A Martian surface power cycle heat dissipation device and design method thereof

Abstract

The present invention provides a Martian surface power cycle heat dissipation device combining heat pipe heat dissipation and convection heat exchange and a design method thereof. The heat dissipation device includes: a heat pipe, a fin, a heat pipe auxiliary pipeline, a convection heat exchange pipeline, a fan, a pump, a cover plate, a header, a support film, a connecting pipeline, a support frame, and liquid metal. The heat dissipation device design steps are: using a thermal resistance network method to design a modeling and solving program for the heat pipe, using a finite volume method to establish a design program for the convection heat exchanger, and then establishing a design program for the entire heat exchange system. After that, the heat pipe heat dissipation power ratio and the convection heat exchanger inlet wind speed are set as optimization parameters, and a multi-objective optimization method is used for design in terms of weight and power consumption to obtain the Pareto frontier, and then a design scheme is selected. The present invention can fully utilize radiation heat dissipation to improve safety and reliability, while reducing the weight of the heat removal system as much as possible, reducing the deployment cost of high-power power supplies on the surface of Mars, and increasing the feasibility of long-term living plans on the surface of Mars.

Description

Technical Field

[0001] The present invention relates to a heat dissipation device and a design method thereof, and in particular, to a heat dissipation device suitable for power circulation on the surface of Mars and a design method thereof. Background Art

[0002] The high-power power sources currently under development for Mars exploration mainly use Brayton and other power cycles for power generation. The key to power cycle power generation is to discharge waste heat to the cold source in time so that the cycle can proceed normally. The atmospheric composition of the surface of Mars is mainly CO2, with a pressure of 700Pa and an average temperature of -30°C. For the power cycle on the surface of Mars, due to the lack of cooling water, it can only dissipate heat through convection and radiation with the Martian atmosphere, and the mass of the heat removal system accounts for more than half of the total mass of the nuclear power source. Due to the tight capacity of launching launch vehicles from the Earth to Mars, reducing the mass of the heat removal system is crucial to reducing the deployment cost of high-power power sources on the surface of Mars and increasing the feasibility of long-term living plans on the surface of Mars.

[0003] At present, the conceptual designs for the power cycle on the surface of Mars at home and abroad are all single-type radiation heat dissipation or convection heat exchange, and the feasibility of combining the two heat dissipation methods has not yet been explored. In terms of design priority, the heat removal system is designed as a byproduct when studying the power cycle power generation system. It adopts a lumped approach, lacks fine modeling, and its accuracy cannot be guaranteed. At the overall level of the power cycle power generation system, the weight optimization research is carried out, and there is a lack of optimization measures to reduce the weight of the heat removal system alone.

[0004] The heat dissipation device used for the power cycle on the surface of Mars uses a fan to drive the Martian atmosphere to blow toward the heat dissipation pipe, taking away the heat emitted by the working fluid inside the pipe for heat exchange, which is an active heat dissipation method. The higher the wind speed, the stronger the heat dissipation capacity and the greater the power consumption. Radiative heat dissipation is the heat of the working fluid inside the heat dissipation pipe. Through the heat pipe inserted on the heat dissipation pipe, the heat is exported to the heat radiation plate connected to the heat pipe through the evaporation and condensation of the working fluid inside the heat pipe to dissipate the heat outward. It is an efficient passive heat dissipation method that does not require driving a fan. When designing a heat dissipation device for the power cycle on the surface of Mars, if convective heat transfer and radiative heat dissipation can be combined, a certain proportion of radiative heat dissipation to the total heat dissipation power can be set to dissipate the power cycle on the surface of Mars, and a design method can be formulated for the measures to reduce weight and power consumption of the heat dissipation device for the power cycle on the surface of Mars, it is possible to fully utilize radiative heat dissipation to improve safety and reliability while reducing the weight of the heat removal system as much as possible. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of the present invention is to provide a Martian surface power cycle heat dissipation device and a design method thereof that combines heat pipe heat dissipation and convection heat transfer.

