EP4689512A1

EP4689512A1 - Energy efficient free-cooling system and fluid for hvac&r system

Info

Publication number: EP4689512A1
Application number: EP24782039.2A
Authority: EP
Inventors: William Leslie Kopko; Satheesh Kulankara
Original assignee: Tyco Fire and Security GmbH
Current assignee: Tyco Fire and Security GmbH
Priority date: 2023-03-31
Filing date: 2024-03-29
Publication date: 2026-02-11
Also published as: CN121127717A; WO2024206838A1; TW202441111A

Abstract

An energy efficient heating, ventilating, air conditioning, and refrigeration (HVAC&R) system (100) includes a conditioning fluid circuit (102) configured to direct a conditioning fluid to a load (106) to condition the load, a mechanical cooling system (30) configured to direct a working fluid therethrough, where the mechanical cooling system (30) is configured to place the working fluid in a first heat exchange relationship with ambient air and to place the working fluid in a second heat exchange relationship with the conditioning fluid, and a free-cooling system (104) configured to direct a chilled fluid therethrough. The chilled fluid includes potassium formate or aqua ammonia, and the free-cooling system (104) is configured to place the chilled fluid in a third heat exchange relationship with the conditioning fluid.

Description

ENERGY EFFICIENT FREE-COOLING SYSTEM AND FLUID FOR HVAC&R SYSTEM

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from and the benefit of U.S. Provisional Patent Application No. 63/456,206, entitled ‘ FREE COOLING SYSTEM AND FLUID FOR HV AC&R SYSTEM,” filed March 31, 2023, which is hereby incorporated by reference in its entirety for all purposes

BACKGROUND

[0002] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0003] Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems, such as chiller systems (e.g., vapor compression systems), utilize a working fluid (e.g., a refrigerant) that changes phases between vapor, liquid, and combinations thereof in response to exposure to different temperatures and pressures within components of the chiller system. The HVAC&R system may place the working fluid in a heat exchange relationship with a conditioning fluid (e. g. , water) and may deliver the conditioning fluid to conditioning equipment and/or a conditioned environment serviced by the HVAC&R system. For example, the HVAC&R system may include a heat exchanger configured to receive the working fluid and the conditioning fluid to place the working fluid in the heat exchange relationship with the conditioning fluid. The conditioning fluid may be directed from the heat exchanger to other equipment, such as air handlers, to condition other fluids, such as air, in a building. The working fluid may be directed from the heat exchanger through other components of the HVAC&R system, such as a compressor and/or a condenser, configured to process (e.g., pressurize, cool) the working fluid to enable the working fluid to provide further conditioning of the conditioning fluid.

[0004] In some applications, HVAC&R systems may include a free-cooling system that circulates a chilled fluid to provide additional or alternative conditioning of the conditioning fluid. Unfortunately, traditional chilled fluids utilized in existing free-cooling systems, such as propylene glycol and ethyl glycol are susceptible to inefficiencies, such as offer poor thermal performance and/or greater energy demands to operate pumps and/or compressors that circulate the traditional chilled fluids through the free-cooling system. It is now recognized that such inefficiencies can result in unnecessary energy consumption and associated emissions.

SUMMARY

[0005] A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety' of aspects that may not be set forth below.

[0006] In one embodiment, an energy^ efficient heating, ventilating, air conditioning, and refrigeration (HVAC&R) system includes a conditioning fluid circuit configured to direct a conditioning fluid to a load to condition the load, a mechanical cooling system configured to direct a working fluid therethrough, where the mechanical cooling system is configured to place the working fluid in a first heat exchange relationship with ambient air and to place the working fluid in a second heat exchange relationship with the conditioning fluid, and a free-cooling system configured to direct a chilled fluid therethrough. The chilled fluid includes potassium formate or aqua ammonia, and the free-cooling system is configured to place the chilled fluid in a third heat exchange relationship with the conditioning fluid.

[0007] In another embodiment, an energy efficient heating, ventilating, air conditioning, and refrigeration (HVAC&R) system includes an air-cooled vapor compression system configured to circulate a working fluid therethrough and configured to place the working fluid in a heat exchange relationship with a conditioning fluid of a conditioning fluid circuit. The energy efficient HVAC&R system also includes and a free-cooling system configured to direct a chilled fluid therethrough, where the chilled fluid includes potassium formate or aqua ammonia. The free-cooling system includes a first heat exchanger configured to place the chilled fluid in a heat exchange relationship with ambient air and a second heat exchanger configured to receive the chilled fluid from the first heat exchanger and to place the chilled fluid in a heat exchange relationship with the conditioning fluid of the conditioning fluid circuit. [0008] In a further embodiment, an energy efficient heating, ventilating, air conditioning, and refrigeration (HVAC&R) system including a vapor compression circuit configured to circulate a working fluid therethrough, where the vapor compression circuit includes an evaporator configured to be disposed along a conditioning fluid circuit and a condenser configured to place the working fluid in a heat exchange relationship with ambient air. The energy efficient HVAC&R system also includes a free-cooling circuit configured to direct a chilled fluid therethrough, where the chilled fluid is an aqueous solution comprising potassium formate, aqua ammonia, or a low-pressure refrigerant. The free-cooling system includes a first heat exchanger configured to place the chilled fluid in a heat exchange relationship with ambient air and a second heat exchanger configured to receive the chilled fluid from the first heat exchanger and to place the chilled fluid in a heat exchange relationship with a conditioning fluid of the conditioning fluid circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:

[0010] FIG. 1 is a perspective view of a building that may utilize an embodiment of a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system in a commercial setting, in accordance with an aspect of the present disclosure;

[0011] FIG. 2 is a schematic of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure; and

[0012] FIG. 3 is a schematic of an embodiment of an HVAC&R system having a vapor compression system and a free cooling system, in accordance with an aspect of the present disclosure.

DETAILED DESCRIPTION

[0013] One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementationspecific decisions must be made to achieve the developers’ specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0014] When introducing elements of various embodiments of the present disclosure, the articles “a,'’ “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including.” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be noted that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0015] As used herein, the terms “approximately,” “generally,” “substantially,” and so forth, are intended to convey that the property value being described may be within a relatively small range of the property value, as those of ordinary skill would understand. For example, when a property value is described as being “approximately” equal to (or, for example, “substantially similar” to) a given value, this is intended to convey that the property value may be within +/- 5%, within +/- 4%, within +/- 3%, within +/- 2%, within +/- 1%, or even closer, of the given value. Similarly, when a given feature is described as being “substantially parallel” to another feature, “generally perpendicular” to another feature, and so forth, this is intended to convey that the given feature is within +/- 5%, within +/- 4%, within +/- 3%, within +/- 2%, within +/- 1%, or even closer, to having the described nature, such as being parallel to another feature, being perpendicular to another feature, and so forth. Mathematical terms, such as “parallel” and “perpendicular,” should not be rigidly interpreted in a strict mathematical sense, but should instead be interpreted as one of ordinary skill in the art would interpret such terms. For example, one of ordinary skill in the art would understand that two lines that are substantially parallel to each other are parallel to a substantial degree, but may have minor deviation from exactly parallel.

