Multi-module cooperative liquid cooling heat dissipation system suitable for microgravity environment

Abstract

The application discloses a multi-module cooperative liquid cooling heat dissipation system suitable for a microgravity environment, relates to the technical field of spacecraft thermal control, and aims to solve the problem of the failure of gas-liquid separation under microgravity, flow pattern instability and the inability to meet the demand of 100-kilowatt-level heat dissipation in the prior art. The system comprises a separated flow two-phase mechanical pump loop module, an EHD pumping module, a centrifugal gas-liquid separator, an ultrasonic auxiliary crushing module and an intelligent pressure accumulator and MPC module. The ultrasonic auxiliary crushing module crushes large bubbles into micro-bubbles, which are carried away from the heating surface under the action of the directional flow of the EHD pumping module; the centrifugal gas-liquid separator efficiently separates the gas-liquid mixture after ultrasonic pretreatment; and the intelligent pressure accumulator and MPC module synchronously and coordinately adjusts the working parameters of each module. Through the deep cooperation of the multiple modules, the critical heat flux density is increased by 40-60%, the temperature difference is controlled within ± 2K, and the system is reduced by more than 40%, and the system can be used in spacecraft such as computing satellites.

Description

Technical Field

[0001] This invention relates to the field of spacecraft thermal control technology, and in particular to a multi-module collaborative liquid cooling system adapted to microgravity environments. Background Technology

[0002] Currently, in the field of spacecraft thermal control, commonly used heat dissipation technologies mainly include single-phase fluid circulation heat dissipation, two-phase fluid circulation heat dissipation, and radiative heat dissipation, each of which has its own significant limitations: I. Bottleneck of Single-Phase Heat Dissipation Capacity Single-phase fluid circulation cooling technology mainly uses a mechanical pump to drive a single liquid working fluid, removing heat through sensible heat changes. Its heat dissipation capacity is limited by the specific heat capacity of the working fluid. In high heat flux density scenarios at the hundreds of kilowatt level, it requires extremely large flow rates and pipe diameters, resulting in a significant increase in system weight and power consumption. Furthermore, it cannot utilize the latent heat of phase change of the working fluid, resulting in low heat exchange efficiency and difficulty in meeting the heat dissipation requirements of chip-level local heat flux densities exceeding 100 W / cm².

[0003] II. Failure of Two-Phase Flow under Microgravity Two-phase fluid circulation heat dissipation technology utilizes the boiling phase change of the working fluid to remove heat, theoretically resulting in a much higher heat exchange efficiency than single-phase heat dissipation. However, this technology relies on gravity to achieve natural gas-liquid separation on Earth. In microgravity environments, the lack of gravity leads to the failure of natural gas-liquid separation, and bubbles coalesce on the heating surface to form a gas film, thus significantly reducing the boiling critical heat flux density. During long-distance transmission, the flow pattern becomes unstable, with alternating slug flow and annular flow, causing system pressure oscillations and cold plate surface temperature fluctuations. Furthermore, frequent evaporator drying out severely reduces system reliability.

[0004] III. Limitations on Radiative Heat Dissipation Area As the final means of heat dissipation for spacecraft, the heat dissipation area of ​​radiative heat dissipation technology is positively correlated with the heat load. A heat load of hundreds of kilowatts requires an ultra-large radiative area of ​​80-120m², and the deployment mechanism is complex and its reliability is difficult to guarantee.

[0005] IV. Lack of systematic collaborative design In existing technology research, individual technologies such as electrohydraulic (EHD) pumping, electrowetting bubble control, capillary wick liquid reflux, and phase change material (PCM) thermal buffering have been studied and published. However, existing technologies mostly focus on improving single technical features and lack systematic collaborative design for microgravity-level heat dissipation requirements of hundreds of kilowatts. The coupling effects and synergistic mechanisms between various technical modules have not been fully studied and utilized. Summary of the Invention

[0006] The technical problem this invention aims to solve is: how to overcome gas-liquid separation failure and flow pattern instability under microgravity conditions, and achieve stable and reliable heat dissipation at high heat flux densities of hundreds of kilowatts. Specifically, this includes: increasing the boiling critical heat flux density; suppressing pressure oscillations and temperature fluctuations in long-distance two-phase flow transport; reducing system weight and improving overall energy efficiency; and achieving a leap in overall performance that cannot be achieved by simply combining single technologies through deep collaboration of multiple modules.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A multi-module collaborative liquid cooling heat dissipation system adapted to microgravity environments includes: A two-phase mechanical pump circuit module with separate flow, including an evaporator assembly and a condenser, is used to realize the circulation of the working fluid in the main circulation circuit; The EHD pumping module, integrated inside the evaporator assembly, includes an EHD electrode array for applying an electric field to drive the flow of the working fluid. An ultrasonic-assisted breakup module is installed in the flow channel of the evaporator assembly. It is used to emit ultrasonic waves to break large bubbles in the flow channel into microbubbles. The microbubbles are carried away from the heating surface by the directional flow established by the EHD pumping module to prevent them from re-aggregating. A centrifugal gas-liquid separator is installed in the pipeline of the main circulation loop, located downstream of the evaporator assembly, and is used to separate the gas-liquid mixture after ultrasonic pretreatment. The intelligent accumulator and MPC module are respectively connected to the ultrasonic-assisted crushing module, the EHD pumping module and the centrifugal gas-liquid separator, and are used to synchronously and coordinately adjust the working parameters of each module based on the system operating status.

