Reducing measurement uncertainties of high-pressure gas flow calibrations by using reference values based on multiple independent traceability chains

2018 ◽  
Vol 85 (12) ◽  
pp. 754-763
Author(s):  
Jos van der Grinten ◽  
Henri Foulon ◽  
Arnthor Gunnarsson ◽  
Bodo Mickan
Keyword(s):  
High Pressure ◽  
Gas Flow ◽  
Weighted Average ◽  
Reference Value ◽  
Polynomial Equation ◽  
Calibration Data ◽  
Traceability Chain ◽  
Uncertainty Sources ◽  
Flow Reynolds Number ◽  
Measurement Uncertainties

Abstract This paper describes the recently updated realization of the harmonized cubic metre for natural gas. It is a procedure based on an intercomparison, that combines the mutually independent traceability chains of four primary laboratories in the field of high-pressure gas flow measurement. The reference value, also called harmonized cubic metre, is the weighted average of at least two laboratories with weighing factors that are inversely proportional to the squared uncertainties of the calibration results. This results in lower uncertainties for the laboratories as long as the stochastic contributions (Type A) to the overall measurement uncertainties are significantly smaller than the uncertainties arising from the traceability chain (Type B). This condition is fulfilled in practice as traceability uncertainties are at least a factor ten greater than the other uncertainty sources. When evaluating the data of intercomparisons, curve fitting is used for the representation of the calibration data. A polynomial equation of maximum four degrees, expressed in the logarithm of the flow Reynolds number, proves to be the optimum choice for fitting the calibration curve of the turbine gasmeters.

The International BIPM/CIPM Key Comparison Reference Value for Natural Gas Flow at High Pressure and Its Metrological Meaning for Natural Gas Trading

2005 ◽  
Author(s):  
D. Dopheide ◽  
B. Mickan ◽  
R. Kramer ◽  
M. P. van der Beek ◽  
G. J. Blom ◽  
...  
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
The Netherlands ◽  
Gas Flow ◽  
Reference Value ◽  
Key Comparisons ◽  
Flow Area ◽  
National Metrology Institutes ◽  
Harmonization Process ◽  
Natural Gas Flow

The paper describes the background of the European Harmonized Reference Value for the cubic meter of Natural Gas at high pressure, which is in use in Germany, The Netherlands and France since May 4th, 2004. The harmonization process began on November 1st, 1999 between Germany and The Netherlands and has been finalized on May 4, 2004 due to the incorporation of the French LNE to the Harmonized Reference Value. The outcome was named: “Harmonized European Natural Gas Cubic Meter” as realized by three independent National Metrology Institutes. The prerequisites of the harmonization process, underlying procedures, results obtained so far and the mutual benefits will be pointed out as well as the economic consequences for the European market as well as for the international user. The paper shows the degree of equivalence between the three participating NMIs PTB, LNE and NMi-VSL. Under auspices of the BIPM (International Bureau for Weight and Measurers) as well as the CIPM (International Conference for Weight and Measures), which is the highest metrological authority worldwide, so called Key Comparisons (KC) have been conducted to get international reference values for all quantities of interest. Among these KCs, the flow area is of economic importance and Key Comparisons for natural gas flow at high pressure and larger flow rates have been conducted successfully. The outcome of such a KC is the international Key Comparisons Reference Value (KCRV), which is then considered to be the worldwide best available realization of Natural Gas Flow at high pressure. These KCs have been conducted among the National Primary Standards of all nations worldwide, represented by their National Metrology Institutes (NMIs) and have been finalized in December 2004 and the KCRV has been approved by the BIPM in April 2005. It turns out at last that the international recommended reference value is exactly the same as the above mentioned European Harmonized Reference Value.

INVESTIGATION OF THE TIME OF GAS FLOW THROUGH A HOLE IN LONG PIPELINES UNDER HIGH PRESSURE

2020 ◽  
Vol 58 (1) ◽  
pp. 30-43
Author(s):  
N.D. Yakimov ◽  
◽  
A.I. Khafizova ◽  
N.D. Chichirova ◽  
O.S. Dmitrieva ◽  
...  
Keyword(s):  
High Pressure ◽  
Gas Flow ◽  
Flow Through

Evaluation of Measurement Uncertainties for Pneumatic Multi-Hole Probes Using a Monte Carlo Method