[0016] Embodiments of the present disclosure relate to a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, such as a chiller system (e.g., an air-cooled chiller system). For example, the HVAC&R system may receive a conditioning fluid from a structure (e.g., a building) and may cool the conditioning fluid. The HVAC&R system may then return the cooled conditioning fluid to the structure to enable conditioning (e.g., cooling) of the structure. In certain embodiments, the HVAC&R system may include a vapor compression system (e.g., vapor compression circuit, mechanical cooling system, working fluid circuit) configured to cool a working fluid (e.g.. a first working fluid, a refrigerant) and to place the cooled working fluid in a heat exchange relationship with the conditioning fluid to absorb heat or thermal energy from the conditioning fluid. Thus, the vapor compression system may cool the conditioning fluid.

[0017] The HVAC system may additionally or alternatively include a free-cooling system (e.g., free-cooling circuit, chilled fluid circuit) configured to cool a chilled fluid (e.g., a second working fluid) and to place the cooled chilled fluid in a heat exchange relationship with the conditioning fluid to absorb heat from the conditioning fluid. For instance, the free-cooling system may cool the chilled fluid by transferring heat from the chilled fluid to ambient air. In this way. the cooling capacity of the free-cooling system may be dependent on a temperature of the ambient air. In certain conditions, the free-cooling system may be operated instead of or in addition to the vapor compression system, which may enable more efficient operation of the HVAC&R system. Specifically, operation of the free-cooling system may enable reduced energy consumption of the HVAC&R system and thereby reduce corresponding greenhouse gas emissions (e.g., via limited or suspended operation of a compressor of the vapor compression system).

[0018] The cooling capacity of the HVAC&R system may be dependent upon heat transfer properties of the chilled fluid (e.g., working fluid) circulated through the free-cooling system. As an example, chilled fluid with a specific heat above a threshold value may not enable efficient heat exchange between the chilled fluid of the free-cooling system and the conditioning fluid. In other words, a relatively high specific heat may cause the HVAC&R system to provide relatively low cooling of the chilled fluid. Thus, operation of the free-cooling system to cool the chilled fluid may be inefficient with chilled fluids having relatively high specific heats. As another example, chilled fluid with a freezing temperature above a threshold temperature may be susceptible to freezing at low ambient conditions, such as when ambient air is below a threshold temperature. Freezing of the chilled fluid may reduce the capability of the chilled fluid to transfer heat with the conditioning fluid and may further reduce efficiency of the HVAC&R system. Additionally or alternatively, freezing of the chilled fluid may affect a structural integrity of certain components of the HVAC&R system, such as components (e.g., piping, a heat exchanger) through which the chilled fluid may be directed during operation of the free-cooling system.

[0019] Thus, it is presently recognized that usage of improved chilled fluids, such as chilled fluids having compositions with desirable thermal properties (e.g., specific heat, freezing temperature, thermal conductivity) may increase efficiency of the free-cooling system and the HVAC&R sy stem generally. Additionally, improved chilled fluids described herein may have lower viscosities than traditional chilled fluids, which may enable pumping of the chilled fluid through the free-cooling system with reduced energy consumption and thereby reduced generation of greenhouse gas emissions. Accordingly, embodiments of the present disclosure are directed to an HVAC&R system having a free-cooling system that utilizes a chilled fluid (e.g., a second working fluid) with a heat transfer property that is within a threshold range of values and/or a freezing temperature that is within a threshold range of values. As an example, the chilled fluid may have a specific heat that is below a corresponding threshold value, a thermal conductivity that is above a corresponding threshold value, a viscosity⁷ that below a corresponding threshold value, and/or a freezing temperature that is above a corresponding threshold value. For instance, the chilled fluid may be or include potassium formate and/or aqua ammonia. Such composition of the chilled fluid may enable the free-cooling system and the HVAC&R system to operate more efficiently to condition the conditioning fluid and/or may improve a useful lifespan of components of the HVAC&R system. Indeed, HVAC&R systems having free-cooling systems configured to circulate chilled fluids described herein may enable operation of the free-cooling system, and the HVAC&R system generally, with reduced energy consumption by a compressor of the HVAC&R system and/or a pump of the free- cooling system. In this way, the present techniques enable a reduction in corresponding greenhouse gas emissions.

[0020] Turning now to the drawings, FIG. 1 is a perspective view of an embodiment of an application for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system. Such systems, in general, may be applied in a range of settings, both within the HVAC&R field and outside of that field. The HVAC&R systems may provide cooling to data centers, electrical devices, freezers, coolers, or other environments through vapor-compression refrigeration, absorption refrigeration, or thermoelectric cooling. In presently contemplated applications, however, HVAC&R systems may be used in residential, commercial, light industrial, industrial, and in any other application for heating or cooling a volume or enclosure, such as a residence, building, structure, and so forth. Moreover, the HVAC&R systems may be used in industrial applications, where appropriate, for cooling and heating of various fluids.

[0021] The illustrated embodiment shows an HVAC&R system for building environmental management that may utilize heat exchangers. A building 10 is cooled by a system that includes a chiller 12 (e.g., a chiller system, air-cooled chiller) and a boiler 14. As shown, the chiller 12 is disposed on the roof of building 10, and the boiler 14 is located in the basement; however, the chiller 12 and boiler 14 may be located in other equipment rooms or areas next to the building 10. In accordance with the present techniques, the chiller 12 is an air-cooled chiller that implements a refrigeration cycle to cool water or other conditioning fluid and is configured to reject heat to an ambient (e.g., outdoor) environment surrounding the chiller 12 and/or the building 10. The chiller 12 is housed within a structure that includes a working fluid circuit, a conditioning fluid circuit, and associated equipment such as pumps, valves, and piping. For example, the chiller 12 may be single package rooftop unit that incorporates a working fluid circuit. As described below, the chiller 12 may also include a free-cooling circuit. The boiler 14 is a closed vessel in which water or other conditioning fluid is heated. The water (e.g., conditioning fluid) from the chiller 12 and the boiler 14 is circulated through the building 10 by conduits 16 (e.g., water conduits). The conduits 16 are routed to air handlers 18 located on individual floors and within sections of the building 10.

[0022] The air handlers 18 are coupled to ductwork 20 that is adapted to distribute air between the air handlers 18 and may receive air from an outside intake. The air handlers 18 include heat exchangers that circulate cold conditioning fluid (e.g., water) from the chiller 12 and hot conditioning fluid (e.g., water) from the boiler 14 to provide heated or cooled air to conditioned spaces within the building 10. Fans within the air handlers 18 draw air through the heat exchangers and direct the conditioned air to environments within building 10, such as rooms, apartments, or offices, to maintain the environments at a designated temperature. A control device, shown in the illustrated embodiment as including a thermostat 22, may be used to designate the temperature of the conditioned air. The control device 22 also may be used to control the flow of air through and from the air handlers 18. Other devices may be included in the system, such as control valves that regulate the flow of conditioning fluid and pressure and/or temperature transducers or switches that sense the temperatures and pressures of the conditioning fluid, the air, and so forth. Moreover, control devices may include computer systems that are integrated with or separate from other building control or monitoring systems, and even systems that are remote from the building 10.

