阅读说明：本技术 一种冷冻侧制冷结构、制冷系统及其控制方法 (Refrigeration side refrigeration structure, refrigeration system and control method of refrigeration side refrigeration structure ) 是由 李宏波 隋红亮 王升 刘国林 刘昊 于 2021-08-26 设计创作，主要内容包括：本发明提供了一种冷冻侧制冷结构、制冷系统及其控制方法,涉及制冷设备技术领域,解决了建筑冷负荷变化较大、较快时,制冷系统加、减机控制需要反应时间,造成系统运行不稳,室温出现较大起伏的技术问题。该冷冻侧制冷结构在冷冻供水总管路加设冷冻供水罐,冷冻回水总管路加设冷冻回水罐,结合阀门组件和水泵组件的控制,可以在开机过程利用支路循环起到低温、稳定供冷的作用；在建筑冷负荷变化较大、较快,而机组无法快速加减机控制反应时,可以起到缓冲、蓄冷的作用,来保证一些控制要求较高建筑达到稳定、高效、低温的供冷。解决常规空调系统机组加减机控制时无法快速控制流量、水温等因素,造成系统运行不稳、室温失控等问题。(The invention provides a refrigeration structure on a refrigeration side, a refrigeration system and a control method thereof, relates to the technical field of refrigeration equipment, and solves the technical problems that when the change of a building cold load is large and quick, the control of an adding machine and a subtracting machine of the refrigeration system needs reaction time, the system is unstable in operation, and the room temperature fluctuates greatly. The freezing side refrigeration structure is additionally provided with a freezing water supply tank on a freezing water supply main pipeline, a freezing water return tank on a freezing water return main pipeline, and the freezing side refrigeration structure can utilize branch circulation to play a role in low temperature and stable cold supply in the starting process by combining the control of a valve component and a water pump component; when the building cold load changes greatly and quickly and the unit cannot quickly control the reaction by adding or subtracting, the cold supply system can play the roles of buffering and cold accumulation, thereby ensuring that some buildings with higher control requirements achieve stable, efficient and low-temperature cold supply. The problems of unstable system operation, out-of-control room temperature and the like caused by the fact that the flow, the water temperature and other factors cannot be quickly controlled during control of the conventional air conditioning system unit plus-minus machine are solved.)

1. A freezing side refrigeration structure is characterized by comprising a water pump assembly, a valve assembly, a water chilling unit, a freezing water supply pipeline and a freezing water return pipeline, wherein the freezing water supply pipeline is internally provided with a freezing water supply tank, and the freezing water return pipeline is internally provided with a freezing water return tank;

the refrigerating side refrigerating structure is provided with an overflow structure and is used for adjusting the supply and demand balance of the refrigerated water.

2. The freezing-side refrigeration structure according to claim 1, wherein the freezing water supply tank is installed at a higher position than the freezing water return tank, and an overflow pipe is provided between the freezing water supply tank and the freezing water return tank to form the overflow structure.

3. The freezing-side refrigeration structure according to claim 2, wherein the volume of the freezing water returning tank is larger than the volume of the freezing water supply tank.

4. The refrigeration side structure as claimed in claim 1, wherein the freezing water supply pipeline comprises a buffering branch and a main cooling supply pipeline connected in parallel, a first end of the buffering branch is communicated with the water chilling unit, and a second end of the buffering branch is communicated with the freezing water return tank; the freezing water supply tank is located in the main cooling supply path, the first end of the main cooling supply path is communicated with the water chilling unit, and the second end of the main cooling supply path is communicated with the cold terminal.

5. The freezing side refrigeration structure of claim 4, wherein the valve assembly includes a bypass valve disposed in the buffer bypass and a main valve disposed in the main cooling path between the chiller and the frozen water supply tank.

6. The chilled side refrigeration structure of claim 5, wherein the main circuit valve includes a plurality of butterfly valves and the bypass valve is a pressure balancing valve.

7. The refrigeration side structure according to claim 4, further comprising a bypass line, one end of which is communicated with the main cooling supply path between the freezing water supply tank and the cold end, and the other end of which is communicated with the freezing water return tank; and a bypass valve is arranged in the bypass pipeline.

8. The freezing-side refrigeration structure according to claim 1, wherein a connection pipe is provided between the freezing water supply tank and the freezing water return tank, and a communication valve is provided in the connection pipe.

