Multi-component gas flux analysis system and time delay determination method

Abstract

The invention relates to a multi-component gas flux analysis system and a time delay determination method. The method comprises the following steps: controlling a first light source and a second light source to respectively emit first laser with a first wavelength and second laser with a second wavelength; the first laser is reflected between a first reflecting mirror and a second reflecting mirror of the open absorption cell for multiple times to obtain first emergent light, and the second laser is reflected between the first reflecting mirror and the second reflecting mirror for multiple times to obtain second emergent light; target gas passes between the first reflecting mirror and the second reflecting mirror, and the target gas comprises first gas and second gas which are different from each other; converting the first emergent light into a first electric signal; converting the second emergent light into a second electric signal; a first time delay is obtained based on the first electrical signal, a second time delay is obtained at least based on the second electrical signal, and the second time delay is corrected based on the first time delay. By adopting the method, the time calibration error in the vorticity flux calculation process can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of laser spectroscopy gas detection, and particularly to a multi-component gas flux analysis system and a time delay determination method. Background Art

[0002] Monitoring the concentration data of greenhouse gases such as ammonia, methane, nitrous oxide, and carbon monoxide in the atmosphere is widely used in industrial production and the agricultural field. The emissions of greenhouse gases have an important impact on global climate change. By monitoring the emissions of greenhouse gases, we can understand the greenhouse gas emissions in different industries and regions, providing a basis for formulating emission reduction measures. In addition, the monitoring can also measure the effectiveness of emission reduction measures and help evaluate the potential impact of global warming on the environment and human health.

[0003] Since some greenhouse gases are soluble in water or easily adsorbed on the inner wall of the pipeline, it poses a challenge to the accuracy of gas concentration data detection. And because the closed-loop pipeline gas transmission detection cannot detect the gas concentration in real time, the open pipeline is a better choice. However, how to obtain the time delay of the gas with a low concentration in the atmosphere is an urgent problem to be solved. Summary of the Invention

[0004] Based on this, in view of the above technical problems, it is necessary to provide a component gas flux analysis system and a time delay determination method that can accurately obtain the time delay data of greenhouse gases with low concentrations in the atmosphere.

[0005] In a first aspect, the present application provides a multi-component gas flux analysis system, including: a first light source for emitting a first laser with a first wavelength; a second light source for emitting a second laser with a second wavelength; an open absorption cell including a first reflector and a second reflector; the target gas in the open absorption cell passes between the first reflector and the second reflector; the target gas in the open absorption cell includes two different first gases and second gases; the first laser is reflected multiple times between the first reflector and the second reflector to obtain a first outgoing light, and the second laser is reflected multiple times between the first reflector and the second reflector to obtain a second outgoing light; a first end face with the first reflector disposed on the first end face; a second end face with the second reflector disposed on the second end face, and the first end face and the second end face are connected by a support frame; a first detector for receiving the first outgoing light and converting the received first outgoing light into a first electrical signal; a second detector for receiving the second outgoing light and converting the received second outgoing light into a second electrical signal; there is an electrical signal stronger than the second electrical signal in the first electrical signal; a data processor for obtaining a first time delay based on the first electrical signal, obtaining at least a second time delay based on the second electrical signal, and correcting the second time delay based on the first time delay.

[0006] In one embodiment, the first mirror includes a first concave mirror, and the second mirror includes a second concave mirror; the first concave mirror includes a first light inlet, a first light outlet, a second light inlet, and a second light outlet; the first laser is incident on the open absorption cell through the first light inlet, and after being reflected multiple times between the first concave mirror and the second concave mirror, it exits through the first light outlet to obtain a first output light, and the second laser is incident on the open absorption cell through the second light inlet, and after being reflected multiple times between the first concave mirror and the second concave mirror, it exits through the second light outlet to obtain a second output light;

[0007] The first wavelength of the first laser is a wavelength having an absorption peak for water or a wavelength having an absorption peak for methane; the first gas includes water and methane;

[0008] The second wavelength of the second laser is a wavelength having an absorption peak for ammonia, and the second gas includes ammonia; or

[0009] The second wavelength of the second laser is a wavelength having an absorption peak for nitrous oxide, and the second gas includes nitrous oxide; or

[0010] The second wavelength of the second laser is a wavelength having an absorption peak for carbon monoxide, and the second gas includes carbon monoxide.

[0011] In one embodiment, the data processor: obtains a reference signal and an average reference signal; the average reference signal is the average signal of a predetermined number of detections of the reference signal; generates a first average electrical signal based on the first electrical signal; the first average electrical signal is the average signal of a predetermined number of detections of the first electrical signal; generates a second average electrical signal based on the second electrical signal; the second average electrical signal is the average signal of a predetermined number of detections of the second electrical signal; generates first time-delay covariances with different time delays based on the reference signal, the average reference signal, the first electrical signal, and the first average electrical signal; generates second time-delay covariances with different time delays based on the reference signal, the average reference signal, the second electrical signal, and the second average electrical signal; generates a maximum first time-delay covariance based on the first time-delay covariances with different time delays, and the time delay corresponding to the maximum first time-delay covariance is the first time delay; generates a maximum second time-delay covariance based on the second time-delay covariances with different time delays, and the time delay corresponding to the maximum second time-delay covariance is the second time delay; corrects the second time delay based on the first time delay.

[0012] In one embodiment, a data processor: obtains the molar mass of air, the molar mass of a target gas, the air density, the vertical wind pulsation, and the target gas mixing ratio pulsation; obtains first spectral information based on a first electrical signal and second spectral information based on a second electrical signal; obtains the concentration of the target gas passing through an open absorption cell from the first spectral information and the second spectral information; obtains the mixing ratio of a first gas and a second gas based on the concentration of the target gas; and obtains the flux of the target gas based on the molar mass of air, the molar mass of the target gas, the air density, the vertical wind pulsation, the target gas mixing ratio pulsation, and the mixing ratio of the first gas and the second gas.

[0013] In one embodiment, the reflected light spot of the first laser on the first mirror forms a first circle, and the reflected light spot of the second laser on the first mirror forms a second circle, and the first circle and the second circle are concentric circles.

[0014] In one embodiment, the multi-component gas flux analysis system further includes a mirror cleaner disposed on one side of the reflecting surface of the second mirror. The mirror cleaner includes: a first connector for receiving a third gas; a second connector for receiving a liquid; a cavity disposed around the second mirror, and a plurality of spray holes are provided on the outer wall of the cavity; the cavity is connected to the first connector to receive the third gas input through the first connector, and the cavity is further connected to the second connector to receive the liquid input through the second connector; wherein the fluid formed after the third gas and the liquid are mixed in the cavity is ejected through the plurality of spray holes; the plurality of spray holes are arranged on the outer wall of the cavity at equal intervals from each other, and the fluid formed after the third gas and the liquid are mixed in the cavity is ejected obliquely from the spray holes; a through hole is provided in the middle of the second mirror, and the fluid is discharged through the through hole; the cavity is provided as a hollow body; and a heater is provided on the side opposite to the reflecting surface of the second mirror.

[0015] In one embodiment, the multi-component gas flux analysis system further includes a brush cleaner disposed on one side of the reflecting surface of the second mirror. The brush cleaner includes:

[0016] A protective cover disposed on the brush cleaner;

[0017] The brush cleaner, and the brush of the brush cleaner is in contact with the reflecting surface of the second mirror.

[0018] In a second aspect, the present application provides a method for determining the time delay of a multi-component gas flux analysis system, including:

[0019] Control the first light source to emit first laser light with a first wavelength; control the second light source to emit second laser light with a second wavelength; the first laser light is reflected multiple times between the first mirror of the open absorption cell and the second mirror of the open absorption cell to obtain first output light, and the second laser light is reflected multiple times between the first mirror and the second mirror to obtain second output light; wherein the target gas passes between the first mirror and the second mirror, and the target gas includes a first gas and a second gas that are different from each other.

