CN115128119B - 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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- CN115128119B CN115128119B CN202111310172.5A CN202111310172A CN115128119B CN 115128119 B CN115128119 B CN 115128119B CN 202111310172 A CN202111310172 A CN 202111310172A CN 115128119 B CN115128119 B CN 115128119B
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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 thermal engineering hydraulics, and solves the problem that the surface emissivity of the liquid metal cannot be determined in radiation heat exchange calculation in the prior art. The measuring device includes: 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 method realizes the direct measurement of the temperature of the high-temperature liquid metal and the indirect measurement of the emissivity by using a visual temperature measurement method.
Description
Technical Field
The invention relates to the technical field of reactor thermal engineering hydraulics, in particular to a device and a method for measuring the surface emissivity of liquid metal.
Background
According to definition of heat transfer theory, emissivity is a physical parameter representing radiation heat transfer capacity of an object, is only related to materials, structures, roughness and the like of the object, is one of basic parameters of thermophysical properties of the material, and refers to the ratio of radiation quantity of the object at a specified temperature T to blackbody radiation quantity at the same temperature.
The current method for measuring the surface emissivity mainly comprises the following steps: calorimetric, reflectometric, multi-wavelength and energetic methods. Conventional measurement methods are mostly directed to solids.
As a novel material, the liquid metal has the advantages of high heat conductivity, high boiling point, large specific heat capacity and the like, and is widely applied to the fields of nuclear engineering, computer chip cooling, electronic printing, biomedicine and the like at present. In the above industrial fields, there are wide design and use demands for liquid metal radiation heat transfer calculation, and in order to calculate the radiation heat transfer amount, it is necessary to obtain the surface emissivity of the liquid metal, and there are many difficulties in measuring the surface emissivity of the high-temperature liquid metal.
Disclosure of Invention
In view of the above analysis, the present invention provides a device and a method for measuring the surface emissivity of a liquid metal, which at least solve one of the following technical problems: (1) The measured samples have very high temperature (generally above 300 ℃) and are difficult to measure for a long time; (2) Droplets generated after evaporation of the liquid metal may condense on the surface of the sample observation window, thereby affecting the measurement accuracy; (3) The measured object is in a liquid state, has good fluidity, and the conventional sample measurement is often difficult to solve the problems of solid, heating, temperature measurement and the like.
In one aspect, the present invention provides a device for measuring the surface emissivity of a 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 further comprises a liquid metal surface temperature measuring device, and the emissivity is calculated based on the following formula:
wherein T is r The radiation temperature measured by the thermal infrared imager,
T 0 -a surface temperature of the liquid metal,
T u -an ambient temperature at which the temperature of the air,
n-approximation index.
Further, the measuring unit further comprises a bracket arranged outside the observation window.
Further, the liquid metal surface temperature measuring device is mounted on a 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 sealing state, and the inside of the container is protected by adopting inert atmosphere provided by a protection unit.
Further, the measuring unit further 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.
Further, the observation window is in sealing connection with the cylinder body and the cylinder body is in sealing connection with the connecting pipe.
Further, the observation window of the measuring unit adopts infrared glass with the light transmittance of more than 95 percent.
Further, the infrared glass is high-temperature resistant infrared glass, and the thickness is 7-11 mm.
The invention also provides a method for measuring the surface emissivity of the liquid metal, which adopts the measuring device and 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;
step 3: substituting the measured data into the following formula, and calculating the emissivity of the liquid metal surface radiation at the temperature:
wherein T is r The radiation temperature measured by the thermal infrared imager,
T 0 -a surface temperature of the liquid metal,
T u -an ambient temperature at which the temperature of the air,
n-approximation index;
step 4: and (3) adjusting the heating temperature to another temperature, and repeating the steps 1-3 to obtain the liquid metal surface emissivity of different temperatures.
Compared with the prior art, the invention has at least one of the following beneficial effects:
1. 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 of liquid drops generated after the evaporation of the liquid metal on the measuring accuracy and the influence of aerosol on the radiation absorption on the measuring accuracy are avoided when the liquid metal emissivity is measured.
2. The measuring device is provided with the liquid containing unit, the measuring unit and the protecting unit, the top of the measuring unit is provided with the visual window which can measure the temperature and the radiation emissivity of the liquid metal in real time, and the measuring device is also provided with the safety protecting device which can measure the surface radiation emissivity of the liquid metal at different temperatures and can also avoid leakage of the liquid metal and the protecting gas.
