CN111140956A

CN111140956A - Multi-mode refrigerating system of cascade cold accumulation-release type data machine room

Info

Publication number: CN111140956A
Application number: CN202010065576.1A
Authority: CN
Inventors: 吕石磊; 许勃文; 贾维
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2020-01-20
Filing date: 2020-01-20
Publication date: 2020-05-12

Abstract

The invention discloses a multi-mode refrigerating system of a cascade cold accumulation-release type data machine room, which comprises a water chilling unit, a chilled water circulating pump, air conditioner tail end equipment, a cooling water circulating pump, a main cooling tower, an auxiliary cooling tower, a plate heat exchanger, a cascade phase change cold accumulation device and a temperature sensor. The system can control the electromagnetic valve according to the running state and the external condition, and flexibly adjust the running mode. In the low-ebb electricity period at night, the system can switch 6 operation modes, and the cold storage capacity of the step phase change cold storage device and the maximization of the natural cold capacity at night are realized. In the peak power period in the daytime, the system has 9 operation modes, and the return water temperature of chilled water entering the water chilling unit is reduced to the maximum extent, so that the refrigeration energy consumption and the operation cost of the water chilling unit are reduced, and the maximization of energy conservation and economic benefits is realized. The system can fully utilize the off-peak electricity at night and an external natural cold source, obviously reduce the refrigeration energy consumption and the operation cost of the data machine room, and has wide application prospect.

Description

Multi-mode refrigerating system of cascade cold accumulation-release type data machine room

Technical Field

The invention relates to a refrigerating system of a data machine room, in particular to a multi-mode refrigerating system of a cascade cold accumulation-release type data machine room.

Background

With the rapid development of big data and cloud computing, the energy consumption of data centers is also rapidly increasing. In 2010, the power consumption of the data center accounts for 1.3% of the total power consumption in the world. Wherein, except the IT server, the energy consumption of the cooling equipment is the highest, which accounts for about 30-50% of the total energy consumption of the data center. Therefore, how to effectively reduce the refrigeration energy consumption of the data center is the key to realize energy conservation and emission reduction. In addition, countries implement peak-to-valley electricity rates due to imbalances in power demand and supply, encouraging off-peak electricity usage. If a certain amount of cold energy can be stored for use in the daytime during the low-ebb electricity period at night, the peak clipping and valley filling effects of the power grid can be achieved, the refrigeration operation cost of the data center can be reduced, and the system economy is improved.

Chinese patent No. ZL2018208097738 discloses a data center energy-saving cold storage and supply system, which comprises a refrigerating unit, a cold release pump, a radiator, a freezing pump and a cold storage tank. Through increasing the refrigerating unit in the period of off-peak electricity at night and throwing into, to the refrigeration jar cold-storage, store a large amount of cold volume in cold-storage jar, when daytime the power consumption peak value, cold-storage jar is put cold, releases the cold volume of storing, realizes the energy-conserving operation of system under the prerequisite that does not influence the system cooling, reduces the operation of system and drops into.

A Chinese patent with the patent number ZL2017208597202 discloses a cold accumulation energy-saving system for a data center, which comprises a main machine of a refrigeration system, and a cold accumulation tank connected with a tail end load in parallel is arranged on a circulating pipeline of the main machine and the tail end load. The system has the effect of saving electricity cost, uses little or no electricity at the peak of the electricity price, releases the stored energy and is suitable for use, and uses more electricity at the low price of the electricity to store the prepared cold or heat.

Chinese patent with the patent number ZL2017205149844 discloses a chilled water storage refrigeration system for a data center, which comprises a conventional operation pipeline, a chilled storage pipeline and a cold discharge pipeline. The conventional operation pipeline comprises a water collector, a freezing pump, a refrigeration host, a cooling pump and a cooling tower which are sequentially connected through a pipeline, wherein the cooling tower is connected with the refrigeration host, and the refrigeration host is connected with a water separator; the cold accumulation pipeline comprises a cold accumulation pump, a refrigeration host, a cold release pump and a cold accumulation tank which are sequentially connected through pipelines, and the cold accumulation tank is connected with the cold accumulation pump; the cold discharging pipeline comprises a water collector, a cold storage pump, a cold storage tank, a cold discharging pump and a water distributor which are connected through pipelines. The system has three operation modes of a conventional operation pipeline, a cold accumulation pipeline and a cold discharge pipeline, and can utilize a low valley electricity cold accumulation tank to accumulate cold at night and utilize the cold energy accumulated by the cold accumulation tank at night to discharge cold at daytime in an area implementing peak valley electricity price.

Chinese patent with the patent number ZL2016205233888 discloses a solar phase change cold accumulation system of a data center. The system comprises a precise air conditioner, a solar absorption refrigerating unit and a phase change cold accumulator. The system uses renewable resource solar energy as a substitute for conventional energy used by the air-conditioning system, reduces energy consumption of the air-conditioning refrigeration system of the data center, and saves enterprise cost. The phase change cold accumulator is adopted, so that a large amount of cold can be stored in a time period when the illumination is sufficient, and the requirement of a user on the cold can be met to the greatest extent when the illumination is insufficient or at night.

From the above patent, the following problems can be summarized: 1. only a mechanical cold accumulation method is considered, namely, cold accumulation is performed only by the refrigerating unit in the low-ebb electricity period at night, a natural cold source at night is not fully utilized, and energy is not saved by only utilizing mechanical refrigeration due to cold loss in the cold accumulation and release process. In addition, in the later stage of the operation of the data center, when the cold load of the machine room reaches the design load, the refrigerating unit can not accumulate cold at night. 2. Most researchers adopt chilled water storage or single-stage phase change chilled storage. However, the water cold storage device has a large volume and a small cold storage amount. The single-stage phase change cold accumulation device filled with a phase change material has poor heat exchange performance and low cold accumulation and release rate,

the efficiency is low. 3. The system operation mode is too simple. The applicant only proposes several simple operation modes based on the valley electricity cold accumulation, lacks the cold volume of utilization night, and can't adjust in a flexible way.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a multi-mode refrigerating system of a cascade cold accumulation-release type data machine room.

Provides a multi-mode refrigerating system of a cascade cold accumulation-release type data machine room,

a multi-mode refrigerating system of a cascade cold accumulation-release type data machine room comprises:

the water outlet of the evaporator of the water chilling unit is sequentially connected with a chilled water circulating pump, a first temperature sensor, air conditioner tail end equipment, a second temperature sensor, a first electromagnetic valve and a water inlet of the evaporator of the water chilling unit through a chilled water circulating pipeline;

one end of a chilled water heat exchange circulating pipeline is communicated with a water outlet of air conditioner terminal equipment and the chilled water circulating pipeline between the first electromagnetic valves, and the other end of the chilled water heat exchange circulating pipeline is sequentially connected with a second electromagnetic valve, a fifth electromagnetic valve, a third temperature sensor, a chilled water circulating plate side of the plate heat exchanger, a fourth temperature sensor, a tenth electromagnetic valve, a third electromagnetic valve and a chilled water circulating pipeline between the first electromagnetic valve and a water inlet of an evaporator of a water chilling unit;

