共查询到20条相似文献,搜索用时 46 毫秒
1.
2.
3.
4.
Primary standard gas flow meters are developed for various applications such as calibration of leak artefacts, generation of calibration pressures by dynamic gas expansion and calibration of secondary standard gas flow meters. The Istituto di Metrologia “G. Colonnetti” (IMGC), Italy, and the University of Applied Sciences Giessen-Friedberg (UASG), Germany, maintain primary flow meters based on different principles in order to measure small gas flows delivered either to vacuum (i.e. practically zero pressure) or to atmosphere (ambient pressure). The principle, design and properties of these flow meters are described. Comparison of the primary standard flow meters maintained at these laboratories was performed over a range from 3×10−8 to 7×10−4 Pa m3/s with nitrogen, using a crimped capillary leak as a transfer standard. IMGC was the pilot laboratory. During the intercomparison, the transfer standard changed by ca. −2% for flow to vacuum and by ca. −4% for flow to atmosphere without obvious reason. The results of the intercomparison show that the laboratories agree within their expanded uncertainties over the measured range of gas flows. 相似文献
5.
6.
利用流量传感器、配对温度传感器、PC机、PLC为主要硬件,组态王软件为开发平台,构建热能表自动检定装置。根据检定点,控制流量阀、调频水泵,输入被检表的读数,装置自动采集到流量值、温度值、压力值,计算出热能表各个检定点的相对误差。实现可视的操作界面、保存检定数据、打印检定证书等功能。 相似文献
7.
An experimental apparatus has been designed to test the use of cross flow heat exchangers. Three identical fin-tube type cross flow heat exchangers are mounted on a board instrumented with thermocouples, flow meters, and a pressure transducer. The apparatus can be set to test the performance of a solo heat exchanger, two or three heat exchangers in series or parallel, or combinations incorporating both series and parallel configurations. The apparatus is relatively simple, inexpensive, and versatile. It may be used in a variety of configurations for several types of student laboratories ranging from demonstrations to design projects. The use of an apparatus such as this gives students hands on experience with experimental procedures and helps them to gain a physical understanding of heat transfer phenomena. 相似文献
8.
A pulsed jet pleated paper cartridge filter system was tested for particle removal efficiency and operating stability using agricultural limestone as the test dust. The test system consisted of 6 pleated paper filter units arranged in parallel, each unit having an effective filtration area of 18.1 square meters. The system was operated at constant pressure drops of 6.25, 7.50 and 8.75 kPa (2.5, 3.0 and 3.5 inches of water), with face velocities of 0.78 to 1.04 m/ min (2.5 to 3.4 feet per minute) and dust loadings ranging from 0.5 g/ m to 2.5 g/ m3. Penetration through the media appeared to be relatively independent of dust loading, and efficiencies were in the 99.95 + % range. Slightly lower efficiencies were found for particles having diameters of 0.3 to 1.0 micrometers. A measure of the redeposition of dust pulsed from the filter was required to describe the effects on the pulse rate caused by changes in system flow and pulsing set point. Increased redeposition was found to occur with increasing flow rate, causing an increase in the pulse rate required to maintain operation of the system at a pulsing set point. Overall, the reverse pulse jet pleated paper cartridge filter system displayed extremely high particle removal efficiency in a compact unit that operated with low differential pressure. 相似文献
9.
The paper presents a new method for indirect flow rate measurement in elbow flow meters. The idea of the method consists in selecting such a Reynolds number value, assumed as a coefficient in fluid flow equations, which fulfils with set accuracy the condition of equality between the measured and the computed pressure difference at the end points of the secant of the elbow arch. The calculus takes into account also the accurate flow geometry, the values of coefficients which describe the thermo-physical properties of the fluid at the measurement temperature, and proper equations of the turbulence model. A special test stand was arranged in order to implement the proposed method in practice. The numerical computations were carried out using the software package FLUENT 6.1. The results of calculations were compared with the corresponding results of measurements achieved on the stand, as well as ones found in the bibliography [?, ?]. A comparison of the outcome of calculations with experimental readings shows a high grade of consistence. 相似文献
10.