[0023] In some embodiments, the chiller 12 may include a free-cooling system configured to circulate a chilled fluid and place the chilled fluid in a heat exchange relationship with the conditioning fluid circulated through the building to condition (e.g., cool) the conditioning fluid (e.g., water). The free-cooling circuit configured to circulate the chilled fluid through the chiller 12 may remain outside of the building 10. In other words, the chilled fluid may not enter and/or be circulated through the building 10 (e.g., piping of the building 10). As a result, the chilled fluid may not be subject to certain regulations or codes that may otherwise establish standards, specifications, or requirements to be satisfied to enable implementation of the chiller 12. As such, the chiller 12 may be more readily and/or easily implemented to condition the building 10.

[0024] FIG. 2 is a schematic of an embodiment of a vapor compression system 30 (e.g., mechanical cooling system, air-cooled vapor compression system) having a flash tank 32 (e.g., an economizer tank). For example, the vapor compression system 30 may be a part of an aircooled chiller (e g., chiller 12). However, it should be appreciated that the disclosed techniques may be incorporated with a variety of other types of chillers. The vapor compression system 30 includes a working fluid circuit 34 (e.g., vapor compression circuit, first working fluid circuit) configured to circulate a working fluid, such as a refrigerant, therethrough with a compressor 36 (e.g., a screw compressor) disposed along the working fluid circuit 34. The working fluid circuit 34 also includes the flash tank 32, a condenser 38 (e.g., first condenser, heat exchanger, air-cooled condenser), expansion valves or devices 40, and an evaporator 42 (e.g., liquid chiller, heat exchanger). The components of the working fluid circuit 34 enable heat transfer between the working fluid and other fluids (e.g., a conditioning fluid, air. water) in order to provide cooling to an environment, such as an interior of the building 10.

[0025] Some examples of working fluids that may be used as refrigerants in the vapor compression system 30 are hydrofluorocarbon (HFC) based working fluids, for example. R- 410A, R-407, R-134a, hydrofluoro-olefin (HFO), “natural” refrigerants like ammonia (NH3), R-717, carbon dioxide (CO2), R-744, or hydrocarbon based working fluids, water vapor, working fluids with low global warming potential (GWP), or any other suitable working fluid. In some embodiments, the vapor compression system 30 may be configured to efficiently utilize working fluids having a normal boiling point of about 19 degrees Celsius (66 degrees Fahrenheit or less) at one atmosphere of pressure, also referred to as low pressure working fluids, versus a medium pressure working fluids, such as R-134a. As used herein, “normal boiling point'’ may refer to a boiling point temperature measured at one atmosphere of pressure.

[0026] The vapor compression system 30 may further include a control panel 44 (e.g., a controller) that has an analog to digital (A/D) converter 46, a microprocessor 48, a non-volatile memory 50, and/or an interface board 52. In some embodiments, the vapor compression system 30 may use one or more of a variable speed drive (VSDs) 54 and a motor 56. The motor 56 may drive the compressor 36 and may be powered by the VSD 54. The VSD 54 receives alternating current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source, and provides power having a variable voltage and frequency to the motor 56. In other embodiments, the motor 56 may be powered directly from an AC or direct current (DC) power source. The motor 56 may include any type of electric motor that can be powered by the VSD 54 or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.

[0027] The compressor 36 compresses a working fluid vapor and may deliver the vapor to an oil separator 58 that separates oil from the working fluid vapor. The working fluid vapor is then directed toward the condenser 38. and the oil is returned to the compressor 36. The working fluid vapor delivered to the condenser 38 may transfer heat to a cooling fluid at the condenser 38. For example, the cooling fluid may be ambient air 60 forced across heat exchanger coils of the condenser 38 by condenser fans 62. The working fluid vapor may condense to a working fluid liquid in the condenser 38 as a result of thermal heat transfer with the cooling fluid (e.g., the ambient air 60).

[0028] The liquid working fluid exits the condenser 38 and then flows through a first expansion device 64 (e.g., the expansion device 40, an electronic expansion valve). The first expansion device 64 may be a flash tank feed valve configured to control flow of the liquid working fluid to the flash tank 32. The first expansion device 64 is also configured to lower the pressure of (e.g., expand) the liquid working fluid received from the condenser 38. During the expansion process, a portion of the liquid may vaporize, and thus, the flash tank 32 may be used to separate the vapor from the liquid received from the first expansion device 64. Additionally, the flash tank 32 may provide for further expansion of the liquid working fluid due to a pressure drop experienced by the liquid working fluid when entering the flash tank 32 (e.g., due to a rapid increase in volume experienced when entering the flash tank 32).

[0029] The vapor in the flash tank 32 may exit and flow to the compressor 36. For example, the vapor may be drawn to an intermediate stage or discharge stage of the compressor 36 (e.g., not the suction stage). A valve 66 (e.g., an economizer valve, solenoid valve) may be included in the working fluid circuit 34 to control flow' of the working fluid vapor from the flash tank 32 to the compressor 36. In some embodiments, when the valve 66 is open (e.g., fully open), additional liquid working fluid within the flash tank 32 may vaporize and provide additional subcooling of the liquid w orking fluid within the flash tank 32. The liquid working fluid that collects in the flash tank 32 may be at a lower enthalpy than the liquid working fluid exiting the condenser 38 due to the expansion in the first expansion device 64 and/or the flash tank 32. The liquid working fluid may flow from the flash tank 32, through a second expansion device 68 (e.g., the expansion device 40, an orifice), and to the evaporator 42. In some embodiments, the working fluid circuit 34 may also include a valve 70 (e.g., a drain valve) configured to regulate flow of liquid working fluid from the flash tank 32 to the evaporator 42. For example, the valve 70 may be controlled (e.g., via the control panel 44) based on an amount of suction superheat of the working fluid.

[0030] The liquid working fluid delivered to the evaporator 42 may absorb heat from a conditioning fluid, which may be different from the cooling fluid (e.g., ambient air 60) directed across the condenser 38. The liquid working fluid in the evaporator 42 may undergo a phase change to become w orking fluid vapor. For example, the evaporator 42 may include a tube bundle fluidly coupled to a supply line 72 and a return line 74 that are connected to a cooling load. The conditioning fluid (e.g., water, oil. calcium chloride brine, sodium chloride brine) may be directed to enter the evaporator 42 via the return line 74 and to exit the evaporator 42 the via supply line 72. The evaporator 42 may reduce the temperature of the conditioning fluid in the tube bundle via thermal heat transfer w ith the working fluid so that the conditioning fluid may be utilized to provide cooling for a conditioned environment. The tube bundle in the evaporator 42 may include a plurality of tubes and/or a plurality of tube bundles. In any case, the working fluid vapor exits the evaporator 42 and returns to the compressor 36 by a suction line to complete the working fluid cycle.

