energy storage system

Abstract

The present disclosure relates to an energy storage system for solving the technical problem of high energy consumption required for heat exchange of the energy storage system. The energy storage system comprises a prefabricated cabin, a wall part provided with a sandwich layer, the sandwich layer provided with a heat exchange coil, a liquid flow battery provided in the prefabricated cabin and comprising an electrolyte heat exchanger, an absorption cooling unit, and a thermal management flow path comprising a first circulation loop in fluid communication between the heat exchange coil and the absorption cooling unit, a second circulation loop in fluid communication between the absorption cooling unit and the electrolyte heat exchanger, and a third circulation loop in fluid communication between the heat exchange coil and the electrolyte heat exchanger; the energy storage system is configured to: when the external environment temperature is higher than the normal working temperature of the liquid flow battery, turn on the first circulation loop and the second circulation loop, and turn off the third circulation loop; when the external environment temperature is lower than the normal working temperature of the liquid flow battery, turn off the first circulation loop and the second circulation loop, and turn on the third circulation loop.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of energy storage devices, in particular, to an energy storage system. BACKGROUND

[0002] In the related art, the heat exchange mode of the liquid flow battery thermal management system mostly adopts a compressor refrigeration mode, for example, a compressor direct evaporation refrigeration, a compressor refrigeration reduces the circulating water temperature, and then the heat in the electrolyte is removed through low-temperature circulating water; the heat exchange of the liquid flow battery thermal management system can also be through recovering the heat generated by the energy storage system and through a multi-stage heat pump to improve the low-grade heat to the quality available for production and living heat, so as to realize the improvement of comprehensive efficiency.

[0003] However, these heat exchange modes essentially still need to use electric energy to take out the heat generated by the energy storage system, or change the setting of the heat exchanger, that is, the heat exchange still needs to consume additional energy and is not suitable for some relatively extreme environments. SUMMARY

[0004] The purpose of the present disclosure is to provide an energy storage system for solving the technical problem of high energy consumption required for heat exchange of the energy storage system.

[0005] In order to achieve the above purpose, the present disclosure provides an energy storage system arranged in an environment with large diurnal temperature difference, comprising: a prefabricated cabin, a sandwich layer is arranged in a wall part, a heat exchange coil is arranged in the sandwich layer, a liquid flow battery arranged in the prefabricated cabin, the liquid flow battery comprising an electrolyte heat exchanger, an absorption chiller unit, and a thermal management flow path comprising: a first circulating loop in fluid communication between the heat exchange coil and the absorption chiller unit, so that the heat absorbed by the heat exchange coil from the external environment is used as a heat source for refrigeration of the absorption chiller unit, a second circulating loop in fluid communication between the absorption chiller unit and the electrolyte heat exchanger, so that the absorption chiller unit cools the electrolyte heat exchanger, and a third circulating loop in fluid communication between the heat exchange coil and the electrolyte heat exchanger, so that the heat exchange coil cools the electrolyte heat exchanger; the energy storage system is configured to: when the external environment temperature is higher than the normal working temperature of the liquid flow battery, turn on the first circulating loop and the second circulating loop, and turn off the third circulating loop; when the external environment temperature is lower than the normal working temperature of the liquid flow battery, turn off the first circulating loop and the second circulating loop, and turn on the third circulating loop.

[0006] Optionally, the energy storage system further comprises a heat storage medium, and the energy storage system is configured to: when the external environment temperature is higher than the normal working temperature of the flow battery, and the temperature in the first circulation loop is higher than the first threshold, make the first circulation loop flow through the heat storage medium; when the external environment temperature is higher than the normal working temperature of the flow battery, and the temperature in the second circulation loop is higher than the second threshold, make the first circulation loop flow through the heat storage medium.

[0007] Optionally, the first circulation loop comprises a first liquid inlet flow path from the heat exchange coil to the absorption cooling unit and a first liquid return flow path from the absorption cooling unit to the heat exchange coil, and the energy storage system is configured to: when the external environment temperature is higher than the normal working temperature of the flow battery, and the temperature in the first liquid return flow path is higher than the first threshold, make the first liquid inlet flow path flow through the heat storage medium.

