Composite phase change thermal control system and control method thereof

Abstract

The invention provides a composite phase change thermal control system and a control method thereof.The composite phase change thermal control system integrates a refrigerating system, a phase change energy storage evaporator and a cooling system, and the refrigerating system is used for providing cooling capacity for a phase change material in the phase change energy storage evaporator through a circulating refrigerant; the cooling system is used for circulating cold energy of a phase-change material in the phase-change energy storage evaporator to the heat dissipation equipment through a circulating coolant, and the phase-change material can rapidly absorb and release heat in the melting and solidification process, so that the system can rapidly respond to temperature changes, the energy density and the heat transfer efficiency are remarkably improved, and the service life of the system is prolonged. The cooling system can effectively absorb a large amount of heat in a short time and circulate the heat to heat dissipation equipment, and the requirement for high heat flux of high-power equipment is met. According to the design of the three-medium plate-fin type phase change energy storage evaporator, the structure is compact, the occupied area is small, and the system can achieve efficient heat exchange in a limited space.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal control, and relates to a composite phase change thermal control system for coping with high heat flux density and a control method thereof. Background Art

[0002] With the rapid development of modern technology, various high-performance electronic devices such as lithium-ion batteries, airborne electronic devices, and high-performance computers generate a large amount of heat during operation. If the heat cannot be effectively dissipated, it will lead to a decline in their performance and even pose potential safety hazards. Therefore, it is particularly important to develop an efficient thermal control system.

[0003] In the field of thermal control of electronic devices, existing technical solutions include single-phase cooling technology, heat pipe cooling, spray cooling, and thermoelectric cooling, etc. Single-phase cooling technology transfers and releases heat through the heat conduction of liquids or gases, including air cooling and liquid cooling. Among them, the heat dissipation efficiency of air cooling is relatively low, making it difficult to effectively handle heat sources with high power density. Moreover, the fan generates noise and vibration during operation and is susceptible to environmental temperature due to its dependence on air flow. Liquid cooling systems usually use water or coolant as the cooling medium and require a coolant storage device, which occupies a large area. This not only increases the complexity of the system but also limits its application in environments with limited space. With the continuous increase in the power density of devices, single-phase cooling is prone to reach its heat transfer limit under high heat flux density conditions and is difficult to effectively maintain the device within a safe temperature range. At the same time, the specific heat capacity of single-phase fluids is limited, and a large flow rate is required to meet the heat transfer demand, resulting in an increase in the volume and weight of the system, which is particularly disadvantageous in airborne systems with strict weight and space limitations. Heat pipe cooling refers to the use of the phase change of a liquid to efficiently transfer heat. The heat at the heat source end causes the liquid in the pipe to evaporate into steam, and the steam transfers the heat to the other end through flow in the pipe and releases the heat and condenses into a liquid at the condensation section with a lower temperature. The liquid then returns to the evaporation section through capillary force or gravity, and this cycle repeats. However, the efficiency and performance of heat pipe cooling are easily affected by directionality and gravity, which greatly limits its application in the field of thermal control of electronic devices. Moreover, the manufacturing process of heat pipes is relatively complex and the cost is high. Under extreme conditions, such as extremely high or low temperature conditions, the performance of heat pipes will decline, resulting in poor heat dissipation effects. Spray cooling refers to a technology that sprays coolant in the form of tiny droplets onto a hot surface to absorb and carry away heat. However, it has strict requirements for spraying uniformity and droplet size to ensure effective cooling. In addition, the design and maintenance of the spray system are complex, and problems such as clogging or uneven spraying are likely to occur, which will lead to uneven cooling. Spray cooling also involves issues of liquid consumption and recovery, increasing the operation and maintenance costs of the system. Thermoelectric cooling is a technology that uses the Peltier effect to generate a temperature difference through the drive of an electric current in semiconductor materials to achieve heat transfer. The efficiency of this method is relatively low, and usually a high electrical energy input is required to obtain a significant cooling effect. In addition, the heat generated by the thermoelectric cooling device itself requires additional heat dissipation treatment, with a high cost and limited application range. Especially when dealing with a large heat load, the effect is poor. Summary of the Invention

[0004] In view of the limitations of existing technical solutions in the thermal management of high-performance electronic devices, especially the problem of poor heat dissipation efficiency when dealing with high power density of devices, the present invention proposes a composite phase change thermal control system and its control method.

[0005] The present invention is achieved through the following technical solutions: In a first aspect, the present invention provides a composite phase change thermal control system, comprising: a refrigeration system, a phase change energy storage evaporator, and a cooling system. The refrigeration system is configured to provide cooling capacity for the phase change material in the phase change energy storage evaporator by circulating a refrigerant, and the cooling system is configured to circulate the cooling capacity of the phase change material in the phase change energy storage evaporator to a heat dissipation device through circulating a coolant. The phase change energy storage evaporator includes a first fin, a second fin, and a third fin that are sequentially stacked. Adjacent fins are separated by a metal plate, and a metal plate is provided on the outside of the outermost fin. The space between the first fin and the metal plates on both sides of the first fin forms a refrigerant flow channel, the space formed by the second fin and the metal plates on both sides of the second fin is used to fill the phase change material, and the space between the third fin and the metal plates on both sides of the third fin forms a coolant flow channel.

[0006] Preferably, the refrigeration system includes a condenser, a compressor, and a subcooler. The refrigerant outlet of the phase change energy storage evaporator is connected to the suction port of the compressor, the outlet of the compressor is connected to the inlet of the condenser, the outlet of the condenser is connected to the inlet of the subcooler, and the outlet of the subcooler is connected to the refrigerant inlet of the phase change energy storage evaporator.

