CN110375451A - Improved cooling system for high density heat load - Google Patents

Abstract

The present invention provides an improved cooling system for high density heat loads. The cooling system includes: a plurality of primary cooling modules that circulate refrigerant through a respective one of a plurality of thermal loads; Supplemental refrigerant flow for the load associated with the failed primary cooling module.

Description

Improved cooling system for high density heat loads

This application is a divisional application of an invention application with the application number 201210599167.5 and the name "Improved Cooling System for High Density Heat Load" filed on December 27, 2012.

technical field

The present disclosure relates to pumped refrigerant cooling systems for precision cooling applications with 1+1 to N+1 primary cooling circuit redundancy.

Background technique

This section provides background information related to the present disclosure which is not necessarily prior art.

A data center is a room that contains many electronic devices, such as computer servers. Data centers and the equipment contained therein typically have optimal environmental operating conditions, particularly temperature and humidity. Climate control systems maintain the proper temperature and humidity in the data center.

The climate control system includes a cooling system that cools the air and provides cool air to the data center. The cooling system may include air conditioning units, such as computer room air handling (CRAH) or computer room air conditioning (CRAC) units, that cool the air provided to the data center. A data center may have a raised floor and cool air is brought in through vents in the raised floor. The raised floor can be constructed to provide plenums between the cold air outlets of the CRAH (or CRAHs) or CRAC (or CRACs) and vents in the raised floor, or alternatively, using ducts such as ) of the separate air chamber (plenum).

Data centers can also have hard floors. CRACS may for example be placed in rows of electronic equipment, their cooling air supplies may be arranged towards respective cold aisles, or CRACS may be arranged along the walls of a data center. Equipment racks at a data center may be arranged in a hot aisle/cold aisle configuration with the equipment racks arranged in rows. Typically the cold air inlet of a row of racks at the front of the rack faces the cool air inlet of a row of racks passing through the cold aisle, and the hot air outlet of a row of racks faces the hot air outlet of a row of racks passing through the hot aisle .

One type of cooling system uses a pumped refrigerant cooling unit, such as that used in the XD system available from the Liebert Company of Columbus, Ohio. The Liebert XD system has two cooling circuits, which may also be referred to as cooling circuits or cycles. The primary circuit uses chilled water or a refrigerant such as R407C, and the secondary circuit uses a pumped refrigerant such as R134a. The primary circuit includes a fluid to fluid heat exchanger for cooling the pumped refrigerant circulating in the secondary circuit. The secondary loop includes one or more phase change cooling assemblies with fluid to an air heat exchanger through which a refrigerant is circulated to cool the air flowing through the heat exchanger. Depending on the particular design, a heat exchanger may typically include an evaporator coil and a flow regulator or expansion valve.

The basic diagram for the two cooling loops (or cycles) of the Liebert XD system is shown and described in USSN 10/904,889, entitled "Cooling System for High Density Heat Load," the entire disclosure of which is incorporated Here for reference. Figures 1 and 2 of the aforementioned application are included herein as Figures 1 and 2 for description.

Referring to FIGS. 1 and 2 , the disclosed cooling system 10 includes a first cooling circuit 12 (primary cooling circuit) in thermal communication with a second circuit 14 (secondary cooling circuit). The disclosed cooling system 10 also includes a control system 90 . The first and second cycles 12 and 14 each include an independent working fluid. The working fluid in the second cycle is any volatile fluid suitable as a conventional refrigerant, including but not limited to chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), or hydrochlorofluorocarbons (HCFCs). The use of a volatile working fluid eliminates the use of water in the vicinity of sensitive equipment, as is sometimes done in conventional systems for cooling computer rooms. The second cycle 14 includes a pump 20 , one or more first heat exchangers (evaporators) 30 , a second heat exchanger 40 , and tubes interconnecting the different components of the second cycle 14 . The second cycle 14 is not a vapor compression refrigeration system. Instead, the second cycle 14 uses a pump 20 instead of a compressor to circulate the volatile working fluid for heat dissipation from the heat load. The pump 20 is preferably capable of pumping the volatile working fluid throughout the second cooling cycle 14 and is preferably controlled by a control system implemented by the controller 90 .

The first heat exchanger 30 is a gas-liquid heat exchanger, and when the second working fluid passes through the second fluid path in the first heat exchanger 30, the gas-liquid heat exchanger flows from a heat load (not shown) to a second 2. The working fluid dissipates heat. For example, the gas-liquid heat exchanger 30 may include a plurality of tubes for the working fluid arranged to allow hot air to pass therebetween. It is understood that any number of gas-to-liquid heat exchangers known in the art can be used in the disclosed cooling system 10 . A flow regulator 32 may be connected between the piping 22 and the inlet of the evaporator 30 to regulate the flow of working fluid into the evaporator 30 . Flow regulator 32 may be a solenoid valve or any kind of device for regulating flow in cooling system 10 . Flow regulator 32 preferably maintains a constant output flow independent of inlet pressure above the system operating pressure range. In the embodiment of FIGS. 1 and 2 , the second cycle 14 includes a plurality of evaporators 30 and a flow regulator 32 connected to the pipe 22 . However, the disclosed system may have one or more than one evaporator 30 and flow regulator 32 connected to tube 22 .

