• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.973-976
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• 2011

본 논문에서는 연소기 엔진 연소시험 설비용으로 사용되는 비연소식 전기히터의 특정부위에서 코일이 파단되는 현상이 연속적으로 발생함에 따라 원인 규명을 목적으로 히터에 대한 복합 열유동해석을 수행하었다. 수행 결과, 히터의 파단이 발생하는 코일 입구 직선구간에서 코일의 온도가 국부적으로 크게 상승함에 따라 열 및 구조적으로 취약하다는 것이 판명되었으며, 이의 원인은 이 영역 부근에서 공기 유속이 매우 낮았기 때문이었다. 코일을 하류로 25mm 이동하였고 이를 통해서 코일 입구 직선부분에서의 공기의 유속이 증가됨으로 코일온도를 감소시킬 수 있었고, 코일의 열 및 구조적 안정성을 확보할 수 있었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.121-125
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• 2008

In this study, the characteristics of internal flow and the heat transfer performance of dimpled plate heat exchanger were numerically investigated. For the numerical analysis, conjugate heat transfer method between cold fluid - plate - hot fluid was studied with appropriate boundary conditions. Velocity magnitude, temperature and pressure distribution were obtained from the simulation. Correlations for fanning f-factor and Colburn j-factor were obtained from numerical results and compared to the experimented data.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.231-234
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• 2010

고온의 연소가스에 노출되는 디퓨저 냉각에 필요한 열량을 계산하였다. 디퓨저 내부는 공기와 혼합된 연소가스가 흐르고 디퓨저 벽체는 채널로 구성된 공간에 물이 흐르도록 되어 있다. 디퓨저 구조물과 유체 간에 또는 유체 자체적인 열전달과 구조물 내부의 열전달 현상은 복합적인 형태로 나타나는데 고온에서 작동하는 점을 고려하여 복사, 대류, 전도 모두를 적용 하였다. 열전달량 계산은 경험식에 근거한 1차원 해석과 CFD 해석의 2가지 방법으로 수행하였다. 1차원 해석은 경험식을 통해 얻어진 결과를 적용하여 열전달량을 산출하였고, CFD 해석은 DO 복사 열전달 모델을 적용하여 계산하였으며, 계산의 타당성을 검정하기 위하여 두 방법을 비교하였다. 총 열전달량의 차이는 1% 미만으로 거의 같았으나, 1차원 계산은 열전달 모델의 단순화로 디퓨저 입구에서의 순환영역을 구현하지 못하여 전체적인 열전달량 분포에서는 차이를 보였다. 디퓨저의 안정성을 확보하기 위한 냉각수 용량은 2가지 계산 결과를 조합하여 각 구간별로 최대 열전달량을 근거로 도출하였다.

• 반도체디스플레이기술학회지
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• 제13권2호
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• pp.57-62
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• 2014

In the study, a numerical analysis is conducted to investigate the heat transfer characteristics of an inverter system inside a panel for three locations (bottom, middle and top). A conjugate heat transfer is simulated using a CFD (computational fluid dynamics) code since the heat transfer through the surrounding panel walls is important. It is shown that the heat flux through the left wall, which is important for the safety of the electronic equipment, is the biggest when the inverter is located at bottom. On the other hand, the heat flux through the left wall is negligible when the inverter at middle or top. It is also found that the heat flux to the surrounding walls is the lowest when the inverter is at middle.

• 대한기계학회논문집
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• 제17권6호
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• pp.1609-1620
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• 1993

본 연구에서는 자연형 태양열시스템의 열성능에 영향을 미치는 인자를 열유동 전산해석을 통해 규명하고 모델을 설정하여 활용률을 최대로 하는 형상을 제시하고자 한다.

• 대한기계학회논문집
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• 제14권2호
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• pp.453-462
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• 1990

