Heat dissipation subsystem and space nuclear Brayton power generation system

Abstract

The heat dissipation subsystem and space nuclear Brayton power generation system address the existing technical problem that existing space nuclear energy systems often use higher cooler temperatures to dissipate waste heat to reduce spaceflight costs and achieve a more compact surface energy system. However, this higher cooler temperature reduces the system's maximum output specific work. The present invention provides a technical solution: a heat dissipation subsystem, applied to a surface nuclear energy system, comprising a heat pump compressor, a heat exchanger, a radiator, and a cooler. The heat exchanger is used to transfer heat from the surface nuclear energy system to the radiator via the heat pump compressor. After passing through the radiator, the heat is cooled by the cooler before being transferred to the heat exchanger. This solution is suitable for use in the construction and research of space power generation systems.

Description

Technical Field

[0001] It involves the field of space nuclear power, and specifically space nuclear power generation. Background Art

[0002] With the advancement of deep space exploration, the design of energy systems for permanent bases on the surface of the moon has attracted significant interest from space researchers worldwide. Taking the lunar base as an example, a permanent base on the surface of the moon must meet technical requirements such as high energy density, high reliability, and a long life cycle. Furthermore, given the high launch and transportation costs of space missions, the energy system designed for the base must meet these technical requirements while minimizing weight and operating costs and achieving the highest possible compactness. Space nuclear energy systems offer high energy density, strong stability, and a long life cycle, making them promising for application in energy systems for bases on the surface of the moon. Based on the technical characteristics of thermoelectric conversion, the conversion mode can be categorized as static or dynamic, depending on whether a work element is present or absent. Due to the technical limitations of static conversion and its low energy conversion efficiency, its application in base power supply requires further exploration. Dynamic conversion, including the Rankine cycle, Brayton cycle, and Stirling cycle, offers high conversion efficiencies exceeding 20%, offering significant advantages in the design of energy systems for bases on the surface of the moon under demanding conditions.

[0003] Due to the problem of alkali metal two-phase flow in the alkali metal Rankine cycle, there are certain safety risks during operation. Therefore, further research is needed in its application in weak gravity fields. Due to its inherent structural characteristics, the Stirling cycle is difficult to output high power. Therefore, further optimization is needed in the application of stellar energy systems. The Brayton cycle has high thermal efficiency and does not have technical characteristics such as two-phase flow instability. Therefore, it has considerable application prospects in the application of stellar energy bases with large energy demands. In the traditional space Brayton cycle, a nuclear reactor, a turbine, a radiation cooler and a compressor are included.

[0004] Unlike the terrestrial Brayton system, the waste heat of the space Brayton system is removed through radiant radiators. The unit radiation heat transfer capacity in space is as follows:

[0005]

[0006] Where ε is the material emissivity, σ is the radiation constant, T1 is the temperature of the radiation panel, and T0 is the space temperature. In space, especially on a star without an atmosphere, the space temperature can be considered a constant of 4K.

[0007] From the above formula, it can be concluded that the waste heat removal capacity of the spatial Brayton system is positively correlated with the temperature of the radiation plate. The higher the temperature of the radiation plate, the stronger the waste heat removal capacity. Under the condition of a certain total amount of waste heat, the higher the temperature of the radiation heat sink, the smaller the required heat exchange area. However, the temperature of the radiation radiator will also affect the thermal performance of the spatial Brayton system. Under the condition of a fixed heat source, taking the helium-xenon working fluid with a pressure below 2 MPa as an example, the system output specific work is obtained under the following design conditions:

[0008]

[0009]

[0010] Where π is the turbocharger ratio, and τ is the cycle pressure ratio. Combining the above two equations, we can conclude that the lower the cooler temperature of the Brayton cycle, the higher the system's output specific work. However, existing space nuclear energy systems often use higher cooler temperatures to dissipate waste heat to reduce spaceflight costs and achieve a more compact surface energy system. However, higher cooler temperatures reduce the system's maximum output specific work. Summary of the Invention

[0011] To solve the problem in the prior art that existing space nuclear energy systems often use higher cooler temperatures to discharge waste heat in order to reduce aerospace costs and achieve a higher compactness of the satellite energy system, but the higher cooler temperature reduces the maximum output specific work of the system, the present invention provides the following technical solutions:

[0012] The heat dissipation subsystem is applied to the star surface nuclear energy system, and the subsystem includes:

[0013] Heat pump compressors, heat exchangers, radiators and desuperheaters;

[0014] The heat exchanger is used to transfer the heat in the satellite nuclear energy system to the radiator through the heat pump compressor. After passing through the radiator, the heat is cooled by the cooler and then transferred to the heat exchanger.

