Direct cooling system

Abstract

The present application relates to the technical field of energy storage, and particularly relates to a direct cooling system. The direct cooling system comprises a compressor, a heat exchanger, at least two throttles and at least two liquid cooling plates, the compressor, the heat exchanger, the at least two throttles and the at least two liquid cooling plates are configured to be connected in sequence to form a refrigeration cycle loop for refrigerant to flow in the refrigeration cycle loop. The heat exchanger is configured as a condenser in the refrigeration cycle loop, the at least two throttles are connected in parallel, the at least two liquid cooling plates are connected in parallel, the at least two throttles are connected with the at least two liquid cooling plates one by one, the at least two liquid cooling plates are configured to exchange heat with the battery cell corresponding to the battery pack, and the throttle is configured to adjust the opening degree to adjust the flow of refrigerant in the corresponding liquid cooling plate. The flow of refrigerant in each liquid cooling plate can be controlled by respectively arranging a throttle upstream of each liquid cooling plate, thereby achieving uniformity of flow distribution.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and in particular to a direct cooling system. Background Technology

[0002] With the rapid development of the energy storage industry, cell lifespan, temperature difference, and system cost are gradually becoming the focus of future industry competition. Developing a high-efficiency, energy-saving, and low-cost thermal management system is crucial to enhancing the core competitiveness of enterprise products. Currently, commonly used thermal management systems for energy storage are liquid cooling systems and direct cooling systems. Liquid cooling systems include a refrigerant circulation system and a water circulation system. Through the refrigerant circulation system, the refrigerant evaporates and exchanges heat with the coolant in the water circuit in a plate heat exchanger. The coolant is then pumped into the liquid cooling plate of the battery pack to exchange heat with the cells, thereby achieving temperature control of the cells. Because liquid cooling systems have problems such as large temperature differences between the inlet and outlet of the coolant at the liquid cooling plate, resulting in large temperature differences inside the cells, direct cooling systems, which allow the refrigerant to directly enter the liquid cooling plate of the battery pack for heat exchange, eliminating the need for a coolant cooling circuit, are gradually gaining a market advantage.

[0003] In the related technologies of direct cooling systems, it is difficult to design the uniformity of refrigerant flow distribution in the liquid cooling plate of the battery pack. The uniformity of flow distribution will directly affect the temperature difference between different cells. Summary of the Invention

[0004] This invention provides a direct cooling system for uniformly distributing the flow of refrigerant in the liquid cooling plate of a battery pack.

[0005] The present invention provides a direct cooling system, including a compressor, a heat exchanger, at least two throttling valves and at least two liquid cooling plates, wherein the compressor, the heat exchanger, the at least two throttling valves and the at least two liquid cooling plates are configured to be connected in sequence to form a refrigeration cycle loop for refrigerant to flow in the refrigeration cycle loop;

[0006] The heat exchanger is configured as a condenser in the refrigeration cycle loop, the at least two throttle valves are connected in parallel, the at least two liquid cooling plates are connected in parallel, the at least two throttle valves are connected to the at least two liquid cooling plates in a one-to-one correspondence, the at least two liquid cooling plates are configured to exchange heat with the cells corresponding to the battery pack, and the throttle valves are configured to adjust their opening to regulate the flow rate of the refrigerant in the corresponding liquid cooling plate.

[0007] In some embodiments, the throttle valve is configured to adjust its opening degree based on the temperature of the corresponding cell collected by the battery pack's BMS.

[0008] In some embodiments, at least two first temperature sensors are also included, each disposed in a corresponding manner at the end of the liquid cooling plate away from the throttle valve, and are used to monitor the temperature of the refrigerant. The throttle valve is configured to adjust its opening degree according to the temperature of the refrigerant monitored by the corresponding first temperature sensor.

[0009] In some embodiments, a pressure regulating valve is also included, which is connected between the at least two liquid cooling plates and the compressor.

[0010] In some embodiments, a second temperature sensor is also included, which is disposed on the compressor and used to monitor the temperature of the refrigerant entering the compressor, and the pressure regulating valve is configured to adjust its opening based on the temperature of the refrigerant monitored by the second temperature sensor.

[0011] In some embodiments, a regenerator is also included, the regenerator comprising a first branch and a second branch, the first branch being connected between the heat exchanger and the at least two throttling valves, and the second branch being connected between the at least two liquid cooling plates and the compressor, wherein the refrigerant in the first branch and the refrigerant in the second branch exchange heat.

[0012] In some embodiments, a liquid storage tank is also included, which is connected between the heat exchanger and the at least two throttling valves.

[0013] In some embodiments, a four-way valve is also included, the four-way valve including a first port, a second port, a third port and a fourth port, wherein the first port and the third port are both connected to the compressor, the second port is connected to the heat exchanger, and the fourth port is connected to the at least two liquid cooling plates;

[0014] When the first port is connected to the second port and the third port is connected to the fourth port, the compressor, the heat exchanger, the at least two throttle valves, and the at least two liquid cooling plates are connected in sequence to form the refrigeration cycle loop;

[0015] When the first port is connected to the fourth port and the second port is connected to the third port, the compressor, the at least two liquid cooling plates, the at least two throttling valves and the heat exchanger are sequentially connected to form a heating cycle loop for refrigerant to flow in the heating cycle loop; wherein the heat exchanger is configured as an evaporator in the refrigeration cycle loop.

