CN115128119A - Device and method for measuring surface emissivity of liquid metal - Google Patents
Device and method for measuring surface emissivity of liquid metal Download PDFInfo
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- CN115128119A CN115128119A CN202111310172.5A CN202111310172A CN115128119A CN 115128119 A CN115128119 A CN 115128119A CN 202111310172 A CN202111310172 A CN 202111310172A CN 115128119 A CN115128119 A CN 115128119A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/18—Investigating or analyzing materials by the use of thermal means by investigating thermal conductivity
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Abstract
The invention relates to a device and a method for measuring the surface emissivity of liquid metal, belongs to the technical field of reactor thermohydraulics, and solves the problem that the radiation emissivity of the surface of the liquid metal cannot be determined in the radiation heat exchange calculation in the prior art. The measuring device comprises: the liquid-containing unit is a container for containing liquid metal; the measuring unit comprises an observation window immersed in the liquid metal and a radiation temperature detector communicated with the optical path of the observation window. The direct measurement of the temperature of the high-temperature liquid metal and the indirect measurement of the radiation emissivity are realized by applying a visual temperature measurement method.
Description
Technical Field
The invention relates to the technical field of reactor thermal hydraulics, in particular to a device and a method for measuring the surface emissivity of liquid metal.
Background
According to the definition of heat transfer science, emissivity is a physical parameter for representing the radiation heat transfer capability of an object, is only related to the material, structure, roughness and the like of the object, is one of basic parameters of the thermophysical property of the material, and refers to the ratio of the radiation quantity of the object at a specified temperature T to the radiation quantity of a black body at the same temperature.
The current methods for measuring surface emissivity mainly comprise: calorimetry, reflectometry, multiple wavelength methods, and energy methods. Conventional measurement methods are mostly directed to solids.
Liquid metal as a novel material has many advantages such as high thermal conductivity, high boiling point, large specific heat capacity, and is widely used in the fields of nuclear engineering, computer chip cooling, electronic printing, biomedicine, and the like. In the industrial field, liquid metal radiation heat transfer calculation has wide design and use requirements, in order to calculate the radiation heat exchange quantity, the surface radiation emissivity of liquid metal needs to be obtained, and the measurement of the surface emissivity of high-temperature liquid metal has many difficulties.
Disclosure of Invention
In view of the foregoing analysis, the embodiments of the present invention are directed to a device and a method for measuring surface emissivity of liquid metal, which at least solve one of the following technical problems: (1) the tested samples have very high temperature (generally over 300 ℃), and are difficult to measure for a long time; (2) small liquid drops generated after the liquid metal is evaporated can be condensed on the surface of the sample observation window, so that the measurement accuracy is influenced; and (3) the measured object is in a liquid state and has good fluidity, and the conventional sample measurement is mostly aimed at solids, so that the problems of heating, temperature measurement and the like are difficult.
In one aspect, the present invention provides a device for measuring surface emissivity of liquid metal, comprising: the device comprises a liquid containing unit, a measuring unit and a protecting unit;
the liquid containing unit is a container for containing liquid metal;
the measuring unit comprises an observation window immersed in the liquid metal and a radiation temperature detector communicated with an optical path of the observation window, and the radiation temperature detector is used for measuring a radiation temperature value of the liquid metal;
the protection unit is used for providing inert atmosphere protection for the container.
Further, the measuring unit also comprises a liquid metal surface temperature measuring device, and the emissivity is calculated based on the following formula:
in the formula, T r -the radiation temperature measured for the thermal infrared imager,
T 0 -the temperature of the surface of the liquid metal,
T u -the temperature of the surroundings,
n-approximate index.
Further, the measuring unit also comprises a bracket arranged outside the observation window.
Further, the liquid metal surface temperature measuring device is mounted on the bracket.
Further, the liquid containing unit comprises a container body and a connecting pipe connected with the container body, and the connecting pipe forms an optical passage between the observation window and the radiation temperature detector; the container body is in a sealed state, and the container is protected by inert atmosphere provided by the protection unit.
