CN109975233B - Non-condensable gas layer measuring device and method based on laser attenuation - Google Patents
Non-condensable gas layer measuring device and method based on laser attenuation Download PDFInfo
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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
Technical Field
The invention relates to 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.
Background
Condensation of water vapor is often seen in industrial production. Steam condensation in most industrial equipment is usually accompanied by a small amount of non-condensable gas, for example, in the process of condensing exhaust steam in a condenser of a power plant, a certain vacuum degree exists in the condenser, and partial air enters after long-time operation; when the central air conditioner is used for cooling in summer, water vapor in the air can be condensed on the surface of an evaporator coil; the condensation of flash steam in a multi-stage flash desalination system is often accompanied by the presence of a certain amount of non-condensable gases. According to research, even the existence of non-condensable gas with low content can have great influence on the condensation process of the steam. When the steam is condensed on the cold surface, the steam forms condensate and adheres to the surface, and the non-condensable gas contained in the gas flow is gathered near the surface to form a gas layer due to diffusion. The non-condensing layer can cause the partial pressure of steam near the surface to be reduced, the saturation temperature is reduced, the heat transfer temperature difference is reduced, and the heat transfer driving force in the condensing process is reduced; meanwhile, a high-concentration noncondensable gas layer is formed near the surface, the concentration gradient of the noncondensable gas layer is opposite to that of steam, the diffusion resistance of the steam to the surface is increased, the mass transfer process of steam condensation is weakened, and the condensation process is further inhibited. Therefore, the formation of the noncondensable gas layer is a key link for restricting the strengthening of the condensation process, and therefore, the research on the characteristics of the noncondensable gas layer in the condensation process of the water vapor containing the noncondensable gas is of great significance.
In experimental research on the condensation of steam containing non-condensable gas, the influence of the content, components and the like of the non-condensable gas on the condensation heat exchange coefficient is mostly researched at present, and the work related to the measurement of a non-condensable gas layer and the like is not carried out. Fourier transform infrared spectroscopy (FTIR) can realize the online measurement to vapor concentration in the gas mixture, but need let in the gas that awaits measuring into the FTIR analysis appearance during the measurement, be not fit for carrying out the normal position measurement to noncondensable gas layer in condensation experimentation. In order to establish a theoretical model suitable for various novel micro-nano structure reinforced surfaces on a classical condensation model and verify the reliability of numerical simulation of a condensation process, an accurate experimental method is indispensable for checking results.
Disclosure of Invention
The invention provides a device and a method for measuring a noncondensable gas layer based on laser attenuation aiming at the current technical problem. According to the invention, the laser attenuation measurement of the non-condensable gas-containing steam in the condensation cavity is realized through the optical measurement system, the difference value of the light intensity of the measurement laser and the reference laser is analyzed by the data acquisition and processing system, so that the non-condensable gas concentration gradient and the non-condensable gas layer thickness on the measurement path are obtained, and an effective means is provided for further research on the condensation phenomenon of the non-condensable gas-containing steam.
The purpose of the invention is realized as follows:
a non-condensable gas layer measuring device based on laser attenuation comprises 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 and an optical window; an optical window is arranged on one side of the visual condensation experimental body, and an intracavity reflector 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, a second light beam detector, a data acquisition instrument and a computer;
the optical measurement system consists 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 positioned on a laser light path emitted by the laser, and an included angle is formed between the normal direction of the first beam splitter and the laser light path; the first beam splitter reflects and transmits laser, the first reflector is arranged on a transmission light path of the first beam splitter, and an included angle exists between the normal direction of the first reflector and the transmission light path; the second reflecting mirror is arranged on a reflecting light path of the first beam splitter, and an included angle exists between the normal direction of the second reflecting mirror and the reflecting light path; the third reflector is arranged on the reflection light path of the second reflector, and the normal direction of the third reflector forms an included angle with the reflection light path; the second beam splitter and the third beam splitter are respectively arranged on the reflection light paths of the first reflector and the third reflector, 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 enters a second beam splitter after passing through a first reflector, and the reflected light beam of the second beam splitter enters a condensation cavity through an optical window and enters a second light beam detector after being reflected by an intra-cavity reflector; the reflected laser of the first beam splitter enters a third beam splitter after passing through a second reflector and a third reflector, and the transmitted beam of the third beam splitter enters a second beam detector after being reflected by the second beam splitter to be used as a reference beam;
the reflected beam of the first beam splitter enters a third beam splitter after passing through a second reflector and a third reflector, and the reflected beam of the third beam splitter enters a condensation cavity through an optical window and enters a first beam detector after being reflected by an intra-cavity reflector; the transmitted beam of the first beam splitter enters a second beam splitter after passing through a first reflector, and the transmitted beam of the second beam splitter enters a first beam detector after being reflected by a third beam splitter to be used as a measuring beam;
the first beam detector and the second beam splitter are arranged on the same sliding platform, the second beam detector and the third beam splitter are arranged on the other sliding platform, and the two sliding platforms are arranged on the guide rail; the displacement of the two sliding platforms is realized by controlling the guide rail through a computer; the computer is connected with the first light beam detector and the second light beam detector through the data acquisition instrument.