[0015] Furthermore, a preferred embodiment is provided, wherein the heat sink is a radiation heat sink.

[0016] Furthermore, a preferred embodiment is provided, wherein the radiant heat sink is a heat pipe radiant heat sink.

[0017] Furthermore, a preferred embodiment is provided, wherein the radiant heat sink is a droplet radiant heat sink.

[0018] Furthermore, a preferred embodiment is provided, wherein the cooler is a heat pump turbine.

[0019] Furthermore, a preferred embodiment is provided, in which the working fluid for transferring heat in the subsystem is helium-xenon, supercritical carbon dioxide or helium.

[0020] Furthermore, a preferred embodiment is provided, characterized in that the cooler is a throttle valve.

[0021] Furthermore, a preferred embodiment is provided, characterized in that, in the system, the working fluid used for transferring heat is benzene, ethane or water.

[0022] Based on the same inventive concept, the present invention also provides a space nuclear Brayton power generation system.

[0023] The system includes a heat dissipation subsystem and a Brayton thermoelectric conversion subsystem;

[0024] The Brayton thermoelectric conversion subsystem is used to exchange waste heat generated by the space nuclear reactor;

[0025] The heat dissipation subsystem is the heat dissipation subsystem for discharging the waste heat;

[0026] The heat pump compressor is coaxial with the Brayton compressor and the Brayton turbine in the Brayton thermoelectric conversion subsystem and is used to drive a generator.

[0027] Furthermore, a preferred embodiment is provided, in which, in the heat dissipation subsystem, the cooler is a heat pump turbine, the heat pump turbine is coaxial with the heat pump compressor, and is used to drive a generator.

[0028] Compared with the prior art, the technical solution provided by the present invention is beneficial in that:

[0029] The space nuclear Brayton power generation system provided by the present invention couples the nuclear Brayton thermoelectric conversion system with the heat pump circulation and heat dissipation subsystem to form a multi-machine integrated space nuclear Brayton power generation system. The low-temperature waste heat of the nuclear Brayton thermoelectric conversion system is transported to the radiant radiator by the heat pump system, thereby reducing the radiation area of ​​the radiant radiator, increasing the specific mass output work of the space nuclear Brayton power generation system, and improving the compactness of the surface nuclear Brayton system.

[0030] The space nuclear Brayton power generation system provided by the present invention proposes two different types of heat pump systems, namely the heat pump cooling system based on the reverse Brayton cycle and the heat pump cooling system based on the reverse Rankine cycle, which can be flexibly selected according to different aerospace needs.

[0031] The space nuclear Brayton power generation system provided by the present invention has strong scalability. The functions of the multi-machine-in-one space nuclear Brayton power generation system are independent of the selection of working fluids of each subsystem. Therefore, it can be designed in combination with the resource characteristics of different star catalogs, and has broad application and development prospects in space missions.

[0032] The space nuclear Brayton power generation system provided by the present invention overcomes the shortcomings of space nuclear Brayton system technology and proposes a design scheme that can ensure a smaller heat dissipation area of ​​the space nuclear Brayton system while improving the output specific work capacity of the energy system; by introducing a heat pump reverse thermodynamic cycle, this design solves to a certain extent the contradiction between the work demand of the space nuclear Brayton system and the system heat dissipation area, and realizes a highly compact satellite surface nuclear energy system design.

[0033] It is suitable for use in the construction and research of space power generation systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a system schematic diagram of the space nuclear Brayton power generation system mentioned in Implementation Method 9;

[0035] Figure 2 This is the system principle diagram of the space nuclear energy Brayton power generation system mentioned in the ninth implementation method.

