Gas detection device and gas concentration detection method

Abstract

The application discloses a kind of gas detection device and gas concentration detection method, it is related to gas detection technical field, first gas sensor, target gas filter unit and second gas sensor are sequentially connected and form detection gas path;Target gas filter unit is used to remove target gas component in gas;When air sequentially flows through first gas sensor, target gas filter unit and second gas sensor, first temperature control device makes the temperature of first gas sensor be in operating temperature range, second temperature control device makes the temperature of second gas sensor be in desorption temperature range;When air sequentially flows through second gas sensor, target gas filter unit and first gas sensor, second temperature control device makes the temperature of second gas sensor be in operating temperature range, first temperature control device makes the temperature of first gas sensor be in desorption temperature range.The application improves the long-term stability, reliability, response speed of detection result.

Description

Technical Field

[0001] This invention relates to the field of gas detection technology, and in particular to a gas detection device and a gas concentration detection method. Background Technology

[0002] Gas detection is a core technology for safeguarding human health, assessing environmental quality, and achieving pollution prevention and risk warning. Among numerous gas sensing technologies, semiconductor gas sensors, with their advantages of small size, low cost, fast response, and ease of integration, have shown broad application prospects in scenarios such as air quality monitoring, mobile monitoring, and distributed environmental sensing.

[0003] Existing semiconductor gas sensors mainly consist of a cap, gas-sensitive material, test electrode, heating electrode, substrate, socket, and pins. Their working principle is as follows: gas molecules undergo a redox reaction with the gas-sensitive material in the semiconductor sensor, changing the carrier concentration of the gas-sensitive material and thus causing a change in its resistance. This process mainly involves two steps. Taking the detection of oxidizing gases using an n-type gas-sensitive material as an example: First, oxygen in the environment adsorbs onto the surface of the gas-sensitive material and captures electrons, generating an initial baseline resistance. When the target oxidizing gas is adsorbed, it further captures carriers in the gas-sensitive material, significantly increasing the material's resistance and forming a response resistance. This resistance change serves as the raw detection signal, which can be acquired through modules such as voltage dividers, constant current sources, or differential amplifiers. After filtering and other processing, the signal accuracy and stability are improved. Then, an analog-to-digital converter converts the analog resistance signal into a digital signal. Finally, a calibration curve maps the resistance signal to gas concentration, enabling real-time monitoring and output of the target gas in the environment.

[0004] In practical engineering applications, the working process of a semiconductor gas sensor is as follows: (1) Baseline establishment and zero-point calibration: Under a stable operating temperature, the semiconductor gas sensor is run in clean air for a period of time, and its steady-state resistance (i.e. baseline resistance) is recorded as a reference baseline for subsequent detection.

[0005] (2) Response calibration: Under specific environmental temperature, humidity and working temperature conditions, a target gas of known concentration is introduced into the semiconductor gas sensor, and its steady-state resistance (i.e. response resistance) is recorded. The response value of different semiconductor gas sensors to different gas concentrations is determined by the ratio of the response resistance to the basic resistance. A quantitative relationship between the response value of the semiconductor gas sensor and the gas concentration is established by fitting.

[0006] (3) Real-time signal acquisition and processing: The resistance signal output by the semiconductor gas sensor is continuously acquired, and noise is suppressed by filtering, smoothing or moving average. Then, based on the calibration relationship established in process (2), the resistance signal is converted into gas concentration or risk level information.

[0007] Most existing semiconductor gas sensors are single-channel semiconductor gas sensors, which only use the initially calibrated baseline resistance as a reference for gas concentration calculation. In actual operation, they lack real-time monitoring methods for changes in baseline resistance, resulting in significant limitations in practical applications. Semiconductor gas sensors are affected by factors such as fluctuations in ambient temperature and humidity and the aging of the materials themselves, causing baseline drift (the baseline resistance changes over time). This leads to a shift in the correspondence between the output signal of the semiconductor gas sensor and the target gas concentration, resulting in errors in the detection results and affecting the accuracy and reliability of gas concentration monitoring. This problem is particularly prominent in low-concentration, long-term online monitoring scenarios, severely restricting the widespread application of semiconductor gas sensors in the field of high-precision environmental monitoring.

[0008] Therefore, there is an urgent need to provide a gas detection device and gas concentration detection method that can effectively suppress environmental interference and baseline drift, and improve the long-term stability and detection accuracy of sensors, in order to meet the growing demand for highly reliable and low-drift environmental monitoring. Summary of the Invention

[0009] The purpose of this invention is to provide a gas detection device and a gas concentration detection method to solve the problems existing in the prior art and improve the long-term stability, reliability and response speed of the detection results.

[0010] To achieve the above objectives, the present invention provides the following solution: This invention provides a gas detection device, comprising a first gas sensor, a second gas sensor, a target gas filter unit, a controller, a first temperature control device, and a second temperature control device. The first gas sensor, the target gas filter unit, and the second gas sensor are sequentially connected to form a detection gas path, which is used to connect to a gas delivery device. The first temperature control device, the second temperature control device, the first gas sensor, and the second gas sensor are all connected to the controller. The target gas filter unit is used to remove target gas components from the gas. When the gas delivery device allows air to flow sequentially through the first gas sensor, the target gas filter unit, and the second gas sensor, the first temperature control device ensures that the temperature of the first gas sensor is within its operating temperature range, and the second temperature control device ensures that the temperature of the second gas sensor is within its desorption temperature range to desorb the gas adsorbed on the surface of the gas-sensitive material of the second gas sensor. When the gas delivery device allows air to flow sequentially through the second gas sensor, the target gas filter unit, and the first gas sensor, the second temperature control device ensures that the temperature of the second gas sensor is within its operating temperature range, and the first temperature control device ensures that the temperature of the first gas sensor is within its desorption temperature range to desorb the gas adsorbed on the surface of the gas-sensitive material of the first gas sensor.

