CN116170994A

CN116170994A - Indirect evaporative cooling unit, data center and refrigeration control method of indirect evaporative cooling unit

Info

Publication number: CN116170994A
Application number: CN202111408665.2A
Authority: CN
Inventors: 居静; 吴四海; 陆涛; 王正华; 冯淑琴; 刘交通; 崔振军; 何剑荣
Original assignee: Hebei Qinhuai Data Co Ltd
Current assignee: Hebei Qinhuai Data Co Ltd
Priority date: 2021-11-24
Filing date: 2021-11-24
Publication date: 2023-05-26
Also published as: WO2023092873A1

Abstract

The application discloses an indirect evaporative cooling unit, which includes a heat exchange core, a spray assembly and a mechanical refrigeration assembly; the heat exchange core has an inner circulation air inlet, an inner circulation air outlet, an outer circulation air inlet and an outer Circulation air outlet; the internal circulation air outlet is provided with an internal circulation fan assembly, and the external circulation air outlet is provided with an external circulation fan assembly, and the speeds of the internal circulation fan assembly and the external circulation fan assembly can be adjusted; The mechanical refrigeration assembly includes a compressor, a condenser, an electronic expansion valve, and an evaporator; the compressor, condenser, electronic expansion valve, and evaporator are connected in series to form a circulation loop, and the electronic expansion valve is used for The flow rate of the refrigerant in the circulation loop is adjusted. The application can perform refrigeration adjustment according to real-time temperature changes and seasonal conditions to reduce energy consumption.

Description

Indirect evaporative cooling unit, data center and refrigeration control method of indirect evaporative cooling unit

Technical Field

The application relates to the field of refrigeration regulation of data centers, in particular to an indirect evaporative cooling unit, a data center and a refrigeration control method thereof.

Background

With the development of data center scale and integration, the power density of server equipment is increased, and the heat density is increased, so that two problems are brought about: on one hand, the electric quantity consumed in the machine room is greatly increased; on the other hand, the problem of heat dissipation of the server becomes more and more serious, a large amount of energy is consumed, and equipment is stopped due to the fact that cooling adjustment is not reasonable enough and equipment generates heat.

The existing data center refrigerating equipment is single in mode, energy consumption cannot be reduced by utilizing seasonal and day-and-night temperature difference changes, natural cold sources are low in utilization, the temperature of a data machine room cannot be reasonably regulated and controlled, the traditional evaporative cooling unit is not matched with the load of a cooling side in spray cooling, excessive water consumption is caused, mechanical refrigeration investment is unreasonable in time, long in running time, high in energy consumption and the like, electric energy consumed by refrigeration accounts for more than 35% of the energy consumption of the machine room, the refrigerating effect is still to be improved, and certain difficulty is brought to daily management work of the data center.

Therefore, it is highly desirable to design an indirect evaporative cooling unit capable of being adjusted in a variable speed manner, and complete the accurate refrigeration adjustment of the annual operation of a data center machine room, so that the problems of low utilization rate of a refrigeration natural cold source, high energy consumption and the like of the data center are solved.

Disclosure of Invention

The utility model aims to provide an indirect evaporative cooling unit, data center and refrigeration control method thereof, can carry out refrigeration regulation according to real-time temperature, reduce the energy consumption.

In order to achieve the above purpose, in one aspect, the present application provides an indirect evaporative cooling unit, including a heat exchange core, a spray assembly and a mechanical refrigeration assembly; the heat exchange core body is provided with an inner circulation air inlet, an inner circulation air outlet, an outer circulation air inlet and an outer circulation air outlet; an inner circulating fan assembly is arranged at the inner circulating air outlet, an outer circulating fan assembly is arranged at the outer circulating air outlet, and the rotating speeds of the inner circulating fan assembly and the outer circulating fan assembly are adjustable; the mechanical refrigeration component comprises a compressor, a condenser, an electronic expansion valve and an evaporator; the compressor, the condenser, the electronic expansion valve and the evaporator are connected in series through pipelines to form a circulation loop, and the electronic expansion valve is used for adjusting the flow of the refrigerant in the circulation loop.