Preferably, the first beam splitter divides the laser into two beams with equal light intensity, and the two beams finally enter the beam detectors respectively so as to realize that the environment attenuation of the reference beam and the measuring beam can be still kept when the sliding platform moves, the light intensity difference received by the two beam detectors is formed by the concentration difference of the non-condensable gas on the two paths, and the concentration of the non-condensable gas at the measuring beam can be obtained through data processing.
Preferably, the visual condensation experimental body is a measurement main body and further comprises a condensation cavity, a semiconductor cold table, a heat insulation material, a test surface, an air distribution plate and a temperature sensor; the air distribution plate and the temperature sensor are positioned on one wall surface of the condensation cavity; the semiconductor cooling table is positioned 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 flow velocity of steam, ensure the uniformity of the steam in the cavity and reduce the influence of gas flow on condensation; the normal direction of the reflector in the cavity is parallel to the reference beam; the temperature sensor is inserted into the condensation cavity and used for monitoring the temperature of the mixed steam in the cavity. The test surface is adhered to the refrigerating surface of the semiconductor cold stage, and the rest part of the refrigerating surface is coated with a heat-insulating 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 surface of the condensation cavity is further provided with a plurality of flange interfaces for connecting external pipelines and equipment or for installing sensors.
Preferably, the first light beam detector and the second light beam detector can detect the light intensity of the incident light beam, and the light intensity is input into a computer by the data acquisition instrument to be viewed and stored.
The reflected beam of the second beam splitter and the transmitted beam of the third beam splitter enter a second beam detector together to form a reference beam, and the non-condensable gas part is measured; the transmitted beam of the second beam splitter and the reflected beam of the third beam splitter enter a third beam detector together to form a measuring beam and measure a mixed gas part; the light intensity difference received by the two light beam detectors is formed by the concentration difference of water vapor on the two paths;
the first beam splitter divides the laser into two beams with equal light intensity, and the two beams finally enter the beam detector respectively, so that the attenuation of the reference beam, the measuring beam and other environments can be still kept when the sliding platform moves, and the measuring precision is ensured;
the condensation cavity can provide a vacuum environment for condensing steam containing non-condensable gas so as to control the components of the non-condensable gas, a plurality of flange interfaces are arranged on the condensation cavity for connecting the instrument and the pipeline, and an electric heating device and heat insulation cotton are laid in each wall surface of the condensation cavity; the semiconductor cold state is inserted into the condensation cavity through the square flange, the cold end is used for testing the temperature control of the surface in the cavity, and the periphery of the cold platform is wrapped with a heat insulation material;
the test surface is connected with the semiconductor cold stage through the heat conducting glue to reduce the contact thermal resistance and realize uniform surface temperature;
the data acquisition instrument calculates the non-condensable gas concentration of the path where the measuring light beam passes through according to the relation between the light beam intensity attenuation and the non-condensable gas concentration by analyzing the light intensity difference acquired by the light beam detector; as the measuring beam moves away from the test surface, measured non-condensable gas concentration data at different distances is transmitted back to the computer; meanwhile, the concentration gradient of the non-condensable gas can be calculated, and the boundary or the range of the non-condensable gas layer is judged according to the concentration gradient data.