[0016] In some embodiments, a heater is also included, which is configured to be connected in the heating cycle loop and connected between the fourth port and the at least two liquid cooling plates, and the heater is configured to adjust the heating power based on the temperature of the refrigerant monitored by the first temperature sensor.

[0017] In some embodiments, the system further includes a pump, a first bypass valve, and a second bypass valve. The pump is connected between the heat exchanger and the at least two throttle valves. The first bypass valve is connected between the heat exchanger and the at least two throttle valves and selectively bypasses the pump. The second bypass valve is connected between the heat exchanger and the at least two liquid cooling plates and selectively bypasses the compressor and the four-way valve.

[0018] This application provides a direct cooling system, which has at least the following advantages compared with the prior art:

[0019] By installing a throttle valve upstream of each liquid cooling plate, the flow rate of refrigerant in each liquid cooling plate can be controlled, thereby achieving uniform flow distribution and avoiding temperature differences between different cells. Attached Figure Description

[0020] The invention will now be described in more detail with reference to embodiments and the accompanying drawings.

[0021] Figure 1 This is a schematic diagram of the refrigeration cycle loop formed by the direct cooling system according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the heating cycle loop formed by the direct cooling system in an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the pump circulation loop formed by the direct cooling system in an embodiment of the present invention.

[0024] Figure label:

[0025] 100-Direct cooling system;

[0026] 1-Compressor; 2-Heat exchanger; 3-Throttle valve; 4-Liquid cooling plate; 5-Four-way valve; 6-Regenerator; 7-Pump; 8-First bypass valve; 9-Pressure regulating valve; 10-Second bypass valve; 11-Liquid storage tank; 12-Gas-liquid separator; 13-Heater; 14-Oil separator; 15-Oil return pipe. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] In this application, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0029] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0030] The technical solution of this application will be further described below with reference to specific embodiments and accompanying drawings.

[0031] This application provides a direct cooling system 100, including a compressor 1, a heat exchanger 2, at least two expansion valves 3, and at least two liquid cooling plates 4. The compressor 1, heat exchanger 2, at least two expansion valves 3, and at least two liquid cooling plates 4 are configured to be connected sequentially to form a refrigeration cycle loop for refrigerant to flow in the refrigeration cycle loop. The heat exchanger 2 is configured as a condenser in the refrigeration cycle loop. The at least two expansion valves 3 are connected in parallel, and the at least two liquid cooling plates 4 are connected in parallel. Each of the at least two expansion valves 3 and at least two liquid cooling plates 4 is connected in a one-to-one correspondence. The at least two liquid cooling plates 4 are configured to exchange heat with the cells corresponding to the battery pack, and the expansion valves 3 are configured to adjust their opening degree to regulate the refrigerant flow rate within the corresponding liquid cooling plate 4.

[0032] In this embodiment, the heat exchanger 2 is equivalent to a condenser in the refrigeration cycle loop. For example, when the temperature of the battery cell is above 35°C, the direct cooling system 100 forms a refrigeration cycle loop. The refrigerant circulates in the refrigeration cycle loop in the following order: compressor 1, heat exchanger 2, at least two expansion valves 3, and at least two liquid cooling plates 4. In this process, the refrigerant is pressurized by compressor 1 to form a high-temperature, high-pressure gaseous refrigerant. When this gaseous refrigerant flows to heat exchanger 2, it exchanges heat with the outside air, transforming into a medium-temperature, high-pressure liquid refrigerant. When this liquid refrigerant flows to expansion valve 3, the expansion valve 3 reduces its pressure, transforming it into a low-temperature, low-pressure liquid refrigerant. This low-temperature, low-pressure liquid refrigerant flows into liquid cooling plate 4, where it exchanges heat with the corresponding battery cell to cool it. After this heat exchange, the liquid refrigerant transforms back into a gaseous refrigerant. The gaseous refrigerant returns to compressor 1, where it is pressurized again to form a high-temperature, high-pressure gaseous refrigerant, thus completing the refrigeration cycle.

[0033] It should be noted that, since the number of battery cells in a battery pack is generally at least two, in order to correspond with the battery cells, the number of liquid cooling plates 4 in this embodiment is also set to at least two, and the number of liquid cooling plates 4 is the same as the number of battery cells. Each liquid cooling plate 4 is in contact with one battery cell, so that at least two liquid cooling plates 4 are in contact with at least two battery cells in a one-to-one correspondence, so that the refrigerant in each liquid cooling plate 4 exchanges heat with the corresponding battery cell in a very small way.

