JP7259950B2 - Cooling system, control device therefor, cooling method, and program - Google Patents

Description

The present invention relates to a cooling system, a cooling system controller, a cooling method and a program that enable reduction of energy consumption. More particularly, the present invention relates to systems for reducing power consumption of data center cooling systems while maintaining desired ambient temperatures.

Energy savings in data center cooling systems have a significant impact on overall data center energy consumption savings. Energy savings in such cooling systems can be realized by operating a free cooling cycle using local level cooling systems. However, the free cooling cycle has a limited cooling capacity, so the cooling cycle is switched to compression cooling when necessary. Proper cooling cycle switching methods/algorithms must be used to maximize energy savings and safe cooling system operation in data centers.

Data center cooling systems typically employ two types of cooling cycles: compression cooling and free cooling. Compression cooling provides year-round cooling regardless of outside temperature, but consumes high electrical energy. Free cooling, on the other hand, consumes relatively low electrical energy, but can provide the necessary cooling capacity only when the external ambient temperature is sufficiently low. Therefore, in order to save energy, it is necessary to operate the free cooling cycle as much as possible, but at the same time to ensure sufficient cooling for safe operation of the data center.

FMACS-V Hybrid is an example of a room-level cooling system, i.e., located at the end of a row of racks, utilizing a compressor and free cooling cycle to provide cooling to all racks in a given row of racks. do. Local level cooling systems are employed for data centers to reduce excessive power consumption due to the excessive cooling characteristics of room level cooling systems.

Local level cooling systems are located near designated racks to provide cooling to the racks and eliminate the need for excessive cooling. To further reduce energy consumption, these local level refrigeration systems can also switch between compressor and free refrigeration cycles using a suitable refrigeration cycle switching method.
Several techniques have attempted to solve one or more of the above problems, such as those taught in US Pat. The solutions have shortcomings and cannot achieve the technical effect of the present invention alone or in combination.

In general, a suitable cooling cycle switching method, such as that disclosed in Non-Patent Document 1, utilizes the external environment temperature and waste heat load to determine the appropriate cooling cycle. However, switching between the compressor cooling cycle and the free cooling cycle must meet the cooling needs of the heat load, not just focus on energy savings. Failure to do so may result in inadequate cooling of the data center, leading to data center failure.

International Publication No. 2015/004742; Komatsu et al.; Heat load prediction device, distribution system, heat load prediction method and program JP-A-2011-247433; Miyajima et al.; cold water production equipment and cold water production method Japanese Unexamined Patent Application Publication No. 2009-252056; Kato et al.; Operation management method and operation management device for information processing system

N. Futawatari et. al. Packaged air conditioner incorporating free cooling cycle for data centers

An exemplary objective of this disclosure is to reduce the power consumed by the cooling system and to properly cool the electronics contained in the server rack by adjusting the cooling temperature in response to environmental and system measurements made by various sensors. An object of the present invention is to provide a cooling system for server racks that can efficiently switch between modes, ie, a free cooling cycle and a compressor cooling cycle.

A suitable cooling cycle must be determined based on the external environment temperature, waste heat load, and refrigerant inlet temperature to the heat exchanger near the rack exit.

As a first exemplary aspect of the present disclosure, a cooling system is provided, the cooling system comprising a server rack, a heat exchanger configured to produce cooling air, and a refrigerant inlet to the heat exchanger. a first pressure sensor configured to measure pressure; a second pressure sensor configured to measure refrigerant outlet pressure of said heat exchanger; and a refrigerant inlet temperature to said heat exchanger. a second temperature sensor configured to measure the refrigerant outlet temperature of the heat exchanger; and a third temperature sensor configured to measure the outdoor environment temperature. a temperature sensor; a flow sensor configured to measure refrigerant flow to the heat exchanger; a controller configured to switch between a compressor cooling cycle and a free cooling cycle based on the measured data, wherein the compressor cooling cycle utilizes the compressor to cool server rack exhaust air. and the free cooling cycle utilizes outside ambient air to cool the exhaust of the server rack.

As a second exemplary aspect of the present disclosure, a controller is provided for a cooling system of a server rack. The cooling system includes a heat exchanger, a plurality of measurement sensors, and a cooling cycle unit configured to provide compressor cooling and free cooling to the heat exchanger. The controller comprises a memory unit, a processing unit, a refrigerant inlet pressure measurement to the heat exchanger, a refrigerant outlet pressure measurement, a refrigerant inlet temperature measurement, a refrigerant outlet temperature measurement, an outdoor environment temperature measurement, and a refrigerant flow rate measurement. an I/O unit configured to receive from a plurality of measurement sensors, wherein the processing unit performs the refrigerant inlet pressure measurements to the heat exchanger, the refrigerant outlet pressure measurements, the refrigerant inlet temperature measurements, It is configured to output a command to the refrigeration cycle unit to switch between a compressor refrigeration cycle and a free refrigeration cycle based on the refrigerant outlet temperature measurement, the outdoor environment temperature measurement and the refrigerant flow measurement.

