CN111595910A - Concentration calculation method - Google Patents
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- CN111595910A CN111595910A CN202010300569.5A CN202010300569A CN111595910A CN 111595910 A CN111595910 A CN 111595910A CN 202010300569 A CN202010300569 A CN 202010300569A CN 111595910 A CN111595910 A CN 111595910A
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Abstract
The invention relates to a concentration calculation method, which belongs to the technical field of gas concentration sensing and measurement and control instruments; measuring environmental temperature data and hydrogen concentration data in air; converting the hydrogen concentration data and the environment temperature data into voltage signals, filtering, and sending the filtered hydrogen concentration voltage signals and environment temperature voltage signals to a single chip microcomputer; measuring the data of the hydrogen concentration changing along with the temperature in the mixed gas with different concentration ratios; step four, fitting a temperature compensation coefficient; and sending the temperature compensation coefficient to the single chip microcomputer; displaying the hydrogen concentration percentage corresponding to the hydrogen concentration flow signal according to the fitting temperature compensation coefficient; displaying a temperature value corresponding to the ambient temperature current signal; the invention has wide measuring range, and the highest detection concentration can reach 100 percent; has "broad spectrum" property; the sensitivity is high, and the response time is short; the stability and the reliability are high; simple structure and easy maintenance.
Description
Technical Field
The invention belongs to the technical field of gas concentration sensing and measurement and control instruments, and relates to a concentration calculation method.
Background
The gas concentration sensor is widely used in various industries, most gas alarms adopt electrochemical sensors, but the traditional electrochemical sensors generally have the problems of small detection range of the sensor, cross influence of gas to be detected and zero drift of the sensor. Although other analytical equipment such as a semiconductor gas sensor has high sensitivity, the stability is poor, the working temperature is mostly above 300 ℃, a heating device is needed, and the analytical equipment can only be used as an alarm generally. In contrast, the thermal conductivity sensor has high reliability and simple device, but has a problem that constant temperature detection is required to reduce errors caused by radiation heat dissipation. Therefore, the following problems are prevalent with gas concentration sensors currently on the market:
(1) poor environmental adaptability and the need of a constant temperature or heating device
(2) Detecting the cross influence of single gas and the gas to be detected
(3) The range of measured concentration is small and the response speed is too slow, typically exceeding 20 seconds.
Disclosure of Invention
The technical problem solved by the invention is as follows: the defects of the prior art are overcome, a concentration calculation method is provided, the measurement range is wide, and the highest detection concentration can reach 100%; has "broad spectrum" property; the sensitivity is high, and the response time is short; the stability and the reliability are high; simple structure and easy maintenance.
The technical scheme of the invention is as follows:
a concentration calculation method comprising the steps of:
step one, sprinkling liquid hydrogen on the ground of an outdoor environment to be measured, volatilizing the liquid hydrogen into hydrogen, placing a concentration sensor in the outdoor environment to be measured, and measuring environmental temperature data and hydrogen concentration data in the air;
secondly, the concentration sensor converts the hydrogen concentration data into a voltage signal through a Wheatstone bridge; converting the ambient temperature data into a voltage signal; filtering the hydrogen concentration voltage signal; filtering the ambient temperature voltage signal; sending the filtered hydrogen concentration voltage signal and the filtered ambient temperature voltage signal to a single chip microcomputer;
measuring the data of the hydrogen concentration changing along with the temperature in the mixed gas with different concentration ratios;
step four, fitting a temperature compensation coefficient according to the data of the hydrogen concentration changing along with the temperature; and sending the temperature compensation coefficient to the single chip microcomputer;
step five; the single chip microcomputer converts both the hydrogen concentration voltage signal and the ambient temperature voltage signal into current signals for displaying; displaying the hydrogen concentration percentage corresponding to the hydrogen concentration flow signal according to the fitting temperature compensation coefficient; and displaying the temperature value corresponding to the ambient temperature current signal according to the fitted temperature compensation coefficient.
In the above concentration calculating method, in the first step, the amount of the hydrogen to be sprayed is 0.5 to 2m3(ii) a The outdoor temperature is-20 ℃ to 50 ℃.
In the above concentration calculating method, in the third step, a specific method for measuring the linear data relationship between the hydrogen concentration and the ambient temperature is as follows:
s1, preparing 10 mixed gases of hydrogen and inert gases with different concentration ratios;
s2, filling the mixed gas with one concentration into the test containers respectively, and changing the temperature of the test containers;
and S3, repeating the step two 10 times to obtain the data of the hydrogen concentration in the mixed gas with each concentration ratio along with the temperature change.
In one of the concentration calculation methods described above, in step three, in S1, the concentrations of hydrogen are 0%, 1%, 2%, 4%, 7%, 10.1%, 25.1%, 50.1%, 75.1%, and 100%, respectively.
In one of the concentration calculation methods described above, in step three, S2, the temperature of the test container was changed 8 times in the test in order of-20 ℃, -10 ℃, 0 ℃, 10 ℃, 20 ℃, 30 ℃, 40 ℃ and 50 ℃.
