A liquid cooling method and energy storage system that enables cooling water to be in a subcooled state.

Abstract

This invention relates to the field of liquid cooling technology, and particularly to a liquid cooling method and energy storage system that allows cooling water to be in a subcooled state. The method uses room-temperature liquid water as the coolant and cools it to a first temperature. Long-chain organic hydrocarbons are added to the surface of the coolant at the first temperature, while maintaining the coolant's isolation from the gas phase. The coolant is then further cooled to a second temperature while retaining its liquid state. A heat absorption process is performed on the coolant at the second temperature, followed by compression to restore it to room-temperature liquid state, completing the cooling cycle. This reduces the viscosity and flow resistance of the coolant during the liquid cooling process in the energy storage system, thereby improving the liquid cooling efficiency of the energy storage system.

Description

Technical Field

[0001] This invention relates to the field of liquid cooling technology, and in particular to a liquid cooling method and energy storage system that can make cooling water in a subcooled state. Background Technology

[0002] With the rapid development of renewable energy and the increasing demand for electricity in society, energy storage systems are being used more and more widely in modern power grids. They can effectively balance the relationship between power supply and demand and improve the stability and flexibility of power grid operation.

[0003] Currently, with the continuous improvement of energy density and power density of energy storage systems, heat dissipation has become a key challenge restricting the performance and safe operation of these systems. Traditional air cooling methods have low heat exchange efficiency and can no longer meet the heat dissipation requirements of high-density energy storage systems. Therefore, liquid cooling technology has become an important solution for heat dissipation in energy storage systems.

[0004] In existing liquid cooling technologies for energy storage systems, the coolant is mostly a mixture of alcohols and water. The high viscosity of this type of coolant leads to high flow resistance during the cooling process, which not only increases system energy consumption and operating load, but also directly limits the improvement of liquid cooling efficiency. Summary of the Invention

[0005] The technical problem to be solved by this invention is: how to reduce the viscosity and flow resistance of the coolant during the liquid cooling process of the energy storage system, so as to improve the liquid cooling efficiency of the energy storage system.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A liquid cooling method that allows cooling water to be in a subcooled state includes the following steps: S1. Use room temperature liquid water as the coolant and cool the coolant to a first temperature; S2. Add long-chain organic hydrocarbons to the surface of the coolant cooled to a first temperature, while keeping the coolant isolated from the gas phase; continue cooling the coolant to a second temperature, while maintaining the coolant's liquid properties; the second temperature is lower than the first temperature; S3. Perform heat absorption operation on the coolant at the second temperature; S4. After the coolant has absorbed heat, it is compressed to restore it to room temperature liquid state, thus completing the cooling cycle.

[0007] Another technical solution adopted in this invention is: An energy storage system for implementing the above-described liquid cooling method that allows cooling water to be in a subcooled state includes: A condenser is used to cool the coolant to a first temperature. A subcooler, connected to the condenser, is used to add long-chain organic hydrocarbons to the surface of the coolant cooled to a first temperature and to keep the coolant isolated from the gas phase; to continue cooling the coolant to a second temperature, while maintaining the coolant in a liquid state; the second temperature is lower than the first temperature; A heat exchanger, connected to the subcooler, is used to absorb heat from the coolant at a second temperature. The compressor, connected between the heat exchanger and the condenser, is used to compress the coolant after it has absorbed heat, so that the coolant returns to its room temperature liquid state.

