MEMS家用热式燃气表结构与计量特性

随着对微机电系统(MEMS)的深入研究和取得的进展,传统的工业和流体力学研究的流量传感器向高集成度、微型化、高精度、高可靠性方向发展。大规模半导体集成技术的不断创新,使基于MEMS技术的气体流量仪表进入规模化生产成为可能。文章对基于MEMS技术的热式流量传感器的原理和JGM系列MEMS家用热式燃气表结构作了简要介绍,重点评述了由荷兰NMi实验室检测的仪表流量误差特性和压力损失特性,以及热式技术应用于燃气计量的耐污染、极小流、噪声干扰、空气与燃气间关系等关键问题。从检测结果可知,该型仪表流量范围度达到1∶250,流量示值误差等主要技术指标满足欧盟MID指令要求。最后对基于MEMS技术的热式燃气表的发展趋势进行了展望。     

热式气体质量流量传感器的工作原理及其应用

<正>一、前言热式气体质量流量传感器是气体质量流量控制器中一个重要的核心部件,对气体质量流量控制器的性能指标,如零漂、准确度、线性、重复度、响应时间等重要指标参数有直接影响。要使气体质量流量控制器的性能指标得到明显改善,首先就要提升热式气体质量流量传感器的性能。然而,热式气体质量流量传感器的性能与其本身的结构参数设计是密切相关的。如     

热式气体流量计信号采集电路的设计与研究

首先介绍了气体流量测量的必要性及影响其测量精度的主要因素,并介绍了热式气体流量计测量气体流量的原理,推导出流体流速与电流之间的表达关系式.根据定温法测量原理,分析了惠斯通电桥电路的作用.然后设计了热式气体流量计信号采集电路,并分析了电路的工作原理及其温度补偿作用,介绍了其优点及创新之处.通过实验研究,得到流量与输出电压的实验数据;对数据进行拟合处理,得到流量与输出电压的表达关系式.实验结果表明:信号采集电路基本消除了因流体温度变化引起的测量误差,提高了系统的测量精度,基本达到工业生产的要求.     

不同热源分布对热式气体质量流量计毛细管温差分布的影响

该文根据热式气体质量流量计的工作原理,通过建立传热方程,对流量计毛细管不同热源模型条件下的流量与温度分布变化开展仿真研究。基于单热源、双热源与四热源加热方式,对热式气体质量流量计的传感器布置方式进行设计与仿真,得到了不同布置方式带来的温差分布影响,分析了影响热式气体质量流量计的主要因素及变化规律。     

基于组合铂膜探头的气体流量计实验研究与数据处理

介绍了一种基于传热原理的组合铂膜探头.在对该组合热膜探头的温度特性以及温度补偿性能实验研究的基础上,设计了具有温度补偿的气体流量传感器,并在钟罩装置上对该流量传感器进行了流量检测实验,对实验结果的拟合和处理表明,该气体流量传感器的测量精度优于1%,流量范围度大于100:1.     

微小气体流量检测技术的研究

系统地介绍了用热式流量传感器测量微气体流量的方法，并在此基础上提出了微气体流景检测仪器的设计方案，同时阐述了微气体流量检测的基本概念、检测方法以及热式质量流量的测量原理。设计的检测仪器方案主要以AWM3100为核心组成，相关的电路设计包括A／D转换电路，信号选通电路，复位电路，按键电路以及以AT89C52为核心的采集控制电路，最后为该检测仪器设计了软件流程图。     

动态气体配气仪流量校准的简析

为了满足人们对不同浓度标准气体的需求,动态气体配气仪应运而生。动态气体配气仪主要由热式质量流量计组成,热式质量流量计控制流量的精度直接影响着配出气体浓度的准确度。本文详细介绍了皂膜式气体流量标准装置校准动态气体配气仪的过程。     

