• Title/Summary/Keyword: Pressure difference

Search Result 465, Processing Time 0.145 seconds

Fiber-Optic Pressure Sensor Using a Rugate-Structured Porous Silicon Diaphragm Coated with PMMA (PMMA가 코팅된 주름 구조를 갖는 다공성규소 격판을 이용한 광섬유 압력센서)

  • Lee, Ki-Won;Cho, So-Yeon
    • Journal of Sensor Science and Technology
    • /
    • v.22 no.3
    • /
    • pp.227-232
    • /
    • 2013
  • In this research, fiber-optic pressure sensors were fabricated with rugate-structured porous silicon (RPS) diaphragms coated with PMMA (Polymethyl-Methacrylate). The reflectance spectrum of the PMMA/RPS diaphragm was almost the same as that of uncoated RPS diaphragm. However the mechanical strength of the PMMA/RPS diaphragm increased more than that of the uncoated diaphragm. As a result, the fiber-optic sensor fabricated with PMMA/RPS diaphragm could successfully detect more high pressure difference without diaphragm damage than the highest detectable pressure difference of the sensor with normal RPS diaphragm. The response data of the fiber-optic sensor recorded as a function of pressure difference were fitted by theoretical curves. During this process, elastic moduli of the used PMMA/RPS diaphragms were obtained numerically. The dynamic response properties of the fiber-optic sensor were also investigated under continuous variation of the pressure difference conditions.

Experimental Analysis for Variation of Pressure Difference on Flooding in PEM Fuel Cell at Cathode Channel Outlet (Cathode 출구 압력 변화에 따른 PEM Fuel Cell 내에서의 플러딩에 관한 실험적 연구)

  • Ahn, Deuk-Keun;Han, Seong-Ho;Kim, Kyoung-Rock;Choi, Young-Don
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.20 no.5
    • /
    • pp.390-396
    • /
    • 2009
  • The flooding, especially in channel, is one of the critical issue to put proton exchange membrane fuel cell (PEMFC) to practical use. In this paper, channel flooding was investigated the pressure difference at cathode channel outlet. A ratio of pressure difference changes to 25, 50% as its variation rate. The pressure variable rate is reflected in dimensionless number FN. As a result, modified dimensionless number $FN^*$ correctly predicted the channel flooding. This study analyzes that a variety of pressure difference is how to affect flooding at the cathode of the PEMFC.

An Experimental Study on the Analyze the Pressure Difference in case of Fire in Vertical Space of High-Rise Buildings (고층건축물 수직공간의 화재 시 압력차 분석을 위한 실험적 연구)

  • Huh, Yerim;Kim, HyeWon;Jin, SeungHyeon;Kwon, YoungJin
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • /
    • pp.111-112
    • /
    • 2020
  • As buildings in South Korea become more skyscrapers, the risk of fire is also emerging. Thus, regulations, regulations, and guidelines are being improved to prevent the spread of smoke in the event of a fire in high-rise buildings, but research on smoke flow and pressure distribution in vertical spaces is insufficient. Therefore, in this study, the temperature of each floor in the vertical space according to the size of the fire is measured through the miniature model experiment, and the pressure difference is calculated to establish the basic data for the improvement of the performance of domestic air supply facilities in the future. Thus, a scale model of one-sixth the size of the actual building was produced to measure the temperature, and the pressure difference was derived by substituting the value for the expression. The pressure difference varies depending on the size of the cause of the fire, and it is believed that the differential pressure and conditions of the building should be taken into account before calculating the supply volume for the analysis of the pressure difference according to the size of the cause of the fire in the event of fire.

  • PDF

Simultaneous Detection Properties of Organic Vapor, Pressure Difference and Magnetic Field using a Rugate-structured Free-standing Porous Silicon Film (Rugate 구조를 갖는 자립형 다공성 실리콘 박막을 이용한 유기 증기, 압력차, 자기장의 동시 감응 특성)

  • Han, Seong-Beom;Lee, Ki Won
    • Journal of Sensor Science and Technology
    • /
    • v.26 no.3
    • /
    • pp.186-191
    • /
    • 2017
  • In this study, we investigated the simultaneous detection properties of organic vapor, pressure difference, and magnetic field using a single rugate-structured free-standing porous silicon (RFPS) thin film. Both the wavelength and the intensity of the rugate peaks were changed in the reflectivity spectrum measured at the thin film surface while the organic vapor was exposed to the RFPS thin film. However, when the pressure difference and the magnetic field were exposed to the film, only the rugate peak intensity was changed. Therefore, it is possible to distinguish whether or not the organic vapor is detected by simultaneously changing the rugate peak wavelength and intensity. In addition, a method of distinguishing between the pressure difference and the magnetic field detection signal has been derived by rapidly modulating the direction of the magnetic field. This study shows that it is possible to simultaneously detect and distinguish various objects using a single RFPS thin film, and it is found that porous silicon can be utilized as a sensor sufficiently.

Numerical Study on the Effects of Velocity Profile Distortion and Swirl on Pressure Difference of Orifice Flowmeter Due to Pipe structure (배관구조에 따른 속도분포 변형과 선회가 오리피스 유량계의 압력차에 미치는 영향에 대한 수치적 연구)

  • Kim, Hong-Min;Kim, Kwang-Yong;Her, Jae-Young
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.27 no.10
    • /
    • pp.1450-1456
    • /
    • 2003
  • Three-dimensional pipe flows with elbows, tees and headers in three different pipe systems are calculated to estimate the effect of asymmetry of axial velocity profile and swirl on measuring accuracy of an orifice flowmeter. It is evaluated how the pressure difference across the orifice is dependent on the upstream straight pipe length and how swirl intensity, swirl angle, and axial velocity distribution affect the measuring error of the orifice flowmeter. From the results, it is found that variation of the pressure difference across the orifice is negligible in case that maximum swirl angle is less than 2$^{\circ}$, and also that the pressure difference across the orifice is more sensitive to the asymmetry of axial velocity profile rather than the swirl intensity.

