Experimental device for simulating invasion of seawater into karst aquifer

Abstract

The utility model relates to an experimental device for simulating seawater invasion into a karst aquifer, which belongs to the field of simulation experimental devices, and is characterized in that two permeable partition plates are arranged in a central water tank, the central water tank is divided into a fresh water bin, a middle sand chamber and a salt water bin by the permeable partition plates, and first water outlets are correspondingly formed in the fresh water bin, the middle sand chamber and the salt water bin; the two water blocking partition plates are correspondingly arranged on the outer sides of the two water permeable partition plates; the transparent pipeline is arranged in the middle sand chamber and is buried in a sand layer of the middle sand chamber, and the two ends of the transparent pipeline abut against the inner side walls of the two permeable partition plates correspondingly; the fresh water level control part is communicated with the fresh water bin; the salt water level control part is communicated with the salt water bin; the transparent pipeline is arranged to simulate the karst pipeline, so that the karst pipeline is closer to the karst stratum environment, the simulation process is more accurate, data closer to reality is provided for seawater invading the karst stratum, and reference value is higher.

Description

Technical Field

[0001] The utility model relates to the field of seawater intrusion simulation experiments, in particular to an experimental device for simulating seawater intrusion into a karst aquifer. Background Art

[0002] Seawater intrusion is a phenomenon in which seawater infiltrates into groundwater due to natural or human factors, resulting in the salinization of groundwater quality. Coastal areas are regions where seawater intrusion is generally severe. The hydrodynamic conditions of groundwater in these areas change, and the dynamic balance between fresh groundwater and seawater is disrupted, causing seawater to invade the fresh aquifer. Seawater intrusion can lead to problems such as a reduction in fresh water resources, soil salinization, and the abandonment of wells in coastal areas.

[0003] The karst aquifer is one of the aquifer types in coastal areas. In the karst aquifer of coastal areas, due to the existence of karst pipelines, solution pores, and karst caves, and sinkholes and "skylights" are usually connected to karst pipelines, etc., it is extremely vulnerable to external influences. Some karst caves open to the sea and are likely to become natural channels for seawater to invade the karst aquifer. Currently, most of the simulation devices for seawater intrusion are used to simulate the process of seawater invading the pore aquifer. For karst aquifers, the current simulation devices are difficult to truly reflect the phenomenon of seawater intrusion. Therefore, an experimental device for simulating seawater intrusion into a karst aquifer is proposed, which can help to reveal the intrusion mechanism of seawater into the karst aquifer, predict the degree of future seawater intrusion into the karst aquifer, and is of great significance for timely preventing and controlling seawater intrusion and preventing the deterioration of the groundwater quality in the karst aquifer. Summary of the Utility Model

[0004] Existing seawater intrusion simulation devices are more focused on simulating the process of seawater intrusion into the pore aquifer, and it is difficult for them to truly and accurately simulate the process of seawater intrusion into the karst aquifer. This application designs an experimental device for simulating seawater intrusion into the karst aquifer, which can help to reveal the intrusion mechanism of seawater into the karst aquifer, predict the degree of future seawater intrusion into the karst aquifer, can timely prevent and control seawater intrusion, and reduce the degree of deterioration of the groundwater quality in the karst aquifer. The specific technical solution adopted is as follows:

[0005] An experimental device for simulating seawater intrusion into a karst aquifer, comprising:

[0006] A central water tank, in which two permeable partition plates are provided. The two permeable partition plates divide the central water tank into a fresh water chamber, an intermediate sand chamber, and a salt water chamber. First drainage ports are respectively provided at the bottom end of the central water tank corresponding to the fresh water chamber, the intermediate sand chamber, and the salt water chamber;

[0007] Two water-blocking partition plates, one of the water-blocking partition plates is arranged on one side of one of the permeable partition plates close to the fresh water chamber, and the other water-blocking partition plate is arranged on one side of the other permeable partition plate close to the salt water chamber;

[0008] A transparent pipe is disposed in the middle sand chamber and buried in the sand layer of the middle sand chamber. The two ends of the transparent pipe respectively abut against the inner side walls of two water-permeable partitions.

[0009] A fresh water level control component is communicated with the fresh water tank and is used for controlling the stable fresh water level in the fresh water tank.