[0008] Optionally, the second circulation loop comprises a second liquid inlet flow path from the absorption cooling unit to the electrolyte heat exchanger and a second liquid return flow path from the electrolyte heat exchanger to the absorption cooling unit, and the energy storage system is configured to: when the external environment temperature is higher than the normal working temperature of the flow battery, and the temperature in the second liquid inlet flow path is higher than the second threshold, make the first liquid inlet flow path flow through the heat storage medium.

[0009] Optionally, the energy storage system further comprises a cold storage medium, and the energy storage system is configured to: when the external environment temperature is lower than the normal working temperature of the flow battery, and the temperature in the third circulation loop is lower than the third threshold, make the third circulation loop flow through the cold storage medium; when the external environment temperature is higher than the normal working temperature of the flow battery, and the temperature in the second circulation loop is higher than the second threshold, make the second circulation loop flow through the cold storage medium.

[0010] Optionally, the third circulation loop comprises a third liquid inlet flow path from the heat exchange coil to the electrolyte heat exchanger and a third liquid return flow path from the electrolyte heat exchanger to the heat exchange coil, and the energy storage system is configured to: when the external environment temperature is lower than the normal working temperature of the flow battery, and the temperature in the third liquid return flow path is lower than the third threshold, make the third liquid inlet flow path flow through the cold storage medium.

[0011] Optionally, the second circulation loop comprises a second liquid inlet flow path from the absorption chiller unit to the electrolyte heat exchanger and a second liquid return flow path from the electrolyte heat exchanger to the absorption chiller unit, and the energy storage system is configured to make the second liquid inlet flow path flow through the cold storage medium when the external environment temperature is higher than the normal operating temperature of the liquid flow battery and the temperature in the second liquid inlet flow path is higher than the second threshold value.

[0012] Optionally, the heat exchange medium in the heat exchange coil is water, ethanol, ethylene glycol, glycerol or lubricating oil, or a mixture of two or three of the above.

[0013] Optionally, the heat storage medium is a sensible heat storage material, a latent heat storage material, a thermochemical heat storage material or a phase change heat storage material.

[0014] Optionally, the absorption chiller unit is a lithium bromide unit.

[0015] With the above technical solution, in the energy storage system provided by the present disclosure, the interlayer of the prefabricated cabin is hollow, and the air therein can play a role in heat insulation and cold insulation, reducing the influence of the external environment temperature on the interior of the prefabricated cabin and avoiding excessive fluctuations in the interior temperature of the prefabricated cabin. In addition, when the external environment temperature is high during the day, the heat of the external environment can be used as a heat source for the absorption chiller unit to cool the electrolyte heat exchanger through the heat exchange coil, thereby reducing the heat exchange energy consumption of the liquid flow battery; when the external environment temperature is low at night, the heat of the electrolyte heat exchanger can be continuously dissipated to the external environment through the heat exchange coil, that is, the low-temperature external environment can directly cool the electrolyte heat exchanger through the heat exchange coil, thereby reducing the heat exchange energy consumption of the liquid flow battery. Through the energy storage system provided by the present disclosure, the temperature change of the external environment can be fully utilized to reduce the heat exchange energy consumption of the energy storage system, improve the efficiency of the energy storage system and ensure the stable and reliable operation of the energy storage system.

[0016] Other features and advantages of the present disclosure will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings are included to provide a further understanding of the present disclosure and constitute a part of the specification, and together with the following specific embodiments, serve to explain the present disclosure but do not constitute a limitation thereof. In the drawings:

[0018] Figure 1 is a structural schematic diagram of the energy storage system in the specific embodiments of the present disclosure, wherein the first circulation loop and the second circulation loop are connected, and the third circulation loop is disconnected;

[0019] Figure 2is a structural schematic diagram of the energy storage system in the specific embodiment of the present disclosure, wherein the first circulation loop and the second circulation loop are cut off, and the third circulation loop is conducted.

[0020] Legend of reference signs

[0021] 1 - prefabricated cabin, 10 - heat exchange coil,

[0022] 2 - flow battery, 20 - electrolyte heat exchanger,

[0023] 3 - absorption cooling unit,

[0024] 41 - first circulation loop, 411 - first liquid inlet flow path, 412 - first liquid return flow path, 42 - second circulation loop, 421 - second liquid inlet flow path, 422 - second liquid return flow path, 43 - third circulation loop, 431 - third liquid inlet flow path, 432 - third liquid return flow path,

[0025] 5 - heat storage medium,

[0026] 6 - cold storage medium. Specific embodiment

[0027] The specific embodiment of the present disclosure is described in detail below in combination with the accompanying drawings. It should be understood that the specific embodiment described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0028] In the present disclosure, the orientation words such as "inner" and "outer" used herein refer to the inner and outer relative to the outline of the corresponding component itself. The terms "first", "second", etc. used in the present disclosure are used to distinguish one element from another element, and do not have sequentiality and importance. In addition, when the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements, unless otherwise indicated.

