Battery thermal management system combining liquid cooling and phase change immersion cooling and regulation method

Abstract

The application relates to the technical field of battery thermal management, in particular to a battery thermal management system combining liquid cooling and phase change immersion cooling and a regulation and control method, which comprises a heat-conducting shell, a heat-conducting upper cover and composite phase change materials filled in the interspaces of the battery, the bottom surface and the outer side of the periphery of the heat-conducting shell are provided with refrigeration devices, the refrigeration devices comprise two sets, one set is a water circuit, and the other set is a refrigerant circuit, each set of serpentine refrigeration pipes comprises a plurality of refrigeration circuits corresponding to a plurality of regions respectively, and the plurality of refrigeration circuits are parallel refrigeration; in the discharging operation process of the battery, a temperature measuring device acquires temperature data of different regions in real time, and the temperature data are transmitted to a control module in real time, the control module regulates and controls the battery thermal management based on the real-time temperature data, precise temperature control can be realized, the battery temperature can be rapidly reduced, and the thermal management efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of battery thermal management technology, specifically to a battery thermal management system and control method that combines liquid cooling and phase change immersion cooling. Background Technology

[0002] Lithium-ion batteries are core components of new energy vehicles and energy storage systems. Most electric vehicle batteries operate normally within a temperature range of -20°C to 55°C, maintaining optimal performance when the battery temperature is below 45°C. Once the battery temperature reaches or exceeds 60°C, the internal chemical substances may react violently, the electrolyte may decompose and burn, and the separator may melt, leading to thermal runaway and posing serious safety risks such as fire and explosion. Furthermore, to ensure optimal battery performance, the temperature difference within the battery module must be controlled within the specified threshold.

[0003] In recent years, liquid cooling has been increasingly widely used in new energy vehicles and other fields. Liquid cooling systems come into direct contact with battery modules through cooling plates or cooling pipes, using coolant to absorb the heat generated by the battery and maintain the battery within its optimal operating temperature range. However, as battery power increases, liquid cooling is becoming increasingly difficult to meet requirements due to its relatively low heat removal capacity, and the flow of coolant in pipes or cooling plates may be uneven, leading to uneven temperature distribution inside the battery pack.

[0004] Composite phase change materials can absorb a large amount of heat when the temperature reaches the phase change point, and at the same time change from solid to liquid. However, the thermal conductivity of composite phase change materials is usually low, and the heat absorption process of composite phase change materials depends on the phase change temperature, making it impossible to achieve precise temperature control.

[0005] Therefore, research and development are urgently needed to find a way to achieve efficient and precise thermal management of batteries by comprehensively considering temperature uniformity and cooling rate. Summary of the Invention

[0006] To address the aforementioned problems in the background art, this invention provides a battery thermal management system and control method that combines liquid cooling and phase change immersion cooling.

[0007] The technical solution of this invention is as follows:

[0008] A battery thermal management system combining liquid cooling and phase change immersion cooling includes: a heat-conducting shell with a top opening, a heat-conducting top cover disposed on top of the heat-conducting shell, and a composite phase change material filling the gaps in the battery.

[0009] The composite phase change material is divided into several regions of equal area. A temperature measuring device is installed in the composite phase change material in each region. The temperature measuring device is communicatively connected to a controller located outside the heat-conducting shell.

[0010] A refrigeration device is installed on the bottom and outer sides of the heat-conducting shell. The refrigeration device includes two sets of independent and spaced serpentine refrigeration pipes. One set is a water circuit and the other is a refrigerant circuit. Each set of serpentine refrigeration pipes includes several parallel refrigeration circuits, and each refrigeration circuit corresponds to a region.

[0011] A first flow regulator is installed at the water inlet of each refrigeration circuit in the water circuit, and a second flow regulator is installed at the refrigerant inlet of each refrigeration circuit in the refrigerant circuit. Both the first and second flow regulators are communicatively connected to the controller.

[0012] Control module: Used to regulate battery thermal management during battery discharge operation based on real-time temperature data of different areas obtained by the temperature measuring device. The regulation process is as follows:

[0013] The average temperature is obtained by taking the average value of the temperature in each area. If the average temperature is less than or equal to the first temperature, all first flow regulators are controlled to open at a fixed opening degree, and the water circuit flows with the first water flow rate. If the average temperature is greater than the first temperature but less than or equal to the second temperature, the opening degree of all first flow regulators is dynamically adjusted according to the set water flow rate adjustment rules.

[0014] If the average temperature is greater than the second temperature, then all first flow regulators are adjusted to their maximum opening, and all second flow regulators are opened to their maximum opening, until the average temperature is less than the second temperature.