[0008] The beneficial effects of this invention are as follows: This solution uses room-temperature liquid water to replace the traditional alcohol-water mixed coolant, fundamentally reducing the viscosity and flow resistance of the coolant. This solves the core problems of high flow resistance and high system energy consumption in existing technologies, laying the foundation for subsequent high-efficiency cooling. Step S2, based on the pre-cooling in Step S1, adds long-chain organic hydrocarbons and isolates the gas phase, eliminating the heterogeneous nucleation of ice crystals in liquid water molecules. This allows the coolant to cool to a second temperature far below its freezing point while maintaining a liquid state, overcoming the technical bottleneck of pure water easily freezing at low temperatures. This significantly reduces the coolant inlet temperature and forms a stepped cooling effect with Step S1, giving the coolant a much better low-temperature heat exchange capacity than traditional coolants. Step S3 utilizes the low-temperature subcooled coolant obtained in Step S2 to complete the heat absorption operation. With the significantly increased heat exchange temperature difference, it can quickly and efficiently transfer heat to the surface. The heat from the energy storage system is removed, creating a synergistic effect with the previous two steps to achieve low-temperature preparation and efficient heat exchange, fundamentally improving the heat dissipation efficiency of the energy storage system. Step S4 compresses the cooled liquid after heat absorption to restore it to a normal-temperature liquid state, forming a complete closed-loop cooling cycle with the previous three steps, realizing the recycling of the cooled liquid. The entire process is energy-saving and environmentally friendly, and the steps are smoothly connected and closely coordinated, forming an integrated cooling effect of "resistance reduction pre-cooling - subcooling temperature control - efficient heat absorption - circulation regeneration", which greatly improves the continuity and practicality of system operation. At the same time, the pure water coolant has no corrosive components such as carboxyl groups, which fundamentally avoids the problem of pipeline acid corrosion, and simultaneously improves the operational safety and service life of the entire cooling cycle system, solving many drawbacks of existing liquid cooling technology such as high flow resistance, low cooling efficiency, and easy corrosion of pipelines. Attached Figure Description

[0009] Figure 1 This is a flowchart of the liquid cooling method of the present invention that allows cooling water to be in a subcooled state; Figure 2 This is a connection block diagram of the energy storage system of the present invention; Figure 3 A graph showing the freezing rate versus time after adding long-chain organic hydrocarbons to the energy storage system of the present invention. Marker explanation: 1. Condenser; 2. Subcooler; 3. Heat exchanger; 4. Compressor; 5. Expansion valve; 6. Water pump; 7. Battery pack. Detailed Implementation

[0010] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0011] Please refer to Figure 1 A liquid cooling method that allows cooling water to be in a subcooled state includes the following steps: S1. Use room temperature liquid water as the coolant and cool the coolant to a first temperature; S2. Add long-chain organic hydrocarbons to the surface of the coolant cooled to a first temperature, while keeping the coolant isolated from the gas phase; continue cooling the coolant to a second temperature, while maintaining the coolant's liquid properties; the second temperature is lower than the first temperature; S3. Perform heat absorption operation on the coolant at the second temperature; S4. After the coolant has absorbed heat, it is compressed to restore it to room temperature liquid state, thus completing the cooling cycle.

[0012] As can be seen from the above description, the beneficial effects of the present invention are as follows: This solution uses room-temperature liquid water to replace the traditional alcohol-water mixed coolant, fundamentally reducing the viscosity and flow resistance of the coolant. This solves the core problems of high flow resistance and high system energy consumption in existing technologies, laying the foundation for subsequent high-efficiency cooling. Step S2, based on the pre-cooling in Step S1, adds long-chain organic hydrocarbons and isolates the gas phase, eliminating the heterogeneous nucleation of ice crystals in liquid water molecules. This allows the coolant to cool to a second temperature far below its freezing point while maintaining a liquid state, overcoming the technical bottleneck of pure water easily freezing at low temperatures. This significantly reduces the coolant inlet temperature and forms a stepped cooling effect with Step S1, giving the coolant a much better low-temperature heat exchange capacity than traditional coolants. Step S3 utilizes the low-temperature subcooled coolant obtained in Step S2 to complete the heat absorption operation. With the significantly increased heat exchange temperature difference, it can quickly and efficiently transfer heat to the surface. The heat from the energy storage system is removed, creating a synergistic effect with the previous two steps to achieve low-temperature preparation and efficient heat exchange, fundamentally improving the heat dissipation efficiency of the energy storage system. Step S4 compresses the cooled liquid after heat absorption to restore it to a normal-temperature liquid state, forming a complete closed-loop cooling cycle with the previous three steps, realizing the recycling of the cooled liquid. The entire process is energy-saving and environmentally friendly, and the steps are smoothly connected and closely coordinated, forming an integrated cooling effect of "resistance reduction pre-cooling - subcooling temperature control - efficient heat absorption - circulation regeneration", which greatly improves the continuity and practicality of system operation. At the same time, the pure water coolant has no corrosive components such as carboxyl groups, which fundamentally avoids the problem of pipeline acid corrosion, and simultaneously improves the operational safety and service life of the entire cooling cycle system, solving many drawbacks of existing liquid cooling technology such as high flow resistance, low cooling efficiency, and easy corrosion of pipelines.

