• 자원환경지질
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• 제50권3호
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• pp.225-238
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• 2017

본 연구에서는 스팀주입중력법 (Steam Assisted Gravity Drainage, SAGD)을 이용한 오일샌드 개발 시 적지 선정을 위한 대안적 척도가 제시되었다. 기존 SAGD 공법 적용 시 스팀주입효율이 우수한 지역을 선정하기 위해 비투멘이 함유될 가능성이 큰 고투수성 퇴적층의 누적 층후가 주로 이용되었다. 그러나 고투수성 퇴적층의 누적 층후 외에도 수직 평균거리 또한 스팀주입효율에 큰 영향을 미칠 것으로 판단하였다. 따라서 본 연구에서는 해당 두 가지 척도(즉, 누적 층후도 및 수직 평균거리)가 SAGD 스팀주입효율에 미치는 영향에 대한 비교 및 분석이 이루어졌다. 이를 위해, 구성 암상 간 특정 전이확률을 기반으로 발생시킨 누적 층후 및 수직 평균거리가 상이한 다양한 가상의 2차원 저류층에 대해 고온 고압 증기 주입 모사를 실시한 후 생성된 스팀챔버의 크기를 비교 및 분석하였다. 2차원 SAGD모사 결과, 투수성 퇴적층의 수직 평균두께가 두꺼운 지역이 누적 층후가 두꺼운 지역보다 더 넓은 범위의 스팀챔버를 형성하는 것을 확인하였다. 따라서 최적의 오일샌드 개발 입지 선정 시, 기존에 이용되고 있던 누적 층후뿐만 아니라 투수성 퇴적층의 수직 평균거리도 함께 고려하였을 때 더욱 적합한 SAGD공법의 최적 입지를 선정할 수 있을 것으로 판단된다.

• 한국유체기계학회 논문집
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• 제17권1호
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• pp.5-11
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• 2014

The purpose of this paper is to investigate an analytical approach for opening performance evaluation of the nuclear pressure safety valve based on standard codes such as ASME or KEPIC. It is well-known that safety valve is considered as one of pressure relief valves for protecting a boiler or pressure vessel from exceeding the maximum allowable working pressure. When pressure in a container reaches its set pressure, the safety valve commences discharging the internal fluid by a sudden opening called as popping. Safety valve is usually evaluated by set pressure, full open, blow-down, leakage and flow capacity. The test procedure and technical requirement for performance evaluation is described in international code of ASME code such as BPVC. The opening characteristics of steam safety valve can be analyzed by computational fluid dynamics (CFD) and steam shaft dynamics. First, the flow analysis along opening process is simulated by running the CFD models of the ten types of opening steps from 0 to 100%. As a analysis result, the various CFD outputs of flow pattern, pressure, forces on the disc and mass flow at each simulation step is demonstrated. The lift force is calculated by using the forces applied on disc from static pressure and secondary flow. And, the effect of huddle chamber or control chamber is studied by dynamic analysis based on CFD simulation results such as lift force. As a result, dynamics analysis shows opening features according to the sizes of control chamber.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.415-420
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• 2009

Selective Catalytic Reduction(SCR) has been used for the reduction of $NO_x$ in a steam supply boiler. Recently, the reduction of $NO_x$ becomes an important research field because of its negative effect on an environment. Shape optimization of circular poles installed in the chamber, which is located in upstream of a SCR, has been performed using response surface method and three-dimensional Navier-Stokes analysis to enhance gas flow uniformity. Three design parameters, diameter, arranging angle and stretching ratio of circular poles, are considered in the present study. Throughout the shape optimization of a circular pole, gas flow uniformity is successfully increased by decreasing local recirculation flow in a square duct chamber. Recirculation flow observed in the corner of the square duct can be reduced by proper installation of a guide vane or a blunt body. Detailed flow characteristics are also analyzed and discussed.

• 한국수소및신에너지학회논문집
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• 제28권5호
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• pp.570-576
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• 2017

Gas turbine system with steam injection has shown outstanding advantages such as high specific power and NOx reduction. In the present work, a comparative exergetic analysis was carried out for Steam Injected Gas Turbine (STIG), Regenerative Steam Injected Gas Turbine (RSTIG), and Regenerative After Fogging Gas Turbine (RAF). Effects of pressure ratio, steam injection ratio and steam injection method on the system performance was theoretically investigated. The results showed that the order of the highest exergy efficiency is RSTIG, RAF, and STIG for low pressure ratios but STIG, RSTIG, and RAF for high pressure ratios. In each arrangement, the combustion chamber has the highest exergy destruction and the compressor has the second one.