The second heat exchanger 40 is a liquid-to-liquid heat exchanger that transfers heat from the second working fluid to the first cycle 12 . It will be appreciated that any number of liquid-to-liquid heat exchangers known in the art may be used with the disclosed cooling system 10 . For example, liquid-to-liquid heat exchanger 40 may include a plurality of hoses for one fluid disposed in a chamber or shell containing a second fluid. Coaxial ("pipe-in-pipe") exchangers may also be suitable. In certain embodiments, it is preferred to use a plate heat exchanger. The second cycle 14 may also include a receiver 50 connected to the outlet pipe 46 of the second heat exchanger 40 by a receiver output line 52 . The receiver 50 may store and collect working fluid in the second cycle 14 to allow for changes in temperature and thermal load.

In one embodiment, a gas-to-liquid heat exchanger 30 may be used to cool a room containing computer equipment. For example, the fan 34 may draw air from the room (heat load) through the heat exchanger 30 where the second working fluid absorbs heat from the air. In another embodiment, the air-to-liquid heat exchanger 30 may be used to remove heat directly from heat-generating electronic equipment (heat loads) by installing the heat exchanger 30 at or near the equipment. For example, the electronics are typically contained within a housing (not shown). A heat exchanger 30 may be mounted to the housing, and a fan 34 may draw air from the housing through the heat exchanger 30 . Alternatively, the first heat exchanger 30 may be an alternating type heat exchanger (eg cold plates) which is in direct thermal contact with the heat source. Those skilled in the art will appreciate that the heat transfer rates, dimensions, and other design parameters of the disclosed cooling system 10 components depend on the disclosed cooling system 10 dimensions, the magnitude of the thermal load being managed, and other details of the particular implementation.

In the embodiment of the disclosed cooling system 10 depicted in FIG. 1 , the first circuit 12 includes a chilled water circuit 60 connected to the liquid-to-liquid heat exchanger 40 of the second circuit 14 . In particular, the second heat exchanger 40 has first and second portions or fluid paths 42 and 44 in thermal communication with each other. A second path 42 for a volatile working fluid is connected between the first heat exchanger 30 and the pump 20 . The first fluid path 44 is connected to a chilled water circulation 60 . Chilled water cycle 60 may be similar to those known in the art. Chilled water system 60 includes a first working fluid that absorbs heat from a second working fluid through liquid-to-liquid heat exchanger 40 . The first working fluid is then cooled by techniques known in the art for conventional chilled water cycles. In general, the first working fluid can be volatile or non-volatile. For example, in the embodiment of FIG. 1, the first working fluid may be water, ethylene glycol, or a mixture thereof. Thus, the embodiment of the second cycle 14 in Figure 1 can be configured to accommodate the pump 20, the gas-to-liquid heat exchanger 30 and the liquid-to-liquid heat exchanger 40, and can be connected to existing chilled water services, such as those available in the building Contains cooled equipment.

In the embodiment of the cooling system 10 disclosed in Figure 2, the second circuit 14 is substantially the same as described above. The first cycle 12 however includes a flow path 44 or first portion of a vapor compression refrigeration system 70 connected to the heat exchanger 40 of the second cycle 14 . As in the embodiment of FIG. 1 , instead of using chilled water to remove heat from the second cycle 14 , the refrigeration system 70 in FIG. 2 is directly connected to the liquid-to-liquid heat exchanger 40 or the "other half" thereof. Vapor-compression refrigeration system 70 may be substantially similar to those known in the art. A typical vapor compression refrigeration system 70 includes a compressor 74 , a condenser 76 and an expansion device 78 . Tubes 72 interconnect these components and to the first flow path 44 of the heat exchanger 40 .

Vapor compression refrigeration system 70 removes heat from a second working fluid passing through second heat exchanger 40 by absorbing heat from exchanger 40 with the first working fluid and radiating heat to the environment (not shown). For example, in the embodiment of FIG. 2, the first working fluid may be any conventional chemical refrigerant including, but not limited to, chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), or hydrochlorofluorocarbons (HCFCs). Expansion device 78 may be a valve, orifice, or other device known to those skilled in the art to create a pressure drop across the working fluid. Compressor 74 may be any type of compressor known in the art so as to be suitable for refrigerant service, such as reciprocating compressors, scroll compressors, and the like. In the embodiment depicted in Figure 2, the cooling system 10 is integral. For example, vapor compression refrigeration system 70 may be part of a single unit that also houses pump 20 and liquid-to-liquid heat exchanger 30 .

During operation of the disclosed system, pump 20 moves working fluid through tube 22 to gas-liquid heat exchanger 30 . The pump increases the pressure of the working fluid while its enthalpy remains substantially the same. The pumped working fluid can thus enter the gas-liquid heat exchanger or evaporator 30 of the second cycle 14 after passing through the flow regulator 32 . A fan 34 may draw air from the heat load through the heat exchanger 30 . When hot air enters the air-to-liquid heat exchanger 30 from a heat load (not shown), the volatile working fluid absorbs heat. As the fluid warms up through the heat exchanger, some of the volatile working fluid will evaporate. In a fully loaded cooling system 10, the fluid exiting the first heat exchanger 30 may be substantially steam. Vapor flows from heat exchanger 30 to liquid-liquid heat exchanger 40 through tube 36 . In the tube or return line 36, the working fluid is substantially in a vapor state, and while its enthalpy remains substantially constant, the pressure of the fluid drops. In the liquid-to-liquid heat exchanger 40 , vapor in the second fluid path 42 is condensed by transferring heat to the first, cooler fluid of the first cycle 12 in the first fluid path 44 . Condensed working fluid exits heat exchanger 40 through tube 46 and enters pump 20 where second cycle 14 may repeat.

