2023 Vol. 67, No. 7

Measurement Methods and Techniques
Metrology of Carbon Emissions from Fossil Fuel Combustion Using Fuel Analysis Methods
WANG Haifeng, SONG Xiaoping, LI Jia
2023, 67(7): 3-10. doi: 10.12338/j.issn.2096-9015.2023.0189
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Accurate quantification of greenhouse gas (GHG) emissions is fundamental to achieving greenhouse gas reduction targets. The combustion of fossil fuels, including coal, fuel oil, and natural gas, is a predominant source of GHG emissions. This study focuses on the determination of carbon dioxide (CO2) emissions from stationary combustion sources using fuel analysis methods. Two distinct methods are presented: Method 1 utilizes the fuel’s calorific value and emission factor to ascertain the CO2 emissions, while Method 2 employs the fuel’s carbon content and oxidation rate for this determination. This paper elaborates on the procedural steps, analytical methodologies, instrumentation, calibration techniques, and uncertainty assessments applied in both methods. Comprehensive metrological techniques encompassing primary calorimeters, certified reference materials for calorific values, elemental contents, and natural gas components, as well as verification regulations and calibration protocols, are employed to ensure the accuracy, reliability, and consistency of the CO2 emission determinations.
Measurement Technique for Pulsatile Microflow Based on Poiseuille’s Law
SONG Shugu, REN Xiaoqing, LIU Weiguang, GUO Shenhui, XIE Chen, ZHANG Zewu
2023, 67(7): 11-17. doi: 10.12338/j.issn.2096-9015.2023.0171
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To address the challenge of measuring pulsatile microflow under high-pressure conditions in the realm of physical and chemical analysis instrumentation, a methodology grounded on the Hagen-Poiseuille law has been devised. This methodology leverages the differential pressure signal for indirect measurement, capitalizing on the traits of high pressure endurance and swift response manifested by the differential pressure transducer. A scheme for measuring differential pressure values within the pulsatile flow pathway has been designed. Employing numerical integration alongside dual time correction, the accumulated mass derived from differential pressure signals was juxtaposed against the static accumulated mass from a balance to validate the measurement accuracy. This effectively ameliorates the erstwhile issue of low accuracy found in balance weighing and stopwatch timing methods. The differential method’s instantaneous flow rate was corroborated through dynamic sampling functions of a balance. Data outcomes denote that within the pulsatile characteristic range of 0.2 to 0.5 mL/min, the error in measuring average flow rate via the differential method does not exceed ±0.5%, and the error in measuring instantaneous flow rate does not surpass ±1.5%. This accords with the flow measurement accuracy requisites of relevant instruments, and concurrently mitigates the issues of exorbitant pricing of microflow sensors and limited pressure resistance during usage.
Research on Calibration Methods for Scanning Switches in Automatic Temperature Measurement Systems
HAN Zhixin, HE Chuan, ZHAO Jing, WEN Jie
2023, 67(7): 18-24, 10. doi: 10.12338/j.issn.2096-9015.2023.0146
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In automatic temperature measurement systems, the mismatch between the computer-controlled scanning switch channel switching time and the sampling time of electrical measuring instruments can lead to data acquisition distortion. Building upon existing calibration techniques addressing parasitic potential and channel-to-channel data acquisition disparities, a novel calibration method focusing on dynamic acquisition differences among scanning switch channels is proposed. By scrutinizing metrological attributes delineated in current national standards, a calibration measurement standard for scanning switches was established and validated through feasibility trials. Within the trials, the calibration methodology was verified using conversion switches in both thermocouple and thermal resistance automatic measurement systems. Based on the experimental outcomes, refinements were made to the calibration method, followed by validation testing. The findings underscore that the calibration method, predicated on dynamic acquisition discrepancies among scanning switch channels, effectively tackles the measurement issues of dynamic channel differences, aligning with the requisite stipulations of existing national standards. This method holds significant practical value for data acquisition in automatic temperature measurement systems, ensuring precise and reliable temperature measurement data.
Key Technologies and Applications for the Green and Low-Carbon Advancement of Microgrids
2023, 67(7): 25-33. doi: 10.12338/j.issn.2096-9015.2023.0165
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The green and low-carbon development of microgrids is centered around renewable energy, and through the application of key technologies such as energy storage, intelligent energy management, and energy efficiency optimization, the green, low-carbon, and sustainable development of microgrids is achieved. This article summarizes the key technologies for the green and low-carbon development of microgrids, including renewable energy utilization, energy storage technology, intelligent energy management systems, energy efficiency optimization technology, microgrid coordination and control, energy internet, and data analysis. The comprehensive application of these technologies will promote the development of microgrids towards green and low-carbon directions, achieve the goals of sustainable energy supply and reducing carbon emissions, and promote environmental protection and sustainable economic development.
