Gas temperature measuring device and method

Abstract

The present invention provides a gas temperature measurement device and method, comprising: an X-ray source capable of emitting high-energy X-rays; an X-ray detector capable of capturing X-ray information that penetrates a subject, converting it into digital signals and transmitting it to a data processing unit; a test section located between the X-ray source and the X-ray detector, containing the gas to be measured; and a data processing unit that performs image processing on the digital signals obtained by the X-ray detector and reconstructs the three-dimensional temperature field of the gas inside the object using three-dimensional reconstruction methods, optical theory, and computer image processing technology. The X-ray imaging device for measuring gas temperature and the temperature measurement method thereof of the present invention can overcome the difficulty in measuring the temperature of gas inside an object in the prior art, and can accurately and reliably reconstruct the three-dimensional temperature field of the gas region using a non-invasive measurement method, while also monitoring the density distribution and flow state of the gas.

Description

Technical Field

[0001] The invention relates to a gas temperature measuring device and method, belonging to the technical field of detection and calibration. Background Art

[0002] Modern temperature measurement methods mainly include infrared temperature measurement technology, thermocouples, thermistor temperature measurement technology, and laser temperature measurement technology. Thermocouple temperature measurement, as the most common temperature measurement method, usually uses various types of thermocouples to directly penetrate into the interior of the object to measure the temperature. It has a simple structure, fast temperature measurement response, high accuracy, and a wide temperature measurement range. However, with the insertion of the thermocouple, the heat transfer performance of the local location inside the object changes, resulting in a deviation between the measured temperature and the actual temperature. Other methods such as infrared temperature measurement and laser temperature measurement can only directly measure the temperature of the surface of the object or structure, which cannot meet the requirements of measuring the internal temperature of the object or monitoring the internal temperature in many occasions, such as measuring the temperature of the gas inside porous media, heat exchangers, and complex pipelines. In recent years, non-invasive measurement methods have been widely used to construct the three-dimensional temperature field of the gas inside the object, such as X-ray fluorescence, X-ray computed tomography, planar laser induced fluorescence, and electrical capacitance tomography. X-ray computed tomography (XCT) captures an instantaneous image of the gas density within an object at a specific moment and, using optical theory and computer image processing techniques, reconstructs the temperature field of the gas within the object. Due to its advantages—non-destructive, high-precision, ability to visualize the three-dimensional microstructure of the object being measured, and the lack of an optical channel—XCT is able to perform internal tomographic scans and reconstruct the three-dimensional physical field without destroying the object's structure. It has been widely used in fields such as biomedicine and materials science.

[0003] Chinese invention patent CN 102706474 A discloses an X-ray imaging device and method for measuring the internal temperature of an object. These devices can calculate the temperature of a heated material based on the grayscale values of its X-ray transmission images before and after heating, given the material's mass absorption coefficient, linear expansion coefficient, density, diameter, and initial temperature. However, this method measures only in one projection direction and cannot obtain three-dimensional temperature field information within the object. Chinese invention patent CN 101216409 A relates to a method and apparatus for measuring flue gas concentration, temperature, and particulate matter concentration distribution, aiming to provide a method and apparatus for simultaneously reconstructing flue gas concentration, particle concentration, and temperature distribution using multi-source tomography technology. However, this method, based on the proportional relationship between laser intensity attenuation and the measured flue gas and particle content, is only applicable to temperature and concentration measurements of particulate-containing flue gas and cannot perform scanning measurements of gases without particulate matter. Furthermore, the laser has a long wavelength and weak penetrating power, making it incapable of performing scanning measurements of gases within an object. Patent JP2009014359A discloses a thermometer capable of performing non-contact, accurate, and easy three-dimensional measurement of gas temperature. The method measures the three-dimensional temperature distribution of a gas by applying the relationship between refractive index and temperature. However, the method only scans and measures the target field from a limited number of directions, is unable to perform rotational scanning, and is unable to scan and measure the gas temperature field inside an object. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the difficulty in measuring the gas temperature inside an object in the prior art, provide an X-ray device for measuring gas temperature and a method for measuring gas temperature, and realize accurate, simple and reliable non-contact measurement of the three-dimensional temperature field of the gas inside the object.

