• Title/Summary/Keyword: gas measurement method

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Uncertainty Assessment Using Monte Carlo Simulation in Gas Flow Measurement (기체 유량 측정에서 몬테 카를로 모사를 이용한 측정불확도 평가)

  • Lee, Dae-Sung;Yang, In-Young;Kim, Chun-Taek;Yang, Soo-Seok
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.12
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    • pp.1758-1765
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    • 2003
  • Monte Carlo simulation(MC) method was used as an uncertainty assessment tool for gas flow measurement in this paper. Uncertainty sources for gas flow measurement were analyzed, and probability distribution characteristics of each source were discussed. Detailed MC methodology was described including the effect of the number of simulation. The uncertainty result was compared with that of the conventional sensitivity coefficient method, and it was revealed that the results were different from each other for this particular gas flow measurement case of which the modelling equation was nonlinear. The MC was comparatively simple, convenient and accurate as an uncertainty assessment method, especially in cases of complex, nonlinear measurement modelling equations. It was noted that the uncertainty assessment method should be selected carefully according to the mathematical characteristics of the measurement.

Uncertainty Assessment of Gas Flow Measurement Using Multi-Point Pitot Tubes (다점 피토관을 이용한 기체 유량 측정의 불확도 평가)

  • Yang, Inyoung;Lee, Bo-Hwa
    • The KSFM Journal of Fluid Machinery
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    • v.19 no.2
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    • pp.5-10
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    • 2016
  • Gas flow measurement in a closed duct was performed using multi-point Pitot tubes. Measurement uncertainty was assessed for this measurement method. The method was applied for the measurement of air flow into a gas turbine engine in an altitude engine test facility. 46 Pitot tubes, 15 total temperature Kiel probes and 9 static pressure tabs were installed in the engine inlet duct of inner diameter of 264 mm. Five tests were done in an airflow range of 2~10 kg/s. The flow was compressible and the Reynolds numbers were between 450,000 and 2,220,000. The measurement uncertainty was the highest as 6.1% for the lowest flow rate, and lowest as 0.8% for the highest flow rate. This is because the difference between the total and static pressures, which is also related to the flow velocity, becomes almost zero for low flow rate cases. It was found that this measurement method can be used only when the flow velocity is relatively high, e.g., 50 m/s. Static pressure was the most influencing parameter on the flow rate measurement uncertainty. Temperature measurement uncertainty was not very important. Measurement of boundary layer was found to be important for this type of flow rate measurement method. But measurement of flow non-uniformity was not very important provided that the non-uniformity has random behavior in the duct.

NDIR Multi-Gas Measurement System for Air Quality based on Wireless Sensor Network (무선센서네트워크 기반 공기질 측정을 위한 비분산적외선 복합가스측정시스템)

  • Paik, Seung Hyun;Lee, Jun Yeong;Jung, Sang Woo;Park, Hong Bae
    • IEMEK Journal of Embedded Systems and Applications
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    • v.11 no.5
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    • pp.299-304
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    • 2016
  • As public interest in air quality and environment problem is increasing, many researches are being carried out the gas measurement system. Especially, Non-dispersive infrared (NDIR) measurements using Beer-Lambert gas sensing principle with very high selectivity and long life time are noted for reliable method. It is possible to detect various gases such as carbon dioxide (CO2), carbon monoxide (CO), and nitrogen dioxide (NO2), but many researches are mostly concentrated on CO2 sensor. The multi-gas measuring instrument is high price and unwieldy, therefore it is not suitable for wide area required numerous instrument. So we study the NDIR multi-gas measurement system for air quality based on wireless sensor network, and experiment the realized measurement system.