[0029] According to the specific embodiment of the present disclosure, an energy storage system is provided, which is arranged in an environment with large diurnal temperature difference, for example, in a desert region. Referring to FIGS. 1 and 2, the energy storage system can include a prefabricated cabin 1, a flow battery 2, an absorption cooling unit 3, and a heat management flow path. Figure 1 and Figure 2 As shown in the drawings, the energy storage system can include a prefabricated cabin 1, a flow battery 2, an absorption cooling unit 3, and a heat management flow path.

[0030] The wall of the prefabricated cabin 1 can be provided with a sandwich, i.e. a hollow sandwich can be formed between the inner wall and the outer wall of the prefabricated cabin 1, and a heat exchange coil 10 can be arranged in the sandwich. In the specific embodiment of the present disclosure, the prefabricated cabin 1 can be a container.

[0031] The flow battery 2 can be arranged in the prefabricated cabin 1, and the flow battery 2 can include an electrolyte heat exchanger 20 through which electrolyte in positive and negative electrolyte tanks of the flow battery 2 can be cooled.

[0032] The absorption cooling unit 3 can use a heat source to perform refrigeration.

[0033] The heat management flow path can include a first circulation loop 41, a second circulation loop 42, and a third circulation loop 43. The first circulation loop 41 can be in fluid communication between the heat exchange coil 10 and the absorption cooling unit 3, so that heat absorbed by the heat exchange coil 10 from the external environment is used as a heat source for the absorption cooling unit 3 to perform refrigeration. The second circulation loop 42 can be in fluid communication between the absorption cooling unit 3 and the electrolyte heat exchanger 20, so that the absorption cooling unit 3 cools the electrolyte heat exchanger 20. The third circulation loop 43 can be in fluid communication between the heat exchange coil 10 and the electrolyte heat exchanger 20, so that the heat exchange coil 10 cools the electrolyte heat exchanger 20. The energy storage system can be configured to: when the external environment temperature is higher than the normal operating temperature of the flow battery 2, turn on the first circulation loop 41 and the second circulation loop 42, and turn off the third circulation loop 43 (see Figure 1 ); when the external environment temperature is lower than the normal operating temperature of the flow battery 2, turn off the first circulation loop 41 and the second circulation loop 42, and turn on the third circulation loop 43 (see Figure 2 ).

[0034] Through the above technical solutions, in the energy storage system provided by the present disclosure, the interlayer of the prefabricated cabin 1 is hollow, and the air therein can play a role in heat insulation and cooling, reducing the influence of the external environment temperature on the interior of the prefabricated cabin 1 and avoiding excessive fluctuations in the interior temperature of the prefabricated cabin 1. In addition, when the external environment temperature is high during the day, the heat of the external environment can be used as a heat source for the absorption cooling unit 3 to cool the electrolyte heat exchanger 20 through the heat exchange coil 10, thereby reducing the heat exchange energy consumption of the flow battery 2. When the external environment temperature is low at night, the heat of the electrolyte heat exchanger 20 can be continuously dissipated to the external environment through the heat exchange coil 10, that is, the low-temperature external environment can directly cool the electrolyte heat exchanger 20 through the heat exchange coil 10, thereby reducing the heat exchange energy consumption of the flow battery 2. Through the energy storage system provided by the present disclosure, the temperature change of the external environment can be fully utilized to reduce the heat exchange energy consumption of the energy storage system, improve the efficiency of the energy storage system, and ensure stable and reliable operation of the energy storage system.

[0035] In the specific embodiments of the present disclosure, the absorption cooling unit 3 can be a lithium bromide unit.

[0036] In the specific embodiment of the present disclosure, the heat exchange medium in the heat exchange coil 10 can be water, ethanol, ethylene glycol, glycerol or lubricating oil, or a mixture of two or three of the above, and needs to meet the normal working condition at -50°C.