[0013] Furthermore, the long-chain organic hydrocarbon is heavy paraffin oil.

[0014] As can be seen from the above description, heavy paraffin oil is selected as a long-chain organic hydrocarbon. It is immiscible with water and can form a stable coating layer on the water surface, effectively isolating the gas phase, ensuring the elimination of ice crystal heterogeneous nucleation, and ensuring that the coolant can stably enter the supercooled state without freezing. At the same time, heavy paraffin oil is chemically inert and will not react with the coolant or pipelines. It is non-corrosive and non-polluting, and its viscosity is moderate and will not increase the system flow resistance.

[0015] Furthermore, the heavy paraffin oil comprises the following components in weight percentage: Paraffinic hydrocarbons ~65%; cycloalkanes ~29%; aromatic hydrocarbons ~6%.

[0016] As can be seen from the above description, the heavy paraffin oil with this ratio has the best surface coverage and phase isolation effect, which can accurately eliminate the heterogeneous nucleation of ice crystals of liquid water molecules and ensure that the coolant is stably cooled to a supercooled state of -12℃; moreover, the heavy paraffin oil with this ratio has good thermal stability and will not decompose or deteriorate with changes in system temperature, and can be reused for a long time, reducing system maintenance costs.

[0017] Furthermore, the first temperature is higher than the freezing point of the coolant, and the second temperature is lower than the freezing point of the coolant.

[0018] As can be seen from the above description, the first temperature achieves preliminary pre-cooling of the coolant, laying the foundation for subsequent subcooling treatment and avoiding freezing caused by direct low-temperature cooling; the second temperature achieves subcooling treatment, maximizing the reduction of coolant temperature to improve heat exchange efficiency, while ensuring that the coolant remains liquid through long-chain organic hydrocarbons, solving the technical problem that pure water is prone to freezing at low temperatures and cannot be used as a coolant.

[0019] Furthermore, the first temperature range is 0℃~4℃.

[0020] As can be seen from the above description, this range is the optimal pre-cooling temperature for room temperature liquid water, which can effectively reduce the temperature and prevent the room temperature liquid water from freezing, thus ensuring the stability of the pre-cooling process. At the same time, this temperature forms a reasonable temperature gradient with the subsequent -12℃ supercooled state, reducing the difficulty of system temperature control and energy consumption, and making the cooling process easier to control.

[0021] Furthermore, the second temperature is -12°C.

[0022] As can be seen from the above description, this temperature is the optimal subcooling temperature for room temperature liquid water under heavy paraffin oil coverage. It can significantly reduce the inlet temperature of the coolant, so that the heat exchange efficiency of the energy storage system can reach the best level, and can also ensure that the room temperature liquid water can be stably maintained in a liquid state without the risk of freezing. At the same time, -12℃ will not cause low-temperature damage to the liquid cooling pipeline and equipment, thus balancing cooling efficiency and equipment safety.

[0023] Please refer to Figure 2 An energy storage system for implementing the above-described liquid cooling method that allows cooling water to be in a subcooled state includes: Condenser 1 is used to cool the coolant to a first temperature; Subcooler 2, connected to condenser 1, is used to add long-chain organic hydrocarbons to the surface of the coolant cooled to a first temperature and to keep the coolant isolated from the gas phase; to continue cooling the coolant to a second temperature, while the coolant maintains its liquid properties; the second temperature is lower than the first temperature; Heat exchanger 3, connected to the subcooler 2, is used to absorb heat from the coolant at the second temperature; The compressor 4 is connected between the heat exchanger 3 and the condenser 1 and is used to compress the coolant after it has absorbed heat, so that the coolant is restored to a normal temperature liquid state.