The first cooling cycle 12 operates in conjunction with the second cycle 14 to remove heat from the second cycle 14 by absorbing heat from the second working fluid into the first working fluid and rejecting the heat to the environment (not shown). As noted above, the first cycle 12 may include a chilled water system 60 as shown in FIG. 1 or a vapor compression refrigeration system 70 as shown in FIG. 2 . During operation of chilled water system 60 of FIG. 1 , for example, a first working fluid may flow through first fluid path 44 of heat exchanger 40 and may be cooled in a cooling tower (not shown). During operation of the refrigeration system 70 of FIG. 2 , for example, a first working fluid passes through the first portion 44 of the liquid-to-liquid heat exchanger 40 and absorbs heat from the volatile fluid in the second cycle 14 . The working fluid evaporates during the process. The vapor is delivered to compressor 74 where the working fluid is compressed. Compressor 74 may be a reciprocating, scroll, or other type of compressor known in the art. After being compressed, the working fluid is sent through a discharge line to condenser 76 where heat is dissipated from the working fluid to an external heat sink, eg, the outdoor environment. Upon exiting condenser 76 , the refrigerant flows through the liquid line to expansion device 78 . As the refrigerant passes through the expansion device 78, the first working fluid experiences a pressure drop. Upon exiting the expansion device 78 , the working fluid flows through the first fluid path of the liquid-to-liquid heat exchanger 40 , which acts as an evaporator for the refrigeration cycle 70 .

Data center providers are constantly looking to improve reliability and up time from climate control systems. Accordingly, there is a continuing need for data center providers to improve redundancy in climate control systems in order to prevent unnecessary downtime of cooling electronics due to unexpected disruptions to the operation of the climate control system. One mode of redundancy consists in duplicating each element of the cooling system, such as the first cooling circuit 12 and the second cooling circuit 14 . This overall redundancy can be costly and very complex to design, implement and control of the cooling system. In a different configuration, redundancy may include the implementation of a cooling circuit, including for example a second reduced implementation of the second cooling circuit 14 shown in FIGS. 1 and 2 . The reduced redundancy may include the second pump unit 20 and half of the heat exchangers provided in the primary cooling system. Implementing these redundant systems will also require associated detection and control. Accordingly, the approximate cost of such a system can be in the range of 50% of the total base cooling load cost.

Another approach to redundancy to minimize equipment may include overprovisioning environments in complex, interleaved configurations by utilizing cooling components. A fault in one cooling circuit can thus cross over to the region of a damaged cooling circuit via other cooling circuits. This overprovisioning again presents increased costs to the customer, including additional pumps, cooling components, probing, piping and control systems over and above the conventional configuration shown in FIGS. 1 and 2 .

Contents of the invention

This section provides an overview of the disclosure, and is not a comprehensive disclosure of the full scope of its features.

The cooling system has a plurality of pump units supplying cooling fluid to the load. In various configurations, the pump unit supplies a portion of the cooling fluid to the load. If a pump unit experiences a fault condition, the output of the other pump units increases to maintain sufficient fluid flow to the load. In another construction, an additional pump unit is provided which normally does not supply fluid flow to the load. When one of the other pump units experiences a fault condition, the other pump unit is activated to provide fluid flow to the load. In another construction, a plurality of pump units provides fluid flow to respective ones of the plurality of loads. When one pump unit experiences a failure condition, a redundant pump unit is inserted into the circuit to supply fluid flow to loads associated with the pump unit under the failure condition.

The cooling system includes a first cooling module having a first variable speed pump that circulates refrigerant through a load. The cooling system also has a second cooling module with a second variable speed pump that circulates refrigerant through the load. The first and second variable speed pumps operate at less than full speed. When one of the primary cooling module or the secondary cooling module is unable to adequately circulate the refrigerant through the load, the speed of the variable speed pump of the other of the primary or secondary cooling modules is increased to compensate for one cooling module.

The cooling system includes a plurality of cooling modules that supply refrigerant to a load, each of the plurality of cooling modules having a variable speed pump for supplying refrigerant to the load. Variable speed pumps run below full speed. When one of the plurality of cooling modules cannot adequately supply refrigerant, the speed of the variable speed pump of at least one of the other of the plurality of cooling modules having variable speed is increased to compensate for one of the plurality of cooling modules.

A method for providing redundant cooling in a cooling system includes providing multiple cooling modules. A plurality of cooling modules cooperate to pump cooling fluid to at least one heat load. The cooling modules operate at variable speeds. When one of the plurality of cooling modules experiences a deceleration, the speed of another of the plurality of cooling modules increases. When one of the plurality of cooling modules experiences an increase in speed, the speed of another of the plurality of cooling modules decreases.