Furthermore, the measuring unit also comprises a cylinder body, the observation window is fixed at one end of the cylinder body, the cylinder body penetrates through the connecting pipe, and an optical passage between the observation window and the radiation temperature detector is formed inside the cylinder body.
Furthermore, the observation window and the cylinder body and the connecting pipe are in sealing connection.
Furthermore, the observation window of the measurement unit adopts infrared glass with the light transmittance of more than 95%.
Furthermore, the infrared glass is high-temperature-resistant infrared glass, and the thickness of the infrared glass is 7-11 mm.
The invention also provides a method for measuring the surface emissivity of the liquid metal, and by adopting the measuring device, the measuring method comprises the following steps:
step 1: heating the liquid metal to a specified temperature;
step 2: after the temperature of the liquid metal is stable, measuring the temperature by using a thermal infrared imager;
and step 3: and (3) substituting the measurement data into the following formula to calculate the surface radiation emissivity of the liquid metal at the temperature:
in the formula, T r -the radiation temperature measured for the thermal infrared imager,
T 0 -the temperature of the surface of the liquid metal,
T u -the temperature of the surroundings,
n-approximation index;
and 4, step 4: and (4) adjusting the heating temperature to another temperature, and repeating the step (1) to the step (3) to obtain the surface radiation emissivity of the liquid metal at different temperatures.
Compared with the prior art, the invention can realize at least one of the following beneficial effects:
1. according to the device for measuring the surface emissivity of the liquid metal, provided by the invention, the measuring unit comprises the observation window immersed in the liquid metal and the radiation temperature detector communicated with the optical path of the observation window, so that the influence on the measurement accuracy and the influence on the measurement accuracy caused by the absorption of the radiation by the aerosol due to the condensation of liquid drops generated after the evaporation of the liquid metal on the glass tube when the emissivity of the liquid metal is measured are avoided.
2. The measuring device is provided with the liquid containing unit, the measuring unit and the protecting unit, the visual window is arranged at the top of the measuring unit, the temperature and the radiation emissivity of the liquid metal can be measured in real time, and the safety protecting device is further arranged, so that the surface radiation emissivity of the liquid metal at different temperatures can be measured, and the liquid metal and the protective gas can be prevented from leaking.
3. The sample container of the measuring device provided by the invention is filled with inert gas-argon gas as protective gas of liquid metal, so that the liquid metal can be prevented from contacting with air to generate chemical reaction.
4. According to the measuring device provided by the invention, the sealing top cover is arranged at the top of the measuring unit, two flanges of the top cover are connected with the top of the connecting pipe through bolts and the red copper gasket, so that a liquid metal leakage channel is completely blocked, high-temperature-resistant glass sheets at the top end of the stainless steel cylinder can be prevented from being cracked, and the liquid metal can be prevented from leaking out when an accident happens.
In the invention, the technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.
FIG. 1 is a schematic view of a device for measuring surface emissivity of liquid metal provided by the present invention;
fig. 2 is a schematic diagram of a position relationship between a stainless steel support and an observation window when the stainless steel support of the device for measuring surface emissivity of liquid metal provided by the invention is of a sleeve structure.
Reference numerals:
1-liquid metal to be measured; 2-high temperature resistant infrared glass observation window; 3-tin soldering; 4-stainless steel brackets; 41-a holder sleeve; 42-a stand leg; 5-stainless steel cylinder; 6-connecting pipe; 7-a graphite gasket; 8-threaded connection; 9-annular gland; 10-high temperature sealant; 11-high temperature resistant infrared glass sheet; 12-infrared thermal imaging system; 13-a flange; 14-copper washer; 15-cover plate; 16-bolt; 17-thermocouple temperature measuring point; 18-inert protective gas.
Detailed Description
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate preferred embodiments of the invention and together with the description, serve to explain the principles of the invention and not to limit the scope of the invention.