In the above concentration calculation method, in the fourth step, a specific method for fitting the temperature compensation coefficient is as follows:
and fitting the data of the hydrogen concentration changing along with the temperature in the mixed gas with each concentration ratio by adopting a least square method to obtain the temperature compensation coefficients of the hydrogen with different concentration ratios.
In the fifth step of the concentration calculation method, the single chip microcomputer converts both the hydrogen concentration voltage signal and the ambient temperature voltage signal into current signals with current values of 8-20 mA.
In the above concentration calculating method, in the first step, the measurement accuracy of the concentration sensor is 1%; response time is less than 1 second; the temperature compensation range is-20 ℃ to 50 ℃.
Compared with the prior art, the invention has the beneficial effects that:
(1) the method measures the data of the hydrogen concentration changing along with the temperature in the mixed gas with different concentration ratios; fitting a temperature compensation coefficient according to the data of the hydrogen concentration changing along with the temperature; obtaining real temperature-concentration relation data;
(2) the invention adopts a Wheatstone bridge to collect concentration voltage signals, and adjusts the balance resistance to realize linear output under stable excitation voltage;
(3) the invention performs multi-objective optimization of the temperature compensation curve with low linearity and high precision on the acquired temperature concentration relation data. And comparing the performance of the fitting curve of various data relations under the condition of meeting the precision, and simplifying and determining the parameters. And a parameter calibration scheme is designed, so that parameter calibration of a single hydrogen concentration sensor can be realized, and a temperature compensation relation curve of the sensor is determined. And designing a temperature compensation hydrogen concentration detection program to realize the rapid detection and temperature compensation of the hydrogen concentration.
Drawings
FIG. 1 is a flow chart of concentration calculation according to the present invention.
Detailed Description
The invention is further illustrated by the following examples.
The invention provides a concentration calculation method, which can realize effective real-time compensation of ambient temperature and wide-range dynamic measurement of various gas concentrations. The concentration sensor has the following characteristics: the measurement range is wide, and the highest detection concentration can reach 100 percent; the product has "broad spectrum" property, and can detect CH4, H2, CO2, CO, SF6, Xe, He, NH3 and other gases; the sensitivity is high, and the response time is short; the stability and the reliability are high; simple structure and easy maintenance.
The concentration calculation method of the present invention, as shown in fig. 1, specifically includes the following steps:
step one, sprinkling liquid hydrogen on the ground of an outdoor environment to be measured, volatilizing the liquid hydrogen into hydrogen, placing a concentration sensor in the outdoor environment to be measured, and measuring environmental temperature data and hydrogen concentration data in the air; the amount of hydrogen in the sprinkling liquid is 0.5-2m3(ii) a The outdoor temperature is-20 ℃ to 50 ℃. The concentration sensor can condition a wide-range concentration signal up to 100% into a signal meeting the voltage range requirement of a single chip microcomputer acquisition channel through a signal conditioning and amplifying circuit in the concentration acquisition circuit. And the concentration sensor can realize the detection of various gases such as CH4, H2, CO2, CO, SF6, Xe, He, NH3 and the like according to different thermal conductivities. The concentration sensor is a thin film resistor and a thermosensitive temperature compensation resistor based on the thermal conductivity principle, and the resistance values of different resistors are correspondingly changed according to the thermal conductivity of different gases; the bridge and the signal conditioning circuit realize bridge balance under a normal state through a precision balance resistor and a zero setting resistor, change the output voltage of the bridge through the resistance change of the thermal conductivity concentration sensor and amplify and filter signals through the conditioning circuit; the temperature sensor is a PT1000 element, so that sensitive and rapid acquisition of temperature signals can be realized; and the temperature voltage division circuit controls temperature voltage signals at two ends of the PT1000 element to be within the range of an AD acquisition channel of the singlechip through the voltage division circuit under the excitation voltage. The singlechip is used for AD conversion and signal processing; the power supply module is used for supplying power to the singlechip, the operational amplifier and the constant-voltage excitation circuit; the display module is used for displaying the concentration information in real time; and the current or voltage output circuit is connected with the singlechip and is used for conditioning and outputting current or voltage signals. Concentration sensing in the present inventionThe precision of the device during actual measurement can reach 1%, the response time is less than 1 second, and the temperature compensation range is-20 ℃ to 50 ℃.
Secondly, the concentration sensor converts the hydrogen concentration data into a voltage signal through a Wheatstone bridge; converting the ambient temperature data into a voltage signal; filtering the hydrogen concentration voltage signal; filtering the ambient temperature voltage signal; sending the filtered hydrogen concentration voltage signal and the filtered ambient temperature voltage signal to a single chip microcomputer;
measuring the data of the hydrogen concentration changing along with the temperature in the mixed gas with different concentration ratios; the specific method for measuring the linear data relation between the hydrogen concentration and the ambient temperature comprises the following steps:
s1, preparing 10 mixed gases of hydrogen and inert gases with different concentration ratios; the concentration of hydrogen was 0%, 1%, 2%, 4%, 7%, 10.1%, 25.1%, 50.1%, 75.1% and 100%, respectively.