[0037] In order to further improve the utilization rate of the heat from the external environment, as shown in Figure 1 and Figure 2 , the energy storage system can further include a heat storage medium 5, which can be connected to the first circulation loop 41 when the heat provided by the external environment is excessive (i.e. when the heat absorbed by the heat exchange coil 10 from the external environment is greater than the heat required for the absorption chiller unit 3 to cool), so as to store the excessive heat from the external environment. The heat storage medium 5 can also be connected to the first circulation loop 41 when the heat provided by the external environment is insufficient (i.e. when the heat absorbed by the heat exchange coil 10 from the external environment is less than the heat required for the absorption chiller unit 3 to cool). Specifically, the energy storage system can be configured such that when the temperature of the external environment is higher than the normal working temperature of the flow battery 2, and the temperature in the first circulation loop 41 is higher than a first threshold value, the first circulation loop 41 flows through the heat storage medium 5. For example, when the external environment is sunny and the temperature is high during the day, and the flow battery 2 is running at low power and generating less heat, causing the absorption chiller unit 3 to run at low power, the heat storage medium 5 can be connected to the first circulation loop 41 to store the excessive heat absorbed by the heat exchange coil 10 from the external environment in the heat storage medium 5. When the temperature of the external environment is higher than the normal working temperature of the flow battery 2, and the temperature in the second circulation loop 42 is higher than a second threshold value, the first circulation loop 41 flows through the heat storage medium 5. For example, when the flow battery 2 is running at high power and generating more heat, and the absorption chiller unit 3 needs to run at high power to quickly cool the electrolyte heat exchanger 20, but the external environment is not sunny enough and the temperature is not high enough during the day, the heat storage medium 5 can be connected to the first circulation loop 41 so that the heat exchange coil 10 absorbs heat from the external environment and the heat storage medium 5 to serve as the heat source for the absorption chiller unit 3, i.e. the heat in the heat storage medium 5 can compensate for the insufficient heat from the external environment.

[0038] As shown in Figure 1 and Figure 2 , the first circulation loop 41 can include a first liquid inlet flow path 411 from the heat exchange coil 10 to the absorption chiller unit 3 and a first liquid return flow path 412 from the absorption chiller unit 3 to the heat exchange coil 10. The energy storage system can be configured such that when the temperature of the external environment is higher than the normal working temperature of the flow battery 2, and the temperature in the first liquid return flow path 412 is higher than a first threshold value, i.e. when the heat absorbed by the heat exchange coil 10 from the external environment is not fully utilized by the absorption chiller unit 3, the first liquid inlet flow path 411 flows through the heat storage medium 5, so as to store the excessive heat in the heat storage medium 5 before the heat exchange medium in the heat exchange coil 10 reaches the absorption chiller unit 3.

[0039] Referring to Figure 1 and Figure 2 As shown, the second circulation loop 42 can include a second liquid inlet flow path 421 from the absorption chiller unit 3 to the electrolyte heat exchanger 20 and a second liquid return flow path 422 from the electrolyte heat exchanger 20 to the absorption chiller unit 3. The energy storage system can be configured to, when the external environment temperature is higher than the normal operating temperature of the liquid flow battery 2 and the temperature in the second liquid inlet flow path 421 is higher than the second threshold value, i.e., the absorption chiller unit 3 cannot sufficiently cool the heat exchange medium in the second circulation loop 42, make the first liquid inlet flow path 411 flow through the heat storage medium 5 to compensate for the heat in the heat storage medium 5 as a heat source to the absorption chiller unit 3, so that the absorption chiller unit 3 can fully refrigerate.

[0040] In the specific embodiments of the present disclosure, the heat storage medium 5 can be sensible heat storage material, latent heat storage material, thermochemical heat storage material or phase change heat storage material to meet the heat storage condition at 60℃.

