• Journal of Advanced Marine Engineering and Technology
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• 제32권6호
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• pp.854-861
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• 2008

Heat transfer characteristics of protruding electronic components in a horizontal channel are studied numerically. The system consists of two horizontal channels formed by two covers and one printed circuit board which has three uniform protruding heat source blocks. A two-dimensional numerical model has been developed to predict the conjugate heat transfer. and the finite volume method is used to solve the problem. Five different cooling methods are considered to examine the heat transfer characteristics of electronic components according to the different cooling methods. The velocity and temperature of cooling medium and the temperature of the heat source blocks are obtained. The results of the five different cooling methods are compared to find out the most efficient cooling method in a given geometry and heat sources.

• 대한기계학회논문집B
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• 제37권7호
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• pp.655-663
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• 2013

막냉각에 관한 많은 연구들은 주유동과 이차유로가 평행한 형태로 연구가 이루어졌다. 하지만 실제 터빈 블레이드에서 이차유로의 방향은 일반적으로 주유동의 방향에 수직한 형태이다. 그래서 본 연구에서는 이차유동의 방향이 이중분사 막냉각의 효율에 미치는 영향을 수치해석을 통해 알아보고자 한다. 분사율은 1, 2이고 횡방향 분사각은 $22.5^{\circ}$이다. 분사율이 1일 때 평행 형상에서는 안티키드니 와류가 잘 형성되어 막냉각 효율이 수직 형상의 경우보다 더 높다. 반면에 분사율이 2일 때 수직 형상의 막냉각 효율은 평행 형상보다 향상되었다. 많은 유량의 제트가 서로 반대 방향으로 분사되기 때문에 두 형상 모두 막냉각 효율이 높게 나타난다. 하지만 안티키드니 와류의 영향은 다른 분사율보다 상대적으로 작다.

• Nuclear Engineering and Technology
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• 제49권5호
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• pp.979-988
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• 2017

The feasibility of cooling in a pressurized heavy water reactor after a large break loss-of-coolant accident has been analyzed using Multidimensional Analysis of Reactor Safety-KINS Standard code during the recirculation phase. Through evaluation of sensitivity of the fuel channel temperature to various effective recirculation flow areas, it is determined that proper cooling of the fuel channels in the broken loop is feasible if the effective flow area remains above approximately 70% of the nominal flow area. When the flow area is reduced by more than approximately 25% of the nominal value, however, incipience of boiling is expected, after which the thermal integrity of the fuel channel can be threatened. In addition, if a dramatic reduction of the recirculation flow occurs, excursions and frequent fluctuations of temperature in the fuel channels are likely to be unavoidable, and thus damage to the fuel channels would be anticipated. To resolve this, emergency coolant supply through the newly installed external injection path can be used as one alternative means of cooling, enabling fuel channel integrity to be maintained and permanently preventing severe accident conditions. Thus, the external injection flow required to guarantee fuel channel coolability has been estimated.

• Design & Manufacturing
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• 제8권1호
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• pp.10-13
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• 2014

Plastic products are producted more than 70% of total processes by the injection molding. The injection molding process has 4 processes such as filling, packing, cooling and ejecting. It spends most of times in the cooling process. Therefore, it is important to control the mold temperature in producing plastic products. The time and system of cooling affect the product's quality and productivity. Especially, cooling time has about 60% of total injection cycle time. Therefore, we can improve a productivity by shortening cooling time. This study shows comparative study about cooling efficiency of spiral channel and baffle and observed the variation of time to freeze of molding As the result of CAE experiments, cooling rate by spiral channel had faster than baffle and as freeze time was decreased. Results of this study will be used widely to design for cooling system of injection mold.

• 한국산학기술학회논문지
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• 제10권4호
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• pp.702-706
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• 2009

본 연구에서는 시작형 몰드재료로 우레탄 레진(TSR-755)을 이용하여 레이저 조형으로 다양한 형태의 냉각 채널을 가진 몰드로 가공했을 경우, 사출성형 상용패키지(Simpoe-Mold)를 사용하여 냉각채널 변화에 따라 사출물의 냉각시간과 변형량을 비교 검토 하였다. 해석결과, 사출물 주변의 적절한 냉각채널배치로 기존 금속재질의 시작형 몰드 대비 19% 최대 변형량 감소와 46%의 냉각시간 단축이 가능한 것으로 나타났다.

