CN109975233B - A non-condensable gas layer measurement device and method based on laser attenuation - Google Patents

Abstract

The invention discloses a device and a method for measuring a non-condensable gas layer based on laser attenuation, and belongs to the field of measurement of condensation experiments. The system comprises an optical measurement system consisting of a laser, a beam splitter, a reflector, a guide rail and the like, a visual condensation experimental body consisting of a condensation cavity, a semiconductor cold stage, an intracavity reflector, an optical window and the like, and a data acquisition and processing system consisting of a laser beam detector, a data acquisition instrument and a computer. The visual condensation experimental body is used for condensation experiments, and the distribution characteristics of the non-condensation layer are obtained by comparing signals of the measurement laser and the reference laser. The invention realizes the in-situ measurement of the noncondensable gas layer near the condensing surface in the condensing experiment process of the noncondensable gas-containing steam with different structural surfaces and different experiment parameters through the optical measurement system.

Description

A non-condensable gas layer measurement device and method based on laser attenuation

technical field

The invention relates to a non-condensable gas layer measurement device and method based on laser attenuation, and belongs to the field of condensation experiment measurement.

Background technique

The condensation process of water vapor is often seen in industrial production. The condensation of water vapor in most industrial equipment is often accompanied by the presence of a small amount of non-condensable gas. For example, in the process of condensing spent steam in the condenser of a power plant, due to the existence of a certain degree of vacuum in the condenser, long-term operation will Some air enters; when the central air conditioner cools in summer, the water vapor in the air may condense on the surface of the evaporator coil; the condensation of the flash steam in the multi-stage flash seawater desalination system is often accompanied by a certain amount of non-condensability. Gas is present. According to research, even the presence of very low content of non-condensable gas will have a great impact on the condensation process of steam. When the steam condenses on the cold surface, the steam forms condensate and adheres to the surface, and the non-condensable gas contained in the airflow accumulates near the surface due to diffusion to form a gas layer. This layer of non-condensable gas layer will cause the partial pressure of vapor near the surface to decrease, the saturation temperature will decrease, which will reduce the heat transfer temperature difference and reduce the heat transfer driving force of the condensation process; at the same time, due to the formation of a high-concentration non-condensable gas layer near the surface. , its concentration gradient is opposite to that of steam, which increases the diffusion resistance of steam to the surface, weakens the mass transfer process of steam condensation, and further inhibits the condensation process. It can be seen that the formation of the non-condensable gas layer is the key link restricting the strengthening of the condensation process. Therefore, it is of great significance to study the characteristics of the non-condensable gas layer during the condensation process of water vapor containing non-condensable gas.

In the experimental research on the condensation of steam containing non-condensable gas, most of them only study the influence of non-condensable gas content and composition on the condensation heat transfer coefficient, and there is no work related to the measurement of non-condensable gas layer. Fourier Transform Infrared Spectroscopy (FTIR) can realize online measurement of water vapor concentration in mixed gas, but the gas to be measured needs to be passed into the FTIR analyzer during measurement, which is not suitable for non-condensable gas layer during condensation experiments. In situ measurement. In order to establish a theoretical model suitable for various new types of micro-nanostructure reinforced surfaces based on the classical condensation model, and to verify the reliability of the numerical simulation of the condensation process, it is essential to use accurate experimental methods to verify the results.

SUMMARY OF THE INVENTION

Aiming at the current technical problems, the present invention proposes a non-condensable gas layer measurement device and method based on laser attenuation. The invention realizes the laser attenuation measurement of the non-condensable gas vapor in the condensation cavity through the optical measurement system, and uses the data acquisition and processing system to analyze the difference between the light intensity of the measurement laser and the reference laser to obtain the non-condensable gas on the measurement path. The concentration gradient and the thickness of the non-condensable gas layer provide an effective means for further research on the condensation phenomenon of steam containing non-condensable gas.