[0007] Further, the refrigeration system further includes a first electronic expansion valve and a second electronic expansion valve; the outlet of the condenser is divided into two paths, one path is connected to the hot fluid inlet of the subcooler, and the other path passes through the first electronic expansion valve and is connected to the cold fluid inlet of the subcooler; the hot fluid outlet of the subcooler passes through the second electronic expansion valve and is connected to the refrigerant inlet of the phase change energy storage evaporator, and the cold fluid outlet is connected to the gas supplement port of the compressor.

[0008] Preferably, the cooling system is a pump-driven two-phase cooling system.

[0009] Further, the pump-driven two-phase cooling system includes a liquid reservoir and a solution pump. The coolant outlet of the phase change energy storage evaporator is connected to the liquid inlet of the liquid reservoir, the liquid outlet of the liquid reservoir is connected to the inlet of the solution pump, the outlet of the solution pump is used to connect to the cold plate inlet of the heat dissipation device, the gas-liquid two-phase inlet of the liquid reservoir is used to connect to the cold plate outlet of the heat dissipation device, and the gas outlet of the liquid reservoir is connected to the coolant inlet of the phase change energy storage evaporator.

[0010] Further, the pump-driven two-phase cooling system further includes a regenerator. The outlet of the solution pump is connected to the cold fluid inlet of the regenerator, the cold fluid outlet of the regenerator is used to connect to the cold plate inlet of the heat dissipation device, the hot fluid inlet of the regenerator is used to connect to the cold plate outlet of the heat dissipation device, and the hot fluid outlet of the regenerator is connected to the gas-liquid two-phase inlet of the liquid reservoir.

[0011] Further, a preheater is further included. The cold fluid outlet of the regenerator is connected to the inlet of the preheater, and the outlet of the preheater is used to connect to the cold plate inlet of the heat dissipation device.

[0012] Furthermore, a heating component and a cooling component are provided outside the liquid reservoir.

[0013] In a second aspect, the present invention provides a control method for the composite phase change thermal control system, including: monitoring the cold plate inlet temperature T1 and the cold plate outlet temperature T2 of the heat dissipation device, and comparing T1 and T2 with a preset target temperature T set respectively. When T1 or T2 ≥ T set + T 阈1 , control the cooling system to operate at the maximum coolant flow rate; when T set < T1 or T2 ≤ T set + T 阈2 , gradually reduce the coolant flow rate until T1 = T set or T2 = T set ; when the cooling system operates at the minimum coolant flow rate, if T1 or T2 ≤ T set - T 阈3 , then turn off the cooling system until T1 or T2 ≥ T set + T 阈1 , and then restart the cooling system; where T 阈1 is a preset first threshold, T 阈2 is a preset second threshold, T 阈1 > T 阈2 , and T 阈3 is a preset third threshold.

[0014] Preferably, monitor the pressure P1 at the cold plate inlet of the heat dissipation device. When P1 > P set , cool down the liquid reservoir until P1 = P set ; when P1 < P set , heat up the liquid reservoir until P1 = P set ; where the P set is the saturation pressure of the coolant at the target temperature T set .

[0015] Compared with the prior art, the present invention has the following beneficial effects: The composite phase change thermal control system of the present invention integrates a refrigeration system, a phase change energy storage evaporator, and a cooling system. The refrigeration system is used to provide cooling capacity for the phase change material in the phase change energy storage evaporator by circulating refrigerant. The cooling system is used to circulate the cooling capacity of the phase change material in the phase change energy storage evaporator to the heat dissipation device through circulating coolant. The phase change material can quickly absorb and release heat during the melting and solidification processes, enabling the system to quickly respond to temperature changes, significantly improving the energy density and heat transfer efficiency, allowing the cooling system to effectively absorb a large amount of heat within a short time and circulate it to the heat dissipation device, thereby achieving efficient cooling, which is particularly important for devices requiring high dynamic thermal management (such as high-performance computing devices, power electronic devices, etc.) and meeting the high heat flux density requirements of high-power devices. Therefore, the present invention realizes efficient heat management of high-power heat dissipation devices by utilizing the solid-liquid phase change latent heat of the phase change material and the liquid-gas phase change latent heat of the refrigerant and coolant. At the same time, the design of the three-medium plate-fin type phase change energy storage evaporator of the present invention is compact and has a small footprint, enabling the system to achieve efficient heat exchange within a limited space. This compact structural design reduces the installation space required for the device. At the same time, the miniaturized and modular design makes the system easier to be deployed in existing facilities or expanded and reconfigured according to requirements.

[0016] Furthermore, the refrigeration system of the present invention adopts a vapor compression refrigeration system. Compared with the liquid cooling system, the vapor compression refrigeration system can operate intermittently according to requirements, greatly reducing the power consumption of the compressor.

[0017] Furthermore, the cooling system of the present invention adopts a pump-driven two-phase cooling system, including a liquid reservoir and a solution pump. On the one hand, the liquid reservoir separates the gas-liquid two-phase working medium, making the working medium entering the phase change energy storage evaporator in a gaseous state, which effectively reduces the heat exchange amount between the phase change material and the working medium, thereby realizing the efficient utilization of energy and improving the overall efficiency of the system; on the other hand, the liquid reservoir enhances the stability of the system through its connection with the phase change energy storage evaporator and the solution pump. The solution pump, as the power core of the pump-driven two-phase cooling system, provides the power for the circulation of the working medium. And the driving force provided by the solution pump is relatively large, enabling the composite phase change thermal control system to achieve longer-distance heat transfer.

[0018] Furthermore, the pump-driven two-phase cooling system of the present invention can also include a recuperator and a preheater. By setting the preheater and the recuperator, heating the coolant to make it in a saturated liquid state or a two-phase state before entering the high-power heat dissipation device can improve the heat exchange effect.