The current methods for measuring surface emissivity mainly comprise: calorimetry, reflectometry, multiple wavelength methods, and energy methods. Among them, calorimetry and energy methods are the methods commonly used in the industry to measure emissivity. The principle of calorimetry is: according to the heat conduction theory, a heat exchange system is formed by the measured object and the surrounding environment, the temperature of the relevant point of the measured object is measured, and the emissivity of the object is solved by utilizing a heat conduction equation. The calorimetry has the advantages of simple system, fast measuring speed, wide measuring range, high accuracy and the like, but when the method is used, the uneven surface temperature of a measured object can cause larger calculation error, and the measurement is needed in a vacuum environment. The principle of the energy method is as follows: under the same measurement means and temperature, the ratio of the radiation power of the sample to the radiation power of the blackbody radiation source is the emissivity of the sample. The energy method has the advantages of wide application range, simpler measuring system, high measuring precision and the like.
Conventional measurement methods are mostly directed to solids. Liquid metal as a novel material has many advantages such as high thermal conductivity, high boiling point, large specific heat capacity and the like, and is widely applied in the fields of nuclear engineering, computer chip cooling, electronic printing, biomedicine and the like at present. In the industrial field, liquid metal radiation heat transfer calculation has wide design and use requirements, in order to calculate the radiation heat exchange quantity, the surface radiation emissivity of liquid metal needs to be obtained, and the measurement of the surface emissivity of high-temperature liquid metal has many difficulties. In research, the following difficulties are mainly found in the measurement of the surface emissivity of the high-temperature liquid metal: firstly, the tested samples have very high temperature (generally over 300 ℃), and are difficult to measure for a long time; secondly, small liquid drops generated after the liquid metal is evaporated can be condensed on the surface of the sample observation window, so that the measurement accuracy is influenced; and thirdly, the measured object is in a liquid state and has good fluidity, and conventional sample measurement is difficult for solids, heating, temperature measurement and the like.
Based on the above problem, in one aspect, the present invention discloses a device for measuring surface emissivity of liquid metal, as shown in fig. 1, the device comprises: the device comprises a liquid containing unit, a measuring unit and a protecting unit;
the liquid containing unit is a container for containing liquid metal;
the measuring unit comprises an observation window immersed in the liquid metal and a radiation temperature detector communicated with an optical path of the observation window, and the radiation temperature detector is used for measuring a radiation temperature value of the liquid metal;
the protection unit is used for providing inert atmosphere protection for the container.
Considering that the measured samples have very high temperature, the condensation of small liquid drops generated after the liquid metal is evaporated on the surface of the observation window can influence the measurement accuracy, meanwhile, the free liquid level of the liquid metal in nuclear engineering is usually covered with protective gas, the liquid metal is evaporated at high temperature and is mixed with the protective gas to form aerosol, the measurement of the temperature is directly influenced, and further the measurement of the emissivity is inaccurate, therefore, the observation window is directly immersed into the liquid metal, compared with the prior art, the emissivity measuring device provided by the invention avoids the absorption of the aerosol to radiation and the condensation of metal vapor on the observation window to influence the observation temperature measurement. That is, the invention inserts the measuring end of the measuring device into the liquid metal instead of being above the liquid metal surface, so as to avoid the influence on the measuring accuracy caused by the condensation of liquid drops generated after the liquid metal is evaporated on the glass tube and the influence on the measuring accuracy caused by the absorption of the aerosol on the radiation when the emissivity of the liquid metal is measured.
In consideration of ensuring that the radiation temperature detected by the thermal infrared imager is as accurate as possible, the observation window is made of infrared glass with the light transmittance of more than 95%, and the observation window is specifically made of high-temperature-resistant infrared glass, so that the parameter requirement can be met.
More specifically, the thickness of the high-temperature-resistant infrared glass observation window is 7-11 mm, and the strength of the glass is insufficient when the thickness is too low, and the transmittance is influenced when the thickness is higher than the thickness.
In order to prevent the liquid metal from contacting with air and causing chemical reaction, the container for containing the liquid metal is in a sealed state, and the container is protected by inert atmosphere.
The invention adopts the technical scheme that the observation window is immersed into liquid metal, in order to form an observation light path, the measuring unit also comprises a cylinder, and the liquid containing unit comprises a container body and a connecting pipe connected with the container body. The observation window is fixed at one end of the cylinder, the cylinder of the measurement unit for fixing the observation window enters the container through the connecting pipe, the other end of the cylinder is connected with the connecting pipe, and an optical passage between the observation window and the radiation temperature detector is formed inside the cylinder.