2016 ◽  
Author(s):  
Magnus Hölle ◽  
Christian Bartsch ◽  
Peter Jeschke
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Compressible Flows ◽  
Uncertainty Evaluation ◽  
Calibration Data ◽  
Input Quantity ◽  
Parameter Evaluation ◽  
Polynomial Curve ◽  
Different Types ◽  
Measurement Uncertainties

The subject of this paper is a statistical method for the accurate evaluation of the uncertainties for pneumatic multi-hole probe measurements. The method can be applied to different types of evaluation algorithms and is suitable for steady flowfield measurements in compressible flows. The evaluation of uncertainties is performed by a Monte Carlo method (MCM), which is based on the statistical law of large numbers. Each input quantity, including calibration and measurement quantities, is randomly varied on the basis of its corresponding probability density function (PDF) and propagated through the deterministic parameter evaluation algorithm. Other than linear Taylor series based uncertainty evaluation methods, MCM features several advantages. On the one hand, MCM does not suffer from lower-order expansion errors and can therefore reproduce nonlinearity effects. On the other hand, different types of PDFs can be assumed for the input quantities and the corresponding coverage intervals can be calculated for any coverage probability. To demonstrate the uncertainty evaluation, a calibration and subsequent measurements in the wake of an airfoil with a 5-hole probe are performed. MCM is applied to different parameter evaluation algorithms. It is found that the MCM approach presented cannot be applied to polynomial curve fits, if the differences between the calibration data and the polynomial curve fits are of the same order of magnitude compared to the calibration uncertainty. Since this method has not yet been used for the evaluation of measurement uncertainties for pneumatic multi-hole probes, the aim of the paper is to present a highly accurate and easy-to-implement uncertainty evaluation method.

scholarly journals The importance of hydrological uncertainty assessment methods in climate change impact studies

2014 ◽  
Vol 18 (8) ◽  
pp. 3301-3317 ◽  
Author(s):  
M. Honti ◽  
A. Scheidegger ◽  
C. Stamm
Keyword(s):  
Climate Change ◽  
Climate Change Impact ◽  
Hydrological Model ◽  
Uncertainty Assessment ◽  
Assessment Method ◽  
Calibration Data ◽  
Relative Importance ◽  
Impact Studies ◽  
Uncertainty Sources ◽  
Change Impact

Abstract. Climate change impact assessments have become more and more popular in hydrology since the middle 1980s with a recent boost after the publication of the IPCC AR4 report. From hundreds of impact studies a quasi-standard methodology has emerged, to a large extent shaped by the growing public demand for predicting how water resources management or flood protection should change in the coming decades. The "standard" workflow relies on a model cascade from global circulation model (GCM) predictions for selected IPCC scenarios to future catchment hydrology. Uncertainty is present at each level and propagates through the model cascade. There is an emerging consensus between many studies on the relative importance of the different uncertainty sources. The prevailing perception is that GCM uncertainty dominates hydrological impact studies. Our hypothesis was that the relative importance of climatic and hydrologic uncertainty is (among other factors) heavily influenced by the uncertainty assessment method. To test this we carried out a climate change impact assessment and estimated the relative importance of the uncertainty sources. The study was performed on two small catchments in the Swiss Plateau with a lumped conceptual rainfall runoff model. In the climatic part we applied the standard ensemble approach to quantify uncertainty but in hydrology we used formal Bayesian uncertainty assessment with two different likelihood functions. One was a time series error model that was able to deal with the complicated statistical properties of hydrological model residuals. The second was an approximate likelihood function for the flow quantiles. The results showed that the expected climatic impact on flow quantiles was small compared to prediction uncertainty. The choice of uncertainty assessment method actually determined what sources of uncertainty could be identified at all. This demonstrated that one could arrive at rather different conclusions about the causes behind predictive uncertainty for the same hydrological model and calibration data when considering different objective functions for calibration.

Field Calibration of Orifice Meters for Natural Gas Flow

1989 ◽  
Vol 111 (1) ◽  
pp. 22-33
Author(s):  
V. C. Ting ◽  
J. J. S. Shen
Keyword(s):  
Natural Gas ◽  
Gas Flow ◽  
Reynolds Numbers ◽  
National Standard ◽  
Test Facility ◽  
Critical Flow ◽  
Calibration Data ◽  
Discharge Coefficients ◽  
Sand Hills ◽  
Natural Gas Flow