[0020] Control the first detector to receive the first output light and convert the received first output light into a first electrical signal; control the second detector to receive the second output light and convert the received second output light into a second electrical signal; there is an electrical signal in the first electrical signal that is stronger than the second electrical signal.

[0021] Control the data processor to obtain a first time delay based on the first electrical signal, obtain a second time delay at least based on the second electrical signal, and correct the second time delay based on the first time delay.

[0022] In one embodiment, controlling the data processor to obtain a first time delay based on the first electrical signal, obtain a second time delay at least based on the second electrical signal, and correct the second time delay based on the first time delay includes:

[0023] Obtain a reference signal and an average reference signal; the average reference signal is the average signal of a predetermined number of detections of the reference signal.

[0024] Generate a first average electrical signal based on the first electrical signal; the first average electrical signal is the average signal of a predetermined number of detections of the first electrical signal; generate a second average electrical signal based on the second electrical signal; the second average electrical signal is the average signal of a predetermined number of detections of the second electrical signal.

[0025] Generate first time delay covariances with different time delays based on the reference signal, the average reference signal, the first electrical signal, and the first average electrical signal.

[0026] Generate second time delay covariances with different time delays based on the reference signal, the average reference signal, the second electrical signal, and the second average electrical signal.

[0027] Generate a maximum first time delay covariance based on the first time delay covariances with different time delays, and the time delay corresponding to the maximum first time delay covariance is the first time delay; generate a maximum second time delay covariance based on the second time delay covariances with different time delays, and the time delay corresponding to the maximum second time delay covariance is the second time delay.

[0028] Correct the second time delay based on the first time delay.

[0029] In one embodiment, the method further includes:

[0030] Obtaining the molar mass of air, the molar mass of the target gas, the air density, the vertical wind pulsation, and the target gas mixing ratio pulsation;

[0031] Obtaining first spectral information based on the first electrical signal and obtaining second spectral information based on the second electrical signal;

[0032] Obtaining the concentration of the target gas passing through the open absorption cell from the first spectral information and the second spectral information;

[0033] Obtaining the mixing ratio of the target gas based on the concentration of the target gas;

[0034] Obtaining the flux of the target gas based on the molar mass of air, the molar mass of the target gas, the air density, the vertical wind pulsation, the target gas mixing ratio pulsation, and the mixing ratio of the target gas; the first wavelength of the first laser is a wavelength having an absorption peak for water or an absorption peak for methane; the first gas includes water and methane.

[0035] The above multi-component gas flux analysis system and time delay determination method include a first light source for emitting a first laser having a first wavelength; a second light source for emitting a second laser having a second wavelength; and an open absorption cell including a first mirror and a second mirror; the target gas in the open absorption cell passes between the first mirror and the second mirror; the target gas in the open absorption cell includes two different first gases and second gases; the first laser is reflected multiple times between the first mirror and the second mirror to obtain a first outgoing light, and the second laser is reflected multiple times between the first mirror and the second mirror to obtain a second outgoing light; it further includes a first detector for receiving the first outgoing light and converting the received first outgoing light into a first electrical signal, and a second detector for receiving the second outgoing light and converting the received second outgoing light into a second electrical signal; and a data processor. By obtaining a first time delay based on the first electrical signal, obtaining a second time delay at least based on the second electrical signal, where the first electrical signal is stronger than the second electrical signal, and correcting the second time delay based on the first time delay, it is possible to accurately obtain the time delay data of greenhouse gases with a lower concentration in the atmosphere, thereby reducing the time calibration error in the vorticity flux calculation process of the multi-component gas flux analysis system. Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments or related technologies. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0037] Figure 1 Schematic diagram of the brief principle of the multi-component gas flux analysis system in one embodiment;

[0038] Figure 2 Schematic diagram of the structure of the multi-component gas flux analysis system in one embodiment;

[0039] Figure 3 Schematic diagram of the structure of the multi-component gas flux analysis system in another embodiment;

[0040] Figure 4 Distribution diagram of the light spot on the first mirror and four through holes in one embodiment;

[0041] Figure 5 Distribution diagram of the light spot of the second mirror in one embodiment;

[0042] Figure 6 Comparison diagram of the wind speed covariance of low-signal-intensity gas (methane) and high-signal-intensity gas (water);

[0043] Figure 7 Schematic diagram of the absorption intensity of each gas at different wavelengths;

[0044] Figure 8 Simulation absorption data results of methane and water;

[0045] Figure 9 Simulation absorption data results of ammonia;

[0046] Figure 10 Simulation absorption data results of nitrous oxide and carbon monoxide;

[0047] Figure 11 Schematic diagram of the structure of the mirror cleaner of the multi-component gas flux analysis system in one embodiment of the present application;

[0048] Figure 12 Schematic diagram of the cavity spray hole structure in one embodiment of the present application;

[0049] Figure 13 Schematic diagram of the structure of the brush cleaner in one embodiment of the present application;

[0050] Figure 14 Schematic diagram of the flow of the method for determining the time delay of the multi-component gas flux analysis system in one embodiment of the present application;

[0051] Figure 15 Schematic diagram of the flow of the method for determining the time delay of the multi-component gas flux analysis system in another embodiment of the present application.

[0052] 101. Open absorption cell; 201. First light source; 202. Second light source; 203. First detector; 204. Second detector; 1011. First reflector; 1012. Second reflector; 206. Support frame; 2011. First laser; 2012. Third reflector; 2021. Second laser; 2022. Fourth reflector; 205. First off-axis mirror; 206. Second off-axis mirror; 102. Reflection end; 103. Emission end; 104. Data processor; 10111. First light inlet; 10112. First light outlet; 10113. Second light inlet; 10114. Second light outlet; 10115. Light spot; 105. First end face; 106. Second end face; 1061. Cavity; 1062. First joint; 1063. Second joint; 10121. Through hole; 10611. Spray hole; 107. Brush cleaner; 1071. Protective cover; 1072. Brush cleaner. Detailed implementation manners

[0053] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following describes the detailed implementation manners of the present invention with reference to the accompanying drawings. Many specific details are set forth in the following description to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein. Those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0054] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0055] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0056] In the present invention, unless otherwise clearly defined or limited, terms such as "installed", "connected", "linked", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal connection of two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0057] In the present invention, unless otherwise clearly defined or limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature is at a higher level than the second feature in terms of horizontal height. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature is at a lower level than the second feature in terms of horizontal height.

[0058] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it may be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation.

[0059] Refer to Figure 1 and Figure 2 , Figure 1 which is a schematic diagram of the brief principle of a multi-component gas flux analysis system in an embodiment of the present invention. Figure 2The structural schematic diagram of a multi-component gas flux analysis system in an embodiment of the present invention is shown. An embodiment of the present invention provides a multi-component gas flux analysis system, including a first light source 201 for emitting a first laser with a first wavelength; a second light source 202 for emitting a second laser with a second wavelength; an open absorption cell 101, including a first reflector 1011 and a second reflector 1012; the target gas in the open absorption cell 101 passes between the first reflector 1011 and the second reflector 1012; the target gas in the open absorption cell 101 includes two different first gases and second gases; the first laser is reflected multiple times between the first reflector 1011 and the second reflector 1012 to obtain a first output light, and the second laser is reflected multiple times between the first reflector 1011 and the second reflector 1012 to obtain a second output light; a first end face 105, the first reflector 1011 is disposed on the first end face 105; a second end face 106, the second reflector 1012 is disposed on the second end face 106, and the first end face 105 and the second end face 106 are connected by a support frame 206; a first detector 203 for receiving the first output light and converting the received first output light into a first electrical signal; a second detector 204 for receiving the second output light and converting the received second output light into a second electrical signal; there is an electrical signal in the first electrical signal that is stronger than the second electrical signal; a data processor 104 for obtaining a first time delay based on the first electrical signal, obtaining at least a second time delay based on the second electrical signal, and correcting the second time delay based on the first time delay.

