Seawater energy storage liquid cooling system

Abstract

The invention provides a seawater energy storage liquid cooling system, which belongs to the technical field of energy storage and comprises a seawater cooling unit, an energy storage liquid supply unit and a heat exchange assembly. The seawater cooling unit comprises a first circulating pipeline for conveying seawater, and a first circulating pump is arranged on the first circulating pipeline; the energy storage and liquid supply unit comprises a second circulating pipeline and a third circulating pipeline, the second circulating pipeline is sequentially provided with a heating module, a seawater battery and a second circulating pump in the flowing direction of a circulating medium, and the third circulating pipeline is sequentially provided with an energy storage converter and a third circulating pump in the flowing direction of the circulating medium; the heat exchange assembly comprises a first plate heat exchanger and a second plate heat exchanger, the first plate heat exchanger is provided with a first heat exchange channel and a second heat exchange channel, and the second plate heat exchanger is provided with a third heat exchange channel and a fourth heat exchange channel. According to the seawater energy storage liquid cooling system provided by the invention, a low-energy-consumption liquid cooling system which is adaptive to a seabed environment and takes PACK and PCS individual requirements into consideration is formed.

Description

Technical Field

[0001] This invention belongs to the field of energy storage technology, and more specifically, relates to a seawater energy storage liquid cooling system. Background Technology

[0002] With the rapid development of the global new energy industry, the scale of development and utilization of marine renewable energy sources such as offshore wind power and ocean energy continues to expand. Subsea energy storage systems, which effectively address energy output volatility and improve power supply stability, have become a key component of the marine energy industry chain. Subsea energy storage systems typically operate in complex environments at depths of 50 meters and above. Their core equipment (such as seawater battery packs and power storage converters, PCS) continuously generates heat during charging and discharging. If this heat cannot be dissipated in time, the internal temperature of the equipment will rise, leading to battery capacity degradation, shortened lifespan of PCS power devices, and even safety risks such as thermal runaway. Therefore, an efficient and stable thermal management system is the core guarantee for the reliable operation of subsea energy storage systems.

[0003] Currently, thermal management solutions for subsea energy storage systems are mainly divided into two categories: air cooling and liquid cooling. Among them, air cooling systems are widely used in some low-power-density terrestrial energy storage scenarios due to their simple structure and low cost. However, they have significant limitations in the subsea environment: Firstly, the seawater environment has extremely high humidity and strong corrosiveness. Air cooling systems need to interact with the external environment through ventilation structures, which can easily lead to water vapor intrusion into the equipment, causing short circuits in electrical components. At the same time, the salt in the sea breeze (or seawater evaporation gases) can also accelerate equipment corrosion. Secondly, air cooling has low heat exchange efficiency, which is difficult to meet the heat dissipation requirements of PACK and PCS in high-power-density subsea energy storage systems. Especially under extreme conditions of high seawater temperature, air cooling systems cannot control the equipment temperature within a safe range, which may lead to derating or shutdown of the system.

[0004] Liquid cooling systems are gradually becoming the mainstream technology for thermal management of subsea energy storage due to their high heat exchange efficiency and strong environmental adaptability. Existing subsea energy storage liquid cooling solutions mostly adopt a "single-cycle liquid cooling + single heat exchanger" structure, meaning that a single circulating pipeline transports the cooling medium while simultaneously dissipating heat from both the PACK and PCS. While this approach can solve the heat exchange efficiency problem of air-cooled systems, it still has several drawbacks in practical applications: First, the heat dissipation requirements of the PACK (seawater battery) and PCS (energy storage converter) differ significantly, and a single-cycle system cannot simultaneously meet the individualized heat exchange needs of both types of equipment, easily leading to overcooling or undercooling. Second, the seawater cooling units in existing liquid cooling systems mostly use a single-stage filtration and single-circulation pump design. Sediment, microorganisms, and other impurities in seawater can easily clog the heat exchanger channels, leading to a decrease in heat exchange efficiency. Furthermore, a failure of the single-circulation pump will directly paralyze the entire cooling system, making it impossible to guarantee the continuous operation of the subsea energy storage system. Summary of the Invention

[0005] The purpose of this invention is to provide a seawater energy storage liquid cooling system that can meet the personalized needs of PACK and PCS, adapt to the complex seabed environment, and has low energy consumption characteristics.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a seawater energy storage liquid cooling system, comprising: The seawater cooling unit includes a first circulation pipeline for transmitting seawater, and a first circulation pump is installed on the first circulation pipeline; The energy storage liquid supply unit includes a second circulation pipeline and a third circulation pipeline. The second circulation pipeline is provided with a heating module, a seawater battery and a second circulation pump in sequence along the flow direction of the circulation medium. The third circulation pipeline is provided with an energy storage converter and a third circulation pump in sequence along the flow direction of the circulation medium. The heat exchange assembly includes a first plate heat exchanger and a second plate heat exchanger. The first plate heat exchanger has a first heat exchange passage and a second heat exchange passage, and the second plate heat exchanger has a third heat exchange passage and a fourth heat exchange passage. The first heat exchange passage and the third heat exchange passage are sequentially connected to the first circulation pipeline along the flow direction of the circulating medium and are located downstream of the first circulation pump; The second heat exchange passage is connected to the second circulation loop and is located between the heating module and the second circulation pump; The fourth heat exchange path is connected to the third circulation loop and is located between the energy storage converter and the third circulation pump.

[0007] In one possible implementation, the seawater cooling unit further includes a first filter, which is arranged in the direction of the seawater flow on the first circulation pipeline and is located upstream of the first circulation pump. The filtration accuracy of the first filter is 100μm, and it is used to filter out impurities in the seawater. The energy storage and liquid supply unit further includes a second filter and a third filter. The second filter is disposed on the second circulation pipeline and located upstream of the second circulation pump. The third filter is disposed on the third circulation pipeline and located upstream of the third circulation pump. The filtration accuracy of the second filter and the third filter is 100μm, and they are used to filter impurities in the circulating medium in the second circulation pipeline and the third circulation pipeline, respectively.

[0008] In one possible implementation, the seawater energy storage liquid cooling system further includes an electrical control unit, which includes an electrical control box and multiple sensors, including a temperature sensor, a pressure sensor, and a flow sensor. The temperature sensors are respectively installed on the first circulation pipeline, the second circulation pipeline and the third circulation pipeline, and are used to monitor the temperature of the medium in each pipeline in real time; The pressure sensors are respectively installed on the first circulation pipeline, the second circulation pipeline and the third circulation pipeline, and are used to monitor the pressure of the medium in each pipeline in real time; The flow sensors are respectively installed on the second circulation pipeline and the third circulation pipeline to monitor the flow rate of the circulating medium in the second circulation pipeline and the third circulation pipeline in real time. The electrical control box is electrically connected to the first circulating pump, the second circulating pump, the third circulating pump, the heating module, and multiple sensors, respectively, and is used to receive monitoring data from the sensors and control the operating status of each circulating pump and the heating module according to the monitoring data.

