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Page 15 of 912 Results 141 - 150 of 9113

Huancheng Yang, Jiamin Zhao, Hongyan Geng, Xiaocheng Xu, Min Zhang
Study of Calibration System for Liquefied Natural Gas (LNG) Dispenser Verification Device Based on Quality Method

To fulfil calibrating of LNG dispenser verification device, the traceability system of the device was researched in this paper. Using a combination of dynamic and static quality measurement system, with high accuracy electronic balance as main standard, ultra-low temperature commutator with uncertainty of better than 1.5 × 10-4 was developed. The device could realize automation during the whole procedure of data collection under the specified flow, the calibration of LNG dispenser verification device, processing the data and generating the records and certificates.

Xingen Wang, Yuming Shen, Chaojian Tao, Fuwei Wu
Review on Computation Models of High-Pressure Hydrogen Compressibility Factor

Several computation models for calculating the compressibility factor of high-pressure hydrogen are discussed,including linear equation, Virial Equation, Van der Waals Equation and Redlich and Kwong Equation. ConvertingNIST hydrogen density data to compressibility factor data, the compressibility factor data calculated by the models are compared with NIST data. The computation accuracy of Redlich and Kwong’s Equation is less than 1 % in a wide range of temperature and pressure. The hydrogen compressibility factor data from NIST can be fitted into a linear equation with linear error < 0.55 % when p/T ≥ MPa/K

Q. Pan, W. D. Lin, Y. Liu, L. Q. Zhang, J. M. Wang, J. Peng
Traceability of ultrasonic transit time based on relative displacement method

The increasing demand for ultrasonic flow meter (UFM) is due to the absence of moving, protruding parts projecting into the measured flow, transient response, high accuracy and wide range, so that it becomes important in flow measurement. By analyzing the error sources and magnitude of measurements in water, considering the uncertainty caused by sound speed profile and standard length, comprehensively. This research proposes a method to trace the transit time to standard length. Firstly, based on the servo driving and automatic displacement control, a facility which can provide displacement with a minimum displacement step of 10 μm, is designed, and has been precisely calibration by laser interferometer. The error function of water temperature uniformity on transit time measurement is evaluated by theoretical model. A high-precision constant system is developed to control the temperature gradient in water better than 5mK, and the Anton Paar MKT50 platinum wire resistance thermometer is being used as the temperature standard. Assuming that the ultrasonic waveform does not change during propagation in water. The transit time for multiple reflections between fixed stainless steel protective layer and movable reflector is measured. The time difference between two different reflections of same wave can be obtained by high-precision cross-correlation algorithm, and the center frequency of the first five cycles are calculated through Hilbert transform. Through the linear increasing experiments, the effects of reflection times, path length and test temperature to the measurement of transit time are compared.

S. H. Lee, J. Rauch, B.-R. Yoon
Bilateral comparison of viscosity measurement standard system between KRISS and PTB

This study was conducted to compare the viscosity measurement standard systems of the KRISS and PTB, as well as to confirm the international equivalence of the standard viscosity measurement system built in the KRISS. The KRISS constructed a viscosity measurement standard system using an Ubbelohde-type capillary viscometer. In the KRISS, the viscometer was calibrated based on the water viscosity standard ISO TR 3666, and 16 viscometer coefficients were obtained using the step-up method. The measured viscosity was corrected by evaluating the surface tension, buoyancy, and kinetic energy. The uncertainty of the measurement system, including the temperature and measurement time, was evaluated. The measurement range of the viscosity measurement standard system was 0.3 to 100000 mm2/s, with 0.13%-0.5 % uncertainty (U, k = 2). A bilateral comparison of the viscosity measurement standard system between KRISS and PTB was conducted using three different viscosity standard liquids (5A, 2000A, and 50000A) synthesized by the PTB. The viscosity of the standard liquid was measured at three different temperatures (15 °C, 20 °C, and 40 °C), and comparisons were performed under all six experimental conditions (5A/15 °C, 5A/20 °C, 2000A/20 °C, 2000A/40 °C, 50000A/20 °C, and 50000A/40 °C). By considering the uncertainty, the calculated En was less than 1 (0.17-0.72) for all experimental cases. Therefore, it was confirmed that the recently constructed viscosity standard system of the KRISS exhibits mutual equivalence with the viscosity measurement standard system of the PTB. In the future, KRISS will register the viscosity measurement standard system in a CMC based on the results of this bilateral comparison.

