阅读说明：本技术 一种利用解耦声弛豫谱探测氢气混合气体的方法及系统 (Method and system for detecting hydrogen mixed gas by using decoupling acoustic relaxation spectrum ) 是由 张向群 程菊明 王小平 张永 袁雅婧 张柯 姚丹丹 于 2019-08-21 设计创作，主要内容包括：本发明公开了一种利用解耦声弛豫谱探测氢气混合气体的方法及系统,属于混合气体探测技术领域,解决了现有技术中探测氢气混合气体的低精度、高成本、高设备要求的问题。一种利用解耦声弛豫谱探测氢气混合气体的方法,包括以下步骤：将解耦的氢气转动弛豫定压热容表达式结合振动弛豫解耦模型,得到转动与振动混合弛豫解耦总模型；采集声波在混合气体中的声速、声弛豫吸收系数以及混合气体的压强和密度；根据热力学的有效声速和有效角波数表达式、声波在气体传播中的有效热力学声速平方表达式以及转动与振动混合弛豫解耦总模型,得到混合气体成分的比例。实现了较高精度、低成本、低设备要求的探测出氢气混合的气体比例。(The invention discloses a method and a system for detecting hydrogen mixed gas by utilizing a decoupling acoustic relaxation spectrum, belongs to the technical field of mixed gas detection, and solves the problems of low precision, high cost and high equipment requirement of detecting hydrogen mixed gas in the prior art. A method for detecting hydrogen gas mixture by using a decoupling acoustic relaxation spectrum comprises the following steps: combining the decoupled hydrogen rotation relaxation constant pressure heat capacity expression with a vibration relaxation decoupling model to obtain a rotation and vibration mixed relaxation decoupling total model; collecting sound velocity and sound relaxation absorption coefficient of sound waves in the mixed gas and pressure and density of the mixed gas; and obtaining the proportion of the components of the mixed gas according to an effective thermodynamic sound velocity and effective angular wave number expression, an effective thermodynamic sound velocity square expression of sound waves in gas transmission and a rotation and vibration mixed relaxation decoupling total model. The method and the device have the advantages of realizing the detection of the gas proportion of the hydrogen mixture with higher precision, low cost and low equipment requirement.)

1. A method for detecting hydrogen gas mixture by using a decoupling acoustic relaxation spectrum is characterized by comprising the following steps:

obtaining a numerical solution of the number change rate of the internal freedom degree molecules according to a transfer probability equation among the rotation energies of the hydrogen and a hydrogen rotation energy transfer probability matrix, obtaining a decoupled hydrogen rotation relaxation constant pressure heat capacity expression by the numerical solution of the number change rate of the internal freedom degree molecules, and combining the decoupled hydrogen rotation relaxation constant pressure heat capacity expression with a vibration relaxation decoupling model to obtain a rotation and vibration mixed relaxation decoupling total model;

collecting sound velocity and sound relaxation absorption coefficient of sound waves in the mixed gas and pressure and density of the mixed gas;

and obtaining the proportion of the components of the mixed gas according to the sound velocity, the acoustic relaxation absorption coefficient and the pressure and density of the mixed gas, as well as according to an effective thermodynamic sound velocity and effective angular wave number expression, an effective thermodynamic sound velocity square expression of sound waves in gas transmission and a rotation and vibration mixed relaxation decoupling total model.

2. The method for detecting a hydrogen gas mixture by using a decoupled acoustic relaxation spectrum according to claim 1, wherein a numerical solution of the change rate of the number of molecules of the internal degree of freedom is obtained according to a transition probability equation among the rotational energies of hydrogen and a rotational energy transition probability matrix of hydrogen, and specifically comprises: equation of transition probability between rotation energies of the hydrogen

Transformation to (B + I ω I) x ═ D, where x is_J＝dN_J/dT，E is the rotational energy of hydrogen, B is the rotational energy transfer probability matrix, B_IJ＝k_IJ，B_JI＝k_JI，k_JIFor the transition probability between the rotation energies of hydrogen, I is an identity matrix, omega is an angular frequency, I, J represents the number of quanta where the rotation energy level is located, I ≠ J, M is the total number of quanta, T is temperature, N is_I、N_JIs the number of molecules at the rotational energy level;

obtaining a numerical solution of the change rate of the number of the molecules of the internal freedom degree according to the transfer probability equation among the rotation energies of the hydrogen and the hydrogen rotation energy transfer probability matrix B

Wherein, V_Jn、d′_nRespectively, the elements of the matrix V, D, the matrix V is the eigenvector matrix, lambda, of the hydrogen rotational energy transfer probability matrix B_nIs the nth eigenvalue of matrix B.