[0024] As can be seen from the above description, the beneficial effects of the present invention are as follows: This solution uses room-temperature liquid water as the coolant, avoiding the problems of high viscosity, high flow resistance, and easy corrosion of pipelines associated with traditional alcohol-based coolants. This reduces system circulation energy consumption and improves operational safety. A subcooler 2 is installed between condenser 1 and heat exchanger 3. This subcooler 2 utilizes long-chain organic hydrocarbons to form an isolation layer on the water surface, effectively inhibiting heterogeneous ice crystal nucleation. This allows the room-temperature liquid water to be stably cooled to a subcooled state below its freezing point (e.g., -12℃), significantly reducing the temperature of the coolant before it enters heat exchanger 3. This significantly increases the heat exchange temperature difference with the heat-generating components, greatly improving heat dissipation efficiency. Through the closed-loop circuit formed by condenser 1, subcooler 2, heat exchanger 3, and compressor 4, the coolant is recycled. After absorbing heat, the subcooled water can be compressed back to room-temperature liquid state, ensuring the continuous and stable operation of the system. This energy storage system has a compact structure and high operating efficiency, significantly improving the thermal management capability and safety reliability of the energy storage system.

[0025] Furthermore, it also includes an expansion valve 5, which is connected between the subcooler 2 and the heat exchanger 3.

[0026] As described above, the expansion valve 5 added between the subcooler 2 and the heat exchanger 3 can throttle and reduce the pressure of the subcooled room temperature liquid water, precisely control the flow rate and pressure of the room temperature liquid water entering the heat exchanger 3, optimize the flow velocity and heat exchange contact area of ​​the room temperature liquid water in the heat exchanger 3, and improve the uniformity and efficiency of heat absorption and heat exchange; at the same time, it plays a pressure stabilizing role, which can prevent high pressure room temperature liquid water from directly entering the heat exchanger 3 and causing equipment impact, protect pipelines and equipment, and improve the stability of system operation.

[0027] Furthermore, it also includes a water pump 6, which is connected to the heat exchanger 3.

[0028] As can be seen from the above description, the addition of a water pump 6 connected to the heat exchanger 3 provides power for the circulation of room temperature liquid water throughout the liquid cooling system. The circulation speed of the room temperature liquid water can be precisely adjusted according to the heat dissipation load of the energy storage system, thereby achieving dynamic control of heat dissipation efficiency. For local high-heat areas in the high-density energy storage system, the heat dissipation effect can be enhanced by increasing the flow rate, avoiding excessively high local temperatures, and further improving the heat dissipation uniformity and safety of the energy storage system.

[0029] Furthermore, it also includes a battery pack 7, which is connected to the heat exchanger 3.

[0030] As can be seen from the above description, directly connecting the battery pack 7 to the heat exchanger 3 allows the subcooled room-temperature liquid water to directly exchange heat with the battery pack 7, significantly shortening the heat conduction path, improving heat exchange efficiency, and quickly removing the heat generated by the battery pack 7 during operation. This effectively controls the operating temperature of the battery pack 7 and prevents problems such as performance degradation and thermal runaway caused by high temperatures.

[0031] Please refer to Figure 1 As shown, one embodiment of the present invention is as follows: A liquid cooling method that allows cooling water to be in a subcooled state includes the following steps: S1. Room temperature liquid water is used as the coolant, and the coolant is cooled to a first temperature; the first temperature is higher than the freezing point of the coolant; the first temperature range is 0℃~4℃. S2. Add long-chain organic hydrocarbons to the surface of the coolant cooled to a first temperature, and keep the coolant isolated from the gas phase; continue to cool the coolant to a second temperature, and keep the coolant in a liquid state; the second temperature is lower than the first temperature; the second temperature is lower than the freezing point of the coolant; the second temperature is -12°C; S3. Perform heat absorption operation on the coolant at the second temperature; S4. After the coolant has absorbed heat, it is compressed to restore it to room temperature liquid state, thus completing the cooling cycle.

[0032] The long-chain organic hydrocarbon is heavy paraffin oil.

[0033] The heavy paraffin oil comprises the following components by weight percentage: Paraffinic hydrocarbons ~65%; cycloalkanes ~29%; aromatic hydrocarbons ~6%.