the cascade phase change cold accumulation device comprises an inner shell and an outer shell sleeved outside the inner shell at intervals, heat insulation materials are filled between the inner shell and the outer shell, an upper cover plate is covered on the top wall of the outer shell and the inner shell, two baffles are fixed in the inner shell at intervals along the left and right direction to divide the inner shell into a first cavity, a second cavity and a third cavity which are independent from each other, a first-stage phase change material is filled in the first cavity to form a first-stage phase change unit, a second-stage phase change material is filled in the second cavity to form a second-stage phase change unit, a third-stage phase change material is filled in the third cavity to form a third-stage phase change cold accumulation unit, and a plurality of temperature sensors of the cascade phase change cold accumulation device are respectively installed in the first-stage phase change material, the second-stage phase change material and the third-stage phase change material, a chilled water heat exchange coil and a cooling water heat exchange coil are respectively coiled to pass through the first chamber, the second chamber and the third chamber, one end of the chilled water heat exchange coil is communicated with one end of a chilled water heat exchange first main pipe provided with a thirteenth electromagnetic valve and a fifth temperature sensor, and the thirteenth electromagnetic valve and the fifth temperature sensor are sequentially arranged on the chilled water heat exchange first main pipe along the flow direction of cold release flow; the other end of the chilled water heat exchange coil is communicated with one end of a chilled water heat exchange second main pipe provided with a fifteenth electromagnetic valve and a sixth temperature sensor, and the sixth temperature sensor and the fifteenth electromagnetic valve are sequentially arranged on the chilled water heat exchange second main pipe along the flowing direction of the cold releasing flow; the other end of the chilled water heat exchange first main pipe is divided into a first branch pipe provided with an eighth electromagnetic valve and a second branch pipe provided with a ninth electromagnetic valve, one end of the first branch pipe is connected to a chilled water circulation pipeline between a water outlet of air conditioner terminal equipment and the first electromagnetic valve, and one end of the second branch pipe is connected to a chilled water heat exchange circulation pipeline between the second electromagnetic valve and the fifth electromagnetic valve; the other end of the chilled water heat exchange second main pipe is divided into a third branch pipe provided with a fourth electromagnetic valve and a fourth branch pipe provided with a sixteenth electromagnetic valve, the other end of the third branch pipe is communicated with a chilled water circulation pipeline between the chilled water circulation pump and a water inlet of air-conditioning terminal equipment, and the other end of the fourth branch pipe is communicated with a chilled water heat exchange circulation pipeline between the third electromagnetic valve and a tenth electromagnetic valve; one end of a fifth branch pipe provided with a seventeenth electromagnetic valve is communicated with a chilled water heat exchange second main pipe positioned between the fifteenth electromagnetic valve and the other end of the chilled water heat exchange coil; one end of a sixth branch pipe provided with an eleventh electromagnetic valve is communicated with a chilled water heat exchange first main pipe positioned between the thirteenth electromagnetic valve and one end of the chilled water heat exchange coil pipe, and the other end of the sixth branch pipe is communicated with a chilled water heat exchange circulating pipeline positioned between the tenth electromagnetic valve and an outlet on the chilled water circulating plate side of the plate heat exchanger;

one end of the cooling water heat exchange coil is communicated with one end of a cooling water heat exchange first main pipe provided with a fourteenth electromagnetic valve and a seventh temperature sensor, and the other end of the cooling water heat exchange coil is communicated with one end of a cooling water heat exchange second main pipe provided with an eighth temperature sensor and an eighteenth electromagnetic valve; the fourteenth electromagnetic valve and the seventh temperature sensor are sequentially arranged on the cooling water heat exchange first main pipe along the flow direction of the cold release flow, and the eighth temperature sensor and the eighteenth electromagnetic valve are sequentially arranged on the cooling water heat exchange second main pipe along the flow direction of the cold release flow;

a water outlet at the condenser side of the water chilling unit is sequentially connected with a ninth temperature sensor, a cooling water circulating pump and a twenty-first electromagnetic valve through a cooling water circulating main pipeline, then the cooling water circulation branch pipe is divided into two cooling water circulation branch pipes, the first cooling water circulation branch pipe is sequentially connected with a tenth temperature sensor, a main cooling tower, an eleventh temperature sensor, a twelfth electromagnetic valve, a twelfth temperature sensor, a cooling water circulation plate side of the plate heat exchanger, a thirteenth temperature sensor, a sixth electromagnetic valve, a fourteenth temperature sensor and a water return port on the condenser side of the water chilling unit, one end of a first cooling water circulation straight connecting pipe is communicated with the first cooling water circulation branch pipe between the main cooling tower and the twelfth electromagnetic valve, the other end of the first cooling water circulation straight connecting pipe is communicated with the first cooling water circulation branch pipe between the water return port on the condenser side of the water chilling unit and the sixth electromagnetic valve, and a seventh electromagnetic valve is installed on the first cooling water circulation branch pipe; the second cooling water circulation branch pipe is sequentially connected with a twentieth electromagnetic valve, a fifteenth temperature sensor, an auxiliary cooling tower, a sixteenth temperature sensor and the other end of the cooling water heat exchange second main pipe, one end of a second cooling water circulation straight connecting pipe provided with a nineteenth electromagnetic valve is communicated with the other end of the cooling water heat exchange second main pipe, and the other end of the second cooling water circulation straight connecting pipe is sequentially communicated with the other end of the cooling water first heat exchange main pipe and a cooling water return port of a water chilling unit; the chilled water heat exchange first main pipe, the chilled water heat exchange second main pipe, the cooling water heat exchange coil and the cooling water heat exchange second main pipe are arranged outside the step phase change cold accumulation device;

the phase change temperature relation of the phase change materials is filled in each level of cold storage units, and the phase change temperature of the first-level phase change material is greater than the phase change temperature of the second-level phase change material and greater than the phase change temperature of the third-level phase change material.

The invention has the advantages that:

1. the cascade cold accumulation-release type data machine room refrigerating system can fully utilize night off-peak electricity and an external natural cold source, reduces the refrigerating operation cost of the data machine room, and plays a role in power grid peak regulation. Compared with the prior art that mechanical cold accumulation is singly adopted, the method has more remarkable energy-saving benefit and economic benefit and wide application prospect.

2. The system adopts a step phase change cold accumulation device, and has the advantages of large cold accumulation density, small device volume and the like compared with a water cold accumulation device.

3. The system adopts a step phase change cold accumulation device, compared with a single-stage phase change cold accumulation device filled with only one phase change material, the system realizes the step cold accumulation in the cold accumulation stage, and can improve the cold accumulation rate and cold accumulation

The efficiency is improved, the requirement on the outlet water temperature of a cold source is further reduced, and partial cold energy can be stored in the system even if the outdoor temperature is relatively high; in the stage of cooling, the step cooling is realized, the cooling rate and cooling can be increased

The efficiency is favorable for reducing the return water temperature of the chilled water of the water chilling unit, and further reduces the refrigeration energy consumption of the unit and the daytime running cost.

4. The system can flexibly adjust the operation mode according to the operation state and the external condition, and the maximization of economic benefit and energy-saving benefit is realized. In the valley electricity period at night, the system can adjust the connection mode of the cold accumulation cold source and the step cold accumulation device according to the water outlet temperature of the cooling tower and the running state of the water chilling unit, so that the natural cold energy is utilized to the maximum extent, and the energy saving performance of the system is improved; in the cold discharging process, the connection mode of the cold releasing cold source and the water chilling unit can be adjusted according to the outlet water temperature of the cooling tower and the outlet water temperature of the cold storage device, the return water temperature of the chilled water is reduced to the maximum extent, the power consumption of the unit in the peak power period is further reduced to the maximum extent, and the economical efficiency and the energy saving performance of the system are improved.

