WO2016086495A1

WO2016086495A1 - Gravity-driven two-phase fluid loop

Info

Publication number: WO2016086495A1
Application number: PCT/CN2015/000301
Authority: WO
Inventors: 苗建印; 邵兴国; 吕魏; 张红星
Original assignee: 北京空间飞行器总体设计部; 苗建印; 邵兴国; 吕魏; 张红星
Priority date: 2014-12-02
Filing date: 2015-05-04
Publication date: 2016-06-09

Abstract

Disclosed is a gravity-driven two-phase fluid loop, consisting of an evaporator (1), a vapour pipeline (2), a condenser (3), a liquid storage device (4), a liquid pipeline (6) and a control valve (5), wherein the gravity formed by the altitude difference between the liquid storage device (4) and the evaporator (1) is used as a driving force; an isotopic nuclear heat source is used as a heat source; the heat is transferred by way of the gas-liquid transformation of a gas-liquid two-phase working medium filled into the loop; and the condenser (3) is arranged to be V-shaped, such that the liquid working medium in the liquid storage device (4) can be prevented from flowing back into the condenser (3) due to the lunar surface inclination.

Description

Gravity driven two-phase fluid circuit

The invention relates to the technical field of spacecraft thermal control, and in particular to a gravity driven two-phase fluid circuit. Background technique

The temperature difference between day and night on the surface of the celestial body is very large, and the high and low temperature lasts for a long time. For example, the moon has a long lunar day (about 27.3 Earth days). During the moon and night, because there is no atmosphere on the moon and the thermal conductivity of the moon is small, the surface temperature of the moon is very fast. Reduce it to around -180 °C. The celestial body detector needs to survive at night in a long-term low temperature environment (such as the 340 hours of continuous low temperature of the moon) in an environment without solar energy (source of heat and electricity). Among the successfully launched celestial detectors, the celestial spacecraft experiencing the low temperature of the moon and night are mainly the US "Surveyor" series, the "Apollo" series and the Soviet "Lunokhod". "Series. Among them, the "Reviewer" series uses batteries as a heat source, and the heat transfer from the cabin equipment to the radiant panel is automatically controlled by a semi-active mechanical thermal switch. This solution requires a larger weight of the battery to meet the heater length of 340. The hourly power supply requirement; "Apollo 11" uses a 30W isotope as a heat source, and the isotope is mounted on the detector to directly transfer heat to the device. In this scheme, the isotope heat source has less heat and most of its heat is in the month. Both 昼 and moonlight are passed to the equipment, which solves the problem of moonlight insulation and brings about the high temperature problem of the moonlight. "Apollo 12, 14-17" mainly uses electric energy converted from isothermal energy of the isotope source as a heat source. At the same time, it solves the problem of power supply during the day and night and the heating problem during the moon and night. The electricity is heated by the moon and night, and the heat is converted into electric energy through the process. The process of converting electrical energy into thermal energy. Due to the thermoelectric conversion efficiency limitation of the thermoelectric battery, the thermal power demand for the nuclear source reaches 1480W, and the design cost is high; the "Lunar Rover" series uses the isotope nuclear heat source as the heat source and utilizes the active circuit. The continuous operation of the system transfers heat to the inside of the detector, and the active loop system is powered by a large-capacity battery. The design scheme of the moon and night insulation is complicated, and the active loop system needs to work continuously with low reliability. At the same time, the battery needs to be 340 hours. Active circuit during the moon and night System power supply, making the weight of the system increase

In view of the above, the present invention provides a gravity driven two-phase fluid circuit that can be used for spacecraft night warming, and that is lightweight and highly reliable.

The gravity driven two-phase fluid circuit of the present invention comprises an evaporator, a vapor line, a condenser, a liquid reservoir, a liquid line and a control valve; wherein the condenser is located above the gravity field of the liquid storage device and is required to be insulated Coupling; the evaporator is located below the gravity field of the accumulator and is coupled to the isotope heat source; the accumulator is connected to the evaporator inlet through the liquid line, and a control valve is arranged on the liquid line; the evaporator outlet passes through the steam tube in sequence The pipeline and the condenser are connected to the accumulator to form a closed pipeline system; wherein the condenser is composed of a condensation pipeline and a condensation fin, the condensation pipeline is a V-shaped tube on the inlet side of the condensation pipeline The road is parallel to the lunar surface. The line on the outlet side of the condensing line is on the same vertical surface as the outlet line, and is located below the inlet line and at an angle of 15° to the inlet line. The inside of the circuit is filled at -70° ( : ~ Working medium in the gas-liquid two-phase state within the range of 120 °C.

