Heat exchange system, immersion energy storage system and temperature control method thereof

Abstract

The present application belongs to the technical field of heat exchange and immersion energy storage system, and provides a heat exchange system, an immersion energy storage system and a temperature control method for achieving the purpose of ensuring temperature control effect and reducing power consumption, which comprises an air conditioning system and a natural cooling system, the natural cooling system comprises a natural cooling coil, a three-way valve and a controller for switching the passage of the three-way valve, the evaporator of the air conditioning system is centrally embedded in a heat exchange container, and the heat exchange pipe of the evaporator is close to the surface of the heat exchange container; the heat exchange container is respectively provided with an inlet and an outlet at both ends for the inflow and outflow of heat exchange medium; the first port, the second port and the third port of the three-way valve are respectively used for inputting heat exchange medium, connecting the inlet and connecting the inlet end of the natural cooling coil; the outlet end of the natural cooling coil is connected in parallel to the passage of the three-way valve and the inlet. The whole battery pack is immersed in insulating liquid, the insulating liquid is used as heat exchange medium, and the heat exchange system of the present application is used for heat exchange.

Description

Technical Field

[0001] This invention belongs to the technical field of heat exchange technology and immersion energy storage system. Background Technology

[0002] Existing large-scale energy storage systems primarily utilize air cooling and cold-plate liquid cooling to control the temperature of energy storage units (such as battery cells). These two cooling methods are relatively inefficient and prone to causing temperature inconsistencies within the energy storage units during operation, leading to inconsistent operating characteristics. Immersion energy storage, by submerging the entire battery pack in an insulating fluid, effectively ensures temperature uniformity across the energy storage units. Furthermore, this system allows for enhanced insulation, improving overall system safety and preventing thermal runaway even in the event of an internal short circuit, thus avoiding the escalation of an accident.

[0003] Currently, reference Figure 1 As shown, the external cold source exchanges heat with the immersion liquid via a heat exchanger, or not. When the temperature of the energy storage unit exceeds the range, the cooling unit must be activated to achieve heat exchange between the cold source and the immersion liquid, releasing the heat from the energy storage unit through the immersion liquid, thereby achieving a cooling effect. However, relying on the cooling unit to drive the heat exchange year-round consumes a large amount of electricity, which is very uneconomical. Summary of the Invention

[0004] The purpose of this invention is to solve the problems existing in the prior art and provide a heat exchange system and method that can ensure temperature control while reducing power consumption. This invention also provides an immersion energy storage system that can fully utilize ambient cooling to cool the battery energy storage system and reduce power consumption.

[0005] This invention is achieved through the following technical solution: a heat exchange system comprising an air conditioning system and a natural cooling system. The natural cooling system includes a natural cooling coil, a three-way valve, and a controller for switching the passage of the three-way valve. A heat exchange container is embedded in the center of the evaporator of the air conditioning system, and the heat exchange tubes of the evaporator are in close contact with the surface of the heat exchange container. The heat exchange container has an inlet and an outlet at both ends for the inflow and outflow of the heat exchange medium, respectively. The first port, second port, and third port of the three-way valve are respectively used for inputting the heat exchange medium, connecting to the inlet, and connecting to the inlet end of the natural cooling coil. The outlet end of the natural cooling coil is connected in parallel to the passage between the three-way valve and the inlet, thereby allowing the heat exchange medium to flow into the heat exchange container after being pre-cooled by the natural cooling coil.

[0006] Furthermore, the air conditioning system is a variable frequency air conditioning system.

[0007] Furthermore, the air conditioning system also includes a four-way reversing valve, through which the compressor of the air conditioning system controls the flow of refrigerant to the condenser or evaporator, thereby realizing the switching between cooling mode and heating mode.

[0008] The present invention also provides an immersion energy storage system, including a battery pack immersed in an insulating liquid circulation pool, the battery pack being composed of several modules, each module being composed of several battery cells, and a heat exchange system provided by the present invention, wherein the first port of a three-way valve in the heat exchange system is connected to the outlet of the insulating circulation pool, and the outlet of the heat exchange container of the heat exchange system is connected to the return port of the insulating circulation pool.

[0009] The present invention also provides a temperature control method for an immersion energy storage system. The method uses the immersion energy storage system provided by the present invention, and uses the outdoor ambient temperature and the average temperature of the battery cells as inputs for fuzzy control. The method controls the input power of the compressor in the variable frequency air conditioning system according to fuzzy rules, thereby adjusting the cooling / heating.

[0010] Furthermore, the fuzzy rules match the corresponding temperature control mode based on the ambient temperature level and the average temperature level of the battery cell.