As a third exemplary aspect of the disclosure, a cooling method is provided for a server rack. The cooling method includes measuring a refrigerant inlet pressure to a heat exchanger, measuring a refrigerant outlet pressure of the heat exchanger, measuring a refrigerant inlet temperature to the heat exchanger, measuring a refrigerant outlet temperature of an exchanger; measuring outdoor environment temperature; measuring refrigerant flow rate to said heat exchanger; said refrigerant inlet pressure; said refrigerant outlet pressure; determining whether to operate a compressor refrigeration cycle or a free refrigeration cycle based on the relationship between temperature, said refrigerant outlet temperature, said outdoor ambient temperature and said refrigerant flow rate.

As a fourth exemplary aspect of the present invention, a computer is provided with measuring refrigerant inlet pressure to a heat exchanger, measuring refrigerant outlet pressure of said heat exchanger, and measuring refrigerant outlet pressure of said heat exchanger. measuring an inlet temperature; measuring a refrigerant outlet temperature of the heat exchanger; measuring an outdoor environment temperature; measuring a refrigerant flow rate to the heat exchanger; operating either a compressor refrigeration cycle or a free refrigeration cycle based on the relationship between said refrigerant outlet pressure, said refrigerant inlet temperature, said refrigerant outlet temperature, said outdoor environment temperature and said refrigerant flow rate; A program is provided to determine whether and to perform.

The present disclosure provides a cooling system, control device, method, and program that can provide necessary cooling for server racks while reducing power consumption.

1 illustrates an exemplary embodiment of a cooling system including racks to dissipate a heat load; FIG. FIG. 1 shows a rack with servers, heat exchangers, and airflow. 3 is a functional diagram of a compressor/free cooling cycle unit of an exemplary embodiment of the invention; FIG. FIG. 4 is an operational diagram illustrating the workflow of the temperature controller of an exemplary embodiment of the invention; FIG. 4 is an operational diagram illustrating the workflow of the switching controller of an exemplary embodiment of the invention; FIG. 4 is a diagram showing an example of a predetermined table showing the relationship between the refrigerant inlet temperature (° C.) of the heat exchanger, the outdoor environment temperature (° C.), and the waste heat load (kW); FIG. 3 is a diagram showing another example of a predetermined table showing the relationship between the refrigerant inlet temperature (° C.) of the heat exchanger, the outdoor environment temperature (° C.), and the waste heat load (kW); FIG. 3 is a diagram showing another example of a predetermined table showing the relationship between the refrigerant inlet temperature (° C.) of the heat exchanger, the outdoor environment temperature (° C.), and the waste heat load (kW); 1 is a functional diagram of an exemplary embodiment of a controller for a server rack of the present invention; FIG.

Exemplary embodiments of the invention are described below with reference to the drawings. In the drawings, the same elements are denoted by the same reference numerals, so redundant descriptions are omitted as necessary.

References to "an embodiment," "an embodiment," "an example," or "an example" throughout this specification mean that a particular feature, structure, or characteristic described in connection with an embodiment or example It is meant to be included in at least one of the embodiments. Thus, the appearances of the phrases "in one embodiment," "in an embodiment," "an example," or "example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. is not limited. Moreover, certain features, structures or characteristics may be combined in any suitable combination and/or subcombination in one or more embodiments or examples.

For room-level cooling systems, the appropriate cooling cycle can be selected based on the external environment temperature and total waste heat load. For a local level cooling system, the actual local cooling requirement may exceed the average cooling requirement due to variations in the local waste heat load. Therefore, local-level cooling systems must consider not only the total waste heat load, but also the fluctuation of the waste heat load. Therefore, proper cooling cycle switching algorithms for room-level cooling systems may fail when applied to local-level cooling systems.

For room-level cooling systems, there is a large free space availability between the rack exit and the cooling system inlet so that all hot exhaust air from the rack exit is thoroughly mixed before reaching the cooling system inlet. be done. Thus, the cooling system handles the total heat load rather than the individual heat load of each rack. Room-level cooling systems are therefore limited by the maximum total heat load that can be extracted, not by the maximum heat load of individual racks.

In the case of a local level cooling system, the cooling system is placed near the rack dissipating the heat load. A local level cooling system may include multiple local cooling equipment, such as heat exchangers, with individual cooling units cooling individual heat loads.

