CN110594898A - Water-saving air-conditioning system for machine room with closed cooling water and chilled water running in series - Google Patents

Abstract

The invention belongs to air treatment equipment in the field of heating and ventilation air conditioners, and particularly relates to a machine room water-saving air conditioning system with closed cooling water and chilled water capable of running in series. The invention has reasonable structure, can improve the operation safety of the system, avoid the problems of freezing and blockage of an open cooling water system, reduce water consumption, realize water saving, fully utilize natural cooling and reduce energy consumption.

Description

Water-saving air-conditioning system for machine room with closed cooling water and chilled water running in series

technical field

The invention belongs to air treatment equipment in the field of heating, ventilating and air conditioning, in particular to a water-saving air conditioning system for a machine room in which closed cooling water and chilled water can operate in series.

Background technique

In recent years, more and more data center computer rooms of different scales have been built all over the country. Due to the high heat density of the computer room, the heat generation per unit area of the computer room has increased to 500-2000W/㎡. The power consumption accounts for 30% to 40% of the power consumption of the cabinets in the computer room. In the data center computer room, it is generally necessary to set up a ventilation and air-conditioning system that runs throughout the year. In the usual traditional mechanical refrigeration and air-conditioning system, the cooling water system is indispensable. The conventional method is to use the open cooling tower to produce cold water to take away the heat, but When the open cooling tower is running in winter, the cooling tower is prone to freezing, and the open cooling water system has many problems such as poor water quality and blockage of the heat exchange coil. The widely used closed cooling tower solves the clogging problem caused by the open cooling water, but usually needs to open the spray water system to cool the cooling water in the closed coil by making cold water, which may cause water consumption The increase, in some areas where water resources are relatively scarce, the application is limited.

CN201621426795.3 discloses an air-conditioning cooling device that operates throughout the year. This patent application combines an air-cooled mechanical refrigeration unit with an evaporative refrigeration unit, and uses the air-cooled mechanical refrigeration unit for supplementary refrigeration. The evaporative refrigeration unit cools the air through a direct evaporative cooling device. , and further use the low-temperature air to pass through the surface heat exchanger to prepare the low-temperature cold-carrying medium required by the air-conditioning system. Among them, the cold-carrying medium is closed-loop, and the system safety is high. By combining with the air-cooled mechanical refrigeration unit, the safety of the air conditioner is improved.

Contents of the invention

The purpose of the present invention is to provide a water-saving air-conditioning system for machine rooms in which closed cooling water and chilled water can be operated in series. It has a reasonable structure, can improve the safety of system operation, and avoid the problems of icing and blockage in the open cooling water system. , can reduce water consumption, realize water saving, make full use of natural cooling, and reduce energy consumption.

The object of the present invention is achieved as follows: a water-saving air-conditioning system for a machine room in which closed cooling water and chilled water can operate in series, including a dry-type indirect evaporative refrigeration unit and a mechanical refrigeration unit, wherein the dry-type indirect evaporative refrigeration unit includes a direct evaporative refrigeration unit Refrigerating device, surface heat exchanger, exhaust fan and chassis, the outlet pipe of the surface heat exchanger is connected to the inlet of the evaporator of the first mechanical refrigeration unit through the first circulation pump, and the outlet pipe of the evaporator is connected to the first evaporator through the user The inlet of the condenser of the mechanical refrigeration unit, and the outlet pipe of the condenser is connected to the inlet of the surface heat exchanger.

The invention combines a dry indirect evaporative chiller with a water-cooled mechanical refrigerating unit, and supplements refrigeration through the water-cooled mechanical refrigerating unit, thereby improving the year-round operating safety of the system. Use the outdoor air to cool the air-conditioning cooling medium of the surface heat exchanger coil. It is used for air-conditioning users. During most of the year, the spray water system and the mechanical refrigeration unit can be turned off, and the outdoor low-temperature air is used for dry-type cooling. Natural cooling to achieve water-saving and energy-saving operation; in some time periods, when the outdoor air temperature is relatively high, by turning on the direct evaporative cooling device, the air cools the cooling medium in the surface heat exchanger coil after being cooled by direct evaporative cooling ; When the outlet water temperature of the cooling medium in the surface heat exchanger coil is relatively high, this part of the cooling medium will be cooled by the mechanical refrigeration unit first, and the temperature will be lowered to be used for cooling by the air conditioner user, and the user’s liquid will be used as a mechanical refrigeration unit The cooling water is used, and the mechanical refrigeration unit is used as auxiliary cooling to make full use of natural cooling and reduce energy consumption.