In order to ensure that the container is in a sealed state, the observation window and the cylinder body and the connecting pipe are in sealed connection.
Specifically, the observation window is fixedly connected with one end of the cylinder body through tin soldering. The observation window is changed in the later stage of considering, also can adopt to dismantle between observation window and the barrel and be connected, like buckle structure.
In order to facilitate the connection between the observation window and the cylinder, the observation window adopts a structure matched with the cylinder, and the opening end of the cylinder of the observation window is fixedly or detachably connected with one end of the cylinder of the measuring unit.
Because the observation window adopts high temperature resistant infrared glass, because glass has heat conduction anisotropy, and the connection structure between observation window and the barrel is long-time in the high temperature operating mode, for preventing not hard up, the measuring unit still is including setting up the outside support at the observation window.
In a preferred scheme, above-mentioned support is the sleeve structure, adopts the sleeve structure can improve the homogeneity of observation window temperature, can also be to playing fixed and supporting role, protection observation window. Specifically, when the stainless steel bracket is of a sleeve structure, the stainless steel bracket comprises a bracket sleeve and a bracket leg, and the position relationship between the stainless steel bracket and the observation window is shown in fig. 2.
The measuring unit further comprises a liquid metal surface temperature measuring device, such as a thermocouple, for measuring the true temperature of the liquid metal surface, which may be mounted on the sleeve structure.
The special container for measurement can be arranged in consideration of the use requirement of the surface emissivity measurement of the liquid metal, and when the special container for measurement is adopted, the support can be directly arranged at the bottom of the container and is in a position opposite to the container connecting pipe, and the observation window is directly matched with the support during assembly, so that the effects of protection, temperature equalization, support and the like on the observation window are realized.
When the special container for measurement is arranged, the container can be set into a split structure for the convenience of installation and replacement of the observation window, the cover body and the liquid containing body are provided with a barrel installation channel, which is equivalent to a pipe connection part, the barrel penetrates through the installation channel to form a sealing structure, and then the observation window at one end of the barrel is installed and fixed. In this case, since the observation window does not need to pass through the installation passage, the size requirement for the observation window can be reduced.
In the invention, the other end of the cylinder body is connected with the connecting pipe to realize the conduction of the observation pipeline and the fixation of the observation window, and the fixed connection of the cylinder body and the connecting pipe can adopt a side wall lap joint mode in consideration of the convenience and the sealing property of the connection between the cylinder body and the connecting pipe.
Specifically, a step surface is arranged on the inner wall of one end, fixed with the cylinder, of the connecting pipe, a lug is correspondingly arranged on the outer wall of the cylinder, and the lug on the outer wall of the cylinder is lapped on the step surface on the inner wall of the connecting pipe so as to realize the detachable fixed connection of the connecting pipe and the cylinder.
In consideration of the sealing requirement, the lap joint of the outer wall lug of the cylinder body and the step surface of the inner wall of the connecting pipe can be the sealing surface of the container, and in order to achieve a more reliable sealing effect, the lap joint of the outer wall lug of the cylinder body and the step surface of the inner wall of the connecting pipe is provided with a sealing ring.
The measuring unit is considered to be high in use condition temperature, the sealing ring is made of a graphite gasket and can resist high temperature, stress is easy to deform, and therefore sealing performance is good.
When the barrel and the connecting pipe are fixedly connected in a detachable mode, due to the fact that the temperature rises, fluctuation of the liquid level can occur, and therefore the barrel and the connecting pipe shake, and in order to achieve stable and reliable sealing connection of the barrel and the connecting pipe, an annular gland is arranged above a lug on the outer wall of the barrel.
In order to realize light path permeability, the upper part of the cylinder is also provided with high-temperature resistant infrared glass, so that on one hand, light rays pass through the cylinder to reach the surface of liquid metal, on the other hand, the high-temperature resistant infrared glass is used as a safety margin, and the test can be continuously completed when the lower high-temperature resistant infrared glass is slightly broken.
In order to further ensure the sealing performance, the high-temperature infrared glass on the stainless steel cylinder is fixed by high-temperature sealant.