The object of the present invention is achieved in this way:

A non-condensable gas layer measurement device based on laser attenuation includes an optical measurement system, a visualized condensation experiment body, and a data acquisition and processing system;

The visualized condensation experiment body includes an intra-cavity reflector and an optical window; one side of the visualized condensation experiment body is provided with an optical window, and the inner wall surface of the other side opposite to the one side is provided with an intra-cavity reflector;

The data acquisition and processing system includes a first beam detector, a second beam detector, a data acquisition instrument and a computer;

The optical measurement system is composed of a laser, a first beam splitter, a first reflector, a second reflector, a third reflector, a second beam splitter, a third beam splitter, and a guide rail;

The first beam splitter is located on the laser light path emitted by the laser, and there is an included angle between the normal direction of the first beam splitter and the laser light path; the first beam splitter reflects and transmits the laser light, and the first reflector is arranged on the On the transmitted light path of the first beam splitter, and its normal direction has an included angle with the transmitted light path; the second reflector is arranged on the reflected light path of the first beam splitter, and its normal direction has an included angle with the reflected light path; The third reflector is arranged on the reflected light path of the second reflector, and its normal direction has an included angle with the reflected light path; the second beam splitter and the third beam splitter are respectively arranged on the first reflector and the third reflector The reflected light path of , and its normal direction has an included angle with the reflected light path;

The transmitted beam of the first beam splitter enters the second beam splitter after passing through the first reflector, the reflected beam of the second beam splitter enters the condensation cavity through the optical window, and is reflected by the intra-cavity reflector and enters the second beam detector; The reflected laser light of the first beam splitter enters the third beam splitter after passing through the second mirror and the third mirror, and the transmitted beam of the third beam splitter is reflected by the second beam splitter and then enters the second beam detector as reference beam;

The reflected beam of the first beam splitter enters the third beam splitter after passing through the second mirror and the third mirror, the reflected beam of the third beam splitter enters the condensation cavity through the optical window, and is reflected by the intra-cavity mirror and enters the third beam splitter. a beam detector; the transmitted beam of the first beam splitter enters the second beam splitter after passing through the first reflecting mirror, and the transmitted beam of the second beam splitter is reflected by the third beam splitter and then enters the first beam detector, as measuring beam;

The first beam detector and the second beam splitter are mounted on the same sliding platform, the second beam detector and the third beam splitter are mounted on another sliding platform, and the two sliding platforms are mounted on the guide rails; The displacement of each sliding platform is realized by the computer-controlled guide rail; the computer is connected with the first beam detector and the second beam detector respectively through the data acquisition instrument.

Preferably, the first beam splitter divides the laser into two beams of equal light intensity, and finally enters the beam detector respectively, so as to maintain the environmental attenuation of the reference beam and the measurement beam when the sliding platform moves, and the two beams The light intensity difference received by the detector is formed by the difference of the non-condensable gas concentration on the two paths, and the non-condensable gas concentration at the measurement beam can be obtained after data processing.

Preferably, the visualized condensation experiment body is a measurement body and further includes a condensation cavity, a semiconductor cold stage, a thermal insulation material, a test surface, an air distribution plate and a temperature sensor; the air distribution plate and the temperature sensor are located in the condensation cavity. one wall surface; the semiconductor cooling stage is located on the other wall surface opposite to the one wall surface, and the air distribution plate is arranged at the steam inlet to reduce the steam flow rate, ensure the uniformity of the steam in the cavity, and reduce the influence of the gas flow on the condensation; the cavity The normal direction of the internal mirror is parallel to the reference beam; the temperature sensor is inserted into the condensation cavity to monitor the temperature of the mixed steam in the cavity. The test surface is pasted on the cooling surface of the semiconductor cold table, and the rest of the cooling surface is covered with thermal insulation material.

Preferably, each wall surface of the condensation cavity is provided with an electric heating device to prevent steam from condensing on the wall surface.

Preferably, the wall of the condensation chamber is further provided with several flange interfaces for connecting external pipelines, equipment or for installing sensors.

Preferably, the first beam detector and the second beam detector can detect the light intensity of the incident beam and input it into the computer for viewing and storage by the data acquisition instrument.

The reflected beam of the second beam splitter and the transmitted beam of the third beam splitter enter the second beam detector together to form a reference beam to measure the non-condensable part; the transmitted beam of the second beam splitter and the third beam splitter The reflected beams enter the third beam detector together to form a measurement beam and measure the gas mixture; the light intensity difference received by the two beam detectors is formed by the difference in water vapor concentration on the two paths;

The first beam splitter divides the laser into two beams of equal intensity, and finally enters the beam detector respectively, so as to maintain the environmental attenuation of the reference beam and the measurement beam when the sliding platform moves, and ensure the measurement accuracy;

The condensation chamber can provide a vacuum environment for the condensation of non-condensable steam to control the composition of non-condensable gas. The condensation chamber is provided with a plurality of flange interfaces for the connection between the instrument and the pipeline. Electric heating device and thermal insulation cotton are installed; the semiconductor cold state is inserted into the condensation cavity through a square flange, the cold end is used in the cavity to control the temperature of the test surface, and the cooling table is surrounded by thermal insulation materials;