Measuring Instruments and Systems
An Instrument for Micro-Newton Force Measurement with Uncertainty in E-5
ZHANG Kai, BAI Yang, ZHANG Zhimin
2023, 67(7): 34-39, 33. doi: 10.12338/j.issn.2096-9015.2023.0194
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Micro-newton force measurement technology, extensively employed in the domains of space exploration, bio-materials analysis, and micro-nano manufacturing, plays a pivotal role. This study presents a device constructed based on the principle of electrostatic force balance, aimed at measuring micro-newton force values. Addressing the issues encountered in preliminary research, such as excessive stiffness in the vertical direction and significant alignment error of cylindrical capacitors, structural optimization of quadrilateral flexible pivots was undertaken to diminish system stiffness vertically, thereby enhancing the force resolution of the electrostatic force balance. Additionally, calibration of the concentricity of the inner and outer electrodes was achieved based on the capacitance characteristics of cylindrical capacitors. Experimental assessments revealed that the devised micro-newton force measurement device adeptly confines the measurement uncertainty of 100 μN force values to the E-5 level. The outcomes of this research are poised to significantly contribute to the establishment of micro-newton force measurement standard devices and further research on micro-newton force measurement methodologies.
Investigation on Miniaturized Optical System for Rapid Steering Fountain Clock
DU Chao, SONG Wenxia, CHEN Weiliang, LIU Kun, ZHENG Fasong, DAI Shaoyang, ZUO Yani, FANG Fang
2023, 67(7): 40-44. doi: 10.12338/j.issn.2096-9015.2023.0190
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The Rapid Steering Fountain Clock is a frequency reference device pivotal for steering hydrogen maser time-keeping. To fulfill time-keeping demands, enhancing the operational reliability and stability of the rapid-steering fountain clock is crucial. The optical system, being the most vulnerable component, is susceptible to environmental factors like temperature, causing fluctuations in atomic cloud temperature and atomic number, thereby deteriorating frequency stability. This study proposes a miniaturized optical system for the rapid-steering fountain clock, achieved by lowering light height, minimizing light path, reducing elastic adjustment frames, and optimizing optical path layout. Utilizing new designs such as waveplate polarizing beamsplitter combination, vertically positioned acousto-optic modulator, and double-pass through cat-eye acousto-optic modulator, all optical devices are integrated onto a 400mm×600mm optical bench with a standard 25 mm hole spacing. The entire optical system, wrapped in foam, underwent temperature fluctuation testing, revealing that with a 12 ℃ temperature change, the optical power fluctuation post-optical fiber in the longest optical path is below 6.6%, significantly improving the compactness and stability of the fountain clock optical system. When applied to the rapid-steering rubidium fountain clock, a daily atomic number fluctuation of 5.28% and a fountain clock frequency daily stability of 5.57E-16 were achieved.
Study on Key Parameters of Flow Element for Particle Samplers
LIU Weiguang, GUO Shenhui, JING Jun, GE Rui, WANG Congxian, REN Xiaoqing
2023, 67(7): 45-52. doi: 10.12338/j.issn.2096-9015.2023.0175
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This study focuses on addressing the shortcomings of commonly utilized flow orifice elements in particle samplers by developing an orifice flow element capable of measuring flow rates ranging from 1 to 120 L/min. Within this flow range, the Reynolds number at the inlet of the flow element does not exceed 2000, ensuring primarily laminar flow conditions. This exceeds the operational range of differential pressure flow elements as per existing standards. To ensure optimal flow performance of the new orifice plates, it is imperative to define the maximum allowable mechanical machining deviations for key parameters such as orifice plate thickness (E), throttling orifice thickness (e), and pressure tap locations. Computational fluid dynamics simulations were employed to determine these maximum allowable deviations in the geometric dimensions. For orifice plates operating in the 1 to 10 L/min range, the suggested E value is 1.6 mm, with a maximum allowable deviation of ±6.25%, and for e, a value of 1.16 mm is recommended with a deviation of ±2.5%. For the 10 to 100 L/min range, an E value of 3.2 mm is recommended with a deviation of ±6.25%, and an e value of 2.00 mm with a deviation of ±5%. The D-D/2 method was used for pressure tapping, with upstream accuracy being ±0.1D and downstream accuracy ±0.05D. Based on these key dimensions, the designed orifice plates exhibited an outflow coefficient linearity and machining consistency better than 1.5%.