[0036] Among them, 1-8 are state nodes, 9 is the space nuclear reactor, 10 is the heater, 11 is the Brayton compressor, 12 is the Brayton turbine, 13 is the heat exchanger, 14 is the heat pump compressor, 15 is the radiation radiator, 16 is the heat pump turbine, 17 is the throttle valve, 18 is the main shaft, 19 is the gearbox, and 20 is the generator. DETAILED DESCRIPTION

[0037] In order to make the advantages and benefits of the technical solution provided by the present invention more clearly reflected, the technical solution provided by the present invention is now further described in detail with reference to the accompanying drawings, specifically:

[0038] Embodiment 1: This embodiment provides a heat dissipation subsystem, which is applied to a star-surface nuclear energy system. The subsystem includes:

[0039] Heat pump compressor 14, heat exchanger 13, radiator and cooler;

[0040] The heat exchanger 13 is used to transfer the heat in the satellite nuclear energy system to the radiator through the heat pump compressor 14. After passing through the radiator, the heat is cooled by the cooler and then transferred to the heat exchanger 13.

[0041] Embodiment 2: This embodiment further limits the heat dissipation subsystem provided in Embodiment 1, and the heat sink is a radiation heat sink 15 .

[0042] Embodiment 3: This embodiment further limits the heat dissipation subsystem provided in Embodiment 2, and the radiation radiator 15 is a heat pipe radiation radiator.

[0043] Embodiment 4: This embodiment further limits the heat dissipation subsystem provided in Embodiment 2, and the radiation heat sink 15 is a droplet radiation heat sink.

[0044] Embodiment 5: This embodiment further limits the heat dissipation subsystem provided in Embodiment 1, and the cooler is a heat pump turbine 16 .

[0045] Implementation 6: This implementation further limits the heat dissipation subsystem provided in Implementation 5. In the subsystem, the working fluid for transferring heat is helium-xenon, supercritical carbon dioxide, or helium.

[0046] Embodiment 7: This embodiment further limits the heat dissipation subsystem provided in Embodiment 1, and the temperature reducer is a throttle valve 17 .

[0047] Embodiment 8: This embodiment further limits the heat dissipation subsystem provided in embodiment 7. In the system, the working fluid for transferring heat is benzene, ethane or water.

[0048] Implementation Method 9: Combination Figure 1 and 2 This embodiment describes a space nuclear Brayton power generation system.

[0049] The system includes a heat dissipation subsystem and a Brayton thermoelectric conversion subsystem;

[0050] The Brayton thermoelectric conversion subsystem is used to exchange waste heat generated by the space nuclear reactor 9;

[0051] The heat dissipation subsystem is the heat dissipation subsystem provided in embodiment 1, and is used to discharge the waste heat;

[0052] The heat pump compressor 14 is coaxial with the Brayton compressor 11 and the Brayton turbine 12 in the Brayton thermoelectric conversion subsystem and is used to drive the generator 20 .

[0053] Specifically:

[0054] This embodiment is achieved through the following technical solutions:

[0055] Combine Figure 1 and Figure 2 .

[0056] The system includes: nuclear energy Brayton thermoelectric conversion subsystem and heat pump circulation heat dissipation subsystem, namely heat dissipation subsystem;

[0057] The Brayton thermoelectric conversion subsystem includes: a space nuclear reactor 9, a Brayton turbine 12, a heat exchanger 13, a Brayton compressor 11, and pipes connecting the various components.

[0058] According to existing research, the working fluid of the Brayton thermoelectric conversion subsystem can be a helium-xenon gas mixture, supercritical carbon dioxide, and other working fluids suitable for space Brayton thermoelectric systems. In the Brayton thermoelectric conversion system, the high-pressure working fluid is heated at a constant pressure by the nuclear reactor, reaching state point 1. The high-temperature and high-pressure working fluid undergoes isentropic expansion and performs work in the Brayton turbine 12, reaching a low-pressure and medium-temperature state point 2. The low-pressure and medium-temperature working fluid is subjected to constant pressure in the heat exchanger 13 to remove waste heat, reaching a low-temperature and low-pressure state point 3. The low-temperature and low-pressure working fluid enters the Brayton compressor 11 for compression, reaching a medium-temperature and high-pressure state point 4. The working fluid in the medium-temperature and high-pressure state is then heated at a constant pressure by the nuclear reactor, reaching state point 1 and completing a thermodynamic cycle.

[0059] The heat pump circulation cooling subsystem includes two types: Figure 1 Heat pump cooling system based on reverse Brayton cycle and Figure 2 Heat pump cooling system based on reverse Rankine cycle.

