Battery thermal management and thermal runaway collaborative protection system based on incombustible refrigerant

Abstract

The invention discloses a battery thermal management and thermal runaway collaborative protection system based on a non-combustible refrigerant. An outlet of the compressor is connected with an inlet of the condenser; an outlet of the condenser is connected with an inlet of the gas separation device; a liquid outlet of the gas separation device is connected with the high-pressure liquid pipeline; an outlet of the high-pressure liquid pipeline is connected with the expansion valve; an outlet of the low-pressure liquid pipeline is connected with an inlet of the sealing shell; refrigerant gas sequentially passes through the compressor, the condenser, the gas separation device, the high-pressure liquid pipeline, the expansion valve and the low-pressure liquid pipeline from an outlet of the sealing shell and then returns to the liquid cooling plate of the sealing shell to form a refrigerating loop. The liquid cooling plate is integrated in the gaps of the battery clusters, and the loop is filled with a non-flammable refrigerant. According to the invention, a triple protection mechanism of efficient refrigeration, flame retardance, explosion prevention and combustible gas separation is provided, and the risk of occurrence and spreading of thermal runaway of the battery can be remarkably reduced.

Description

Technical Field

[0001] This invention belongs to the field of battery pack temperature control technology, specifically a battery thermal management and thermal runaway coordinated protection system based on non-flammable refrigerant. Background Technology

[0002] Driven by the integration of high-proportion renewable energy sources and the growth of high power loads, electrochemical energy storage technology has become one of the key supporting technologies for the global energy transition. Among the many energy storage technologies, lithium-ion batteries, with their advantages of high energy density and long cycle life, are widely used in fields such as power storage power stations and electric transportation.

[0003] However, the high energy density of lithium-ion batteries also makes them highly susceptible to thermal runaway when subjected to abuse conditions such as internal short circuits, thermal shock, or overcharging. Thermal runaway is a complex chain reaction process accompanied by violent heat release and the ejection of flammable gases. This process not only leads to the failure of individual battery cells but also easily induces thermal propagation at the module level or even the system level, seriously threatening the safe operation of energy storage systems and the safety of people and property. For example, in 2025, a fire broke out at a photovoltaic energy storage facility in Gangjin-dong, South Korea, destroying more than 500 square meters of energy storage facilities and 3,852 energy storage modules, causing property damage worth 10 billion won; in 2023, a 20MWh energy storage power station in Minqin County, Wuwei, Gansu Province, experienced thermal runaway due to overcharging, resulting in the burning of one energy storage battery compartment and direct economic losses of approximately 4.1 million yuan; in 2024, a fire caused by battery thermal runaway at a Neermoor lithium battery energy storage container in Germany resulted in injuries to two firefighters, the emergency closure of a highway for several hours, and economic losses of approximately 500,000 euros. Therefore, effective thermal management and thermal runaway protection are crucial for ensuring the performance, lifespan, and safety of lithium-ion batteries.

[0004] Existing thermal management techniques include air cooling, liquid cooling, and phase change cooling. Air cooling systems are simple in structure and low in cost, but their cooling efficiency and temperature uniformity are generally poor. Liquid cooling technology removes battery heat through coolant circulation, offering advantages in cooling efficiency and temperature uniformity. Phase change cooling utilizes the heat absorption of material phase changes, significantly improving heat transfer efficiency and suppressing nucleation boiling. However, these thermal management technologies primarily focus on heat dissipation, aiming to maintain the battery's operating temperature within a reasonable range. When faced with mechanical abuse or sudden, intense heat release caused by severe internal short circuits, external cooling often fails to curb the chain reaction within the cell, making it difficult to completely prevent thermal runaway of individual battery cells under extreme conditions.

[0005] Given the sporadic nature of individual thermal runaway, existing technologies also employ module-level structural design or thermal barrier methods to cut off heat propagation paths and suppress its spread. Common methods include implementing thermal insulation at the system level and using nanofiber aerogel composites, ceramic fiber felts, and other materials as insulation. However, physical barrier materials ultimately have limits to their heat resistance and impact resistance. If the energy release from thermal runaway is too violent, exceeding the protective threshold of the insulation layer or accompanied by high-pressure gas ejection igniting an open flame, this passive barrier will fail and will be unable to suppress the further spread of thermal runaway.

[0006] Fire extinguishing and explosion-proof technologies serve as emergency measures to address the failure of thermal spread, primarily targeting the risks of existing fires and explosions. For example, fine water mist can be used to delay thermal runaway through rapid cooling and oxygen isolation, or inert gases such as nitrogen and composite extinguishing agents can be used for suppression. However, the gases produced by thermal runaway (mainly composed of hydrogen, carbon monoxide, and alkanes) and the resulting high temperatures can accumulate within milliseconds, making it difficult for traditional fire extinguishing or explosion-proof systems triggered by smoke, temperature, or pressure thresholds to effectively halt the early stages of the accident. Controlling a single link in the chain is often insufficient to break the complex chain of "high temperature-high pressure-violent reaction," easily leading to reignition or secondary deflagration.