[0019] Furthermore, the liquid reservoir of the present invention is provided with a heating component and a cooling component. The temperature of the liquid reservoir can be adjusted through the heating component and the cooling component. By adjusting the temperature of the liquid reservoir, the system pressure can be adjusted, avoiding the deviation of the pressure from the saturation pressure of the cold plate of the heat dissipation device, which may affect the temperature control of the heat dissipation device or cause heat dissipation damage.

[0020] By controlling the temperature of the composite phase change thermal control system of the present invention, effective thermal management of the heat dissipation device is achieved, enabling its temperature to always remain at the target temperature during operation. At the same time, pressure control can ensure that the pressure of the heat dissipation device is maintained at the saturation pressure of the target temperature, preventing the two-phase coolant entering the cold plate of the heat dissipation device from being in a high dryness state or overheating state, which may affect the temperature control of the heat dissipation device. Based on the dual fuzzy PID control strategy of flow rate and pressure, precise adjustment of the inlet and outlet temperatures and pressures of high-power heat dissipation devices is realized, ensuring that the devices operate under the optimal temperature and pressure conditions, and improving the response speed and robustness of the system. Brief Description of the Drawings

[0021] 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 use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 It is the schematic diagram of the composite phase change thermal control system of the present invention; Figure 2 It is the schematic diagram of the three-medium plate-fin type phase change energy storage evaporator of the present invention; (a) is the three-dimensional view; (b) is the front view; Figure 3 It is the schematic diagram of the internal flow channel distribution in the plate-fin type phase change energy storage evaporator of the present invention; (a) is the arrangement of the internal fins in the phase change energy storage evaporator; (b) is the flat fin; Figure 4 It is the schematic diagram of the pump-driven two-phase cooling system of the present invention; Figure 5 It is the schematic diagram of the control principle of the composite phase change thermal control system of the present invention; Figure 6 It is the control flow chart of the composite phase change thermal control system of the present invention.

[0023] In the figure: 1 is a condenser, 2 is a first electronic expansion valve, 3 is a subcooler, 4 is a second electronic expansion valve, 5 is a solenoid valve, 6 is a phase change energy storage evaporator, 7 is a compressor, 8 is a liquid receiver, 9 is a cooling fin, 10 is a heating fin, 11 is a solution pump, 12 is a mass flow meter, 13 is a regenerator, 14 is a preheater, 15 is a cold plate, 16 is a refrigerant outlet, 17 is a refrigerant inlet, 18 is a coolant outlet, 19 is a coolant inlet, 20 is a refrigerant flow channel, 21 is a coolant flow channel, 22 is a phase change material, and 23 is a metal plate. Specific embodiments

[0024] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0025] It should be noted that the process equipment or devices not specifically noted in the following embodiments all adopt conventional equipment or devices in the art.

[0026] It should be noted that the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices. Moreover, unless otherwise stated, the numbering of each method step is only a convenient tool for identifying each method step, rather than a limitation on the arrangement order of each method step or the scope in which the present invention can be implemented. The change or adjustment of their relative relationship, without substantial change in technical content, should also be regarded as the scope in which the present invention can be implemented.

[0027] In addition, it should be noted that the terms "first", "second", etc. of the present invention are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. Moreover, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components.

[0028] As Figure 1As shown in the figure, the composite phase change thermal control system of the present invention includes a refrigeration system, a phase change energy storage evaporator 6, and a cooling system. The refrigerant outlet of the refrigeration system is connected to the refrigerant inlet 17 of the phase change energy storage evaporator 6, and the refrigerant outlet 16 of the phase change energy storage evaporator 6 is connected to the refrigerant inlet of the refrigeration system; the coolant outlet of the cooling system is connected to the coolant inlet 19 of the phase change energy storage evaporator 6, and the coolant outlet 18 of the phase change energy storage evaporator 6 is connected to the coolant inlet of the cooling system. The phase change energy storage evaporator 6 includes a first fin, a second fin, and a third fin stacked in sequence. Adjacent fins are separated by a metal plate 23, and a metal plate 23 is provided on the outside of the outermost fin; the space between the first fin and the metal plates 23 on both sides of the first fin forms a refrigerant flow channel 20, and the space formed by the second fin and the metal plates 23 on both sides of the second fin is used to fill the phase change material 22, and the space between the third fin and the metal plates 23 on both sides of the third fin forms a coolant flow channel 21.

[0029] The main function of the refrigeration system is to provide cooling capacity for the phase change material 22 in the phase change energy storage evaporator 6 by circulating the refrigerant. The function of the cooling system is to circulate the cooling capacity of the phase change material 22 in the phase change energy storage evaporator 6 to the heat dissipation device through circulating the coolant, so as to achieve efficient thermal management. Compared with the traditional water cooling system that uses cold water to cool the coolant, the advantage of the phase change energy storage evaporator 6 using the phase change material 22 is that the phase change material 22 mainly stores and releases heat using latent heat. Latent heat can absorb or release a large amount of energy without significantly changing the temperature during the phase change process, which enables the phase change energy storage evaporator 6 to store more energy in a smaller volume. In addition, this efficient energy transfer method also reduces the demand for water flow, thereby reducing the overall floor area and operating cost of the system.

[0030] In some specific embodiments of the present invention, the refrigeration system is a vapor compression refrigeration system. The vapor compression refrigeration system includes a condenser 1, a compressor 7, and a subcooler 3. The refrigerant outlet 16 of the phase change energy storage evaporator 6 is connected to the suction port of the compressor 7, the outlet of the compressor 7 is connected to the inlet of the condenser 1, the outlet of the condenser 1 is connected to the inlet of the subcooler 3, and the outlet of the subcooler 3 is connected to the refrigerant inlet 17 of the phase change energy storage evaporator 6. The compressor 7 preferably uses a scroll compressor.

