• 한국산학기술학회논문지
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• 제14권1호
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• pp.69-73
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• 2013

내부열교환기를 이용한 에어컨 시스템은 작동유체인 R134a의 고압측 액상냉매와 저압측 기상냉매의 상호 열교환을 통해 시스템의 응축 효율을 증가시켜 에너지 효율을 개선시킨다. 이는 에어컨 시스템의 성능 향상 및 경량화를 가능하게 하여 차량 연비 향상과 냉매 누출을 최소화할 수 있으며, 또한 현 R134a 대비 대체냉매 (R1234yf 등)의 동등 냉방성능 확보를 가능하게 하는 기술이다. 본 연구에서는 내측 압출 파이프 및 외측 사이 고효율 냉각 휜 (fin)이 삽입된 이중관 형태의 내부열교환기 상세 설계를 위해, 냉각 휜의 높이 및 내측 압출 파이프 내부형상 등의 다양한 형상 설계인자 변경에 따른 열전달 성능 및 압력강하 특성을 살펴보았다. 가장 우수한 내부열교환기 성능은 난류형성을 위한 내측관 형상이 라이너 및 세레이션 겸용 타입이었으며, 이는 내부열교환기가 장착되지 않은 경우보다 냉방시스템 성능이 약 6.4%, 시스템 COP는 약 9.2% 향상된 결과를 나타내었다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.175-180
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• 2008

This paper is dedicated to the development of cooling devices such as mLHP with Fan-Fin system limited by noise and vibration. As we know, Heat pipe has the limitation of cooling capability to cool down the electronics. It is bounded by capillary and thermal limitation but heat load that it has to deal with is increasing. Especially Today's electronic technology has a tendency to integrate lots of function into the small piece of a processor like Dual core having 35W heat load for mobile and desktop computer respectively. There is an optimum operating condition of temperature, below $70^{\circ}C$, during the maximum heat load, 35W. There is the motivation needed to develop the new type of cooling devices and we can discuss about the new challenge beyond heat pipe.

• ETRI Journal
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• 제20권4호
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• pp.380-394
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• 1998

A numerical study has been performed to predict the characteristics on the transient operation of the heat pipe with multiple heaters for electronic cooling. The model of the heat pipe was composed of the evaporator section with four heaters, insulated transport section, and the condensor section with a conductor which is cooled with uniform heat flux condition to surrounding. The governing equations and the boundary conditions were solved by the generalized PHOENICS computational code employing the finite volume method. Two test cases are investigated in present study; Case 1 indicates that the 1st and 2nd heaters among four heating sources are heated off, while the 3rd and 4th heaters are heated on. Case 2 is the inverse situation switched from heating location of Case 1. The results show that the transient time to reach the steady state is shorter for Case 1 than for Case 2. Especially, the temperature difference of the heater during switching operation is relatively small compared to the maximum allowable operating temperature difference in electronic system. Hence, it is predicted that the heat pipe in present study operates with thermally good reliability even for switching the heaters.

• 소성∙가공
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• 제21권2호
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• pp.131-137
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• 2012

With the advantages of power savings, increased life expectancy and fast response time over traditional incandescent bulb, LEDs are increasingly used for many applications including automotive, aviation, display, and special lighting applications. Since the high heat generation of LED chips can reduce service life, degrade luminous efficiency, and cause variation of color temperature, many studies have been carried out on the optimization of LED packaging and heat sinks. In this study, a fin expansion type cooling device using heat pipe, instead of a solid aluminum heat sink, was designed for LED security lightings based on thermal resistance analysis. Numerical analysis and experimental validation were carried out to evaluate its cooling performance.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1385-1390
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• 2009

In this study the purpose is development of passive cooling system for telecommunication cabinet used by latent heat material. This cooling system is not required for electronic power. It was tested for the performance of the telecommunication combined latent heat material with $48^{\circ}C$ of phase changed temperature and heat pipe. At $45^{\circ}C$ of outside temperature, when heater power was 1,000 W and 1,500 W, the inside temperature of the cabinet was $55^{\circ}C$ and $62^{\circ}C$. This system was showed better performance than the other systems.

• 플랜트 저널
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• 제13권4호
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• pp.38-40
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• 2017

본 연구는 기기냉각수 계통 Water Balance 정상화 방안을 위한 연구로 비용 대비 효과를 고려하여 최적안을 도출한다. Water Balance 검토를 위해 배관망해석프로그램이 사용되며, 프로그램의 신뢰성을 높이기 위해 초음파유량계로 현장 계측을 통해 시뮬레이션 계수 보정을 진행한다. 이를 토대로 다양한 Case Simulation을 통해 최적운전방안에 대해 도출하는 것이 목적이다.