As a further improvement of the above technical scheme: the two electronic expansion valves are specifically a first electronic expansion valve and a second electronic expansion valve respectively; the first electronic expansion valve and the second electronic expansion valve are connected in series between the condenser and the evaporator, a drying filter is connected in series between the second electronic expansion valve and the condenser, and the second electronic expansion valve and the drying filter are connected in parallel with the first electronic expansion valve.

As a further improvement of the above technical scheme: the condenser is positioned between the outer circulation air outlet and the outer circulation fan assembly; the evaporator is positioned between the inner circulation air outlet and the inner circulation fan assembly.

As a further improvement of the above technical scheme: the spraying assembly comprises a liquid storage tank, a spraying part and a water pump; the water outlet of the liquid storage tank is connected with a water pump and a spraying part through another pipeline, and the water pump is used for extracting the refrigerating fluid from the liquid storage tank so as to enable the refrigerating fluid to be sprayed onto the heat exchange core body from the spraying part; the flow of the water pump is adjustable; the spraying part comprises a first spraying head and a second spraying head; the first spray header and the outer circulation air inlet are correspondingly arranged, and the outer circulation air outlet and the second spray header are correspondingly arranged.

In order to achieve the above object, another aspect of the present application further provides a data center, including an area to be cooled and the indirect evaporative cooling unit described above; the indirect evaporative cooling unit is connected to one side of the region to be cooled; the external circulation air inlet and the external circulation air outlet of the indirect evaporative cooling unit are communicated with the external air of the data center, so that external cooling circulation is formed; and the internal circulation air inlet and the internal circulation air outlet of the indirect evaporative cooling unit are communicated with the inside of the region to be cooled, so that an internal cooling circulation is formed.

As a further improvement of the above technical scheme: and a temperature sensor and a humidity sensor are arranged in the region to be cooled.

In order to achieve the above object, another aspect of the present application further provides a refrigeration control method for a data center, including: the refrigeration control mode is divided into four refrigeration modes, namely a mode one, a mode two, a mode three and a mode four;

when the mode one starts up: the external circulation fan assembly and the internal circulation fan assembly act, and the external cooling circulation and the internal cooling circulation exchange heat at the heat exchange core;

when the mode two is started: the outer circulating fan assembly, the inner circulating fan assembly and the spraying assembly act simultaneously to spray air flowing through the external cooling circulation, and evaporation heat absorption after spraying and the external cooling circulation exchange heat with the internal cooling circulation through the heat exchange core;

when the mode three is started: the outer circulation fan assembly, the inner circulation fan assembly, the spraying assembly and the mechanical refrigeration assembly act simultaneously, at the moment, the first electronic expansion valve is opened, the second electronic expansion valve is closed, and mechanical refrigeration is carried out on the air outlet of the inner circulation air outlet;

when the mode four is started: on the basis of the third mode, the first electronic expansion valve is closed, the second electronic expansion valve is opened, and at the moment, the circulating loop of the mechanical refrigeration assembly flows through the dry filter, so that the dehumidification treatment is performed while the mechanical refrigeration is performed on the air outlet of the inner circulation air outlet.

As a further improvement of the above technical scheme: based on the judgment of different seasons and humidity sensors, selecting to start one of the mode one, the mode two, the mode three and the mode four;

when in winter, the mode one is started; when in spring or autumn, the mode II is started; when in summer, the mode III is started; after the mode III is started, judging whether to start the mode IV based on the detection result of the humidity sensor; when the detection result is greater than a threshold value, the mode four is started; in any mode, the temperature of the air inlet of the region to be cooled can be adjusted in real time according to the detection value of the temperature sensor and the preset target temperature value.