[0008] Furthermore, the EHD electrode array is composed of multiple layers of staggered metal electrodes with an electrode spacing of 0.5-2 mm, an applied voltage of 0-5 kV, and an electric field strength of 10-50 kV / m.

[0009] Furthermore, the EHD electrode array adopts one of the following arrangements: interdigitated electrode arrangement, spiral electrode arrangement, or concentric ring electrode arrangement.

[0010] Furthermore, it also includes an electrowetting control layer, integrated inside the evaporator assembly. The electrowetting control layer consists of an insulating dielectric layer and a hydrophobic coating. By adjusting the voltage of the solid-liquid-gas three-phase contact angle from 0 to 100V, it controls the bubble generation size to be less than 1mm and the detachment frequency to be greater than 100Hz.

[0011] Furthermore, the centrifugal gas-liquid separator is equipped with a spiral guide vane with a spiral angle of 15-45° and a rotation speed of 3000-10000 rpm, generating a centrifugal acceleration that is 10-50 times that of gravity, and a separation efficiency greater than 95%.

[0012] Furthermore, the ultrasonic-assisted breakup module operates at a frequency of 20-100kHz and a power of 10-100W, and is configured to break bubbles with a diameter greater than 2mm into microbubbles with a diameter less than 0.5mm.

[0013] Furthermore, it also includes a gradient aperture capillary wick structure, which is disposed on the heating surface side of the evaporator assembly. The aperture gradually changes from 50-100μm to 200-500μm along the fluid flow direction. It is used to enhance the liquid reflux under microgravity by superimposing the capillary driving force with the electric field driving force of the EHD pumping module.

[0014] Furthermore, it also includes a PCM bubble stabilizing layer, disposed on the wall of the evaporator assembly, using microencapsulated phase change material, with microcapsule diameter of 10-50 μm, phase change temperature of 40-80℃, latent heat of phase change greater than 150 kJ / kg, and a mass fraction of 1-5% of the working fluid, or coated on the evaporator wall with a thickness of 0.5-2 mm; the PCM bubble stabilizing layer absorbs transient overheating energy to provide a response time window for the electrowetting control layer, and the two form a fast-slow synergistic control.

[0015] Furthermore, it also includes a capillary-driven chip-level two-phase flow loop, which is embedded as a secondary heat dissipation unit in a chip heat dissipation path with a local heat flux density greater than 100W / cm². The loop consists of a chip-level microchannel evaporator, a capillary reflux tube, and a chip-level condenser. It does not require external pump drive and forms a thermal backup redundancy with the main circulation loop. The chip heat dissipation path includes a high heat flux density chip.

[0016] Furthermore, the two-phase mechanical pump circuit module for the separated flow also includes a gas-liquid separation accumulator, a mechanical pump, and connecting pipelines; the control logic of the intelligent accumulator and the MPC module is as follows: collect data from the cold plate surface temperature sensor array, with a sampling frequency ≥10Hz, input to the MPC controller, predict the system pressure change in the next 10-60 seconds, adjust the accumulator volume and mechanical pump speed in advance, and control the cold plate surface temperature difference within ±0.5K to ±2K; the working fluid is one of R134a, R245fa, ammonia, deionized water, or perfluorinated carbon working fluid.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Significantly improved critical heat flux density (CHF): Through the synergistic effect of ultrasonic-assisted crushing module 4 and EHD pumping module 2, the microbubbles generated by ultrasonic crushing are quickly carried away from the heating surface by EHD directional flow, effectively suppressing bubble coalescence and gas film formation under microgravity, and increasing CHF by 40-60%.

[0018] (2) Significantly improved flow pattern stability: By using the ultrasonic-assisted crushing module 4 to pre-treat the gas-liquid mixture, and combined with the efficient separation of the centrifugal gas-liquid separator 3, the flow pattern instability problem in long-distance two-phase flow transmission was solved. The system pressure oscillation amplitude was reduced from ±15% to within ±5%, and the surface temperature difference of the cold plate was controlled from ±5K to ±0.5K to ±2K.

[0019] (3) System weight reduction and energy efficiency improvement: The EHD pumping module 2 directly uses electric field force to drive the working fluid, eliminating the dependence on traditional high-power mechanical pumps, and the overall system weight is reduced by more than 40%; the passive reinforcement of gradient pore size capillary core structure 5 and PCM bubble stabilizing layer 6 improves the overall energy efficiency by more than 25%.