[0060] The heat pump cooling system based on the reverse Brayton cycle is as follows Figure 1 This type of subsystem consists of a heat exchanger 13, a heat pump compressor 14, a radiator 15, a heat pump turbine 16, and pipes connecting the various components.

[0061] Figure 1 The radiation heat exchanger 13 described in the figure can be a heat pipe radiator or a droplet radiation radiator 15.

[0062] Figure 1 The working fluid of the heat pump circulation subsystem (reverse Brayton) can be helium-xenon, supercritical carbon dioxide, helium, or other working fluids suitable for reverse Brayton thermal systems. In this system, the low-temperature, low-pressure working fluid absorbs waste heat removed by the Brayton thermoelectric conversion subsystem at a constant pressure in heat exchanger 13, reaching state 5. The working fluid, having absorbed heat and heated up, is adiabatically compressed in heat pump compressor 14, reaching state 6. The high-temperature, high-pressure working fluid discharges heat to outer space through radiant heat sink 15, reaching state 7. The cooled high-pressure working fluid is discharged into heat pump turbine 16, where it expands and performs work, reaching state 8. The low-temperature, low-pressure working fluid absorbs heat again in heat exchanger 13, reaching state 5, completing a cycle.

[0063] In the space nuclear Brayton power generation system composed of the nuclear Brayton thermoelectric conversion subsystem and the heat pump circulation heat dissipation subsystem (reverse Brayton), the Brayton compressor 11, Brayton turbine 12, heat pump compressor 14, heat pump turbine 16 and generator 20 are integrated into a set of rotating shafts by a set of gearboxes 19 and supply power to the external system.

[0064] The heat pump cooling system based on the reverse Rankine cycle is as follows Figure 2 This type of subsystem consists of a heat exchanger 13, a heat pump compressor 14, a radiant radiator 15, a throttle valve 17, and pipes connecting the various components.

[0065] Figure 2 The radiation heat exchanger 13 described in the figure can be a heat pipe radiator or a droplet radiation radiator 15.

[0066] Figure 2 The working fluid of the heat pump circulation subsystem (reverse Rankine) can be benzene, ethane, water, or other working fluids suitable for reverse Rankine thermodynamic systems. In this system, the low-temperature, low-pressure wet saturated steam working fluid absorbs waste heat removed by the Brayton thermoelectric conversion subsystem at a constant pressure in heat exchanger 13, reaching a saturated state 5. The dry saturated working fluid is adiabatically compressed in heat pump compressor 14, reaching a superheated state point 6. The high-temperature, high-pressure superheated working fluid vapor passes through radiator 15 at a constant pressure to discharge heat into outer space, and ultimately reaches a saturated liquid phase state 7 at the corresponding pressure at the outlet of radiator 15. The saturated liquid phase working fluid enters throttle valve 17, where it is cooled and reduced in pressure to a wet saturated steam state 8. The low-temperature, low-pressure wet saturated steam working fluid absorbs heat in heat exchanger 13, reaching state point 5, completing a cycle.

[0067] In the space nuclear Brayton power generation system composed of the nuclear Brayton thermoelectric conversion subsystem and the heat pump circulation heat dissipation subsystem (inverse Rankine), the Brayton compressor 11, Brayton turbine 12, heat pump compressor 14 and generator 20 are integrated into a set of main shafts 18 by a set of gearboxes 19, and supply power to the external system.

[0068] Embodiment 10. This embodiment further limits the space nuclear Brayton power generation system provided in embodiment 9. In the heat dissipation subsystem, the cooler is a heat pump turbine 16, which is coaxial with the heat pump compressor 14 and is used to drive a generator 20.

[0069] Implementation 11: This implementation provides a specific implementation of the space nuclear Brayton power generation system provided in Implementation 9. Specifically:

[0070] The key design parameters of the system are shown in the following table:

[0071] Table 1 Key parameters of the multi-machine integrated space nuclear Brayton power generation system

[0072]

[0073] In Table 1, τ is the system temperature increase ratio, and its acquisition expression is:

[0074]

[0075] Wherein T3 is the Figure 1 and Figure 2 The outlet temperature of the heat exchanger 13 of the Brayton thermoelectric conversion subsystem of the China Nuclear Energy Corporation is shown in Table 1. In Table 1, κ is the adiabatic index of the working fluid, which is 1.678 in this embodiment.