Therefore, according to the technical scheme provided by the application, different operation modes are selected according to different seasons and humidity conditions, the outside air temperature in different seasons is reasonably utilized for heat dissipation, and the energy consumption is reduced; meanwhile, according to daily day-to-day temperature difference change, the temperature sensor is utilized to detect and accurately adjust the rotating speed of the outer circulating fan assembly, the rotating speed of the inner circulating fan assembly, the flow of the water pump and the flow of the electronic expansion valve, so that the timely heat dissipation requirement of the server is met, a natural cold source is utilized to the maximum extent, and the reduction of the energy consumption of an air conditioner of a data machine room is also met; further, the condenser is arranged between the external circulation air outlet and the external circulation fan assembly, so that the condenser can be cooled while external cooling circulation is operated, and the external circulation fan assembly is reasonably utilized; and two spray heads are arranged to spray at the external circulation air inlet and the external circulation air outlet, so that the spray cooling effect is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of an embodiment of an indirect evaporative cooling unit provided herein;

FIG. 2 is a schematic diagram of a data center in one embodiment provided herein;

in the figure: 1. a heat exchange core; 11. an internal circulation air inlet; 12. an internal circulation air outlet; 13. an external circulation air inlet; 14. an external circulation air outlet; 2. a spray assembly; 21. a liquid storage tank; 221. a first showerhead; 222. A second showerhead; 23. a water pump; 3. a mechanical refrigeration assembly; 31. a compressor; 32. a condenser; 331. A first electronic expansion valve; 332. a second electronic expansion valve; 333. drying the filter; 34. an evaporator; 4. An internal circulation fan assembly; 5. an external circulation fan assembly; 6. a region to be cooled; 61. a temperature sensor; 62. A humidity sensor.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the embodiments of the present application will be described in further detail below with reference to the accompanying drawings. Terms such as "upper," "lower," "first end," "second end," "one end," "the other end," and the like as used herein to refer to a spatially relative position are used for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. The term spatially relative position may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Furthermore, the terms "mounted," "disposed," "provided," "connected," "slidingly connected," "secured," and "sleeved" are to be construed broadly. For example, "connected" may be in a fixed connection, a removable connection, or a unitary construction; may be a mechanical connection, or an electrical connection; may be directly connected, or indirectly connected through intervening media, or may be in internal communication between two devices, elements, or components. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.

The existing data center refrigerating equipment is single in mode, energy consumption cannot be reduced by utilizing seasonal and day-and-night temperature difference changes, natural cold sources are low in utilization, the temperature of a data machine room cannot be reasonably regulated and controlled, the traditional evaporative cooling unit is not matched with the load of a cooling side in spray cooling, excessive water consumption is caused, mechanical refrigeration investment is unreasonable in time, long in running time, high in energy consumption and the like, electric energy consumed by refrigeration accounts for more than 35% of the energy consumption of the machine room, the refrigerating effect is still to be improved, and certain difficulty is brought to daily management work of the data center. Therefore, it is highly desirable to design an indirect evaporative cooling unit capable of being adjusted in a variable speed manner, and complete the accurate refrigeration adjustment of the annual operation of a data center machine room, so that the problems of low utilization rate of a refrigeration natural cold source, high energy consumption and the like of the data center are solved.

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. It should be apparent that the embodiments described herein are only some, but not all, of the embodiments of the present application. All other embodiments, based on the embodiments herein, which are within the scope of the protection of the present application, will be within the skill of the art without undue effort.