A method for providing redundant cooling modules in a cooling system includes providing a first cooling module. The first cooling module provides cooling fluid to the heat load. The first cooling module operates at a variable speed. The first cooling module has a first normal operating speed that is less than full speed. A second cooling module is provided. The second cooling module provides cooling fluid to the heat load. The second cooling module operates at a variable speed, the second cooling module has a second normal operating speed, the second normal operating speed is less than full speed. When one of the first cooling module or the second cooling module is operating below its respective normal operating speed, the speed of the other of the first cooling module or the second cooling module is increased. When one of the first cooling module or the second cooling module experiences an increase in speed, the speed of the first cooling module or the second cooling module is reduced.

The cooling system includes: primary cooling module. The primary cooling module supplies refrigerant to the load. When insufficient refrigerant flow of the primary cooling module is detected, the secondary cooling module provides supplementary refrigerant flow to the load.

The cooling system includes: a plurality of primary cooling modules. The primary cooling modules supply refrigerant to respective ones of the plurality of heat loads. The secondary cooling module selectively provides supplemental refrigerant flow through loads associated with the primary cooling module for which a failure has been detected.

A method of providing redundant cooling in a cooling system includes providing a primary cooling module with a loop. The primary cooling module provides cooling fluid to the heat load. A secondary cooling module is provided, and operation of the secondary cooling module is initiated upon detection of a fault in the primary cooling module. A secondary cooling module is inserted into the loop, the secondary cooling module provides cooling fluid to the heat load, and the primary cooling module is deactivated.

A method for redundant control of a cooling system includes providing a plurality of primary cooling modules. The primary cooling modules circulate refrigerant through their respective heat loads. A secondary cooling module is provided. When a failure is detected in one primary cooling module, the secondary cooling module selectively provides supplemental refrigerant flow through the load associated with the optional primary cooling module.

Description of drawings

The drawings described herein are for illustrative purposes only of alternative embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

Figure 1 is a schematic diagram of a primary cooling circuit connected to a cooling water circuit;

Figure 2 is a schematic diagram of a cooling system with a primary cooling circuit utilizing a vapor compression refrigeration system;

Figure 3 is a schematic illustration of a cooling system arranged in accordance with various embodiments;

Figure 4 is a schematic diagram of a cooling system arranged in accordance with various embodiments;

5 is a flowchart describing a process for providing redundant cooling capabilities in a system having redundant cooling sources such as those of FIGS. 3 and 4;

Figure 6 is a schematic diagram of a cooling system arranged according to another embodiment;

FIG. 7 is a flowchart describing a process for providing redundant cooling in the system of FIG. 6;

Figure 8 is a schematic diagram of a cooling system arranged in accordance with another embodiment; and

FIG. 9 is a flowchart describing a process for providing redundant cooling in the system of FIG. 8 .

Corresponding reference characters indicate corresponding parts throughout the different views of the drawings.

Detailed ways

Exemplary embodiments will now be described more fully with reference to the accompanying drawings.

The exemplary embodiments are provided so that the scope of the present disclosure will be fully conveyed and fully conveyed to those skilled in the art. Numerous specific details are set forth, such as specific components, equipment and methods, to provide a thorough understanding of embodiments of the present disclosure. To those skilled in the art, specific details need not be employed, the illustrated embodiments may be embodied in many different forms and neither should be combined to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. For example, as used herein, the singular forms "a", "an" and "each" may also include the plural forms; unless the context clearly dictates otherwise. The terms "consisting of", "comprising", "including" and "having" are inclusive and specify the presence of certain features, integers, steps, operations, elements and/or parts, but do not exclude one or more The presence or addition of multiple other features, integers, steps, operations, elements, parts and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as having to be performed in the particular order discussed or illustrated unless explicitly identified as an order of performance. It is also understood that additional or alternative steps may be used.

When an element or layer refers to being "on," "joined," "connected" or "in conjunction with" another element or layer, it can be directly on, joined, connected, or joined to another element or layer , or can be understood as an intervening element or layer. In contrast, when an element is referred to as being "on," "directly engaged with," "directly connected to" or "directly coupled with" another element or layer, it may be understood that there are no intervening elements or layers present. Other words used to describe the relationship between elements should be construed in a like fashion (eg, "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed products.

Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. . These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first," "second," and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the illustrated embodiments.

Spatially related terms such as "inside", "outside", "below", "beneath", "lower", "above", "above" and similar terms may The description is used herein for ease to describe the relationship of one element or feature illustrated in the figures to another element or feature. Spatially relative terms may be used 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" another element or feature would then be oriented "above" the other element or feature. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device may be oriented in different ways (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

FIG. 3 depicts a schematic diagram of a pumped refrigerant cooling system 100 arranged in accordance with various embodiments. The pumped refrigerant cooling system 100 includes a pair of pump units 120a, 120b. The pump units 120 a , 120 b provide working fluid that is pumped to the load 122 . Load 122 is placed in an environment to be cooled, such as a data room. In some cases, n elements may be described using common reference numerals without using a, b...n. Further, the same reference numerals will be used to describe the same elements throughout the specification. In various configurations, load 122 may include multiple loads 122 , collectively referred to as loads 122 .

