CN203894183U - Hemispherical emittance tester based on balanced-state heat meter measurement method - Google Patents

Abstract

A steady-state calorimeter hemispherical emissivity tester, comprising a vacuum chamber, a sample heating component, a vacuum device, a constant temperature cooling device, and a data measurement and processing device; the vacuum chamber includes a vacuum cover and is fixed on the inner wall of the vacuum cover The heat sink; the sample heating component is set in the vacuum chamber to heat the sample, including the main heater; the vacuum device is connected with the vacuum test space of the vacuum chamber; the constant temperature cooling device is connected with the cooling medium channel of the vacuum chamber; the data measurement The temperature of the sample, the temperature of the heat sink, the vacuum degree in the vacuum chamber and the power of the main heater are collected with the processing device, and the hemispherical emissivity of the sample is calculated. It overcomes the strict requirements of the test process on the thermal conductivity and specific heat capacity of the material. It has high test accuracy and a wide test temperature range. It can test the hemispherical emissivity of materials under different temperature conditions, especially at low temperatures. Using the test results of the test device, the hemispherical emissivity of the material can be conveniently calculated, and the test and calculation are relatively simple.

Description

A steady-state calorimeter method hemispherical emissivity tester

technical field

The utility model relates to the field of hemispherical emissivity testers, in particular to a hemispherical emissivity tester with a steady-state calorimeter method.

Background technique

Hemispherical emissivity is an important physical performance parameter of solid materials, which reflects the radiation ability of materials relative to black bodies at specific temperatures. The test methods for material hemispherical emissivity include card meter method and optical method. The calorimeter method includes the transient calorimeter method and the steady-state calorimeter method (steady-state calorimeter method). The transient card meter method can continuously measure the emissivity of the sample under different temperature conditions in a short period of time, but it requires good thermal conductivity of the sample during the test to ensure that there is no temperature gradient inside the sample during the cooling process. Therefore, it is difficult to use it to test the hemispherical emissivity of low thermal conductivity materials. In addition, the specific heat capacity of materials at different temperatures needs to be obtained by using the transient calorimetric method. However, the thermodynamic parameters of many new functional materials and thermal control materials are very scarce, which also limits the application of the transient calorimetric method.

Utility model content

In order to meet the measurement requirements of heat radiation materials, especially heat insulation coatings, under different temperature conditions, especially at low temperatures, the utility model rationally designs a hemispherical emissivity tester based on the steady-state calorimeter method.

In order to achieve the above object, the utility model adopts the following technical solutions: a steady-state calorimeter method hemispherical emissivity tester, including a vacuum chamber, a sample heating component, a vacuum device, a constant temperature cooling device, and a data measurement and processing device;

The vacuum chamber includes a vacuum cover and a semi-enclosed heat sink fixed on the inner wall of the vacuum cover; the inner side of the heat sink constitutes a vacuum test space, and a line is left between the outer side and the inner wall of the vacuum cover. A cooling medium channel; the cooling medium channel is provided with a cooling medium inlet and a cooling medium outlet;

The sample heating assembly is arranged in the vacuum test space of the vacuum chamber to heat the sample, including a main heater; the main heater forms a series circuit with a standard resistor and a DC power supply;

The vacuum pumping device communicates with the vacuum test space of the vacuum chamber through a pipeline;

The constant temperature cooling device communicates with the cooling medium inlet and the cooling medium outlet of the cooling medium passage through pipes respectively;

The data measurement and processing device collects the temperature of the sample, the temperature of the heat sink, the vacuum degree in the vacuum chamber and the power of the main heater; when the data measurement and processing device detects that the pressure in the vacuum chamber reaches below 1.0X10 ^-3 Pa, and the sample When the temperature reaches the set temperature, the data measuring and processing device calculates the hemispherical emissivity of the sample according to the sample temperature, the heat sink temperature, the power of the main heater and the radiation surface area of the sample.

