• 한국군사과학기술학회지
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• 제24권6호
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• pp.629-637
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• 2021

For the stabilization of laser output power and wavelength of the high power fiber laser, the cooling plate must be properly taken into account. In this study, three analyzing methods which are heat transfer theory, CFD and experiment are used to analyze cooling plate performance by measuring pump Laser Diode(LD) temperature. Under limited operating conditions of a cooling plate, the internal flow of cooling plate is transitional flow so that the internal flow is assumed to be laminar and turbulence flow and conducted theoretical calculation. Through CFD, temperature of pump LD and characteristics of the internal flow were analyzed. By the experiment, temperature of pump LD was measured in real conditions and the performance of the cooling plate was verified. The results of this study indicate that three analyzing methods are practically useful to design the cooling plate for the high power fiber laser or similar things.

• 한국산학기술학회논문지
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• 제14권2호
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• pp.573-577
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• 2013

히트펌프는 에너지 효율이 높고, 지열, 폐열, 공기열 등 다양한 열원 사용이 가능하기 때문에 보급이 빠르게 확대되고 있다. 공기를 열원으로 이용하는 공랭식 히트펌프의 경우는 실외기 표면에 형성되는 서리를 제거하기 위해 제상운전이 요구된다. 일반적으로 사용하는 역사이클(reverse cycle) 제상운전 방법은 연속난방이 불가능하며 이로 인해 성능계수가 감소하는 원인이 된다. 본 연구에서는 실외기 코일용 휜-관 열교환기를 3열로 구성하고 난방과 제상이동시에 가능하도록 일정시간 간격으로 열교환기의 한 개의 열을 응축기로, 나머지 열은 증발기로 교번 운전을 수행하여 KS C 9306에 규정된 제상-난방 시험조건(건구온도 $2^{\circ}C$, 습구온도 $1^{\circ}C$)에서 최소 180분 이상 연속난방이 가능함을 실증하였으며 역사이클 제상방법을 사용하는 일반적인 히트펌프 대비 COP가 약 20% 향상됨을 알 수 있었다.

• 에너지공학
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• 제17권3호
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• pp.125-138
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• 2008

에너지원의 다양화와 효율적인 이용을 위하여 광역지역의 통합에너지관리 시스템 구축이 요구되고 있다. 본 보문에서는 이러한 필요성에 부응하여 광역에너지 네트워크 구축에 필요한 핵심기술을 발굴하여 이를 종합적으로 현장에 적용하는 기술개발 을 수행하고 있다. 이를 위해 IT기술과 접목한 광역 네트워크 열공급 최적화 통합시스템 구축 기술, 발생되는 배열을 이용한 열펌프와 같은 미활용에너지 이용기술, 다양한 열원을 이용한 열수송 및 축열 기술 등 새로운 시스템을 개발하고 이를 현장적용을 통해 경제성을 평가하여 최종적으로 실용화할 수 있는 사업화 모델에 대하여 기술하였다.

• 항공우주시스템공학회지
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• 제17권5호
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• pp.11-18
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• 2023

The architecture of the Fuel Thermal Management System (FTMS) in a commercial aircraft engine was built to model and simulate the fuel system. The study shows the thermal interactions between the fuel and engine lubrication oil through the mission profile of a high bypass ratio, two-spool turbofan engine. Fuel temperature was monitored as it flowed through each sub-component of the fuel system during the mission. The heat load in the fuel system strongly depended on the fuel flow rate, and was significantly increased for the periods of cruise and descent with decrease of fuel flow rate, rather than for the periods of take-off. Due to the thermal interaction in the pump housing, the fuel temperature at the outlet of the low-pressure pump was increased (4.0, 9.2, and 30.0) % over the case without thermal interaction for take-off, cruise, and descent, respectively.

• 한국수소및신에너지학회논문집
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• 제30권6호
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• pp.540-548
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• 2019

This study was conducted to develop insulation for solid oxide fuel cell (SOFC). The developed insulation is based on the lamination technology and the radiation shielding technology of the satellite insulation. The insulation material is consisting of insulation material for conduction resistance, spacer, and radiation shielding material. The experimental apparatus consisting vacuum bell jar, pump, heater and temperature recording device has developed to verify the performance of the insulation. The experimental values were used as reference data for the modeling development. In this paper, heat transfer is assumed to be one- dimensional phenomena for the prediction of insulation performance and internal temperature distribution in high temperature region of SOFC. The developed model was used to compare the performance difference of insulation types according to composition materials. The analysis result shows that the insulation including spacer and radiation shielding has better heat insulation performance than other cases. In this study, the thickness reduction effect of about 20% was shown compared to the insulation including only conductive material. It is noted that the radiant shielding material should be carefully selected for durability, because SOFC insulation should be used for a long time at high temperature.

