CN104502392B - Failure test method is freezed in a kind of two-phase fluid loop - Google Patents

Abstract

The invention discloses a kind of two-phase fluid loop and freeze failure test method. Use the present invention to test in the failure state exceeding under working medium condensation temperature environment two-phase fluid loop, and analyze the impact of freezing two-phase fluid loop heat transfer property. First the present invention has designed test battery device, the operating temperature in the temperature control two-phase fluid loop by control simulation thermal source and heat sink, and design experiment method, freezes failure performance to two-phase fluid loop and tests. Wherein, being furnished with of temperature sensor is beneficial to the state of observing ammonia working medium in two-phase fluid loop, checks whether satisfied temperature requirement of each parts in two-phase fluid loop, can also check whether two-phase fluid loop reaches balance simultaneously.

Description

A two-phase fluid circuit freezing failure test method

technical field

The invention relates to the technical field of spacecraft thermal control, in particular to a two-phase fluid circuit freezing failure test method.

Background technique

Two-phase fluid circuit technology is a spacecraft thermal control technology that has been developed at home and abroad in the past two decades, mainly including loop heat pipe technology, mechanical pump-driven two-phase fluid circuit technology, gravity-driven two-phase fluid circuit technology, etc. The gravity-driven two-phase fluid circuit system is the key technology for the rover and lander in the Chang'e lunar exploration project to spend the moon night. Through the two-phase fluid circuit system, the heat of the isotope heat source is brought into the load compartment to ensure that the equipment in the load compartment temperature is not too low. The system composition of gravity-driven two-phase fluid circuit is shown in Figure 1, including evaporator 1 (including wire mesh evaporator 7, liquid divider 8 and vapor confluence 9), steam pipeline 2, condensation pipeline 3, liquid storage 4, liquid pipeline 6 and control valve 5, wherein, the condensation pipeline 3 is located above the gravity field of the liquid reservoir 4, the evaporator 1 is located below the gravity field of the liquid reservoir 4, and is coupled with the isotope heat source, and the liquid reservoir A gravity-assisted height difference is formed between the inner liquid level in 4 and the bottom of evaporator 1; the liquid reservoir 4 is connected to the inlet of evaporator 1 through a liquid pipeline 6, and a control valve 5 is arranged on the liquid pipeline 6, and the outlet of evaporator 1 is sequentially The steam pipeline 2 and the condensation pipeline 3 are connected to the liquid reservoir 4 to form a closed pipeline system. In order to ensure that the gravity-driven two-phase fluid circuit has good heat transfer characteristics in the temperature range of -50°C to 70°C, ammonia was selected as the working medium. During the moon night, the gravity-driven two-phase fluid circuit control valve 5 is opened, and the gravity-driven two-phase fluid circuit is activated to introduce the heat of the isotope nuclear heat source into the detector. During the moon and day, the gravity-driven two-phase fluid circuit control valve 5 is closed, closing the gravity-driven two-phase fluid circuit, and blocking the isotope nuclear heat source from transferring heat source to the detector.

The freezing condition of the two-phase fluid circuit is a fault condition. In order to prevent the insufficient heat transfer capacity of the gravity-driven two-phase fluid circuit on the surface of the moon or the failure of the instrument, it is necessary to test the freezing condition of the two-phase fluid circuit at low temperature to verify Failure mechanism and failure consequences of freezing in two-phase fluid circuits.

Since the gravity-driven two-phase fluid circuit technology is a new thermal control method for spacecraft thermal control, there is no fixed test method and test method. At the same time, considering the harsh environment of the moon, it is necessary to test the freezing failure process of the gravity-driven two-phase fluid circuit and the heat transfer capacity of thawing after freezing, so as to guide the on-orbit application of the gravity-driven two-phase fluid circuit.

Contents of the invention

In view of this, the present invention provides a two-phase fluid circuit freezing failure test method, which can test the failure state of the two-phase fluid circuit in an environment exceeding the condensation temperature of the working medium, and analyze the effect of freezing on the heat transfer performance of the two-phase fluid circuit Impact.