[0020] (4) Overall performance leap brought about by multi-module synergy: This invention deeply couples ultrasonic-assisted crushing, EHD pumping, centrifugal separation and MPC intelligent control, resulting in an overall performance leap that cannot be achieved by simply superimposing a single technology module. Specifically, ultrasonic-EHD synergy increases pumping efficiency by an additional 15-25%; ultrasonic-centrifugal synergy increases gas-liquid separation efficiency from 95% to 97-99%; electrowetting-PCM synergy expands dry margin by 3-4 times; capillary-EHD synergy increases liquid reflux reliability under microgravity by 2-3 times; MPC multi-actuator synergy shortens system response time by 60-80%; secondary loop-main loop synergy increases system MTBF from about 500 hours to more than 10,000 hours. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the system architecture of the multi-module collaborative liquid cooling heat dissipation system adapted to microgravity environment according to the present invention; Figure 2 is a schematic diagram of the internal structure of the evaporator assembly; Figure 3 This is a cross-sectional view of the internal structure of a centrifugal gas-liquid separator. Figure 4 A schematic diagram of the gradual pore size change in a gradient pore size capillary core structure; Figure reference numerals: 1-Separated flow two-phase mechanical pump loop module; 11-Evaporator assembly; 12-Gas-liquid separation accumulator; 13-Mechanical pump; 14-Condenser; 15-Connecting pipeline; 2-EHD pumping module; 21-EHD electrode array; 22-Electrowetting control layer; 3-Centrifugal gas-liquid separator; 31-Spiral guide vane; 4-Ultrasonic-assisted crushing module; 5-Gradient pore size capillary wick structure; 6-PCM bubble stabilizing layer; 7-Intelligent accumulator and MPC module; 8-Capillary force driven chip-level two-phase flow loop; 81-Chip-level microchannel evaporator; 82-Capillary reflux tube; 83-Chip-level condenser; 84-High heat flux density chip. Detailed Implementation

[0022] This invention provides a multi-module collaborative liquid cooling heat dissipation system adapted to microgravity environments, the overall architecture of which is as follows: Figure 1 As shown, the core modules include a two-phase mechanical pump loop module 1, an EHD pumping module 2, a centrifugal gas-liquid separator 3, an ultrasonic-assisted fragmentation module 4, and an intelligent accumulator and MPC module 7. As a further optimization, the system may also include a gradient aperture capillary wick structure 5, a PCM bubble stabilizing layer 6, and a capillary-driven chip-level two-phase flow loop 8. The core innovation of this invention lies in the deep coupling and collaborative operation of multiple technical modules to form a multi-physics field synergistic enhancement mechanism, solving problems such as gas-liquid separation failure, flow pattern instability, and system drying under microgravity conditions, and achieving stable and efficient heat dissipation for hundreds of kilowatt-level heat loads.

[0023] The two-phase mechanical pump loop module 1 with separate flow is the main circulation architecture of the entire system, such as... Figure 1 As shown, the system includes an evaporator assembly 11, a condenser 14, a gas-liquid separation accumulator 12, a mechanical pump 13, and connecting pipes 15. The mechanical pump 13 provides the basic driving force for the working fluid to circulate in the main loop. The gas-liquid separation accumulator 12 buffers system pressure fluctuations and assists in gas-liquid separation. The condenser 14 condenses the separated pure vapor into liquid, completing the final heat dissipation. The connecting pipes 15 connect the various components of the main loop, forming a closed loop. Under normal operating conditions, the mechanical pump 13 drives the working fluid to circulate in the main loop. After absorbing heat from the evaporator chip within the evaporator assembly 11, the working fluid boils and generates vapor, forming a gas-liquid two-phase flow.

[0024] The EHD pumping module 2, integrated within the evaporator assembly 11, is one of the core innovative modules of this system. Its internal structure, as shown in Figure 2, includes an EHD electrode array 21 composed of multiple layers of staggered metal electrodes. The electrode material can be conductive metals such as copper, gold, titanium, or aluminum, and the electrode spacing can be 0.5 mm, 1 mm, or 2 mm, preferably 1 mm. When a voltage of 0-5 kV is applied, such as 3 kV, an electric field strength of 10-50 kV / m, such as 30 kV / m, can be generated between the electrodes. This electric field directly acts on the free charges in the working fluid, generating volume forces to drive the directional flow of the working fluid, with a flow velocity reaching 0.5-2 m / s. The electric field driving force provided by the EHD pumping can partially or completely replace the driving function of the mechanical pump 13. When the EHD pumping provides sufficient driving force, the mechanical pump 13 can stop working, resulting in an overall system weight reduction of over 40%.

[0025] As an alternative, the EHD electrode array 21 can also adopt one of the following arrangements: interdigitated electrode arrangement, spiral electrode arrangement, or concentric ring electrode arrangement. In the interdigitated electrode arrangement, the interdigitated width is 0.2-0.5 mm, the interdigitated spacing is 0.5-1.5 mm, and a voltage of 1-4 kV is applied to generate a non-uniform electric field to enhance local working fluid driving. In the spiral electrode arrangement, titanium electrodes are spirally wound along the evaporator channel wall with a pitch of 5-15 mm, and a voltage of 2-5 kV is applied to generate a rotating electric field within the channel. In the concentric ring electrode arrangement, concentric ring-shaped aluminum electrodes are arranged above the circular evaporator heating surface with a ring spacing of 1-3 mm, and a voltage of 0.5-3 kV is applied to generate a radial electric field that drives bubbles to move from the center to the edge. All of these variant arrangements can achieve the basic function of EHD driving working fluid flow, and each has its own applicable advantages depending on the evaporator geometry and channel design.

[0026] As a further optimization, as shown in Figure 2, the system also includes an electrowetting control layer 22, integrated inside the evaporator assembly 11. The electrowetting control layer 22 consists of an insulating dielectric layer and a hydrophobic coating. The insulating dielectric layer can be made of polyimide or silicon dioxide with a thickness of 30-80 μm, preferably 50 μm; the hydrophobic coating can be made of Teflon or Cytop fluorinated polymer with a thickness of 3-10 μm, preferably 5 μm. By adjusting the voltage of the solid-liquid-gas three-phase contact angle from 0-100V, for example 60V or 80V, the contact angle can be changed from 120° (hydrophobic state) to 60° (hydrophilic state), controlling the bubble formation size to be less than 0.8 mm and the detachment frequency to reach 150 Hz with a millisecond-level response speed. This bubble behavior regulation mechanism fundamentally inhibits the coalescence of bubbles on the heating surface under microgravity, preventing the formation of a gas film, thereby increasing the boiling critical heat flux density (CHF) from about 100 W / cm² to 160 W / cm², an increase of 60%.