Each pump unit 120 includes a first pump 124 and a second pump 126 that pump working fluid at high pressure to a respective check valve 132 , 134 . The pumps 124, 126 may be provided in a first, redundant configuration. Optionally, pumps 124 , 126 may be arranged to cooperate to supply fluid at output pressure and flow through respective check valves 132 , 134 to output line 136 . The pumps 124, 126 can be controlled to provide redundant and coordinated operation.

Fluid pumped through output line 136 is applied to load 122 . Load 122 may take many configurations, including configurations similar to evaporator 30 of FIGS. 1 and 2 . Load 122 is placed in an environment where heat removal is desired, where load 122 transfers heat to fluid pumped through output line 136 . Fluid from output line 136 enters load 122 at a first temperature and exits load 122 in line 140 at an elevated temperature. Fluid pumped through load 122 may also change from a liquid phase to a gas phase. A line 140 , commonly referred to as an inlet line 140 , returns working fluid to the pump unit 120 .

Fluid in inlet line 140 is input to condenser 138 . Condenser 138 receives the working fluid at a first, elevated temperature and rejects heat in the working fluid to an output fluid at a reduced temperature. Fluid passing through condenser 138 changes from a gas phase to a liquid phase. The fluid output at the reduced temperature is output through return line 144 input to receiver 142 . The receiver 142 stores working fluid used by the pump unit 120 . Receiver 142 returns working fluid to the respective pump 124 , 126 via receiver output line 143 . Bypass line 145 bypasses the receiver so that fluid flows from the outlet of condenser 138 directly to receiver output line 143 , thereby bypassing receiver 142 . Receiver output line 143 provides working fluid to pumps 124 , 126 via respective pump input lines 148 , 150 . A controller 146 is connected to each pump unit 120 and sends and receives sense and control signals from and to each main pump unit 120 .

In operation, the respective pump units 120a, 120b each provide approximately 50% of the required refrigerant flow to the load 122 . When a condition occurs, ie, when either pump unit 120a or 120b provides less than a predetermined capacity (eg, 50%), the other pump unit 120a, 120b may be controlled by the controller 146 to increase output. The output can be increased to maintain sufficient fluid flow to the load 122 by increasing the output of the other pump units 120a, 120b. The output of each pump unit 120a, 120b may return to a predetermined operation, such as 50% of full load, when it is determined that the previously determined pump unit being supplied with less than full capacity is fully brought back online.

FIG. 4 depicts a schematic diagram of a pumped refrigerant cooling system 200 arranged in accordance with various embodiments. FIG. 4 is an arrangement similar to FIG. 3 described above, but including more than two pump units 120 . The pumped refrigerant cooling system 200 includes a plurality of primary pump units 120a, 120b... 120n. Each pump unit 120a, 120b...120n provides working fluid to be pumped to a load 122 or a plurality of loads 122 arranged side by side. Load 122 is placed in an environment to be cooled, such as a data room. It should be noted that n may be any positive integer and represents an optional number of similarly arranged elements in the figure. For example, pump units 120a, 120b...120n refer to N pump units. The number of pump units may vary depending on the particular implementation of the pumped refrigerant cooling system 200 described herein. This numbering convention is used to describe other similar elements. In some cases, n pump units may be collectively described with reference numerals instead of a, b...n.

The operation of the pumped refrigerant cooling systems 100, 200 of FIGS. 3 and 4 will be described. The pumped refrigerant cooling system 200 of FIG. 4 operates similarly to the pumped refrigerant cooling system 100 of FIG. 3 . In particular, the pumped refrigerant cooling system 200 operates similarly except that it has multiple pump units 120 instead of the pair of pump units 120 depicted in FIG. 3 .

In operation, the pump unit 120 operates at less than full capacity to share a portion of the fluid flow provided to the load 122 . Allocation can be equal in various structures. In another structure, assignments need not be equal. When any of the N pump units are deactivated by the controller 146 , the controller 146 may also increase the output of the remaining (N−1) pump units 120 to the load 122 to maintain sufficient refrigerant flow through the load 122 . As a non-limiting example, if N=3, and the refrigerant flow is divided equally among the three pump units 120 , then each pump unit uses 33.33% of the total refrigerant flow to the load 122 . If any of the N units are deactivated by the controller 146 , the remaining (N−1) units provide the remaining refrigerant flow to the load 122 . In this case, each of the remaining (N-1) units will provide approximately 50% of the total refrigerant flow to load 122 . In another non-limiting example, if N=5, each primary pump unit 120 may provide 20% of the total refrigerant flow to the load 122 . If the controller 146 deactivates one pump unit 120, the remaining four pump units provide 25% of the total refrigerant flow. While the examples described herein are directed to each pump unit 120 providing equal refrigerant flow, those skilled in the art will recognize that the pump units 120 can provide unequal flow, and that sufficient refrigerant flow can be provided as long as the pump units 120 remain on-line Just give the load 122.