[0034] Please refer to Figure 2 and Figure 3 As shown, one embodiment of the present invention is as follows: Please refer to Figure 2 An energy storage system for implementing the above-described liquid cooling method that allows cooling water to be in a subcooled state includes a condenser 1, a subcooler 2, a heat exchanger 3, a compressor 4, an expansion valve 5, a water pump 6, and a battery pack 7. The condenser 1 is used to cool the coolant to a first temperature; The subcooler 2 is connected to the condenser 1 and is used to add long-chain organic hydrocarbons to the surface of the coolant cooled to a first temperature and keep the coolant isolated from the gas phase; continue to cool the coolant to a second temperature, and the coolant maintains its liquid properties; the second temperature is lower than the first temperature; The heat exchanger 3 is connected to the subcooler 2 and is used to absorb heat from the coolant at the second temperature. The compressor 4 is used to compress the coolant after it has absorbed heat, so that the coolant returns to a normal temperature liquid state.

[0035] The expansion valve 5 is connected between the subcooler 2 and the heat exchanger 3.

[0036] The water pump 6 is connected to the heat exchanger 3.

[0037] The battery pack 7 is connected to the water pump 6 and the heat exchanger 3 respectively.

[0038] The specific implementation steps of the energy storage system in this embodiment are as follows: Step 1: Use room temperature liquid water as coolant. Driven by water pump 6, the coolant enters condenser 1. Condenser 1 cools the room temperature liquid water to a first temperature of 0℃~4℃, completing the pre-cooling of the coolant. Step 2: The pre-cooled room-temperature liquid water enters subcooler 2. The heavy paraffin oil in subcooler 2 forms a stable coating layer on the surface of the room-temperature liquid water, completely isolating it from the gas phase and eliminating heterogeneous ice crystal nucleation of water molecules at the phase change temperature. Subcooler 2 continues to cool the room-temperature liquid water to a second temperature of -12°C. At this point, the room-temperature liquid water is in a subcooled state and maintains its liquid properties, without freezing (e.g., ...). Figure 3 (as shown) Step 3: The room temperature liquid water, which is in a subcooled state of -12℃, is throttled and depressurized by the expansion valve 5 and then enters the heat exchanger 3 connected to the battery pack 7. The room temperature liquid water directly exchanges heat with the battery pack 7 in the heat exchanger 3 to complete the heat absorption operation and quickly remove the heat generated by the battery pack 7 during operation, thereby achieving heat dissipation and cooling of the battery pack 7. Step 4: After absorbing heat, the room temperature liquid water rises in temperature and then enters compressor 4. Compressor 4 compresses the liquid water, generating heat through compression and then exchanging heat through condensation, restoring the room temperature liquid water to its initial state. The cooled room temperature liquid water then re-enters condenser 1, completing the entire cooling cycle.

[0039] In this embodiment, the dynamic viscosity of the room-temperature liquid water coolant is much lower than that of the traditional alcohol-water mixed coolant, reducing the flow resistance of the liquid cooling system by more than 80% compared to the prior art, and significantly reducing the system's operating energy consumption; the coolant inlet temperature is reduced to -12°C, and the liquid cooling efficiency of the energy storage system is improved by more than 50% compared to the prior art; the operating temperature of the battery pack 7 can be stably controlled within a suitable range, and the battery cycle life is improved by more than 30%; at the same time, the room-temperature liquid water coolant is non-corrosive, the heavy paraffin oil has stable chemical properties, and the entire liquid cooling system has no risk of pipeline corrosion, greatly improving operational safety and stability.

[0040] The liquid cooling method and energy storage system proposed in this solution can be widely used for heat dissipation and cooling of high-density energy storage equipment such as various electrochemical energy storage systems and new energy energy storage power stations. It effectively solves the core problems of high flow resistance and low cooling efficiency of existing liquid cooling technology, and can significantly improve the heat dissipation effect and operational safety of energy storage systems, extend the service life of energy storage units, reduce system operation and maintenance costs, adapt to the heat dissipation requirements of high-density energy storage systems, and has good industrial application prospects and promotion value.