Compared with the prior art, a steady-state calorimeter method hemispherical emissivity tester of the present invention includes a vacuum chamber, a constant temperature cooling device, a sample heating assembly, a vacuum device, and a data measurement and processing device. The calorimeter method overcomes the strict requirements on the thermal conductivity and specific heat capacity of the material during the test process. It has high test accuracy, wide test temperature range, and is widely used. It can test the hemispherical emissivity of materials under different temperature conditions, especially at low temperatures. . Using the test results of the test device, the hemispherical emissivity of the material can be conveniently calculated, and the test and calculation are relatively simple.

Further, the data measurement and processing device includes a first temperature measurement unit, a second temperature measurement unit, a third temperature measurement unit, a fourth temperature measurement unit, a first voltmeter, a second voltmeter, and a processing unit; A temperature measurement unit is set on the sample to measure the temperature of the sample; the second temperature measurement unit is set on the heat sink; the third temperature measurement unit is set at the inlet of the cooling medium; the fourth temperature measurement unit is set at the cooling medium outlet; the first voltmeter is connected in parallel with the main heater to measure the voltage of the main heater; the second voltmeter is connected in parallel with the standard resistance to measure the voltage of the standard resistance; the processing unit according to the first The values of the voltmeter and the second voltmeter and the resistance of the standard resistor are used to calculate the power of the main heater.

Further, the vacuum pumping device includes an oil diffusion pump, an air storage tank, and a mechanical pump; the vacuum chamber, the oil diffusion pump, the air storage tank, and the mechanical pump are connected through pipelines in sequence; on the pipeline between the vacuum chamber and the oil diffusion pump Equipped with high vacuum valve.

Further, the vacuum pumping device also includes a three-way valve; the three-way valve includes a main port and two selection ports; the main port communicates with the mechanical pump through a pipeline; one of the selection ports communicates with the gas storage tank through a pipeline The other selection port is directly communicated with the vacuum chamber through a pipeline; the data measurement and processing device also includes a high vacuum gauge, a first low vacuum gauge and a second low vacuum gauge; the high vacuum gauge is arranged between the high vacuum valve and the On the pipeline between the oil diffusion pump; the first low vacuum gauge is set on the pipeline between the three-way valve and the mechanical pump; the second low vacuum gauge is set on the pipeline between the three-way valve and the vacuum chamber . The high-vacuum mechanism and the low-vacuum mechanism share a mechanical pump, which can be switched through a three-way valve, which simplifies the pipeline connection and saves costs.

Further, the sample heating assembly includes a main heater and an auxiliary heater; the auxiliary heater is semi-enclosed, and the main heater is arranged in the semi-enclosed space of the auxiliary heater. The auxiliary heater is used for sample temperature compensation.

Further, the sample heating assembly also includes a soaking plate, and the soaking plate is arranged on the main heater. Heat the sample evenly.

Further, it also includes a lifting pin fixedly connected with the vacuum cover, the lifting pin is equipped with a power unit and a control button electrically connected with the power unit, and the power unit drives the lifting pin to move up and down. Control the lifting pin shaft to move up and down through the control button to drive the vacuum cover to open or close, improving labor efficiency.

Further, the constant temperature cooling device is a circulating cooling water device or a liquid nitrogen tank.

Further, the side of the heat sink facing the vacuum test space is coated with matt black paint.

Further, the tester also includes a test host; the test host includes a display screen, a vacuum pressure gauge, a temperature display and a control panel; the vacuum pressure gauge displays the first low vacuum gauge, the second low vacuum gauge and the high vacuum gauge. The measured values; the temperature display device displays the measured values of the first temperature measuring unit and the second temperature measuring unit; the control panel is provided with a plurality of control buttons.

Description of drawings

Fig. 1 is a device connection diagram of a steady-state calorimeter method hemispherical emissivity tester of the present utility model

Fig. 2 is a schematic diagram of the internal structure of the vacuum 1 in Fig. 1

Fig. 3 is a circuit diagram of the main heater 31 and the auxiliary heater 32 in Fig. 2

Referring to the accompanying drawings and specific embodiments below, the utility model will be further described.