advantage:

1. The cooling water system of the mechanical refrigeration unit operates in closed mode, which improves the safety of system operation and avoids the problems of freezing and blockage in the open cooling water system;

2. Use outdoor air for natural cooling during part of the year, reducing water consumption and saving water;

3. During part of the year, the closed cooling water enters the mechanical refrigeration unit for further cooling, and is used for cooling by air conditioners, and then used as cooling water for the condenser of the mechanical refrigeration unit, which reduces the configuration of the mechanical refrigeration unit;

4. In order to better prevent freezing, the cooling medium in the closed cooling water system can be antifreeze, such as ethylene glycol.

The invention has a reasonable structure, improves the safety of system operation, avoids the problems of freezing and blockage in the open cooling water system, reduces water consumption, realizes water saving, makes full use of natural cooling, and reduces energy consumption.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings. Fig. 1 is a schematic structural view of embodiment 1 of the present invention, Fig. 2 is a schematic structural view of embodiment 2 of the present invention, Fig. 3 is a schematic structural view of embodiment 3 of the present invention, and Fig. 4 is a schematic structural view of the present invention The structural diagram of Embodiment 4, FIG. 5 is a schematic structural diagram of Embodiment 5 of the present invention, FIG. 6 is a schematic structural diagram of Embodiment 6 of the present invention, and FIG. 7 is a schematic structural diagram of Embodiment 7 of the present invention.

Detailed ways

A water-saving air-conditioning system for a computer room in which closed cooling water and chilled water can operate in series, as shown in Figure 1, including a dry-type indirect evaporative refrigeration unit and a mechanical refrigeration unit, wherein the dry-type indirect evaporative refrigeration unit includes a direct evaporative refrigeration unit 3 , the surface heat exchanger 4, the exhaust fan 5 and the cabinet, the outlet pipe of the surface heat exchanger 4 is connected to the inlet of the evaporator of the first mechanical refrigeration unit 7 through the first circulating pump 6, and the outlet pipe of the evaporator passes through the user 8 It is connected to the inlet of the condenser of the first mechanical refrigeration unit 7 , and the outlet pipe of the condenser is connected to the inlet of the surface heat exchanger 4 . A direct evaporative cooling device 3 , a surface heat exchanger 4 and an exhaust fan 5 are arranged in sequence along the air inlet direction in the cabinet with the air inlet 1 and the air outlet 2 . The dry indirect evaporative refrigeration unit includes a direct evaporative refrigeration device 3, a surface heat exchanger 4, an exhaust fan 5, an air inlet 1 and an air exhaust 2, and the low-temperature outlet liquid of the surface heat exchanger 4 is supplied to air conditioners. It has the following operation modes: Operation mode 1: When the dry bulb temperature of the outdoor air is relatively low, the circulating water pump of the direct evaporative cooling device 3 is turned off, and the outdoor low-temperature air enters the surface heat exchanger 4 through the air inlet 1, and the surface heat exchanger 4 is cooled. The cold-carrying medium in the heater 4, the cold-carrying medium whose temperature has dropped enters the evaporator of the first mechanical refrigeration unit 7 under the action of the first circulating pump 6, and the output liquid of the evaporator enters the user for cooling, and the output liquid of the user enters the condensation The liquid out of the condenser returns to the surface heat exchanger 4 to cool down in a cooling cycle. At this time, the first mechanical refrigeration unit 7 is closed; operating mode 2: when the outdoor air dry bulb temperature is relatively high and the wet bulb temperature is relatively low, directly The evaporative cooling device 3 is turned on, the outdoor air is cooled by the direct evaporative cooling device 3, and after the temperature drops, it enters the surface heat exchanger 4 to cool the cooling medium, and the dry indirect evaporative cooling unit starts the wet operation mode, at this time the first mechanical refrigeration unit 7 is off; operation mode three: when the outdoor air temperature is relatively high, the direct evaporative cooling device 3 is turned on, and when the temperature of the cooling medium prepared by the surface heat exchanger 4 is not enough to satisfy the user's refrigeration, the first mechanical refrigeration unit 7 is turned on , the cooling medium is further cooled by the first mechanical refrigeration unit to perform mixed refrigeration.