[0006] According to a first aspect of the present invention, a heat dissipation device for a Martian surface power cycle combining heat pipe heat dissipation and convection heat exchange is provided. The heat dissipation device is suitable for a Martian surface power cycle, comprising: the heat dissipation device comprises a heat pipe (1), a fin (2), a heat pipe auxiliary pipeline (3), a convection heat exchange pipeline (4), a fan (5), a pump (6), a cover plate (7), a header (8), a support film (9), a connecting pipeline (10), a support frame (11) and liquid metal (12); the fin (2) is connected to the heat pipe (1); the heat pipe (1) The bottom is connected to the heat pipe auxiliary pipeline (3), the heat pipe auxiliary pipeline (3) is connected to the connecting pipeline (10), the pump (6), and the header (8) in sequence, the convection heat exchange pipeline (4) is connected to the header (8) on both sides, the support frame (11) is connected to the support film (9) and the cover plate (7), the fan (5) is connected to the support film (9) and the support frame (11), and the liquid metal (12) flows through the heat pipe (1), the heat pipe auxiliary pipeline (3), the connecting pipeline (10), the pump (6), the header (8), the convection heat exchange pipeline (4), and the header (8) in sequence.

[0007] In the above solution, the shell and the mesh core of the heat pipe (1) are made of titanium. While meeting the strength requirements, the titanium material is light in weight, thus reducing transportation costs.

[0008] The internal working medium of the heat pipe (1) is water. Water has a relatively large latent heat of vaporization, which can increase the heat transfer power limit of the heat pipe.

[0009] The heat pipe (1) is placed vertically with the evaporation section at the bottom. The vertical placement is conducive to the reflux of condensate and further improves the heat transfer power limit of the heat pipe.

[0010] The surface of the fin (2) is coated with a high-emissivity coating, which can increase the radiation heat exchange of the fin to space.

[0011] The heat pipe auxiliary pipe (3) is made of titanium, and the convection heat exchange pipe (4) is made of titanium.

[0012] The pump (6) is a hydraulic pump, which can provide a relatively high pressure for the working fluid, so that the working fluid can overcome the flow resistance in the circuit. Relationship between the weight and power of the water pump:

[0013]

[0014] The fan (5) is made of glass fiber, which meets the fan strength requirements and is light in weight. The liquid metal (12) is made of sodium-potassium alloy. Advantages: The sodium-potassium alloy has a high boiling point, which avoids phase change and ensures heat exchange effect.

[0015] A method for designing a Martian surface power cycle heat dissipation device combining heat pipe heat dissipation and convection heat transfer, the method comprising the following steps:

[0016] Step 1: Use the thermal resistance network method to model and solve the heat pipe design program to obtain the temperature field and heat transfer power of a single heat pipe.

[0017] Step 2: Use the finite volume method to establish a design program for the convection heat exchanger. First, obtain the temperature field and current heat transfer power. Then, adjust the number of heat transfer pipes of the convection heat exchanger so that its heat transfer capacity finally meets the given heat transfer requirements.

[0018] Step 3: Preliminarily select the basic geometric parameters of the heat pipe cooling device based on the power-to-weight ratio and capillary limit of the heat pipe cooling device.

[0019] Step 4: According to the power-to-weight and volume restrictions of the convection heat exchanger, the basic geometric parameters of the convection heat exchanger are preliminarily selected.

[0020] Step 5: Establish the design program of the entire heat exchange system, set the heat pipe heat dissipation power ratio and the convection heat exchanger inlet wind speed, set the number of heat pipes in series and the number of pipes in parallel in the heat pipe heat dissipation device,

[0021] Step 6: Use the heat pipe solver to model and solve each heat pipe in the same series pipeline to obtain the temperature field and heat transfer power. According to the designed heat transfer capacity of the heat pipe part, adjust the length of the heat pipe condensation section.

[0022] Step 7: Use the convection heat exchanger design program to design the number of convection heat exchanger pipes at a given wind speed and partial heat dissipation power of the convection heat exchanger.