[0041] In order to further improve the utilization rate of external environment cold, referring to Figure 1 and Figure 2As shown, the energy storage system can also include a cold storage medium 6, which is required to meet the cold storage condition at -50°C. The cold storage medium 6 can be connected to the third circulation loop 43 when there is excess cooling provided by the external environment (i.e. when the cooling provided by the external environment is greater than the cooling required by the electrolyte heat exchanger 20), so as to store the excess cooling in the external environment. The cold storage medium 6 can also be connected to the second circulation loop 42 when the absorption chiller unit 3 is unable to sufficiently cool the electrolyte heat exchanger 20 (e.g. when the heat absorbed by the heat exchange coil 10 from the external environment is less than the heat required by the absorption chiller unit 3 to cool), so as to further cool the heat exchange medium in the second circulation loop 42 using the cooling in the cold storage medium 6. Specifically, the energy storage system can be configured such that when the external environment temperature is lower than the normal operating temperature of the flow battery 2 and the temperature in the third circulation loop 43 is lower than a third threshold, for example, when the external environment temperature is low at night and the flow battery 2 is operating at low power and producing less heat, the third circulation loop 43 is caused to flow through the cold storage medium 6 in order to store excess cooling in the heat exchange coil 10 in the cold storage medium 6, so as to avoid the external environment excessively cooling the electrolyte heat exchanger 20 through the heat exchange coil 10, which can cause the electrolyte temperature to be too low. When the external environment temperature is higher than the normal operating temperature of the flow battery 2 and the temperature in the second circulation loop 42 is higher than a second threshold, for example, when the flow battery 2 is operating at high power and producing more heat, and the absorption chiller unit 3 is required to operate at high power to rapidly cool the electrolyte heat exchanger 20, but the external environment temperature is not high enough due to insufficient sunlight during the day, the second circulation loop 42 is caused to flow through the cold storage medium 6, so as to further cool the heat exchange medium in the second circulation loop 42 using the cooling in the cold storage medium 6, thereby compensating for the insufficient cooling of the heat exchange medium in the second circulation loop 42 by the absorption chiller unit 3. That is, when the absorption chiller unit 3 is unable to sufficiently cool the heat exchange medium in the second circulation loop 42, the heat stored in the heat storage medium 5 can be used to compensate for the heat source deficiency of the absorption chiller unit 3, and / or the cooling stored in the cold storage medium 6 can be used to directly further cool the heat exchange medium in the second circulation loop 42.

[0042] Reference Figure 1 and Figure 2As shown, the third circulation loop 43 can include a third liquid inlet flow path 431 from the heat exchange coil 10 to the electrolyte heat exchanger 20 and a third liquid return flow path 432 from the electrolyte heat exchanger 20 to the heat exchange coil 10. The energy storage system can be configured to, when the external environment temperature is lower than the normal working temperature of the flow battery 2 and the temperature in the third liquid return flow path 432 is lower than the third threshold value, i.e., the cooling capacity provided by the external environment is greater than the cooling capacity required for cooling the electrolyte heat exchanger 20, make the third liquid inlet flow path 431 flow through the cold storage medium 6, so that the heat exchange medium in the heat exchange coil 10 stores the excess cooling capacity into the cold storage medium 6 before reaching the electrolyte heat exchanger 20, avoiding excessive cooling of the electrolyte heat exchanger 20 by the heat exchange medium.

[0043] Reference Figure 1 and Figure 2 As shown, the energy storage system can also be configured to, when the external environment temperature is higher than the normal working temperature of the flow battery 2 and the temperature in the second liquid inlet flow path 421 is higher than the second threshold value, i.e., the heat exchange medium flowing back through the second liquid return flow path 422 is not sufficiently cooled by the absorption chiller unit 3, make the second liquid inlet flow path 421 flow through the cold storage medium 6, so that the heat exchange medium in the second circulation loop 42 is further cooled by the cold storage medium 6 before reaching the electrolyte heat exchanger 20, thereby ensuring the cooling effect of the heat exchange medium on the electrolyte heat exchanger 20.

[0044] Through the heat storage medium 5 and / or the cold storage medium 6, the utilization rate of heat and cooling capacity in the external environment by the energy storage system can be further improved, the heat exchange energy consumption of the energy storage system can be reduced, and the working stability of the flow battery 2 in the energy storage system can be further improved.

[0045] The preferred embodiments of the present disclosure are described in detail above with reference to the drawings, but the present disclosure is not limited to the specific details in the above-described embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0046] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again in the present disclosure.

[0047] In addition, various different embodiments of the present disclosure can also be combined in any manner, as long as they do not deviate from the idea of the present disclosure, and they should also be considered as disclosed by the present disclosure.

