• 한국전산유체공학회지
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• 제7권2호
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• pp.43-52
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• 2002

This paper presents the numerical methodology of ATHOS3 code for thermal hydraulic analysis of steam generators in nuclear power plant. Topics include porous media approach, governing equations, physical models and correlations for solid-to-fluid interaction and heat transfer, and numerical solution scheme. The ATHOS3 code is applied to the thermal hydraulic analysis of steam generator in the Korea Kori Unit-1 nuclear power plant and the computed results are presented

• 한국유체기계학회 논문집
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• 제8권6호
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• pp.33-39
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• 2005

A thermal vapor compressor in which the subsonic/supersonic flow appears simultaneously, has been accurately designed through the CFD analysis for the various shape parameters such as the primary nozzle shape, converging duct shape, mixing tube diameter, and so on. The performance of the developed thermal vapor compressor has been experimentally verified to be installed in a Multi Effect Desalination(MED) plant as an important element. In this paper, the effects of each parameter are discussed on the basis of CFD results and the experimental results for various boundary conditions(motive pressure, suction pressure, and discharge pressure) are presented in compared with CFD results. The two results show a good agreement with each other within 2 % accuracy with regard to the entrainment ratio.

• 방사성폐기물학회지
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• 제2권1호
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• pp.13-22
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• 2004

This study presents the thermal analyses of a spent fuel dry storage cask under normal and off-normal conditions. The environmental temperature is assumed to be 15 $^{\circ}C$ under the normal condition. The off-normal condition has an environmental temperature of 38 $^{\circ}C$. An additional off-normal condition is considered as a partial blockage of the air inlet ducts. Two of the four air inlet ducts are assumed to be completely blocked. The significant thermal design feature of the storage cask is the air flow path used to remove the decay heat from the spent fuel. Natural circulation of the air inside the cask allows the concrete and fuel cladding temperatures to be maintained below the allowable values. The finite volume computational fluid dynamics code FLUENT was used for the thermal analysis. The maximum temperatures of the fuel rod and concrete overpack were lower than the allowable values under the normal and off-normal conditions.

• 설비공학논문집
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• 제20권10호
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• pp.645-653
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• 2008

Spiral-jacketed thermal storage tanks can greatly simplify solar heating systems while maintaining the thermal performance at a similar level as conventional systems with an external heat exchanger. Proper design of the spiral-jacket flow path is essential to make the most of solar energy, and thus to maximize the thermal performance. In the present work, computational fluid dynamics (CFD) analysis was carried out for a spiral-jacketed storage tank installed in a solar heating demonstration system. The results of the CFD analysis showed a good agreement with experimentally determined thermal performance indices such as the acquired heat, collector efficiency, and mixed temperature in the storage tank. This verified CFD modelling approach can be a useful design tool in optimizing the shape of spiral-jacket flow path and the flow rate of circulating fluid for better performance.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2642-2647
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• 2007

This study represents numerical study on the thermal and fluid flow characteristics of exhaust gas in a motorcycle muffler. The reference engine was used 124.cc small displacement. Numerical analysis with computational fluid dynamics(CFD) was carried out to investigate the exhaust gas that flow into a motorcycle muffler. The STAR-CD S/W used to three dimensional steady state CFD analysis in a muffler. And than We got the information of static pressure it is used to structural analysis ant the first baffle plate using the commercial CAE code ANSYS workbench. Exhaust gas flow third chamber from frist chamber and running second chamber. A simulation result shows that each chamber of muffler temperature is about 460 K, 445 and 463K and pressure is about 22,000 Pa, 16,000 Pa and 10,000 Pa.

• 한국유체기계학회 논문집
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• 제17권6호
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• pp.5-12
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• 2014

Organic Rankine Cycle is widely used to convert the low-grade thermal energy to the electrical energy. However, usually available thermal energy is not supplied constantly. This makes hard to use positive displacement expanders. Hence, turbo-expander has merits to apply as an expander in ORC because it can operate well off-design points even though the mass flowrate is fluctuated. The thermal energy fluctuation causes the turbo-expander to operate in partial admission. In addition, supersonic nozzles are required so that the partially admitted turbine operates efficiently. In this study, R245fa was chosen as a working fluid of ORC. A design method and an analysis technique of supersonic nozzle based on R245fa were developed. The shape of the nozzle was designed by the characteristic method. The thermal properties within the nozzle were estimated and the predicted results were agreed well with the computed results.

• 한국가시화정보학회지
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• 제21권2호
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• pp.63-71
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• 2023

Energy storage and distribution technologies are emerging as important factors as research on renewable energy continues. Analyzing the thermal flow of phase change material inside a latent heat storage device and to predict the phase change time is an important part for improvement of thermal performance. However, most of the current research is based on the trial-and-error experimental investigation to measure the phase change time. Therefore, in this study, a can-type phase change material container was designed, and the numerical method for analyzing the thermal flow of phase change material was established and validated. The error rate of the phase change time between the numerical and experimental results was within 5%, which proves its reliability. As a result, the phase change finishing times were found to be 78 minutes with inlet fluid temperature of 80℃ during charging process, and 126 minutes with inlet fluid temperature of 9℃ during discharging process.

• 한국유체기계학회 논문집
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• 제8권6호
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• pp.40-46
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• 2005

Because of design and manufacturing costs, it is important to predict an expected life of bellows with component stresses of bellows as its design factors and material characteristics. In this study, numerical analyses are carried out to elucidate the thermal and flow characteristics of the bellows-seal gate and globe valves for high temperature (max. $600^{\circ}C$) and for high pressure (max. $104 kgf/cm^2$) conditions. Using commercial codes, FLUENT, which uses FVM and SIMPLE algorithm, and ANSYS, which uses FEM, the pressure and temperature fields are graphically depicted. In addition, when bellows have an axial displacement, thermal stress affecting bellows life is studied. The pressure and temperature values obtained from the flow analyses are adopted as the boundary conditions for thermal stress analyses. As the result of this study, we got the reasonable coefficients for valve and thermal stress for bellows, compared with existing coefficients and calculated values.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.147-150
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• 2006

A new class of heat transfer fluid with higher thermal conductivity, called nanofluids has been developed by Dr. S. Choi about decade ago. Many exciting experimental and theoretical results have been reported worldwide to predict the thermal conductivity enhancement of nanofluids, however, they sometimes show excessive large discrepancies between each other. This kind of disagreements in thermal conductivity data is partly ascribable to the accuracy of the measuring apparatus, that is, mostly used THM(transient hot-wire method). New thermal conductivity measuring method whose principle is different from that of conventional THM is proposed in this article and measurements and uncertainty analysis were made for the three nanofluid samples with different particle concentration of pure, 2% and 4% of AlN nanofluids.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 춘계 학술대회논문집
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• pp.75-78
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• 2005

A numerical investigation has been performed to discuss the radiation-affected steady-laminar natural convection in an enclosure under a large temperature difference. Due to inherent nature of this study, the Boussinesq approximation is no longer valid. Therefore the radiating fluid in an enclosure is treated as a ideal gas. To examine the effects of thermal radiation on thermo-fluid dynamic behaviors in complex geometries, two incomplete partitions are introduced. Based on the results of this study, the dispositions of incomplete partitions with radiatively participating medium are found to incur a distinct difference in fluid-dynamic as well as thermal behavior.