[0009] In one possible implementation, ball valves are provided on the first circulation pipeline, the second circulation pipeline, and the third circulation pipeline, and the ball valves are used to control the opening and closing of each pipeline; The seawater battery consists of multiple modules. At a charge / discharge rate of 0.5C, the heat generation power of a single module is 698.88W, the total heat loss power of multiple modules is ≥3.49kW, and the cooling capacity of the first heat exchanger is ≥1.87kW, which is used to meet the heat dissipation requirements of the seawater battery.

[0010] In one possible implementation, the circulating medium in both the second and third circulation pipelines is a 50% ethylene glycol solution; The heating module is an electric heating module with a heating power of ≥2kW. When the seawater temperature is ≤15℃, the electric heating module is activated to raise the temperature of the circulating medium in the second circulation pipeline.

[0011] In one possible implementation, the flow rate of the circulating medium in the second circulation pipeline is ≥30L / min, and the supply pressure is ≥0.1MPa; When the heating module is not activated, the supply temperature of the circulating medium in the second circulation pipeline is ≤T. 海水 +3℃ is used to meet the heat exchange requirements of seawater batteries.

[0012] In one possible implementation, the flow rate of the circulating medium in the third circulation pipeline is ≥23L / min, and the supply pressure is ≥0.1MPa; When the heating module is not activated, the supply temperature of the circulating medium in the third circulation pipeline is ≤T. 海水 +6℃, and the liquid supply temperature ≤45℃, to meet the heat dissipation requirements of the energy storage converter.

[0013] In one possible implementation, the seawater energy storage liquid cooling system is applied to an environment at a depth of 50m underwater. The temperature range of the seawater in the first circulation pipeline is 10℃~36℃, the temperature of the circulating medium in the second circulation pipeline is controlled at 23±2℃, and the temperature of the individual cell of the seawater battery is controlled at 20~40℃. The temperature difference between all cells in the seawater battery is ≤3℃, and the temperature difference between the inlet and outlet media of the second and third circulation pipelines is ≤2℃.

[0014] In one possible implementation, the sum of the heat exchange of the first plate heat exchanger Q1 and the heat exchange of the second plate heat exchanger Q2 is the total heat exchange of the system Qtotal, the total heat exchange of the system Qtotal = Q1 + Q2, the heat exchange of the first plate heat exchanger is ≥3kW, and the heat exchange of the second plate heat exchanger is ≥3kW. Both the first and second plate heat exchangers use the logarithmic mean temperature difference method to calculate the heat exchange. The logarithmic mean temperature difference of the first plate heat exchanger is Δtm1 = (Δtmax1 - Δtmin1) / ln(Δtmax1 / Δtmin1), where Δtmax1 is the difference between the inlet temperature of the hot medium and the outlet temperature of the cold medium in the first plate heat exchanger, and Δtmin1 is the difference between the outlet temperature of the hot medium and the inlet temperature of the cold medium in the first plate heat exchanger. The logarithmic mean temperature difference Δtm2 of the second plate heat exchanger is calculated as follows: Δtmax2 - Δtmin2 / ln(Δtmax2 / Δtmin2), where Δtmax2 is the difference between the inlet temperature of the hot medium and the outlet temperature of the cold medium in the second plate heat exchanger, and Δtmin2 is the difference between the outlet temperature of the hot medium and the inlet temperature of the cold medium in the second plate heat exchanger.

[0015] In one possible implementation, when calculating the heat exchange between the first and second plate heat exchangers and determining the system operating parameters, a system of equations is established for the calculation of the logarithmic mean temperature difference of the first and second plate heat exchangers, and the five variables involved in the relationship between the first and second plate heat exchangers. First, key, secondary, and unnecessary values ​​are set according to the boundary conditions given by the system, and the temperature T and pressure drop range are preliminarily determined with reference to empirical values. The energy conservation equation, pressure drop equation, and physical property parameter equation are solved simultaneously. At the same time, an iterative algorithm is used to adjust the intermediate temperature or flow rate so that the solution of each unit model is consistent with the system constraints. Finally, a calculation program written in Python software is used to solve the final low-energy-consumption and high-efficiency numerical results to match the system heat exchange requirements.

[0016] The beneficial effects of the seawater energy storage liquid cooling system provided by this invention are as follows: Compared with the prior art, the second and third circulation pipelines are adapted to the personalized heat dissipation requirements of the seawater battery (PACK) and energy storage converter (PCS), respectively. The second circulation pipeline, targeting the temperature characteristics of the medium regulated by the heating module during PACK operation, efficiently exchanges heat with the first plate heat exchanger through a second heat exchange path. The third circulation pipeline, matching the working heat flow characteristics of the PCS, precisely controls the temperature with the second plate heat exchanger through a fourth heat exchange path. This ensures that both types of core components receive a suitable heat dissipation solution, balancing personalized needs while guaranteeing operational stability. For the complex seabed environment, the system uses seawater as the cooling source, constructing a reliable seawater transmission channel through the first circulation pipeline and the first circulation pump. The independent heat exchange path design of the plate heat exchanger components avoids direct contact between seawater and the energy storage medium, effectively mitigating the risk of seawater corrosion. In addition, the system relies on the natural low temperature advantage of seawater to replace traditional active cooling equipment. Furthermore, through the coordinated layout of circulating pumps and plate heat exchangers, the heat exchange process is carried out in a highly efficient sequential manner along the direction of medium flow, reducing energy loss. At the same time, the targeted matching design of pipelines and heat exchange components avoids redundant heat exchange links, further reducing the overall energy consumption of the system. Ultimately, a low-energy liquid cooling system is formed that is adapted to the seabed environment and takes into account the personalized needs of PACK and PCS. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the seawater energy storage liquid cooling system provided by the present invention; Figure 2 This is a module structure diagram of a seawater battery (PACK) provided in an embodiment of the present invention; Figure 3 A surface temperature distribution diagram of a cold plate provided in an embodiment of the present invention; Figure 4 Temperature distribution diagram of the battery cell provided in an embodiment of the present invention; Figure 5 Temperature distribution diagram of the module provided in the embodiment of the present invention.

[0019] In the diagram: 1. First circulation pipeline; 2. First circulation pump; 3. Second circulation pipeline; 4. Heating module; 5. Seawater battery; 6. Second circulation pump; 7. Third circulation pipeline; 8. Energy storage converter; 9. Third circulation pump; 10. First heat exchanger; 11. Second heat exchanger. Detailed Implementation

[0020] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0021] Unless otherwise explicitly specified, the use of terms such as "first," "second," or "third" is intended to distinguish different objects, not to describe a specific order.

[0022] Unless otherwise expressly defined, the use of directional terms such as “center,” “lateral,” “longitudinal,” “horizontal,” “vertical,” “top,” “bottom,” “inner,” “outer,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “clockwise,” “counterclockwise,” “high,” and “low” to indicate orientation or positional relationships is based on the orientation and positional relationships shown in the accompanying drawings and is only for the convenience of describing the invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the specific scope of protection of the invention.

[0023] Please see Figure 1 The seawater energy storage liquid cooling system provided by this invention will now be described. The seawater energy storage liquid cooling system includes a seawater cooling unit, an energy storage liquid supply unit, and a heat exchange component.