[0010] A salt water level control component is communicated with the salt water tank and is used for controlling the stable salt water level in the salt water tank.

[0011] Preferably, each water-permeable partition includes a porous partition and a geotextile. A water-blocking base is provided at the bottom of the central water tank, and the porous partition is vertically disposed on the water-blocking base.

[0012] Preferably, the water-blocking partition is vertically disposed on the water-blocking base, and the connection between the water-blocking partition and the inner wall of the central water tank and between the water-blocking partition and the water-blocking base is a sealed connection.

[0013] Preferably, mounting grooves are provided on the inner wall of the central water tank corresponding to the connection of the water-blocking partition and on the water-blocking base, and sealing strips are provided in the mounting grooves.

[0014] Preferably, the transparent pipe is made of an acrylic glass pipe.

[0015] Preferably, both the water-blocking partition and the central water tank are made of acrylic glass plates.

[0016] Preferably, the central water tank includes an inner box body and an outer box body. Two partitions are provided at intervals along the length direction of the bottom of the outer box body. The space between the inner box body and the outer box body is divided into a fresh water overflow cavity, an intermediate drainage cavity, and a salt water overflow cavity by the two partitions. The first drainage ports are provided on the inner box body, and the three first drainage ports correspond to the fresh water overflow cavity, the intermediate drainage cavity, and the salt water overflow cavity. An operation port is provided at the bottom end of the outer box body corresponding to the intermediate drainage cavity. Overflow ports are respectively provided on the side walls of the central water tank corresponding to the fresh water tank and the salt water tank.

[0017] Preferably, sealing gaskets are provided at the tops of the two partitions, and the inner box body is placed on the two partitions;

[0018] Or sealing gaskets are provided at the tops of the two partitions, and the inner box body is connected to the two partitions by screws;

[0019] Or the inner box body is connected to the two partitions by an adhesive.

[0020] Preferably, second drainage ports are respectively provided at the bottom ends of the outer box body corresponding to the fresh water overflow cavity and the bottom end of the outer box body corresponding to the salt water overflow cavity.

[0021] Preferably, the fresh water level control component and the salt water level control component have the same structure and both include:

[0022] A water storage tank is connected to the inner box body by a water inlet pipe, and the water storage tank is connected to the outer box body by a water return pipe. The connection between the water return pipe and the outer box body is arranged near the bottom end of the outer box body.

[0023] A water pump is connected to the water inlet pipe.

[0024] A switching valve is connected to the water return pipe.

[0025] By the above technical solutions, the utility model has the following technical effects:

[0026] ① A water-blocking partition and a water-permeable partition are provided. When filling the middle sand chamber with gravel, the water-blocking partition can play a role in blocking water, preventing fresh water and salt water from entering the middle sand chamber, avoiding seawater intrusion when the gravel filling is not completed and the aquifer has not been formed, ensuring the accuracy of the experiment. After the preparation is completed, the water-blocking partition is removed to cause seawater intrusion and simulate the real seawater intrusion process.

[0027] ② The karst pipeline is simulated by setting a transparent pipeline, and the specific shape of the transparent pipeline is reduced in proportion according to the shape of the karst pipeline detected on the spot, making it closer to the karst stratum environment, ensuring that the simulation process is more accurate, providing more approximate and real data for seawater intrusion into the karst stratum, and having more reference value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is the front view of the utility model;

[0029] Figure 2 is the front view with the overflow port arranged on the side wall of the inner box body;

[0030] Figure 3 is the top view of the outer box body.

[0031] In the figure, 1. Central water tank, 2. Water-permeable partition, 3. Fresh water chamber, 4. Middle sand chamber, 5. Salt water chamber, 6. First drain port, 7. Transparent pipeline, 8. Water-blocking partition, 9. Installation groove, 10. Sealing strip, 11. Overflow port, 12. Salt water overflow cavity, 13. Sealing gasket, 14. Partition, 15. Middle drain cavity, 16. Water-blocking base, 17. Second drain port, 18. Fresh water overflow cavity, 19. Fresh water level control component, 20. Operation port;

[0032] 101. Inner box body, 102. Outer box body;

[0033] 201. Porous partition, 202. Geotextile;

[0034] 1901. Water inlet pipe, 1902. Water pump, 1903. Switching valve, 1904. Water return pipe, 1905. Water storage tank. DETAILED DESCRIPTION OF THE INVENTION

[0035] To clearly illustrate the technical features of this solution, the following will elaborate on the present utility model in detail through specific embodiments and in conjunction with the accompanying drawings.