[0015] Specifically, the water flow regulation rule when the average temperature is greater than the first temperature and less than or equal to the second temperature is expressed by the following formula:

[0016]

[0017] Where, N i For different average temperatures T i The opening degree of all first flow regulators, Q i For different average temperatures T i The corresponding adjusted water flow rate, Q max The maximum water flow rate is T, Q1 is the first water flow rate, and T is the maximum water flow rate. i To obtain different average temperatures in real time, T1 <T i << T2; T1 is the first temperature, and T2 is the second temperature.

[0018] During the battery thermal management process, if the average temperature is less than or equal to the first temperature, and the maximum temperature difference between any two regions exceeds the temperature difference threshold, then based on the first water flow rate, the maximum temperature difference, and the set flow rate adjustment, the region with the highest temperature is regulated with the second zone flow rate, while other regions are regulated with the first water flow rate. The formula for the second zone flow rate adjustment is as follows:

[0019]

[0020] Among them, Q v The second partition's traffic is calculated to obtain Q. v When it is greater than 100%, take Q. v It is 100%; Q1 is the first water flow rate, ΔT is the maximum temperature difference, ΔT th q represents the temperature difference threshold, and q represents the flow rate adjustment.

[0021] Specifically, the first flow regulating component is an electric flow regulating valve, and the second flow regulating component is a solenoid valve.

[0022] Specifically, a thermally conductive sealant is provided between the composite phase change material and the thermally conductive top cover inside the thermally conductive housing.

[0023] The temperature measuring device is a thermocouple.

[0024] Furthermore, it also includes an alarm module that communicates with the controller, located outside the heat-conducting housing, to issue an early warning when the average temperature exceeds the second temperature.

[0025] The phase transition temperature of the composite phase change material is 37°C.

[0026] The first temperature is lower than the second temperature.

[0027] The beneficial effects of this invention are as follows:

[0028] 1. The present invention provides a battery thermal management system and control method that combines liquid cooling and phase change immersion cooling. Based on the heat absorption of composite phase change materials, dual-path cooling and control are achieved through a water circuit and a refrigerant circuit. Based on real-time temperature data, the opening degree of the first flow regulator set on the water circuit inlet pipe corresponding to different areas and the second flow regulator set on the refrigerant circuit corresponding to different areas are adjusted to facilitate precise temperature control, which can quickly reduce the battery temperature, effectively improve thermal management efficiency, and ensure that the battery operates within the optimal temperature range.

[0029] 2. Based on real-time temperature data, when the maximum temperature difference between any two regions exceeds the temperature difference threshold, this invention can reduce the temperature difference between different regions by adjusting the water flow rate in different zones, thereby making the temperature distribution in each region inside the battery uniform, thus improving battery performance, extending battery life, and enhancing safety. Attached Figure Description

[0030] In the attached diagram:

[0031] Figure 1 This is a schematic diagram showing the layered layout of the battery thermal management system in the embodiment;

[0032] Figure 2 This is a schematic diagram of the layout of a single set of serpentine cooling pipes in the embodiment;

[0033] The components represented by the various reference numerals in the diagram are:

[0034] 1. Thermally conductive housing; 2. Thermally conductive top cover; 3. Composite phase change material; 4. Battery; 5. Temperature measuring device; 6. Water circuit; 7. Refrigerant circuit; 8. Flow regulating component; 801. First flow regulating component; 802. Second flow regulating component; 10. Thermally conductive sealant. Detailed Implementation

[0035] Exemplary embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings.

[0036] Example

[0037] This embodiment provides a battery thermal management system that combines liquid cooling and phase change immersion cooling. (See attached image) Figure 1 , Figure 2 It includes: a heat-conducting housing 1 with a top opening, a heat-conducting top cover 2 disposed on the top of the heat-conducting housing 1, and a composite phase change material 3 filling the gaps in the battery 4.

[0038] The composite phase change material 3 is divided into several regions of equal area. A temperature measuring device 5 is installed in each region of the composite phase change material 3. The temperature measuring device 5 is communicatively connected to a controller located outside the heat-conducting shell 1.

[0039] A refrigeration device is installed on the bottom surface and the outer sides of the heat-conducting shell 1. The refrigeration device includes two sets of independent and spaced serpentine refrigeration pipes. One set is water circuit 6 and the other set is refrigerant circuit 7. Each set of serpentine refrigeration pipes includes several parallel refrigeration circuits, and each refrigeration circuit corresponds to a region.

