Double-layer flow channel integrated liquid cooling device and lithium ion battery cooling device

Abstract

The utility model provides a double-layer runner integrated liquid cooling device and a lithium ion battery cooling device, which comprise at least one group of double-layer runners which are arranged into a whole, one layer of the double-layer runners is provided with runners with the flowing direction from two sides to the middle, and the other layer of the double-layer runners is provided with runners with the flowing direction from the middle to the two sides. According to the liquid cooling device, double-circulation cooling or heating is conducted on the battery by arranging the double-layer flow channels with the opposite flow directions, the two layers of flow channels complement each other, one flow channel is from inside to outside, and the other flow channel is from outside to inside, compared with a single flow channel, the liquid cooling device can effectively improve the situation that the temperature difference of the battery is too large, the working temperature consistency of the battery is improved, and the service life of the battery is prolonged. The service life of the battery is further prolonged; the endurance mileage is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium ion batteries, and in particular to a double-layer flow channel integrated liquid cooling device and a lithium ion battery cooling device. Background Art

[0002] As energy vehicles are becoming more and more popular, lithium-ion batteries are widely used as the main power source. At present, the mainstream of the industry is lithium-ion batteries with liquid electrolytes. The energy density development of liquid electrolytes has reached a bottleneck, and liquid electrolytes have the risk of corroding battery electrodes and are volatile. Major battery manufacturers have focused on the next generation of solid-state batteries. Solid-state batteries have higher energy density, higher cycle life, and higher charge and discharge rates, but at the same time, the heat generation also increases sharply, which also puts forward higher requirements for thermal management and thermal safety. In order to ensure that solid-state batteries maintain safe and efficient operation within a suitable temperature range, it is generally necessary to use liquid cooling devices to heat or cool the batteries. Liquid cooling plate is the most common cooling functional part, but common liquid cooling plate uses a single flow channel, adopts the idea of ​​entering from both sides and returning in the middle or entering from one side and returning from one side. This will cause a large temperature difference between battery heating or cooling. When the battery temperature difference is large, it will cause the performance and capacity attenuation rate of each battery cell in the battery module to be inconsistent, thereby affecting the overall performance of the battery assembly. Liquid cooling plate usually reduces the battery temperature difference by adjusting the water flow rate, but the temperature is not easy to control accurately, resulting in a battery temperature difference of 8-10℃, which cannot reach the suitable working temperature of the battery, thereby reducing battery life and increasing cruising range. Utility Model Content

[0003] The technical problem to be solved by the utility model is how to make the temperature of the liquid cooling device uniform so that the battery can reach a suitable working temperature.

[0004] The utility model solves the above technical problems through the following technical means:

[0005] The utility model provides a double-layer flow channel integrated liquid cooling device, comprising at least one group of double-layer flow channels arranged as one body, wherein one layer of the double-layer flow channel is provided with a flow channel with a flow direction of entering from both sides and exiting from the middle, and the other layer is provided with a flow channel with a flow direction of entering from the middle and exiting from both sides.

[0006] Beneficial effect: The liquid cooling device of the present application performs dual-cycle cooling or heating of the battery by setting up a double-layer flow channel with opposite flow directions. The two layers of flow channels complement each other, one from the inside to the outside and the other from the outside to the inside. Compared with a single flow channel, the liquid cooling device of the present application can effectively improve the excessive temperature difference of the battery, improve the temperature consistency of the battery operation, and further improve the battery life and increase the cruising range.

[0007] Preferably, it also includes an upper plate of the liquid cooling plate, a connecting pipeline and an inlet and outlet joint, the connecting pipeline is communicated with the double-layer flow channel, and the connecting pipeline and the inlet and outlet joint are fixed on the upper plate of the liquid cooling plate.

[0008] Preferably, the double-layer flow channel includes a liquid cooling plate middle plate and a liquid cooling plate lower plate. The liquid cooling plate middle plate is provided with a flow channel with a flow direction of entering from both sides and exiting from the middle. The liquid cooling plate lower plate is provided with a flow channel with a flow direction of entering from the middle and exiting from both sides. The liquid cooling plate upper plate, liquid cooling plate middle plate and liquid cooling plate lower plate are fixed in sequence as a whole.