[0024] The seawater cooling unit includes a first circulation pipeline 1 for transmitting seawater, and a first circulation pump 2 is installed on the first circulation pipeline 1; the energy storage and liquid supply unit includes a second circulation pipeline 3 and a third circulation pipeline 7, the second circulation pipeline 3 is sequentially provided with a heating module 4, a seawater battery 5 and a second circulation pump 6 along the flow direction of the circulation medium, and the third circulation pipeline 7 is sequentially provided with an energy storage converter 8 and a third circulation pump 9 along the flow direction of the circulation medium; the heat exchange assembly includes a first plate heat exchanger 10 and a second plate heat exchanger 11, the first plate heat exchanger 10 has a first heat exchange passage and a second heat exchange passage, and the second plate heat exchanger 11 has a third heat exchange passage and a fourth heat exchange passage; The first heat exchange passage and the third heat exchange passage are connected sequentially to the first circulation pipeline 1 along the flow direction of the circulating medium and are located downstream of the first circulation pump 2; the second heat exchange passage is connected to the second circulation loop and is located between the heating module 4 and the second circulation pump 6; the fourth heat exchange passage is connected to the third circulation loop and is located between the energy storage converter 8 and the third circulation pump 9.

[0025] The seawater energy storage liquid cooling system provided by this invention, compared with the prior art, employs a second circulation pipeline 3 and a third circulation pipeline 7 to adapt to the personalized heat dissipation requirements of the seawater battery 5 (PACK) and the energy storage converter 8 (PCS), respectively. The second circulation pipeline 3, targeting the temperature characteristics of the medium regulated by the heating module 4 during PACK operation, efficiently exchanges heat with the first plate heat exchanger 10 through a second heat exchange path. The third circulation pipeline 7, matching the working heat flow characteristics of the PCS, precisely controls the temperature through a fourth heat exchange path and the second plate heat exchanger 11. This provides both types of core components with adaptable heat dissipation solutions, balancing personalized needs while ensuring operational stability. For the complex seabed environment, the system uses seawater as a cooling source, constructing a reliable seawater transmission channel through the first circulation pipeline 1 and the first circulation pump 2. The independent heat exchange path design of the plate heat exchanger components avoids direct contact between seawater and the energy storage medium, effectively mitigating the risk of seawater corrosion. In addition, the system relies on the natural low temperature advantage of seawater to replace traditional active cooling equipment. Furthermore, through the coordinated layout of circulating pumps and plate heat exchangers, the heat exchange process is carried out in a highly efficient sequential manner along the direction of medium flow, reducing energy loss. At the same time, the targeted matching design of pipelines and heat exchange components avoids redundant heat exchange links, further reducing the overall energy consumption of the system. Ultimately, a low-energy liquid cooling system is formed that is adapted to the seabed environment and takes into account the personalized needs of PACK and PCS.

[0026] Preferably, the seawater cooling unit further includes a first filter. The first filter is located on the first circulation pipeline 1 along the direction of seawater flow and is located upstream of the first circulation pump 2. The filtration accuracy of the first filter is 100μm. It is used to filter out impurities in the seawater, which not only prevents impurities from entering the heat exchange passages of the first plate heat exchanger 10 and the second plate heat exchanger 11 and causing flow channel blockage or surface scaling, thus ensuring stable heat exchange efficiency on the seawater side, but also prevents downstream components such as the impeller of the first circulation pump 2 from being worn by impurities. At the same time, it reduces the indirect corrosion of the plate heat exchangers by impurities and extends the service life of the heat exchange components to adapt to the high-salt and high-impurity seawater environment on the seabed.

[0027] The energy storage liquid supply unit also includes a second filter and a third filter. The second filter is located on the second circulation pipeline 3 and upstream of the second circulation pump 6; the third filter is located on the third circulation pipeline 7 and upstream of the third circulation pump 9. Both the second and third filters have a filtration accuracy of 100μm and are used to filter impurities in the circulating medium within the second and third circulation pipelines 3 and 7, respectively. This effectively prevents impurities from entering the internal flow channels of the seawater battery 5 (PACK) and the energy storage converter 8 (PCS), preventing blockage of core components or contamination of critical parts, ensuring the stability of the PACK's electrochemical performance and the PCS's power conversion efficiency, and accommodating the individual heat dissipation requirements of both types of components. Simultaneously, the placement of each filter significantly reduces damage to the pump body, heat exchanger, battery, and converter caused by impurities, reducing equipment failures and maintenance frequency, and lowering maintenance costs.

[0028] Preferably, the seawater energy storage liquid cooling system also includes an electrical control unit, which includes an electrical control box and multiple sensors, including a temperature sensor, a pressure sensor and a flow sensor.

[0029] Temperature sensors are installed on the first circulation pipe 1, the second circulation pipe 3, and the third circulation pipe 7 respectively, which can accurately capture the temperature changes of the seawater cooling medium, the PACK circulation medium, and the PCS circulation medium, providing data support for matching the heat dissipation requirements of different core components.

[0030] Pressure sensors are installed on the first circulation pipeline 1, the second circulation pipeline 3, and the third circulation pipeline 7 respectively, to monitor the pressure of the medium in each pipeline in real time. They can provide real-time warnings of pressure anomalies caused by impurities blocking the pipeline or the high-pressure environment at the seabed, thus avoiding risks such as pipeline rupture or pump overload.

[0031] Flow sensors are installed on the second circulation pipe 3 and the third circulation pipe 7 respectively to monitor the flow rate of the circulating medium in the second circulation pipe 3 and the third circulation pipe 7 in real time, directly feedback the supply efficiency of the heat dissipation medium of PACK and PCS, and provide a basis for flow regulation.

[0032] The electrical control box is electrically connected to the first circulating pump 2, the second circulating pump 6, the third circulating pump 9, the heating module 4, and multiple sensors. It is used to receive the monitoring data from the sensors and control the operating status of each circulating pump and the heating module 4 according to the monitoring data. This targeted control mode enables the personalized heat dissipation needs of the PACK and PCS to be met more accurately, breaking through the limitations of traditional fixed parameter heat dissipation.

[0033] The electrical control unit constructs a multi-level safety assurance system. Pressure sensors monitor the seawater pressure in the first circulation pipeline 1 and the pressure in each energy storage circulation pipeline in real time, enabling timely detection of the impact of seabed pressure fluctuations on the pipeline system. The control box triggers circulation pump speed adjustment or emergency shutdown commands through preset thresholds to prevent system damage caused by high pressure. Temperature sensors monitor seawater temperature in real time, helping to determine the impact of seawater temperature changes at different depths on heat exchange efficiency. Based on this, the control box adjusts the speed of the first circulation pump 2 to optimize seawater supply, ensuring that the heat exchange components always maintain a high-efficiency heat exchange state, adapting to the complex operating conditions of unstable seabed water temperature. Simultaneously, the sealed design and anti-interference layout of each sensor and the control box can withstand the corrosive environment of high humidity and high salt spray on the seabed, ensuring the stability of monitoring and control.

[0034] Based on the联动 analysis of the data from various sensors, the electrical control box can achieve the on-demand operation of each circulation pump and the heating module 4. When the medium temperature and flow rate of each pipeline are monitored to be within the optimal range, the circulation pump is regulated to operate at a low speed; when the temperature is below the threshold, the heating module 4 is accurately controlled to start with a low power to avoid ineffective energy consumption; when the seawater temperature is low and efficient heat exchange conditions are available, the rotation speed of the first circulation pump 2 is optimized to reduce the energy consumption of seawater transportation. This dynamically adaptable regulation mode completely avoids the energy waste of the traditional system running at full load, maximizing the low-energy consumption characteristics of the system relying on natural seawater cooling.