Because the measured liquid metal has higher temperature and active chemical property, a protection system needs to be designed to prevent harm to personnel and equipment, high-temperature-resistant infrared glass at the top end of a cylinder (such as a stainless steel cylinder) of a measuring unit has a risk of fragmentation, and in order to prevent the liquid metal from leaking out in an accident, a sealing top cover is arranged at the top of a connecting pipe, and the sealing top cover is used as a final safety barrier to completely block a liquid metal leakage channel.
In one possible design, the seal cap includes: the two flanges are connected with the top of the vessel connecting pipe through the bolts and the red copper gaskets. The seal top cover is put into use when the high temperature infrared resistant glass sheets on the upper parts of the observation window and the stainless steel cylinder are simultaneously broken.
The measuring device is designed based on an energy method, and the basic principle is that an area in the center of the surface of a sample is selected, the radiation temperature of the area is measured by a radiation temperature detector such as a thermal infrared imager, the surface temperature of the area is measured by a thermocouple, and the emissivity can be calculated according to the radiation temperature value and the surface real temperature value.
In actual conditions, the infrared radiation received by the thermal infrared imager not only includes the infrared radiation of the surface of the object to be measured, but also includes the reflected radiation of the object to the environment, atmospheric radiation and thermal radiation inside the thermal infrared imager.
According to the basic rule of radiation heat transfer, and by combining various factors, the equivalent radiation intensity of the surface of a measured object is as follows:
L λ (T r )＝τ a ·ε·L bλ (T 0 )+τ a ·(1-α)·L bλ (T u )+ε a ·L bλ (T a )+L h formula one
In the formula:
T r -the radiation temperature measured for the thermal infrared imager,
T a -the temperature of the surface of the liquid metal,
T u -the temperature of the surroundings,
T a -the temperature of the atmosphere,
epsilon-the surface emissivity of the liquid metal,
ε a -an atmospheric emissivity, and-a thermal conductivity,
τ a -a transmission of light through the atmosphere,
the alpha-liquid metal surface absorption rate,
L h in a thermal infrared imagerThe intensity of the partial heat radiation is determined,
L λ- the intensity of the heat radiation inside the liquid metal,
L bλ -liquid metal surface thermal radiation intensity.
On the right side of equation (1), part 1 τ a ·ε·L bλ (T 0 ) Part 2 τ being the spectral radiant intensity of the liquid metal surface a ·(1-α)·L bλ (T u ) Part 3 ε for reflection of ambient spectral intensity by liquid metal a ·L bλ (T a ) Part 4L for intensity of atmospheric radiation h The thermal radiation intensity inside the thermal infrared imager. Typically, the thermal infrared imager is internally compensated for the thermal radiation of the instrument, so part 4 of the equation one may be omitted. When the temperature measurement distance is close, the transmissivity of the atmosphere is approximately 1, namely tau a 1 and e a 0. For an object with a temperature less than 2000K, the object can be regarded as a diffused gray body in the operating band of the thermal infrared imager, so that the surface absorption rate alpha is a constant independent of the wavelength. Meanwhile, based on kirchhoff's law, for a diffuse gray body, whether input radiation comes from a black body or not and whether the input radiation is in a thermal equilibrium condition or not, the absorptivity of the diffuse gray body is constantly equal to the emissivity at the same temperature, namely alpha-epsilon. So equation one can be converted into:
L λ (T r )＝ε·L bλ (T 0 )+(1-ε)·L bλ (T u ) Formula two
In the formula, T r -the radiation temperature measured for the thermal infrared imager,
T 0 -the temperature of the surface of the liquid metal,
T u -the temperature of the surroundings,
epsilon-the surface emissivity of the liquid metal,
L λ- the intensity of the heat radiation inside the liquid metal,
L bλ -liquid metal surface thermal radiation intensity.