[0034] It is understandable that during the process of the refrigerant output from the heat exchanger 2 flowing to at least two liquid cooling plates 4, the refrigerant is distributed approximately evenly to each of the at least two liquid cooling plates 4, resulting in different flow rates of refrigerant in different liquid cooling plates 4. This leads to different heat exchange rates between the refrigerant and the corresponding battery cells in different liquid cooling plates 4, thus creating temperature differences between the different battery cells. To solve this problem, in this embodiment of the application, when the direct cooling system 100 forms a refrigeration cycle loop, at least two throttling valves 3 are installed downstream of the heat exchanger 2 and upstream of the at least two liquid cooling plates 4. The number of the at least two throttling valves 3 corresponds one-to-one with the number of the at least two liquid cooling plates 4, and the opening degree of each throttling valve 3 can control the flow rate of refrigerant entering the corresponding liquid cooling plate 4.

[0035] In one example, when the direct cooling system 100 forms a refrigeration cycle and the temperature of one or more battery cells is detected to be higher than that of other battery cells, the opening of the corresponding throttle valve 3 can be increased to increase the flow rate of refrigerant entering the corresponding liquid cooling plate 4, thereby increasing the heat exchange between the battery cell and the refrigerant and thus lowering the battery cell temperature. When the direct cooling system 100 forms a refrigeration cycle and the temperature of one or more battery cells is detected to be lower than that of other battery cells, the opening of the corresponding throttle valve 3 can be decreased to reduce the flow rate of refrigerant entering the corresponding liquid cooling plate 4, thereby reducing the heat exchange between the battery cell and the refrigerant and thus raising the battery cell temperature.

[0036] In another example, when the direct cooling system 100 forms a refrigeration cycle and the temperature of one or more battery cells is detected to be higher than the preset temperature, the opening of the corresponding throttle valve 3 can be increased to increase the flow rate of refrigerant entering the corresponding liquid cooling plate 4, thereby increasing the heat exchange between the battery cell and the refrigerant, and thus reducing the battery cell temperature to the preset temperature; when the direct cooling system 100 forms a refrigeration cycle and the temperature of one or more battery cells is detected to be lower than the preset temperature, the opening of the corresponding throttle valve 3 can be decreased to reduce the flow rate of refrigerant entering the corresponding liquid cooling plate 4, thereby reducing the heat exchange between the battery cell and the refrigerant, and thus increasing the battery cell temperature to the preset temperature.

[0037] In other examples, when the direct cooling system 100 forms a refrigeration cycle loop, the opening of the throttle valve 3 can also be adjusted by monitoring the temperature of the refrigerant at the end of the liquid cooling plate 4 away from the throttle valve 3.

[0038] Therefore, in this embodiment of the application, when the direct cooling system 100 forms a refrigeration cycle to cool the battery cell, a throttle valve 3 can be set upstream of each liquid cooling plate 4 to control the flow rate of refrigerant entering each liquid cooling plate 4, thereby achieving uniform flow distribution and avoiding temperature differences between different battery cells.

[0039] In some implementations, the throttle valve 3 is configured to adjust its opening degree based on the temperature of the corresponding cell collected by the battery pack's BMS.

[0040] Among them, the BMS (Battery Management System) can monitor parameters such as voltage, current and temperature of each cell in the battery pack in real time.

[0041] In one example, when the direct cooling system 100 forms a refrigeration cycle and the BMS detects that the temperature of one or more battery cells is higher than that of other battery cells, the opening of the corresponding throttle valve 3 can be increased to increase the flow rate of refrigerant entering the corresponding liquid cooling plate 4, thereby increasing the heat exchange between the battery cell and the refrigerant and thus lowering the battery cell temperature. When the direct cooling system 100 forms a refrigeration cycle and the BMS detects that the temperature of one or more battery cells is lower than that of other battery cells, the opening of the corresponding throttle valve 3 can be decreased to reduce the flow rate of refrigerant entering the corresponding liquid cooling plate 4, thereby reducing the heat exchange between the battery cell and the refrigerant and thus raising the battery cell temperature.

[0042] In another example, when the direct cooling system 100 forms a refrigeration cycle and the BMS detects that the temperature of one or more battery cells is higher than the preset temperature, the opening of the corresponding throttle valve 3 can be increased to increase the flow rate of refrigerant entering the corresponding liquid cooling plate 4, thereby increasing the heat exchange between the battery cell and the refrigerant, and thus reducing the battery cell temperature to the preset temperature; when the direct cooling system 100 forms a refrigeration cycle and the BMS detects that the temperature of one or more battery cells is lower than the preset temperature, the opening of the corresponding throttle valve 3 can be decreased to reduce the flow rate of refrigerant entering the corresponding liquid cooling plate 4, thereby reducing the heat exchange between the battery cell and the refrigerant, and thus increasing the battery cell temperature to the preset temperature.

[0043] In this embodiment, when the direct cooling system 100 forms a refrigeration cycle loop, the opening of the throttle valve 3 is adjusted according to the temperature of each battery cell monitored by the BMS. This allows for precise adjustment of the opening of the throttle valve 3, thereby precisely controlling the flow rate of refrigerant entering the liquid cooling plate 4.