Detailed ways

The principle of measuring the hemispherical emissivity of the material by the steady-state card meter method is as follows: Assume that the hemispherical emissivity ε _H of the sample is equal to the hemispherical absorptivity, when the temperature T of the sample reaches thermal equilibrium, the following relationship is expressed:

$\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}\mathrm{<span\; class="notranslate">\; \&sigma;A</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula, σ is the Stephen-Boltzmann constant; A is the surface area of the sample; T and T ₀ are the temperature of the sample and the inner wall of the test chamber; _Q is the heating power of the heater; Heat loss; Q _g is the heat loss caused by residual gas in the test chamber; Q _r is the energy absorbed by the sample and the test chamber wall for multiple reflections.

During the test, the test chamber maintains a high vacuum, and the surface area of the test chamber is much larger than the surface area of the sample, so Q _g and Q _r can be ignored; since the heating wire and the diameter of the lead wire are small, the heat of the lead wire can be ignored. Loss of Q _w . That is, formula (1) is equivalent to

${\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;A</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Therefore, the hemispherical emissivity ε _H of the sample can be calculated by measuring the heating power Q of the test heater, the temperature T of the sample, the temperature T ₀ of the inner wall of the test chamber, and the surface area A of the sample.

Please refer to Fig. 1 and Fig. 2, Fig. 1 is a device connection diagram of a steady-state calorimeter hemispherical emissivity tester of the present invention, and Fig. 2 is a schematic diagram of the internal structure of the vacuum chamber 1 in Fig. 1 . The utility model relates to a hemispherical emissivity tester with a steady-state calorimeter method, comprising a vacuum chamber 1, a constant temperature cooling device 2, a sample heating component 3, a vacuuming device 4, a data measurement and processing device 5 and a test host. The vacuum chamber 1 includes a vacuum cover 11, a flange 12 arranged at the bottom of the vacuum cover, and a heat sink 13 fixed on the inner wall of the vacuum cover 11 in a semi-enclosed shape; A vacuum test space is formed, and a cooling medium channel 14 is left between the outward facing side and the inner wall of the vacuum cover 11 . The constant temperature cooling device 2 communicates with the cooling medium passage 14 of the vacuum chamber 1 through a pipeline, which generates cooling medium and exchanges heat with the heat sink to keep the temperature of the heat sink constant. The sample heating assembly 3 is arranged in the vacuum chamber 1 , the sample to be tested is placed on the sample heating assembly 3 and is heated by the sample heating assembly 3 . The vacuuming device 4 communicates with the vacuum testing space of the vacuum chamber 1 for evacuating the vacuum chamber 1 . The data measuring and processing device 5 is used to measure the running data of the tester, and calculate the hemispherical emissivity ε _H of the sample when the sample temperature T reaches a preset temperature and the vacuum chamber 1 is in a thermally stable state.

A lifting pin 15 is fixed on the outer wall of the vacuum cover 11, and the lifting pin 15 is connected with a power unit, and the power unit is electrically connected with the up button and the down button respectively; The shaft 15 is manipulated to control the up and down movement of the vacuum cover 11 and improve labor efficiency; the power unit is preferably a motor. The inwardly facing side of the heat sink 13 is painted with matt black paint. The cooling medium passage 14 is provided with a cooling medium inlet 16 and a cooling medium outlet 17 . The cooling medium inlet 16 and the cooling medium outlet 17 are respectively communicated with the constant temperature cooling device 2 through pipelines; after the cooling medium is generated from the constant temperature cooling device 2, it enters the cooling medium channel 14 through the cooling medium inlet 16, and exchanges heat with the heat sink 13 To maintain the temperature of the heat sink 13, and return to the constant temperature cooling device 2 through the cooling medium outlet 17 for re-refrigeration.

The constant temperature cooling device 2 is a circulating cooling water device or a liquid nitrogen tank.

