• 제목/요약/키워드: Rated pressure

검색결과 120건 처리시간 0.025초

급기가 프란시스 수차의 수압 맥동에 미치는 영향 (Effect of Air Admission on Pressure Pulsation in a Francis Turbine)

  • 전윤흥;박시훈;최한수;박준관
    • 신재생에너지
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    • 제10권4호
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    • pp.9-15
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    • 2014
  • In this study pressure and shaft torque pulsation were measured with variation of head and flow during the model test for a 15 MW Francis Turbine. Pressure pulsations were measured at the inlet of the spiral casing and 4 points in the cone of the diffuser and shaft torque pulsation at the upper position of the turbine. The maximum amplitude of pressure pulsation appeared 2.03% of the maximum rated head with the frequency of 25% of the rated revolution and at the guide vane opening of $10^{\circ}$. Shaft torque pulsation appeared 0.01% of the rated shaft torque, fairly low value. Air was admitted through the cone and pressure pulsation gradually decreased with increase of air flow and kept nearly constant after 5% of the rated flow. A new Francis turbine of which specific speed is 115 m-kW had been designed to rehabilitate the old one and the model test was performed at EPFL. The commercial code, STAR-$CCM^+$ was used for numerical simulation of flow.

초고압 시스템의 안전성 확보에 대한 연구 (A Study of Safety Acquirement for an Assessment of Ultra High Pressure System)

  • 이기천;김형의;김재훈
    • 한국안전학회지
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    • 제25권5호
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    • pp.7-14
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    • 2010
  • Ultra high pressure system, which can be generally increased over 1,000bar, needs to have sealing mechanism to protect leakage and selection of the materials used in the intensifier. Components such as pressure vessel, hydraulic hose assembly, accumulator, hydraulic cylinder, hydraulic valve, pipe, etc., are tested under the impulse-pressure conditions. Components need to be tested under 1.5 to 3 times of rated pressure to check the tolerance even though rated pressure range of these components are not ultra high pressure. So, the ultra high pressure system needs to be equiped to test components. In this study, safety assessments of ultra high pressure system which are using failure analysis of components, changing the types of the control system, and finite element analysis with static condition, are investigated.

원자력 발전소 고압터빈의 교축여유(Throttle Margin) 최적화 연구 (Study on Optimization of Throttle Margin in High Pressure Turbine of Nuclear Power Plant)

  • 고우식
    • 동력기계공학회지
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    • 제14권4호
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    • pp.43-49
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    • 2010
  • In the present study, optimization of throttle margin for high pressure turbine to be retrofitted or partially modified for power uprating or life extension in nuclear power plant, has been performed to increase the electrical output. Throttle margin for high pressure turbine is required to maintain all the time the rated power by opening more of governor valves whenever inlet pressure is decreased due to the tube plugging of steam generator. If throttle margin of high pressure turbine is too much compared to remaining lifetime, loss of electrical output due to pressure drop of governor valves is inevitable. On the contrary, if it is too little, the rated power operation can not be accomplished when inlet pressure of high pressure turbine is dropped after many years operation. So, throttle margin for high pressure turbine in nuclear power plant is compromised considering for the degradation of steam generator, governor valve capacity, manufacturing tolerance of high pressure turbine, future plan of power uprating, and remaining lifetime of power plant.

차축의 중량 분포와 타이어의 공기압이 트랙터 작업의 연료 효율에 미치는 영향 (Effects of Distribution of Axle Load and Inflation Pressure of Tires on Fuel Efficiency of Tractor Operations)

