Pumpless self-circulation loop heat pipe heat dissipation system and method for water-based energy storage battery pack

Abstract

This invention discloses a pump-free self-circulating loop heat pipe cooling system and method for an underwater energy storage battery pack. The system includes an evaporator, a steam pipeline, an underwater condenser, and a liquid pipeline, which are sequentially connected to form a phase change circulation loop and filled with a phase change working fluid. The evaporator is located on the heat exchange surface of the battery pack and has a built-in capillary wick. The steam pipeline extends below the water surface, and the underwater condenser is submerged in the water. The evaporator absorbs heat from the battery pack and, in conjunction with the underwater condenser, achieves long-distance heat transfer. The capillary wick generates capillary force to overcome gravity and drive the liquid working fluid to flow upwards back, adapting to an underwater layout where the heat source is above and the cold source is below. The system requires no fan or liquid cooling unit, has no additional energy consumption or moving parts, has a simple structure, is easy to install, and can fully utilize the natural cold source of water to achieve passive and efficient heat dissipation, improving heat dissipation reliability and scenario adaptability.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal management of electrochemical energy storage systems, and particularly relates to a pump-free self-circulating loop heat pipe cooling system and method for an underwater energy storage battery pack. Background Art

[0002] Energy storage supporting a floating photovoltaic power station is an important technical path to suppress the output fluctuation of the power station and improve the power generation benefit. Restricted by the water area space conditions, decentralized underwater energy storage battery packs have become the mainstream layout mode, but the heat dissipation problem of the battery pack directly restricts the long-term stable operation of the system. At present, lithium iron phosphate energy storage systems mostly adopt air-cooling and liquid-cooling heat dissipation modes. Air-cooling heat dissipation is significantly affected by environmental wind speed and temperature, and heat accumulation is likely to occur under high-temperature and windless conditions. In addition, the fan components have problems such as additional energy consumption and insufficient reliability; liquid-cooling heat dissipation has a higher efficiency, but a liquid-cooling unit and complex pipelines need to be configured, and the overall volume is large, the installation is cumbersome, and the energy consumption is relatively high, which is not suitable for decentralized energy storage scenarios.

[0003] Heat pipes have gradually been applied to the field of battery thermal management due to their efficient passive heat transfer advantages. For example, the annular heat pipe battery module disclosed in patent CN201510266341.8 can only achieve heat distribution among battery monomers and cannot meet the long-distance heat transfer requirements. In the underwater energy storage scenario, the battery pack is arranged above the water surface, and the cold source water body is located below, forming a vertical layout with the heat source above and the cold source below. This layout is contrary to the working principle of conventional thermosyphon heat pipes, and it is difficult for the liquid working medium to overcome gravity and flow upward, resulting in the inability to directly apply traditional heat pipes. Summary of the Invention

[0004] The purpose of the present invention is to provide a pump-free self-circulating loop heat pipe cooling system and method for an underwater energy storage battery pack to solve the technical defects that the existing underwater energy storage battery pack heat dissipation has poor adaptability to air-cooling conditions and energy consumption, the liquid-cooling installation is complex, the existing heat pipes cannot transfer heat over a long distance, and the conventional heat pipes cannot achieve the return of the working medium under the layout with the heat source above and the cold source below.

[0005] To achieve the above purpose, the present invention is implemented by adopting the following technical solutions.

[0006] In the first aspect of the present application, a pump-free self-circulating loop heat pipe cooling system for an underwater energy storage battery pack is provided, including: An evaporator, arranged on the heat exchange surface of the underwater energy storage battery pack, and a wick structure is arranged inside the evaporator; A steam pipeline, one end of which is hermetically connected to the steam outlet of the evaporator, and the other end extends downward below the water surface; An underwater condenser, immersed in the water body, and the steam inlet of the underwater condenser is hermetically connected to the other end of the steam pipeline; A liquid pipeline, one end of which is sealed and connected to the liquid outlet of the underwater condenser, and the other end of which is sealed and connected to the liquid inlet of the evaporator; The evaporator, steam pipeline, underwater condenser and liquid pipeline are sequentially sealed and connected to form a phase change circulation loop, and the phase change circulation loop is filled with a phase change working fluid. The capillary force generated by the capillary wick can overcome gravity and drive the liquid working fluid to flow back from the underwater condenser to the evaporator autonomously, achieving pump-free self-circulating heat dissipation.

[0007] In one optional embodiment, the evaporator is a flat-plate evaporator, and the heat exchange surface of the flat-plate evaporator is attached to the bottom surface of the energy storage battery pack to form a thermal conduction connection. Alternatively, the heat exchange surface of the flat-plate evaporator may be attached to the side of the energy storage battery pack to form a heat conduction connection.

[0008] In one alternative embodiment, the capillary core is a porous structure of sintered metal powder.

[0009] In one alternative embodiment, the underwater condenser is a finned tube heat exchanger structure.

[0010] In one optional embodiment, the steam pipeline and the liquid pipeline are fastened along the outer wall of the water surface photovoltaic support column by pipe clamps, and the length of the steam pipeline and the liquid pipeline is not less than the height of the water surface photovoltaic support column.