[0011] Furthermore, the outdoor ambient temperature rating and the average cell temperature rating are classified as follows: below 0℃ is extremely cold, 0~15℃ is cold, 16~30℃ is moderate, 31~40℃ is hot, and above 41℃ is extremely hot.

[0012] Furthermore, the temperature control modes include compressor heating mode, compressor cooling mode, natural cooling mode, and coupled cooling mode;

[0013] The compressor cooling mode: In the cooling mode of the air conditioning system, the third port of the three-way valve is closed, and the insulating liquid flows into the heat exchange container from the passage from the first port to the second port. The insulating liquid exchanges heat with the evaporator through the heat exchange container, so that the insulating liquid releases heat and then returns to the insulating liquid circulation pool.

[0014] The compressor heating mode: In the heating mode of the air conditioning system, the third port of the three-way valve is closed, and the insulating liquid flows into the heat exchange container from the passage from the first port to the second port. The insulating liquid exchanges heat with the evaporator through the heat exchange container, so that the insulating liquid absorbs heat and then returns to the insulating liquid circulation pool.

[0015] The natural cooling mode: the second port of the three-way valve is closed, and the insulating liquid flows into the natural cooling coil from the passage from the first port to the third port. The insulating liquid exchanges heat with the outdoor air through the natural cooling coil, so that the insulating liquid releases heat and then returns to the insulating liquid circulation pool through the heat exchange container.

[0016] The coupled cooling mode: In the cooling mode of the air conditioning system, the insulating liquid flows into the natural cooling coil from the first port to the third port. The insulating liquid is first pre-cooled by exchanging heat with the outdoor air through the natural cooling coil, and then exchanges heat with the evaporator through the heat exchange container, so that the insulating liquid releases heat and then returns to the insulating liquid circulation pool.

[0017] Furthermore, the matching methods between ambient temperature ratings and average cell temperature ratings include:

[0018] When the outdoor ambient temperature is hot and the average temperature of the battery cell is hot or extremely hot, the compressor cooling mode is used.

[0019] When the outdoor ambient temperature is moderate and the average temperature of the battery cell is hot, the coupling cooling mode is adopted.

[0020] When the outdoor ambient temperature is cold and the average temperature of the battery cell is hot, the natural cooling mode is adopted.

[0021] When the outdoor ambient temperature is moderate and the average temperature of the battery cell is hot, the coupling cooling mode is adopted.

[0022] When the outdoor ambient temperature is cold and the average temperature of the battery cell is extremely hot, a coupled cooling mode is adopted.

[0023] When the outdoor ambient temperature is cold and the average temperature of the battery cell is hot, the natural cooling mode is adopted.

[0024] When the outdoor ambient temperature is extremely cold and the average temperature of the battery cell is hot, the natural cooling mode is adopted.

[0025] When the outdoor ambient temperature is cold and the average temperature of the battery cell is cold, the compressor heating mode is adopted.

[0026] When the outdoor ambient temperature is extremely cold and the average temperature of the battery cell is cold, the compression mechanism is used for heating.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. This invention significantly reduces the self-consumption of the energy storage system's thermal management, i.e., the power consumption of the air conditioning system, by utilizing a natural cooling system to exchange heat with outdoor air.

[0029] 2. This invention matches the corresponding temperature control mode according to the ambient temperature level and the average temperature level of the battery cell, so as to adapt to changes in ambient temperature and battery cell temperature, thereby reducing power consumption and achieving good temperature control effect.

[0030] 3. This invention can not only cool down the battery cell, but also meet certain needs for heating. Attached Figure Description

[0031] Figure 1This is a schematic diagram of the heat exchange principle in existing technology;

[0032] Figure 2 This is a schematic diagram of the summer operation mode of the heat exchange system in this specific embodiment;

[0033] Figure 3 This is a schematic diagram of the transitional season operation mode of the heat exchange system in this specific embodiment.

[0034] Figure 4 This is a schematic diagram of the winter operation mode of the heat exchange system in this specific embodiment. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings:

[0036] Both the battery pack's own temperature and the ambient temperature affect the system's heat exchange efficiency and temperature transfer. For example, the battery pack's temperature is related to the inlet coolant temperature; the greater the temperature difference, the greater the heat exchange efficiency. The same principle applies to external cold sources. Therefore, the selection of the system's inlet temperature needs to consider the optimal temperatures of both systems. Based on these constraints, we first need to determine the optimal temperature for the battery pack: 25℃ is the optimal operating temperature for the battery.