A Computational Work of Critical Nozzle Flow for High-Pressure Hydrogen Gas Mass Flow Measurement (고압수소 유량계측용 임계노즐 유동의 수치해석적 연구)

  • Lee, Jun-Hee;Kim, Heuy-Dong;Park, Kyung-Am
    • 유체기계공업학회:학술대회논문집
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    • 2006.08a
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    • pp.227-230
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    • 2006
  • The method of mass flow rate measurement using a critical nozzle is well established in the flow satisfying ideal gas law. However, in the case of measuring high-pressure gas flow, the current method shows invalid discharge coefficient because the flow does not follow ideal gas law. Therefore an appropriate equation of state considering real gas effects should be applied into the method. The present computational study has been performed to give an understanding of the physics of a critical nozzle flow for high-pressure hydrogen gas and find a way for the exact mass flow prediction. The two-dimensional, axisymmetric, compressible Navier-Stokes equations are computed using a fully implicit finite volume method. The real gas effects are considered in the calculation of discharge coefficient as well as in the computation. The computational results are compared with the previous experimental data and predict well the measured mass flow rates. It has been found that the discharge coefficient for high-pressure hydrogen gas can be corrected properly adopting the real gas effects.

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Quantitative Acetone PLIF Measurement of Fuel Distribution in a Gas Turbine Combustor Burner (아세톤 PLIF를 이용한 가스터빈 연소기 버너 출구 연료분포의 정량적 측정)

  • Jeon, Woo-Jin;Kim, Hyung-Mo;Lee, Kang-Yeop;Yang, Su-Seok
    • Journal of the Korean Society of Combustion
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    • v.15 no.4
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    • pp.43-52
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    • 2010
  • A non-intrusive measurement, Planar Laser Induced Fluorescence was employed to visualize and measure the fuel distribution of the non-reacting field at the burner exit of gas turbine combustor. Measurement techniques, image processing method and quantification procedure were presented. Also, concentration measurement with gas analyzer was carried out to verify the propriety of PLIF result. The PLIF result coincides well with gas analyzer measurement result. PLIF test result for several other conditions are mentioned as well.

Comparison of ISO-GUM and Monte Carlo Method for Evaluation of Measurement Uncertainty (몬테카를로 방법과 ISO-GUM 방법의 불확도 평가 결과 비교)

  • Ha, Young-Cheol;Her, Jae-Young;Lee, Seung-Jun;Lee, Kang-Jin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.38 no.7
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    • pp.647-656
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    • 2014
  • To supplement the ISO-GUM method for the evaluation of measurement uncertainty, a simulation program using the Monte Carlo method (MCM) was developed, and the MCM and GUM methods were compared. The results are as follows: (1) Even under a non-normal probability distribution of the measurand, MCM provides an accurate coverage interval; (2) Even if a probability distribution that emerged from combining a few non-normal distributions looks as normal, there are cases in which the actual distribution is not normal and the non-normality can be determined by the probability distribution of the combined variance; and (3) If type-A standard uncertainties are involved in the evaluation of measurement uncertainty, GUM generally offers an under-valued coverage interval. However, this problem can be solved by the Bayesian evaluation of type-A standard uncertainty. In this case, the effective degree of freedom for the combined variance is not required in the evaluation of expanded uncertainty, and the appropriate coverage factor for 95% level of confidence was determined to be 1.96.

New Method of Volume Measurement for Reference Weights of a Pressure Balance Using a Gas Pycnometer (기체용적계를 이용한 분동식 압력계용 기준분동의 새로운 부피측정 방법)

  • Lee, Yong Jae;Lee, Woo Gab;Mohammed, Mohammed Abdurahman;Park, Yon-Kyu;Oh, Chae Yoon
    • Journal of the Korean Vacuum Society
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    • v.22 no.5
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    • pp.231-237
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    • 2013
  • New method of volume measurement for reference weights of a pressure balance using a gas pycnometer is proposed. The result of volume measurement of proposed method shows the uncertainties of approximately 0.2% at the level of confidence of 95% for reference weights in the ranges of 1 kg, 2 kg, and 5 kg. This measuring system consists of a sample chamber, an expansion chamber, a precision pressure gage, a precison thermometer, a vacuum pump, and helium as a medium gas. The measurement principle of this proposed method is based on Boyle's law. This method will contribute a reliability of the volume measurements of reference weights for a pressure balance to the national measurement standard.