The emissivity measured by the measuring device of the invention is normal emissivity, the liquid metal infrared radiation is irradiated to the thermal infrared imager vertically, and according to the Lanfibrate law and the Stefan-Boltzmann law, the radiation force of the liquid metal is equal to pi times of the directional radiation intensity, then the radiation force borne by the thermal infrared imager is:
in the formula: e λ -the radiation force of a thermal infrared imager,
A 0 -the visible area of the target corresponding to the minimum spatial opening angle of the thermal infrared imager,
l-distance of liquid metal to thermal infrared imager,
E bλ -spectral radiance of the liquid metal.
Since the thermal infrared imager usually works in a certain wavelength band, which is obtained from planck's law, the thermal infrared imager is subjected to the following radiation power:
in the formula: the radiation power of the P-infrared thermal imager,
lambda-the spectral wavelength of the thermal infrared imager,
A 0 -the visible area of the target corresponding to the minimum spatial opening angle of the thermal infrared imager,
A l -a thermal infrared imager entrance aperture,
l-distance of liquid metal to thermal infrared imager,
R λ -the spectral responsivity of the instrument.
Order to
In the formula, the spectrum wavelength of the lambda-infrared thermal imager,
T i -heating the liquid metal to a specified temperature,
R λ -the spectral responsivity of the instrument,
E bλ -the spectral radiation power of the liquid metal,
and is formed by Planck's law
Simplified equations one to four are:
f(T i )＝ε·f(T 0 )+(1-ε)·ε·f(T u ) Formula six
In the formula, T i -heating the liquid metal to a specified temperature,
T 0 -the surface temperature of the liquid metal,
epsilon-the surface emissivity of the liquid metal,
T u -ambient temperature.
The normal emissivity of the surface of the object thus obtained is expressed by:
in the formula, T r -the radiation temperature measured for the thermal infrared imager,
T 0 -the temperature of the surface of the liquid metal,
T u -ambient temperature.
According to Planck's law and spectral responsivity of detector, for convenient calculation it can make
The above equation can be converted into:
in the formula, T r -the radiation temperature measured for the thermal infrared imager,
T 0 -the temperature of the surface of the liquid metal,
T u -the temperature of the surroundings,
the n-approximation index is related to a response waveband of the infrared thermometer, the working waveband of the infrared thermal imager is 2-5 mu m, the value of n is 8.68, and the value of n is 4.09 for the infrared thermal imager of 8-14 mu m.
Because thermal infrared imagers of different models adopt different detectors and working bands, approximate index n values in emissivity calculation formulas are different, such as: the value of n is 8.68 for the thermal infrared imager with the working band of 2-5 mu m, and the value of n is 4.09 for the thermal infrared imager with the working band of 8-14 mu m. In practice, the value of n may be determined according to the corresponding band of the frequency of the selected thermal infrared imager model.
On the other hand, the invention discloses a method for measuring the surface emissivity of liquid metal, which comprises the following steps:
step 1: heating the liquid metal to a specified temperature, and displaying the temperature T by a measuring device for the surface temperature of the liquid metal at the bottom 0 ；
Step 2: after the temperature of the liquid metal is stable, measuring the temperature by using the thermal infrared imager 12 to obtain T r ；
And 3, step 3: the ambient temperature T u Atmospheric temperature T a Substituting the measured data in the step 2 and the data measured in the step 3 into the following formula eight, and calculating the surface radiation emissivity of the liquid metal at the temperature;
and 4, step 4: adjusting the heating temperature to another temperature, and repeating the step 1-3 to obtain the surface radiation emissivity of the liquid metal at different temperatures;
if the visible window is cracked and the high-temperature resistant glass tube is cracked, the processing steps are as follows:
step T1: under the condition that the bottom high-temperature-resistant infrared glass and the top high-temperature-resistant infrared glass are simultaneously broken, covering an upper cover plate of the observation window flange, compressing the red copper gasket, and screwing the compression bolt;
step T2: gradually reducing the temperature of the liquid metal, opening the cover plate after the device is cooled, and replacing the damaged part and the red copper gasket.
The emissivity measuring device provided by the invention can avoid the influence of aerosol on radiation absorption, and the high-temperature resistant glass tube at the measuring end of the measuring device is inserted into the liquid metal instead of being positioned above the liquid metal surface, so that the influence of liquid drops generated after the liquid metal is evaporated on the glass tube to the measuring accuracy when the emissivity of the liquid metal is measured can be avoided.
