Performance evaluation method of cooled infrared imaging system based on gas leakage

Abstract

The invention discloses a performance evaluation method for a refrigerated infrared imaging system based on gas leakage, relates to the technical field of refrigerated infrared imaging systems, and solves the technical problem that the applicability of the prior art in terms of leaked gas detection is limited. Specifically, the background black body temperature, gas temperature, ambient pressure, ambient temperature, test gas type, and test optical system parameters in the experiment are controlled to remain consistent; the distances L1, L2, L3, ..., L n At equal distances, the minimum detectable flow rate of the system is measured to be LR1, LR2, ...LR n ; According to LR i =αL i 2 +β basic form for LR1...LR n With L1...L n The relationship between is fitted to obtain the specific comparison parameter α and the correction term β; the detection capability of the refrigerated infrared imaging system for gas leakage is determined by α, and the smaller α is, the stronger the detection capability of the refrigerated infrared imaging system for gas leakage is.

Description

Technical Field

[0001] The invention relates to the technical field of refrigerated infrared imaging systems, in particular to a performance evaluation method for refrigerated infrared imaging systems based on gas leakage. Background Art

[0002] The cooled infrared imaging system is an advanced technical equipment that uses infrared detectors to perform thermal imaging of target objects. The cooled infrared imaging system is mainly composed of an optical system, an infrared detector, a refrigerator and a signal processing system. The optical system focuses the infrared radiation emitted by the target object onto the infrared detector, and the infrared detector converts the received infrared radiation into an electrical signal. After amplification, filtering, digitization and other processing by the signal processing system, an infrared image that can be displayed and analyzed is formed.

[0003] However, the existing evaluation methods for cooled infrared imaging systems are mainly based on indicators such as system NETD and MRTD. However, considering that the above indicators mainly focus on discussing the imaging resolution capability of cooled infrared imaging systems for specific image targets (such as four-bar targets, etc.), they fail to discuss their use in the actual scenario of gas leakage. Therefore, their applicability in leaking gas detection is limited.

[0004] In view of the above technical defects, a solution is now proposed. Summary of the invention

[0005] The purpose of the present invention is to solve the above-mentioned problems and to propose a performance evaluation method for a refrigerated infrared imaging system based on gas leakage.

[0006] The purpose of the present invention can be achieved by the following technical solution: a performance evaluation method of a refrigerated infrared imaging system based on gas leakage, and the specific performance evaluation method steps are as follows:

[0007] Step 1: Control the background black body temperature, gas temperature, ambient pressure, ambient temperature, test gas type, and test optical system parameters in the experiment to keep them consistent;

[0008] Step 2: Control the distance between L1, L2, L3...L n At equal distances, the minimum detectable flow rate of the system is measured to be LR1, LR2, ...LR n ;

[0009] Step 3: According to LR i =αL i 2 +β basic form for LR1...LR n With L1...L nThe relationship between is fitted to obtain the specific comparison parameter α and the correction term β; the detection capability of the refrigerated infrared imaging system for gas leakage is determined by α, and the smaller α is, the stronger the detection capability of the refrigerated infrared imaging system for gas leakage is.

[0010] As a preferred embodiment of the present invention, the specific process of step 1 is as follows:

[0011] Step S1: The experimental scene is set in an indoor environment, or in a scene without significant additional radiation sources in the surrounding area; when setting up the imaging system, ensure that the imaging system and the final imaging screen of the imaging system only contain leaked gas and black body background;

[0012] Step S2: Connect the flow controller to the gas cylinder to be tested, and release the gas to be tested through a hose; the hose aperture should be set to 1 / 4, and the nozzle should be vertically pointed to the zenith;

[0013] Step S3: Connect the imaging system to the display system; the display system should be able to correctly display 8-bit black and white video;

[0014] Step S4: The background blackbody temperature is controlled by the blackbody; the gas temperature is controlled by a water bath heating structure.