[0005] The technical solutions of the present invention are as follows:

[0006] The present invention provides a gas temperature measuring device, comprising an X-ray source capable of emitting high-energy X-rays; an X-ray detector capable of capturing X-ray information penetrating an object from different irradiation directions, converting the information into digital signals, and transmitting the signals to a data processing unit; a test section located between the X-ray source and the X-ray detector, containing a gas to be measured; and a data processing unit for performing image processing on the digital signals obtained by the X-ray detector, calculating a three-dimensional X-ray image of the gas to be measured by a three-dimensional reconstruction method, and reconstructing the three-dimensional temperature field of the gas inside the object by means of optical theory and computer image processing technology.

[0007] The preferred solution further includes any of the following technical features:

[0008] Also included is a rotating stage for carrying the test section.

[0009] The gas to be measured is in a closed static state or a stable flow state.

[0010] Specific occasions corresponding to the closed static state include but are not limited to the measurement of gas temperature in a gas storage tank or pressure vessel; specific occasions corresponding to the stable flow state include but are not limited to the measurement of gas temperature in a porous medium burner or a heat exchanger pipe.

[0011] Depending on the gas flow state, different gas containers and insulation or heating equipment are used; for gases in a closed static state, the gas to be tested needs to be filled into a gas tank, and insulation or heating equipment is installed on the gas tank to obtain a steady-state temperature field; for gases in a stable flow state, the gas to be tested needs to be passed into the test section and the gas flow rate needs to be controlled to be constant or the gas combustion needs to be stable, and insulation, heating or ignition equipment is installed on the test section.

[0012] It also includes a power drive device, which has two drive modes. In the first drive mode, the test section and the rotating stage are connected and rotate together under the drive of the power device, and the X-ray source and the X-ray detector are fixed; in the second drive mode, the power device drives the X-ray source and the X-ray detector to rotate around the test section, and the test section is fixed.

[0013] The X-ray detector can convert the attenuated X-rays after passing through the gas to be measured into visible light, convert it into an electrical signal, and then convert the electrical signal into a digital signal and transmit it to a data processing unit.

[0014] A lead plate with a through hole is provided between the X-ray source and the test section, and the X-rays pass through the through hole to cover the entire test section.

[0015] The present invention also provides a method for measuring gas temperature. The method captures X-rays that have penetrated the gas being measured, measures the average linear attenuation coefficient of the gas being measured, and mixes a contrast agent gas into the gas being measured to enhance the attenuation effect. Based on the measured data and in combination with the gas state equation, optical theory and computer image processing technology are used to reconstruct the three-dimensional temperature field of the gas inside the object. The method specifically includes the following steps:

[0016] S1: Adjust the positions of the X-ray source, lead plate, test section and X-ray detector so that the projection of the part of the gas to be measured falls entirely within the display range of the X-ray detector, and the lead plate shields excess X-rays.

[0017] S2: Mix the contrast agent gas and the gas to be tested and introduce them into the test section, select the driving mode, and start the power drive device;

[0018] S3: The X-ray source emits X-rays that are projected onto the test section. After being attenuated by the gas being tested, the X-rays fall onto the X-ray detector panel. The X-ray detector converts the optical signal into an electrical signal, and then into a digital signal, which is sent to the data processing unit for image processing and the first scan data is recorded.

[0019] S4: Replace the contrast agent gas with air, mix it with the gas to be tested and introduce it into the test section, scan again and record the second scan data;

[0020] S5: The data processing unit processes the two measurement data, combines the gas state equation, and uses optical theory and computer image processing technology to reconstruct the three-dimensional temperature field of the gas inside the object.