The sample heating assembly 3 includes a main heater 31 , an auxiliary heater 32 and a vapor chamber 33 . The main heater 31 is used to heat the sample A to a predetermined temperature. As shown in FIG. 3 , it is a circuit diagram of the main heater 31 and the auxiliary heater 32 in FIG. 2 . The main heater 31 is connected in series with a standard resistor and a DC power supply to form a main heating circuit. The vapor chamber 33 is placed on the main heater 31 . The sample A is placed on the vapor chamber 33 so that the sample A is evenly heated. The auxiliary heater 32 is in a semi-enclosed shape, and the sample A, vapor chamber 33 and main heater 31 are placed in the auxiliary heater 32, and the space between the sample A and the auxiliary heater 32 is sealed by a cover plate 34. The gap was closed so that all the heat generated by the main heater 31 was supplied to the sample A. The auxiliary heater 32 has a built-in coil, and the coil is heated by receiving an alternating current. The auxiliary heater 32 supplies all the heat generated by the main heater 31 to the sample A as compensation heating, and keeps the temperature of the sample constant.

The vacuum device 4 includes a three-way valve 41, an oil retainer 42, an oil diffusion pump 43, an air tank 44, and a mechanical pump 45; the three-way valve 41 includes a main port, a first selection port and a second selection port . The main port communicates with the mechanical pump 45 through a pipeline, and the pipeline is provided with a solenoid valve 46; The through valve 41 is on-off. The first selection port communicates with the vacuum chamber 1 through a pipe. The vacuum chamber 1 , the oil retainer 42 , the oil diffusion pump 43 , the gas storage tank 44 and the second selection port are connected through pipelines in sequence; a high vacuum valve 47 is arranged on the pipeline between the oil diffusion pump 43 and the vacuum chamber 1 . This three-way valve 41 is provided with a handle, and the handle can be pulled out to the dead point position, or pushed inward to the dead point position. When the three-way valve 41 is in the position of pushing in to the dead point, the second selection port communicates with the main port; when the three-way valve 41 is in the position of pulling out to the dead point, the first selection port communicates with the main port . The function of the three-way valve 41 is equivalent to a selector, which selects the pipeline in which the mechanical pump 45 works.

The data measurement and processing device 5 includes a first temperature measurement unit, a second temperature measurement unit, a third temperature measurement unit, a fourth temperature measurement unit, a first voltmeter, a second voltmeter, a high vacuum gauge 51, a first Rough gauge 52, second rough gauge 53 and processing unit. The first temperature measurement unit is arranged on the sample to measure the temperature T of the sample. The second temperature measuring unit is arranged on the heat sink to measure the temperature T ₀ of the heat sink. The third temperature measuring unit is arranged at the cooling medium inlet 16 . The fourth temperature measuring unit is arranged at the cooling medium outlet 17 . The first voltmeter is connected in parallel with the main heater 31 to measure the terminal voltage V of the main heater 31 . The second voltmeter is connected in parallel with the standard resistance to measure the voltage V1 of the standard resistance. The high vacuum gauge 51 is arranged between the high vacuum valve 47 and the oil deflector 42 . The first rough vacuum gauge 52 is disposed between the three-way valve 41 and the solenoid valve 46 . The second rough vacuum gauge 53 is arranged between the three-way valve 41 and the vacuum chamber 1 . The processing unit calculates the power Q of the main heater according to the values of the first voltmeter and the second voltmeter and the resistance value R of the standard resistor. And, when using circulating cooling water as the constant temperature device, the heat sink temperature _T0 is the average value of the values detected by the third and fourth temperature measuring units, that is, the average temperature value of the cooling medium inlet 16 and the cooling medium outlet 17; Liquid nitrogen is used as a constant temperature device, and the heat sink temperature T ₀ is the temperature value detected by the second unit.