正压式标准表法气体流量标准装置的建立

为了能准确地对南京港华燃气有限公司内部用于“西气东输”的气体流量仪表进行检定．江苏省计量科学研究院与南京港华燃气有限公司合作建立了正压式标准表法气体流量标准装置（以下简称“装置”）,开展对气体流量仪表的检定工作。     

弯管流量计的计量特性及其在热电行业的节能效益验证

流量仪表在实现有效计量的同时,也会造成能量损耗.科学选择流量仪表,以有效解决准确计量与计量仪表耗能这一矛盾,是做好能源计量的重要工作.经过理论分析和实践总结,笔者认为,在气体流量测量中以弯管流量计替代常见的孔板式差压流量测量装置,既能准确测量气体的流量,又可免除孔板节流装置的压损,达到节能的效果.     

热式气体流量计的温度补偿

<正>本文主要利用径向基函数(RBF)神经网络算法在温度补偿中的优势,分析不同温度对气体流量测量的影响,设计一种基于RBF神经网络的温度补偿方法,有效避免硬件电路补偿方法的单一性和不稳定性,在降低成本的同时提高测量装置的准确性。最终采用软件补偿的方法对热式气体流量计的温度补偿进行了大量实验研究,实现了温度梯度变化下热式气体流量计的高精度测量。一、热式流量计的工作原理及分类     

Measurement of cryogenic regenerator characteristics under oscillating flow and pulsating pressure

This paper describes an experimental apparatus developed to investigate detailed thermal and hydrodynamic characteristics of a regenerator at cryogenic temperature under oscillating flow and pulsating pressure conditions. Cold-end of the regenerator is maintained at approximately 85 K for G-M cryocooler type and 100 K for Stirling cryocooler type operations by means of two cryogenic heat exchangers. At both ends of the regenerator, fine hot wire probes are installed to measure the fast oscillating gas temperature and mass flow rate. The gas temperature sensors installed very close to the ends of the regenerator matrix assure precise gas temperature measurement in the regenerator. In this study, thermal and hydrodynamic behaviors of the well-defined wire-screen regenerator are fully characterized. First, pressure drop characteristics are discussed for different frequencies under room temperature. Second, ineffectiveness of the regenerator is obtained for different cold-end temperatures.     

A new approach to estimating the main error of a primary transducerfor an electromagnetic flowmeter

The existing methods for estimating the error caused by various flow parameters for electromagnetic flowmeters are based on nonhomogeneity in the distribution of a weight vector. The author presents a new numerical flow generator, called the moving stream method, that allows for an estimate of the primary error for a flowmeter during the design stage much more precisely than classical methods. It considers the contribution to measurement error that various flow velocities make within a measurement zone. The simulated flows account for all hydrologic conditions existing in the field     

Determining of gas type in counter flow vortex tube using pairwise fisher score attribute reduction method

This paper focused on the determining of gas types in counter flow type vortex tubes. In the present study, four different gas types including air, oxygen, nitrogen, and argon in the vortex tube with different inlet pressures and nozzle numbers have been used. The main aims of this paper are to investigate the correlations between gas types and input parameters comprising nozzle numbers, inlet pressures, inlet mass flow rate, temperature of cold outlet, temperature of hot outlet, and cold mass fraction and to select the most important attributes using correlation based attribute reduction and pairwise fisher score attribute reduction (PFSAR). After attribute reduction methods applied to dataset, k-nearest neighbor and C4.5 decision tree classifiers have been used to determine the gas type in the RHVT. The results have demonstrated that the PFSAR is a robust and efficient method in the reduction of attributes belonging to vortex tube.     

电驱动双活塞式气体流量标准装置的仿真研究

设计研制了一套用于检定临界流流量计的双活塞式气体流量标准装置.该装置利用两个活塞交替运行产生连续标准流量,可有效提高检定流量上限.介绍了该双活塞式气体流量标准装置的机械结构和检定原理;然后在Simulink仿真环境下,搭建了装置系统模型,并在此基础上进行了在最大检定流量点和最小检定流量点上活塞联动过程的仿真.结果显示,压力、流量等几项重要指标均能控制在规定的范围内,该装置可用于临界流流量计的检定.     