[0060] Wherein, the first light source 201 includes: a first laser 2011 and a third reflector 2012, the first laser emitted by the first laser 2011 is incident on the third reflector 2012 and is reflected by the third reflector 2012 to the open absorption cell 101; and the second light source 202 includes: a second laser 2021 and a fourth reflector 2022, the second laser emitted by the second laser 2021 is incident on the fourth reflector 2022 and is reflected by the fourth reflector 2022 into the open absorption cell 101.

[0061] The first laser 2011 or the second laser 2021 can be a quantum cascade laser (Quantum Cascade Lasers, QCL).

[0062] The open absorption cell 101 can be an open Herriott cell. A Herriott cell generally refers to a closed gas absorption cell, which is an optical multipass cell and has important applications in fields such as spectroscopy. The Herriott cell mainly works based on the principle of optical reflection. Its core structure includes two oppositely placed mirrors. When a beam of light enters the Herriott cell from a specific position, the light will be reflected multiple times between the two mirrors. By reasonably designing the incident position and angle of the light, the light can be made to reflect multiple times in the cell along a specific path, thereby increasing the interaction length between the light and the medium (such as gas) in the cell. The open Herriott cell is an optical multipass cell after improving the structure of the closed Herriott cell. Different from the closed Herriott cell, the open Herriott cell does not have a completely closed outer shell, allowing gases or samples in the external environment to directly enter the optical path region, and this design enables the gas exchange to be more rapid.

[0063] The multi-component gas flux analysis system provided by an embodiment of this application, which can also be called a multi-component laser open-path gas flux analysis instrument, has a schematic diagram of its brief principle as shown in Figure 1 shown.

[0064] As Figure 1 shown, the light from the first laser 2011 and the second laser 2021, for example, two quantum cascade lasers, emits from the emission end 103, passes through the open absorption cell 101, for example, an open Herriott cell, and is reflected multiple times between the emission end 103 and the reflection end 102, and then emits from the emission end 103, and after being reflected by, for example, a lens to the detector, high-precision data on the absorption of each gas concentration in the open environment is obtained. Among them, the emission end 103 and the reflection end 102 can be located on the same side of the open absorption cell 101 or on the opposite sides of the open absorption cell 101.

[0065] Exemplarily, the two sets of laser components and the detector components are all fixed to the emission end 103. Among them, the first laser 2011 emits the first laser with the first wavelength, and the light is injected into the first detector 203 through multiple reflections along the inner ring optical path of the open absorption cell 101; the second laser 2021 emits the second laser with the second wavelength, and the light is injected into the second detector 204 through multiple reflections along the outer ring optical path of the Herriott cell, as shown in Figure 2 shown. Optionally, the first detector 203 and the second detector 204 can be MCT (Mercury Cadmium Telluride) detectors. The multi-component gas flux analysis system processes the signals obtained in the first detector 203 and the second detector 204 to obtain the concentration data of each component gas.

[0066] Since some greenhouse gases dissolve in water or are easily adsorbed on the inner wall of pipelines, it poses challenges to the accuracy of gas concentration data detection. And because the closed-loop pipeline gas transmission detection cannot detect the gas concentration in real time, the present application adopts an open structure and a dual-laser dual-optical path system, which can simultaneously detect multiple greenhouse gases in real time and provides an integrated detection solution for greenhouse gases such as ammonia, methane, nitrous oxide, and carbon monoxide.

[0067] To obtain an open environment, the multi-component gas flux analysis system further includes a first end face 105 and a second end face 106. The first reflector 1011 is disposed on the first end face 105, and the second reflector 1012 is disposed on the second end face 106. The first end face 105 and the second end face 106 are connected by a support frame 206, so as to form an open environment between the first reflector 1011 and the second reflector 1012, and the gas to be measured in the open environment can flow freely.

[0068] At the same time, in order to accurately obtain the time delay data of greenhouse gases with relatively low concentrations in the atmosphere, the multi-component gas flux analysis system proposed in the present application can correct the time delay of weak signal gases through a time calibration method, that is, multiple gas components can correct the time delay of weak signal gases through the time delay of strong signal gases, thereby reducing the error of time calibration in the process of eddy flux calculation.

[0069] In the present application, the first detector 203 receives the first outgoing light and converts the received first outgoing light into a first electrical signal; the second detector 204 receives the second outgoing light and converts the received second outgoing light into a second electrical signal; and there is an electrical signal in the first electrical signal that is stronger than the second electrical signal. In some cases, the second electrical signal is the signal of a weak signal gas, and the first electrical signal includes the signal of a strong signal gas. Exemplarily, the target gases in the open absorption cell 101 include two different first gases and second gases, where the first gas includes a strong signal gas and the second gas is a weak signal gas. The first laser and the second laser are incident on the first gas and the second gas in the open absorption cell 101, so as to carry the information of the first gas and the second gas when exiting the open absorption cell 101, obtaining the first outgoing light and the second outgoing light, and thus there is also an electrical signal in the first electrical signal converted from the first outgoing light that is stronger than the electrical signal converted from the second outgoing light. Thus, a first time delay can be obtained based on the first electrical signal, a second time delay can be obtained at least based on the second electrical signal, and the second time delay can be corrected based on the first time delay.

[0070] The above multi-component gas flux analysis system has an open environment detection structure, which can detect the concentration data of various gases in the atmosphere in real time and obtain more accurate detection results for gases that are easily adsorbed on the inner wall of the pipeline. The dual-laser and dual-light-path structure of the system can synchronously detect multi-component gases. Based on the absorption relationships of different gases under different wavelength lasers, the gas concentrations of ammonia, methane, water or nitrous oxide, carbon monoxide, methane, and water can be detected simultaneously. By obtaining a first time delay based on a first electrical signal and at least a second time delay based on a second electrical signal, where there is an electrical signal stronger than the second electrical signal in the first electrical signal, and correcting the second time delay based on the first time delay, the time delay data of greenhouse gases with lower concentrations in the atmosphere can be accurately obtained, thereby reducing the time calibration error in the process of vorticity flux calculation of the multi-component gas flux analysis system. And by determining the proportional relationship of ammonia, methane or nitrous oxide, carbon monoxide, methane based on the detected multi-component gas concentration data, the types of pollution sources can be evaluated.

[0071] In an exemplary embodiment, the first mirror 1011 includes a first concave mirror, and the second mirror 1012 includes a second concave mirror; the first concave mirror includes a first light inlet 10111, a first light outlet 10112, a second light inlet 10113, and a second light outlet 10114; the first laser is incident on the open absorption cell 101 through the first light inlet 10111, and after being reflected multiple times between the first concave mirror and the second concave mirror, it exits through the first light outlet 10112 to obtain a first output light. The second laser is incident on the open absorption cell 101 through the second light inlet 10113, and after being reflected multiple times between the first concave mirror and the second concave mirror, it exits through the second light outlet 10114 to obtain a second output light.

[0072] In an exemplary embodiment, as Figure 3As shown, in the multi-component gas flux analysis system, the first laser 2011 and the second laser 2021 emit light under the control of the system's drive circuit, and the laser beams are reflected by the third mirror 2012 and the fourth mirror 2022 respectively into the open absorption cell 101. The open absorption cell 101 is equipped with two concave mirrors, namely the first concave mirror and the second concave mirror. The surfaces of the first concave mirror and the second concave mirror are treated with a high-hardness coating. After the light beam is reflected multiple times, it exits through the opening of the first concave mirror. Among them, the first laser enters the open absorption cell 101 through the first light inlet 10111, is reflected multiple times between the first concave mirror and the second concave mirror, and then exits through the first light outlet 10112 to obtain the first output light. The second laser enters the open absorption cell 101 through the second light inlet 10113, is reflected multiple times between the first concave mirror and the second concave mirror, and then exits through the second light outlet 10114 to obtain the second output light. The first output light and the second output light are reflected by the first off-axis mirror 205 and the second off-axis mirror 206 respectively to the first detector 203 and the second detector 204. Among them, the first off-axis mirror 205 and the second off-axis mirror 206 can be off-axis parabolic mirrors. The multi-component gas flux analysis system processes the signals obtained by the detectors to obtain the concentration data of each component gas. The temperatures of the first laser 2011, the second laser 2021, the first detector 203, and the second detector 204 are all stabilized by thermoelectric coolers (TECs). Optionally, in order to improve the performance of TEC control, each TEC is connected to a heat dissipation cold water row, and the heat dissipation cold water rows are connected in series and combined with a compact external chiller.

