• Title/Summary/Keyword: valve rate

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Sliding Wear Properties of Graphite as Sealing Materials for Cut off Hot Gas (고온차단 기밀용 그라파이트의 고온 미끄럼마모 특성 평가)

  • Kim, YeonWook;Kim, JaeHoon;Yang, HoYeong;Park, SungHan;Lee, HwanKyu;Kim, BumKeun;Lee, SeungBum;Kwak, JaeSu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.11
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    • pp.1349-1354
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    • 2013
  • Sealing structure to prevent flowing hot gas into the driving device, located between the driving shaft and the liner of On-Off valve for controlling the hot gas flow path was studied. Wear occurs due to the constant movement of the driving shaft controlled by actuator on graphite as the sealing material. In this paper, the dynamic wear behavior in high temperature of graphite(HK-6) to be used as sealing material was evaluated. Reciprocating wear test was carried out for the graphite(HK-6) to the relative motion between shaft materials(W-25Re). The results of friction coefficient and specific wear rate according to contact load, sliding speed at room temperature and $485^{\circ}C$ considering the actual operating environment were evaluated. Through the SEM analysis of the worn surface, third body as lubricant films were observed and lubricant effect of third body was considered.

Fire-fighting Pump Approval Standard for Fire-fighting Trucks with an Additional Positive Displacement Pump (용적형 펌프를 추가한 소방자동차용 소방펌프의 성능 인정기준에 관한 연구)

  • Han, Yong-Taek;Sung, Ki-Chan;Min, Se-Hong
    • Fire Science and Engineering
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    • v.30 no.1
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    • pp.104-110
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    • 2016
  • Positive displacement pumps with high pressure and water capacity are used large fires in various high-rise buildings. This study provides information for a performance approval standard of fire pumps for fire trucks based on centrifugal pump standards enacted in 2012. An experiment was conducted with a positive displacement pump for three levels of performance from the approval standard (V-1, 2, and 3). The efficiency of the pump was included in the reference, which requires the approval of 65% performance, the same as a centrifugal pump. The water pressure is between 1.5 and 2.5 MPa, and the required flow rate was established as at least $0.31m^3/min$ and up to $3.0m^3/min$. A relief valve was added to adjust the shut-off pressure due to the structural characteristics of the positive displacement pump. A strainer was also installed to prevent damage to the inside of the pump due to foreign matter. However, the strainer includes a difference from the positive displacement pump to operate without a vacuum pump and the centrifugal pump. This is due to the additional approval standard portion of the positive displacement pump, which is expected to be selected for more variety of fire-fighting equipment and proactive responses to fire suppression in a high-rise buildings and large fires. In conclusion, this approval standard was enacted in January 2016.

The Methodology for Prediction and Control of Hazardous Chlorine Gas Flow Releases as Meteorological Data (기상조건에 따른 유해독성염소가스의 가상흐름누출에 관한 예측 및 제어론)

  • Kim, Jong-Shik;Park, Jong-Kyu
    • Applied Chemistry for Engineering
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    • v.10 no.8
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    • pp.1155-1160
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    • 1999
  • The screening methodology modeling, dispersion modeling procedures for continuous and instantaneous releases of the gas phase flow from the storage tank and pressure relief valve were considered. This study was performed to develop the screening methodology for prediction and control of hazardous/toxic gas releases by estimating the 1-hr average maximum ground-level concentration of $Cl_2$ gas vs. downwind distance by incorporating source term model including the general/physical properties of released material and release mode of the $Cl_2$ storage tank of the chemical plant facilities, dispersion model, and meteorological/topographical data into the TSCREEN model. As the results of the study, it was found that dispersion modes of the dense gas were affected by the state of the released material, the released conditions, physical-chemical properties of released material, and the released modes (continuous and instantaneous releases), and especially largely affected by initial (depressurized) density of the released material and release emission rate as well as the wind velocity. Especially, this study was considered to release hazardous material as meteorological data. It was thought that this screening methodology can be useful as a preliminary guideline for application of the refined analysis model by developing the generic sliding scale methodology for various senarios selected.

