Volume 2, Number 2 (2016)
Peculiarities of Non-Stationary Pressure Measurement in Real Time
Myroslav Tykhan
Lviv Polytechnic National University, 12, S. Bandery str., Lviv, 79013, Ukraine
Received: April 18, 2016. Revised: December 12, 2016. Accepted: December 23, 2016
© 2016, Tykhan M. Published by Lviv Polytechnic National University
Abstract
Nowadays, industrial development creates new and more complex processes leading to emergence of specific conditions for use of sensors and therefore specific measurement tasks. These circumstances lead to new requirements both for the methods of measurement and for sensors that implement these methods. Developments in microelectronic technologies and materials science have led to a significant number of types of pressure sensors. However, in recent years, despite the growing number of sensors range, it is in high-tech industries that the need for pressure sensors with fundamentally new features and characteristics has increased dramatically. This is caused by the need to rapidly measure unsteady pressure in real time, with a normalized error mostly within the static one. Taking this into account, the features of non-stationary pressure measurement in real time are analyzed in this paper and the necessary and sufficient requirements for sensors that allow their effective use are outlined. Thus, the goal of this work is the analysis of the process of measuring the non-stationary pressure in real time, aimed at identifying the peculiarities of the measurement problem and development of ways of its solution.
Keywords: peculiarities; measurement; unsteady; pressure; real time; sensor.
References – 18.
Techniques for Natural Gas Physical Properties Definition
for Flow Rate and Volume Metering Systems
Fedir Matiko , Halyna Matiko, Vitalii Roman, Ivan Stasiuk
Lviv Polytechnic National University, 12, S. Bandery str., Lviv, 79013, Ukraine
Received: November 18, 2016. Revised: December 12, 2016. Accepted: December 26, 2016
© 2016, Matiko F., Matiko H., Roman V., Stasiuk I. Published by Lviv Polytechnic National University
References – 18.
Preparation of Papers for the Journal EECS
Roman Fedoryshyn, Sviatoslav Klos, Volodymyr Savytskyi, Oleh Masniak Identification of Controlled Plant and Development of Its Model by Means of PLC
Optimization of Gas Dynamical Subsystem of Transducers for
Measurement of Gas Flow Temperature
Vasyl Fedynets , Ihor Vasylkivskyi, Yaroslav Yusyk
Lviv Polytechnic National University, 12, S. Bandery str., Lviv, 79013, Ukraine
Received: November 11, 2016. Revised: December 12, 2016. Accepted: December 26, 2016
© 2016, Fedynets V., Vasylkivskyi I., Yusyk Ya. Published by Lviv Polytechnic National University
Abstract
The main types of errors which occur while measuring the temperature of gas flows, including flows of fuels, are determined by the conditions of thermal balance at the interaction of the sensor of the temperature transducer (TT) with the gas flow via convection, radiation and conduction. The limited TT capacity to track flow temperature variation should also be taken into consideration. For high gas flow speeds (over 50 m/s), another type of error (the so-called speed error) arises from the transformation of part of kinetic energy of the flow into thermal energy. A comprehensive analytical study of the combined influence of all the major factors on the total error of gas flow temperature measurement with a particular TT is actually impracticable, since some relationships describing the character of influence of this or that factor can be obtained only by experiment. Therefore, in practice, each error type is analysed separately, assuming that no other types of error occur, and the total error of measurement is regarded as superposition of separate error types. For convenience of analysis, TT is represented as a combination of separate units, each with its own components of the error. TT for gas flow temperature measurements appears as three units, such as gas dynamic, thermal and electrical, connected in series. The gas dynamic subsystem transforms the thermodynamic temperature T(τ) of the gas flow at the TT input into the deceleration temperature ТПТ(τ) at the temperature sensor input and is characterized by the speed error. The defining characteristic of the gas dynamic subsystem is the TT recovery factor, which is why the paper discusses the methods and means of ensuring the constancy of the recovery factor.
Keywords: gas flow; measurement; heat exchange; temperature; temperature transducer.
References – 15.
Calculation of Expansibility Factor of Gas at Its Flow Through
an Orifice Plate With Flange Pressure Tappings
Yevhen Pistun, Leonid Lesovoy
Lviv Polytechnic National University, 12, S. Bandery str., Lviv, 79013, Ukraine
Received: October 9, 2015. Revised: February 26, 2016. Accepted: December 26, 2016
© 2016, Pistun Y., Lesovoy L. Published by Lviv Polytechnic National University
Abstract
The values of expansibility factor of gas were defined more accurately based on the values obtained by Seidl in CEESI using the equation of mass flowrate and on the basis of experimental data (differential pressure across the orifice plate, mass flowrate, absolute static pressure and temperature of air) for orifice plates with flange pressure tappings and diameter ratios of 0.242, 0.363, 0.484, 0.5445, 0.6655, 0.728 and pipe internal diameter of 52.48 mm (2.066 in.). When obtaining the values of expansibility factor of gas, the Stolz equation was used by Seidl to calculate the discharge coefficient for Reynolds numbers equal to infinity. New values of expansibility factor of gas are defined more accurately by us with taking into account the Reader-Harris/Gallagher equation for calculating the discharge coefficient for the actual Reynolds numbers of gas in the pipe. Based on these new more accurate data a new equation for calculating the expansibility factor of gas for orifice plate with flange pressure tappings is developed. The comparison and analysis of the expansibility factor calculated according to the equation given in ISO 5167:2-2003 and according to the new developed equation is presented in the paper. The equation in ISO 5167:2-2003 for computing the gas expansibility factor is developed for all three types of pressure tappings arrangement. In this case the scattering of discharge coefficient values being applied for deriving the expansibility factor equation is large for the same set of input data. It is shown that the shortcomings mentioned above are eliminated in the new equation and the standard deviation of the expansibility factor calculated according to the new equation from the new accurate experimental values is smaller. New formula for calculating the relative expanded uncertainty of expansibility factor for orifice plate with flange pressure tappings is also presented in the paper.
Keywords: expansibility factor; flowrate measurement; orifice plate; flange tappings.
References – 15.
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