[0007] In summary, although existing research has made significant progress in suppressing triggering, preventing spread, and extinguishing fires and preventing explosions, the aforementioned phased defense systems still face severe challenges in real-world applications with high power and large capacity. An ideal protection system must overcome the limitations of single-point treatment and achieve a three-pronged approach that enhances heat dissipation, isolates oxygen, and manages combustible gas generation. Summary of the Invention

[0008] To address the problems existing in the background technology, the present invention provides a battery thermal management and thermal runaway coordinated protection system based on non-flammable refrigerant. The technical solution includes: a sealed shell, a compressor, a condenser, a gas separation device, a high-pressure liquid pipeline, an expansion valve, and a low-pressure liquid pipeline; wherein the outlet of the sealed shell is connected to the compressor inlet, the compressor outlet is connected to the condenser inlet, the condenser outlet is connected to the gas separation device inlet, the liquid outlet of the gas-liquid separator is connected to the high-pressure liquid pipeline, the outlet of the high-pressure liquid pipeline is connected to the expansion valve, the outlet of the expansion valve is connected to the low-pressure liquid pipeline, and the outlet of the low-pressure liquid pipeline is connected to the inlet of the sealed shell.

[0009] The refrigerant gas exits from the sealed housing and sequentially passes through the compressor, condenser, gas-liquid separator, high-pressure liquid line, expansion valve, and low-pressure liquid line before returning to the liquid-cooled plate of the sealed housing to form a refrigeration circuit.

[0010] The liquid cooling plate is integrated into the gap between the battery clusters, and the circuit is filled with non-flammable refrigerant; the inlet of the liquid cooling plate is connected to the outlet of the refrigerant delivery pipeline, and the outlets of the liquid cooling plate are connected to the inlet of the liquid storage tank and the refrigerant exhaust pipeline respectively through a gas-liquid mixing tee.

[0011] The sealed casing is internally sealed, ensuring that the battery clusters are always in a relatively stable atmosphere of non-flammable refrigerant gas.

[0012] The compressor inlet has a compressor flow regulating valve;

[0013] The gas separation device includes a gas-liquid separator, a gas-liquid separation exhaust pipe, and an exhaust valve. The inlet of the gas-liquid separator is connected to the outlet of the condenser, and the outlet is divided into two paths: the liquid refrigerant outlet is connected to the high-pressure liquid pipeline, and the gaseous combustible material outlet is connected to the exhaust pipeline.

[0014] The protection system also includes a liquid recovery device, in which the gas-liquid two-phase refrigerant from the outlet of the liquid-cooled plate enters the gas-liquid mixing tee, the gaseous refrigerant is directly introduced into the internal space of the sealed shell through the refrigerant exhaust pipe, and the liquid refrigerant flows into the storage tank and then re-enters the liquid-cooled plate through the pressurized reflux system to complete the recycling.

[0015] The non-flammable refrigerant is non-flammable in its gaseous state and has refrigerant properties in its liquid state, achieving heat exchange through the aforementioned circulation loop; at the same time, it dilutes the oxygen concentration in its gaseous state, blocking the combustion chain reaction; the refrigerant must have a boiling point below room temperature and above 0°C under normal pressure; in addition, to ensure that the refrigeration cycle can form a stable gas-liquid two-phase flow state, the refrigerant must condense into a liquid after the compression and condensation process to achieve effective circulation.

[0016] The protection system also includes a collaborative protection module; the collaborative protection module includes a pressure sensor, a temperature sensor, a combustible gas monitoring device, a normal operation module, and a safety pressure relief start / stop module; wherein, the pressure sensor is located inside the sealed housing at one end to detect the gas pressure inside the sealed housing chamber; the temperature sensor is located in each battery cluster to monitor the operating temperature of the battery cell or module in real time; a temperature sensor is also located inside the sealed housing to monitor the ambient temperature inside the sealed housing.

[0017] The combustible gas monitoring device is installed inside the sealed enclosure and can be used to monitor the concentration of combustible gases such as carbon monoxide and hydrogen in the internal space of the sealed enclosure to determine whether the battery has experienced thermal runaway; the oxygen concentration monitor is used to monitor the oxygen concentration inside the sealed enclosure in real time and can also determine whether non-flammable refrigerant gas has leaked in the space of the sealed enclosure.

[0018] When the work begins, non-flammable refrigerant is injected through the refrigerant charging port set on the sealed shell. After the combustible gas monitoring device detects that the oxygen concentration is lower than the preset limit oxygen concentration, it determines that the non-flammable refrigerant has reached the specified concentration and the seal meets the standard, and then the compressor and compressor flow regulating valve are turned on.