[0031] Compared with the liquid cooling system, the vapor compression refrigeration system can operate intermittently according to demand, greatly reducing the power consumption of the compressor.

[0032] In a further preferred embodiment of the present invention, the vapor compression refrigeration system further includes a first electronic expansion valve 2 and a second electronic expansion valve 4; the outlet of the condenser 1 is divided into two paths, one path is connected to the hot fluid inlet of the subcooler 3, and the other path passes through the first electronic expansion valve 2 and is connected to the cold fluid inlet of the subcooler 3; the hot fluid outlet of the subcooler 3 passes through the second electronic expansion valve 4 and is connected to the refrigerant inlet 17 of the phase change energy storage evaporator 6, and the cold fluid outlet is connected to the gas supplement port of the compressor 7.

[0033] In some specific embodiments of the present invention, the cooling system is a pump-driven two-phase cooling system, and the pump-driven two-phase cooling system includes a liquid storage tank 8 and a solution pump 11. The coolant outlet 18 of the phase change energy storage evaporator 6 is connected to the liquid inlet of the liquid storage tank 8, the liquid outlet of the liquid storage tank 8 is connected to the inlet of the solution pump 11, the outlet of the solution pump 11 is used to connect to the inlet of the cold plate 15 of the heat dissipation device, the gas-liquid two-phase inlet of the liquid storage tank 8 is used to connect to the outlet of the cold plate 15 of the heat dissipation device, and the gas outlet of the liquid storage tank 8 is connected to the coolant inlet 19 of the phase change energy storage evaporator 6.

[0034] On the one hand, the liquid storage tank 8 separates the gas-liquid two-phase working medium, so that the working medium entering the phase change energy storage evaporator 6 is gaseous, which effectively reduces the heat exchange amount between the phase change material 22 and the working medium, thereby realizing the efficient utilization of energy and improving the overall efficiency of the system. On the other hand, the liquid storage tank 8 enhances the stability of the system through its connection with the phase change energy storage evaporator 6 and the solution pump 11. The solution pump 11, as the power core of the pump-driven two-phase cooling system, provides the power for the circulation of the working medium.

[0035] In a further preferred embodiment of the present invention, the pump-driven two-phase cooling system further includes a regenerator 13. The outlet of the solution pump 11 is connected to the cold fluid inlet of the regenerator 13, the cold fluid outlet of the regenerator 13 is used to connect to the inlet of the cold plate 15 of the heat dissipation device, the hot fluid inlet of the regenerator 13 is used to connect to the outlet of the cold plate 15 of the heat dissipation device, and the hot fluid outlet of the regenerator 13 is connected to the gas-liquid two-phase inlet of the liquid storage tank 8.

[0036] In a further preferred embodiment of the present invention, a preheater 14 is further included. The cold fluid outlet of the regenerator 13 is connected to the inlet of the preheater 14, and the outlet of the preheater 14 is used to connect to the inlet of the cold plate 15 of the heat dissipation device.

[0037] By providing the preheater 14 and the regenerator 13 to heat the working medium to reach the saturated liquid state or the two-phase state, the heat exchange effect can be improved.

[0038] In a further preferred embodiment of the present invention, a heating component and a cooling component are provided outside the liquid storage device 8. The temperature of the liquid storage device 8 can be adjusted through the heating component and the cooling component. By adjusting the temperature of the liquid storage device 8, the system pressure can be adjusted, avoiding the deviation of the pressure from the saturation pressure of the cold plate 15 of the heat dissipation device, which may affect the temperature control of the heat dissipation device or cause heat dissipation damage.

[0039] The control method of the composite phase change heat control system of the present invention includes: Monitoring the inlet temperature T1 and the outlet temperature T2 of the cold plate 15 of the heat dissipation device, and comparing T1 and T2 with a preset target temperature T set respectively. When T1 or T2 ≥ T set +T 阈1 , controlling the cooling system to operate at the maximum flow rate of the coolant; when T set < T1 or T2 ≤ T set +T 阈2 , gradually reducing the flow rate of the coolant until T1 = T set or T2 = T set ; when the cooling system operates at the minimum flow rate of the coolant, if T1 or T2 ≤ T set -T 阈3 , then shutting down the cooling system until T1 or T2 ≥ T set +T 阈1 , restarting the cooling system; where T 阈1 is a preset first threshold, T 阈2 is a preset second threshold, T 阈1 > T 阈2 , T 阈3 is a preset third threshold.

[0040] In a further preferred embodiment of the present invention, the control method of the composite phase change heat control system further includes: monitoring the pressure P1 at the inlet of the cold plate 15 of the heat dissipation device. When P1 > P set , cooling the liquid storage device 8 until P1 = P set ; when P1 < P set , heating the liquid storage device 8 until P1 = P set ; where the P set is the saturation pressure of the coolant at the target temperature T set .

[0041] The present invention realizes effective thermal management of the heat dissipation device through temperature control, enabling its temperature to always operate at the target temperature. At the same time, pressure control can ensure that the pressure of the heat dissipation device is maintained at the saturation pressure of the target temperature, avoiding the two-phase coolant entering the cold plate 15 from being in a high dryness state or overheating state, which may affect the temperature control of the heat dissipation device.

[0042] Embodiment The composite phase change thermal control system described in this embodiment includes: a refrigeration system, a phase change energy storage evaporator 6, and a cooling system. The refrigeration system is a vapor compression refrigeration system, and the cooling system is a pump-driven two-phase cooling system.

