### Thermal Boundary Layers in Critical Flow Venturis

July 30, 2021

Author(s)

, , , Woong Kang, Liang Zhang, Bodo Mickan

We improve the usefulness of small (diameter

Displaying 1 - 25 of 156

July 30, 2021

Author(s)

, , , Woong Kang, Liang Zhang, Bodo Mickan

We improve the usefulness of small (diameter

June 15, 2021

Author(s)

, , , Vern E. Bean, , , Christopher J. Crowley, , ,

We describe the 15 kg/s water flow calibration standard operated by the Fluid Metrology Group of the National Institute of Standards and Technology (NIST) to calibrate liquid flow meters for customers. The 15 kg/s standard is a dynamic, gravimetric, liquid

June 6, 2020

Author(s)

Giovanni Garberoglio,

,
Erratum to paper published in 2011

February 25, 2020

Author(s)

, , , , , , Thomaa D. Martz, Matthew Gentry

Exhaust flows from coal-fired electricity-generating-plants are determined by measuring the flue gas velocity at prescribed points in the stack cross section. These velocity measurements are made using EPA-approved differential pressure probes such as the

July 16, 2019

Author(s)

, , , Eric Harman, James Mehl

We describe our progress in the development of a novel gas flow standard using the acoustic and microwave resonances of a 1.85 m3, nearly-spherical, steel vessel at pressures up to 7 MPa. For flow calibrations using pressure and acoustic frequency

June 28, 2019

Author(s)

, , , , ,

Exhaust flows from coal-fired stacks are determined by measuring the flue gas velocity at prescribed points in the stack cross section. During the last 30+ years these velocity measurements have been made predominantly using S-type pitot probes. These

April 18, 2019

Author(s)

Patrick Rourke, Christof Gaiser, Roberto M. Gavioso,

, Laurent Pitre, Robin Underwood
The principles and techniques of primary refractive-index gas thermometry (RIGT) are reviewed. Absolute primary RIGT using microwave measurements of helium-filled quasi-spherical resonators has been implemented at the temperatures of the triple points of

September 21, 2018

Author(s)

, , , , , , , Scott Swiggard, Chris Gunning, David Elam, Tom Martz, Eric Harman, David Nuckols, Liang Zhang, Woong Kang, Salvator Vigil

The complex flow conditions inherent in power plant smokestacks make accurate flow measurements challenging, which in turn limits the accuracy of hazardous emissions measurements. While stack composition measurements are assessed daily via comparison to a

May 17, 2018

Author(s)

, , , ,

We report progress towards the goal of reducing the errors in industrial smokestack flow measurements to 1 % by replacing S-probes with calibrated 3-D probes (i.e., probes that measure 3 components of velocity). NIST calibrated a commercially-manufactured

May 17, 2018

Author(s)

, , , ,

The amounts of CO2 and other pollutants emitted by a coal-fired power plant are measured using a continuous emissions monitoring system (CEMS) permanently installed in the exhaust smokestack. The pollutant flux is the product of the pollutants

March 28, 2018

Author(s)

, , , , Eric Harman

We characterized a 1.8 m3, nearly-spherical, steel shell at pressures up to 7 MPa for use as a gas flow standard. For pressure, volume, temperature, and time measurements, the shells cavity will collect gas; for blow-down measurements, the shell will be a

March 21, 2018

Author(s)

, , ,

The rate of rise (RoR) method measures the time rate of change of the mass of gas in a collection volume as it is filled via a flow meter under test. The mass of gas is calculated from time-stamped pressure and temperature data gathered from the known

February 5, 2018

Author(s)

, Joachim Fischer, Bernd Fellmuth, Christof Gaiser, Laurent Pitre, Fernando Sparasci, Lara Risegari, Roberto M. Gavioso, D M. Rippa, Bengt Hallstedt, Jifeng Qu, XiaoJuan Feng, Jianqiang Zhang, David R. White, L Gianfrani, A Castrillo, L Moretti, B Darquie, C Daussy, S Briaudeau, O Kozlova, J J. Segovia, M C. Martin, D del Campo,

