WO2020037843A1 - Air conditioner cooling water system for multi-stage cooling and cascade utilization of terminal energy - Google Patents

Abstract

An air conditioner cooling water system for multi-stage cooling and cascade utilization of terminal energy comprises: a water supply system for conveying cooling water inside an ice storage device (4) to an air conditioner terminal apparatus, and a water return system for conveying return water inside the air conditioner terminal apparatus to the ice storage device (4) for cooling. The water return system comprises: a water return pipe, and a first cooler (2) and a cooling heat exchanger (3) disposed on the water return pipe. Return water of the water return system flows through the first cooler (2) for first-level cooling, then the cooling heat exchanger (3) for second-level cooling, and finally into the ice storage device (4) for third-level cooling. The ice storage device (4) processes the return water undergoing second-level cooling into cooling water. The cooling water flows into the water supply system for re-use by the air conditioner terminal apparatus. The temperature of the return water flowing out of the first cooler (2) is less than 18°C.

Description

Air-conditioning chilled water system with multi-stage refrigeration and terminal energy step utilization Technical field

The present invention relates to the field of heating, ventilation, and air conditioning, and in particular to an air conditioning chilled water system with multi-stage refrigeration and terminal energy step utilization.

Background technique

In the traditional air-conditioning system, the requirements for the temperature and temperature difference of the chilled water supply and return water by the terminal equipment are mostly about 7/12 ° C, and the temperature difference between the supply and return water is about 5 ° C. The air-conditioning refrigeration system is usually a single-stage refrigerator system that directly provides chilled water at about 7 ° C. The ice-storage air-conditioning system has a two-stage series, that is, an ice storage tank is connected in series with a dual-mode refrigerator, and an intermediate heat exchanger is provided. Perform indirect connection to reduce the temperature of the return water of the air-conditioning system at about 12 ° C to about 7 ° C. Very few air-conditioning refrigeration systems also have a series of two-stage refrigerators, which gradually reduce the return water of the air-conditioning system at about 12 ° C to 7 ° C. Left and right, or two refrigerators in parallel, one of which is a high-temperature refrigerator, and the two refrigerators each provide frozen water of different temperatures, and then supply different end equipment through two sets of conveying systems.

Through the reverse Carnot cycle analysis, increasing the evaporation temperature of the refrigerator, that is, increasing the temperature of the chilled water supply, can improve the COP (coefficient of performance) of the refrigerator. According to statistics, each time the evaporation temperature of a refrigerator increases by 1 ° C, that is, when the temperature of the chilled water supply increases by 1 ° C (the temperature of the refrigerator's evaporation is generally about 1 ° C lower than the temperature of the frozen water supply), the COP increases by about 3% to 5% on average. This is why the COP of a high-temperature refrigerator is significantly larger than that of a conventional refrigerator.

With the development of urban construction in China, urban land resources are becoming increasingly scarce, and urban building density is increasing. In recent years, CBD (Central Business District) has been constructed all over the country as a landmark building group of the city. The buildings in the CBD are mostly large-scale commercial complexes, with many high-rises and even super-high-rises. The building density is very large, the building functions are complex and diverse, the air conditioning system has a large load, and the operation energy consumption is high. District cooling technology is widely used in CBD, but it is not difficult to find from some district cooling projects that are currently running, the comprehensive energy efficiency of some systems is not very high. The reasons include the following two points: first, because the refrigeration system has a longer operating time at part load conditions, and it is very difficult to adjust the small load operation, resulting in low energy efficiency of the refrigeration system; and second, because the energy consumption of the chilled water delivery system High, especially for long distance transportation. Of course, it also includes imperfect automatic control systems and imperfect management systems.