[0043] (1) Vapor compression refrigeration system The vapor compression refrigeration system in this embodiment includes a condenser 1, a compressor 7, a subcooler 3, a first electronic expansion valve 2, and a second electronic expansion valve 4. The outlet of the condenser 1 is divided into two paths. One path is connected to the hot fluid inlet of the subcooler 3, and the other path passes through the first electronic expansion valve 2 and is connected to the cold fluid inlet of the subcooler 3. The cold fluid outlet of the subcooler 3 is connected to the gas injection port of the compressor 7 through a solenoid valve 5. The hot fluid outlet passes through the second electronic expansion valve 4 and is connected to the refrigerant inlet 17 of the phase change energy storage evaporator 6. The refrigerant outlet 16 of the phase change energy storage evaporator 6 is connected to the suction port of the compressor 7. The outlet of the compressor 7 is connected to the inlet of the condenser 1. The first electronic expansion valve 2 and the second electronic expansion valve 4 are both step-type electronic expansion valves.

[0044] The cycle of the vapor compression refrigeration system is divided into a main cycle and an enhanced enthalpy injection cycle. The low-temperature and low-pressure refrigerant vapor enters the suction port of the compressor 7, is compressed non-isentropically into high-temperature and high-pressure refrigerant vapor, and then enters the condenser 1 to exchange heat with the outside air, and the temperature decreases. The low-temperature and high-pressure subcooled liquid refrigerant flows out from the outlet of the condenser 1 and is divided into two paths. The first path of refrigerant (i.e., the refrigerant of the main cycle) enters the hot fluid inlet of the subcooler 3, and the second path of refrigerant enters the cold fluid inlet of the subcooler 3 through the first electronic expansion valve 2. The first path of refrigerant exchanges heat with the second path of refrigerant in the subcooler 3 to further reduce the subcooling degree of the refrigerant before the second electronic expansion valve 4 and improve the refrigeration capacity of the system. At the same time, the second path of refrigerant after heat exchange enters the gas injection port of the compressor 7 through the solenoid valve 5 and mixes with the refrigerant vapor from the phase change energy storage evaporator 6 to complete the enhanced enthalpy injection process. Then the refrigerant of the main cycle enters the second electronic expansion valve 4 for throttling and pressure reduction, and the two-phase refrigerant enters the phase change energy storage evaporator 6 to exchange heat with the phase change material 22 (Phase Change Materials, abbreviated as PCMs), and the temperature increases. Then the low-temperature and low-pressure refrigerant vapor enters the compressor 7 for the next cycle. It should be noted that the vapor compression refrigeration system integrates steam injection technology, that is, the second path of refrigerant enters the gas injection port of the compressor 7 after heat exchange to further improve the system efficiency.

[0045] (2) Pump-driven two-phase cooling system The pump-driven two-phase cooling system includes a liquid reservoir 8, a solution pump 11, a preheater 14 and a regenerator 13. The pump-driven two-phase cooling system circulates the cold energy of the phase change energy storage evaporator 6 to the heat dissipation device through the solution pump 11 to achieve efficient thermal management.

[0046] The coolant outlet 18 of the phase change energy storage evaporator 6 is connected to the liquid inlet of the liquid reservoir 8. The liquid outlet of the liquid reservoir 8 is connected to the inlet of the solution pump 11. The outlet of the solution pump 11 is connected to the cold fluid inlet of the regenerator 13. The cold fluid outlet of the regenerator 13 is connected to the inlet of the preheater 14. The outlet of the preheater 14 is used to connect to the inlet of the cold plate 15 of the heat dissipation device. The hot fluid outlet of the regenerator 13 is connected to the gas-liquid two-phase inlet of the liquid reservoir 8. The hot fluid inlet of the regenerator 13 is used to connect to the outlet of the cold plate 15 of the heat dissipation device. The gas outlet of the liquid reservoir 8 is connected to the coolant inlet 19 of the phase change energy storage evaporator 6. Cooling fins 9 and heating fins 10 are arranged on both sides of the liquid reservoir 8.

[0047] The schematic diagram of the pump-driven two-phase cooling system is as Figure 3As shown in the figure, in the pump-driven two-phase cooling system, the working fluid (coolant) enters the solution pump 11 in a subcooled state. After being pressurized by the solution pump 11, the degree of subcooling increases. Subsequently, it flows into the regenerator 13 and the preheater 14, and the working fluid approaches the saturated state. Then it flows into the heat dissipation device. The flow control valve is adjusted according to the different heat flux densities of different cold plates 15, thereby adjusting the mass flow rate of the working fluid entering the cold plate 15 to achieve precise control of the temperature of the heat dissipation device. After that, the working fluid flows into the regenerator 13 and exchanges heat with the subcooled working fluid flowing out of the solution pump 11, reducing the subcooling degree of the working fluid entering the heat dissipation device and realizing the effective utilization of energy. The gas-liquid two-phase working fluid after heat exchange in the regenerator 13 flows into the accumulator 8 for gas-liquid separation. The liquid is stored in the accumulator 8, and the gas enters the phase change energy storage evaporator 6. At this time, the high-temperature working fluid exchanges heat with the phase change material 22. The phase change material 22 melts and absorbs heat, changing from a solid state to a liquid state. After the temperature of the working fluid is reduced to the subcooled state, it flows into the accumulator 8. The liquid in the accumulator 8 flows out according to the system needs and enters the solution pump 11 to complete the cycle. It should be noted that the accumulator 8 plays a dual role of gas-liquid separator and temperature control in the system. On the one hand, the accumulator 8 separates the gas-liquid two-phase working fluid, making the working fluid entering the phase change energy storage evaporator 6 gaseous, which effectively reduces the heat exchange amount between the phase change material 22 and the working fluid, thereby realizing the efficient utilization of energy and improving the overall efficiency of the system. On the other hand, the accumulator 8 enhances the stability of the system through its connection with the phase change energy storage evaporator 6 and the solution pump 11. The outside of the accumulator 8 is provided with a heating sheet 10 and a cooling sheet 9, and the temperature of the accumulator 8 is precisely controlled through the heating sheet 10 and the cooling sheet 9, thereby adjusting the pressure inside the accumulator 8. This temperature and pressure management mechanism helps to control the subcooling degree of the working fluid at the inlet of the solution pump 11, ensuring that the working fluid entering the solution pump 11 is in a subcooled state and improving the reliability of its operation. This comprehensive design not only improves the energy efficiency of the system but also ensures the reliable operation of the equipment under various working conditions.