[0019] The sealed outer casing has a safety relief device to prevent excessive internal pressure during thermal runaway from causing structural damage or secondary explosion; the safety relief device opens in the event of thermal runaway.

[0020] When the normal operation module is working, the compressor flow regulating valve, compressor and expansion valve are open; the gas-liquid separator exhaust valve is open and the safety pressure relief device is closed; at the same time, the environment is monitored by the sensors in the collaborative protection module.

[0021] When the safety pressure relief start / stop module is working, it collects data from the pressure sensor in real time for monitoring. When the pressure sensor reading is higher than the rapid pressure relief threshold, it sends a control signal and activates the safety pressure relief device. When the pressure sensor reading returns to below the rapid pressure relief threshold, it sends a pressure relief shutdown message to the safety pressure relief start / stop module and sends a control signal to shut down the safety pressure relief device.

[0022] During normal operation, the exhaust valve of the gas-liquid separator is always open. As the refrigeration cycle continues, the gas separation device performs gas-liquid separation on the working fluid in the refrigeration cycle loop, continuously separating out air, water vapor, or other non-preset working fluid gases, and discharges the non-preset working fluid gases from the system through the exhaust valve of the gas-liquid separator, so as to maintain the concentration of non-flammable refrigerant gas in the sealed shell within a preset safe range.

[0023] When the combustible gas monitoring device detects that the concentration of combustible gas inside the sealed casing reaches a preset emergency concentration threshold, the temperature sensor detects that the temperature reaches a preset emergency temperature threshold, or the pressure sensor detects that the pressure reaches a preset emergency pressure threshold, a risk of thermal runaway is determined, and the safety pressure relief start-stop module starts working: immediately disconnecting the battery cluster and the system from the external circuit, stopping the charging and discharging operation; adjusting the compressor flow regulating valve to the maximum opening, and simultaneously increasing the opening of the gas-liquid separator exhaust valve based on the liquid level feedback of the gas-liquid separator to enhance the flow and entrainment capacity of the refrigerant gas; maintaining the continuous operation of the refrigeration cycle system, using the gaseous non-flammable refrigerant as the carrier gas to carry the combustible gas generated by thermal runaway to the gas separation device, achieving active separation and safe discharge of combustible gas through gas-liquid separation; when the exhaust capacity of the gas-liquid separator is insufficient, causing the pressure inside the sealed casing to exceed the preset safety pressure relief trigger pressure value, the safety pressure relief device is activated for secondary pressure relief and explosion prevention.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. This invention constructs a battery thermal management and thermal runaway collaborative protection system based on a non-flammable refrigerant, proposing a triple protection mechanism of efficient cooling, flame retardant and explosion-proof, and combustible gas separation. The evaporator adopts a liquid-cooled plate structure, which efficiently absorbs battery heat through refrigerant phase change; the gaseous working fluid formed by the evaporation of the non-flammable refrigerant diffuses into the sealed shell, actively reducing the oxygen concentration in the sealed shell to below a preset limit oxygen concentration, which can significantly reduce the risk of battery thermal runaway and its spread.

[0026] 2. During the liquid circulation process of non-flammable refrigerant, a gas-liquid separator is used to separate flammable gas, incoming air and liquid refrigerant in real time, and the exhaust pipe is linked to exhaust the flammable gas outside the cabin to prevent the accumulation of explosive gases such as hydrogen.

[0027] 3. The refrigerant is recycled in the system, eliminating the need for frequent replenishment of inert gas or extinguishing agent; the same refrigerant serves as a heat dissipation medium, a flame-retardant gas, and a carrier gas (carrying combustible gas), reducing system complexity.

[0028] 4. The evaporator adopts a liquid-cooled plate structure, which can utilize the compressor, condenser, and expansion valve from the air conditioning system. These three components are all outside the energy storage system, making it compatible with battery energy storage systems of different sizes. By reusing mature air conditioning components (compressor / condenser / expansion valve), system manufacturing costs are reduced and maintenance procedures are simplified.

[0029] 5. It solves the industry pain points of traditional solutions such as slow response and limited functionality, and has significant potential in the field of energy storage power stations. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of an embodiment of a battery thermal management and thermal runaway collaborative protection system based on a non-flammable refrigerant according to the present invention.

[0031] Figure 2 This is a comparison chart of the coefficients of performance (COPs) of various refrigerants in embodiments of the present invention.