[0021] The scanning time and number of samples for the two tests are the same. The test section is scanned multiple times each time, and the average value of the large amount of X-ray projection image information obtained is taken. When replacing the gas, the gas flow state and thermal insulation and heating state before and after the replacement must be kept the same.

[0022] Obtain the linear attenuation coefficient of the mixed gas by scanning Then the density field of the mixed gas can be obtained;

[0023] Linear attenuation coefficient is the mass attenuation coefficient and density The product of:

[0024]

[0025] Among them, the mass attenuation coefficient It has nothing to do with the density and physical state of the medium, but only with the type of substance and the energy of photon radiation. The density of the mixed gas Able to use known quantities and measurement Express:

[0026]

[0027] The data processing in step S5 is to obtain the gas temperature field information by subtracting the linear attenuation coefficients obtained from the two measurements before and after according to the gas state equation. It can be expressed as:

[0028]

[0029] in, is the attenuation coefficient obtained from the first scan, where the measured gas is mixed with contrast medium gas; is the attenuation coefficient obtained from the second scan. The gas being measured does not contain contrast agent gas. minus To eliminate the influence of X-ray attenuation caused by mixed contrast agent gas during the first scan; for mixed gas, It can be expressed as an expression for density and mass attenuation coefficient:

[0030]

[0031] Among them, N s is the number of gas mixture components, is the average mass attenuation coefficient of X-rays of a gas component j, Y j is the mass fraction of a component j, ρ j is the density of a component j. According to the gas state equation, the measured gas temperature T can be calculated by the difference in attenuation coefficients obtained from the two measurements. The ideal gas state equation is used as an example to express the known physical properties of the contrast agent gas (subscript K). The measured gas temperature T is expressed as:

[0032]

[0033] Where P is the gas pressure, R u is the universal gas constant, W is the molar mass, and X is the mole fraction

[0034] For non-ideal gases, the relationship between gas temperature and density can be obtained by using the actual gas state equation, so the gas temperature can be used as the measured parameter. and other known physical parameters.

[0035] The mole fraction of a component in a binary gas mixture can be obtained by scanning, and the formula (4) can be transformed using Y j =ρ j / ρ, in the case of ideal gas, the mole fraction X1 of a component in a binary gas mixture can be expressed as:

[0036]

[0037] in, and is the linear attenuation coefficient of component 1 and component 2 measured at pressure P and temperature T.

[0038] The gas flow morphology and flow state can be monitored through the density field, temperature field and mole fraction distribution.

[0039] Contrast agent gases include but are not limited to krypton and xenon. By adding contrast agent gases, the density and mass attenuation coefficient of the mixed gas are increased, and the attenuation degree of X-rays after passing through the mixed gas is increased to obtain effective data, improve the signal-to-noise ratio, and thus improve the quality of three-dimensional X-ray images.

[0040] The present invention has the following advantages and technical effects:

[0041] The X-ray imaging device for measuring gas temperature and the temperature measurement method thereof of the present invention can accurately and reliably measure the gas temperature inside an object in a non-invasive measurement method, reconstruct the three-dimensional temperature field of the gas region, and monitor the density distribution and flow state of the gas while measuring the temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 3 is a schematic structural diagram of the first driving mode of the gas temperature measuring device of the present invention.

[0043] Figure 2 3 is a schematic structural diagram of the second driving mode of the gas temperature measuring device of the present invention.

[0044] Figure 3 It is a structural schematic diagram of a first driving mode of a porous medium burner internal gas temperature measuring device provided by the present invention.

[0045] Figure 4 It is a structural schematic diagram of the second driving mode of a porous medium burner internal gas temperature measuring device provided by the present invention.

[0046] Description of reference numerals:

[0047] 1-X-ray source; 2-lead plate; 3-test section; 4-X-ray detector; 5-data processing unit; 6-rotating stage; 7-connecting device; 8-X-ray source; 9-lead plate; 10-combustion section; 11-holding tube; 12-igniter; 13-X-ray detector; 14-data processing unit; 15-rotating stage; 16-T-connector; 17-rotor flowmeter; 18-voltage regulator; 19-valve; 20-gas cylinder; 21-connecting device. DETAILED DESCRIPTION

[0048] Figure 1-2 It is a structural schematic diagram of the gas temperature measuring device of the present invention.