[0048] The main functions of each component in the pump-driven two-phase cooling system are as follows: (1) The solution pump 11, as the power core of the pump-driven two-phase cooling system, provides the power for the working fluid circulation; (2) The accumulator 8 improves the system stability, ensures the reliability of the solution pump 11 by controlling the subcooling degree of the working fluid at the inlet of the solution pump 11, and at the same time reduces the heat exchange amount between the phase change material 22 and the working fluid to realize the efficient utilization of energy; (3) The preheater 14 and the regenerator 13, since the heat exchange effect is poor when the working fluid is in a subcooled state, in order to ensure the heat exchange effect, the preheater 14 and the regenerator 13 heat the working fluid to make it reach the saturated state or the two-phase state.

[0049] (3)High-efficiency phase change energy storage evaporator 6 The vapor compression refrigeration system and the pump-driven two-phase cooling system are coupled through a plate-fin phase change energy storage evaporator. The plate-fin phase change energy storage evaporator is a compact and efficient three-medium heat exchange device, which is composed of refrigerant channels 20, phase change material 22 and coolant channels 21 stacked alternately. The fluid circuits and the phase change material 22 are arranged at intervals and connected by metal plates 23, as Figure 2 shown. Arranged in sequence from top to bottom, the phase change material 22 - refrigerant channel 20 - phase change material 22 - coolant channel 21 - phase change material 22 - refrigerant channel 20 - phase change material 22 - coolant channel 21 - phase change material 22.

[0050] Figure 3 The internal flow channel arrangement of the plate-fin phase change energy storage evaporator is shown. The core heat transfer unit is composed of metal plates 23 and enhanced fin assemblies. The phase change energy storage evaporator 6 includes first fins, second fins, and third fins arranged in layers, which are cyclically arranged in the order of first fins, second fins, third fins, second fins, and first fins, and the outermost layer is the second fins. The first fins, second fins, and third fins are all straight fins. Adjacent fins are separated by metal plates 23, and metal plates 23 are arranged on the outer sides of the outermost fins; the space between the first fins and the metal plates 23 on both sides of the first fins forms the refrigerant channel 20, and the space formed by the second fins and the metal plates 23 on both sides of the second fins is used to fill the phase change material 22, and the space between the third fins and the metal plates 23 on both sides of the third fins forms the coolant channel 21. The cavities between two adjacent metal plates 23 are divided into several parallel channels through a parallel fin array, and three functional zones are formed in the plate-fin composite structure: the refrigerant channel 20, the phase change material cold storage layer, and the coolant channel 21. The fin structure effectively expands the contact area at the solid-liquid phase change interface, and at the same time strengthens the convection-conduction coupling heat transfer mechanism between the phase change material 22 and the fluid working medium through multi-level channel topology, significantly improving the overall efficiency of the evaporator.

[0051] Compared with the plate-type phase change energy storage evaporator and the shell-and-tube phase change energy storage evaporator, the plate-fin type phase change energy storage evaporator shows significant advantages in structural design and thermodynamic performance. First, it has a higher heat transfer area and space efficiency: the plate-fin structure expands the heat transfer surface through fins, and the heat transfer area per unit volume is increased by more than about 30% compared with the plate type structure. Moreover, the stacked flow channel design saves 30%-40% of the floor area compared with the shell-and-tube type, meeting the requirements of compact integration; Second, it has better multi-medium compatibility and phase change material 22 utilization rate: the plate-fin structure can flexibly configure alternating layers of multiple working fluids (such as refrigerants, coolants, phase change material 22), and realizes efficient cross-medium coupling through high thermal conductivity metal plates 23. The filling rate of the phase change material 22 is increased by more than 20% compared with the shell-and-tube phase change energy storage evaporator, avoiding the problem of local non-phase change of materials caused by flow dead zones in traditional shell-and-tube phase change energy storage evaporators; Third, it has a faster dynamic heat load response: the heat transfer enhancement characteristics of the fins make the solid-liquid interface movement rate of the phase change material 22 2-3 times faster than that of the plate-type phase change energy storage evaporator.

[0052] The plate-fin type phase change energy storage evaporator has the ability of bidirectional energy regulation. When the phase change energy storage evaporator has a cold storage demand, the vapor compression refrigeration system starts to operate. The low-temperature and low-pressure working fluid (refrigerant) flows into the refrigerant flow channel 20 from the refrigerant inlet 17, and exchanges heat with the high-temperature phase change material 22. The phase change material 22 absorbs the cold quantity and its temperature decreases until it completely solidifies, completing the cold quantity storage. The working fluid after heat exchange flows out from the refrigerant outlet 16, completing the cold storage process; When the phase change energy storage evaporator 6 has a cold release demand, that is, when the temperature of the heat dissipation device is relatively high, the pump-driven two-phase cooling system starts. The high-temperature working fluid (coolant) enters from the coolant inlet 19, and exchanges heat with the phase change material 22 in the coolant flow channel 21. The phase change material 22 absorbs heat and releases cold quantity until it completely melts. The low-temperature working fluid after heat exchange flows out from the coolant outlet 18, completing the cold release process. Through the design of the three-medium plate-fin type phase change energy storage evaporator, the dynamic storage and precise release of cold quantity are realized, which is especially suitable for the active thermal management requirements of intermittent high-load heat dissipation scenarios.

