An electric field regulation composite phase change system for the field of spacecraft thermal control and its control method

Abstract

The present invention discloses an electric field-regulated composite phase change system for the field of spacecraft thermal control, which includes a porous medium carrier, a composite phase change material, microchannels, a nanofluid medium, electrode plates, and a liquid storage tank. The composite phase change material is filled in the pores of the porous medium carrier; the microchannels are arranged inside the porous medium carrier, the nanofluid medium is arranged in the microchannels, and both ends of the microchannels are communicated with the liquid storage tank through pipelines; the temperature at corresponding positions in the porous medium carrier is detected by a temperature sensor to control the working states of the electrode plates, heating devices, and cooling devices, so as to generate an electric field on the electrode plates; the electric field acts on the composite phase change system to control the flow rate of the nanofluid in the microchannels and the state of the composite phase change material. A control method is also disclosed. The present invention can continuously absorb and store heat at higher temperatures and release the stored heat at lower temperatures under the action of an electric field, alleviating the problems of high heat flux density and uneven heat distribution of the spacecraft.

Description

Technical Field

[0001] The present invention relates to a phase change control method and system, in particular to an electric field-regulated composite phase change system for spacecraft thermal control and its control method. Background Art

[0002] Major breakthroughs in deep space exploration have promoted the development of space science exploration towards multi-mission, high-integration, and high-power consumption, making spacecraft equipment face problems such as high installation density, large power consumption, insufficient heat dissipation space, and complex thermal environments. As an essential part of ensuring the normal operation of instruments and the survival of astronauts, the thermal control system is mainly divided into passive heat dissipation technologies, such as thermal control coatings and adiabatic components, and active thermal control technologies, such as louvers and fluid loops. However, these existing technologies have problems such as poor responsiveness to environmental changes, the presence of moving parts, and inability to accurately regulate.

[0003] Therefore, to meet the requirements of future deep space exploration missions in China, it is necessary to design a thermal control system that can react to the space thermal environment in real time, adjust autonomously, and control precisely. Summary of the Invention

[0004] The object of the present invention is to solve the problems of poor responsiveness to environmental changes, the presence of moving parts, and inability to accurately regulate in existing thermal control systems, and to provide an electric field-regulated composite phase change system for spacecraft thermal control. In this system, microchannels through which a heat exchange fluid flows are arranged in the phase change material, and a controllable electric field is arranged on the microchannels. Under the action of the electric field, electroosmotic flow is formed to drive the fluid movement in the microchannels. At the same time, the phase change material is affected by the electric field, and an electroconvection phenomenon occurs under the drive of the electric field force. Thus, by adjusting the electric field parameters, the electroosmotic rate and the solid-liquid phase change intensity can be actively regulated, which has the advantages of precision, controllability, and high efficiency.

[0005] The object of the present invention can be achieved by adopting the following technical solutions:

[0006] An electric field-regulated composite phase change system for the field of spacecraft thermal control, comprising a porous medium carrier, a composite phase change material, microchannels, a nanofluid medium, electrode plates and a liquid storage tank. The composite phase change material is filled in the pores of the porous medium carrier; the microchannels are arranged inside the porous medium carrier, the nanofluid medium is arranged in the microchannels, and both ends of the microchannels are communicated with the liquid storage tank through pipelines; the electrode plates are arranged on the outer surface of the porous medium carrier; a temperature sensor is arranged inside the porous medium carrier, and a heating device and a cooling device for heating and cooling the nanofluid medium are respectively arranged in the liquid storage tank; the temperature at the corresponding position inside the porous medium carrier is detected by the temperature sensor to control the working states of the electrode plates, the heating device and the cooling device, so that the electrode plates generate an electric field; the electric field acts on the composite phase change system to control the flow velocity of the nanofluid in the microchannels and regulate the state of the composite phase change material in the porous medium.

[0007] As a preferred solution, the microchannels are communicated with the liquid storage tank through a liquid collecting plate. A sealed cavity is arranged inside the liquid collecting plate. A plurality of liquid collecting plates are provided, and the liquid collecting plates cover the outer surface of the porous medium carrier to form a phase change heat storage box body, so that the porous medium carrier is stored in the phase change heat storage box body.

[0008] As a preferred solution, the electrode plates are arranged between the liquid collecting plate and the outer surface of the porous medium carrier.

[0009] As a preferred solution, a switching valve is connected in series on the pipeline.

[0010] As a preferred solution, the electrode plates are connected to a DC power supply.

