• 설비공학논문집
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• 제14권11호
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• pp.880-889
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• 2002

The purpose of the present study is to examine the factors affecting the heat transfer limitations of screen mesh heat pipe for electronic cooling by theoretical analysis. Diameter of pipe was 6 mm, and mesh numbers are 50, 100, 150, 200 and 250 and water was selected as a working fluid. According to the change of mesh number, wick layer, inclination and saturation temperature, capillary pressure, pumping pressure, liquid friction coefficient in wick, vapor friction coefficient, capillary limitation, entrainment limitation, sonic limitation and boiling limitation we analyzed by theoretical design method of a heat pipe. As some results, the capillary limitation in small diameter of heat pipe is largely affected by mesh number and wick layer.

• 대한기계학회논문집B
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• 제26권11호
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• pp.1630-1637
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• 2002

A slab-wick heat pipe was fabricated and tested for applications where the condenser temperature is in a range of 80 to 12$0^{\circ}C$. The pipe material was 9.53 mm O.D. copper tube and the working fluids were ethanol and water. The total length of the heat pipe was 1.6 m, in which evaporator section was 1.4 m and the condenser was 0.10 m. The slab was a composite wick structure fabricated with STS316 wire screens. Thermal load was varied for a specified fill charge ratio and inclined angle. The optimum fill charge ratio was identified to be 110% based on a theoretical calculation of the pore space in the slab wick of the heat pipe. The maximum thermal load was 120W for ethanol and the same was 200W for water with the condenser temperature of 8$0^{\circ}C$. The thermal performance of the slab wick heat pipe is analysed in terms of temperature characteristics and thermal resistance against thermal load, tilt angle and fill charge ratio.

• 대한조선학회논문집
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• 제35권1호
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• pp.98-106
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• 1998

멤브레인형 가스운반선의 경우 화물창들 사이에 cofferdam을 두어 격리시키고 있는데 이 경우 극 저온 액체 화물의 영향으로 cofferdam 실내 온도는 약 $-40^{\circ}C$내외로 떨어지게 된다. 그 결과 cofferdam 및 화물창을 구성하는 bulkhead는 구조 부재로서의 허용 강도를 만족하는 온도를 유지할 수 없게 된다. 결국 heating system을 사용하여 cofferdam 실내 온도를 최소한 $5^{\circ}C$까지 올려야 하는데, 소요 pipe의 길이 산정을 위한 heat flux 산출과 pipe의 배치가 우선적으로 요청된다. 본 연구에서는 다양한 설계 조건에서의 cofferdam 내 heat flux를 각 compartment들 간의 연성 효과를 고려하여 구하고 이를 기존 계산서들과 비교 검토하여 그 타당성을 검증하였고 이를 토대로 heating system에 필요한 pipe의 길이를 산정하였다. 아울러 현재의 heating system의 대안으로 fin을 부착한 pipe로 구성된 heating coil system을 제시하고 그 효율을 비교하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.899-900
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• 2010

• 한국산학기술학회논문지
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• 제17권12호
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• pp.723-729
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• 2016

본 연구에서는 핀-관형 히트파이프와 평행류형 히트파이프 제작하여 시험하였으며 분리형 히트파이프의 작동유체의 충진량은 40~60(% vol.), 풍량은 300~1,400 사이에서 변화시켜가며 온도교환 효율, 열회수량, 공기측 압력강하를 비교하였다. 온도교환 효율은 두 종류의 히트파이프 모든 경우에서 저 풍량에서는 작동유체 충진량이 40(%vol.)일 때가 가장 높았으며 풍량이 증가함에 따라 최대 효율을 가지는 작동유체 충진량이 다름을 알 수 있었고, 환기량이 작을수록 온도교환 효율이 높게 나타났다. 평행류형 히트파이프 60(%vol.)의 실험결과에서 보는 것과 같이 작동 유체를 너무 많이 충진하게 되면 오히려 낮은 온도교환 효율을 보이는데 이는 관벽의 액막이 두터워지면서 열전달 효과를 악화시킨 결과로 최적 충진량이 40~50(%vol.) 사이에 있음을 알 수 있다. 풍량 변화에 따른 공기측 압력강하 비교에서는 증발부 히트파이프가 응축부 히트파이프 보다 크게 계측 되었는데 증발부 표면에 생긴 결로수의 영향으로 생각된다. 평행류형 히트파이프는 핀-관형 히트파이프와 비교하여 냉매 충진량은 48%, 체적은 41%에서 동등이상의 성능을 보였으며, 공기측 압력강하도 37% 정도로 좋은 성능을 나타내었다.