[0011] Preferably, the device further includes the gas delivery equipment and a switching valve, the switching valve being connected to the controller; the first gas sensor has a first gas inlet and a second gas inlet; the second gas sensor has a third gas inlet and a fourth gas inlet, and the target gas filtration unit has a fifth gas inlet and a sixth gas inlet; the switching valve has a first type port and at least two second type ports, the first type port being used to connect and communicate with the gas delivery equipment; the two second type ports are respectively connected and communicated with the first gas inlet and the fourth gas inlet, and the first type port of the switching valve can communicate with one of the two second type ports; the fifth gas inlet and the sixth gas inlet are respectively connected and communicated with the second gas inlet and the third gas inlet.

[0012] Preferably, it further includes a first electrically controlled valve and a second electrically controlled valve, wherein the outlet and inlet of the first electrically controlled valve are respectively connected to and communicate with the first gas flow port and the external atmosphere; the outlet and inlet of the second electrically controlled valve are respectively connected to and communicate with the fourth gas flow port and the external atmosphere; both the first electrically controlled valve and the second electrically controlled valve are connected to the controller; the controller is capable of controlling the opening and closing of the first electrically controlled valve and the second electrically controlled valve; the controller is capable of controlling the first type port of the switching valve to communicate with one of the two second type ports.

[0013] Preferably, both the first gas sensor and the second gas sensor include a cap and a detection body. Each cap includes a main body, a baffle, and two inlet / outlet branches. One end of each main body has an opening, and the inlet end of each detection body is located at the opening of the corresponding main body. The two inlet / outlet branches of each cap are fixedly connected to both sides of the corresponding main body. The diameter of each inlet / outlet branch gradually increases from the end away from the corresponding main body to the end closer to the corresponding main body. Each baffle is sealed to the inner wall of the corresponding main body and the inner wall of the end away from the detection body, dividing the inner cavity of the main body into a first cavity and a second cavity. A gap is left between each baffle and the inlet end of the corresponding detection body. Each first cavity and the corresponding second cavity are connected through the gap. The first cavity and the second cavity of each main body are respectively connected to the two inlet / outlet branches of the corresponding main body. The inner wall of each main body is a concave curved surface.

[0014] Preferably, the system also includes a temperature and humidity sensor that is communicatively connected to the controller, the temperature and humidity sensor being used to detect ambient temperature and humidity.

[0015] Preferably, both the first gas sensor and the second gas sensor are semiconductor gas sensors, and the switching valve is a two-position three-way valve.

[0016] The present invention also provides a gas concentration detection method based on the gas detection device described above, comprising the following steps: Calibration is performed by passing the air sequentially through the first gas sensor, the target gas filter unit, and the second gas sensor, or sequentially through the second gas sensor, the target gas filter unit, and the first gas sensor. When the air passes sequentially through the first gas sensor, the target gas filter unit, and the second gas sensor, the first gas sensor acts as a detection sensor, and the second gas sensor acts as a reference sensor. When the air passes sequentially through the second gas sensor, the target gas filter unit, and the first gas sensor, the second gas sensor acts as the detection sensor, and the first gas sensor acts as the reference sensor. The target gas component is removed from the gas by the target gas filter unit. The correspondence between the gas concentration, the response resistance value, and the baseline resistance value is obtained based on the response resistance value obtained by the detection sensor and the baseline resistance value obtained by the reference sensor, thus completing the calibration of the gas detection device. Target gas detection: S1. The gas is sequentially passed through the first gas sensor, the target gas filter unit, and the second gas sensor. The target gas filter unit removes the target gas component from the gas. The first gas sensor obtains a first measured response resistance, and the second gas sensor obtains a first measured baseline resistance. The gas concentration is obtained based on the correspondence between the gas concentration obtained during calibration and the response resistance value and the baseline resistance value. The first temperature control device controls the temperature of the first gas sensor to keep it within the operating temperature range, and the second temperature control device controls the temperature of the second gas sensor to keep it within the desorption temperature range, so as to desorb the gas adsorbed on the surface of the gas-sensitive material of the second gas sensor. S2. The gas is sequentially passed through the second gas sensor, the target gas filter unit, and the first gas sensor. The target gas filter unit removes the target gas component from the gas. The second gas sensor obtains a second measured response resistance, and the first gas sensor obtains a second measured baseline resistance. The gas concentration is obtained based on the correspondence between the gas concentration obtained during calibration and the response resistance value and the baseline resistance value. The second temperature control device controls the temperature of the second gas sensor to keep it within the operating temperature range. The first temperature control device controls the temperature of the first gas sensor to keep it within the desorption temperature range to desorb the gas adsorbed on the surface of the gas-sensitive material of the first gas sensor. S3. Repeat steps S1 and S2, using the first gas sensor and the second gas sensor alternately as the detection sensors to detect the target gas concentration.

[0017] The present invention also provides a gas concentration detection method, wherein the gas concentration detection method is applied to the above-mentioned gas detection device, and the gas concentration detection method includes: Obtain the measured baseline resistance, measured response resistance, ambient temperature, and ambient humidity at the current moment; The measured baseline resistance is subjected to a first-order low-pass filter to obtain the baseline resistance estimate. Based on the measured response resistance and the baseline resistance estimate, determine whether the gas response has started; If the gas response begins, the measured baseline resistance and the measured response resistance are differentially processed to obtain a characteristic response signal characterizing the gas concentration. Based on the characteristic response signal and combined with the pre-established concentration fitting model, the initial concentration value of the target gas is determined. Based on the ambient temperature and the ambient humidity, the initial concentration value is compensated and corrected, and the compensated gas concentration value is smoothed to obtain the final concentration value of the target gas. If the gas response has not started, the system will return "Get the measured baseline resistance, measured response resistance, ambient temperature and ambient humidity at the current moment".

[0018] Preferably, the pre-established concentration fitting model is: ; in, Let t be the initial concentration of the target gas at time t; The characteristic response signal at time t; The slope is obtained by fitting a pre-experimental model of an actual semiconductor sensor. These are constants obtained by fitting based on preliminary experiments with actual semiconductor sensors.