As shown in Figure 2, a first bypass 20 and a first valve 12 are provided on the pipeline connecting the first circulation pump 6 to the inlet of the evaporator of the first mechanical refrigeration unit 7, and the user 8 is connected to the condenser of the first mechanical refrigeration unit 7 The inlet pipeline is provided with a second bypass 21 and a second valve 13, wherein the second bypass 21 is connected to the inlet of the evaporator of the first mechanical refrigeration unit 7 through the second circulation pump 11 and the fourth valve 15, and the first bypass The road 20 is connected to the pipeline connected to the inlet of the condenser of the first mechanical refrigeration unit 7 before the second valve 13 through the third valve 14 . By setting bypass and valves, the operating mode of the unit is more perfect. Operation mode 1: When the dry bulb temperature of the outdoor air is relatively low, the circulating water pump of the direct evaporative cooling device 3 is turned off, and the outdoor low-temperature air enters the surface heat exchanger 4 through the air inlet 1, and the cooling load in the surface heat exchanger 4 is cooled. Medium, the cooling medium with reduced temperature passes through the first valve 12 under the action of the first circulation pump 6, and enters the evaporator of the first mechanical refrigeration unit 7, and the output liquid of the evaporator enters the user for refrigeration. At this time, the first mechanical refrigeration unit 7 is closed, the first valve 12 and the second valve 13 are opened, the third valve 14 and the fourth valve 15 are closed, and only the dry operation of the dry indirect evaporative refrigeration unit can satisfy the air conditioning refrigeration; operation mode 2: when the outdoor air is dry When the bulb temperature is relatively high and the wet bulb temperature is relatively low, the direct evaporative refrigeration device 3 is turned on, and the outdoor air is cooled by the direct evaporative refrigeration device 3. After the temperature drops, it enters the surface heat exchanger 4 to cool the cooling medium, dry indirect evaporative refrigeration The unit starts the wet operation mode. At this time, the first mechanical refrigeration unit 7 is closed, the first valve 12 and the second valve 13 are opened, the third valve 14 and the fourth valve 15 are closed; operating mode three: when the outdoor air is dry and the wet bulb temperature When both are relatively high, the direct evaporative refrigeration device 3 is turned on, and the temperature of the cooling medium prepared by the surface heat exchanger 4 is not enough to satisfy the user's refrigeration, the first mechanical refrigeration unit 7 is turned on to perform mixed refrigeration, and the surface heat exchanger The output liquid of 4 enters the evaporator of the first mechanical refrigeration unit 7 for further cooling, the output liquid of the evaporator enters the user for cooling, the temperature of the user’s output liquid rises, and enters the condenser, as the cooling water of the first mechanical refrigeration unit 7, condensed The output liquid of the device returns to the surface heat exchanger 4 to be recycled by air cooling. At this time, the first mechanical refrigeration unit 7 is opened, the first valve 12 and the second valve 13 are opened, and the third valve 14 and the fourth valve 15 are closed. ; Operation mode four: when the liquid outlet temperature of the surface heat exchanger 4 is higher than the liquid return temperature of the user, the liquid outlet of the surface heat exchanger 4 is only used as cooling water for the condenser of the first mechanical refrigeration unit 7, The low-temperature output liquid produced by the first mechanical refrigeration unit 7 is used for refrigeration by the second circulating pump 11, at this time, the third valve 14 and the fourth valve 15 are opened, and the first valve 12 and the second valve 13 are closed. The cooling medium circulating between the surface heat exchanger 4 and the evaporator, condenser and users can be water or antifreeze (such as ethylene glycol).

As shown in Figure 3, the pipeline connecting the first circulation pump 6 to the first valve 12 is connected to the pipeline connecting the outlet of the evaporator of the first mechanical refrigeration unit 7 to the user 8 through the fifth valve 16 provided by the third bypass 22, and the user 8. The outlet is connected to the first mechanical refrigeration unit 7. The condenser inlet is located on the pipeline at the rear of the second valve 13. The sixth valve 17 set through the fourth bypass 23 is connected to the first mechanical refrigeration unit 7. The condenser outlet is connected to the surface type inverter. On the pipeline of heater 4 inlet. By adding the fifth valve 16 and the sixth valve 17, when the mechanical refrigeration unit does not need to be turned on during winter operation or transitional season operation, when the outlet liquid temperature of the surface heat exchanger 4 can meet the user's requirements, it is closed at this time The first valve 12, the second valve 13, the third valve 14, and the fourth valve 15 open the fifth valve 16 and the sixth valve 17, and the outlet liquid of the surface heat exchanger 4 passes through the first circulating pump 6 and passes through the fifth valve. The valve 16 enters the user’s refrigeration, and the user’s outlet liquid returns to the surface heat exchanger 4 to cool down through the sixth valve 17. At this time, the circulation process of the cooling medium does not pass through the first mechanical refrigeration unit 7, which reduces the first cycle The operating energy consumption of the pump 6.