[0041] In summary, this invention provides a liquid cooling method and energy storage system that allows cooling water to be in a subcooled state. It uses room-temperature liquid water instead of the traditional alcohol-water mixed coolant, fundamentally reducing the viscosity and flow resistance of the coolant. This solves the core problems of high flow resistance and high system energy consumption in existing technologies, laying the foundation for subsequent efficient cooling. Step S2, based on the pre-cooling in Step S1, adds long-chain organic hydrocarbons and isolates the gas phase, eliminating heterogeneous ice crystal nucleation of liquid water molecules. This allows the coolant to cool to a second temperature far below its freezing point while maintaining a liquid state, overcoming the technical bottleneck of pure water easily freezing at low temperatures. This significantly reduces the coolant inlet temperature, forming a stepped cooling effect with Step S1, giving the coolant a much better low-temperature heat exchange capacity than traditional coolants. Step S3 utilizes the low-temperature subcooled coolant obtained in Step S2 to complete the heat absorption operation, leveraging the significant… The increased heat exchange temperature difference can quickly and efficiently remove heat from the energy storage system, creating a synergistic effect with the first two steps of low-temperature preparation and efficient heat exchange, fundamentally improving the heat dissipation efficiency of the energy storage system. Step S4 compresses the cooled liquid after heat absorption to restore it to room temperature liquid state, forming a complete closed-loop cooling cycle with the first three steps, realizing the recycling of the cooled liquid. The entire process is energy-saving and environmentally friendly, and the steps are smoothly connected and closely coordinated, forming an integrated cooling effect of "resistance reduction pre-cooling - subcooling temperature control - efficient heat absorption - circulation regeneration", which greatly improves the continuity and practicality of system operation. At the same time, the pure water coolant has no corrosive components such as carboxyl groups, which fundamentally avoids the problem of pipeline acid corrosion, and simultaneously improves the operational safety and service life of the entire cooling cycle system, solving many drawbacks of existing liquid cooling technology such as high flow resistance, low cooling efficiency, and easy corrosion of pipelines.

[0042] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A liquid cooling method that enables cooling water to be in a subcooled state, characterized in that, Includes the following steps: S1. Use room temperature liquid water as the coolant and cool the coolant to a first temperature; S2. Add long-chain organic hydrocarbons to the surface of the coolant cooled to a first temperature, while keeping the coolant isolated from the gas phase; continue cooling the coolant to a second temperature, while maintaining the coolant's liquid properties; the second temperature is lower than the first temperature; S3. Perform heat absorption operation on the coolant at the second temperature; S4. After the coolant has absorbed heat, it is compressed to restore it to room temperature liquid state, thus completing the cooling cycle.

2. The liquid cooling method according to claim 1, which enables cooling water to be in a subcooled state, is characterized in that, The long-chain organic hydrocarbon is heavy paraffin oil.

3. The liquid cooling method according to claim 2, which enables cooling water to be in a subcooled state, is characterized in that, The heavy paraffin oil comprises the following components by weight percentage: Paraffinic hydrocarbons ~65%; cycloalkanes ~29%; aromatic hydrocarbons ~6%.

4. The liquid cooling method according to claim 1, which enables cooling water to be in a subcooled state, is characterized in that, The first temperature is higher than the freezing point of the coolant, and the second temperature is lower than the freezing point of the coolant.

5. The liquid cooling method according to claim 4, which enables cooling water to be in a subcooled state, is characterized in that, The first temperature range is 0℃~4℃.

6. The liquid cooling method according to claim 4, which enables cooling water to be in a subcooled state, is characterized in that, The second temperature is -12℃.

7. An energy storage system for implementing the liquid cooling method according to any one of claims 1 to 6, characterized in that, include: A condenser is used to cool the coolant to a first temperature. A subcooler, connected to the condenser, is used to add long-chain organic hydrocarbons to the surface of the coolant cooled to a first temperature and to keep the coolant isolated from the gas phase; to continue cooling the coolant to a second temperature, while maintaining the coolant in a liquid state; the second temperature is lower than the first temperature; A heat exchanger, connected to the subcooler, is used to absorb heat from the coolant at a second temperature. The compressor, connected between the heat exchanger and the condenser, is used to compress the coolant after it has absorbed heat, so that the coolant returns to its room temperature liquid state.

8. The energy storage system according to claim 7, characterized in that, It also includes an expansion valve connected between the subcooler and the heat exchanger.

9. The energy storage system according to claim 7, characterized in that, It also includes a water pump, which is connected to the heat exchanger.

10. The energy storage system according to claim 7, characterized in that, It also includes a battery pack, which is connected to the heat exchanger.

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