• 대한기계학회논문집B
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• 제22권3호
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• pp.303-315
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• 1998

Numerical and experimental studies on a heat pipe with two heat sources have been performed to investigate the operating characteristics. Numerical analysis was performed based on the cylindrical two-dimensional incompressible laminar flow for the vapor space and the conjugate heat transfer for the entire heat pipe. Experimental study with a 0.45 m length copper-water heat pipe was also performed to validate the numerical modeling for the heat input range from 29 W to 47 W on each heater. As results, the temperature profiles at the outer wall for the single active heat source as well as the temperature profiles for the switching operation between two heat sources are suggested. Due to the axial conduction, it is found that the temperature drop between the evaporator and the condenser appears small when the heat source closer to the condenser is turned on. For the switching operation in the present study, the transient time is about 700s and the temperatures at the locations of both heat source are same in 130s after switching.

• 한국항공우주학회지
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• 제41권11호
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• pp.874-882
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• 2013

한국형발사체(KSLV-II) 각 단 엔진의 연료로 사용되는 케로신(Jet A-1)은 추력실 재생냉각 및 연료 막냉각 과정에서 냉각유체로도 기능하게 된다. 본 연구에서는 Jet A-1의 열물리적 특성을 재현하기 위한 대체 혼합물 모델을 선정하고, SUPERTRAPP(NIST SRD4)을 이용하여 초임계압 영역을 포함하는 고압 영역에서 모델 연료의 열역학적 전달 상태량을 예측하였다. 측정값과의 비교 결과 액체로켓 엔진 추력실의 복합 열전달 해석 수행 시 Jet A-1 상태량을 추출하기 위한 데이터베이스로 활용 가능한 것으로 판단되며, 향후 연소 시험 결과와의 비교를 통하여 케로신 대체 모델의 상태량 정보를 이용한 재생냉각 추력실의 연소 냉각 성능 통합 해석 결과를 지속적으로 검증해 나갈 계획이다.

• 설비공학논문집
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• 제26권12호
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• pp.600-604
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• 2014

Longitudinal heat conduction is known to be an important factor in the design of a printed circuit heat exchanger(PCHE) for cryogenic applications. Parasitic heat conduction through the heat exchanger frame needs to be considered because it is known to decrease the effectiveness of the heat exchanger. In this paper, a conjugate heat transfer problem in a simple counter-flow PCHE is analyzed by a computational fluid dynamics simulation. The effect of longitudinal conduction in a straight channel is compared with the theoretical effectiveness-NTU relationship that assumes a "thin" heat exchanger frame. The calculation results suggest that the theoretical model is valid in the present calculation conditions where NTU is < 13.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.808-810
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• 2002

Higher current-rating and improved thermal performance are being sought for existing medium-voltage vacuum circuit breakers(VCB) in order to meet market needs which require to be compact and downsized. In this paper, thermal performance of medium voltage vacuum circuit breaker was investigated through experiments and numerical analysis. We changed several major parameters of current-rating and heat sink affecting on thermal behaviors in the breaker and observed the results. To predict the temperature distribution in complex three-dimensional (3-D) VCB components and gas, the commercial package was used to simulate conjugate heat transfer. Although some assumptions and simplifications were introduced to simulate the model, results from the computational model were in good agreement with actual temperature rise measurements obtained from experiments.

• 한국전산유체공학회지
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• 제22권1호
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• pp.26-36
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• 2017

A numerical study has been performed to evaluate thermal-hydraulic performance of a finger type cooling module with multiple-jet impingement in a divertor of nuclear fusion reactor. To analyze conjugate heat transfer in both solid and fluid domains, numerical analysis of the flow using three-dimensional Reynolds-averaged Navier-Stokes equations has been performed with shear stress transport turbulence model. The computational domain for the cooling module consisted of a single fluid domain and three solid domains; tile, thimble, and cartridge. The numerical results for the temperature variation on the tile were validated in comparison with experimental data under the same conditions. A parametric study was performed with four geometric parameters, i.e., angles between x-axis and centerlines of hole 1, 2, 3 and 4. The results indicate that the heat transfer rate was increased by 2.7% and 0.7% by the angle ${\theta}_1$ and angle ${\theta}_2$, respectively, and that the pressure drop was decreased by up to 1.8% by the angle ${\theta}_3$.