[0053] Compared with the traditional liquid cooling system, the advantages of the three-medium plate-fin type phase change energy storage evaporator mainly include: 1) High-efficiency energy storage dominated by latent heat: The phase change material releases / absorbs latent heat through solid-liquid phase change. The cold storage capacity per unit volume is much higher than the sensible heat exchange of the traditional liquid cooling system, greatly improving the energy density and reducing the equipment volume.

[0054] 2) Simplification of the system structure: The compact design of the plate-fin type combined with the integration of the three-medium flow channels reduces the requirements for auxiliary equipment such as water pumps and pipelines, and reduces the system complexity and floor area; 3) Energy saving and economy: The latent heat exchange reduces the demand for the coolant circulation flow rate. Combined with the intermittent operation characteristics, it can reduce the pump power consumption and operation and maintenance costs by about 30-50%; (4)Intelligent System Control Strategy To achieve effective thermal management of the heat dissipation device and keep its temperature running at the target temperature all the time, the present invention introduces a fuzzy PID control strategy to precisely adjust the pressure and flow rate of the system, so as to achieve the goal of accurate and rapid temperature control. Specifically, this control strategy combines fuzzy logic and PID control, and analyzes the temperature error and the rate of change of the error in real time through fuzzy rules, thereby dynamically adjusting the PID control parameters. According to the instant feedback of the system, fuzzy PID can adaptively optimize the control response, making the temperature regulation more flexible and accurate. This method improves the robustness and response speed of the system, ensures that the heat dissipation device can maintain the optimal temperature state under different working conditions, and enhances its performance and reliability. The control modes of the system include a fuzzy PID control strategy based on flow rate and a fuzzy PID control strategy based on pressure. The two control modes operate simultaneously to separately control the temperature and pressure at the inlet and outlet of the cold plate 15 of the heat dissipation device, so as to achieve rapid heat dissipation and temperature regulation of the device. Refer to Figure 6 , and the specific control mode is as follows: 1) Fuzzy PID Control Strategy Based on Flow Rate As Figure 4 shown, the flow rate control is to adjust the rotation speed of the solution pump 11 in the system. By comparing the set target temperature with the temperatures at the inlet and outlet of the cold plate 15 of the heat dissipation device, the rotation speed of the solution pump 11 is then adjusted in real time by the PID controller to increase / decrease the coolant flow rate, thereby achieving thermal management of the heat dissipation device. The specific control process is as Figure 5 shown. First, set the optimal operating temperature of the heat dissipation device (i.e., the target temperature T set ). When the system monitors that the temperature at the inlet of the cold plate 15 of the heat dissipation device (T1) or the temperature at the outlet of the cold plate 15 (T2) is higher than the target temperature by 2°C (i.e., T1 or T2 ≥ T set +2), the composite phase change thermal control system starts. At this time, the solution pump 11 runs at the maximum rotation speed, and the gaseous coolant enters the phase change energy storage evaporator 6 to exchange heat with the phase change material 22. The cooled coolant enters the cold plate 15 of the heat dissipation device in a saturated liquid state through the liquid storage tank 8, the solution pump 11, the regenerator 13, and the preheater 14 to cool it. When the temperatures at the inlet and outlet of the cold plate 15 of the heat dissipation device drop to be higher than the target temperature by 1°C (i.e., T set <T1 or T2 ≤ T set+1), the composite phase change heat control system enters the capacity adjustment mode. By sequentially reducing the rotational speed of the solution pump 11 (decreasing in sequence from high to low according to the rotational speed range of the solution pump 11), and stabilizing the operation at each rotational speed point for 3 s until the temperatures at the inlet and outlet of the cold plate 15 of the heat dissipation device are monitored to reach the target temperature. At this time, the rotational speed of the solution pump 11 remains unchanged, and the composite phase change heat control system operates stably. When the solution pump 11 is reduced to the lowest rotational speed for operation, if the temperature at the inlet or outlet of the cold plate 15 of the heat dissipation device drops to 1°C below the target temperature (i.e., T1 or T2 ≤ T set -1), and there is a tendency to continue to decrease, then the solution pump 11 is turned off until the temperature at the inlet or outlet of the cold plate 15 of the heat dissipation device is monitored to be 2°C higher than the target temperature, and then the solution pump 11 is restarted.

[0055] (2) Pressure-based fuzzy PID control strategy As Figure 4 shown, when using the flow-based fuzzy PID control strategy to control the temperature of the heat dissipation device, due to the pressure boost of the solution pump 11 and the pressure losses of devices such as the regenerator 13 and the preheater 14, the pressure inside the cold plate 15 of the heat dissipation device is in a fluctuating state. When the pressure deviates from the saturation pressure of the cold plate 15 of the heat dissipation device, the two-phase coolant entering the cold plate 15 of the heat dissipation device is easily in a high dryness state or a superheated state, thereby affecting the temperature control of the heat dissipation device and seriously causing damage to the heat dissipation device in severe cases. Therefore, based on the flow control, the present invention proposes a pressure-based fuzzy PID control strategy to effectively control the pressure at the inlet of the cold plate 15 of the heat dissipation device, so that it always operates at the saturation pressure under the target temperature. The specific control process is as Figure 5 shown. First, determine the optimal operating temperature (i.e., the target temperature) of the heat dissipation device, then the saturation pressure at this target temperature is the target pressure P set , when it is monitored that the pressure (P1) at the inlet of the cold plate 15 of the heat dissipation device deviates from the target pressure, then the pressure control mode is turned on, and the temperature of the liquid storage tank 8 (the function of the liquid storage tank 8 is to adjust the pressure of the liquid storage tank 8 by controlling the temperature of the coolant in the tank) is adjusted through the fuzzy PID controller. When it is monitored that the pressure at the inlet of the cold plate 15 of the heat dissipation device is higher than the target pressure (P1 > P set ), the cooling fin 9 operates to cool down the liquid storage tank 8, thereby reducing the pressure inside the liquid storage tank 8; when it is monitored that the pressure at the inlet of the cold plate 15 of the heat dissipation device is lower than the target pressure (P1 < P set), the heating sheet 10 operates to heat up the liquid reservoir 8, thereby increasing the pressure inside the liquid reservoir 8 until the inlet pressure of the heat dissipation device stabilizes near the target pressure, and the pressure regulation ends. The function of the cooling fin 9 or the heating sheet 10 of the liquid reservoir 8 is to adjust the temperature of the liquid reservoir 8, and further control the pressure at the inlet of the cold plate 15 of the heat dissipation device, so that the coolant always operates at a low dryness or saturated liquid state.

