CN115468925A - Construction method, detection method and device of non-dispersive infrared detection carbon dioxide concentration model - Google Patents
Construction method, detection method and device of non-dispersive infrared detection carbon dioxide concentration model Download PDFInfo
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Abstract
The invention relates to a construction method of a non-dispersive infrared detection carbon dioxide concentration model, which comprises the following steps: for m known concentrations are respectively C 1 、C 2 823060 m Respectively acquiring corresponding sets of voltage signal values and detection temperatures at n different set temperatures: { (AD) 11 /T 11 、AD 21 /T 21 ……AD m1 /T m1 )、(AD 12 /T 12 、AD 22 /T 22 ……AD m2 /T m2 )……(AD 1n /T 1n 、AD 2n /T 2n ……AD mn /T mn ) }; temperature intervals are formed by adjacent set temperatures, and the voltage signal change rate K of each concentration standard sample in each temperature interval is calculated pq ＝(AD pq ‑AD p(q‑1) )/(T pq ‑T p(q‑1) ) (ii) a K calculated from various concentration standards in various temperature intervals pq As ordinate, in AD pq For lying onPerforming unitary quadratic fitting to respectively obtain temperature compensation relational expressions in each temperature interval; for set temperature t i Respective concentration standards of p As ordinate, with AD pi Performing linear fitting for abscissa, selecting at least two points in each linear fitting, and respectively obtaining j fitting linear equations y = e ij *x+f ij And the AD value interval used when each fitted linear equation is fitted.
Description
Technical Field
The invention relates to the technical field of infrared sensors, in particular to a construction method, a detection method and a device of a non-dispersive infrared carbon dioxide concentration detection model.
Background
With the continuous development of scientific technology, the increasing improvement of the living standard of people and the increasing attention of people on environmental protection, the compact quantitative monitoring and control of carbon dioxide gas becomes an increasing demand. The infrared carbon dioxide sensor adopts a broad-spectrum light source, and light rays penetrate through a measured gas in a light path, penetrate through the narrow-band filter and reach the infrared detector. In the detection process, the concentration value of the carbon dioxide can be calculated by recording the measured value of the infrared detector and then utilizing the relation between the gas concentration and the absorption intensity. However, because the infrared carbon dioxide sensor is prone to temperature drift and is greatly influenced by time and environment, the traditional infrared carbon dioxide concentration detection model is low in calculation accuracy, prone to false alarm and requiring frequent calibration.
Therefore, a method for constructing a non-dispersive infrared carbon dioxide concentration detection model capable of improving calculation accuracy is needed.
Disclosure of Invention
Based on the above, one of the purposes of the present application is to provide a method for constructing a non-dispersive infrared detection carbon dioxide concentration model, which can improve the calculation accuracy.
The method for constructing the non-dispersive infrared detection carbon dioxide concentration model provided by the embodiment of the application comprises the following steps:
for m known concentrations are respectively C 1 、C 2 823060 +8230and C m Respectively acquiring corresponding sets of voltage signal values and detection temperatures at n different set temperatures: { (AD) 11 /T 11 、AD 21 /T 21 ……AD m1 /T m1 )、(AD 12 /T 12 、AD 22 /T 22 ……AD m2 /T m2 )……(AD 1n /T 1n 、AD 2n /T 2n ……AD mn /T mn ) Where AD is a voltage signal value, T is a detected temperature, m and n are each independently a positive integer greater than 1, and "/" represents a correspondence;
temperature intervals are formed by adjacent set temperatures, and the voltage signal change rate K of each concentration standard sample in each temperature interval is calculated according to the following formula pq ：
K pq ＝(AD pq -AD p(q-1) )/(T pq -T p(q-1) )；
Wherein p is a positive integer from 1 to m, and q is a positive integer from 2 to n;
k calculated from each concentration standard sample in each temperature interval pq As ordinate, in AD pq And (3) carrying out unary quadratic fitting for the abscissa to respectively obtain temperature compensation relational expressions in each temperature interval:
F(x)＝a q *x^2+b q *x+c q ；
for set temperature t i Respective concentration standards of p As ordinate, in AD pi Performing linear fitting for abscissa, selecting at least two points in each linear fitting, and respectively obtaining j fitting linear equations y = e ij *x+f ij And AD value intervals used in fitting of all fitting linear equations, wherein i is a positive integer from 1 to n, and j is a positive integer from 1 to (m-1);
preferably, the set temperature t i It was 25 ℃.
In one embodiment, m is a positive integer > 2;
preferably, j is a positive integer ≧ 2;
more preferably, j is a positive integer ≧ 5.