[0009] Preferably, the flow channel of the liquid cooling plate middle plate includes a first liquid inlet flow channel, a first middle flow channel, a first left flow channel, a first right flow channel and a first liquid outlet flow channel; the first liquid inlet flow channel is arranged at the outermost edge of the liquid cooling plate middle plate; the first liquid outlet flow channel is arranged below the first liquid inlet flow channel; the first left flow channel is arranged at the leftmost part of the liquid cooling plate middle plate; the first right flow channel is arranged at the rightmost part of the liquid cooling plate middle plate; the first middle flow channel is arranged in the middle position of the liquid cooling plate middle plate, and the first liquid inlet flow channel is sequentially connected with the first left flow channel or the first right flow channel, the first middle flow channel and the first liquid outlet flow channel.

[0010] Preferably, the flow channel of the lower plate of the liquid cooling plate includes a second liquid inlet flow channel, a second middle flow channel, a second left flow channel, a second right flow channel and a second liquid outlet flow channel; the second liquid outlet flow channel is arranged at the outermost edge of the lower plate of the liquid cooling plate; the second liquid inlet flow channel is arranged below the second liquid outlet flow channel; the second left flow channel is arranged at the leftmost part of the lower plate of the liquid cooling plate; the second right flow channel is arranged at the rightmost part of the lower plate of the liquid cooling plate; the second middle flow channel is arranged in the middle position of the lower plate of the liquid cooling plate, and the second liquid inlet flow channel is connected with the second middle flow channel, the second left flow channel or the second right flow channel and the second liquid outlet flow channel in sequence.

[0011] Preferably, the flow channel further includes a plurality of branch flow channels; two first intermediate flow channels are provided, which are respectively connected to the first left flow channel and the first right flow channel through a plurality of branch flow channels, and the branch flow channels are curved rotating flow channels.

[0012] Preferably, the flow channel further includes a plurality of branch flow channels; two second intermediate flow channels are provided, which respectively communicate with the second left flow channel and the second right flow channel through a plurality of branch flow channels, and the branch flow channels are curved rotating flow channels.

[0013] Preferably, the multiple branch flow channels are symmetrically arranged.

[0014] Preferably, the inlet and outlet joints include a first inlet joint, a second inlet joint, a first outlet joint and a second outlet joint; the inlet and outlet joints are connected to the male plug of the quick-connect joint.

[0015] Beneficial effect: The inlet and outlet joints are connected to the male plug of the quick-connect joint, which plays a role in sealing the connecting pipeline, and also plays a role in evenly flowing the automobile cooling water into each flow channel.

[0016] The utility model also provides a lithium-ion battery cooling device, comprising the above-mentioned double-layer flow channel integrated liquid cooling device and an automobile cooling water circulation system, wherein the connecting pipeline is connected to the automobile cooling water circulation system.

[0017] The advantages of the utility model are:

[0018] The liquid cooling device of the present application is provided with flow channels with opposite flow directions on the middle plate and the lower plate of the liquid cooling plate. The automobile cooling water circulation system performs double-circulation cooling or heating of the battery in the double-layer flow channel through connecting pipes. The two layers of flow channels complement each other, one from the inside to the outside, and the other from the outside to the inside. Compared with a single flow channel, the liquid cooling device of the present application can effectively improve the excessive temperature difference of the battery, improve the temperature consistency of the battery operation, and further improve the battery life and increase the cruising range.

[0019] The liquid cooling device of the present application has liquid flowing into a flow channel that enters from both sides and returns to the middle, and a flow channel that enters from the middle and returns to both sides. The two layers of flow channels complement each other, one from the inside to the outside, and the other from the outside to the inside. Combined with the CFD simulation software starccm+, the two layers of flow channels distribute an appropriate amount of liquid, and the temperature difference of the battery can be maintained within 5°C, which reduces the temperature difference of the battery, improves the consistency of the battery operating temperature, and thereby improves the battery's charging and discharging capacity, improves the battery cycle life, and improves the battery's durability.