[0035] Preferably, ball valves are provided on the first circulation pipeline 1, the second circulation pipeline 3 and the third circulation pipeline 7. The ball valves are used to control the on and off of each pipeline, constructing an independent and controllable on and off mechanism for each loop. At the start-up stage of the system, each pipeline can be opened step by step through the ball valves to realize the sequential commissioning of the seawater cooling unit, the PACK liquid supply unit and the PCS liquid supply unit, avoiding the pressure shock caused by the simultaneous start-up of multiple loops. During maintenance and repair, the single-loop isolation can be achieved by closing the corresponding pipeline ball valve, and the pump body, filter or plate heat exchanger and other components can be repaired without shutting down the whole system, greatly improving the maintenance feasibility and system operation continuity in the complex seabed environment and reducing the shutdown loss.

[0036] The seawater battery 5 consists of multiple modules. At a charge-discharge rate of 0.5C, the heat generation power of a single module is 698.88W, the total heat loss power of multiple modules ≥ 3.49kW, and the refrigerating capacity of the first plate heat exchanger 10 ≥ 1.87kW, which is used to meet the heat dissipation requirements of the seawater battery 5. With the intelligent regulation of the electrical control unit, when the temperature sensor monitors that the medium temperature of the second circulation pipeline 3 rises due to battery heating, the electrical control box can regulate the rotation speed of the second circulation pump 6 to increase the flow rate, and at the same time the ball valve remains fully open to ensure the medium circulation efficiency, giving full play to the refrigerating capacity of the first plate heat exchanger 10. If it is necessary to adjust the heat dissipation intensity or perform local maintenance, the on and off degree of the pipeline can be finely adjusted through the ball valve to assist the flow control, achieving an accurate balance between the heat dissipation effect and energy consumption. This combined mode solves the heat dissipation problem of large and fluctuating heat generation of PACK, ensuring the stable electrochemical performance of the battery in the seabed environment.

[0037] Specifically, the circulating medium in both the second circulation line 3 and the third circulation line 7 is a 50% ethylene glycol solution. This concentration of solution possesses excellent low-temperature antifreeze properties, allowing it to withstand the low-temperature environment of the deep seabed and preventing the circulation lines from cracking due to ice formation. Its good thermal stability and conductivity not only efficiently transfer the heat generated by the PACK and PCS but also maintain stable performance during long-term circulation, reducing the decrease in heat exchange efficiency caused by medium deterioration. Furthermore, the corrosion-resistant properties of the ethylene glycol solution are highly compatible with the materials of various pipelines, filters, and plate heat exchanger components, allowing for further reduction of pipeline corrosion risks and extending the system's service life in the high-salt environment of the seabed.

[0038] Heating module 4 is an electric heating module with a heating power ≥2kW. When the seawater temperature is ≤15℃, the electric heating module 4 is activated to raise the temperature of the circulating medium in the second circulation pipe 3. The electrochemical activity of the seawater battery 5 is prone to decrease in low-temperature environments, and the seabed temperature is often below 15℃ due to depth variations. At this time, the electric heating module 4 with a heating power ≥2kW can quickly start to heat the 50% ethylene glycol solution in the second circulation pipe 3. Combined with real-time monitoring data from the temperature sensor, the control box can precisely adjust the heating power and heating time to ensure that the temperature of the medium entering the seawater battery 5 is maintained within a suitable range. Combined with the cooling capacity of the first plate heat exchanger 10 ≥1.87kW, the system achieves bidirectional temperature control capability. When the seawater temperature is low, the electric heating module 4 and the second circulation pump 6 work together to raise the medium temperature; when the total heat loss power of the battery at a 0.5C charge / discharge rate is ≥3.49kW, the first plate heat exchanger 10 efficiently dissipates heat, keeping the PACK always within its optimal operating temperature range, overcoming the limitation of traditional liquid cooling systems that can only dissipate heat in one direction.

[0039] Specifically, the liquid supply flow rate of the circulating medium in the second circulation pipeline 3 is ≥30L / min, and the liquid supply pressure is ≥0.1MPa. The liquid supply flow rate of ≥30L / min is designed to match the heating characteristics of the seawater battery 5, which has a total heat loss power of ≥3.49kW at a 0.5C charge / discharge rate. When the 50% ethylene glycol solution circulates at this flow rate, it ensures that the heat removed per unit time is sufficient to cover the battery's heating requirements. Combined with the cooling capacity of the first plate heat exchanger 10 (≥1.87kW), this forms a dual heat exchange guarantee. The requirement of a liquid supply pressure of ≥0.1MPa ensures that the circulating medium can flow smoothly in the second circulation pipeline 3 and the multi-module flow channels of the seawater battery 5, avoiding flow attenuation caused by the high-pressure environment of the seabed or pipeline resistance. Especially in scenarios with a large number of battery modules and complex flow channels, stable pressure can ensure the heat exchange uniformity of each module and prevent local overheating.

[0040] When the heating module 4 is not activated, the supply temperature of the circulating medium in the second circulation pipeline 3 is ≤T_seawater + 3℃, which meets the heat exchange requirements of the seawater battery 5. This utilizes the natural low temperature advantage of seawater to achieve efficient heat exchange, avoiding abnormal temperature fluctuations in the battery caused by excessively low supply temperature, and perfectly adapting to the stringent heat exchange temperature requirements of the seawater battery 5. Combined with real-time monitoring by the temperature sensor and speed control of the second circulation pump 6 by the electrical control box, this temperature range can be dynamically maintained without the need for additional refrigeration equipment, maximizing the low-energy consumption advantage of natural seawater cooling.

[0041] Specifically, the supply flow rate of the circulating medium in the third circulation pipeline 7 is ≥23L / min, and the supply pressure is ≥0.1MPa. This provides quantitative assurance for the heat generation characteristics and flow channel design of the PCS. When the 50% ethylene glycol solution circulates at this flow rate, it can stably handle the heat generated by the operation of the PCS. Combined with the heat exchange between the second plate heat exchanger 11 and the seawater cooling source, it ensures efficient heat removal. The lower pressure limit of 0.1MPa ensures smooth flow of the medium in the complex flow channels of the PCS, avoiding flow rate attenuation caused by pressure fluctuations in the seabed environment or pipeline resistance, and ensuring uniform heat dissipation in all parts.

[0042] When the heating module 4 is not activated, the supply temperature of the circulating medium in the third circulation pipeline 7 is ≤T_seawater + 6℃, and the supply temperature is ≤45℃, to meet the heat dissipation requirements of the energy storage converter 8. In line with the PCS's strong temperature adaptability, the heat exchange energy consumption is reduced by widening the temperature difference with seawater, while a 45℃ upper limit is used to establish a robust over-temperature protection line to avoid heat dissipation failure under extreme conditions. This precision is achieved through the efficient heat exchange of the second heat exchanger 11, combined with real-time monitoring by temperature sensors and control by the electrical control box, dynamically optimizing the speeds of the third circulation pump 9 and the first circulation pump 2. Stable temperature control can be maintained without additional cooling equipment, fully leveraging the low-energy consumption advantage of natural seawater cooling.