[0019] Preferably, the initial concentration value is compensated and corrected based on the ambient temperature and humidity, and the compensated gas concentration value is smoothed to obtain the final concentration value of the target gas, specifically including: Using formula The initial concentration value is compensated and corrected to obtain the compensated gas concentration value; wherein, The gas concentration value after compensation at time t; Let t be the initial concentration of the target gas at time t; The response resistance at a specific temperature; The ambient temperature; The gas temperature used to pre-establish the concentration fitting model; The response resistance at a specific humidity level; For ambient humidity; The gas humidity when the concentration fitting model is established in advance; Using formula The compensated gas concentration value is smoothed to obtain the final concentration value of the target gas; wherein, Let t be the final concentration value of the target gas at time t; These are the filter coefficients; The final concentration value of the target gas at time t-1.

[0020] The present invention achieves the following technical effects compared to the prior art: This invention provides a gas detection device and a gas concentration detection method, comprising a first gas sensor, a second gas sensor, a target gas filter unit, a controller, a first temperature control device, and a second temperature control device. The first gas sensor, the target gas filter unit, and the second gas sensor are sequentially connected to form a detection gas path, which is used to connect to a gas delivery device. The first temperature control device, the second temperature control device, the first gas sensor, and the second gas sensor are all connected to the controller. The target gas filter unit is used to remove target gas components from the gas. When the gas delivery device allows air to flow sequentially through the first gas sensor, the target gas filter unit, and the second gas sensor, the first temperature control device ensures that the temperature of the first gas sensor is within its operating temperature range, and the second temperature control device ensures that the temperature of the second gas sensor is within its desorption temperature range to desorb the gas adsorbed on the surface of the gas-sensitive material of the second gas sensor. When the gas delivery device allows air to flow sequentially through the second gas sensor, the target gas filter unit, and the first gas sensor, the second temperature control device ensures that the temperature of the second gas sensor is within its operating temperature range, and the first temperature control device ensures that the temperature of the first gas sensor is within its desorption temperature range to desorb the gas adsorbed on the surface of the gas-sensitive material of the first gas sensor.

[0021] Under the action of the gas conveying equipment, air can sequentially pass through the first gas sensor, the target gas filter unit, and the second gas sensor, or sequentially pass through the second gas sensor, the target gas filter unit, and the first gas sensor. When air sequentially passes through the first gas sensor, the target gas filter unit, and the second gas sensor, the first gas sensor is the detection sensor and the second gas sensor is the reference sensor. When air sequentially passes through the second gas sensor, the target gas filter unit, and the first gas sensor, the second gas sensor is the detection sensor and the first gas sensor is the reference sensor. Before detecting the target gas, the gas detection device is calibrated: either using a first gas sensor as the detection sensor and a second gas sensor as the reference sensor, or using a second gas sensor as the detection sensor and a first gas sensor as the reference sensor. The gas passes sequentially through the detection sensor, the target gas filter unit, and the reference sensor. The heating temperature of the temperature control device heating the detection sensor is set to the optimal operating temperature (first operating temperature), and the heating temperature of the temperature control device heating the reference sensor is set to a higher heating temperature (second operating temperature). The target gas component is removed from the gas by the target gas filter unit without significantly altering the gas's temperature, humidity, or flow rate. This ensures that the gas contacted by the reference sensor is essentially free of the target gas, thereby outputting a reference signal reflecting environmental changes and the sensor's own state. The correspondence between gas concentration and the response resistance value and baseline resistance value is obtained based on the response resistance value acquired by the detection sensor and the baseline resistance value acquired by the reference sensor. When detecting a target gas, the first gas sensor and the second gas sensor are used alternately as detection sensors to detect the target gas concentration. Taking the first gas sensor as the detection sensor as an example, the target gas concentration detection method includes: passing the gas sequentially through the first gas sensor, the target gas filter unit, and the second gas sensor; obtaining the measured response resistance through the first gas sensor; and obtaining the gas concentration based on the correspondence between the gas concentration, the response resistance value, and the baseline resistance value obtained during calibration. This invention introduces a reference detection mechanism by constructing a dual-channel detection structure, which reduces interference caused by environmental changes and long-term sensor operation, and improves the stability and reliability of the detection results. Simultaneously with target gas detection, the heating temperature of the temperature control device for heating the detection sensor is set to the optimal operating temperature (first operating temperature) to obtain a highly sensitive response to the target gas; the heating temperature of the temperature control device for heating the reference sensor is set to a higher heating temperature (second operating temperature) to accelerate the desorption process of residual gas on the surface of the gas-sensitive material of the reference sensor, achieving rapid recovery. After the gas path is switched, the original detection sensor becomes a reference sensor and is heated to desorb, while the original reference sensor becomes a detection sensor and is cooled to the optimal operating temperature. This achieves the alternating switching of sensor operating states, improving the overall response speed and long-term stability of the system. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the gas detection device provided in Example 1; Figure 2 This is a schematic diagram of the structure of the first gas sensor and the second gas sensor provided in Example 1; Figure 3 Cross-sectional views of the first gas sensor and the second gas sensor provided in Embodiment 1; In the diagram: 100, Gas detection device; 1, First gas sensor; 2, Second gas sensor; 3, Switching valve; 4, Target gas filtration unit; 5, Gas delivery equipment; 6, First electrically controlled valve; 7, Second electrically controlled valve; 8, Pipe cap; 801, Main body; 802, Baffle; 803, Inlet and outlet gas branches; 804, Concave curved surface; 9, Detection body; 10, Adapter plate; 11, Temperature and humidity sensor. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that in the description of this invention, the terms "upper," "lower," "left," "right," "inner," "outer," "front," "rear," "center," "longitudinal," "transverse," "length," "width," "thickness," "vertical," "horizontal," "top," "bottom," "clockwise," and "counterclockwise," etc., indicating directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Additionally, it should be noted that in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] The purpose of this invention is to provide a gas detection device and a gas concentration detection method to solve the problems existing in the prior art and improve the long-term stability, reliability and response speed of the detection results.