Claims

1. An energy storage system disposed in an environment with large diurnal temperature variation, characterized by, The energy storage system comprises: a prefabricated cabin, a wall of which is provided with a sandwich layer, the sandwich layer being provided with heat exchange coils, a flow battery provided in the prefabricated cabin, the flow battery comprising an electrolyte heat exchanger, an absorption chiller unit, and a thermal management flow path comprising: a first circulation loop in fluid communication between the heat exchange coils and the absorption chiller unit, so that heat absorbed by the heat exchange coils from an external environment is used as a heat source for refrigeration of the absorption chiller unit, a second circulation loop in fluid communication between the absorption chiller unit and the electrolyte heat exchanger, so that the absorption chiller unit cools the electrolyte heat exchanger, and a third circulation loop in fluid communication between the heat exchange coils and the electrolyte heat exchanger, so that the heat exchange coils cool the electrolyte heat exchanger; the energy storage system is configured to: when the external environment temperature is higher than the normal working temperature of the flow battery, turn on the first circulation loop and the second circulation loop, and turn off the third circulation loop; when the external environment temperature is lower than the normal working temperature of the flow battery, turn off the first circulation loop and the second circulation loop, and turn on the third circulation loop.

2. The energy storage system of claim 1, wherein, The energy storage system further comprises a heat storage medium, the energy storage system is configured to: when the external environment temperature is higher than the normal working temperature of the flow battery, and the temperature in the first circulation loop is higher than a first threshold, make the first circulation loop flow through the heat storage medium; when the external environment temperature is higher than the normal working temperature of the flow battery, and the temperature in the second circulation loop is higher than a second threshold, make the first circulation loop flow through the heat storage medium.

3. The energy storage system of claim 2, wherein, The first circulation loop comprises a first liquid inlet flow path from the heat exchange coils to the absorption chiller unit and a first liquid return flow path from the absorption chiller unit to the heat exchange coils, the energy storage system is configured to: when the external environment temperature is higher than the normal working temperature of the flow battery, and the temperature in the first liquid return flow path is higher than the first threshold, make the first liquid inlet flow path flow through the heat storage medium.

4. The energy storage system of claim 3, wherein, The second circulation loop comprises a second liquid inlet flow path from the absorption chiller unit to the electrolyte heat exchanger and a second liquid return flow path from the electrolyte heat exchanger to the absorption chiller unit, the energy storage system is configured to: when the external environment temperature is higher than the normal working temperature of the flow battery, and the temperature in the second liquid inlet flow path is higher than the second threshold, make the first liquid inlet flow path flow through the heat storage medium.

5. The energy storage system of claim 1, wherein, The energy storage system further comprises a cold storage medium, the energy storage system is configured to: when the external environment temperature is lower than the normal working temperature of the flow battery, and the temperature in the third circulation loop is lower than a third threshold, make the third circulation loop flow through the cold storage medium; when the external environment temperature is higher than the normal working temperature of the flow battery, and the temperature in the second circulation loop is higher than the second threshold, make the second circulation loop flow through the cold storage medium.

6. The energy storage system of claim 5, wherein, The third circulation loop comprises a third liquid inlet flow path from the heat exchange coil to the electrolyte heat exchanger and a third liquid return flow path from the electrolyte heat exchanger to the heat exchange coil, The energy storage system is configured to cause the third liquid inlet flow path to pass through the cold storage medium when the external environment temperature is lower than the normal working temperature of the flow battery and the temperature in the third liquid return flow path is lower than the third threshold value.

7. The energy storage system of claim 5, wherein, The second circulation loop comprises a second liquid inlet flow path from the absorption cooling unit to the electrolyte heat exchanger and a second liquid return flow path from the electrolyte heat exchanger to the absorption cooling unit, The energy storage system is configured to cause the second liquid inlet flow path to pass through the cold storage medium when the external environment temperature is higher than the normal working temperature of the flow battery and the temperature in the second liquid inlet flow path is higher than the second threshold value.

8. The energy storage system of claim 1, wherein, The heat exchange medium in the heat exchange coil is water, ethanol, ethylene glycol, glycerol or lubricating oil, or a mixture of two or three of the above.

9. The energy storage system of claim 2, wherein, The heat storage medium is a sensible heat storage material, a latent heat storage material, a thermochemical heat storage material or a phase change heat storage material.

10. The energy storage system of claim 1, wherein, The absorption cooling unit is a lithium bromide unit.

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