[0040] Each refrigeration circuit in water circuit 6 is equipped with a first flow regulator 801 at its water inlet, and each refrigeration circuit in refrigerant circuit 7 is equipped with a second flow regulator 802 at its refrigerant inlet. Both the first flow regulator 801 and the second flow regulator 802 are communicatively connected to the controller.

[0041] Control module: Used to regulate the thermal management of battery 4 during its discharge operation based on real-time temperature data from different areas acquired by temperature measuring device 5. The regulation process is as follows:

[0042] The average temperature is obtained by taking the average value of the temperature of each area. If the average temperature is less than or equal to the first temperature, all first flow regulating components 801 are controlled to open at a fixed opening degree, and water circuit 6 flows water at the first water flow rate. If the average temperature is greater than the first temperature and less than or equal to the second temperature, the opening degree of all first flow regulating components 801 is dynamically adjusted according to the set water flow regulation rules.

[0043] If the average temperature is greater than the second temperature, all first flow regulators 801 are adjusted to their maximum opening, and all second flow regulators 802 are opened to their maximum opening until the average temperature is less than the second temperature.

[0044] Specifically, this embodiment provides a battery thermal management system combining liquid cooling and phase change immersion cooling. Both the thermally conductive shell 1 and the thermally conductive top cover 2 are made of metallic copper, which has high thermal conductivity. The thermally conductive shell 1 serves as an external structural support, and a composite phase change material 3 is disposed inside it. A thermally conductive sealant 10 is disposed between the composite phase change material 3 and the thermally conductive top cover 2. The composite phase change material 3 used in this embodiment is graphene aerogel-reinforced paraffin, with a phase change temperature of 37°C. Under a load of only 12.5 wt% graphene aerogel (HGA) filler, the thermal conductivity before phase change is 0.719 W / m·K, and the thermal conductivity after phase change is 30.75 W / m·K, significantly higher than that of traditional composite phase change materials (such as pure paraffin, which has 0.2-0.5 W / m·K), and the latent heat of phase change is 200 J / g.

[0045] The composite phase change material 3 absorbs heat when the battery 4 generates heat during operation. Upon reaching the phase change temperature, it undergoes a phase change, absorbing heat and melting, changing from a solid to a liquid state. The heat absorbed by the composite phase change material 3 is transferred to the heat-conducting shell 1 via thermal conduction, and then dissipated outwards from the shell. Several batteries 4 are arranged at equal intervals inside the composite phase change material 3. This even spacing ensures uniform heat distribution and prevents heat concentration. All batteries 4 are in close contact with the composite phase change material 3, allowing the heat generated by the batteries 4 to be quickly transferred to the composite phase change material 3, improving heat transfer efficiency.

[0046] A cooling device is installed on the bottom surface and outer perimeter of the heat-conducting shell 1. The cooling device includes two independent, spaced-apart serpentine cooling pipes. Each serpentine cooling pipe is integrally connected and tightly attached to the outer surface of the heat-conducting shell 1. The two cooling pipes are independent, providing redundancy and improving system reliability. The two cooling pipes can actively cool by circulating a cooling medium to remove heat transferred to the heat-conducting shell. To increase the contact area between the cooling pipes and the outer surface of the heat-conducting shell 1 and improve heat dissipation efficiency, both cooling pipes adopt a serpentine design. Simultaneously, both liquid cooling pipes are arranged in a counter-flow manner, with a diameter of 20mm and a wall thickness of 0.2mm. Each serpentine liquid cooling pipe is spaced 30mm apart on the bottom surface of the heat-conducting shell and 40mm apart on the outer perimeter.

[0047] This invention achieves dual heat dissipation by combining the passive heat absorption capacity of the composite phase change material 3 with the active cooling capacity of the cooling pipes. Furthermore, the dual-path cooling pipe design significantly improves the efficiency and reliability of the battery's thermal management. The latent heat of phase change of the composite phase change material 3 absorbs a large amount of heat, significantly reducing the battery temperature. Simultaneously, the uniform distribution of the composite phase change material 3 and the thermal conductivity of the heat-conducting shell contribute to temperature uniformity, preventing localized overheating. The dual-path cooling pipes can achieve precise temperature control through flow regulation, compensating for the insufficient temperature control accuracy of the composite phase change material.

[0048] The present invention further considers zoned control based on temperature differences on the basis of dual heat dissipation. Based on the arrangement of batteries 4, the composite phase change material 3 is divided into several regions of the same area. A temperature measuring device 5 is provided in the composite phase change material 3 in each region. The temperature measuring device 5 can be a thermocouple. The temperature measuring device 5 is communicatively connected to a controller located outside the heat-conducting shell 1 to transmit the measured temperature data to the controller in real time.