[0044] In some embodiments, the direct cooling system 100 further includes at least two first temperature sensors (not shown in the figure), which are disposed one-to-one at the end of the liquid cooling plate 4 away from the throttle valve 3 and are used to monitor the temperature of the refrigerant. The throttle valve 3 is configured to adjust its opening degree according to the temperature of the refrigerant monitored by the corresponding first temperature sensor.

[0045] Understandably, when the direct cooling system 100 forms a refrigeration cycle, the end of the liquid cooling plate 4 furthest from the expansion valve 3 is the outlet position of the liquid cooling plate 4. The first temperature sensor is positioned at this end of the liquid cooling plate 4 furthest from the expansion valve 3, allowing it to monitor the temperature of the gaseous refrigerant that has been converted into gaseous form after heat exchange with the battery cell within the liquid cooling plate 4. The fact that at least two first temperature sensors are positioned one-to-one at the ends of the liquid cooling plate 4 furthest from the expansion valve 3 indicates that each first temperature sensor only monitors the temperature of the refrigerant at its corresponding end of the liquid cooling plate 4 furthest from the expansion valve 3.

[0046] In one example, when the direct cooling system 100 forms a refrigeration cycle and one or more first temperature sensors detect a refrigerant temperature that is higher than that detected by other first temperature sensors, the opening of the corresponding throttle valve 3 can be increased to increase the flow rate of refrigerant entering the corresponding liquid cooling plate 4, thereby increasing the heat exchange between the battery cell and the refrigerant and thus lowering the battery cell temperature. When the direct cooling system 100 forms a refrigeration cycle and one or more first temperature sensors detect a refrigerant temperature that is lower than that detected by other first temperature sensors, the opening of the corresponding throttle valve 3 can be decreased to reduce the flow rate of refrigerant entering the corresponding liquid cooling plate 4, thereby reducing the heat exchange between the battery cell and the refrigerant and thus raising the battery cell temperature.

[0047] In another example, when the direct cooling system 100 forms a refrigeration cycle and one or more first temperature sensors detect that the refrigerant temperature is higher than the preset temperature, the opening of the corresponding throttle valve 3 can be increased to increase the flow rate of the refrigerant entering the corresponding liquid cooling plate 4, thereby increasing the heat exchange between the battery cell and the refrigerant, and thus reducing the battery cell temperature to the preset temperature; when the direct cooling system 100 forms a refrigeration cycle and one or more first temperature sensors detect that the refrigerant temperature is lower than the preset temperature, the opening of the corresponding throttle valve 3 can be decreased to reduce the flow rate of the refrigerant entering the corresponding liquid cooling plate 4, thereby reducing the heat exchange between the battery cell and the refrigerant, and thus increasing the battery cell temperature to the preset temperature.

[0048] In this embodiment, when the direct cooling system 100 forms a refrigeration cycle loop, the opening of the throttle valve 3 is adjusted according to the outlet position of the corresponding liquid cooling plate 4 monitored by the first temperature sensor. This allows for precise adjustment of the opening of the throttle valve 3, thereby precisely controlling the flow rate of refrigerant entering the liquid cooling plate 4.

[0049] In some embodiments, the direct cooling system 100 further includes a pressure regulating valve 9, which is connected between at least two liquid cooling plates 4 and the compressor 1.

[0050] In this embodiment, the refrigerant circulates in the refrigeration cycle in the following order: compressor 1, heat exchanger 2, at least two expansion valves 3, at least two liquid cooling plates 4, and pressure regulating valve 9. In this process, the refrigerant is pressurized by compressor 1 to form a high-temperature, high-pressure gaseous refrigerant. When this gaseous refrigerant flows to heat exchanger 2, it exchanges heat with the outside air, transforming into a medium-temperature, high-pressure liquid refrigerant. When this liquid refrigerant flows to throttling valve 3, the throttling action of valve 3 reduces its pressure, transforming it into a low-temperature, low-pressure liquid refrigerant. This low-temperature, low-pressure liquid refrigerant flows into liquid cooling plate 4, where it exchanges heat with the corresponding battery cell, cooling the cell. After this heat exchange, the liquid refrigerant transforms into a gaseous refrigerant. The gaseous refrigerant is further cooled and depressurized by pressure regulating valve 9. After further cooling and depressurization, the gaseous refrigerant returns to compressor 1, where it is pressurized again to form a high-temperature, high-pressure gaseous refrigerant, thus completing the refrigeration cycle.