• Journal of Animal Science and Technology
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• 제62권4호
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• pp.475-484
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• 2020

This study was conducted to evaluate the effect of the thickness of corn flakes produced by pressurized steam chamber (PSC) on rumen fermentation characteristics and nutrient degradability in Hanwoo and Holstein cows. Corn flakes were treated by PSC, in three groups based on corn flake thickness: < 2.5 mm (T1), 2.5-3.0 mm (T2), and > 3.0 mm (T3). Corn flake thickness significantly influenced pH (p < 0.01) and propionate concentration (p < 0.05) and slightly but not significantly influenced acetate, butyrate, and total-volatile fatty acids (T-VFA) concentrations. The dry matter (DM) degradability increased significantly with a reduction in corn flake thickness (p < 0.01), being significantly greater in T1 and T2 than T3 groups (p < 0.01) and similar between T1 and T2 groups throughout whole incubation time. Also, starch degradability was the lowest in T3 groups than others (p < 0.01). Thus, the present results showed that considering the production efficiency and economic feasibility, the optimal thickness of corn flakes produced in a PSC is recommended to be 2.5-3.0 mm.

• 항공우주시스템공학회지
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• 제14권5호
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• pp.66-72
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• 2020

본 연구에서는 증기발생기 내부로 냉각수 공급 시 화염에 의한 냉각수 분사 노즐 손상이 없도록, 초반 냉각수 공급량을 늘리는 방안에 대한 연구를 진행하였다. 초기 증기발생기 시험 시 벤추리만 사용하여 유량을 제어하였는데, 초반 유량 안정화 구간 동안 연소실 내부로 냉각수 공급이 되지 않아 냉각수 노즐의 손상이 발생하였다. 이를 해결하기 위해 벤추리와 오리피스를 병렬로 구성하여, 초반 공급 유량을 늘림으로써 냉각수 매니폴드와 연소실 사이 차압을 형성시켜 냉각수를 공급하였다. 수류시험을 통해 벤추리와 오리피스 공급 시퀀스를 확립하였으며, 최종 검증을 위해 연소실험을 진행하였다. 실험 결과 연소 초반 지속적으로 냉각수를 공급하는 것을 확인하였으며, 냉각수 노즐 손상 없이 성공적으로 실험을 수행하였다.

• 한국압력기기공학회 논문집
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• 제11권2호
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• pp.13-19
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• 2015

Steam generator is one of the most important component of nuclear power plant, and it's integrity and reliability are to be assured to high level by pre-service inspection and in-service inspection. To improve the reliability of steam generator heat exchanger tubes and to secure the management of nuclear power plant safely, KHNP CRI recently has developed eddy current testing system for steam generator. KHNP CRI have performed a series of experimental verification and field application to confirm the performance of the developed ECT system in accordance with ASME Code requirements. The ECT system consists of a remote data acquisition unit, an ECT signal acquisition and analysis software, a water chamber robot controller and a probe push-puller. In this paper, we will details of the developed ECT system and the software and their experimental performance. And also we will report the field applying performance and the issues for further steps.

• Nuclear Engineering and Technology
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• 제34권4호
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• pp.344-357
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• 2002

The present paper reports spontaneous steam explosions observed in fuel coolant interaction experiments using prototypic reactor materials. Pure ZrO$_2$ and a mixture of UO$_2$ and ZrO$_2$ are used. A high temperature molten material in the form of a jet is poured into a subcooled water pool located in a pressure vessel. An induction skull melting technique is used for the melting of the reactor material. In both tests using pure ZrO$_2$ and a mixture of UO$_2$ and ZrO$_2$, either a quenching or a spontaneous steam explosion was observed. The morphology of debris and pressure profile clearly indicate the differences between the qunching cases and explosion cases. The dynamic pressure. dynamic impulse, water temperature, melt temperature, and static pressure Inside the containment chamber were measured . As the spontaneous steam explosion for the reactor material is firstly observed in the present experiments, the results of present experiments could be a siginificant step forward the understanding the explosion of the reactor material.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1520-1524
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• 2004

This paper describes the development of a robotic maintenance system for use in a maintenance operation of the nozzle dam in a water chamber of a steam generator at the Kori nuclear power plant in Korea. The robotic maintenance system was designed to minimize the personnel exposure to a hazardous radioactive environment. This robotic maintenance system is operated by a teleoperated control which was designed to perform the nozzle dam maintenance tasks in a remote manner without endangering the human workers. Specific maintenance tasks involve the transportation, insertion, and removal of nozzle dams in a water chamber inside a steam generator via a narrow man-way entrance port. The developed robotic maintenance system has two major subsystems: a two degrees of freedom guiding device acting as the main guiding arm and a master-slave manipulator with a kinematic dissimilarity. The mechanical design considerations, control system, and capabilities of the robotic maintenance system are presented. Finally, a graphical representation of the nozzle dam maintenance processes in a simulated work environment are also demonstrated.

• 한국수소및신에너지학회논문집
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• 제21권4호
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• pp.286-294
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• 2010

According to the propagation of fuel cell system, the importance of that system efficiency is being magnified. Thus, the efficiency improvement of reformer which is the important part of fuel cell system will be required. In structural aspect, the reformer is classified into cylindrical and plate type. Plate type reformer features better maintenance and space efficiency compared with cylindrical type. In this study, we changed the shape of combustion chamber to improve the reforming efficiency. And then we performed the CFD simulation to predict the spacial distribution of temperature. Analysis cased contains with baffles, fins, baffles and fins, and without those. In case of only with-baffle, temperature distributions were uneven because the high temperature stream was concentrated near the baffle end. In case of with-fin, the temperature distributions were relatively even than other cases.