[0049] Two sets of serpentine refrigerant pipes are used. One set of serpentine refrigerant pipes carries water (water circuit 6), and the other set carries refrigerant (refrigerant circuit 7). Each set of serpentine refrigerant pipes includes several refrigeration circuits corresponding to several regions, and these circuits refrigerate in parallel.

[0050] In the water circuit 6, a first flow regulator 801 is installed at the bottom of the refrigeration circuit and its inlet pipe connection in each area. The first flow regulator 801 is an electric flow regulator valve. In the refrigerant circuit, a second flow regulator 802 is installed at the bottom of the refrigeration circuit and its inlet pipe connection in each area. The second flow regulator 802 is a solenoid valve.

[0051] During the discharge operation of battery 4, the temperature measuring device 5 acquires the temperature data of the composite phase change material 3 in different regions in real time and transmits the temperature data to the control module in real time. Based on the received temperature data, the control module adjusts the thermal management of battery 4. The adjustment process is as follows:

[0052] The average temperature is obtained by taking the average value of the temperature of each area. If the average temperature is less than or equal to the first temperature, all first flow regulating components 801 are controlled to open at a fixed opening degree, and water circuit 6 flows water at the first water flow rate. If the average temperature is greater than the first temperature and less than or equal to the second temperature, the opening degree of all first flow regulating components 801 is dynamically adjusted according to the set water flow regulation rules.

[0053] If the average temperature is greater than the second temperature, all first flow regulators 801 are adjusted to their maximum opening, and all second flow regulators 802 are opened to their maximum opening until the average temperature is less than the second temperature.

[0054] In this embodiment, the phase change temperature of the composite phase change material 3 is set as a first temperature of 37°C. The first temperature is set to be lower than a second temperature of 45°C. Generally, when the maximum temperature difference in each region is not greater than the temperature difference threshold, the temperature difference threshold can be set to 5°C. This allows for uniform adjustment of all flow regulators to ensure consistent opening, reducing the system's operational burden and improving its reliability and response speed.

[0055] When the average temperature is less than or equal to the first temperature, all first flow rate regulators are opened at a fixed degree, and water circuit 6 flows water at the first water flow rate to avoid excessive cooling and energy waste. The first water flow rate can be set to 60%.

[0056] When the average temperature is greater than the first temperature and less than or equal to the second temperature, the opening of all first flow rate regulating components is dynamically adjusted according to the set water flow rate regulation rules. This dynamic adjustment of the water flow rate ensures a balance between cooling effect and energy consumption. The water flow rate regulation rules are expressed by the following formula:

[0057]

[0058] Where, N i For different average temperatures T i The opening degree of all first flow regulators, Q i For different average temperatures T i The corresponding adjusted water flow rate, Q max The maximum water flow rate is T, Q1 is the first water flow rate, and T is the maximum water flow rate. i To obtain different average temperatures in real time, T1 <T i << T2; T1 is the first temperature, and T2 is the second temperature.

[0059] If the average temperature is higher than the second temperature, all first flow regulators 801 are adjusted to their maximum opening, and all second flow regulators 802 are opened to their maximum opening, until the average temperature is lower than the second temperature. The second temperature is a warning temperature. When the average temperature is higher than the second temperature, the temperature of battery 4 is rapidly reduced by controlling all first flow regulators 801 and second flow regulators 802 to be opened to their maximum opening.

[0060] The present invention also includes an alarm module that is connected in communication with the controller and is located outside the heat-conducting housing 1, which provides an early warning when the average temperature is greater than the second temperature.

[0061] Furthermore, during the battery thermal management process, if the average temperature is greater than a first temperature and less than a second temperature, and the maximum temperature difference between any two regions exceeds a temperature difference threshold, then based on the water flow rate adjusted according to different average temperatures, the maximum temperature difference, and the set flow rate adjustment amount, the flow rate of the region with the highest temperature is adjusted using the first zone flow rate, while other regions are adjusted according to the water flow rate adjustment rules. The formula for the first zone flow rate adjustment is as follows:

[0062]

[0063] Among them, Q u For the first partition traffic, when Q is calculated... u When it is greater than 100%, take Q. u 100%; Q i The water flow rate is adjusted for different average temperatures, where ΔT is the maximum temperature difference. th q represents the temperature difference threshold, and q represents the flow rate adjustment.