[0051] It is understandable that during the heat exchange between the low-temperature, low-pressure liquid refrigerant and the battery cell in the liquid-cooled plate 4, the liquid refrigerant will evaporate into a gaseous state. However, if the liquid refrigerant evaporates too completely, the surface temperature of the liquid-cooled plate 4 will become too low, resulting in condensation on its surface. To solve this problem, in this embodiment, a pressure regulating valve 9 is provided between the liquid-cooled plate 4 and the compressor 1. When the refrigerant evaporates too completely in the liquid-cooled plate 4, the opening of the pressure regulating valve 9 is reduced to decrease the flow rate of the refrigerant in the liquid-cooled plate 4, thereby slowing down the evaporation rate of the refrigerant in the liquid-cooled plate 4 and increasing the evaporation pressure in the liquid-cooled plate 4. This, in turn, increases the evaporation temperature and the surface temperature of the liquid-cooled plate 4, reducing the risk of condensation on the surface of the liquid-cooled plate 4. In addition, reducing the opening of the pressure regulating valve 9 to decrease the flow rate of the refrigerant in the liquid-cooled plate 4 can also prevent the refrigerant in the liquid-cooled plate 4 from overheating.

[0052] In some embodiments, the direct cooling system 100 further includes a second temperature sensor (not shown), which is disposed on the compressor 1 and used to monitor the temperature of the refrigerant entering the compressor 1, and the pressure regulating valve 9 is configured to adjust its opening based on the temperature of the refrigerant monitored by the second temperature sensor.

[0053] After monitoring the temperature of the refrigerant entering compressor 1, the second temperature sensor compares the refrigerant temperature with the corresponding saturation temperature to obtain the suction superheat. Therefore, the pressure regulating valve 9 is configured to adjust its opening based on the refrigerant temperature monitored by the second temperature sensor, meaning it adjusts its opening based on the suction superheat corresponding to the refrigerant temperature monitored by the second temperature sensor.

[0054] Saturation temperature refers to the temperature at which the liquid and gas are in dynamic equilibrium (i.e., saturated state). Suction superheat is the difference between the saturation temperature and the refrigerant temperature monitored by the second temperature sensor.

[0055] In this embodiment, when the suction superheat calculated from the temperature of the refrigerant entering the compressor 1 monitored by the second temperature sensor is lower than zero, it indicates that the refrigerant is evaporating too fully in the liquid cooling plate 4, which may cause liquid refrigerant to be sucked into the compressor 1 and cause liquid slugging, etc. Therefore, the flow rate of the refrigerant can be reduced by decreasing the opening of the pressure regulating valve 9 to increase the evaporation pressure of the refrigerant in the liquid cooling plate 4. At this time, the pressure of the refrigerant is approximately equal to the evaporation pressure in the liquid cooling plate 4. Therefore, the increase in the pressure of the refrigerant can lead to an increase in the saturation temperature at the corresponding pressure, thereby increasing the suction superheat and avoiding liquid slugging, etc.

[0056] In some embodiments, the direct cooling system 100 further includes a gas-liquid separator 12, which can be connected between the pressure regulating valve 9 and the compressor 1, i.e., the gas-liquid separator 12 can be located at the input end of the compressor 1. The gas-liquid separator 12 can ensure that the refrigerant entering the compressor 1 is a gaseous refrigerant.

[0057] In some embodiments, the direct cooling system 100 further includes a regenerator 6, which includes a first branch and a second branch. The first branch is connected between the heat exchanger 2 and at least two throttling valves 3, and the second branch is connected between at least two liquid cooling plates 4 and the compressor 1. The refrigerant in the first branch and the refrigerant in the second branch exchange heat.

[0058] In some more specific embodiments, the second branch of the regenerator 6 is connected between the pressure regulating valve 9 and the compressor 1.

[0059] In this embodiment, the refrigerant circulates in the refrigeration cycle in the following order: compressor 1, heat exchanger 2, first branch of regenerator 6, at least two expansion valves 3, at least two liquid cooling plates 4, pressure regulating valve 9, and second branch of regenerator 6. Specifically, when the refrigerant passes through compressor 1, it is pressurized by compressor 1 to form a high-temperature, high-pressure gaseous refrigerant. When the high-temperature, high-pressure gaseous refrigerant flows to heat exchanger 2, it exchanges heat with the outside air, converting it into a medium-temperature, high-pressure liquid refrigerant. After passing through the first branch of regenerator 6, the medium-temperature, high-pressure liquid refrigerant flows to expansion valve 3. The throttling action of expansion valve 3 reduces the pressure of the medium-temperature, high-pressure liquid refrigerant, causing it to convert into a low-temperature, high-pressure liquid refrigerant. Low-temperature, low-pressure liquid refrigerant flows into the liquid cooling plate 4 and exchanges heat with the corresponding battery cell to cool it down. After heat exchange with the battery cell, the low-temperature, low-pressure liquid refrigerant is converted into gaseous refrigerant. The gaseous refrigerant is further cooled and depressurized by the pressure regulating valve 9. After further cooling and depressurization, the gaseous refrigerant returns to the compressor 1 after passing through the second branch of the regenerator 6. It is then pressurized by the compressor 1 to form a high-temperature, high-pressure gaseous refrigerant again, thus realizing the refrigeration cycle loop.

[0060] It should be noted that the liquid refrigerant passing through the first branch of the regenerator 6 releases heat, causing it to become subcooled when it flows to the expansion valve 3. At the same time, the gaseous refrigerant passing through the second branch of the regenerator 6 absorbs heat, causing it to become overheated when it flows back to the compressor 1.