[0011] As a preferred solution, a plurality of temperature sensors are provided and are arranged in a matrix distribution inside the porous medium carrier.

[0012] A control method for an electric field-regulated composite phase change system for the field of spacecraft thermal control, comprising the following steps:

[0013] S1: The space heat flux and the spacecraft component heat flux are transferred to the porous medium carrier through the wall surface. The phase change material absorbs heat and begins to melt, and at the same time the temperature sensor detects that the temperature rises;

[0014] S2: Control the magnitude and direction (positive / negative) of the output voltage of the DC power supply to generate a corresponding electric field. If the temperature rises in multiple regions inside the porous medium carrier, start multiple electrode plates to generate a multi-directional electric field to maximize the controllability and flexibility of the electric field.

[0015] S3: Under the drive of the electric field, the nanofluid in the microchannels undergoes flow heat transfer through electroosmotic flow; the composite phase change material generates electroconvection under the action of the electric field force to realize the enhancement of heat transfer and heat storage.

[0016] S4: If the temperature detected by the temperature sensor exceeds the set warning value, increase the voltage output of the DC power supply to strengthen the electroosmotic flow rate and the solid-liquid phase change intensity, and at the same time control the working power of the cooling device to increase the heat transfer intensity; if the temperature inside the porous medium carrier monitored by the temperature sensor is less than the warning value, repeat steps S3 and S4;

[0017] S5: When the spacecraft components return to normal operating temperature or the component working intensity is low, turn off or reduce the voltage output of the DC power supply;

[0018] S6: When the spacecraft is at a relatively low operating temperature, the temperature sensor detects a relatively low temperature area inside the porous medium carrier, activates the electrode plates in the corresponding direction to generate an electric field, controls the heating device of the liquid storage tank to start, makes the electroosmotic drive nanofluid move, and the phase change composite material solidifies and releases heat to keep the spacecraft components operating normally.

[0019] Implementing the present invention has the following beneficial effects:

[0020] 1. The present invention can continuously absorb and store heat at higher temperatures and release the stored heat at lower temperatures under the action of an electric field to improve the influence of a complex thermal environment, and the microchannels transport / release heat to alleviate the problems of high heat flux density and uneven heat distribution of the spacecraft, and establish a heat storage-heat transfer-heat dissipation mechanism in space and time, thereby solving the problem of thermal runaway and ensuring the safe operation of spacecraft components. This system can improve the thermal control efficiency of spacecraft components, improve the energy utilization efficiency, and has the advantages of simple manufacturing, low cost, and compact structure.

[0021] 2. Each liquid collection plate of the present invention is independent of each other and not directly connected, and three pairs of electrode plates are respectively formed in different planes. The space surrounded by each liquid collection plate forms a box structure, which serves to store the porous medium carrier, the composite phase change material, and the microchannels, and each liquid collection plate can also collect the nanofluid medium flowing in and out of the microchannels, greatly simplifying the structure of the entire composite phase change system and making the structure more compact and lightweight. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings without creative efforts based on these drawings.

[0023] Figure 1 It is a schematic structural diagram of the electric field-regulated composite phase change system for spacecraft thermal control field of the present invention.

[0024] Figure 2 This is an exploded view of the electric field regulated composite phase change system of the present invention for the field of spacecraft thermal control.

[0025] Figure 3 This is a schematic diagram of the connection structure of the porous medium carrier, composite phase change material, microchannel, and nanofluid medium of the electric field regulated composite phase change system of the present invention for the field of spacecraft thermal control.

[0026] Figure 4 It is Figure 3 side view of.

[0027] Figure 5 This is a control block diagram of the control method of the electric field regulated composite phase change system of the present invention for the field of spacecraft thermal control. Specific embodiments

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] Embodiment

[0030] Referring to Figures 1 to 4 , this embodiment relates to a composite phase change system, including a porous medium carrier 1, a composite phase change material 2, a microchannel 3, a nanofluid medium 4, an electrode plate 5, and a liquid storage tank 6. The composite phase change material 2 is filled in the pores of the porous medium carrier 1; the microchannel 3 is arranged inside the porous medium carrier 1, the nanofluid medium 4 is arranged in the microchannel 3, and both ends of the microchannel 3 are communicated with the liquid storage tank 6 through a pipeline 7; the electrode plate 5 is arranged on the outer surface of the porous medium carrier 1; a temperature sensor 8 is arranged inside the porous medium carrier 1, and a heating device and a cooling device for heating and cooling the nanofluid medium 4 are respectively arranged in the liquid storage tank 6; the temperature at a corresponding position inside the porous medium carrier 1 is detected by the temperature sensor 8 to control the working states of the electrode plate 5, the heating device, and the cooling device, so that the electrode plate 5 generates an electric field; the electric field acts on the microchannel 3 and the nanofluid medium 4 (composite phase change system) to control the flow rate of the nanofluid in the microchannel 3 and the state of the composite phase change material 2.