[0015] As a preferred embodiment of the present invention, for the convenience of calculation, the test gas should be selected with a purity of at least 90%, and a mixed gas should be selected in which the spectral absorption range of the impurity components is significantly different from the spectral response range of the current test gas and the imaging system; at the same time, the spectral response range of the imaging system does not include the spectral absorption range of the gas significantly present in the current test environment atmosphere; the background blackbody temperature should be set to the gas temperature + 5°C.

[0016] As a preferred embodiment of the present invention, the hose mouth should be at least 30 cm away from the background black body and should be just outside the imaging screen, wherein the distance is measured in the direction from the center of the outermost window of the imager optical system to the hose mouth.

[0017] As a preferred embodiment of the present invention, the experiment should be equipped with 4 observers, and the display system can output real-time imaging pictures to the computer.

[0018] As a preferred embodiment of the present invention, the ambient pressure and ambient temperature should ensure that the fluctuation during the experiment does not exceed 5% of the state at the beginning of the experiment.

[0019] As a preferred embodiment of the present invention, the specific process of step 2 is as follows:

[0020] Step SS1: In the experiment, L1...L n The distance is not recommended to exceed 30m

[0021] Step SS2: The system can detect the minimum flow rate by two methods: human visual inspection and computer judgment; specifically: human visual inspection and computer judgment;

[0022] Step SS3: The system should start testing from a larger flow rate. When the current flow rate is detectable, the gas leakage flow rate should be continuously reduced according to the minimum scale value of the flow controller. When a specific flow rate is reached, it is determined that no gas is visible on the screen. The previous gas flow rate is the minimum detectable flow rate at the current distance.

[0023] As a preferred embodiment of the present invention, the human eye visual observation specifically requires that at least two of the four on-site observers subjectively determine that the leaking gas can be observed in the picture and continuously observed for at least more than 5 seconds.

[0024] As a preferred embodiment of the present invention, the computer judgment is specifically as follows: all pixels of the picture are traversed, the grayscale value of each pixel value is read and the average grayscale of the picture is obtained; a person who observes the gas with human eyes draws the gas part in the real-time picture; the computer traverses each pixel of the gas part and calculates the average pixel value of the gas part; the average grayscale of the picture is compared with the average grayscale of the gas part, and if it exceeds a specific threshold, it is confirmed that the current gas is visible.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] Compared with the existing commonly used evaluation experimental system, the disclosed content of the present invention is simple and easy to operate, and the evaluation system can be expanded to monitor over long distances, rather than being limited to the laboratory. At the same time, based on the idea of ​​the present invention, it is theoretically possible to further deduce the theoretical minimum detectable leakage gas flow rate of the system under the conditions of any commonly used distance and any gas of the system, so as to ensure the accuracy of gas leakage detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0028] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0031] See also Figure 1 As shown, the performance evaluation method of the refrigerated infrared imaging system based on gas leakage, the specific performance evaluation method steps are as follows:

[0032] This method is mainly based on the minimum detectable leakage gas flow rate of the same gas at different observation distances under the condition that other conditions are fixed by the refrigerated infrared imaging system, and the flow data at the above different distances are fitted to obtain the specific comparison parameter α. The detection capability of the refrigerated infrared imaging system for gas leakage will be evaluated based on the parameter α.

[0033] Step 1: Control the background black body temperature, gas temperature, ambient pressure, ambient temperature, test gas type, and test optical system parameters in the experiment to keep them consistent;

[0034] Step 2: Control the distance between L1, L2, L3...L n At equal distances, the minimum detectable flow rate of the system is measured to be LR1, LR2, ...LR n ; L represents the set distance label;

[0035] Step 3: According to LR i =αL i 2 +β basic form for LR1...LR n With L1...L n The relationship between is fitted to obtain a specific comparison parameter α and a correction term β; the detection capability of the refrigerated infrared imaging system for gas leakage is determined by α, and the smaller α is, the stronger the detection capability of the refrigerated infrared imaging system for gas leakage is considered; wherein α and β in this technical solution are both empirical values ​​generated by personnel in this field in the actual experimental process;

