• 제목/요약/키워드: U-tube

검색결과 383건 처리시간 0.026초

CE형 증기발생기 전열관에 대한 유체탄성 불안정성 해석 (Analysis of Fluid-elastic Instability In the CE-type Steam Generator Tube)

  • 박치용;유기완
    • 한국소음진동공학회논문집
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    • 제12권4호
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    • pp.261-271
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    • 2002
  • The fluid-elastic instability analysis of the U-tube bundle inside the steam generator is very important not only for detailed design stage of the SG but also for the change of operating condition of the nuclear powerplant. However the calculation procedure for the fluid-elastic instability was so complicated that the consolidated computer program has not been developed until now. In this study, the numerical calculation procedure and the computer program to obtain the stability ratio were developed. The thermal-hydraulic data in the region of secondary side of steam generator was obtained from executing the ATHOS3 code. The distribution of the fluid density can be calculated by using the void fraction, enthalpy, and operating pressure. The effective mass distribution along the U-tube was required to calculate natural frequency and dynamic mode shape using the ANSYS ver. 5.6 code. Finally, stability ratios for selected tubes of the CE type steam generator were computed. We considered the YGN 3.4 nuclear powerplant as the model plant, and stability ratios were investigated at the flow exit region of the U-tube. From our results, stability ratios at the central and the outside region of the tube bundle are much higher than those of other region.

GM Tube 및 NaI(TI) 검출기를 사용한 Wide-Range 방사선 측정 시스템의 설계 (Design of Wide-Range radiation measurement system using GM Tube and NaI(TI) Detector)

  • 라승탁;이주현;이승호
    • 전기전자학회논문지
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    • 제21권2호
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    • pp.146-149
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    • 2017
  • 본 논문에서는 GM Tube 및 NaI(TI) 검출기를 사용한 Wide-Range 방사선 측정 시스템을 제안한다. 제안하는 시스템은 NaI(Tl) 검출기 및 GM Tube의 검출기 신호를 제어, 계수할 수 있게 최적화한 하나의 소형 모듈로 설계한 다. 방사선량은 2개의 검출기를 연동하여 Wide-range인 0.1uSv/h~10mSv/h 구간에서 측정되고, 측정구간이 중복되는 지점인 10uSv/h~100uSv/h에서는 2개의 검출기가 동시에 동작한다. 방사선량은 중첩된 방사선 측정 가능 구간에 대해 적정한 구간에서 해당 검출기 기능의 On/Off를 제어하는 Wide-Range 방사선 측정 알고리즘을 이용하여 선택 적용하였다. 제안된 시스템의 성능을 평가하기 위하여 공인시험기관에서 실험한 결과, 각 구간별로 측정 불확도가 ${\pm}7.5%$로 측정되어 국제 표준인 ${\pm}15%$ 이하에서 정상동작 됨이 확인되었다.

FPSO의 횡요 감쇠 장치에 대한 고찰 (A Study on Roll Reduction Devices for FPSOs)

  • 박인규;양진호;신현수
    • 한국해양공학회:학술대회논문집
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    • 한국해양공학회 2004년도 학술대회지
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    • pp.30-35
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    • 2004
  • Several roll motion reduction devices are reviewed and suggested for the application in FPSO. The firstly suggested solution is the shape of the bilge. The next is a bilge keel. The last suggestion is the ART (anti-rolling tank). Typical U-tube type ART is designed for a FPSO and examined extensively by model experiment. The model section was made of transparent acryl. Free decay test, forced oscillation test and wave test were carried out at a two-dimensional wave flume. U-tube type ART is effective only when the natural periods of ART and ship are same. Therefore, the divided U-tube type ART with split plate is suggested for the reduction of the roll motion of a FPSO over the wide range of the roll period.

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Feasibility Study of High-Efficiency Ground Heat Exchanger using Double U-tube through a Real-Scale Experiment

  • Bae, Sangmu;Kim, Jaemin;Nam, Yujin
    • KIEAE Journal
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    • 제17권4호
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    • pp.33-39
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    • 2017
  • Purpose: The use of renewable energy system is essential for building energy independence and saving energy consumption in the building sector. Among renewable energy technologies, ground source heat pump(GSHP) system is more energy-efficient and environmental-friendly than other heat source systems due to utilize stable ground heat source. However, the GSHP system requires a high initial installation cost and installation space in limited urban area, so it is difficult to have superiority in the market of heat source system. Therefore, it is necessary to develop the installation method of low-cost and improve system performance. This paper aims to evaluate the performance of double u-tube ground heat exchanger(GHX) and verify system feasibility through real-scale experiment. Method: In this study, the real-scale experiment of vertical closed-type GSHP system was conducted using double u-tube GHX and high-efficiency grout. Through the verification experiment, heat source temperature, heat exchange rate(HER) and seasonal performance factor(SPF) were measured according to the long-term operation. In addition, the feasibility analysis was conducted comparing to the single u-tube system. Result: In the results of experiment, average HER was 136.27 W/m and average SPF was 5.41. Furthermore, compared to the single u-tube, the installation cost of the developed system could be reduced about 70% in the same heating load condition.