In recent years, in view of the advantages of light load of air conditioning system, low initial investment of the system, energy saving, comfort, and high indoor air quality, the concept of temperature and humidity independent control air conditioning system has been widely accepted and widely used. In the temperature and humidity independent control air conditioning system, two independent air conditioning systems, temperature and humidity, are used to control and adjust the indoor temperature and humidity. (1) Exhaust heat can be removed in a variety of ways. As long as the temperature of the medium is lower than room temperature, the cooling effect can be achieved. Indirect contact (radiation end, etc.) can also be used, and it can also be achieved by the flow of low-temperature air. (2) The task of removing excess humidity, removing CO2, indoor odor and other harmful gases, is achieved by replacing low-humidity, low-concentration air with room air. Since the task of dehumidification is undertaken by an independent humidity control system, the chilled water supply temperature of the sensible heat system no longer needs 7 ° C in a conventional condensing dehumidification air conditioning system, but can be raised to 16-18 ° C, which is a natural cold source. The use provides conditions, even if the conventional electric cooling method is used, the coefficient of performance of the refrigerator has been greatly improved. The waste heat elimination terminal device can adopt various forms such as radiating end, dry fan coil. Because the temperature and humidity independent control air conditioning system separates the indoor heat and humidity removal processes, it avoids the losses caused by the combined heat and humidity treatment in conventional air conditioning systems. At the same time, it can meet the changing requirements of room heat-humidity ratio, overcome the difficulty of simultaneously meeting the requirements of temperature and humidity parameters in the conventional air-conditioning system, and avoid the phenomenon that the indoor humidity is too high (or too low).

However, in the temperature and humidity independent control air conditioning system, there may be multiple forms of terminal equipment at the same time, and the required chilled water supply temperature is different, such as 14 ° C, 16 ° C, 18 ° C, or other temperatures. If a conventional refrigeration system is used, there are two solutions: (1) The refrigerating machine room provides cold water at the same temperature, and then multiple heat exchangers are added in the terminal equipment room to make the secondary water outlet temperature meet the needs of different end equipment. (2) Prepare cold water that meets different end equipment in the refrigerating machine room, and supply it to each end equipment through a multi-pipe network. Obviously, these two schemes have the shortcomings of high initial investment in the system, high energy consumption and cost of operation, complex system, and inconvenient regulation, control and management.

Summary of the Invention

In order to solve the above technical problems, an object of the present invention is to provide an air-conditioning chilled water system with multi-stage refrigeration and terminal energy step utilization, which adopts the form of three-stage series refrigeration to reduce the temperature of water supply.

The technical solutions to achieve the objectives of the present invention are as follows:

An air-conditioning chilled water system for multi-stage refrigeration and terminal energy cascade utilization includes: a water supply system for transferring chilled water in an ice storage device to an air-conditioning terminal device, and returning water in the air-conditioning terminal device to an ice storage device. A cooled return water system, the return water system includes a return water pipe, a first refrigerator and a refrigerating heat exchanger provided on the return water pipe, and the return water of the return water system flows through the first refrigerator in sequence. After the first-stage cooling and the second-stage cooling of the refrigerating heat exchanger, the three-stage cooling is integrated into the ice storage device. The ice-storing device processes the returned water after the second-stage cooling into frozen water, and the frozen water enters the water supply system for supply. Air conditioning end equipment is used again.

As a further improvement of the present invention, a second refrigerator is further included, and an ice storage coil is placed in the ice storage device, and the ice storage coil is in communication with the second refrigerator; the ice storage coil is immersed in the ice storage device Inside, used to freeze water in the ice storage device.

As a further improvement of the present invention, a cooling supply line and a return cooling line are provided between the ice storage coil and the second refrigerator, the ice storage coil, the cooling supply line, the return cooling line, the first A circulation circuit is formed between the two refrigerators for circulating low-temperature refrigerant;

A refrigerating heat exchanger is also connected to the supply and return cooling lines. The refrigerating heat exchanger and the ice storage device are connected in parallel. The low-temperature refrigerant flowing through the refrigerating heat exchanger and the refrigerating heat exchanger flow through the refrigerating heat exchanger. Heat exchange of the return water of the device to reduce the temperature of the return water

As a further improvement of the present invention, a connection pipeline is connected between the cooling supply pipeline and the return cooling pipeline, and a switching valve is provided on the connection pipeline.