[0011] In an optional embodiment, the phase change circulation loop is further provided with a liquid reservoir; The liquid reservoir is sealed and connected to the liquid pipeline; or the liquid reservoir is sealed and connected to the shell of the evaporator.

[0012] In one alternative embodiment, a thermally conductive interface material is filled and bonded between the heat exchange surfaces of the evaporator and the energy storage battery pack to form a low-resistance thermal conductivity connection.

[0013] In one optional embodiment, a phase change material layer is sandwiched between the heat exchange surfaces of the evaporator and the energy storage battery pack, and the phase change material layer forms a thermally conductive connection with the evaporator and the energy storage battery pack respectively.

[0014] In one alternative embodiment, the evaporators are provided in multiple units and arranged in parallel; The steam outlets of each evaporator are all connected to the steam inlet of the underwater condenser via a confluence seal, and the liquid inlets of each evaporator are all connected to the liquid outlet of the underwater condenser via a confluence seal.

[0015] A second aspect of this application provides a pumpless self-circulating loop heat pipe cooling method for a floating energy storage battery pack. The method employs the pumpless self-circulating loop heat pipe cooling system for the floating energy storage battery pack as described above, and includes: The evaporator absorbs the heat generated by the water-based energy storage battery pack, causing the phase change working fluid inside the evaporator to evaporate and form steam. The steam is transported via a steam pipeline to an underwater condenser submerged in water, where it exchanges heat with the water to condense into a liquid phase change working fluid. Under the capillary force generated by the capillary wick inside the evaporator, the capillary force overcomes gravity and drives the liquid phase change working fluid to flow back to the evaporator through the liquid pipeline, forming a continuous pump-free self-circulating phase change heat dissipation, thereby achieving continuous heat dissipation for the water-based energy storage battery pack.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The evaporator is attached to the battery pack to absorb heat, and works with the underwater condenser to achieve long-distance heat transfer, overcoming the problem that existing heat pipes can only heat evenly but cannot transfer heat over long distances; the capillary wick generates capillary force to overcome gravity and drive the liquid working fluid to flow upwards, which is suitable for the water layout with the heat source on top and the cold source below, solving the problem that conventional heat pipes cannot be used. The entire system does not require a fan or liquid cooling unit, has no additional energy consumption or moving parts, is not affected by environmental conditions, has a simple structure, is easy to install, makes full use of the natural cold source of water, achieves passive and efficient heat dissipation, and improves the reliability of heat dissipation and the adaptability of the scenario.

[0017] 2. Flat-plate evaporator, which can be attached to the bottom or side of the energy storage battery pack to form a heat conduction connection, can greatly improve heat collection efficiency and installation adaptability, reduce contact thermal resistance, and ensure that the heat of the battery pack is quickly transferred to the inside of the evaporator. It is suitable for use with different models and installation orientations of water-based energy storage battery packs.

[0018] 3. The capillary core is a porous structure of sintered metal powder, which can provide stable and sufficient capillary suction force to ensure reliable overcoming of gravity to drive the liquid working fluid backflow. It can improve the working fluid circulation stability and heat exchange efficiency, and has the advantages of high temperature resistance, corrosion resistance and long service life, making it suitable for harsh environments with high humidity and high salt spray on the water surface.

[0019] 4. By limiting the underwater condenser to a finned tube heat exchange structure, the heat exchange area can be significantly increased, enhancing the heat exchange efficiency between steam and water, improving condensation speed and heat dissipation capacity, fully utilizing the natural cold source of water, and rapidly converting steam into a liquid working fluid to maintain stable loop pressure. This structure has low flow resistance, is corrosion-resistant, and is easy to install underwater, meeting the requirements for long-term continuous operation and improving the overall system's heat dissipation efficiency and reliability.

[0020] 5. Steam and liquid pipelines are laid securely along the outer wall of the support column using pipe clamps, and the length is not less than the height of the support column. This ensures that the pipelines are laid out neatly and firmly, resisting the disturbance of wind and waves on the water surface and avoiding shaking and damage.

[0021] 6. Adding a liquid receiver to the phase change circulation loop can connect to the liquid pipeline or be fixed to the evaporator shell. It can effectively regulate the volume and pressure of the phase change working fluid in the loop, buffer the volume expansion or contraction caused by temperature changes, and avoid abnormal pressure damage to the pipeline.

[0022] 7. A thermally conductive interface material is placed between the evaporator and the battery pack to fill the tiny gaps in the contact surface, eliminate the thermal resistance caused by the air layer, achieve a low-resistance and high-efficiency heat conduction connection, significantly improve the heat transfer speed, improve the heat dissipation response speed, avoid local overheating due to poor contact, and protect the safe operation of the battery pack.

[0023] 8. A phase change material layer is sandwiched between the evaporator and the battery pack. This can absorb the thermal shock generated by the instantaneous high-power discharge of the battery pack, stabilize temperature fluctuations, suppress temperature spikes, and protect the battery from high-temperature damage. The phase change material layer can achieve temperature uniformity and heat buffering, improve the stability of the system under varying operating conditions, and at the same time, it does not increase additional energy consumption or moving parts.