[0032] In the diagram: 1-Sealed outer casing, 2-Compressor, 3-Condenser, 4-Gas separation device, 5-High-pressure liquid pipeline, 6-Expansion valve, 7-Low-pressure liquid pipeline, 10-Battery cluster, 11-Liquid cooling plate, 12-Refrigerant delivery pipeline, 13-Refrigerant exhaust pipeline, 14-Storage tank inlet, 15-Storage tank, 16-Pressurized reflux system, 17-Oxygen concentration monitor, 18-Combustible gas monitoring device, 19-Safety pressure relief device, 21-Compressor flow regulating valve, 41-Gas-liquid separator, 42-Gas-liquid separator exhaust pipeline, 43-Exhaust valve, P-Pressure sensor, T-Temperature sensor. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the accompanying drawings.

[0034] like Figure 1 The embodiment of the present invention shown includes: a sealed housing 1, a compressor 2, a condenser 3, a gas separation device 4, a high-pressure liquid pipeline 5, an expansion valve 6, and a low-pressure liquid pipeline 7; wherein the outlet of the sealed housing 1 is connected to the inlet of the compressor 2, the outlet of the compressor 2 is connected to the inlet of the condenser 3, the outlet of the condenser 3 is connected to the inlet of the gas separation device 4, the liquid outlet of the gas-liquid separator 41 is connected to the high-pressure liquid pipeline 5, the outlet of the high-pressure liquid pipeline 5 is connected to the expansion valve 6, the outlet of the expansion valve 6 is connected to the low-pressure liquid pipeline 7, and the outlet of the low-pressure liquid pipeline 7 is connected to the inlet of the sealed housing 1;

[0035] The refrigerant gas flows from the outlet of the sealed casing through the compressor 2, condenser 3, gas-liquid separator 41, high-pressure liquid line 5, expansion valve 6 and low-pressure liquid line 7 in sequence, and then returns to the liquid cooling plate 11 of the sealed casing to form a refrigeration circuit.

[0036] The liquid cooling plate 11 is integrated into the gap of the battery cluster 10, and the circuit is filled with non-flammable refrigerant; the inlet of the liquid cooling plate 11 is connected to the outlet of the refrigerant delivery pipe 12, and the outlets of the liquid cooling plate 11 are connected to the inlet of the liquid storage tank 15 and the refrigerant exhaust pipe 13 respectively through the gas-liquid mixing tee.

[0037] The interior of the sealed housing 1 is sealed, ensuring that the battery cluster 10 is always in a relatively stable atmosphere of non-flammable refrigerant gas.

[0038] The compressor 2 inlet has a compressor flow regulating valve 21. During the process of refrigerant being charged into the sealed housing 1, the valve is adjustable. In daily operation, the compressor (2) and the gas separation device (4) are always running to ensure that the battery is in a suitable operating temperature and a high concentration of inert atmosphere. At the same time, after the oxygen concentration monitor detects that the oxygen concentration is higher than the preset limit oxygen concentration, the operating power of the compressor is increased. At the same time, based on the liquid level feedback of the gas-liquid separator, the opening of its exhaust valve is increased to accelerate the separation of non-preset working gas.

[0039] The gas separation device 4 includes a gas-liquid separator 41, a gas-liquid separation exhaust pipe 42, and an exhaust valve 43. The inlet of the gas-liquid separator 41 is connected to the outlet of the condenser, and the outlet is divided into two paths: the liquid refrigerant outlet is connected to the high-pressure liquid pipeline 5, and the gaseous combustible material outlet is connected to the exhaust pipe 42.

[0040] The sealed housing 1 has a safety pressure relief device 19. When the pressure sensor (P) detects that the internal pressure of the sealed housing is higher than the preset safety pressure relief trigger pressure value, the safety pressure relief device 19 is opened to prevent the internal pressure of the system from being too high during thermal runaway, which could lead to structural damage or secondary explosion.

[0041] The system is also equipped with a liquid recovery device: the gas-liquid two-phase refrigerant at the outlet of the liquid cooling plate 11 enters the gas-liquid mixing tee, the gaseous refrigerant is directly introduced into the internal space of the sealed shell 1 through the refrigerant exhaust pipe 13, and the liquid refrigerant flows into the liquid storage tank 15 and then re-enters the liquid cooling plate 11 through the pressurized reflux system 16 to complete the recycling. In this embodiment, the pressurized reflux system 16 consists of a one-way valve near the refrigerant delivery pipe 12, a liquid pump near the liquid storage tank 15, a liquid level sensor installed in the liquid storage tank 15, and pipelines; when the liquid level sensor is triggered, the liquid pump operates for a period of time and will pressurize and transport the liquid refrigerant back to the refrigerant delivery pipe 12 to participate in the circulation.