[0027] As shown in Figure 2, the ultrasonic-assisted cavitation module 4, installed within the flow channel of the evaporator assembly 11, addresses the problem of large bubbles coalescing and forming slug flows under microgravity. The module operates at frequencies ranging from 20-100kHz, with options for 40kHz, 60kHz, or 80kHz; and at power ranging from 10-100W, with options for 30W or 50W. The parameters are selected based on the following: the frequency must match the resonant frequency of the target bubble size (diameter greater than 2mm) to achieve optimal cavitation disruption efficiency; the power is adjusted according to the required number of bubbles to be disrupted. When slug flows with bubbles larger than 2mm in diameter appear in the flow channel, the ultrasonic waves break them into microbubbles with a diameter less than 0.3mm within 0.1 seconds, increasing the heat transfer coefficient from approximately 5000W / (m²·K) to 7500W / (m²·K), an improvement of 30-50%.

[0028] The ultrasonic-assisted fragmentation module 4 and the EHD pumping module 2 form a core first synergistic effect. In microgravity environments, large bubbles in the flow channel significantly increase flow resistance and disrupt the electric field distribution, reducing the driving efficiency of EHD pumping. After the ultrasonic-assisted fragmentation module 4 breaks bubbles larger than 2 mm in diameter into microbubbles smaller than 0.5 mm, the uniformity of the gas-liquid two-phase flow in the flow channel is significantly improved. The microbubbles respond more uniformly to the electric field, reducing the liquid flow resistance driven by EHD volume forces by approximately 20%, and increasing the flow velocity from 0.5 m / s to over 0.6 m / s at the same 3 kV voltage. Simultaneously, the directional flow established by EHD pumping rapidly carries the ultrasonically fragmented microbubbles away from the heating surface, preventing them from re-aggregating and forming a gas film within 0.5 seconds. This synergistic effect results in an additional 15-25% increase in EHD pumping efficiency and significantly enhanced system flow stability, ensuring continuous and stable heat dissipation for hundreds of kilowatt-level heat loads.

[0029] A second synergistic effect is formed between the ultrasonic-assisted fragmentation module 4 and the centrifugal gas-liquid separator 3. The centrifugal gas-liquid separator 3 is located in the main circulation loop, downstream of the evaporator assembly 11, and its internal structure is as follows: Figure 3 As shown, it is equipped with a spiral guide vane 31, with a spiral angle selectable of 15°, 30°, or 45°, preferably 30°. The rotational speed range is 3000-10000 rpm, for example 5000 rpm or 8000 rpm, which can generate a centrifugal field with 10-50 times the acceleration of gravity. After pretreatment by the ultrasonic-assisted crushing module 4, the bubble diameter of the gas-liquid mixture has been reduced to below 0.3 mm. The separation path of microbubbles in the centrifugal acceleration field is shorter and the separation speed is faster, significantly reducing the separation load of the centrifugal separator. The overall separation efficiency of the gas-liquid mixture after ultrasonic pretreatment in the centrifugal gas-liquid separator 3 is increased from about 90-95% in single centrifugal separation to 97-99%. At the same time, ultrasonic crushing suppresses the formation of slug flow, making the flow pattern entering the separator more stable, avoiding the impact of slug flow on the rotating parts of the separator, and extending the service life of the separator. The separated pure steam enters the condenser 14 from the top outlet, and the liquid flows back to the evaporator assembly 11 from the bottom outlet. The dryness of the outlet steam can reach more than 95%.

[0030] As a further enhanced technical solution, a gradient pore size capillary wick structure 5 is disposed on the heating surface side of the evaporator assembly 11, and its pore size gradient structure is as follows: Figure 4As shown, the capillary wick structure has a pore size that gradually changes from 50-100 μm (e.g., 80 μm) to 200-500 μm (e.g., 300 μm) along the fluid flow direction. It is made of sintered copper powder or metal mesh and has a porosity of 60-70%. The large pore size at the evaporation end reduces liquid flow resistance, while the small pore size at the condensation end provides high capillary pressure, forming a capillary reflux driving force from the condensation end to the evaporation end. The capillary driving force generated by this structure can reach 5000 Pa, which is 50% higher than that of a capillary wick with uniform pore size. The gradient pore size capillary wick structure 5 and the EHD pumping module 2 form a synergistic enhanced liquid reflux mechanism. The capillary driving force provided by the capillary wick is about 5000 Pa, which is in the same direction as the volume driving force provided by the EHD electric field. The superposition of the two increases the liquid replenishment of the evaporator heating surface by about 30% and expands the drying margin by 2-3 times.