The sample container of the measuring device provided by the invention is filled with inert gas-argon gas as protective gas of liquid metal, so that the liquid metal can be prevented from contacting with air to generate chemical reaction.
According to the measuring device provided by the invention, the sealing top cover is arranged at the top of the measuring unit, two flanges of the top cover are connected with the top of the connecting pipe through bolts and the red copper gasket, so that a liquid metal leakage channel is completely blocked, high-temperature-resistant glass sheets at the top end of the stainless steel cylinder can be prevented from being cracked, and the liquid metal can be prevented from leaking out when an accident happens.
Example 1
The embodiment provides a device for measuring the surface emissivity of liquid metal and a method for measuring the surface emissivity of the liquid metal by using the device, and the specific details are as follows:
the measuring device comprises: the device comprises a liquid containing unit, a measuring unit and a protecting unit;
the liquid containing unit is a container for containing the liquid metal 1 to be measured, and the upper end of the container is provided with a connecting pipe 6.
The measuring unit takes a stainless steel cylinder 5 as a main body, the upper part of the cylinder is fixed on a connecting pipe of the sample container in a threaded connection 8 mode through an annular gland 9, and a graphite gasket 7 is arranged between the cylinder and the connecting pipe to serve as a buffer; the lower part of the cylinder is fixed at the bottom of the sample container through a stainless steel bracket 4. The top end of the cylinder is an observation end, a high-temperature resistant infrared glass sheet 11 with the light transmittance of more than 95% is used and is connected with the cylinder through high-temperature sealant 10, and an infrared thermal imager 12 is arranged above the observation end and used for measuring the radiation temperature value of the liquid metal; the bottom end of the cylinder is a measuring end, the high-temperature-resistant infrared glass observation window 2 is connected with the stainless steel cylinder in a soldering 3 mode and is inserted into liquid metal, so that the thermal infrared imager 12 above the observing end can smoothly receive sample radiation. The bottom of the cylinder is provided with a K-type sheathed thermocouple 17 for measuring the true temperature of the liquid metal surface.
A protection unit: the sample container is filled with inert gas-argon as protective gas 18 of liquid metal to prevent the liquid metal from contacting with air to generate chemical reaction; a sealing top cover is arranged above the observation end and at the position of the joint at the top of the vessel connecting pipe, and two flanges 13 of the top cover are connected with the top of the connecting pipe 6 through bolts 16 and a red copper gasket 14, so that a liquid metal leakage channel is completely blocked.
The method for measuring the surface emissivity of the liquid metal by using the measuring device comprises the following steps:
step 1: unscrewing the compression bolts 16 and opening the upper cover plate 15 of the observation window flange;
step 2: heating the liquid metal 1 to a specified temperature, and displaying the temperature T by a bottom liquid metal surface temperature measuring device 0 ；
And step 3: after the temperature of the liquid metal is stable, measuring the temperature by using the thermal infrared imager 12 to obtain T r ；
And 4, step 4: substituting the measured data into the following formula eight, and calculating the surface radiation emissivity of the liquid metal at the temperature;
and 5: adjusting the heating temperature to another temperature, and repeating the step 2-4 to obtain the surface radiation emissivity of the liquid metal at different temperatures;
if the visible window is cracked and the high-temperature resistant glass tube is cracked, the processing steps are as follows:
step T1: under the condition that the bottom-end high-temperature-resistant infrared glass observation window 2 and the top-end visual window high-temperature-resistant infrared glass sheet 11 are simultaneously broken, the upper cover plate 15 of the flange 13 is covered, the red copper gasket 14 is tightly pressed, and the compression bolt 16 is tightly screwed;
step T2: the liquid metal temperature is gradually reduced, and after the device is cooled, the cover plate 15 is opened to replace the damaged parts and the red copper gasket 14.