[0031] The porous medium carrier 1 serves as the framework of the phase change system. When the solid-phase composite phase change material 2 absorbs heat and turns into a liquid phase, the porous medium carrier 1 has the function of enhancing the solid-liquid heat transfer rate and improving the temperature uniformity of the system. The microchannels 3 are integrated within the porous medium to achieve efficient multi-directional and multi-flow heat transfer. The composite phase change material 2 is prepared from a phase change material and high-thermal-conductivity nanoparticles and is filled in the pores between the porous medium carrier 1 and the microchannels 3 to store the spatial heat flux, the heat flux of spacecraft components, and the heat of the microchannels 3, and solidify and release heat when needed. The nanofluid is prepared from nanoparticles and an electrolyte solution and is used to provide the flow and heat transfer medium for the microchannels 3 and is stored in the liquid storage tank 6. The electrode plates 5 are distributed on the inlet and outlet surfaces of the microchannels 3, that is, the electrode plates 5 are arranged on the outer surface of the porous medium carrier 1. The electrode plates 5 are used to apply an external electric field to drive the transportation of the nanofluid in the liquid storage tank 6 and regulate the intensity of the solid-liquid phase change process, and encapsulate the porous medium carrier 1 to form a heat transfer working fluid cavity.

[0032] The microchannels 3 are of a fractal bionic structure and are integrated within the porous medium carrier 1 through additive manufacturing technology. The microchannels 3 are provided in both the y-plane and the z-plane. The nanofluid in the microchannels 3 at different positions can exchange heat with different positions during flow. Each liquid collection plate is independent of each other and is not directly connected.

[0033] This structure applies an electric field through the electrode plates 5 to generate an electric field force on the nanofluid medium 4 in the microchannels 3 of the composite phase change material 2 to improve the heat transfer and heat storage performance of the composite phase change material 2. When heat acts on the phase change system through heat conduction, the composite phase change material 2 near the components starts to absorb heat and melt and store heat. The temperature sensor 8 detects the rising temperature, and the control electrode plate 5 works to generate a corresponding electric field. Under the action of the electric field, the nanofluid contacts the wall surface of the microchannels 3 to produce the double-layer effect, making the ions in the double layer drive the fluid to flow directionally along the electric field direction, carrying part of the heat. At the same time, more regions in the composite phase change material 2 change from the solid phase to the liquid phase, and the electric field excitation generates charges to form a Coulomb force, establishing a complex flow of thermocapillary convection and electroconvection, thereby enhancing the heat transfer and heat storage ability of the components. In addition, based on the principle of electrohydrodynamics, the electroosmotic flow and electroconvection can be precisely regulated by controlling the output voltage of the DC power supply to change the electric field strength. Therefore, the composite phase change system of this structure can continuously absorb and store heat at a higher temperature and release the stored heat at a lower temperature under the action of the electric field to improve the influence of a complex thermal environment, and the microchannels 3 transport / release heat to alleviate the problems of high heat flux density and uneven heat distribution, establishing a heat storage-heat transfer-heat dissipation mechanism in space and time, thereby solving the problem of thermal runaway and ensuring the safe operation of spacecraft components. This structure can improve the thermal control efficiency of spacecraft components, improve the energy utilization efficiency, and has the advantages of simple manufacturing, low cost, compact structure, and precise control.

[0034] The microchannel 3 communicates with the liquid storage tank 6 through the liquid collecting plate 9. The inside of the liquid collecting plate 9 is provided with a sealed cavity. The liquid collecting plates 9 are multiple, and the liquid collecting plates 9 cover the outer surface of the porous medium carrier 1 to form a phase change heat storage box body, so that the porous medium carrier 1 is stored in the phase change heat storage box body. Each liquid collecting plate 9 is independent of each other and not directly connected, and three pairs of electrode plates 5 are respectively formed in different planes. The spaces surrounded by the liquid collecting plates 9 form a box structure, which serves to store the porous medium carrier 1, the composite phase change material 2 and the microchannel 3, and each liquid collecting plate 9 can also collect the nanofluid medium 4 flowing in and out of the microchannel 3, greatly simplifying the structure of the entire composite phase change system and making the structure more compact and lightweight.