Drawings

Fig. 1 is a schematic structural diagram of a cascade cold accumulation-release type data room multi-mode refrigeration system according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of the stepped phase change cold storage device in the system shown in fig. 1.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The invention discloses a multi-mode refrigerating system of a cascade cold accumulation-release type data machine room, which comprises:

the water cooling system comprises a water chilling unit 1, wherein a water outlet of an evaporator of the water chilling unit 1 is sequentially connected with a chilled water circulating pump 7, a first temperature sensor 21-1, an air conditioner terminal device 8, a second temperature sensor 21-2, a first electromagnetic valve F1 and a water inlet of the evaporator of the water chilling unit 1 through a chilled water circulating pipeline;

one end of a chilled water heat exchange circulating pipeline of the plate heat exchanger 6 is communicated with a chilled water circulating pipeline between a water outlet of an air conditioner terminal device 8 and a first electromagnetic valve F1, and the other end of the chilled water heat exchange circulating pipeline is sequentially connected with a second electromagnetic valve F2, a fifth electromagnetic valve F5, a third temperature sensor 21-3, a chilled water circulating plate side of the plate heat exchanger 6, a fourth temperature sensor 21-4, a tenth electromagnetic valve F10, a third electromagnetic valve F3 and a chilled water circulating pipeline between the first electromagnetic valve F1 and a water inlet of an evaporator of the water chilling unit 1;

the cascade phase change cold storage device 5 comprises an inner shell 11 and an outer shell 9 sleeved outside the inner shell at intervals, wherein a heat insulation material 10 is filled between the inner shell 11 and the outer shell 9, an upper cover plate 14 is covered on the top wall of the outer shell 9 and the inner shell 11, two baffles 18 are fixed in the inner shell 11 at intervals along the vertical direction to separate the inner shell 3 into a first cavity, a second cavity and a third cavity which are independent from each other, a first-stage phase change material 20 is filled in the first cavity to form a first-stage phase change cold storage unit, a second-stage phase change material 19 is filled in the second cavity to form a second-stage phase change cold storage unit, a third-stage phase change material 17 is filled in the third cavity to form a third-stage phase change cold storage unit, and the first-stage phase change material 20, A plurality of cold accumulation device temperature sensors 21-17, 21-18, 21-19, 21-20, 21-21, 21-22, 21-23, 21-24 and 21-25 are respectively arranged in the second-stage phase change material 19 and the third-stage phase change material 17, a chilled water heat exchange coil 12 and a cooling water heat exchange coil 13 are respectively coiled to pass through a first chamber, a second chamber and a third chamber, one end of the chilled water heat exchange coil 12 is communicated with one end of a chilled water heat exchange first dry pipe 16 provided with a thirteenth electromagnetic valve F13 and a fifth temperature sensor 21-5, and the thirteenth electromagnetic valve F13 and the fifth temperature sensor 21-5 are sequentially arranged on the chilled water heat exchange first dry pipe 16 along the flow direction of cold release flow; the other end of the chilled water heat exchange coil 12 is communicated with one end of a chilled water heat exchange second main pipe provided with a fifteenth electromagnetic valve F15 and a sixth temperature sensor 21-6, and the sixth temperature sensor 21-6 and the fifteenth electromagnetic valve F15 are sequentially arranged on the chilled water heat exchange second main pipe along the flow direction of cold release flow; the other end of the chilled water heat exchange first main pipe 16 is divided into a first branch pipe provided with an eighth solenoid valve F8 and a second branch pipe provided with a ninth solenoid valve F9, one end of the first branch pipe is connected to a chilled water circulation pipeline between a water outlet of air conditioner terminal equipment 8 and a first solenoid valve F1, and one end of the second branch pipe is connected to a chilled water heat exchange circulation pipeline between a second solenoid valve F2 and a fifth solenoid valve F5; the other end of the chilled water heat exchange second main pipe is divided into a third branch pipe provided with a fourth electromagnetic valve F4 and a fourth branch pipe provided with a sixteenth electromagnetic valve F16, the other end of the third branch pipe is communicated with a chilled water circulation pipeline between the chilled water circulation pump 7 and a water inlet of an air-conditioning terminal device 8, and the other end of the fourth branch pipe is communicated with a chilled water heat exchange circulation pipeline between a third electromagnetic valve F3 and a tenth electromagnetic valve F10; one end of the fifth branch pipe provided with the seventeenth electromagnetic valve is communicated with the chilled water heat exchange second main pipe which is positioned between the fifteenth electromagnetic valve F15 and the other end of the chilled water heat exchange coil 12; one end of a sixth branch pipe provided with an eleventh electromagnetic valve F11 is communicated with the chilled water heat exchange first main pipe 16 between the thirteenth electromagnetic valve and one end of the chilled water heat exchange coil 12, and the other end is communicated with a chilled water heat exchange circulation pipeline between the tenth electromagnetic valve F10 and an outlet on the chilled water circulation plate side of the plate heat exchanger 6.

One end of the cooling water heat exchange coil 13 is communicated with one end of a cooling water heat exchange first main pipe 15 provided with a fourteenth electromagnetic valve F14 and a seventh temperature sensor 21-7, and the other end of the cooling water heat exchange coil is communicated with one end of a cooling water heat exchange second main pipe provided with an eighth temperature sensor 21-8 and an eighteenth electromagnetic valve F18; the fourteenth electromagnetic valve F14 and the seventh temperature sensor 21-7 are sequentially installed on the cooling water heat exchange first main pipe 15 along the flow direction of the cooling flow, and the eighth temperature sensor 21-8 and the eighteenth electromagnetic valve F18 are sequentially installed on the cooling water heat exchange second main pipe along the flow direction of the cooling flow.

A water outlet at the condenser side of the water chilling unit 1 is sequentially connected with a ninth temperature sensor 21-9, a cooling water circulating pump 2 and a twenty-first electromagnetic valve F21 through a cooling water circulating main pipeline and then is divided into two cooling water circulating branch pipes, the first cooling water circulating branch pipe is sequentially connected with a tenth temperature sensor 21-10, a main cooling tower 3, an eleventh temperature sensor 21-11, a twelfth electromagnetic valve F12, a twelfth temperature sensor 21-12, a cooling water circulating plate side of the plate heat exchanger 6, a thirteenth temperature sensor 21-13, a sixth electromagnetic valve F6, a fourteenth temperature sensor 21-14 and a water return port at the condenser side of the water chilling unit 1, one end of one first cooling water circulating direct connecting pipe is communicated with the first cooling water circulating branch pipe between the main cooling tower 3 and the twelfth electromagnetic valve F12, and the other end of the first cooling water circulating branch pipe is communicated with the water return port between the condenser side of the water chilling unit 1 and the sixth electromagnetic valve F6 The water circulation branch pipe is communicated, and a seventh electromagnetic valve F7 is arranged on the first cooling water circulation branch pipe; the second cooling water circulation branch pipe is sequentially connected with a twentieth electromagnetic valve F20, a fifteenth temperature sensor 21-15, an auxiliary cooling tower 4, a sixteenth temperature sensor 21-16 and the other end of the cooling water heat exchange second main pipe, one end of a second cooling water circulation straight connecting pipe provided with a nineteenth electromagnetic valve F19 is communicated with the other end of the cooling water heat exchange second main pipe, and the other end of the second cooling water circulation straight connecting pipe is sequentially communicated with the other end of the cooling water first heat exchange main pipe and a cooling water return port of the water chilling unit.

