Method for two frequency point sound measurement of heat capacity of ideal gas

An ideal gas and sound measurement technology, applied in measurement devices, material analysis using sonic/ultrasonic/infrasonic waves, instruments, etc., can solve problems such as systematic errors, and achieve the effect of avoiding systematic errors

Inactive Publication Date: 2017-05-24
GUIZHOU INST OF TECH
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  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, the traditional method of measuring the heat capacity of an ideal gas by measuring the sound velocity value at a certain frequency or the average sound velocity value at multiple frequency points may cause the measured sound velocity value to change due to the difference in the selected sound frequency points. systematic error

Method used

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  • Method for two frequency point sound measurement of heat capacity of ideal gas
  • Method for two frequency point sound measurement of heat capacity of ideal gas
  • Method for two frequency point sound measurement of heat capacity of ideal gas

Examples

Experimental program
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Effect test

Embodiment 1

[0035] Embodiment 1: a two-frequency point-acoustic measurement method for ideal gas heat capacity, comprising the following steps:

[0036] (1) A dual-frequency signal generator is used to generate dual-frequency signals with sound frequencies of 40 kHz and 125 kHz respectively;

[0037] (2) the dual-frequency signal in the step (1) is converted into ultrasonic waves by the ultrasonic sending probe respectively;

[0038] (3) Ultrasonic wave in step (2) is passed through pure Cl 2 The medium (P=1atm, temperature T=273.15K) in the gas cavity propagates and the electrical signal converted by the ultrasonic receiving probe triggers the interrupt timer in the control module, calculates the time interval between sending and receiving of the signal, and measures the sound velocity c(ω 1 ) and c(ω 2 ) are 209.7m / s and 211.4m / s respectively; the signals received simultaneously and before attenuation enter the dual-channel peak detection module to complete the peak detection process ...

Embodiment 2

[0044] Embodiment 2: a two-frequency point-acoustic measurement method for ideal gas heat capacity, comprising the following steps:

[0045] (1) A dual-frequency signal generator is used to generate dual-frequency signals with sound frequencies of 40kHz and 125kHz respectively;

[0046] (2) the dual-frequency signal in the step (1) is converted into ultrasonic waves by the ultrasonic sending probe respectively;

[0047] (3) Ultrasound in step (2) passes through 80% CH 4 -20%N 2 The medium (P=1atm, temperature T=273.15K) in the gas chamber propagates and the electrical signal converted by the ultrasonic receiving probe triggers the interrupt timer in the control module, calculates the time interval between sending and receiving of the signal, and measures the sound velocity c(ω 1 ) and c(ω 2 ) are 418.5m / s and 420.3m / s respectively; the signal received at the same time and the signal before attenuation enter the dual-channel peak detection module to complete the peak detecti...

Embodiment 3

[0053] Embodiment 3: a two-frequency point-acoustic measurement method for ideal gas heat capacity, comprising the following steps:

[0054] (1) A dual-frequency signal generator is used to generate dual-frequency signals with sound frequencies of 60kHz and 100kHz respectively;

[0055] (2) the dual-frequency signal in the step (1) is converted into ultrasonic waves by the ultrasonic sending probe respectively;

[0056] (3) Ultrasound in step (2) passes through 80% CO 2 -20%N 2 The medium (P=1atm, temperature T=273.15K) in the gas chamber propagates and the electrical signal converted by the ultrasonic receiving probe triggers the interrupt timer in the control module, calculates the time interval between sending and receiving of the signal, and measures the sound velocity c(ω 1 ) and c(ω 2 ) are 287.0m / s and 288.2m / s respectively; the signal received at the same time and the signal before attenuation enter the dual-channel peak detection module to complete the peak detecti...

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Abstract

The invention discloses a method for two frequency point sound measurement of heat capacity of ideal gas. First two-frequency signals with sound frequencies being Omega1 and Omega2 respectively occur; the two-frequency signals are converted into mechanical sound waves respectively, transmission sound velocities c(Omega1) and c(Omega1) of the mechanical sound waves in an ideal gas medium and relaxation absorption coefficient Alpha(Omega1) and Alpha(Omega2) are respectively measured; according to the measured c(Omega1), c(Omega1), Alpha(Omega1) and Alpha(Omega2), effective heat capacities as shown in the descriptions are obtained by the formula as shown in the description, vibrational coupling molar heat capacities, as shown in the description, of the ideal gas are obtained by calculating the effective heat capacities as shown in the descriptions; and finally the heat capacity Cv of the ideal gas is obtained through a formula as shown in the description according to the vibrational coupling molar heat capacities. According to the measurement method, the influence of acoustic disturbance on gas heat capacity measurement results is effectively eliminated, and system errors generated in a conventional gas heat capacity acoustic measurement method due to sound velocity dispersion can be avoided.

Description

technical field [0001] The invention relates to a method for measuring the heat capacity of an ideal gas, in particular to a two-frequency point-acoustic measurement method for the heat capacity of an ideal gas. Background technique [0002] Heat capacity is an important physical parameter in the study of gas in thermodynamics, and it is of great significance and role in the study of the thermophysical properties of fluid working fluids. As long as the heat capacity of the fluid in the ideal gas state is known as a function of temperature and the equation of state of the fluid, the thermodynamic parameters such as internal energy, enthalpy, entropy, free energy, free enthalpy and fugacity coefficient of the fluid can be determined, and even It can also deduce the microscopic characteristics of molecular structure and intermolecular interaction. [0003] Heat capacity data in an ideal gas state is usually calculated using calorimetric methods or statistical methods from spec...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N29/024
CPCG01N29/024G01N2291/011G01N2291/021G01N2291/0215
Inventor 张克声郭晓学
Owner GUIZHOU INST OF TECH
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