As shown in fig. 1, in one possible embodiment, an indirect evaporative cooling unit includes a heat exchange core 1, a spray assembly 2, and a mechanical refrigeration assembly 3; the heat exchange core 1 is provided with an inner circulation air inlet 11, an inner circulation air outlet 12, an outer circulation air inlet 13 and an outer circulation air outlet 14; the heat exchange core 1 is common knowledge in the art, and the principle of the heat exchange core is that two groups of mutually-intersected and non-communicated air channels are arranged on one heat exchange body, and the air in the two air channels exchanges heat when passing through the heat exchange body; the spraying assembly 2 sprays the air of the external circulation air inlet 13 and the external circulation air outlet 14 and the heat exchange core 1 (and ensures that the sprayed refrigerating fluid does not enter the internal circulation air inlet 11 and the internal circulation air outlet 12), the sprayed water mist evaporates, absorbs the heat in the outdoor air, cools the outdoor air to be lower than the wet bulb temperature of the outdoor air to be close to the dew point temperature, realizes the cooling, and the water which is not evaporated flows into the liquid storage tank 21 to form recirculation; the mechanical refrigeration component 3 adopts a mechanical refrigeration mode to cool the air outlet of the internal circulation air outlet 12, so that the refrigeration effect is improved.

In order to realize the heat exchange between the air external circulation and the air internal circulation, an internal circulation fan assembly 4 is arranged at an internal circulation air outlet 12, an external circulation fan assembly 5 is arranged at an external circulation air outlet 14, and the rotation speeds of the internal circulation fan assembly 4 and the external circulation fan assembly 5 are ensured to be adjustable;

for the mechanical refrigeration assembly 3, it specifically includes a compressor 31, a condenser 32, an electronic expansion valve and an evaporator 34; the compressor 31, the condenser 32, the electronic expansion valve and the evaporator 34 are connected in series through pipelines to form a circulation loop, and the electronic expansion valve is used for adjusting the flow of the refrigerant in the circulation loop; the operation principle is that after the refrigerant is compressed and discharged by the compressor 31, the refrigerant enters the condenser 32 to be condensed, and then the refrigerant enters the evaporator 34 to evaporate and absorb the heat in the air discharged by the internal circulation air outlet 12 under the current limitation of the electronic expansion valve, so as to perform circulation mechanical refrigeration; the flow rate of the electronic expansion valve is adjusted to control the refrigerating capacity of mechanical refrigeration, and the variable-frequency compressor 31 can be adopted to adjust the refrigerating capacity of mechanical refrigeration through frequency adjustment.

Further, in order to realize the dehumidification function, the electronic expansion valves in the embodiments of the present application specifically include two electronic expansion valves, namely, a first electronic expansion valve 331 and a second electronic expansion valve 332; the first electronic expansion valve 331 and the second electronic expansion valve 332 are connected in series between the condenser 32 and the evaporator 34, the second electronic expansion valve 332 and the condenser 32 are connected in series with the dry filter 333, and the second electronic expansion valve 332 and the dry filter 333 are connected in parallel with the first electronic expansion valve 331; two circulation loops are realized through the on-off selection of the first electronic expansion valve 331 and the second electronic expansion valve 332; a circulation loop, which passes through the first electronic expansion valve 331 and does not have a dehumidification function; the other circulation circuit has a dehumidification function through the dry filter 333 and the second electronic expansion valve 332.

Preferably, the condenser 32 is located between the outer circulation air outlet 14 and the outer circulation fan assembly 5; the condenser can be cooled while the external cooling circulation is operated, and the external circulation fan assembly is reasonably utilized; the evaporator 34 is positioned between the inner circulation air outlet 12 and the inner circulation fan assembly 4, so that the temperature of the air outlet of the inner circulation air outlet 12 is reduced.