In order to solve the problems of the technologies described above, the present invention is achieved in that:

Step 1, design the test device:

The test device includes a heat dissipation plate, a temperature control heater, a multi-layer heat insulation assembly, a temperature sensor, a simulated heat source and a loop support; wherein, the heat dissipation plate is installed on the upper part of the loop support through a heat insulation pad; the two-phase fluid circuit The condensing pipeline is buried in the heat dissipation plate, and the liquid reservoir of the two-phase fluid circuit is half buried in the heat dissipation plate; the evaporator in the two-phase fluid circuit is heat-insulated and installed at the lower part of the circuit support; the temperature control heater is installed in the two-phase fluid circuit On the steam line, liquid receiver, control valve and liquid line of the circuit; the temperature sensor is installed on the evaporator, steam line, condensing line, liquid receiver, control valve and liquid line of the two-phase fluid circuit, simulated heat source And on the edge area of the cooling plate; multi-layer heat insulation components are wrapped on the steam pipeline, liquid reservoir, control valve and liquid pipeline; the simulated heat source is RHU isotope electric simulation heat source, fixedly installed in the evaporator; the installation is provided for the cooling plate A heat sink heater with working temperature, the heat sink heater is an infrared heater installed in the outer space of the heat sink or a heating sheet pasted on the heat sink;

Step 2, put the loop bracket into the vacuum chamber, pump the vacuum to make the vacuum degree less than 2×10 ^-3 Pa, set the temperature control heaters on the liquid reservoir, control valve, liquid pipeline and steam pipeline to the automatic control state, The automatic control threshold is -70°C; set the automatic control threshold of the heat sink heater to -70°C;

Step 3, pass liquid nitrogen to the heat sink of the vacuum chamber, reduce the temperature of the vacuum chamber to -150°C; reduce the temperature of the liquid reservoir to -60°C, and reach the equilibrium of the two-phase fluid circuit; the equilibrium of the operating conditions is The temperature of the liquid reservoir remains unchanged for half an hour or the monotonous change is less than 1°C/h; the temperature of the liquid reservoir is the working temperature of the two-phase fluid circuit;

Step 4, limit heat transfer capacity test:

Turn on the simulated heat source, increase the heating power of the simulated heat source according to a certain step, and decrease the heating power of the radiator heater while increasing the heating power of the simulated heat source each time, so that the temperature of the liquid reservoir is maintained at T ₁ , -60 ℃≤T ₁ ≤-70℃, and reach the balance of the two-phase fluid circuit working condition, until the heating power of the radiator heater is zero or the working condition balance cannot be maintained due to the sudden rise of the temperature of the evaporator, the heating of the radiator heater When the power is zero or the heating power of the simulated heat source at the equilibrium moment before the temperature of the evaporator suddenly rises is the limit heat transfer capacity of the two _- phase fluid circuit at the working temperature of T1;

Step 5, freeze:

Turn off the heat sink heater and the simulated heat source heater, wait for the temperature of each measuring point to drop below -90°C, and maintain it for a period of time to fully freeze the two-phase fluid circuit;

Step 6, unfreeze:

First turn on and increase the heating power of the radiator plate to raise the temperature of the condensing pipeline above the freezing point of the working fluid, then turn on the temperature-controlled heaters and simulated heat sources of the liquid receiver, liquid pipeline, valve, and steam pipeline to make the storage Liquid vessels, liquid pipelines, valves, steam pipelines, and evaporators are evenly heated to above the freezing point of the working medium;

Step 7, maintain the temperature of the liquid reservoir at T ₁ , obtain the limit heat transfer capacity of the two-phase fluid circuit after thawing at the working temperature T ₁ according to the method in step 4, and obtain the limit heat transfer capacity at the same working temperature obtained in step 3 If the deviation of heat transfer capacity is less than 10%, it means that the heat transfer performance of the two-phase fluid circuit will not be affected after freezing failure and thawing; damage.

Among them, in step 3, the limit heat transfer capacity of the two-phase fluid circuit at multiple low temperature working temperatures is measured, and in step 7, the limit heat transfer capacity of the two-phase fluid circuit at the corresponding low temperature working temperature is measured, and the same value before and after freezing is calculated. The limit heat transfer capability deviation of the two-phase fluid circuit at the working temperature, where the low temperature working temperature is -60°C to -70°C.

In the cooling process of the step 3, the simulated heat source is turned on, so that the two-phase fluid circuit runs, and the cooling rate of the evaporator is accelerated.