3. The sample container of the measuring device provided by the invention is filled with inert gas-argon as the protective gas of the liquid metal, so that the liquid metal can be prevented from being contacted 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, and the two flanges of the top cover are connected with the top of the connecting pipe through the bolts and the red copper gasket, so that the leakage channel of the liquid metal is completely blocked, the breakage of the high-temperature-resistant glass sheet at the top end of the stainless steel cylinder can be prevented, and the leakage of the liquid metal during accidents can be prevented.
In the invention, the technical schemes can be mutually combined 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 practice of the invention. The objectives and other advantages of the invention may 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, like reference numerals being used to refer to like parts throughout the several views.
FIG. 1 is a schematic diagram of a measuring device for the surface emissivity of a liquid metal;
fig. 2 is a schematic diagram of the positional relationship between a stainless steel bracket and an observation window when the stainless steel bracket of the liquid metal surface emissivity measuring device provided by the invention is of a sleeve structure.
Reference numerals:
1-liquid metal to be detected; 2-a high-temperature resistant infrared glass observation window; 3-soldering; 4-stainless steel brackets; 41-a stent sleeve; 42-bracket legs; 5-stainless steel cylinder; 6-connecting pipe; 7-graphite gaskets; 8-threaded connection; 9-an annular gland; 10-high-temperature sealant; 11-a high temperature resistant infrared glass sheet; 12-a thermal infrared imager; 13-flanges; 14-red copper gasket; 15-cover plate; 16-bolts; 17-thermocouple temperature measuring points; 18-inert shielding gas.
Detailed Description
Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and together with the description serve to explain the principles of the invention, and are not intended to limit the scope of the invention.
The current method for measuring the surface emissivity mainly comprises the following steps: calorimetric, reflectometric, multi-wavelength and energetic methods. Among these, calorimetry and energy methods are methods commonly used in the industry to measure emissivity. The principle of calorimetry is: according to the heat conduction theory, the measured object and the surrounding environment form a heat exchange system, the temperature of the relevant point of the measured object is measured, and the emissivity of the object is obtained by utilizing a heat conduction equation. The calorimeter has the advantages of simple system, high measuring speed, wide temperature measuring range, higher accuracy and the like, but when the method is used, the uneven temperature of the surface of the 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: and under the same measuring 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. As a novel material, the liquid metal has the advantages of high heat conductivity, high boiling point, large specific heat capacity and the like, and is widely applied to the fields of nuclear engineering, computer chip cooling, electronic printing, biomedicine and the like at present. In the above industrial fields, there are wide design and use demands for liquid metal radiation heat transfer calculation, and in order to calculate the radiation heat transfer amount, it is necessary to obtain the surface emissivity of the liquid metal, and there are many difficulties in measuring the surface emissivity of the high-temperature liquid metal. It is found in the research that the measurement of the surface emissivity of the high-temperature liquid metal mainly has the following difficulties: firstly, the measured samples have very high temperature (generally above 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 affected; thirdly, the measured object is in a liquid state, has good fluidity, and conventional sample measurement is difficult to solid, heat, temperature measurement and the like.
Based on the above-mentioned problems, in one aspect, the present invention discloses a device for measuring the surface emissivity of a 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 all have very high temperature, condensation of small liquid drops generated after liquid metal evaporation on the surface of an observation window can influence 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 and mixed with the protective gas to form aerosol at high temperature, temperature measurement is directly influenced, and therefore emissivity measurement is inaccurate. That is, the measuring end of the measuring device is inserted into the liquid metal, not above the liquid metal level, so that the influence of liquid drops generated after the evaporation of the liquid metal on the measuring accuracy and the influence of the absorption of aerosol on the radiation on the measuring accuracy are avoided when the emissivity of the liquid metal is measured.
Considering that the radiation temperature detected by the thermal infrared imager is ensured to be as accurate as possible, the observation window adopts infrared glass with the light transmittance of more than 95 percent, and the specific adoption of the high-temperature-resistant infrared glass observation window can meet the parameter requirement.
More specifically, the thickness of the high temperature resistant infrared glass observation window is 7-11 mm, and the glass strength is insufficient when the thickness is too low, and the transmittance is affected when the thickness is higher than the thickness.
In order to prevent the liquid metal from contacting with air to generate 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 method that the observation window is immersed in liquid metal, in order to form an observation light path, the measuring unit also comprises a cylinder body, and the liquid containing unit comprises a container body and a connecting pipe connected with the container body. The observation window is fixed in the one end of barrel, and the barrel of the fixed observation window of measuring unit passes through the takeover and gets into in the container, and the other end and the takeover of barrel are connected, and the inside optics passageway that forms between observation window and the radiation temperature detector of barrel.