S2, filling the mixed gas with one concentration into the test containers respectively, and changing the temperature of the test containers; in the test, the temperature of the test vessel was changed 8 times in order at-20 deg.C, -10 deg.C, 0 deg.C, 10 deg.C, 20 deg.C, 30 deg.C, 40 deg.C and 50 deg.C, respectively.
And S3, repeating the step two 10 times to obtain the data of the hydrogen concentration in the mixed gas with each concentration ratio along with the temperature change. The thermistor resistance changes differently due to the different thermal conductivity of the measured component and the reference gas, and the bridge circuit outputs concentration voltage signals.
Step four, fitting a temperature compensation coefficient according to the data of the hydrogen concentration changing along with the temperature; the specific method for fitting the temperature compensation coefficient comprises the following steps: and fitting the data of the hydrogen concentration changing along with the temperature in the mixed gas with each concentration ratio by adopting a least square method to obtain the temperature compensation coefficients of the hydrogen with different concentration ratios. And sending the temperature compensation coefficient to the single chip microcomputer;
step five; the single chip microcomputer converts the hydrogen concentration voltage signal and the environment temperature voltage signal into current signals, and the single chip microcomputer converts the hydrogen concentration voltage signal and the environment temperature voltage signal into current signals with current values of 8-20mA and displays the current signals. Displaying the hydrogen concentration percentage corresponding to the hydrogen concentration flow signal according to the fitting temperature compensation coefficient; and displaying the temperature value corresponding to the ambient temperature current signal according to the fitted temperature compensation coefficient.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make variations and modifications of the present invention without departing from the spirit and scope of the present invention by using the methods and technical contents disclosed above.
Claims (8)
1. A concentration calculation method characterized by: the method comprises the following steps:
step one, sprinkling liquid hydrogen on the ground of an outdoor environment to be measured, volatilizing the liquid hydrogen into hydrogen, placing a concentration sensor in the outdoor environment to be measured, and measuring environmental temperature data and hydrogen concentration data in the air;
secondly, the concentration sensor converts the hydrogen concentration data into a voltage signal through a Wheatstone bridge; converting the ambient temperature data into a voltage signal; filtering the hydrogen concentration voltage signal; filtering the ambient temperature voltage signal; sending the filtered hydrogen concentration voltage signal and the filtered ambient temperature voltage signal to a single chip microcomputer;
measuring the data of the hydrogen concentration changing along with the temperature in the mixed gas with different concentration ratios;
step four, fitting a temperature compensation coefficient according to the data of the hydrogen concentration changing along with the temperature; and sending the temperature compensation coefficient to the single chip microcomputer;
step five; the single chip microcomputer converts both the hydrogen concentration voltage signal and the ambient temperature voltage signal into current signals for displaying; displaying the hydrogen concentration percentage corresponding to the hydrogen concentration flow signal according to the fitting temperature compensation coefficient; and displaying the temperature value corresponding to the ambient temperature current signal according to the fitted temperature compensation coefficient.
2. A concentration calculation method according to claim 1, wherein: in the first step, the amount of the sprayed liquid hydrogen is 0.5-2m3(ii) a The outdoor temperature is-20 ℃ to 50 ℃.
3. A concentration calculation method according to claim 2, wherein: in the third step, a specific method for measuring the linear data relation between the hydrogen concentration and the ambient temperature is as follows:
s1, preparing 10 mixed gases of hydrogen and inert gases with different concentration ratios;
s2, filling the mixed gas with one concentration into the test containers respectively, and changing the temperature of the test containers;
and S3, repeating the step two 10 times to obtain the data of the hydrogen concentration in the mixed gas with each concentration ratio along with the temperature change.
4. A concentration calculation method according to claim 3, wherein: in step three, the concentration of hydrogen in S1 was 0%, 1%, 2%, 4%, 7%, 10.1%, 25.1%, 50.1%, 75.1% and 100%, respectively.
5. The concentration calculation method according to claim 4, wherein: in step three, S2, the temperature of the test container is changed for 8 times in sequence, namely-20 deg.C, -10 deg.C, 0 deg.C, 10 deg.C, 20 deg.C, 30 deg.C, 40 deg.C and 50 deg.C.
6. A concentration calculation method according to claim 5, wherein: in the fourth step, a specific method for fitting the temperature compensation coefficient is as follows:
and fitting the data of the hydrogen concentration changing along with the temperature in the mixed gas with each concentration ratio by adopting a least square method to obtain the temperature compensation coefficients of the hydrogen with different concentration ratios.
7. A concentration calculation method according to claim 6, wherein: in the fifth step, the single chip microcomputer converts both the hydrogen concentration voltage signal and the ambient temperature voltage signal into current signals with current values of 8-20 mA.
8. A concentration calculation method according to claim 7, wherein: in the first step, the measurement precision of the concentration sensor is 1%; response time is less than 1 second; the temperature compensation range is-20 ℃ to 50 ℃.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112326882A (en) * | 2020-10-22 | 2021-02-05 | 深圳市汇投智控科技有限公司 | Air quality sensor processing method and device |
| CN114034746A (en) * | 2021-11-11 | 2022-02-11 | 中煤科工集团重庆研究院有限公司 | Intelligent carbon monoxide sensor and detection method |
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Cited By (3)
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