[0049] The X-ray source 1 is capable of emitting high-energy X-rays. The X-ray detector 4 is capable of capturing X-ray information after penetrating the test section 3 from different irradiation directions, converting it into digital signals and transmitting it to the data processing unit 5. The test section 3 is located between the X-ray source 1 and the X-ray detector 4, and contains the gas to be tested. The data processing unit 5 performs image processing on the digital signal obtained by the X-ray detector 4, calculates the three-dimensional X-ray image of the gas to be tested in the test section 3 through a three-dimensional reconstruction method, and reconstructs the three-dimensional temperature field of the internal gas with the help of optical theory and computer image processing technology. The rotating stage 6 is used to carry the test section. The X-ray source 1 and the X-ray detector 4 rotate around the test section 3 through the connecting device 7.

[0050] The X-ray imaging device for measuring gas temperature and the temperature measurement method thereof of the present invention can accurately and reliably measure the gas temperature inside an object in a non-invasive measurement method, reconstruct the three-dimensional temperature field of the gas region, and monitor the density distribution and flow state of the gas while measuring the temperature.

[0051] The specific embodiments of the present invention are described below with reference to examples.

[0052] Figure 3-4 An example of a porous media burner is provided. In recent years, great progress has been made in the study of the combustion mechanism of gases inside porous media, but there is still a lack of a full understanding of the physical process of gas combustion and the internal flame structure inside porous media. Heat transfer inside a porous media burner involves the coupling of heat conduction, convection and radiation between solid skeletons, between airflows, and between gas and solid, and the influencing mechanism is very complex. Therefore, measuring the gas temperature inside a porous media burner is very important for understanding the heat transfer and combustion characteristics (thermal efficiency, pollutant emissions and flame stability, etc.) of the porous media burner. Currently, common methods for obtaining gas temperature data inside a porous media burner include thermocouple temperature measurement, infrared temperature measurement, laser temperature measurement, etc., none of which can generate three-dimensional temperature field data, and all require the combustion system itself to be designed and modified. A device and method for measuring the gas temperature inside a porous media burner provided by the present invention can accurately, reliably and non-destructively measure the gas temperature inside a porous media burner using a non-invasive measurement method, reconstruct the three-dimensional temperature field of the gas region, and monitor the density distribution and flow state of the gas while measuring the gas temperature.

[0053] After being emitted by X-ray source 8, X-rays pass through the gas under test in combustion section 10, attenuate, and fall onto X-ray detector 13. Lead plate 9 with through holes partially shields the X-rays, ensuring that the projection of the portion of the gas under test in combustion section 10 that requires temperature measurement falls entirely within the display range of X-ray detector 13.

[0054] The combustion section 10 is a porous medium burner, and silicon carbide is selected as the porous medium material because of its good thermal shock resistance and high conductivity.

[0055] The combustion section 10 is enclosed within a transparent containment tube 11, preventing contamination from surrounding gases, impurities, and dust, which could affect test results. Quartz, with its low thermal expansion coefficient, high heat resistance, and transparency, allows for direct observation of the flame position and flow within the porous medium burner, as well as assessment of flame stability.

[0056] The X-ray source 8, the combustion section 10 and the X-ray detector 13 are not limited to being arranged in the horizontal direction, but can also be arranged linearly in the vertical direction, or can be arranged linearly in an oblique direction, as long as the X-ray source 8, the combustion section 10 and the X-ray detector 13 can be arranged linearly and the rays passing through the combustion section 10 can be received by the X-ray detector 13.

[0057] The working process of the device is divided into a first scanning stage and a second scanning stage.