• Nuclear Engineering and Technology
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• 제52권1호
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• pp.19-26
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• 2020

Small nuclear reactor features higher power capacity, longer operation life than conventional power sources. It could be an ideal alternative of existing power source applied for special equipment for terrestrial or underwater missions. In this paper, a 25kWe heat pipe cooled reactor power source applied for multiple use is preliminary designed. Based on the design, a thermal-hydraulic analysis code for heat pipe cooled reactor is developed to analyze steady and transient performance of the designed nuclear reactor. For reactor design, UN fuel with 65% enrichment and potassium heat pipes are adopted in the reactor core. Tungsten and LiH are adopted as radiation shield on both sides of the reactor core. The reactor is controlled by 6 control drums with B₄C neutron absorbers. Thermoelectric generator (TEG) converts fission heat into electricity. Cooling water removes waste heat out of the reactor. The thermal-hydraulic characteristics of heat pipes are simulated using thermal resistance network method. Thermal parameters of steady and transient conditions, such as the temperature distribution of every key components are obtained. Then the postulated reactor accidents for heat pipe cooled reactor, including power variation, single heat pipe failure and cooling channel blockage, are analyzed and evaluated. Results show that all the designed parameters satisfy the safety requirements. This work could provide reference to the design and application of the heat pipe cooled nuclear power source.

• 동력기계공학회지
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• 제18권4호
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• pp.23-28
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• 2014

In order to increase the performance of conventional hot water floor heating system, the bubble jet loop heat pipe for the system was developed. This experiment was conducted under next conditions : Working fluid was R-134a, charging ratio was 50%. A temperature of hot water, room temperature and flow rate were $60^{\circ}C$, $15^{\circ}C$ and 0.5~1.5 kg/min, respectively. The experimental results, show that bubble jet loop heat pipe had a high effective thermal conductivity of $4714kW/m^{\circ}C$ and a sufficient heat flux of $73W/m^2$ to heat the floor to $35^{\circ}C$ in case of the 1.5 kg/min of flow rate. So the bubble jet loop heat pipe has a possibility for appling of the floor heating system. Additionally, the visualization of bubble jet loop heat pipe was performed to understand the operating principle. Bubbles made by the narrow gap between inner tube and outer tube of evaporating part generate pulsation at liquid surface of working fluid. The pulsation had slug flow and wavy flow. So working fluid circulates in the bubble jet loop heat pipe as two phase flow pattern. And large amount of heat is transferred by the latent heat from evaporating part to condensing part.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 추계학술발표대회 논문집
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• pp.220-225
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• 2008

Cylindrical stainless-steel/sodium heat pipe for a high-temperature solar thermal application was manufactured and tested for transient and steady-state operations. Two layers of stainless-steel screen mesh wick was inserted as a capillary structure. The outer diameter of the heat pipe was 12.7 mm and the total length was 250 mm. The effective heat transport length, the thermal load, and the operating temperature were varied as thermal transport conditions of the heat pipe. The thermal load was supplied by an electric furnace up to 1kW and the cooling was performed by forced convection of air The effective thermal conductivity and the thermal resistance were investigated as a function of heat flux, heat transport length, and vapor temperature. Typical range of the total effective thermal conductivity was as low as 43,500 W/m K for heat flux of 176.4 kW/$m^2$ and of operating temperature of 1000 K.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.346-351
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• 2006

When metallic alloys are reacted to hydrogen, heat transfer of storage tank effects hydrogen storage rate and capacity. If pulsating heat pipe are used to improve heat transfer efficiency, production of hydrogen storage tank can be more simple and economical. Experiment of heat pipe was conducted by varying working fluids and heat flux. According to supply heat flux, test indicate that R-22 and R-l42b were found lower temperature difference between evaporator and condenser than R-134a and Ethanol. Thermal resistances of R-22 and R-142b were also lower than others. Using R-142b as a working fluid, heat pipe type hydrogen storage tank is tested in absorption and desorption processes.

• 지질공학
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• 제25권1호
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• pp.131-148
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• 2015

본 연구는 지열시스템 열교환 효율의 개선방안을 모색하기 위한 것으로 금속재질의 열교환기인 동관 및 스테인레스관과 기존 지열시스템에 많이 적용되는 PE관을 이용하여 지열열교환기의 재질에 따른 열전달 효율을 비교 분석하였다. 또한 지하매질의 지하수에 포함되어 있는 지하수열을 동시 활용할 경우의 열전달 효율 변화를 평가하고 그 적용성을 검토하였다. 열교환기 내의 유속, 유량 및 열교환기의 구경을 조절함으로써 열교환기의 재질에 따른 열전달 효율을 평가 후 현장실증시험 설계인자를 도출하였다. 열교환 효율과 유효 열전도도는 현장 열전달 효율 시험 및 열응답 시험을 통해 변화양상을 분석하였다. 분석결과 금속재질이 PE관에 비해 높은 열전달 효율을 보였으며, 유량에서의 구경증대에 따른 열전달효율은 크지 않았으나 유속에서의 구경증대에 따른 열전달효율은 높아지는 것을 확인하였다.