The substrate of the heat dissipation plate is an aluminum plate or a honeycomb plate, and the surface of the heat dissipation plate is pasted with an OSR sheet or sprayed with a high emissivity coating.

The installation location of the temperature sensor is:

At least 2 temperature sensors are respectively arranged along the height direction on the 4 fins of the evaporator, one of which is located at the lower end of the evaporator fin and one is located at the upper end of the evaporator fin;

A temperature sensor is respectively arranged at the inlet, top and outlet of the steam pipeline;

A temperature sensor is arranged at the inlet and outlet of the condensing pipeline, and at least one temperature sensor is arranged on the fin of the condensing pipeline;

Three temperature sensors are arranged along the height direction on the outer surface of the reservoir, which are respectively located in the gas space, gas-liquid interface and liquid space of the reservoir;

Arrange at least one temperature sensor on the liquid pipeline connecting the liquid reservoir and the control valve, and arrange at least one temperature sensor on the liquid pipeline connecting the control valve and the evaporator;

A temperature sensor is arranged on the control valve;

Arrange at least one temperature sensor on the simulated heat source;

At least one temperature sensor is arranged on the edge area of the inner surface of the cooling plate.

The temperature control heater is a heating sheet, a heating wire, a heating belt or a heating plate.

The evaporator is installed on the heat insulation board, the simulated heat source is placed inside the evaporator, and the lugs of the simulation heat source tooling are fixed on the heat insulation board through screws and heat insulation pads, and the heat insulation board passes through 4 heat insulation columns Fixed installation on the loop bracket.

The material of the heat insulation board, heat insulation pad and heat insulation column is glass fiber reinforced plastic or polyimide.

Beneficial effect:

(1) The failure state of the two-phase fluid under freezing conditions can be tested by using the present invention, and the heat transfer performance of the thawed two-phase fluid circuit can be analyzed to evaluate the influence of freezing on the two-phase fluid circuit.

(2) Due to the different cooling rates of the condensing pipeline and the evaporator, increasing the heating power of the simulated heat source during the cooling process can increase the temperature of the evaporator, and the ammonia working fluid in the two-phase fluid circuit transfers the heat of the evaporator to the condensing The pipeline can increase the cooling rate of the evaporator.

(3) The substrate of the cooling plate is selected as an aluminum plate or a honeycomb plate, and an OSR sheet is pasted on its surface or a coating with a high emissivity is sprayed, which is beneficial to improving the heat dissipation rate of the cooling plate.

(4) The arrangement of the temperature sensor is beneficial to observe the state of the ammonia working medium in the two-phase fluid circuit, and it is possible to check the freezing process of each component in the two-phase fluid circuit, and to check the freezing process of each component in the two-phase fluid circuit under non-freezing conditions. Whether the temperature of the components meets the requirements and whether the two-phase fluid circuit reaches equilibrium.

Description of drawings

Figure 1 is a schematic diagram of the composition of the gravity-driven two-phase fluid circuit system.

Fig. 2 is a schematic diagram of a vacuum thermal performance test device for a two-phase fluid circuit.

Figure 3 is a schematic diagram of the installation of a two-phase fluid circuit evaporator.

Fig. 4 is a schematic diagram of the arrangement of temperature sensors on a two-phase fluid circuit.

Fig. 5 is a schematic diagram of the arrangement of temperature sensors on the cooling plate (including the condensation pipeline).

Among them, 1-evaporator, 2-steam pipeline, 3-condensing pipeline, 4-reservoir, 5-control valve, 6-liquid pipeline, 7-wire evaporator, 8-liquid splitter, 9 - steam confluence, 10 - vacuum chamber, 11 - cooling plate, 12 - heat insulation plate, 13 - heat insulation pad, 14 - heat insulation column, 15 - simulated heat source, 16 - infrared heater, 17 - loop support.

detailed description

The present invention will be described in detail below with reference to the accompanying drawings and examples.

The present invention provides a two-phase fluid circuit freezing failure test method, the method is based on the test device shown in Figure 2 for test testing, the test device includes a cooling plate 11, a temperature control heater, a multi-layer heat insulation assembly, Temperature sensor, simulated heat source 15 and loop support 17.