In one embodiment, the set temperature t i The corresponding AD value intervals of the following different fitting linear equations are not overlapped or share endpoints;
preferably, two of the points are selected for each linear fit, with the ordinates of the two points adjacent.
In one embodiment, the n different set temperatures include a high temperature, a second low temperature, and a low temperature, which are sequentially decreased in temperature and do not exceed a maximum temperature point of the non-dispersive infrared detection device.
In one embodiment, the different concentration carbon dioxide standards do not contain a blank sample with a carbon dioxide concentration of 0 ppm;
optionally, the different concentration carbon dioxide standards comprise a zero point sample having a carbon dioxide concentration of 500 ppm.
Still another objective of the present application is to provide a method for detecting carbon dioxide concentration by non-dispersive infrared detection, wherein the model is constructed by using the above construction method, and the method comprises the following steps:
obtaining the voltage signal value AD of the detected sample to be detected To be measured And detecting the temperature T To be measured ；
According to the detected temperature T To be measured In the temperature interval, the temperature compensation relational expression F (x) = a is selected q *x^2+b q *x+c q Will AD To be measured Substituting as x to calculate F (x), i.e., K Compensation ；
Selecting the set temperature t from the set temperatures at two endpoints of the temperature interval i Closer endpoint set temperature T Setting up According to formula K Compensating for ＝(AD To be measured -AD Setting up )/(T To be measured -T Setting up ) Calculating to obtain AD Setting up ；
If T is Setting up Not at the set temperature t i Then continue to compensate the relation and formula K according to the temperature pq ＝(AD pq -AD p(q-1) )/(T pq -T p(q-1) ) Calculating until T is obtained Setting up For the set temperature t i Time of day voltage signal value AD i ；
At the set temperature t i The AD value interval used in the fitting is selected from the following fitting straight lines to cover AD i Fitting equation of straight line of (1), AD i Substituting x into the fitted linear equation to calculate the measurement of the sample to be measuredAnd (4) concentration.
It is another object of the present application to provide a device for constructing a non-dispersive infrared carbon dioxide concentration model, including:
a standard sample data acquisition module for respectively obtaining C for m known concentrations 1 、C 2 823060 m Respectively acquiring corresponding sets of voltage signal values and detection temperatures at n different set temperatures: { (AD) 11 /T 11 、AD 21 /T 21 ……AD m1 /T m1 )、(AD 12 /T 12 、AD 22 /T 22 ……AD m2 /T m2 )……(AD 1n /T 1n 、AD 2n /T 2n ……AD mn /T mn ) Where AD is a voltage signal value, T is a detected temperature, m and n are each independently a positive integer greater than 1, and "/" represents a correspondence;
a change rate calculation module for forming temperature intervals by adjacent set temperatures and calculating the voltage signal change rate K of each concentration standard sample in each temperature interval according to the following formula pq ：
K pq ＝(AD pq -AD p(q-1) )/(T pq -T p(q-1) )；
Wherein p is a positive integer of 1-m, and q is a positive integer of 2-n;
a temperature compensation calculation module for calculating K in each temperature interval by using each concentration standard sample pq As ordinate, in AD pq And (3) carrying out unary quadratic fitting for the abscissa to respectively obtain temperature compensation relational expressions in each temperature interval:
F(x)＝a q *x^2+b q *x+c q ；
a linear fitting module for fitting the set temperature t i Respective concentration standards of p As ordinate, in AD pi Performing linear fitting for abscissa, selecting at least two points in each linear fitting, and respectively obtaining j fitting linear equations y = e ij *x+f ij And the AD value interval used in the fitting of each fitted linear equation, whichWherein i is a positive integer of 1 to n, and j is a positive integer of 1 to (m-1);
preferably, the set temperature t i It was 25 ℃.
It is another object of the present application to provide a non-dispersive infrared detection apparatus for detecting carbon dioxide concentration, the model constructed by the above construction method, the detection apparatus comprising:
a detection data acquisition module for acquiring the voltage signal value AD of the sample to be detected To be measured And detecting the temperature T To be measured ；
A compensation calculation module for calculating the compensation value according to the detected temperature T To be measured In the temperature interval, the temperature compensation relational expression F (x) = a is selected q *x^2+b q *x+c q Will AD To be measured Substituting as x to calculate F (x), i.e., K Compensation ；
A set voltage signal value calculation module for selecting the set temperature t from the two end set temperatures of the temperature interval i Closer endpoint set temperature T Setting up According to formula K Compensation ＝(AD To be measured -AD Setting up )/(T To be measured -T Setting up ) Calculating to obtain AD Setting up ；
If T is Setting up Not at the set temperature t i Then continue to compensate the relation and formula K according to the temperature pq ＝(AD pq -AD p(q-1) )/(T pq -T p(q-1) ) Calculating until T is obtained Setting up For the set temperature t i Time of day voltage signal value AD i ；
At the set temperature t i The AD value interval used in the fitting is selected from the following fitting straight lines to cover AD i Fitting a linear equation of (A) to (D) i Substituting the x into the fitted linear equation to calculate the measured concentration of the sample to be measured.
