Low-cavity mode gas absorption cell for closed-cavity flux greenhouse gas monitoring

Abstract

The utility model relates to the technical field of greenhouse gas detection, in particular to a low-cavity-mode gas absorption cell for closed-cavity flux greenhouse gas monitoring, which comprises a laser used for emitting laser beams, and further comprises a base, a gas absorption tube, a gas absorption tube and a gas absorption tube, and the strip-shaped reflecting mirror a and the strip-shaped reflecting mirror b are respectively arranged at the two ends of the base. According to the utility model, the ultra-thin strip-shaped reflecting mirror is adopted, so that the low-cavity-die and long-optical-path gas absorption cell is realized, the measurement optical path exceeds 5m, the cavity die volume is less than 15mL and the gas replacement time is less than 1s under the condition of small volume, and the absorption cell adopts an up-and-down structure, has few parts, is low in cost and is convenient to debug and maintain; by means of rapid gas replacement and optimized light path design, laser beams can interact with newly entering gas more rapidly, the detector can detect gas concentration changes more timely, flux monitoring precision is improved, and greenhouse gas flux data can be obtained more accurately.

Description

Technical Field

[0001] This utility model relates to the field of greenhouse gas detection technology, specifically to a low-cavity model gas absorption cell for closed-cavity flux greenhouse gas monitoring. Background Technology

[0002] The gas absorption cell is a key component of a closed-cavity greenhouse gas flux measurement system. Based on its optical path structure, it is mainly classified into single-path direct-infrared, multi-reflection (White / Herriott Ce10-15mL), and annular cavity-enhanced (CRDS) types. Single-path direct-infrared absorption cells, due to their short optical path and low sensitivity, are mainly used for detecting high-concentration pollution sources and are not suitable for atmospheric measurements. Multi-reflection absorption cells use two concave mirrors to achieve multiple reflections (usually 20-100 times) to increase the optical path, offering advantages such as simple structure and low cost, and are widely used. Cavity-enhanced absorption cells possess the highest equivalent optical path, reaching the kilometer level, and have high sensitivity, making them suitable for high-precision, low-concentration gas detection.

[0003] However, the gas absorption cells currently used for closed-cavity flux greenhouse gas monitoring are mainly based on the multi-reflection principle. Traditional reflective absorption cells are mainly divided into two types: White type and Herriott type. Regardless of the type, they all have problems such as large cavity size and slow gas replacement speed. The response speed has a lag of 5-12 seconds compared with the three-dimensional wind field detection, which seriously affects the monitoring accuracy of flux. Utility Model Content

[0004] To address the aforementioned shortcomings of existing technologies, this invention provides a low-cavity gas absorption cell for closed-cavity flux greenhouse gas monitoring, which effectively solves the problems of large cavity size and slow gas replacement rate in existing technologies.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] This invention provides a low-cavity mode gas absorption cell for closed-cavity flux greenhouse gas monitoring, including a laser for emitting a laser beam, and further comprising:

[0007] A base, wherein a protruding plate is fixedly connected to the upper end of the base;

[0008] Strip-shaped reflector a and strip-shaped reflector b are respectively installed at both ends of the base;

[0009] The top cover is fixed to the base by screws. The base, the top cover, and the strip reflector a and strip reflector b together form a cavity mold, which is a closed cavity.

[0010] The strip-shaped reflector a and strip-shaped reflector b are respectively provided with beam entry and exit holes, which are used for the laser beam to enter and exit the cavity mode.

[0011] According to the aforementioned low-cavity model gas absorption cell for closed-cavity flux greenhouse gas monitoring, both the strip-shaped reflector a and the strip-shaped reflector b are ultra-thin reflectors.

[0012] According to the aforementioned low-cavity model gas absorption cell for closed-cavity greenhouse gas flux monitoring, the volume of the cavity model is 10-15 mL.

[0013] According to the aforementioned low-cavity greenhouse gas absorption cell for closed-cavity flux monitoring, a sealing gasket is provided between the base and the top cover, and the sealing gasket, together with the convex plate, ensures the sealing of the cavity.

[0014] The low-cavity model gas absorption pool for closed-cavity flux greenhouse gas monitoring described above also includes a gas inlet and a gas outlet connected to the cavity model. The gas inlet and gas outlet are located on the base to enable rapid exchange of gas inside the cavity model with external gas.