When the sample temperature T reaches the preset temperature and the vacuum chamber 1 is in a thermally stable state, the data measuring and processing device 5 will perform the test according to the sample temperature T, the heat sink temperature T ₀ , the power Q of the main heater and the sample temperature. Calculate the hemispherical emissivity ε _H of the sample from the radiating surface area S. in, ${\mathrm{\&epsiv;}}_h=\frac{Q}{\mathrm{\&sigma;A}(T^4-T_0^4)},Q=\frac{V1}{R}V.$

The test host includes a display screen, a vacuum pressure gauge, a temperature indicator and a control panel; the vacuum pressure gauge displays the values measured by the first low vacuum gauge 52 , the second low vacuum gauge 53 and the high vacuum gauge 51 . The temperature display device displays the measured values of the first temperature measuring unit, the second temperature measuring unit, the third temperature measuring unit and the fourth temperature measuring unit. The control panel is provided with a test host power button, a display power button, a temperature indicator power button, a mechanical pump switch button, a constant temperature cooling device switch button, a cooling water switch button, a vacuum cover up button, a vacuum cover down button, and a main Heater switch button and auxiliary heater switch button.

Further, the vacuum chamber 1 is additionally communicated with the air pump through a pipeline, and an inflation valve is arranged between the vacuum chamber 1 and the air pump.

The measurement principle of a steady-state calorimeter method hemispherical emissivity tester of the utility model: a test sample is placed in the vacuum chamber 1, there is only radiation heat exchange between the sample surface and the vacuum chamber 1, and the sample emits All of the heat radiation is projected onto the heat sink surface of the vacuum chamber 1. The electric heating method is used to provide a continuous heating power to the sample, so that the sample is heated to the measurement temperature, and the sample conducts heat exchange with the cooling blackbody cavity in which it is located through thermal radiation. When the thermal balance between the sample and the environment is reached, the data of the heater temperature T, the heat sink temperature T ₀ , the terminal voltage V of the main heater and the terminal voltage V1 of the standard resistor are collected by the data measuring and processing device 5, and then according to the sample The surface area S of the sample is directly calculated by the computer software to calculate the hemispherical emissivity ε _H of the sample.

The concrete operating procedure of a kind of steady-state calorimeter method hemispherical emissivity tester of the present utility model is as follows:

Press the vacuum cover up button, raise the vacuum cover 11 to a suitable height through the lifting pin, fix the prepared test sample on the soaking plate 33 of the vacuum chamber 1 with thermal conductive silicone grease, and press it with the pressure plate 34, and then Press the down button of the vacuum cover to lower the vacuum cover 11 to the lowest point, so that the vacuum cover 11 and the sealing ring of the bottom flange are compressed under negative pressure. Pre-pump the vacuum chamber 1 to low vacuum: pull the three-way valve 41 outward to the dead point, and keep the high vacuum valve 47 closed. Open the following buttons on the control panel: test host power button, display power button, temperature display instrument power button, mechanical pump switch button. When the pressure of the vacuum chamber 1 is less than or equal to 10Pa, vacuumize the oil retainer 42 and the oil diffusion pump 43: push the handle of the three-way valve 41 to the dead point, and keep the high vacuum valve 47 in a closed state , when the pressure of the oil diffusion pump 43 reaches below about 6Pa, turn on the cooling water switch button to connect the cooling water of the oil diffusion pump 43, heat the oil diffusion pump 43, and turn on the constant temperature water or liquid nitrogen. If liquid nitrogen is used, Then unscrew the pressure reducing valve of the liquid nitrogen bottle directly to control the pressure at 0.05-0.1MPa. After heating the oil diffusion pump 43 for 40 minutes, pull the three-way valve 41 outward to the dead point position, and then evacuate the vacuum chamber 1 below 10 Pa: push the three-way valve 41 inward to the dead point position, and turn the high vacuum Valve 47 is opened, and the following buttons are pressed on the control panel: the main heater switch button and the auxiliary heater switch button, and the sample starts to be heated and heated. When the sample temperature T reaches the preset temperature and the vacuum chamber 1 is in a thermally stable state (within 20 minutes, the sample temperature fluctuation is not greater than 0.1°C), measure the sample temperature T, heat sink temperature T ₀ , The terminal voltage V of the main heater 31 and the terminal voltage V1 of the standard resistor; wherein, the heat sink temperature T ₀ is the average value of the temperatures of the cooling medium inlet 15 and the cooling medium outlet 16 when the sample temperature T reaches the detected temperature. The data is collected by the data measuring and processing device 5, and then according to the surface area S of the sample, the hemispherical emissivity ε _H of the sample is directly calculated by computer software.