[0058] Before the first scan phase, the component gases are supplied from compressed gas cylinders 20 equipped with valves 19 and pressure regulators 18 to ensure a constant pressure supply of each component gas. A set of T-joints 16 ensures thorough mixing of the component gases. A set of rotameters 17 controls and measures the flow rates of the component gases.

[0059] The mixed gas includes fuel gas CH4, air and contrast agent gas Kr. Kr 0.375, and The flow rate was controlled at 4.0 cm / s.

[0060] When the flow rate of the mixed gas reaches a stable state, the igniter 12 at the combustion section outlet ignites the mixed gas, and the flame moves upstream and eventually stabilizes inside the porous medium burner. The combustion products are directly discharged into the atmosphere through the upper opening of the combustion section.

[0061] After achieving stable combustion, a drive mode is selected and scanning begins. In the first drive mode, the X-ray source 8 and X-ray detector 13 remain stationary, the combustion section 10 and the holding tube 11 fit tightly together, the bottom of the holding tube 11 is connected to the rotating stage 15, and the center of the burner coincides with the rotation axis. Driven by a power device, the rotating stage 15 rotates the holding tube 11 and the combustion section 10, thereby capturing images of a complete rotation of the combustion section 10. In the second drive mode, the X-ray source 8 and X-ray detector 13 rotate around the combustion section 10 at a constant angular velocity via the connecting device 21. During rotation, the X-ray detector 13 converts attenuated X-rays that pass through the gas being measured into visible light, then converts the visible light into electrical signals and outputs them as digital signals, which are transmitted to the data processing unit 14. A large number of X-ray projection images are recorded and stored from different irradiation directions, and recording ceases after scanning the combustion section 10 several times.

[0062] Before the second scanning phase, the valve of the contrast agent gas Kr cylinder is closed to stop the supply of contrast agent gas, and the contrast agent gas is replaced with an equal flow of air. When the flow of the mixed gas reaches stability, the igniter 12 at the outlet of the combustion section ignites the mixed gas, and the flame will move upstream and eventually stabilize inside the porous medium burner, and the second scan begins under the condition of no contrast agent gas.

[0063] In the second scanning stage, the operation steps, scanning time, and sampling quantity are consistent with those in the first scanning stage, and the recording is stopped after the combustion section 10 is scanned the same number of times.

[0064] The data processing unit 14 performs image processing on the digital signal obtained by the X-ray detector 13, calculates the three-dimensional X-ray projection image of the gas under inspection in the combustion section 10, averages a large amount of X-ray projection image information obtained in the first scanning stage, and records the average attenuation coefficient as The average value of a large amount of X-ray projection image information obtained in the second scanning stage is taken and the average attenuation coefficient is recorded as

[0065] By subtracting the linear attenuation coefficients obtained from the two measurements, the gas temperature field information is obtained according to the gas state equation. The difference in attenuation coefficients obtained from the two measurements is It can be expressed as:

[0066]

[0067] in, is the attenuation coefficient obtained from the first scan, where the measured gas is mixed with contrast medium gas; is the attenuation coefficient obtained from the second scan, and the measured gas does not contain contrast agent gas. minus To eliminate the influence of X-ray attenuation caused by mixed contrast agent gas during the first scan. It can be expressed as an expression for density and mass attenuation coefficient:

[0068]

[0069] Among them, N s is the number of gas mixture components, is the average mass attenuation coefficient of X-rays of a gas component j, Y j is the mass fraction of a component j, ρ j is the density of a component j. According to the gas state equation, the measured gas temperature T can be calculated by the difference in attenuation coefficients obtained from the two measurements. The measured gas temperature T is expressed as follows:

[0070]

[0071] Where P is the gas pressure, which can be measured by a manometer; R u is the universal gas constant, 8.314 J / (mol·K); W K is the molar mass of Kr, 83.8 g / mol; X K is the mole fraction, which is 0.375; the mass attenuation coefficient It is a known quantity that has nothing to do with the density and physical state of the medium, but only with the type of matter and the energy of photon radiation.