[0073] In one embodiment, the first mirror 1011 and the second mirror 1012 are coaxially symmetrically arranged; the first mirror 1011 and the second mirror 1012 have the same focal length.

[0074] Exemplarily, an optical simulation software is used to design the optical path. The first concave mirror and the second concave mirror of the open absorption cell 101 are coaxially symmetrically placed, and the light beam enters from the first concave mirror. Let the light beam incident point be (x0, y0); after n reflections, the position of the light spot 10115 is (x n , y n ); the incident angle is (x0’, y0’); the first mirror 1011 and the second mirror 1012 have the same focal length, both set to f, and the distance between the first mirror 1011 and the second mirror 1012 is d; when the first laser is reflected between the first concave mirror and the second concave mirror, the angle between two consecutive reflected light spots 10115 is θ. Then their corresponding relationship is:

[0075] x n= A sin(nθ + α) (1)

[0076] y n = B sin(nθ + β) (2)

[0077] Wherein,

[0078]

[0079] In an exemplary embodiment, the reflected light spot 10115 of the first laser on the first reflector 1011 forms a first circle, and the reflected light spot 10115 of the second laser on the first reflector 1011 forms a second circle, and the first circle and the second circle are concentric circles.

[0080] Generally, when the laser is incident into the open absorption cell according to the relationships of formulas (1) to (6), the light spots 10115 shown on the first concave mirror and the second concave mirror are distributed in an irregular shape. When A = B and α = β ± (π / 2) are satisfied simultaneously, the distribution pattern of the light spots 10115 on the static surfaces of the first concave mirror and the second concave mirror presents a circular shape.

[0081] For the multi-component gas flux analysis system provided by the present application, when designing the structural optical path and assembling and debugging, a mirror holder for adjusting the incident angle is designed to ensure that the light spot 10115 is adjusted to a circular distribution pattern.

[0082] In one embodiment, the distance between the first reflector 1011 and the second reflector 1012 is less than four times the focal length.

[0083] When the distance d between the first reflector 1011 and the second reflector 1012 is less than four times the spherical focal length f of the reflector, the incident light can be reflected multiple times between the mirror surfaces of the first reflector 1011 and the second reflector 1012 without overflowing the chamber.

[0084] In one embodiment, the multi-component gas flux analysis system provided by the present application selects the outer diameter of the light spot 10115 to be 44 mm, the inner diameter to be 32 mm, the distance between the first reflector 1011 and the second reflector 1012 to be 264.5 mm, and the focal lengths of the first reflector 1011 and the second reflector 1012, i.e., the spherical focal lengths, to be 250 mm. After multiple reflections, both the first optical path and the second optical path are more than 10 meters to ensure obtaining stronger absorption concentration data, where the first optical path is the optical path formed before the first laser is reflected multiple times between the first reflector 1011 and the second reflector 1012 and exits; the second optical path is the optical path formed before the second laser is reflected multiple times between the first reflector 1011 and the second reflector 1012 and exits. In one embodiment, please refer to Figure 4 and Figure 5 , Figure 4It is a distribution diagram of the light spot 10115 and four through holes 10121 on the first reflector 1011. Figure 5 It is a distribution diagram of the light spot 10115 of the second reflector 1012. As Figure 4 shown, it is a distribution diagram of the light spot 10115 and four through holes 10121 on the first reflector 1011 in an embodiment. The first reflector 1011 is arranged at the transmitting end 103. The relatively large circles on the first reflector 1011 respectively represent the first light inlet 10111, the first light outlet 10112, the second light inlet 10113 and the second light outlet 10114, and the relatively small circles represent the light spot 10115. The first light inlet 10111, the first light outlet 10112, the second light inlet 10113 and the second light outlet 10114 are all through holes 10121. Exemplarily, the first light inlet 10111, the first light outlet 10112, the second light inlet 10113 and the second light outlet 10114 are set as circular through holes 10121. Please refer to Figure 5 , Figure 5 It is a distribution diagram of the light spot 10115 of the second reflector 1012 in an embodiment. There are no through holes 10121 provided on the second reflector 1012, and the second reflector 1012 only provides a reflection function. The reflected light spot 10115 of the first laser on the first reflector 1011 forms a first circle, and the reflected light spot 10115 of the second laser on the first reflector 1011 forms a second circle. The first circle and the second circle are concentric circles.

[0085] In an exemplary embodiment, the data processor:

[0086] Obtains a reference signal and an average reference signal; the average reference signal is the average signal of a predetermined number of detections of the reference signal. Generates a first average electrical signal based on the first electrical signal; the first average electrical signal is the average signal of a predetermined number of detections of the first electrical signal; generates a second average electrical signal based on the second electrical signal; the second average electrical signal is the average signal of a predetermined number of detections of the second electrical signal. Generates first time-delay covariances with different time delays based on the reference signal, the average reference signal, the first electrical signal, and the first average electrical signal. Generates second time-delay covariances with different time delays based on the reference signal, the average reference signal, the second electrical signal, and the second average electrical signal. Generates a maximum first time-delay covariance based on the first time-delay covariances with different time delays, and the time delay corresponding to the maximum first time-delay covariance is the first time delay; generates a maximum second time-delay covariance based on the second time-delay covariances with different time delays, and the time delay corresponding to the maximum second time-delay covariance is the second time delay. Corrects the second time delay based on the first time delay.

[0087] Exemplarily, in the flux observation site, there is a spatial distance between the multi-component gas flux analysis system of the present application and other instruments for obtaining gas information. This will result in the data collected by different instruments at the same time being difficult to represent the real turbulent change in the time domain. Therefore, it is necessary to use the maximum covariance method to correct the time delay between the multi-component gas flux analysis system and other instruments.

[0088] The covariance formula for calculating different time delays τ is:

[0089]

[0090] where x(t) and y(t) are the signals of the multi-component gas flux analysis system and other instruments for obtaining gas information respectively, and are the means of the signals, and N is the number of data points. Calculate the time delay τ that maximizes the covariance Cov(τ) max , then τ is the time delay between the two signals.

[0091] Exemplarily, for different gases, calculate the covariance at different time delays τ:

[0092]

[0093] where x1(t) represents the first electrical signal, and the first average electrical signal is generated based on the first electrical signal x1(t) Specifically, the first average electrical signal is obtained by averaging the first electrical signal for a predetermined number of detections. The first average electrical signal is the average signal of the first electrical signal for the predetermined number of detections. x2(t) represents the second electrical signal, and the second average electrical signal is generated based on the second electrical signal x2(t) Specifically, the second average electrical signal is obtained by averaging the second electrical signal for a predetermined number of detections. The second average electrical signal is the average signal of the second electrical signal for the predetermined number of detections. y(t) represents the reference signal, and the average reference signal is generated based on the reference signal y(t) Specifically, the average reference signal is obtained by averaging the reference signal for a predetermined number of detections. The average reference signal is the average signal of the reference signal for the predetermined number of detections. N is the number of data points, that is, the predetermined number of detections.

[0094] According to formula (8), generate the first time-delay covariance with different time delays based on the reference signal, the average reference signal, the first electrical signal, and the first average electrical signal. According to formula (9), generate the second time-delay covariance with different time delays based on the reference signal, the average reference signal, the second electrical signal, and the second average electrical signal.