It is a further object of the present application to provide a computer device comprising a memory storing a computer program and a processor implementing all the steps of the above construction method or the above detection method when the processor executes the computer program.
It is a further object of the present application to provide a computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out all the steps of the above-mentioned construction method or the above-mentioned detection method.
The construction method of the non-dispersive infrared carbon dioxide concentration detection model divides the temperature into a plurality of intervals, respectively calculates the temperature compensation of each temperature interval, compensates the temperature compensation to the actually measured voltage signal value in the form of the voltage signal value, and then calculates the carbon dioxide concentration by taking the compensated voltage signal value as an input value. The temperature compensation method comprises the steps of respectively fitting the change rate and the compensation signal value of each interval to obtain a first-order quadratic polynomial, and obtaining the R of the model 2 Compared with the traditional Lambert beer linear fitting, the method is closer to 1, the calculation precision is higher, and the fault tolerance rate is higher. When the voltage signal value and the carbon dioxide concentration value are subjected to linear fitting, the voltage signal value is divided into a plurality of intervals, and sectional fitting is performed, so that the method is more targeted, errors can be further reduced, and the precision is improved.
The model constructed by the construction method does not need to measure the absorption rate under 0ppm, and can take the signal AD value of 500ppm as a zero point, thereby being convenient for detection.
Drawings
FIG. 1 is a diagram illustrating a fitting curve and a temperature compensation relationship within a temperature interval;
FIG. 2 is a schematic of a fitted line and fitted line equation at 25 ℃.
Detailed Description
In order that the invention may be more fully understood, reference will now be made to the following more detailed description. The following is a description of preferred embodiments of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
The Non-dispersive Infrared (NDIR) technology is a spectrum gas detection method based on a gas absorption theory. The principle is as follows: after infrared radiation emitted by the infrared light source is absorbed by gas with a certain concentration to be measured, the light intensity on a specific wavelength changes correspondingly to the gas concentration, and the change rule can be described by the Lambert-beer absorption law. Therefore, the gas concentration can be obtained according to the light intensity change.
The NDIR carbon dioxide sensor is based on the principle that the absorption of carbon dioxide molecules to specific wavelengths is detected, and the concentration of carbon dioxide is calculated according to the measured absorption intensity and the Lambert-beer absorption theorem. The NDIR detector comprises the following components: the infrared light source emits infrared rays with specific wavelength ranges, and the detector only receives infrared spectral lines with specific wavelengths through the optical filter. The infrared light source and the detector are arranged in the air chamber, the air chamber is provided with the temperature sensor and the incubator, the temperature sensor is used for collecting actual detection temperature, and comprehensive compensation is carried out on the output result of the NDIR sensor, so that the final output measurement value of the sensor is closer to a true value, and the accuracy and precision of the measurement data of the sensor are improved.
Residual sum of squares R 2 Is a physical quantity that measures the degree of fit of a model in a linear model. Statistically, the difference between a data point and its corresponding position on the regression line is called residual, and the sum of the squares of each residual is called the sum of the squares of the residuals, which is equivalent to the sum of the squares of the differences between the actual value and the predicted value.
The temperature drift refers to the change of parameters of the semiconductor device caused by the temperature change, is a main reason for generating zero drift, and is called temperature drift for short.
