Refrigeration circuit for cooling system

Abstract

A cooling system includes a first evaporator configured to output a first coolant at a first temperature and a second evaporator configured to output a second coolant at a second temperature. The first evaporator is configured to be flooded and the second evaporator is configured to be dry. The cooling system further includes a liquid receiver coupled between the first evaporator and the second evaporator. The liquid receiver is configured to output a liquid through a first outlet and to output a gas through a second outlet.

Description

BACKGROUND1. Field of the Invention

[0001] The present invention relates to cooling systems, and more particularly to cooling systems used with information technology (IT) equipment racks and enclosures used to support data processing, networking and telecommunications equipment, and to a refrigeration circuit capable of achieving two different evaporation levels to accommodate different cooling systems.2. Discussion of Related Art

[0002] Cooling systems for removing heat in conditioned spaces, such as IT environments, use heat transport fluids, such as air, water, or refrigerant, to transport heat energy from indoors to outdoors. Many cooling systems rely on the refrigeration cycle as the primary means of cooling. Pumped and blown refrigerant systems provide isolation between the primary heat removal system and IT equipment.

[0003] In some embodiments, the space being cooled is a data center or IT environment. A data center may include one or more rooms or spaces that contain rows of equipment racks designed to house electronic equipment, such as data processing, networking, and telecommunications equipment. During operation, the electronic equipment generates heat that needs to be removed to ensure the continued performance, reliability, and useful life of the equipment components housed by the equipment racks. One or more embodiments of the systems disclosed herein are designed to remove heat produced by the electronic equipment within the data center and return cool air back to the data center.

[0004] In different applications, there may be the need to produce cold fluid at two different temperature levels. This can happen in several industrial processes, and it is particularly common in domestic refrigeration applications. Referring to FIG. 1, with domestic refrigerators, it is known that there are compartments dedicated to the fresh and frozen products department, for example, each with its own evaporator. As shown, a refrigeration cycle, generally indicated at 10, includes a compressor 12, a condenser 14, a first evaporator 16, and a second evaporator 18. A first capillary tube 20 is provided between the condenser 14 and the first evaporator 16. A second capillary tube 22 is provided between the first evaporator 16 and the second evaporator 18. The two evaporators 16, 18 are placed in series and separated by the capillary tubes 20, 22, which are configured to bring each of the evaporators 16, 18 to a pressure able to provide the cold at the desired respective temperature.

[0005] Referring to FIG. 2, a similar problem arises specifically in supermarkets, where the same refrigeration plant can be provided to produce cold fluid for the compartments containing frozen products and for fresh products, or again in the industry of processes field, when cold at two different temperatures is required. As shown, a refrigeration cycle, generally indicated at 30, includes a compressor 32, a condenser 34, a first evaporator 36, and a second evaporator 38. A liquid receiver 40 is provided between the condenser 34 and the first evaporator 36 and the second evaporator 38. A first expansion valve 42 is provided between the liquid receiver 40 and the first evaporator 36. A second expansion valve 44 is provided between the liquid receiver 40 and the second evaporator 38. The two evaporators 36, 38 are placed in parallel, with the expansion valves 42, 44 being configured to bring each of the evaporators 36, 38 to a pressure able to provide the cold at the desired temperature.

[0006] Referring to FIGS. 3A and 3B, in the case of industry of processes, there are several reason why the requirement to provide cooling at different temperatures arises. One convenient way to be able to produce cold at different temperature levels is to have two (or more) separate units, each one with a different set point. FIG. 3A shows a refrigeration cycle, generally indicated at 50, including a compressor 52, a condenser 54, a first evaporator 56, and a first expansion valve 58 provided between the condenser 54 and the first evaporator 56. The first evaporator 56 and the first expansion valve 58 can be set at a first temperature set point. FIG. 3B shows a refrigeration cycle, generally indicated at 70, including a compressor 72, a condenser 74, a second evaporator 76, and a second expansion valve 78 provided between the condenser 74 and the second evaporator 76. The second evaporator 76 and the second expansion valve 78 can be set at a second temperature set point, thereby enabling refrigeration circuits 50, 70 to produce cooling at different temperatures.