In practical application, the spray assembly 2 comprises a liquid storage tank 21, a spray part and a water pump 23; the water outlet of the liquid storage tank 21 is connected with a water pump 23 and a spraying part through another pipeline, and the water pump 23 is used for extracting the refrigerating fluid from the liquid storage tank 21 so as to enable the refrigerating fluid to be sprayed onto the heat exchange core body 1 from the spraying part; the flow rate of the water pump 23 is adjustable so as to perform real-time adjustment according to the change of the temperature sensor 61;

the flow rate of the water pump 23 can be adjusted in various ways, namely, speed change adjustment: the rotating speed of the water pump is changed, so that the performance of the water pump is changed, and the working condition point of the water pump is changed, and the method is called speed change adjustment; 2. reducing adjustment: after the impeller is turned, the performance of the water pump is changed according to a certain rule, so that the working condition point of the water pump is changed, and the method for turning the impeller to change the working condition point of the water pump is called reducing adjustment; 3. throttle adjustment: for the water pump device with the gate valve installed on the water outlet pipeline, when the gate valve is closed, local resistance is increased in the pipeline, the pipeline characteristic curve becomes steep, and the working point of the pipeline characteristic curve moves leftwards and upwards along the Q-H curve of the water pump. The smaller the gate valve is, the larger the increased resistance is, and the smaller the flow becomes, and the method for changing the working point of the water pump by closing the gate valve is called throttling adjustment or variable valve adjustment; in the present application, in order to achieve the energy saving effect, it is preferable to employ a variable speed adjustment for the water pump 23, thereby reducing the energy consumption.

Further, in order to improve the spray effect, the spray part includes a first spray header 221 and a second spray header 222; the first shower head 221 is disposed corresponding to the outer circulation air inlet 13, and the outer circulation air outlet 14 is disposed corresponding to the second shower head 222.

With particular reference to fig. 2, based on the same inventive concept, the present application also provides a data center comprising an area to be cooled 6 and the above-mentioned indirect evaporative cooling unit; the indirect evaporative cooling unit is connected to one side of the region 6 to be cooled; the area 6 to be cooled in the present application may be a machine room area or a power distribution room.

The external circulation air inlet 13 and the external circulation air outlet 14 of the indirect evaporative cooling unit are communicated with the external air of the data center, so that external cooling circulation is formed, and the external cooling circulation path is specifically shown in the arrow direction of the external circulation air inlet 13, the heat exchange core 1, the external circulation air outlet 14, the condenser 32 and the external circulation fan assembly 5 in sequence in fig. 2, so that the external air flows in and flows out into the external air;

the internal circulation air inlet 11 and the internal circulation air outlet 12 of the indirect evaporative cooling unit are communicated with the interior of the region to be cooled 6, so that an internal cooling circulation is formed, and the path of the internal cooling circulation is specifically shown in the arrow direction of the primary-pass internal circulation air inlet 11, the heat exchange core 1, the internal circulation air outlet 12, the evaporator 34 and the internal circulation fan assembly 4 in fig. 2, flows in from the region to be cooled 6 and flows out into the region to be cooled 6;

and, be equipped with temperature sensor 61 and humidity transducer 62 in waiting to cool off regional 6, temperature sensor 61 is used for detecting the temperature in waiting to cool off regional 6, and humidity transducer 62 is used for detecting the humidity in waiting to cool off regional 6, and corresponding still need set up a control terminal, receive temperature sensor 61 and humidity transducer 62's signal to unified coordination heat exchange core 1, spray subassembly 2 and mechanical refrigeration subassembly 3's the switching condition.

Based on the same inventive concept, the application also provides a refrigeration control method of the data center, which comprises the following steps: the refrigeration control mode of the indirect evaporative cooling unit is divided into four refrigeration modes, namely a mode one, a mode two, a mode three and a mode four;

when mode one starts up: the external circulation fan assembly 5 and the internal circulation fan assembly 4 act under the condition that the temperature of external air is low, the external cooling circulation and the internal cooling circulation exchange heat at the heat exchange core body 1, and the external air exchanges heat with the internal cooling circulation air directly to cool the region 6 to be cooled;

when mode two starts: the external circulation fan assembly 5, the internal circulation fan assembly 4 and the spraying assembly 2 are operated simultaneously under the condition of higher external air temperature, air flowing through external cooling circulation is sprayed, and evaporation heat absorption after spraying and external cooling circulation are used for exchanging heat with the internal cooling circulation through the heat exchange core body 1, so that the cooling effect of the area 6 to be cooled is improved;