9. The freezer-side refrigeration structure of claim 1, further comprising a detection device comprising a freezer tank water temperature monitoring device.

10. The refrigeration side structure as claimed in any one of claims 1 to 9, further comprising a water replenishing and purifying device communicated with the freezing return water tank through a pipeline.

11. The chilled-side refrigeration structure according to claim 10, wherein the chilled water supply tank and the chilled water return tank are each provided with a drain.

12. A refrigeration system for cryogenic refrigeration of a building comprising a cold side and a cold side, wherein the cold side employs a cold side refrigeration structure according to any one of claims 1 to 11.

13. The refrigeration system as recited in claim 12 wherein the cooling tower on the cooling side is in communication with the chilled water supply tank via a conduit and a transfer pump is disposed in the conduit.

14. A control method for a refrigerating system as recited in claim 12 or 13, comprising a power-on control step, a normal cooling step, and an up-down cooling step.

15. The control method according to claim 14, wherein the power-on control step includes: the valve component and the water pump component are controlled to enable the water chilling unit and the freezing backwater tank to be connected in series for circulation, so that zero hot water cooling during starting is achieved, the outlet temperature of the water chilling unit quickly meets the cooling requirement, and the water in the freezing backwater tank is cooled.

16. The control method according to claim 15, wherein the regular cooling is entered when the temperature of the water in the freezing return tank reaches the cooling design temperature, and the regular cooling step comprises: and the valve assembly and the water pump assembly are controlled to enable the water chilling unit, the freezing water supply tank and the freezing water return tank to be connected in series for circulation, so that refrigeration and water storage of the freezing water supply tank and the freezing water return tank are realized.

17. The control method according to claim 16, characterized in that, when the system cooling load changes, the step of cooling by the adding and subtracting machine is entered;

when needing to add the machine:

s11, adding a machine set to perform the starting control step, wherein the increased demand of the system is provided by low-temperature cold water stored in a freezing water supply tank;

s12, after the water temperature of the freezing water return tank reaches the design temperature of cooling, the chilled water of the newly added unit is converged into a main cooling main road for conventional cooling;

when the machine needs to be reduced, the reduced demand of the system stores cold water by the freezing water supply tank to achieve the buffering effect.

Technical Field

The invention relates to the technical field of refrigeration equipment, in particular to a refrigeration structure at a freezing side, a refrigeration system and a control method of the refrigeration system.

Background

At present, when the cold load of a building is changed greatly and fast in a conventional refrigerating system, the unit addition and subtraction control needs reaction time, so that the chilled water supply and return water temperature and the chilled water flow of the system fluctuate greatly within a period of time, the system is unstable in operation, and the room temperature fluctuates. This obviously does not satisfy some buildings with higher control requirements. Meanwhile, the design of the conventional cooling system adopts a closed mode of direct pipeline connection of a freezing side, a cooling side and a tail end system, water quality in the whole operation process cannot be controlled at any time, a water channel is easily blocked for a long time, and the actual operation flow of the system is small, so that the operation energy efficiency of the system is influenced, and meanwhile, units, equipment, valves and the like are easily damaged, and economic loss is caused.

Disclosure of Invention

The invention aims to provide a refrigeration side structure, a refrigeration system and a control method thereof, which at least solve the technical problems that the operation of the system is unstable and the room temperature fluctuates greatly due to the fact that the control of the addition and subtraction of the refrigeration system needs reaction time when the change of the cold load of a building is large and quick in the prior art. The technical effects that can be produced by the preferred technical scheme in the technical schemes provided by the invention are described in detail in the following.

In order to achieve the purpose, the invention provides the following technical scheme:

the invention provides a freezing side refrigerating structure which comprises a water pump assembly, a valve assembly, a water chilling unit, a freezing water supply pipeline and a freezing water return pipeline, wherein the freezing water supply pipeline and the freezing water return pipeline are communicated with the water chilling unit;

the refrigerating side refrigerating structure is provided with an overflow structure and is used for adjusting the supply and demand balance of the refrigerated water.

Optionally, the freezing water supply tank is installed at a position higher than the freezing water return tank, and an overflow pipe is disposed between the freezing water supply tank and the freezing water return tank to form the overflow structure.

