Chi Wang, Chunhui Li, Jingan Wang, Tao Li
To achieve the change of trade balance from volumetric determination to energy determination for natural gas in China. The smallest release system of energy determination for natural gas was built. On the base of analyses of energy determination, the uncertainty for this system was conducted taking an example of Beijing experimental station. The results showed that the uncertainty of energy determination could be lower than 1 % ( k = 2), when the measurement process was kept in good control. On the other hand, because the influence of the flowrate and composition on energy determination was...
John D. Wright
Accurate gas properties are needed to take full advantage of the low uncertainties provided by NIST’s Gas Flow Calibration Services. If a flowmeter user and NIST use different values for these properties (molecular mass, compressibility, density, viscosity, and critical flow factor), the user’s flow measurements will have errors. Since January 2009, calibrations conducted by NIST’s Fluid Metrology Group use the NIST-supported database REFPROP version 8.1 to reduce calibration data. Prior to 2009, NIST’s calibration data were reduced using REFPROP 7.0. Flowmeter users who recalibrate their...
William R. Johansen
Constant values for isentropic exponent and absolute viscosity are commonly used for the calculation of gas flow rates through differential producing flowmeters. Errors in flow measurement due to the use of constants for thermodynamic and transport properties are bias errors. Bias errors in natural gas orifice flow measurement due to incorrect isentropic exponent values can exceed 0.15 %. When the adiabatic expansion factor is used to calculate natural gas flow rates the bias errors due to the use of a constant isentropic exponent can exceed 2 %. Bias errors in natural gas flow measurement...
J. Barbe, F. Dijoux, C. Yardin, T. Macé
More and more chemical analysis laboratories using gas chromatographs need to measure the different flowrates involved during the analysis process (split ratio, column flow). The measurement of the column flow is certainly the most difficult because the flowrate of carrier gas is generally very small. For example, the flowrate of helium which is the most often used carrier gas is typically less than 15 µg/s (5 cm³/min). To calibrate helium flowmeters, the "traced gas method" developed at LNE for nitrogen has been optimized for helium microflow measurements in the range of 0.75 µg/s to 30...
Mou Changhua, Wang Maolin, Peng Lihui
At present gas flow measurement and control are the key parts in the fuel cell and solar energy equipment. The percent of mixture gas would be calculated theoretically to achieve the high efficiency. Thus a new gas flow measurement and controller are presented for energy industry in this paper. Based on the thermal sensor and low pressure drop solenoid valve, the new gas flow measurement controller is integrated by temperature compensation. Experiment and customer testing results demonstrate the better performance of the new gas flow measurement and controller.
Yahong Yao, ChihChang Chen, Xiaozhong Wu, Liji Huang
Thermal time-of-flight (TOF) technology has been considered to be one of the most effective approaches that could provide an accurate flow measurement at ultra low flow speed. While the technology remains on paper for over half a century without real implementation, the lack of market drive may be one of the major reasons. Current demands in energy management such as city natural gas metering, medical applications for respiratory machines and others have revitalized this technology. Thermal TOF technology in principle can provide accurate flow speed measurements for gases regardless of its...
Liji Huang, ChihChang Chen, Yahong Yao, Gaofeng Wang, Yong Feng, Kaiping Wei, Wenhong Deng, Changming Jiang, Jiliang Ruan, Sugang Jiang
City gas metering has been dominated by diaphragm meters for over a century. In the past 30 years, development of all-electronic meters for better energy management has been pursued by many companies using ultrasonic, thermal time-of- flight, and MEMS calorimetric principles. Installations and trials have been reported but mostly in small quantity. The challenges for such meters come from reliability and cost requirements. While ultrasonic technology has been better developed, the cost and gas composition dependency are often the barrier for the market acceptance. In this paper, we discuss...
Wenhong Deng, Sugang Jiang, Rui Liu, Liji Huang, Pujun Zhao, Li Lei, Kaiyou Jin
Thermal mass flow meters are commonly of full scale accuracy and not considered for applications where custody transfer is required. Recent advancement of MEMS mass flow technology in city natural gas metering has demanded a better calibration and verification procedure so that the custody transfer can be justified with regard to the traditional thermal mass flow meter technology. The thermal mass flow sensor could be impacted by the humidity, gas composition and temperature. Calibrations with one standard may often be not applicable to the others if each of the factors is not fully...
J.-P. Vallet, P. Kervevan, A. Ouerdani, E. Mann, M. Schladerer, J. Guerin
Since January 2006, the MESURA company, located in FORBACH France, manufacturer of gas regulators for the distribution networks up to 4 bar, has been developing a design which integrates two functions on the same body, thus optimizing the volume (16 cm or 6.3 inch cubic volume), the pressure regulation and flow metering, and in addition, providing wireless data transmission and remote safety control. The evaluation and the qualification of the complete system and the process (including uncertainties) has been undertaken by the French laboratory LNE-LADG in order to confirm the metering of...
Jim Storer, Richard Steven
A simple, accurate, relatively compact and light gas mass flow meter has been developed with diagnostic capabilities. This fundamental mass flow meter concept revises a simple concept originally suggested four decades ago before the computer power existed to make a practical system. This paper revises the concept, discusses the development of a modern meter design and adds new diagnostic capabilities. The mass meters outputs are the volume flow rate, the fluid density and the mass flow rate. The system does not require the fluid density from an external source and can meter gas mass flows...