[0043] The seawater energy storage liquid cooling system is designed for applications at a depth of 50m. The system uses a seawater temperature range of 10℃ to 36℃ as the cooling basis and relies on the first circulation pipeline 1 and plate heat exchange components to build a heat exchange link. The high pressure resistance and corrosion resistance design of each pipeline, pump body and filter can withstand the pressure environment at a depth of 50m. With the on-off control of ball valves and the intelligent monitoring of electrical control unit, it ensures stable operation under high humidity, high pressure and high salinity conditions at this depth.

[0044] The second circulation pipeline 3 stabilizes the temperature of the 50% ethylene glycol solution at 23±2℃, directly providing a suitable heat exchange medium for the seawater battery 5. Combined with parameters such as a liquid supply flow rate of ≥30L / min and a pressure of ≥0.1MPa, the temperature of the individual cells of the seawater battery 5 is precisely controlled within a safe range of 20~40℃. Furthermore, through uniform flow distribution and efficient heat exchange design, the temperature difference between all cells is ≤3℃, avoiding performance degradation or shortened lifespan caused by excessive local temperature differences. This precision perfectly matches the electrochemical characteristics requirements of the seawater battery 5 at a charge / discharge rate of 0.5C. Meanwhile, the design of the temperature difference between the inlet and outlet media of the second and third circulation pipelines 7 is ≤2℃, which ensures the smooth heat exchange process of the two types of circulation systems and avoids the impact on the plate heat exchanger, battery or energy storage converter 8 (PCS) due to sudden changes in media temperature. For the third circulation pipeline 7, this temperature difference control, together with the requirement that the liquid supply temperature is ≤T seawater +6℃ and ≤45℃, not only meets the heat dissipation requirements of the PCS, but also maintains the overall heat exchange stability of the system, and can achieve a smooth temperature transition without additional energy consumption.

[0045] In summary, the electrical control unit uses temperature sensors to capture real-time temperature data from each pipeline and battery cell, dynamically adjusting the speed of each circulating pump and the operating status of the electric heating module 4. For example, when the seawater temperature is ≤15℃, the heating module 4 is activated to raise the temperature of the medium in the second circulating pipeline 3 to the target range. The high-efficiency heat exchange performance of the plate heat exchanger provides hardware support for temperature difference control, ensuring that the temperature of the circulating medium remains stable within the design range even when the seawater temperature fluctuates (10℃~36℃). Ultimately, based on adaptability to a 50m underwater environment, the system, through multi-dimensional temperature precision control, takes into account the personalized needs of the seawater battery 5 and the PCS. While ensuring the safe operation of core components, it further consolidates the low-energy consumption advantage of relying on natural seawater cooling, forming a liquid cooling solution that is adaptable to the deep-sea environment, provides precise temperature control, and is highly efficient and energy-saving.

[0046] In the specific design, the sum of the heat exchange of the first plate heat exchanger 10, Q1, and the heat exchange of the second plate heat exchanger 11, Q2, is the total heat exchange of the system, Qtotal = Q1 + Q2. The heat exchange of the first plate heat exchanger 10 is ≥3kW, and the heat exchange of the second plate heat exchanger 11 is ≥3kW.

[0047] The design of the first heat exchanger 10 and the second heat exchanger 11 with heat exchange capacity of ≥3kW and total heat exchange capacity of Q_total = Q1 + Q2 ≥6kW not only covers the requirement of total heat loss power of ≥3.49kW for the seawater battery 5 at a charge-discharge rate of 0.5C, but also reserves sufficient redundancy for heat dissipation of the energy storage converter 8 (PCS). Even under full load operation or extreme conditions, the heat exchange capacity of the dual heat exchangers can ensure rapid heat dissipation and avoid performance degradation or failure of core components due to insufficient heat dissipation.

[0048] Both the first plate heat exchanger 10 and the second plate heat exchanger 11 use the logarithmic mean temperature difference method to calculate the heat exchange. The logarithmic mean temperature difference of the first plate heat exchanger 10 is Δtm1 = (Δtmax1 - Δtmin1) / ln(Δtmax1 / Δtmin1), where Δtmax1 is the difference between the inlet temperature of the hot medium and the outlet temperature of the cold medium in the first plate heat exchanger 10, and Δtmin1 is the difference between the outlet temperature of the hot medium and the inlet temperature of the cold medium in the first plate heat exchanger 10. The logarithmic mean temperature difference of the second plate heat exchanger 11 is Δtm2 = (Δtmax2 - Δtmin2) / ln(Δtmax2 / Δtmin2), where Δtmax2 is the difference between the inlet temperature of the hot medium and the outlet temperature of the cold medium in the second plate heat exchanger 11, and Δtmin2 is the difference between the outlet temperature of the hot medium and the inlet temperature of the cold medium in the second plate heat exchanger 11. This method, by taking into account the temperature difference between the inlet and outlet of the heat exchanger's internal heat exchanger and the cold medium, can more accurately reflect the temperature variation along the actual heat exchange process compared to a simple arithmetic mean temperature difference. It is especially suitable for scenarios involving seawater temperature fluctuations (10℃~36℃) and precise control of the circulating medium temperature.

[0049] Taking the first heat exchanger 10 as an example, by calculating the difference Δtmax1 between the inlet temperature of the heat medium (50% ethylene glycol solution in the second circulation pipe 3) and the outlet temperature of the cold medium (seawater), and the difference Δtmin1 between the outlet temperature of the heat medium and the inlet temperature of the cold medium, and substituting these values ​​into the formula Δtm1=(Δtmax1-Δtmin1) / ln(Δtmax1 / Δtmin1), the actual heat exchange temperature difference can be accurately obtained. This provides precise data support for the selection of the heat exchanger area, the design of the flow channel, and the matching of the circulation pump parameters, ensuring that its heat exchange capacity stably reaches the design standard of ≥3kW. Similarly, the second heat exchanger 11 is calculated using the logarithmic average temperature difference method to ensure that its heat exchange capacity is ≥3kW, meeting the heat dissipation requirements of the PCS.

[0050] This technical solution, by constructing a multivariate equation system and combining iterative algorithms with Python programs for solving, provides a precise quantitative analysis method for calculating the heat exchange of plate heat exchangers and determining system operating parameters. This significantly improves the rationality of the liquid cooling system design and enhances its low-energy consumption and high-efficiency characteristics, enabling a more precise adaptation to the personalized heat dissipation requirements of the seawater battery 5 and the PCS in a 50m underwater environment. From the perspective of the systematic and scientific nature of parameter design, constructing an equation system involving the logarithmic mean temperature difference calculation of the first plate heat exchanger 10 and the second plate heat exchanger 11, and the five variables related to their relationship, breaks through the limitations of traditional single-component design. It achieves collaborative analysis of the plate heat exchanger unit and the overall system—by clarifying system boundary conditions, distinguishing key values ​​(such as total heat loss power of the seawater battery 5 ≥ 3.49kW, heat exchange of the plate heat exchanger ≥ 3kW), secondary values ​​(such as the temperature difference between the inlet and outlet of the pipeline ≤ 2℃), and unnecessary values, and combining empirical data such as seawater temperature (10℃~36℃) and the physical properties of the circulating medium, the temperature T and pressure drop range are initially locked, avoiding the blindness and redundancy of parameter design.