[0023] Step 8: Set the heat pipe heat dissipation power ratio and the convection heat exchanger inlet wind speed as optimization parameters, call the entire heat exchange system design program, and use the multi-objective optimization method to design the weight and power consumption to obtain the Pareto frontier.

[0024] Step 9: Perform performance analysis on the individuals on the Pareto frontier and select the final design solution based on weight and power consumption.

[0025] Among them, the control equations of the heat pipe wall, liquid wick, and steam zone in step 1 are:

[0026]

[0027] The differential expressions of each control volume are:

[0028]

[0029] In step 2, the difference results of the control volume inside and outside the tube are:

[0030]

[0031] The total heat transfer resistance between the working fluid in the tube and the Martian atmosphere is expressed as:

[0032]

[0033] Compared with the lumped parameter method commonly used in current heat exchanger modeling, the discrete heat exchanger modeling method using the finite volume method can accurately calculate the total heat transfer, avoid calculation errors caused by changes in physical properties, and thus design a more reliable heat removal system.

[0034] Compared with the prior art, the advantages of the present invention are as follows: the present invention makes full use of the thin atmosphere on the surface of Mars, combines convective heat transfer and radiant heat dissipation to apply to the heat dissipation device of the power cycle on the surface of Mars, sets a certain proportion of radiant heat dissipation to the total heat dissipation power to dissipate the power cycle on the surface of Mars, and formulates a design method for the heat dissipation device of the power cycle on the surface of Mars to reduce weight and power consumption. While making full use of radiant heat dissipation to improve safety and reliability, the weight and volume of the heat dissipation system can be reduced by 50%-100% compared with the weight and volume of traditional heat pipe heat dissipation. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The features, innovations and advantages of the present invention will be more easily understood through the detailed explanation of non-limiting embodiments and implementation methods with reference to the following drawings:

[0036] Figure 1 It is a front view of the overall structure of the heat dissipation device of the present invention.

[0037] Figure 2 It is a top view of the overall structure of the heat dissipation device of the present invention.

[0038] Figure 3 The figure is a flow chart of the heat dissipation device design method of the present invention.

[0039] In the figure: 1 is a heat pipe, 2 is a fin, 3 is an auxiliary pipe of the heat pipe, 4 is a convection heat exchange pipe, 5 is a fan, 6 is a pump, 7 is a cover plate, 8 is a header, 9 is a support membrane, 10 is a connecting pipeline, 11 is a support frame, and 12 is liquid metal. DETAILED DESCRIPTION

[0040] The specific embodiments of the heat dissipation device of the present invention and the implementation steps of the heat dissipation device design method are described in detail below with reference to the accompanying drawings. It should be understood that the significance of this implementation is to illustrate this patent, rather than to limit the scope of protection of this patent.

[0041] For the first part of the present invention, a Mars surface power circulation heat dissipation device combining heat pipe heat dissipation and convection heat transfer is provided, see Figure 1 and Figure 2A heat dissipation device suitable for power circulation on the surface of Mars, comprising: a heat pipe 1, a fin 2, a heat pipe auxiliary pipeline 3, a convection heat exchange pipeline 4, a fan 5, a pump 6, a cover plate 7, a header 8, a support film 9, a connecting pipeline 10, a support frame 11 and a liquid metal 12, wherein the fin 2 is connected to the heat pipe 1, the bottom of the heat pipe 1 is connected to the heat pipe auxiliary pipeline 3, the heat pipe auxiliary pipeline 3 is connected to the connecting pipeline 10, the pump 6, and the header 8 in sequence, the convection heat exchange pipeline 4 is connected to the header 8 on both sides, the support frame 11 is connected to the support film 9 and the cover plate 7, the fan 5 is connected to the support film 9 and the support frame 11, and the liquid metal 12 flows through the heat pipe 1, the heat pipe auxiliary pipeline 3, the connecting pipeline 10, the pump 6, the header 8, the convection heat exchange pipeline 4, and the header 8 in sequence to transport heat in.

[0042] Furthermore, the shell and mesh core of the heat pipe 1 are made of titanium. Specifically, the mesh core is 100 mesh, and the shell thickness is calculated based on the saturation pressure of the working fluid at the working temperature.