[0042] The non-flammable refrigerant used in this embodiment is non-flammable in its gaseous state but possesses refrigerant properties in its liquid state. It achieves heat exchange through the circulation loop and simultaneously dilutes the oxygen concentration in its gaseous state, thus preventing a combustion chain reaction. The refrigerant must have a boiling point below room temperature and above 0°C at atmospheric pressure. Furthermore, to ensure a stable gas-liquid two-phase flow state in the refrigeration cycle, allowing the refrigerant to condense into a liquid after compression and condensation for effective circulation, the refrigerant must condense into a liquid after compression and condensation.

[0043] The non-flammable refrigerants used in this invention include, but are not limited to, trans-1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(E)), cis-1-chloro-2,3,3,4-tetrafluoropropene (HCFO-1224yd(Z)), or 1,1,1,3,3-pentafluoropropane (HFC-245fa). Figure 2 As shown, the performance of three suitable refrigerants—HCFO-1233zd(E), HCFO-1224yd(Z), and HFC-245fa—was compared. In the vapor compression refrigeration cycle, the evaporation temperature (the saturation temperature at which the refrigerant evaporates from a liquid to a gaseous state in the evaporator) was set to 20°C, and the condensation temperature (the saturation temperature at which the refrigerant condenses from a gaseous state to a liquid state in the condenser) varied within the range of 40°C to 70°C. The coefficient of performance (COP) of these three refrigerants was calculated and compared. Thermodynamic analysis results show that, under the above operating conditions, HCFO-1233zd(E) has the highest refrigeration capacity and cycle performance (i.e., the highest COP). Therefore, in this embodiment, HCFO-1233zd(E) is preferred as the refrigerant in the battery thermal management and thermal runaway synergistic protection system.

[0044] In this embodiment, the selected trans-1-chloro-3,3,3-trifluoropropylene (HCFO-1233zd) has an ASHRAE A1 safety rating, exhibits no flame propagation and low toxicity at room temperature and pressure, and has a boiling point below ambient temperature at normal pressure. This refrigerant has an ozone depletion potential of 0.00034 and a global warming potential of 1, thus having a small environmental impact and being environmentally friendly.

[0045] The working principle of the system is explained using HCFO-1233zd(E) as an example. Its boiling point at normal pressure is about 19°C. After compression and condensation, it can form a liquid state and rapidly vaporize and absorb heat when it enters the liquid cooling plate during throttling expansion, thus meeting the dual requirements of thermal control and safety protection of this system.

[0046] In this embodiment, the liquid cooling plate 11 is integrated into the gaps between battery clusters 10 by placing one liquid cooling plate 11 between every two battery clusters 10; the compressor 2 is a dual-rotor compressor, widely used in air conditioning systems, characterized by low-frequency energy efficiency, cost advantages, and flexible load adaptability; the liquid cooling plate 11 has a serpentine flow channel; the gas-liquid separator is a vertical gravity gas-liquid separator, with liquid refrigerant entering the expansion valve from the lower outlet and combustible gas entering the exhaust pipe from the upper end before being discharged into the atmosphere; the compressor 2, condenser, and expansion valve are standard air conditioning refrigeration system components; the evaporator adopts a liquid cooling plate 11 structure and is integrated into the gaps between battery clusters 10. The specific layout of embedding the liquid cooling plate 11 into the gaps between battery clusters 10 is that one liquid cooling plate 11 is placed between every two battery clusters 10.

[0047] The collaborative protection module includes: a pressure sensor P, a temperature sensor T, a combustible gas monitoring device 18, a normal operation module, and a safety pressure relief start / stop module. The pressure sensor P is located inside the sealed housing 1 and is used to detect the gas pressure within the sealed housing 1. The temperature sensor T is located in each battery cluster and is used to monitor the operating temperature of individual battery cells or modules in real time. A temperature sensor T is also located inside the sealed housing 1 to monitor the ambient temperature within the sealed housing 1. The combustible gas monitoring device 18, located inside the sealed housing 1, includes multiple gas concentration monitors and can be used to monitor the concentration of various combustible gases such as hydrogen and carbon monoxide to determine whether the battery has experienced thermal runaway.

[0048] The oxygen concentration monitor (17) is used to monitor the oxygen concentration inside the sealed housing in real time, and can also determine whether non-flammable refrigerant gas has leaked in the space of the sealed housing (1).

[0049] When thermal runaway occurs, the compressor flow regulating valve 21 and the gas-liquid separator exhaust valve 43 need to be increased to release the flammable mixture or excess refrigerant gas accumulated in the system, prevent abnormal increase in internal pressure, and the refrigeration cycle system (compressor 2 and other components) can continue to operate as needed during this process.

[0050] When the operation begins, non-flammable refrigerant is injected through the refrigerant charging port set on the sealed outer shell. After the combustible gas monitoring device 18 detects that the oxygen concentration is lower than the preset limit oxygen concentration, it determines that the non-flammable refrigerant has reached the specified concentration and the seal is up to standard, and then starts the compressor 2 and the compressor flow regulating valve 21.