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Example 1 like Figures 1-3As shown, this embodiment provides a gas detection device 100, including a first gas sensor 1, a second gas sensor 2, a target gas filter unit 4, a controller, a first temperature control device, and a second temperature control device. The first gas sensor 1, the target gas filter unit 4, and the second gas sensor 2 are sequentially connected to form a detection gas path, which is used to connect to a gas delivery device 5. The first temperature control device, the second temperature control device, the first gas sensor 1, and the second gas sensor 2 are all connected to the controller. The target gas filter unit 4 is used to remove the target gas component from the gas. When the gas delivery device 5 causes air to flow sequentially through the first gas sensor 1, the target gas filter unit 4, and the second gas sensor 2, the detection gas path is used to connect to a gas delivery device 5. When the second gas sensor 2 is in operation, the first temperature control device can keep the temperature of the first gas sensor 1 within its operating temperature range, and the second temperature control device can keep the temperature of the second gas sensor 2 within its desorption temperature range to desorb the gas adsorbed on the surface of the gas-sensitive material of the second gas sensor 2; when the gas conveying device 5 makes air flow sequentially through the second gas sensor 2, the target gas filter unit 4 and the first gas sensor 1, the second temperature control device can keep the temperature of the second gas sensor 2 within its operating temperature range, and the first temperature control device can keep the temperature of the first gas sensor 1 within its desorption temperature range to desorb the gas adsorbed on the surface of the gas-sensitive material of the first gas sensor 1.

[0029] Under the action of the gas conveying device 5, air can sequentially pass through the first gas sensor 1, the target gas filter unit 4, and the second gas sensor 2, or sequentially pass through the second gas sensor 2, the target gas filter unit 4, and the first gas sensor 1. When air sequentially passes through the first gas sensor 1, the target gas filter unit 4, and the second gas sensor 2, the first gas sensor 1 is the detection sensor and the second gas sensor 2 is the reference sensor. When air sequentially passes through the second gas sensor 2, the target gas filter unit 4, and the first gas sensor 1, the second gas sensor 2 is the detection sensor and the first gas sensor 1 is the reference sensor. Before detecting the target gas, the gas detection device 100 is calibrated: either using the first gas sensor 1 as the detection sensor and the second gas sensor 2 as the reference sensor, or using the second gas sensor 2 as the detection sensor and the first gas sensor 1 as the reference sensor, the gas passes sequentially through the detection sensor, the target gas filter unit 4, and the reference sensor. The heating temperature of the temperature control device heating the detection sensor is set to the optimal operating temperature (first operating temperature), and the heating temperature of the temperature control device heating the reference sensor is set to a higher heating temperature (second operating temperature). The target gas component is removed from the gas by the target gas filter unit 4 without significantly changing the gas temperature, humidity, or flow rate, ensuring that the gas contacted by the reference sensor is essentially free of the target gas, thereby outputting a reference signal reflecting environmental changes and the sensor's own state. The correspondence between the gas concentration and the response resistance value and the baseline resistance value is obtained based on the response resistance value acquired by the detection sensor and the baseline resistance value acquired by the reference sensor. When detecting the target gas, the first gas sensor 1 and the second gas sensor 2 are used alternately as detection sensors to detect the target gas concentration. Taking the first gas sensor 1 as the detection sensor as an example, the target gas concentration detection method includes: passing the gas sequentially through the first gas sensor 1, the target gas filter unit 4, and the second gas sensor 2; removing the target gas component from the gas through the target gas filter unit 4; obtaining the measured response resistance through the first gas sensor 1; obtaining the measured baseline resistance through the second gas sensor 2; and obtaining the gas concentration based on the correspondence between the gas concentration, response resistance value, and baseline resistance value obtained during calibration. This embodiment introduces a reference detection mechanism by constructing a dual-channel detection structure, reducing interference caused by environmental changes and long-term sensor operation, and improving the stability and reliability of the detection results. Simultaneously with target gas detection, the heating temperature of the temperature control device for heating the detection sensor is set to the optimal operating temperature (first operating temperature) to obtain a highly sensitive response to the target gas; the heating temperature of the temperature control device for heating the reference sensor is set to a higher heating temperature (second operating temperature) to accelerate the desorption process of residual gas on the surface of the gas-sensitive material of the reference sensor, achieving rapid recovery.After the gas path switching, the original detection sensor becomes a reference sensor and is heated to desorb, while the original reference sensor becomes a detection sensor and is cooled to its optimal operating temperature, thus achieving alternating switching of sensor operating states. In practical applications, gas sensors are typically exposed to environments containing target gases for extended periods, leading to continuous adsorption and accumulation of gas molecules on the surface of the gas-sensitive material. When the adsorbed gas molecules cannot be desorbed promptly and completely, or when the surface of the gas-sensitive material is contaminated by other impurities, the electrical characteristics of the gas sensor change over time, resulting in reduced operational stability. Furthermore, when the gas concentration in the detection environment changes, incomplete desorption of adsorbed gases from the gas-sensitive material surface makes it difficult for the gas sensor output signal to recover to its initial state promptly, easily causing response lag or residual effects, which in turn affects the repeatability and accuracy of the detection results. This embodiment solves this problem, improving the overall response speed and long-term stability of the system.

[0030] In some embodiments, the system further includes a gas delivery device 5 and a switching valve 3, the switching valve 3 being connected to a controller; a first gas sensor 1 having a first gas outlet and a second gas outlet; a second gas sensor 2 having a third gas outlet and a fourth gas outlet; and a target gas filter unit 4 having a fifth gas outlet and a sixth gas outlet; the switching valve 3 having a first type of port and at least two second type of ports, the first type of port being used to connect and communicate with the gas delivery device 5; the two second type of ports being respectively connected and communicated with the first gas outlet and the fourth gas outlet, and the first type of port of the switching valve 3 being able to communicate with one of the two second type of ports; and the fifth and sixth gas outlets being respectively connected and communicated with the second and third gas outlets. By switching the gas flow direction through the switching valve 3, the alternating switching of the sensor's operating state is achieved, resulting in a simple structure and easy control.