[0024] 9. By employing multiple evaporators arranged in parallel and sharing an underwater condenser, centralized heat dissipation of multiple battery packs can be achieved, increasing energy storage density per unit space, simplifying piping layout and installation procedures, and improving heat dissipation capacity through the convergence of multiple evaporators. The shared underwater condenser reduces costs, minimizes underwater nodes, and enhances system reliability. This modular design allows for flexible expansion of heat dissipation capacity, making it suitable for medium to large-scale floating photovoltaic energy storage power stations and enhancing its engineering application value. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic diagram of an embodiment of the pumpless self-circulating loop heat pipe cooling system for an underwater energy storage battery pack provided by the present invention; Figure 2 A schematic diagram of the second embodiment of the pumpless self-circulating loop heat pipe cooling system for a floating energy storage battery pack provided by the present invention; Figure 3 A schematic diagram of the third embodiment of the pumpless self-circulating loop heat pipe cooling system for a floating energy storage battery pack provided by the present invention; Figure 4 A schematic diagram of the fourth embodiment of the pumpless self-circulating loop heat pipe cooling system for a floating energy storage battery pack provided by the present invention; In the diagram: 1. Photovoltaic module; 2. Support column; 3. Triangular bracket; 4. Energy storage battery pack; 5. Phase change thermal storage material; 6. Evaporator; 7. Steam pipeline; 8. Liquid pipeline; 9. Underwater condenser; 10. Water body; 11. Water surface platform. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] To address the technical deficiencies mentioned in the background section, this embodiment provides a pump-free self-circulating loop heat pipe cooling system and method for a floating energy storage battery pack. The invention will be further described in detail below with reference to the accompanying drawings: In a first aspect, this invention provides a pumpless self-circulating heat pipe cooling system for an underwater energy storage battery pack, comprising: an evaporator 6 disposed on the heat exchange surface of an underwater energy storage battery pack 4, the evaporator 6 having a capillary wick structure inside; a steam pipeline 7, one end of which is sealed and connected to the steam outlet of the evaporator 6, and the other end extending downward below the water surface; an underwater condenser 9 submerged in water 10, the steam inlet of the underwater condenser 9 being sealed and connected to the other end of the steam pipeline 7; and a liquid pipeline 8, one end of which is sealed and connected to the liquid outlet of the underwater condenser 9, and the other end of the liquid pipeline 8 being sealed and connected to the liquid inlet of the evaporator 6; wherein the evaporator 6, the steam pipeline 7, the underwater condenser 9, and the liquid pipeline 8 are sequentially sealed and connected to form a phase change circulation loop, the phase change circulation loop being filled with a phase change working fluid; the capillary force generated by the capillary wick can overcome gravity and drive the liquid working fluid to autonomously flow back from the underwater condenser 9 to the evaporator 6, achieving pumpless self-circulating heat dissipation.

[0029] Example 1 like Figure 1As shown, the overall structure of this embodiment includes a photovoltaic module 1, a support column 2, a triangular bracket 3, an energy storage battery pack 4, an evaporator 6, a steam pipeline 7, a liquid pipeline 8, an underwater condenser 9, and a water body 10. The support column 2 is vertically and fixedly installed inside the water body 10, with its bottom firmly connected to the bottom foundation. The top is used to install the photovoltaic module 1, and the triangular bracket 3 is fixedly connected in the middle. The triangular bracket 3 is made of high-strength corrosion-resistant metal material and has the properties of wind and waves resistance, vibration resistance, and corrosion resistance. It is used to stably support the energy storage battery pack 4, ensuring that the energy storage battery pack 4 maintains structural stability in the environment of high humidity, high salt spray, and wind and waves on the water surface, and avoiding problems such as shaking, displacement, and falling off that affect the safe operation of the heat dissipation system and electrical system.

[0030] Photovoltaic module 1 is installed on the top of support column 2 to convert solar energy into electrical energy. On the one hand, it supplies power to external loads, and on the other hand, it provides charging power to energy storage battery pack 4. Together with energy storage battery pack 4, it realizes energy dispatch, smooths out the fluctuation of photovoltaic output, and improves the overall revenue of the power station, which meets the core application requirements of water surface photovoltaic power storage.

[0031] In this embodiment, the energy storage battery pack 4 is a lithium iron phosphate battery pack, which is fixed to the middle of the support column 2 by the triangular bracket 3 and is located above the water surface, forming a heat source layout on the top. The underwater condenser 9 is submerged in the water body 10 below the water surface, forming a cold source layout on the bottom. This creates a vertical height difference, providing the basic scenario conditions for the pumpless self-circulating heat dissipation of the present invention.

[0032] Furthermore, the evaporator 6 is a flat-plate evaporator 6, with its heat exchange surface tightly attached to the bottom or side of the energy storage battery pack 4, forming a stable heat conduction connection. There are no gaps or air layers between the two, ensuring rapid and efficient heat transfer. The evaporator 6 is equipped with a capillary wick structure. The capillary wick adopts a porous structure of sintered metal powder with a porosity controlled at 70%~80% and an average pore size of 10~50 micrometers. It has excellent capillary suction capability and can generate a sufficiently large capillary force to overcome the gravity and pipeline pressure drop during the liquid working fluid reflux process, ensuring stable and autonomous reflux of the working fluid.