Wherein, the two-phase fluid circuit and the heat dissipation plate 11 are installed on the circuit support 17 with heat insulation, and the heat dissipation plate 11 is installed on the upper part of the circuit support 17 with heat insulation pads, for simulating the heat dissipation part of the two-phase fluid circuit on the rail; The condensation pipeline 3 of the phase fluid circuit is buried in the cooling plate 11, and the liquid reservoir 4 of the two-phase fluid circuit is half buried in the cooling plate 11, and is located at the outlet of the condensation pipeline 3; the evaporator 1 in the two-phase fluid circuit Heat insulation is installed on the lower part of the circuit support 17, located below the condensation pipeline 3; the temperature control heater is installed on the steam pipeline 2, the liquid reservoir 4, the control valve 5 and the liquid pipeline 6 of the two-phase fluid circuit to prevent The pipeline is frozen; the temperature sensor is installed on the evaporator 1, the steam pipeline 2, the condensation pipeline 3, the liquid receiver 4, the control valve 5 and the liquid pipeline 6 of the two-phase fluid circuit, and the cooling plate 11 to measure The temperature of each component of the two-phase fluid circuit and the cooling plate is used to detect the operation of the two-phase fluid circuit; the multi-layer heat insulation component is installed on the steam pipeline 2, the liquid reservoir 4, the control valve 5 and the liquid pipeline 6, and is used to Prevent environmental heat leakage in the pipeline part, and simulate on-orbit working conditions; the simulated heat source 15 adopts RHU isotope electric simulated heat source, which is fixedly installed in the evaporator 1, and is used to simulate the isotope heating device, and the simulated heat source 15 is also the temperature control of the evaporator 1 The heater; the loop support 17 is placed in the vacuum chamber 10, and the vacuum chamber 10 provides a vacuum environment with a temperature not greater than 80K and a vacuum degree of less than 2×10 ⁻³ Pa.

Among them, the substrate of the heat sink can be made of aluminum plate or honeycomb plate and other materials with good thermal conductivity, and its outer surface is pasted with OSR sheet, or sprayed with high emissivity coating, so as to facilitate heat dissipation.

The heat insulation method between the evaporator 1, the simulated heat source 15 and the loop support 17 is shown in Figure 3, the evaporator 1 is installed on the heat shield 12, the simulated heat source 15 is placed inside the evaporator 1, and the simulated heat source 15 tooling The lugs are fixed on the heat insulation board 12 through screws and heat insulation pads 13, and the heat insulation board 12 is fixedly installed on the circuit support 17 through four heat insulation columns 14. Wherein, the materials of heat insulation plate 12, heat insulation pad 13 and heat insulation column 14 are materials with low thermal conductivity such as polyimide or glass fiber reinforced plastics. The distance between the lower surface of the liquid splitter 8 and the upper surface of the heat shield 12 is greater than 10mm, the effective heat insulation distance between the heat shield 12 and the circuit support 17 is greater than 100mm, and the outer diameter of the heat insulation pad 13 is less than 10mm.

The temperature sensor is a thermocouple temperature sensor, and its layout is shown in Figure 4. Arrange 34 temperature sensors on the two-phase fluid circuit:

① On the 4 fins of the evaporator 1, 3 temperature sensors are evenly arranged from bottom to top along the height direction, a total of 12, numbered T1~T12, and the sensors can also be arranged only at the lower and upper ends of the evaporator fins, mainly It is used to measure the temperature of liquid working medium and gaseous working medium in the evaporator, so as to reflect the working state of the evaporator 1.

② Arrange one temperature sensor at the inlet, top and outlet of the steam pipeline 2, numbered T13, T14 and T15 respectively.

③Arrange 9 temperature sensors at the inlet and outlet of the condensing pipeline 3 and on the condensing pipeline, numbered T16~T24, as shown in Figure 5; the condensing pipeline 3 is generally equipped with fins to increase the heat dissipation area, and the temperature sensor Usually mounted on fins.

④ Arrange three temperature sensors along the height direction on the outer surface of the liquid reservoir 4, numbered T25-T27, which are used to measure the temperature of the gas, gas-liquid interface and liquid in the liquid reservoir 4 respectively.

⑤ The liquid pipeline 6 is divided into two sections, one section connects the liquid reservoir 3 and the control valve 5 , and the other section connects the control valve 5 and the evaporator 1 . Among them, one temperature sensor, numbered T28, is arranged at the midpoint of the liquid pipeline connecting the liquid reservoir 3 and the control valve 5; one is arranged at the inlet and outlet of the liquid pipeline connecting the control valve 5 and the evaporator 1, respectively There are two temperature sensors, numbered T31 and T32 respectively, and one temperature sensor can also be arranged at the midpoint of the liquid pipeline connecting the control valve 5 and the evaporator 1.