[0036] The specific process of step one is as follows:

[0037] Step S1: The experimental scene is set in an indoor environment, or in a scene without significant additional radiation sources (including sunlight) in the surrounding area; when setting up the imaging system, it should be ensured that in the imaging system, the final imaging screen of the imaging system only contains leaked gas and black body (or equivalent black body, such as collimator, etc.) background; for the convenience of calculation, the test gas should be selected with a purity of at least 90%, and a mixed gas whose spectral absorption range of the impurity component is significantly different from the spectral response range of the current test gas and the imaging system should be selected as much as possible;

[0038] At the same time, the spectral response range of the imaging system should not include the spectral absorption range of gases that are significantly present in the current test environment atmosphere; the background blackbody temperature should be set to the gas temperature + 5°C;

[0039] Step S2: Connect the flow controller to the gas cylinder to be tested, and release the gas to be tested through a hose; the hose aperture should be set to 1 / 4 (DN8), and the hose mouth should be vertically pointed to the zenith; the hose mouth should be at least 30cm away from the background black body (measured from the direction from the center of the outermost window of the optical system of the imager to the hose mouth), and the hose mouth should be just outside the imaging screen;

[0040] Step S3: Connect the imaging system to the display system; the display system should be able to correctly display 8-bit black and white video; the experiment should be equipped with at least 4 observers, and the display system should be able to output real-time imaging images to the computer;

[0041] Step S4: The background blackbody temperature is controlled by the blackbody; the gas temperature is controlled by a water bath heating structure; the ambient pressure and ambient temperature should ensure that the fluctuation during the experiment does not exceed 5% of the state at the beginning of the experiment;

[0042] The specific process of step 2 is as follows:

[0043] Step SS1: In the experiment, L1...L n The distance is not recommended to exceed 30m

[0044] Step SS2: The system can detect the minimum flow rate by visual inspection and computer judgment, specifically:

[0045] Visual observation: At least two of the four on-site observers subjectively determined that the leaking gas could be observed on the screen and lasted for at least 5 seconds;

[0046] Computer judgment: traverse all pixels of the screen, read the gray value of each pixel value and calculate the average gray value of the screen; the person who observes the gas visually draws the gas part in the real-time screen. The computer traverses each pixel of the gas part and calculates the average value of the gas part pixels; compares the average gray value of the screen with the average gray value of the gas part. If it exceeds a specific threshold (temporarily set to 2.5 gray levels), it is confirmed that the current gas is visible.

[0047] Step SS3: The system should start the test from a larger flow rate. When the current flow rate is detectable, the gas leakage flow rate should be continuously reduced according to the minimum scale value of the flow controller until a certain flow rate is reached and the gas is judged to be invisible on the screen. The previous gas flow rate is the minimum detectable flow rate at the current distance.

[0048] When the present invention is used, the background black body temperature, gas temperature, ambient pressure, ambient temperature, test gas type, and test optical system parameters in the experiment are controlled to remain consistent; the distances L1, L2, L3, ... L n At equal distances, the minimum detectable flow rate of the system is measured to be LR1, LR2, ...LR n ; According to LR i =αL i 2 +β basic form for LR1...LR n With L1...L n The relationship between is fitted to obtain the specific comparison parameter α and the correction term β; the detection capability of the refrigerated infrared imaging system for gas leakage is determined by α, and the smaller α is, the stronger the detection capability of the refrigerated infrared imaging system for gas leakage is.

