Акустичний газоаналізатор
Date
2018-02-26
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Видавництво Львівської політехніки
Abstract
Запропоновано метод вимірювання відносних концентрацій складових дво- та трикомпонентних
сумішей газів, оснований на залежності швидкості поширення звуку від таких параметрів, як молярна маса газів у суміші,
їх відносна концентрація, теплоємність за сталого тиску, теплоємність за сталого об’єму та абсолютна температура. Для
підвищення точності запропоновано перейти від вимірювань швидкості до вимірювань частоти. Показано, що за сталої
довжини хвилі частота акустичного резонатора лінійно зростатиме відповідно до зміни швидкісті поширення звуку в
газовій суміші. Запропоновано та перевірено алгоритм програми визначення концентрацій дво- та трикомпонентних
сумішей газів за резонансною частотою. Обґрунтовано, що основними чинниками, що впливають на точність вимірювань,
є шуми автогенератора та добротність акустичного резонатора. Запропоновано математичну модель і доведено, що
акустичні газоаналізатори порівняно простої конструкції можуть забезпечувати прийнятну точність.
Method of measuring the relative concentrations of two and three-component gas mixtures components is proposed. The dependence of the sound velocity on the molar mass, the relative concentration, the heat capacity at constant pressure, the heat capacity at a constant volume and the absolute temperature of the gases in the mixture form the basis of the method. To improve accuracy the alteration the measuring the speed on the measuring the frequency is proposed. It is shown that at constant wavelengths the frequency increases linearly with sound velocity at the gas mixture in the acoustic resonator. The program algorithm was created with the help of Mathcad 2001 Professional. It permits the determination of three component gaseous mixture concentration at the measured frequency. First, the frequency value inherent to this mixture is compared with the values in the table. Two closest values are selected. The change in relative concentrations of gases is determined by these values. This change is split into 10 intervals. The frequency values for each interval are calculated. These frequencies are compared with the measured values. Again, there are two closest values and the cycle is repeated. In such a way the nearest frequency increment band is narrowed in 3-orders magnitude after three iterations. Change in the concentration of particular gases could be 80 % between the adjacent rows of the table. Determined value of gas concentration is one thousand times smaller than the band (0,8 %) after the third iteration. The number of iterations is unlimited for this algorithm and is given in advance. The two main factors affect the accuracy of measurements. They are the quality and the noise of the auto generator. The most common definition of Q is the ratio of the energy accumulated in the oscillation to the losses of this energy. This definition defines the design of an acoustic resonator. It should be such that the acoustic oscillations that occur in it do not lose energy. This is necessary to ensure a high-quality resonator.
Method of measuring the relative concentrations of two and three-component gas mixtures components is proposed. The dependence of the sound velocity on the molar mass, the relative concentration, the heat capacity at constant pressure, the heat capacity at a constant volume and the absolute temperature of the gases in the mixture form the basis of the method. To improve accuracy the alteration the measuring the speed on the measuring the frequency is proposed. It is shown that at constant wavelengths the frequency increases linearly with sound velocity at the gas mixture in the acoustic resonator. The program algorithm was created with the help of Mathcad 2001 Professional. It permits the determination of three component gaseous mixture concentration at the measured frequency. First, the frequency value inherent to this mixture is compared with the values in the table. Two closest values are selected. The change in relative concentrations of gases is determined by these values. This change is split into 10 intervals. The frequency values for each interval are calculated. These frequencies are compared with the measured values. Again, there are two closest values and the cycle is repeated. In such a way the nearest frequency increment band is narrowed in 3-orders magnitude after three iterations. Change in the concentration of particular gases could be 80 % between the adjacent rows of the table. Determined value of gas concentration is one thousand times smaller than the band (0,8 %) after the third iteration. The number of iterations is unlimited for this algorithm and is given in advance. The two main factors affect the accuracy of measurements. They are the quality and the noise of the auto generator. The most common definition of Q is the ratio of the energy accumulated in the oscillation to the losses of this energy. This definition defines the design of an acoustic resonator. It should be such that the acoustic oscillations that occur in it do not lose energy. This is necessary to ensure a high-quality resonator.
Description
Keywords
газоаналізатор, відносна концентрація, резонансна частота, акустичний резонатор, автогенератор, добротність резонатора, трикомпонентна суміш газів, gas analyzer, relative concentration, resonance frequency, acoustic resonator, auto generator, Q-factor of a resonator, three-component gas mixture
Citation
Рак В. С. Акустичний газоаналізатор / В. С. Рак, Я. Т. Луцик // Вимірювальна техніка та метрологія : міжвідомчий науково-технічний збірник. — Львів : Видавництво Львівської політехніки, 2018. — Том 79. — № 2. — С. 13–19.