FIG. 5 depicts a block diagram for providing redundant pump units in the pumped refrigerant cooling system of FIGS. 3 and 4 . The process begins at start block 151 and proceeds to decision block 152 . Decision block 152 decides whether a fault has been detected in one of the pump units 120 . If no fault is detected, control continues back to the beginning of decision block 152, which continues to monitor whether a fault is detected in the pump unit. If a fault condition is detected in a pump unit, control passes to block 154 where the controller 146 provides a signal to increase the speed of (N-1) pump units other than the pump unit in which the fault condition occurred. Once the output of (N−1) pump units 120 has increased sufficiently, control continues to block 156 . At block 156, the controller 146 adjusts the output of the pump unit 120 of the pump unit 120 in which the fault condition occurred. The controller 146 may reduce the required output of the pump unit 120 under the fault condition or disable the pump unit 120 under the fault condition. Control then passes to block 158 which monitors for an indication that the pump unit 120 returned to normal operation under a fault condition. If the pump unit under the fault condition does not return to normal operation, then control continues back to the beginning of decision block 158 . Control proceeds to block 160 when it is determined that the pump unit under the fault condition is fully operational. At block 160, the controller 146 generates a control signal to restore the pump unit 120 from the previous fault condition to its normal operating output. Control then continues to block 162. At block 162, the controller 146 reduces the speed of (N-1) pump units 120 whose speeds were previously increased to compensate for pump units 120 that were previously deactivated or decreased in output during the fault condition. Control then continues to block 164, ending the process.

FIG. 6 depicts a cooling system 300 arranged in accordance with various embodiments. The cooling system 300 includes pump units 120a, 120b...120n arranged similarly to the pump unit 120 previously described herein. The pump unit 120 provides fluid flow to a pair of cooling modules or loads 122a, 122b shown disposed side-by-side. The structure of Figure 6 is directed to a system comprising a pump unit that operates as a backup pump unit that is activated when one or more of the other (N-1) pump units must be deactivated. When the other pump units are deactivated by the controller 146, then the backup pump unit 120 becomes active and inserted into the circuit.

Figure 6 is configured similarly to the various embodiments described above. Figure 6 also includes inlet valves 170a, 170b...170n in communication with respective pump units 120a, 120b...120n. Figure 6 also includes outlet valves 172a, 172b...172n in communication with respective pump units 120a, 120b...120n. The inlet valve 170 and outlet valve 172 cooperate to enable and disable fluid flow into and out of the respective pump unit 120 . Pump unit 120n of the N pump units acts as a backup pump unit and when one or more other (N-1) pump units 120 are deactivated, the backup pump unit is activated to provide replacement for one or more other (N-1) pump units. The fluid flow of the fluid flow of the pump unit 120.

FIG. 7 depicts a block diagram of the operation of the pumped refrigerant cooling system 300 of FIG. 6 . Control begins at start block 180 and continues to decision block 182 . At decision block 182 , the controller 146 or other portion of the system 300 determines whether a fault condition has been detected in the pump unit 120 . If no fault is detected, control continues back to decision block 182 . If a fault is detected, control continues to block 184 . At block 184, in this example, the controller 146 brings the backup pump unit 120n online so that the backup pump unit 120n can provide pressurized fluid flow. Control then continues to block 186 where the controller 146 brings the standby pump unit 120n into the circuit by opening the inlet valve 170n and outlet valve 172n. This enables the backup pump unit 120n to provide fluid flow to the load 122 . Control then continues to block 188 where the pump unit 120 under the fault condition is removed from the circuit. The controller 146 removes the faulty pump unit 120 from the circuit by closing its respective inlet valve 170 and outlet valve 172 to remove the pump unit 120 under the fault condition. Control then continues to decision block 190 . At decision block 190, the controller 146 determines whether the pump unit in the fault condition is determined to be fully operational. If the deactivated pump unit is not being fully operated, control returns to decision block 190 . If the pump unit under the fault condition is determined to be fully operational, control continues to block 192 and the controller 146 brings the fully operational pump unit 120 back online so that it can provide fluid flow of cooling fluid to the load 122 . Control continues to block 194 once the pump unit under the fault condition is brought online. At block 194 , the pump unit under the fault condition is put into the circuit by opening its respective inlet valve 170 and outlet valve 172 to allow fluid to flow into the load 122 . Control then continues to block 196. At block 196, the controller 146 removes the backup pump unit 120n from the circuit by closing the inlet valve 170n and the outlet valve 172n. Control then continues to block 198 where the controller 146 deactivates the backup pump unit 120 . Control then continues to end block 199.

FIG. 8 depicts a schematic diagram of a pumped refrigerant cooling system 400 with redundant pump units. As described above, the pumped refrigerant cooling system 400 includes a plurality of primary or primary pump units 120a, 120b... 120n. Each primary pump unit 120a, 120... 120n provides working fluid that is pumped to a load 122a, 122b... 122n. Each load 122a, 122b...122n is placed in an environment to cool the environment, such as a data room. It should be noted that n may be any positive integer and represents an optional number of similarly arranged elements in the figure. For example, pump units 120a, 120b...120n refer to N pump units. As also described above, those skilled in the art will recognize that the number of pump units may vary depending on the particular implementation of the pumped refrigerant cooling system 400 described herein.

Each main pump unit 120 includes a first pump 124 and a second pump 126 that pump working fluid at elevated pressure to a respective check valve (one-way valve) 132 , 134 . The pumps 124, 126 may be provided in a first, redundant configuration. Optionally, pumps 124 , 126 may be arranged to cooperate to supply fluid at output pressure and flow through respective check valves 132 , 134 to output line 136 . The pumps 124, 126 may be controlled to provide redundant and coordinated operation.