As a further improvement of the present invention, the air-conditioning terminal equipment includes a primary cold equipment and a secondary cold equipment, and the temperature of the chilled water required by the primary cold equipment is lower than that of the secondary cold equipment. Temperature, the first-stage cold equipment and the second-stage cold equipment are connected in series, so that the chilled water flows through the first-stage cold equipment before entering the second-stage cold equipment.

As a further improvement of the present invention, a water supply side bypass pipe is also connected in parallel at both ends of the first-stage cooling equipment, and the chilled water output from the main pipe of the water supply system can be mixed with the effluent of the first-stage cooling equipment and enter the second-stage cooling equipment. Equipment for secondary cold equipment.

As a further improvement of the present invention, two ends of the secondary cooling equipment are also connected with a return water bypass pipe in parallel, and the return water of the primary cooling equipment may partially flow through the return water bypass pipe and enter the return water system supervisor. .

As a further improvement of the present invention, the first-level cold user includes a first cold user and a second cold user, and the first cold user is connected in parallel with the second cold user;

The secondary cold-use equipment includes a third cold-use user and a fourth cold-use user, and the third cold-use user is connected in parallel with the fourth cold-use user.

As a further improvement of the present invention, the return water of the first cold user and the return water of the second cold user are combined for use by the secondary cold equipment, and the return water of the third cold user and the fourth cold user are combined. After the return water is collected, it flows into the return water system.

As a further improvement of the present invention, the chilled water output from the water supply system flows into a first cold user for use by the first cold user;

The frozen water output from the water supply system is mixed with the return water of the second cold user to a temperature required by the second cold user, and then flows into the second cold user for use by the second cold user;

The return water of the first cold user and the return water of the second cold user are collected and flowed into the third cold user for use by the third cold user;

The return water of the first cold user, the return water of the second cold user, and the return water of the fourth cold user are mixed to a temperature required by the fourth cold user, and then used by the fourth cold user.

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

1. The present invention adopts a three-stage series refrigeration system. The return water of the water-cooled air-conditioning at a higher temperature flows through the first refrigerator, the refrigeration heat exchanger, and the ice storage device in this order, so that the temperature of the outlet water of the first refrigerator increases, and the first refrigerator The performance coefficient of the second refrigerator is effectively improved. Compared with the conventional refrigeration system, the performance coefficient of the three-stage series refrigeration system of the present invention is increased by more than 20%, which greatly reduces the operation energy consumption and cost of the refrigeration system;

2. The present invention adopts a series of primary cooling equipment and secondary cooling equipment in series to increase the temperature difference between the chilled water supply and the return water. The increase in the temperature difference between the supply and the return water greatly reduces the supply and return water volume. Therefore, the water-cooled air conditioner The power of the intermediate circulation pump is reduced accordingly, and the energy consumption of the entire water-cooled air conditioner is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of an air-conditioning chilled water system.

In the figure, 1. Base-load circulation pump; 2. First refrigerator; 3. Refrigeration heat exchanger; 4. Ice storage device; 5. Refrigerated water circulation pump; 6. Second refrigerator; 7. Solution circulation pump; 8. Primary cold equipment; 10, secondary cold equipment; 12, the first pressurized pump; 13, the first pressurized mixed water pump; 14, the second pressurized pump; 15, the second pressurized mixed water pump; 16, Water supply side bypass pipe; 17, return water side bypass pipe.

detailed description

The present invention will be described in detail below with reference to the embodiments shown in the drawings, but it should be noted that these embodiments are not a limitation on the present invention, and the functions, methods, or structures performed by those skilled in the art based on these embodiments Equivalent transformations or substitutions fall within the protection scope of the present invention.

In the description of this embodiment, it should be understood that the terms “center”, “portrait”, “horizontal”, “up”, “down”, “front”, “rear”, “left”, “right”, The orientations or positional relationships indicated by "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are merely for the convenience of describing the present invention. The description is created and simplified, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the creation of the invention.

In addition, the terms "first", "second", "third" and the like are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise stated, "multiple" means two or more.

The terms "installation", "connected", and "connected" should be understood in a broad sense. For example, they can be fixed, detachable, or integrally connected; they can be mechanical or electrical; they can be direct Connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the creation of the present invention can be understood through specific situations.