[0007] The schematics of the refrigeration circuits 10, 30, 50, 70 shown in FIGS. 1, 2, 3A and 3B, respectively, are somewhat general in terms of type of compressor (scroll, screw, centrifugal), refrigerant, and type of heat exchangers, both at the condenser and evaporator level. Likewise, the cooling fluid, sometimes referred to as refrigerant, can be water, a mixture of water and glycol, air, and, in industrial processes, process fluids.

[0008] The efficiency of a cooling unit is strongly linked to the compressor suction temperature, which in turn depends on the cold produced at the lower temperature. Aspects of the cooling system of the present disclosure is to overcome this limit, at least in part, by making the evaporators work at their maximum efficiency, thus increasing the evaporation temperature to the maximum possible value.SUMMARY

[0009] One aspect of the present disclosure is directed to a cooling system, comprising a first evaporator configured to output a first coolant at a first temperature and a second evaporator configured to output a second coolant at a second temperature. The first evaporator is configured to be flooded and the second evaporator is configured to be dry. The cooling system further comprises a liquid receiver coupled between the first evaporator and the second evaporator. The liquid receiver is configured to output a liquid through a first outlet and to output a gas through a second outlet.

[0010] Embodiments of the cooling system further may include a compressor in fluid communication with the liquid receiver and the second evaporator. The compressor may be configured to receive gas from the second outlet of the liquid receiver. The cooling system further may include a condenser in fluid communication with the compressor and the first evaporator. The cooling system further may include a first expansion valve in fluid communication with the condenser and the first evaporator. The cooling system further may include a second expansion valve in fluid communication with the first outlet of the liquid receiver and the second evaporator. The cooling system further may include a valve in fluid communication with the second outlet of the liquid receiver and the compressor. The cooling system further may include a controller coupled to the first expansion valve, the second expansion valve and the valve to control the operation of the cooling system. The first evaporator may be in fluid communication with a first electrical component configured to receive the first coolant at the first temperature and the second evaporator may be in fluid communication with a second electrical component configured to receive the second coolant at the second temperature.

[0011] Another aspect of the present disclosure is directed to a method of cooling comprising: outputting a first coolant at a first temperature with a first evaporator, which is configured to be flooded; outputting a second coolant at a second temperature with a second evaporator, which is configured to be dry; and coupling a liquid receiver between the first evaporator and the second evaporator. The liquid receiver is configured to output a liquid through a first outlet and to output a gas through a second outlet.

[0012] Embodiments of the method further may include pumping gas with a compressor in fluid communication with the liquid receiver and the second evaporator. The method further may include compressing gas from the compressor with a condenser in fluid communication with the compressor and the first evaporator. The method further may include expanding liquid with a first expansion valve in fluid communication with the condenser and the first evaporator, and expanding liquid with a second expansion valve in fluid communication with the first outlet of the liquid receiver and the second evaporator. The method further may include controlling flow of gas with a valve in fluid communication with the second outlet of the liquid receiver and the compressor.

[0013] Yet another aspect of the present disclosure is directed to a computer readable medium configured to cause a controller to perform a method of cooling. In one embodiment, the method comprises outputting a first coolant at a first temperature with a first evaporator, which is configured to be flooded, outputting a second coolant at a second temperature with a second evaporator, which is configured to be dry, and coupling a liquid receiver between the first evaporator and the second evaporator. The liquid receiver is configured to output a liquid through a first outlet and to output a gas through a second outlet.

[0014] Embodiments of the method performed by the controller include pumping gas with a compressor in fluid communication with the liquid receiver and the second evaporator. The compressor may be configured to receive gas from the second outlet of the liquid receiver. The method performed by the controller further may include compressing gas from the compressor with a condenser in fluid communication with the compressor and the first evaporator. The method performed by the controller further may include expanding liquid with a first expansion valve in fluid communication with the condenser and the first evaporator. The method performed by the controller further may include expanding liquid with a second expansion valve in fluid communication with the first outlet of the liquid receiver and the second evaporator. The method performed by the controller further may include controlling flow of gas with a valve in fluid communication with the second outlet of the liquid receiver and the compressor. The method performed by the controller further may include controlling the first expansion valve, the second expansion valve and the valve with a controller coupled to the first expansion valve, the second expansion valve and the valve to control the operation of the cooling system. The first evaporator may be in fluid communication with a first electrical component configured to receive the first coolant at the first temperature and the second evaporator may be in fluid communication with a second electrical component configured to receive the second coolant at the second temperature.