The test surface is connected with the semiconductor cold stage through thermal conductive glue to reduce contact thermal resistance and achieve uniform surface temperature;

The data acquisition instrument calculates the non-condensable gas concentration at the path where the measurement beam passes by analyzing the light intensity difference collected by the beam detector, according to the relationship between the beam intensity attenuation and the non-condensable gas concentration; When the surface moves far away, the measured non-condensable gas concentration data at different distances are sent back to the computer; at the same time, the concentration gradient of the non-condensable gas can be calculated, and the boundary or range of the non-condensable gas layer can be judged according to the concentration gradient data.

The invention also discloses a non-condensable gas layer measurement method based on laser attenuation:

First, start the laser, adjust the sliding platform to an appropriate position, the measurement beam is at one end of the test surface, and the reference beam is at the steam inlet end; turn on the computer and data acquisition instrument, and record the initial data;

Then, the condensation experiment was started according to the corresponding process of condensation of non-condensable gas on the test surface in the vacuum chamber; since the non-condensable gas was introduced before the experiment, the non-condensable gas content near the steam inlet was considered to be zero in the experiment; each experiment After the working condition reaches a steady state, adjust the measurement beam to move from the side near the test surface to the far side, and record the light intensity data on the moving track. Since the beam is only attenuated in the non-condensable gas, the attenuation degree is obtained by obtaining the received light intensity of the two beam detectors by the computer, and according to the Bell-Lambert law, there is the following relationship between the attenuation degree and the non-condensable gas concentration:

α(ν)=S(T)×g(ν-ν ₀ )×N, (2)

Among them, I is the received light intensity, I ₀ is the incident light intensity, -α(ν) is the absorption coefficient of the non-condensable gas, P is the total pressure of the gas, and L is the length of the absorption path (here, twice the cavity body width); T is the temperature of the gas, S(T) is the linear absorption intensity, g(ν—ν ₀ ) is the normalization constant of the non-condensable gas molecules, and N is the total number of molecules absorbed by the gas per unit pressure and unit volume ;

According to the ideal gas equation of state, we have:

Among them, c is the gas volume ratio, K is the Boltzmann constant; the normalization constant of the line absorption intensity and the non-condensable gas molecules can be obtained from the database, so the non-condensable gas concentration is:

Wherein, E _t is the received light intensity (measurement beam light intensity) of the first beam detector, and E _r is the received light intensity (reference beam light intensity) of the second light beam detector.

According to the concentration of non-condensable gas everywhere, the boundary position and concentration gradient of non-condensable gas layer are obtained; when the measurement beam is close to the reference beam, the measurement beam returns, and it is repeated many times to monitor the dynamic change of the non-condensable gas layer;

Finally, the measurement of each working condition is repeated three times and the average value is taken as the final measurement result, which is recorded and saved; after the measurement of all working conditions is completed, the optical measurement system and the data acquisition and processing system are turned off, the condensation experiment is ended, and the measurement is completed.

The beneficial effects of the present invention are:

(1) Using the different attenuation degrees of the laser in different concentrations of water vapor, the distribution characteristics of the non-condensable gas layer during the condensation process of the non-condensable gas steam can be measured with high precision. In order to further study the effect of the non-condensable gas layer on heat and mass transfer to provide an effective means of influence;

(2) It can realize the measurement of the distribution characteristics of the non-condensable gas layer under different condensation pressures, various condensation surfaces, various non-condensable gas components and concentrations, and provide a reference for the strengthening effect of various condensation-strengthening surfaces;

(3) It is a non-contact measurement method, which avoids the interference to the non-condensable gas layer caused by contact measurement methods such as micro-probe sampling, and improves reliability;

(4) The change process of the non-condensable gas layer during the condensation process is monitored online by the data acquisition instrument and the computer.

Description of drawings

Fig. 1 is the schematic diagram of the present invention;

Figure 2 is a cross-sectional view of a visualized condensation experimental body.

In the figure: laser 1, first beam splitter 2, first reflector 3, second reflector 4, third reflector 5, second beam splitter 6, second beam detector 7, third beam splitter 8. First beam detector 9, guide rail 10, visual condensation experiment body 11, intracavity mirror 12, data acquisition instrument 13, computer 14, condensation cavity 15, semiconductor cold stage 16, thermal insulation material 17, test surface 18, The air distribution plate 19 , the temperature sensor 20 , the optical window 21 , the second receiving light path 22 , and the first receiving light path 23 .