As shown in Figure 4, the outlet pipe of the first circulating pump 6 is connected to the inlet of the first mechanical refrigeration unit 7 evaporators, and the outlet pipe of its evaporator is connected to the inlet of the second mechanical refrigeration unit 18 evaporators, and the outlet pipe of its evaporator is connected to the inlet of the evaporator of the second mechanical refrigeration unit 18. The outlet pipe is connected to the inlet of the condenser of the first mechanical refrigeration unit 7 through the user 8, the outlet pipe of the condenser is connected to the inlet of the condenser of the second mechanical refrigeration unit 18, and the outlet pipe of the condenser is connected to the surface heat exchanger 4 imports. The outlet of the surface heat exchanger 4 is connected to the cooling medium inlet of the evaporator of the first mechanical refrigeration unit 7 through the first circulation pump 6, and the cooling medium outlet of the evaporator of the first mechanical refrigeration unit 7 is connected to the second mechanical refrigeration unit 7. The cooling medium inlet of the evaporator of the unit 18, the cooling medium outlet of the evaporator of the second mechanical refrigeration unit 18 is connected to the inlet of the user 8, and the cooling medium outlet of the user 8 is connected to the load of the condenser of the first mechanical refrigeration unit 7. The cold medium inlet, the cooling medium outlet of the condenser of the first mechanical refrigeration unit 7 is connected to the cooling medium inlet of the condenser of the second mechanical refrigeration unit 18, through two mechanical refrigeration units arranged in series on the cooling water side and the chilled water side , reducing the temperature difference of a single mechanical refrigeration unit and improving the energy efficiency of the mechanical refrigeration unit.