Example 1:

This embodiment provides an air-conditioning chilled water system with multi-stage refrigeration and terminal energy cascade utilization as shown in FIG. 1, which includes: a water supply system that transports frozen water in the ice storage device 4 to an air-conditioning terminal device, and water-cooled air conditioners. The return water in the water is sent to the return water system for cooling in the ice storage device, and the second refrigerating machine 6 that sends the refrigerant to the ice storage device 4 to complete the cooling of the frozen water in the ice storage device 4, the return water system includes: return water The pipeline, the first refrigerator 2 and the refrigerating heat exchanger 3 installed on the return water pipeline, the return water of the return water system flows through the first refrigerator in order to perform the first-level cooling, and the refrigerating heat exchanger 3 performs the second-level cooling. Three-stage temperature reduction is conducted inside the ice storage device 4. The ice storage device 4 treats the second-temperature-reduced return water into chilled water, and the chilled water enters the water supply system for reuse by the air-conditioning terminal equipment. An ice storage coil is placed in the ice storage device 4, and the ice storage coil is in communication with the second refrigerator 6; the ice storage coil is immersed in the ice storage device 4 and is used to freeze the water in the ice storage device 4 into ice. The temperature of the return water flowing out of the first refrigerator 2 is lower than 18 ° C, so that the temperature of the return water entering the second refrigerator can be guaranteed, and the operating energy consumption of the first refrigerator can be minimized, and it can also ensure that After three stages of refrigeration, the temperature of the chilled water meets the design requirements.

The return water system of this embodiment adopts the form of three-stage series refrigeration. The first stage refrigeration uses the first refrigerator 2, the second stage refrigeration uses the refrigerating heat exchanger 3, and the third stage refrigeration uses the ice storage device 4. The goal of reducing the temperature of water supply, this system can achieve 1 ~ 2 ℃ water supply.

In this embodiment, the first refrigerator 2 is a high-temperature refrigerator, which mainly functions as a base carrier and plays a first-level cooling effect on the return water of the air-conditioning system. The COP (coefficient of performance) is high, and it can also meet the low The requirements of high energy efficiency and easy control and adjustment during load (mainly at night) operation.

In this embodiment, a cooling supply line and a return cooling line are provided between the ice storage coil and the second refrigerator 6, the ice storage coil, the cooling supply line, the return cooling line, and the second refrigerator 6 A circulation loop for circulating low-temperature refrigerant is formed between them; the supply and return cooling lines are also connected with a refrigeration heat exchanger 3, and the refrigeration heat exchanger 3 and the ice storage device 4 are connected in parallel and flow through the refrigeration heat exchanger. The low-temperature refrigerant in the heat exchanger 3 performs heat exchange with the return water flowing through the refrigeration heat exchanger 3 to reduce the temperature of the return water.

In this embodiment, a connection line is connected between the cooling supply line and the return line, and a switching valve is provided on the connection line. Preferably, the switching valve is a two-way valve, and an electric two-way valve is provided on the recooling pipeline, and the electric two-way valve is located at the rear end of the connection pipeline and the recooling pipeline. In the ice storage state, the switching valve is opened and the electric two-way valve is closed, and the second refrigerator 6 only performs ice storage; in the cooling state, the electric two-way valve is opened, the switching valve is closed, and the second refrigerator 6 is for cooling.

In this embodiment, the ice storage device 4 is preferably an open-type ice storage tank. The open-type ice storage tank adopts a coiled ice storage open-type external melting method, and the return water after secondary refrigeration enters the open-type storage system through a water distributor. The ice storage tank is in direct contact with the ice stored in the open ice storage tank for heat exchange. The temperature of the frozen water outlet of the ice storage tank is close to the freezing point, usually about 1 to 2 ° C.

This embodiment adopts an open-type external melting ice direct supply method, which saves a lot of intermediate heat exchangers, soft water systems, and make-up water constant-pressure systems. Moreover, the supply and return volume of air-conditioning chilled water is greatly reduced, which makes the pipe network Compared with traditional air-conditioning water systems, the initial investment can be saved by more than 15%.