[0031] In some embodiments, the system further includes a first electrically controlled valve 6 and a second electrically controlled valve 7. The outlet and inlet of the first electrically controlled valve 6 are connected and communicate with a first gas flow port and the external atmosphere, respectively. The outlet and inlet of the second electrically controlled valve 7 are connected and communicate with a fourth gas flow port and the external atmosphere, respectively. Both the first electrically controlled valve 6 and the second electrically controlled valve 7 are connected to a controller. The controller can control the opening and closing of the first electrically controlled valve 6 and the second electrically controlled valve 7. The controller can control the connection between the first type port of the switching valve 3 and one of the two second type ports. This embodiment adopts a dual-channel structure, and the switching between the detection channel and the reference channel is realized through the coordinated control of the controller, the first electrically controlled valve 6, the second electrically controlled valve 7 and the switching valve 3. The gas delivery device 5 can be a vacuum pump or a sampling pump, actively drawing in the gas from the environment to be tested to pass through the gas chamber of the gas sensor. Specifically, it operates as follows: In one operating state, the controller controls the first channel of the switching valve 3 to open synchronously with the first solenoid valve 6, while the second solenoid valve 7 closes. Driven by the gas delivery device 5, the gas flows sequentially through the first solenoid valve 6, the first gas sensor 1, the target gas filter unit 4, the second gas sensor 2, the first channel of the switching valve 3, and the gas delivery device 5 before being discharged. The first gas sensor 1 serves as a detection sensor to detect changes in the target gas concentration, and the second gas sensor 2 serves as a reference sensor. In another operating state, the controller controls the second channel of the switching valve 3 to open synchronously with the second solenoid valve 7, while the first solenoid valve 6 closes. The gas flow direction is switched, and the gas flows sequentially through the second solenoid valve 7, the second gas sensor 2, the target gas filter unit 4, the first gas sensor 1, the second channel of the switching valve 3, and the gas delivery device 5 before being discharged. The second gas sensor 2 serves as a detection sensor, and the first gas sensor 1 serves as a reference sensor. By employing the aforementioned alternating switching method, the detection channel and reference channel can be dynamically interchanged, thereby reducing the impact of drift and individual differences generated during long-term operation of a single sensor on the detection results. In one exemplary embodiment, the two detection paths are switched periodically during the detection process, with the specific switching time determined based on the response time of the specific gas sensor.

[0032] In some embodiments, both the first and second temperature control devices include heating units. Independent adapter plates 10 are respectively provided in the first gas sensor 1 and the second gas sensor 2. The first and second temperature control devices are integrated with the adapter plates 10. The adapter plate 10 has four pins, two of which can be used to heat the gas sensors by applying current / voltage, and the other two pins can be used to acquire the resistance / voltage of the gas sensors. The independent adapter plates 10 are used to achieve independent acquisition of sensor signals and independent control of sensor heating temperature. In one exemplary embodiment, the heating temperature of the first and second temperature control devices can be adjusted by adjusting the voltage of the adapter plate 10.

[0033] In some embodiments, both the first gas sensor 1 and the second gas sensor 2 include a cap 8 and a detection body 9. Each cap 8 includes a main body 801, a baffle 802, and two inlet / outlet branches 803. One end of the main body 801 has an opening, and the inlet end of the detection body 9 is located at the opening of the main body 801. The two inlet / outlet branches 803 are respectively fixedly connected to both sides of the main body 801. From the end of each inlet / outlet branch 803 away from the main body 801 to the end closer to the main body 801, the inlet / outlet branches 803... The diameter gradually increases; each baffle 802 is sealed to the inner wall of the corresponding main body 801 and the inner wall of the end away from the detection body 9, and divides the inner cavity of the main body 801 into a first cavity and a second cavity. There is a gap between each baffle 802 and the air inlet end of the detection body 9. Each first cavity and the corresponding second cavity are connected through the gap. The first cavity and the second cavity of each main body 801 are respectively connected to the two air inlet and outlet branches 803 of the corresponding main body 801. The inner wall of each main body 801 is a concave curved surface 804. In this embodiment, the inlet and outlet air passages 803 are designed with a variable diameter to reduce the gas flow rate. The curved design of the inner wall of the main body 801 allows the airflow to flow downwards evenly and reduces the gas flow rate. The baffle 802 leaves a gap only between itself and the inlet end of the detection body 9, which restricts the flow path of the airflow. This causes the airflow to flow from the end away from the detection body 9 to the end closer to the detection body 9, and through the gap between the baffle 802 and the detection body 9, it flows from the first cavity into the second cavity, or from the second cavity into the first cavity. This forces the gas-sensitive material to flow on the surface, increasing the probability of contact between the gas and the surface of the gas sensor. This embodiment incorporates a cap 8 structure at the gas sensor inlet, which functions to slow down, guide, and redistribute the gas. This slows down and redistributes the high-speed airflow entering the sensing region before it reaches the surface of the gas-sensitive material. This transforms the high-speed, disordered flow into a low-speed, uniform, controlled flow along the surface of the gas-sensitive material. This structure significantly increases the effective residence time of gas molecules on the gas-sensitive material surface and the probability of them participating in the adsorption reaction, thereby improving the capture efficiency of low-concentration gases, reducing local eddies or stagnant zones, and ensuring uniform gas distribution. Ultimately, this enhances the capture efficiency of the target gas by the gas-sensitive material per unit time. Compared to the natural diffusion mode, this embodiment achieves a faster response build-up process and a higher sensing response value under low-concentration conditions.

[0034] In some embodiments, the baffle 802 is disposed in the middle position of the main body 801, and the two air inlet and outlet branches 803 are symmetrically arranged about the baffle 802.

[0035] In some embodiments, the detection body 9 includes a gas-sensitive material, electrodes, etc. The connection relationships between the gas-sensitive material, electrodes, heating unit, and cap 8 are all prior art and will not be described in detail here. A sealing structure such as a sealing plate is provided at the contact position between the cap 8 and the detection body 9.

[0036] In some embodiments, the first gas sensor 1 and the second gas sensor 2 are both semiconductor gas sensors, and the switching valve 3 is a two-position three-way valve. The first electrically controlled valve 6 and the second electrically controlled valve 7 are both solenoid valves. The gas delivery device 5 is a miniature gas pump.

[0037] In some embodiments, a temperature and humidity sensor 11 is also included, which is communicatively connected to the controller and is used to detect ambient temperature and humidity.

[0038] This embodiment provides a gas detection device 100 with a dual-channel structure, gas flow regulation, and independent temperature control. Through structural design and coordinated control of operating parameters, it solves the common problems of insufficient response, poor stability, and susceptibility to environmental interference in low-concentration detection and long-term operation of gas detection devices 100. The gas detection device 100 is preferably a semiconductor gas sensor, suitable for real-time monitoring and long-term continuous detection of gases, especially suitable for applications requiring high detection sensitivity, detection limit, stability, and long-term operational reliability. It is widely applicable in various technical fields, such as indoor environmental quality monitoring, industrial environmental gas leak early warning, gas safety monitoring in public places and confined spaces, online monitoring of environmental pollutants, and related scientific research experiments and instruments.