when mode three is started: the external circulation fan assembly 5, the internal circulation fan assembly 4, the spraying assembly 2 and the mechanical refrigeration assembly 3 are operated simultaneously under the condition that the external air temperature is higher, at the moment, the first electronic expansion valve 331 is opened, the second electronic expansion valve 332 is closed, the mechanical refrigeration is carried out on the air outlet of the internal circulation air outlet 12, at the moment, the evaporation heat absorption after spraying and the external cooling circulation are used for exchanging heat with the internal cooling circulation through the heat exchange core body 1, and then the temperature is reduced through the evaporator 34, so that the temperature reduction effect of the area 6 to be cooled is further improved;

when mode four is enabled: the first electronic expansion valve 331 is closed and the second electronic expansion valve 332 is opened on the basis of the third mode under the condition that the temperature of the external air is higher and the humidity is too high, and at the moment, the circulation loop of the mechanical refrigeration assembly 3 flows through the dry filter 333, so that the dehumidification treatment is performed while the mechanical refrigeration is performed on the air outlet of the internal circulation air outlet 12, namely, the cooling effect of the third mode is achieved, and meanwhile, the dehumidification function is achieved.

Further, the present application selects one of the first, second, third and fourth modes of activation based on the different seasons and humidity sensor 62 determinations;

specifically, when in winter, mode one is started; when the device is in spring or autumn, the mode II is started; when in summer, the mode III is started; after the mode III is started, judging whether to start the mode IV based on the detection result of the humidity sensor 62; when the detection result is greater than the threshold value, the mode four is started, wherein the threshold value refers to a preset allowable humidity value in the region 6 to be cooled.

Furthermore, taking into account the change of the temperature difference between day and night, the external air is reasonably utilized, the energy consumption is effectively reduced, the refrigerating effect of the region 6 to be cooled is ensured, the temperature of the air inlet of the region 6 to be cooled can be adjusted in real time according to the detection value of the temperature sensor 61 and the preset target temperature value in any mode, and it is to be explained that the preset target temperature value here refers to the temperature value which can meet the working condition in the region 6 to be cooled, and the temperature value is set in the program in advance for the staff.

The specific real-time adjustment mode is as follows: in the mode one startup case: when the detected value is smaller than the target temperature value, the rotating speed of the outer circulation fan assembly 5 and/or the inner circulation fan assembly 4 is reduced; when the detected value is greater than the target temperature value, the rotation speed of the outer circulation fan assembly 5 and/or the inner circulation fan assembly 4 is increased.

In the mode two start-up case: when the detected value is smaller than the target temperature value, at least one of the rotation speed of the outer circulation fan assembly 5, the rotation speed of the inner circulation fan assembly 4, and the flow rate of the water pump 23 (i.e., the rotation speed of the water pump 23 is reduced); when the detected value is greater than the target temperature value, at least one of the rotation speed of the outer circulation fan assembly 5, the rotation speed of the inner circulation fan assembly 4, and the flow rate of the water pump 23 is increased.

In the mode three start case: when the detected value is less than the target temperature value, at least one of the rotation speed of the outer circulation fan assembly 5, the rotation speed of the inner circulation fan assembly 4, the flow rate of the water pump 23, the flow rate of the first electronic expansion valve 331, and the frequency of the compressor 31 is reduced; when the detected value is greater than the target temperature value, at least one of the rotation speed of the outer circulation fan assembly 5, the rotation speed of the inner circulation fan assembly 4, the flow rate of the water pump 23, the flow rate of the first electronic expansion valve 331, and the frequency of the compressor 31 is increased.