In such a local level cooling system, the waste heat load from the outlet of a rack is taken directly by the inlet of the cooling system without mixing with nearby waste heat loads from other racks. Individual distributed cooling units, such as heat exchangers, near individual heat loads must meet their respective cooling requirements. The cooling system is therefore limited by the maximum local heat load rather than the total heat load of all racks.

Therefore, if the maximum heat load of any rack is greater than the average heat load of all racks, the proper cooling cycle switching algorithm for room-level cooling systems will fail when applied to local-level cooling systems.

This bottleneck occurs because the average load cooling cycle parameter determined for the room level cooling system extracts only the average heat load from the individual local level cooling systems. Therefore, if the local heat load is higher than the average heat load, the remaining load, i.e. (maximum heat load minus average heat load), is not extracted by the cooling system and can lead to data center failure. .

FIG. 1 illustrates server racks 110 and 111, heat exchangers 112 and 113, cooling inlet pipe 119, cooling outlet pipe 120, outlet pressure sensor 121, inlet pressure sensor 124, temperature sensors 122, 123 and 126, flow sensor 125, compression The entire system including machine/free cooling cycle unit 114, switching controller 115, and power supply 127 is shown. FIG. 1 shows the overall cooling system used to cool cooling racks 110 and 111 .

Server racks 110 and 111 may store electronic equipment 212 such as computing servers, network devices, etc., as shown in FIG. Electronics 212 consume power for their operation and dissipate a comparable amount of thermal energy. This heat energy can be transferred to cool air and drawn into the device body by a fan 213 attached to the electronic device, as shown in FIG. The fan 213 also exhausts hot air from the equipment body in a rack exhaust airflow direction 214 as shown in FIG.

Hot air exhausted from the outlet of electronic device 212 flows toward cooling units 112 and 113 . The cooling units 112 and 113 extract thermal energy from the hot air until the hot air reaches a predetermined temperature. Air exits the cooling units 112 and 113 as indicated by the heat exchanger exhaust direction 215 in FIG. . Airflow between the cooling and the rack is indicated by arrows 215 in FIG. One example of such a cooling unit is a heat exchanger.

Heat exchangers 112 and 113 may also include auxiliary fans to assist with airflow around server racks 110 and 111, if desired.

Also, heat exchangers 112 and 113 are shown in a horizontal position. Depending on the design of the cooling system, heat exchangers 112 and 113 can have any orientation.

Server racks 110 and 111 consume electrical energy from power supply 127, which is dissipated as heat energy.

The dissipated heat energy is extracted by refrigerant flowing inside heat exchangers 112 and 113 . Liquid refrigerant reaches the heat exchanger from heat exchanger inlet pipe 119 . The liquid coolant absorbs thermal energy to reduce the exhaust temperature of the rack. By absorbing thermal energy, the liquid refrigerant turns into a vapor refrigerant. Vapor refrigerant is carried away from the heat exchanger by heat exchanger outlet pipe 120 .

FIG. 3 shows an example compressor/free cooling cycle unit 114 that includes the basic equipment for running either a compressor cooling cycle or a free cooling cycle at a given time. Compressor/free cooling cycle unit 114 includes compressor 310 , pump 315 , expansion valve 316 , cycle switching valve 312 , outdoor unit 326 and temperature controller 317 .

During compressor cycle operation, compressor 310 operates to compress vapor refrigerant coming from heat exchanger outlet pipe 120 . The vapor refrigerant is then sent via pipe 313 to outdoor unit 326 where it returns to liquid refrigerant by removing heat energy from the vapor refrigerant to the outdoor environment. Liquid refrigerant returned by outdoor unit 326 via pipe 314 is expanded using expansion valve 316 . The liquid refrigerant then returns to heat exchangers 112 and 113 via heat exchanger inlet pipe 119 . Switching valve 312 remains closed and pump 315 remains off.

During free cooling cycle operation, the vapor refrigerant coming from heat exchanger outlet pipe 120 bypasses compressor 310 through compressor bypass 311 and goes directly to outdoor unit 326 via pipe 313 and passes from the vapor refrigerant to the outdoor environment. It returns to liquid refrigerant by removing the heat energy to . Liquid refrigerant received by outdoor unit 326 via pipe 314 passes through pump 315 and returns to the heat exchanger via heat exchanger inlet pipe 119 . The compressor 310 remains off and the expansion valve remains closed.

Pump 315 only assists the flow of refrigerant. Depending on system design, pump 315 may be removed.