[0051] When the normal operation module is working, the compressor flow regulating valve 21, compressor 2 and expansion valve 6 are open; the gas-liquid separator exhaust valve 43 is open and the safety pressure relief device 19 is closed; at the same time, the environment is monitored by the sensors in the collaborative protection module.

[0052] The safety pressure relief start / stop module is connected to the pressure sensor P. When the safety pressure relief start / stop module is working, it collects data sent by the pressure sensor P in real time and keeps it under monitoring. When the pressure sensor P is greater than the rapid pressure relief threshold, it sends a control signal and turns on the safety pressure relief device 19. When the pressure sensor P returns to below the rapid pressure relief threshold, it sends a pressure relief shutdown message to the safety pressure relief start / stop module and sends a control signal to turn off the safety pressure relief device 19.

[0053] The workflow of HCFO-1233zd in the thermal management and thermal runaway synergistic protection system is as follows:

[0054] During normal charging and discharging of the battery cluster 10, the compressor inlet flow valve 22 is open, and the gas-liquid separator exhaust valve (43) is always open. After the liquid refrigerant absorbs heat and undergoes phase change in the liquid cooling plate 11, it enters the sealed shell 1 under normal pressure (0.1MPa). At this time, the non-flammable refrigerant gas surrounds the battery cluster 10, realizing battery thermal management and thermal runaway protection functions. The gas separation device (4) performs gas-liquid separation on the working fluid in the refrigeration cycle loop, continuously separating out air, water vapor or other non-preset working fluid gases, and discharges the non-preset working fluid gases from the system through the gas-liquid separator exhaust valve (43) to maintain the concentration of non-flammable refrigerant gas in the sealed shell (1) within the preset safety range. The oxygen concentration is diluted to the preset limit. Once the oxygen concentration is below a certain level, the gaseous refrigerant enters the twin-rotor compressor 2 to be heated and pressurized. After compression, the high-temperature and high-pressure refrigerant flows through the condenser to be cooled into a liquid state, and then enters the high-pressure liquid pipeline 5 through the liquid outlet of the gas-liquid separator 41. After the liquid refrigerant is throttled down to atmospheric pressure by the expansion valve 6, it is transported to the refrigerant delivery pipeline 12 of the sealed shell 1 through the low-pressure liquid pipeline 7. Subsequently, the liquid refrigerant enters the liquid cooling plate 11, absorbs heat at approximately isobaric pressure, and evaporates into a gaseous state before entering the liquid cooling plate exhaust pipeline 13. The exhaust temperature of the liquid cooling plate 11 is higher than the boiling point of the refrigerant at atmospheric pressure. The incompletely vaporized liquid refrigerant leaves the liquid cooling plate 11 outlet pipeline and enters the liquid storage tank 15 inside the sealed shell 1, and then enters the liquid cooling plate 11 through the lower end pipeline for reuse, completing the cycle.

[0055] When the combustible gas monitoring device 18 detects that the concentration of combustible gas inside the sealed casing reaches a preset emergency concentration threshold, the temperature sensor T detects that the temperature reaches a preset emergency temperature threshold, or the pressure sensor P detects that the pressure reaches a preset emergency pressure threshold, it is determined that there is a risk of thermal runaway, and the safety pressure relief start-stop module starts working: immediately disconnecting the battery pack and the system from the external circuit, stopping the charging and discharging operation; adjusting the opening of the compressor flow regulating valve 21 to the maximum, and simultaneously increasing the opening of its exhaust valve based on the liquid level feedback of the gas-liquid separator to enhance the flow and entrainment capacity of the refrigerant gas; maintaining The refrigeration cycle system operates continuously, using gaseous non-flammable refrigerant as a carrier gas to carry the flammable gas generated by thermal runaway to the gas separation device 4. The flammable gas is actively separated and safely discharged through gas-liquid separation. When the gas-liquid separator's exhaust capacity is insufficient, causing the internal pressure of the sealed shell 1 to exceed the preset safety pressure relief trigger pressure value, the safety pressure relief device 19 is activated for secondary pressure relief and explosion prevention. Since the oxygen concentration inside the system is diluted to below the preset limit oxygen concentration, the environment is in a non-flammable state. When the gaseous refrigerant enters the compressor 2, it will actively carry the flammable gas generated by battery thermal runaway into the compressor 2. After being heated and pressurized by compressor 2, the mixed gas enters the condenser to be cooled to above 19°C (the boiling point of HCFO-1233zd(E) at normal pressure). At this point, the HCFO-1233zd refrigerant gas with a higher boiling point is cooled into a liquid state, while the combustible gas remains in a gaseous state. Subsequently, the liquid refrigerant and the gaseous combustible are efficiently separated by the gas separation device 4. The liquid refrigerant enters the expansion valve 6 to participate in the refrigeration cycle, while the combustible gas is discharged through the gas-liquid separation exhaust pipe 42, which realizes the protection against battery thermal runaway and the discharge of combustible gas. When the exhaust capacity of the gas-liquid separator is insufficient and the pressure sensor P detects that the pressure inside the chamber exceeds the safe pressure relief setting value, the safety pressure relief device 19 inside the sealed outer shell 1 is opened, and the gas is quickly discharged through the safety pressure relief device 19 to prevent secondary explosion.