[0037] refer to Figure 2 As shown, a heat exchange system includes an air conditioning system and a natural cooling system. The natural cooling system includes a natural cooling coil 1, a three-way valve 2, and a controller for switching the passage of the three-way valve. The evaporator 4 of the air conditioning system has a heat exchange container 3 embedded in its center, and the heat exchange tubes of the evaporator 4 are in close contact with the surface of the heat exchange container 3. The heat exchange container 3 has an inlet 301 and an outlet 302 at both ends for the flow of heat exchange medium. The first port, second port, and third port of the three-way valve 2 are respectively used to input the heat exchange medium, connect to the inlet 301, and connect to the inlet end of the natural cooling coil 1. The outlet end of the natural cooling coil 1 is connected in parallel to the passage between the three-way valve 2 and the inlet 301, so that the heat exchange medium can flow into the heat exchange container 3 after being pre-cooled by the natural cooling coil 1.

[0038] In this specific embodiment, the air conditioning system is a variable frequency air conditioning system.

[0039] In this specific embodiment, the air conditioning system further includes a four-way reversing valve. The compressor 5 of the air conditioning system controls the flow of refrigerant to the condenser 6 or the evaporator 4 through the four-way reversing valve, thereby realizing the switching between cooling mode and heating mode. The principle of switching between air conditioning cooling mode and heating mode is prior art and will not be described in detail here.

[0040] An immersion energy storage system includes a battery pack immersed in an insulating liquid circulation pool. The battery pack is composed of several modules, and each module is composed of several battery cells. The system also includes a heat exchange system. The first port of a three-way valve 2 in the heat exchange system is connected to the outlet of the insulating circulation pool, and the outlet 302 of the heat exchange container 3 of the heat exchange system is connected to the return port of the insulating circulation pool.

[0041] The entire battery pack is immersed in insulating liquid, which is used as a heat exchange medium. The heat exchange system of this invention is used to exchange heat with the insulating liquid.

[0042] A temperature control method for an immersion energy storage system, which employs an immersion energy storage system and controls the temperature based on the outdoor ambient temperature and the average temperature of the battery cells (each battery cell is equipped with a corresponding temperature sensor to collect the corresponding temperature, and then the average value is taken).

[0043] In this specific embodiment, the fuzzy rule matches the corresponding temperature control mode based on the ambient temperature level and the average temperature level of the battery cell.

[0044] In this specific embodiment, the outdoor ambient temperature level and the average temperature level of the battery cell are classified as follows: below 0°C is extremely cold, 0-15°C is cold, 16-30°C is moderate, 31-40°C is hot, and above 41°C is extremely hot.

[0045] In this specific embodiment, the temperature control modes include compressor heating mode, compressor cooling mode, natural cooling mode, and coupled cooling mode;

[0046] The compressor cooling mode: In the cooling mode of the air conditioning system, the third port of the three-way valve 2 is closed, and the insulating liquid flows into the heat exchange container 3 through the passage from the first port to the second port. The insulating liquid exchanges heat with the evaporator 4 through the heat exchange container 3, so that the insulating liquid releases heat and then returns to the insulating liquid circulation pool.

[0047] The compressor heating mode: In the heating mode of the air conditioning system, the third port of the three-way valve 2 is closed, and the insulating liquid flows into the heat exchange container 3 through the passage from the first port to the second port. The insulating liquid exchanges heat with the evaporator 4 through the heat exchange container 3, so that the insulating liquid absorbs heat and then returns to the insulating liquid circulation pool.

[0048] The natural cooling mode: the second port of the three-way valve 2 is closed, and the insulating liquid flows into the natural cooling coil 1 through the passage from the first port to the third port. The insulating liquid exchanges heat with the outdoor air through the natural cooling coil 1, so that the insulating liquid releases heat and then returns to the insulating liquid circulation pool through the heat exchange container 3.

[0049] The coupled cooling mode: In the cooling mode of the air conditioning system, the insulating liquid flows into the natural cooling coil 1 through the passage from the first port to the third port. The insulating liquid is first pre-cooled by exchanging heat with the outdoor air through the natural cooling coil 1, and then exchanges heat with the evaporator 4 through the heat exchange container 3, so that the insulating liquid releases heat and then returns to the insulating liquid circulation pool.

[0050] The following sections will explain the operating modes for different seasons in more detail.

[0051] 1) Summer Operation Mode

[0052] refer to Figure 2 As shown, according to the second law of thermodynamics, heat transfer from a low-temperature environment to a high-temperature environment requires energy. Therefore, in summer, electrical energy is needed to power the air conditioning unit to dissipate heat from the indoor environment to the outdoors. At this time, the compressor and fan are turned on (to dissipate heat from the condenser of the air conditioning system), and the passage of the natural cooling coil 1 on the three-way valve 2 is closed. All the cooling load is borne by the compressor of the air conditioning system.