Optionally, the volume of the freeze water return tank is greater than the volume of the freeze water supply tank.

Optionally, the freezing water supply line includes a buffering branch line and a main cooling supply line connected in parallel, a first end of the buffering branch line is communicated with the water chilling unit, and a second end of the buffering branch line is communicated with the freezing water return tank; the freezing water supply tank is located in the main cooling supply path, the first end of the main cooling supply path is communicated with the water chilling unit, and the second end of the main cooling supply path is communicated with the cold terminal.

Optionally, the valve assembly comprises a bypass valve disposed in the buffer bypass and a main valve disposed in the main cooling path between the chiller and the chilled water supply tank.

Optionally, the main circuit valve comprises a plurality of butterfly valves and the branch circuit valve is a pressure balance valve.

Optionally, the refrigeration structure on the freezing side further comprises a bypass pipeline, one end of the bypass pipeline is communicated with the main cooling supply path between the freezing water supply tank and the cold using terminal, and the other end of the bypass pipeline is communicated with the freezing water return tank; and a bypass valve is arranged in the bypass pipeline.

Optionally, a connection pipe is provided between the freezing water supply tank and the freezing water return tank, and a communication valve is provided in the connection pipe.

Optionally, an overflow pipe is provided between the chilled water supply tank and the chilled water return tank.

Optionally, the refrigeration structure on the freezing side further comprises a detection device, and the detection device comprises a freezing tank water temperature monitoring device.

Optionally, the refrigeration structure on the freezing side further comprises a water replenishing and purifying device which is communicated with the freezing water return tank through a pipeline.

Optionally, the chilled water supply tank and the chilled water return tank are each provided with a waste fitting.

The invention provides a refrigerating system for low-temperature refrigeration of buildings, which comprises a freezing side and a cooling side, wherein the freezing side adopts any one of the freezing side refrigerating structures.

Optionally, the cooling tower on the cooling side is communicated with the chilled water supply tank through a pipeline, and a delivery pump is arranged in the pipeline.

The control method of the refrigeration system provided by the invention comprises a starting control step, a conventional cooling step and an adding and subtracting cooling step.

Optionally, the boot-up controlling step includes: the valve component and the water pump component are controlled to enable the water chilling unit and the freezing backwater tank to be connected in series for circulation, so that zero hot water cooling during starting is achieved, the outlet temperature of the water chilling unit quickly meets the cooling requirement, and the water in the freezing backwater tank is cooled.

Optionally, entering normal cooling when the temperature of the water in the freezing backwater tank reaches the cooling design temperature, wherein the normal cooling step comprises: and the valve assembly and the water pump assembly are controlled to enable the water chilling unit, the freezing water supply tank and the freezing water return tank to be connected in series for circulation, so that refrigeration and water storage of the freezing water supply tank and the freezing water return tank are realized.

Optionally, entering a cooling step of an adding and subtracting machine when the cooling load of the system changes;

when needing to add the machine:

s11, adding a machine set to perform the starting control step, wherein the increased demand of the system is provided by low-temperature cold water stored in a freezing water supply tank;

s12, after the water temperature of the freezing water return tank reaches the design temperature of cooling, the chilled water of the newly added unit is converged into a main cooling main road for conventional cooling;

when the machine needs to be reduced, the reduced demand of the system stores cold water by the freezing water supply tank to achieve the buffering effect.

The invention provides a freezing side refrigeration structure, a refrigeration system and a control method thereof, wherein the freezing side refrigeration structure is additionally provided with a freezing water supply tank on a freezing water supply main pipeline, and a freezing water return tank on a freezing water return main pipeline, and can play a role in low temperature and stable cold supply by utilizing branch circulation in the starting process by combining the control of a valve component and a water pump component; when the building cold load changes greatly and quickly and the unit cannot quickly control the reaction by adding or subtracting, the cold supply system can play the roles of buffering and cold accumulation, thereby ensuring that some buildings with higher control requirements achieve stable, efficient and low-temperature cold supply. The problems of unstable system operation, out-of-control room temperature and the like caused by the fact that the flow, the water temperature and other factors cannot be quickly controlled during control of the conventional air conditioning system unit plus-minus machine are solved. Due to the overflow structure, the supply and demand balance of chilled water can be adjusted, the problem that the chilled water of the freezing water supply tank is too much and cannot be discharged in the running process of the system is solved, and the running stability of the system is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a refrigeration system according to an embodiment of the present invention;