[0036] In addition, in the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationships shown in the accompanying drawings. These are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0037] As Figures 1 - 3 shown, an experimental device for simulating seawater intrusion into a karst aquifer includes a central water tank 1. The water tank is made of plexiglass, which facilitates observing the seawater intrusion process inside and the seawater-freshwater interface after the intrusion reaches equilibrium. Two permeable partition plates 2 are provided inside the central water tank 1. The permeable partition plates 2 are bonded with waterproof glue or connected by screws. The permeable partition plates 2 ensure water permeability but prevent sand from passing through, avoiding sand and gravel from entering the fresh water and seawater on both sides during the seawater intrusion process. The two permeable partition plates 2 are arranged at intervals from left to right (the left-right direction is the length direction of the central water tank 1). The two permeable partition plates 2 divide the central water tank 1 into a fresh water chamber 3, an intermediate sand chamber 4, and a salt water chamber 5 from left to right in sequence. A certain water level of fresh water is injected into the fresh water chamber 3. Quartz sand is filled in the intermediate sand chamber 4. When filling, it is filled in layers and continuously compacted to try to restore the true porosity and permeability. A certain water level of salt water is injected into the salt water chamber 5. The salt water is a NaCl solution with a concentration of 36 g / L, and a little carmine is added for coloring, which is convenient for observing the seawater intrusion interface. After starting the experiment, after the red salt water body stops moving, record the position where the salt water body meets the fresh water body, which is the position where the seawater intrudes into the aquifer. At the bottom of the central water tank 1, first drainage ports 6 are respectively provided corresponding to the fresh water chamber 3, the intermediate sand chamber 4, and the salt water chamber 5, which are used to drain the water after the simulation experiment is completed.

[0038] It also includes two water-blocking partition plates 8. One water-blocking partition plate 8 is arranged on the left side of one of the permeable partition plates 2, and the other water-blocking partition plate 8 is arranged on the right side of the other permeable partition plate 2. The water-blocking partition plates 8 are impermeable. Their main function is to prevent fresh and salt water from entering the intermediate sand chamber 4 when filling quartz sand into the intermediate sand chamber 4, avoiding seawater intrusion before the sand and gravel filling is completed and the aquifer has not been formed yet, and ensuring the accuracy and authenticity of the seawater intrusion simulation. After the preparation work is completed and the intrusion experiment starts, pull out the water-blocking partition plates 8, and the salt water will start to move towards the fresh water side. The water-blocking partition plates 8 are still made of plexiglass plates, which facilitates observing the internal situation of the intermediate sand chamber 4.

[0039] It further includes a transparent pipeline 7. For the convenience of observation, the transparent pipeline 7 is also made of plexiglass tube. The transparent pipeline 7 is arranged in the middle sand chamber 4 and buried in the sand layer of the middle sand chamber 4. According to the actual formation conditions and the shape of the karst pipeline (such as single pipeline, multi-pipeline intersection, etc.), the placement form (such as horizontal, inclined, etc.), the height relative to the sand layer, and the diameter size, etc. of the transparent pipeline 7 are arranged. In this application, one of the shapes of the karst pipeline is taken as an example for illustration (and also drawn in the attached drawings). The left and right ends of the two ends of the transparent pipeline 7 (the transparent pipeline 7 of this application has three ports, one port at the left end and two ports at the right end. According to other actual terrain conditions, more above-mentioned ports can also be set) correspondingly abut against the inner side walls of the two water-permeable partitions 2. The transparent pipeline 7 simulates the karst pipeline. When seawater intrusion occurs, the salt-fresh water interface in the karst pipeline can reach the equilibrium position preferentially.