An embodiment of the application provides a method for constructing a non-dispersive infrared detection carbon dioxide concentration model, which comprises the following steps:
step S110: for m piecesKnown concentrations are respectively C 1 、C 2 823060 m Respectively acquiring corresponding sets of voltage signal values and detection temperatures at n different set temperatures: { (AD) 11 /T 11 、AD 21 /T 21 ……AD m1 /T m1 )、(AD 12 /T 12 、AD 22 /T 22 ……AD m2 /T m2 )……(AD 1n /T 1n 、AD 2n /T 2n ……AD mn /T mn ) Where AD is a voltage signal value, T is a detected temperature, m and n are each independently a positive integer greater than 1, and "/" represents a correspondence;
step S120: temperature intervals are formed by adjacent set temperatures, and the voltage signal change rate K of each concentration standard sample in each temperature interval is calculated according to the following formula pq ：
K pq ＝(AD pq -AD p(q-1) )/(T pq -T p(q-1) )；
Wherein p is a positive integer of 1-m, and q is a positive integer of 2-n;
step S130: k calculated from various concentration standards in various temperature intervals pq As ordinate, in AD pq And (3) carrying out unary quadratic fitting for the abscissa to respectively obtain temperature compensation relational expressions in each temperature interval:
F(x)＝a q *x^2+b q *x+c q ；
step S140: for set temperature t i Respective concentration standards of p As ordinate, in AD pi Performing linear fitting for abscissa, selecting at least two points in each linear fitting, and respectively obtaining j fitting linear equations y = e ij *x+f ij And an AD value interval used when each fitting linear equation is fitted, wherein i is a positive integer from 1 to n, and j is a positive integer from 1 to (m-1).
In one example, m is a positive integer > 2.
Preferably, j is a positive integer ≧ 2.
More preferably, j is a positive integer ≧ 5.
In one example, the set temperature t i The temperature was 25 ℃.
In one example, the set temperature t i The corresponding AD value intervals of the following different fitting linear equations are not overlapped or share endpoints.
Preferably, two of the points are selected for each linear fit, with the ordinates of the two points adjacent.
In one example, the n different set temperatures include a high temperature, a second low temperature, and a low temperature, which are sequentially decreased in temperature, and which do not exceed a maximum temperature point of the non-dispersive infrared detection device.
In one example, the different concentration carbon dioxide standards do not contain a blank sample with a carbon dioxide concentration of 0 ppm.
Optionally, the different concentration carbon dioxide standards comprise a zero sample with a carbon dioxide concentration of 500 ppm.
The following describes a method for constructing a model for detecting carbon dioxide concentration by non-dispersive infrared detection with reference to a specific example.
Step S210: controlling the temperature of the incubator of the sensor to a high temperature TT 1 6 carbon dioxide samples with known concentrations of PPM1 and PPM2, 8230, 8230and PPM6 with different concentrations are respectively introduced into the incubator, and a set of signal values of the sensor corresponding to the detection temperature is respectively recorded, wherein the set is AD1/T1, AD2/T2, 8230, 8230and AD6/T6 shown in the following table 1.
Step S220: respectively controlling the temperature of the incubator of the sensor at a sub-high temperature TT 2 Sub-low temperature TT 3 And cryogenic temperature TT 4 In step S210, the sets of signal values of the sensors corresponding to the detected temperatures are recorded, respectively, as shown in Table 1 below, AD7/T7, AD8/T8 \8230, and AD24/T24.
TABLE 1
Step S230: formed by adjacent set temperatures (TT) 4 ～TT 3 )、(TT 3 ～TT 2 ) And (TT) 2 ～TT 1 ) Three temperature intervals, and calculating the voltage signal change rate K of each concentration standard sample in each temperature interval according to the following formula pq ：
K pq ＝(AD pq -AD p(q-1) )/(T pq -T p(q-1) )；
For example, (TT 2 ～TT 1 ) Within a temperature interval, the voltage signal change rate K of the carbon dioxide standard sample with the concentration of PPM1 PPM1-(TT2～TT1) ＝(AD1-AD7)/(T1-T7)。
Step S240: k calculated from each concentration standard sample in step S230 in each temperature interval pq As ordinate, in AD pq And (3) carrying out unary quadratic fitting for the abscissa to respectively obtain temperature compensation relational expressions in each temperature interval:
F(x)＝a q *x^2+b q *x+c q ；
for example, (TT) 2 ～TT 1 ) The fitting curve and the temperature compensation relation in the temperature interval are shown in FIG. 1, wherein the temperature compensation relation is F (x) = a (TT2～TT1) *x^2+b (TT2～TT1) *x+c (TT2～TT1) 。
Step S250: to TT 2 Concentrations at temperature, as C p As ordinate, in AD p-TT2 For the abscissa, linear fitting is performed, at least two points of which are selected for each linear fitting, at TT 2 J fitting linear equations y = e respectively obtained at temperature TT2-j *x+f TT2-j And the AD value interval used when each fitted linear equation is fitted.
For example, signal values AD7, AD8, 8230 \ 8230 @, and AD12 are abscissa values, and concentration values PPM1, PPM2, 8230 \ 8230 @, and PPM6 are ordinate values, the signal values and the corresponding concentration values are divided into 5 segments, and each segment is fitted separately to obtain 5 fitting straight lines, which are shown in fig. 2.