[0020] The lithium-ion battery cooling device of the present application is reasonably designed, has strong cooling and heating capabilities, and has good temperature uniformity, which effectively improves battery life and increases cruising range. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is an exploded view of a double-channel integrated liquid cooling device of an embodiment;

[0022] Figure 2 is a plan view of the upper plate of the liquid cooling plate of the embodiment;

[0023] Figure 3 is a plan view of a plate in a liquid cooling plate of an embodiment; arrows in the figure indicate the direction of liquid flow;

[0024] Figure 4 is a plan view of the lower plate of the liquid cooling plate of the embodiment; the arrows in the figure indicate the flow direction of the liquid;

[0025] Figure 5 is a cross-sectional view of a double-channel integrated liquid cooling device of an embodiment;

[0026] In the figure: 1-liquid cooling plate upper plate; 2-liquid cooling plate middle plate; 21-first liquid inlet channel; 22-first middle channel; 23-first left channel; 24-first right channel; 25-first liquid outlet channel; 3-liquid cooling plate lower plate; 31-second liquid inlet channel; 32-second middle channel; 33-second right channel; 34-second left channel; 35-second liquid outlet channel; 41-first inlet joint; 42-second inlet joint; 51-first outlet joint; 52-second outlet joint; 61-inlet pipeline; 62-outlet pipeline. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the utility model clearer, the technical solution in the embodiments of the utility model will be clearly and completely described below in combination with the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model; in addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. It should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0029] Example 1

[0030] like Figure 1-5As shown, the present embodiment provides a double-layer flow channel integrated liquid cooling device, including a liquid cooling plate upper plate 1, a liquid cooling plate middle plate 2, a liquid cooling plate lower plate 3, connecting pipes and inlet and outlet joints; the connecting pipes and the inlet and outlet joints are fixed on the liquid cooling plate upper plate 1, the connecting pipes include an inlet pipe 61 and an outlet pipe 62, the liquid cooling plate middle plate 2 is provided with a flow channel with a flow direction of entering from both sides and exiting from the middle, the liquid cooling plate lower plate 3 is provided with a flow channel with a flow direction of entering from the middle and exiting from both sides, the flow channel on the liquid cooling plate middle plate 2 and the flow channel on the liquid cooling plate lower plate 3 form a double-layer flow channel, the connecting pipe is connected to the double-layer flow channel, and the liquid cooling plate upper plate 1, the liquid cooling plate middle plate 2, and the liquid cooling plate lower plate 3 are welded into one.

[0031] The upper plate 1 of the liquid cooling plate is made of an aluminum alloy material with a model number of Al3003MOD, which is used to improve the strength and flatness of the upper plate 1 of the liquid cooling plate. The middle plate 2 of the liquid cooling plate and the lower plate 3 of the liquid cooling plate are made of ordinary aluminum alloy materials with a model number of Al3003, or aluminum alloy materials of the same model as the upper plate 1 of the liquid cooling plate are selected. The inlet and outlet joints are riveted above the upper plate 1 of the liquid cooling plate, and then the upper plate 1 of the liquid cooling plate is brazed with the middle plate 2 of the liquid cooling plate and the lower plate 3 of the liquid cooling plate to form a whole.