[0031] In some circumstances, it may be desirable to cool the conditioning fluid via free cooling. As used herein, free cooling refers to cooling (e.g., cooling the conditioning fluid) without operation of components of a mechanical cooling system (e.g., the vapor compression system 30) and/or with reduced operation of components of the mechanical cooling system. In other words, an HVAC&R system, such as the chiller 12 (e.g., air-cooled chiller), may include a free-cooling system in addition to a mechanical cooling system. In some embodiments, the free-cooling system may utilize a temperature of ambient air (e.g., the ambient air 60) to cool the conditioning fluid. More specifically, a chilled fluid (e.g., a second working fluid) circulated through the free-cooling system may be cooled by the ambient air, and the chilled fluid may be placed in a heat exchange relationship with the conditioning fluid to cool the conditioning fluid. Indeed, it should be appreciated that the free-cooling system may operate to cool the conducting fluid without operation of the compressor 36 (e.g., the vapor compression system 30).

[0032] In certain implementations, the free cooling system (e.g., a system that is separate from the vapor compression system 30) may be operated instead of the vapor compression system (e.g., the vapor compression system 30) to enable reduced energy⁷ consumption. For instance, by operating the free-cooling system, components of the vapor compression system 30, such as the compressor 36. may not be in operation. In this way, energy consumed by the HVAC&R system may be reduced, thereby enabling a reduction in the generation of greenhouse gas emissions. Additionally, suspended operation of the vapor compression system 30 (e.g., the compressor 36) may also reduce costs associated with operating the HVAC&R system. Additionally or alternatively, the free-cooling system may be operated in conjunction with the vapor compression system 30 to provide additional cooling to the conditioning fluid. In such embodiments, the free-cooling system and the vapor compression system 30 may be independently operable based on the desired amount of cooling of the conditioning fluid, based on ambient conditions (e g., a temperature of the ambient air 60), and/or based on other suitable parameters.

[0033] The present disclosure is directed to a free-cooling system that utilizes ambient air to cool a chilled fluid (e.g.. working fluid) circulated through the free-cooling system. In accordance with present techniques, the free-cooling system may circulate a chilled fluid with improved properties (e.g., thermal properties, fluid properties) that enable more efficient operation of an HVAC&R system. For example, the chilled fluid may have a specific heat, a thermal conductivity, a viscosity, and/or another suitable property (e.g., heat transfer property ) that is within a respective threshold range of values to enable the chilled fluid to more efficiently exchange heat with a conditioning fluid. Thus, a desirable efficiency or amount of heat exchange between the chilled fluid and the conditioning fluid may be achieved, and as a result, energy consumption of the HVAC&R system may be reduced. As another example, the freezing temperature of the chilled fluid may be within a threshold range of values. As such, freezing of the chilled fluid may be avoided at different temperatures of the ambient air 60 used to cool the chilled fluid. Therefore, desirable operation of the free-cooling system may be maintained at different conditions (e.g., different ambient air temperatures).

[0034] With the foregoing in mind, FIG. 3 is a schematic of an embodiment of an HVAC&R system 100 (e.g., air-cooled chiller system, energy efficient air-cooled chiller) having the vapor compression system 30 (e.g., mechanical cooling system), a conditioning fluid circuit 102, and a free-cooling system 104 (e.g., a free-cooling circuit, energy-efficient free-cooling system). The vapor compression system 30 may be an embodiment of the vapor compression system 30 described above with reference to FIG. 2. More specifically, the vaporcompression system 30 may be an air-cooled chiller having the condenser 38. A conditioning fluid, such as water and/or glycol (e.g., propylene glycol), may be directed through the conditioning fluid circuit 102 to be cooled by the vapor compression system 30 and/or the free- cooling system 104. For example, the conditioning fluid circuit 102 is fluidly coupled to a load 106, such as electronic equipment (e.g., a data center), a conditioned space (e.g., a residential space, an office space), and/or air handling equipment, which may be located within a structure (e.g., building 10) serviced by the HVAC&R system 100. The HVAC&R system 100 may receive conditioning fluid from the load 106, cool the conditioning fluid via the vapor compression system 30 and/or the free-cooling system 104, and return the cooled conditioning fluid to the load 106 to provide cooling for the load 106.

[0035] The conditioning fluid circuit 102 may include a conditioning fluid pump 108 positioned along a return line 110 (e.g., the return line 74) of the conditioning fluid circuit 102. The conditioning fluid pump 108 may force or draw the conditioning fluid from the load 106 into the conditioning fluid circuit 102 via the return line 110. The conditioning fluid pump 108 may direct the conditioning fluid to a heat exchanger 112 (e.g., free-cooling heat exchanger), which is configured to place the conditioning fluid in a heat exchange relationship with a chilled fluid 114 (e.g., a cooling fluid, a working fluid, a free-cooling fluid) flowing through the free-cooling system 104. The heat exchanger 112 may therefore be a component of the free-cooling system 104. For instance, the heat exchanger 1 12 may enable heat transfer from the conditioning fluid to the chilled fluid 114, thereby cooling the conditioning fluid.

[0036] The cooled conditioning fluid may then be directed from the heat exchanger 112 to the evaporator 42 of the vapor compression system 30, which may place the conditioning fluid in a heat exchange relationship with cool working fluid (e.g., refrigerant) to further cool the conditioning fluid. As such, implementation and operation of both the free-cooling system 104 and the vapor compression system 30 may increase the cooling capacity provided by the HVAC&R system 100 to cool the conditioning fluid.

[0037] However, it should be noted that in some cases, operation of one of the free-cooling system 104 or the vapor compression system 30 may be suspended in certain circumstances. For example, operation of one of the free-cooling system 104 or the vapor compression system 30 may be suspended based on a desirable amount of cooling (e.g., a demand of the load 106) to be provided by the HVAC&R system 100 (e.g., to cool the conditioning fluid). In some instances, operation of the vapor compression system 30 may be suspended and the free- cooling system 104 may be operated to cool the conditioning fluid based on an ambient temperature being below athreshold value. As a result, the HVAC&R system 100 may operate with reduced energy consumption and improved efficiency (e.g., via non-operation of a compressor of the vapor compression system 30).

[0038] The conditioning fluid may be directed from the evaporator 42 to the load 106 via a supply line 116 (e.g., the supply line 72) of the conditioning fluid circuit 102 to provide cooling for the load 106. In additional or alternative embodiments, the HVAC&R system 100 may provide different conditioning for the conditioning fluid. For example, the HVAC&R system 100 (e.g., the vapor compression system 30) may be configured to operate as a heat pump to heat the conditioning fluid in a heating mode of the vapor compression system 30. In such embodiments, the conditioning fluid may provide heating for the load 106.