[0072] For non-ideal gases, the relationship between gas temperature and density can be obtained by using the actual gas state equation, so the gas temperature can be used as the measured parameter. and other known physical parameters.

[0073] Finally, with the help of optical theory and computer image processing technology, the three-dimensional temperature field of the gas inside the object was reconstructed using CTSIM software according to the three-dimensional cone-beam Feldkamp-Davis-Kress (FDK) equidistant projection method.

[0074] In addition, the mixed gas is regarded as a binary component, the fuel gas CH4 and air are regarded as component 1, and the contrast agent gas Kr is regarded as component 2. The mole fraction of a component in the binary mixed gas can be obtained by scanning. j =ρ j / ρ, in the case of ideal gas, the mole fraction X1 of component 1 in the binary gas mixture can be expressed as:

[0075]

[0076] in, is the attenuation coefficient obtained by scanning the mixed gas, and is the linear attenuation coefficient obtained by scanning component 1 and component 2 separately under pressure P and temperature T.

[0077] The embodiments of the present invention are merely illustrative of this patent and do not limit its scope of protection. Those skilled in the art may also make partial changes thereto, which are within the scope of protection of this patent as long as they do not exceed the spirit of this patent.

Claims

1. A method for measuring gas temperature, using a gas temperature measuring device for measurement, the gas temperature measuring device comprising: An X-ray source capable of emitting high-energy X-rays; X-ray detector, which can capture X-ray information penetrating the object from different irradiation directions, convert it into digital signals and transmit them to the data processing unit; The test section is located between the X-ray source and the X-ray detector and contains the gas to be tested; A data processing unit performs image processing on the digital signal obtained by the X-ray detector; Characterized in that the method comprises: By capturing X-rays that have penetrated the gas being measured, measuring the average linear attenuation coefficient of the gas being measured, and mixing contrast agent gas into the gas being measured to enhance the attenuation effect, the three-dimensional temperature field of the gas inside the object is reconstructed based on the measured data and the gas state equation, with the help of optical theory and computer image processing technology. The specific steps include: S1: Adjust the positions of the X-ray source, lead plate, test section and X-ray detector so that the projection of the part of the gas to be measured falls entirely within the display range of the X-ray detector, and the lead plate shields excess X-rays. S2: Mix the contrast agent gas and the gas to be tested and introduce them into the test section, select the driving mode, and start the power drive device; S3: The X-ray source emits X-rays that are projected onto the test section. After being attenuated by the gas being tested, the X-rays fall onto the X-ray detector panel. The X-ray detector converts the optical signal into an electrical signal, and then into a digital signal, which is sent to the data processing unit for image processing and the first scan data is recorded. S4: Replace the contrast agent gas with air, mix it with the gas to be tested and introduce it into the test section, scan again and record the second scan data; S5: The data processing unit processes the two measurement data, combines the gas state equation, and uses optical theory and computer image processing technology to reconstruct the three-dimensional temperature field of the gas inside the object.

2. A gas temperature measurement method according to claim 1, characterized in that: Also included is a rotating stage for carrying the test section.

3. The gas temperature measurement method according to claim 1, characterized in that: The gas to be measured is in a closed static state or a stable flow state.

4. A gas temperature measurement method according to claim 3, characterized in that: Specific occasions corresponding to the closed static state include but are not limited to the measurement of gas temperature in a gas storage tank or pressure vessel; specific occasions corresponding to the stable flow state include but are not limited to the measurement of gas temperature in a porous medium burner or a heat exchanger pipe.

5. A gas temperature measurement method according to claim 3, characterized in that: Depending on the gas flow state, different gas containers and insulation or heating equipment are used; for gases in a closed static state, the gas to be tested needs to be filled into a gas tank, and insulation or heating equipment is installed on the gas tank to obtain a steady-state temperature field; for gases in a stable flow state, the gas to be tested needs to be passed into the test section and the gas flow rate needs to be controlled to be constant or the gas combustion needs to be stable, and insulation, heating or ignition equipment is installed on the test section.