[0053] This method operates the compressor at full load when the external ambient temperature also fails to meet the requirements. The fuzzy control rules for the summer operation mode include:

[0054] When the outdoor ambient temperature is hot and the average temperature of the battery cell is hot or extremely hot, the compressor cooling mode is used.

[0055] When the outdoor ambient temperature is moderate and the average temperature of the battery cell is hot, a coupled cooling mode is adopted.

[0056] II) Transitional Season Operation Mode

[0057] refer to Figure 3 As shown, during transitional seasons or at night (when the outdoor temperature is lower than the indoor temperature), the insulating liquid is pre-cooled by the natural cooling coil 1. Any shortfall is supplemented by the compressor. At this time, the compressor and fan are on (for dissipating heat from the condenser of the air conditioning system), and natural cooling is activated. The cooling load is shared by the compressor and natural cooling coil 1 (natural cooling takes priority). As the outdoor temperature gradually decreases, the compressor's power consumption decreases accordingly. The compressor's cooling capacity is intelligently adjusted by the unit control system based on changes in the outdoor temperature.

[0058] The fuzzy control rules under the transitional season operation mode include:

[0059] When the outdoor ambient temperature is cold and the average temperature of the battery cell is hot, a natural cooling mode is adopted.

[0060] When the outdoor ambient temperature is moderate and the average temperature of the battery cells is hot, a coupled cooling mode is adopted.

[0061] When the outdoor ambient temperature is cold and the average temperature of the battery cell is extremely hot, a coupled cooling mode is adopted.

[0062] III) Winter Operation Mode

[0063] refer to Figure 4 As shown, in winter (when the outdoor ambient temperature is as low as specified), the insulating liquid is directly supplied to the terminal equipment after heat exchange through the natural cooling coil 1: the compressor is off, the fan is off, and natural cooling is on. The cooling load is entirely borne by the natural cooling coil 1. The compressor input power is 0.

[0064] The fuzzy control rules under the winter seasonal operation mode include:

[0065] When the outdoor ambient temperature is cold and the average temperature of the battery cell is hot, the natural cooling mode is adopted.

[0066] When the outdoor ambient temperature is extremely cold and the average temperature of the battery cell is hot, the natural cooling mode is adopted.

[0067] When the outdoor ambient temperature is cold and the average temperature of the battery cell is cold, the compressor heating mode is adopted.

[0068] When the outdoor ambient temperature is extremely cold and the average temperature of the battery cell is cold, the compression mechanism is used for heating.

[0069] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0070] The above technical solutions are merely specific embodiments of the present invention. For those skilled in the art, based on the principles disclosed in the present invention, it is easy to make various types of improvements or modifications, and not limited to the technical solutions described in the above specific embodiments of the present invention. Therefore, the foregoing descriptions are only preferred and not restrictive.

Claims

1. A heat exchange system characterized by: The system includes an air conditioning system and a natural cooling system. The natural cooling system includes a natural cooling coil, a three-way valve, and a controller for switching the three-way valve's path. A heat exchange container is embedded in the center of the evaporator of the air conditioning system, and the heat exchange tubes of the evaporator are in close contact with the surface of the heat exchange container. The heat exchange container has an inlet and an outlet at both ends for the heat exchange medium to flow in and out. The first, second, and third ports of the three-way valve are used to input the heat exchange medium, connect to the inlet, and connect to the inlet of the natural cooling coil, respectively. The outlet of the natural cooling coil is connected in parallel to the path between the three-way valve and the inlet, allowing the heat exchange medium to be pre-cooled by the natural cooling coil before flowing into the heat exchange container. The air conditioning system also includes a four-way reversing valve. The compressor of the air conditioning system controls the flow of refrigerant to the condenser or evaporator through the four-way reversing valve, thereby realizing the switching between cooling mode and heating mode. The cooling modes include: compressor cooling mode, natural cooling mode, and coupled cooling mode; The compressor cooling mode: In the cooling mode of the air conditioning system, the third port of the three-way valve is closed, and the insulating liquid flows into the heat exchange container from the passage from the first port to the second port. The insulating liquid exchanges heat with the evaporator through the heat exchange container, so that the insulating liquid releases heat and then returns to the insulating liquid circulation pool. The natural cooling mode: the second port of the three-way valve is closed, and the insulating liquid flows into the natural cooling coil from the passage from the first port to the third port. The insulating liquid exchanges heat with the outdoor air through the natural cooling coil, so that the insulating liquid releases heat and then returns to the insulating liquid circulation pool through the heat exchange container. The coupled cooling mode: In the cooling mode of the air conditioning system, the insulating liquid flows into the natural cooling coil from the passage from the first port to the third port. The insulating liquid is first pre-cooled by exchanging heat with the outdoor air through the natural cooling coil, and then exchanges heat with the evaporator through the heat exchange container, so that the insulating liquid releases heat and then returns to the insulating liquid circulation pool. The heating mode includes the compressor heating mode: In the heating mode of the air conditioning system, the third port of the three-way valve is closed, and the insulating liquid flows into the heat exchange container from the first port to the second port. The insulating liquid exchanges heat with the evaporator through the heat exchange container, so that the insulating liquid absorbs heat and then returns to the insulating liquid circulation pool.