Outdoor unit 326 is used to remove heat from the vapor refrigerant to the outside environment. Refrigerant inlet pipe 313 carries vapor refrigerant to heat exchanger(s) 321 . A fan 323 may be used to move outside ambient air through the heat exchanger as indicated by airflow direction 322 . The vapor refrigerant loses thermal energy to the outside air and turns into a liquid refrigerant. The liquid refrigerant then returns to refrigerant outlet pipe 314 .

Compressor/free cooling cycle unit 114 may include temperature controller 317 . A temperature controller 317 controls and maintains the heat exchanger outlet cold air temperature. The temperature controller 314 has three functions: a "receive heat exchanger outlet air temperature" function 318 that receives heat exchanger outlet cold air temperature data, a "determine actuator target" function 319 that determines the operation of the actuators, and a An "actuator operator" function 320 may be included to activate. These functions are described in detail later in FIG.

In FIG. 1, inlet pressure sensor 124 in heat exchanger inlet pipe 119 is used to measure refrigerant pressure at heat exchanger inlet pipe 119 . An outlet pressure sensor 121 on the heat exchanger outlet pipe 120 is used to measure the refrigerant pressure at the heat exchanger outlet pipe 120 . The heat exchanger inlet pipe 119 inlet temperature sensor 123 is used to measure the coolant temperature in the heat exchanger inlet pipe 119 . An outlet temperature sensor 122 in the heat exchanger outlet pipe 120 is used to measure the coolant temperature in the heat exchanger outlet pipe 120 . A temperature sensor 126 located outdoors is used to measure the outdoor ambient temperature of the outdoor environment. Flow sensor 125 is used to measure liquid refrigerant flow at heat exchanger inlet pipe 119 .

Power supply 127 is used to supply the electrical energy required by various equipment such as server racks 110 and 111 , compressor/free cooling cycle unit 114 , and switching controller 115 . The sensor's electrical energy requirements can be met by the hardware used for the “data fetch” function 118 . The power supply 127 can also supply electrical energy to various sensors as needed.

A switching controller 115 controls and maintains proper cooling cycle operation. The switching controller 115, for example, has three functions: a "data fetch" function 118 that fetches data from various sensors; a "cycle select" function 116 that selects the appropriate cycle from the compressor/free cooling cycles; may also include an "actuator operator" function 117 that activates the actuators necessary to operate the appropriate cooling cycle. Details of the switching controller 115 are shown in FIG.

A "data fetch" function 118 communicates with each sensor 121, 122, 123, 124, 125, 126 and receives their measurements. The received value is then sent to the “cycle select” function 116 . A "cycle select" function 116 processes the data received from the "data fetch" function 118 to determine the appropriate cooling cycle. The determination of the appropriate cooling cycle is sent to the “actuator operator” function 117 . Based on the determination of the appropriate cooling cycle, the “actuator operator” function 117 communicates with the compressor/free cooling cycle unit 114 . Based on commands received from the "actuator operator" function 137, the compressor/free cooling cycle unit 114 operates the appropriate actuators.

FIG. 1 shows only two server racks 110 and 111 with respective local cooling systems, ie heat exchangers 112 and 113 . Note that the number of racks is not particularly limited and can be expanded to any number of racks.

The workflow of the temperature controller 317 will be described below.
(1) Step 411
First, set the target temperature value of the heat exchanger outlet cold air temperature according to the data center condition requirements.

(2) Step 412
Heat exchanger outlet cold air temperature is measured using a temperature sensor via the Receive Heat Exchanger Outlet Air Temperature function 318 . Multiple sensors may be used to measure the outlet cold air temperature of each of the multiple heat exchangers. Depending on the rack power distribution, the heat exchanger exit cold air temperature may vary.

In one exemplary embodiment, both server racks 110 and 111 of FIG. 1 consume equal power, so the rack exhaust exit air temperature is equal for both racks. Since heat exchanger refrigerant inlet pipe 119 is common to heat exchangers 112 and 113, the thermophysical conditions at the liquid refrigerant inlet are the same for both heat exchangers. Therefore, for the same rack exhaust temperature and same liquid refrigerant inlet conditions, the heat exchanger outlet cold air temperature will also be equal.

In another exemplary embodiment, server rack 110 consumes more power than rack 111, provided that the total rack power of server racks 110 and 111 is equal to that in the previous case. In this case, the exhaust temperature of the server rack 110 is higher than that of the rack 111 . Therefore, the heat exchanger exit cold air temperature of the heat exchanger near server rack 110 is lower than that of the heat exchanger near rack 111 because the thermophysical conditions at the liquid refrigerant inlet are the same for both heat exchangers. expensive.