[0039] The free-cooling system 104 may include a conduit system 117 (e.g., piping, tubing, valves, free-cooling circuit) and a chilled fluid pump 118 configured to direct the chilled fluid 114 through the conduit system 117 to circulate the chilled fluid 114 through the free-cooling system 104. As an example, the chilled fluid pump 118 may pressurize the chilled fluid 114 that is in a vapor state 120 (e.g.. a partially vapor state, a two-phase state) and direct the pressurized chilled fluid 114 to a condenser 122 (e g., cooling coil, air-cooled heat exchanger, heat exchanger) of the free-cooling system 104 via the conduit system 1 17. Additionally or alternatively, the chilled fluid pump 118 may direct chilled fluid 114 to the condenser 122 without pressurizing the chilled fluid 114.

[0040] The HVAC&R system 100 may provide cooling (e.g., free cooling) of the conditioning fluid via operation of the free-cooling system 104 and without operating the vapor compression system 30. The condenser 122 may cool the chilled fluid 114 by transferring heat from the chilled fluid 114 to ambient air (e.g., ambient air 60). For instance, the condenser 122 may be a fluid-air heat exchanger (e.g., a liquid to air heat exchanger) configured to place the chilled fluid 114 directed through the free-cooling system 104 in a heat exchange relationship with ambient air. As an example, a fan 124 may direct ambient air across the condenser 122 to enable the condenser 122 to cool the chilled fluid 114, such as via convection. In some embodiments, cooling of the chilled fluid 114 within the condenser 122 may cause the chilled fluid 114 to condense from the vapor state 120 into a liquid state 126.

[0041] The condenser 122 may direct the cooled chilled fluid 114 to the heat exchanger 112 via the conduit system 117. In the heat exchanger 112, the cooled chilled fluid f 14 may absorb heat or thermal energy from the conditioning fluid to cool the conditioning fluid and to heat the chilled fluid 114. For example, heat exchange between the chilled fluid 114 and the conditioning fluid may cause the chilled fluid 114 to at least partially vaporize into the vapor state 120. The heat exchanger 112 may direct the chilled fluid 114 (e.g.. the chilled fluid 114 in the at least partially vapor state 120) toward the chilled fluid pump 118 to complete the flow path of the chilled fluid 114 through the free-cooling system 104.

[0042] The HVAC&R system 100 may also include a control system 128 (e.g.. the control panel 44, an automation controller, a programmable controller, an electronic controller, a cloud computing system, control circuitry) configured to control operation of various components of the HVAC&R system 100. The control system 128 may include a memory 130 (e.g., nonvolatile memory 50) and processing circuitry 132 (e.g., microprocessor 48). The memory 130 may include volatile memory, such as random-access memory (RAM), and/or non-volatile memory, such as read-only memory (ROM), optical drives, hard disc drives, solid-state drives, or any other non-transitory computer-readable medium that includes instructions (e.g., processor input instructions) to operate the HVAC&R sy stem 100. The processing circuitry 132 may be configured to execute such instructions. For example, the processing circuitry 132 may include one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more general purpose processors, or any combination thereof.

[0043] As an example, the control system 128 may be communicatively coupled to the chilled fluid pump 118 and/or to the fan 124 of the free-cooling system 104. The control system 128 may control pressurization and/or a flow rate (e.g., a volumetric flow rate) of the chilled fluid 114 via operation of the chilled fluid pump 118 and/or may control cooling of the chilled fluid via operation of the fan 124. Thus, the control system 128 may control a property and/or operating parameter (e.g., temperature) of the chilled fluid 114 to enable the chilled fluid 114 to provide desirable conditioning capabilities for the conditioning fluid. For instance, the control system 128 may operate the chilled fluid pump 118 and/or the fan 124 to enable the chilled fluid 114 to cool the conditioning fluid to a target temperature via heat transfer within the heat exchanger 1 12. Indeed, the control system 128 may adjust an operating level, state, and/or mode of the chilled fluid pump 118 and/or of the fan 124. To this end, the chilled fluid pump 118 may be a variable speed pump, a variable displacement pump, or another suitable pump configured to operate in different modes or settings, and/or the chilled fluid pump 118 may be a variable speed compressor, a variable capacity compressor, a multi-stage compressor, or any other suitable compressor configured to operate in different modes or settings. The control system 128 may adjust operation of the chilled fluid pump 118 to adjust a parameter (e.g., a flow rate, a pressure, a temperature) of the chilled fluid 114 directed to the condenser 122. Additionally or alternatively, the fan 124 may be a variable speed fan and/or one fan of a fan array associated with the condenser 122, and the control system 128 may adjust a speed of the fan 124 (e.g., suspend operation of the fan 124) to adjust cooling of the chilled fluid 114 via the condenser 122. In some embodiments, the control system 128 may operate the chilled fluid pump 118 and/or the fan f24 based on a temperature of ambient air. The temperature of ambient air may affect cooling of the chilled fluid 114 via the condenser 122. and the temperature of ambient air may therefore affect a cooling capability or capacity of the chilled fluid 114 flowing through the heat exchanger 112.

[0044] The control system 128 may also be communicatively coupled to the vapor compression system 30. For instance, the control system 128 may be configured to control the operation of the vapor compression system 30 (e.g., via controlling operation of the compressor 36) to determine, select, establish, or set the cooling capacity of the working fluid circulated through the vapor compression system 30 to cool the conditioning fluid via the evaporator 42. Further, the control system 128 may independently operate the vapor compression system 30 and the free-cooling system 104. In an example, the control system 128 may operate the free- cooling system 104 and suspend operation of the vapor compression system 30, such as in response to a determination (e.g., based on data and/or feedback received by the control system 128) that the temperature of the chilled fluid 114 is lower than the temperature of the conditioning fluid (e.g., during conditions in which the temperature of ambient air is sufficiently low), and the free-cooling system 104 may therefore adequately cool the conditioning fluid to satisfy the demand of the load 106. As a result, the free-cooling system 104 alone may cool the conditioning fluid. As will be appreciated, suspended operation of the vapor compression system 30 and operation of the free-cooling system 104 alone may result in operation ofthe HVAC&R 100 to satisfy' a cooling demand of the load 106 while also reducing energy consumption of the HVAC&R system 100. In this way, the present techniques enable a reduction in the generation of greenhouse gas emissions.