[0015] The present invention will be more fully understood after a review of the following figures, detailed description and claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] For a better understanding of the present invention, reference is made to the figures which are incorporated herein by reference and in which:

[0017] FIG. 1 is a schematic representation of a refrigeration circuit of a known cooling system;

[0018] FIG. 2 is a schematic representation of another refrigeration circuit of a known cooling system;

[0019] FIGS. 3A and 3B are schematic representations of two known refrigeration circuits of cooling systems set at different set points;

[0020] FIG. 4 is a schematic representation of a cooling system having a refrigeration circuit of an embodiment of the present disclosure; and

[0021] FIG. 5 is a diagram of a control system including a controller configured to control the operation of the refrigeration circuit.DETAILED DESCRIPTION

[0022] The present disclosure is directed to a cooling system suitable for liquid cooling applications that is capable of supplying cooling fluid at two different temperature levels, one at a higher temperature for liquid cooling and another at a lower temperature for traditional close control air conditioning.

[0023] In one embodiment, the cooling system includes a first flooded evaporator and a second dry evaporator that output fluid at two different temperatures. A liquid receiver is positioned between the first evaporator and the second evaporator, the liquid receiver being configured to output a liquid through a first output to output a gas through a second outlet.

[0024] As noted, with respect to a data center, the need to produce heat at two different temperature levels is desired in circumstances in which the data center uses liquid cooling applications to cool electronic equipment within IT equipment racks. The liquid cooling technique requires that the coolant be at a temperature higher than that required by traditional air conditioning cooling systems, regardless of whether the IT equipment racks are in room or in row type arrangement. Therefore, in a system that converts over time to the liquid cooling technology, it may be desired to produce, initially, a minimum quantity of refrigerant at a higher temperature to liquid cooling applications, delegating a substantial part of the refrigerant at a lower temperature to traditional air conditioners. Subsequently, the percentage of refrigerant produced at a higher temperature will increase, until reaching a final balance, in which the percentage of refrigerant for liquid cooling (produced at a higher temperature) will probably be around 80% of the total. Unfortunately, the efficiency of the refrigeration circuit is strongly linked to the compressor suction temperature, which in turn depends on the cold produced at the lower temperature.

[0025] Aspects of the present disclosure are directed to a cooling system designed to overcome this limit, at least in part, by making the evaporators work at their maximum efficiency, thus increasing the evaporation temperature to the maximum possible value.

[0026] For the purposes of illustration only, and not to limit the generality, the present invention will now be described in detail with reference to the accompanying figures. This invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,”“comprising,”“having,”“containing”“involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

[0027] Referring to FIG. 4, a cooling system including a refrigeration circuit, generally indicated at 100, of an embodiment of the present disclosure is illustrated. In a traditional refrigeration circuit embodying a vapor-compression cycle, the refrigeration circuit includes two heat exchangers, a condenser configured to release heat and an evaporator configured to accept heat. At a start of the cycle, a low pressure refrigerant enters a compressor, which is configured to increase the pressure to cause the refrigerant to leave the compressor as a higher temperature and higher pressure superheated gas. The pressurized gas then passes through the condenser where the gas releases heat to the surroundings as it cools and condenses. The cooler refrigerant passes through an expansion valve, which is configured to reduce the pressure and cause a temperature to drop. The cold low pressure refrigerant is directed to the evaporator, which is configured to vaporize the refrigerant as it receives heat from the surroundings before returning to the compressor as a low temperature fluid or gas.

[0028] As shown, the refrigeration circuit 100 includes a compressor 102 in fluid communication with a condenser 104. The compressor 102 may embody any type of compressor, e.g., a scroll-, a screw-or a centrifugal-type compressor, suitable for pressurizing fluids. In one embodiment, the compressor 102 receives low pressure refrigerant gas and pressurizes the refrigerant gas to increase the temperature and pressure. The superheated pressurized gas then passes through the condenser 104 where the gas releases heat to the surroundings as it cools and condenses. As noted above, the condenser 104 is a heat exchanger that is provided to condense a gas into a liquid through cooling. Heat is released and transferred to the surrounding environment.