[0033] In addition, the evaporator shell is made of a metal material with excellent thermal conductivity and corrosion resistance, and the outer wall is sealed and insulated to adapt to high humidity and high salt spray environments on the water surface, preventing water vapor and salt spray from entering the interior and causing short circuits, corrosion and other failures.

[0034] One end of the steam pipeline 7 is sealed to the steam outlet of the evaporator 6. The sealing method is welding or flange sealing to ensure the airtightness of the circuit and prevent leakage of the phase change working fluid and the entry of external water vapor. The other end of the steam pipeline 7 extends downward along the outer wall of the support column 2 until it is below the water surface, and is sealed to the steam inlet of the underwater condenser 9.

[0035] Among them, the steam pipeline 7 is made of insulated pipe material, and the outer wall is covered with an insulation layer to reduce the heat loss of steam during the transportation process, ensuring that the steam enters the underwater condenser 9 at a higher temperature and improving the heat exchange efficiency. The steam pipeline 7 is laid securely along the outer wall of the support column 2 by pipe clamps. The pipe clamps are arranged at equal intervals to ensure that the pipeline is laid neatly and firmly, without shaking or falling off. The length of the steam pipeline 7 is not less than the height of the support column 2, which meets the vertical height transmission requirements and can realize long-distance heat transmission, breaking through the traditional heat pipe transmission limit of less than 0.5 meters.

[0036] In this embodiment, the underwater condenser 9 is completely submerged inside the water body 10, with an installation depth of 1 to 2 meters below the water surface. It makes full use of the natural water body 10 as a natural cold source, eliminating the need for additional cooling units, heat dissipation towers, and other equipment. The underwater condenser 9 adopts a finned tube heat exchange structure, with fins evenly distributed on the outer wall of the condenser tube, significantly increasing the heat exchange area and improving condensation efficiency. The material is selected as copper alloy or stainless steel that is resistant to seawater corrosion, allowing it to operate stably for a long time in different water environments such as freshwater and seawater, without rusting, corroding, or leaking.

[0037] The steam inlet of the underwater condenser 9 is sealed and connected to the steam pipeline 7, and the liquid outlet is sealed and connected to the liquid pipeline 8. After the steam enters the underwater condenser 9, it undergoes forced heat exchange with the low-temperature water body 10, releases the latent heat of vaporization, and rapidly condenses into a liquid phase change working fluid, thus completing the final release of heat to the water body 10.

[0038] Furthermore, one end of the liquid pipeline 8 is sealed and connected to the liquid outlet of the underwater condenser 9, and the other end extends upward along the outer wall of the support column 2, and is sealed and connected to the liquid inlet of the evaporator 6. It is laid in parallel with the steam pipeline 7 and is also fixed to the outer wall of the support column 2 by pipe clamps. Its length is not less than the height of the support column 2. The inner wall of the liquid pipeline 8 is smooth to reduce the flow resistance of the liquid working fluid. The outer wall is also heat-insulated to prevent the temperature of the working fluid from being affected by the temperature of the external environment.

[0039] Evaporator 6, steam pipeline 7, underwater condenser 9, and liquid pipeline 8 are sequentially sealed and connected to form a complete closed phase change circulation loop. The loop is filled with a phase change working fluid, which is selected from ethanol, ammonia, acetone, R134a, or R245fa. The selection is flexible according to the ambient temperature of the water area and the operating temperature range of the energy storage battery pack 4. The amount of working fluid charged is precisely controlled according to the loop volume and operating pressure to ensure stable operation of the system under different operating conditions.

[0040] In this embodiment, the phase change circulation loop can also be equipped with a liquid receiver, which is sealed and connected to the liquid pipeline 8 or sealed and connected to the shell of the evaporator 6. This liquid receiver is used to regulate the amount of working fluid charged inside the system, buffer operating pressure fluctuations, and prevent abnormal loop pressure caused by the expansion or contraction of the working fluid volume due to temperature changes, thereby improving the system's operational stability and safety. A thermally conductive interface material is filled and adhered between the heat exchange surfaces of the evaporator 6 and the energy storage battery pack 4. This material fills the tiny gaps between the two surfaces, reducing contact thermal resistance and forming a low-resistance thermal conduction connection, further improving heat transfer efficiency.

[0041] In this embodiment, the system workflow is as follows: During the charging and discharging operation, the energy storage battery pack 4 continuously generates heat, which is rapidly transferred to the evaporator 6 via thermal conduction. The liquid phase change working fluid inside the evaporator 6 absorbs heat, and after its temperature rises to the phase change temperature, it vaporizes and transforms into gaseous steam. Driven by the pressure inside the evaporator 6, the steam enters the steam pipeline 7 through the steam outlet and flows downward along the steam pipeline 7 to the underwater condenser 9. After entering the underwater condenser 9, the steam undergoes efficient heat exchange with the low-temperature water body 10, releasing its latent heat of vaporization, causing its temperature to drop rapidly, and it re-condenses into a liquid phase change working fluid. Under the capillary force generated by the capillary wick inside the evaporator 6, the working fluid overcomes its own gravity and the flow resistance inside the liquid pipeline 8, and flows back up along the liquid pipeline 8 to the inside of the evaporator 6 to re-participate in the heat absorption and vaporization process. The above process repeats continuously, forming a pump-free, power-free, self-circulating phase change heat dissipation system that continuously transfers the heat generated by the energy storage battery pack 4 to the water body 10 for dissipation. This ensures that the temperature of the energy storage battery pack 4 is stable within the optimal operating range of 15-35℃, avoids the generation of local hot spots, extends the battery cycle life, and ensures the long-term stable operation of the system in an unattended water surface environment.