[0043] Furthermore, the working fluid inside the heat pipe 1 is water, and the specific heat capacity is 4200 J / (kg·K), which is suitable for working within the temperature range of the cooler.

[0044] Furthermore, the heat pipe 1 is placed vertically with the evaporation section at the bottom, which greatly increases the upper limit of the capillary limit and increases the heat pipe power.

[0045] Furthermore, the fin 2 is designed with high thermal conductivity material, and when the width is less than 9 cm, the efficiency is above 90%. The surface is coated with a high emissivity coating, and the emissivity is greater than 0.9. A thin plate sandwich design is adopted, and lightweight materials are used for filling to reduce weight.

[0046] Furthermore, the heat pipe auxiliary pipe 3 is made of titanium and adopts a contraction-type flow channel design to minimize the weight of the pipe and the internal liquid metal.

[0047] Furthermore, the material of the convection heat exchange pipe 4 is titanium. Since the convection heat exchange pipe has a small diameter, the internal pressure is lower than that of the heat pipe, and the pipe thickness is also thinner than that of the heat pipe.

[0048] Furthermore, the pump 6 is a hydraulic pump. The water pump adopts a hydraulic pump, which can output a high pressure of MPa level to ensure circulation. The relationship between the weight and power of the water pump is:

[0049]

[0050] Where m pump is the mass of the water pump, kg; W pump is the power consumption of the water pump, kW.

[0051] and

[0052] W pump =Δp×V u,NaK

[0053] Where V u,NaK is the NaK volume flow rate.

[0054] Furthermore, the fan 5 is made of glass fiber.

[0055] Furthermore, the liquid metal 12 is made of sodium-potassium alloy, and has a relatively large heat transfer coefficient with the wall of the heat pipe.

[0056] For the second part of the present invention, a design method for a Martian surface power cycle heat dissipation device combining heat pipe heat dissipation and convection heat transfer is provided. Figure 3 , including the following steps:

[0057] Step 1: Use the thermal resistance network method to model and solve the heat pipe design program to obtain the temperature field and heat transfer power of a single heat pipe. The control equations for the heat pipe wall, wick, and steam zone are:

[0058]

[0059] The differential expressions of each control volume are:

[0060]

[0061] Step 2: Use the finite volume method to establish a design program for the convection heat exchanger. First, obtain the temperature field and current heat transfer power. Then, adjust the number of heat transfer pipes of the convection heat exchanger so that its heat transfer capacity finally meets the given heat transfer requirements. The differential results of the control volume inside and outside the tube are:

[0062]

[0063] Where ρ is the control volume density, c p is the constant pressure specific heat capacity, T is the control body temperature, N represents the liquid metal side, M represents the Martian atmosphere side, y is the control body length in the direction of the tube length, x is the control body length perpendicular to the tube length, V is the control body volume of the working fluid inside and outside the pipeline, and R is the heat transfer resistance between each control body. The total heat transfer resistance between the working fluid in the tube and the Martian atmosphere is expressed as:

[0064]

[0065] Where A is the heat exchange area, h is the convection heat transfer coefficient, d0 is the outer diameter of the pipe, d1 is the inner diameter of the pipe, Δy is the length of the control body in the direction of the pipe length, λ is the wall thermal conductivity, hot represents the hot side of the liquid metal, and cold represents the cold side of the Martian atmosphere.

[0066] Step 3: According to the specific power-to-weight and capillary limit of the heat pipe cooling device, the basic geometric parameters of the heat pipe cooling device are preliminarily selected: the thickness of the liquid absorption core is 0.4mm, the radius of the steam zone is 5mm, the length of the evaporation section is 4cm, and each pipe has 70 heat pipes in series. The average power of each heat pipe is 90W.

[0067] Step 4: According to the power-to-weight and volume restrictions of the convection heat exchanger, the basic geometric parameters of the convection heat exchanger are preliminarily selected: the outer diameter of the pipe is 2 mm, the horizontal and vertical section diameter ratio is 2, the number of vertical rows is 5, and the pipe length is 6 m.