[0095] Based on Equation (8), different time delays τ1 are taken, and the maximum first-time-delay covariance is generated based on the first-time-delay covariances with different time delays. The time delay corresponding to the maximum first-time-delay covariance is the first time delay τ. 1max , it can be understood that τ 1max is the time delay of the multi-component gas flux analysis system based on the detected first gas relative to other instruments for obtaining gas information. Based on Equation (9), different time delays τ2 are taken, and the maximum second-time-delay covariance is generated based on the second-time-delay covariances with different time delays. 2max , and the time delay corresponding to the maximum second-time-delay covariance is the second time delay. It can be understood that τ 2max is the time delay of the multi-component gas flux analysis system based on the detected second gas relative to other instruments for obtaining gas information. The second time delay is corrected based on the first time delay.

[0096] For the above multi-component gas flux analysis system, the first time delay is obtained based on the first electrical signal, and the second time delay is obtained based on at least the second electrical signal, where there is an electrical signal in the first electrical signal that is stronger than the second electrical signal, and the second time delay is corrected based on the first time delay, so as to accurately obtain the time delay data of greenhouse gases with lower concentrations in the atmosphere, thereby reducing the time calibration error in the process of eddy flux calculation of the multi-component gas flux analysis system.

[0097] In one embodiment, the data processor 104 includes an ultrasonic anemometer, and a reference signal and an average reference signal are obtained through the ultrasonic anemometer.

[0098] In one embodiment, the first wavelength of the first laser is a wavelength with an absorption peak for water or a wavelength with an absorption peak for methane; the first gas includes water and methane.

[0099] To reduce the time calibration error in the process of eddy flux calculation, the time delay of the multi-component gas can be corrected by the time delay of the strong-signal gas water in the first gas for the time delay of the weak-signal gas such as the second gas, such as correcting the time delay of ammonia by the water vapor time delay.

[0100] The time delay of the multi-component gas flux analysis system of the present application relative to other instruments for obtaining gas information is generally in the range of -1.5 s to 1.5 s. However, for trace gases, it is difficult to find an obvious signal peak within the time range under low signal intensity conditions, and using the maximum covariance method to correct the time delay of the multi-component gas flux analysis system will result in a relatively large numerical value of the flux calculation result. For example Figure 6The figure shows a comparison chart of the wind speed covariance of low-signal-intensity gas (methane) and the wind speed covariance of high-signal-intensity gas (water). In the figure, obvious peaks can be observed in the covariance results of water vapor and wind. On the contrary, there are no such peaks in the wind speed covariance chart of methane gas. Under such conditions, using the time corresponding to the maximum covariance value as the time error of the instrument will cause the overall flux calculation result to be too large.

[0101] Since the multi-component gas flux analysis system of the present application can simultaneously detect the gas concentration data of water vapor and methane in the first gas, the time delay can be calculated by capturing the maximum covariance of water vapor and wind speed, and this time delay data is used as the calibration parameter for other low-concentration gas detection data.

[0102] In this embodiment, by setting the first wavelength of the first laser to a wavelength with an absorption peak for water or a wavelength with an absorption peak for methane; the first gas includes water and methane, obvious characteristics can be observed in the covariance results of water vapor and wind. The time delay is calculated by capturing the maximum covariance of water vapor and wind speed, and this time delay data is used as the calibration parameter for other low-concentration gas detection data, thereby reducing the time calibration error in the process of eddy flux calculation.

[0103] In one embodiment, the second wavelength of the second laser is a wavelength with an absorption peak for ammonia, and the second gas includes ammonia; or the second wavelength of the second laser is a wavelength with an absorption peak for nitrous oxide, and the second gas includes nitrous oxide; or the second wavelength of the second laser is a wavelength with an absorption peak for carbon monoxide, and the second gas includes carbon monoxide.

[0104] Exemplarily, according to the different absorption signal intensities of each gas under lasers of different wavelengths, the second wavelength of the second laser can be a wavelength with an absorption peak for greenhouse gases, and the second gas can include greenhouse gases. For example, greenhouse gases include but are not limited to ammonia, nitrous oxide, carbon monoxide, carbon dioxide, and ethane. As Figure 7 shown: Select appropriate wavelength lasers to detect greenhouse gases ammonia, nitrous oxide, carbon monoxide, and methane.

[0105] The wavelength of the laser is initially selected according to the absorption intensity of each gas at different wavelengths, and then the specific wavelength is simulated and analyzed. Figure 8 The simulation absorption data results of methane and water are shown. According to Figure 8 the simulation absorption data results of methane and water, the first laser 2011 of the multi-component gas flux analysis system selects a corresponding wavelength laser with relatively high absorption peaks for both methane and water. The first wavelength of the first laser is a wavelength with an absorption peak for water or a wavelength with an absorption peak for methane, and the first gas includes water and methane. When it is necessary to detect the ammonia concentration in the atmosphere, according to Figure 9Ammonia simulation absorption data. The second laser 2021 uses a laser with a wavelength corresponding to a relatively high ammonia absorption peak, that is, the second wavelength of the second laser is the wavelength with an ammonia absorption peak, and the second gas includes ammonia; when it is necessary to detect the concentrations of nitrous oxide and carbon monoxide in the atmosphere, according to Figure 10 Nitrous oxide and carbon monoxide simulation absorption data. The second laser 2021 uses a laser with a wavelength corresponding to relatively high absorption peaks of nitrous oxide and carbon monoxide, that is, the second wavelength of the second laser is the wavelength with a nitrous oxide absorption peak, and the second gas includes nitrous oxide; or the second wavelength of the second laser is the wavelength with a carbon monoxide absorption peak, and the second gas includes carbon monoxide.

[0106] In this embodiment, by utilizing the characteristic that the absorption peaks of methane and water are close, the first wavelength of the first laser is set to the wavelength with a methane absorption peak, so that the gas intensities of two gas components can be measured simultaneously. Similarly, by utilizing the characteristic that the absorption peaks of nitrous oxide and carbon monoxide are close, the second wavelength of the second laser is set to the wavelength with nitrous oxide and carbon monoxide absorption peaks, and through the multi-component gas concentration data obtained by this instrument, the concentration ratio relationships of ammonia, methane or nitrous oxide, carbon monoxide, and methane can be obtained. Furthermore, the types of pollution sources can be evaluated through data analysis, providing data support for relevant departments in environmental detection and protection.

[0107] In one embodiment, the data processor: obtains the air molar mass, the target gas molar mass, the air density, the vertical wind pulsation, and the target gas mixing ratio pulsation; obtains the first spectral information based on the first electrical signal and the second spectral information based on the second electrical signal; obtains the mixing ratios of the first gas and the second gas of the target gas passing through the open absorption cell 101 through the first spectral information and the second spectral information; obtains the flux of the target gas based on the air molar mass, the target gas molar mass, the air density, the vertical wind pulsation, the target gas mixing ratio pulsation, and the mixing ratios of the first gas and the second gas.

[0108] According to the principle of Net Ecosystem Exchange (NEE), under the assumptions of turbulent stationarity, horizontally homogeneous surface, and turbulent characteristics, the mass balance equation is simplified to a simple form, which is also the most essential flux calculation formula:

[0109]

[0110] In formula (10), F C is the flux; x c is the target gas mixing ratio, that is, the mixing ratios of the first gas and the second gas of the target gas passing through the open absorption cell 101 obtained through the first spectral information and the second spectral information; M dis the molar mass of air, optionally, M d is the molar mass of dry air; M c is the molar mass of the target gas; ρ d is the air density, optionally, ρ d is the dry air density; w’ is the vertical wind pulsation; x c ’ is the pulsation of the target gas mixing ratio; is the average value of the product of the vertical wind pulsation and the target gas mixing ratio pulsation within a certain period of time. Optionally, this certain period of time is half an hour. It can be understood that the longer the time, the more accurate the flux data.