⑥ Arrange the temperature sensor on the control valve 5 . If the control valve 5 is composed of two parallel valves (valve a and valve b), one temperature sensor is respectively arranged on valve a and valve b, and the numbers are T29 and T30 respectively;

⑦ Arrange two temperature sensors on the simulated heat source, numbered T33 and T34;

⑧ Arrange four temperature sensors, numbered T35 and T38, on the edge area of the inner surface of the cooling plate 11, and the four temperature sensors are 100 mm away from the edge of the cooling plate, as shown in FIG. 5 .

The location of the temperature sensor is the location of the measuring point.

The temperature control heater can be a heating sheet, heating wire, heating belt, heating plate or other heating methods, and adopts PID control or on-off temperature control, mainly to prevent the components of the two-phase fluid circuit from being frozen. Among them, the temperature control heater on the liquid reservoir 4 is implemented by installing two heating plates in series on the liquid reservoir 4; the temperature control heater on the control valve 5 is realized by installing a heating belt on the liquid pipeline connected to the control valve 5, As shown in Figure 2 (pipeline between measuring point 28 and measuring point 29, pipeline between measuring point 29 and measuring point 31, pipeline between measuring point 28 and measuring point 30, side point 30 and measuring point 31 1 heating belt, 4 heating belts connected in series, each section of pipeline is about 50mm long; the temperature control heater on the liquid pipeline 6 adopts the measuring point 31 and the measuring point 32 is installed with one heating belt; the temperature control heater on the steam pipeline 2 is realized by three heating belts installed in series.

The temperature control heater on the liquid reservoir 4, the control valve 5, the liquid pipeline 6 and the steam pipeline 2 mainly plays the role of preventing the pipeline from freezing.

The temperature control of the evaporator 1 is realized by means of a simulated heat source 15 installed inside it. Since the heat of the isotope heat source is carried away by the two-phase fluid circuit during the heat transfer process, the temperature of the surface of the isotope heat source itself will be reduced to be consistent with the temperature of the evaporator.

The condensation pipeline 2 is pre-buried in the heat sink 11, and the temperature of the heat sink 11 is basically the same. The temperature control of the heat sink 11 is realized by the infrared heater 16 installed on the outside of the heat sink 11 or the heating sheet pasted on the heat sink. .

Wherein, the temperature of the cooling plate 11 is controlled to be -60°C to 50°C. Due to the heat transfer effect of the ammonia working medium during the operation of the two-phase fluid circuit, the temperature of the evaporator 1, the steam pipeline 2, the condensation pipeline 3, the liquid receiver 4, the control valve 5 and the liquid pipeline 6 is basically at -55°C ~50°C range. Wherein, the temperature of the liquid reservoir 4 is the working temperature of the two-phase fluid circuit.

Select measuring points T1 (lower part of evaporator 1, near the outlet of liquid pipeline 6), T3 (upper part of evaporator 1, near the inlet of steam pipeline 2), T14 (middle part of steam pipeline 2), T17 (condensation pipeline 3 Inlet), T23 (outlet of condensing pipeline 3), T25 (upper part of reservoir 4, i.e. air space of reservoir), T27 (lower part of reservoir), T29~T30 (control valve a and control valve b), T31 (Liquid pipeline 6 inlet), T35 ~ T38 (4 corners of heat sink 11) are temperature monitoring points, monitor whether the simulated heat source 15, heat sink 11 and two-phase fluid circuit meet the temperature requirements, and at the same time, by comparing the temperature monitoring points With the temperature of other measuring points, judge whether to reach equilibrium.