[0031] As another further enhanced technical solution, the PCM bubble stabilizing layer 6 is disposed on the wall of the evaporator assembly 11, and its integrated layout is shown in Figure 2. This bubble stabilizing layer uses microencapsulated phase change material, which can be paraffin, fatty acids, or low-melting-point metal alloys (such as Wood's alloy, with a melting point of approximately 70°C). The microcapsule diameter is 10-50 μm, preferably 20 μm; the phase change temperature is 40-80°C, preferably 60°C; and the latent heat of phase change is greater than 150 kJ / kg, preferably 200 kJ / kg. The PCM bubble stabilizing layer 6 can be implemented in two ways: one is to incorporate the microcapsules into the working fluid at a mass fraction of 1-5% (e.g., 3%); the other is to mix the PCM microcapsules with a thermally conductive adhesive and then coat them onto the evaporator wall, with a coating thickness of 0.5-2 mm. The PCM bubble stabilizing layer 6 and the electrowetting control layer 22 form a fast-slow synergistic bubble control mechanism. When the computing load increases from 50 W / cm² to 150 W / cm², the PCM bubble stabilizing layer 6 first absorbs the transient overheating energy within 0.3 seconds, providing the electrowetting control layer 22 with a response time window of approximately 1 second. The electrowetting control layer 22 then adjusts the contact angle from 120° to 70°, restoring the bubble generation process to a steady state. This fast-slow collaborative control mechanism further increases the drying margin by 3-4 times, and reduces the temperature overshoot from ±3K to within ±0.5K.

[0032] The intelligent accumulator and MPC module 7 are connected to the split-flow two-phase mechanical pump loop module 1 to quickly adjust the system pressure when the computing load changes abruptly. Their system architecture is as follows: Figure 1As shown. The control logic of this module is as follows: It collects data from the cold plate surface temperature sensor array (sampling frequency ≥ 10Hz) and inputs it into the MPC controller. The MPC controller establishes a multi-input multi-output (MIMO) dynamic model of the system and simultaneously adjusts multiple actuators, including the voltage of the EHD electrode array 21, the power of the ultrasonic-assisted crushing module 4, the speed of the mechanical pump 13, and the volume of the intelligent accumulator. When the computing load increases from 50kW to 100kW, the MPC controller, based on the temperature sensor array data and load change trend, predicts the system pressure fluctuation in the next 30 seconds and coordinates an increase in the EHD voltage from 3kV to 4kV and the ultrasonic power from 30W to 50W 2 seconds in advance, while simultaneously pre-adjusting the accumulator volume by 10%. The coordinated action of multiple actuators avoids the oscillation and lag problems of a single control loop. The system response time is shortened from approximately 8 seconds in traditional single-loop PID control to less than 2 seconds, and the temperature difference fluctuation of the cold plate surface is reduced by 60-80%, ultimately controlled within ±0.5K to ±2K. In addition to the MPC control algorithm, this module can also be replaced by advanced control strategies with multivariable coordination capabilities, such as adaptive fuzzy PID control, sliding mode variable structure control, or neural network predictive control.

[0033] As a redundancy solution to cope with extreme failure conditions, the capillary-driven chip-level two-phase flow loop 8 serves as a secondary heat dissipation unit, embedding a chip heat dissipation path with a local heat flux density greater than 100W / cm². Its system architecture position is as follows: Figure 1 As shown, the chip heat dissipation path includes a high heat flux density chip 84. The capillary-driven chip-level two-phase flow loop 8 consists of a chip-level microchannel evaporator 81, a capillary reflux tube 82, and a chip-level condenser 83, requiring no external pump. The chip-level microchannel evaporator 81 is arranged close to the high heat flux density chip 84 for efficient heat absorption. The capillary reflux tube 82 uses capillary force to drive the liquid working fluid back from the chip-level condenser 83 to the chip-level microchannel evaporator 81. Under normal operating conditions, this secondary loop diverts heat from the high heat flux density chip 84, reducing the thermal load pressure of the main loop. When the main loop fails due to mechanical pump 13 malfunction, pipe blockage, or power failure, the secondary loop can operate independently without external pump, providing continuous emergency heat dissipation for the high heat flux density chip 84. The two-stage loop forms a thermal backup redundancy design, increasing the system's mean time between failures (MTBF) from approximately 500 hours for a single loop to over 10,000 hours, improving reliability by two orders of magnitude.

[0034] Explanation of the synergistic effect of each module The core innovation of this invention lies in the deep coupling of the ultrasonic-assisted fragmentation module 4, the intelligent accumulator and MPC module 7, and the capillary-driven chip-level two-phase flow loop 8 with the EHD pumping module 2, the electrowetting control layer 22, the centrifugal gas-liquid separator 3, the gradient pore size capillary core structure 5, and the PCM bubble stabilizing layer 6, forming a multi-physics field synergistic enhancement mechanism to achieve a leap in the overall system performance. The synergistic effects between the modules are explained in detail below:

[0035] (1) Synergistic effect of ultrasonic-assisted fragmentation and EHD pumping In microgravity environments, large air bubbles within the flow channel significantly increase flow resistance and disrupt the electric field distribution, reducing the driving efficiency of EHD pumping. The ultrasonic-assisted fragmentation module 4 breaks bubbles larger than 2 mm in diameter into microbubbles smaller than 0.5 mm, significantly improving the uniformity of the gas-liquid two-phase flow within the flow channel. The microbubbles respond more uniformly to the electric field, significantly enhancing the stability of the liquid flow driven by EHD volume forces. Simultaneously, the directional flow established by the EHD pumping module 2 rapidly carries the ultrasonically fragmented microbubbles away from the heating surface, preventing them from re-aggregating and forming a gas film near the heating surface. The synergistic effect of these two components increases EHD pumping efficiency by 15-25%, significantly enhancing system flow stability and ensuring continuous and stable heat dissipation for hundreds of kilowatt-level heat loads.