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On the Performance Test of the Piezoelectric-Hydraulic Pump (압전유압펌프 성능실험에 대한 연구)

  • Joo, Yong-Hwi;Hwang, Jai-Hyuk;Yang, Ji-Youn;Bae, Jae-Sung;Lee, Jong-Hoon;Kwon, Jun-Yong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.9
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    • pp.822-829
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    • 2015
  • In this paper, the piezoelectric-hydraulic pump with a piezostack actuator as a driving source has been designed, fabricated, and evaluated for its application to UAV's brake system. The performance requirements of the piezoelectric-hydraulic pump were decided based on the requirements analysis of the target aircraft brake system. The geometric design of the piezoelectric-hydraulic pump to meet the performance requirements of the pump was conducted, and all components of the pump including the spring sheet type check valves were machined with close tolerance. By constructing a test apparatus for the performance check of the piezoelectric-hydraulic pump, the performance characteristics of the pump, such as the outlet flow rate for load-free condition and the outlet oil pressure for closed loop condition, have been evaluated. It has been found by the performance test result that the developed piezoelectric-hydraulic pump satisfies the design requirements effectively.

Development of a New Commercial Grain Cooler (곡물냉각기의 개발)

  • 김동철;김의웅;금동혁;한종규
    • Food Science and Preservation
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    • v.11 no.2
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    • pp.250-256
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    • 2004
  • The objectives of this study were to develop a new commercial grain cooler suited to domestic weather and post-harvesting conditions for paddy, and to evaluate the performance. A prototype grain cooler capable of cooling paddy of 200 tons within 24 hours was developed. The grain cooler was designed to control the refrigeration capacity from 0 to 100% by controlling the capacity of compressor with unloading solenoid valve and by changing the flow rates of hot refrigerant gas flowing into reheater and evaporator from compressor. And a controller with one chip microprocessor was developed to control temperature and relative humidity of cooling air. The maximum cooling capacity of the grain cooler was 35,284㎉/hr at condensing/evaporating pressure of 16.5/3.6 kgf/$\textrm{cm}^2$. Maximum flow rate of cooling air was 120 ㎥/min at static pressure of 279 mmAq. The total maximum required power was 22.8㎾, and total required energy was saved from 26.7 to 33.3% of maximum power depending on operating conditions. The coefficient of performance of refrigeration devices and total coefficient of performance of the grain cooler were 4.71 and 1.8, respectively.

A Study of the Fluidic Characteristics of High-Pressure Fuel Pumps for GDI Engines (GDI 고압펌프의 유동특성에 관한 연구)

  • Lee, Sangjin;Noh, Yoojeong;Liu, Hao;Lee, Jae-Cheon;Shin, Yongnam;Park, Yongduk;Kang, Myungkweon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.39 no.5
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    • pp.455-461
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    • 2015
  • A high-pressure fuel pump is a key component in a gasoline direct injection (GDI) engine; thus, understanding its flow characteristics is essential for improving the engine power and fuel efficiency. In this study, AMESim, which is a hydraulic analysis program, was used to analyze the performance of the high-pressure fuel pump. However, since AMESim uses a one-dimensional model for the system analysis, it does not accurately analyze the complicated flow characteristics. Thus, Fluent, computational fluid dynamics (CFD) software, was used to calculate the flow rates and net forces at the intake and discharge ports of the high-pressure fuel pump where turbulent flow occurs. The CFD analysis results for various pressure conditions and valve lifts were used as look-up tables for the AMEsim model. The CFD analysis results complemented the AMEsim results, and thus, improved the accuracy of the performance analysis results for the high-pressure fuel pump.

Characterization Tests on the SIT Injection Capability of the ATLAS for an APR1400 Simulation (APR1400 모의를 위한 ATLAS 안전주입탱크의 주입 성능에 관한 특성 시험)

  • Park, Hyun-Sik;Choi, Nam-Hyun;Park, Choon-Kyung;Kim, Yeon-Sik
    • Journal of Energy Engineering
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    • v.17 no.2
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    • pp.67-76
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    • 2008
  • A thermal-hydraulic integral effect test facility, ATLAS (Advanced Thermal-hydraulic Test Loop for Accident Simulation), has been constructed at KAERI (Korea Atomic Energy Research Institute). Recently several integral effect tests for the reflood period of a LBLOCA (Large Break LOss of Coolant Accident) of the APR1400 have been performed with the ATLAS. In the APR1400 a high flow condition is changed to a low flow condition due to an fluidic device during an operation of the SIT. As the self-controlled fluidic device was not installed in the ATLAS, a set of characterization tests was performed to simulate its injection capability from the SIT for the APR1400 simulation. In the ATLAS the required SIT flow rate in the high flow condition was acquired by installing orifices with an optimized flow area to throttle the SIT discharge line and the low flow condition was achieved by changing the opening of the flow control valve in the SIT injection line. The test results showed that the safety injection systems of the ATLAS could simulate the required high and low flow rates of the SIT for the APR1400 simulation efficiently.