In order to ensure that the container is in a sealed state, the observation window is in sealed connection with the cylinder body and the cylinder body is in sealed connection with the connecting pipe.
Specifically, the observation window is fixedly connected with one end of the cylinder body through soldering. In consideration of the later replacement of the observation window, detachable connection, such as a buckle structure, can be adopted between the observation window and the cylinder.
In order to facilitate 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 connection structure between observation window and the barrel is in high temperature operating mode for a long time, in order to prevent not hard up, the measuring unit still includes the support of setting in the observation window outside.
In a preferred scheme, the support is of a sleeve structure, the uniformity of the temperature of the observation window can be improved by adopting the sleeve structure, and the observation window can be further fixed and supported, so that the observation window is protected. Specifically, when the stainless steel bracket is of a sleeve structure, the stainless steel bracket comprises a bracket sleeve and bracket legs, 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 actual temperature of the liquid metal surface, which may be mounted on the sleeve structure.
In consideration of the use requirement of liquid metal surface emissivity measurement, a special measurement container can be arranged, when the special measurement container is adopted, the bracket can be directly arranged at the bottom of the container and at the position opposite to the container connecting pipe, and the observation window is directly matched with the bracket during assembly, so that the effects of protecting, homogenizing temperature, supporting and the like of the observation window are realized.
When setting up the special container of measurement, in order to be convenient for the installation and the change of observation window, can set up the container into split structure, including lid and flourishing liquid body, be provided with barrel installation passageway on the lid, be equivalent to the takeover part, the barrel passes and forms seal structure after the installation passageway, carries out the installation and the fixed of the observation window of barrel one end again. At this time, since the observation window does not need to pass through the installation channel, the size requirement on the observation window can be reduced.
In the invention, the other end of the cylinder is connected with the connecting pipe so as to realize the conduction of the observation pipeline and the fixation of the observation window, and the fixed connection of the cylinder and the connecting pipe can adopt a mode of overlapping the side wall in consideration of the convenience and the tightness of the connection between the cylinder and the connecting pipe.
Specifically, the inner wall of one end of the connecting pipe, which is fixed with the cylinder, is provided with a step surface, the outer wall of the cylinder is correspondingly provided with a lug, and the outer wall lug of the cylinder is lapped on the step surface of 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 step surface of the outer wall lug of the cylinder and the inner wall of the connecting pipe can be a sealing surface of the container, and in order to achieve a more reliable sealing effect, a sealing ring is arranged at the lap joint of the step surface of the outer wall lug of the cylinder and the inner wall of the connecting pipe.
Considering that the working condition of the measuring unit is high in temperature, the sealing ring adopts a graphite gasket, and the measuring unit can resist high temperature and is easy to deform under stress, so that the sealing performance is good.
When the barrel body and the connecting pipe are in detachable and fixed connection, the fluctuation of the liquid level can occur due to the temperature rise, so that the barrel body and the connecting pipe are caused to shake, and an annular gland is arranged above the outer wall lug of the barrel body in order to realize stable and reliable sealing connection of the barrel body and the connecting pipe.
In order to realize the light path permeability, the upper part of the cylinder is also provided with high-temperature-resistant infrared glass, so that on one hand, light reaches the surface of liquid metal through the cylinder, and on the other hand, as a safety margin, the test can be continuously completed when the lower high-temperature-resistant infrared glass is slightly broken.
In order to further ensure the tightness, the high-temperature-resistant infrared glass on the stainless steel cylinder is fixed by high-temperature-resistant sealant.
Because the measured liquid metal has higher temperature and active chemical property, a protection system needs to be designed to prevent damage to personnel and equipment, and the high-temperature-resistant infrared glass at the top end of the cylinder body (such as a stainless steel cylinder) of the measuring unit is at risk of fragmentation.
In one possible design, the seal cap comprises: the flange, the red copper gasket and the sealing bolt are connected with the top of the container connecting pipe through the bolts and the red copper gasket. The seal top cover is put into use when the observation window and the high-temperature-resistant infrared glass sheet at the upper part of the stainless steel cylinder are broken at the same time.
The measuring device is designed based on an energy method, and the basic principle is that a region at the center of the surface of a sample is selected, the radiation temperature is measured by a radiation temperature detector such as a thermal infrared imager, the surface temperature is measured by a thermocouple, and the emissivity can be calculated by the radiation temperature value and the surface real temperature value.