A Study on the Ventilation Efficiency of Apartment Housing Bathroom Based on the Flexible Installation Method of Exhaust Fan. (공동주택 욕실 배기팬의 플랙시블 덕트 시공상태에 따른 환기효율에 관한 연구)

  • Lee Kwang Myung;Ham Jin Sik
    • Journal of the Korean housing association
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    • v.16 no.1
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    • pp.73-79
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    • 2005
  • The ventilation efficiency of apartment housing bathroom has been measured by the flexible's diameter, length, and installation format to the exhaust In. The gas density attenuation method of Tracer Gas Method has been specifically utilized for this measurement. Full size mock-up of apartment housing bathroom, which was approximately $100 m^2$ in size, has been established for the ventilation emciency measurement. In addition, the ventilation efficiency has been studied by the possibility of air-supply In. The diameters of flexible are 100 mm, 125 mm, and 150mm. It also have the length of 1.0m, and 1.5 m. The installation formats are I shape, L shape, and S shape. As a result of this measurement, the flexible which has the highest ventilation efficiency was the one has bigger diameter, short in length, and I shape installation format.

Temperature measurement of the spray flame using micro scale absorption bands and line strength (마이크로 스케일의 흡수선과 흡수강도를 이용한 분무화염의 온도측정)

  • Choi, G.M.
    • Journal of ILASS-Korea
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    • v.7 no.2
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    • pp.1-6
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    • 2002
  • It is necessary to develope a high frequency diode laser sensor system based on the absorption spectroscopy for the measurement of temperature of the spray flame. DFB diode laser operating near $2.0{\mu}m$ was used to scan over selected $H_2O$ transitions near $1.9{\mu}m\;and\;2.2{\mu}m$, respectively. The measurement sensitivity at wide range of sweep frequency was evaluated using multi-pass cell containing $CO_2$ gas. This diode laser absorption sensor with high temporal resolution up to 10kHz was applied to measure the gas temperature in the spray flame region of liquid-gas 2-phase counter flow flame. The successful demonstration of time series temperature measurement in the spray flame gives us motivation of trying to establish non-intrusive temperature measurement method in the practical spray flame.

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Evaluation of Critical Flow Factor in Natural Gas Flow Measurement Using Sonic Nozzle and International Comparison Results (소닉노즐을 이용한 천연가스 유량측정에서 임계유동인자 계산 및 국제비교 결과)

  • Ha, Youngcheol;Her, Jaeyoung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.7
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    • pp.911-917
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    • 1999
  • The sonic nozzle is widely used as reference device for calibrating flowmeters In gas flow measurement and its use requires the Critical Flow Factor(CFF) based on the thermodynamic properties of the gas at the nozzle throat. ISO-9300 provides the calculating method of the factor. But since the CFF from this method show an error over ${\pm}0.5%$ In specific conditions and of ${\pm}0.1{\sim}{\pm}0.2%$ in common Natural Gas(NG) custody transfer condition. this method cannot be applied for gas flow measurement with sonic nozzle. Each research bodies or organizations of the world have joined in order to calculate the CFF more accurately. They have performed these works using their own method and compared the results with each other under the management of ISO. KOGAS have joined those works, because the high-pressure natural gas flow calibration facility of KOGAS will be constructed in late 1999, and then had necessities to calculate a CFF accurately. The calculation method of KOGAS was using the equation of state from AGA-8('94), high accuracy model of ideal gas properties and the solutions of thermodynamic equations. The evaluation results have had a very good consistency within ${\pm}0.05%$ in most NO custody transfer conditions compared to the speed of sound for methane and also shown that the CFF was within ${\pm}0.1%$ compared to the results of other works of the world.