Further, the evaporator includes four screen evaporators, a vapor combiner, and a liquid splitter, wherein the screen evaporator is composed of an evaporator housing and a heat collecting seat that is sleeved on the evaporator housing, The collector seat and the isotope nuclear heat source are thermally conductively mounted, the inner circumferential wall surface of the evaporator casing is provided with a thread groove, and the sintered stainless steel wire mesh is set inside the casing as a capillary core; the inlet of the wire mesh evaporator is connected with the liquid flow divider, the wire mesh The outlet of the evaporator is connected to the vapor manifold; the liquid splitter is connected to the liquid line, and the vapor combiner is connected to the vapor line.

Further, the vapor manifold is a 1/4 open annular structure, and the liquid splitter has a ring structure.

Further, one end of the vapor line near the condenser is an inverted U-shaped, inverted U-shaped vapor line The bottom is higher than the inlet of the condenser.

Further, the control valve is a solenoid valve, and the sealing specific pressure is 4.51 MPa, and the pressure difference between the sealing surfaces of the control valve is 0.2 MPa.

Further, the working fluid is ammonia.

Further, the method for calculating the filling amount of the working medium is: using the mass=density* volume, the working mass quality calculation equation of the highest and lowest storage temperatures, and obtaining the volume of the accumulator and the filling amount of the working medium; At the highest storage temperature, the liquid filling rate in the reservoir is 100%, and the outer circuit is gas; at the lowest storage temperature, the outer circuit is filled with liquid, and the liquid storage medium contains 10% by volume of liquid working medium; The outer circuit consists of the remainder of the fluid circuit that removes the reservoir, the volume of which is known.

Beneficial effects:

(1) The present invention has a simple structure, is light in weight, does not require an additional driving force, and can be applied to a spacecraft for nighttime insulation and has high reliability.

(2) Coupling with a plurality of parallel screen evaporators on the surface of the heat source, these screen evaporators can be evenly arranged on the surface of the heat source to make the temperature of the heat source more uniform; and the screen evaporator has a capillary structure for absorbing liquid shunts The liquid working medium reduces the superheat of the evaporator and can transfer more heat.

(3) The vapor manifold is designed as a 1/4-open annular structure, which can better adapt to the thermal expansion and contraction of the evaporator due to the temperature change of the isotope source (changed between 110~240 °C). Thermal Stress.

(4) Set the vapor line to an inverted U shape to prevent the liquid working fluid in the condenser from flowing back into the vapor line.

(5) The condensing line is designed to be V-shaped, so that the liquid working medium in the reservoir can be prevented from flowing back into the condenser when the lunar slope is not more than 15°.

(6) The solenoid valve can effectively realize multiple opening and closing of the fluid circuit, and realize the heat transfer of the moon shackle. The function of transferring heat on the moon night. The solenoid valve with a sealing specific pressure of 4.51Mpa and a pressure difference of 0.2MPa on the sealing surface of the control valve can meet the sealing reliability of the control valve and can withstand the axial acceleration of the detector in the launching section and the power lowering section. The sealing reliability of the control valve during the flight of the detector. DRAWINGS

Figure 1 is a schematic view of the structure of the present invention.

Figure 2 is a schematic view of the structure of the evaporator.

Figure 3 is a schematic view of the structure of the screen evaporator.

Figure 4 is a schematic view of the structure of the condenser.

Figure 5 is a schematic view of the structure of the accumulator.

Figure 6 is a schematic view of the structure of the control valve.