The temperature sensors are respectively arranged at the inlet and outlet of the evaporator and the condenser of the water chilling unit 1, the inlet and outlet of the main cooling tower 3 and the auxiliary cooling tower 4, the inlet and outlet of the step phase change cold storage device 5 and the inside of the device, and the inlet and outlet of the plate heat exchanger 6.

The chilled water heat exchange first main pipe 16, the chilled water heat exchange second main pipe, the cooling water heat exchange coil 13 and the cooling water heat exchange second main pipe are arranged outside the step phase change cold storage device 5.

The phase-change temperature relation of the phase-change materials is filled in each level of cold storage units, and the phase-change temperature of the first-level phase-change material 20 is greater than the phase-change temperature of the second-level phase-change material 19 and greater than the phase-change temperature of the third-level phase-change material 17. In the cold accumulation process, the low-temperature heat transfer fluid flows along the direction of the phase change temperature which is sequentially increased; in the cooling process, the low-temperature heat transfer fluid flows along the direction of the sequentially reduced phase-change temperature. In addition, considering that the stepped phase change cold accumulation device can still accumulate part of cold energy when the outlet water temperature of the cooling tower at night cannot meet the cold accumulation requirement of the stepped phase change cold accumulation device, the cold accumulation requirement temperature of the stepped phase change cold accumulation device is designed to be higher than the outlet water temperature of chilled water of the water chilling unit, so that the water chilling unit can directly charge cold to the stepped phase change cold accumulation device at night.

The first-stage phase-change material 20 can adopt octanoic acid with the phase-change temperature of 16 ℃, the second-stage phase-change material 19 can adopt dipotassium phosphate hexahydrate with the phase-change temperature of 13 ℃, and the third-stage phase-change material 17 can adopt pentadecane with the phase-change temperature of 10 ℃.

The main cooling tower 3 and the auxiliary cooling tower 4 are preferably the same type of cooling tower. The main cooling tower 3 can be formed by connecting a plurality of cooling towers in parallel. The main cooling tower 3 is mainly used for reducing the temperature of cooling water so as to be used for heat exchange of a condenser of the water chilling unit 1 or precooling return water of the cooling water through the plate heat exchanger 6. The auxiliary cooling tower 4 is mainly used for separately storing cold for the cascade phase change cold storage device 5 when the temperature of the outlet water of the cooling tower meets the cold storage requirement of the cascade cold storage device. The return chilled water output from the output end of the air conditioner terminal equipment 8 is branched into three paths, and the return chilled water directly enters the water chilling unit 1 for heat exchange, enters the step phase change cold storage device 5 and enters the plate heat exchanger 6. The electromagnetic valve can be controlled according to the running state of the system, the flow path of the chilled water output by the air conditioner terminal equipment 8 is changed, the temperature of the chilled water entering the water chilling unit 1 is the lowest, and therefore the lowest refrigeration energy consumption and running cost of the unit in the daytime are achieved. When the temperature of the outlet water of the main cooling tower 3 meets the cold accumulation requirement of the step cold accumulation device at night, the auxiliary cooling tower is opened, and the low-temperature cooling water from the auxiliary cooling tower 4 can directly enter the step phase change cold accumulation device for cold accumulation.

The operation modes of the system in the night off-peak electricity period comprise 6 modes of mechanical refrigeration, partial mechanical refrigeration, mechanical cold accumulation-partial mechanical refrigeration, natural cold accumulation, mechanical cold accumulation-partial mechanical refrigeration and natural cold accumulation-natural cooling. By means of the 6 kinds of operation mode switching, the cold storage capacity of the step phase change cold storage device and the maximization of the natural cold capacity at night can be realized under the condition that the operation of the water chilling unit is not influenced, and the efficient and energy-saving operation of the system is ensured. The operation modes are as follows:

in the mechanical cooling mode, the first solenoid valve F1, the seventh solenoid valve F7, and the twentieth solenoid valve F21 are opened. The mode is suitable for the condition that the outlet water temperature of the cooling tower at night is higher than the cold accumulation required temperature of the step phase change cold accumulation device and the return water precooling required temperature of the chilled water of the evaporator, and the cold water unit runs at full load and can not meet the extra cold accumulation requirement. The chilled water is output from the output end of the chilled water circulating water pump 7, enters the air conditioner terminal equipment 8, enters the evaporator of the water chilling unit 1 through the first electromagnetic valve F1 for heat exchange, and is output from the evaporator and enters the input end of the chilled water circulating water pump 7. The cooling water is output from the cooling water circulating water pump 2, enters the main cooling tower 3 through the twenty-first electromagnetic valve F21, is output from the output end of the main cooling tower 3, enters the condenser of the water chilling unit 1 through the seventh electromagnetic valve F7 for heat exchange, and finally enters the input end of the cooling water circulating water pump 2.

The partial mechanical cooling mode opens second solenoid valve F2, third solenoid valve F3, fifth solenoid valve F5, sixth solenoid valve F6, tenth solenoid valve F10, twelfth solenoid valve F12, twenty-first solenoid valve F21. The mode is suitable for the condition that the outlet water temperature of the cooling tower at night is higher than the cold accumulation requirement temperature of the step phase change cold accumulation device and lower than the return water precooling requirement temperature of chilled water of the evaporator, and the cold water unit runs at full load and can not meet the requirement of additional cold accumulation. The chilled water is output from the output end of the chilled water circulating water pump 7, enters the air conditioner tail end equipment 8, enters the plate heat exchanger 6 through the second electromagnetic valve F2 and the fifth electromagnetic valve F5 to exchange heat with cooling water flowing out of the main cooling tower 4, enters the evaporator of the water chilling unit 1 through the tenth electromagnetic valve F10 and the third electromagnetic valve F3 to exchange heat, and is output from the evaporator to enter the input end of the circulating water pump 7. The cooling water is output from the cooling water circulating water pump 2, passes through the twenty-first electromagnetic valve F21, enters the main cooling tower 3, is output from the output end of the main cooling tower 3, enters the plate type heat exchange heat exchanger 6 through the twelfth electromagnetic valve F12, precools the return water of the chilled water coming out of the air conditioner tail end equipment 8, then enters the condenser of the water chilling unit 1 through the sixth electromagnetic valve F6 for heat exchange, and finally enters the input end of the cooling water circulating water pump 2.