[0076] This embodiment couples a reverse Brayton heat pump cooling system using helium and xenon as the working fluids with a nuclear Brayton thermoelectric conversion subsystem. This embodiment iteratively designs the system using different technical routes: an uncoupled heat pump radiator with a 600K inlet temperature for the radiant heat exchanger 13; an uncoupled heat pump radiator with a 300K inlet temperature for the cold side of the heat exchanger 13; and a coupled heat pump radiator with a 300K inlet temperature for the cold side of the heat exchanger 13 and a 600K inlet temperature for the radiant heat exchanger 15.

[0077] Table 2 shows the system design parameters when the heat pump radiator is not coupled and the cold side inlet temperature of the heat exchanger 13 is 300K.

[0078] Table 2 Parameters of the star-level nuclear energy system without coupling the heat pump radiator and with the cold side inlet temperature of heat exchanger 13 at 300K

[0079]

[0080] In the above system design, helium-xenon at a pressure of 1.5 MPa is heated to 1300K by the nuclear reactor; the high-temperature, high-pressure helium-xenon enters the Brayton turbine 12 to expand and perform work, causing its temperature to drop to 663.5K and its pressure to drop to 0.282 MPa; the working fluid, which has completed the work, passes through the heat exchanger 13 to remove waste heat, and its temperature further drops to 336.4K; the low-temperature, low-pressure helium-xenon is compressed by the Brayton compressor 11, raising its pressure to 1.5 MPa and its temperature to 657.2K; the high-pressure, low-temperature helium-xenon is heated by the nuclear reactor heater 10, raising its temperature to 1300K, completing a power cycle. In this design, the thermal efficiency of the interstellar nuclear energy Brayton system is 43.9%, and the system specific cycle work is 148.58 kJ / kg. The required heat dissipation area of ​​the system radiation radiator 15 is 2200 m 2 .

[0081] Table 3 shows the system design parameters when the heat pump radiator is not coupled and the inlet temperature of the radiation heat exchanger 13 is 600K.

[0082] Table 3 Parameters of the star-level nuclear energy system without coupling the heat pump radiator and with the inlet temperature of the radiation heat exchanger 13 at 600K

[0083]

[0084]

[0085] In the above system design, helium-xenon at a pressure of 1.5 MPa is heated to 1300K by the nuclear reactor; the high-temperature, high-pressure helium-xenon enters the Brayton turbine 12 to expand and perform work, causing its temperature to drop to 908.6K and its pressure to drop to 0.612 MPa; the working fluid, which has completed the work, passes through the heat exchanger 13 to remove waste heat, and its temperature further drops to 630.8K; the low-temperature, low-pressure helium-xenon is compressed by the Brayton compressor 11, raising its pressure to 1.5 MPa and its temperature to 904.1K; the high-pressure, low-temperature helium-xenon is heated by the nuclear reactor heater 10, raising its temperature to 1300K, completing a power cycle. In this design, the thermal efficiency of the interstellar nuclear energy Brayton system is 23.7%, and the system specific cycle work is 48.56 kJ / kg. The required heat dissipation area of ​​the system radiation radiator 15 is 193 m 2 .

[0086] Table 4 shows the system design parameters for a coupled heat pump radiator with a cold side inlet temperature of 300K for the heat exchanger 13 and a radiant radiator 15 inlet temperature of 600K.

[0087] Table 4

[0088]

[0089]