[0032] like Figure 3 As shown, the flow channel of the liquid cooling plate middle plate 2 includes a first liquid inlet flow channel 21, a first middle flow channel 22, a first left flow channel 23, a first right flow channel 24, a first liquid outlet flow channel 25 and a plurality of branch flow channels; the first liquid inlet flow channel 21 is arranged at the outermost edge of the liquid cooling plate middle plate 2. The first liquid inlet flow channel 21 of this embodiment is arranged at the uppermost edge of the liquid cooling plate middle plate 2, and is provided with a first liquid inlet hole, the first liquid inlet hole is arranged on the right side of the first liquid inlet flow channel 21, and the first liquid inlet hole is connected to the inlet pipeline 61 of the connecting pipeline; the first liquid outlet flow channel 25 is arranged below the first liquid inlet flow channel 21, and is provided with a first liquid outlet hole, the first liquid outlet hole is arranged on the left side of the first liquid outlet flow channel 25, and the first liquid outlet hole is connected to the outlet pipeline 62 of the connecting pipeline. The first left channel 23 is arranged at the leftmost part of the liquid cooling plate middle plate 2; the first right channel 24 is arranged at the rightmost part of the liquid cooling plate middle plate 2; the first liquid inlet channel 21 is connected with the first left channel 23 and the first right channel 24 at the edge of the liquid cooling plate middle plate 2, the first middle channel 22 is arranged in the middle position of the liquid cooling plate middle plate 2, and the first middle channel 22 is provided with two channels, one of the first middle channels 22 is connected with the first left channel 23 through a plurality of branch channels, and the other is connected with the first right channel 24 through a plurality of branch channels, the shape of the branch channel is curved and turned, similar to a snake shape, and the branch channels on the left and right sides are symmetrically arranged, and the first middle channel 22 is connected with the first liquid outlet channel 25.

[0033] The liquid flows into the liquid cooling device from the inlet pipe 61, and then enters the liquid cooling plate middle plate 2. The liquid enters the first liquid inlet channel 21 through the first liquid inlet hole, flows to both sides, flows into the first left channel 23 and the first right channel 24, and then flows from the first left channel 23 through multiple branch channels into the first middle channel 22, and at the same time flows from the first right channel 24 through multiple branch channels into the first middle channel 22. Finally, the liquid flows out of the first liquid outlet hole from the first liquid outlet channel 25 and flows out through the outlet pipe 62. The liquid flows as follows: Figure 3 As indicated by the arrow in .

[0034] like Figure 4 As shown, the flow channel of the lower plate 3 of the liquid cooling plate includes a second liquid inlet flow channel 31, a second middle flow channel 32, a second left flow channel 34, a second right flow channel 33, a second liquid outlet flow channel 35 and a plurality of branch flow channels; the second liquid outlet flow channel 35 is arranged at the outermost edge of the lower plate 3 of the liquid cooling plate. The second liquid outlet flow channel 35 of this embodiment is arranged at the uppermost edge of the lower plate 3 of the liquid cooling plate, and is provided with a second liquid outlet hole, the second liquid outlet hole is arranged on the left side of the second liquid outlet flow channel 35, and the second liquid outlet hole is connected to the outlet pipeline 62 of the connecting pipeline; the second liquid inlet flow channel 31 is arranged below the second liquid outlet flow channel 35, and is provided with a second liquid inlet hole, the second liquid outlet hole is arranged on the right side of the second liquid inlet flow channel 31, and the second liquid inlet hole is connected to the inlet of the connecting pipeline The pipeline 61 is connected; the second left flow channel 34 is arranged at the leftmost part of the lower plate 3 of the liquid cooling plate; the second right flow channel 33 is arranged at the rightmost part of the lower plate 3 of the liquid cooling plate; the second liquid outlet flow channel 35 is connected with the second left flow channel 34 and the second right flow channel 33, and the second middle flow channel 32 is arranged in the middle position of the lower plate 3 of the liquid cooling plate. There are two second middle flow channels 32, one of the second middle flow channels 32 is connected with the second left flow channel 34 through multiple branch flow channels, and the other is circulated with the second right flow channel 33 through multiple branch flow channels. The shape of the branch flow channel is curved and turned, similar to a snake, and the branch flow channels on the left and right sides are symmetrically arranged, and the second middle flow channel 32 is connected with the second liquid outlet flow channel 35.