As shown in Figure 5, the first bypass 20, the third bypass 22 and the first valve 12 are arranged on the pipeline connecting the outlet pipe of the first circulation pump 6 to the inlet of the evaporator of the first mechanical refrigeration unit 7, wherein the first bypass 20, the third bypass 22 and the first valve 12 A bypass 20 is connected to the inlet of the condenser of the first mechanical refrigeration unit 7 through the third valve 14, and the third bypass 22 is connected to the outlet pipe of the evaporator of the second mechanical refrigeration unit 18 through the fifth valve 16; the outlet pipe of the user 8 The inlet of the condenser of the first mechanical refrigeration unit 7 is connected through the second bypass 21 and the second valve 13 provided, wherein the second bypass 21 is connected to the first mechanical refrigeration unit through the second circulation pump 11 and the fourth valve 15 7 The inlet of the evaporator, the outlet of the user 8 are connected to the first mechanical refrigeration unit 7 The inlet of the condenser is located on the pipeline behind the second valve 13, and the sixth valve 17 set through the fourth bypass 23 is connected to the first mechanical refrigeration unit 7 The outlet of the condenser is connected to the pipeline of the condenser inlet of the second mechanical refrigeration unit 18, and the seventh valve 19 provided on the pipeline through the fifth bypass 24 is connected to the outlet pipe of the condenser of the second mechanical refrigeration unit 18. The first valve 12 to the seventh valve 19 are added for adjustment, and there are several operation modes as follows: Operation mode 1: When the dry bulb temperature of the outdoor air is relatively low, the circulating water pump of the direct evaporative refrigeration device 3 is turned off, and the outdoor low-temperature air passes through the inlet The tuyere 1 enters the surface heat exchanger 4 to cool the cooling medium in the surface heat exchanger 4. The cooled medium passes through the fifth valve 16 under the action of the first circulation pump 6 and enters the user’s refrigeration. The outlet liquid returns to the surface heat exchanger 4 through the sixth valve 17 and the seventh valve 19 to cool down in circulation. At this time, the two mechanical refrigeration units are closed, and the first valve 12, the second valve 13, the third valve 14, and the fourth valve 15 is closed, only the dry-type indirect evaporative refrigeration unit is used for dry cooling to meet the air-conditioning refrigeration, and the circulation process of the cooling medium does not pass through two mechanical refrigeration units, which reduces the operating energy consumption of the first circulation pump 6; operation mode 2: when When the dry-bulb temperature of the outdoor air is relatively high and the wet-bulb temperature is relatively low, the direct evaporative refrigeration device 3 is turned on, and the outdoor air is cooled by the direct evaporative refrigeration device 3. After the temperature drops, it enters the surface heat exchanger 4 to cool the cooling medium. The indirect evaporative refrigeration unit turns on the wet operation mode. At this time, the two mechanical refrigeration units are closed, and the circulation process of the cooling medium does not pass through the two mechanical refrigeration units. The valves are the first valve 12, the second valve 13, the third valve 14, the The four valves 15 are closed; the third operation mode: when the outdoor air is dry and the wet bulb temperature is relatively high, the direct evaporative cooling device 3 is turned on, and the temperature of the cooling medium prepared by the surface heat exchanger 4 is not enough to meet the user's cooling requirements. , turn on two or one of the mechanical refrigeration units to perform mixed refrigeration, and the liquid discharged from the surface heat exchanger 4 first enters the evaporator of the first mechanical refrigeration unit 7 for cooling, and then enters the evaporator of the second mechanical refrigeration unit 18 for further cooling. Cooling, the outlet liquid of the evaporator of the second mechanical refrigeration unit 18 enters the user for cooling, and the temperature of the user’s outlet liquid rises, and enters the condenser of the two mechanical refrigeration units connected in series, as the cooling water of the two mechanical refrigeration units, the condenser The outlet liquid returns to the surface heat exchanger 4 to be recycled by air cooling. At this time, two or one of the mechanical refrigeration units are opened, the first valve 12 and the second valve 13 are opened, and the third valve 14 and the fourth valve are opened. 15. The fifth valve 16 and the sixth valve 17 are closed; operation mode 4: when the liquid outlet temperature of the surface heat exchanger 4 is higher than the return liquid temperature of the user, the liquid outlet of the surface heat exchanger 4 is only used as The cooling water of the condensers of two mechanical refrigeration units arranged in series, the low-temperature output liquid produced by the mechanical refrigeration units is used for cooling by the user through the second circulation pump 11. At this time, the third valve 14 and the fourth valve 15 are opened, and the first The valve 12, the second valve 13, the fifth valve 16 and the sixth valve 17 are closed.

As shown in Figure 6 and Figure 7, the outlet pipe of the surface heat exchanger 4 is connected to the outlet of the first mechanical refrigeration unit 7 evaporator through the liquid-liquid heat exchanger 9 and the first circulating pump 6; or/and in the cabinet An indirect evaporative cooling section 10 is arranged between the inner air inlet 1 and the direct evaporative refrigeration device 3 . A liquid-liquid heat exchanger 9 is arranged on the liquid outlet side of the surface heat exchanger 4, and during operation in summer, the cooling medium is further cooled through the liquid-liquid heat exchanger 9 to reduce the temperature of the cooling medium; in direct evaporative refrigeration The indirect evaporative cooling section 10 is set on the air inlet side of the device 3, and the indirect evaporative cooling section 10 reduces the dry and wet bulb temperature of the air inlet air, improves the running time of natural cooling, reduces the configuration of mechanical refrigeration units, and is more energy-saving. it is good.

Claims (7)

1. The utility model provides a but closed cooling water and refrigerated water tandem operation's computer lab water-saving air conditioning system, includes dry-type indirect evaporation refrigerating unit and mechanical refrigeration unit, and wherein dry-type indirect evaporation refrigerating unit includes direct evaporation refrigerating plant (3), surface formula heat exchanger (4), exhaust fan (5) and quick-witted case, characterized by: the outlet pipe of the surface heat exchanger (4) is connected with the inlet of the evaporator of the first mechanical refrigerating unit (7) through a first circulating pump (6), the outlet pipe of the evaporator is connected with the inlet of the condenser of the first mechanical refrigerating unit (7) through a user (8), and the outlet pipe of the condenser is connected with the inlet of the surface heat exchanger (4).

