• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.273-279
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• 2008

The purpose of this study is not only to evaluate thermal performance but also to find the stress behavior of heat transfer tubes under the part load operation in Heat Recovery Steam Generator. Flow analysis was performed to know the behavior of exhaust gas from gas turbine and thermal performance was calculated using distribution of hot exhaust velocity. In addition, tubes temperature during operation were gathered from actual plant to verify the uneven flow distribution under part load operation. Stress analysis was performed using tubes temperature data gathered from actual plant under both part and full load operations to know the stress behavior of tubes.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.651-655
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• 2000

The objective of present work is to investigate experimentally the characteristics of heat transfer. A fluidized bed combustion has advantages of pollution control, fuel flexibility and excellent heat transfer. The present study investigates fundamental phenomena of bed-to-surface heat transfer in high temperature fluidized beds to improve design of immersed tube surface. The tested operating variables are bed temperature, supeficial velocity, mean size of bed material, and the rake angle of fin. Generally, heat transfer rates between the fluidized bed and immersed finned-tube are much higher than those of a smooth tube. A life time of finned-tube is generally longer than that of smooth tube.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.3
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• pp.263-268
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• 2007

The pressure drop and heat transfer coefficient were measured at room temperature in a CFB heat exchanger with multiple vertical tubes. The circulation rate of solid particles was also measured. The theoretical model for predicting heat transfer coefficient using the solid flowrate was developed in this study. The model predictions were compared with the measured heat transfer coefficient to show relatively good agreement.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.4
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• pp.109-121
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• 2004

A distributed nonlinear mathematical model for investigation of regenerative heat exchangers of both a continuous and periodic operation is described in the paper. The non-iterative numerical integration scheme for conjugate unsteady heat exchange problem of one dimensional flows and two dimensional matrix wall conductivity is developed. Case study of a regenerative heat exchanger with a rotary ceramic matrix is presented. The range of optimum rotation rates of the regenerator providing the greatest calorific efficiency is determined.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.6
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• pp.1959-1970
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• 1996

Effects of oscillatory flow upon heat transfer characteristics have been studied experimentally for oscillating flow in a circular tube. The experimental apparatus was designed to simulate the heat exchangers of the Stirling or Vuilleumier cycle machines and the test section consists of heater and cooler. Measurements were presented of heat flux, axial wall temperature distribution, and radial temperature profile of the working fluid for several cases of oscillation frequency and swept distance ratio. The influences of two main parameters, frequency and tidal displacement of the oscillation were investigated. Then the heat transfer coefficient at the heater is obtained. The carried by the authors with a assumption of oscillatory laminar slug flow.

• Bulletin of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.53-66
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• 1996

21세기를 바라보면서 물에 대한 많은 경고가 이어지고 있고 우리나라도 물 부족에 대한 영향을 서서히 피부로 느껴가고 있다. 이제 물은 천연의 혜택만은 아니며, 물의 상당향을 담수화 설비로 만들어 생산해야 되는 공산품으로 서서히 자리잡아 가고 있다. 따라서 담수화 설비의 기술적인 핵심을 역시 저렴한 담수의 생산, 즉 경제성을 갖기위한 기술개발에 중점이 될 것이다. 이를 위하여 최적 하이브리드 시스템을 위한 기술개발, 시스템의 대형화를 위한 연구, 증발법의 경우 오염방지기술(Fouling 방지), 전열향상을 위한 유동연구등이 수행되고 있으며, 역삼투막법의 경우에는 전처리 기술과 에너지 재이용을 위한 요소기술들이 연구되고 있다.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.828-833
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• 2001

In this study, an analysis tool to assess the susceptibility of steam generator tubes due to the flow-induced vibration was developed. The fluid-elastic instability analysis of the U-tube bundle for CE-type steam generator was accomplished. The effective mass distribution along the U-tube was obtained to calculate the natural frequency and dynamic mode shape. Finally, stability ratios for selected tubes are obtained.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.12
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• pp.989-995
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• 2002

A new fluidized bed heat exchanger for exhaust gas heat recovery is developed. Compared to the existing ones, the present heat exchanger system is featured by the particle fluidization method which does not depend on conventionally used baffle plate with holes and by the multiple downcomer tubes to extract heat energy from hot particle during the time particles moves down to be fed again to the hot gas line. Particles are introduced to the main hot gas stream alongside the pipe circumference. The heat exchanger performance and pressure drop are evaluated through experiments for the present gas-to-water heat exchanger system.

• The KSFM Journal of Fluid Machinery
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• v.7 no.4 s.25
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• pp.32-39
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• 2004

This study deals with the Benard Flow of Magnetic Fluids in a rectangular cavity which the ratio between height and width is 1 : 4 and the base side or left side is a heating face while other sides are to be cooling faces. When Magnetic field was equally impressed, considering the internal rotation of the elementary ferromagnetic particle, we found the following result from the numerical analysis of the GSMAC algorithm applied to the equation of the magnetic fluid. Benard flow is controlled by intensity and direction of magnetic fields, and critical point appears when especially magnetic field with a heating base and side area near H=-7000 and H=-10000 is applied.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.584-589
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• 1998

범용 전산유체 해석코드인 CFX 4.1을 사용하여 철재격납용기 표면을 전열면으로 이용하는 피동격납용기냉각계통에 대한 열전달 현상해석을 수행하였다. 철재격납용기 내부와 외부 채널에서 발생하는 열전달 현상을 모사하기 위하여 액막의 유동 및 온도계산 모델을 범용 전산유체해석코드인 CFX4.1에 적용하여 철재격납용기 내.외부의 표면을 흐르는 액막의 높이, 액막내 온도분포, 철재격납용기 내.외부의 온도, 유속 및 부피분율 등을 계산하는 복합 열전달 해석 방법론을 개발하였다. 해석결과는 향후 실험 둥을 통한 검증이 필요하나 피동형 격납용기템각계통에서 발생하는 물리적 현상들의 복합적인 거동 분석에 사용될 수 있는 것으로 평가되었다.