[0049] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for evaluating the performance of a refrigerated infrared imaging system based on gas leakage, characterized in that: The specific performance evaluation method steps are as follows: Step 1: Control the background black body temperature, gas temperature, ambient pressure, ambient temperature, test gas type, and test optical system parameters in the experiment to keep them consistent; Step 2: Control the distance between L1, L2, L3...L n At the distance, the minimum detectable flow rate of the system is measured to be LR1, LR2...LR n ; Step 3: According to LR i =αL i 2 +β basic form for LR1...LR n With L1...L n The relationship between is fitted to obtain the specific comparison parameter α and the correction term β; the detection capability of the refrigerated infrared imaging system for gas leakage is determined by α, and the smaller α is, the stronger the detection capability of the refrigerated infrared imaging system for gas leakage is.

2. The method for evaluating the performance of a refrigerated infrared imaging system based on gas leakage according to claim 1, characterized in that: The specific process of step one is as follows: Step S1: The experimental scene is set in an indoor environment and in a scene without significant additional radiation sources in the surrounding area; when setting up the imaging system, ensure that the imaging system and the final imaging screen of the imaging system only contain leaked gas and black body background; Step S2: Connect the flow controller to the gas cylinder to be tested, and release the gas to be tested through a hose; the hose aperture should be set to 1 / 4, and the nozzle should be vertically pointed to the zenith; Step S3: Connect the imaging system to the display system; the display system should be able to correctly display 8-bit black and white video; Step S4: The background blackbody temperature is controlled by the blackbody; the gas temperature is controlled by a water bath heating structure.

3. The performance evaluation method of a refrigerated infrared imaging system based on gas leakage according to claim 2 is characterized in that: For ease of calculation, the test gas should be a test gas with a purity of at least 90%, and a mixed gas should be selected in which the spectral absorption range of the impurity components is significantly different from the spectral response range of the current test gas and the imaging system; at the same time, the spectral response range of the imaging system does not include the spectral absorption range of the gas that is significantly present in the current test environment atmosphere; the background blackbody temperature should be set to the gas temperature + 5°C.

4. The performance evaluation method of a refrigerated infrared imaging system based on gas leakage according to claim 3 is characterized in that: The hose mouth should be at least 30cm away from the background black body, and the hose mouth should be just outside the imaging screen, where the distance is measured in the direction from the center of the outermost window of the imager's optical system to the hose mouth.

5. The method for evaluating the performance of a refrigerated infrared imaging system based on gas leakage according to claim 4, characterized in that: The experiment should be equipped with 4 observers, and the display system should be able to output real-time imaging images to a computer.

6. The method for evaluating the performance of a refrigerated infrared imaging system based on gas leakage according to claim 5, characterized in that: The ambient pressure and ambient temperature should ensure that the fluctuation during the experiment does not exceed 5% of the state at the beginning of the experiment.

7. The method for evaluating the performance of a refrigerated infrared imaging system based on gas leakage according to claim 1, characterized in that: The specific process of step 2 is as follows: Step SS1: In the experiment, L1...L n Distance no more than 30m Step SS2: The system can detect the minimum flow rate by two methods: human visual inspection and computer judgment; specifically: human visual inspection and computer judgment; Step SS3: The system should start testing from a flow rate. When the current flow rate is detectable, the gas leakage flow rate should be continuously reduced according to the minimum scale value of the flow controller. When a specific flow rate is reached, it is determined that no gas is visible on the screen. The previous gas flow rate is the minimum detectable flow rate at the current distance.

8. The method for evaluating the performance of a refrigerated infrared imaging system based on gas leakage according to claim 7, characterized in that: Specifically, human visual observation requires that at least two of the four on-site observers subjectively determine that the leaking gas can be observed on the screen and lasts for at least more than 5 seconds.

9. The method for evaluating the performance of a refrigerated infrared imaging system based on gas leakage according to claim 8, characterized in that: The computer judgment is as follows: all pixels of the screen are traversed, the gray value of each pixel is read and the average gray value of the screen is obtained; the person who observes the gas with human eyes draws the gas part in the real-time screen; The computer traverses each pixel of the gas part and calculates the average pixel value of the gas part; compares the average grayscale of the image with the average grayscale of the gas part. If it exceeds a specific threshold, it confirms that the current gas is visible.

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