Claims

1. A battery thermal management and thermal runaway coordinated protection system based on a non-flammable refrigerant, characterized in that, include: The components are: sealed housing (1), compressor (2), condenser (3), gas separator (4), high-pressure liquid pipeline (5), expansion valve (6), and low-pressure liquid pipeline (7); wherein the outlet of the sealed housing (1) is connected to the inlet of the compressor (2), the outlet of the compressor (2) is connected to the inlet of the condenser (3), the outlet of the condenser (3) is connected to the inlet of the gas separator (4), the liquid outlet of the gas-liquid separator (41) is connected to the high-pressure liquid pipeline (5), the outlet of the high-pressure liquid pipeline (5) is connected to the expansion valve (6), the outlet of the expansion valve (6) is connected to the low-pressure liquid pipeline (7), and the outlet of the low-pressure liquid pipeline (7) is connected to the inlet of the sealed housing (1); The refrigerant gas flows from the outlet of the sealed housing (1) through the compressor (2), condenser (3), gas-liquid separator (41), high-pressure liquid line (5), expansion valve (6) and low-pressure liquid line (7) in sequence and then returns to the liquid cooling plate (11) of the sealed housing (1) to form a refrigeration circuit. The liquid cooling plate (11) is integrated into the gap of the battery cluster (10), and the circuit is filled with non-flammable refrigerant; the inlet of the liquid cooling plate (11) is connected to the outlet of the refrigerant delivery pipe (12), and the outlet of the liquid cooling plate (11) is connected to the inlet of the liquid storage tank (15) and the refrigerant exhaust pipe (13) respectively through the gas-liquid mixing tee; The interior of the sealed housing (1) is sealed, ensuring that the battery cluster (10) is always in a relatively stable atmosphere of non-flammable refrigerant gas; The compressor (2) inlet has a compressor flow regulating valve (21); The gas separation device (4) includes: a gas-liquid separator (41), a gas-liquid separator exhaust pipe (42), and an exhaust valve (43). The inlet of the gas-liquid separator (41) is connected to the outlet of the condenser, and the outlet is divided into two paths: the liquid refrigerant outlet is connected to the high-pressure liquid pipeline (5), and the gaseous combustible material outlet is connected to the exhaust pipeline (42).

2. The battery thermal management and thermal runaway coordinated protection system based on non-flammable refrigerant according to claim 1, characterized in that, The protection system also includes a liquid recovery device, wherein the non-flammable gas-liquid two-phase refrigerant from the outlet of the liquid cooling plate (11) enters the gas-liquid mixing tee, the gaseous refrigerant is directly introduced into the internal space of the sealed shell (1) through the refrigerant exhaust pipe (13), and the liquid refrigerant flows into the liquid storage tank (15) and then re-enters the liquid cooling plate (11) through the pressurized reflux system (16) to complete the recycling.

3. The battery thermal management and thermal runaway coordinated protection system based on non-flammable refrigerant according to claim 1, characterized in that, The non-flammable refrigerant is non-flammable in the gaseous state and has refrigerant properties in the liquid state, achieving heat exchange through the aforementioned circulation loop; at the same time, it dilutes the oxygen concentration in the gaseous state, blocking the combustion chain reaction; the non-flammable refrigerant has a boiling point below room temperature and above 0°C under normal pressure; in order to ensure that the refrigeration cycle can form a stable gas-liquid two-phase flow state, the non-flammable refrigerant needs to condense into a liquid after the compression and condensation process to achieve effective circulation.

4. A battery thermal management and thermal runaway coordinated protection system based on a non-flammable refrigerant according to claim 1 or 2, characterized in that, The protection system also includes: a collaborative protection module; The collaborative protection module includes: a pressure sensor (P), a temperature sensor (T), a combustible gas monitoring device (18), a normal operation module, and a safety pressure relief start / stop module; wherein, the pressure sensor (P) is located inside the sealed housing (1) at one end and is used to detect the gas pressure inside the sealed housing (1); the temperature sensor (T) is located in each battery cluster and is used to monitor the working temperature of the battery cell or module in real time; a temperature sensor (T) is also provided inside the sealed housing (1) to monitor the ambient temperature inside the sealed housing (1); The combustible gas monitoring device (18) is installed inside the sealed shell (1) and can be used to monitor the concentration of combustible gases such as carbon monoxide and hydrogen in the internal space of the sealed shell (1) to determine whether the battery has thermal runaway; the oxygen concentration monitor (17) is used to monitor the oxygen concentration inside the sealed shell in real time and can also determine whether non-flammable refrigerant gas has leaked in the space of the sealed shell (1).