Investigation of Components for Flow Calibration in Particulate Matter Samplers
GUO Shenhui, LIU Weiguang, GAO Jinsheng, ZHANG Xiaoni, LI Qin, ZHANG Zewu
2023, 67(7): 53-61. doi: 10.12338/j.issn.2096-9015.2023.0172
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Particulate matter samplers serve as essential instruments for air monitoring, facilitating the sampling and assessment of air quality. Conventionally, orifice flowmeters utilized for flow calibration in these samplers have demonstrated inadequate linearity and long-term stability, exhibiting significant uncertainty in flow measurement within the prevalent range of 1-120 L/min. This research aims to unveil alternative components capable of enhancing the flow calibration of particulate matter samplers. An in-depth analysis was conducted, scrutinizing the merits and shortcomings of various flowmeters in relevance to their applicability in sampler flow calibration. Priority was given to the design of orifice plates and nozzle components that assure precise manufacturing and cost-efficiency. Employing Computational Fluid Dynamics (CFD), simulations were executed to evaluate the performance of these components across distinct flow ranges. Components manifesting superior linearity within the 1-120 L/min range were selected for further processing. Compliance with national standards for differential pressure flowmeters and adherence to simulation-derived structural parameters were ensured during the manufacturing of these components, followed by rigorous experimental validation. The study culminates in the design of orifice flowmeters optimized for flow ranges of 0.5-5 L/min, 5-10 L/min, and 10-120 L/min, proving instrumental for the flow calibration of particulate matter samplers. Within these ranges, the orifice flowmeters exhibit commendable mechanical processing consistency, an outflow coefficient linearity surpassing 1.0%, and long-term flow stability within a 1.5% margin. These findings are instrumental, providing pivotal theoretical insights for the future design of gas sampler flow calibration components and broadening the array of choices available for sampler flow calibration components.
Impact Studies in Metrology
Interference Study of Multiple Gases on Electrochemical Sensors in Flue
LIU Peiyuan, LI Jian, XIA Chun, HE Yuanyuan, WANG Shengjia
2023, 67(7): 62-67, 52. doi: 10.12338/j.issn.2096-9015.2023.0221
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This study investigates the interference effects of multiple gases, including CO, SO2, NO, NO2, and CH4, on electrochemical sensors in flue gas analyzers under coexisting conditions. Zero-interference and cross-interference experiments were conducted. Results demonstrated that CO positively interfered with the SO2 sensor, while NO and NO2 negatively interfered with the SO2 sensor, with NO2 causing the most significant interference. An increase of 100mg/m3 in NO2 resulted in a 0.173% reduction in the SO2 sensor reading. NO exhibited significant positive interference with the CO sensor, causing a 0.116% increase in sensor reading per 100mg/m3 increase in NO. Conversely, CH4 negatively interfered with the CO sensor, with each 100mg/m3 increase in CH4 leading to a 0.005% decrease in the CO sensor reading.
Reference Material Development
Development of a Certified Reference Material of Three-Component Mixed Solution for GC-MS Calibration
LI Zhifeng, WANG Xiaobing, GUO Shuo, SONG Zengliang
2023, 67(7): 68-73, 44. doi: 10.12338/j.issn.2096-9015.2023.0197
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To address the traceability issue in gas chromatography-mass spectrometry (GC-MS), standard substances are necessitated. A three-component mixed solution, comprising octafluoronaphthalene, benzophenone, and methyl stearate dissolved in isooctane, was meticulously prepared using the gravimetric method for the purpose of gas quality calibration. Analysis was carried out utilizing a gas chromatography equipped with a hydrogen flame ionization detector (GC-FID). Rigorous evaluation was conducted by employing F-tests and regression analysis to assess the homogeneity and stability of the prepared standard substances, as well as the associated uncertainty in the obtained results. Each component in the mixed standard substance yielded calibration values of 3.00 ng/μL with a relative expanded uncertainty Urel of 3%, at a coverage factor (k) of 2. Comprehensive experimentation involving raw material analysis, preparation of standard materials, assessment of uniformity and stability, and comparison of quantitative values confirmed that the developed standard material fulfills the criteria for national secondary standard substances. Consequently, it has been officially accredited with a certificate number GBW (E) 130677, enabling its utilization in the calibration of GC-MS instruments, specifically for the repeatability testing of retention times.
Measurement Management
Overview of CCQM’s 2021-2030 Strategic Planning
JIAO Hui, ZHANG Qinghe
2023, 67(7): 74-78. doi: 10.12338/j.issn.2096-9015.2021.0606
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In June 2021, the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM) released its development strategy for 2021-2030. This document outlines the vision, primary objectives, and strategic goals for the next decade, adhering to its mission of enhancing the global comparability of chemical and biological measurement standards and capabilities. This article organizes and summarizes the main content of the strategic plan, offering insights into the future developmental trends and key areas in the ‘amount of substance’ field. Understanding the CCQM development strategy helps in positioning China’s metrological strategic choices in the ‘amount of substance’, building strategic bilateral and multilateral relationships, innovating development models, and making a leap from aligning with international standards to leading development in this domain.