[0068] Step 5: Establish the design program of the entire heat exchange system, set the heat pipe heat dissipation power ratio and the convection heat exchanger inlet wind speed, set the number of heat pipes in series and the number of pipes in parallel in the heat pipe heat dissipation device.

[0069] Step 6: Use the heat pipe solver to model and solve each heat pipe in the same series pipeline to obtain the temperature field and heat transfer power. Adjust the length of the heat pipe condensation section according to the designed heat transfer capacity of the heat pipe part.

[0070] Step 7: Use the convection heat exchanger design program to design the number of convection heat exchanger pipes under given wind speed and partial heat dissipation power of the convection heat exchanger.

[0071] Step 8: The basic parameters of the entire heat removal system are known to be heat removal power 5.9MW, inlet NaK temperature 485K, and mass flow rate 37.28kg / s. Set the heat pipe heat dissipation power ratio and the convection heat exchanger inlet wind speed as optimization parameters, set the heat pipe heat dissipation power ratio range to 0-100%, and the wind speed range to 2-8m / s. Use the NSGA-II multi-objective optimization method, set 120 individuals and 15 generations for the two objective functions of heat removal system weight and power consumption, call the entire heat exchange system design program, and use the multi-objective optimization method for design to obtain the Pareto frontier. The weight of the pure heat pipe heat dissipation device designed in this study is 17.20t, which can be reduced by 54.3% compared with the original design of 37.60t. The weight of the pure convection heat exchanger is 4.84t, which can be reduced by 87.1% compared with the original design. The power consumption of the pure convection heat exchanger is 83.56kW. And the corresponding relationship between the heat pipe heat dissipation ratio and wind speed on the Pareto frontier is obtained.

[0072] Step 9: Perform performance analysis on the individuals on the Pareto frontier and select the final design solution based on weight and power consumption. If you want to reduce weight while maintaining a certain passive heat dissipation ratio and increase the safety of the heat dissipation system, you can select the corresponding wind speed based on the heat pipe heat dissipation ratio for design reference.

Claims

1. A heat dissipation device suitable for power circulation on the surface of Mars, characterized in that: include: The heat dissipation device comprises a heat pipe (1), a fin (2), a heat pipe auxiliary pipe (3), a convection heat exchange pipe (4), a fan (5), a pump (6), a cover plate (7), a header (8), a support film (9), a connecting pipe (10), a support frame (11) and liquid metal (12), wherein the fin (2) is connected to the heat pipe (1), the bottom of the heat pipe (1) is connected to the heat pipe auxiliary pipe (3), the heat pipe auxiliary pipe (3) is connected to the connecting pipe (10), the pump (6) and the header (8) in sequence, the convection heat exchange pipe (4) is connected to the header (8) on both sides, the support frame (11) is connected to the support film (9) and the cover plate (7), the fan (5) is connected to the support film (9) and the support frame (11), and the liquid metal (12) flows through the heat pipe (1), the heat pipe auxiliary pipe (3), the connecting pipe (10), the pump (6), the header (8), the convection heat exchange pipe (4) and the header (8) in sequence.

2. The heat dissipation device suitable for power cycle on the surface of Mars according to claim 1, characterized in that: The outer shell and mesh core of the heat pipe (1) are made of titanium.

3. The heat dissipation device suitable for power cycle on the surface of Mars according to claim 1, characterized in that: The internal working medium of the heat pipe (1) is water.

4. The heat dissipation device suitable for power cycle on the surface of Mars according to claim 1, characterized in that: The heat pipe (1) is placed vertically with the evaporation section at the bottom.

5. The heat dissipation device suitable for power cycle on the surface of Mars according to claim 1, characterized in that: The surface of the fin (2) is coated with a high emissivity coating, the heat pipe auxiliary pipe (3) is made of titanium, and the convection heat exchange pipe (4) is made of titanium.