Of which, 1-evaporator, 2-vapor line, 3-condenser, 4-reservoir, 5-control valve, 6-liquid line, 7-wire evaporator, 8-liquid splitter, 9- Steam manifold, 10-filled pipe, 11-three-way, 12-two-way, 13-four-way, 14-evaporator housing, 15-collector, 16-condensing line, 17-condensing fin. detailed description

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

The present invention provides a gravity driven two-phase fluid circuit, as shown in FIG. 1, including an evaporator 1 (including a wire mesh evaporator 7, a liquid flow divider 8 and a vapor manifold 9), a vapor line 2, and a condenser 3 a reservoir 4, a liquid line 6 and a control valve 5, wherein the condenser 3 is located above the gravity field of the accumulator 4 and coupled to a device (heat sink) requiring heat preservation, the evaporator 1 is located at the accumulator 4 gravity Below the field, coupled with an isotope heat source, a gravity driven height difference is formed between the liquid level in the reservoir 4 and the bottom of the evaporator 1; the reservoir 4 is connected to the inlet of the evaporator 1 through the liquid line 6, in the liquid tube There is a control room 5 on the road 6. The outlet of the evaporator 1 is connected to the accumulator 4 through the vapor line 2 and the condenser 3 in sequence to form a closed piping system. The inside of the circuit is filled with a working fluid in a gas-liquid two-phase state, such as ammonia, in the range of -70 ° C to 120 ° C, and the heat transfer is performed by using the gas-liquid phase change. During the moonlight night, the control valve 5 is opened. Due to the certain height difference between the reservoir 4 and the bottom of the evaporator 1, the liquid ammonia working fluid in the accumulator 4 flows into the evaporator 1 along the liquid line 6 under the driving of gravity. The ammonia working fluid in the evaporator 1 absorbs the heat of the isotope heat source and is transformed into a gas. The gaseous ammonia working fluid flows along the vapor line 2 to the condenser 3 to condense into a liquid, and transfers the heat to the lunar surface detector device. The condensed liquid ammonia working fluid flows into the accumulator 4 to form a heat conduction loop for keeping the celestial detector warm. During the lunar period, it is necessary to block the transfer of heat. At this time, the control valve 5 is closed, and the gravity-driven two-phase fluid circuit stops running. At this time, the heat transfer between the isotope heat source and the inside of the detector is conducted through the heat conduction of the vapor line. The heat is small to achieve thermal isolation, at which point the heat of the isotope nuclear heat source is dissipated outward by its own thermal radiation.

The structure of the evaporator 1 is as shown in FIG. 2, and includes four wire mesh evaporators 7, a vapor manifold 9, a liquid flow divider 8, a liquid filling pipe 10, and a joint (two-way, three-way, four-way), and wire. The structure of the net evaporator 7 is as shown in FIG. 3, and is composed of an evaporator casing 14 and a heat collecting seat 15. The evaporator casing 14 is installed inside the heat collecting seat 15, and the heat collecting seat 15 is thermally connected to the isotope heat source to evaporate. The inner circumferential wall surface of the casing 14 is provided with a threaded groove, and the interior of the evaporator casing 14 is provided with a sintered stainless steel wire mesh as a capillary core. The vapor manifold 9 is a 1/4-open circular ring. As shown in Fig. 2, it consists of two two-way 12, one three-way 11, one four-way 13 and three elbows. There are four steam inlets. And a vapor outlet, wherein the four vapor inlets are respectively connected to the outlets of the four screen evaporators, and the vapor outlets are connected to the vapor line 2. At the same time, the vapor manifold 9 is also provided with a liquid filling tube 10 of a two-phase fluid circuit. The liquid diverter is annular and consists of three tees 11, one four-way 13 and four elbows, one liquid inlet and four liquid outlets, wherein the liquid inlet is connected to the liquid line 6, 4 The liquid outlets are respectively connected to the inlets of the four screen evaporators 7. Wherein, the material of the evaporator casing 14, the liquid filling pipe 10 and the joint is 00Crl7Nil4Mo2, and the material of the heat collecting seat is 3A21 aluminum. The liquid ammonia working fluid in the liquid storage device 4 flows into the liquid flow divider 8 through the liquid pipeline 6, and flows into the screen evaporator 7 by gravity to absorb the heat of the isotope nuclear heat source into a gaseous state, and the gaseous ammonia working fluid passes through the vapor. The combiner 9 merges and flows into the vapor line 2.

