• Title/Summary/Keyword: Heat transfer modeling

Search Result 380, Processing Time 0.021 seconds

An Analysis and Experimental Study for Thermal Design Verification of Satellite Electronic Equipment (인공위성 전장품의 열설계 검증을 위한 해석 및 실험적 연구)

  • Kim Jung-Hoon;Jun Hyoung Yoll;Yang Koon-Ho
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2005.04a
    • /
    • pp.91-95
    • /
    • 2005
  • A heat dissipation modeling method of EEE parts is developed for thermal design and analysis of an satellite electronic equipment. The power consumption measurement value of each functional breadboard is used for the heat dissipation modeling method. For the purpose of conduction heat transfer modeling of EEE parts, surface heat model using very thin ignorable thermal plates is developed instead of conventional lumped capacity nodes. The thermal plates are projected to the printed circuit board and can be modeled and modified easily by numerically preprocessing programs according to design changes. These modeling methods are applied to the thermal design and analysis of CTU and verified by thermal cycling and vacuum tests.

  • PDF

Evaporative Modeling in n Thin Film Region of Micro-Channel (마이크로 채널내 박막영역에서의 증발 모델링)

  • Park, Kyoung-Woo;Noh, Kwan-Joong;Lee, Kwan-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.27 no.1
    • /
    • pp.17-24
    • /
    • 2003
  • A mathematical model of the hydrodynamic and heat transfer performances of two-phase flow (gas-liquid) in thin film region of micro channel is proposed. For the formulation of modeling, the flow of the vapor phase and the shear stress at the liquid-vapor interface are considered. In this work, disjoining pressure and capillary force which drive the liquid flow at the liquid-vapor interface in thin film region are adopted also. Using the model, the effects of the variations of channel height and heat flux on the flow and heat transfer characteristics are investigated. Results show that the influence of variation of vapor pressure on the liquid film flow is not negligible. The heat flux in thin-film region is the most important operation factor of micro cooler system.

ASSESSMENT OF THE TiO2/WATER NANOFLUID EFFECTS ON HEAT TRANSFER CHARACTERISTICS IN VVER-1000 NUCLEAR REACTOR USING CFD MODELING

  • MOUSAVIZADEH, SEYED MOHAMMAD;ANSARIFAR, GHOLAM REZA;TALEBI, MANSOUR
    • Nuclear Engineering and Technology
    • /
    • v.47 no.7
    • /
    • pp.814-826
    • /
    • 2015
  • The most important advantage of nanoparticles is the increased thermal conductivity coefficient and convection heat transfer coefficient so that, as a result of using a 1.5% volume concentration of nanoparticles, the thermal conductivity coefficient would increase by about twice. In this paper, the effects of a nanofluid ($TiO_2$/water) on heat transfer characteristics such as the thermal conductivity coefficient, heat transfer coefficient, fuel clad, and fuel center temperatures in a VVER-1000 nuclear reactor are investigated. To this end, the cell equivalent of a fuel rod and its surrounding coolant fluid were obtained in the hexagonal fuel assembly of a VVER-1000 reactor. Then, a fuel rod was simulated in the hot channel using Computational Fluid Dynamics (CFD) simulation codes and thermohydraulic calculations (maximum fuel temperature, fluid outlet, Minimum Departure from Nucleate Boiling Ratio (MDNBR), etc.) were performed and compared with a VVER-1000 reactor without nanoparticles. One of the most important results of the analysis was that heat transfer and the thermal conductivity coefficient increased, and usage of the nanofluid reduced MDNBR.

Thermal Transport Phenomena in the FET Typed MWCNT Gas Sensor with the 60 μm Electrode Distance (60 μm의 전극 간극을 갖는 FET식 MWCNT 가스센서에서 열 유동 현상)

  • Jang, Kyung-Uk
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.28 no.6
    • /
    • pp.403-407
    • /
    • 2015
  • Generally, MWCNT, with thermal, chemical and electrical superiority, is manufactured with CVD (chemical vapor deposition). Using MWCNT, it is comonly used as gas sensor of MOS-FET structure. In this study, in order to repeatedly detect gases, the author had to effectively eliminate gases absorbed in a MWCNT sensor. So as to eliminate gases absorbed in a MWCNT sensor, the sensor was applied heat of 423[K], and in order to observe how the applied heat was diffused within the sensor, the author interpreted the diffusion process of heat, using COMSOL interpretation program. In order to interpret the diffusion process of heat, the author progressed modeling with the structure of MWCNT gas sensor in 2-dimension, and defining heat transfer velocity($u={\Delta}T/{\Delta}x$), accorded to governing equation within the sensor, the author proposed heat transfer mechanism.

