel is filled with an isotropic porous medium. At the channel walls, a uniform heat flux is given. Comprehensive numerical solutions are acquired to the Brinkman-Forchheimer extended Darcy equation and the LTNE model which does not employ the assumption of local thermal equilibrium between solid and fluid phases. Details of thermal fields in the developing region are examined over wide ranges of the thermal parameters. The numerical solutions at the fully developed region are compared with the previous analytical solutions. The correlation for predicting local Nusselt number in a porous channel is proposed.

Comparative Investigation of Convective Heat Transfer Coefficients for Analyzing Compressed Hydrogen Fueling Process (압축 수소 충전 공정 해석을 위한 대류 열전달 계수 비교 분석)

  • Hyo Min Seo;Byung Heung Park
    • Journal of the Korean Institute of Gas
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    • v.27 no.3
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    • pp.123-133
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    • 2023
  • Commercial hydrogen fuel cell vehicles are charged by compressing gaseous hydrogen to high pressure and storing it in a storage tank in the vehicle. This process causes the temperature of the gas to rise, to ensure the safety to storage tanks, the temperature is limited. Therefore, a heat transfer model is needed to explain this temperature rise. The heat transfer model includes the convective heat transfer phenomenon, and accurate estimation is required. In this study, the convective heat transfer coefficient in the hydrogen fueling process was calculated and compared using various correlation equations considering physical phenomena. The hydrogen fueling process was classified into the fueling line from the dispenser to the tank inlet and the storage tank in the vehicle, and the convective heat transfer coefficients were estimated according to process parameters such as mass flow rate, diameter, temperature and pressure. As a result, in the case of the inside of the filling line, the convective heat transfer coefficient was about 1000 times larger than that of the inside of the storage tank, and in the case of the outside of the filling line, the convective heat transfer coefficient was about 3 times larger than that of the outside of the storage tank. Finally, as a result of a comprehensive analysis of convective heat transfer coefficients in each process, it was found that outside the storage tank was lowest in the entire hydrogen fueling process, thus dominated the heat transfer phenomenon.

An Economic Analysis and Performance Prediction for a Ground Heat Pump System with Barrette Pile (Barrette 파일을 이용한 지열시스템의 채열 성능 예측 및 경제성 분석에 관한 연구)

  • Chae, Ho-Byung;Nam, Yujin;Park, Yong-Boo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.11
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    • pp.600-605
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    • 2013
  • Ground source heat pump systems (GSHP) can achieve higher performance of the system, by supplying more efficient heat source to the heat pump, than the conventional air-source heat pump system. But building clients and designers have hesitated to use GSHP systems, due to expensive initial cost, and uncertain economic feasibility. In order to reduce the initial cost, many researches have focused on the energy-pile system, using the structure of the building as a heat exchanger. Even though several experimental studies for the energy-pile system have been conducted, there was not enough data of quantitative evaluation with economic analysis and comprehensive analysis for the energy-pile. In this study, a prediction method has been developed for the energy pile system with barrette pile, using the ground heat transfer model and ground heat exchanger model. Moreover, a feasibility study for the energy pile system with barrette pile was conducted, by performance analysis and LCC assessment. As a result, it was found that the heat exchange rate of a barrette pile was 2.55 kW, and the payback period using LCC analysis was 8.8 years.

Numerical Prediction of Low Heat Rejection Diesel Engine Performance for Small Size Vessel (시뮬레이션 프로그램에 의한 소형 선박용 저열손실 디젤엔진의 성능평가)

  • Baek, Moon-Yeal;Lee, Kyo-Seung;Kang, Shin-Hyung
    • Journal of the Society of Naval Architects of Korea
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    • v.41 no.6
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    • pp.134-139
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    • 2004
  • It is known that over 60% of engine power is dissipated into circumstance, cooling water and cooling oil without any conversion into useful work. Following the first law of thermodynamics, it is possible that heat loss to cooling water can be converted into mechanical work through crankshaft. But in case that the engine is operating without any cooling effect, the serious problem unsolved so far is the engine durability. In this study, LHR(Low Heat Rejection) engine was introduced as one of the promising engine and several useful qualitative and quantitative data were drawn.

Visualization Experiment for Nucleate Boiling Bubble Motion on a Horizontal Tube Heater Fabricated with Flexible Circuit Board (연성회로기판 기반 수평전열관 표면의 비등기포거동 가시화 실험 연구)

  • Kim, Jae Soon;Kim, Yu-Na;Park, Goon-Cherl;Cho, Hyoung Kyu
    • Journal of the Korean Society of Visualization
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    • v.14 no.2
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    • pp.52-60
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    • 2016
  • The Passive Auxiliary Feedwater System(PAFS) is one of the advanced safety concepts adopted in the Advanced Power Reactor Plus(APR+). To validate the operational performance of the PAFS, detailed understanding of a boiling heat transfer on horizontal tube outside is of great importance. Especially, in the mechanistic boiling heat transfer model, it is important to visualize the phenomena but there are some limitations with conventional experimental approaches. In the present study, we devised a heater based on the Flexible Printed Circuit Board (FPCB) for a more comprehensive visualization and subsequently, a digital image processing technique for the bubble motion measurement was established. Using the measurement technique, important parameters of the nucleate boiling are analyzed.