After the test is completed, turn off the power supply for vacuum measurement, stop the oil diffusion pump 43 for heating, and close the high vacuum valve. Open the inflation valve to inflate the vacuum cover 11. Raise the vacuum cover 11, take out the sample, lower the vacuum cover 11, close the inflation valve, pull out the three-way valve 41 to the dead point, and vacuum the vacuum cover 11 for 3-5 minutes. After the oil diffusion pump 43 is cooled to room temperature, stop the mechanical pump 45 again to ensure that the oil diffusion pump 43 keeps the vacuum. Turn off the cooling water and the power supply of the oil diffusion pump 43, and all work ends.

In the test process, after the vacuum container is sealed, the vacuum must be drawn down first, and the high vacuum valve should be opened after the vacuum has been drawn down to 6Pa. Oxidation, which destroys the performance of the diffusion pump. At the end of the vacuum operation, you must first cut off the vacuum measurement, then close the high vacuum valve, and then open the inflation valve. If the high vacuum measurement is not cut off and the gas is filled, the filament of the ionization tube will be burned immediately. If the high vacuum valve is not closed and the gas is filled, the diffusion pump oil will Oxidation, the diffusion pump will not work properly. During the working process, always pay attention to whether the cooling water is unblocked, whether the water temperature and flow are normal. In case of a sudden power failure, immediately cut off the vacuum measurement and close the high vacuum valve, pull the three-way valve 41 to the dead point (the cooling water cannot be cut off), after the power is turned on, wait for the mechanical pump 45 to work for 2-3 minutes before closing the three-way valve. Valve 41 is pushed inward to the dead point, and continues to turn into normal work, if the power supply cannot be repaired within 30 minutes, the diffusion pump should be deheated and cooled as fast as possible.

Compared with the prior art, a steady-state calorimeter hemispherical emissivity tester of the present invention includes a vacuum chamber 1, a constant temperature cooling device 2, a sample heating component 3, a vacuuming device 4, and a data measurement and processing device 5. Through the steady-state calorimeter method, it overcomes the strict requirements on the thermal conductivity and specific heat capacity of materials during the test process. The test accuracy is high, the test temperature range is wide, and the application is relatively wide. It can test materials under different temperature conditions, especially at low temperatures. Lower hemispheric emissivity. Using the test results of the test device, the hemispherical emissivity of the material can be conveniently calculated, and the test and calculation are relatively simple.

The above are only preferred implementations of the present utility model. It should be pointed out that the above-mentioned preferred implementations should not be regarded as limitations on the present utility model, and the protection scope of the present utility model should be based on the scope defined by the claims. For those skilled in the art, without departing from the spirit and scope of the utility model, some improvements and modifications can also be made, and these improvements and modifications should also be regarded as the protection scope of the utility model.

Claims (10)

1. The utility model provides a hemisphere emissivity tester of steady state calorimetry method which characterized in that: comprises a vacuum chamber, a sample heating component, a vacuumizing device, a constant-temperature cooling device and a data measuring and processing device;

the vacuum chamber comprises a vacuum cover and a heat sink which is fixedly arranged on the inner wall of the vacuum cover and is in a semi-surrounding shape; the inward side of the heat sink forms a vacuum test space, and a cooling medium channel is reserved between the outward side and the inner wall of the vacuum cover; a cooling medium inlet and a cooling medium outlet are arranged in the cooling medium channel;

the sample heating assembly is arranged in a vacuum test space of the vacuum chamber to heat a sample and comprises a main heater; the main heater, a standard resistor and a direct current power supply form a series circuit;

the vacuum pumping device is communicated with the vacuum test space of the vacuum chamber through a pipeline;

the constant-temperature cooling device is communicated with a cooling medium inlet and a cooling medium outlet of the cooling medium channel through pipelines respectively;

the data measuring and processing device collects the temperature of a sample, the temperature of a heat sink, the vacuum degree in the vacuum chamber and the power of the main heater; when the data measuring and processing device detects that the pressure in the vacuum chamber reaches 1.0X10^-3Pa below, and when the temperature of the sample reaches the set temperature, the data measuring and processing device calculates the hemispherical emissivity of the sample according to the temperature of the sample, the temperature of the heat sink, the power of the main heater and the radiation surface area of the sample.