The invention also discloses a non-condensable gas layer measuring method based on laser attenuation, which comprises the following steps:
firstly, starting a laser, adjusting a sliding platform to a proper position, wherein a measuring beam is arranged at one end of a test surface, and a reference beam is arranged at one end of a steam inlet; opening a computer and a data acquisition instrument, and recording initial data;
then, starting a condensation experiment according to a corresponding process of condensation of the steam containing the non-condensable gas on the test surface in the vacuum cavity; as the non-condensable gas is introduced before the experiment, the content of the non-condensable gas close to the steam inlet end is considered to be zero in the experiment; and after each experimental working condition reaches a stable state, adjusting the measuring light beam to move from one side close to the test surface to a far side, and recording light intensity data on a moving track. Because the light beam only attenuates in the non-condensable gas, the attenuation degree is obtained by obtaining the received light intensity of the two light beam detectors through a computer, and according to the Bell-Lanbeite law, the following relation exists between the attenuation degree and the concentration of the non-condensable gas:
α(ν)＝S(T)×g(ν-ν0)×N， (2)
where I is the received light intensity, I0is the intensity of incident light, - 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 width in the cavity); t is the temperature of the gas, S (T) is the linear absorption intensity, g (v-v)0) The normalization constant of the non-condensable gas molecules is shown, and N is the total number of molecules of the absorbed gas in unit pressure intensity and unit volume;
according to the ideal gas state equation, there are:
wherein c is the gas volume ratio and K is the Boltzmann constant; the linear absorption intensity and the normalization constant of the non-condensable gas molecules can be obtained from the database, so that the concentration of the non-condensable gas is as follows:
wherein E istThe received light intensity (measuring beam intensity), E, of the first beam detectorrThe received light intensity of the second beam detector (reference beam light intensity).
Obtaining the boundary position and the concentration gradient of the non-condensable gas layer according to the concentration of the non-condensable gas at each position; when the measuring beam is tightly attached to the reference beam, the measuring beam returns, and the dynamic change of the non-condensable layer is monitored by repeating the steps for a plurality of times;
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.
The invention has the beneficial effects that:
(1) the distribution characteristics of the noncondensable gas layer in the condensation process of the steam containing the noncondensable gas are measured with high precision by utilizing the different attenuation degrees of the laser in the water vapor with different concentrations, so that an effective way is provided for further researching the influence of the noncondensable gas layer on heat and mass transfer;
(2) the method 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 provides reference basis for the strengthening effect of various condensation strengthening surfaces;
(3) the method belongs to a non-contact measurement method, avoids the interference on a non-condensable layer caused by contact measurement methods such as microprobe sampling and the like, and improves the reliability;
(4) the change process of the non-condensable layer in the condensation process is monitored on line through a data acquisition instrument and a computer.
Drawings
FIG. 1 is a schematic view of the present invention;
fig. 2 is a cross-sectional view of a visual condensation experimental body.
In the figure: the device comprises 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 second light beam detector 7, a third beam splitter 8, a first light beam detector 9, a guide rail 10, a visual condensation experimental body 11, an in-cavity reflector 12, a data acquisition instrument 13, a computer 14, a condensation cavity 15, a semiconductor cooling table 16, a heat insulation material 17, a test surface 18, an air distribution plate 19, a temperature sensor 20, an optical window 21, a second receiving light path 22 and a first receiving light path 23.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
as shown in fig. 1 and 2, in one embodiment of the present invention, the apparatus for measuring a non-condensable gas layer based on laser attenuation comprises an optical measurement 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 reflecting mirror 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 the reflecting light path of the first beam splitter 2, and the normal direction of the second reflecting mirror forms an included angle with 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 in-cavity reflector 12; the reflected laser of the first beam splitter 2 enters a third beam splitter 8 after passing through a second reflecting mirror 4 and a third reflecting mirror 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 to be 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 a cavity reflector 12 to enter a first light beam detector 9; the transmitted beam of the first beam splitter 2 enters the second beam splitter 6 after passing through the first reflector 3, and the transmitted beam of the second beam splitter 6 enters the first beam detector 9 after being reflected by the third beam splitter 8 to be used as a measuring 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 the computer 14; the computer 14 is connected to the first and second beam detectors 9 and 7, respectively, via the data acquisition unit 13.
In another embodiment of the invention, the first beam splitter splits the laser into two beams with equal light intensity, and the two beams finally enter the beam detectors respectively to realize that the environment attenuation of the reference beam and the measuring beam can be still maintained when the sliding platform moves, the light intensity difference received by the two beam detectors is formed by the concentration difference of the non-condensable gas on the two paths, and the concentration of the non-condensable gas at the measuring beam can be obtained through data processing.