[0040] It further includes a fresh water level control component 19 and a salt water level control component. The fresh water level control component 19 is communicated with the fresh water tank 3 and is used to control the fresh water level in the fresh water tank 3 to remain unchanged during the process of seawater intrusion. Similarly, the salt water level control component is communicated with the salt water tank 5 and is used to control the salt water level in the salt water tank 5 to remain unchanged during the process of seawater intrusion. Only by keeping the water levels of both unchanged during the process of seawater intrusion can it be ensured that the seawater intrusion reaches an equilibrium position, can the real process of seawater intrusion be simulated, and a part of the aquifer is invaded and finally reaches equilibrium. By analyzing the salt-fresh water interface, the position and degree of the actual seawater intrusion into the karst aquifer can be obtained in advance, providing reference data for the actual prevention and control of seawater intrusion. Otherwise, the salt-fresh water interface will change continuously and cannot reach the equilibrium position, which does not conform to the actual situation and loses the significance of simulation.

[0041] After the seawater intrusion experiment under the fresh water level is completed, the initial set water level in the fresh water tank 3 can be changed to carry out the seawater intrusion experiments under different scenarios.

[0042] Furthermore, the specific implementation form of the water-permeable and sand-proof of the above-mentioned water-permeable partition 2 is that the water-permeable partition 2 includes a porous partition 201 and a geotextile 202. A water-blocking base 16 is provided at the bottom of the central water tank 1. The water-blocking base 16 can be set in an integrated form with the central water tank 1 to ensure the sealing performance. The porous partition 201 is vertically arranged on the water-blocking base 16.

[0043] Furthermore, the water-blocking partition 8 is vertically arranged on the water-blocking base 16. The height of the water-blocking partition 8 is not less than the height of the water-permeable partition 2. The connection between the water-blocking partition 8 and the inner wall of the central water tank 1 and with the water-blocking base 16 is a sealed connection to prevent salt water and fresh water from entering the middle sand chamber 4 from this connection.

[0044] Further, for the above-mentioned sealed connection method, specifically, installation grooves 9 are provided on the inner wall of the central water tank 1 corresponding to the connection of the water-blocking partition 8 and the water-blocking base 16. The installation grooves 9 are strip-shaped, and sealing strips 10 are provided in the installation grooves 9. The sealing strips 10 can be made of materials such as rubber or silica gel.

[0045] Further, in order to keep the saltwater level and the freshwater level constant, the present application sets the above-mentioned central water tank 1 in the following form, which specifically includes an inner box body 101 and an outer box body 102. Two partitions 14 are provided at intervals on the left and right of the bottom of the outer box body 102 (in the length direction of the central water tank 1). The two partitions 14 and the outer box body 102 adopt an integrated structure form to ensure tightness. The space between the inner box body 101 and the outer box body 102 is sequentially divided into a freshwater overflow chamber 18, an intermediate drainage chamber 15, and a saltwater overflow chamber 12 from left to right by the two partitions 14. The first drain openings 6 are provided on the inner box body 101, and the three first drain openings 6 correspond to the freshwater overflow chamber 18, the intermediate drainage chamber 15, and the saltwater overflow chamber 12. That is, the freshwater in the freshwater bin 3 can flow into the freshwater overflow chamber 18 through the first drain openings 6, the water in the intermediate sand chamber 4 can flow into the intermediate drainage chamber 15 through the first drain openings 6, and the saltwater in the saltwater bin 5 can flow into the saltwater overflow chamber 12 through the first drain openings 6. An operation port 20 is provided at the bottom end of the outer box body 102 corresponding to the intermediate drainage chamber 15. Through this operation port 20, the staff can unplug or block the first drain openings 6. Overflow openings 11 are respectively provided on the side walls of the central water tank 1 corresponding to the freshwater bin 3 and the side walls corresponding to the saltwater bin 5. The height of the overflow openings 11 is set according to the freshwater level and the saltwater level. Of course, if necessary, a plurality of vertically spaced overflow openings 11 can also be provided on the inner box body 101 corresponding to the freshwater bin 3 and the saltwater bin 5. When higher-level fresh and saltwater are required, the lower overflow openings 11 can be blocked by existing methods.

[0046] Further, sealing gaskets 13 are provided at the tops of the two partitions 14. The sealing gaskets 13 are preferably silica gel gaskets. The silica gel gaskets have better softness and larger deformation, can increase the contact surface with the inner box body 101, and improve the sealing effect. The inner box body 101 is placed on the two partitions 14, and the self-weight of the inner box body 101 presses down on the sealing gaskets 13, causing them to deform and seal. After the inner box body 101 is placed on the two partitions 14, the freshwater overflow chamber 18, the intermediate drainage chamber 15, and the saltwater overflow chamber 12 of the outer box body 102 form non-communicating cavities, providing a basis for the water level control and circulation of fresh and saltwater. At the same time, this structural form allows the inner box body 101 to be taken out separately after the experiment, and experiments can still be carried out when it is connected to other water level control components.