The material of the steam line 2 is 00Crl7Nil4Mo2, in order to avoid the liquid working medium in the condenser 3 and the accumulator 4 flowing back into the evaporator 1 due to the position of the accumulator 4 being higher than the evaporator 1 during the lunar period, the evaporator 1 The liquid working medium is turned into a vapor and sent back to the condenser line 5, so that the detector device is still in a heating state. The present invention sets the vapor line 2 close to the condenser 3 end to an inverted U shape, thereby The bottom of the inverted U-shaped vapor line 2 is made higher than the condenser 3 and the accumulator 4, and the reflux of the liquid working medium is suppressed.

The condenser 3 is composed of a condensing line 16 and a condensing fin 17, as shown in Figure 4, the material of the condensing line 16 is 00Crl 7Nil4Mo2, and the material of the condensing fin 17 is 3A21 aluminum. In order to avoid that the height of the reservoir due to the inclination of the lunar surface is greater than the height of the condenser, so that the liquid working medium in the accumulator flows into the condenser, causing adverse effects, the present invention designs the condensing line to be V-shaped, wherein, the condensation The pipeline on the inlet side of the pipeline is parallel to the lunar surface, and the pipeline on the outlet side of the condensing pipeline is located below the gravity field of the inlet pipeline and at an angle of 15° to the inlet pipeline, thereby avoiding the inclination of the lunar surface by 15 degrees. The liquid working fluid in the reservoir does not flow back into the condenser.

The control valve 5 is a solenoid valve, and its structure is shown in FIG. 6. The material of the control valve housing is 00Crl 7Nil4Mo2 stainless steel, and the sealing portion is made of rubber. The utility model utilizes the permanent magnet suction force and the medium pressure to act on the sealing surface to generate the sealing specific pressure. In the present invention, the sealing specific pressure of 4.51 MPa is adopted, and the rubber soft sealing structure can ensure the Ι.Οχ ΙΟ· ⁴ Pa-m ³ / s leak rate, meet the technical index internal leakage rate does not exceed 1.0xl (T ³ Pa rnVs requirements. In addition, the control valve 5 is also subjected to acceleration in the detector launch section and the power down section, between the liquid ammonia working fluid and the control valve sealing structure In the squeeze state, the control valve 5 is in a sealed state and will not be opened, thereby ensuring the reliability of the two-phase fluid circuit during the acceleration and deceleration of the detector. Meanwhile, the pressure formula according to the extrusion Ρ=/^ /ζ knows that when liquid ammonia has the highest density, maximum acceleration, and storage When the height difference between the liquid level of the liquid ammonia and the control valve sealing structure is the largest, the generated pressure is the largest. When the pressure difference between the sealing surface of the control valve is 0.2 MPa, it can withstand the influence of the pressure between the detector and the power-down section of the detector on the sealing structure due to the acceleration or deceleration of the ammonia and the sealing structure of the control valve.

The matching design of the accumulator 4 and the filling amount of the working fluid is related to the safety and heat transfer performance of the two-phase fluid circuit. The accumulator should be able to accommodate most of the working fluid in the circuit during the lunar period, thereby avoiding the liquid working. The volume expands when the temperature rises, causing the circuit to rupture, ensuring the safety of the entire fluid circuit. At the same time, when the fluid circuit is working, the liquid level of the working fluid in the reservoir should be as small as possible with the working temperature, so that the storage The gravity driving force corresponding to the height difference between the liquid level of the liquid level and the bottom of the evaporator 1 is as small as possible with temperature, which on the one hand can reduce the influence of the liquid level fluctuation on the stability of the circuit operation, and on the other hand, can ensure Provides sufficient driving force when the liquid level is lowest. The structure of the accumulator 4 is as shown in Fig. 5, which is a cylinder whose upper and lower end faces are ellipsoidal. In order to reduce the height change of the liquid level of the accumulator at different working temperatures, the accumulator satisfies the layout and weight. The inner diameter should be as large as possible if required.