  • 이진웅;김경욱;김동현;최규정
    • Journal of Biosystems Engineering
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    • 제36권5호
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    • pp.303-313
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    • 2011
  • This study was conducted to investigate the effects of axle weight distribution and inflation pressure of tire on the fuel economy of tractors as well as operational range of tractor engine in terms of engine speed and power when a 4WD tractor of 38.2 kW rated power at 2500 rpm is used for plowing and flooded-field rotavating in paddy fields. (1) Plowing operation required an average engine power of 9.6~13.5 kW which equals 25~35% of rated PTO power. Engine speed ranged from 1,320.4 to 1,737.4 rpm, work velocity from 3.4 to 4.8 km/h, and fuel consumption from 3.2 to 4.2 L/h, respectively. (2) Flooded-field rotavating required an average engine power of 11.5~18.5 kW which equals 30~48.4% of rated PTO power. Out of this 6.2~12.2 kW was used for PTO power. Engine speed ranged from 1,557 to 2,067 rpm, work velocity from 2.5~5.4 km/h and fuel consumption from 3.2~5.5 L/h, respectively. (3) Axle weight distribution, inflation pressure of tire and moisture content of soil did not affect significantly the specific volumetric fuel consumption but affected significantly the fuel consumption per unit area of operation. Fuel savings amounted to 65% in plowing operation and 20% in flooded-field rotavating when the axle weight distribution and inflation pressure of tire were optimally adjusted. (4) Optimal adjustment of axle weight distribution and inflation pressure of tire are expected to save fuel consumption by 10~65% per unit area of operation in plowing and 10~20% in flooded-field rotavating.

공기청정기 시험기의 센서신호 오차가 공기청정기 성능 평가에 미치는 영향 (Effects of Sensor Errors in Air Cleaner Testing on the Cleaner Performance Estimation)

  • 이천환;김민영;이수민
    • 한국수소및신에너지학회논문집
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    • 제34권1호
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    • pp.77-82
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    • 2023
  • The fuel cell in fuel cell electric vehicle utilizes oxygen in the atmosphere, which requires the use of an air cleaner system to minimize the intake of harmful pollutants. To estimate the performance of the air cleaner system, the pressure drop between the filter inlet and outlet is used under the rated air flow condition. In this study, the effect of sensor error in this air cleaner testing is experimentally carried out. It is found that the errors of the temperature sensor does not significantly affect the estimation of pressure drop. However, in the case of the pressure sensor, 5% sensor error results in the error of pressure drop estimation by 3%. Therefore, it is recommended that the measurement accuracy of the pressure sensor mounted in test system should be maintained at less than 5%.

3차원 형상계측법을 이용한 토양변형 측정 (Measurements of Soil Deformation Using 3-Dimensional Form Determination)

  • 전형규
    • Journal of Biosystems Engineering
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    • 제26권5호
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    • pp.409-414
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    • 2001
  • This paper reports a technique for measuring a three-dimensional soil deformation and a simplified method to determine the three-dimensional contact area of agricultural tires in a soil bin. A Pirelli 12.4R28 radial-ply tire was used on soft soil. Effects of dynamic load and inflation pressure were determined using the equipment for measuring soil deformation on the soil surface. Soil deformation measurements were made under three conditions of over-load (59kPa-14.2kN), rated-load (108kPa-11.8kN) and under-load (157kPa-9.3kN) in the combinations of the inflation pressures (kPa) and the tire load (kN). The results from three conditions were shown that the contact area of the over-load increased considerably bigger than those of the rated-load and the under-load. Therefore, to regulate soil deformation, the inflation pressure and the tire load should be set according to the soil conditions.

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노인의 주관적 건강상태와 관련요인에 관한 연구 (Self-rated Health and its Associated Factors in the Elderly)

  • 원종순;전혜진;이혜련
    • 문화기술의 융합
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    • 제5권4호
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    • pp.217-225
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    • 2019
  • 본 연구는 노인이 주관적으로 평가하는 건강상태를 알아보고 이와 관련된 요인을 파악하기 위한 서술적 상관관계 연구이다. 연구 대상은 60세 이상의 재가 노인으로, 일반적 특성, 생활습관, 질병, 투약, 우울, 불면증 등의 건강관련 특성이 포함되어 있는 질문지를 이용하여 설문조사를 하였고, 혈압 측정 및 신체계측, 지질 및 공복 혈당을 측정하였다. 211명의 자료를 분석한 결과 주관적으로 건강한 편이라고 평가한 경우는 78.2%로 나타났으며 이와 관련된 요인은 질병(OR:10.83, 95% CI:2.47-47.43), 우울(OR=2.50, 95% CI=1.20-5.18), 운동(OR=3.01, 95% CI=1.40-6.47)으로 나타났다. 그러므로 신체적 질병, 우울과 같은 정신 건강문제 뿐 아니라 운동과 같은 생활습관을 고려한 노인 건강증진 프로그램 개발이 필요하다.