Example 2
The embodiment provides a method for measuring the surface emissivity of liquid metal, and the method for measuring the surface emissivity of sodium liquid metal by using the measuring device provided in embodiment 1 comprises the following specific steps:
step 1: unscrewing the compression bolts 16 and opening the upper cover plate 15 of the observation window flange;
and 2, step: the liquid metal 1 is heated to 300 ℃, and the thermocouple obtains the temperature T 0 ＝ 300.00℃；
And step 3: after the temperature of the liquid metal sodium is stable, measuring the temperature by using the thermal infrared imager 12 to obtain T r ＝47.89℃；
And 4, step 4: the ambient temperature T u Substituting the data measured in the step 2 and the step 3 at 20.00 ℃ into the following formula (converting the temperature into open type), taking n as 4.09, and calculating the surface radiation emissivity epsilon of the liquid metal at the temperature as 0.031;
and 5: and (3) adjusting the heating temperature to 400 ℃, and repeating the steps 2-4 to obtain the liquid metal sodium surface radiation emissivity epsilon of 0.035 at the temperature of 400 ℃.
Step 6: and (3) adjusting the heating temperature to 500 ℃, and repeating the step 2-4 to obtain the liquid metal sodium surface radiation emissivity epsilon of 500 ℃, which is 0.037.
The surface emissivity of the liquid metal sodium at different temperatures obtained in the embodiment 1 provides effective data for the calculation of the radiation heat exchange amount of the liquid metal sodium in the later period, and provides data guarantee for the radiation heat transfer calculation and analysis of a liquid metal sodium device, thereby being beneficial to the safety production of reactors.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (10)
1. A measuring device for the surface emissivity of liquid metal, the measuring device comprising: the device comprises a liquid containing unit, a measuring unit and a protecting unit;
the liquid containing unit is a container for containing liquid metal;
the measuring unit comprises an observation window immersed in the liquid metal and a radiation temperature detector communicated with an optical path of the observation window, and the radiation temperature detector is used for measuring a radiation temperature value of the liquid metal;
the protection unit is used for providing inert atmosphere protection for the container.
2. The measurement device of claim 1, wherein the measurement unit further comprises a liquid metal surface temperature measurement device that calculates emissivity based on the formula:
in the formula, T r -the radiation temperature measured for the thermal infrared imager,
T 0 -the temperature of the surface of the liquid metal,
T u -the temperature of the surroundings,
n-approximate index.
3. The measurement device of claim 2, wherein the measurement unit further comprises a bracket disposed outside the viewing window.
4. A measuring device according to claim 3, characterized in that the liquid metal surface temperature measuring device is mounted on a support.
5. The measuring device according to claim 1, wherein the liquid containing unit comprises a container body and a connection pipe connected with the container body, the connection pipe forming an optical path between the observation window and the radiation temperature detector; the container body is in a sealed state, and the container is protected by inert atmosphere provided by the protection unit.
6. The measuring device according to claim 5, wherein the measuring unit further comprises a cylinder, the observation window is fixed at one end of the cylinder, the cylinder penetrates through the adapter tube, and an optical path between the observation window and the radiation temperature detector is formed inside the cylinder.
7. The measuring device of claim 6, wherein the observation window is in sealed connection with the cylinder and the cylinder is in sealed connection with the adapter tube.
8. The measuring device according to claims 1 to 7, wherein the observation window of the measuring unit is made of infrared glass with a light transmittance of 95% or more.
9. The measuring device according to claim 2, wherein the infrared glass is high-temperature-resistant infrared glass and has a thickness of 7-11 mm.
10. A method for measuring the surface emissivity of a liquid metal, wherein the measuring device of any one of claims 1 to 9 is used, and the method comprises the following steps:
step 1: heating the liquid metal to a specified temperature;
step 2: after the temperature of the liquid metal is stable, measuring the temperature by using a thermal infrared imager;
and step 3: and (3) substituting the measurement data into the following formula to calculate the surface radiation emissivity of the liquid metal at the temperature:
in the formula, T r -the radiation temperature measured for the thermal infrared imager,
T 0 -the temperature of the surface of the liquid metal,
T u -the temperature of the surroundings,
n-approximation index;
and 4, step 4: and (4) adjusting the heating temperature to another temperature, and repeating the step (1) to the step (3) to obtain the surface radiation emissivity of the liquid metal at different temperatures.
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