Another embodiment of the present application further provides a method for detecting carbon dioxide concentration by using non-dispersive infrared detection, where the model is constructed by using the above model construction method, and the method includes the following steps:
step S310: obtaining the voltage signal value AD of the detected sample to be detected To be measured And detecting the temperature T To be measured 。
Step S320: according to the detected temperature T To be measured In the temperature interval, the temperature compensation relational expression F (x) = a is selected q *x^2+b q *x+c q Will AD To be measured Substituting as x to calculate F (x), i.e., K Compensation 。
Step S330: selecting the set temperature t from the two end set temperatures in the temperature interval i Closer endpoint set temperature T Setting up According to the formula K Compensation ＝(AD To be measured -AD Setting up )/(T To be measured -T Setting up ) Calculating to obtain AD Setting up ；
If T is Setting up Not at said set temperature t i Then continue to compensate the relation and formula K according to the temperature pq ＝(AD pq -AD p(q-1) )/(T pq -T p(q-1) ) Calculating until T is obtained Setting up For the set temperature t i Time of day voltage signal value AD i 。
Step S340: at the set temperature t i The AD value interval used in the fitting is selected from the following fitting straight lines to cover AD i Fitting equation of straight line of (1), AD i Substituting the x into the fitted linear equation to calculate the measured concentration of the sample to be measured.
Further, another embodiment of the present application provides an apparatus for constructing a non-dispersive infrared carbon dioxide concentration detection model, where the apparatus may adopt a software module or a hardware module, or a combination of the two modules to form a part of a computer device, and the apparatus specifically includes:
a standard sample data acquisition module for respectively obtaining C for m known concentrations 1 、C 2 823060 +8230and C m Respectively acquiring corresponding sets of voltage signal values and detection temperatures at n different set temperatures: { (AD) 11 /T 11 、AD 21 /T 21 ……AD m1 /T m1 )、(AD 12 /T 12 、AD 22 /T 22 ……AD m2 /T m2 )……(AD 1n /T 1n 、AD 2n /T 2n ……AD mn /T mn ) Where AD is a voltage signal value, T is a detected temperature, m and n are each independently a positive integer greater than 1, "/" denotes a corresponding relationship;
a change rate calculation module for forming temperature intervals with adjacent set temperatures and calculating the voltage signal change rate K of each concentration standard sample in each temperature interval according to the following formula pq ：
K pq ＝(AD pq -AD p(q-1) )/(T pq -T p(q-1) )
Wherein p is a positive integer from 1 to m, and q is a positive integer from 2 to n;
a temperature compensation calculation module for calculating K in each temperature interval by using each concentration standard sample pq As ordinate, in AD pq And (3) carrying out unary quadratic fitting for the abscissa to respectively obtain temperature compensation relational expressions in each temperature interval:
F(x)＝a q *x^2+b q *x+c q ；
a linear fitting module for fitting the set temperature t i Respective concentration standards of p As ordinate, in AD pi Performing linear fitting for abscissa, selecting at least two points in each linear fitting, and respectively obtaining j fitting linear equations y = e ij *x+f ij And AD value intervals used in fitting of all fitting linear equations, wherein i is a positive integer from 1 to n, and j is a positive integer from 1 to (m-1);
preferably, the set temperature t i The temperature was 25 ℃.
Still further, another embodiment of the present application provides a non-dispersive infrared detection apparatus for detecting carbon dioxide concentration, wherein a model constructed by using the above model construction method may be a software module or a hardware module, or a combination of the two modules, which is a part of a computer device, and the detection apparatus includes:
a detection data acquisition module for acquiring the voltage signal value AD of the detected sample To be measured And detecting the temperature T To be measured ；
A compensation calculation module for calculating the compensation value according to the detected temperature T To be measured In the temperature interval, the temperature compensation relational expression F (x) = a is selected q *x^2+b q *x+c q Will AD To be measured Substituting as x to calculate F (x), i.e., K Compensating for ；
A set voltage signal value calculation module for selecting the set temperature t from the two end set temperatures of the temperature interval i Closer endpoint set temperature T Setting up According to formula K Compensation ＝(AD To be measured -AD Setting up )/(T To be measured -T Setting up ) Calculating to obtain AD Setting up ；
If T is Setting up Not at the set temperature t i Then continue to compensate the relation and formula K according to the temperature pq ＝(AD pq -AD p(q-1) )/(T pq -T p(q-1) ) Calculating until T is obtained Setting up For the set temperature t i Time of day voltage signal value AD i ；
At the set temperature t i The AD value interval used in the fitting is selected from the following fitting straight lines to cover AD i Fitting equation of straight line of (1), AD i Substituting the x into the fitted linear equation to calculate the measured concentration of the sample to be measured.