[0042] Example 2 This embodiment is an optimization and improvement on the basic structure of embodiment 1. The difference is that a phase change material layer 5 is sandwiched between the heat exchange surface of the evaporator 6 and the energy storage battery pack 4. The rest of the structural composition, connection relationship, installation layout and material selection are consistent with embodiment 1. It is suitable for application scenarios where the energy storage battery pack 4 has instantaneous high power discharge and large thermal shock. It can further improve temperature uniformity, suppress temperature peaks and enhance the adaptability of system operating conditions.

[0043] like Figure 2 As shown, the overall structure of this embodiment includes a photovoltaic module 1, a support column 2, a triangular bracket 3, an energy storage battery pack 4, a phase change material layer 5, an evaporator 6, a steam pipeline 7, a liquid pipeline 8, an underwater condenser 9, and a water body 10. The installation position, connection method, material selection, and function of the support column 2, photovoltaic module 1, triangular bracket 3, energy storage battery pack 4, steam pipeline 7, liquid pipeline 8, and underwater condenser 9 are exactly the same as those in embodiment 1, ensuring the stable realization of the basic heat dissipation function.

[0044] Furthermore, the phase change material layer 5 is sandwiched between the heat exchange surface of the energy storage battery pack 4 and the heat exchange surface of the evaporator 6. The phase change material layer 5 forms a fully bonded and gapless thermal conduction connection with the energy storage battery pack 4 and the evaporator 6 respectively. The three are tightly pressed together to ensure smooth heat transfer.

[0045] The phase change material layer 5 uses phase change thermal storage material 5, which has a fixed phase change temperature point. When the energy storage battery pack 4 generates a sudden high-power thermal shock, it can quickly absorb a large amount of latent heat, buffer temperature fluctuations, and avoid local overheating of the evaporator 6 and the inside of the battery pack. When the heat load of the battery pack decreases, the phase change material layer 5 can slowly release the stored heat to maintain the system temperature stability and avoid damage to battery performance caused by sudden temperature rises and falls.

[0046] Evaporator 6 remains a flat-plate evaporator, with its internal sintered metal powder porous capillary core structure unchanged. The capillary force is sufficient to overcome gravity and drive the liquid working fluid backflow. Steam pipeline 7 and liquid pipeline 8 are still laid along the outer wall of support column 2 and secured by pipe clamps, with a length not less than the height of support column 2. The underwater condenser 9 maintains its finned tube corrosion-resistant structure and is submerged 1 to 2 meters below the water surface. The phase change circulation loop is filled with phase change working fluid and can be equipped with a liquid receiver to regulate the pressure and working fluid mass. The space between evaporator 6 and phase change material layer 5 can also be filled with a heat-conducting interface material to further reduce thermal resistance.

[0047] The workflow of this embodiment is basically the same as that of embodiment 1, except that a phase change thermal storage buffer is added to the heat transfer path. The heat generated by the charging and discharging of the energy storage battery pack 4 is first transferred to the phase change material layer 5. When the heat load of the battery pack is small, the heat is directly transferred to the evaporator 6 through the phase change material layer 5. When the battery pack experiences instantaneous high-power discharge and generates a large amount of heat, the phase change material layer 5 quickly absorbs the excess heat and undergoes a phase change to store latent heat, suppressing the rapid rise in temperature and avoiding direct thermal shock to the evaporator 6 and the battery body. After temperature buffering and equalization, the heat is stably transferred to the evaporator 6, driving the internal working fluid to vaporize. The steam is transported to the underwater condenser 9 via the steam pipeline 7 and condensed into liquid. The liquid working fluid flows back to the evaporator 6 through the liquid pipeline 8 under the action of capillary force, completing the circulating heat dissipation.

[0048] Based on Example 1, this embodiment adds the thermal buffering and temperature equalization function of the phase change material layer 5, which can effectively cope with variable operating conditions and high-power operation scenarios, further improve heat dissipation stability and battery protection effect, retain all the beneficial effects such as pump-free self-circulation, long-distance heat transfer, and utilization of water cold source, while enhancing the system's tolerance to thermal shock, extending the service life of battery and heat dissipation system, and adapting to the heat dissipation requirements of higher power density floating energy storage battery pack 4.

[0049] Example 3 This embodiment features a centralized heat dissipation structure consisting of multiple support columns 2, multiple energy storage battery packs 4, evaporators 6 connected in parallel, and a shared underwater condenser 9. It is suitable for medium-sized floating photovoltaic energy storage power stations, can increase the energy storage density per unit water surface, simplify the pipeline layout, and reduce installation and maintenance costs. It is a modular extension application of the basic structure of Embodiment 1.