[0111] Exemplarily, the data processor 104 of the multi-component gas flux analysis system further includes obtaining the molar mass M of air d , the molar mass M of the target gas c , the air density ρ d , the vertical wind pulsation w’ and the target gas mixing ratio pulsation x c ’; obtaining the first spectral information based on the first electrical signal, and obtaining the second spectral information based on the second electrical signal; obtaining the mixing ratios of the first gas and the second gas of the target gas passing through the open absorption cell 101 through the first spectral information and the second spectral information; according to formula (10), based on the molar mass M of air d , the molar mass M of the target gas c , the air density ρ d , the vertical wind pulsation w’, the target gas mixing ratio pulsation and the mixing ratios of the first gas and the second gas to obtain the flux of the target gas.

[0112] In this embodiment, by accurately measuring the gas mixing ratio, complex spectral correction and density correction are discarded during the calculation of the eddy flux, and the flux data of the gas to be measured is directly calculated, thereby improving the calculation efficiency and calculation accuracy. And it is possible to determine the proportional relationship of ammonia, methane or nitrous oxide, carbon monoxide, methane based on the multi-component gas concentration data obtained by detection, and evaluate the types of pollution sources.

[0113] In one embodiment, the data processor: obtains the concentration of the target gas passing through the open absorption cell 101 through the first spectral information and the second spectral information; obtains the mixing ratios of the first gas and the second gas based on the concentration of the target gas.

[0114] Exemplarily, the concentration of the target gas passing through the open absorption cell 101 is obtained through the first spectral information and the second spectral information; the mixing ratios of the first gas and the second gas are obtained based on the concentration of the target gas, and then the flux of the target gas can be obtained based on the molar mass of air, the molar mass of the target gas, the air density, the vertical wind pulsation, the target gas mixing ratio pulsation and the mixing ratios of the first gas and the second gas.

[0115] In this embodiment, a first time delay is obtained based on a first electrical signal, and a second time delay is obtained based at least on a second electrical signal, where the first electrical signal is stronger than the second electrical signal, and the second time delay is corrected based on the first time delay, so that time delay data of greenhouse gases with a low concentration in the atmosphere can be accurately obtained, and thus the multi-component gas flux analysis system of this embodiment can obtain a more accurate flux result of the target gas.

[0116] Since the multi-component gas flux analysis system of this embodiment can simultaneously collect high-frequency target gas and water vapor density and is insensitive to temperature changes, the flux can be calculated using the mixing ratio. Because the pressure pulsation in the atmosphere is relatively slow and is mainly caused by water vapor changes, the influence of pressure pulsation is usually ignored in the calculation. The mixing ratio formula is defined as follows:

[0117]

[0118] In formula (11), x cm is the measured mixing ratio, which is the mixing ratio of the target gas in this embodiment; is the spectral correction average coefficient; ρ cm is the density of the gas to be measured, which is the density of the target gas in this embodiment; is the average ambient temperature; R d is the specific gas constant of dry air; e is the water vapor partial pressure; is the average air pressure.

[0119] The measured mixing ratio is used to represent the true mixing ratio: k is the spectral correction coefficient; P is the air pressure; T is the ambient temperature.

[0120]

[0121] In the formula: is the mixing ratio of water measurement; Substituting formula (12) and formula (13) into formula (14) can obtain the relationship between x c and x cm . Since the atmospheric pressure changes little within half an hour, it can be approximately equal to 1. After Reynolds decomposition, the mixing ratio can be rewritten in the following form:

[0122]

[0123] Higher-order small terms are ignored in the derivation (e.g., k’T’, k’x’ cm ).

[0124] k′ = k T T′ + k v ρ v ′ (16)

[0125] In the formula:

[0126]

[0127] At M T , k v When approaching 0, M T and k v are the effects of temperature and water vapor pulsations on the instrument concentration measurement. Therefore, the multi-component gas flux analysis system of this embodiment can calculate gas flux data using the measured gas mixing ratio data.

[0128] In an exemplary embodiment, the multi-component gas flux analysis system further includes a mirror cleaner, which is disposed on one side of the reflecting surface of the second mirror 1012. The mirror cleaner includes: a first connector 1062 for receiving a third gas; a second connector 1063 for receiving a liquid; a cavity 1061 surrounding the second mirror 1012, and a plurality of spray holes 10611 are provided on the outer wall of the cavity 1061; the cavity 1061 is connected to the first connector 1062 to receive the third gas input through the first connector 1062, and the cavity 1061 is also connected to the second connector 1063 to receive the liquid input through the second connector 1063; wherein the fluid formed by mixing the third gas and the liquid in the cavity 1061 is ejected through the plurality of spray holes 10611.

[0129] Since the multi-component gas flux analysis system operates in an outdoor environment, the mirror surfaces of the first mirror 1011 and the second mirror 1012 of the absorption cell are easily covered by dust or other debris in the air, resulting in abnormal detection of gas concentration data. In this embodiment, a mirror flushing cleaner is designed. When the system recognizes that the detected gas signal strength (Optical Signal Strength, OSS) is lower than the set warning value, the system automatically starts the mirror flushing cleaner to work.

[0130] Please refer to Figure 11 , Figure 11 which is a schematic structural diagram of the mirror cleaner of the multi-component gas flux analysis system in an embodiment of the present application. Figure 11 In, the mirror cleaner is disposed on one side of the reflecting surface of the second mirror 1012. The cavity 1061 is installed above the second mirror 1012, and its size is larger than the diameter of the reflecting lens to avoid blocking the optical path. The cavity 1061 is fixed to the multi-component gas flux analysis system through a connecting member. Exemplarily, the interior of the cavity 1061 is a circular cavity, and a plurality of spray holes 10611 are provided on the inner side surface, as Figure 12As shown, it is a schematic structural diagram of the nozzle 10611 of the cavity 1061 in an embodiment of the present application. A first joint 1062 and a second joint 1063 are provided on the cavity 1061. The first joint 1062 serves as an air inlet for receiving a third gas, and the third gas can be air; the second joint 1063 is used for receiving liquid. Exemplarily, the second joint 1063 is connected to a water tank as a water inlet. The cavity 1061 is connected to the first joint 1062 to receive the third gas input through the first joint 1062. The cavity 1061 is also connected to the second joint 1063 to receive the liquid input through the second joint 1063. The fluid formed by mixing the third gas and the liquid in the cavity 1061 is ejected through a plurality of nozzles 10611. It can be understood that the first joint 1062 can also be a water inlet, and the second joint 1063 can also be an air inlet, which is not limited in this application.

[0131] In this embodiment, by providing a mirror cleaner, the component gas flux analysis system can automatically clean the reflecting mirror, which can reduce the labor maintenance cost.

[0132] In an exemplary embodiment, a plurality of nozzles 10611 are arranged on the outer wall of the cavity 1061 at equal intervals from each other. The fluid formed by mixing the third gas and the liquid in the cavity 1061 is ejected obliquely from the nozzles 10611. A through hole 10121 is provided in the middle of the second reflector 1012, and the fluid is discharged through the through hole 10121. The cavity 1061 is provided as a hollow body.

[0133] Please also refer to Figure 11 and Figure 12 , the cavity 1061 is provided as a hollow body. A plurality of nozzles 10611 are arranged on the outer wall of the cavity 1061 at equal intervals from each other. A third gas such as air and a liquid such as water are respectively introduced into the cavity 1061 through the first joint 1062 and the second joint 1063. The fluid formed by mixing in the cavity 1061 is ejected obliquely from each nozzle 10611 towards the lens of the second reflector 1012. The ejected fluid forms a vortex to impact the mirror surface of the second reflector 1012, thereby blowing away and flushing away the dust, powder and other sundries on the mirror surface. A through hole 10121 is provided in the middle of the second reflector 1012, and the fluid is discharged through the through hole 10121.

[0134] In this embodiment, by reasonably setting the position of the nozzles 10611 on the cavity 1061 and receiving the third gas and the liquid through the first joint 1062 and the second joint 1063 respectively to form a fluid, the ejected fluid can form a vortex to impact the mirror surface of the second reflector 1012, thereby blowing away and flushing away the dust, powder and other sundries on the mirror surface. Only the fluid contacts the mirror surface of the second reflector 1012 during the whole process, so the mirror surface will not be scratched.