3. The method for detecting a hydrogen gas mixture by using a decoupled acoustic relaxation spectrum as claimed in claim 2, wherein the obtaining of the decoupled expression of the rotational relaxation constant pressure heat capacity of hydrogen by the numerical solution of the change rate of the number of molecules of the internal degree of freedom specifically comprises:

solving x for the value of the rate of change of the number of molecules of the internal degree of freedom_JSubstituting the effective constant pressure heat capacity expression of the hydrogen to obtain a decoupled hydrogen rotation relaxation constant pressure heat capacity expression

Wherein the content of the first and second substances,is a hydrogen gasThe dynamic heat capacity is improved by the dynamic heat capacity,n is 0,1 Λ N, N is the number of single rotation relaxation processes, b_JRepresents p-H₂Or o-H₂The mole fraction occupied.

4. The method for detecting hydrogen gas mixture by using decoupled acoustic relaxation spectrum according to claim 3, wherein the decoupled hydrogen rotational relaxation constant pressure heat capacity expression is combined with the vibration relaxation decoupling model to obtain a rotational and vibration hybrid relaxation decoupling total model, which specifically comprises:

rotating relaxation constant pressure heat capacity expression of hydrogenLinearly combining with the vibration relaxation decoupling model to obtain a rotation and vibration mixed relaxation decoupling total model

Wherein, g_JIs the molar component of the hydrogen gas,is the molar component of the mixed gas except hydrogen,is the external effective heat capacity of the mixed gas except hydrogen,n is 0,1 lambdan, N is the number of single rotation relaxation processes,a_j、respectively represent the respective molar components and the vibrational heat capacity of the mixed gas other than hydrogen,and τ_mRespectively decoupled vibration relaxation processes and corresponding relaxation times, b_JE_JRepresents the contribution of the J-th decoupling process to the isobaric heat capacity.

5. A system for detecting hydrogen mixed gas by using a decoupling acoustic relaxation spectrum is characterized by comprising a rotation and vibration mixed relaxation decoupling total model building module, a data acquisition module and a mixed gas component detection module;

the rotation and vibration mixed relaxation decoupling total model building module is used for obtaining a numerical solution of the number change rate of the internal freedom degree molecules according to a transfer probability equation among the rotation energies of the hydrogen and a hydrogen rotation energy transfer probability matrix, obtaining a decoupled hydrogen rotation relaxation constant pressure heat capacity expression by the numerical solution of the number change rate of the internal freedom degree molecules, and combining the decoupled hydrogen rotation relaxation constant pressure heat capacity expression with a vibration relaxation decoupling model to obtain a rotation and vibration mixed relaxation decoupling total model;

the data acquisition module is used for acquiring the sound velocity, the acoustic relaxation absorption coefficient and the pressure intensity and the density of the mixed gas of the sound wave in the mixed gas;

and the mixed gas component detection module is used for obtaining the proportion of the components of the mixed gas according to the sound velocity, the acoustic relaxation absorption coefficient, the pressure and the density of the mixed gas, and according to a thermodynamic effective sound velocity and effective angular wave number expression, an effective thermodynamic sound velocity square expression of sound waves in gas transmission and a rotation and vibration mixed relaxation decoupling total model.

6. The system for detecting the hydrogen gas mixture by using the decoupled acoustic relaxation spectrum as claimed in claim 5, wherein the rotational and vibratory mixed relaxation decoupling total model building module comprises an internal degree of freedom molecule number change rate numerical solution obtaining unit,

the internal freedom degree molecule number change rate numerical solution obtaining unit is used for obtaining the numerical solution of the internal freedom degree molecule number change rate according to a transfer probability equation among the rotation energies of the hydrogen and a hydrogen rotation energy transfer probability matrix,

equation of transition probability between rotation energies of the hydrogen

Transformation to (B + I ω I) x ═ D, where x is_J＝dN_J/dT，E is the rotational energy of hydrogen, B is the rotational energy transfer probability matrix, B_IJ＝k_IJ，B_JI＝k_JI，k_JIFor the transition probability between the rotation energies of hydrogen, I is an identity matrix, omega is an angular frequency, I, J represents the number of quanta where the rotation energy level is located, I ≠ J, M is the total number of quanta, T is temperature, N is_I、N_JIs the number of molecules at the rotational energy level;

obtaining a numerical solution of the change rate of the number of the molecules of the internal freedom degree according to the transfer probability equation among the rotation energies of the hydrogen and the hydrogen rotation energy transfer probability matrix B

Wherein, V_Jn、d′_nRespectively, the elements of the matrix V, D, the matrix V is the eigenvector matrix, lambda, of the hydrogen rotational energy transfer probability matrix B_nIs the nth eigenvalue of matrix B.