[0047] Alternatively, the above-mentioned inner box body 101 and the two partition plates 14 can also be connected in the following way, that is, sealing gaskets 13 are provided at the tops of the two partition plates 14, and the inner box body 101 and the two partition plates 14 are connected by screws;

[0048] Or, the inner box body 101 and the two partition plates 14 can also be connected by adhesive.

[0049] Furthermore, after the experiment is completed, in addition to draining the water inside by manually pouring the outer box body 102, second drain ports 17 are respectively provided at the bottom of the outer box body 102 corresponding to the fresh water overflow chamber 18 and at the bottom of the outer box body 102 corresponding to the salt water overflow chamber 12. When it is necessary to drain the water in the salt water, fresh water and the middle sand chamber 4 after the experiment is completed, just open the first drain port 6 and the second drain port 17.

[0050] Furthermore, the above-mentioned fresh water level control component 19 and the salt water level control component have the same structure, and both of them include:

[0051] A water storage tank 1905, a water inlet pipe 1901 is connected between the water storage tank 1905 and the inner box body 101, a water pump 1902 is connected to the water inlet pipe 1901, the water inlet pipe 1901 is preferably inserted into the bottom of the water storage tank 1905, a water return pipe 1904 is connected between the water storage tank 1905 and the outer box body 102, a switching valve 1903 is connected to the water return pipe 1904, and the connection between the water return pipe 1904 and the outer box body 102 is arranged close to the bottom end of the outer box body 102. The water pump 1902 pumps the salt water and fresh water in the water storage tank 1905 into the salt water tank and the fresh water tank. When the water levels of the salt water and fresh water reach their respective overflow ports 11, they overflow into the salt water overflow chamber 12 and the fresh water overflow chamber 18, and open the switching valve 1903 to flow back into their respective water storage tanks 1905 through the return pipe.

[0052] It should be noted that in order to keep the water levels of the salt water and fresh water unchanged during the simulation of seawater intrusion, therefore, during the whole process, the water pump 1902 needs to keep working to continuously circulate the salt water and fresh water to keep the water levels unchanged.

[0053] The specific simulation process of this application is as follows: First, clarify the shape of the karst pipeline to be simulated, and according to the principle of equal proportion reduction, customize a transparent pipeline 7 and place it in the middle sand chamber 4 of the central water tank 1. Fill the middle sand chamber 4 with sand and gravel in layers, and compact it with an acrylic board every 10 cm of filling. Stop filling after filling to a certain height.

[0054] Secondly, configure the solution in the salt water chamber 5, and its concentration is a NaCl solution of 36 g / L, and add a little carmine for staining.

[0055] Secondly, pump the fresh water in the water storage tank 1905 into the fresh water chamber 3, and pump the salt water (NaCl solution) in the water storage tank 1905 into the salt water chamber 5. The water pump 1902 keeps working to always maintain a certain water level in the fresh water chamber 3 and the salt water chamber 5.

[0056] Secondly, remove the water blocking partition 8 to simulate the process of seawater intrusion. After the carmine-colored salt water body stops moving, record the position of the boundary between the salt water body and the fresh water body, which is the position where the seawater intrudes into the aquifer.

[0057] Finally, after the simulation is completed, open the first drain port 6, the second drain port 17 and the operation port 20 to drain the water in the intermediate sand chamber 4, the fresh water in the fresh water chamber 3, and the salt water in the salt water chamber 5.

[0058] As needed, change the water levels in the fresh water chamber 3 and the salt water chamber 5 by setting the heights of different overflow ports 11 (when a higher-position overflow port 11 is needed, the lower-position overflow port 11 can be blocked with a blocking component). Repeating the above simulation process can conduct seawater intrusion tests under different scenarios.

[0059] The above specific implementation manners cannot be used as a limitation on the protection scope of the present utility model. For those skilled in the art of this technology, any alternative improvement or transformation made to the implementation manners of the present utility model falls within the protection scope of the present utility model.