Evaluation of the effect of free gas on the measurement error for crude oil mass by coriolis flowmeters and dissolved gas on the error of measuring well production rate

Results are presented for experimental studies of estimating the effect of free gas on the metrological properties of coriolis flowmeters. The requirement is demonstrated for considering gas dissolved in oil during measurement of well production rate.     

Measurement of Helium Micro Flows for Gas Chromatography by the Dilution Method

More and more chemical analysis laboratories using gas chromatography need to measure the different flows involved during the analysis process (split ratio, column flow). The measurement of the column flow is certainly the most difficult because the flow of carrier gas is generally very small. For example, the flow of helium (the most often used carrier gas) is typically <15???g/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?C30???g/s (0.25?C10?cm³/min) with an expanded uncertainty of 0.6?% or less at the 95% confidence level. The traced gas method, the uncertainty estimation of the calibration bench and the calibration results of a laminar flow element type Molbloc and an industrial mass flowmeter are presented in this paper.     

The Characterization of a Piston Displacement-Type Flowmeter Calibration Facility and the Calibration and Use of Pulsed Output Type Flowmeters

Critical measurement performance of fluid flowmeters requires proper and quantified verification data. These data should be generated using calibration and traceability techniques established for these verification purposes. In these calibration techniques, the calibration facility should be well-characterized and its components and performance properly traced to pertinent higher standards. The use of this calibrator to calibrate flowmeters should be appropriately established and the manner in which the calibrated flowmeter is used should be specified in accord with the conditions of the calibration.These three steps: 1) characterizing the calibration facility itself, 2) using the characterized facility to calibrate a flowmeter, and 3) using the calibrated flowmeter to make a measurement are described and the pertinent equations are given for an encoded-stroke, piston displacement-type calibrator and a pulsed output flowmeter. It is concluded that, given these equations and proper instrumentation of this type of calibrator, very high levels of performance can be attained and, in turn, these can be used to achieve high fluid flow rate measurement accuracy with pulsed output flowmeters.     

基于收缩流动的气体超声流量计声道稀疏化及测量方法

为了提高低声道数超声流量计的准确度水平,在传统超声流量计的基础上设计了一种具有收缩流动结构的低声道数超声流量计。采用数值模拟研究了渐缩管中收缩流动的流场特征,确定了渐缩管的几何参数及超声探头的安装方式。通过空气实流实验,研究了单声道及双声道在收缩流动条件下流量计量的基本特性。在流量范围27~432m3/h,管径范围100~150mm进行了实验验证。结果表明:收缩流动的数值模拟结果与理论模型相吻合,当渐缩管的收缩比由2增大为6,被测流场均匀区占比显著增大;当收缩比固定不变时,随着流量的增大,边界层厚度显著降低。通过实流实验比较不同结构和配置超声流量计的测量结果,发现单声道收缩管超声流量计的准确度水平显著优于传统单声道气体超声流量计,与传统双声道气体超声流量计的准确度水平相当。     

Rational choice of the constriction of a flowmeter

The solution of the urgent problem of choosing the type of constriction in flowmeters with a variable pressure drop in industrial instruments for measuring the flow rate of liquids, gases and vapors is considered. Ten criteria are established by which the constriction must be chosen, numerical characteristics are given, and recommendations are made on the rational area of application of each type of constriction. Translated from Izmeritel'naya Tekhnika, No. 9, pp. 33–35, September, 1996     

Use of wall-type electromagnetic velocity gauges to measure flow rate in largediameter water pipes

The following are determined in this study; the strength of the signal received from the electrodes of wall-type flowmeters; the working region of the channel; flow rate with an asymmetric flow-velocity profile; error of measurement of flow rate with allowance for changes in hydrodynamic conditions and imprecise positioning of flowmeters in the cross-section of the pipe channel. Translated from Izmeritel'naya Tekhnika, No. 5, pp. 22–28, May, 1997.