[0039] Example 2 This embodiment provides a gas concentration detection method based on the gas detection device 100 in Embodiment 1, including the following steps: Calibration is performed by sequentially passing air through the first gas sensor 1, the target gas filter unit 4, and the second gas sensor 2, or sequentially passing air through the second gas sensor 2, the target gas filter unit 4, and the first gas sensor 1. When air sequentially passes through the first gas sensor 1, the target gas filter unit 4, and the second gas sensor 2, the first gas sensor 1 acts as the detection sensor, and the second gas sensor 2 acts as the reference sensor. When air sequentially passes through the second gas sensor 2, the target gas filter unit 4, and the first gas sensor 1, the second gas sensor 2 acts as the detection sensor, and the first gas sensor 1 acts as the reference sensor. The target gas component is removed from the gas by the target gas filter unit 4. The correspondence between the gas concentration and the response resistance value and the baseline resistance value is obtained based on the response resistance value obtained by the detection sensor and the baseline resistance value obtained by the reference sensor. Target gas detection: S1. The gas is sequentially passed through the first gas sensor 1, the target gas filter unit 4, and the second gas sensor 2. The target gas filter unit 4 removes the target gas component from the gas. The first measured response resistance is obtained through the first gas sensor 1, and the first measured baseline resistance is obtained through the second gas sensor 2. The gas concentration is obtained based on the correspondence between the gas concentration obtained during calibration and the response resistance value and the baseline resistance value. The temperature of the first gas sensor 1 is controlled by the first temperature control device to keep the first gas sensor 1 within its operating temperature range. The temperature of the second gas sensor 2 is controlled by the second temperature control device to keep the temperature of the second gas sensor 2 within its desorption temperature range so as to desorb the gas adsorbed on the surface of the gas-sensitive material of the second gas sensor 2, thus completing the calibration of the gas detection device 100. S2. The gas is sequentially passed through the second gas sensor 2, the target gas filter unit 4, and the first gas sensor 1. The target gas filter unit 4 removes the target gas components from the gas. The second gas sensor 2 obtains the second measured response resistance, and the first gas sensor 1 obtains the second measured baseline resistance. The gas concentration is obtained based on the correspondence between the gas concentration obtained during calibration and the response resistance value and the baseline resistance value. The temperature of the second gas sensor 2 is controlled by the second temperature control device to keep the second gas sensor 2 within its operating temperature range. The temperature of the first gas sensor 1 is controlled by the first temperature control device to keep the temperature of the first gas sensor 1 within its desorption temperature range so as to desorb the gas adsorbed on the surface of the gas-sensitive material of the first gas sensor 1. S3. Repeat steps S1 and S2, using the first gas sensor 1 and the second gas sensor 2 alternately as detection sensors to detect the concentration of the target gas.

[0040] This embodiment constructs detection and reference channels with similar physical structures and consistent gas introduction paths but different functional divisions to suppress common interference factors such as environmental changes, background gas fluctuations, and device aging, providing a stable foundation for subsequent differential signal processing.

[0041] This embodiment, based on a dual-channel structure, applies different operating temperatures to the detection channel and the reference channel: the detection channel is maintained at a lower optimal operating temperature to ensure the sensitivity of gas adsorption and reaction processes; the reference channel is maintained at a higher desorption temperature to accelerate the desorption process of adsorbates on the surface of the gas-sensitive material. This temperature-differentiated design helps shorten the sensor's recovery time, reduce signal hysteresis, achieve a balance between rapid response and rapid recovery, and improve response repeatability during continuous detection. Because the reference channel can continuously desorb at a higher temperature and provide a stable reference signal, this embodiment, compared to traditional sensors, reduces the reliance on frequent heating cleaning or manual calibration during long-term operation. This improves the long-term stability of the system from both structural and operational mechanism perspectives, making it more suitable for long-term online or unattended monitoring applications. Existing semiconductor gas sensors mostly adopt a single-channel structure. In actual use, in order to restore the gas sensor to its initial working state, it is usually necessary to perform a pre-processing operation on the sensor before each detection. This involves removing adsorbates from the surface of the gas-sensitive material by continuous heating. This process often takes a long time to complete, greatly extending the sensor's recovery cycle and making it difficult to meet the application requirements for high continuity, real-time performance, and long-term reliability.

[0042] It should be noted that during the calibration and testing phases, the detection sensor and the reference sensor are identical in all environmental parameters except for the gas composition detected (the gas contacted by the reference sensor has the target gas removed) and temperature; the detection sensor is heated at the same temperature during the calibration and testing phases, and the reference sensor is heated at the same temperature during the calibration and testing phases.

[0043] Example 3 This embodiment provides a gas concentration detection method, which is applied to the gas detection device 100 of Embodiment 1. The gas concentration detection method includes: Step 101: Obtain the measured baseline resistance, measured response resistance, ambient temperature, and ambient humidity at the current moment.

[0044] Step 102: Perform a first-order low-pass filter on the measured baseline resistance to obtain the baseline resistance estimate.

[0045] Step 103: Determine whether the gas response has started based on the measured response resistance and the baseline resistance estimate.

[0046] During signal acquisition, the controller acquires the output resistance signals of the first gas sensor 1 and the second gas sensor 2 in real time through the adapter board 10, and preprocesses the acquired resistance signals. The preprocessing process is as follows: 1) Processing of measured baseline resistance: First-order low-pass filtering is used to suppress the influence of high-frequency noise and transient disturbances on the test results.

[0047] .

[0048] .

[0049] .

[0050] in, Here is the baseline resistance estimate at time t; This is the baseline resistance estimate at time t-1; Let be the measured baseline resistance at time t; These are the filter coefficients; This refers to the sensor response time. This is the sensor's own cutoff frequency; This is the filter cutoff frequency, which is typically 2-5 times the sensor's own cutoff frequency.