[0015] According to the low-cavity mode gas absorption cell for closed-cavity flux greenhouse gas monitoring described above, the laser beam is a laser beam of a specific wavelength, and the wavelength of the laser beam matches the absorption spectrum of the greenhouse gas to be monitored.

[0016] The technical solution provided by this utility model has the following advantages compared with the known prior art:

[0017] 1. This utility model achieves a low cavity mode and long optical path gas absorption cell by using an ultra-thin strip-shaped reflector. It achieves a measurement optical path of more than 5m, a cavity mode volume of less than 15mL, and a gas replacement time of less than 1s in a small volume. The absorption cell adopts an upper and lower structure, with fewer parts, lower cost, and convenient debugging and maintenance.

[0018] 2. This invention reduces the cavity module volume and accelerates gas replacement. The rapid gas replacement and optimized optical path design enable the laser beam to interact with the newly introduced gas more quickly, and the detector can detect changes in gas concentration more promptly, greatly improving the response speed and reducing hysteresis, thereby improving the accuracy of flux monitoring and enabling more accurate acquisition of greenhouse gas flux data. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a cross-sectional structural diagram of the present invention;

[0021] Figure 2 This is a front view structural diagram of the present invention;

[0022] Figure 3 for Figure 1 A schematic diagram of the structure of the central base.

[0023] Reference numerals in the attached drawings: 1. Base; 11. Convex plate; 2. Top cover; 3. Strip reflector a; 4. Strip reflector b; 5. Beam inlet / outlet hole; 6. Cavity mold. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0025] The present invention will be further described below with reference to the embodiments.

[0026] Example: Refer to Figures 1 to 3 The low-cavity mode gas absorption cell for closed-cavity flux greenhouse gas monitoring includes a laser that emits a laser beam of a specific wavelength. The wavelength of the laser beam matches the absorption spectrum of the greenhouse gas to be monitored. In practical applications, a semiconductor laser can be selected, which has advantages such as small size, low power consumption, and convenient modulation. For example, for monitoring carbon dioxide, a semiconductor laser with an emission wavelength in the range of 2.004μm-2.008μm can be selected. This wavelength is near the absorption peak of carbon dioxide and can be effectively absorbed by carbon dioxide. This design ensures that the laser beam can generate a strong interaction with the greenhouse gas to be monitored, improving the sensitivity and accuracy of monitoring, and enabling the entire monitoring system to accurately identify and measure the content of the target greenhouse gas.

[0027] The base 1 has a protruding plate 11 fixedly connected to its upper end. The base is made of high-strength, corrosion-resistant aluminum alloy material. This material can ensure the structural strength of the base and prevent it from being corroded in humid or corrosive environments. The design of the protruding plate 11 not only increases the stability of the connection between the base and the top cover, but also provides a better installation position for the sealing gasket, so that the sealing gasket can play a better role in preventing gas leakage and maintaining the stability of the gas environment inside the cavity mold 6. This is crucial for accurately measuring the concentration of greenhouse gases.

[0028] Strip mirrors a3 and b4 are respectively installed at both ends of the base 1. Both strip mirrors a3 and b4 are ultra-thin mirrors. The ultra-thin mirrors adopt a special coating process to minimize the absorption and scattering of the laser beam while ensuring high reflectivity. For example, multilayer dielectric film coating technology is used to make the reflectivity of the mirror reach more than 99.9% at a specific wavelength. This design can effectively increase the number of reflections of the laser beam in the cavity mode 6, extend the optical path, and improve the monitoring sensitivity. At the same time, the ultra-thin design helps to reduce the volume of the cavity mode 6. By reducing the thickness of the mirror itself, the space occupied by the cavity mode 6 is reduced, so the volume of the cavity mode 6 can be reduced, thereby improving the gas replacement efficiency, reducing gas residue, and improving the monitoring accuracy.

[0029] The upper cover 2 is fixed to the base 1 with screws. The base 1, the upper cover 2, and the strip reflectors a3 and b4 together form a cavity mold 6. The cavity mold 6 is a closed cavity with a volume of 10-15 mL. The connection between the upper cover 2 and the base 1 uses high-precision screws to ensure a tight connection. During installation, the screws are tightened to the specified torque to prevent poor sealing due to overtightening or loosening. The precise control of the cavity mold 6 volume allows the gas to be quickly replaced in a limited space, reducing measurement errors. The smaller cavity mold 6 volume allows for more complete interaction between gas molecules and the laser beam, which also accelerates the gas replacement speed, shortens the measurement response time, and helps improve the real-time performance and accuracy of monitoring.