For specific limitations of the non-dispersive infrared detection carbon dioxide concentration model construction device and the non-dispersive infrared detection carbon dioxide concentration detection device, reference may be made to the above limitations of the non-dispersive infrared detection carbon dioxide concentration model construction method and the non-dispersive infrared detection carbon dioxide concentration detection method, and details are not repeated here. The building device of the non-dispersive infrared detection carbon dioxide concentration model and each module in the non-dispersive infrared detection carbon dioxide concentration detection device can be completely or partially realized by software, hardware and a combination thereof. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.
Yet another embodiment of the present application provides a computer device, including a memory and a processor, where the memory stores a computer program, and the processor implements all the steps of the above construction method or the above detection method when executing the computer program.
Yet another embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored, which when executed by a processor implements all the steps of the above-mentioned construction method or the above-mentioned detection method.
Yet another embodiment of the present application provides a computer program product comprising a computer program which, when being executed by a processor, carries out all the steps of the above construction method or the above detection method.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above may be implemented by hardware instructions of a computer program, which may be stored in a non-volatile computer-readable storage medium, and when executed, may include the processes of the embodiments of the methods described above. Any reference to memory, storage, database or other medium used in the embodiments provided herein can include at least one of non-volatile and volatile memory. Non-volatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical Memory, or the like. Volatile Memory can include Random Access Memory (RAM) or external cache Memory. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM), among others.
The following are specific examples.
Step S410: the temperature of the incubator of the sensor is controlled to be 55 ℃ at the maximum, 6 carbon dioxide standard samples with known concentrations of PPM1, PPM2 \8230, 8230and PPM6 are respectively introduced into the incubator, and corresponding sets of signal values and detection temperatures of the sensor are respectively recorded, as shown in the following table 1.
Step S420: the oven temperatures of the sensors were controlled at-10 deg.C, 5 deg.C and 25 deg.C, respectively, and the step S410 was repeated to record sets of signal values of the sensors corresponding to the detected temperatures, respectively, as shown in Table 2 below.
TABLE 2
Step S430: three temperature intervals of (-10 ℃ to 5 ℃), (5 ℃ to 25 ℃) and (25 ℃ to 55 ℃) are formed by adjacent set temperatures, and the voltage signal change rate K of each concentration standard sample in each temperature interval is calculated according to the following formula pq As shown in table 3 below:
K pq ＝(AD pq -AD p(q-1) )/(T pq -T p(q-1) )；
for example, the voltage signal change rate K of a carbon dioxide standard sample with a concentration of 500ppm at a temperature range of (25 ℃ to 55 ℃), is 500ppm-(25℃～55℃) ＝(28200-28822)/(55.5-27.3)＝-22.0567375886525。
TABLE 3
Step S440: k calculated by each concentration standard sample in step S430 in each temperature interval pq As ordinate, with AD pq And (3) carrying out unary quadratic fitting for the abscissa to respectively obtain temperature compensation relational expressions in each temperature interval:
F(x)＝a q *x^2+b q *x+c q ；
the temperature compensation relations in the temperature ranges of (55-25 ℃), (25-5 ℃) and (5-10 ℃) are respectively as follows:
K (25℃～55℃) ＝-0.000000061620x 2 +0.003189605033x-63.116300981062；
K (25℃～5℃) ＝-0.000000149919x 2 +0.008494403490x-160.330702002065；
K (5℃～-10℃) ＝-0.000000367292x 2 +0.022128252112x-367.578994303053。
step S450: taking signal values 28822, 27353, 26009, 23699, 21891 and 20120 at 25 ℃ as abscissas, concentration values 500ppm, 1000ppm, 1500ppm, 2500ppm, 3500ppm and 5000ppm as ordinates, dividing the signal values and the corresponding concentration values into 5 sections, and respectively fitting each section to obtain 5 fitting straight lines:
(28822 to 27353) segment: y = -0.340367597005x +10310.074880871300;
(27353-26009) paragraph: y = -0.372023809524x +11175.967261904800;
paragraphs (26009 to 23699): y = -0.432900432900x +12759.307359307400;
(23699 to 21891) section: y = -0.553097345133x +15607.853982300900;
(sections 21891 to 20120): y = -0.846979107849x +22041.219649915300.
And (3) verifying the accuracy of the non-dispersive infrared detection carbon dioxide concentration detection method of the model constructed by using the model construction method by using the carbon dioxide with the concentration of 1429ppm as a sample to be detected.