[0045] In another example, the control system 128 may operate the vapor compression system 30 and suspend operation of the free-cooling system 104, such as when the temperature of the chilled fluid is higher than the temperature of the conditioning fluid (e.g., when the temperature of ambient air is high), and the free-cooling system 104 may therefore not be able to adequately cool the conditioning fluid (e.g., to satisfy a cooling demand of the load 106). In a further example, the control system 128 may operate both the free-cooling system 104 and the vapor compression system 30, and the conditioning fluid may be cooled by both the chilled fluid 114 of the free-cooling system 104 and the working fluid (e.g., refrigerant) of the vapor compression system 30. As such, the cooling of the conditioning fluid may be increased as compared to operation of either the free-cooling system 104 or the vapor compression system 30 alone. The control system 128 may also regulate the respective operating parameters of the vapor compression system 30 and the free-cooling system 104. For example, the control system 128 may operate the chilled fluid pump 1 18 of the free-cooling system 104 independently of the compressor 36 of the vapor compression system 30. In this way, the control system 128 may adjust the respective cooling capacities of the vapor compression system 30 and the free-cooling system 104, such as based on a change in operating conditions (e.g., cooling demand of the load 106, temperature of ambient air, etc.).

[0046] In additional or alternative embodiments, the control system 128 may be communicatively coupled to the conditioning fluid pump 108. For example, the control system 128 may operate the conditioning fluid pump 108 to direct conditioning fluid through the conditioning fluid circuit 102, such as based on a determination by the control system 128 that the conditioning fluid should be conditioned (e.g., to satisfy a demand of the load 106). The control system 128 may also suspend operation of the conditioning fluid pump 108, such as when cooling of the conditioning fluid is not desirable and, therefore, the conditioning fluid is not directed through the conditioning fluid circuit 102. In certain embodiments, the conditioning fluid pump 108 may be a variable speed pump or a variable displacement pump, and the control system 128 may operate the conditioning fluid pump 108 to direct the conditioning fluid through the conditioning fluid circuit 102 at a particular flow rate of multiple available flow rates. For instance, in response to an increased cooling demand of the load 106 is desirable, the control system 128 may operate the conditioning fluid pump 108 to increase the flow rate of the conditioning fluid through the conditioning fluid circuit 102.

[0047] The control system 128 may be communicatively coupled to one or more sensor(s) 134 of the HVAC&R system 100. Each sensor(s) 134 may monitor a respective operating parameter and may transmit sensor data indicative of the monitored operating parameter to the control system 128. In response, the control system 128 may operate the HVAC&R system 100 (e.g., the vapor compression system 30 and/or the free-cooling system 104) based on the sensor data. As an example, the operating parameter monitored by the sensor(s) 134 may include a temperature of ambient air, atemperature associated with the load 106 (e.g., an indoor air temperature), a temperature of the chilled fluid 114 entering and/or exiting the heat exchanger 112, a temperature of the conditioning fluid entering and/or exiting the heat exchanger 112, atemperature ofthe condenser 122 (e.g., atemperature of a wall or shell of the condenser 122), a flow rate of conditioning fluid through the conditioning fluid circuit 102, another suitable operating parameter, or any combination thereof. As another example, the control system 128 may receive other suitable input (e.g., user input), which may indicate a desirable or target temperature of the conditioning fluid, a desirable or target flow' rate of the conditioning fluid, and the like. The control system 128 may operate the conditioning fluid pump 108, the chilled fluid pump 118, and/or the fan 124 based on such operating parameters.

[0048] In accordance with the techniques described herein, the chilled fluid 114 that is circulated through the free-cooling system 104 may be an improved chilled fluid 114 having particular thermal and/or fluid properties to enable desirable conditioning of the conditioning fluid via the heat exchanger 112. For example, the thermal and/or fluid properties may be indicative of a capability (e g., capacity) of the chilled fluid 1 14 to transfer heat, such as a specific heat, athermal conductivity, and/or a viscosity. For instance, the specific heat may be below a threshold specific heat, the thermal conductivity may be above a threshold thermal conductivity, and/or the viscosity may be below a threshold viscosity. Thus, more efficient and/or greater heat exchange between the chilled fluid 114 and the conditioning fluid during operation of the free-cooling system 104 may be achieved. As such, a composition of the chilled fluid 114 may be selected to enable the HVAC&R system 100 to operate at a desired efficiency’ to condition the conditioning fluid.

[0049] Additionally or alternatively, the thermal and/or fluid property of the chilled fluid 114 may include a freezing temperature that is below a threshold temperature (e.g., between approximately -30 degrees Fahrenheit and approximately -40 degrees Fahrenheit, approximately -30 degrees Fahrenheit, approximately -35 degrees Fahrenheit, approximately -40 degrees Fahrenheit) to avoid potential freezing of the chilled fluid 114 at various conditions, such as conditions in which the temperature of ambient air is low⁷. By way of example, at least a portion (e.g., a substantial portion, an entirety) of the free-cooling system 104 may be located in an ambient environment to place the chilled fluid 114 in a heat exchange relationship with ambient conditions throughout the free-cooling system 104 (e.g., during flow of the chilled fluid 114 through the conduit system 117). For instance, at low temperatures of ambient air, heat may continually and/or continuously be transferred from the chilled fluid 114 to ambient air as the chilled fluid 114 is circulated throughout the conduit system 117 to reduce the temperature of the chilled fluid 114. During such ambient conditions, a sufficiently low freezing temperature of the chilled fluid 114 may block the chilled fluid 114 from freezing, which may otherwise occur as a result of the ambient air continually and/or continuously reducing the temperature of the chilled fluid 114. As such, the chilled fluid 114 may flow through the free-cooling system 104 in the at least partially vapor state 120 and/or in the liquid state 126 instead block or reduce flow of the chilled fluid of a solid state or at least partially solid state.

[0050] Blocking of freezing or solidification of the chilled fluid 114 may facilitate flow of the chilled fluid 114 through the free-cooling system 104 to enable the chilled fluid 1 14 to exchange heat with the conditioning fluid more efficiently. For example, the chilled fluid 114 may flow more readily from the chilled fluid pump 118 to the condenser 122 to cool the chilled fluid 114, and/or the chilled fluid 114 may flow more readily through the heat exchanger 112 to exchange heat with the conditioning fluid. As a result, the chilled fluid pump 1 18 may operate with reduced energy' consumption, which may reduce corresponding greenhouse gas emissions. Furthermore, blocking of freezing of the chilled fluid 114 may increase a useful lifespan of various components (e.g., of the conduit system 117, of the free-cooling system 104) of the HVAC&R system 100. For example, flow of the chilled fluid 114 through the free- cooling system 104 in the at least partially vapor state 120 and/or in the liquid state 126 may impart a relatively low amount of force onto various components of the free-cooling system 104 as compared to the amount of force imparted by a flow of the chilled fluid 114 through the free-cooling system 104 in a solid state and/or in an at least partially solid state. Thus, a structural integrity of the components of the HVAC&R system 100 may be maintained.