[0035] The electrode plate 5 is arranged between the outer surface of the liquid collecting plate 9 and the porous medium carrier 1. The electrode plate 5 generates an electric field to perform electroosmotic flow on the nanofluid medium 4, so that the composite phase change system can continuously absorb and store heat at a higher temperature and release the stored heat at a lower temperature under the action of the electric field to improve the influence of a complex thermal environment, and the microchannel 3 conveys / releases heat to alleviate the problems of high heat flux density and uneven heat distribution.

[0036] A switching valve 10 is connected in series on the pipeline 7. Before the flow of the nanofluid medium 4 needs to be controlled by applying an electric field, the switching valve 10 is first opened, otherwise, the switching valve 10 is closed.

[0037] The electrode plate 5 is connected to the DC power supply 11. A pair of corresponding electrode plates 5 are respectively connected to the positive and negative electrodes of the DC power supply 11.

[0038] Multiple temperature sensors are provided and are arranged in a matrix distribution inside the porous medium carrier 1, so as to timely obtain temperature changes and make responses.

[0039] A control method for an electric field-regulated composite phase change system in the field of spacecraft thermal control, as Figure 5 shown, includes the following steps:

[0040] S1: The space heat flux and the heat flux of the spacecraft components are transferred to the porous medium carrier 1 through the wall surface, the phase change material absorbs heat and begins to melt, and at the same time the temperature sensor 8 detects an increase in temperature;

[0041] S2: Control the magnitude and direction (positive / negative) of the output voltage of the DC power supply to generate a corresponding electric field. If the temperatures in multiple regions inside the porous medium carrier 1 increase, start multiple electrode plates 5 to generate a multi-directional electric field to maximize the controllability and flexibility of the electric field.

[0042] S3: Under the drive of the electric field, the nanofluid in the microchannel 3 undergoes flow heat transfer through electroosmotic flow; the composite phase change material 2 generates electroconvection under the action of the electric field force to enhance heat transfer and heat storage.

[0043] S4: If the temperature sensor 8 detects that the temperature exceeds the set warning value, increase the voltage output of the DC power supply to enhance the electroosmotic flow rate and the solid-liquid phase change intensity, and at the same time control the working power of the cooling device to increase the heat transfer intensity; if the temperature inside the porous medium carrier 1 monitored by the temperature sensor 8 is less than the warning value, repeat steps S3 and S4;

[0044] S5: When the spacecraft components return to normal operating temperature or the component working intensity is low, turn off or reduce the voltage output of the DC power supply;

[0045] S6: When the spacecraft is at a lower operating temperature, the temperature sensor 8 detects the lower temperature area inside the porous medium carrier 1, activates the electrode plate 5 in the corresponding direction to generate an electric field, and controls the heating device of the liquid storage tank 6 to start, so that the electroosmotic drive nanofluid moves, and the phase change composite material solidifies and releases heat to keep the spacecraft components operating normally.

[0046] The porous medium is made of metal foam or expanded graphene. The nano-phase change material is selected according to the heating power, temperature control range, working cycle, heat storage requirement and working temperature range of the spacecraft components; it is injected into the porous medium carrier 1 by the vacuum infiltration method. The nano-phase change material is a straight-chain alkane, such as n-octadecane, n-nonadecane or n-eicosane, etc., and the nano-particles are metal oxides, such as alumina, titanium oxide, iron oxide, etc.

[0047] This method applies an electric field through the electrode plate 5 to exert an electric field force on the nanofluid medium 4 in the microchannel 3 of the composite phase change material 2, so as to improve the heat transfer and heat storage performance of the composite phase change material 2. When heat acts on the phase change system through heat conduction, the composite phase change material 2 near the component starts to absorb heat and melt to store heat; the temperature sensor 8 detects the temperature rise, and controls the electrode plate 5 to work to generate a corresponding electric field. Under the action of the electric field, the nanofluid contacts the wall surface of the microchannel 3 to produce the electric double layer effect, so that the ions in the electric double layer drive the fluid to flow directionally along the electric field direction, carrying part of the heat. At the same time, more regions in the composite phase change material 2 change from solid phase to liquid phase, and the electric field excitation generates charges to form Coulomb force, establishing a complex flow of thermocapillary convection and electroconvection, thereby strengthening the heat transfer and heat storage capacity of the component. In addition, based on the principle of electrohydrodynamics, the electroosmotic flow and electroconvection can be precisely regulated by controlling the output voltage of the DC power supply to change the electric field strength. Therefore, the composite phase change system of this structure can continuously absorb and store heat at a higher temperature and release the stored heat at a lower temperature under the action of the electric field, so as to improve the influence of the complex thermal environment, and the microchannel 3 conveys / releases heat to alleviate the problems of high heat flux density and non-uniform heat distribution, establishing a heat storage-heat transfer-heat dissipation mechanism in space and time, thereby solving the problem of thermal runaway and ensuring the safe operation of spacecraft components. This structure can improve the thermal control efficiency of spacecraft components, improve the energy utilization efficiency, and has the advantages of simple manufacturing, low cost and compact structure.