Use the above-mentioned test device to conduct the freezing failure test of the two-phase fluid circuit, check the freezing process of the two-phase fluid circuit under freezing conditions, and the limit heat transfer performance of the two-phase fluid circuit after thawing, and evaluate the impact of freezing on the two-phase fluid circuit. Wherein, the working temperature of the two-phase fluid circuit is the temperature of the liquid reservoir 4. During the test, the temperature of the liquid reservoir 4 is changed by changing the temperature of the evaporator 1 and the cooling plate 11. The liquid reservoir 4, the control valve 5, the liquid The temperature-controlled heaters on pipeline 6 and steam pipeline 2 are only used for thawing the components in the two-phase fluid circuit. Since the working fluid in the two-phase fluid circuit is ammonia, its condensation point is -77°C, which is used for testing freezing. The effect of working conditions on the heat transfer performance of the two-phase fluid circuit, first test the limit heat transfer capacity of the two-phase fluid circuit under low temperature conditions (-60 ° C ~ -70 ° C), and then reduce the temperature of the two-phase fluid circuit to -77 Below ℃, let it freeze, observe the freezing process of the two-phase fluid circuit, then unfreeze the two-phase fluid circuit, and measure the ultimate heat transfer capacity of the two-phase fluid circuit after thawing under low temperature conditions, and work the same as before freezing Compare the limit heat transfer capacity at different temperatures to check the effect of freezing on the heat transfer capacity of the two-phase fluid circuit. The specific implementation steps are as follows:

Step 1, put the circuit bracket 17 into the vacuum chamber 10, vacuumize (the degree of vacuum is less than 2×10 ^-3 Pa), and set the control valves on the liquid reservoir 4, control valve 5, liquid pipeline 6 and steam pipeline 2. The temperature heater is in a self-control state, and the self-control threshold is -70°C, that is, when the temperature is lower than the self-control threshold, the temperature-control heater is automatically turned on. Set the self-control threshold of the heat sink heater to -70°C.

Step 2, pass liquid nitrogen to the heat sink of the vacuum chamber, reduce the temperature of the vacuum chamber to -150°C, because the steam pipeline 2, the liquid reservoir 4, the control valve 5 and the liquid pipeline 6 of the two-phase fluid circuit are separated by multiple layers The cooling rate of the thermal component is slow, and the cooling rate of the cooling plate is the fastest. In order to increase the cooling rate of the components of the two-phase fluid circuit, during the cooling process, the simulated heat source 15 is turned on to make the two-phase fluid circuit run. The condensing pipeline drives the evaporator and liquid receiver to cool down, and speeds up the cooling rate of the evaporator until the temperature of the liquid receiver drops to -60°C. When the temperature of the liquid receiver remains unchanged for half an hour or the monotonous change is less than 1°C /h, the working condition is considered to be balanced. The temperature of the reservoir is the operating temperature of the two-phase fluid circuit.

Step 3, limit heat transfer capacity test: maintain the temperature of the liquid reservoir at -60°C, increase the heating power of the evaporator (that is, the heating power of the simulated heat source) according to a certain step size, and increase the heating power of the simulated heat source each time Simultaneously reduce the heating power of the radiator heater, so that the temperature of the liquid reservoir is maintained at -60°C and the two-phase fluid circuit is balanced, until the heating power of the radiator heater is zero or the temperature of the evaporator suddenly rises This makes it impossible to maintain the balance of working conditions. When the heating power of the radiator plate is 0, the radiator plate reaches the maximum heat dissipation capacity at this working temperature, and the continuous increase of the heating power of the evaporator will cause the temperature of the liquid reservoir to rise, which cannot continue to be maintained at -60°C. When the heating power of the evaporator is greater than the limit heat transfer capacity of the two-phase fluid circuit, the liquid in the evaporator is burned dry, causing the temperature of the evaporator to rise suddenly. Therefore, when the heating power of the radiator plate heater is zero or the heating power of the evaporator at the equilibrium moment before the temperature of the evaporator suddenly rises is the limit heat transfer capacity of the two-phase fluid circuit at the working temperature.

Step 4. By reducing the power of the evaporator and increasing the power of the radiator plate, the temperature of the liquid reservoir is changed to -70°C. According to the method of step 3, the limit heat transfer capacity of the two-phase fluid circuit at the working temperature of -70°C is obtained. .

Step 5, freeze:

Turn off the heat sink heater and the simulated heat source heater, wait for the temperature of each measuring point to drop below -90°C, and maintain it for more than 2 hours, so that the two-phase fluid circuit is fully frozen. By observing the temperature of each measuring point, it can be seen that the freezing order of the components of the two-phase fluid circuit is: condensate pipeline → liquid reservoir → liquid pipeline inlet → liquid reservoir outlet → valve → evaporator (due to the ammonia in the steam pipeline It is gaseous and will not freeze). Due to the different heat dissipation rates of each component, the sequence of freezing of each component is: condensing pipeline→liquid pipeline inlet→liquid reservoir→liquid reservoir outlet→valve→evaporator.