In the mechanical cold accumulation-mechanical refrigeration mode, the first electromagnetic valve F1, the fourth electromagnetic valve F4, the seventh electromagnetic valve F7, the eighth electromagnetic valve F8, the thirteenth electromagnetic valve F13, the fifteenth electromagnetic valve F15 and the twenty-first electromagnetic valve F21 are opened. The mode is suitable for the condition that the outlet water temperature of the night cooling tower is higher than the cold accumulation required temperature of the step phase change cold accumulation device and the return water precooling required temperature of the chilled water of the evaporator, and the water chilling unit runs with partial load, so that the additional cold accumulation requirement can be met. The chilled water is output from the output end of the chilled water circulating water pump 7 and enters two branches, one branch is connected with the air conditioner tail end equipment 8, and the other branch is connected with the step phase change cold accumulation device 5. Wherein, the refrigerated water that gets into step phase transition cold-storage device passes through fourth solenoid valve F4, fifteenth solenoid valve F15 back, first third level phase transition cold-storage unit of getting into, reentrant second level phase transition cold-storage unit, flow out from first order phase transition cold-storage unit at last through thirteenth solenoid valve F13, behind eighth solenoid valve F8, with the refrigerated water return water that comes out from air conditioner end equipment 8 and intersect, later get into the heat transfer of 1 evaporimeter of cooling water set through first solenoid valve F1, get into refrigerated water circulating water pump 8 input at last. The cooling water is output from the cooling water circulating water pump 2, passes through the twenty-first electromagnetic valve F21, enters the main cooling tower 3, is output from the output end of the main cooling tower 3, passes through the seventh electromagnetic valve F7, enters the condenser of the water chilling unit 1 for heat exchange, and finally enters the input end of the cooling water circulating water pump 2. When the difference value between the inlet temperature of the cascade phase change cold accumulation device and the temperature of each level of cold accumulation units in the device (the arithmetic mean value of the temperature values of the temperature sensors in each cavity) detected by the temperature sensors is within a set value (such as 0.1 degree), which indicates that the cascade phase change cold accumulation device has reached the maximum cold accumulation amount in the mechanical cold accumulation-mechanical refrigeration mode, the fourth electromagnetic valve F4, the eighth electromagnetic valve F8, the thirteenth electromagnetic valve F13 and the fifteenth electromagnetic valve F15 are closed, and cold accumulation is stopped.

In the mechanical cold accumulation-partial mechanical refrigeration mode, a second electromagnetic valve F2, a third electromagnetic valve F3, a fourth electromagnetic valve F4, a fifth electromagnetic valve F5, a sixth electromagnetic valve F6, an eighth electromagnetic valve F8, a tenth electromagnetic valve F10, a twelfth electromagnetic valve F12, a thirteenth electromagnetic valve F13, a fifteenth electromagnetic valve F15 and a twenty-first electromagnetic valve F21 are opened. The mode is suitable for the condition that the outlet water temperature of the cooling tower at night is higher than the cold accumulation required temperature of the step phase change cold accumulation device and lower than the return water precooling required temperature of the chilled water of the evaporator, and the water chilling unit operates with partial load and can meet the requirement of additional cold accumulation. The chilled water is output from the output end of the chilled water circulating water pump 7 and enters two branches, one branch is connected with the air conditioner tail end equipment 8, and the other branch is connected with the step phase change cold accumulation device 5. The chilled water entering the step phase change cold storage device firstly enters the third-stage phase change cold storage unit after passing through the fourth electromagnetic valve F4 and the fifteenth electromagnetic valve F15, then enters the second-stage phase change cold storage unit, finally flows out of the first-stage phase change cold storage unit, passes through the thirteenth electromagnetic valve F13 and the eighth electromagnetic valve F8, and then is intersected with the chilled water backwater coming out of the air conditioner terminal equipment 8. The intersected chilled water enters the plate heat exchanger 6 and cooling water flowing out of the main cooling tower 4 through a second electromagnetic valve F2 and a fifth electromagnetic valve F5 for heat exchange, then enters the evaporator of the water chilling unit 1 for heat exchange after passing through a tenth electromagnetic valve F10 and a third electromagnetic valve F3, and finally is output from the evaporator and enters the input end of the circulating water pump 7. The cooling water is output from the cooling water circulating water pump 2, passes through the twenty-first electromagnetic valve F21, enters the main cooling tower 3, is output from the output end of the main cooling tower 3, enters the plate type heat exchange heat exchanger 6 through the twelfth electromagnetic valve F12, precools the return water of the chilled water coming out of the air conditioner tail end equipment 8, then enters the condenser of the water chilling unit 1 through the sixth electromagnetic valve F6 for heat exchange, and finally enters the input end of the cooling water circulating water pump 2. When the difference value between the inlet temperature of the cascade phase change cold accumulation device and the temperature of each level of cold accumulation unit in the device is detected to be within a set value (such as 0.1 degree) through the temperature sensor, which indicates that the cascade phase change cold accumulation device has reached the maximum cold accumulation amount in the mechanical cold accumulation-partial mechanical refrigeration mode, the fourth electromagnetic valve F4, the eighth electromagnetic valve F8, the thirteenth electromagnetic valve F13 and the fifteenth electromagnetic valve F15 are closed, and cold accumulation is stopped.