Fluid pumped through output line 136 is supplied to load 122 . Load 122 may take many configurations, including a configuration similar to evaporator 30 of FIGS. 1 and 2 . Load 122 is placed in the environment where it is desirable to transfer heat from the environment in which load 122 is located by transferring heat to the fluid pumped through output line 136 . Fluid from output line 136 enters load 122 at a first temperature and exits load 122 in line 140 at an elevated temperature. Fluid pumped through load 122 may also change from a liquid phase to a gas phase. A line 140 , commonly referred to as an inlet line 140 , returns working fluid to the main pump unit 120 .

Fluid in inlet line 140 is input to condenser 138 . Condenser 138 receives working fluid at a first, elevated temperature and transfers heat from the working fluid to output fluid at a reduced temperature. Fluid flowing through condenser 138 changes from a gas phase to a liquid phase. The fluid output at the reduced temperature is output through return line 144 to receiver 142 . The receiver 142 stores working fluid used by the pump unit 120 . Receiver 142 sends working fluid back to the respective pump 124 , 126 via receiver output line 143 . Bypass line 145 bypasses the receiver so that fluid flows from the outlet of condenser 138 directly to receiver output line 143 , thereby bypassing receiver 142 . Receiver output line 143 provides working fluid to pumps 124 , 126 via respective pump input lines 148 , 150 .

In addition to the main pump units 120a, 120b... 120n, a redundant or backup pump unit 120' is included in the pumped refrigerant cooling system 400 of Figure 8 . If any one of the main pump units 120a, 120b... 120n is disabled, the redundant pump unit 120' provides working fluid under pressure. In this manner, the pump unit 120' provides redundancy to other pump units, thereby maintaining uptime and providing cooling functionality to any loads 122 associated with the primary pump unit being deactivated.

The redundant or backup pump unit 120' is configured similarly to the pump unit 120 described above. The pump unit 120' also includes a spare liquid line 136' and a vapor line 140'. Fluid output from liquid backup line 136' may flow to each load 122a, 122b...122n. Fluid from the liquid backup line 136' flows through one of the backup outlet valves 208a, 208b...208n. Backup fluid lines 210a, 210b... 210n connect to respective backup outlet valves 208a, 208b... 208n and provide fluid in place of respective pump units 120a, 120b... 120n. The respective outlet valves 218a, 218b...218n may be closed to prevent fluid flow in the backup liquid lines 210a, 210b...210n from flowing into the respective pump units 120a, 120b...120n. The steam output from the loads 122a, 122b... 122n may be returned to the pump unit 120' through respective backup steam lines 214a, 214b... 214n. Spare steam lines 214a, 214b...214n are connected to respective spare inlet valves 212a, 212b...212n. Inlet valves 220a, 220b... 220n associated with respective pump units 120a, 120b... 120n prevent the flow of steam into optional respective pump units 120a, 120b... 120n. To effectuate control of the pumped refrigerant cooling system 400 , the controller 146 sends and receives monitoring and control signals to optional components of the pumped refrigerant cooling system 400 .

The operation of the system of FIG. 8 will be described. When the primary pump unit 120 has been disabled or must be disabled due to various operating conditions of the primary pump unit 120, the redundant pump unit 120' is activated to replace the disabled primary pump unit. For example, if the primary pump unit 120a needs to be deactivated, the redundant pump unit 120' will be activated to provide pumping action to the deactivated primary pump unit 120a. When this occurs, redundant pump unit 120' instead enters the cooling circuit from load 122a to provide fluid flow to load 122a. This is accomplished through the operation of valves 220a, 218a, 212a and 208a.

For example, to insert redundant pump unit 120' into the circuit to provide fluid to load 122a, inlet valve 212a and outlet valve 208a are opened to allow fluid to flow into and out of pump unit 120'. Similarly, inlet valve 220a and outlet valve 218b are closed to move pump unit 120a out of the circuit to provide fluid flow to load 122a. Once it is determined that the main pump unit 120a is to be restarted, thus requiring deactivation of the redundant pump unit 120', a process similar to that described above will take place.

FIG. 9 depicts a block diagram of the operation of the pumped refrigerant cooling system 400 of FIG. 8 . Control begins at start block 230 and continues to decision block 232 . At decision block 232, the controller 146 or other portion of the system determines whether a fault condition has been detected in the pump unit. If no fault condition is detected, control continues to block 234 . At block 234, the controller 146 brings the example spare pump unit 120' online so that the spare pump unit 120' can provide pressurized fluid flow. Control then continues to block 236, where the controller 146 places the spare pump unit 120' into the cooling circuit of the pump unit 120 under the failure condition. This occurs by opening the respective inlet valve 212 and outlet valve 208 . This enables pump unit 120' to provide fluid flow to load 122. Control then continues to block 238 where the pump unit 120 in the fault condition is removed from the circuit. The controller 146 removes the pump unit 120 in the fault condition from its respective cooling circuit by closing its respective inlet valve 220 and outlet valve 218 to remove the pump unit 120 in the fault condition.