7. The system for detecting hydrogen gas mixture by using decoupled acoustic relaxation spectrum according to claim 6, wherein said rotational and vibratory mixed relaxation decoupling total model building module further comprises a hydrogen rotational relaxation constant pressure heat capacity expression obtaining unit,

the hydrogen rotational relaxation constant pressure heat capacity expression obtaining unit is used for obtaining a decoupled hydrogen rotational relaxation constant pressure heat capacity expression according to the numerical solution of the number change rate of the internal freedom degree molecules, and specifically comprises the step of solving the numerical solution x of the number change rate of the internal freedom degree molecules_JSubstituting the effective constant pressure heat capacity expression of the hydrogen to obtain a decoupled hydrogen rotation relaxation constant pressure heat capacity expression

Wherein the content of the first and second substances,is the translational heat capacity of the hydrogen,n is 0,1 Λ N, N is the number of single rotation relaxation processes, b_JRepresents p-H₂Or o-H₂The mole fraction occupied.

8. The system for detecting hydrogen gas mixture by using decoupled acoustic relaxation spectrum according to claim 7, wherein the rotational and vibratory mixed relaxation decoupling total model constructing module combines the decoupled rotational relaxation constant pressure heat capacity expression of hydrogen gas with the vibratory relaxation decoupling model to obtain a rotational and vibratory mixed relaxation decoupling total model,

specifically, the hydrogen rotation relaxation constant pressure heat capacity expression is adoptedLinearly combining with the vibration relaxation decoupling model to obtain a rotation and vibration mixed relaxation decoupling total model

Wherein, g_JIs the molar component of the hydrogen gas,is the molar component of the mixed gas except hydrogen,is the external effective heat capacity of the mixed gas except hydrogen,n is 0,1 lambdan, N is the number of single rotation relaxation processes,a_j、respectively represent the respective molar components and the vibrational heat capacity of the mixed gas other than hydrogen,and τ_mRespectively decoupled vibration relaxation processes and corresponding relaxation times, b_JE_JRepresents the contribution of the J-th decoupling process to the isobaric heat capacity.

Technical Field

The invention relates to the technical field of mixed gas detection, in particular to a method and a system for detecting hydrogen mixed gas by utilizing a decoupling acoustic relaxation spectrum.

Background

Hydrogen is an important industrial gas, and many methods for detecting hydrogen are available: the chemical reaction method has short service life; the semiconductor method is single in applicable scene, the sensitivity is greatly changed by the temperature and the humidity of the environment, and the calibration is often needed; the spectroscopic method has high requirements on technology and equipment and high cost; the principle is that the decoupled acoustic relaxation spectrum is utilized to obtain the molecular structure and components of the gas, and then the type and concentration of the hydrogen mixed gas are detected.

Disclosure of Invention

The invention aims to overcome at least one technical defect and provides a method and a system for detecting hydrogen mixed gas by using a decoupling acoustic relaxation spectrum.

In one aspect, the invention provides a method for detecting hydrogen gas mixture by using a decoupled acoustic relaxation spectrum, which comprises the following steps:

obtaining a numerical solution of the number change rate of the internal freedom degree molecules according to a transfer probability equation among the rotation energies of the hydrogen and a hydrogen rotation energy transfer probability matrix, obtaining a decoupled hydrogen rotation relaxation constant pressure heat capacity expression by the numerical solution of the number change rate of the internal freedom degree molecules, and combining the decoupled hydrogen rotation relaxation constant pressure heat capacity expression with a vibration relaxation decoupling model to obtain a rotation and vibration mixed relaxation decoupling total model;

collecting sound velocity and sound relaxation absorption coefficient of sound waves in the mixed gas and pressure and density of the mixed gas;

and obtaining the proportion of the components of the mixed gas according to the sound velocity, the acoustic relaxation absorption coefficient and the pressure and density of the mixed gas, as well as according to an effective thermodynamic sound velocity and effective angular wave number expression, an effective thermodynamic sound velocity square expression of sound waves in gas transmission and a rotation and vibration mixed relaxation decoupling total model.