[0061] In some embodiments, the direct cooling system 100 further includes a liquid storage tank 11, which is connected between the heat exchanger 2 and at least two throttling valves 3.

[0062] In some more specific embodiments, the liquid storage tank 11 is connected between the first branch of the regenerator 6 and at least two throttling valves 3.

[0063] In this embodiment, the refrigerant circulates in the refrigeration cycle in the following order: compressor 1, heat exchanger 2, first branch of regenerator 6, liquid receiver 11, at least two expansion valves 3, at least two liquid cooling plates 4, pressure regulating valve 9, and second branch of regenerator 6. Specifically, when the refrigerant passes through compressor 1, it is pressurized by compressor 1 to form a high-temperature, high-pressure gaseous refrigerant. When the high-temperature, high-pressure gaseous refrigerant flows to heat exchanger 2, it exchanges heat with the outside air, converting it into a medium-temperature, high-pressure liquid refrigerant. The medium-temperature, high-pressure liquid refrigerant then flows through the first branch of regenerator 6 to liquid receiver 11 for storage. When the medium-temperature, high-pressure liquid refrigerant in liquid receiver 11 flows to expansion valve 3, the throttling action of expansion valve 3 reduces the pressure of the medium-temperature, high-pressure liquid refrigerant, allowing... The medium-temperature, high-pressure liquid refrigerant is converted into a low-temperature, low-pressure liquid refrigerant. The low-temperature, low-pressure liquid refrigerant flows into the liquid cooling plate 4 and exchanges heat with the corresponding battery cell to cool the battery cell. After heat exchange with the battery cell, the low-temperature, low-pressure liquid refrigerant is converted into a gaseous refrigerant. The gaseous refrigerant is further cooled and depressurized by the pressure regulating valve 9. After further cooling and depressurization, the gaseous refrigerant returns to the compressor 1 after passing through the second branch of the regenerator 6. The compressor 1 pressurizes the gaseous refrigerant to form a high-temperature, high-pressure gaseous refrigerant again, thus realizing the refrigeration cycle loop.

[0064] The liquid receiver 11 can be used to ensure that the refrigerant flowing to the throttle valve 3 is approximately liquid refrigerant.

[0065] In some embodiments, the direct cooling system 100 further includes an oil separator, which may be located at the output end of the compressor 1. The oil separator can separate the lubricating oil from the compressor 1, preventing the lubricating oil from flowing into the circulation loop. Simultaneously, the direct cooling system 100 also includes an oil return pipe 15, one end of which is connected to the oil separator, and the other end is connected to the compressor 1. The lubricating oil separated by the oil separator from the compressor 1 can return to the compressor 1 through the oil return pipe 15.

[0066] In some embodiments, the direct cooling system 100 further includes a four-way valve 5, which includes a first port, a second port, a third port and a fourth port, wherein the first port and the third port are both connected to the compressor 1, the second port is connected to the heat exchanger 2, and the fourth port is connected to at least two liquid cooling plates 4.

[0067] When the first port is connected to the second port and the third port is connected to the fourth port, the compressor 1, heat exchanger 2, at least two throttle valves 3 and at least two liquid cooling plates 4 are connected in sequence to form a refrigeration cycle loop.

[0068] When the first port is connected to the fourth port and the second port is connected to the third port, the compressor 1, at least two liquid cooling plates 4, at least two throttle valves 3 and heat exchanger 2 are connected in sequence to form a heating cycle loop for refrigerant to flow in the heating cycle loop; wherein the heat exchanger 2 is configured as an evaporator in the refrigeration cycle loop.

[0069] In this embodiment, the direct cooling system 100 can switch between the refrigeration cycle loop and the heating cycle loop by switching the internal port of the four-way valve 5.

[0070] In one example, when the first port of the four-way valve 5 is connected to the second port and the third port is connected to the fourth port, the refrigerant circulates in the refrigeration cycle in the following order: compressor 1, oil separator, first port, second port, heat exchanger 2 (condenser), first branch of regenerator 6, liquid receiver 11, at least two expansion valves 3, at least two liquid cooling plates 4, pressure regulating valve 9, second branch of regenerator 6, fourth port, third port, and gas-liquid separator 12, and then returns to compressor 1.

[0071] It is understandable that the refrigerant in the refrigeration cycle is mainly used to cool the battery cells.

[0072] When the external temperature is too low, such as below -20°C, the electrolyte inside the battery cells becomes viscous and may even partially solidify, reducing ion conductivity and significantly slowing down the chemical reaction rate within the cells. Simultaneously, the activity of the positive and negative electrodes also decreases at low temperatures, further affecting the battery's charge and discharge performance. Therefore, when the external temperature is too low, the direct cooling system 100 can switch from a cooling cycle to a heating cycle by switching the internal ports of the four-way valve 5.