[0051] 2) Determining the initial threshold of the detection signal: .

[0052] .

[0053] in, Let be the measured response resistance at time t; This represents the average response resistance after m consecutive data acquisitions. The baseline resistance (baseline resistance estimate) is determined after processing the real-time baseline resistance. The response begins when all of the above conditions are met.

[0054] Step 104: If the gas response begins, perform differential processing on the measured baseline resistance and the measured response resistance to obtain the characteristic response signal characterizing the gas concentration.

[0055] In this embodiment, the response value is differentially processed to eliminate the influence of the initial resistance difference between different sensors.

[0056] Normalized response value: .

[0057] in, This is the normalized response value of the measured baseline resistance.

[0058] Subsequently, the resistance signal response values ​​of the first gas sensor 1 and the second gas sensor 2 are differentially processed to obtain a response signal (characteristic response signal) that characterizes the response features of the target gas, further reducing the drift error caused by individual device differences, baseline drift, and long-term operation.

[0059] .

[0060] in, It is a characteristic response signal; To detect the sensor's response to the target gas at time t (i.e., the normalized response value after measuring the response resistance); This is the response value of the reference sensor to the reference gas at time t (i.e., the response value after normalization of the measured baseline resistance).

[0061] .

[0062] .

[0063] in, The estimated response resistance at time t; This is the estimated response resistance at time t-1.

[0064] Step 105: Determine the initial concentration value of the target gas based on the characteristic response signal and the pre-established concentration fitting model.

[0065] As an optional implementation method, the pre-established concentration fitting model is as follows: ; in, Let t be the initial concentration of the target gas at time t; The characteristic response signal at time t; The slope is obtained by fitting a pre-experimental model of an actual semiconductor sensor. These are constants obtained by fitting based on preliminary experiments with actual semiconductor sensors.

[0066] In this embodiment, the controller calculates the real-time concentration value (initial concentration value) of the target gas based on the obtained characteristic response signal and according to the pre-established correspondence or fitting model between the target gas concentration and the response signal (pre-established concentration fitting model).

[0067] Step 106: Based on the ambient temperature and humidity, compensate and correct the initial concentration value, and smooth the compensated gas concentration value to obtain the final concentration value of the target gas.

[0068] As an optional implementation, step 106 specifically includes: Step 106-1: Using the formula The initial concentration value is compensated and corrected to obtain the compensated gas concentration value; where, The gas concentration value after compensation at time t; Let t be the initial concentration of the target gas at time t; The response resistance at a specific temperature; The ambient temperature; The gas temperature used to pre-establish the concentration fitting model; The response resistance at a specific humidity level; For ambient humidity; The gas humidity when a concentration fitting model is pre-established.

[0069] In this embodiment, the controller compensates and corrects the real-time concentration value based on the ambient temperature and humidity information detected by the temperature and humidity sensor 11, so as to reduce the impact of changes in ambient temperature and humidity on the detection results.

[0070] Step 106-2: Using the formula The compensated gas concentration value is smoothed to obtain the final concentration value of the target gas; where, Let be the final concentration of the target gas at time t; These are the filter coefficients, and the method for determining their values ​​is the same. ; This represents the final concentration of the target gas at time t-1.

[0071] In this embodiment, the compensated gas concentration value is smoothed to improve the stability and continuity of the output results, and finally outputs the real-time concentration detection result of the target gas.

[0072] In addition, during signal acquisition and processing, the controller also dynamically compensates and adjusts the heating temperature of the first gas sensor 1 and the second gas sensor 2 based on the ambient temperature signal obtained by the temperature and humidity sensor 11, so that the two gas-sensitive materials are always maintained at their respective optimal operating temperature and desorption temperature under different environmental conditions.

[0073] If the gas response has not started, return to "Step 101".

[0074] By performing differential, ratio, or combination operations on the output signals of the detection channel and the reference channel, the influence of temperature and humidity changes, individual sensor differences, and aging drift on the detection results is effectively reduced, thereby improving the stability and reliability of the output results.

[0075] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A gas detection device, characterized in that, The system includes a first gas sensor, a second gas sensor, a target gas filter unit, a controller, a first temperature control device, and a second temperature control device. The first gas sensor, the target gas filter unit, and the second gas sensor are sequentially connected to form a detection gas path, which is used to connect to a gas delivery device. The first temperature control device, the second temperature control device, the first gas sensor, and the second gas sensor are all connected to the controller. The target gas filter unit is used to remove the target gas component from the gas. When the gas delivery device allows air to flow sequentially through the first gas sensor, the target gas filter unit, and the second gas sensor for calibration or detection, the first temperature control device... The first temperature control device enables the temperature of the first gas sensor to be within its operating temperature range, and the second temperature control device enables the temperature of the second gas sensor to be within its desorption temperature range to desorb the gas adsorbed on the surface of the gas-sensitive material of the second gas sensor. When the gas delivery device causes the air to flow sequentially through the second gas sensor, the target gas filter unit, and the first gas sensor for calibration or detection, the second temperature control device enables the temperature of the second gas sensor to be within the operating temperature range, and the first temperature control device enables the temperature of the first gas sensor to be within the desorption temperature range to desorb the gas adsorbed on the surface of the gas-sensitive material of the first gas sensor.

2. The gas detection device according to claim 1, characterized in that, It also includes the gas delivery device and a switching valve, the switching valve being connected to the controller; the first gas sensor has a first gas outlet and a second gas outlet; the second gas sensor has a third gas outlet and a fourth gas outlet, and the target gas filtration unit has a fifth gas outlet and a sixth gas outlet; the switching valve has a first type port and at least two second type ports, the first type port being used to connect and communicate with the gas delivery device; the two second type ports are respectively connected and communicated with the first gas outlet and the fourth gas outlet, and the first type port of the switching valve can communicate with one of the two second type ports; the fifth gas outlet and the sixth gas outlet are respectively connected and communicated with the second gas outlet and the third gas outlet.