2. The heat exchange system of claim 1, wherein: The air conditioning system is a variable frequency air conditioning system.

3. An immersion energy storage system, comprising a battery pack immersed in an insulating liquid circulation pool, the battery pack being composed of several modules, each module being composed of several battery cells, characterized in that: It also includes the heat exchange system as described in claim 2, wherein the first port of the three-way valve in the heat exchange system is connected to the outlet of the insulating liquid circulation tank, and the outlet of the heat exchange container of the heat exchange system is connected to the return port of the insulating liquid circulation tank.

4. A method of temperature control of an immersion energy storage system, characterized by: The immersion energy storage system as described in claim 3 is used, and the outdoor ambient temperature and the average temperature of the battery cells are used as inputs for fuzzy control. The input power of the compressor in the variable frequency air conditioning system is controlled according to fuzzy rules, thereby adjusting the cooling / heating. The fuzzy rules match the corresponding temperature control mode based on the ambient temperature level and the average temperature level of the battery cell. Temperature control modes include compressor heating mode, compressor cooling mode, natural cooling mode, and coupled cooling mode; The compressor cooling mode: In the cooling mode of the air conditioning system, the third port of the three-way valve is closed, and the insulating liquid flows into the heat exchange container from the passage from the first port to the second port. The insulating liquid exchanges heat with the evaporator through the heat exchange container, so that the insulating liquid releases heat and then returns to the insulating liquid circulation pool. The compressor heating mode: In the heating mode of the air conditioning system, the third port of the three-way valve is closed, and the insulating liquid flows into the heat exchange container from the passage from the first port to the second port. The insulating liquid exchanges heat with the evaporator through the heat exchange container, so that the insulating liquid absorbs heat and then returns to the insulating liquid circulation pool. The natural cooling mode: the second port of the three-way valve is closed, and the insulating liquid flows into the natural cooling coil from the passage from the first port to the third port. The insulating liquid exchanges heat with the outdoor air through the natural cooling coil, so that the insulating liquid releases heat and then returns to the insulating liquid circulation pool through the heat exchange container. The coupled cooling mode: In the cooling mode of the air conditioning system, the insulating liquid flows into the natural cooling coil from the first port to the third port. The insulating liquid is first pre-cooled by exchanging heat with the outdoor air through the natural cooling coil, and then exchanges heat with the evaporator through the heat exchange container, so that the insulating liquid releases heat and then returns to the insulating liquid circulation pool.

5. The immersion energy storage system temperature control method of claim 4, wherein: The outdoor ambient temperature rating and the average cell temperature rating are classified as follows: below 0℃ is extremely cold, 0~15℃ is cold, 16~30℃ is moderate, 31~40℃ is hot, and above 41℃ is extremely hot.

6. The temperature control method for the immersion energy storage system according to claim 5, characterized in that: The matching methods between ambient temperature rating and average cell temperature rating include: When the outdoor ambient temperature is hot and the average temperature of the battery cell is hot or extremely hot, the compressor cooling mode is used. When the outdoor ambient temperature is moderate and the average temperature of the battery cell is hot, the coupling cooling mode is adopted. When the outdoor ambient temperature is cold and the average temperature of the battery cell is hot, the natural cooling mode is adopted. When the outdoor ambient temperature is moderate and the average temperature of the battery cell is hot, the coupling cooling mode is adopted. When the outdoor ambient temperature is cold and the average temperature of the battery cell is extremely hot, a coupled cooling mode is adopted. When the outdoor ambient temperature is cold and the average temperature of the battery cell is hot, the natural cooling mode is adopted. When the outdoor ambient temperature is extremely cold and the average temperature of the battery cell is hot, the natural cooling mode is adopted. When the outdoor ambient temperature is cold and the average temperature of the battery cell is cold, the compressor heating mode is adopted. When the outdoor ambient temperature is extremely cold and the average temperature of the battery cell is cold, the compression mechanism is used for heating.

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