[0073] In another example, when the first port of the four-way valve 5 is connected to the fourth port and the second port is connected to the third port, the refrigerant circulates in the heating cycle in the following order: compressor 1, oil separator, first port, fourth port, second branch of regenerator 6, pressure regulating valve 9, at least two liquid cooling plates 4, at least two throttle valves 3, liquid receiver 11, first branch of regenerator 6, heat exchanger 2 (evaporator), second port, third port, and gas-liquid separator 12, and then returns to compressor 1.

[0074] It should be noted that heat exchanger 2 is a condenser in the heating cycle and an evaporator in the refrigeration cycle.

[0075] In this example, the refrigerant is pressurized by compressor 1 to form a high-temperature, high-pressure gaseous refrigerant. After passing through the second branch of regenerator 6, the high-temperature, high-pressure gaseous refrigerant flows to pressure regulating valve 9, where it is depressurized to form a high-temperature, low-pressure gaseous refrigerant. The high-temperature, low-pressure gaseous refrigerant flows into liquid cooling plate 4, where it exchanges heat with the battery cell and is converted into a low-temperature, low-pressure liquid refrigerant. The low-temperature, low-pressure liquid refrigerant is further depressurized by throttle valve 3 and then transported to liquid storage tank 11 for storage. The liquid refrigerant in liquid storage tank 11 flows through the first branch of regenerator 6 to heat exchanger 2 (evaporator), where it absorbs heat and evaporates to form a gaseous refrigerant. After passing through gas-liquid separator 12, the gaseous refrigerant returns to compressor 1, where it is pressurized again to form a high-temperature, high-pressure gaseous refrigerant, thus realizing a heating cycle loop.

[0076] In some embodiments, the direct cooling system 100 further includes a heater 13 configured to be connected in the heating cycle loop and connected between the fourth port and at least two liquid cooling plates 4, the heater 13 being configured to adjust the heating power based on the temperature of the refrigerant monitored by the first temperature sensor.

[0077] To further increase the temperature of the refrigerant before it enters the liquid cooling plate 4, a heater 13 can be installed in the heating cycle loop. The refrigerant circulates in the heating cycle loop in the following order: compressor 1, oil separator, first port, fourth port, heater 13, second branch of regenerator 6, pressure regulating valve 9, at least two liquid cooling plates 4, at least two throttle valves 3, liquid receiver 11, first branch of regenerator 6, heat exchanger 2 (evaporator), second port, third port, and gas-liquid separator 12 before returning to compressor 1.

[0078] Heater 13 is used to assist in heating the refrigerant to ensure the heating requirements of the battery cell. When the refrigerant enters the heater 13, the heating components inside the heater 13 come into contact with the refrigerant and heat it through convection heat transfer. It can be understood that heater 13 is in a closed state in the refrigeration cycle and in an operating state in the heating cycle.

[0079] In one example, when the direct cooling system 100 forms a heating cycle and one or more first temperature sensors detect a high refrigerant temperature, the power of the heater 13 can be reduced to decrease the heat exchange between the battery cell and the refrigerant, preventing the battery cell temperature from becoming too high; when the direct cooling system 100 forms a heating cycle and one or more first temperature sensors detect a low refrigerant temperature, the power of the heater 13 can be increased to increase the heat exchange between the battery cell and the refrigerant, preventing the battery cell temperature from becoming too low.

[0080] In some embodiments, the direct cooling system 100 further includes a pump 7, a first bypass valve 8, and a second bypass valve 10. The pump 7 is connected between the heat exchanger 2 and at least two throttle valves 3. The first bypass valve 8 is connected between the heat exchanger 2 and at least two throttle valves 3 and selectively bypasses the pump 7. The second bypass valve 10 is connected between the heat exchanger 2 and at least two liquid cooling plates 4 and selectively bypasses the compressor 1 and the four-way valve 5.

[0081] When the first bypass valve 8 of the direct cooling system 100 is opened and the second bypass valve 10 is closed, the first bypass valve 8 bypasses the pump 7, and the direct cooling system 100 forms a refrigeration cycle or a heating cycle.

[0082] When the first bypass valve 8 of the refrigeration system is closed and the second bypass valve 10 is open, the second bypass valve 10 bypasses the compressor 1 and the four-way valve 5, and the direct cooling system 100 forms a pump 7 circulation loop.

[0083] In some more specific embodiments, the second bypass valve 10 is connected between the heat exchanger 2 and the heater 13.

[0084] For example, when the ambient temperature is below 5°C and the cell temperature is between 25°C and 35°C, the first bypass valve 8 closes and the second bypass valve 10 opens, causing the direct cooling system 100 to form a pump 7 circulation loop. The refrigerant circulates in the pump 7 circulation loop in the following order: pump 7, at least two throttle valves 3, at least two liquid cooling plates 4, pressure regulating valve 9, the second branch of the regenerator 6, heater 13, the second bypass valve 10, heat exchanger 2, the first branch of the regenerator 6, liquid storage tank 11, and returns to pump 7.

[0085] It should be noted that when the direct cooling system 100 forms a circulation loop with pump 7, the heat exchanger 2 is equivalent to a condenser.