Therefore, even for equal total rack power consumption in different embodiments, the heat exchanger outlet cold air temperature may differ, which depends on the rack power distribution.
Again, the number of racks is not specifically limited for the above description and can be extended to any number of racks.

All measured temperature sensor values used are forwarded to the next step.
(3) Step 413
The "Actuator Target Determination" function 319 calculates the maximum heat exchanger exit cold air temperature from all measured temperature sensor values. The calculated maximum heat exchanger outlet cold temperature is compared to the heat exchanger outlet cold temperature set point from step 410 .

(4) Step 414
If the maximum temperature value of the heat exchanger outlet cold air temperature is higher than the set point for the heat exchanger outlet cold air temperature, the increase in the amount of heat exchanged in the heat exchangers 112 and 113 is indicated by the "Determine Actuator Target" function 319 to the "Actuator operator' function 320. One example of increasing the amount of heat exchanged is to lower the heat exchanger inlet refrigerant temperature.

(5) Step 415
In response to an increase in heat exchange, an "actuator operator" function 320 operates the minimum set of actuators appropriate to operate the cooling cycle. As an example of step 414, there are several ways to reduce the refrigerant inlet temperature of the heat exchanger, one example is using the compressor 310 to reduce the heat exchanger pressure.

(6) Step 416
If the maximum temperature value of the outlet cold air temperature of heat exchangers 112 and 113 is lower than the setpoint for the outlet cold air temperature, a decrease in the amount of heat exchanged by heat exchangers 112 and 113 is determined by the "determine actuator target" function 319. It is sent to the “actuator operator” function 320 . One example of reducing the amount of heat exchanged is to increase the heat exchanger inlet refrigerant temperature.

(7) Step 417
In response to a decrease in heat exchange, an "actuator operator" function 320 operates the minimum set of actuators appropriate to operate the cooling cycle. As an example of step 416, there are several ways to increase the coolant inlet temperature of the heat exchanger. One example is to use the compressor 310 to increase the heat exchanger pressure.

(8) Step 418
Temperature controller 317 waits M minutes, which is a preset value and can be changed as needed.

The impact of rack power distribution can be quantified using variables such as (total rack power consumption and heat exchanger coolant inlet temperature). As explained above, the heat exchanger outlet cold air temperature depends on the power distribution of the rack. The temperature controller also maintains the heat exchanger outlet cold air temperature by controlling the refrigerant inlet temperature of the heat exchanger. Therefore, a set of variables (total rack power consumption and heat exchanger coolant inlet temperature) can be utilized to quantify the impact of rack power distribution.

Workflow of switching controller 115 (1) Step 511
The current value of heat exchanger inlet liquid refrigerant pressure is fetched from inlet pressure sensor 124 at heat exchanger inlet pipe 119 and the heat exchanger outlet vapor refrigerant pressure is fetched from outlet pressure sensor 121 at heat exchanger outlet pipe 120. The heat exchanger inlet liquid refrigerant temperature is fetched from inlet temperature sensor 123 at heat exchanger inlet pipe 119 and the heat exchanger outlet vapor refrigerant temperature is fetched from outlet temperature sensor 122 at heat exchanger outlet pipe 120. Fetched, the heat exchanger inlet liquid refrigerant flow rate is fetched from the flow sensor 125 at the heat exchanger inlet pipe 119 and the data center external environment temperature is fetched from the temperature sensor 126 at the external environment.

(2) Step 512
Using the heat exchanger inlet liquid refrigerant pressure and the heat exchanger inlet liquid refrigerant temperature, the enthalpy of the heat exchanger inlet liquid refrigerant can be calculated using a refrigerant property table. Refrigerant property tables are available not only from manufacturers, but also from standard databases of refrigerant properties such as REFPROP by NIST.

Using the heat exchanger outlet liquid refrigerant pressure and the heat exchanger outlet liquid refrigerant temperature, the enthalpy of the heat exchanger outlet vapor refrigerant can be calculated using a refrigerant property table. Using the heat exchanger inlet liquid refrigerant pressure and the heat exchanger inlet liquid refrigerant temperature, the density of the heat exchanger inlet liquid refrigerant can be calculated using a refrigerant property table.

ここで、Ｈｅａｔ＿ｌｏａｄは現在の排熱負荷、ρは熱交換器入口液体冷媒の密度、ｑは流量センサから取得した熱交換器入口液体冷媒流量、ｈ_{ｖａｐｏｒ}は熱交換器出口蒸気冷媒のエンタルピー、ｈ_{ｌｉｑｕｉｄ}は熱交換器入口液体冷媒のエンタルピーである。 The current waste heat load can be calculated using the following equation (1).