This paper presents the orifice calibration results for nominal 15.24, 10.16, and 5.08-cm (6, 4, 2-in.) orifice meters conducted at the Chevron’s Sand Hills natural gas flow measurement facility in Crane, Texas. Over 200 test runs were collected in a field environment to study the accuracy of the orifice meters. Data were obtained at beta ratios ranging from 0.12 to 0.74 at the nominal conditions of 4576 kPa and 27°C (650 psig and 80°F) with a 0.57 specific gravity processed, pipeline quality natural gas. A bank of critical flow nozzles was used as the flow rate proving device to calibrate the orifice meters. Orifice discharge coefficients were computed with ANSI/API 2530-1985 (AGA3) and ISO 5167/ASME MFC-3M-1984 equations for every set of data points. The uncertainty of the calibration system was analyzed according to The American National Standard (ANSI/ASME MFC-2M-A1983). The 10.16 and 5.08-cm (4 and 2-in.) orifice discharge coefficients agreed with the ANSI and ISO standards within the estimated uncertainty level. However, the 15.24-cm (6-in.) meter deviated up to − 2 percent at a beta ratio of 0.74. With the orifice bore Reynolds numbers ranging from 1 to 9 million, the Sand Hills calibration data bridge the gap between the Ohio State water data at low Reynolds numbers and Chevron’s high Reynolds number test data taken at a larger test facility in Venice, Louisiana. The test results also successfully demonstrated that orifice meters can be accurately proved with critical flow nozzles under realistic field conditions.

scholarly journals Intercomparison of Indoor Radon Measurements Under Field Conditions In the Framework of MetroRADON European Project

2020 ◽  
Vol 17 (5) ◽  
pp. 1780 ◽  
Author(s):  
Daniel Rabago ◽  
Ismael Fuente ◽  
Santiago Celaya ◽  
Alicia Fernandez ◽  
Enrique Fernandez ◽  
...  
Keyword(s):  
Indoor Radon ◽  
Measurement Techniques ◽  
Weighted Average ◽  
Reference Value ◽  
Field Conditions ◽  
Air Exposure ◽  
Basic Part ◽  
Percentage Difference ◽  
Gas Measurements ◽  
Physical Reasons

Interlaboratory comparisons are a basic part of the regular quality controls of laboratories to warranty the adequate performance of test and measurements. The exercise presented in this article is the comparison of indoor radon gas measurements under field conditions performed with passive detectors and active monitors carried out in the Laboratory of Natural Radiation (LNR). The aim is to provide a direct comparison between different methodologies and to identify physical reasons for possible inconsistencies, particularly related to sampling and measurement techniques. The variation of radon concentration during the comparison showed a big range of values, with levels from approximately 0.5 to 30 kBq/m3. The reference values for the two exposure periods have been derived from a weighted average of participants’ results applying an iterative algorithm. The indexes used to analyze the participants’ results were the relative percentage difference D(%), the Zeta score ( ζ ), and the z-score ( z ). Over 80% of the results for radon in air exposure are within the interval defined by the reference value and 20% and 10% for the first and the second exposure, respectively. Most deviations were detected with the overestimating of the exposure using passive detectors due to the related degassing time of detector holder materials.

scholarly journals Transient Flow Characteristic of High-Pressure Hydrogen Gas in Check Valve during the Opening Process

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4222
Author(s):  
Jianjun Ye ◽  
Zhenhua Zhao ◽  
Jinyang Zheng ◽  
Shehab Salem ◽  
Jiangcun Yu ◽  
...  
Keyword(s):  
High Pressure ◽  
Gas Flow ◽  
Transient Flow ◽  
Check Valve ◽  
Hydrogen Gas ◽  
Strong Impact ◽  
Hydrogen Flow ◽  
Hydrogen Systems ◽  
Pressure Hydrogen ◽  
Opening Process

In high-pressure hydrogen systems, the check valve is one of the most easy-to-damage components. Generally, the high-pressure hydrogen flow can generate a strong impact on the check valve, which can cause damage and failure. Therefore, it is useful to study the transient flow characteristics of the high-pressure hydrogen flow in check valves. Using dynamic mesh generation and the National Institute of Standards and Technology (NIST) real hydrogen gas model, a transient-flow model of the high-pressure hydrogen for the check valve is established. First, the flow properties of high-pressure hydrogen during the opening process is investigated, and velocity changes and pressure distribution of hydrogen gas flow are studied. In addition, the fluid force, acceleration, and velocity of the valve spool are analyzed quantitatively. Subsequently, the effect of the hydrogen inlet-pressure on the movement characteristic of the valve spool is investigated. The results of this study can improve both the design and applications of check valves in high-pressure hydrogen systems.

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