In the actual working condition, the infrared radiation received by the thermal infrared imager not only comprises the infrared radiation of the surface of the measured object, but also comprises the reflected radiation of the object to the environment, the atmospheric radiation and the heat radiation in the thermal imager.
According to the basic law of radiation heat transfer, various factors are integrated, and the equivalent radiation intensity of the surface of the 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 equation one
Wherein:
T r the radiation temperature measured by the thermal infrared imager,
T a -a surface temperature of the liquid metal,
T u -an ambient temperature at which the temperature of the air,
T a the temperature of the atmosphere is chosen to be,
the surface emissivity of the epsilon-liquid metal,
ε a the emissivity of the atmosphere is chosen to be,
τ a the transmittance of the atmosphere is chosen to be high,
the absorption rate of the alpha-liquid metal surface,
L h the intensity of the thermal radiation inside the thermal infrared imager,
L λ- the intensity of the heat radiation inside the liquid metal,
L bλ -intensity of heat radiation of the liquid metal surface.
On the right side of equation (1), part 1, τ a ·ε·L bλ (T 0 ) For the spectral radiation intensity of the liquid metal surface, part 2 τ a ·(1-α)·L bλ (T u ) For the liquid metal reflection ambient spectral intensity, part 3 ε a ·L bλ (T a ) For atmospheric radiation intensity, part 4L h The infrared thermal imager is used for measuring the internal heat radiation intensity of the infrared thermal imager. The thermal radiation of the instrument is compensated for in the thermal infrared imager, so the 4 th part of the formula I can be omitted. When the temperature measurement distance is relatively close, the transmittance of the atmosphere is approximately 1, namely tau a =1, and ε a =0. For objects with a temperature of less than 2000K, the infrared heat is applied toThe surface absorption α is a constant independent of wavelength, which can be considered as a diffuse gray body in the operating band of the imager. Meanwhile, based on kirchhoff's law, for a diffuse gray body, whether the input radiation comes from a black body or not, whether or not in a heat balance condition, the absorptivity is constantly equal to the emissivity at the same temperature, i.e., α=ε. So equation one can be converted into:
L λ (T r )＝ε·L bλ (T 0 )+(1-ε)·L bλ (T u ) Formula II
Wherein T is r The radiation temperature measured by the thermal infrared imager,
T 0 -a surface temperature of the liquid metal,
T u -an ambient temperature at which the temperature of the air,
the surface emissivity of the epsilon-liquid metal,
L λ- the intensity of the heat radiation inside the liquid metal,
L bλ -intensity of heat radiation of the liquid metal surface.
The emissivity measured by the measuring device is normal emissivity, the infrared radiation of the measured liquid metal vertically irradiates the thermal infrared imager, and as known from the law of the blue fibrate and the law of the Stefan-Boltzmann, the radiation force of the liquid metal is equal to pi times of the directional radiation intensity, and the radiation force born by the thermal infrared imager is as follows:
wherein: e (E) λ The radiation power of the thermal infrared imager,
A 0 the visible area of the target corresponding to the thermal infrared imager minimum spatial opening angle,
l-distance of liquid metal from thermal infrared imager,
E bλ -spectral radiant forces of the liquid metal.
Since the thermal infrared imager usually works at a certain band, the radiation power of the thermal infrared imager is as follows, which is obtained by planck's law:
wherein: the radiation power of the P-thermal infrared imager,
the spectral wavelength of the lambda-thermal infrared imager,
A 0 the visible area of the target corresponding to the thermal infrared imager minimum spatial opening angle,
A l a thermal infrared imager entrance aperture,
l-distance of liquid metal from thermal infrared imager,
R λ -the spectral responsivity of the instrument.
Order the
Wherein, the spectrum wavelength of the lambda-thermal infrared imager,
T i heating the liquid metal to a specified temperature,
R λ the spectral responsivity of the instrument,
E bλ the spectral radiant forces of the liquid metal,
and by Planck's lawThe formulas one to four can be simplified as:
f(T i )＝ε·f(T 0 )+(1-ε)·ε·f(T u ) Formula six
Wherein T is i Heating the liquid metal to a specified temperature,
T 0 -a surface temperature of the liquid metal,
the surface emissivity of the epsilon-liquid metal,
T u -ambient temperature.