[0086] Liquid refrigerant is pumped to throttle valve 3 via pump 7. After being depressurized by throttle valve 3, it enters liquid cooling plate 4. In liquid cooling plate 4, liquid refrigerant exchanges heat with the battery cell, causing the battery cell temperature to drop. The liquid refrigerant evaporates to form gaseous refrigerant, which is then depressurized by pressure regulating valve 9 and enters heat exchanger 2 (condenser) via heater 13 and second bypass valve 10. In heat exchanger 2, gaseous refrigerant exchanges heat with the external environment, causing the gaseous refrigerant to cool into liquid refrigerant. The liquid refrigerant flows to liquid storage tank 11 for storage. The liquid refrigerant in liquid storage tank 11 then flows back to pump 7, thus realizing the circulation loop of pump 7.

[0087] It should be noted that heater 13 can be in a closed state or an operating state in the circulation loop of pump 7, and no limitation is made here.

[0088] In this embodiment, by setting up pump 7, first bypass valve 8 and second bypass valve 10, the direct cooling system 100 can switch between refrigeration cycle loop, heating cycle loop and pump 7 cycle loop. When switching to pump 7 cycle loop in a low ambient temperature environment, the system can make full use of the low temperature external environment, so that the refrigerant can exchange heat with the external environment and then exchange heat with the battery cell to reduce the temperature of the battery cell, thereby achieving energy saving under low temperature conditions.

[0089] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A direct cooling system, characterized in that, The device includes a compressor, a heat exchanger, at least two expansion valves, and at least two liquid cooling plates, wherein the compressor, the heat exchanger, the at least two expansion valves, and the at least two liquid cooling plates are configured to be connected in sequence to form a refrigeration cycle loop for refrigerant to flow in the refrigeration cycle loop; The heat exchanger is configured as a condenser in the refrigeration cycle loop, the at least two throttle valves are connected in parallel, the at least two liquid cooling plates are connected in parallel, the at least two throttle valves are connected to the at least two liquid cooling plates in a one-to-one correspondence, the at least two liquid cooling plates are configured to exchange heat with the cells corresponding to the battery pack, and the throttle valves are configured to adjust their opening to regulate the flow rate of the refrigerant in the corresponding liquid cooling plate.

2. The direct cooling system according to claim 1, characterized in that, The throttle valve is configured to adjust its opening degree based on the temperature of the corresponding cell collected by the battery pack's BMS.

3. The direct cooling system according to claim 1, characterized in that, It also includes at least two first temperature sensors, which are respectively disposed at the end of the liquid cooling plate away from the throttle valve and are used to monitor the temperature of the refrigerant. The throttle valve is configured to adjust its opening degree according to the temperature of the refrigerant monitored by the corresponding first temperature sensor.

4. The direct cooling system according to claim 3, characterized in that, It also includes a pressure regulating valve connected between the at least two liquid cooling plates and the compressor.

5. The direct cooling system according to claim 4, characterized in that, It also includes a second temperature sensor, which is disposed in the compressor and used to monitor the temperature of the refrigerant entering the compressor, and the pressure regulating valve is configured to adjust its opening degree according to the temperature of the refrigerant monitored by the second temperature sensor.

6. The direct cooling system according to claim 3, characterized in that, It also includes a regenerator, which includes a first branch and a second branch. The first branch is connected between the heat exchanger and the at least two throttling valves, and the second branch is connected between the at least two liquid cooling plates and the compressor. The refrigerant in the first branch and the refrigerant in the second branch exchange heat.

7. The direct cooling system according to claim 3, characterized in that, It also includes a liquid storage tank, which is connected between the heat exchanger and the at least two throttling valves.

8. The direct cooling system according to any one of claims 3-7, characterized in that, It also includes a four-way valve, which has a first port, a second port, a third port and a fourth port, wherein the first port and the third port are both connected to the compressor, the second port is connected to the heat exchanger and the fourth port is connected to the at least two liquid cooling plates; When the first port is connected to the second port and the third port is connected to the fourth port, the compressor, the heat exchanger, the at least two throttle valves, and the at least two liquid cooling plates are connected in sequence to form the refrigeration cycle loop; When the first port is connected to the fourth port and the second port is connected to the third port, the compressor, the at least two liquid cooling plates, the at least two throttling valves and the heat exchanger are sequentially connected to form a heating cycle loop for the refrigerant to flow in the heating cycle loop; wherein the heat exchanger is configured as an evaporator in the refrigeration cycle loop.

9. The direct cooling system according to claim 8, characterized in that, It also includes a heater configured to be connected in the heating cycle loop and connected between the fourth port and the at least two liquid cooling plates, the heater being configured to adjust the heating power based on the temperature of the refrigerant monitored by the first temperature sensor.

10. The direct cooling system according to claim 8, characterized in that, It also includes a pump, a first bypass valve, and a second bypass valve. The pump is connected between the heat exchanger and the at least two throttle valves. The first bypass valve is connected between the heat exchanger and the at least two throttle valves and selectively bypasses the pump. The second bypass valve is connected between the heat exchanger and the at least two liquid cooling plates and selectively bypasses the compressor and the four-way valve.

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