• 한국산학기술학회논문지
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• 제12권3호
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• pp.1111-1116
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• 2011

열교환기는 자동차, 공조시스템 및 기타 다양한 산업시설에 이용되고 있어 그 수요가 매우 넓다. 보통 고효율의 루버핀 열교환기는 비오염 환경에 많이 사용되고 파형핀 열교환기는 건설 현장 등 오염이 문제가 되는 곳에 사용된다. 본 논문에서는 공기측과 오일측에 각기 다른 형태의 격자를 사용할 수 있는 듀얼셀 모델을 이용하여 오일쿨러나 연료쿨러에 쓰이는 전형적인 열교환기에 대한 방열 성능을 수치해석하였다. 먼저 풍동 실험을 통한 열교환기 방열성능 실험을 수행하여 1차원 방열성능 데이터를 확보하였다. 다음으로 3차원 수치해석 듀얼셀 열교환기 모델을 이용하여 통과 풍량에 따른 열교환량을 예측하였다. 이러한 모델은 통과 풍속의 불균일도에 따른 열교환량을 예측할 수 있어 방열설계 정확성 향상에 크게 기여할 수 있다.

• 한국태양에너지학회 논문집
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• 제31권3호
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• pp.101-108
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• 2011

This study aims to suggest an energy consumption improvement plan for university buildings through an analysis of energy consumption. Upon a simulation of subject building to interpret energy consumption, it was found that 154.07kWh/$m^2$ of energy is consumpted annually. Improvement of design elements can cut down the energy consumption to 135.61kWh/$m^2$ according to an energy reduction analysis related to envelope performance improvement. Additional improvement of lights and heat exchanger can curtail annual energy consumption to 108.32kWh/$m^2$. Also, an analysis of energy consumption while increasing indoor temperature gradually showed that the two factors are in proportion. $6^{\circ}C$ higher temperature requires over twice of the current energy. Based on this survey result, performance improvement due to building management and envelope elements which influence to building cooling and heating loads can curtail building energy consumption.

• 한국압력기기공학회 논문집
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• 제7권4호
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• pp.44-50
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• 2011

Turbulent mixing of hot and cold coolants is one of the possible causes of high cycle thermal fatigue in piping systems of nuclear power plants. A typical situation for such mixing appears in turbulent flow through a T-junction. Since the high cycle thermal fatigue caused by thermal striping was not considered in the piping fatigue design in several nuclear power plants, it is very important to evaluate the effect of thermal striping on the integrity of mixing tees. In the present work, before conducting detailed evaluation, three thermal striping evaluation methodology suggested by EPRI, JSME and NESC are analyzed. Then, a by-pass pipe connected to the shutdown cooling system heat exchanger is investigated by using these evaluation methodology. Consequently, the resulting thermal stresses and the fatigue life of the mixing tee are reviewed and compared to each other. Futhermore, the limitation of each methodology are also presented in this paper.

• 생물환경조절학회지
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• 제11권3호
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• pp.101-107
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• 2002

본 연구에서는 온실의 온풍식 난방시스템 연통에 장착할 수 있는 폐열 회수기의 성능을 개선하기 위하여 각각 상이하게 설계된 3개의 열교환 장치에 대해 열회수 성능을 실험적으로 비교 분석하였다. A형 열회수시스템의 경우, 초기 투자비용과 현재의 농용 전력요금 하에서 대체로 1년을 전후하여 투자에 대한 보상이 충분한 것으로 판단된다. B형 및 C형 열회수시스템의 경우, 열 회수용 공기 흐름방향이 180$^{\circ}$굴절로 저항이 크게 발생되어 송풍팬의 전압 증가에 따른 유속 증가가 미미하며 동일한 열 교환면적에서는 송풍팬의 공기저항 증대로 열 회수 성능이 현저히 개선되지는 못했지만, 직선형보다 B형의 경우 약 5%. C형의 경우 약 13%정도 높은 열 회수효율을 보였다. 송풍팬의 용량은 A형에 사용된 용량인 25m$^3$/min전후가 적절할 것으로 판단되며, 적정 송풍팬 용량 하에서 열회수성능은 헤어핀형이 직선형보다 효과적인 것으로 나타났다. 다만, 헤어핀형은 물론 직선형에서도 열교환 파이프의 배치밀도, 파이프 길이 및 두께 등의 변화에 따른 최적화 연구가 수반되어야 할 것으로 판단된다.

• 한국지진공학회논문집
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• 제24권3호
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• pp.123-128
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• 2020

Analysis of the 2016 Gyeongju earthquake and the 2017 Pohang earthquake showed the characteristics of a typical high-frequency earthquake with many high-frequency components, short time strong motion duration, and large peak ground acceleration relative to the magnitude of the earthquake. Domestic nuclear power plants were designed and evaluated based on NRC's Regulatory Guide 1.60 design response spectrum, which had a great deal of energy in the low-frequency range. Therefore, nuclear power plants should carry out seismic verification and seismic performance evaluation of systems, structures, and components by reflecting the domestic characteristics of earthquakes. In this study, high-frequency amplification factors that can be used for seismic verification and seismic performance evaluation of nuclear power plant systems, structures, and equipment were analyzed. In order to analyze the high-frequency amplification factor, five sets of seismic time history were generated, which were matched with the uniform hazard response spectrum to reflect the characteristics of domestic earthquake motion. The nuclear power plant was subjected to seismic analysis for the construction of the Korean standard nuclear power plant, OPR1000, which is a reactor building, an auxiliary building assembly, a component cooling water heat exchanger building, and an essential service water building. Based on the results of the seismic analysis, a high-frequency amplification factor was derived upon the calculation of the floor response spectrum of the important locations of nuclear power plants. The high-frequency amplification factor can be effectively used for the seismic verification and seismic performance evaluation of electric equipment which are sensitive to high-frequency earthquakes.