[0029] The condenser 104 is in fluid communication with a first evaporator 106 in which the cooler refrigerant first passes through a first expansion valve 108. As noted above, the first expansion valve 108 is configured to reduce the pressure and cause a temperature to drop of the fluid refrigerant received from the condenser 104. The cold low pressure refrigerant is directed to the first evaporator 106, which may be a finned coil, a plate, a shell or a tube, and is configured to operate in a flooded condition since the refrigerant exits the first evaporator 106 to a liquid receiver 110. When the first evaporator 106 operates in a flooded condition, a whole surface of the first evaporator 106 is used to exchange the heat during operation. The first evaporator 106 is configured to output a first liquid, e.g., the liquid refrigerant or coolant, at a first temperature, with the first evaporator 106 being coupled to a cooling system, indicated at 112, requiring cooling fluid at the first temperature. For example, the first evaporator 106 may be configured to cool refrigerant to a higher temperature for use in a liquid cooling system, e.g., cooling system 112, to provide cooling to electronic equipment supported by IT equipment racks. In some embodiments, the first liquid is sometimes referred to as the first coolant.

[0030] In one embodiment, the liquid receiver 110 embodies a storage tank configured to hold liquid and gas refrigerant delivered from the first evaporator. The storage tank of the liquid receiver 110 includes a first outlet 114 provided at a bottom of the storage tank and a second outlet 116 provided at a top of the storage tank. In a typical application, the liquid receiver is placed immediately after the condenser so that the liquid receiver is in direct fluid communication with the condenser. The liquid receiver is provided to ensure that liquid refrigerant enters another expansion valve and to provide a liquid refrigerant backup if a refrigerant level of the condenser drops.

[0031] The liquid receiver 110 is in fluid communication with a second evaporator 118 in which the cooler liquid refrigerant contained in the liquid receiver 110 passes through a second expansion valve 120 prior to being delivered to the second evaporator 118. The liquid receiver 110 further is in fluid communication with the compressor 102 in which the hotter gas refrigerant from the liquid receiver 110 passes through a third valve 122 to control the amount of gas refrigerant delivered to the compressor 102.

[0032] The entire flow of refrigerant within the refrigeration circuit 100 is compressed by the compressor 102, after that condensed by the condenser 104 and then is expanded through the first expansion valve 108, which modulates the flow quantity based on the request of cooling capacity of first evaporator 106. The first evaporator 106 operates in a flooded condition since the refrigerant at an outlet of the first evaporator 106 is connected to the liquid receiver 110. When the first evaporator 106 operates in the flooded condition, the entire surface of the first evaporator 106 is used to exchange the heat. The provision of the liquid receiver 110 located after the outlet of the first evaporator 106 makes it is possible to flood the first evaporator 106 and to take advantage of the first evaporator 106 at a maximum of its efficiency, with the additional benefit of protecting the compressor 102 from liquid refrigerant from entering the compressor 102.

[0033] The second evaporator 118 may be referred to as a dry evaporator. The second expansion valve 120 is configured to reduce the pressure and cause a temperature to drop of the refrigerant. The cold low pressure refrigerant from the liquid receiver 110 is directed to the second evaporator, which also may be a finned coil, a plate, a shell or a tube, and is configured to operate in a dry condition. The second evaporator 118 is configured to output a second liquid, e.g., the liquid refrigerant or coolant, at a second temperature. The second evaporator 118 may be coupled to a cooling system, indicated at 124, requiring cooling at the second temperature, which may be different, e.g., lower, than the first temperature delivered to cooling system 112. For example, the second evaporator 118 also may be configured to cool refrigerant to a lower temperature for use in an air conditioning system, e.g., cooling system 124, configured to provide cooling to electronic equipment, e.g., servers, provided in IT equipment racks. In some embodiments, the second liquid is sometimes referred to as the second coolant. The heated gas refrigerant generated by the second evaporator 118 is directed to the compressor 102 where the heated gas refrigerant is combined with the heated gas refrigerant from the liquid receiver 110. At this point, the refrigeration cycle begins again.

[0034] The arrangement is such that the first evaporator 106 is in fluid communication with a first electrical component, e.g., cooling system 112, configured to receive the first liquid at the first temperature. Similarly, the second evaporator 118 is in fluid communication with a second electrical component, e.g., cooling system 124, configured to receive the second liquid at the second temperature.