Step 6, unfreeze:

When the solid working medium is locally heated and turned into a liquid, heating the liquid will cause expansion and pressure rise, which will cause the pipeline to rupture or burst. Since the working medium in the condensation pipeline flows into the liquid receiver, there is less working medium in it. , so first defrost the condensing pipeline, increase the heating power of the radiator plate, so that the temperature of the condensing pipeline rises above the freezing point of the working fluid, and the liquid receiver, liquid pipeline, and valves are controlled by the temperature control temperature of the temperature control heater. Thawing, the power of thawing is controlled, and the temperature of each component is required to be evenly raised until the freezing point of the working fluid is above the freezing point, and the thawing is over.

Step 7, repeat step 3 and step 4, test the limit heat transfer capacity of the two-phase fluid circuit at the operating temperature of -60°C and -70°C, and compare it with the limit heat transfer capacity of step 3 and step 4 at the corresponding operating temperature , if the deviation of heat transfer capacity is less than 10%, it means that the heat transfer performance of the two-phase fluid circuit will not be affected after freezing failure and thawing. If the heat transfer capacity deviation is greater than 10%, it indicates that the freezing failure and thawing process has certain damage to the two-phase circuit.

To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (8)

1. A two-phase fluid circuit freezing failure test method, is characterized in that, comprises the steps: Step 1, design the test device: The test device comprises a cooling plate (11), a temperature control heater, a multi-layer heat insulation assembly, a temperature sensor, a simulated heat source (15) and a loop support (17); wherein, the cooling plate (11) is insulated by a thermal insulation pad Installed on the upper part of the circuit bracket (17); the condensation pipeline (3) of the two-phase fluid circuit is buried in the heat dissipation plate (11), and the liquid reservoir (4) of the two-phase fluid circuit is half buried in the heat dissipation plate (11) ; The evaporator (1) in the two-phase fluid circuit is thermally insulated and installed at the bottom of the circuit support (17); the temperature control heater is installed on the steam pipeline (2), liquid reservoir (4), control On the valve (5) and the liquid pipeline (6); the temperature sensor is installed on the evaporator (1), steam pipeline (2), condensate pipeline (3), liquid receiver (4), control Valve (5) and liquid pipeline (6), simulated heat source (15) and the edge area of heat dissipation plate (11); multi-layer heat insulation components are wrapped around steam pipeline (2), liquid reservoir (4), control valve (5) and on the liquid pipeline (6); the simulated heat source (15) is a RHU isotope electric simulated heat source, which is fixedly installed in the evaporator (1); the radiator plate heater that provides the working temperature for the radiator plate (11) is installed, The heat dissipation plate heater is an infrared heater (16) installed in the space outside the heat dissipation plate or a heating sheet pasted on the heat dissipation plate; Step 2, put the loop bracket (17) into the vacuum chamber (10), pump the vacuum to make the vacuum degree less than 2×10 ^-3 Pa, set the liquid reservoir (4), control valve (5), liquid pipeline ( 6) and the temperature control heater on the steam pipeline (2) is in a self-control state, and the self-control threshold is -70°C; set the self-control threshold of the heat sink heater to -70°C; Step 3, passing liquid nitrogen to the heat sink of the vacuum chamber (10), lowering the temperature of the vacuum chamber to -150°C; lowering the temperature of the liquid reservoir to -60°C, and reaching the equilibrium of the two-phase fluid circuit; The state equilibrium is that the temperature of the liquid reservoir remains unchanged for half an hour or the monotonous change is less than 1°C/h; the temperature of the liquid reservoir is the working temperature of the two-phase fluid circuit; Step 4, limit heat transfer capacity test: Turn on the simulated heat source, increase the heating power of the simulated heat source according to a certain step, and decrease the heating power of the radiator heater while increasing the heating power of the simulated heat source each time, so that the temperature of the liquid reservoir is maintained at T ₁ , -60 ℃≤T ₁ ≤-70℃, and reach the balance of the two-phase fluid circuit working condition, until the heating power of the radiator heater is zero or the working condition balance cannot be maintained due to the sudden rise of the temperature of the evaporator, the heating of the radiator heater When the power is zero or the heating power of the simulated heat source at the