Modeling of Turbulent Heat Transfer in an Axially Rotating Pipe Flow (축을 중심으로 회전하는 관유동에서 난류열전달의 모형화)

  • Shin, Jong-Keun
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.31 no.9
    • /
    • pp.741-753
    • /
    • 2007
  • The elliptic conceptual second moment model for turbulent heat fluxes, which was proposed on the basis of elliptic-relaxation equation, was applied to calculate the turbulent heat transfer in an axially rotating pipe flow. The model was closely linked to the elliptic blending model which was used for the prediction of Reynolds stress. The effects of rotation on the turbulent characteristics including the mean velocity, the Reynolds stress tensor, the mean temperature and the turbulent heat flux vector were examined by the model. The numerical results by the present model were directly compared to the DNS as well as the experimental results to assess the performance of the model predictions and showed that the behaviors of the turbulent heat transfer in the axially rotating pipe flow were satisfactorily captured by the present models.

Heat and Flow Analysis of a Parallel Flow Heat Exchanger Using Porous Modeling (다공성 모델링을 이용한 평행류 열교환기의 열.유동 해석)

  • Jeong, Gil-Wan;Lee, Gwan-Su
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.25 no.12
    • /
    • pp.1784-1792
    • /
    • 2001
  • Numerical analysis on a parallel flow heat exchanger(PFHE) is performed using 2 dimensional turbulent porous modeling. This modeling can consider three-dimensional configuration of passage (flat tube with micro-channels), and the stability and accuracy of numerical results are improved. The geometrical parameters(e.g., the position of separators, inlet/outlet, and porosity of passages of a PFHE) are varied in order to examine the flow and thermal characteristics and flow distribution of the single phase multiple passages system. The flow non-uniformities along the paths of the PFHE are observed to evaluate the thermal performance of the heat exchanger. The location of inlet affects the heat transfer, and the location of outlet affects the pressure drop. The porosity with the optimum thermal performance is around 0.53.

A Study of Thermal and flow Characteristics Induced by Fire in a Partial Enclosure (부분밀폐공간내에서 화재로 야기되는 열 및 유동특성에 관한 연구)

  • 박희용;한철희;박경우
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.18 no.5
    • /
    • pp.1288-1300
    • /
    • 1994
  • Mathematical modeling and numerical calculation on the flow and thermal characteristics induced by fire in a partial enclosure are performed. The solution procedures include the Shvab-Zeldovich approximation for the physical transport equations, low Reynolds number k-.epsilon. model for the turbulent fluid flow and Discrete Ordinate method(DOM) to calculate the radiative heat transfer. PMMA(Polymethylmethacrylate) is adopted as a solid fuel. Two different cases are considered : combustions with and without gas radiation occuring in a open cavity for variable pyrolyzing location of PMMA. When the fire source is located at the left-wall, the flow region of flame gas is limited at the left-wall and ceiling and recirculation region of inlet gas is formulated at neat the floor. In case of neglecting the radiative heat transfer, more large flame size and higher temperature is predicted. It is essential to consider the radiative heat transfer for analysis of fire phenomenon.

Parallelized Unstructured-Grid Finite Volume Method for Modeling Radiative Heat Transfer

  • Kim Gunhong;Kim Seokgwon;Kim Yongmo
    • Journal of Mechanical Science and Technology
    • /
    • v.19 no.4
    • /
    • pp.1006-1017
    • /
    • 2005
  • In this work, we developed an accurate and efficient radiative finite volume method applicable for the complex 2D planar and 3D geometries using an unstructured-grid finite volume method. The present numerical model has fully been validated by several benchmark cases including the radiative heat transfer in quadrilateral enclosure with isothermal medium, tetrahedral enclosure, a three-dimensional idealized furnace, as well as convection-coupled radiative heat transfer in a square enclosure. The numerical results for all cases are well agreed with the previous results. Special emphasis is given to the parallelization of the unstructured-grid radiative FVM using the domain decomposition approach. Numerical results indicate that the present parallel unstruc­tured-grid FVM has the good performance in terms of accuracy, geometric flexibility, and computational efficiency.

Fully coulpled CMC modeling for three-dimensional turbulent nonpremixed syngas flame (CMC 모델을 이용한 난류 비예혼합 Syngas 화염장 해석)

  • Kim, Gun-Hong;Lee, Jung-Won;Kim, Yong-Mo;Ahn, Kook-Young
    • 한국연소학회:학술대회논문집
    • /
    • 2006.04a
    • /
    • pp.111-120
    • /
    • 2006
  • The fully coupled conditional moment closure(CMC) model has been developed to realistically simulate the structure of complex turbulent nonpremixed syngas flame, in which the flame structure could be considerablyl influenced by the turbulence, transport history, and heat transfer as well. In order to correctly account for the transport effect, the CMC transport equations fully coupled with the flow and mixing fields are numerically solved. The present CMC approach has successfully demonstrated the capability to realistically predict the detailed structure and the overall combustion characteristics. The numerical results obtained in this study clearly reveal the importance of the convective and radiative heat transfer in the precise structure and NOx emission of the present confined combustor with a cooling wall.

  • PDF