Matching design between the filling amount of the working fluid and the volume of the accumulator: Using the mass = density 'volume, the equation for calculating the mass of the working medium at the highest and lowest storage temperatures, the volume of the accumulator and the filling amount of the working fluid are obtained; At the highest storage temperature, the liquid filling rate in the liquid reservoir is 100%, and the outer circuit is gas; at the lowest storage temperature, the outer circuit is filled with liquid, and the liquid storage medium contains a liquid working medium having a volume fraction of 10%; The outer circuit consists of the remainder of the fluid circuit that removes the reservoir, the volume of which is known.

The material of the liquid line 6 is 00Crl7Nil4Mo2 stainless steel.

In conclusion, the above is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims

Claim

1. A gravity driven two-phase fluid circuit, characterized in that it comprises an evaporator (1), a vapor line

(2), condenser (3), accumulator (4), liquid line (6) and control valve (5); wherein, condenser

(3) Located above the gravity field of the accumulator (4) and coupled to the equipment to be insulated; the evaporator (1) is located below the gravity field of the accumulator (4) and is coupled to the isotope heat source; the accumulator ( 4) Connect to the evaporator (1) inlet through the liquid line (6) and set the control valve (5) on the liquid line (6); the evaporator (1) outlet passes through the vapor line (2) in turn, The condenser (3) is connected to the accumulator (4) to form a closed piping system; wherein the condenser (3) is composed of a condensation line (16) and a condensation fin (17), the condensation tube The road (16) is V-shaped, the pipeline on the inlet side of the condensing pipeline is parallel to the lunar surface, and the pipeline on the outlet side of the condensing pipeline is on the same vertical plane as the outlet pipeline, and is located below the inlet pipeline and with the inlet The pipeline is at an angle of 15°; the inside of the circuit is filled with a working fluid in a gas-liquid two-phase state in the range of -70 ° C to 120 ° C.

2. A gravity driven two-phase fluid circuit according to claim 1, characterized in that said evaporator (1) comprises four wire mesh evaporators (7), a vapor manifold (9) and a liquid splitter (8). Wherein, the wire mesh evaporator (7) is composed of an evaporator casing (14) and a heat collecting seat (15) fitted on the evaporator casing, and the heat collecting seat (15) is thermally insulated from the isotope nuclear heat source. The inner side wall surface of the evaporator casing (14) is provided with a thread groove, and the inside of the casing is provided with a sintered stainless steel wire mesh as a capillary core; the inlet of the wire mesh evaporator (7) is connected with the liquid flow divider (8), the wire mesh The outlet of the evaporator (7) is connected to the vapor manifold (9); the liquid splitter (8) is connected to the liquid line (6), and the vapor manifold (9) is connected to the vapor line (2).

3. A gravity driven two-phase fluid circuit according to claim 2, wherein said vapor manifold (9) is a 1/4 open annular structure and said liquid flow divider (8) is annular.

4. The gravity driven two-phase fluid circuit according to claim 1, wherein one end of the vapor line (2) adjacent to the condenser (3) is inverted U-shaped, and the bottom of the U-shaped vapor line is inverted. Above the condenser (3) The entrance.

The gravity-driven two-phase fluid circuit according to claim 1, wherein the control valve (5) is a solenoid valve having a sealing specific pressure of 4.51 MPa and a pressure difference of 0.2 MPa on the sealing surface of the control valve.

6. The gravity driven two phase fluid circuit of claim 1 wherein said working fluid is ammonia.

7. The gravity driven two-phase fluid circuit according to claim 1, wherein the filling amount of the working fluid is calculated by: using mass=density* volume, and working medium quality at maximum and minimum storage temperatures. Calculate the equation to obtain the volume of the accumulator and the filling amount of the working fluid; wherein, at the highest storage temperature, the liquid filling rate in the accumulator is 100%, the outer loop is gas; at the lowest storage temperature, the outer loop is filled with liquid, 睹The liquid reservoir contains a liquid working medium having a volume fraction of 10%; wherein the outer circuit is composed of the remaining portion of the fluid circuit except the liquid storage device, and the volume thereof is known.