2. The water-saving air conditioning system of the machine room with the closed cooling water and the chilled water capable of operating in series according to claim 1, which is characterized in that: a direct evaporation refrigerating device (3), a surface type heat exchanger (4) and an exhaust fan (5) are sequentially arranged in a case with an air inlet (1) and an air outlet (2) along the air inlet direction.

3. The water-saving air conditioning system of the machine room with the closed cooling water and the chilled water capable of operating in series according to claim 1, which is characterized in that: a first bypass (20) and a first valve (12) are arranged on a pipeline of a first circulating pump (6) connected with an inlet of an evaporator of a first mechanical refrigerating unit (7), a second bypass (21) and a second valve (13) are arranged on a pipeline of a user (8) connected with an inlet of a condenser of the first mechanical refrigerating unit (7), wherein the second bypass (21) is connected with an inlet of an evaporator of the first mechanical refrigerating unit (7) through a second circulating pump (11) and a fourth valve (15), and the first bypass (20) is connected with a pipeline of the inlet of the condenser of the first mechanical refrigerating unit (7) before the second valve (13) through a third valve (14).

4. The water-saving air conditioning system of the machine room with the closed cooling water and the chilled water capable of operating in series according to claim 3, which is characterized in that: a fifth valve (16) arranged on a pipeline of a first circulating pump (6) connected with a first valve (12) through a third bypass (22) is connected to a pipeline of a user (8) connected with an evaporator outlet of a first mechanical refrigerating unit (7), a condenser inlet of the user (8) connected with the first mechanical refrigerating unit (7) is arranged on a pipeline at the rear part of a second valve (13), and a sixth valve (17) arranged through a fourth bypass (23) is connected to a pipeline of the first mechanical refrigerating unit (7) connected with a condenser outlet of a surface type heat exchanger (4).

5. The water-saving air conditioning system of the machine room with the closed cooling water and the chilled water capable of operating in series according to claim 1, which is characterized in that: the outlet pipe of the first circulating pump (6) is connected with the inlet of the evaporator of the first mechanical refrigerating unit (7), the outlet pipe of the evaporator is connected with the inlet of the evaporator of the second mechanical refrigerating unit (18), the outlet pipe of the evaporator is connected with the inlet of the condenser of the first mechanical refrigerating unit (7) through a user (8), the outlet pipe of the condenser is connected with the inlet of the condenser of the second mechanical refrigerating unit (18), and the outlet pipe of the condenser is connected with the inlet of the surface heat exchanger (4).

6. The water-saving air conditioning system of the machine room with the closed cooling water and the chilled water capable of operating in series according to claim 5, which is characterized in that: a first bypass (20), a third bypass (22) and a first valve (12) are arranged on a pipeline of which an outlet pipe of the first circulating pump (6) is connected with an inlet of an evaporator of the first mechanical refrigerating unit (7), wherein the first bypass (20) is connected with an inlet of a condenser of the first mechanical refrigerating unit (7) through a third valve (14), and the third bypass (22) is connected with an outlet pipe of an evaporator of the second mechanical refrigerating unit (18) through a fifth valve (16); an outlet pipe of a user (8) is connected with an inlet of a condenser of the first mechanical refrigerating unit (7) through a second bypass (21) and a second valve (13), wherein the second bypass (21) is connected with an inlet of an evaporator of the first mechanical refrigerating unit (7) through a second circulating pump (11) and a fourth valve (15), an outlet of the user (8) is connected with a pipeline of the condenser of the first mechanical refrigerating unit (7) and an inlet of the condenser of the first mechanical refrigerating unit (7) is positioned behind the second valve (13), a sixth valve (17) arranged through the fourth bypass (23) is connected with a pipeline of the condenser of the first mechanical refrigerating unit (7) and an outlet of the condenser of the second mechanical refrigerating unit (18), and a seventh valve (19) arranged on the pipeline through a fifth bypass (24) is connected with the outlet pipe of the condenser of the second mechanical refrigerating unit (18).

7. The water-saving air conditioning system of the machine room with the closed cooling water and the chilled water capable of operating in series according to the claim 1, 2, 3, 4, 5 or 6, which is characterized in that: an outlet pipe of the surface type heat exchanger (4) is connected with an outlet of an evaporator of the first mechanical refrigerating unit (7) through a liquid-liquid heat exchanger (9) and a first circulating pump (6); or/and an indirect evaporative cooling section (10) is arranged between the air inlet (1) in the case and the direct evaporative cooling device (3).