The International Committee for Weights and Measures (CIPM), at its meeting in October 2017 followed the recommendation of the Consultative Committee for Units (CCU) on the redefinition of the kilogram, ampere, kelvin and mole. For the redefinition of the

September 11, 2017

Author(s)

, XiaoJuan Feng, Jintao Zhang, H. Lin, James B. Mehl, , K Zhang, Y.N. Duan

We report a new determination of the Boltzmann constant kB using a cylindrical acoustic gas thermometer. We determined the length of the copper cavity from measurements of its microwave resonance frequencies. This contrasts with our previous work (Zhang et

September 11, 2017

Author(s)

Laurent Pitre, Fernando Sparasci,

, Cecile Guianvarch, Catherine Martin, Martin Himbert, Mark Plimmer, James B. Mehl, Giuliano Albo, Bo Gao, Lara Risegari
The SI unit of temperature will soon be redefined in terms of a fixed value of the Boltzmann constant k derived from an ensemble of measurements worldwide. We report on a new determination of k using acoustic thermometry of helium-4 gas in a 3-litre quasi

May 18, 2017

Author(s)

XiaoJuan Feng, Jintao Zhang,

, Inseok Yang, Mark Plimmer, H. Lin
This article describes the accurate determination of the molar mass of a sample of argon gas used for a determination of the Boltzmann constant. The method due to one of the authors [Moldover et al., J. Res. Natl. Bur. Stand. 93, 85-144 (1988)] uses the

November 2, 2016

Author(s)

Felix Sharipov,

We review values of the temperature jump coefficient zeta_T determined from measurements of the acoustic resonance frequencies f_acoust of helium-filled and argon-filled, metal-walled, quasi- spherical cavities near ambient temperature. We combine these

September 15, 2016

Author(s)

, , , , , , ,

Accurate flow measurements are essential to quantify the amount of greenhouse gases (GHGs) and other pollutants emitted from power plant stacks. Although protocols have been developed, the uncertainty of stack flow measurements has not been documented.

May 6, 2016

Author(s)

, , James B. Mehl

We demonstrate that a leak from a large, unthermostatted pressure vessel into ambient air can be detected an order of magnitude more effectively by measuring the time dependence of the ratio p/f2 than by measuring the ratio p/T. Here f is the resonance

February 22, 2016

Author(s)

K. Zhang, X.J. Feng,

, , Jintao Zhang, Hong Lin, Jifeng Qu
Relative primary acoustic gas thermometry determines the ratios of thermodynamic temperatures from measured ratios of acoustic and microwave resonance frequencies in a gas-filled metal cavity on isotherms of interest. When measured in a cavity with known

January 1, 2016

Author(s)

, ,

The last 25 years have seen tremendous progress in thermometry in the moderate temperature range (1 K to 1235 K). Various primary thermometers based on different physics have uncovered errors in the International Temperature Scale of 1990 and set the

September 30, 2015

Author(s)

Inseok Yang, Laurent Pitre,

, Jintao Zhang, XiaoJuan Feng, Jin Seog Kim
We determined accurate values of ratios among the average molar masses MAr of 9 argon samples using two completely-independent techniques: (1) mass spectroscopy and (2) measured ratios of acoustic resonance frequencies. The two techniques yielded mutually

September 9, 2015

Author(s)

, Roberto M. Gavioso,

We review correlated uncertainties among the accurate determinations of the Boltzmann constant kB that used the techniques of primary acoustic gas thermometry (AGT). We consider uncertainty contributions from four sources: (1) resonator-dependent

August 19, 2015

Author(s)

XiaoJuan Feng, Hong Lin,

, , Jintao Zhang
We report progress in determining the Boltzmann constant kB using a virtual acoustic resonator derived by combining the measured frequencies of the longitudinal acoustic modes of two argon-filled, cylindrical, cavity resonators in such a way as to minimize

June 27, 2015

Author(s)

Graham Machin, Joachim Fischer,

, John Saunders, J. P. Martin Trusler, Rod White
none