[0050] like Figure 3 As shown, this embodiment adopts a layout of double support columns 2 or multiple support columns 2. Each support column 2 is vertically fixed in the water body 10 with uniform spacing. Photovoltaic modules 1 are installed on the top of each column, and energy storage battery packs 4 are fixedly installed in the middle through triangular brackets 3. Each heat exchange surface of the energy storage battery pack 4 is equipped with an evaporator 6. Multiple evaporators 6 are arranged in parallel to form a multi-heat source collection structure.

[0051] Each evaporator 6 is a flat plate evaporator 6, equipped with a porous capillary core of sintered metal powder inside. The heat exchange surface is tightly attached to the energy storage battery pack 4. A phase change material layer 5 or a thermal interface material can be added to improve the heat dissipation effect.

[0052] The steam outlets of each evaporator 6 are connected to the main steam pipeline 7 via branch pipes and sealed. The main steam pipeline 7 extends downward along the outer wall of the support column 2 and is sealed to the steam inlet of the shared underwater condenser 9. The liquid inlets of each evaporator 6 are connected to the main liquid pipeline 8 via branch pipes and sealed. The main liquid pipeline 8 is sealed to the liquid outlet of the underwater condenser 9.

[0053] The diameters of the main steam pipeline 7 and the main liquid pipeline 8 are larger than those of the branch pipelines, which meets the requirements for the convergence and transmission of multiple steam and liquid working fluids. The two main pipelines are laid in parallel and fixed to the outer wall of the support column 2 by pipe clamps. The length is not less than the height of the support column 2 to ensure stable transmission over long distances.

[0054] The underwater condenser 9 is a large-capacity finned tube enhanced heat exchange structure, made of corrosion-resistant copper alloy or stainless steel. It spans the underwater area between multiple support columns 2, with an immersion depth of 1-2 meters. The heat exchange area is designed to match the number of parallel evaporators 6 and the total heat dissipation power, simultaneously meeting the heat dissipation needs of multiple energy storage battery packs 4. Compared to the single evaporator 6 and single condenser 9 structure of Embodiment 1, this embodiment uses a shared underwater condenser 9, reducing the number of underwater connection nodes, lowering the difficulty of underwater installation and the risk of leakage, simplifying the system structure, and improving overall reliability.

[0055] The phase change circulation loop consists of multiple parallel evaporators 6, a main steam pipeline 7, a shared underwater condenser 9, and a main liquid pipeline 8. It is filled with a sufficient amount of phase change working fluid and can be equipped with a liquid receiver installed on the main liquid pipeline 8. The liquid receiver is used to balance the pressure of multiple loops, regulate the total amount of working fluid, and ensure that the working fluid circulation in each parallel branch is uniform, unblocked, and uninterrupted.

[0056] In this embodiment, the workflow is as follows: multiple energy storage battery packs 4 operate synchronously to generate heat, which is transferred to corresponding parallel evaporators 6; the working fluid inside each evaporator 6 absorbs heat and vaporizes synchronously, and the generated steam flows into the main steam pipeline 7; the main steam pipeline 7 centrally transports multiple steam streams to a common underwater condenser 9; the steam undergoes uniform heat exchange and condenses into a liquid state in the condenser; under the capillary force generated by the capillary cores inside each evaporator 6, the liquid working fluid flows back evenly to each evaporator 6 through the main liquid pipeline 8 and branch pipelines, forming a multi-parallel, centralized heat dissipation, pump-free self-circulation working mode.

[0057] This embodiment achieves modular parallel expansion based on embodiment 1. The number of evaporators 6 and energy storage battery packs 4 can be flexibly adjusted according to the energy storage scale without increasing the number of condensers, which greatly improves space utilization and heat dissipation efficiency. It retains all the advantages such as no power, no maintenance, long-distance heat transfer, and adaptability to water layout. It is suitable for water photovoltaic energy storage scenarios with multiple support columns 2 distributed and centralized heat dissipation, solving the defects of traditional heat dissipation systems that cannot be scaled up.

[0058] Example 4 This embodiment features a multi-layer stacked energy storage battery pack 4, multiple evaporators 6 connected in parallel, and a centralized heat dissipation structure. It is suitable for large-scale floating photovoltaic energy storage power stations and centralized energy storage scenarios on water surface platforms 11. It can further improve the energy storage capacity density and is compatible with high-power, high-capacity, multi-layer floating energy storage systems. It is the implementation of the invention with the highest degree of integration.

[0059] like Figure 4 As shown, this embodiment eliminates the single-pillar arrangement mode and uses a water surface platform 11 as the basic load-bearing structure. The water surface platform 11 floats on the surface of the water body 10, providing stable buoyancy and resistance to wind and waves. The energy storage battery pack 4 is vertically arranged on the water surface platform 11 in a multi-layer stacking manner to form a large-capacity battery cluster. Each layer of the energy storage battery pack 4 has a corresponding evaporator 6 installed on its heat exchange surface. Multiple evaporators 6 are arranged in layers and in parallel. Each evaporator 6 is a flat plate structure with a capillary wick inside. The heat exchange surface is in close contact with the battery pack. A phase change material layer 5 can be optionally added to improve the thermal buffering performance.