[0051] Solving the energy conservation equation, pressure drop equation, and physical property parameter equation simultaneously ensures the comprehensive fit and feasibility of the system parameters.

[0052] The energy conservation equation ensures that the sum of the heat exchange of the first heat exchanger 10 and the second heat exchanger 11 (Qtotal = Q1 + Q2) is balanced with the total heat demand of the seawater battery 5 and PCS, thus avoiding insufficient heat exchange or over-design.

[0053] The pressure drop equation, combined with the requirement of pipeline supply pressure ≥0.1MPa, ensures smooth flow of the circulating medium in each pipeline and plate heat exchanger channel, and matches the power output of the circulating pump.

[0054] The physical property parameter equations take into account the changes in thermal conductivity, viscosity, etc. of 50% ethylene glycol solution at different temperatures, making the calculation results more consistent with actual operating conditions.

[0055] The introduction of iterative algorithms solves the problem that intermediate variables such as temperature and flow rate are difficult to determine at once in the coupled solution of multiple equations. By continuously adjusting intermediate parameters (such as the inlet and outlet temperatures of the medium in the second circulation pipeline 3 and the seawater flow rate of the first circulation pump 2), the calculation results of each unit model gradually approach the system constraints, such as the medium temperature in the second circulation pipeline 3 being 23±2℃ and the cell temperature difference being ≤3℃, ultimately achieving optimal parameter matching.

[0056] The computational program written in Python further enhances the advantages of this method, driving the system towards optimization towards low energy consumption and high efficiency. The program can handle large amounts of data in iterative calculations, quickly converging to obtain numerical results that satisfy all constraints, significantly improving efficiency and accuracy compared to traditional manual calculations. More importantly, the program can compare and analyze the energy consumption and heat transfer efficiency of different parameter combinations (such as circulating pump speed and plate heat exchanger channel structure) during the solution process, automatically selecting the low-energy-consumption solution. For example, by adjusting the speed of the first circulating pump 2 to change the seawater flow rate, the logarithmic mean temperature difference of the plate heat exchanger is maintained within the high-efficiency range, minimizing the power consumption of the circulating pump while meeting the heat transfer requirement of ≥3kW, perfectly aligning with the system's low-energy-consumption design intention of relying on natural seawater cooling.

[0057] Example: Simulation Design and Analysis of Seawater Energy Storage Liquid Cooling System This embodiment takes a 232 kWh subsea energy storage project at a depth of 50 m as the application scenario. It conducts simulation verification on the operation effect of the liquid cooling system under different charge and discharge rates and extreme seawater temperature conditions. Combining the dual circulation pipeline, dual plate heat exchange components and electrical control unit in the patented technical solution, it verifies the system's adaptability to the personalized heat dissipation requirements of the seawater battery 5 (PACK) and the energy storage converter 8 (PCS), as well as its low energy consumption and high stability operation characteristics.

[0058] I. Basic Conditions Application environment parameters: underwater depth of 50m, seawater temperature range of 10℃~36℃, seawater temperature of 27℃ under extreme conditions; total system energy storage capacity of 232kWh, please refer to [link / reference]. Figure 2 The seawater battery 5 (PACK) consists of 5 modules, and the energy storage converter 8 (PCS) is rated to match the system's charging and discharging requirements.

[0059] Core component configuration Seawater cooling unit: The first circulation pipeline 1 is made of high pressure resistant and corrosion resistant material, and is equipped with one first circulation pump 2 (flow rate adjustable) and one 100μm precision first filter; Energy storage liquid supply unit: The second circulation pipeline 3 (adapted to PACK) is equipped with 1 second circulation pump 6, 1 second filter with a precision of 100μm, and 1 electric heating module 4 with a power of ≥2kW; the third circulation pipeline 7 (adapted to PCS) is equipped with 1 third circulation pump 9 and 1 third filter with a precision of 100μm; the circulation medium is 50% ethylene glycol solution. Heat exchange components: First plate 10 (compatible with PACK) heat exchange capacity ≥3kW, second plate 11 (compatible with PCS) heat exchange capacity ≥3kW; Electrical control unit: The electrical control box is equipped with a Python control program, and temperature sensors (accuracy ±0.5℃), pressure sensors (accuracy ±0.01MPa), and flow sensors (accuracy ±0.5L / min) are installed at key nodes of each pipeline.

[0060] II. Simulation Condition 1: System Operation Verification at 0.5C Charge / Discharge Rate (a) Operating Condition Settings The seawater temperature is 20℃ (normal seabed water temperature). The PACK is charged and discharged at a rate of 0.5C (charge and discharge time is 4 hours), and the PCS is operating at full load. According to the patented technical solution, the following conditions must be met: the temperature of the PACK individual cell is 20~40℃, the temperature difference of the cells in the module is ≤3℃, the liquid supply temperature of the PCS is ≤45℃, and the temperature difference between the inlet and outlet of the second / third circulation pipeline 7 is ≤2℃.

[0061] (II) Simulation Process and Control Logic Heat load calculation: According to the "Battery module heat load calculation" method in the patent specification, the heat generation power of a single PACK module at 0.5C rate is 698.88W, and the total heat loss power of 5 modules is 3.49kW; the heat dissipation of PCS is ≥3kW, and the total heat load of the system is ≥6.49kW, which matches the design requirement of total heat exchange of dual-plate heat exchanger (Qtotal = Q1 + Q2 ≥ 6kW).

[0062] System startup and control The electrical control box receives a temperature sensor signal (seawater temperature 20℃), determines that there is no need to start the electric heating module 4, and controls the first circulation pump 2 to start. After the seawater is filtered by a 100μm filter, it enters the first heat exchange passage of the first plate heat exchanger 10 and the third heat exchange passage of the second plate heat exchanger 11 in sequence. The second circulation pump 6 starts, and the 50% ethylene glycol solution, after being filtered by the second filter, enters the PACK to absorb heat (the temperature rises to 25°C), and then flows into the second heat exchange passage of the first plate heat exchanger 10 to exchange heat with seawater. After cooling down to 23°C, it flows back to the PACK, forming a cycle. The speed of the second circulation pump 6 is adjusted by the flow sensor to stabilize the liquid supply flow rate at 30L / min (meeting the minimum flow requirement of the PACK), and the pressure sensor monitors the liquid supply pressure as 0.15MPa (≥0.1MPa). The third circulation pump 9 is started. After the 50% ethylene glycol solution is filtered by the third filter, it enters the PCS to absorb heat (the temperature rises to 43°C), and then flows into the fourth heat exchange passage of the second plate heat exchanger 11 to exchange heat with seawater. After cooling down to 41°C, it flows back to the PCS. The speed of the third circulation pump 9 is adjusted to stabilize the liquid supply flow rate at 23L / min (meeting the minimum flow requirement of the PCS), and the liquid supply pressure is 0.12MPa (≥0.1MPa).