In the mode four start-up case: when the detected value is less than the target temperature value, at least one of the rotation speed of the outer circulation fan assembly 5, the rotation speed of the inner circulation fan assembly 4, the flow rate of the water pump 23, the flow rate of the second electronic expansion valve 332, and the frequency of the compressor 31 is reduced; when the detected value is greater than the target temperature value, at least one of the rotation speed of the outer circulation fan assembly 5, the rotation speed of the inner circulation fan assembly 4, the flow rate of the water pump 23, the flow rate of the second electronic expansion valve 332, and the frequency of the compressor 31 is increased.

The foregoing description of the preferred embodiments of the present application is not intended to limit the invention to the particular embodiments of the present application, but to limit the scope of the invention to the particular embodiments of the present application.

Claims

1. An indirect evaporative cooling unit, comprising a heat exchange core (1), a spray assembly (2) and a mechanical refrigeration assembly (3); the heat exchange core (1) has an internal circulation air inlet (11) , an inner circulation air outlet (12), an outer circulation air inlet (13) and an outer circulation air outlet (14); it is characterized in that,

The inner circulation air outlet (12) is provided with an inner circulation fan assembly (4), the outer circulation air outlet (14) is provided with an outer circulation fan assembly (5), and the inner circulation fan assembly (4) and The rotating speed of the external circulation fan assembly (5) can be adjusted;

The mechanical refrigeration assembly (3) includes a compressor (31), a condenser (32), an electronic expansion valve and an evaporator (34); the compressor (31), the condenser (32), an electronic expansion valve and an evaporator The devices (34) are connected in series through pipelines to form a circulation loop, and the electronic expansion valve is used to adjust the flow of refrigerant in the circulation loop.

2. The indirect evaporative cooling unit according to claim 1, characterized in that there are two electronic expansion valves, namely a first electronic expansion valve (331) and a second electronic expansion valve (332);

The first electronic expansion valve (331) and the second electronic expansion valve (332) are connected in series between the condenser (32) and the evaporator (34), and the second electronic expansion valve (332 ) and the condenser (32) are connected in series with a dry filter (333), and the second electronic expansion valve (332) and the dry filter (333) are connected with the first electronic expansion valve (331 )in parallel.

3. The indirect evaporative cooling unit according to claim 2, characterized in that, the condenser (32) is located between the outer circulation air outlet (14) and the outer circulation fan assembly (5); The evaporator (34) is located between the internal circulation air outlet (12) and the internal circulation fan assembly (4).

4. The indirect evaporative cooling unit according to any one of claims 1 to 3, characterized in that the spray assembly (2) includes a liquid storage tank (21), a spray part and a water pump (23);

The water outlet of the liquid storage tank (21) is connected with a water pump (23) and a spraying part through another pipeline, and the water pump (23) is used to extract refrigerant liquid from the liquid storage tank (21) to The refrigerant liquid is sprayed from the spraying part onto the heat exchange core (1); the flow rate of the water pump (23) is adjustable.

5. The indirect evaporative cooling unit according to claim 4, characterized in that, the spray part comprises a first spray head (221) and a second spray head (222); the first spray head ( 221) is arranged corresponding to the outer circulation air inlet (13), and the outer circulation air outlet (14) is arranged corresponding to the second shower head (222).

6. A data center, characterized in that it comprises an area to be cooled (6) and the indirect evaporative cooling unit according to claim 4 or 5; the indirect evaporative cooling unit is connected to one side of the area to be cooled (6) ;

The outer circulation air inlet (13) and the outer circulation air outlet (14) of the indirect evaporative cooling unit communicate with the outside air of the data center, thereby forming an external cooling cycle; the inner circulation air intake of the indirect evaporative cooling unit The port (11) and the internal circulation air outlet (12) are in communication with the area to be cooled (6), thereby forming an internal cooling cycle.

7. The data center according to claim 6, characterized in that a temperature sensor (61) and a humidity sensor (62) are provided in the area to be cooled (6).