• Journal of Mechanical Science and Technology
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• 제16권3호
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• pp.354-362
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• 2002

In this paper, the heat transfer characteristics of a self-oscillating heat pipe are experimentally investigated for the effect of various working fluid fill charge ratios and heat loads. The characteristics of temperature oscillations of the working fluid are also analysed based on chaotic dynamics. The heat pipe is composed of a heating section, a cooling section and an adiabatic section, and has a 0.002m internal diameter, a 0.34m length in each turn and consists of 19 turns. The heating and the cooling portion of each turn has a length of 70mm. A series of experiments was carried out to measure the temperature distributions and the pressure variations of the heat pipe. Furthermore, heat transfer performance, effective thermal conductivity, boiling heat transfer and condensation heat transfer coefficients are calculated for various operating conditions. Experimental results show the efficacy of this type of heat pipe.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
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• pp.381-386
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• 1994

Recently, the design and construction of massive concrete structures are increased. But, the temperature rise within a large concrete mass make the construction of massive concrete structures be very difficult. Therefore, in Seohae Grand Bridge Project, the field measurement of hydration heat for the massive concrete footings(11$\times$22$\times$4m) was carried out. It was shown to be possible to construct the massive concrete footing successfully by application of pipe cooling system. And the measurement results showed that standard code for concrete practice was very conservative.

• 한국유체기계학회 논문집
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• 제17권6호
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• pp.109-114
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• 2014

After the Fukushima accident in 2011, it was revealed that nuclear power plant has the vulnerability to SBO accident and its extension situation without sufficient cooling of reactor core resulting core meltdown and radioactive material release even after reactor shutdown. Many safety systems had been developed like PAFS, hybrid SIT, and relocation of RPV and IRWST as a part of steps for the Fukushima accident, however, their applications have limitation in the situation that supply of feedwater into reactor is impossible due to high pressure inside reactor pressure vessel. The concept of hybrid heat pipe with control rod is introduced for breaking through the limitation. Hybrid heat pipe with control rod is the passive decay heat removal system in core, which has the abilities of reactor shutdown as control rod as well as decay heat removal as heat pipe. For evaluating the cooling performance hybrid heat pipe, a commercial CFD code, ANSYS-CFX was used. First, for validating CFD results, numerical results and experimental results with same geometry and fluid conditions were compared to a tube type heat pipe resulting in a resonable agreement between them. After that, wall temperature and thermal resistances of 2 design concepts of hybrid heat pipe were analyzed about various heat inputs. For unit length, hybrid heat pipe with a tube type of $B_4C$ pellet has a decreasing tendency of thermal resistance, on the other hand, hybrid heat pipe with an annular type $B_4C$ pellet has an increasing tendency as heat input increases.

• 콘크리트학회논문집
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• 제15권2호
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• pp.314-322
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• 2003

콘크리트 구조물의 수화열 저감 방안으로 사용되는 파이프 쿨링 시스템을 적용할 경우 파이프 관 주변의 내부유동에 의한 열전달이 발생하게 된다. 이와 같은 내부유동에 의한 열전달 효과를 정확히 규명하기 위해서는 유수대류계수를 산정하여야 한다. 파이프 쿨링 효과의 규명에 필요한 유수대류계수의 영향인자로는 냉각수의 층난류 여부, 냉각수의 유동속도, 관의 형상 및 열특성 등이 있다. 본 연구에서는 유수대류계수를 산정하기 위한 실험장치를 개발하였으며, 이를 이용하여 강재 및 PVC 파이프에 대한 실험을 수행하였다. 이들 실험결과를 토대로 관의 내부표면이 매끈한 원형관이며 난류흐름을 갖는 내부유동에 대한 유수대류계수 모델식을 제안하였으며, 제안된 모델식은 냉각수의 유속뿐만 아니라 유동관의 재질 및 형상을 고려할 수 있다. 유수대류계수는 관을 흐르는 냉각수의 대류에 의한 열전달 효과를 나타내는 값으로 관의 열전도율 및 관의 직경과는 비례관계에 있으며, 관의 두께와는 반비례관계를 갖는다. 본 연구에서 개발된 유수대류계수 모델식은 이러한 영향을 잘 반영하고 있으나, 강재 파이프에 대해서만 관의 두께 및 직경에 관한 보정계수를 제시하였다. 제안된 모델식에 의한 유수대류 계수와 실험으로부터 구한 유수대류계수를 비교한 결과, 제안된 모델식이 실험값을 정확히 추정하고 있음을 알 수 있었다.