[0060] Where the present utility model is not described in detail are all well-known technologies to those skilled in the art of this technology.

Claims

1. An experimental device for simulating seawater intrusion into a karst aquifer, characterized in that, Comprising: A central water tank, within which there are two water-permeable partitions. The two water-permeable partitions divide the central water tank into a fresh water compartment, an intermediate sand chamber, and a salt water compartment. At the bottom of the central water tank, there are first drain outlets corresponding to the fresh water compartment, the intermediate sand chamber, and the salt water compartment respectively; Two water-blocking partitions, one of the water-blocking partitions is arranged on one side of one of the water-permeable partitions close to the fresh water compartment, and the other water-blocking partition is arranged on one side of the other water-permeable partition close to the salt water compartment; A transparent pipe, which is arranged in the intermediate sand chamber and buried in the sand layer of the intermediate sand chamber. The two ends of the transparent pipe are respectively abutted against the inner side walls of the two water-permeable partitions; A fresh water level control component, which is communicated with the fresh water compartment and is used to control the stable fresh water level in the fresh water compartment; A salt water level control component, which is communicated with the salt water compartment and is used to control the stable salt water level in the salt water compartment.

2. The experimental device for simulating seawater intrusion into a karst aquifer according to claim 1, characterized in that, Each of the water-permeable partitions includes a porous partition and a geotextile. There is a water-blocking base at the bottom of the central water tank, and the porous partition is vertically arranged on the water-blocking base.

3. An experimental device for simulating seawater intrusion into a karst aquifer according to claim 2, characterized in that, The water-blocking partition is vertically arranged on the water-blocking base, and the connection between the water-blocking partition and the inner wall of the central water tank and between the water-blocking partition and the water-blocking base is a sealed connection.

4. An experimental device for simulating seawater intrusion into a karst aquifer according to claim 3, characterized in that, On the inner wall of the central water tank corresponding to the connection of the water-blocking partition and on the water-blocking base, there are installation grooves, and sealing strips are arranged in the installation grooves.

5. The experimental device for simulating seawater intrusion into a karst aquifer according to claim 1, characterized in that, The transparent pipe is made of an acrylic pipe.

6. The experimental device for simulating seawater intrusion into a karst aquifer according to claim 1 or 5, characterized in that, Both the water-blocking partition and the central water tank are made of acrylic plate material.

7. An experimental device for simulating seawater intrusion into a karst aquifer according to claim 1, characterized in that, The central water tank includes an inner box body and an outer box body. Along the length direction of the bottom of the outer box body, there are two partitions at intervals. The two partitions divide the space between the inner box body and the outer box body into a fresh water overflow cavity, an intermediate drainage cavity, and a salt water overflow cavity. The first drain outlet is arranged on the inner box body. The three first drain outlets correspond to the fresh water overflow cavity, the intermediate drainage cavity, and the salt water overflow cavity. At the bottom end of the outer box body corresponding to the intermediate drainage cavity, there is an operation port. On the side wall of the central water tank corresponding to the fresh water compartment and on the side wall corresponding to the salt water compartment, there are overflow ports respectively.

8. An experimental device for simulating seawater intrusion into a karst aquifer according to claim 7, characterized in that, There are sealing gaskets at the tops of the two partitions, and the inner box body is placed on the two partitions; Or there are sealing gaskets at the tops of the two partitions, and the inner box body is connected to the two partitions by screws; Or the inner box body is connected to the two partitions by an adhesive.

9. An experimental device for simulating seawater intrusion into a karst aquifer according to claim 7 or 8, characterized in that, At the bottom end of the outer box body corresponding to the fresh water overflow cavity and at the bottom end of the outer box body corresponding to the salt water overflow cavity, there are second drain outlets respectively.

10. An experimental device for simulating seawater intrusion into a karst aquifer according to claim 7, characterized in that, The fresh water level control component and the salt water level control component have the same structure, and both include: A storage water tank, there is a water inlet pipe connecting the storage water tank and the inner box body, and there is a return pipe connecting the storage water tank and the outer box body. The connection between the return pipe and the outer box body is arranged close to the bottom end of the outer box body; A water pump, which is connected to the water inlet pipe; A switch valve, which is connected to the return pipe.

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