• Nuclear Engineering and Technology
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• 제41권9호
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• pp.1171-1180
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• 2009

The internal core baffle structure of a French Pressurized Water Reactor (PWR) consists of a collection of baffles and formers that are attached to the barrel. The connections are done thanks to a large number of bolts (about 1500). After inspection, some of the bolts have been found cracked. This has been attributed to the Irradiation Assisted Stress Corrosion Cracking (IASCC). The $Electricit\acute{e}$ De France (EDF) has set up a research program to gain better knowledge of the temperature distribution, which may affect the bolts and the whole structure. The temperature distribution in the structure was calculated thanks to the thermal code SYRTHES that used a finite element approach. The heat transfer between the by-pass flow inside the cavities of the core baffle and the structure was accounted for thanks to a strong thermal coupling between the thermal code SYRTHES and the CFD code named Code_Saturne. The results for the CP0 plant design show that both the high temperature and strong temperature gradients could potentially induce mechanical stresses. The CPY design, where each bolt is individually cooled, had led to a reduction of temperatures inside the structures. A new parallel version of SYRTHES, for calculations on very large meshes and based on MPI, has been developed. A demonstration test on the complete structure that has led to about 1.1 billion linear tetraedra has been calculated on 2048 processors of the EDF Blue Gene computer.

• 약학회지
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• 제48권6호
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• pp.369-373
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• 2004

We previously reported that Streptococcus pneumoniae capsule attached to the surface protein (JY-Pol) was protective to systemic pneumococcal infection. The JY -Pol antigen induced IgM, IgG, and IgA in mice and provoked cell-mediated immunity. In this current study, we investigated the effect of anti JY-Pol antiserun and monoclonal antibody C2 (Mab C2) specific for the JY-Pol antigen against the pneumococcal disease. Mice that were given the antiserum survived longer than mice that received antiserum pre-absorbed with S.pneumoniae cells or DPBS as a negative control. Heat-treated anti JY-Pol antiserum resulted in survival rates similar to intact fresh JY-Pol antiserum. Mab C2 isolated from JY-Pol-immunized mice also enhanced resistance of naive mice against the pneumococcal diseaser. This protection by Mab C2 appeared to be mediated by opsonization as determined in a RAW 264.7 monocyte/macrophage cell line. Epitope analysis showed that Mab C2 epitope consisted of glucuronic acid and glucose that blocked the interaction of JY-Pol to the C2. Taken together, these data indicate that the antiserum induced by the JY-Pol, a naturally pneumococcal conjugate formula, mediated the protection by passive transfer, which was confirmed by protective effect of Mab C2.

• 대한기계학회논문집B
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• 제38권7호
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• pp.639-646
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• 2014

난류모델에서 벽면처리법이 터빈 노즐 베인의 열전달 예측에 미치는 영향을 비교 분석하였다. 본 연구를 위해 NASA의 C3X 터빈 노즐 베인을 사용하였다. 벽함수 방법, 저레이놀즈수 방법, 천이모델을 사용하여 베인 표면에서의 압력 및 온도를 해석하였다. 해석 결과 터빈 노즐 베인의 중간 압력분포는 각 벽면처리법에 따른 차이 없이 실험값과 잘 일치하였다. 그러나 터빈 노즐 베인의 온도와 열전달 계수는 각 벽면처리법에 따라 큰 차이를 보였다. 전반적으로 저레이놀즈수 방법과 천이모델은 벽함수 방법에 비해 온도 및 열전달 계수 예측에 특별한 이점을 보이지 않았으며, 벽함수 방법을 적용한 레이놀즈응력 난류모델이 터빈 노즐 베인 표면의 온도 및 열전달 계수를 비교적 잘 예측하였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.468-472
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• 2010

To develop the Exhaust Maniverter(Manifold and converter) it needs to consider flow characteristics related to durability and performance of the catalyst, manufacturability, etc. This paper presents the analysis results regarding to flow characteristics such as flow uniformity, tangential speed, O2 sensor sensitivity and CHT (conjugate heat transfer) for the LCF(Low Cycle Fatigue) for gasoline 2.0 liter engine. The results are satisfactorily corresponded to the general criteria. Also skin temperature and pressure drop wire measured at the Engine Bench. These results can be useful for the design guide for Exhaust Maniverter.

• 대한기계학회논문집B
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• 제34권5호
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• pp.553-561
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• 2010

한국원자력연구원에서는 초고온가스로를 모사할 수 있는 중형 헬륨 회로를 건설 중에 있다. 이 실험헬륨 회로에서 두 개의 전기 가열기가 헬륨 유체를 1 ~ 9 MPa 의 압력 하에서 $950^{\circ}C$ 까지 가열하게 된다. 이 실험 헬륨 회로의 설계 사양을 최적화하기 위하여, 본 연구에서는 두 개의 가열기 중 하류에 위치한 고온헬륨가열기 안의 복합열전달 현상을 전산유체역학으로 해석하였다. 해석 결과에서 헬륨 가열기 내 최대 온도는 허용 한계를 넘지 않았고, 이로써 선정된 기하구조의 열적 특성은 설계요건을 만족함이 확인되었다.