[0135] In an exemplary embodiment, a heater is provided on a side opposite to the reflecting surface of the second mirror 1012.

[0136] Exemplarily, a heater is installed on a side opposite to the reflecting surface of the second mirror 1012 in the multi-component gas flux analysis system, so as to accelerate the evaporation of water on the mirror surface of the second mirror 1012, enabling the instrument to be quickly used after cleaning.

[0137] In an exemplary embodiment, please refer to Figure 13 , the system further includes a brush cleaner 107, which is arranged on one side of the reflecting surface of the second mirror 1012. The brush cleaner 107 includes:

[0138] A protective cover 1071, which is arranged on the brush cleaner 1072;

[0139] The brush cleaner 1072, and the brush of the brush cleaner 1072 is in contact with the reflecting surface of the second mirror 1012.

[0140] Exemplarily, the brush cleaner 2 is connected to an adjustable-speed motor inside the system and fixed on the base. The brush on the brush cleaner 2 is in contact with the reflecting surface of the second mirror 1012, and the protective cover 1071 is attached to the brush cleaner 2 with screws.

[0141] The working principle of the brush cleaner 107 is as follows: After the system receives a cleaning instruction, the adjustable-speed motor starts to work. By its own gravity and the centrifugal force generated by rotation, the position of the brush is adjusted so that the brush is exactly in the spot 10115 area of the second mirror 1012 for cleaning, thereby cleaning the dust, powder and other sundries at the mirror surface spot 10115. Since the brush is relatively soft and the rotation speed is limited, it will not damage the mirror surface.

[0142] To solve the problem of real-time detection of multi-component greenhouse gas concentration data in an open environment, this application proposes a multi-component gas flux analysis system. An open gas absorption cell is designed between the transmitting end 103 and the reflecting end 102 of this system, and the greenhouse gas to be measured in the open environment can flow freely. To synchronously detect multi-component greenhouse gases, such as ammonia, methane, water, or nitrous oxide, carbon monoxide, methane, water, this system designs a dual-laser dual-light-path structure. By using the absorption relationship of different gases under lasers with different wavelengths, the actual concentration data of multiple gases can be obtained. Through the accurate gas mixing ratio detected by this system, the flux data of the gas to be measured can be directly calculated, thereby eliminating complex spectral correction and density correction in the process of calculating the flux, and improving the calculation efficiency and calculation accuracy. To reduce the error of time calibration in the process of calculating the eddy flux, the multi-component gas can correct the time delay of the weak-signal gas through the time delay of the strong-signal gas, such as correcting the time delay of the methane gas through the time delay of the water vapor. This system can determine the proportional relationship of ammonia, methane, or nitrous oxide, carbon monoxide, methane based on the detected multi-component gas concentration data, and evaluate the types of pollution sources.

[0143] Based on the same inventive concept, an embodiment of this application also provides a method for determining the time delay of a multi-component gas flux analysis system applied to the above multi-component gas flux analysis system. The implementation solution provided by this method to solve the problem is similar to the implementation solution described in the above multi-component gas flux analysis system. Therefore, the specific limitations in one or more embodiments of the method for determining the time delay of the multi-component gas flux analysis system provided below can refer to the limitations on the multi-component gas flux analysis system in the above text, and will not be repeated here.

[0144] In an exemplary embodiment, as Figure 14 shown, a method for determining the time delay of a multi-component gas flux analysis system is provided. Taking this method applied to the Figure 2 multi-component gas flux analysis system as an example, it includes the following steps 1402 to step 1406.

[0145] Step 1402, control the first light source to emit the first laser with the first wavelength; control the second light source to emit the second laser with the second wavelength; the first laser is reflected multiple times between the first mirror of the open absorption cell and the second mirror of the open absorption cell to obtain the first outgoing light, and the second laser is reflected multiple times between the first mirror and the second mirror to obtain the second outgoing light; wherein the target gas passes between the first mirror and the second mirror, and the target gas includes two different first gases and second gases.

[0146] Step 1404: Control the first detector to receive the first emitted light and convert the received first emitted light into a first electrical signal; control the second detector to receive the second emitted light and convert the received second emitted light into a second electrical signal; there is an electrical signal in the first electrical signal that is stronger than the second electrical signal.

[0147] Step 1406: Control the data processor to obtain a first time delay based on the first electrical signal, obtain a second time delay at least based on the second electrical signal, and correct the second time delay based on the first time delay.

[0148] In the above method for determining the time delay of the multi-component gas flux analysis system, the time delay of a weak signal gas such as the second gas can be corrected by the time delay of the first gas containing the strong signal gas, thereby reducing the error of time calibration in the process of vorticity flux calculation.

[0149] In an exemplary embodiment, as Figure 15 shown, step 1406 includes:

[0150] Step 1502: Obtain a reference signal and an average reference signal; the average reference signal is the average signal of a predetermined number of detections of the reference signal.

[0151] Step 1504: Generate a first average electrical signal based on the first electrical signal; the first average electrical signal is the average signal of a predetermined number of detections of the first electrical signal; generate a second average electrical signal based on the second electrical signal; the second average electrical signal is the average signal of a predetermined number of detections of the second electrical signal.

[0152] Step 1506: Generate a first time delay covariance with different time delays based on the reference signal, the average reference signal, the first electrical signal, and the first average electrical signal.

[0153] Step 1508: Generate a second time delay covariance with different time delays based on the reference signal, the average reference signal, the second electrical signal, and the second average electrical signal.

[0154] Step 1510: Generate a maximum first time delay covariance based on the first time delay covariance with different time delays, and the time delay corresponding to the maximum first time delay covariance is the first time delay; generate a maximum second time delay covariance based on the second time delay covariance with different time delays, and the time delay corresponding to the maximum second time delay covariance is the second time delay.

[0155] Step 1512: Correct the second time delay based on the first time delay.

[0156] In an exemplary embodiment, the data processor includes an ultrasonic anemometer, and obtaining the reference signal and the average reference signal includes: obtaining the reference signal and the average reference signal through the ultrasonic anemometer.

[0157] In an exemplary embodiment, the method for determining the time delay of the multi-component gas flux analysis system further includes: obtaining the molar mass of air, the molar mass of the target gas, the air density, the vertical wind pulsation, and the target gas mixing ratio pulsation; obtaining first spectral information based on the first electrical signal and second spectral information based on the second electrical signal; obtaining the mixing ratio of the target gas passing through the open absorption cell from the first spectral information and the second spectral information; and obtaining the flux of the target gas based on the molar mass of air, the molar mass of the target gas, the air density, the vertical wind pulsation, the target gas mixing ratio pulsation, and the mixing ratio of the target gas.

[0158] In an exemplary embodiment, obtaining the mixing ratio of the target gas passing through the open absorption cell from the first spectral information and the second spectral information includes: obtaining the concentration of the target gas passing through the open absorption cell from the first spectral information and the second spectral information; and obtaining the mixing ratio of the target gas based on the concentration of the target gas.

[0159] In an exemplary embodiment, the first wavelength of the first laser is a wavelength having an absorption peak for water or an absorption peak for methane; the first gas includes water and methane.

[0160] It should be understood that although the steps in the flowcharts involved in the above-described embodiments are shown in sequence according to the indications of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-described embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same moment, but can be executed at different moments. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or steps or stages in other steps.