Control continues to decision block 240 . At decision block 240, the controller 146 or other portion of the system determines when the pump unit under the fault condition is determined to be fully operational. If the pump unit under the fault condition is not fully operational, then control returns to decision block 240 . If the pump unit under the fault condition is fully operational, then control proceeds to block 242, and the controller 146 brings the fully operational pump unit 120 back online so that it can be reinserted into its respective cooling circuit to provide a fluid flow of cooling fluid to the pump unit 120. Load 122. Once the pump unit under the fault condition is brought online, control continues to block 244 . At block 244, the pump unit under the fault condition is placed into its respective cooling circuit by opening its respective inlet valve 220 and outlet valve 218 . Control then continues to block 246 . At block 226, the controller 146 removes the backup pump unit 120' from the cooling circuit by closing the respective backup inlet valve 212 and outlet valve 208. Control then continues to block 248, which takes the redundant pump unit 120' offline. Control then continues to end block 250 .

The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, are, however, advantageously interchangeable and can be used in alternative embodiments, even if not explicitly shown or described. The same can also be changed in many ways. Such modifications are not intended to be a departure from the invention, and all such modifications are intended to be included within the scope of the invention.

Claims (18)

1. A cooling system comprising: a plurality of primary cooling modules that circulate refrigerant through respective ones of the plurality of heat loads; and A secondary cooling module selectively provides supplemental refrigerant flow through a load associated with the primary cooling module for which a failure has been detected. 2. The cooling system of claim 1, wherein each primary cooling module further comprises: a plurality of first pumps for circulating refrigerant, the plurality of first pumps supplying refrigerant at a first temperature to respective loads associated with respective primary cooling modules; and A plurality of first condensers for receiving refrigerant from respective loads associated with respective primary cooling modules, the refrigerant received by the respective condensers at a temperature greater than a first temperature. 3. The cooling system of claim 2, wherein the secondary cooling module further comprises: a second pump for supplying refrigerant, the second pump supplying refrigerant at the first temperature to a load associated with the primary cooling module for which a failure has been detected; and A second condenser for receiving refrigerant from a load associated with the primary cooling module for which a failure has been detected, the refrigerant received by the second condenser having a temperature higher than the first temperature. 4. The cooling system of claim 3, further comprising: a plurality of inlet valves associated with the respective primary cooling modules for controlling fluid flow between the inlets of the respective loads and the respective primary cooling modules and the secondary cooling modules; and A plurality of outlet valves associated with the respective primary cooling modules for controlling fluid flow between the outlets of the respective loads and the respective primary and secondary cooling modules. 5. A method for providing redundant control of a cooling system comprising: providing a plurality of primary cooling modules that circulate refrigerant through respective heat loads; and Secondary cooling modules are provided that selectively provide supplemental refrigerant flow through loads associated with the respective primary cooling module when a failure is detected in one of the primary cooling modules. 6. The method of claim 5, further comprising removing the one primary cooling module from a circuit associated with the one primary cooling module. 7. The method according to claim 5, further comprising: initiating operation of the secondary cooling module when a failure is detected in one of the primary cooling modules; inserting a secondary cooling module into the circuit of said one primary cooling module, the secondary cooling module providing cooling fluid to the heat load; and The one primary cooling module is deactivated. 8. The method of claim 7, further comprising removing said one primary cooling module from the circuit. 9. The method of claim 7, further comprising returning the cooling system to normal operation, said returning the cooling system to normal operation comprising: commencing operation of said one primary cooling module when a fault is no longer detected; inserting said one primary cooling module into a circuit for providing cooling fluid to a heat load; and Deactivate the secondary cooling module. 10. The method of claim 9, further comprising removing the secondary cooling module from the circuit. 11. The method according to claim 7, further comprising: supplying refrigerant at a first temperature to loads associated with respective primary cooling modules; and Refrigerant is received from a load associated with a respective primary cooling module, the refrigerant received by the first condenser at a temperature greater than a first temperature. 12. The method according to claim 7, further comprising: controlling fluid flow between the inlet of the respective load of a primary cooling module for which a failure has been detected and the secondary cooling module; and Fluid flow is controlled between the outlet of the respective load of a primary cooling module for which a failure has been detected and the secondary cooling module. 13. The method according to claim 5, further comprising: supplying refrigerant at a first temperature to a load associated with the primary cooling module for which a failure has been detected; and Refrigerant is received from a load associated with the primary cooling module for which a failure has been detected, the temperature of the refrigerant received from the load being higher than a first temperature. 14. The method of claim 13, further comprising receiving the refrigerant in a liquid state from the second condenser. 15. The method of claim 13, further receiving the refrigerant in a liquid state from the second condenser. 16. The method according to claim 5, further comprising: supplying refrigerant at a first temperature to loads associated with respective primary cooling modules; and Refrigerant is received from a load associated with a respective primary cooling module, the refrigerant received by the first condenser at a temperature greater than a first temperature. 17. The method according to claim 5, further comprising: supplying refrigerant at a first temperature to a load associated with the primary cooling module for which a failure has been detected; and Refrigerant is received from a load associated with the primary cooling module for which a failure has been detected, the temperature of the refrigerant received from the load being higher than a first temperature. 18. The method according to claim 5, further comprising: controlling fluid flow between the inlet of the respective load of a primary cooling module for which a failure has been detected and the secondary cooling module; and Fluid flow is controlled between the outlet of the respective load of the one primary cooling module for which a failure has been detected and the secondary cooling module.