Further, obtaining a numerical solution of the change rate of the number of molecules of the internal degree of freedom according to a transition probability equation among the rotation energies of the hydrogen and a hydrogen rotation energy transition probability matrix, specifically comprising: equation of transition probability between rotation energies of the hydrogen

Abbreviated (B + I ω I) x ═ D, where x is_J＝dN_J/dT，E is the rotational energy of hydrogen, B is the rotational energy transfer probability matrix, B_IJ＝k_IJ，B_JI＝k_JI，k_JIFor the transition probability between the rotation energies of hydrogen, I is an identity matrix, omega is an angular frequency, I, J represents the number of quanta where the rotation energy level is located, I ≠ J, M is the total number of quanta, T is temperature, N is_I、N_JIs the number of molecules at the rotational energy level;

obtaining a numerical solution of the change rate of the number of the molecules of the internal freedom degree according to the transfer probability equation among the rotation energies of the hydrogen and the hydrogen rotation energy transfer probability matrix B

Wherein, V_Jn、d′_nRespectively, the elements of the matrix V, D, the matrix V is the eigenvector matrix, lambda, of the hydrogen rotational energy transfer probability matrix B_nIs the nth eigenvalue of matrix B.

Further, the numerical solution of the number change rate of the molecules with the internal degree of freedom obtains a decoupled expression of the hydrogen rotational relaxation constant pressure heat capacity, which specifically comprises the following steps:

solving x for the value of the rate of change of the number of molecules of the internal degree of freedom_JSubstituting the effective constant pressure heat capacity expression of the hydrogen to obtain a decoupled hydrogen rotation relaxation constant pressure heat capacity expression

Wherein the content of the first and second substances,is the translational heat capacity of the hydrogen,n is 0,1 Λ N, N is the number of single rotation relaxation processes, b_JRepresents p-H₂，o-H₂The mole fraction occupied.

Further, combining the decoupled hydrogen rotation relaxation constant pressure heat capacity expression with the vibration relaxation decoupling model to obtain a rotation and vibration mixed relaxation decoupling total model, specifically comprising:

rotating relaxation constant pressure heat capacity expression of hydrogenLinearly combining with the vibration relaxation decoupling model to obtain a rotation and vibration mixed relaxation decoupling total model

Wherein, g_JIs the molar component of the hydrogen gas,is the molar component of the mixed gas except hydrogen,is the external effective heat capacity of the mixed gas except hydrogen,n is 0,1 lambdan, N is the number of single rotation relaxation processes,a_j,、respectively represent the respective molar components and the vibrational heat capacity of the mixed gas other than hydrogen,and τ_mRespectively decoupled vibration relaxation processes and corresponding relaxation times, b_JE_JRepresents the contribution of the J-th decoupling process to the isobaric heat capacity.

On the other hand, the invention provides a system for detecting hydrogen mixed gas by using a decoupling acoustic relaxation spectrum, which comprises a rotation and vibration mixed relaxation decoupling total model building module, a data acquisition module and a mixed gas component detection module;

the rotation and vibration mixed relaxation decoupling total model building module is used for obtaining a numerical solution of the number change rate of the internal freedom degree molecules according to a transfer probability equation among the rotation energies of the hydrogen and a hydrogen rotation energy transfer probability matrix, obtaining a decoupled hydrogen rotation relaxation constant pressure heat capacity expression by the numerical solution of the number change rate of the internal freedom degree molecules, and combining the decoupled hydrogen rotation relaxation constant pressure heat capacity expression with a vibration relaxation decoupling model to obtain a rotation and vibration mixed relaxation decoupling total model;

the data acquisition module is used for acquiring the sound velocity, the acoustic relaxation absorption coefficient and the pressure intensity and the density of the mixed gas of the sound wave in the mixed gas;

and the mixed gas component detection module is used for obtaining the proportion of the components of the mixed gas according to the sound velocity, the acoustic relaxation absorption coefficient, the pressure and the density of the mixed gas, and according to a thermodynamic effective sound velocity and effective angular wave number expression, an effective thermodynamic sound velocity square expression of sound waves in gas transmission and a rotation and vibration mixed relaxation decoupling total model.

Further, the rotation and vibration mixed relaxation decoupling total model building module comprises an internal freedom degree molecule number change rate numerical solution obtaining unit,

the internal freedom degree molecule number change rate numerical solution obtaining unit is used for obtaining the numerical solution of the internal freedom degree molecule number change rate according to a transfer probability equation among the rotation energies of the hydrogen and a hydrogen rotation energy transfer probability matrix,

equation of transition probability between rotation energies of the hydrogen

Transformation to (B + I ω I) x ═ D, where x is_J＝dN_J/dT，E is the rotational energy of hydrogen, B is the rotational energy transfer probability matrix, B_IJ＝k_IJ，B_JI＝k_JI，k_JIFor the transition probability between the rotation energies of hydrogen, I is an identity matrix, omega is an angular frequency, I, J represents the number of quanta where the rotation energy level is located, I ≠ J, M is the total number of quanta, T is temperature, N is_I、N_JIs the number of molecules at the rotational energy level;

obtaining a numerical solution of the change rate of the number of the molecules of the internal freedom degree according to the transfer probability equation among the rotation energies of the hydrogen and the hydrogen rotation energy transfer probability matrix B

Wherein, V_Jn、d′_nRespectively, the elements of the matrix V, D, the matrix V is the eigenvector matrix, lambda, of the hydrogen rotational energy transfer probability matrix B_nIs the nth eigenvalue of matrix B.