The detection method comprises the following steps:
step S510: obtaining the voltage signal value AD of the detected sample to be detected To be measured 26877 and detecting the temperature T To be measured The temperature was 8.2 ℃.
Step S520: according to the temperature range (25-5 ℃) of the detection temperature of 8.2 ℃, selecting a temperature compensation relational expression:
K (25℃～5℃) ＝-0.000000149919x 2 +0.008494403490x-160.330702002065, and D To be measured =26877 doCalculate F (x), i.e., K, for x substitution Compensating for It was-40.32407653.
Step S530: setting 25 ℃ to T Setting up According to the formula K Compensating for ＝(AD To be measured -AD Setting up )/(T To be measured -T Setting up ) Calculating to obtain AD Setting up 26106.81014;
step S540: the AD value interval used in selecting the fitting among a plurality of fitting straight lines at 25 ℃ covers AD Setting up Is fitted to the equation of a straight line, i.e.
(27353-26009) paragraph: y = -0.372023809524x +11175.967261904800;
will AD Setting up And substituting the fitted linear equation with the value of =26106.81014 as x to calculate the measured concentration y =1463.6123ppm of the sample to be measured. The error from its actual concentration of 1429ppm is in the range of + (+ -50 ppm + 5%).
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be understood as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A construction method of a non-dispersive infrared detection carbon dioxide concentration model is characterized by comprising the following steps:
for m known concentrations are respectively C 1 、C 2 823060 m Respectively acquiring corresponding sets of voltage signal values and detection temperatures at n different set temperatures: { (AD) 11 /T 11 、AD 21 /T 21 ……AD m1 /T m1 )、(AD 12 /T 12 、AD 22 /T 22 ……AD m2 /T m2 )……(AD 1n /T 1n 、AD 2n /T 2n ……AD mn /T mn ) Where AD is a voltage signal value, T is a detected temperature, m and n are each independently a positive integer greater than 1, and "/" represents a correspondence;
temperature intervals are formed by adjacent set temperatures, and the voltage signal change rate K of each concentration standard sample in each temperature interval is calculated according to the following formula pq ：
K pq ＝(AD pq -AD p(q-1) )/(T pq -T p(q-1) )
Wherein p is a positive integer of 1-m, and q is a positive integer of 2-n;
k calculated from various concentration standards in various temperature intervals pq As ordinate, with AD pq And (3) carrying out unary quadratic fitting for the abscissa to respectively obtain temperature compensation relational expressions in each temperature interval:
F(x)＝a q *x^2+b q *x+c q ；
for set temperature t i Respective concentration standards of p As ordinate, with AD pi Performing linear fitting for abscissa, selecting at least two points in each linear fitting, and respectively obtaining j fitting linear equations y = e ij *x+f ij And AD value intervals used in fitting of all fitting linear equations, wherein i is a positive integer from 1 to n, and j is a positive integer from 1 to (m-1);
preferably, the set temperature t i The temperature was 25 ℃.
2. The method for constructing a model for non-dispersive infrared detection of carbon dioxide concentration according to claim 1, wherein m is a positive integer > 2;
preferably, j is a positive integer ≧ 2;
more preferably, j is a positive integer ≧ 5.
3. The method for constructing a model for non-dispersive infrared detection of carbon dioxide concentration according to claim 2, wherein the set temperature t is i The corresponding AD value intervals of the following different fitting linear equations are not overlapped or share endpoints;
preferably, two of the points are selected for each linear fit, with the ordinates of the two points adjacent.
4. The method of claim 1, wherein the n different set temperatures include a high temperature, a low temperature, a sub-high temperature, a sub-low temperature, and a low temperature, which are sequentially decreased in temperature and do not exceed a maximum temperature point of the non-dispersive infrared detection device.
5. The method for constructing a model for non-dispersive infrared detection of carbon dioxide concentration according to any one of claims 1 to 4, wherein the carbon dioxide standard samples with different concentrations do not contain a blank sample with carbon dioxide concentration of 0 ppm;
optionally, the different concentration carbon dioxide standards comprise a zero sample with a carbon dioxide concentration of 500 ppm.