Detailed ways

Below in conjunction with accompanying drawing, the present invention is described in further detail:

As shown in Figures 1 and 2, in a specific embodiment of the present invention, the non-condensable gas layer measurement device based on laser attenuation includes an optical measurement system, a visualized condensation experiment body, and a data acquisition and processing system; the visualized condensation experiment The body includes an intra-cavity mirror 12 and an optical window 21; one side of the visualized condensation experiment body is provided with an optical window 21, and the inner wall surface of the other side opposite to the one side is provided with an intra-cavity mirror 12; The processing system includes a first beam detector 9, a second beam detector 7, a data acquisition instrument 13 and a computer 14; the optical measurement system is composed of a laser 1, a first beam splitter 2, a first mirror 3, a second The reflector 4, the third reflector 5, the second beam splitter 6, the third beam splitter 8, and the guide rail 10 are composed;

The first beam splitter 2 is located on the laser light path emitted by the laser 1, and the normal direction of the first beam splitter 2 has an included angle with the laser light path; the first beam splitter 2 reflects and transmits the laser light, and the first beam splitter 2 reflects and transmits the laser light. The mirror 3 is arranged on the transmitted light path of the first beam splitter 2, and its normal direction has an angle with the transmitted light path; the second mirror 4 is arranged on the reflected light path of the first beam splitter 2, and its normal There is an included angle between the direction and the reflected light path; the third reflector 5 is arranged on the reflected light path of the second reflector 4, and its normal direction has an included angle with the reflected light path; the second beam splitter 6, the third beam splitter 8 They are respectively arranged on the reflected light paths of the first reflector 3 and the third reflector 5, and their normal directions have an included angle with the reflected light paths respectively;

The transmitted beam of the first beam splitter 2 enters the second beam splitter 6 after passing through the first reflector 3 , and the reflected beam of the second beam splitter 6 enters the condensation cavity 15 through the optical window 21 and is reflected by the intra-cavity reflector 12 Enter the second beam detector 7; the reflected laser light of the first beam splitter 2 enters the third beam splitter 8 after passing through the second mirror 4 and the third mirror 5, and the transmitted beam of the third beam splitter 8 passes through the second beam splitter 8. After being reflected by the beam splitter 6, it enters the second beam detector 7 as a reference beam;

The reflected beam of the first beam splitter 2 enters the third beam splitter 8 after passing through the second mirror 4 and the third mirror 5, and the 8 reflected beams of the third beam splitter enter the condensation cavity 15 through the optical window 21, The intra-cavity mirror 12 reflects into the first beam detector 9; the transmitted beam of the first beam splitter 2 enters the second beam splitter 6 after passing through the first mirror 3, and the transmitted beam of the second beam splitter 6 passes through the third beam splitter 6. After being reflected by the beam splitter 8, it enters the first beam detector 9 as a measuring beam;

The first beam detector 9 and the second beam splitter 8 are mounted on the same sliding platform, the second beam detector 7 and the third beam splitter 6 are mounted on another sliding platform, and the two sliding platforms are mounted on the same sliding platform. On the guide rail 10; the displacement of the two sliding platforms is realized by controlling the guide rail 10 through the computer 14;

In another specific embodiment of the present invention, the first beam splitter divides the laser into two beams of equal intensity, and finally enters the beam detector respectively, so as to maintain the reference beam and the measurement when the sliding platform moves. When the light beam and other environments are attenuated, the difference in light intensity received by the two beam detectors is formed by the difference in the non-condensable gas concentration on the two paths. After data processing, the non-condensable gas concentration at the measurement beam can be obtained.

In another preferred embodiment of the present invention, the visualized condensation experimental body is a measurement body and further includes a condensation cavity 15, a semiconductor cold stage 16, a thermal insulation material 17, a test surface 18, an air distribution plate 19 and a temperature sensor 20; The air distribution plate 19 and the temperature sensor 20 are located on one wall surface of the condensation chamber 15; the semiconductor cold stage 16 is located on the other wall surface opposite to the one wall surface, and the air distribution plate 19 is located at the steam inlet to reduce the temperature. The steam flow rate ensures uniform steam in the cavity and reduces the effect of gas flow on condensation; the normal direction of the mirror 12 in the cavity is parallel to the reference beam; the temperature sensor 20 is inserted into the condensing cavity to monitor the temperature of the mixed steam in the cavity. The test surface is pasted on the cooling surface of the semiconductor cold table, and the rest of the cooling surface is covered with thermal insulation material.