equilibrium moment before the temperature of the evaporator suddenly rises is the limit heat transfer capacity of the two _- phase fluid circuit at the working temperature of T1; Step 5, freeze: Turn off the heat sink heater and the simulated heat source heater, wait for the temperature of each measuring point to drop below -90°C, and maintain it for a period of time to fully freeze the two-phase fluid circuit; Step 6, unfreeze: First turn on and increase the heating power of the radiator plate to raise the temperature of the condensing pipeline to above the freezing point of the working medium, then turn on the liquid receiver, liquid pipeline, control valve, temperature-controlled heater and simulated heat source of the steam pipeline, so that The temperature of the liquid receiver, liquid pipeline, control valve, steam pipeline and evaporator is evenly raised to above the freezing point of the working medium; Step 7, maintain the temperature of the liquid reservoir at T ₁ , obtain the limit heat transfer capacity of the two-phase fluid circuit after thawing at the working temperature T ₁ according to the method in step 4, and obtain the limit heat transfer capacity at the same working temperature obtained in step 3 If the deviation of heat transfer capacity is less than 10%, it means that the heat transfer performance of the two-phase fluid circuit will not be affected after freezing failure and thawing; damage. 2. two-phase fluid circuit freezing failure test method as claimed in claim 1, is characterized in that, in step 3, measure the limit heat transfer capacity of the two-phase fluid circuit of a plurality of low temperature operating temperatures, measure corresponding in step 7 The limit heat transfer capacity of the two-phase fluid circuit at the low temperature working temperature, calculate the limit heat transfer capacity deviation of the two-phase fluid circuit at the same working temperature before and after freezing, where the low temperature working temperature is -60℃～-70℃. 3. the two-phase fluid circuit freezing failure test method as claimed in claim 1 or 2, is characterized in that, in the cooling process of described step 3, open simulation heat source (15), make two-phase fluid circuit operation, quicken evaporator (1) The cooling rate. 4. two-phase fluid circuit freezing failure test method as claimed in claim 1, is characterized in that, the base plate of described heat dissipation plate (11) is aluminum plate or honeycomb plate, and the surface of heat dissipation plate (11) is pasted with OSR sheet or spraying High emissivity coating. 5. two-phase fluid circuit freezing failure test method as claimed in claim 1, is characterized in that, the installation position of described temperature sensor is: At least two temperature sensors are respectively arranged along the height direction on the four fins of the evaporator (1), one of which is located at the lower end of the evaporator fin, and one is located at the upper end of the evaporator fin; A temperature sensor is respectively arranged at the inlet, top and outlet of the steam pipeline (2); One temperature sensor is arranged at the inlet and outlet of the condensation pipeline (3), and at least one temperature sensor is arranged on the fin of the condensation pipeline (3); Three temperature sensors are arranged along the height direction on the outer surface of the liquid reservoir (4), respectively located in the gas space, gas-liquid interface and liquid space of the liquid reservoir (4); At least one temperature sensor is arranged on the liquid pipeline connecting the liquid reservoir (4) and the control valve (5), and at least one temperature sensor is arranged on the liquid pipeline connecting the control valve (5) and the evaporator (1); A temperature sensor is arranged on the control valve (5); At least one temperature sensor is arranged on the simulated heat source (15); At least one temperature sensor is arranged on the edge area of the inner surface of the cooling plate (11). 6. The two-phase fluid circuit freezing failure test method according to claim 1, wherein the temperature-controlled heater is a heating sheet, a heating wire, a heating belt or a heating plate. 7. two-phase fluid circuit freezing failure test method as claimed in claim 1, is characterized in that, described evaporator (1) is installed on the insulation board (12), and simulated heat source (15) is placed on evaporator (1 ), the lugs of the simulation heat source (15) tooling are fixed on the heat insulation board (12) by screws and heat insulation pads (13), and the heat insulation board (12) is fixed by 4 heat insulation columns (14) Install on the loop support (17). 8. two-phase fluid circuit freezing failure test method as claimed in claim 7, is characterized in that, described insulation board (12), heat insulation pad (13) and heat insulation column (14) material are glass fiber reinforced plastics or polyamide imine.