[0161] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0162] The above-described embodiments only represent several implementation manners of the present application. Their descriptions are relatively specific and detailed, but should not be construed as limiting the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A multi-component gas flux analysis system, characterized in that: include: A first light source, configured to emit a first laser having a first wavelength; A second light source, configured to emit a second laser having a second wavelength; An open absorption cell, comprising a first reflector and a second reflector; a target gas of the open absorption cell passes between the first reflector and the second reflector; the target gas of the open absorption cell comprises a first gas and a second gas which are different from each other; the first laser is reflected multiple times between the first reflector and the second reflector to obtain a first output light, and the second laser is reflected multiple times between the first reflector and the second reflector to obtain a second output light; a first end surface, wherein the first reflector is disposed on the first end surface; a second end surface, the second reflector is arranged on the second end surface, and the first end surface and the second end surface are connected by a supporting frame; a first detector, receiving the first emitted light, and converting the received first emitted light into a first electrical signal; a second detector, receiving the second emitted light, and converting the received second emitted light into a second electrical signal; wherein the first electrical signal contains an electrical signal stronger than the second electrical signal; A data processor is configured to obtain a first time delay based on the first electrical signal, obtain a second time delay based at least on the second electrical signal, and correct the second time delay based on the first time delay.

2. The multi-component gas flux analysis system according to claim 1, characterized in that: The first reflector includes a first concave reflector, and the second reflector includes a second concave reflector; the first concave reflector includes a first light inlet, a first light outlet, a second light inlet, and a second light outlet; the first laser is incident on the open absorption pool through the first light inlet, and is reflected multiple times between the first concave reflector and the second concave reflector before being emitted through the first light outlet to obtain the first emitted light; the second laser is incident on the open absorption pool through the second light inlet, and is reflected multiple times between the first concave reflector and the second concave reflector before being emitted through the second light outlet to obtain the second emitted light; The first wavelength of the first laser is a wavelength having an absorption peak for water or a wavelength having an absorption peak for methane; the first gas includes water and methane; The second wavelength of the second laser is a wavelength having an absorption peak for ammonia, and the second gas includes ammonia; or The second wavelength of the second laser is a wavelength having an absorption peak for nitrous oxide, and the second gas includes nitrous oxide; or The second wavelength of the second laser is a wavelength having an absorption peak for carbon monoxide, and the second gas includes carbon monoxide.

3. The multi-component gas flux analysis system according to claim 1, characterized in that: The data processor: Acquire a reference signal and an average reference signal; the average reference signal is an average signal of a predetermined number of detections of the reference signal; generating a first average electrical signal based on the first electrical signal; The first average electrical signal is an average signal of the predetermined number of detections of the first electrical signal; generating a second average electrical signal based on the second electrical signal; The second average electrical signal is an average signal of the predetermined number of detections of the second electrical signal; generating a first time delay covariance of different time delays based on the reference signal, the average reference signal, the first electrical signal, and the first average electrical signal; generating a second time delay covariance with different time delays based on the reference signal, the average reference signal, the second electrical signal, and the second average electrical signal; Generate a maximum first time delay covariance based on the first time delay covariance of the different time delays, and the time delay corresponding to the maximum first time delay covariance is the first time delay; generate a maximum second time delay covariance based on the second time delay covariance of the different time delays, and the time delay corresponding to the maximum second time delay covariance is the second time delay; The second time delay is corrected based on the first time delay.

4. The multi-component gas flux analysis system according to claim 3, characterized in that: Data Processor: Obtain air molar mass, target gas molar mass, air density, vertical wind pulsation and target gas mixing ratio pulsation; Acquire first spectrum information based on the first electrical signal, and acquire second spectrum information based on the second electrical signal; Obtaining the concentration of the target gas passing through the open absorption cell through the first spectral information and the second spectral information; obtaining a mixing ratio of the first gas and the second gas based on the concentration of the target gas; The flux of the target gas is obtained based on the air molar mass, the target gas molar mass, the air density, the vertical wind pulsation, the target gas mixing ratio pulsation, and the mixing ratio of the first gas and the second gas.

5. The multi-component gas flux analysis system according to claim 1, characterized in that: The reflection spot of the first laser on the first reflector forms a first circle, and the reflection spot of the second laser on the first reflector forms a second circle. The first circle and the second circle are concentric circles.

6. The multi-component gas flux analysis system according to claim 1, characterized in that: It also includes a mirror cleaning device, which is arranged on one side of the reflective surface of the second reflector, and the mirror cleaning device includes: A first connector for receiving a third gas; a second connector for receiving liquid; A cavity is arranged around the second reflector, and a plurality of spray holes are arranged on the outer wall of the cavity; the cavity is connected to the first joint to receive the third gas input through the first joint, and the cavity is also connected to the second joint to receive the liquid input through the second joint; wherein the fluid formed by the third gas and the liquid mixed in the cavity is sprayed out through the plurality of spray holes; the plurality of spray holes are arranged on the outer wall of the cavity at equal intervals, and the fluid formed by the third gas and the liquid mixed in the cavity is sprayed out obliquely from the spray holes; A through hole is provided in the middle of the second reflector, and the fluid is discharged through the through hole; The cavity is arranged to be hollow; a heater is arranged on the side opposite to the reflecting surface of the second reflecting mirror.

7. The multi-component gas flux analysis system according to claim 1, characterized in that: It also includes a brush cleaner, which is arranged on one side of the reflective surface of the second reflector, and the brush cleaner includes: A protective cover is arranged on the brush cleaner; A brush cleaner, wherein the brush of the brush cleaner contacts the reflective surface of the second reflector.

8. A method for determining time delay of a multi-component gas flux analysis system, characterized in that: include: Controlling the first light source to emit a first laser with a first wavelength; controlling the second light source to emit a second laser with a second wavelength; The first laser is reflected multiple times between a first reflector of the open absorption cell and a second reflector of the open absorption cell to obtain a first output light, and the second laser is reflected multiple times between the first reflector and the second reflector to obtain a second output light; The target gas passes between the first reflector and the second reflector, and the target gas includes a first gas and a second gas that are different from each other; Controlling the first detector to receive the first emitted light and converting the received first emitted light into a first electrical signal; controlling the second detector to receive the second emitted light and converting the received second emitted light into a second electrical signal; the first electrical signal contains an electrical signal stronger than the second electrical signal; The control data processor obtains a first time delay based on the first electrical signal, obtains a second time delay based on at least the second electrical signal, and corrects the second time delay based on the first time delay.

9. The method according to claim 1, characterized in that: The control data processor obtains a first time delay based on the first electrical signal, obtains a second time delay based at least on the second electrical signal, and corrects the second time delay based on the first time delay, including: Acquire a reference signal and an average reference signal; the average reference signal is an average signal of a predetermined number of detections of the reference signal; Generate a first average electrical signal based on the first electrical signal; the first average electrical signal is an average signal of the predetermined number of detections of the first electrical signal; generate a second average electrical signal based on the second electrical signal; the second average electrical signal is an average signal of the predetermined number of detections of the second electrical signal; generating a first time delay covariance of different time delays based on the reference signal, the average reference signal, the first electrical signal, and the first average electrical signal; generating a second time delay covariance with different time delays based on the reference signal, the average reference signal, the second electrical signal, and the second average electrical signal; Generate a maximum first time delay covariance based on the first time delay covariance of the different time delays, and the time delay corresponding to the maximum first time delay covariance is the first time delay; generate a maximum second time delay covariance based on the second time delay covariance of the different time delays, and the time delay corresponding to the maximum second time delay covariance is the second time delay; The second time delay is corrected based on the first time delay.

10. The method according to claim 9, characterized in that The method further comprises: Obtain air molar mass, target gas molar mass, air density, vertical wind pulsation and target gas mixing ratio pulsation; Acquire first spectrum information based on the first electrical signal, and acquire second spectrum information based on the second electrical signal; Obtaining the concentration of the target gas passing through the open absorption cell through the first spectral information and the second spectral information; obtaining a mixing ratio of the target gas based on the concentration of the target gas; The flux of the target gas is obtained based on the molar mass of the air, the molar mass of the target gas, the air density, the vertical wind pulsation, the target gas mixing ratio pulsation and the mixing ratio of the target gas; the first wavelength of the first laser is a wavelength having an absorption peak for water or an absorption peak for methane; and the first gas includes water and methane.

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