[0035] The first and second evaporators 106, 118 each may be configured to facilitate evaporation by conductive and convective heat transfer to transition the refrigerant from a liquid to a gas. The liquid refrigerant is exposed to a reduced pressure environment by the respective expansion valve 108, 120 to facilitate the phase change from liquid to gas at a much lower required temperature. The first and second evaporators 106, 118 can each embody a network of tubes or channels to circulate the refrigerant. Fins are provided to increase the surface areas of the first and second evaporators 106, 118 and thus the heat transfer area. The source of heat used to vaporize the liquid refrigerant is from the cooling system requiring cooling, e.g., the liquid cooling system or the air cooling system described above.

[0036] As noted above, the liquid receiver 110 is configured with two outlets, the first outlet 114 at a bottom of the storage tank of the liquid receiver 110 and a second outlet 116 at a top of the storage tank of the liquid receiver 110. The provision of the liquid receiver 110 positioned between the first evaporator 106 and the second evaporator 118, along with the second expansion valve 120 enables the liquid receiver 110 to constantly feed the second evaporator 118 with liquid refrigerant by the first outlet 114 through the second expansion valve 120 thus enabling the second evaporator 118 to operate at a lower temperature. The second outlet 116, which is positioned at the top of the storage tank of the liquid receiver 110, is fed by saturated gas refrigerant, and allows to keep the level of the liquid refrigerant constant inside the liquid receiver by the third valve 122. The amount of gas refrigerant delivered to the compressor 102 is controlled by the third valve 122. Thus, the liquid receiver 110 is configured to output a liquid refrigerant through the first outlet 114 and to output a gas refrigerant through the second outlet 116.

[0037] The refrigeration circuit 100 of embodiments of the present disclosure proposes a configuration which, while keeping the compressor 102 drawing in the refrigerant at a lowest working pressure, maximizes the efficiency of the first evaporator 106 and the second evaporator 118, thereby the total cycle efficiency. As previously discussed, within the refrigeration circuit 110, the entire flow of refrigerant is compressed by the compressor 102, after that condensed by the condenser 104, and then is expanded through the first expansion valve 108, which modulates the flow quantity based on the request of cooling capacity of the first evaporator 106. The necessity to have a certain superheating of refrigerant is related to the one to protect the compressor 102 from the risk to have liquid droplets entering the compressor 102. By placing the liquid receiver 110 in fluid communication with first evaporator 106, it is possible to flood the first evaporator 106 and to maximize the efficiency of the first evaporator 106. As noted, with this arrangement, the compressor 102 is protected from any liquid entering it.

[0038] Referring to FIG. 5, in one embodiment, the refrigeration circuit includes a control system, e.g., a controller 130, which is configured to control the operation of the first expansion valve 108, the second expansion valve 120 and the third valve 122. The controller 130 can control the operation of the first expansion valve 108 to output the first liquid at the first temperature and control the operation of the second expansion valve 120 to output a second liquid at the second temperature. The controller 130 further can control the operation of the compressor 102, and can be configured be coupled to the condenser 104, the first evaporator 106 and the second evaporator 118 to monitor the operation of these components of the refrigeration circuit 100. It should be understood that the control system can be part of the refrigeration circuit 100 or part of a higher level control system that is configured to control the operation of the cooling system in general.

[0039] As noted above, the controller 130 can control the operation of the first expansion valve 108 to output the first liquid at the first temperature. The first evaporator 106 may be configured to cool refrigerant, e.g., the first liquid, to a lower temperature for use in a traditional air conditioning cooling system, e.g., cooling system 112, to provide cooling to electronic equipment supported by IT equipment racks. Similarly, the controller 130 can control the operation of the second expansion valve 120 to output the second liquid at the second temperature. The second evaporator 118 may be configured to cool refrigerant, e.g., the second liquid, to a higher temperature for use in a liquid cooling system, e.g., cooling system 124, configured to provide cooling to electronic equipment supported by IT equipment racks. The first evaporator 106 is configured to be flooded and the second evaporator 118 configured to be dry.