[0036] (2) Synergistic effect of ultrasonic-assisted disruption and centrifugal gas-liquid separation The ultrasonic-assisted disruption module 4 pre-treats the gas-liquid mixture, significantly reducing the bubble diameter entering the centrifugal gas-liquid separator 3. Microbubbles have shorter separation paths and faster separation speeds in the centrifugal acceleration field, significantly reducing the separation load on the centrifugal separator. The overall separation efficiency of the gas-liquid mixture in the centrifugal gas-liquid separator 3 after ultrasonic pre-treatment increases from 90-95% in single centrifugal separation to 97-99%. Simultaneously, ultrasonic disruption suppresses slug flow formation, making the flow pattern entering the separator more stable, avoiding the impact of slug flow on the rotating components of the separator, and extending the separator's service life.

[0037] (3) Synergistic effect of electrowetting control and PCM foam stabilizing layer The electrowetting control layer 22 dynamically adjusts the solid-liquid-gas three-phase contact angle to control the bubble formation size and detachment frequency with a millisecond-level response speed. The PCM bubble stabilizing layer 6 absorbs transient thermal shock energy on a second-level timescale through the phase change endothermic characteristics of the microencapsulated phase change material. When the computing load undergoes a step change, the PCM bubble stabilizing layer 6 first absorbs the transient overheating energy, providing a 0.5-2 second response time window for the electrowetting control layer 22. The electrowetting control layer 22 then precisely adjusts the bubble behavior to restore the bubble formation process to a steady state. The fast-slow collaborative control mechanism of the two significantly improves the stability of bubble formation, and the drying margin is further increased by 3-4 times from the expansion effect of a single technology.

[0038] (4) Synergistic effect of gradient aperture capillary core and EHD pumping The gradient-aperture capillary wick structure 5 features pore sizes that gradually transition from 50-100 μm to 200-500 μm along the fluid flow direction. The larger pore size at the evaporation end reduces liquid flow resistance, while the smaller pore size at the condensation end provides high capillary pressure, creating a capillary reflux driving force from the condensation end to the evaporation end. The electric field volume driving force provided by the EHD pumping module 2, combined with the capillary force of the capillary wick, creates a superposition effect. Both drive in the same direction, jointly enhancing liquid reflux under microgravity. In microgravity, a single capillary force may be insufficient to overcome the flow resistance of long-distance loops; the supplementary EHD driving force ensures continuous and stable liquid reflux to the evaporation end. The synergistic effect of both significantly improves the reliability of liquid reflux under microgravity, expanding the critical heat flux density for drying by 2-3 times.

[0039] (5) Synergistic effect of MPC intelligent control and various execution modules The intelligent accumulator and MPC module 7 establish a multi-input multi-output (MIMO) dynamic model for the system, simultaneously adjusting multiple actuators such as the voltage of the EHD electrode array 21, the power of the ultrasonic-assisted crushing module 4, the speed of the mechanical pump 13, and the volume of the intelligent accumulator. When the computing load increases dramatically, the MPC controller predicts system pressure fluctuations over the next 10-60 seconds based on temperature sensor array data and load change trends. It proactively coordinates increases in EHD voltage and ultrasonic power to enhance bubble control and liquid drive, while simultaneously adjusting the accumulator volume to absorb pressure shocks. This coordinated action of multiple actuators avoids the oscillation and lag problems of a single control loop, reducing the system response time from 5-10 seconds in traditional single-loop PID control to 1-3 seconds, and reducing surface temperature fluctuations of the cold plate by 60-80%.

[0040] (6) Synergistic effect between secondary capillary emergency circuit and main circuit Under normal operating conditions, the capillary-driven chip-level two-phase flow loop 8 serves as a secondary heat dissipation unit, diverting chip heat with a local heat flux density greater than 100 W / cm², thus reducing the thermal load pressure on the main loop. When the main loop fails due to mechanical pump 13 malfunction, pipe blockage, or power supply abnormality, the secondary capillary emergency loop can operate independently without external pump drive, providing continuous emergency heat dissipation for high heat flux density chips. The two-stage loop forms a thermal backup redundancy design, increasing the system's mean time between failures (MTBF) from approximately 500 hours for a single loop to over 10,000 hours, improving reliability by two orders of magnitude.