표면 조도와 곡률 반경에 대한 U-자관 압력 손실의 상관관계 (THE CORRELATION OF PRESSURE DROP FOR SURFACE ROUGHNESS AND CURVATURE RADIUS IN A U-TUBE)

  • 박정후;장세명;이신영;장강원
    • 한국전산유체공학회지
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    • 제20권1호
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    • pp.39-46
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    • 2015
  • In this research, we studied the pressure drop affecting on the internal surface roughness and the curvature radius of a U-tube, which is used for the cooling system in PWR(Pressurized Water Reactor). Using ANSYS-FLUENT, a commercial code based on CFD(Computational Fluid Dynamics) technique, we compared a Moody chart with the Darcy friction factor changed by a range of various surface roughness and Reynolds numbers of a straight pipe model. We studied the effect giving variation about a range of various surface roughness and the curvature radius of the full scale U-tube model. The material of the heat transfer tube is Inconel 690 used in the steam generator. We compared the velocity distribution of selected 4 locations, and derived the correlation between the surface roughness and the pressure drop for the U-tube of each representative curvature radius using the linear regression method.

고도로 정렬된 TiO2 나노튜브의 제조와 활용 (Highly ordered TiO2 nanotubes; Synthesis and applications)

  • 유정은;이기영
    • 한국표면공학회지
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    • 제55권1호
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    • pp.1-8
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    • 2022
  • Titanium dioxide (TiO2) is one of the most intensively investigated materials in materials science. Mostly, TiO2 has been used in the form of nanoparticles, but recently new highly ordered TiO2 nanotubes (U-tube) has been introduced and applied to various applications due to their one-dimensional charge path way. In the present paper, we described the formation process and physical properties of U-tube then, gave examples of applications in sequence. Firstly, in photocatalysis, U-tube was used with Au/Pt co-catalysts and showed enhanced photogenerated H2 efficiency compared to bare TiO2. Secondly, photoelectrochemical performance of U-tube was evaluated with different heat-treatment temperatures. As a further application, two different types of electrical cell (Ti-TiO2-Pt and Ti-TiO2-PtNP) was configurated to observe memristive behavior of U-tube. Both cells behaved as switching electrodes and follow a memristive movement in the high and low resistance state extremely well with high reproducibility.

Fretting-Wear Characteristics of Steam Generator Tubes by Foreign Object

  • Jo Jong Chull;Jhung Myung Jo;Kim Woong Sik;Choi Young Hwan;Kim Hho Jung;Kim Tae Hyung
    • Nuclear Engineering and Technology
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    • 제35권5호
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    • pp.442-453
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    • 2003
  • This study investigates the safety assessment of the potential for fretting-wear damages on steam generator (SG) U-tubes caused by foreign object in operating nuclear power plants. The operating SG shell-side flow field conditions are obtained from three-dimensional SG flow calculation using the ATHOS3 code. Modal analyses are performed for the finite element modelings of U-tubes to get the natural frequency, corresponding mode shape and participation factor. The wear rate of U-tube caused by foreign object is calculated using the Archard formula and the remaining life of the tube is predicted. Also, discussed in this study is the effect of the flow velocity and vibration of the tube on the remaining life of the tube.

핀 부착 U형 복사튜브 버너의 열전달 및 연소성능 실험 (Heat Transfer and Combustion Characteristics and Performance of U type Radiation Tube Burner with fin)

  • 이현찬;유현석;이중성
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집D
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    • pp.516-521
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    • 2001
  • Present study deals with combustion characteristics and performance of U type radiation tube burner with fin which combustion capacity is 30,000kcal/hr and the maximum capacity of supply fuel is $30Nm^{3}/hr$. Temperature difference of radiation tube is about $173^{\circ}C$ at 25% capacity and this show relatively small temperature difference for convenient type. Thermal efficiency is satisfactory as $72{\sim}81%$. Also, radiative efficiency of radiation tube is $52{\sim}73%$. The efficiency of heat exchanger is $27{\sim}37%$. Therefore, radiative efficiency is improved to $1{\sim}10%$ after installing fin.

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U형 복사튜브 버너 연소특성 및 성능실험 (Combustion Characteristics and Performance of U type Radiation Tube Burner)

  • 이현찬;유현석;이중성
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 추계학술대회논문집B
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    • pp.710-714
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    • 2000
  • Present study deals with combustion characteristics and performance of U type radiation tube burner which combustion capacity is 30,000kcal/he and the maximum capacity of supply fuel is $3.0N m^3/hr$. Temperature range of radiation tube is maximum $170^{\circ}C$ and minimum $150^{\circ}C$ and this displays relatively small temperature range. And thermal efficiency is satisfactory as $75{\sim}80%$. Also, radiative efficiency of radiation tube is $52{\sim}63%$.

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임의형상을 갖는 납작관에서의 혼합대류 열전달 해석 (Analysis of Mixed Convection Heat Transfer in Arbitrarily Shaped Flat Tubes)

  • 박희용;박경우;이상철
    • 설비공학논문집
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    • 제13권5호
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    • pp.398-410
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    • 2001
  • The flow and heat transfer characteristics for three-dimensional mixed convection flows in a radiator flat tube with U--shaped grooves are analyzed numerically. The flow and temperature fields are calculated by using the modified SIMPLE algorithm for irregular geometry. One tube specification among the various flat tube exchangers is recommended by considering the heat transfer and pressure drop. The effects of variation of coolant flow conditions and external air conditions on the flow and the thermal characteristics for the selected tube are investigated. the results show that inlet velocity of coolant flow is the very important factor in heat transfer and pressure drop, and top side is better position than the others as fin cleave to tube.

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