[0040] Various controllers may execute various operations discussed above, including operations performed by controller 130. Using data stored in associated memory and / or storage, the controller also executes one or more instructions stored on one or more non-transitory computer-readable media, which the controller may include and / or be coupled to, that may result in manipulated data. In some examples, the controller may include one or more processors or other types of controllers. In one example, the controller is or includes at least one processor. In another example, the controller performs at least a portion of the operations discussed above using an application-specific integrated circuit tailored to perform particular operations in addition to, or in lieu of, a general-purpose processor. As illustrated by these examples, examples in accordance with the present disclosure may perform the operations described herein using many specific combinations of hardware and software and the disclosure is not limited to any particular combination of hardware and software components. Examples of the disclosure may include a computer-program product configured to execute methods, processes, and / or operations discussed above. The computer-program product may be, or include, one or more controllers and / or processors configured to execute instructions to perform methods, processes, and / or operations discussed above.

[0041] A method of cooling is further disclosed. In one embodiment, the method includes outputting a first liquid, e.g., liquid refrigerant, at a first temperature with the first evaporator 106, outputting a second liquid, e.g., liquid refrigerant, at a second temperature with the second evaporator 118, and coupling a liquid receiver 110 between the first evaporator 106 and the second evaporator 118. As described, the liquid receiver 110 is configured to output a liquid through a first outlet 114 and to output a gas through a second outlet 116. Thus, the method of cooling is capable of providing cooling to two cooling systems, e.g., cooling system 112 and cooling system 124, requiring differing temperatures.

[0042] The method further includes pumping gas refrigerant with the compressor 102, which is in fluid communication with the liquid receiver 110 and the second evaporator 118. The compressor 102 is configured to receive gas refrigerant from the second outlet 116 of the liquid receiver 110.

[0043] The method further includes compressing gas refrigerant from the compressor 102 with the condenser 104, which is in fluid communication with the compressor 102 and the first evaporator 106, expanding liquid refrigerant with the first expansion valve 108, which is in fluid communication with the condenser 104 and the first evaporator 106, and expanding liquid refrigerant with the second expansion valve 120, which is in fluid communication with the first outlet 114 of the liquid receiver 110 and the second evaporator 118.

[0044] The method further includes controlling the flow of gas refrigerant with the third valve 122, which is in fluid communication with the second outlet 116 of the liquid receiver 110 and the compressor 102. The method further includes controlling the first expansion valve 108, the second expansion valve 120 and the third valve 122 with the controller 130, which is coupled to the first expansion valve 108, the second expansion valve 120, and the third valve 122 to control the operation of the cooling system.

[0045] In some embodiments, depending on the cooling percentage, which can be defined as the quantity of cooling capacity at higher temperature divided by the total cooling capacity, the state of refrigerant leaving the first evaporator changes. The state depends on the liquid level in the liquid receiver.

[0046] In some embodiments, the refrigeration circuit is configured to minimize the superheating of the second evaporator, thereby enabling the second evaporator to operate at almost flooded condition to maximize the efficiency of the second evaporator.

[0047] In some embodiments, the refrigeration circuit enables a compressor working point to remain inside a compressor envelope, which means that the compressor operates under safe working conditions during most operating environments.

[0048] In some embodiments, it is possible to operate the first evaporator in a flooded condition and to operate the second evaporator in an almost flooded conditions.

[0049] In some embodiments, the provision of the liquid receiver protects the compressor from having liquid at a suction point.

[0050] In some embodiments, since the second evaporator is configured to operate under almost flooded conditions, the second evaporator is used close to an optimum efficiency. As a consequence, the temperature difference between the cooled fluid refrigerant and evaporator is reduced, which results in an increase of evaporating temperature.

[0051] In some embodiments, an energy efficiency ration (EER) of the refrigeration circuit is improved approximately 7%.

[0052] A liquid receiver is provided to store heat transfer fluid, e.g., a refrigerant including but not limited to R-134a coolant, used in the cooling system. The liquid receiver includes a tank configured to store at least a portion of coolant depending on fluctuating changes in the pressure of the cooling system and can function to flood the heat exchanger, e.g., an evaporator, using a flooding valve. The flooding valve functions to maintain a steady or minimum liquid pressure and / or temperature of the coolant in the cooling system.

[0053] Having thus described at least one embodiment of the present invention, various alternations, modifications and improvements will readily occur to those skilled in the art. Such alterations, modifications and improvements are intended to be within the scope and spirit of the invention. Accordingly, the foregoing description is by way of example only and is not intended to be limiting. The invention's limit is defined only in the following claims and equivalents thereto.