[0035] The liquid flows into the liquid cooling device from the inlet pipe 61, and then enters the lower plate 3 of the liquid cooling plate. The liquid enters the second liquid inlet channel 31 through the second liquid inlet hole, and flows into the second middle channel 32 respectively. The liquid flows from one of the second middle channels 32 into the second left channel 34 through multiple branch channels. At the same time, the liquid flows from another of the second middle channels 32 into the second right channel 33 through multiple branch channels. The liquid then flows from the second left channel 34 and the second right channel 33 into the second liquid outlet channel 35 at the same time, flows out of the second liquid outlet hole, and flows out through the outlet pipe 62. The liquid flows as follows: Figure 4 As indicated by the arrow in .

[0036] The liquid cooling device uses two layers of flow channels for liquid to flow into, one flow channel that enters from both sides and returns to the middle, and the other flow channel that enters from the middle and returns to both sides. The two layers of flow channels complement each other, one from inside to outside, and the other from outside to inside. Combined with the CFD simulation software starccm+, the two layers of flow channels distribute the appropriate amount of liquid, and the temperature difference of the battery can be maintained within 5°C, which reduces the temperature difference of the battery, improves the consistency of the battery operating temperature, and thus improves the battery's charge and discharge capacity, improves the battery cycle life, and improves the battery's durability.

[0037] The inlet and outlet joints include a first inlet joint 41, a second inlet joint 42, a first outlet joint 51 and a second outlet joint 52, and the inlet and outlet joints are aluminum joints; the inlet and outlet joints are riveted above the upper plate 1 of the liquid cooling plate, and the other end of the inlet and outlet joints is connected to the male plug of the quick-plug joint; on the one hand, it seals the liquid cooling device, and on the other hand, the liquid flows into the inlet pipe 61, flows into the flow channel through the first inlet joint 41 and the second inlet joint 42, and then flows out from the other side of the first outlet joint 51 and the second outlet joint 52, and flows out through the outlet pipe 62, which plays a role in evenly flowing the liquid into each flow channel.

[0038] The first inlet joint 41 is consistent with the first outlet joint 51 in size; the second inlet joint 42 is consistent with the second outlet joint 52 in size; by keeping the inlet and outlet joints in the same size, a fool-proof design is achieved.

[0039] Conventional liquid cooling channel designs adopt a single channel that enters from both sides and returns in the middle, or enters from one side and returns from one side, which cannot effectively reduce the large temperature difference caused by the position reasons. The double-layer channel integrated liquid cooling device of the present application perfectly solves this problem by setting a double-layer channel design with opposite flow directions. Compared with a single channel, it has stronger heat exchange capacity, significantly improved cooling capacity, and improved consistency of battery operating temperature, which is beneficial to improving battery life and increasing cruising range.

[0040] Those skilled in the art will appreciate that, according to the design principle of the present invention, the liquid cooling device may have multiple sets of the double-layer flow channels, thereby achieving a better cooling effect.

[0041] Example 2

[0042] This embodiment provides a lithium-ion battery cooling device, including the double-layer flow channel integrated liquid cooling device of Example 1 and an automobile cooling water circulation system. The liquid cooling device is connected to the automobile cooling water circulation system through a connecting pipeline, and the inlet pipeline 61 and the outlet pipeline 62 are both connected to the automobile cooling water circulation system.

[0043] The lithium-ion battery cooling device of the present application is reasonably designed, has strong cooling and heating capabilities, and has good temperature uniformity, which is beneficial to improving the life of the battery cell and increasing the cruising range.

[0044] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A double-layer flow channel integrated liquid cooling device, characterized in that: It comprises at least one group of double-layer flow channels arranged as one body, wherein one layer of the double-layer flow channels is provided with flow channels with flow directions of entering from both sides and exiting from the middle, and the other layer is provided with flow channels with flow directions of entering from the middle and exiting from both sides.

2. The double-layer flow channel integrated liquid cooling device according to claim 1, characterized in that: It also comprises a liquid cooling plate upper plate (1), a connecting pipeline and an inlet and outlet joint, wherein the connecting pipeline is in communication with the double-layer flow channel, and the connecting pipeline and the inlet and outlet joint are fixed on the liquid cooling plate upper plate (1).