Endurance of Pneumatic Valve with a Multi-bender PZT Actuator (적층 벤더형 압전식 공압밸브의 내구 특성)

  • Yun, So-Nam;Park, In-Sub
    • Journal of Power System Engineering
    • /
    • v.18 no.2
    • /
    • pp.31-36
    • /
    • 2014
  • In this paper, pneumatic valve which consists of valve body, valve controller, nozzle and a multi-bender PZT actuator was suggested and fabricated. The fabricated pneumatic valve was experimented for performance evaluation. From the experimental results, we know that the flow rate of the suggested valve is 23 lpm at the pressure difference of 1bar and the maximum flow rate is 30 lpm at the pressure difference of 4 bar. The flow rates after endurance test of 9.8 million were 22.57 lpm and 28.62 lpm at the pressure difference of 1bar and 4bar, respectably. Finally, it was verified that the B10 life of the suggested pneumatic valve is over 50 million.

A Study on the Pressure Difference of Smoke Control Influence Factor in the Super High-rise Building (초고층 건물의 제연영향요소에 따른 수직피난공간 압력분포 시뮬레이션)

  • Choi, Seung-Hyuck;Lee, Dong-Yun;Jun, Hyun-Do;Lee, Dong-Yun
    • Proceedings of the SAREK Conference
    • /
    • /
    • pp.130-135
    • /
    • 2009
  • These days, the super high-rise buildings construction plans are increased in Korea. But the stack effect in the super high-rise building interrupts the smoke control system's operation because of pressure difference, so it is more dangerous than the general building when firing. Therefore it needs to study about the pressure difference in the super high-rise buildings. We research the smoke control influence factor in the super high-rise building. Reflecting the influence factor, the simulation is practiced the case by case.

  • PDF

A Study on Ventilation and Heat Transfer Coefficient of Passive Ventilation Skin (패시브환기외피의 통기성능 및 열관류율에 대한 연구)

  • Lee, Tae-Cheol;Son, Yu-Nam;Yoon, Seong-Hwan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.24 no.9
    • /
    • pp.679-684
    • /
    • 2012
  • This paper aims to evaluate performances of ventilation and insulation of 6types PVS(Passive ventilation skin) by numerical simulation. The results are as follows. 1) The result of Performance of ventilation by pressure difference, it was shown that the amount of ventilation changed bigger under 1Pa and amount of ventilation increased according to increase opening area (${\alpha}A$). Although same opening area of PVS, it can predict that pressure differences cause ventilation differences. 2) In case of same opening area of PVS, however, it was changed the amount of ventilation each types of PVS that is distinguished opening area by flow coefficient. 3) Dynamic U-value that represents performance of insulation PVS was similar change upper ${\alpha}A40\;cm^2/m^2$, great change in casse of 0.1 Pa pressure difference. In case of ${\alpha}A10\;cm^2/m^2$, it was changed bigger under 0.3 Pa pressure difference, ${\alpha}A20\;cm^2/m^2$ of PVS was changed under 0.2 Pa pressure difference.

Experimental Study on Estimation of Oxidation Rate of PM inside of Diesel Particulate Filter (DPF내 포집된 입자상 물질의 산화율 산출을 위한 실험적 연구)

  • Shim, Beomjoo;Park, Kyoungsuk;Jo, Kyuhee;Lee, Hyeongjun;Min, Byeongdu
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.21 no.2
    • /
    • pp.98-103
    • /
    • 2013
  • Conventional method to estimate mass of particulate matter accumulated in diesel particulate filter is to use pressure difference between upstream and downstream of the filter. Then measured pressure difference should be compared that of clean condition which is no particulate matter accumulated in DPF. During regeneration soot oxidation is also estimated by same method. This methodology, however, has demerit on accuracy because of pressure difference deviation of clean DPFs and pressure difference caused by non-carbon based PM which is different from that of caused by carbon based PM. This study suggests new methodology to estimate accumulated soot oxidation rate through exhaust gas characteristics during regeneration. Results, more high accuracy of soot oxidation was obtained by analysis of relationship between fuel mass and concentration of carbon dioxide and oxygen.

A Study on the Noise Reduction and Performance Improvement of the Hot Water Distributing System (시스템분배기 소음방지 및 성능개선방안 연구)

  • Kim, Yong-Ki;Lee, Tae-Won;Han, Tae-Su;Yoo, Sun-Hak
    • Proceedings of the SAREK Conference
    • /
    • /
    • pp.1055-1060
    • /
    • 2009
  • Noise is one of the major environmental problems in human life. But hot water distributers with the flow rate control valve bring about often noise according to the heating control condition in residential buildings. The sound power level increased as the flow rate and pressure difference increased. And thus, experimental analyses for the flow rate control and the pressure difference control were carried out in this study to reduce the noise emitted from the flow rate control valve. As the results, the flow rate control method using a SMA(Shape Memory Alloy)-valve and the flow rate control system using a pressure difference sensor can be expected to control noise in the region of below 50 dB of sound power level.

  • PDF