The mode of natural cold accumulation and mechanical cold accumulation-partial mechanical refrigeration is adopted. The mode is suitable for the condition that the outlet water temperature of the cooling tower at night is lower than the cold accumulation required temperature of the step phase change cold accumulation device and the return water precooling required temperature of the chilled water of the evaporator but is higher than the outlet water temperature of the chilled water of the water chilling unit, and the water chilling unit refrigerates with partial load, thereby meeting the requirement of additional cold accumulation. At this time, in order to store as much cold as possible for use in the daytime, the auxiliary cooling tower set 4 is operated to cool the stepped phase change cold storage device 5, and then the chilled water of the chiller unit 1 is discharged to cool the stepped phase change cold storage device 5. The second solenoid valve F2, the third solenoid valve F3, the fifth solenoid valve F5, the sixth solenoid valve F6, the tenth solenoid valve F10, the twelfth solenoid valve F12, the fourteenth solenoid valve F14, the eighteenth solenoid valve F18, the twentieth solenoid valve F20 and the twenty-first solenoid valve F21 are opened first. The chilled water is output from the output end of the chilled water circulating water pump 7, enters the air conditioner tail end device 8, enters the plate heat exchanger 6 through the second electromagnetic valve F2 and the fifth electromagnetic valve F5, exchanges heat with the water outlet of the main cooling tower 3, enters the evaporator of the water chilling unit 1 through the tenth electromagnetic valve F10 and the third electromagnetic valve F3, exchanges heat, and is output from the evaporator and enters the input end of the chilled water circulating water pump 7. The cooling water is output from the cooling water circulating water pump 2, passes through a twenty-first electromagnetic valve F21, enters the main cooling tower 3 and branches, and passes through a twentieth electromagnetic valve F20 and then branches of the auxiliary cooling tower 4. The water is output from the output end of the main cooling tower 3, enters a plate heat exchanger 6, and precools the return water of the chilled water from the air conditioner tail end equipment 8; the cold air is output from the output end of the auxiliary cooling tower 4, enters the step phase change cold accumulation device 5, and sequentially passes through the third-stage phase change cold accumulation unit, the second-stage phase change cold accumulation unit and the first-stage phase change cold accumulation unit. The two branches are intersected at the cooling water return position of the condenser of the water chilling unit 1 and finally enter the input end of the cooling water circulating water pump 2. When the difference value between the inlet temperature of the cascade phase change cold accumulation device and the temperature of each cold accumulation unit in the device is detected to be within a set value (such as 0.1 degree) through the temperature sensor, which indicates that the cascade phase change cold accumulation device reaches the maximum cold accumulation amount in the natural cold accumulation-partial mechanical refrigeration mode, the fourteenth electromagnetic valve F14, the eighteenth electromagnetic valve F18, the twentieth electromagnetic valve F20 and the auxiliary cooling tower 4 are closed, and the fourth electromagnetic valve F4, the eighth electromagnetic valve F8, the thirteenth electromagnetic valve F13 and the fifteenth electromagnetic valve F15 are opened. The system operation mode is changed from a natural cold accumulation-partial mechanical refrigeration mode to a mechanical cold accumulation-partial mechanical refrigeration mode. The chilled water is output from the output end of the chilled water circulating water pump 7 and enters two branches, one branch is connected with the air conditioner tail end equipment 8, and the other branch is connected with the step phase change cold accumulation device 5. The chilled water entering the cascade phase change cold storage device sequentially enters a third-stage phase change cold storage unit, a second-stage phase change cold storage unit and finally flows out of the first-stage phase change cold storage unit, passes through a thirteenth electromagnetic valve F13 and an eighth electromagnetic valve F8 and is intersected with the chilled water returning water coming out of the tail end of the air conditioner through a fourth electromagnetic valve F4 and a fifteenth electromagnetic valve F15. The intersected chilled water enters the plate heat exchanger 6 and cooling water flowing out of the main cooling tower 4 through a second electromagnetic valve F2 and a fifth electromagnetic valve F5 for heat exchange, then enters the evaporator of the water chilling unit 1 for heat exchange after passing through a tenth electromagnetic valve F10 and a third electromagnetic valve F3, and finally is output from the evaporator and enters the input end of the circulating water pump 7. The cooling water is output from the cooling water circulating water pump 2, passes through the twenty-first electromagnetic valve F21, enters the main cooling tower 3, is output from the output end of the main cooling tower 3, enters the plate type heat exchange heat exchanger 6 through the twelfth electromagnetic valve F12, precools the return water of the chilled water coming out of the air conditioner tail end equipment 8, then enters the condenser of the water chilling unit 1 through the sixth electromagnetic valve F6 for heat exchange, and finally enters the input end of the cooling water circulating water pump 2. When the difference value between the inlet temperature of the cascade phase change cold accumulation device and the temperature of each level of cold accumulation unit in the device is detected to be within a set value (such as 0.1 degree) through the temperature sensor, which indicates that the cascade phase change cold accumulation device has reached the maximum cold accumulation amount under the mechanical cold accumulation-partial mechanical refrigeration mode, the fourth electromagnetic valve F4, the eighth electromagnetic valve F8, the thirteenth electromagnetic valve F13 and the fifteenth electromagnetic valve F15 are closed, and the cold accumulation is stopped.

Natural cold accumulation-natural cooling mode. The mode is suitable for the condition that the outlet water temperature of the night cooling tower is lower than the cold accumulation required temperature of the step phase change cold accumulation device and the natural cooling required temperature of the air conditioner tail end equipment. The second solenoid valve F2, the third solenoid valve F3, the fifth solenoid valve F5, the sixth solenoid valve F6, the tenth solenoid valve F10, the twelfth solenoid valve F12, the fourteenth solenoid valve F14, the eighteenth solenoid valve F18, the twentieth solenoid valve F20, and the twenty-first solenoid valve F21 are opened, and the water chilling unit 1 stops operating. The chilled water is output from the output end of the chilled water circulating water pump 7, enters the air conditioner terminal equipment 8, enters the plate heat exchanger 6 and the main cooling tower 3 through the second electromagnetic valve F2 and the fifth electromagnetic valve F5 to exchange heat with water, enters the water chilling unit 1 through the tenth electromagnetic valve F10 and the third electromagnetic valve F3 (does not exchange heat), and finally enters the input end of the chilled water circulating water pump 7. The return water temperature of the chilled water coming out of the air conditioner tail end equipment 8 enters the plate heat exchanger 6 for heat exchange, and the return water temperature of the chilled water can be reduced to the outlet water temperature of the chilled water. At this time, the cooling water is output from the cooling water circulation water pump 2, passes through the twenty-first solenoid valve F21, enters the branch of the main cooling tower 3, and enters the branch of the auxiliary cooling tower 4 through the twenty-second solenoid valve F20. The chilled water which is output from the output end of the main cooling tower 3, enters the plate heat exchanger 6 through a twelfth electromagnetic valve F12 and is discharged from the air conditioner tail end equipment 8 is subjected to water return heat exchange and flows out through a sixth electromagnetic valve F6; the cold storage device is output from the output end of the auxiliary cooling tower 4, enters the cascade phase change cold storage device 5 through an eighteenth electromagnetic valve F18, sequentially passes through the third-stage phase change cold storage unit, the second-stage phase change cold storage unit and the first-stage phase change cold storage unit and flows out of a fourteenth electromagnetic valve F14. The two branches are intersected at the cooling water return position of the condenser of the water chilling unit 1 and finally enter the input end of the cooling water circulating water pump 2. When the difference value between the inlet temperature of the cascade phase change cold accumulation device and the temperature of each level of cold accumulation unit in the device is detected to be within a set value (such as 0.1 degree) through the temperature sensor, which indicates that the cascade phase change cold accumulation device reaches the maximum cold accumulation amount in the natural cold accumulation-natural cooling mode, the fourteenth electromagnetic valve F14, the eighteenth electromagnetic valve F18, the twentieth electromagnetic valve F20 and the auxiliary cooling tower 4 are closed.

The operation modes of the system in the daytime peak power period comprise 9 modes of mechanical refrigeration, step cooling and natural cooling, wherein the modes comprise a cooling tower precooling mode and step cooling mode, the cooling tower precooling mode and the cooling tower natural cooling mode are firstly carried out step cooling and then carried out step cooling, part of step cooling-mechanical refrigeration, part of cooling tower precooling-mechanical refrigeration, the cooling tower precooling mode and the cooling tower precooling mode are firstly carried out cooling tower precooling and then carried out step cooling-part of mechanical refrigeration, and the cooling tower precooling mode are firstly carried out step cooling and then. Through the above 9 modes switching, the return water temperature of the chilled water entering the water chilling unit can be reduced to the maximum extent, so that the energy consumption and the refrigeration running cost of the water chilling unit are reduced, and the maximization of energy conservation and economic benefits is realized. The specific operation modes are as follows:

in the mechanical refrigeration mode, the first solenoid valve F1, the seventh solenoid valve F7 and the twenty-first solenoid valve F21 are opened. The mode is suitable for the condition that the outlet water temperature of the cooling tower is higher than the return water precooling requirement temperature of chilled water of the evaporator, and the step phase change cold accumulation device is fully cooled and can not provide extra cold. The chilled water is output from the output end of the chilled water circulating water pump 7, enters the air conditioner terminal equipment 8, enters the evaporator of the water chilling unit 1 through the first electromagnetic valve F1 for heat exchange, and is output from the evaporator and enters the input end of the chilled water circulating water pump 7. The cooling water is output from the cooling water circulating water pump 2, enters the main cooling tower 3 through a twenty-first electromagnetic valve F21, is output from the output end of the main cooling tower 3, enters the condenser of the water chilling unit 1 through a seventh electromagnetic valve F7 for heat exchange, and finally enters the input end of the cooling water circulating water pump 2.