[0051] In accordance with present embodiments, the chilled fluid 114 may include potassium formate and/or aqua ammonia (e.g., water ammonia), such as an aqueous solution of potassium formate and/or aqua ammonia that may include liquid or mostly liquid (e.g., liquid-rich two-phase). Each of potassium formate and aqua ammonia may have thermal properties (e.g., heat transfer properties, freezing temperature, fluid properties) that enable improved (e.g., more efficient) operation of the HVAC&R system 100. For instance, potassium formate and/or aqua ammonia may provide more efficient and/or greater heat exchange with the conditioning fluid and/or may have a relatively lower freezing temperature as compared to another composition of fluid, such as glycol, that may be used as a chilled fluid of the free-cooling system 104. Indeed, embodiments of the free-cooling system 104 described herein may not circulate a chilled fluid that includes glycol. Various other fluids, such as propylene carbonate, a low-pressure refrigerant (e.g., R1233zd(E), R1336mzz(E)), and/or fluids with high vapor pressures, may have certain thermal properties that are desirable (e.g., more desirable than that of glycol) and may additionally or alternatively be used as the chilled fluid 114 in the free-cooling system 104. Such compositions may also be more cost effective than certain other fluids to limit costs associated with implementation and/or operation of the free-cooling system 104. Moreover, potassium formate and/or aqua ammonia may not undesirably flash (e.g., vaporize) during flow of the chilled fluid 114 through the free-cooling system 104. For example, potassium formate and/or aqua ammonia (e.g., an aqueous solution including potassium formate and/or aqua ammonia) may remain in the liquid state 126 at high temperatures and/or low pressures (e.g., sudden temperature increases, sudden pressure drops). The flow of potassium formate and/or aqua ammonia in the liquid state 126 may enable the chilled fluid 114 to be more controllably conditioned (e.g., cooled by the condenser 122) and/or directed through the free-cooling system 104.

[0052] Further still, potassium formate and/or aqua ammonia may be easily detectable. Thus, flow of the chilled fluid 1 14 may be more easily monitored. For example, undesirable flow of the chilled fluid 114 external to the conduit system 117 (e.g., external to piping, escaped flow of the chilled fluid 114) may be more readily detected and addressed. Thus, impact of such undesirable flow (e.g., reduced operation of the HVAC&R system 100, odor emitted by the chilled fluid 114, chemical reactions caused by the chilled fluid 114) may be more promptly addressed. For instance, such flow may be promptly diluted with water or another liquid.

[0053] In certain embodiments, the chilled fluid 114 may be injected with a gas (e.g., an inert gas, such as nitrogen or argon) to increase the pressure of the chilled fluid 1 14 directed through the free-cooling system 104 (e.g., above atmospheric pressure). The increased pressure of the chilled fluid 114 may block entry of external particles (e.g., another gas, such as air or oxygen) into the free-cooling system 104, such as into the conduit system 117, which may otherwise reduce performance of the chilled fluid 114 (e.g.. by chemically changing the composition of the chilled fluid 114).

[0054] The increased efficiency of the HVAC&R system 100 provided by potassium formate and/or aqua ammonia as the chilled fluid 114 of the free-cooling system 104 may enable the HVAC&R system 100 to provide desirable conditioning of the conditioning fluid (e.g., to satisfy a cooling demand of the load 106) while limiting and/or reducing energy consumption during operation of the HVAC&R system. As an example, as compared to operation of the free-cooling system 104 using another chilled fluid having a different composition (e.g., glycol, propylene glycol, ethyl glycol), the control system 128 may operate the chilled fluid pump 118 at a lower operating level (e.g., a lower speed, a lower stage, a lower capacity) and/or operate the fan 124 at a lower speed and nevertheless enable desirable conditioning of the conditioning fluid via potassium formate and/or aqua ammonia (e.g.. an aqueous solution including potassium formate and/or aqua ammonia). Thus, energy consumption associated with operation of the chilled fluid pump 118, of the fan 124, and/or of the control system 128 may be reduced, which may enable a reduction in generation of greenhouse gas emissions. Additionally or alternatively, costs associated with operation and/or installation of the HVAC&R system 100 may be reduced. For example, a more cost-effective embodiment (e.g., an embodiment having reduced specifications and/or operating capacities) of the chilled fluid pump 118, of the fan 124, and/or of the control system 128 may be implemented.

[0055] Further still, usage of potassium formate and/or aqua ammonia as a component of the chilled fluid 114 in accordance with present techniques may reduce a physical footprint occupied by the free-cooling system 104 and/or the HVAC&R system 100. For example, because the thermal and/or fluid properties of potassium formate and/or aqua ammonia may enable increased heat exchange between the chilled fluid 114 and ambient air and/or increased heat exchange between the chilled fluid 114 and the conditioning fluid, an amount of chilled fluid 114 in the free-cooling system 104 and/or a size or amount of certain equipment (e.g., coils of the condenser 122, coils of the heat exchanger 112) implemented with the HVAC&R system 100 to enable such heat exchange may be reduced. As a result, a size or quantity of other components, such as the conduit system 1 17 (e.g., a size or diameter of piping/tubing. a length of piping/tubing), used for enabling flow of the chilled fluid 114 through the free-cooling system 104 may also be reduced. Therefore, costs associated with manufacture and/or implementation of such equipment and components may be reduced. Additionally, the reduced physical footprint occupied by the HVAC&R system 100 may enable more efficient usage of space. As an example, transportation of various components of the HVAC&R system 100 (e.g., of the free-cooling system 104 in a single package) may be more easily performed. As another example, the components of the HVAC&R system 100 may be more readily or easily- assembled and/or installed (e.g., within a particular area). For example, the HVAC&R system 100 including the vapor compression system 30 and the free-cooling system 104 may be manufactured and assembled at a factory or other supplier location and may then be subsequently transported to a customer or installation destination as a single packaged unit. As such, usage of potassium formate and/or aqua ammonia as the chilled fluid 114 may facilitate greater ease of implementation of the HVAC&R system 100.

[0056] As discussed herein, a substantial portion (e.g., an entirety) of the free-cooling system 104 may be positioned in an ambient environment to place the chilled fluid 114 in a heat exchange relationship with ambient air throughout the free-cooling system 104 (e.g., across a substantial portion and/or an entirety of the free-cooling system 104). Thus, the chilled fluid 114 may be continually and/or continuously conditioned (e.g., cooled) during flow of the chilled fluid 114 through the free-cooling system t04, including outside of the condenser 122 (e.g., during flow of the chilled fluid 114 along the conduit system 117 from the condenser 122 to the heat exchanger 1 12). As such, a cooling capacity of the chilled fluid 1 14 may be increased, thereby increasing the capacity⁷ of the chilled fluid 114 to absorb heat from the conditioning fluid via the heat exchanger 112. In this way, the cooling capacity provided by the HVAC&R system 100 may be further increased. Indeed, in certain embodiments, operation of the fan 124 may be suspended, but the chilled fluid 114 may continue to provide desirable conditioning of the conditioning fluid as a result of heat exchange between the chilled fluid 114 and ambient air as a result of flow of the chilled fluid 114 through the free-cooling system 104 (e.g.. the conduit system 117). For example, the control system 128 may suspend operation of the fan 124 in response to a determination the temperature of ambient air is below a threshold temperature to reduce energy⁷ consumption of the HVAC&R system 100 and still provide desirable conditioning of the conditioning fluid (e.g., to satisfy a cooling demand of the load 106).