The normal emissivity expression of the surface of the object can be obtained by the method:
wherein T is r The radiation temperature measured by the thermal infrared imager,
T 0 -a surface temperature of the liquid metal,
T u -ambient temperature.
According to Planck's law and spectral responsivity of the detector, for convenient calculation, the method can makeThe above can be converted into:
wherein T is r The radiation temperature measured by the thermal infrared imager,
T 0 -a surface temperature of the liquid metal,
T u -an ambient temperature at which the temperature of the air,
the n-approximation index is related to the response wave band of the infrared thermometer, the working wave band of the infrared thermal imager is 2-5 mu m, the value is n=8.68, and the value is n=4.09 for the infrared thermal imager of 8-14 mu m.
Because the thermal infrared imagers of different models adopt different detectors and working wave bands, the approximate index n value in the emissivity calculation formula is different, for example: for a thermal infrared imager with an operating band of 2-5 μm, the value is n=8.68, and for a thermal infrared imager with an operating band of 8-14 μm, the value is n=4.09. In practice, the value of n may be determined according to the frequency corresponding band of the thermal infrared imager model selected.
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 a temperature T by a bottom liquid metal surface temperature measuring device 0 ；
Step 2: after the temperature of the liquid metal is stable, the thermal infrared imager 12 is used for measuring the temperature to obtain T r ；
Step 3: ambient temperature T u Atmospheric temperature T a Substituting the measured data obtained in the step 2 and the measured data obtained in the step 3 into the following formula eight, and calculating the surface emissivity of the liquid metal at the temperature;
step 4: adjusting the heating temperature to another temperature, and repeating the steps 1-3 to obtain the liquid metal surface emissivity of different temperatures;
if the visible window is broken and the high-temperature-resistant glass tube is broken, 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 broken at the same time, an upper cover plate of the flange of the observation window is covered, a red copper gasket is pressed tightly, and a pressing bolt is screwed tightly;
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.
According to the emissivity measuring device provided by the invention, the influence of aerosol on radiation absorption can be avoided, and the influence of liquid drops generated after liquid metal evaporation on the measuring accuracy can be avoided by inserting the high-temperature-resistant glass tube at the measuring end of the measuring device into the liquid metal instead of being positioned above the liquid level of the liquid metal.
The sample container of the measuring device provided by the invention is filled with inert gas-argon as the protective gas of the liquid metal, so that the liquid metal can be prevented from being contacted 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, and the two flanges of the top cover are connected with the top of the connecting pipe through the bolts and the red copper gasket, so that the leakage channel of the liquid metal is completely blocked, the breakage of the high-temperature-resistant glass sheet at the top end of the stainless steel cylinder can be prevented, and the leakage of the liquid metal during accidents can be prevented.
Example 1
The embodiment provides a device for measuring the surface emissivity of liquid metal and method steps for measuring the surface emissivity of the liquid metal by adopting the device, and the specific details are as follows:
the measuring device includes: 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 1 to be measured, and a connecting pipe 6 is arranged at the upper end of the container.
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 be used as 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 for being connected with a high-temperature sealant 10 filled between the cylinders, and a thermal infrared imager 12 is arranged above the observation end and used for measuring the radiation temperature value of liquid metal; the bottom end of the cylinder is a measuring end, and 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 observation end can successfully receive sample radiation. The bottom of the cylinder is provided with a K-type armoured thermocouple 17 for measuring the true temperature of the liquid metal surface.
Protection unit: the sample container is filled with inert gas-argon gas as a 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 joint position of the top of the container connecting pipe, and two flanges 13 of the top cover are connected with the top of the connecting pipe 6 through bolts 16 and red copper gaskets 14 to completely block the liquid metal leakage channel.
The method for measuring the surface emissivity of the liquid metal by using the measuring device comprises the following steps of:
step 1: unscrewing the compression bolt 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 a temperature T by a bottom liquid metal surface temperature measuring device 0 ；
Step 3: after the temperature of the liquid metal is stable, the thermal infrared imager 12 is used for measuring the temperature to obtain T r ；
Step 4: substituting the measured data into the following formula eight, and calculating the emissivity of the liquid metal surface radiation at the temperature;
step 5: adjusting the heating temperature to another temperature, and repeating the steps 2-4 to obtain the liquid metal surface emissivity of different temperatures;
if the visible window is broken and the high-temperature-resistant glass tube is broken, the processing steps are as follows:
step T1: under the condition that the high-temperature-resistant infrared glass observation window 2 at the bottom and the high-temperature-resistant infrared glass sheet 11 at the top are broken at the same time, the upper cover plate 15 of the flange 13 is covered, the red copper gasket 14 is pressed, and the pressing bolt 16 is screwed;
step T2: gradually reducing the temperature of the liquid metal, opening the cover plate 15 after the device is cooled, and replacing the damaged parts and the red copper gasket 14.