6. A non-dispersive infrared detection method for detecting the concentration of carbon dioxide, which is characterized in that a model is constructed by the construction method of any one of claims 1 to 5, and the detection method comprises the following steps:
obtaining the voltage signal value AD of the detected sample to be detected To be measured And detecting the temperature T To be measured ；
According to said detected temperature T To be measured In the temperature interval, the temperature compensation relational expression F (x) = a is selected q *x^2+b q *x+c q Will AD To be measured Substituting as x to calculate F (x), i.e., K Compensating for ；
Selecting the set temperature t from the set temperatures at two endpoints of the temperature interval i Closer endpoint set temperature T Setting up According to the formula K Compensating for ＝(AD To be measured -AD Setting up )/(T To be measured -T Setting up ) Calculating to obtain AD Setting up ；
If T is Setting up Not at the set temperature t i Then continue to compensate the relation and formula K according to the temperature pq ＝(AD pq -AD p(q-1) )/(T pq -T p(q-1) ) Calculating until T is obtained Setting up For the set temperature t i Time of day voltage signal value AD i ；
At the set temperature t i The AD value interval used in the fitting is selected from the following fitting straight lines to cover AD i Fitting equation of straight line of (1), AD i Substituting the x into the fitted linear equation to calculate the measured concentration of the sample to be measured.
7. A construction device of a non-dispersive infrared detection carbon dioxide concentration model is characterized by comprising the following components:
a standard sample data acquisition module for respectively obtaining C for m known concentrations 1 、C 2 823060 m Respectively acquiring corresponding sets of voltage signal values and detection temperatures at n different set temperatures: { (AD) 11 /T 11 、AD 21 /T 21 ……AD m1 /T m1 )、(AD 12 /T 12 、AD 22 /T 22 ……AD m2 /T m2 )……(AD 1n /T 1n 、AD 2n /T 2n ……AD mn /T mn ) Where AD is a voltage signal value, T is a detected temperature, m and n are each independently a positive integer greater than 1, and "/" represents a correspondence;
a change rate calculation module for forming temperature intervals by adjacent set temperatures and calculating the voltage signal change rate K of each concentration standard sample in each temperature interval according to the following formula pq ：
K pq ＝(AD pq -AD p(q-1) )/(T pq -T p(q-1) )；
Wherein p is a positive integer of 1-m, and q is a positive integer of 2-n;
a temperature compensation calculation module for calculating K in each temperature interval by using each concentration standard sample pq As ordinate, with AD pq And (3) carrying out unary quadratic fitting for the abscissa to respectively obtain temperature compensation relational expressions in each temperature interval:
F(x)＝a q *x^2+b q *x+c q ；
a linear fitting module for fitting the set temperature t i Respective concentration standards of p As ordinate, in AD pi Performing linear fitting for abscissa, selecting at least two points in each linear fitting, and respectively obtaining j fitting linear equations y = e ij *x+f ij And AD value intervals used in fitting of all fitting linear equations, wherein i is a positive integer from 1 to n, and j is a positive integer from 1 to (m-1);
preferably, the set temperature t i The temperature was 25 ℃.
8. A detection apparatus for detecting carbon dioxide concentration by non-dispersive infrared detection, wherein a model is constructed by the construction method according to any one of claims 1 to 5, the detection apparatus comprises:
a detection data acquisition module for acquiring the voltage signal value AD of the sample to be detected To be measured And detecting the temperature T To be measured ；
A compensation calculation module for calculating the compensation value according to the detected temperature T To be measured In the temperature interval, the temperature compensation relational expression F (x) = a is selected q *x^2+b q *x+c q Will AD To be measured Substituting as x to calculate F (x), i.e., K Compensating for ；
A set voltage signal value calculation module for selecting the set temperature t from the two end set temperatures of the temperature interval i Closer endpoint set temperature T Setting up According to formula K Compensation ＝(AD To be measured -AD Setting up )/(T To be measured -T Setting up ) Calculating to obtain AD Setting up ；
If T is Setting up Is not at homeThe set temperature t i Then continue to compensate the relation and formula K according to the temperature pq ＝(AD pq -AD p(q-1) )/(T pq -T p(q-1) ) Calculating until T Setting up For the set temperature t i The voltage signal value of time is AD i ；
A concentration calculation module for calculating the concentration at the set temperature t i The AD value interval used in the fitting is selected from the following fitting straight lines to cover AD i Fitting a linear equation of (A) to (D) i Substituting the x into the fitted linear equation to calculate the measured concentration of the sample to be measured.
9. A computer device comprising a memory and a processor, the memory storing a computer program, wherein the processor when executing the computer program implements all the steps of the construction method of any one of claims 1 to 5 or the detection method of claim 6.
10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out all the steps of the construction method according to any one of claims 1 to 5 or the detection method according to claim 6.
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| CN116952884B (en) * | 2023-06-25 | 2024-03-15 | 青岛崂应海纳光电环保集团有限公司 | Gas concentration calculation method for non-dispersive infrared gas detection |
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