Here, Heat_load is the current exhaust heat load, ρ is the density of the heat exchanger inlet liquid refrigerant, q is the heat exchanger inlet liquid refrigerant flow rate obtained from the flow sensor, h _vapor is the heat exchanger outlet vapor refrigerant enthalpy, h _liquid is the enthalpy of the heat exchanger inlet liquid refrigerant.

(3) Step 513
A predetermined table is selected for the current heat exchanger refrigerant inlet temperature. In the selected predetermined table, the intersection cell of the current outdoor environment temperature row and the current heat exhaust load column is selected. These predetermined tables define the relationship between outdoor ambient temperature, total waste heat load, and refrigerant inlet temperature to the heat exchanger, as shown in FIGS. 6A and 6B.

This predetermined table defines the relationship between the required heat exchanger liquid refrigerant inlet temperature and the total heat load as to whether the current heat load can be extracted by the free cooling cycle under the provided outdoor temperature. The probability can be expressed as 1 or 0, with 1 meaning that for the required heat exchanger liquid refrigerant inlet temperature, the current heat load can be extracted by the free cooling cycle under the provided outdoor temperature. , 0 means that the current heat load cannot be extracted by the free cooling cycle under the provided outdoor temperature for the required heat exchanger liquid refrigerant inlet temperature.

In one exemplary embodiment, the current heat exchanger refrigerant inlet temperature is 20° C., the waste heat load is 30 kW, and the outdoor environment temperature is 6° C. Table 1 shows the current heat exchange selected based on a coolant inlet temperature of 20°C. In Table 1, based on values of waste heat load=30 kW and outdoor ambient temperature=6° C., the appropriate table cells are selected as shown in FIG.

(4) Step 514
Based on step 513, cell values are received.
According to one exemplary embodiment defined in step 513 and FIG. 7, the received cell value is one.

(5) Step 515
If the cell value is 1, the switching controller 115 selects the free cooling cycle for operation.

(6) Step 516
If the cell value is 0, the switching controller 115 selects the compressor cooling cycle for operation.

(7) Step 517
The determination of step 515 or step 516 is provided to the "actuator operator" function 117, which causes the actuator to operate appropriately.

According to the exemplary embodiment of step 514 , ie, the free cooling cycle case, the “actuator operator” function 117 sets the switching valve 312 to the open position and starts the pump 315 . An "actuator operator" function 117 also shuts down the compressor 310 and sets the expansion valve 316 to the closed position.

For the compressor cooling cycle, the "actuator operator" function 117 sets the expansion valve 316 to the open position and turns on the compressor 310, as shown in FIG. Also, the “actuator operator” function 117 sets the switching valve 312 to the closed position and shuts down the pump 315 .

(8) Step 518
After actuating the actuator, the switching controller 115 waits N minutes, which is a preset value and can be changed as required.

Step 511 of FIG. 5 is performed by the “data fetch” function 118 , steps 512 through 516 are performed by the “cycle select” function 116 , and step 517 is performed by the “actuator operation” function 117 .

(other exemplary embodiments)
In another exemplary embodiment, heat exchangers 112 and 113 are located on the rack inlet air side rather than the rack outlet air side of the first exemplary embodiment.

In another exemplary embodiment, instead of a cooling cycle, constant temperature coolant is supplied to heat exchangers 112 and 113 . In this exemplary embodiment, the current waste heat load, outdoor ambient temperature, and heat exchanger inlet coolant mass flow rate are used to determine the appropriate cooling cycle.

In another exemplary embodiment, the current heat rejection load is determined from the total power of the rack.

In another exemplary embodiment, for an incompressible single-phase refrigerant system, only temperature and flow sensors are used to determine the current waste heat load, outdoor ambient temperature, and heat exchanger inlet refrigerant temperature. .

In another exemplary embodiment, a single rack may include multiple heat exchanger units to remove the heat load of the rack.

In another exemplary embodiment, a single heat exchanger is used to remove the evacuated heat load of multiple racks.
In another exemplary embodiment, the predetermined table defines relationships using values other than 0 and 1.

In another exemplary embodiment, a predetermined table value is compared to some set/variable value. Comparisons can utilize functions such as greater than, less than, equal, or any combination thereof.

Note that in the above description, a "heat exchanger" may be multiple heat exchangers operating independently or in combination. Similarly, other components may also be included as multiple respective other components according to design specifications.

Further, example embodiments according to the present example embodiments may be implemented as an apparatus, device, method, or computer program product. Accordingly, the present exemplary embodiments may be either an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.), or referred to herein as a "module" or "system." Embodiments may take the form of a combination of software and hardware aspects, all of which may be commonly referred to. Furthermore, the present exemplary embodiments may take the form of a computer program product embodied in any tangible medium of expression having computer-usable program code embodied in the medium.