5. A battery thermal management and thermal runaway coordinated protection system based on a non-flammable refrigerant according to claim 4, characterized in that, When the work begins, non-flammable refrigerant is injected through the refrigerant charging port set on the sealed shell. After the oxygen concentration monitoring device (17) monitors that the oxygen concentration is lower than the preset limit oxygen concentration, it determines that the non-flammable refrigerant has reached the specified concentration and the seal meets the standard, and then starts the compressor (2) and the compressor flow regulating valve (21).

6. The battery thermal management and thermal runaway coordinated protection system based on a non-flammable refrigerant according to claim 4, characterized in that, The sealed housing (1) has a safety pressure relief device (19). When the pressure sensor (P) detects that the internal pressure of the sealed housing is higher than the preset safety pressure relief trigger pressure value, the safety pressure relief device (19) is opened to prevent the internal pressure of the system from being too high during thermal runaway, which could lead to structural damage or secondary explosion.

7. The battery thermal management and thermal runaway coordinated protection system based on a non-flammable refrigerant according to claim 4, characterized in that, When the normal operation module is working, the compressor flow regulating valve (21), compressor (2) and expansion valve (6) are open; the gas-liquid separator exhaust valve (43) is open and the safety pressure relief device (19) is closed; at the same time, the environment is monitored by the sensors in the collaborative protection module; The compressor (2) and the gas separation device (4) are always running to ensure that the battery is in a suitable operating temperature and a high concentration of inert atmosphere. At the same time, after the oxygen concentration monitor detects that the oxygen concentration is higher than the preset limit oxygen concentration, the operating power of the compressor is increased. Meanwhile, based on the liquid level feedback of the gas-liquid separator, the opening of its exhaust valve is increased to accelerate the separation of non-preset working gas.

8. The battery thermal management and thermal runaway coordinated protection system based on a non-flammable refrigerant according to claim 4, characterized in that, When the safety pressure relief start-stop module is working, it collects data from the temperature sensor (T), combustible gas monitoring device (18) and pressure sensor (P) in real time for monitoring; when the pressure sensor (P) is greater than the rapid pressure relief threshold, it sends a control signal and turns on the safety pressure relief device (19); when the pressure sensor (P) returns to below the rapid pressure relief threshold, it sends a pressure relief shutdown message to the safety pressure relief start-stop module; and sends a control signal and turns off the safety pressure relief device (19).

9. A battery thermal management and thermal runaway coordinated protection system based on a non-flammable refrigerant according to claim 7, characterized in that, The normal operating module is connected to the gas-liquid separator exhaust valve (43). During the continuous refrigeration cycle of the compressor (2), the gas separation device (4) performs gas-liquid separation on the working fluid in the refrigeration cycle loop, continuously separating out air, thermal runaway gas or other non-preset working fluid gas, and discharges the non-preset working fluid gas from the system through the gas-liquid separator exhaust valve (43) to maintain the concentration of non-flammable refrigerant gas in the sealed shell (1) within the preset safety range.

10. A battery thermal management and thermal runaway coordinated protection system based on a non-flammable refrigerant according to claim 8, characterized in that, When the combustible gas monitoring device (18) detects that the concentration of combustible gas in the sealed shell reaches the preset emergency concentration threshold, the temperature sensor (T) detects that the temperature reaches the preset emergency temperature threshold, or the pressure sensor (P) detects that the pressure reaches the preset emergency pressure threshold, it is determined that there is a risk of thermal runaway, and the safety pressure relief start-stop module starts to work: immediately disconnect the battery cluster and the system from the external circuit, and stop the charging and discharging operation; adjust the opening of the compressor flow regulating valve (21) to the maximum, and at the same time increase the opening of the gas-liquid separator exhaust valve (43) based on the liquid level feedback of the gas-liquid separator to enhance the flow and entrainment capacity of the refrigerant gas; maintain the continuous operation of the refrigeration cycle system, use the gaseous non-flammable refrigerant as the carrier gas, carry the combustible gas generated by thermal runaway to the gas separation device (4), and realize the active separation and safe discharge of combustible gas through gas-liquid separation; When the gas-liquid separator's exhaust capacity is insufficient, causing the internal pressure of the sealed housing (1) to exceed the preset safety pressure relief trigger pressure value, the safety pressure relief device (19) is activated to perform secondary pressure relief and explosion protection.

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