PARKER C. REIST DAVID F. UTTERBACK HARRY BARR 《Particulate Science and Technology》2013,31(4):315-323
ABSTRACT A pulsed jet pleated paper cartridge filter system was tested for particle removal efficiency and operating stability using agricultural limestone as the test dust. The test system consisted of 6 pleated paper filter units arranged in parallel, each unit having an effective filtration area of 18.1 square meters. The system was operated at constant pressure drops of 6.25, 7.50 and 8.75 kPa (2.5, 3.0 and 3.5 inches of water), with face velocities of 0.78 to 1.04 m/ min (2.5 to 3.4 feet per minute) and dust loadings ranging from 0.5 g/ m to 2.5 g/ m3. Penetration through the media appeared to be relatively independent of dust loading, and efficiencies were in the 99.95 + % range. Slightly lower efficiencies were found for particles having diameters of 0.3 to 1.0 micrometers. A measure of the redeposition of dust pulsed from the filter was required to describe the effects on the pulse rate caused by changes in system flow and pulsing set point. Increased redeposition was found to occur with increasing flow rate, causing an increase in the pulse rate required to maintain operation of the system at a pulsing set point. Overall, the reverse pulse jet pleated paper cartridge filter system displayed extremely high particle removal efficiency in a compact unit that operated with low differential pressure. 相似文献
11.
12.
针对气液两相流流过槽式孔板时产生的差压信号呈现出的非高斯特性,提出了一种基于高阶谱技术的信号分析方法.通过对槽式孔板两端差压信号进行的双谱分析,提取了不同流量下信号的非高斯特征.以信号的双谱幅度最大值和双谱切片幅度最大值作为特征参数,对不同流型、流量下差压信号偏离高斯分布的程度进行了定量估计.结果表明,提取的特征值不仅可作为气液两相流流型转变的判据,而且还为进一步优化两相流流量计的设计提供了参考. 相似文献
13.
14.
V. S. Sheiko 《Measurement Techniques》1958,1(2):190-192
Conclusions This portable set may find a wide application both in State Inspection Laboratories for Measuring Equipment and in establishments connected with the testing and repair of electricity meters, in particular in Base Laboratories for Departmental Inspection. It is therefore advisable to organize mass production of these sets. 相似文献
15.
Jonathan S. Colton John Baxter Jack Behlendorf Tabassum Halim Bryan Harris Gary Kiesler Kuou-Tung Lu Susan Sammons George W. Woodruff 《Materials and Manufacturing Processes》1987,2(1):1-22
The processing of PEEK/graphite fiber composites is characterized by an inordinate amount of hand labor. This greatly increases the cost, time, and inaccuracy involved in production. Automation of the lay-up and consolidation steps are a prerequisite for the widespread application and acceptance of these, as well as all, high performance materials. Automated techniques for the lay-up and consolidation of PEEK/graphite fiber composites have been developed and are presented in this paper. Discrete part lay-up schemes utilize robotic manipulators and specially constructed tables and allow any lay-up configuration to be automatically produced at high production rates. The size of the discrete parts was limited to 4 by 4 meters by design, not by any inherent difficulties. This size can be increased by enlarging the lay-up table. The length of a continuous sheet was limited by the length of the PEEK/graphite fiber prepreg material currently available. Its width was also restricted to 4 meters by design, but also can be increased to the desired width. Continuous consolidation methods were designed for both discrete and continuous parts. Heating is performed by quartz radiative heaters and consolidation pressure is produced by pressure rollers. These processes were designed taking into consideration 相似文献
16.
17.
18.
19.
We describe new features of vacuum membrane capacity meters with electrostatic compensation, which improves their performance and expands their functional applicability for measuring volumes with complex configurations and flow rates of small gas streams. The concept is based on introduction of an additional reservoir with mobile gas-impermeable gate. When connected to the chambers of pressure gauge converter, the unit reduces the chamber volume in the course of pressure measurement so as to modify the conversion ratio in the vacuum meter measurement equation.Translated from Izmeritel'naya Tekhnika, No. 6, pp. 9–10, June, 1993. 相似文献
20.
随着长江三峡水库蓄水及蓄水量的变化,必将引起库坝地区局部介质受力状态、介质物理性质和区域应力场等的变化,从而可能诱发水库地震。为有效监测库区地壳变形、构造断裂的活动趋势、库盘沉降及水库诱发地震活动,在库坝区建立水库诱发地震监测系统是必要的。文章简要介绍了长江三峡水库诱发地震监测系统的建设情况。 相似文献