• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.1999-2011
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• 1995

Computer simulation was conducted to study performance characteristics of air-cooled condenser of a double effect absorption heat pump with variations of saturation pressures and mass flow rates of the refrigerant ; volume flow rates, relative humidities and temperatures of the air The vertically installed condenser had the staggered tube array with continuous plate fins of wavy type. When the saturation pressure of the condenser was decreased from 760 torr to 20 torr, heat transfer rates and condensing rates of refrigerant were decreased. If excess refrigerant flows in the condenser, the pressure and saturation temperature of the condenser were increased which makes the refrigerating capacity of an absorption heat pump reduced.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.45-49
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• 1999

본 논문은 전력전자 시스템의 방열판 시스템에 대한 이론과 실제 시스템을 고찰하고 있다. 본 논문에는 공냉식과 수냉식 방열 시스템에 관한 내용이 있다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.6
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• pp.740-748
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• 1999

This research was concerned with the enhancement of heat transfer by surfactant added to the aqueous solution of LiBr. Different vertical tubes were tested with and without an additive of normal octyl alcohol. The test tubes were a bare inner surface, groove inner surface, corrugated inner surface and spring inserted inner surface tubes. The additive concentration was about 0.08 mass%. The heat transfer coefficient was measured as a function of film Reynolds number in the range of 20~200. Experiments were tarried out at higher cooling water temperature of $35^{\circ}C$ to simulate an air cooling condition for several kinds of absorber testing tubes. The experimental results were compared with cases without surfactant. The enhancement of heat transfer by Marangoni convection effect which was generated by addition of the surfactant is observed in each test tube. Especially, it is clarified that the tube with an inserted spring has the highest enhancement effect.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.6 no.3
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• pp.194-201
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• 1977

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.3
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• pp.13-19
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• 2000

In the present study, a program for predicting thermal performance of an air cooled condenser is illustrated. Heat transfer equations of single phase and two phase flow are formulated into the form that is convenient to incorporate the local analysis method. The resulting equations are solved by temperature and mass correction methods. Empirical equations for both side fluids are incorporated in the caculation procedures. In order to compare the calculation results, superheat temperature of steam are varied. The tube length of superheated zone, wall temperature, temperature profile along the tube and steam qualities are predicted.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.1
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• pp.42-51
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• 1998

A 150 m$\^$3//hr, 30 kg/cm$\^$2/, air-cooled 3-stage reciprocating air compressor is designed to be used in starting large diesel engines of ships. A basic design procedure is presented to meet the targeted pressure and flow rate, and especially a volumetric efficiency of 80%. Temperature and stress analysis of the 1st stage cylinder are performed using axisymmetric FEM modelings. The dynamics of valve system is analyzed and stress at the 1st stage valve seat caused by valve impact is evaluated. To reduce friction loss and wear at the compressor engine system tribological design issues are reviewed and good design practices are suggested. Finally, forced-air pin-type interstage coolers are designed to dissipate generated compression heat at each stage.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.4
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• pp.453-462
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• 1994

An unsteady quasi one-dimensional model of momentum, heat and mass transfer in a falling film of a vertical plate absorber which is cooled by air was developed using the integral method. Energy conservation of the absorber wall is considered in the model. The model can predict absorption rate, film thickness and mean velocity as well as concentration and temperature profiles. Predictions of steady state temperature and concentration profiles for LiBr/water system for constant wall temperature condition are in good agreement with the two-dimensional finite difference method solutions. Effects of operating conditions, such as convective heat transfer coefficient between the cooling air and the absorber wall, cooling air temperature and film thickness at inlet, on absorption rate of water vapor into LiBr/water solution were shown.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.6
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• pp.163-168
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• 2001

Vibration problems occurred in an air cooled heat exchanger with axial flow fan for a petrochemical plant were investigated. Experimental field test and theoretical verification were performed. To find the main cause of the high vibration of the fan at the air inlet of the axial fan, the frequency spectrum was measured. The natural frequency of the driving support of the heat exchanger was numerically calculated. Both of the measured and the natural frequency were approximately equal to the blade passing frequency. Because it was difficult to modify the structure of the driving support during the normal operation of the plant, the blade number of the fan was increased, which greatly reduced the vibration level of the heat exchanger.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.932-933
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• 2011

지속적인 경제발전 및 이상 기후변화 등으로 인한 전력수요의 지속적 증가로 2010년에 최대 66,511MW, 2011년에는 4월 현재까지 최대 68,154MW를 기록하고 있어 원활한 전력공급을 위한 전력설비의 지속적인 건설이 요구되고 있다. 그러나 건설지역 주민들의 민원 등으로 인해 건설은 갈수록 어려워지고 있는 실정이다. 한전에서는 변전소 건설의 경제성을 확보하고 변전소 건설 부지면적 및 건물면적을 최소화한 154kV Compact형 변전소를 개발하게 되었다. 이를 위해서는 변전소 면적의 상당부분을 차지하고 있는 변압기 설치면적 최소화가 필수적이다. 이를 위해 변압기 설치공간 최소화하고 냉각효율 및 민원 등을 고려한 냉매냉각방식(HCFC:Hydro Chloro Carbons, 수소화염화불화탄소)의 적용을 추진하였으나 HCFC는 오존파괴물질로 규정되어 생산과 수입이 규제될 예정으로 한전은 냉매냉각방식의 대안으로 기존 수냉식 냉각방식의 환경문제, 냉각탑 관리의 어려움 등과 물 비산에 따른 상하수도 이용요금 부담 등의 단점을 개선한 공냉형 수냉식 냉각방식을 개발하게 되었다. 본 논문에서는 154kV 변압기 공냉형 수냉식 냉각방식의 개발내용 및 운전현황에 대해 기술하고자 한다.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.2 no.1
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• pp.57-60
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• 1973