• 한국전산유체공학회지
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• 제17권4호
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• pp.41-48
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• 2012

A numerical analysis of thermal stratification in the upper plenum of the MONJU fast breeder reactor was performed. Calculations were performed for a 1/6 simplified model of the MONJU reactor using the commercial code, CFX-13. To better resolve the geometrically complex upper core structure of the MONJU reactor, the porous media approach was adopted for the simulation. First, a steady state solution was obtained and the transient solutions were then obtained for the turbine trip test conducted in December 1995. The time dependent inlet conditions for the mass flow rate and temperature were provided by JAEA. Good agreement with the experimental data was observed for steady state solution. The numerical solution of the transient analysis shows the formation of thermal stratification within the upper plenum of the reactor vessel during the turbine trip test. The temporal variations of temperature were predicted accurately by the present method in the initial rapid coastdown period (~300 seconds). However, transient numerical solutions show a faster thermal mixing than that observed in the experiment after the initial coastdown period. A nearly homogenization of the temperature field in the upper plenum is predicted after about 900 seconds, which is a much shorter-term thermal stratification than the experimental data indicates. This discrepancy is due to the shortcoming of the turbulence models available in the CFX-13 code for a natural convection flow with thermal stratification.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.113-116
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• 2007

Performance of a steam reformer can be improved by using a coaxial cylindrical reactor, because the design can enhance the heat transfer for the steam reforming reaction, which is the one of main rate-determining steps of overall reactions. The objective of this study is to investigate the coaxial cylindrical reactor numerically. Pseudo-homogeneous model and one medium approach are incorporated for the chemical reactions, and models are validated with experimental results. The catalyst of the coaxial cylindrical reactor is 67% for one of the cylindrical reactor, but fuel conversion of the coaxial cylindrical reactor is increased by 10%. Heat flux profiles are investigated by modified Nusselt number and heat flux which is transported from the product gas to the catalyst bed affecting performance of the steam reformer.

• 신재생에너지
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• 제17권2호
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• pp.40-49
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• 2021

This paper explains the development process of methane decomposition to hydrogen and carbon black using solar thermal energy. It also demonstrates the advantages and disadvantages of five different reactors for each development stage, including the reactor's experimental results. Starting with the initial direct heating type reactor, the indirect heating type reactor was developed through five modifications. The 40-kWth solar furnace installed at the Korea Institute of Energy Research was used for the experiment. In the experiment using the developed indirect heating reactor, an 89.0% methane to hydrogen conversion rate was achieved at a methane flow rate of 40 L/min, obtained at about twice the flow rate compared to previous advanced studies.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.728-744
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• 2024

The presence of hydrogen absorbed by zirconium-based cladding materials during reactor operation can trigger degradation mechanisms and endanger the rod integrity. Ensuring the durability of the rods in extended time-frames like dry storage requires anticipating hydrogen behavior using numerical modeling. In this context, the present paper describes a hydrogen post-processing tool for Falcon - HYPE, a PSI's in-house tool able to calculate hydrogen uptake, transport, thermochemistry, reorientation of hydrides and hydrogen-related failure criteria. The tool extracts all necessary data from a Falcon output file; therefore, it can be considered loosely coupled to Falcon. HYPE has been successfully validated against experimental data and applied to reactor operation and interim storage scenarios to present its capabilities.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 춘계학술발표회
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• pp.37-38
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• 2005

• 대한기계학회논문집B
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• 제34권5호
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• pp.553-561
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• 2010

한국원자력연구원에서는 초고온가스로를 모사할 수 있는 중형 헬륨 회로를 건설 중에 있다. 이 실험헬륨 회로에서 두 개의 전기 가열기가 헬륨 유체를 1 ~ 9 MPa 의 압력 하에서 $950^{\circ}C$ 까지 가열하게 된다. 이 실험 헬륨 회로의 설계 사양을 최적화하기 위하여, 본 연구에서는 두 개의 가열기 중 하류에 위치한 고온헬륨가열기 안의 복합열전달 현상을 전산유체역학으로 해석하였다. 해석 결과에서 헬륨 가열기 내 최대 온도는 허용 한계를 넘지 않았고, 이로써 선정된 기하구조의 열적 특성은 설계요건을 만족함이 확인되었다.

• Korean Chemical Engineering Research
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• 제59권3호
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• pp.467-479
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• 2021

Abstract: A kinetic model was developed for the dehydration of ethanol to ethylene based on two parallel reaction pathways. Kinetic parameters were estimated by fitting experimental data of powder catalysts in a lab-scale test, and the effectiveness factor was determined using data from pellet-type catalysts in bench-scale experiments. The developed model was used to design a multitubular fixed-bed reactor (MTR) and an adiabatic reactor (AR) at a 10 ton per day scale. The two different reactor types resulted in different process configurations: the MTR consumed the ethanol completely and did not produce the reaction intermediate, diethyl ether (DEE), resulting in simple separation trains at the expense of high equipment cost for the reactor, whereas the AR required azeotropic distillation and cryogenic distillation to recycle the unreacted ethanol and to separate the undesired DEE, respectively. Quantitative analysis based on the equipment and annual energy costs showed that, despite high equipment cost of the reactor, the MTR process had the advantages of high productivity and simple separation trains, whereas the use of additional separation trains in the AR process increased both the total equipment cost and the annual energy cost per unit production rate.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.671-674
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• 2011

한국기계연구원에서는 원자로냉각재펌프의 완전특성을 시험할 수 있는 시험 설비를 구축하였다. 이 설비는 유량은 최대 2,000 m3/hr, 동력은 최대 132 kW까지 펌프 및 수차의 시험이 가능하다. 본 논문에서는 완전특성 시험장치 및 시험방법, 이를 이용한 원자로냉각재펌프의 시험결과를 소개하고자 한다.

• 상하수도학회지
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• 제18권3호
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• pp.307-311
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• 2004

The objective of this work is to evaluate the hypothesis that a good technique for supplying oxygen to the saturated zone in the presence of light nonaqueous phase liquid (LNAPL) pool contamination at the water table is to pass air through the unsaturated zone above the pool. This hypothesis was evaluated in experimental studies performed using a bench-scale, sand-tank reactor, Steady-state abiotic experiments in the sand-tank reactor with air flowing through the reactor headspace demonstrated that oxygen supply through the water table interface into the saturated zone was enhanced when an LNAPL (dodecane) pool was present at the water table. These experimental results confirmed the hypothesis that an LNAPL pool can serve as a high concentration oxygen source to the oxygen-limited area beneath the pool and, as a result, enhance the in situ biodegradation rate.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.276-276
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• 2003

This paper dealt with an experimental study on the free vibration of circular-tube-beam submerged in water. A circular-tube-beam is commonly founded on the nuclear fuel assembly system in nuclear reactor. The nuclear fuel assembly susceptible to flow-induced vibration in nuclear reactor. So, the nuclear fuel assembly be designed to avoid any resonance due to the vibration during the reactor operation. In the experiment, applied boundary condition is clamped-free and the effect of water height to natural frequency and damping is studied. The experiment in air and in water has been performed. Used experimental method is impact exciting method. The natural frequencies and damping ratio according to water height is presented.