3. The gas detection device according to claim 2, characterized in that, It also includes a first electrically controlled valve and a second electrically controlled valve. The outlet and inlet of the first electrically controlled valve are respectively connected to and communicate with the first gas flow port and the external atmosphere. The outlet and inlet of the second electrically controlled valve are respectively connected to and communicate with the fourth gas flow port and the external atmosphere. Both the first electrically controlled valve and the second electrically controlled valve are connected to the controller. The controller can control the opening and closing of the first electrically controlled valve and the second electrically controlled valve. The controller can control the connection of the first type port of the switching valve to one of the two second type ports.

4. The gas detection device according to claim 2, characterized in that, Both the first gas sensor and the second gas sensor include a cap and a detection body. Each cap includes a main body, a baffle, and two inlet / outlet branches. One end of each main body has an opening, and the inlet end of each detection body is located at the opening of the corresponding main body. The two inlet / outlet branches of each cap are fixedly connected to both sides of the corresponding main body. The diameter of each inlet / outlet branch gradually increases from the end away from the corresponding main body to the end closer to the corresponding main body. Each baffle is sealed to the inner wall of the corresponding main body and the inner wall of the end away from the detection body, dividing the inner cavity of the main body into a first cavity and a second cavity. A gap is left between each baffle and the inlet end of the corresponding detection body. Each first cavity and the corresponding second cavity are connected through the gap. The first cavity and the second cavity of each main body are respectively connected to the two inlet / outlet branches of the corresponding main body. The inner wall of each main body is a concave curved surface.

5. The gas detection device according to claim 1, characterized in that, It also includes a temperature and humidity sensor that is communicatively connected to the controller, the temperature and humidity sensor being used to detect ambient temperature and humidity.

6. The gas detection device according to claim 4, characterized in that, Both the first gas sensor and the second gas sensor are semiconductor gas sensors, and the switching valve is a two-position three-way valve.

7. A method for detecting gas concentration based on the gas detection device according to any one of claims 1 to 6, characterized in that, Includes the following steps: Calibration is performed by passing the air sequentially through the first gas sensor, the target gas filter unit, and the second gas sensor, or sequentially through the second gas sensor, the target gas filter unit, and the first gas sensor. When the air passes sequentially through the first gas sensor, the target gas filter unit, and the second gas sensor, the first gas sensor acts as a detection sensor, and the second gas sensor acts as a reference sensor. When the air passes sequentially through the second gas sensor, the target gas filter unit, and the first gas sensor, the second gas sensor acts as the detection sensor, and the first gas sensor acts as the reference sensor. The target gas component is removed from the gas by the target gas filter unit. The correspondence between the gas concentration, the response resistance value, and the baseline resistance value is obtained based on the response resistance value obtained by the detection sensor and the baseline resistance value obtained by the reference sensor, thus completing the calibration of the gas detection device. Target gas detection: S1. The gas is sequentially passed through the first gas sensor, the target gas filter unit, and the second gas sensor. The target gas filter unit removes the target gas component from the gas. The first gas sensor obtains a first measured response resistance, and the second gas sensor obtains a first measured baseline resistance. The gas concentration is obtained based on the correspondence between the gas concentration obtained during calibration and the response resistance value and the baseline resistance value. The first temperature control device controls the temperature of the first gas sensor to keep it within the operating temperature range, and the second temperature control device controls the temperature of the second gas sensor to keep it within the desorption temperature range, so as to desorb the gas adsorbed on the surface of the gas-sensitive material of the second gas sensor. S2. The gas is sequentially passed through the second gas sensor, the target gas filter unit, and the first gas sensor. The target gas filter unit removes the target gas component from the gas. The second gas sensor obtains a second measured response resistance, and the first gas sensor obtains a second measured baseline resistance. The gas concentration is obtained based on the correspondence between the gas concentration obtained during calibration and the response resistance value and the baseline resistance value. The second temperature control device controls the temperature of the second gas sensor to keep it within the operating temperature range. The first temperature control device controls the temperature of the first gas sensor to keep it within the desorption temperature range to desorb the gas adsorbed on the surface of the gas-sensitive material of the first gas sensor. S3. Repeat steps S1 and S2, using the first gas sensor and the second gas sensor alternately as the detection sensors to detect the target gas concentration.

8. A method for detecting gas concentration, characterized in that, The gas concentration detection method described herein is applied to the gas detection device according to any one of claims 1-6, and the gas concentration detection method comprises: Obtain the measured baseline resistance, measured response resistance, ambient temperature, and ambient humidity at the current moment; The measured baseline resistance is subjected to a first-order low-pass filter to obtain the baseline resistance estimate. Based on the measured response resistance and the baseline resistance estimate, determine whether the gas response has started; If the gas response begins, the measured baseline resistance and the measured response resistance are differentially processed to obtain a characteristic response signal characterizing the gas concentration. Based on the characteristic response signal and combined with the pre-established concentration fitting model, the initial concentration value of the target gas is determined. Based on the ambient temperature and the ambient humidity, the initial concentration value is compensated and corrected, and the compensated gas concentration value is smoothed to obtain the final concentration value of the target gas. If the gas response has not started, return "Get the measured baseline resistance, measured response resistance, ambient temperature and ambient humidity at the current moment".

9. The gas concentration detection method according to claim 8, characterized in that, The pre-established concentration fitting model is as follows: ； in, Let t be the initial concentration of the target gas at time t; The characteristic response signal at time t; The slope is obtained by fitting a pre-experimental model of an actual semiconductor sensor. These are constants obtained by fitting based on preliminary experiments with actual semiconductor sensors.

10. The gas concentration detection method according to claim 8, characterized in that, Based on the ambient temperature and humidity, the initial concentration value is compensated and corrected, and the compensated gas concentration value is smoothed to obtain the final concentration value of the target gas. Specifically, this includes: Using formula The initial concentration value is compensated and corrected to obtain the compensated gas concentration value; wherein, The gas concentration value after compensation at time t; Let t be the initial concentration of the target gas at time t; The response resistance at a specific temperature; The ambient temperature; The gas temperature used to pre-establish the concentration fitting model; The response resistance at a specific humidity level; For ambient humidity; The gas humidity when the concentration fitting model is established in advance; Using formula The compensated gas concentration value is smoothed to obtain the final concentration value of the target gas; wherein, Let t be the final concentration value of the target gas at time t; These are the filter coefficients; The final concentration value of the target gas at time t-1.

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