[0060] The steam outlets of each evaporator 6 are connected to the stratified main steam pipeline 7, and the liquid inlets of each evaporator 6 are connected to the stratified main liquid pipeline 8. The main steam pipeline 7 and the main liquid pipeline 8 extend vertically downwards along the edge of the water surface platform 11, directly connecting to the underwater condenser 9 submerged in the water body 10. The underwater condenser 9 adopts a high-power finned tube heat exchange structure, installed at a position of about 1.5 meters below the water surface, with a heat exchange area matching the total heat dissipation of the multi-layer battery pack. The material is corrosion-resistant stainless steel or copper alloy to ensure long-term stable operation.

[0061] Steam pipeline 7 and liquid pipeline 8 are securely laid along the water surface platform 11 and the supporting structure, fixed with pipe clamps to prevent damage from shaking. The pipeline length meets the vertical height transmission requirements, enabling long-distance heat transfer. The phase change circulation loop is filled with a suitable phase change working fluid and equipped with a liquid receiver installed on the main liquid pipeline 8. The liquid receiver is used to balance the system pressure, regulate the working fluid charge, and ensure uniform and stable working fluid circulation in the multi-layer evaporator 6.

[0062] In this embodiment, the working process involves the synchronous operation of multi-layer stacked energy storage battery packs 4, which generate a large amount of heat. The heat from each layer is transferred to the corresponding evaporator 6. The working fluid inside each evaporator 6 absorbs heat and vaporizes, and the steam is layered and flows into the main steam pipeline 7. The main steam pipeline 7 centrally transports multiple streams of steam to the underwater condenser 9 for condensation. The condensed liquid working fluid, under the action of capillary force, flows upward through the main liquid pipeline 8 and is evenly distributed to each layer of evaporator 6, forming a working mode of layered heat collection, centralized condensation and heat dissipation, and pump-free self-circulation.

[0063] This embodiment achieves high-capacity, high-power-density water-based energy storage and heat dissipation. It features a compact structure, reasonable layout, and simplified piping, making it suitable for large-scale water-based photovoltaic energy storage stations. It retains all the beneficial effects of being power-free, maintenance-free, having high-efficiency heat exchange, and utilizing water as a cold source. It solves the technical defects of traditional liquid cooling systems, which cannot be adapted to large-capacity stacked energy storage, and traditional heat pipes, which cannot transmit heat over long distances. It has extremely high engineering application value.

[0064] In a second aspect, this invention provides a pump-free self-circulating loop heat pipe cooling method for an aquatic energy storage battery pack. This method is implemented using the cooling system described in any of the above embodiments of this application. The method steps are complete, clear, and repeatable. It operates without pumps, power, or power throughout the entire process and is passively controlled. It is suitable for a layout where the heat source is on top and the cold source is below on water, thus overcoming the shortcomings of existing cooling technologies.

[0065] Step 1: The evaporator absorbs the heat generated by the water-based energy storage battery pack, causing the phase change working fluid inside the evaporator to evaporate and form steam. For example, the evaporator 6 is in close contact with the heat exchange surface of the water-based energy storage battery pack 4 to quickly absorb the heat generated during the charging and discharging process of the energy storage battery pack 4; after the phase change working fluid filled inside the evaporator 6 absorbs the heat, its temperature rises to the phase change temperature, and it changes from liquid to gaseous vapor, thus completing the heat collection and working fluid phase change process.

[0066] Step 2: The steam is transported through a steam pipeline to an underwater condenser submerged in water. The underwater condenser exchanges heat with the water, causing the steam to condense into a liquid phase change working fluid. For example, the steam generated inside the evaporator 6 is driven by the pressure difference to enter the steam pipeline 7; the steam is transported downward along the steam pipeline 7, passes through the water surface, and reaches the underwater condenser 9 submerged in the water body 10, realizing long-distance heat transfer and breaking through the traditional heat pipe transmission distance limitation.

[0067] After the underwater condensing and releasing steam enters the underwater condenser 9, it exchanges heat efficiently with the low-temperature natural water body 10, releasing the latent heat of vaporization. The temperature drops rapidly, and the steam re-condenses from a gaseous state into a liquid phase change working fluid, ultimately releasing the heat of the energy storage battery pack 4 into the water body 10, and completing the heat dissipation by utilizing the natural cold source of the water body 10.

[0068] Step 3: Under the action of capillary force generated by the capillary wick inside the evaporator, the capillary force overcomes gravity and drives the liquid phase change working medium to flow back to the evaporator through the liquid pipeline, forming a continuous pump-free self-circulating phase change heat dissipation, thereby realizing continuous heat dissipation for the water-based energy storage battery pack.

[0069] For example, under the capillary force generated by the capillary core inside the evaporator 6, the capillary force directly overcomes the gravity of the liquid working fluid and the flow resistance inside the liquid pipeline 8, driving the liquid phase change working fluid to flow back up along the liquid pipeline 8 into the evaporator 6 and re-participate in the heat absorption and vaporization cycle.