[0056] This embodiment combines vapor compression refrigeration technology, a high-efficiency phase change energy storage evaporator, a pump-driven two-phase cooling system, and an intelligent system control strategy, significantly improving the thermal management efficiency. It can provide a stable and reliable thermal control solution while reducing the system weight and volume.

Claims

1. A composite phase change thermal control system, characterized in that, Comprising: A refrigeration system, a phase change energy storage evaporator, and a cooling system. The refrigeration system is used to provide cooling capacity for the phase change material in the phase change energy storage evaporator by circulating refrigerant, and the cooling system is used to circulate the cooling capacity of the phase change material in the phase change energy storage evaporator to the heat dissipation device through circulating coolant; The phase change energy storage evaporator includes a first fin, a second fin, and a third fin that are sequentially stacked. Adjacent fins are separated by a metal plate, and a metal plate is provided on the outside of the outermost fin. The space between the first fin and the metal plates on both sides of the first fin forms a refrigerant flow channel, the space formed by the second fin and the metal plates on both sides of the second fin is used to fill the phase change material, and the space between the third fin and the metal plates on both sides of the third fin forms a coolant flow channel.

2. The composite phase change thermal control system according to claim 1, characterized in that The refrigeration system includes a condenser, a compressor, and a subcooler. The refrigerant outlet of the phase change energy storage evaporator is connected to the suction port of the compressor, the outlet of the compressor is connected to the inlet of the condenser, the outlet of the condenser is connected to the inlet of the subcooler, and the outlet of the subcooler is connected to the refrigerant inlet of the phase change energy storage evaporator.

3. The composite phase change thermal control system according to claim 2, wherein The refrigeration system further includes a first electronic expansion valve and a second electronic expansion valve; the outlet of the condenser is divided into two paths, one path is connected to the hot fluid inlet of the subcooler, and the other path passes through the first electronic expansion valve and is connected to the cold fluid inlet of the subcooler; the hot fluid outlet of the subcooler passes through the second electronic expansion valve and is connected to the refrigerant inlet of the phase change energy storage evaporator, and the cold fluid outlet is connected to the gas supplement port of the compressor.

4. The composite phase change thermal control system according to claim 1, characterized in that, The cooling system is a pump-driven two-phase cooling system.

5. The composite phase change thermal control system according to claim 4, wherein The pump-driven two-phase cooling system includes a liquid storage tank and a solution pump. The coolant outlet of the phase change energy storage evaporator is connected to the liquid inlet of the liquid storage tank, the liquid outlet of the liquid storage tank is connected to the inlet of the solution pump, the outlet of the solution pump is used to connect to the cold plate inlet of the heat dissipation device, the gas-liquid two-phase inlet of the liquid storage tank is used to connect to the cold plate outlet of the heat dissipation device, and the gas outlet of the liquid storage tank is connected to the coolant inlet of the phase change energy storage evaporator.

6. The composite phase change thermal control system according to claim 5, wherein The pump-driven two-phase cooling system further includes a regenerator. The outlet of the solution pump is connected to the cold fluid inlet of the regenerator, the cold fluid outlet of the regenerator is used to connect to the cold plate inlet of the heat dissipation device, the hot fluid inlet of the regenerator is used to connect to the cold plate outlet of the heat dissipation device, and the hot fluid outlet of the regenerator is connected to the gas-liquid two-phase inlet of the liquid storage tank.

7. The composite phase change thermal control system according to claim 6, wherein It further includes a preheater. The cold fluid outlet of the regenerator is connected to the inlet of the preheater, and the outlet of the preheater is used to connect to the cold plate inlet of the heat dissipation device.

8. The composite phase change thermal control system according to claim 5, wherein A heating component and a cooling component are provided outside the liquid storage tank.

9. The control method of the composite phase change thermal control system according to any one of claims 1-8, characterized in that, Comprising: Monitor the cold plate inlet temperature T1 and the cold plate outlet temperature T2 of the heat dissipation device, and compare T1 and T2 with the preset target temperature T respectively set for comparison. When T1 or T2 ≥ T set + T 阈1 , control the cooling system to operate at the maximum coolant flow rate; when T set < T1 or T2 ≤ T set + T 阈2 , gradually reduce the coolant flow rate until T1 = T set or T2 = T set ; when the cooling system operates at the minimum coolant flow rate, if T1 or T2 ≤ T set - T 阈3 , then turn off the cooling system until T1 or T2 ≥ T set + T 阈1 , and then restart the cooling system; where T 阈1 is the preset first threshold, T 阈2 is the preset second threshold, T 阈1 > T 阈2 , and T 阈3 is the preset third threshold.

10. The control method of the composite phase change thermal control system according to claim 9, characterized in that, Monitor the pressure P1 at the cold plate inlet of the heat dissipation device. When P1 > P set , cool down the liquid reservoir until P1 = P set ; when P1 < P set , heat up the liquid reservoir until P1 = P set ; where the P set is the saturation pressure of the coolant at the target temperature T set .

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