Optimization of biomethane production by biogas upgrading process using response surface mothodolgy (반응표면분석을 이용한 바이오가스 고질화공정을 통한 바이오메탄)

  • Park, Seong-Bum;Sung, Hyun-Je;Shim, Dong-Min;Kim, Nack-Joo
    • Journal of Energy Engineering
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    • v.23 no.2
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    • pp.62-73
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    • 2014
  • This research was focused to apply response surface methodology for optimization of bio-methane production by biogas upgrading process. Methane concentration(Y1) and methane efficiency(Y2) on biogas upgrading process were mathematically described as being modeled by the use of the Box-Behnken design on response surface methodology. The results of ANOVA(analysis of variance) about models, the probability value of the methane concentration and methane recovery response surface model are 0.0001 and 0.0001, respectively and coefficient of determination($R^2$) are 0.9788 and 0.9710, respectively. The response surface model is proved of high reliability and suitability. The operation pressure had the greatest influence to methane concentration than other operation parameters and the PSA rotary valve velocity had the greatest influence to methane recovery than other operation parameters. Optimal condition of biogas upgrading process for production of $100Nm^3/hr$ bio-methane were operation pressure 8.0bar and outlet flow rate 31.55RPM, respectively. At that operation condition the methane concentration of bio-methane was 97.13% and methane recovery in biogas upgrading process was 75.89%.

Evaluation of characteristics for microbubble generation according to venturi nozzle specification (벤튜리 노즐 제원에 따른 마이크로버블 발생 특성 평가)

  • Lim, Ji-Young;Kim, Hyun-Sik;Park, Soo-Young;Kim, Jin-Han
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.9
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    • pp.6397-6402
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    • 2015
  • This research was performed to review operating parameters, optimum condition and check characteristic of microbubble generation for using bubble size distribution according to venturi specification. Optimum operating condition have airflow rate 0.3 LPM, 3 bar(pressure tank) and connecting nozzle directly(without valve), it is advantageous to generate microbubble. In case of characteristic of microbubble generation according to venturi specification, effect that nozzle specification affects bubble size distribution is low impact. But considering performance aspects, when using nozzle that throat diameter 3-4 mm, $D_{50}$ are $54.98-61.19{\mu}m$(D3L15, D4L15), fraction of bubble less than $50{\mu}m$ are 0.326, 0.345. And it is superior to others. Besides, $D_{50}$ and fraction of bubble less than $50{\mu}m$ of throat length 20 mm are $49.40-54.98{\mu}m$, 0.447, respectively And nozzle that throat length 20 mm is relatively tendency to generate microbubble stably.

The Physical Properties of Port Type Crack Injection Method Using Latex Elastic Storage Tube (라텍스 탄성 저장관을 활용한 포트식 균열주입 공법의 물리적 특성에 관한 연구)

  • Kim, Eun-Young;Sho, Kwang-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.2
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    • pp.68-75
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    • 2018
  • In this study, to solve the problems of the conventional crack repair and injection method, high elasticity latex was used as the material of the storage tube to withstand the high pressure in the center part differently from the general port. When the repair solution was injected into the crack part, The TPS method was developed so that the air existing in the TPS can be discharged. In addition, a new infusion port in which a valve blocking the backflow of the remediation solution was installed at the injection port was developed and the physical characteristics of the port were analyzed. As a result of the evaluation, it was found that the filling rate of the remedial solution was improved compared to the existing ordinary injector method, and the cracks were completely filled in the test conditions. Compressive strength and tensile strength after repair showed about 20% decrease after repair in case of using ordinary injector method, while TPS method showed about 2~7% increase after repair. The results of this study showed that the injection port method using the elastic storage tube increased the injection performance and the quality after repair compared to the conventional injector method. The result of this study is expected to be utilized as the basic data for application and commercialization of the result to the practical structure.