• Journal of Advanced Marine Engineering and Technology
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• 제38권6호
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• pp.609-614
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• 2014

화산지형인 제주도의 지열에너지를 사용하기 위하여 지하공기를 측정하였을 때 지중 온도는 $15{\sim}18^{\circ}C$이며, 상대습도는 70~80%로 타 지역에 비하여 매우 높은 경향을 나타내고 있다. 본 연구는 제습기능 및 난방기능을 구비한 다단 제습 가열 열펌프 시스템의 개발에 관한 연구로써, 개발된 열펌프의 성능실험을 수행한 결과 흡입공기의 상태가 최저 $15^{\circ}C$, 60%인 경우 총제습량이 1.797(kg/h)로 나타났으며, 최고 $20^{\circ}C$, 80%인 경우 총제습량이 45% 증가한 3.269(kg/h)로 증가하여 충분한 제습이 이루어짐을 알 수 있다. 또한, 난방능력은 흡입온도 $17^{\circ}C$ 상대습도 70% 일 때 1.91로 가장 높은 효율을 얻을 수 있다.

• 한국자동차공학회논문집
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• 제22권5호
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• pp.20-28
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• 2014

The high velocity oxygen fuel spraying (HVOF) is a kind of surface modification process technology to form the sprayed coating layer after spraying the powder to molten or semi-molten state by the ultra-high speed at the high-temperature heat source and conflicting with a substrate. It is desirable to melt completely the thermal spray powder in order to produce the coating layer with an optimal adhesion, however, because a semi-molten powder in a spray process has the low efficiency and become a factor that degrades the mechanical property by the inducement of pore-forming within the coating layer. To improve the wear resistance, corrosion resistance and heat resistance, in this study, the plungers of high-speed and ultra-high pressure reciprocating hydraulic pumps for oil and water used in ironwork are produced with $420J_2$ and the coating layers of plungers are formed by the powders of WC-Co-Cr and WC-Cr-Ni including the high hardness WC. The surface of these plungers is modified by the super-mirror face grinding machine using variable air pressure developed in this laboratory, and then the characteristics of cross-sectional microstructure, and surface roughness and hardness values between no operation and 100 days-operation are examined and made a comparison. The fine tops and bottoms on surface roughness curve of oil-hydraulic pump plunger sprayed by WC-Cr-Ni are molded more and higher than those of water-hydraulic pump sprayed by WC-Co-Cr because the plunger diameter of oil-hydraulic pump is 0.4 times smaller than that of water-hydraulic pump and the pressure of oil-hydraulic pump exerted on the plunger is operated with the 70 bars higher than that of water-hydraulic pump. As a result, it is found that the values of centerline average surface roughness and maximum height for oil-hydraulic pump plunger are bigger than those of water-hydraulic pump plunger.

• 한국가스학회지
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• 제18권4호
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• pp.13-20
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• 2014

상업용 천연가스 배급 시스템에서 천연가스의 공급압력은 압력조절밸브를 사용하여 제어하며 이때 막대한 압력에너지가 낭비된다. 이러한 폐압에너지는 터보 팽창기와 같은 터보기계를 사용하여 회수할 수 있으나 팽창과정에서 발생하는 Joule-Thompson 효과에 따라서 큰 온도강하가 발생한다. 터보 팽창기 전단 또는 후단에 보일러를 설치하여 영하의 온도를 방지할 수 있으며 또한 보일러를 대체하여 연료전지나 가스엔진의 폐열을 이용하여 천연가스를 예열할 수도 있으나 하이브리드 시스템의 구동을 위해 운영규모에 따라 일정량을 소모해야 한다. 이 연구에서는 천연가스가 가지고 있는 압력에너지를 활용하여 천연가스의 소모 없이 터보 팽창기와 연결된 히트펌프를 구동하여 천연가스를 예열하는 시스템을 제안하고 증발온도, 응축온도 및 작동유체의 변화에 따른 시스템의 열역학적 특성을 분석하였다. R717 냉매가 예상 작동범위 내에서 가장 높은 COP와 가장 낮은 압축일을 나타내 제안된 하이브리드 시스템에 적합함을 확인하였다. 보일러시스템과의 경제성 분석을 통해 천연가스를 LNG 형태로 수입하고 있는 국내의 경우 히트펌프 하이브리드 시스템이 경쟁력 있음을 확인하였다.

• Nuclear Engineering and Technology
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• 제41권8호
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• pp.1115-1126
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• 2009

As one of the ways to enhance the economical features in sodium-cooled fast reactor development, the concept of an integrated steam generator and pump system (ISGPS) is proposed from a structural point of view. And the related intermediate heat transfer system (IHTS) piping layout compatible with the ISGPS is described in detail. To assure the creep design lifetime of 60 years, the structural integrity is investigated through high temperature structural evaluation procedures by the SIE ASME-NH computer code, which implements the ASME-NH design rules. From the results of this study, it is found that the proposed ISGPS concept is feasible and applicable to a commercial SFR design.

• 한국기계가공학회지
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• 제12권6호
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• pp.152-158
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• 2013

The purpose of this study is to investigate cooling performance of high power LEDs from 100 to 200 W class by using a jet impingement cooling module. The numerical analysis of forced convection cooling inside cooling module is carried out using a multi-purpose CFD software, FLUENT 6.3. In the experiments, the LED cooling system consists of jet impingement module, heat exchanger, water reservoir, and pump. In the present study, the cooling performance of jet impingement cooling module is investigated to determine the effect of the heat sink types on the impinging surface, the space and length of fins. Numerical and experimental studies show the reasonable agreement of LED metal PCB temperature between those results and give the optimized design parameters such as the space of fin and the length of fin. Also, the pin fin type of heat sink is found to be more efficient than the plate type heat sink in jet impingement cooling.