Furthermore, in no way should the examples or illustrations described herein represent limitations, limitations, or definitions of the term or terms in which they are used. Instead, these examples or illustrations are described with respect to one particular embodiment and should be considered exemplary only. Any one or more terms in which these examples or illustrations are utilized will be readily apparent to those skilled in the art, other embodiments that may or may not be provided herein or elsewhere herein. and all such embodiments are intended to be included within the scope of that term or terms. Language specifying such non-limiting examples or illustrations includes "for example," "for instance," "such as," and "in one embodiment," is not limited to

The present disclosure is applicable to cooling systems that can provide necessary cooling for server racks while reducing power consumption.

110 server rack 111 server rack 112 heat exchanger 113 heat exchanger 114 compressor/free cooling cycle unit 115 switching controller 116 cycle selection function 117 actuator operation function 118 data fetch function 119 cooling inlet pipe 120 cooling outlet pipe 121 outlet pressure sensor 122 Outlet temperature sensor 123 Inlet temperature sensor 124 Inlet pressure sensor 125 Flow rate sensor 126 Outside air temperature sensor 127 Power supply 160 CPU
161 memory unit 162 I/O unit 212 electronic device 213 fan 214 rack exhaust airflow direction 215 heat exchanger exhaust direction 310 compressor 311 compressor bypass 312 switching valve 313 refrigerant inlet pipe 314 refrigerant outlet pipe 315 pump 316 expansion valve 317 temperature controller 318 Outlet temperature receiving function 319 Actuator target determination function 320 Actuator operator function 321 Heat exchanger 322 Airflow direction 323 Fan 326 Outdoor unit

Claims (7)