[0063] (III) Simulation Results Temperature control performance: The temperature distribution of individual PACK cells is 36.8℃~39.3℃, and the temperature difference of cells within the module is 2.5℃ (≤3℃); the temperature difference between the inlet and outlet of the second circulation pipeline 3 is 2℃ (≤2℃), and the medium temperature is stable at 23±2℃; the PCS liquid supply temperature is 41℃ (≤45℃), and the temperature difference between the inlet and outlet of the third circulation pipeline 7 is 2℃ (≤2℃), all of which meet the patented design specifications.

[0064] Energy consumption and heat exchange efficiency: The first circulation pump 2 consumes 1.2kW of power, the second / third circulation pump 9 consumes a total of 0.8kW of power, and the total energy consumption of the system is 2.0kW; the first plate heat exchanger 10 has an actual heat exchange of 3.2kW (≥3kW), the second plate heat exchanger 11 has an actual heat exchange of 3.1kW (≥3kW), the heat exchange efficiency reaches 98%, and there is no energy waste.

[0065] III. Simulation Condition 2: Verification of Charge / Discharge Rate at Extreme Seawater Temperature (27℃) +0.25C (a) Operating Condition Settings Seawater temperature 27℃ (extreme high temperature condition at 50m underwater), PACK is charged and discharged at 0.25C rate (reducing the charging and discharging speed to adapt to the high temperature environment), PCS operates at half load; it is required that: PACK single cell temperature ≤ 40℃, and the medium temperature of the second circulation pipeline 3 ≤ T seawater + 3℃ (i.e. ≤ 30℃).

[0066] (II) Simulation Process and Control Logic Parameter adjustment: Based on the seawater temperature sensor signal (27℃), the electrical control box automatically increases the speed of the first circulation pump 2, increases the seawater flow rate (20% higher than normal operating conditions), and enhances the heat exchange capacity of the dual-plate heat exchanger; at the same time, it reduces the PACK charge / discharge rate to 0.25C to reduce the heat generated by the PACK.

[0067] Circulating medium control: The flow rate of the second circulating pump 6 is maintained at 30L / min, and after heat exchange through the first plate heat exchanger 10, the medium temperature is stabilized at 29℃ (≤30℃); the flow rate of the third circulating pump 9 is maintained at 23L / min, and the PCS supply liquid temperature is stabilized at 44℃ (≤45℃).

[0068] (III) Simulation Results Temperature control performance: The maximum temperature of a single PACK cell is 39.75℃ (≤40℃), and the cell temperature difference is 3℃ (≤3℃); the medium temperature of the second circulation pipeline 3 is 29℃ (≤T seawater +3℃), and the medium temperature of the third circulation pipeline 7 is 44℃ (≤45℃). Even under extreme high temperatures, the requirements for safe operation are still met.

[0069] System stability: There were no abnormal pressure fluctuations in any pipeline (seawater pressure in the first circulation pipeline 1 was 0.6 MPa, and the liquid supply pressures in the second and third circulation pipelines 7 were 0.16 MPa and 0.13 MPa, respectively); there was no clogging in the filter, and the temperature distribution in the plate heat exchanger channel was uniform with no risk of local overheating.

[0070] IV. Simulation Condition 3: Low-Temperature Seawater (10℃) + Heating Module 4 Startup Verification (a) Operating Condition Settings With a seawater temperature of 10℃ (underwater low temperature conditions at 50m), the PACK is charged and discharged at a rate of 0.5C, and the PCS is operating at full load. It is necessary to verify the effect of the electric heating module 4 on improving the temperature of the PACK medium to ensure that the temperature of the individual PACK cells is ≥20℃.

[0071] (II) Simulation Process and Control Logic Heating module 4 starts: When the electrical control box detects that the seawater temperature is 10℃ (≤15℃), it automatically starts the electric heating module 4 (power 2kW) to preheat the 50% ethylene glycol solution in the second circulation pipeline 3. After the medium temperature rises to 20℃, the second circulation pump 6 is started.

[0072] Heat exchange coordination control: The first circulation pump 2 maintains the normal flow rate, and the first plate heat exchanger 10 reduces the heat exchange intensity (by adjusting the on / off ratio of the plate heat exchanger channel using the electrical control box) to avoid excessive temperature drop of the medium; the medium in the second circulation pipeline 3 is stabilized at 22℃ after heating and heat exchange; the medium in the third circulation pipeline 7 is stabilized at 38℃ (≤45℃) after heat exchange by the second plate heat exchanger 11.

[0073] (III) Simulation Results Temperature control effect: Please refer to Figures 3 to 5 The temperature distribution of the PACK individual battery cells is between 28℃ and 31℃ (≥20℃), with a temperature difference of 3℃ (≤3℃); the medium temperature of the second circulation pipeline 3 is 22℃ (within the range of 23±2℃), and there is no energy waste after the electric heating module 4 is started; the liquid supply temperature of the PCS is 38℃, which meets the heat dissipation requirements.

[0074] Energy efficiency of heating module 4: After the electric heating module 4 runs for 15 minutes, the medium temperature in the second circulation pipeline 3 rises from 10℃ to 20℃, with an average energy consumption of 1.8kW (lower than the rated power of 2kW), and an energy efficiency of 90%, which meets the low energy consumption design requirements.

[0075] V. Conclusion This embodiment demonstrates through simulation verification under two conventional operating conditions and one extreme operating condition that the seawater energy storage liquid cooling system is fully compatible with the patented technology solution: Dual circulation piping + dual plate heat exchanger assembly can precisely meet the personalized needs of PACK and PCS, and can achieve precise control of temperature, flow and pressure in both normal and extreme conditions. The electrical control unit, combined with Python programs and iterative algorithms, can dynamically adjust the operating parameters of each component to ensure that the system maintains high heat exchange efficiency with low energy consumption, with a total energy consumption of ≤2.0kW; The system exhibits high stability in complex underwater environments up to 50m deep. The synergistic effect of components such as filters, corrosion-resistant pipelines, and heating modules effectively mitigates risks such as seawater corrosion and impurity blockage, fully meeting the operational requirements of the 232kWh subsea energy storage project.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A seawater energy storage liquid cooling system, characterized in that, The application relates to a seawater energy storage liquid cooling system. The seawater cooling unit comprises a first circulating pipeline (1) for conveying seawater, wherein a first circulating pump (2) is arranged on the first circulating pipeline (1). The energy storage liquid supply unit comprises a second circulating pipeline (3) and a third circulating pipeline (7), wherein a heating module (4), a seawater battery (5) and a second circulating pump (6) are sequentially arranged on the second circulating pipeline (3) along the circulating medium flow direction, and an energy storage converter (8) and a third circulating pump (9) are sequentially arranged on the third circulating pipeline (7) along the circulating medium flow direction. The heat exchange assembly comprises a first plate heat exchanger (10) and a second plate heat exchanger (11), wherein the first plate heat exchanger (10) is provided with a first heat exchange channel and a second heat exchange channel, and the second plate heat exchanger (11) is provided with a third heat exchange channel and a fourth heat exchange channel. The first heat exchange channel and the third heat exchange channel are sequentially connected to the first circulating pipeline (1) and located downstream of the first circulating pump (2) along the circulating medium flow direction. The second heat exchange channel is connected to the second circulating pipeline and located between the heating module (4) and the second circulating pump (6). The fourth heat exchange channel is connected to the third circulating pipeline and located between the energy storage converter (8) and the third circulating pump (9).