Claims

1. A cooling system, comprising:a first evaporator configured to output a first coolant at a first temperature, the first evaporator being configured to be flooded;a second evaporator configured to output a second coolant at a second temperature, the second evaporator being configured to be dry; anda liquid receiver coupled between the first evaporator and the second evaporator,wherein the liquid receiver is configured to output a liquid through a first outlet and to output a gas through a second outlet.

2. The cooling system of claim 1, further comprising a compressor in fluid communication with the liquid receiver and the second evaporator.

3. The cooling system of claim 2, wherein the compressor is configured to receive gas from the second outlet of the liquid receiver.

4. The cooling system of claim 2, further comprising a condenser in fluid communication with the compressor and the first evaporator.

5. The cooling system of claim 4, further comprising a first expansion valve in fluid communication with the condenser and the first evaporator.

6. The cooling system of claim 5, further comprising a second expansion valve in fluid communication with the first outlet of the liquid receiver and the second evaporator.

7. The cooling system of claim 6, further comprising a valve in fluid communication with the second outlet of the liquid receiver and the compressor.

8. The cooling system of claim 7, further comprising a controller coupled to the first expansion valve, the second expansion valve and the valve to control the operation of the cooling system.

9. The cooling system of claim 1, wherein the first evaporator is in fluid communication with a first electrical component configured to receive the first coolant at the first temperature and the second evaporator is in fluid communication with a second electrical component configured to receive the second coolant at the second temperature.

10. A method of cooling, comprising:outputting a first coolant at a first temperature with a first evaporator, which is configured to be flooded;outputting a second coolant at a second temperature with a second evaporator, which is configured to be dry; andcoupling a liquid receiver between the first evaporator and the second evaporator,wherein the liquid receiver is configured to output a liquid through a first outlet and to output a gas through a second outlet.

11. The method of claim 10, further comprising pumping gas with a compressor in fluid communication with the liquid receiver and the second evaporator.

12. The method of claim 11, further comprising compressing gas from the compressor with a condenser in fluid communication with the compressor and the first evaporator.

13. The method of claim 12, further comprising expanding liquid with a first expansion valve in fluid communication with the condenser and the first evaporator, and expanding liquid with a second expansion valve in fluid communication with the first outlet of the liquid receiver and the second evaporator.

14. The method of claim 13, further comprising controlling flow of gas with a valve in fluid communication with the second outlet of the liquid receiver and the compressor.

15. A computer readable medium configured to cause a controller to perform a method of cooling, the method comprising:outputting a first coolant at a first temperature with a first evaporator, which is configured to be flooded;outputting a second coolant at a second temperature with a second evaporator, which is configured to be dry; andcoupling a liquid receiver between the first evaporator and the second evaporator,wherein the liquid receiver is configured to output a liquid through a first outlet and to output a gas through a second outlet.

16. The computer readable medium of claim 15, wherein the method of cooling further comprises pumping gas with a compressor in fluid communication with the liquid receiver and the second evaporator.

17. The computer readable medium of claim method of claim 16, wherein the compressor is configured to receive gas from the second outlet of the liquid receiver.

18. The computer readable medium of claim 16, wherein the method of cooling further comprises compressing gas from the compressor with a condenser in fluid communication with the compressor and the first evaporator.

19. The computer readable medium of claim 18, wherein the method of cooling further comprises expanding liquid with a first expansion valve in fluid communication with the condenser and the first evaporator.

20. The computer readable medium of claim 19, wherein the method of cooling further comprises expanding liquid with a second expansion valve in fluid communication with the first outlet of the liquid receiver and the second evaporator.

21. The computer readable medium of claim 20, wherein the method of cooling further comprises controlling flow of gas with a valve in fluid communication with the second outlet of the liquid receiver and the compressor.

22. The computer readable medium of claim 21, wherein the method of cooling further comprises controlling the first expansion valve, the second expansion valve and the valve with a controller coupled to the first expansion valve, the second expansion valve and the valve to control the operation of the cooling system.

23. The computer readable medium of claim 15, wherein the first evaporator is in fluid communication with a first electrical component configured to receive the first coolant at the first temperature and the second evaporator is in fluid communication with a second electrical component configured to receive the second coolant at the second temperature.

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