server rack,
a heat exchanger configured to produce cooling air;
a first pressure sensor configured to measure refrigerant inlet pressure to the heat exchanger;
a second pressure sensor configured to measure refrigerant outlet pressure of the heat exchanger;
a first temperature sensor configured to measure refrigerant inlet temperature to the heat exchanger;
a second temperature sensor configured to measure a refrigerant outlet temperature of the heat exchanger;
a third temperature sensor configured to measure the temperature of the outdoor environment;
a flow sensor configured to measure refrigerant flow to the heat exchanger;
A controller configured to switch between a compressor cooling cycle and a free cooling cycle based on measured data received by the first, second, and third temperature sensors and the first and second pressure sensors. and including
the controller for determining whether to switch between the compressor cooling cycle and the free cooling cycle;
liquid refrigerant enthalpy at the refrigerant inlet of the heat exchanger calculated based on the refrigerant inlet pressure obtained from the first pressure sensor and the refrigerant inlet temperature obtained from the first temperature sensor;
vapor refrigerant enthalpy at the refrigerant outlet of the heat exchanger calculated based on the refrigerant outlet pressure obtained from the second pressure sensor and the refrigerant outlet temperature obtained from the second temperature sensor;
a liquid refrigerant density at a refrigerant inlet of the heat exchanger calculated based on the refrigerant inlet pressure obtained from the first pressure sensor and the refrigerant inlet temperature obtained from the first temperature sensor;
is used to calculate the exhaust heat load , and a table defining whether or not the current heat load can be extracted by a free cooling cycle according to the relationship between the exhaust heat load and the outdoor environment temperature. determining whether to operate the compressor refrigeration cycle or the free refrigeration cycle based on a table corresponding to exchanger refrigerant inlet temperatures ;
the compressor cooling cycle utilizes a compressor to cool server rack exhaust;
A cooling system wherein the free cooling cycle utilizes outside ambient air to cool the exhaust of the server rack. The controller uses the measured data to determine whether to switch between the compressor cooling cycle and the free cooling cycle based on the difference between the refrigerant outlet and the refrigerant inlet. determine the
A cooling system according to claim 1 . the heat load and outdoor ambient temperature values are compared to a predetermined table to determine whether to switch between the compressor cooling cycle and the free cooling cycle;
3. The cooling system of claim 2. the predetermined table includes data regarding whether the free cooling cycle can remove waste heat load for the outdoor environment temperature value and the coolant inlet temperature of the heat exchanger;
4. The cooling system of claim 3. A controller for a cooling system of a server rack, said cooling system comprising a heat exchanger, a plurality of measurement sensors, and a cooling cycle configured to provide compressor cooling and free cooling to said heat exchanger. a unit, the controller comprising:
a memory unit;
a processing unit;
I configured to receive refrigerant inlet pressure measurements to the heat exchanger, refrigerant outlet pressure measurements, refrigerant inlet temperature measurements, refrigerant outlet temperature measurements, outdoor environment temperature measurements, and refrigerant flow measurements from the plurality of measurement sensors. /O units and
Based on the refrigerant inlet pressure measurement to the heat exchanger, the refrigerant outlet pressure measurement, the refrigerant inlet temperature measurement, the refrigerant outlet temperature measurement, the outdoor environment temperature measurement, and the refrigerant flow measurement, the processing unit: configured to output a command to switch between a compressor cooling cycle and a free cooling cycle to the cooling cycle unit;
to determine whether to switch between the compressor cooling cycle and the free cooling cycle;
a liquid refrigerant enthalpy at the refrigerant inlet of the heat exchanger calculated based on the refrigerant inlet pressure measurement and the refrigerant inlet temperature measurement;
a vapor refrigerant enthalpy at the refrigerant outlet of the heat exchanger calculated based on the refrigerant outlet pressure measurement and the refrigerant outlet temperature measurement;
a liquid refrigerant density at the refrigerant inlet of the heat exchanger calculated based on the refrigerant inlet pressure measurement and the refrigerant inlet temperature measurement;
is used to calculate the exhaust heat load, and a table defining whether or not the current heat load can be extracted by the free cooling cycle according to the relationship between the exhaust heat load and the value of the outdoor environment temperature measurement. determining whether to operate the compressor refrigeration cycle or the free refrigeration cycle based on a table corresponding to the refrigerant inlet temperatures of the heat exchangers of the . measuring the refrigerant inlet pressure to the heat exchanger;
measuring the refrigerant outlet pressure of the heat exchanger;
measuring a refrigerant inlet temperature to the heat exchanger;
measuring the refrigerant outlet temperature of the heat exchanger;
measuring the temperature of the outdoor environment;
measuring refrigerant flow to the heat exchanger;
Compressor cooling cycle or free cooling cycle based on the relationship between the refrigerant inlet pressure, the refrigerant outlet pressure, the refrigerant inlet temperature, the refrigerant outlet temperature, the outdoor environment temperature, and the refrigerant flow rate. determining which of the
including
to determine whether to operate the compressor cooling cycle or the free cooling cycle;
a liquid refrigerant enthalpy at the refrigerant inlet of the heat exchanger calculated based on the measured refrigerant inlet pressure and the measured refrigerant inlet temperature;
a vapor refrigerant enthalpy at the refrigerant outlet of the heat exchanger calculated based on the measured refrigerant outlet pressure and the measured refrigerant outlet temperature;
a liquid refrigerant density at the refrigerant inlet of the heat exchanger calculated based on the measured refrigerant inlet pressure and the measured refrigerant inlet temperature;
is used to calculate the exhaust heat load, and a table defining whether or not the current heat load can be extracted by the free cooling cycle according to the relationship between the exhaust heat load and the measured value of the outdoor environment temperature. A cooling method for a server rack that identifies whether to operate the compressor refrigeration cycle or the free refrigeration cycle based on a table corresponding to the current heat exchanger refrigerant inlet temperature . to the computer,
measuring the refrigerant inlet pressure to the heat exchanger;
measuring the refrigerant outlet pressure of the heat exchanger;
measuring a refrigerant inlet temperature to the heat exchanger;
measuring the refrigerant outlet temperature of the heat exchanger;
measuring the temperature of the outdoor environment;
measuring refrigerant flow to the heat exchanger;
Compressor cooling cycle or free cooling cycle based on the relationship between the refrigerant inlet pressure, the refrigerant outlet pressure, the refrigerant inlet temperature, the refrigerant outlet temperature, the outdoor environment temperature, and the refrigerant flow rate. determining which of the
and
to determine whether to operate the compressor cooling cycle or the free cooling cycle;
a liquid refrigerant enthalpy at the refrigerant inlet of the heat exchanger calculated based on the measured refrigerant inlet pressure and the measured refrigerant inlet temperature;
a vapor refrigerant enthalpy at the refrigerant outlet of the heat exchanger calculated based on the measured refrigerant outlet pressure and the measured refrigerant outlet temperature;
a liquid refrigerant density at the refrigerant inlet of the heat exchanger calculated based on the measured refrigerant inlet pressure and the measured refrigerant inlet temperature;
is used to calculate the exhaust heat load, and a table defining whether or not the current heat load can be extracted by the free cooling cycle according to the relationship between the exhaust heat load and the measured value of the outdoor environment temperature. A program for executing processing for specifying whether to operate the compressor cooling cycle or the free cooling cycle based on a table corresponding to current refrigerant inlet temperatures of the heat exchanger .

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