• 에너지공학
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• 제25권4호
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• pp.7-12
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• 2016

본 연구는 냉각효과를 높이기 위해 냉각채널 형상에 대한 변수를 다루고 있다. 냉각효과가 증가하면 제조현장에 있는 공장에 의해 발생되는 배출가스량은 감소하게 된다. 이러한 문제를 해결하기 위해 효율적인 냉각시스템에 대한 설계가 필요하다. 따라서, 본 연구에서는 냉각채널을 냉각성능을 향상시키기 위해 수치분석을 수행하였다. 배플과 핀의 길이에 영향을 받는 열전달률은 수치해석에 의해 계산이 된다. 3차원 레이놀즈 평균 나비아스토크 방정식이 유동과 냉각채녈의 열전달을 계산하는데 사용되며 난류영역은 $k-{\varepsilon}$ 모델이 사용되었다.

• Journal of Astronomy and Space Sciences
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• 제28권3호
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• pp.233-239
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• 2011

A series of computational analyses was performed to predict the cooling process by the cooling channel of preburners used for kerosene-liquid oxygen staged combustion cycle rocket engines. As an oxygen-rich combustion occurs in the kerosene fueled preburner, it is of great importance to control the wall temperature so that it does not exceed the critical temperature. However, since the heat transfer is proportional to the speed of fluid running inside the channel, the high heat transfer leads to a trade-off of pressure loss. For this reason, it is necessary to establish a certain criteria between the pressure loss and the heat transfer or the wall surface temperature. The design factors of the cooling channel were determined by the computational research, and a test model was manufactured. The test model was used for the hot fire tests to prove the function of the cooling mechanism, among other purposes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.811-814
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• 2001

Warpage analysis of bobbin, molded by injection molding process was performed. Concerned with a mold design, cooling system was designed based on Taguchi method, the distance between cavity wall and cooling channel was most influent factor amongst four design variables like an inlet temperature of coolant, a coolant flow rate, a diameter of cooling channel, and the distance between cavity wall and cooling channel. Optimal packing processes to reduce the warpage of molded part was analyzed based on the response surface method by considering holding pressure. Their optimal processing conditions were 9.4 seconds, 5.3 seconds, 15.2 seconds, and 85MPa, respectively.

• 대한기계학회논문집A
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• 제21권11호
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• pp.1773-1785
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• 1997

The cooling stage is the very critical and most time consuming stage of the injection molding process, thus it cleary affects both the productivity and the part quality. Even through there are several commercialized package programs available in the injection molding industry to analyze the cooling performance of the injection molding coling stage, optimization of the cooling system has npt yet been accomplished in the literature due to the difficulty in the sensitivity analysis. However, it would be greatly desirable for the mold cooling system designers to have a computer aided design system for the cooling stage. With this in mind, the present study has successfully developed an interated computer aided design system for the injection molding cooling system. The CAD system utilizes the sensitivity analysis via a Boundary Element Method, which we recently developed, and the well-known CONMIN alforuthm as an optimization technique to minimize a weighted combination (objective function) of the temperature non-uniformity over the part surface and the cooling time related to the productivity with side constranits for the design reality. In the proposed objective function , the weighting parameter between the temperature non-uniiformity abd the cooling time can be adjusted according to user's interest. In this cooling system optimization, various design variable are considered as follows : (i) (design variables related to processing conditions) inlet coolant bulk temperature and volumetric flow rate of each cooling channel, and (ii) (design variables related to mold cooling system design) radius and location of each cooling channel. For this optimum design problem, three different radius and location of each cooling channel. For this optimum design problem, three different strategies are suffested based upon the nature of design variables. Three sample problems were successfully solved to demonstrated the efficiency and the usefulness of the CAD system.

• 한국추진공학회지
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• 제16권2호
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• pp.1-9
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• 2012

2,500 N급 과산화수소/케로신 이원 추력기의 성능 향상 및 다양한 미션에 적용하기 위하여 재생냉각의 적용가능성을 검토하였다. 1-D 계산을 통해 과산화수소를 냉각제로 하는 경우에 대한 계산을 수행하였다. 설계된 재생냉각 연소기의 노즐 목에서의 열 유속은 18-20 MW/$m^2$로 예측되었으며, 그에 따른 유로의 너비는 2.5 mm 높이는 0.45 mm로 설계 되었다. 설계된 유로형상을 바탕으로 냉각 유로 내에서의 압력강하를 예측하기 위한 평판형 모델을 제작하여 실험을 진행하였고, 수치해석 결과와 비교를 수행하였다. 그 결과, 수치해석과 실험결과와의 최대 오차는 약 13%, 그리고 평균 오차는 약 5%로 계산되었다.