• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2003년도 하계학술대회 논문집
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• pp.46-46
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• 2003

• 설비공학논문집
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• 제13권5호
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• pp.368-376
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• 2001

Performance of heat exchanger was evaluated to heat exchanger using oscillating heat pipe for waste heat recovery of low temperature. Oscillating heat pipe used in this study was formed to the closed loop of serpentine shapes using copper tubes. Heat exchanger was formed to shell and tube type and composed of low finned tube. R-22 and R-141b were used to the working fluids of tube side and their charging ratio was 40%. And, water was used to the working fluid of shell side. As the experimental parameters, the inlet temperature difference of heating and cooling part of secondary fluid and the mass velocity of secondary fluid were used. The mass velocity of secondary fluid was changed from 90 kg/$m^2s\; to\;190 kg/m^2$s from the experimental results, heat recovery rate was linearly increased to the increment of the mass velocity of secondary fluid and the inlet temperature difference of secondary fluid. Finally, the performance of heat exchanger was evaluated by using $\varepsilon$-NTU method. It was found that NTU was about 1.5 when effectiveness was decided to 80%.

• 설비공학논문집
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• 제29권4호
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• pp.149-158
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• 2017

In general, the air-side j and f factors of evaporators or condensers are obtained through single-design tests performed under air-dry and wet-bulb temperatures. Considering that the indoor or outdoor air temperatures vary significantly during the operation of an air conditioner, it is necessary to confirm that the experimentally-obtained j and f factors are widely applicable under variable air conditions. In this study, a series of tests were conducted on a two-row slit-finned heat exchanger to confirm the applicability. The results showed that, for the dry-surface condition, the changes of the tube-side water temperature, water-flow rate, and air temperature had virtually no effect on the air-side j and f factors. For the wet condition, however, the f factor was significantly affected by these changes; contrarily, the j factor is relatively independent regarding this change. The formulation of the possible reasoning is in consideration of the condensation behavior underneath the tube. The wet-surface j and f factors are larger than those of the dry surface, with a larger amount for the f factor.

• 한국산학기술학회논문지
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• 제8권6호
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• pp.1337-1342
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• 2007

본 연구에서는 동시 냉난방 히트펌프용 열교환기의 성능평가 및 설계해석 기술의 확보를 위해 난방운전 온도조건에서 6종의 루버핀-관 열교환기의 공기측 열전달특성 및 마찰특성을 실험을 통하여 조사하였다. 실험을 위해 공기엔탈피방식의 칼로리미터와 항온수조를 이용하였다. 전열량의 증가는 핀피치보다 열수에 의해 더 크게 나타났고, 핀피치가 작을수록 열전달계수는 더 높았다. 또한 핀피치가 작을수록 열수증가에 의한 열전달계수의 증가폭이 커졌다. 핀피치와 열수변화에 대한 j-계수와 f-계수는 레이놀즈 수가 증가할수록 감소하였고, 레이놀즈 수 400부근의 영역에서 역전현상이 존재하였다.

• 대한기계학회논문집A
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• 제38권8호
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• pp.831-836
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• 2014

본 연구에서는 한국원자력연구원 내에 설치될 예정인 소듐시험 시설인 SELFA(Sodium Thermal-hydraulic Experiment Loop for Finned-tube Sodium-to-Air heat exchanger) 내에서 정상상태 가동온도가 $510^{\circ}C$의 고온 압력용기인 팽창탱크에 대해 고온 건전성 평가를 수행하였다. 팽창탱크에 대해 3 차원 유한요소해석에 기초하여 고온설계 기술기준인 ASME Section III Subsection NH 와 프랑스의 RCC-MRx 코드를 따라 크리프-피로 손상평가를 수행하였다. 평가결과 팽창탱크는 크리프-피로 설계 과도 하중 하에서 구조적 건전성을 유지하는 것으로 나타났다. 316L 스테인리스강 재질의 동 압력용기에 대해 정량적 코드 비교 분석을 수행하였다.

• 한국산학기술학회논문지
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• 제16권6호
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• pp.3698-3707
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• 2015

본 연구에서는 비대칭형 슬릿 핀 열교환기의 습표면 열전달 및 압력손실에 대하여 실험적으로 검토하였다. 비교를 위하여 널리 사용되는 루버 핀 열교환기에 대한 실험도 수행하였다. 실험범위에서 핀 핏치가 j와 f 인자에 미치는 영향은 크지 않았다. 또한 루버 핀 시료의 j와 f 인자가 슬릿 핀 시료의 값들보다 크게 나타났다. 1열의 경우 평균 j 인자와 f 인자는 27%, 31% 크고, 2열에서는 15%, 30% 크게 나타났다. 슬릿 핀과 루버 핀 모두 열수가 증가하면 j와 f 인자가 감소하였다. 슬릿 핀의 평균 j/f가 루버 핀보다 1열에서 3.4%, 2열에서 11.5% 크게 나타났다. 본 데이터로부터 새로운 상관식을 도출하였다.

• 한국압력기기공학회 논문집
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• 제6권1호
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• pp.65-71
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• 2010

The plugging rate of reheater tubes of Wolsung unit 1 nuclear power plant has been increased by corrosion and erosion since 1990. As the dimensions of the new first stage reheater bundle tubes which were supplied by Hanjung company to replace were different from old one, numerical calculations are carried out for flow and heat transfer in the reheater bundle tubes of the N.P.P. Numerical calculations consists of thermal performance, drain line pressure drop, flow change by pressure drop of line, stress analysis of finned tubes and analysis of flow induced vibration. Computational analysis using heat transfer research institute program is adopted to verify the results of the numerical calculations. It contains the evalution of performance in the system with view to location of the new reheater bundle and it shows the differences between the numerical calculation results and heat transfer research institute program output.

• 설비공학논문집
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• 제4권4호
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• pp.351-359
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• 1992

In order to improve the performance of heat exchanger, fluidized bed is often employed. The experiments are carried out in fluidized double pipe parallel flow heat exchanger in which finned tube is vertically immersed. And the heat transfer coefficients between the heated tube and fluidized bed of alumina beads(dp=0.41, 0.54, 0.65, 0.77mm) are calculated as a function of air fluidized velocity and pumping power. The effects of particle size, static bed height and pumping power on the heat transfer coefficients are investigated. And the heat transfer coefficients are compared with that of single phase forced convection heat exchanger. In particular, the heat transfer performance of each type heat exchanger is evaluated in relation to the pumping power.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1348-1354
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• 2009

The purpose of the present study is to investigate the flow resistance and the heat transfer characteristics of V type circular fin-tube heat exchanger. Four kinds of V type fin having the same fin area and the different span wise angle tested numerically. Test data for the heat transfer, pressure drop and fin temperature were shown and discussed. The pressure drop and heat transfer increased for decreasing the span wise angle up to 58% and 25% respectively.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.788-793
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• 2001

Finite element analysis was carried out to investigate the integrity and reliability of boiler module during sea transportation. The boiler module was supported by steel structure to relieve the instantaneous shock from oceanic wave and its primary parts were strengthened with several reinforcements. Finned tube walls which were used in the furnace wall were assumed as orthotropic plates having equivalent material properties. The bank tubes were also equivalently modeled in accordance with ASME B31.1 for the convenience of finite element modeling. The calculation results were compared with the yield stress of the material. In particular, the bank tube stress, which was evaluated by converting the calculated stresses in equivalent tubes into those in original tubes by using the ratio of diameter, was also examined with yield stress.