D. L. Liu, Q. Cai, J. Wang,H. M. Hu
Influence of Medium Type on Measurement Performance for Vortex flowmeter

The verification medium of vortex flowmeter in the laboratory is often different from the actual measurement. It is very important and necessary to quantitatively analyze the influence of the medium type on its measurement performance. So it is very important and necessary to quantitatively analyze the influence of medium type on its metering performance. The instrument coefficient and indication error of the same vortex flowmeter are verified by water, diesel and air at different flow velocity points, and the measurement performance difference is analyzed which caused by the medium type. The experimental results are that the instrument coefficients by three media are some different under the conventional flow velocity, but not exceed 1/3 of the maximum allowable error, and the indication error is below 1.0 %, which meets the accuracy requirements. The conclusion is that the influence of the medium type on the measurement performance of the vortex flowmeter is small, and the result qualified by air, water or diesel can be used for other media, which can meets the requirements of the accuracy level.

Nuolin Xiang, Suna Guo, Chenguang Song, Longlong Wang
Dynamic characteristics of orifice flowmeter impulse response based on CFD simulation

Because of its simple structure and ability to measure in reverse, orifice flowmeters are widely used in petroleum, chemical and other fields. In the measurement, the pipeline flow state instability occurs, which has a greater impact on the measurement performance of the orifice flowmeter. In order to study the influence of dynamic flow on the dynamic characteristics of orifice flowmeter. Based on CFD simulation, the dynamic characteristics of orifice flowmeter with different throttling ratio (β) under sinusoidal pulsating flow conditions is studied. Through the simulation of the internal flow field of the orifice flowmeter under the conditions of 7 different frequencies and 4 different amplitude combinations, the differential pressure values under different working conditions are extracted to analyze the amplitude-frequency characteristics and phase-frequency characteristics. The results show that the frequency has a great influence on the dynamic characteristics of the orifice flowmeter. At the throttling ratio is 0.2, the flow rate is 6 m³/h and the amplitude is 1.2 m³/h, the orifice flowmeter amplitude-frequency characteristic linearity is as low as 1.9860 %, phase difference is as low as -7.56°.

S. Neuhaus, H. Bissig, B. A. Bircher, M. de Huu
Presentation of the METAS pipe viscometer

Calibration of flow devices is important in several areas of pharmaceutical, flow chemistry and HPLC applications where dosage of process liquids or accurate measurement of the flow rate are important. The process-oriented liquid itself might influence the performance of the flow device. Therefore, the calibration of the flow meter or microfluidic device with the process-oriented liquid is important and the simultaneous determination of the dynamic viscosity under flow conditions is a valuable information for viscosity dependent flow metering methods or other process parameters. To offer the simultaneous calibration of the dynamic viscosity of the process-oriented liquid at the corresponding flowrate, METAS has built a pipe viscometer for the traceable in-line measurement of the dynamic viscosity in the current flow facilities for low flow rates from 1 L/min to 150 mL/min and pressure drops up to 10 bar. To guarantee the tracability, the most challenging part remain the determination of the inner diameter of the micro tube. This can be determined by measuring the pressure drop as a function of flow rate and applying the law of Hagen-Poiseuille with a well known liquid (water) or perform the measurements with the μ-CT at METAS, which determines the inner diameter by x-ray diffraction. The setup of the facility, the uncertainty calculation for the in-line measurement of the dynamic viscosity and the validation measurements are discussed in this paper.