Example 2
The embodiment provides a method for measuring the surface emissivity of liquid metal, which adopts the measuring device provided in the embodiment 1 to measure the surface emissivity of sodium liquid metal, and specifically comprises the following steps:
step 1: unscrewing the compression bolt 16 and opening the upper cover plate 15 of the observation window flange;
step 2: heating the liquid metal 1 to 300 ℃ and obtaining a temperature T by a thermocouple 0 ＝ 300.00℃；
Step 3: after the temperature of the liquid metal sodium is stable, the temperature is measured by using the thermal infrared imager 12 to obtain T r ＝47.89℃；
Step 4: ambient temperature T u The data measured in step 2 and step 3 at 20.00 ℃ are substituted into the following formula (converting the degrees celsius into open degrees), n is 4.09, and the emissivity epsilon=0.031 of the liquid metal surface at the temperature is calculated;
step 5: and (3) regulating the heating temperature to 400 ℃, and repeating the steps 2-4 to obtain the liquid metal sodium with the temperature of 400 ℃ and the surface emissivity epsilon=0.035.
Step 6: and (3) regulating the heating temperature to 500 ℃, and repeating the steps 2-4 to obtain the liquid metal sodium with the temperature of 500 ℃ and the surface emissivity epsilon=0.037.
The surface emissivity of the liquid metal sodium obtained in the embodiment 1 at different temperatures provides effective data for the calculation of the radiation heat exchange quantity of the liquid metal sodium in the later period, and further provides data guarantee for the radiation heat transfer calculation analysis of the liquid metal sodium device, thereby being beneficial to the safe production of the reactor.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.
Claims (5)
1. A device for measuring the surface emissivity of a high-temperature sodium liquid metal, which is characterized by 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, a radiation temperature detector communicated with an optical path of the observation window, a liquid metal surface temperature measuring device and a bracket arranged outside the observation window, wherein the radiation temperature detector is used for measuring a liquid metal radiation temperature value, and the liquid metal surface temperature measuring device is used for measuring a liquid metal surface real temperature;
the protection unit is used for providing inert atmosphere protection for the container, and liquid metal evaporates and protective gas forms aerosol at high temperature;
the bracket is of a sleeve structure, and the liquid metal surface temperature measuring device is arranged on the bracket and is positioned below an observation window immersed in liquid metal;
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 inside of the container is protected by adopting inert atmosphere provided by a protection unit;
the measuring unit further comprises a cylinder body, the observation window is fixed at one end of the cylinder body, the cylinder body penetrates through the connecting pipe, an optical passage between the observation window and the radiation temperature detector is formed in the cylinder body, and the observation window is in sealing connection with the cylinder body and the connecting pipe;
the inner wall of one end of the connecting pipe, which is fixed with the cylinder, is provided with a step surface, the outer wall of the cylinder is correspondingly provided with a lug, and the lug of the outer wall of the cylinder is lapped on the step surface of the inner wall of the connecting pipe;
and the upper part of the cylinder body is provided with high-temperature-resistant infrared glass.
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 following formula:
，
in the method, in the process of the invention,for the radiation temperature measured by the radiation temperature detector,
-a surface temperature of the liquid metal,
-an ambient temperature at which the temperature of the air,
n-an approximation index.
3. The measurement device according to claim 1 or claim 2, wherein the observation window of the measurement unit is made of infrared glass having a light transmittance of 95% or more.
4. The measuring device according to claim 3, wherein the infrared glass is high-temperature-resistant infrared glass, and the thickness is 7-11 mm.
5. A method for measuring the surface emissivity of a liquid metal, characterized in that a measuring device according to any one of claims 1-4 is used, said measuring method comprising the steps of:
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;
step 3: substituting the measured data into the following formula, and calculating the emissivity of the liquid metal surface radiation at the temperature:
，
in the method, in the process of the invention,-the radiation temperature measured by the radiation temperature detector
-a surface temperature of the liquid metal,
-an ambient temperature at which the temperature of the air,
n-an approximation index;
step 4: and (3) adjusting the heating temperature to another temperature, and repeating the steps 1-3 to obtain the liquid metal surface emissivity of different temperatures.
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