[0030] A sealing gasket is provided between the base 1 and the top cover 2. The sealing gasket, together with the protruding plate 11, ensures the sealing of the cavity mold 6. The cooperation between the sealing gasket and the protruding plate 11 is a key measure to ensure the sealing of the cavity mold 6, effectively preventing the mixing of external gases and the leakage of internal gases, maintaining the stability of the gas composition inside the cavity mold 6, and providing a reliable environment for accurate measurement of greenhouse gas concentration.

[0031] The strip reflectors a3 and b4 are respectively provided with beam entry and exit holes 5. The beam entry and exit holes 5 are used for the laser beam to enter and exit the cavity mode 6, providing a channel for the laser beam to enter and exit the cavity mode 6, so that the laser beam can be reflected multiple times in the cavity mode 6 and fully interact with the gas in the cavity mode 6, thereby realizing the effective monitoring of greenhouse gases.

[0032] It also includes a gas inlet and a gas outlet connected to the cavity mold 6. The gas inlet and gas outlet are set on the base 1 to realize the rapid exchange of gas inside the cavity mold 6 with external gas. Both the gas inlet and the gas outlet are equipped with flow control valves, which can accurately control the gas flow rate according to actual needs. For example, when performing rapid measurements, the gas flow rate can be increased to speed up the gas replacement speed; when a stable measurement environment is required, the flow rate can be appropriately reduced. This solves the problem of slow gas replacement speed in traditional absorption tanks, can quickly update the gas inside the cavity mold, improve the timeliness of monitoring, and make the monitoring results more reflective of real-time changes in greenhouse gas concentration.

[0033] The working principle of this utility model is as follows:

[0034] A laser beam of a specific wavelength is emitted by a laser, and this wavelength matches the absorption spectrum of the greenhouse gas to be monitored. The laser beam enters the closed cavity mode 6 through the beam inlet / outlet 5 on the bar reflectors a3 and b4. It is reflected back and forth between the bar reflectors a3 and b4 multiple times, increasing the optical path. During the reflection process, the laser beam interacts fully with the greenhouse gas in the cavity mode 6. The gas absorbs the light of the specific wavelength, causing a change in the intensity of the laser beam. By detecting the intensity change of the laser beam after entering and exiting the cavity mode 6, the concentration of the greenhouse gas in the cavity mode can be calculated according to the Lambert-Beer law, thereby realizing the monitoring of greenhouse gas flux in the closed cavity.

[0035] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of this utility model.

Claims

1. A low-cavity mode gas absorption cell for closed-cavity flux greenhouse gas monitoring, comprising a laser for emitting a laser beam, characterized in that, Also includes: The base (1) has a protruding plate (11) fixedly connected to its upper end. Strip mirror a (3) and strip mirror b (4) are respectively installed at both ends of the base (1); The upper cover (2) is fixed to the base (1) by screws. The base (1), the upper cover (2), the strip reflector a (3), and the strip reflector b (4) together form a cavity mold (6), which is a closed cavity. The strip mirror a (3) and strip mirror b (4) are respectively provided with beam entry and exit holes (5), which are used for the laser beam to enter and exit the cavity mode (6).

2. The low-cavity model gas absorption cell for closed-cavity flux greenhouse gas monitoring according to claim 1, characterized in that, Both the strip-shaped reflector a (3) and the strip-shaped reflector b (4) are ultra-thin reflectors.

3. The low-cavity model gas absorption cell for closed-cavity flux greenhouse gas monitoring according to claim 1, characterized in that, The volume of the cavity mold (6) is 10-15 mL.

4. The low-cavity model gas absorption cell for closed-cavity flux greenhouse gas monitoring according to claim 1, characterized in that, A sealing gasket is provided between the base (1) and the top cover (2), and the sealing gasket, together with the protruding plate (11), ensures the sealing of the cavity mold (6).

5. The low-cavity model gas absorption cell for closed-cavity flux greenhouse gas monitoring according to claim 1, characterized in that, It also includes a gas inlet and a gas outlet connected to the cavity mold (6), which are located on the base (1) to enable rapid exchange of gas between the cavity mold (6) and the outside gas.

6. The low-cavity model gas absorption cell for closed-cavity flux greenhouse gas monitoring according to claim 1, characterized in that, The laser beam is a laser beam of a specific wavelength, and the wavelength of the laser beam matches the absorption spectrum of the greenhouse gas to be monitored.

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