This embodiment also discloses a multi-stage series refrigeration air-conditioning chilled water method, including the following steps:

Step 1. The return water of the air-conditioning system is supplied to the air-conditioning end system after being cooled by the cooling circuit. The cooling circuit is: the fluid conveying device first sends the returned water to the first refrigerator 2 for first-stage cooling, and then enters the refrigeration heat exchanger for second-stage cooling. Cool down, and finally enter the ice storage device 4 for three-stage cooling, and supply the cooled cold water to the air-conditioning end system;

Step 2: After the ice in the ice storage device is thawed into frozen water, the frozen water is supplied to the air-conditioning terminal system through the frozen water circulation device.

After the chilled water is mixed with the return water of the air conditioning terminal system in the above step 2 and reaches the water supply temperature required by the air conditioning terminal system itself, it is supplied to the air conditioning terminal system. The air-conditioning end system includes a low-temperature user 8 and a high-temperature user 10, the low-temperature user 8 is connected in series with the high-temperature user 10, and the return water of the low-temperature user 8 and the high-temperature user 10 are mixed into a water supply temperature required by the high-temperature user 10 and supplied to the high-temperature user 10, After the return water of the high-temperature user 10 is mixed, it is cooled by three stages of the first refrigerator 2, the refrigeration heat exchanger 3, and the ice storage device 4 into chilled water, and then supplied to the low-temperature user 8 and the high-temperature user 10 again.

Example 2:

The difference from Embodiment 1 lies in that the air-conditioning chilled water system of the multi-stage refrigeration and terminal energy cascade utilization in this embodiment further includes a transmission and distribution system. The transmission and distribution system adopts a power decentralized multi-stage pump transmission and distribution system. There is a chilled water circulation pump 5, and a three-stage pump is installed in the terminal equipment room. The three-stage pump includes an end pressure pump and an end mixed water pressure pump. The functions of the three-stage pump include pressure, mixed water, and mixed water pressure. It can adjust the temperature and pressure of water supply. The end user adopts the cascade form of the primary cold equipment (low temperature users) and the secondary cold equipment (medium and high temperature users) according to the guiding ideology of energy step utilization. Of course, according to the characteristics of the system, the secondary cold equipment (medium temperature users) and the triple cold equipment (high temperature users) can be connected in series to form a three-level user series system. Adjust the water supply temperature by adjusting the water mixing ratio of the mixed water booster pump at the end (the ratio of the secondary network return water flow and the primary network water supply flow entering the mixed water pump), so as to maximize the total return water temperature of the air conditioning system . The three-stage cascade refrigeration system minimizes the temperature of the water supply. The two systems work together to maximize the temperature difference between the supply and return water and minimize the amount of water supplied to the air-conditioning chilled water.

The chilled water circulation pump 5 in the refrigerating machine room satisfies the pressure head in the machine room and the necessary external network head. It does not pass the intermediate heat exchanger, and directly sends the air-conditioned chilled water at about 1 to 2 ° C to the end equipment through a pipeline network. .

Preferably, the three-stage pump provided in the terminal equipment room includes the end pressurizing pump and the end mixed water pressurizing pump, and its functions include pressurization, mixed water and mixed water pressurization, etc., according to the end user's water supply temperature and water supply pressure. Different needs, choose different forms of water supply.

As shown in FIG. 1, the air-conditioning end equipment includes a first-stage cold equipment 8 and a second-stage cold equipment 10, and the chilled water temperature required by the first-stage cold equipment 8 is lower than that of the second-stage cold equipment 10. Water temperature, the first-stage cold equipment 8 and the second-stage cold equipment 10 are connected in series, so that the frozen water flows through the first-stage cold equipment before entering the second-stage cold equipment 10. The primary cold equipment 8 includes a first cold user and a second cold user. The first cold user is connected in parallel with the second cold user, and the chilled water output from the water supply system flows into the first cold user for the first cold user. The first cold user uses it; the chilled water output from the water supply system is mixed with the second cold user's own return water to the temperature required by the second cold user and then flows into the second cold user for the second cold user. The return water of the first cold user and the return water of the second cold user are combined and used for the secondary cold equipment. The secondary cold-use device 10 includes a third cold-use user and a fourth cold-use user. The third cold-use user is connected in parallel with the fourth cold-use user. The return water from the first cold-use user and the second cold-use user return. After the water is collected, it flows into the third cold user for use by the third cold user; the return water of the first cold user, the return water of the second cold user, and the return water of the fourth cold user are mixed into the fourth cold user. After the temperature required by the user, it is used by the fourth cold user, and the return water of the third cold user and the fourth cold user's return water are collected and flowed into the return water system.