[0041] Overall system operation process The complete working process of this system is as follows: First, the EHD pumping module 2 is started, and an initial electric field, such as a 3kV voltage, is applied to its EHD electrode array 21, generating an electric field strength of approximately 30kV / m between the electrodes. This drives the working fluid to establish a stable flow in the main circulation loop, with a flow rate of 0.5-2m / s. Then, the chip begins to heat up, and the working fluid absorbs heat in the evaporator assembly 11, boils, and generates bubbles, forming a gas-liquid two-phase flow. During this process, the electrowetting control layer 22 monitors the bubble size in real time. When the bubble diameter exceeds 1mm, the solid-liquid-gas three-phase contact angle is adjusted by applying a 60-80V voltage, forcing the bubbles to detach when their size is less than 0.8mm, thus inhibiting bubble coalescence and gas film formation. When load fluctuations intensify, slug flow occurs in the flow channel, or large bubbles with a diameter greater than 2mm coalesce, the ultrasonic-assisted breaking module 4 is activated. At a frequency of 40-80kHz and a power of 30-50W, the large bubbles are broken into microbubbles with a diameter less than 0.3mm within 0.1 seconds. The broken microbubbles are rapidly carried away from the heating surface by the directional flow established by the EHD pump module 2, preventing them from re-aggregating. The gas-liquid mixture containing microbubbles then enters the centrifugal gas-liquid separator 3. In the rotating flow field generated by the spiral guide vane 31, efficient gas-liquid separation is achieved with a speed of 5000-8000 rpm and a centrifugal force of 10-50 times the acceleration of gravity, with a separation efficiency of 97-99%. Pure steam enters the condenser 14 and is condensed into liquid. The liquid flows back to the evaporator assembly 11 through the connecting pipe 15 to continue the cycle. (…omitted…) When the main circulation loop fails due to mechanical pump 13 failure, pipe blockage, or power failure, the capillary-driven chip-level two-phase flow loop 8 can start automatically without external pump drive. The chip-level microchannel evaporator 81 is in close contact with the high heat flux density chip 84 to absorb the chip heat. The capillary return pipe 82 uses capillary force to drive the working fluid circulation, and the chip-level condenser 83 completes heat dissipation, providing uninterrupted emergency heat dissipation for the high heat flux density chip 84. Through the organic synergy of the above processes, this system achieves stable, efficient, and reliable heat dissipation of hundreds of kilowatt-level heat loads under microgravity conditions.

[0042] Variant implementation Many technical features of this invention can be flexibly replaced and adjusted to expand the scope of protection and adapt to different application scenarios. Several modified embodiments are provided below, all of which fall within the protection scope of this invention.

[0043] Variation 1: EHD Electrode Array Arrangement In addition to the multi-layered staggered metal electrodes mentioned above, the EHD electrode array 21 can also adopt the following arrangement: (a) Interdigitated electrode arrangement: Interdigitated gold electrodes are arranged on the bottom surface of the evaporator channel, with an interdigitated width of 0.2-0.5 mm and an interdigitated spacing of 0.5-1.5 mm. A voltage of 1-4 kV is applied to generate a non-uniform electric field to enhance the local working fluid drive; (b) Spiral electrode arrangement: Titanium electrodes are spirally wound along the wall of the evaporator channel with a pitch of 5-15 mm. A voltage of 2-5 kV is applied to generate a rotating electric field in the channel to enhance the stirring effect of the gas-liquid two-phase flow; (c) Concentric ring electrode arrangement: Concentric ring aluminum electrodes are arranged above the heating surface of the circular evaporator with a ring spacing of 1-3 mm. A voltage of 0.5-3 kV is applied to generate a radial electric field to drive the bubbles to move from the center to the edge and detach. All of the above-mentioned modified arrangements can achieve the basic function of EHD driving the working fluid flow, and each has its own applicable advantages depending on the evaporator geometry and flow channel design, and all fall within the protection scope of this invention.

[0044] Variation 2: Multi-working-medium applicability In addition to the aforementioned R134a working fluid, the system described in this invention may also employ the following working fluids: (a) R245fa: suitable for medium-temperature heat dissipation scenarios of 60-100℃, with lower saturation pressure and reduced system pressure requirements; (b) Ammonia (NH3): suitable for wide temperature range scenarios of -30℃ to 80℃, with high latent heat (approximately 1300kJ / kg) and high heat exchange efficiency, but material compatibility must be considered; (c) Deionized water: suitable for high-temperature heat dissipation scenarios of 100-150℃, with low cost and good environmental performance, but anti-corrosion measures are required; (d) Perfluorinated carbon working fluids (such as FC-72): suitable for extremely high heat flux density scenarios, with high dielectric constant and good coupling effect with EHD electric field. The parameters such as EHD electric field strength, electrowetting voltage, ultrasonic frequency, and PCM phase transition temperature corresponding to different working fluids need to be adjusted accordingly, and the adjustment methods are well known to those skilled in the art.

[0045] Variation 3: Implementation Form of PCM Foam Stabilizing Layer In addition to the above-mentioned microcapsule incorporation into the working fluid, the PCM stabilizing layer 6 can also be implemented in the following ways: (a) wall coating: PCM microcapsules are mixed with thermally conductive adhesive and coated on the evaporator wall with a coating thickness of 0.5-2 mm. This method is convenient for maintenance and replacement; (b) porous matrix composite: PCM is immersed in a sintered metal porous matrix (porosity 50-80%) to form a composite stabilizing layer, which has both high thermal conductivity and large heat capacity; (c) metal phase change material: a low-melting-point metal alloy (such as Wood's alloy, melting point about 70°C) is used as the phase change material. Its thermal conductivity is much higher than that of organic PCM, and its phase change endothermic response is faster.

[0046] Variation 4: Alternative Control Algorithms In addition to the above-mentioned MPC control algorithm, the intelligent accumulator and MPC module 7 can also adopt the following control strategies: (a) Adaptive fuzzy PID control: Adjusts PID parameters in real time according to bubble size and temperature deviation, which is suitable for scenarios with large model uncertainty; (b) Sliding mode variable structure control: Has strong robustness to system parameter disturbances and external disturbances, which is suitable for microgravity environment parameter drift scenarios; (c) Neural network predictive control: Utilizes neural networks to establish a nonlinear model of the system, which is suitable for a wide range of nonlinear working conditions.