[0064] During the battery thermal management process, if the average temperature is less than or equal to the first temperature, and the maximum temperature difference between any two regions exceeds the temperature difference threshold, then based on the first water flow rate, the maximum temperature difference, and the set flow rate adjustment, the region with the highest temperature is regulated with the second zone flow rate, while other regions are regulated with the first water flow rate. The formula for the second zone flow rate adjustment is as follows:

[0065]

[0066] Among them, Q v The second partition's traffic is calculated to obtain Q. v When it is greater than 100%, take Q. v It is 100%; Q1 is the first water flow rate, ΔT is the maximum temperature difference, ΔT th q represents the temperature difference threshold, and q represents the flow rate adjustment.

[0067] By adjusting the cooling intensity in different zones, the problem of uneven heat distribution in the battery can be precisely controlled, ensuring uniform temperature distribution in all areas of the battery pack, thereby improving battery performance, extending battery life, and enhancing safety.

Claims

1. A battery thermal management system combining liquid cooling and phase change immersion cooling, characterized in that, include: A top-opening heat-conducting housing, a heat-conducting top cover on top of the heat-conducting housing, and a composite phase change material filling the gaps in the battery. The composite phase change material is divided into several regions of equal area. A temperature measuring device is installed in the composite phase change material in each region. The temperature measuring device is communicatively connected to a controller located outside the heat-conducting shell. A refrigeration device is installed on the bottom and outer sides of the heat-conducting shell. The refrigeration device includes two sets of independent and spaced serpentine refrigeration pipes. One set is a water circuit and the other is a refrigerant circuit. Each set of serpentine refrigeration pipes includes several parallel refrigeration circuits, and each refrigeration circuit corresponds to a region. A first flow regulator is installed at the water inlet of each refrigeration circuit in the water circuit, and a second flow regulator is installed at the refrigerant inlet of each refrigeration circuit in the refrigerant circuit. Both the first and second flow regulators are communicatively connected to the controller. Control module: Used to regulate battery thermal management during battery discharge operation based on real-time temperature data of different areas obtained by the temperature measuring device. The regulation process is as follows: The average temperature is obtained by taking the average value of the temperature in each area. If the average temperature is less than or equal to the first temperature, all first flow regulating components are controlled to open at a fixed opening degree, and the water circuit flows water at the first water flow rate. If the average temperature is greater than the first temperature and less than or equal to the second temperature, the opening degree of all first flow regulating components will be dynamically adjusted according to the set water flow regulation rules. If the average temperature is greater than the second temperature, then control all first flow regulators to adjust to the maximum opening, and at the same time control all second flow regulators to open to the maximum opening, until the average temperature is less than the second temperature. The water flow regulation rule when the average temperature is greater than the first temperature and less than or equal to the second temperature is expressed by the following formula: ， , in, For different average temperatures The opening degree of all first flow regulators at that time, For different average temperatures The corresponding water flow rate is adjusted. For maximum water flow, The first water flow rate, To obtain different average temperatures in real time, ; The first temperature, The second temperature; During the battery thermal management process, if the average temperature is less than or equal to the first temperature, and the maximum temperature difference between any two regions exceeds the temperature difference threshold, then based on the first water flow rate, the maximum temperature difference, and the set flow rate adjustment, the region with the highest temperature is regulated with the second zone flow rate, while other regions are regulated with the first water flow rate. The formula for the second zone flow rate adjustment is as follows: ， in, The traffic for the second partition was calculated. When it is greater than 100%, take 100%; The first water flow rate, For the maximum temperature difference, Temperature difference threshold For flow regulation.

2. The battery thermal management system combining liquid cooling and phase change immersion cooling according to claim 1, characterized in that, The first flow regulating component is an electric flow regulating valve, and the second flow regulating component is a solenoid valve.

3. The battery thermal management system combining liquid cooling and phase change immersion cooling according to claim 1, characterized in that, A thermally conductive sealant is provided between the composite phase change material and the thermally conductive top cover inside the thermally conductive housing.

4. The battery thermal management system combining liquid cooling and phase change immersion cooling according to claim 1, characterized in that, The temperature measuring device is a thermocouple.

5. The battery thermal management system combining liquid cooling and phase change immersion cooling according to claim 1, characterized in that, It also includes an alarm module that communicates with the controller, which is located outside the heat-conducting housing and provides an early warning when the average temperature exceeds the second temperature.

6. The battery thermal management system combining liquid cooling and phase change immersion cooling according to claim 1, characterized in that, The phase transition temperature of the composite phase change material is 37°C.

7. The battery thermal management system combining liquid cooling and phase change immersion cooling according to claim 1, characterized in that, The first temperature is lower than the second temperature.

Images