The two ends of the first-stage cooling equipment 8 are also connected in parallel with the water supply side bypass pipe. The chilled water output from the main water supply system can be mixed with the effluent of the first-stage cooling equipment 8 and enter the second-stage cooling equipment 10 for the second stage. Use with cold equipment 10. The two ends of the secondary cooling device 10 are also connected with a return water bypass pipe 17 in parallel. The return water of the primary cooling device 8 may partially flow through the return water bypass pipe 17 and enter the return water system supervisor. The water supply side bypass line and the return water side bypass line are used to adjust the temperature and flow of the chilled water entering the secondary cold equipment 10. For example, the output temperature of the primary cooling equipment is higher than the temperature required by the secondary cooling equipment, and the bypass pipe on the water supply side needs to be filled with low temperature cold water. It is necessary to return directly from the bypass pipe on the return side to a part of the main return pipe. Both the water supply side bypass line and the return side bypass line should be provided with electric regulating valves.

The terminal equipment adopts the form of the first stage cold equipment 8 and the second stage cold equipment 10 connected in series according to the guiding idea of energy step utilization. The temperature of the chilled water supply can be adjusted by adjusting the mixing ratio of the end mixed water pressure pump. It satisfies the needs of different end users for the temperature of the chilled water supply, realizes that only one set of pipe network can be used to meet the requirements of different chilled water supply temperatures, and is widely applicable to systems with diverse requirements for chilled water supply temperature at the end equipment. Small investment and strong applicability.

As the temperature difference between the chilled water supply and the return water of the air conditioner increases, the supply and return water volume is greatly reduced, and the power of the air conditioner chilled water circulation pump 5 is reduced accordingly. Take 2 ℃ water supply and 18 ℃ return water as an example. The temperature difference is 16 ℃, Compared with the temperature difference between 5 ℃ and 7 ℃ water supply and 12 ℃ return water, the flow rate can be reduced by about 70%, which can greatly reduce the power of the main pump and greatly reduce the energy consumption of the system. Moreover, many heat exchangers and regulating valves are omitted in this system, which further reduces the power of the main pump and greatly helps to reduce the energy consumption of the system.

The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and they are not intended to limit the scope of protection of the present invention. Any equivalent implementations that do not depart from the technical spirit of the present invention or Changes should be included in the protection scope of the present invention.

It is obvious to a person skilled in the art that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, the embodiments are to be regarded as exemplary and non-limiting in every respect, and the scope of the present invention is defined by the appended claims rather than the above description, and therefore is intended to fall within the claims. All changes that are within the meaning and scope of equivalent elements are encompassed by the invention. Any reference signs in the claims should not be construed as limiting the claims involved.

In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment includes only an independent technical solution. This description of the specification is for clarity only, and those skilled in the art should take the specification as a whole. The technical solutions in the embodiments can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims (10)