And in the step cooling release mode, a second electromagnetic valve F2, a third electromagnetic valve F3, a ninth electromagnetic valve F9, a thirteenth electromagnetic valve F13, a fifteenth electromagnetic valve F15 and a sixteenth electromagnetic valve F16 are opened, and the water chilling unit and the cooling tower stop running. The mode is suitable for the condition that the outlet water temperature of the cooling tower is higher than the return water precooling requirement temperature of the chilled water of the evaporator, and the outlet water temperature of the step phase change cold accumulation device is lower than the cold supply requirement temperature of the air conditioner tail end equipment. The chilled water is output from the output end of the chilled water circulating water pump 7, enters the air conditioner terminal equipment 8, enters the cascade phase change cold accumulation device through the second electromagnetic valve F2 and the ninth electromagnetic valve F9, exchanges heat with the first-stage phase change cold accumulation unit, the second-stage phase change cold accumulation unit and the third-stage phase change cold accumulation unit in sequence, enters the evaporator (not exchanging heat) of the water chilling unit 1 through the fifteenth electromagnetic valve F15, the sixteenth electromagnetic valve F16 and the third electromagnetic valve F3, and finally enters the input end of the chilled water circulating water pump 7.

In the natural cooling mode, the second electromagnetic valve F2, the third electromagnetic valve F3, the fifth electromagnetic valve F5, the sixth electromagnetic valve F6, the tenth electromagnetic valve F10, the twelfth electromagnetic valve F12 and the twenty-first electromagnetic valve F21 are opened, and the water chilling unit stops running. The mode is suitable for the condition that the temperature of the outlet water of the cooling tower is lower than the natural cooling requirement temperature of the air-conditioning terminal equipment, and the cascade phase change cold accumulation device has sufficient cold release and can not provide extra cold. The chilled water is output from the output end of the chilled water circulating water pump 7, enters the air conditioner terminal equipment 8, passes through the second electromagnetic valve F2 and the fifth electromagnetic valve F5, then enters the plate heat exchanger 6, fully cools, passes through the tenth electromagnetic valve F10 and the third electromagnetic valve F3, enters the water chilling unit 1 (does not exchange heat), and finally enters the input end of the chilled water circulating water pump 7. The cooling water is output from the cooling water circulating water pump 2, enters the main cooling tower 3 through the twenty-first electromagnetic valve F21, is output from the output end of the main cooling tower 3, enters the plate type heat exchange heat exchanger 6 through the twelfth electromagnetic valve F12, cools the return water of the chilled water coming out of the air conditioner end equipment 8, enters the condenser of the water chilling unit 1 (without heat exchange) after passing through the sixth electromagnetic valve F6, and finally enters the input end of the cooling water circulating water pump 2.

And in the cooling tower precooling and then stepped cooling release mode, opening a second electromagnetic valve F2, a third electromagnetic valve F3, a fifth electromagnetic valve F5, a sixth electromagnetic valve F6, an eleventh electromagnetic valve F11, a twelfth electromagnetic valve F12, a fifteenth electromagnetic valve F15, a sixteenth electromagnetic valve F16 and a twenty-first electromagnetic valve F21, and stopping the water chilling unit. The mode is suitable for the condition that the outlet water temperature of the cooling tower is lower than the return water precooling requirement temperature of chilled water of the evaporator but higher than the natural cooling requirement temperature of the air conditioner terminal equipment, and the outlet water temperature of the cascade phase change cold storage device is lower than the cooling requirement temperature of the air conditioner terminal equipment. The chilled water is output from the output end of the chilled water circulating water pump 7, is output from the air conditioner terminal equipment 8, then passes through the second electromagnetic valve F2 and the fifth electromagnetic valve F5, is precooled by the plate heat exchanger 6, then enters the step phase change cold storage device 5 through the eleventh electromagnetic valve F11, exchanges heat with the first-stage phase change cold storage unit, the second-stage phase change cold storage unit and the third-stage phase change cold storage unit in sequence, then passes through the fifteenth electromagnetic valve F15, the sixteenth electromagnetic valve F16 and the third electromagnetic valve F3, enters the evaporator (no heat exchange) of the water chilling unit 1, and finally enters the input end of the chilled water circulating water pump 7. The cooling water is output from the cooling water circulating water pump 2, enters the main cooling tower 3 through the twenty-first electromagnetic valve F21, is output from the output end of the main cooling tower 3, enters the plate type heat exchange heat exchanger 6 through the twelfth electromagnetic valve F12, precools the return water of the chilled water coming out of the air conditioner tail end equipment 8, then enters the condenser of the water chilling unit 1 through the sixth electromagnetic valve F6 (no heat exchange), and finally enters the input end of the cooling water circulating water pump 2.

And (3) a step cooling-first natural cooling mode of the secondary cooling tower is adopted, a second electromagnetic valve F2, a third electromagnetic valve F3, a sixth electromagnetic valve F6, a ninth electromagnetic valve F9, a tenth electromagnetic valve F10, a twelfth electromagnetic valve F12, a seventeenth electromagnetic valve F17 and a twenty-first electromagnetic valve F21 are opened, and the water chilling unit stops running. The mode is suitable for the condition that the outlet water temperature of the cooling tower is lower than the natural cooling requirement temperature of the air conditioner terminal equipment, and the outlet water temperature of the step phase change cold accumulation device is higher than the cooling requirement temperature of the air conditioner terminal equipment but lower than the return water precooling requirement temperature of the chilled water of the evaporator. The chilled water is output from the output end of the chilled water circulating water pump 7, passes through a second electromagnetic valve F2, a ninth electromagnetic valve F9 and a thirteenth electromagnetic valve F13, is output from an air conditioner terminal device 8, and then enters the step phase change cold storage device 5, and exchanges heat with the first-stage phase change cold storage unit, the second-stage phase change cold storage unit and the third-stage phase change cold storage unit in sequence, then enters the plate heat exchanger 6 from the seventeenth electromagnetic valve F17, flows out from the plate heat exchanger 6, passes through a tenth electromagnetic valve F10 and a third electromagnetic valve F3, enters the water chilling unit 1 (without heat exchange), and finally enters the input end of the chilled water circulating water pump 7. The cooling water is output from the cooling water circulating water pump 2, enters the main cooling tower 3 through the twenty-first electromagnetic valve F21, is output from the output end of the main cooling tower 3, enters the plate type heat exchange heat exchanger 6 through the twelfth electromagnetic valve F12, cools the return water of the chilled water coming out of the step phase change cold storage device 5, then enters the condenser of the water chilling unit 1 through the sixth electromagnetic valve F6 (without heat exchange), and finally enters the input end of the cooling water circulating water pump 2.