[0047] The working fluid selection of this invention has wide adaptability, and can be selected from R134a, R245fa, ammonia, deionized water, or perfluorinated carbon working fluids (such as FC-72) according to different temperature ranges and scenarios. Those skilled in the art can flexibly select the working fluid according to actual needs and adjust parameters such as EHD electric field strength, electrowetting voltage, ultrasonic frequency, and PCM phase transition temperature accordingly.

[0048] It should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-module collaborative liquid cooling heat dissipation system adapted to microgravity environments, characterized in that, include: A two-phase mechanical pump loop module (1) with separate flow includes an evaporator assembly (11) and a condenser (14) for realizing the circulation of the working fluid in the main circulation loop; EHD pumping module (2), integrated inside the evaporator assembly (11), includes an EHD electrode array (21) for applying an electric field to drive the flow of the working fluid; The ultrasonic-assisted breaking module (4) is set in the flow channel of the evaporator assembly (11) and is used to emit ultrasonic waves to break large bubbles in the flow channel into micro bubbles. The micro bubbles are carried away from the heating surface under the directional flow established by the EHD pumping module (2) to prevent them from re-aggregating. A centrifugal gas-liquid separator (3) is installed in the pipeline of the main circulation loop, located downstream of the evaporator assembly (11), and is used to separate the gas-liquid mixture after ultrasonic pretreatment. The intelligent accumulator and MPC module (7) are respectively connected to the ultrasonic-assisted crushing module (4), the EHD pumping module (2) and the centrifugal gas-liquid separator (3) to synchronously coordinate and adjust the working parameters of each module based on the system operating status.

2. The liquid cooling heat dissipation system according to claim 1, characterized in that, The EHD electrode array (21) is composed of multiple layers of staggered metal electrodes with an electrode spacing of 0.5-2mm, an applied voltage of 0-5kV, and an electric field strength of 10-50kV / m.

3. The liquid cooling heat dissipation system according to claim 1, characterized in that, The EHD electrode array (21) adopts one of the following: interdigitated electrode arrangement, spiral electrode arrangement, or concentric ring electrode arrangement.

4. The liquid cooling heat dissipation system according to claim 1, characterized in that, It also includes an electrowetting control layer (22), which is integrated inside the evaporator assembly (11). The electrowetting control layer (22) is composed of an insulating dielectric layer and a hydrophobic coating. By adjusting the voltage of the solid-liquid-gas three-phase contact angle from 0 to 100V, the generation size of the bubbles is controlled to be less than 1mm and the detachment frequency is greater than 100Hz.

5. The liquid cooling heat dissipation system according to claim 1, characterized in that, The centrifugal gas-liquid separator (3) is equipped with a spiral guide vane (31) with a spiral angle of 15-45° and a rotation speed of 3000-10000 rpm. The centrifugal acceleration generated is 10-50 times that of gravity, and the separation efficiency is greater than 95%.

6. The liquid cooling heat dissipation system according to claim 1, characterized in that, The ultrasonic-assisted breakage module (4) operates at a frequency of 20-100kHz and a power of 10-100W, and is configured to break bubbles with a diameter greater than 2mm into microbubbles with a diameter less than 0.5mm.

7. The liquid cooling heat dissipation system according to claim 1, characterized in that, It also includes a gradient aperture capillary wick structure (5), which is set on the heating surface side of the evaporator assembly (11). The aperture gradually changes from 50-100μm to 200-500μm along the fluid flow direction. It is used to enhance the liquid reflux under microgravity by superimposing the capillary driving force with the electric field driving force of the EHD pumping module (2).

8. The liquid cooling heat dissipation system according to claim 4, characterized in that, It also includes a PCM bubble stabilizing layer (6), which is disposed on the wall of the evaporator assembly (11). It is made of microencapsulated phase change material with a microcapsule diameter of 10-50 μm, a phase change temperature of 40-80℃, a latent heat of phase change greater than 150 kJ / kg, and a mass fraction of 1-5% of the working fluid, or is coated on the evaporator wall with a thickness of 0.5-2 mm. The PCM bubble stabilizing layer (6) absorbs transient overheating energy to provide a response time window for the electrowetting control layer (22), and the two form a fast-slow collaborative control.

9. The liquid cooling heat dissipation system according to claim 1, characterized in that, It also includes a capillary-driven chip-level two-phase flow loop (8), which is embedded as a secondary heat dissipation unit in the chip heat dissipation path with a local heat flux density greater than 100W / cm². The loop consists of a chip-level microchannel evaporator (81), a capillary reflux tube (82), and a chip-level condenser (83). It does not require external pump drive and forms a thermal backup redundancy with the main circulation loop. The chip heat dissipation path includes a high heat flux density chip (84).

10. The liquid cooling heat dissipation system according to claim 1, characterized in that, The two-phase mechanical pump circuit module (1) further includes a gas-liquid separation accumulator (12), a mechanical pump (13), and a connecting pipeline (15); the control logic of the intelligent accumulator and the MPC module (7) is as follows: collect data from the cold plate surface temperature sensor array, with a sampling frequency ≥10Hz, input to the MPC controller, predict the system pressure change in the next 10-60 seconds, adjust the accumulator volume and mechanical pump speed in advance, and control the cold plate surface temperature difference to ±0.5K to ±2K; the working fluid is one of R134a, R245fa, ammonia, deionized water, or perfluorinated carbon working fluid.

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