6. A gas temperature measurement method according to claim 1, characterized in that: It also includes a power drive device, which has two drive modes. In the first drive mode, the test section and the rotating stage are connected and rotate together under the drive of the power device, and the X-ray source and the X-ray detector are fixed; in the second drive mode, the power device drives the X-ray source and the X-ray detector to rotate around the test section, and the test section is fixed.

7. A gas temperature measurement method according to claim 1, characterized in that: The X-ray detector can convert the attenuated X-rays after passing through the gas to be measured into visible light, convert it into an electrical signal, and then convert the electrical signal into a digital signal and transmit it to a data processing unit.

8. A gas temperature measurement method according to claim 1, characterized in that: A lead plate with a through hole is provided between the X-ray source and the test section, and the X-rays pass through the through hole to cover the entire test section.

9. A gas temperature measurement method according to claim 1, characterized in that: The scanning time and number of samples for the two tests are the same. The test section is scanned multiple times each time, and the average value of the large amount of X-ray projection image information obtained is taken. When replacing the gas, the gas flow state and thermal insulation and heating state before and after the replacement must be kept the same.

10. A gas temperature measurement method according to claim 1, characterized in that: Obtain the linear attenuation coefficient of the mixed gas by scanning Then the density field of the mixed gas can be obtained; Linear attenuation coefficient is the mass attenuation coefficient and density The product of: Among them, the mass attenuation coefficient It has nothing to do with the density and physical state of the medium, but only with the type of substance and the energy of photon radiation. The density of the mixed gas Able to use known quantities and measurement Express:

11. A gas temperature measurement method according to claim 1, characterized in that: The data processing in step S5 is to obtain the gas temperature field information by subtracting the linear attenuation coefficients obtained from the two measurements before and after according to the gas state equation. It can be expressed as: in, is the attenuation coefficient obtained from the first scan, where the measured gas is mixed with contrast medium gas; is the attenuation coefficient obtained from the second scan. The gas being measured does not contain contrast agent gas. minus To eliminate the influence of X-ray attenuation caused by mixed contrast agent gas during the first scan; for mixed gas, It can be expressed as an expression for density and mass attenuation coefficient: Among them, N s is the number of gas mixture components, is the average mass attenuation coefficient of X-rays of a gas component j, Y j is the mass fraction of a component j, ρ j is the density of a component j. According to the gas state equation, the measured gas temperature T can be calculated by the difference in attenuation coefficients obtained from the two measurements. And the physical parameters of the known contrast agent gas (subscript K) are expressed. Taking the ideal gas state equation as an example, the measured gas temperature T is expressed as: Where P is the gas pressure, R u is the universal gas constant, W is the molar mass, X is the mole fraction, For non-ideal gases, the relationship between gas temperature and density can be obtained by using the actual gas state equation, so the gas temperature can be used as the measured parameter. and other known physical parameters.

12. A gas temperature measurement method according to claim 11, characterized in that: The mole fraction of a component in a binary gas mixture can be obtained by scanning, and the formula (4) can be transformed using Y j =ρ j / ρ, in the case of ideal gas, the mole fraction X1 of a component in a binary gas mixture can be expressed as: in, and is the linear attenuation coefficient of component 1 and component 2 measured at pressure P and temperature T.

13. A gas temperature measurement method according to claim 1, characterized in that: The gas flow morphology and flow state can be monitored through the density field, temperature field and mole fraction distribution.

14. A gas temperature measurement method according to claim 1, characterized in that: Contrast agent gases include but are not limited to krypton and xenon. By adding contrast agent gases, the density and mass attenuation coefficient of the mixed gas are increased, and the attenuation degree of X-rays after passing through the mixed gas is increased to obtain effective data, improve the signal-to-noise ratio, and thus improve the quality of three-dimensional X-ray images.

Images