Preferably, each wall surface of the condensation cavity 15 is provided with an electric heating device to prevent steam from condensing on the wall surface.

Preferably, the wall surface of the condensation cavity 15 is further provided with several flange interfaces for connecting external pipelines, equipment or for installing sensors.

Preferably, the first light beam detector 9 and the second light beam detector 7 can detect the light intensity of the incident light beam and input it into the computer 14 by the data acquisition instrument 13 for viewing and storage.

The non-condensable layer measurement method based on laser attenuation of the present invention is as follows:

First, start the laser, adjust the sliding platform to an appropriate position, the measurement beam is at one end of the test surface, and the reference beam is at the steam inlet end; turn on the computer and data acquisition instrument, and record the initial data;

Then, the condensation experiment was started according to the corresponding process of condensation of non-condensable gas on the test surface in the vacuum chamber; since the non-condensable gas was introduced before the experiment, the non-condensable gas content near the steam inlet was considered to be zero in the experiment; each experiment After the working condition reaches a steady state, adjust the measurement beam to move from the side near the test surface to the far side, and record the light intensity data on the moving track. Since the beam is only attenuated in the non-condensable gas, the attenuation degree is obtained by obtaining the received light intensity of the two beam detectors by the computer, and according to the Bell-Lambert law, there is the following relationship between the attenuation degree and the non-condensable gas concentration:

α(ν)=S(T)×g(ν-ν ₀ )×N,

Among them, I is the received light intensity, I ₀ is the incident light intensity, -α(ν) is the absorption coefficient of the non-condensable gas, P is the total pressure of the gas, and L is the length of the absorption path (here, twice the cavity body width); T is the temperature of the gas, S(T) is the linear absorption intensity, g(ν—ν ₀ ) is the normalization constant of the non-condensable gas molecules, and N is the total number of molecules absorbed by the gas per unit pressure and unit volume ;

According to the ideal gas equation of state, we have:

Among them, c is the gas volume ratio, K is the Boltzmann constant; the normalization constant of the line absorption intensity and the non-condensable gas molecules can be obtained from the database, so the non-condensable gas concentration is:

Wherein, E _t is the received light intensity (measurement beam light intensity) of the first beam detector, and E _r is the received light intensity (reference beam light intensity) of the second light beam detector.

According to the concentration of non-condensable gas everywhere, the boundary position and concentration gradient of non-condensable gas layer are obtained; when the measurement beam is close to the reference beam, the measurement beam returns, and it is repeated many times to monitor the dynamic change of the non-condensable gas layer;

Finally, the measurement of each working condition is repeated three times and the average value is taken as the final measurement result, which is recorded and saved; after the measurement of all working conditions is completed, the optical measurement system and the data acquisition and processing system are turned off, the condensation experiment is ended, and the measurement is completed.

Claims (7)

1. A non-condensable gas layer measuring device based on laser attenuation is characterized by comprising an optical measuring system, a visual condensation experimental body and a data acquisition and processing system;

the visual condensation experimental body comprises an intracavity reflector (12) and an optical window (21); an optical window (21) is arranged on one side of the visual condensation experimental body, and an intracavity reflector (12) is arranged on the inner wall surface of the other side opposite to the one side;

the data acquisition and processing system comprises a first light beam detector (9), a second light beam detector (7), a data acquisition instrument (13) and a computer (14);

the optical measurement system consists of a laser (1), a first beam splitter (2), a first reflector (3), a second reflector (4), a third reflector (5), a second beam splitter (6), a third beam splitter (8) and a guide rail (10);

the first beam splitter (2) is positioned on a laser light path emitted by the laser (1), and an included angle exists between the normal direction of the first beam splitter (2) and the laser light path; the first beam splitter (2) reflects and transmits laser, the first reflector (3) is arranged on a transmission light path of the first beam splitter (2), and an included angle exists between the normal direction of the first reflector and the transmission light path; the second reflecting mirror (4) is arranged on a reflecting light path of the first beam splitter (2), and an included angle exists between the normal direction of the second reflecting mirror and the reflecting light path; the third reflector (5) is arranged on the reflection light path of the second reflector (4), and the normal direction of the third reflector and the reflection light path form an included angle; the second beam splitter (6) and the third beam splitter (8) are respectively arranged on the reflection light paths of the first reflector (3) and the third reflector (5), and included angles exist between the normal direction of the second beam splitter and the reflection light paths respectively;