2. The steady-state calorimeter hemispherical emissivity tester of claim 1, wherein: the data measuring and processing device comprises a first temperature measuring unit, a second temperature measuring unit, a third temperature measuring unit, a fourth temperature measuring unit, a first voltmeter, a second voltmeter and a processing unit; the first temperature measuring unit is arranged on the sample and is used for measuring the temperature of the sample; the second temperature measuring unit is arranged on the heat sink; the third temperature measuring unit is arranged at a cooling medium inlet; the fourth temperature measuring unit is arranged at the cooling medium outlet; the first voltmeter is connected with the main heater in parallel and used for measuring the voltage of the main heater; the second voltmeter is connected in parallel to the standard resistor and used for measuring the voltage of the standard resistor; and the processing unit calculates the power of the main heater according to the values of the first voltmeter and the second voltmeter and the resistance value of the standard resistor.

3. The steady-state calorimeter hemispherical emissivity tester of claim 2, wherein: the vacuumizing device comprises an oil diffusion pump, a gas storage tank and a mechanical pump; the vacuum chamber, the oil diffusion pump, the gas storage tank and the mechanical pump are communicated in sequence through pipelines; a high vacuum valve is arranged on a pipeline between the vacuum chamber and the oil diffusion pump.

4. The steady-state calorimeter hemispherical emissivity tester of claim 3, wherein: the vacuum-pumping device also comprises a three-way valve; the three-way valve comprises a main port and two selection ports; the main port is communicated with the mechanical pump through a pipeline; one of the selection ports is communicated with the gas storage tank through a pipeline, and the other selection port is directly communicated with the vacuum chamber through a pipeline; the data measuring and processing device also comprises a high vacuum gauge, a first low vacuum gauge and a second low vacuum gauge; the high vacuum gauge is arranged on a pipeline between the high vacuum valve and the oil diffusion pump; the first low vacuum gauge is arranged on a pipeline between the three-way valve and the mechanical pump; the second low vacuum gauge is arranged on a pipeline between the three-way valve and the vacuum chamber.

5. The steady-state calorimeter hemispherical emissivity tester of claim 4, wherein: the sample heating assembly comprises a main heater and an auxiliary heater; the auxiliary heater is in a semi-surrounding shape, and the main heater is arranged in a semi-surrounding space of the auxiliary heater.

6. The steady-state calorimeter hemispherical emissivity tester of claim 5, wherein: the sample heating assembly also includes a vapor chamber disposed above the primary heater.

7. The steady-state calorimeter hemispherical emissivity tester of claim 6, wherein: the vacuum cover is fixedly connected with the vacuum cover, the lifting pin shaft is provided with a power unit and a control button electrically connected with the power unit, and the power unit drives the lifting pin shaft to move up and down.

8. The steady-state calorimeter hemispherical emissivity tester of claim 7, wherein: the constant temperature cooling device is a circulating cooling water device or a liquid nitrogen tank.

9. The steady-state calorimeter hemispherical emissivity tester of claim 8, wherein: the side of the heat sink facing the vacuum test space is coated with a matt black paint.

10. The steady-state calorimeter hemispherical emissivity tester of claim 9, wherein: the tester also comprises a test host; the test host comprises a display screen, a vacuum pressure gauge, a temperature display instrument and a control panel; the vacuum pressure gauge displays the values measured by the first low vacuum gauge, the second low vacuum gauge and the high vacuum gauge; the temperature display instrument displays the measured numerical values of the first temperature measuring unit, the second temperature measuring unit, the third temperature measuring unit and the fourth temperature measuring unit; and a plurality of control buttons are arranged on the control panel.