H. Bissig, O. Büker, K. Stolt, E. Graham, L. Wales, A. Furtado, S. Moura, Z.Metaxiotou, S. H. Lee, S. Kartmann, J. Groenesteijn, J. C. Lötters
First comparison of inline measurements of dynamic viscosity

Microfluidic devices are gaining importance in various fields of pharmacy, flow chemistry and healthcare. In the embedded microchannel, the flow rates, the dynamic viscosity of the transported fluids and the fluid dynamic properties play an important role. Various auxiliary functional components of microfluidic devices such as flow restrictors, valves and flow meters need to be characterised with liquids used in several microfluidic applications. However, calibration with water does not always reflect the behaviour of the fluids used in the different applications. Therefore, several National Metrology Institutes (NMI) have developed micro pipe viscometers for traceable in-line measurement of the dynamic viscosity of liquids used in flow applications as part of the EMPIR 18HLT08 MeDDII project. These micro pipe viscometers allow the calibration of any flow device at different flow rates and the calibration of the dynamic viscosity of the liquid or liquid mixture used under actual flow conditions. The traceability of the micro pipe viscometer, the validation of the stated measurement uncertainty with eight liquids as well as dynamic viscosity measurements with in-line sensors are presented in this paper.

Yuan Liu, Wenrui Gao, Lei Wang, Heming Hu
Experimental Investigations of Boundary Layer Thickness Using Ultrasonic Transit Time Method

The widely used investigation method of fluid boundary layer is to record or simulate the current profile distributions near boundary, and then the loss of velocity can be estimate by integration. A directly measuring method of boundary layer displacement thickness by using ultrasonic transit time instrument is proposed. The problem of boundary layer measurement can be simplified to a easier measurement process of current velocity calibration, and the verification experiments are carried out by taking smooth plate as an example. An experimental platform of towing tank facility is established, the towing velocity is taken as the standard value of the outflow speed. The device for flat plate boundary layer measurement is regarded as an ultrasonic current meter. The inner side of the pair of plates equipped with ultrasonic probes can be considered as smooth surface, when the concave at the end of probes, installed by path axial angle, is filled with the material, which acoustic impedance is approximately equal to water. The measured value of ultrasonic current meter is equivalent to the difference between the outflow velocity and the loss caused by boundary layer. The accuracy of measurement result is ensured through high-precision geometric measurement, time delay calibration and sufficient zero-offset correction. In order to improve the time measurement resolution of the current meter, the range of flow velocity is set higher than 100mm/s. By changing the towing velocity and the characteristic position of ultrasonic probe installation, the Reynolds number range is 5e4 to 5e5. By analyzing the principle of ultrasonic current meter and towing tank facility, the uncertainty of displacement thickness measurement results can be properly evaluated. The measurement results of these experiments are close to the integration of flow field record by LDA.

S. Dixon, D. Greenshields, Z. Li, W. Sun, L. D. Smith
Ultrasonic anemometry from very to low to high air flow speeds using a cw or long pulse ultrasonic wave

Ultrasonic anemometers have a wide dynamic range, no moving parts and potentially high accuracies for measuring wind speed, but can also be used for indoor air flow monitoring. Some designs of ultrasonic anemometer already use flexural ultrasonic transducers (FUTs)- a sensor that is used extensively in car parking sensors as they are low cost, robust and reliable. Ultrasonic anemometers often use a method called transit time difference, where the different transit time generally with or against the air flow gives rise to a transit time difference, that can be used to calculate air flow speed. In most conventional ultrasonic anemometers, each transducer in a pair is pulsed in turn, with one generating whilst the other detects, and then the roles are reversed by multiplexing. The ADC captured signals and are processed using cross-correlation (or similar). Arranging pairs of transducers at different angles facilitates 2D and 3D measurements of air flow speed - the most common being 2D anemometers. Both air flow speed and direction (velocity) can be calculated. Challenges with this approach include that ADC and signal processing needed are relatively power-hungry and expensive.

Page 15 of 912 Results 141 - 150 of 9113