8. A cooling control method based on the data center according to claim 7, characterized in that it comprises: dividing the cooling control mode into four cooling modes, namely mode 1, mode 2, mode 3 and mode 4;

When the first mode is activated: the external circulation fan assembly (5) and the internal circulation fan assembly (4) operate, the external cooling cycle and the internal cooling cycle are in the heat exchange core (1) for heat exchange;

When the second mode starts: the outer circulation fan assembly (5), the inner circulation fan assembly (4) and the spray assembly (2) act simultaneously to spray the air flowing through the external cooling cycle Showering, after spraying, the evaporation absorbs heat and the external cooling cycle passes through the heat exchange core (1) to exchange heat with the internal cooling cycle;

When the mode three starts: the outer circulation fan assembly (5), the inner circulation fan assembly (4), the spray assembly (2) and the mechanical refrigeration assembly (3) act simultaneously, at this time , the first electronic expansion valve (331) is opened, the second electronic expansion valve (332) is closed, and the air outlet of the internal circulation air outlet (12) is mechanically refrigerated;

When the mode four starts: on the basis of the mode three, the first electronic expansion valve (331) is closed, and the second electronic expansion valve (332) is opened, at this time, the mechanical refrigeration assembly ( 3) The circulation loop flows through the drying filter (333), so as to perform dehumidification treatment while performing mechanical refrigeration on the air outlet of the internal circulation air outlet (12).

9. The refrigeration control method according to claim 8, characterized in that, based on different seasons and the judgment of the humidity sensor (62), one of the mode 1, mode 2, mode 3 and mode 4 is selected to start;

When in winter, the first mode is started; when in spring or autumn, the second mode is started; when in summer, the third mode is started; after the third mode is started, based on the humidity sensor (62) The detection result determines whether to activate the mode four; wherein, when the detection result is greater than a threshold, the mode four is activated.

10. The refrigeration control method according to claim 9, characterized in that, in any mode, the temperature of the air inlet of the area to be cooled (6) can be adjusted according to the detected value of the temperature sensor (61) and the predicted value. The size of the set target temperature value can be adjusted in real time.

11. The refrigeration control method according to claim 10, characterized in that, in the case of starting mode one: when the detected value is less than the target temperature value, reduce the external circulation fan assembly (5) and/or The rotating speed of described internal circulation fan assembly (4);

When the detected value is greater than the target temperature value, the speed of the outer circulation fan assembly (5) and/or the inner circulation fan assembly (4) is increased.

12. The refrigeration control method according to claim 11, characterized in that, in the case of mode two startup: when the detected value is less than the target temperature value, at least reduce the speed of the external circulation fan assembly (5) 1. One of the rotating speed of the internal circulation fan assembly (4) and the flow rate of the water pump (23);

When the detection value is greater than the target temperature value, at least one of the rotation speed of the outer circulation fan assembly (5), the rotation speed of the inner circulation fan assembly (4) and the flow rate of the water pump (23) is increased.

13. The refrigeration control method according to claim 12, characterized in that, in the case of mode three startup: when the detected value is less than the target temperature value, at least reduce the speed of the external circulation fan assembly (5) , one of the rotating speed of the internal circulation fan assembly (4), the flow rate of the water pump (23) and the flow rate of the first electronic expansion valve (331);

When the detected value is greater than the target temperature value, at least increase the rotation speed of the outer circulation fan assembly (5), the rotation speed of the inner circulation fan assembly (4), the flow rate of the water pump (23) and the One of the flows of the first electronic expansion valve (331).

14. The refrigeration control method according to claim 13, characterized in that, in the case of mode four startup: when the detected value is less than the target temperature value, at least reduce the speed of the external circulation fan assembly (5) , one of the speed of the internal circulation fan assembly (4), the flow of the water pump (23) and the flow of the second electronic expansion valve (332);

When the detected value is greater than the target temperature value, at least increase the rotation speed of the outer circulation fan assembly (5), the rotation speed of the inner circulation fan assembly (4), the flow rate of the water pump (23) and the One of the flows of the second electronic expansion valve (332).