[0070] The continuous self-circulating heat dissipation process, as described in steps one through three above, forms a pump-free, power-free, and maintenance-free self-circulating phase change heat dissipation system. This system continuously transfers the heat generated by the water-based energy storage battery pack to the water body 10 for dissipation, ensuring that the battery pack temperature remains stable within the optimal operating range and achieving long-term stable heat dissipation.

[0071] This method requires no moving parts such as fans or pumps, consumes no additional energy, is unaffected by ambient wind speed and temperature, is simple to install, has extremely low maintenance costs, and can operate stably in high temperature, high humidity, and unattended water surface environments. It is perfectly suited to the heat dissipation needs of distributed, long-distance, and vertical layout of floating photovoltaic energy storage.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading the present invention, they can still make various changes, modifications or equivalent substitutions to the specific implementation of the invention, but these changes, modifications or equivalent substitutions are all within the scope of protection of the pending claims of the invention.

Claims

1. A pump-free self-circulating loop heat pipe cooling system for a floating energy storage battery pack, characterized in that, include: An evaporator is located on the heat exchange surface of an underwater energy storage battery pack, and the evaporator has a capillary wick structure inside. The steam pipeline has one end sealed and connected to the steam outlet of the evaporator, and the other end extends downward below the water surface. An underwater condenser is submerged in water, and the steam inlet of the underwater condenser is sealed and connected to the other end of the steam pipeline; A liquid pipeline, one end of which is sealed and connected to the liquid outlet of the underwater condenser, and the other end of which is sealed and connected to the liquid inlet of the evaporator; The evaporator, steam pipeline, underwater condenser and liquid pipeline are sequentially sealed and connected to form a phase change circulation loop, and the phase change circulation loop is filled with a phase change working fluid. The capillary force generated by the capillary wick can overcome gravity and drive the liquid working fluid to flow back from the underwater condenser to the evaporator autonomously, achieving pump-free self-circulating heat dissipation.

2. The pump-free self-circulating loop heat pipe cooling system for a floating energy storage battery pack according to claim 1, characterized in that, The evaporator is a flat plate evaporator, and the heat exchange surface of the flat plate evaporator is attached to the bottom surface of the energy storage battery pack to form a heat conduction connection. Alternatively, the heat exchange surface of the flat-plate evaporator may be attached to the side of the energy storage battery pack to form a heat conduction connection.

3. The pumpless self-circulating loop heat pipe cooling system for a floating energy storage battery pack according to claim 1, characterized in that, The capillary core is a porous structure of sintered metal powder.

4. The pump-free self-circulating loop heat pipe cooling system for a floating energy storage battery pack according to claim 1, characterized in that, The underwater condenser is a finned tube heat exchanger.

5. The pumpless self-circulating loop heat pipe cooling system for a floating energy storage battery pack according to claim 1, characterized in that, The steam pipeline and liquid pipeline are fastened along the outer wall of the photovoltaic support column on the water surface by pipe clamps, and the length of the steam pipeline and liquid pipeline is not less than the height of the photovoltaic support column on the water surface.

6. The pumpless self-circulating loop heat pipe cooling system for a floating energy storage battery pack according to claim 1, characterized in that, The phase change circulation loop is also equipped with a liquid reservoir; The liquid reservoir is sealed and connected to the liquid pipeline; or the liquid reservoir is sealed and connected to the shell of the evaporator.

7. The pump-free self-circulating loop heat pipe cooling system for a floating energy storage battery pack according to claim 1, characterized in that, A thermally conductive interface material is filled and bonded between the heat exchange surfaces of the evaporator and the energy storage battery pack to form a low-resistance thermal conduction connection.

8. The pump-free self-circulating loop heat pipe cooling system for a floating energy storage battery pack according to claim 1, characterized in that, A phase change material layer is sandwiched between the heat exchange surfaces of the evaporator and the energy storage battery pack, and the phase change material layer forms a thermal conductive connection with the evaporator and the energy storage battery pack respectively.

9. The pumpless self-circulating loop heat pipe cooling system for a floating energy storage battery pack according to claim 1, characterized in that, The evaporator is provided in multiple units and arranged in parallel; The steam outlets of each evaporator are all connected to the steam inlet of the underwater condenser via a confluence seal, and the liquid inlets of each evaporator are all connected to the liquid outlet of the underwater condenser via a confluence seal.

10. A pump-free self-circulating loop heat pipe cooling method for a floating energy storage battery pack, characterized in that, The method employs the pumpless self-circulating loop heat pipe cooling system for the aquatic energy storage battery pack as described in any one of claims 1-9, comprising: The evaporator absorbs the heat generated by the water-based energy storage battery pack, causing the phase change working fluid inside the evaporator to evaporate and form steam. The steam is transported via a steam pipeline to an underwater condenser submerged in water, where it exchanges heat with the water to condense into a liquid phase change working fluid. Under the capillary force generated by the capillary wick inside the evaporator, the capillary force overcomes gravity and drives the liquid phase change working fluid to flow back to the evaporator through the liquid pipeline, forming a continuous pump-free self-circulating phase change heat dissipation, thereby achieving continuous heat dissipation for the water-based energy storage battery pack.

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