Further, the rotation and vibration mixed relaxation decoupling total model building module further comprises a hydrogen rotation relaxation constant pressure heat capacity expression obtaining unit,

the hydrogen rotational relaxation constant pressure heat capacity expression obtaining unit is used for obtaining a decoupled hydrogen rotational relaxation constant pressure heat capacity expression according to the numerical solution of the number change rate of the internal freedom degree molecules, and specifically comprises the step of solving the numerical solution x of the number change rate of the internal freedom degree molecules_JSubstituting the effective constant pressure heat capacity expression of the hydrogen to obtain a decoupled hydrogen rotation relaxation constant pressure heat capacity expression

Wherein the content of the first and second substances,is the translational heat capacity of the hydrogen,n is 0,1 Λ N, N is the number of single rotation relaxation processes, b_JRepresents p-H₂Or o-H₂The mole fraction occupied.

Further, the rotation and vibration mixed relaxation decoupling total model building module combines a decoupled hydrogen rotation relaxation constant pressure heat capacity expression with a vibration relaxation decoupling model to obtain a rotation and vibration mixed relaxation decoupling total model,

specifically, the hydrogen rotation relaxation constant pressure heat capacity expression is adoptedLinearly combining with the vibration relaxation decoupling model to obtain a rotation and vibration mixed relaxation decoupling total model

Wherein, g_JIs the molar component of the hydrogen gas,is the molar component of the mixed gas except hydrogen,is the external effective heat capacity of the mixed gas except hydrogen,n is 0,1 lambdan, N is the number of single rotation relaxation processes,a_j、respectively represent the respective molar components and the vibrational heat capacity of the mixed gas other than hydrogen,and τ_mRespectively decoupled vibration relaxation processes and corresponding relaxation times, b_JE_JRepresents the contribution of the J-th decoupling process to the isobaric heat capacity.

Compared with the prior art, the invention has the beneficial effects that: obtaining a numerical solution of the number change rate of the internal freedom degree molecules according to a transfer probability equation among the rotation energies of the hydrogen and a hydrogen rotation energy transfer probability matrix, obtaining a decoupled hydrogen rotation relaxation constant pressure heat capacity expression by the numerical solution of the number change rate of the internal freedom degree molecules, and combining the decoupled hydrogen rotation relaxation constant pressure heat capacity expression with a vibration relaxation decoupling model to obtain a rotation and vibration mixed relaxation decoupling total model; collecting sound velocity, sound relaxation absorption coefficient and pressure and density of sound waves in the mixed gas, and combining a rotation and vibration mixed relaxation decoupling total model to obtain the proportion of the components of the mixed gas; the proportion of detecting the components of the hydrogen mixed gas with higher precision, low cost and low equipment requirement is realized.

Drawings

FIG. 1 is a schematic flow chart of a method for detecting a hydrogen gas mixture by using a decoupled acoustic relaxation spectrum according to embodiment 1 of the present invention;

FIG. 2 is a graph of decoupling results of hydrogen multirotation relaxation as described in example 1 of this invention compared to experimental data;

FIG. 3 is a graph of the decoupling results of the hydrogen multi-rotational relaxation described in example 1 of the present invention compared to experimental data;

FIG. 4 is a graph of the decoupling result of sound velocity dispersion of common hydrogen gas at a temperature of 295K according to example 1 of the present invention;

FIG. 5 is a graph comparing the decoupled prediction of the acoustic absorption spectrum of a gas mixture as described in example 1 of the present invention with experimental data of the prior art;

FIG. 6 shows a gas mixture n-H according to example 1 of the present invention₂-N₂Corresponding dispersion map of sound velocities;

FIG. 7 is a first general model for decoupling rotation and vibration mixed relaxation according to embodiment 1 of the present invention;

FIG. 8 is a second general model for decoupling rotation and vibration mixed relaxation according to embodiment 1 of the present invention;

fig. 9 is a schematic diagram of the intersection point of the two curves of the acoustic relaxation absorption coefficient and the acoustic velocity according to example 1 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.