The step cool release-partial mechanical cooling mode opens second solenoid valve F2, third solenoid valve F3, sixth solenoid valve F6, ninth solenoid valve F9, thirteenth solenoid valve F13, fifteenth solenoid valve F15, sixteenth solenoid valve F16, twenty-first solenoid valve F21. The mode is suitable for the condition that the outlet water temperature of the cooling tower is higher than the return water precooling requirement temperature of the chilled water of the evaporator, and the outlet water temperature of the step phase change cold accumulation device is higher than the cold supply requirement temperature of the air conditioner tail end equipment but lower than the return water precooling requirement temperature of the chilled water of the evaporator. The chilled water is output from the output end of the chilled water circulating water pump 7, enters the air conditioner tail end equipment 8, enters the cascade phase change cold accumulation device through a second electromagnetic valve F2, a ninth electromagnetic valve F9 and a thirteenth electromagnetic valve F13, exchanges heat with the first-stage phase change cold accumulation unit, the second-stage phase change cold accumulation unit and the third-stage phase change cold accumulation unit in sequence, enters the evaporator of the water chilling unit 1 through a fifteenth electromagnetic valve F15, a sixteenth electromagnetic valve F16 and a third electromagnetic valve F3 for heat exchange, and finally enters the input end of the chilled water circulating water pump 7. The cooling water is output from the cooling water circulating water pump 2, enters the main cooling tower 3 through a twenty-first electromagnetic valve F21, is output from the output end of the main cooling tower 3, enters the condenser of the water chilling unit 1 through a sixth electromagnetic valve F6 for heat exchange, and finally enters the input end of the cooling water circulating water pump 2.

And in the cooling tower precooling-partial mechanical refrigeration mode, opening a second electromagnetic valve F2, a third electromagnetic valve F3, a fifth electromagnetic valve F5, a sixth electromagnetic valve F6, a tenth electromagnetic valve F10, a twelfth electromagnetic valve F12 and a twenty-first electromagnetic valve F21. The mode is suitable for the condition that the temperature of the outlet water of the cooling tower is lower than the return water precooling requirement temperature of chilled water of the evaporator but higher than the cold supply requirement temperature of the air conditioner terminal equipment, and the cascade phase change cold accumulation completely releases cold and can not provide extra cold. The chilled water is output from the output end of the chilled water circulating water pump 7, enters the air conditioner tail end equipment 8, enters the plate heat exchanger 6 through the second electromagnetic valve and the fifth electromagnetic valve, enters the evaporator of the water chilling unit 1 through the tenth electromagnetic valve F10 after precooling, exchanges heat through the third electromagnetic valve F3, and finally enters the input end of the chilled water circulating water pump 7. The cooling water is output from the cooling water circulating water pump 2, the twenty-first electromagnetic valve F21 enters the main cooling tower 3, the cooling water is output from the output end of the main cooling tower 3, enters the plate type heat exchange heat exchanger 6 through the twelfth electromagnetic valve F12, precools the return water of the chilled water coming out of the air conditioner tail end equipment 8, then enters the condenser of the water chilling unit 1 through the sixth electromagnetic valve F6 for heat exchange, and finally enters the input end of the cooling water circulating water pump 2.

And in the cooling tower precooling and then cascade cooling-partial mechanical refrigeration mode, a second electromagnetic valve F2, a third electromagnetic valve F3, a fifth electromagnetic valve F5, a sixth electromagnetic valve F6, an eleventh electromagnetic valve F11, a twelfth electromagnetic valve F12, a fifteenth electromagnetic valve F15, a sixteenth electromagnetic valve F16 and a twenty-first electromagnetic valve F21 are opened. The mode is suitable for the condition that the water outlet temperature of the cooling tower and the water outlet temperature of the step phase change cold accumulation device are both lower than the backwater precooling requirement temperature of the chilled water of the evaporator but higher than the natural cooling requirement temperature of the air conditioner tail end equipment, and the water outlet temperature of the step phase change cold accumulation device is lower than the water outlet temperature of the cooling tower. The chilled water is output from the output end of the chilled water circulating water pump 7, is output from the air conditioner terminal equipment 8, then enters the plate heat exchanger 6 through the second electromagnetic valve F2 and the fifth electromagnetic valve F5, is precooled, then enters the step phase change cold storage device 5 through the eleventh electromagnetic valve F11, exchanges heat with the first-stage phase change cold storage unit, the second-stage phase change cold storage unit and the third-stage phase change cold storage unit in sequence, then enters the evaporator of the water chilling unit 1 through the fifteenth electromagnetic valve F15, the sixteenth electromagnetic valve F16 and the third electromagnetic valve F3 for heat exchange, and finally enters the input end of the chilled water circulating water pump 7. The cooling water is output from the cooling water circulating water pump 2, enters the main cooling tower 3 through a twenty-first electromagnetic valve F21, is output from the output end of the main cooling tower 3, enters the plate type heat exchange heat exchanger 6 through a twelfth electromagnetic valve F12, flows out through a sixth electromagnetic valve F6, precools the return water of the chilled water coming out of the air conditioner tail-end equipment 8, then enters the condenser of the water chilling unit 1 for heat exchange, and finally enters the input end of the cooling water circulating water pump 2.

And in a pre-cooling-part mechanical refrigeration mode of the first-step cooling-releasing and re-cooling tower, opening a second electromagnetic valve F2, a third electromagnetic valve F3, a sixth electromagnetic valve F6, a ninth electromagnetic valve F9, a tenth electromagnetic valve F10, a twelfth electromagnetic valve F12, a thirteenth electromagnetic valve F13, a seventeenth electromagnetic valve F17 and a twenty-first electromagnetic valve F21, and stopping the running of the water chilling unit. The mode is suitable for the condition that the water outlet temperature of the cooling tower and the water outlet temperature of the step phase change cold accumulation device are both lower than the backwater precooling requirement temperature of the chilled water of the evaporator but higher than the natural cooling requirement temperature of the air conditioner tail end equipment, and the water outlet temperature of the cooling tower is lower than the water outlet temperature of the step phase change cold accumulation device. The chilled water is output from the output end of the chilled water circulating water pump 7, after being output from the air conditioner terminal equipment 8, the chilled water firstly enters the step phase change cold accumulation device 5 through the second electromagnetic valve F2, the ninth electromagnetic valve F9 and the thirteenth electromagnetic valve F13, exchanges heat with the first-stage phase change cold accumulation unit, the second-stage phase change cold accumulation unit and the third-stage phase change cold accumulation unit in sequence, then enters the plate heat exchanger 6 through the seventeenth electromagnetic valve F17, then enters the water chilling unit 1 through the tenth electromagnetic valve F10 and the third electromagnetic valve F3 to exchange heat, and finally enters the input end of the chilled water circulating water pump 7. The cooling water is output from the cooling water circulating water pump 2, enters the main cooling tower 3 through the twenty-first electromagnetic valve F21, is output from the output end of the main cooling tower 3, enters the plate type heat exchange heat exchanger 6 through the twelfth electromagnetic valve F12, is cooled, flows out from the chilled water return water from the step phase change cold storage device 5 through the sixth electromagnetic valve F6, then enters the condenser of the water chilling unit 1 for heat exchange, and finally enters the input end of the cooling water circulating water pump 2.

Claims

1. A multi-mode refrigerating system of a cascade cold accumulation-release type data machine room is characterized by comprising:

2. The multi-mode refrigeration system of a stepped cold accumulation-release type data room of claim, characterized in that: the first-stage phase-change material adopts octanoic acid with phase-change temperature, the second-stage phase-change material adopts dipotassium phosphate hexahydrate with phase-change temperature, and the third-stage phase-change material adopts pentadecane with phase-change temperature.

3. The multi-mode refrigeration system of a cascade cold accumulation-release type data room of claim or wherein: the main cooling tower and the auxiliary cooling tower are cooling towers of the same type.