[0090] In the above system design, in the Brayton thermoelectric conversion subsystem, helium-xenon at a pressure of 1.5 MPa is heated to 1300K by the nuclear reactor; the high-temperature and high-pressure helium-xenon enters the Brayton turbine 12 to expand and perform work, and its temperature drops to 663.5K and its pressure drops to 0.282 MPa; the working fluid that has completed the work passes through the heat exchanger 13 to remove waste heat, and its temperature further drops to 336.4K; the low-temperature and low-pressure helium-xenon is compressed by the Brayton compressor 11, the pressure is increased to 1.5 MPa, and the temperature rises to 657.2K; the high-pressure and low-temperature helium-xenon is heated by the nuclear reactor heater 10, and the temperature rises to 1300K, completing a work cycle. In the heat pump circulation and heat dissipation subsystem, helium-xenon with a pressure of 0.3 MPa and a temperature of 300 K is heated to 426 K by the heat exchanger 13; the medium-temperature, low-pressure helium-xenon enters the heat pump compressor 14 for compression, and its temperature rises to 600 K and its pressure rises to 1.08 MPa; the high-temperature, high-pressure helium-xenon passes through the radiation radiator 15 to remove waste heat, and its temperature further drops to 450 K; the medium-temperature, high-pressure helium-xenon passes through the heat pump turbine 16 to perform work, and its pressure drops to 0.3 MPa and its temperature drops to 300 K; the low-temperature, low-pressure helium-xenon enters the heat exchanger 13 for heating, completing a heat transport cycle. In this design, the thermal efficiency of the interstellar nuclear energy Brayton system is 25.4%, and the system specific cycle work is 84.2 kJ / kg. The heat dissipation area required by the system radiation radiator 15 is 200 m 2 .

[0091] In summary, in this embodiment, under the condition that the inlet temperature of the cold side of the heat exchanger 13 is 300K, the thermal efficiency of the coupled heat pump heat dissipation star-level nuclear energy system is 56% of the thermal efficiency of the uncoupled heat pump nuclear energy system, and the system specific work is 57% of the specific work of the uncoupled heat pump nuclear energy system. However, the heat dissipation area required is only 9% of the uncoupled heat pump nuclear energy system, which is 200m2. 2 Under the condition that the inlet temperature of the radiation radiator 15 is 600K, the heat dissipation area of ​​the coupled heat pump heat dissipation star-level nuclear energy system is the same as that of the uncoupled heat pump heat dissipation star-level nuclear energy system, but the thermal efficiency of the coupled heat pump heat dissipation star-level nuclear energy system is 1.08 times that of the uncoupled heat pump heat dissipation star-level nuclear energy system, and the output specific work of the coupled heat pump heat dissipation star-level nuclear energy system is 1.75 times that of the uncoupled heat pump heat dissipation star-level nuclear energy system.

[0092] It can be seen that under the condition that the inlet temperature of the cold side of the heat exchanger 13 is the same, the present invention can effectively reduce the radiation heat dissipation area of ​​the system; under the condition that the inlet temperature of the radiation heat exchanger 13 is the same, the present invention can effectively improve the thermal efficiency and work capacity of the system.

[0093] Above, in combination with the accompanying drawings, the technical solution provided by the present invention is further described in detail through specific implementation methods in order to highlight the advantages and benefits of the technical solution provided by the present invention. However, the several specific implementation methods described above are not intended to limit the present invention. Any reasonable modification and improvement of the present invention, reasonable combination of implementation methods and equivalent replacement based on the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Space nuclear Brayton power generation system, characterized in that: The system includes a heat dissipation subsystem and a Brayton thermoelectric conversion subsystem; The Brayton thermoelectric conversion subsystem is used to exchange waste heat generated by the space nuclear reactor; The heat dissipation subsystem is used to discharge the waste heat; The heat pump compressor is coaxial with the Brayton compressor and the Brayton turbine in the Brayton thermoelectric conversion subsystem and is used to drive the generator; The heat dissipation subsystem includes: Heat pump compressors, heat exchangers, radiators and desuperheaters; The heat exchanger is used to transfer the heat in the star surface nuclear energy system to the radiator through the heat pump compressor. After passing through the radiator, the heat is cooled by the cooler and then transferred to the heat exchanger. The cooler is a heat pump turbine; In the heat dissipation subsystem, the working fluid used to transfer heat is helium-xenon, supercritical carbon dioxide or helium.

2. The space nuclear Brayton power generation system according to claim 1, characterized in that: In the heat dissipation subsystem, the cooler is a heat pump turbine, which is coaxial with the heat pump compressor and is used to drive a generator.

3. The space nuclear Brayton power generation system according to claim 1, characterized in that: The radiator is a radiation radiator.

4. The space nuclear Brayton power generation system according to claim 3, characterized in that: The radiant heat sink is a heat pipe radiant heat sink.

5. The space nuclear Brayton power generation system according to claim 3, characterized in that: The radiation radiator is a droplet radiation radiator.

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