정압 베어링을 적용한 수소 액화 공정용 터보 팽창기 개발 (Development of Turbo Expanders with Hydrostatic Bearings for Hydrogen Liquefaction Plants)

  • 이동현;김병옥;박무룡;임형수
    • Tribology and Lubricants
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    • 제37권3호
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    • pp.91-98
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    • 2021
  • This paper presents a hydrostatic bearing design and rotordynamic analysis of a turbo expander for a hydrogen liquefaction plant. Th~e turbo expander includes the turbine and compressor wheel assembled to a shaft supported by two hydrostatic radial and thrust bearings. The rated speed is 75,000 rpm and the rated power is 6 kW. For the bearing operation, we use pressurized air at 8.5 bar as the lubricant that is supplied to the bearing through the orifice restrictor. We calculate the bearing stiffness and flow rate for various gauge pressure ratios and select the orifice diameter providing the maximum bearing stiffness. Additionally, we conduct a rotordynamic analysis based on the calculated bearing stiffness and damping considering design parameters of the turbo expander. The predicted Cambell diagram indicates that there are two critical speeds under the rated speed and there exists a sufficient separation margin for the rated speed. In addition, the predicted rotor vibration is under 1 ㎛ at the rated speed. We conduct the operating test of the turbo expander in the test rig. For the operation, we supply pressurized air to the turbine and monitor the shaft vibration during the test. The test results show that there are two critical speeds under the rated speed, and the shaft vibration is controlled under 2.5 ㎛.

Evaluation of the Functional and Non-functional Seat Sponge Effect in Sitting Chairs

  • Min, Seung Nam;Park, Se Jin;Subramaniyam, Murali;Lee, Heeran
    • 대한인간공학회지
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    • 제33권4호
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    • pp.255-265
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    • 2014
  • Objective: The purpose of this study was to evaluate comfort levels of functional and non-functional chairs using subjective comfort rating, interface pressure measurement, muscle activity measurement, and skin temperature measurement. Background: Chairs are used for a prolonged period of time for sitting in many places such as the office, at university, at school, in industry, and so on. Almost all people use chairs in their everyday life. The functional properties of the chair are associated with comfort. Method: The subjective evaluation contains questions regarding chair comfort which can be rated with five point scale. The body-seat interface pressure was measured using a pressure mat system. The symmetry of sitting was measured using electromyography. The change in body part (thigh and buttock) temperature before and after sitting on a chair was measured with an infrared camera. Results: Participants rated significantly (p < 0.05) higher comfort scores for the functional chair in relation to the buttock and thigh region. Also, the participants felt a better cushion effect in the functional chair. When using the functional chair, lower interface pressure, better thermal comfort, and better symmetry of erector spinae muscle activity were observed. Conclusion: Overall, interface pressure measurement, muscle activity measurement, thermal imaging and subjective comfort score results showed that the functional chair was more comfortable than the non-functional chair. Application: The adopted methodologies could be used to measure the seating comfort of train seats.

변압운전 방식의 500MW 초임계압 석탄 화력발전소 터빈 우회계통에 제어에 관한 고찰 (A Study on Turbine Bypass System in a 500MW Rated Coal Fired Supercritical Thermal Power Plant with Sliding Pressure Operation)

  • 최인규;김종안
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2008년도 제39회 하계학술대회
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    • pp.1663-1664
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    • 2008
  • Many years ago, most of thermal power plants built in this country were of subcritical pressure, of medium or small size, of constant pressure operations and of drum type steam generators with circulation type boilers. But, nowadays almost all of them were of high efficiency, of supercritical pressure, of big capacity, of sliding pressure operations, and of once through type steam generators. Presently built once through boilers introduce turbine bypass systems to variable pressure operation which eliminates unexpected materials in boiler tube during startup, minimizes fuel loss by short startup period and eventually improve both total efficiency and power system stability.

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