2. The seawater energy storage liquid cooling system of claim 1, wherein, The seawater cooling unit further comprises first filters, which are arranged on the first circulating pipeline (1) along the seawater flow direction and located upstream of the first circulating pump (2), and the filtering precision of the first filters is 100 microns, so that impurities in seawater are filtered out. The energy storage liquid supply unit further comprises second filters and third filters, the second filters are arranged on the second circulating pipeline (3) and located upstream of the second circulating pump (6), the third filters are arranged on the third circulating pipeline (7) and located upstream of the third circulating pump (9), and the filtering precision of the second filters and the third filters is 100 microns, so that impurities in the circulating medium in the second circulating pipeline (3) and the third circulating pipeline (7) are filtered out.

3. The seawater energy storage liquid cooling system of claim 1, wherein, The seawater energy storage liquid cooling system further comprises an electrical control unit, the electrical control unit comprises an electric control box and a plurality of sensors, and the plurality of sensors comprise temperature sensors, pressure sensors and flow sensors. The temperature sensors are arranged on the first circulating pipeline (1), the second circulating pipeline (3) and the third circulating pipeline (7) respectively, and are used for monitoring the temperature of the medium in each pipeline in real time. The pressure sensors are arranged on the first circulating pipeline (1), the second circulating pipeline (3) and the third circulating pipeline (7) respectively, and are used for monitoring the pressure of the medium in each pipeline in real time. The flow sensors are arranged on the second circulating pipeline (3) and the third circulating pipeline (7) respectively, and are used for monitoring the flow of the circulating medium in the second circulating pipeline (3) and the third circulating pipeline (7) in real time. The electric control box is electrically connected with the first circulating pump (2), the second circulating pump (6), the third circulating pump (9), the heating module (4) and a plurality of sensors respectively, is used for receiving monitoring data of the sensors, and controls operating states of the circulating pumps and the heating module (4) according to the monitoring data.

4. The seawater energy storage liquid cooling system of claim 1, wherein, Ball valves are arranged on the first circulating pipeline (1), the second circulating pipeline (3) and the third circulating pipeline (7), and the ball valves are used for controlling on-off of the pipelines. The seawater battery (5) is composed of a plurality of modules, the heating power of a single module is 698.88W under 0.5C charging and discharging rate, the total heat loss power of the plurality of modules is greater than or equal to 3.49kW, and the refrigerating capacity of the first plate exchanger (10) is greater than or equal to 1.87kW, so as to meet the heat dissipation requirement of the seawater battery (5).

5. The seawater energy storage liquid cooling system of claim 1, wherein, The circulating medium in the second circulating pipeline (3) and the third circulating pipeline (7) is a 50% glycol solution. The heating module (4) is an electric heating module (4), the heating power of the electric heating module (4) is greater than or equal to 2Kw, the electric heating module (4) is started when the seawater temperature is less than or equal to 15℃, and the temperature of the circulating medium in the second circulating pipeline (3) is raised.

6. The seawater energy storage liquid cooling system of claim 5, wherein, The liquid supply flow rate of the circulating medium in the second circulating pipeline (3) is greater than or equal to 30L / min, and the liquid supply pressure is greater than or equal to 0.1MPa. When the heating module (4) is not started, the liquid supply temperature of the circulating medium in the second circulating pipeline (3) is less than or equal to Tseawater+3℃, so as to meet the heat exchange requirement of the seawater battery (5).

7. The seawater energy storage liquid cooling system of claim 5, wherein, The liquid supply flow rate of the circulating medium in the third circulating pipeline (7) is greater than or equal to 23L / min, and the liquid supply pressure is greater than or equal to 0.1MPa. When the heating module (4) is not started, the liquid supply temperature of the circulating medium in the third circulating pipeline (7) is less than or equal to Tseawater+6℃, and the liquid supply temperature is less than or equal to 45℃, so as to meet the heat dissipation requirement of the energy storage converter (8).

8. The seawater energy storage liquid cooling system of claim 1, wherein, The seawater energy storage liquid cooling system is applied to an underwater environment with a depth of 50m, the temperature of seawater in the first circulating pipeline (1) ranges from 10℃ to 36℃, the temperature of the circulating medium in the second circulating pipeline (3) is controlled to be 23±2℃, and the temperature of the single cell of the seawater battery (5) is controlled to be 20-40℃. The temperature difference between all the cells in the seawater battery (5) is less than or equal to 3℃, and the temperature difference between the medium at the inlet and the outlet of the second circulating pipeline (3) and the third circulating pipeline (7) is less than or equal to 2℃.

9. The seawater energy storage liquid cooling system of claim 1, wherein, The sum of the heat exchange amount Q1 of the first plate exchanger (10) and the heat exchange amount Q2 of the second plate exchanger (11) is the total heat exchange amount Qtotal of the system, the total heat exchange amount Qtotal of the system is Q1+Q2, the heat exchange amount of the first plate exchanger (10) is greater than or equal to 3kW, and the heat exchange amount of the second plate exchanger (11) is greater than or equal to 3kW. The first plate heat exchanger (10) and the second plate heat exchanger (11) both use logarithmic mean temperature difference method to calculate heat exchange amount, the logarithmic mean temperature difference Δtm1 of the first plate heat exchanger (10) is (Δtmax1-Δtmin1) / ln(Δtmax1 / Δtmin1), wherein Δtmax1 is the difference between the hot medium inlet temperature and the cold medium outlet temperature in the first plate heat exchanger (10), and Δtmin1 is the difference between the hot medium outlet temperature and the cold medium inlet temperature in the first plate heat exchanger (10); The logarithmic mean temperature difference Δtm2 of the second plate heat exchanger (11) is (Δtmax2-Δtmin2) / ln(Δtmax2 / Δtmin2), wherein Δtmax2 is the difference between the hot medium inlet temperature and the cold medium outlet temperature in the second plate heat exchanger (11), and Δtmin2 is the difference between the hot medium outlet temperature and the cold medium inlet temperature in the second plate heat exchanger (11).

10. The seawater energy storage liquid cooling system of claim 9, wherein, In the calculation of the heat exchange amount of the first plate heat exchanger (10) and the second plate heat exchanger (11) and the determination of the system operating parameters, an equation group is established by the first plate heat exchanger (10) logarithmic mean temperature difference calculation, the second plate heat exchanger (11) logarithmic mean temperature difference calculation and the five variables involved in the correlation between the first plate heat exchanger (10) and the second plate heat exchanger (11), the key value, the secondary value and the unnecessary value are set according to the given boundary conditions of the system, the temperature T and the pressure drop range are preliminarily determined by referring to the experience value; the energy conservation equation, the pressure drop equation and the physical property parameter equation are solved simultaneously, and the iterative algorithm is used to adjust the intermediate temperature or the flow rate, so that the solution of each unit model is consistent with the system constraints, and the final low-energy-consumption high-efficiency numerical result is solved by the calculation program compiled by Python software to match the system heat exchange demand.

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