3. The double-layer flow channel integrated liquid cooling device according to claim 2, characterized in that: The double-layer flow channel comprises a liquid cooling plate middle plate (2) and a liquid cooling plate lower plate (3). The liquid cooling plate middle plate (2) is provided with a flow channel with a flow direction of entering from both sides and exiting from the middle. The liquid cooling plate lower plate (3) is provided with a flow channel with a flow direction of entering from the middle and exiting from both sides. The liquid cooling plate upper plate (1), the liquid cooling plate middle plate (2) and the liquid cooling plate lower plate (3) are fixed in sequence as a whole.

4. The double-channel integrated liquid cooling device according to claim 3, characterized in that: The flow channels of the liquid cooling plate middle plate (2) include a first liquid inlet flow channel (21), a first middle flow channel (22), a first left flow channel (23), a first right flow channel (24) and a first liquid outlet flow channel (25); the first liquid inlet flow channel (21) is arranged at the outermost edge of the liquid cooling plate middle plate (2); the first liquid outlet flow channel (25) is arranged below the first liquid inlet flow channel (21); the first left flow channel (23) is arranged at the leftmost part of the liquid cooling plate middle plate (2); the first right flow channel (24) is arranged at the rightmost part of the liquid cooling plate middle plate (2); the first middle flow channel (22) is arranged at the middle position of the liquid cooling plate middle plate (2), and the first liquid inlet flow channel (21) is sequentially connected to the first left flow channel (23) or the first right flow channel (24), the first middle flow channel (22) and the first liquid outlet flow channel (25).

5. The double-channel integrated liquid cooling device according to claim 4, characterized in that: The flow channel also includes a plurality of branch flow channels; the first intermediate flow channel (22) is provided with two, which are respectively connected to the first left flow channel (23) and the first right flow channel (24) through a plurality of branch flow channels, and the branch flow channels are curved rotating flow channels.

6. The double-channel integrated liquid cooling device according to claim 3, characterized in that: The flow channel of the lower plate (3) of the liquid cooling plate comprises a second liquid inlet flow channel (31), a second middle flow channel (32), a second left flow channel (34), a second right flow channel (33) and a second liquid outlet flow channel (35); the second liquid outlet flow channel (35) is arranged at the outermost edge of the lower plate (3) of the liquid cooling plate; the second liquid inlet flow channel (31) is arranged below the second liquid outlet flow channel (35); the second left flow channel (34) is arranged at the leftmost part of the lower plate (3) of the liquid cooling plate; the second right flow channel (33) is arranged at the rightmost part of the lower plate (3) of the liquid cooling plate; the second middle flow channel (32) is arranged at the middle position of the lower plate (3) of the liquid cooling plate, and the second liquid inlet flow channel (31) is connected with the second middle flow channel (32), the second left flow channel (34) or the second right flow channel (33) and the second liquid outlet flow channel (35) in sequence.

7. The double-channel integrated liquid cooling device according to claim 6, characterized in that: The flow channel also includes a plurality of branch flow channels; the second middle flow channel (32) is provided with two, which respectively communicate with the second left flow channel (34) and the second right flow channel (33) through a plurality of branch flow channels, and the branch flow channels are curved rotating flow channels.

8. The double-channel integrated liquid cooling device according to claim 5 or 7, characterized in that: The multiple branch flow channels are symmetrically arranged.

9. The double-layer flow channel integrated liquid cooling device according to claim 2, characterized in that: The inlet and outlet joints include a first inlet joint (41), a second inlet joint (42), a first outlet joint (51) and a second outlet joint (52), and the inlet and outlet joints are connected to the male plug of the quick-connect joint.

10. A lithium-ion battery cooling device, characterized in that: It comprises the double-channel integrated liquid cooling device as described in any one of claims 1 to 9 and an automobile cooling water circulation system, wherein the liquid cooling device is connected to the automobile cooling water circulation system via a connecting pipeline.

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