FIG. 2 is a schematic view of a circulation path of cold water in the refrigeration structure on the freezing side when the refrigerator is operated at start-up, in which solid arrows show the flow direction of supply water and hollow arrows show the flow direction of return water;

FIG. 3 is a schematic view showing a circulation path of cold water in a conventional cooling state, in which solid arrows show a flow direction of supply water and hollow arrows show a flow direction of return water;

FIG. 4 is a schematic view showing a circulation path of cold water during operation of the charging machine, in which solid arrows show a flow direction of supply water and hollow arrows show a flow direction of return water;

fig. 5 is a schematic structural view of the freeze water return tank and the freeze water supply tank.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.

The invention provides a freezing side refrigerating structure which comprises a water pump assembly, a valve assembly, a water chilling unit, a freezing water supply pipeline and a freezing water return pipeline, wherein the freezing water supply pipeline and the freezing water return pipeline are communicated with the water chilling unit; the refrigerating side refrigerating structure is provided with an overflow structure and is used for adjusting the supply and demand balance of the refrigerated water.

The freezing side refrigeration structure is additionally provided with a freezing water supply tank on a freezing water supply main pipeline, a freezing water return tank on a freezing water return main pipeline, and the freezing side refrigeration structure can utilize branch circulation to play a role in low temperature and stable cold supply in the starting process by combining the control of a valve component and a water pump component; when the building cold load changes greatly and quickly and the unit cannot quickly control the reaction by adding or subtracting, the cold supply system can play the roles of buffering and cold accumulation, thereby ensuring that some buildings with higher control requirements achieve stable, efficient and low-temperature cold supply. The problems of unstable system operation, out-of-control room temperature and the like caused by the fact that the flow, the water temperature and other factors cannot be quickly controlled during control of the conventional air conditioning system unit plus-minus machine are solved. And owing to have overflow structure, can adjust the supply and demand balance of refrigerated water, prevent the too much unable problem of discharging of refrigerated water supply tank refrigerated water at system operation in-process, improved the operating stability of system.

As an optional embodiment, the freezing water supply pipeline comprises a buffering branch and a main cooling supply pipeline which are connected in parallel, a first end of the buffering branch is communicated with the water chilling unit, and a second end of the buffering branch is communicated with the freezing water return tank; the freezing water supply tank is located in the main cooling supply path, the first end of the main cooling supply path is communicated with the water chilling unit, and the second end of the main cooling supply path is communicated with the cold terminal.

As an alternative embodiment, the valve assembly includes a branch valve provided in the buffering branch and a main valve provided in the main cooling supply path between the water chilling unit and the freezing water supply tank.

As an optional implementation mode, the main path valve comprises a plurality of electric butterfly valves, and the electric butterfly valves are conveniently controlled according to the temperature of the chilled water of the system to select different circulation paths; the branch valve is a pressure balance valve.

As an optional implementation mode, the refrigeration structure at the freezing side further comprises a bypass pipeline, one end of the bypass pipeline is communicated with the main cooling supply path between the freezing water supply tank and the cold using terminal, and the other end of the bypass pipeline is communicated with the freezing water return tank; and a bypass valve is arranged in the bypass pipeline. When the water flow is suddenly increased, the redundant cold water flows to the freezing water return tank through the bypass pipeline for buffering.

As an alternative embodiment, a connection pipe is provided between the freezing water supply tank and the freezing water return tank, and a communication valve is provided in the connection pipe.

As an alternative embodiment, an overflow pipe is provided between the frozen water supply tank and the frozen water return tank.

As an optional embodiment, the refrigeration side structure further comprises a detection device, and the detection device comprises a freezing tank water temperature monitoring device. The valve and the water pump are controlled by monitoring the water temperature, so that the purpose of stable low-temperature refrigeration of the system is achieved.

As an optional implementation mode, the freezing side refrigeration structure further comprises a water replenishing and purifying device which is communicated with the freezing water returning tank through a pipeline. Is beneficial to the full utilization of cold water.

As an alternative embodiment, both the chilled water supply tank and the chilled water return tank are provided with a sewage drain.