[0048] The above disclosure is only a preferred embodiment of the present invention, and of course it cannot be used to limit the scope of the rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. An electric field regulation composite phase change system for the field of spacecraft thermal control, characterized in that It includes a porous medium carrier, a composite phase change material, microchannels, nanofluid medium, electrode plates and a liquid storage tank. The composite phase change material is filled in the pores of the porous medium carrier; the microchannels are arranged inside the porous medium carrier, and the nanofluid medium is arranged in the microchannels, and both ends of the microchannels are communicated with the liquid storage tank through pipelines; the electrode plates are arranged on the outer surface of the porous medium carrier; a temperature sensor is arranged inside the porous medium carrier, and a heating device and a cooling device for heating and cooling the nanofluid medium are respectively arranged in the liquid storage tank; the temperature at the corresponding position inside the porous medium carrier is detected by the temperature sensor to control the working states of the electrode plates, the heating device and the cooling device, so that the electrode plates generate an electric field; the electric field acts on the composite phase change system to control the flow velocity of the nanofluid in the microchannels and regulate the state of the composite phase change material in the porous medium.

2. The electric field-regulated composite phase change system for the field of spacecraft thermal control according to claim 1, wherein The microchannels are communicated with the liquid storage tank through a liquid collecting plate. The liquid collecting plate is internally provided with a sealed cavity. A plurality of liquid collecting plates are provided, and the liquid collecting plates cover the outer surface of the porous medium carrier to form a phase change heat storage box body, so that the porous medium carrier is stored in the phase change heat storage box body.

3. The electric field regulated composite phase change system for spacecraft thermal control field according to claim 2, characterized in that, The electrode plates are arranged between the liquid collecting plate and the outer surface of the porous medium carrier.

4. The electric field-regulated composite phase change system for spacecraft thermal control field according to claim 1, wherein A switching valve is connected in series on the pipeline.

5. The electric field-regulated composite phase change system for the field of spacecraft thermal control according to claim 1, wherein The electrode plates are connected to a DC power supply.

6. The electric field regulation composite phase change system for the spacecraft thermal control field according to claim 1, wherein A plurality of temperature sensors are provided and are arranged in a matrix distribution inside the porous medium carrier.

7. A control method for an electric field-regulated composite phase change system used in the field of spacecraft thermal control according to any one of claims 1 to 6, characterized in that, It includes the following steps: S1: The spatial heat flow and the heat flow of the spacecraft components are transferred to the porous medium carrier through the wall surface. The phase change material absorbs heat and begins to melt, and at the same time the temperature sensor detects a temperature rise. S2: Control the magnitude and direction of the output voltage of the DC power supply to generate a corresponding electric field. If the temperatures in multiple regions inside the porous medium carrier rise, start multiple electrode plates to generate a multi-directional electric field. S3: Under the drive of the electric field, the nanofluid in the microchannels undergoes flow heat transfer through electroosmotic flow; the composite phase change material generates electroconvection under the action of the electric field force to achieve enhanced heat transfer / heat storage. S4: If the temperature sensor detects that the temperature exceeds the set warning value, increase the voltage output magnitude of the DC power supply to strengthen the electroosmotic flow rate and the solid-liquid phase change intensity, and at the same time control the working power of the cooling device to increase the heat transfer intensity; if the temperature inside the porous medium carrier monitored by the temperature sensor is less than the warning value, repeat steps S3 and S4. S5: When the spacecraft components return to the normal working temperature or the working intensity of the components is low, turn off or reduce the voltage output magnitude of the DC power supply. S6: When the spacecraft is at a lower working temperature, the temperature sensor detects the lower temperature region inside the porous medium carrier, start the electrode plates in the corresponding direction to generate an electric field, control the heating device in the liquid storage tank to start, make the electroosmosis drive the nanofluid to move, and the phase change composite material solidifies and releases heat to keep the spacecraft components at the normal working temperature.

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