The interaction of forced convection-conduction with thermal radiation in laminar boundary layer over a plate fin is studied numerically. The analysis is based on complete solution whereby the heat conduction equation for the fin is solved simultaneously with the conservation equations for mass, momentum and energy in the fluid boundary layer adjacent to the fin. The fluid is a gray medium and diffusion(Rosseland) approximation is used to describe the radiative heat flux in the energy equation. The resulting boundary value problem are convection-conduction parameter N$_{c}$ and radiation-conduction parameter m, Prandtl number Pr. Numerical results are presented for gases with the Prandtl numbers of 0.7 & 5 with values of N$_{c}$ and M ranging from 0 to 10 respectively. The object of this study is to provide the first results on forced convection-radiation interaction in boundary layer flow over a semi-infinite flay plate which can be used for comparisons with future studies that will consider a more accurate expression for the radiative heat flux. The agreement of the results from the complete solution presented by E. M. Sparrow and those from this paper for the special case of M=0 is good. The overall rate of heat transfer from the fin considering radiative effect is higher than that from the fin neglecting radiative effect. The local heat transfer coefficient with radiative effect is higher than that without radiative effect. In the direction from tip to base, those coefficients decrease at first, attain minimum, and then increase. The larger values of N$_{c}$ M, Pr give rise to larger fin temperature variations and the fin temperature without radiative effect is always higher than that with radiative effect.

• 한국군사과학기술학회지
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• 제22권2호
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• pp.249-254
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• 2019

A Digital Transmitter/Receiver Module(DTRM), which is an essential part in active phased-array radar systems, generates a high heat density, and needs to be properly cooled for stable operation. A tile-type DTRM that is a stacking structure of multi-layer components was modeled with simplification and heat dissipation characteristics of the DTRM model were studied using computational fluid dynamics(CFD) simulations. Most of the heat was dissipated by the heat conduction through the cold plate, but the heat transfer by the forced convection on top of the DTRM also was found to play an important role in the thermal management. Under the given conjugated heat transfer environment, the DTRM was confirmed to secure a stable operating temperature range.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.793-802
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• 2024

In the framework of the European project SAMOSAFER, this numerical study focuses on some thermal aspects of the Emergency Draining Tank (EDT) located underneath the core of a Molten Salt Reactor. In case of an emergency, this tank passively receives the liquid fuel salt and is designed to ensure a subcritical state. An important requirement is that the fuel does not overheat to maintain the EDT Hastelloy container integrity. The present EDT is based upon a group of hexagonal cooling assemblies arranged in a hexagonal grid and cooled down thanks to conduction through the inert salt layer up to an air flow in charge of removing the heat. This numerical thermal study relies on a conjugated heat transfer analysis coupling a Finite Element solid thermal code (SYRTHES) and two instances of a Finite Volume CFD codes (Code_Saturne). Calculations on an initial design suggest that a simple center airpipe flow is likely to not sufficiently cool the device. Alternative solutions have been evaluated. Introduction of fins to enhance the heat transfer do not bring a noticeable improvement regarding maximum temperature reached. However, a solution in which the central pipe air flow is replaced by several cooling channels located closer to the fuel is investigated and suggests a better cooling.

• 한국추진공학회지
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• 제22권2호
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• pp.152-159
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• 2018

고온밸브의 비정상상태 복합열전달 해석 기법을 확립하기 위한 연구를 수행하였다. 장시간 작동하는 고온밸브의 특성과 해석의 경제성을 고려하여 두 가지 해석 기법을 제시하였다. 발달순서에 따라 구간을 나누고 구간별로 시간간격을 증가시켜 해석을 수행하는 다 구간 해석 기법과 정상상태 유동장 해석결과를 비정상상태 해석의 초기 값으로 사용하는 one-way 해석 기법을 제시 하였다. 다 구간 해석 기법의 경우 신뢰도가 높은 해석이 수행 가능하지만 경제적인 측면에서 설계 단계의 해석 기법으로는 부적합하였다. one-way 해석 기법의 경우 초기 신뢰도는 떨어지나 기민한 설계 변수 연구가 가능한 경제적인 해석 수행이 가능하였다.

• 한국분무공학회지
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• 제26권1호
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• pp.1-8
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• 2021

Droplet evaporation has been known as a common phenomenon in daily life, and it has been widely used for many applications. In particular, the influence of the different heated substrates on evaporation flux and flow characteristics is essential in understanding heat and mass transfer of evaporating droplets. This study aims to simulate the droplet evaporation process by considering variation of thermal property depending on the substrates and the surface temperature. The commercial program of ANSYS Fluent (V.17.2) is used for simulating the conjugated heat transfer in the solid-liquid-vapor domains. Moreover, we adopt the diffusion-limited model to predict the evaporation flux on the different heated substrates. It is found that the evaporation rate significantly changes with the increase in substrate temperature. The evaporation rate substantially varies with different substrates because of variation of thermal property. Also, the droplet evaporates more rapidly as the surface temperature increases owing to an increase in saturation vapor pressure as well as the free convection effect caused by the density gradient.