In another preferred embodiment of the invention, the visualized condensation experimental body is a measurement main body and further comprises a condensation cavity 15, a semiconductor cold stage 16, a heat insulating 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 positioned on one wall surface of the condensation cavity 15; the semiconductor cooling table 16 is positioned on the other wall surface opposite to the one wall surface, and the air distribution plate 19 is arranged at the steam inlet to reduce the flow rate of steam, ensure the uniformity of the steam in the cavity and reduce the influence of gas flow on condensation; the normal direction of the intracavity reflector 12 is parallel to the reference beam; a temperature sensor 20 is inserted into the condensation chamber for monitoring the temperature of the mixed vapor within the chamber. The test surface is adhered to the refrigerating surface of the semiconductor cold stage, and the rest part of the refrigerating surface is coated with a heat-insulating material.
Preferably, each wall of the condensation chamber 15 is provided with an electric heating device to prevent the steam from condensing on the wall.
Preferably, the wall surface of the condensation cavity 15 is further provided with a plurality of flange interfaces for connecting external pipelines and 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 the light intensity is input into the computer 14 by the data acquisition instrument 13 to be viewed and stored.
The method for measuring the non-condensable gas layer based on laser attenuation comprises the following steps:
firstly, starting a laser, adjusting a sliding platform to a proper position, wherein a measuring beam is arranged at one end of a test surface, and a reference beam is arranged at one end of a steam inlet; opening a computer and a data acquisition instrument, and recording initial data;
then, starting a condensation experiment according to a corresponding process of condensation of the steam containing the non-condensable gas on the test surface in the vacuum cavity; as the non-condensable gas is introduced before the experiment, the content of the non-condensable gas close to the steam inlet end is considered to be zero in the experiment; and after each experimental working condition reaches a stable state, adjusting the measuring light beam to move from one side close to the test surface to a far side, and recording light intensity data on a moving track. Because the light beam only attenuates in the non-condensable gas, the attenuation degree is obtained by obtaining the received light intensity of the two light beam detectors through a computer, and according to the Bell-Lanbeite law, the following relation exists between the attenuation degree and the concentration of the non-condensable gas:
α(ν)＝S(T)×g(ν-ν0)×N，
where I is the received light intensity, I0for incident light intensity, - α (v) is the absorption coefficient of the non-condensable gas, P is the total pressure of the gas, L is the length of the absorption path (here, twice the width in the cavity), T is the temperature of the gas, S (T) is the linear absorption intensity, g (v-v)0) The normalization constant of the non-condensable gas molecules is shown, and N is the total number of molecules of the absorbed gas in unit pressure intensity and unit volume;
according to the ideal gas state equation, there are:
wherein c is the gas volume ratio and K is the Boltzmann constant; the linear absorption intensity and the normalization constant of the non-condensable gas molecules can be obtained from the database, so that the concentration of the non-condensable gas is as follows:
wherein E istThe received light intensity (measuring beam intensity), E, of the first beam detectorrThe received light intensity of the second beam detector (reference beam light intensity).
Obtaining the boundary position and the concentration gradient of the non-condensable gas layer according to the concentration of the non-condensable gas at each position; when the measuring beam is tightly attached to the reference beam, the measuring beam returns, and the dynamic change of the non-condensable layer is monitored by repeating the steps for a plurality of times;
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.
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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| CN201910189030.4A CN109975233B (en) | 2019-03-13 | 2019-03-13 | Non-condensable gas layer measuring device and method based on laser attenuation |
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| DE2045386C3 (en) * | 1970-08-07 | 1980-04-03 | Nils Dr.Med. 8035 Gauting Kaiser | Device for determining the CO2 content of a biological substance |
| JP4732277B2 (en) * | 2006-08-23 | 2011-07-27 | トヨタ自動車株式会社 | Gas analyzer and gas analysis method |
| TWI547683B (en) * | 2010-12-06 | 2016-09-01 | Univ Nat Central | Multi-wavelength optical measurement method for thin film elements |
| CN104359564B (en) * | 2014-11-19 | 2018-11-02 | 湖北三江航天红峰控制有限公司 | A kind of pulsed laser light beam quality synchronized measurement system and its synchronisation control means |
| CN105487081B (en) * | 2016-01-07 | 2019-04-02 | 福建省计量科学研究院 | A kind of differential detection system for laser velocimeter |
| CN106547189B (en) * | 2016-11-25 | 2019-11-15 | 西安科技大学 | Reflective digital holographic microscopic imaging system and method based on pulse laser |
| CN206378393U (en) * | 2017-01-18 | 2017-08-04 | 西安科技大学 | A kind of optical fiber type apparatus for measuring dust concentration |
| CN108981592B (en) * | 2018-06-25 | 2021-08-17 | 浙江大学 | Device and method for measuring thickness and temperature of micro-liquid film in contact melting based on laser interference and attenuation |
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