the transmitted light beam of the first beam splitter (2) enters the second beam splitter (6) after passing through the first reflector (3), the reflected light beam of the second beam splitter (6) enters the condensation cavity (15) through the optical window (21), and enters the second light beam detector (7) after being reflected by the intracavity reflector (12); the reflected laser of the first beam splitter (2) enters a third beam splitter (8) after passing through a second reflector (4) and a third reflector (5), and the transmitted beam of the third beam splitter (8) enters a second beam detector (7) after being reflected by a second beam splitter (6) and is used as a reference beam;

the reflected light beam of the first beam splitter (2) enters a third beam splitter (8) after passing through a second reflector (4) and a third reflector (5), the reflected light beam of the third beam splitter (8) enters a condensation cavity (15) through an optical window (21), and is reflected by an in-cavity reflector (12) to enter a first light beam detector (9); the transmitted light beam of the first beam splitter (2) enters the second beam splitter (6) after passing through the first reflector (3), and the transmitted light beam of the second beam splitter (6) enters the first light beam detector (9) after being reflected by the third beam splitter (8) to be used as a measuring light beam;

the first beam detector (9) and the second beam splitter (8) are arranged on the same sliding platform, the second beam detector (7) and the third beam splitter (6) are arranged on the other sliding platform, and the two sliding platforms are arranged on the guide rail (10); the displacement of the two sliding platforms is realized by controlling the guide rail (10) through a computer (14); the computer (14) is respectively connected with the first beam detector (9) and the second beam detector (7) through the data acquisition instrument (13).

2. The measuring device as claimed in claim 1, wherein the first beam splitter splits the laser beam into two beams of equal intensity, and the two beams of equal intensity finally enter the beam detectors respectively, so as to achieve the purpose of maintaining the attenuation of the reference beam and the measuring beam in the same environment when the sliding platform moves, the difference between the intensities received by the two beam detectors is formed by the difference between the concentrations of the non-condensable gases in the two paths, and the concentration of the non-condensable gas at the measuring beam can be obtained through data processing.

3. The measuring device according to claim 1, wherein the visual condensation experimental body is a measuring body and further comprises a condensation cavity (15), a semiconductor cold stage (16), a heat insulating material (17), a test surface (18), a wind distribution plate (19) and a temperature sensor (20); the air distribution plate (19) and the temperature sensor (20) are positioned on one wall surface of the condensation cavity (15); the semiconductor cooling platform (16) is positioned on the other wall surface opposite to the one wall surface, and the air distribution plate (19) is positioned at the steam inlet and used for reducing the influence of gas flow on condensation; the normal direction of the intracavity reflector (12) is parallel to the reference beam; the temperature sensor (20) measures the temperature of the mixed steam in the cavity, the testing surface is stuck on the refrigerating surface of the semiconductor cold stage, and the rest part of the refrigerating surface is coated with a heat-insulating material.

4. A measuring device according to claim 1, characterized in that each wall of the condensation chamber (15) is provided with electric heating means to prevent condensation of steam on the wall.

5. The measuring device according to claim 1, characterized in that the wall of the condensation chamber (15) is further provided with a plurality of flange interfaces for connecting external pipes, equipment or for installing sensors.

6. The measuring device according to claim 1, characterized in that the first beam detector (9) and the second beam detector (7) can detect the intensity of the incident beam and input the intensity into the computer (14) for viewing and storing by the data collector (13).

7. A laser attenuation based non-condensable gas layer measurement method using the apparatus of claim 1, wherein:

firstly, starting a laser (1), adjusting a sliding platform to a working position, wherein a measuring beam is arranged at one end of a test surface (18), and a reference beam is arranged at one end of a steam inlet; opening a computer (14) and a data acquisition instrument (13) and recording initial data;

then, starting a condensation experiment according to a corresponding process of condensation of the non-condensable gas-containing vapor on the test surface (18) in the condensation chamber (15); after each experiment working condition reaches a stable state, adjusting the measuring light beam to move from one side close to the test surface (18) to a far side, recording light intensity data on a moving track, returning the measuring light beam when the measuring light beam is tightly attached to the reference light beam, and repeating for multiple times to monitor the dynamic change of the non-condensable layer;

finally, repeating the measurement of each working condition for three times, taking the average value as a final measurement result, and recording and storing the average value; and after all the working conditions are measured, closing the optical measuring system and the data acquisition and processing system, ending the condensation experiment, and finishing the measurement.

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