A multi-stage refrigeration and air-conditioning chilled water system for terminal energy step use is characterized in that it includes: a chilled water in an ice storage device (4) to a water supply system of an air-conditioning terminal device, and a return water in the air-conditioning terminal device. A return water system that is sent to the ice storage device (4) for cooling, the return water system includes: a return water pipe, a first refrigerator (2) and a refrigeration heat exchanger (3) arranged on the return water pipe, The return water of the return water system first flows through the first refrigerator (2) for first-stage cooling, then flows through the refrigeration heat exchanger (3) for second-stage cooling, and finally flows into the ice storage device (4) for three-stage cooling. The temperature is lowered, and the ice storage device (4) treats the second-temperature-reduced return water into chilled water, and the chilled water enters the water supply system for reuse by the air-conditioning terminal equipment; At 18 ° C. The air-conditioning chilled water system for multi-stage refrigeration and terminal energy step utilization according to claim 1, further comprising a second refrigerator (6), and an ice storage coil is placed in the ice storage device (4). The ice storage coil is in communication with the second refrigerator (6); the ice storage coil is immersed in the ice storage device (4) and is used for freezing water in the ice storage device (4). The air-conditioning chilled water system for multi-stage refrigeration and terminal energy cascade utilization according to claim 2, characterized in that a cooling supply pipe and a return cooling are provided between the ice storage coil and the second refrigerator (6) A pipeline, a circulation circuit for circulating low-temperature refrigerant is formed between the ice storage coil, the cooling supply pipeline, the return cooling pipeline, and the second refrigerator (6); A refrigerating heat exchanger (3) is also connected to the supply and return cooling pipelines. The refrigerating heat exchanger (3) and the ice storage device (4) are connected in parallel and flow through the refrigerating heat exchanger (3). The low-temperature carrier refrigerant performs heat exchange with the return water flowing through the refrigeration heat exchanger (3) to reduce the temperature of the return water. The multi-stage refrigeration and air-conditioning chilled water system for terminal energy step use according to claim 3, characterized in that a connection pipe is connected between the cooling pipe and the return cooling pipe, and the connection pipe is provided with There are switching valves. The air-conditioning chilled water system for multi-stage refrigeration and terminal energy cascade utilization according to claim 1, characterized in that the air-conditioning terminal equipment comprises a first-stage cold equipment (8) and a second-stage cold equipment (10). The chilled water temperature required for the first-stage cold equipment (8) is lower than the chilled water temperature required for the second-stage cold equipment (10), the first-stage cold equipment (8) and the second-stage cold equipment (10) ) In series so that the chilled water flows through the primary cold equipment (8) before entering the secondary cold equipment (10). The air-conditioning chilled water system for multi-stage refrigeration and terminal energy cascade utilization according to claim 5, characterized in that both ends of the first-stage cooling equipment (8) are further connected with a water supply side bypass pipe (16), The chilled water output from the main water supply system can be mixed with the effluent from the first-stage cooling equipment (8) and then entered into the second-stage cooling equipment (10) for use by the second-stage cooling equipment (10). The air-conditioning chilled water system for multi-stage refrigeration and terminal energy cascade utilization according to claim 5, characterized in that the two ends of the secondary cooling equipment (10) are further connected with a return side bypass pipe (17) in parallel. The return water of the first-stage cooling equipment (8) can partially flow through the return side bypass pipe (17) and enter the return water system supervisor. The air-conditioning chilled water system for multi-stage refrigeration and terminal energy cascade utilization according to any one of claims 5 to 7, characterized in that the first-stage cold equipment (8) includes a first cold user and a second cold user. Cold user, the first cold user and the second cold user are connected in parallel; The secondary cold device (10) includes a third cold user and a fourth cold user, and the third cold user is connected in parallel with the fourth cold user. The multi-stage refrigeration and air-conditioning chilled water system for terminal energy cascade utilization according to claim 8, characterized in that the return water of the first cold user and the return water of the second cold user are combined for secondary use. The cold equipment (10) is used. The return water of the third cold user and the return water of the fourth cold user are collected and flowed into the return water system. The multi-stage refrigeration and air-conditioning chilled water system for terminal energy cascade utilization according to claim 8, characterized in that the chilled water output from the water supply system flows into a first cold user for use by the first cold user; The frozen water output from the water supply system is mixed with the return water of the second cold user to a temperature required by the second cold user, and then flows into the second cold user for use by the second cold user; The return water of the first cold user and the return water of the second cold user are collected and flowed into the third cold user for use by the third cold user; The return water of the first cold user, the return water of the second cold user, and the return water of the fourth cold user are mixed to a temperature required by the fourth cold user, and then used by the fourth cold user.

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