Conventional air conditioner design system belongs to closed system, can't cause the water route to block up in real time accuse quality of water, water yield, long-time easily, and the actual operation flow of system is less, influences the system operation efficiency, simultaneously, causes damages such as unit, equipment, valve easily, causes economic loss too big scheduling problem. The air conditioning system belongs to an open system, can flexibly overhaul the system and control the water quality and the water quantity through a water replenishing pipe and a sewage draining pipe on a freezing water return tank, fills the water quantity for the system or discharges the sewage of the system at any time, and is favorable for cleaning and maintaining the system.

The invention provides a refrigerating system for low-temperature refrigeration of buildings, which comprises a freezing side and a cooling side, wherein the freezing side adopts any one freezing side refrigerating structure.

As an alternative embodiment, the cooling tower on the cooling side communicates with the chilled water supply tank through a pipeline, and a transfer pump is provided in the pipeline.

A refrigeration system according to an embodiment of the present invention will be further described with reference to the accompanying drawings.

As shown in figure 1, the invention provides a novel double-freezing-liquid-tank refrigerating system, which comprises a water chilling unit, a water pump, a double-freezing-liquid-tank, a pipeline, a valve and the like. The freezing water supply tank is additionally arranged at the freezing water supply main pipe, and the pipeline is additionally provided with a bypass pipeline to the freezing water return tank. The freezing backwater header pipe is additionally provided with a freezing backwater tank, wherein the freezing backwater tank is additionally provided with a bypass pipe except for two freezing backwater pipes.

The water supply pipeline and the water return pipeline are provided with corresponding control valves (1-1, 1-2, 1-3, 2-1, 2-2, 2-3, 3-1, 3-2, 3-3, 3-4, 7-1 and 10-1 are electric butterfly valves, a buffer valve 9-1 is a pressure balance valve), a sensing device (comprising a temperature sensor and a pressure sensor), a water pump and the like. The water pump is divided into a first-stage water pump and a second-stage water pump, wherein the water pump (6-1) is the first-stage water pump; the water pumps (4-1, 4-2 and 4-3) are two-stage water pumps; the water pumps (5-1, 5-2 and 5-3) are cooling water pumps; the water pump (8-1) is a delivery pump.

Structure of the freezing water returning tank and the freezing water supplying tank (also called freezing double-liquid tank) referring to fig. 5, the structure of the freezing water supplying tank and the freezing water returning tank has no special requirement, the volume of the freezing water returning tank is larger than that of the freezing water supplying tank, and the position of the freezing water supplying tank is higher than that of the freezing water returning tank. The reason of design prevents that freezing water supply tank refrigerated water is too much unable discharge in system operation process, can utilize the difference in height to overflow to freezing water return tank. Meanwhile, the low-temperature chilled water can be prevented from being wasted, the chilled water overflows to the freezing water return tank, the water quantity of the system can be ensured, the cold energy of the chilled water can be fully utilized to cool the returned water, and the efficiency of the refrigerator is improved. The freezing water supply tank is provided with a freezing water supply pipe and a sewage discharge pipe device, and the freezing water return tank is provided with a freezing water return pipe, a bypass pipe, a water supplementing pipe, an overflow pipe and a sewage discharge pipe device. An upper overflow pipe and a lower connecting pipe are connected between the two tanks.

When the double-freezing liquid tank refrigerating system is initially operated, the water temperature monitoring device checks the water temperature of the freezing water supply tank:

the water temperature of the freezing water supply tank is within the range of the requirement of freezing water supply, and the water does not need to be discharged;

the water temperature of the freezing water supply tank is higher than the freezing water supply required range (the freezing water supply temperature of a conventional air-conditioning system is about 7 ℃ and the low-temperature air-conditioning system is about 2 ℃ according to the requirements of different air-conditioning systems), but is lower than the freezing return water temperature, the water of the freezing water supply tank is discharged to the freezing return water tank through a connecting pipe;

the water temperature of the freezing water supply tank is higher than the freezing backwater temperature requirement range (the freezing backwater temperature of the conventional air-conditioning system is about 12 ℃ according to the requirements of different air-conditioning systems), but is lower than the cooling water temperature, so that the water of the freezing water supply tank can be discharged to a cooling tower through a connecting pipe or directly discharged through a sewage tank according to the actual situation;

through the monitoring and the transportation of freezing water supply tank temperature, can guarantee freezing water supply temperature of freezing water supply tank, realize the make full use of cold volume of cold water and the requirement of stable cooling of system low temperature.