6. The heat dissipation device suitable for power cycle on the surface of Mars according to claim 1, characterized in that: The pump (6) is a hydraulic pump, and the relationship between the pump weight and power is: Where m pump is the mass of the water pump, kg; W pump is the power consumption of the water pump, kW.

7. The heat dissipation device suitable for power cycle on the surface of Mars according to claim 1, characterized in that: The fan (5) is made of glass fiber, and the liquid metal (12) is made of sodium-potassium alloy.

8. A method for designing a heat dissipation device suitable for power circulation on the surface of Mars, characterized in that: Using the heat dissipation device according to any one of claims 1 to 7, the method comprises the following steps: Step 1: Use the thermal resistance network method to model and solve the heat pipe design program to obtain the temperature field and heat transfer power of a single heat pipe. Step 2: Use the finite volume method to establish a design program for the convection heat exchanger. First, obtain the temperature field and current heat transfer power. Then, adjust the number of heat transfer pipes of the convection heat exchanger so that its heat transfer capacity finally meets the given heat transfer requirements. Step 3: Preliminarily select the basic geometric parameters of the heat pipe cooling device based on the power-to-weight ratio and capillary limit of the heat pipe cooling device. Step 4: According to the power-to-weight and volume restrictions of the convection heat exchanger, the basic geometric parameters of the convection heat exchanger are preliminarily selected. Step 5: Establish the design program of the entire heat exchange system, set the heat pipe heat dissipation power ratio and the convection heat exchanger inlet wind speed, set the number of heat pipes in series and the number of pipes in parallel in the heat pipe heat dissipation device, Step 6: Use the heat pipe solver to model and solve each heat pipe in the same series pipeline to obtain the temperature field and heat transfer power. According to the designed heat transfer capacity of the heat pipe part, adjust the length of the heat pipe condensation section. Step 7: Use the convection heat exchanger design program to design the number of convection heat exchanger pipes at a given wind speed and partial heat dissipation power of the convection heat exchanger. Step 8: Set the heat pipe heat dissipation power ratio and the convection heat exchanger inlet wind speed as optimization parameters, call the entire heat exchange system design program, and use the multi-objective optimization method to design the weight and power consumption to obtain the Pareto frontier. Step 9: Perform performance analysis on the individuals on the Pareto frontier and select the final design solution based on weight and power consumption.

9. The method for designing a heat dissipation device suitable for power cycle on the surface of Mars according to claim 8, characterized in that: The control equations of the heat pipe wall, wick, and steam zone in step 1 are: where ρ wall is the density of the pipe wall material, λ wall is the thermal conductivity of the tube wall metal, λ eff is the equivalent thermal conductivity of the wick, T wv is the interface temperature between the wick and the vapor zone, r is the radial coordinate, z is the axial coordinate, R r is the radial thermal resistance at the junction of the wick and the vapor zone, R z is the internal axial thermal resistance of the steam zone, C is the specific heat capacity, The differential expressions of each control volume are: Where ρ is the control volume density, c p is the constant pressure specific heat capacity, V is the volume of the control body, T is the temperature of the control body, Q in is the heat entering the control volume, Q out is the heat discharged from the control body, and i represents the i-th control body.

10. The method for designing a heat dissipation device suitable for power cycle on the surface of Mars according to claim 8, characterized in that: The difference results of the control volume inside and outside the tube in step 2 are: Where ρ is the control volume density, c p is the constant pressure specific heat capacity, T is the control body temperature, N represents the liquid metal side, M represents the Martian atmosphere side, y is the control body length in the direction of the tube length, x is the control body length perpendicular to the tube length, V is the control body volume of the working fluid inside and outside the pipeline, R is the heat transfer resistance between the control bodies, and the total heat transfer resistance between the working fluid in the tube and the Martian atmosphere is expressed as: Where A is the heat exchange area, h is the convection heat transfer coefficient, d0 is the outer diameter of the pipe, d1 is the inner diameter of the pipe, Δy is the length of the control body in the direction of the pipe length, λ is the wall thermal conductivity, hot represents the hot side of the liquid metal, and cold represents the cold side of the Martian atmosphere.

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