When the cold machine is started to operate, as shown in fig. 2, in order to ensure stable cold supply of the system at low temperature, taking a #1 cold water unit as an example, the water path operation condition of the system is to open valves 1-1, 3-2 and 3-3, close valves 2-1 and 9-1, and then connect the cold water unit and the freezing return water tank in series for circulation, so that the temperature of the frozen outlet water can reach a set value to realize the zero-hot water cold supply function during starting, and the design can meet the requirements of setting stable cold supply and cooling the water in the freezing return water tank.

When the temperature of the chilled water at the outlet of the cold machine stably reaches the designed cooling supply temperature, as shown in fig. 3, the valve 1-1 is closed, the valves 2-1 and 3-1 are opened, and at the moment, the water path of the system is formed by the serial circulation of the water chilling unit, the freezing water supply tank and the freezing water return tank, so that stable building refrigeration is carried out, and the freezing water supply tank and the freezing water return tank carry out normal water storage.

When the system needs to add or subtract machines, the cold machine adding and subtracting machine control can not be completed quickly, and the temperature of the system freezing water can not be ensured to be at low temperature, so the system can quickly react to realize the change of flow by the functions of cold water discharging and cold water storing of the freezing water supply tank and the return water tank, and the requirement of building cold quantity is ensured.

When the system needs to be added, taking the water chilling unit #2 as an example, the valve 1-2 is opened, the valve 2-2 is closed for low-temperature cooling, and the temperature set value is converged into the main road for cooling (namely, the valve 1-2 is closed, the valve 2-2 is opened, and the valve 9-1 is opened at the same time). In the machine adding process of the unit, the actual flow demand of the system is increased, the demand is provided by low-temperature cold water stored in a freezing water supply tank under the action of a primary pump (6-1), wherein under the operation frequency of a water pump, the water which cannot be carried can be directly transferred to a freezing water return tank through a bypass pipe to be stored (if the water exceeds the volume of the freezing water return tank, the water is discharged out of the system through an overflow pipe). The water quantity can be circulated back to the freezing water supply tank to be stored to reach the balance after the system is stabilized by the action of the added cold machine and the secondary pump (4-1, 4-2, 4-3). See fig. 4.

When the system needs to reduce the volume, the actual flow demand of the system is reduced, and the demand is stored with cold water by the freezing water supply tank under the action of the primary pump (6-1), so that the effects of cold accumulation and buffering are achieved. Along with the linkage action of the two-stage pumps (4-1, 4-2 and 4-3) to control the water amount of the freezing water return tank, the water storage amount of the double freezing liquid tanks can reach balance again after the system is stabilized. If the water storage capacity of the freezing water supply tank exceeds the water storage volume in the machine reduction process, water can be directly discharged to the freezing water return tank through the overflow pipe to be stored.

According to the design of the refrigeration air-conditioning system, stable and efficient cold supply can be achieved for places or cold-storage buildings with higher room temperature control requirements by combining the storage coordination of the double freezing liquid tanks and the operation of the adding and subtracting machine.

According to the invention, the freezing water supply tank is additionally arranged on the freezing water supply tank, and the freezing water return tank is additionally arranged on the freezing water return tank, so that the stable and low-temperature cold supply effect can be realized by utilizing the branch water path to operate in the starting process; when the load of the building changes greatly and quickly, the unit can not react quickly to perform the operation of adding and subtracting the machine, and the freezing water supply tank is used for storing and releasing the freezing water, so that the effects of buffering and cold accumulation are achieved, and the room temperature control requirements of the buildings for stable, low-temperature and efficient cold supply are ensured. Meanwhile, the double-liquid tank is provided with the water replenishing device, the softening device and the sewage device, so that system maintenance and control of water quality and water quantity can be performed at any time, and the system is favorably cleaned and maintained.

In the description of the invention, it is to be noted that "a plurality" means two or more unless otherwise specified; the terms "upper", "lower", "left", "right", "inner", "outer", "front", "rear", "head", "tail", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing and simplifying the description, but do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated, and thus are not to be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meaning of the above terms in the present invention can be understood as appropriate to those of ordinary skill in the art.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.