[0057] Additionally, positioning of the free-cooling system 104 in the ambient environment may block or avoid flow of the chilled fluid 114 into a structure (e.g., the load 106). Thus, certain regulations or codes that otherwise set standards of construction and/or of operation associated with the structure may not apply to the free-cooling system 104. For example, flow of the chilled fluid 114 outside of the structure may reduce odor, chemical reactions, or other impact that may otherwise be caused by the chilled fluid 114 flowing within the structure. Moreover, utilizing potassium formate and/or aqua ammonia as the chilled fluid 114 and/or a component of the chilled fluid 114 may not cause environmental (e.g., groundwater) contamination and may satisfy other certain environmental regulations (e.g., environmental standards). As such, ease of implementation of the free-cooling system 104 may be further achieved.

[0058] The illustrated free-cooling system 104 includes a tank or vessel 136 (e.g.. an expansion tank) that may accommodate a volume of the chilled fluid 114 directed through the free-cooling system 104 (e.g., the conduit system 117). For example, the tank 136 may receive the chilled fluid 114 in the liquid state 126. In some embodiments, the tank 136 may be positioned (e.g., along the conduit system 117, fluidly coupled to the conduit system 117) downstream of the condenser 122 (e g., upstream of the heat exchanger 112) with respect to flow of the chilled fluid 114 from the condenser 122 to the heat exchanger 112. During operation of the free-cooling system 104, the volume of the chilled fluid 114 in the liquid state 126 may increase as a result of thermal expansion, such as when the temperature of the ambient environment or ambient air exceeds a threshold temperature. The tank 136 may receive a portion of the increased volume of the chilled fluid 114 in the liquid state 126. Receipt of the portion of the increased volume of the chilled fluid 114 may reduce pressure that may otherwise be imparted onto other components (e.g., the conduit system 117, the condenser 122, the heat exchanger 112) as a result of the increased volume of the chilled fluid 1 14 flowing through the free-cooling system 104.

[0059] In some embodiments, the tank 136 may contain a pressurized gas 138 (e.g., anon- corrosive gas, nitrogen, argon) to reduce undesirable buildup and/or storage of chilled fluid 114 within the tank 136. For instance, the pressurized gas 138 may impart pressure within the tank 136 to force flow of a portion of the chilled fluid 114 through and/or out of the tank 136 and/or to block vaporization of the chilled fluid 114 within the tank 136. As such, the pressurized gas 138 may reduce an amount or level of chilled fluid 114 that remains in the tank 136 (e g., and does not flow to other components of the free-cooling system 104) to enable the HVAC&R system 100 to operate more efficiently. However, an increased volume of the chilled fluid 114 (e.g., within the free-cooling system 104) resulting from the thermal expansion of the chilled fluid 114 may increase the pressure exerted by the chilled fluid 114 in the tank 136, which may cause the pressurized gas 138 to compress within the tank 136. In this way, the tank 136 and the pressurized gas 138 therein may enable greater intake of the chilled fluid 114 into the tank 136 and may accommodate and/or relieve the volumetric increase of the chilled fluid 114 in other components of the free-cooling system 104.

[0060] Other equipment and/or materials may also be used to facilitate operation of the HVAC&R system 100. For example, certain material may be used as base material for certain components of the HVAC&R system 100 (e.g., free-cooling system 104) and/or may be applied as a coating to the components of the HVAC&R system 100 (e.g., free-cooling system 104) to maintain a structural integrity of the components. For instance, such material may block corrosion, fouling, chemical reaction, or other changes (e.g., chemical alterations, physical distortions) that may affect structural integrity of the components. As such, usage of such material may increase a useful lifespan of HVAC&R system 100 and/or reduce undesirable operation (e.g., suspension of operation, inefficient operation) of the HVAC&R system 100. Indeed, such material may be compatible with the composition of the chilled fluid 114 and/or may reduce possible contamination and/or entrainment of other particles, such as during assembly, during operation, and/or during installation of the free-cooling system 104. In additional or alternative embodiments, an additional component or element, such as a corrosive inhibitor, a biological inhibitor, a stabilizer, or any other component, may be implemented with the chilled fluid 114 to block the chilled fluid 114 from affecting the components of the free- cooling system 104. Thus, the additional component may facilitate implementation and/or operation of free-cooling system 104 utilizing the chilled fluid 114 described herein.

[0061] While only certain features and embodiments of the disclosure have been illustrated and described, many modifications and changes may occur to those skilled in the art, such as variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, including temperatures and pressures, mounting arrangements, use of materials, colors, orientations, and so forth without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described, such as those unrelated to the presently contemplated best mode of carrying out the disclosure, or those unrelated to enabling the claimed disclosure. It should be noted that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.

[0062] The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function]... '’ or “step for [perform]ing [a function] ... ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).

Claims

CLAIMS:

1. An energy efficient heating, ventilating, air conditioning, and refrigeration (HVAC&R) system, comprising: a conditioning fluid circuit configured to direct a conditioning fluid to a load to condition the load; a mechanical cooling system configured to direct a working fluid therethrough, wherein the mechanical cooling system is configured to place the working fluid in a first heat exchange relationship with ambient air and to place the working fluid in a second heat exchange relationship with the conditioning fluid; and a free-cooling system configured to direct a chilled fluid therethrough, wherein the chilled fluid comprises potassium formate or aqua ammonia, and the free-cooling system is configured to place the chilled fluid in a third heat exchange relationship with the conditioning fluid.

2. The energy efficient HVAC&R system of claim 1, wherein the free-cooling system comprises: a first heat exchanger configured to place the chilled fluid in a fourth heat exchange relationship with ambient air; and a second heat exchanger configured to receive the chilled fluid from the first heat exchanger and to place the chilled fluid in the third heat exchange relationship with the conditioning fluid.

3. The energy efficient HVAC&R system of claim 2, wherein the free-cooling system comprises a fan configured to direct ambient air across the first heat exchanger.

4. The energy efficient HVAC&R system of claim 2, wherein the mechanical cooling system comprises an evaporator disposed along the conditioning fluid circuit, the evaporator is configured to place the working fluid in the second heat exchange relationship with the conditioning fluid, and the second heat exchanger is disposed along the conditioning fluid circuit upstream of the evaporator relative to flow of the conditioning fluid through the conditioning fluid circuit.

5. The energy efficient HVAC&R system of claim 1 , wherein the free-cooling system comprises: a conduit system configured to circulate the chilled fluid through the free- cooling system; and a tank fluidly coupled to the conduit system, wherein the tank is configured to receive at least a portion of the chilled fluid to accommodate thermal expansion of the chilled fluid within the conduit system.

6. The energy efficient HVAC&R system of claim 5, wherein the free-cooling system comprises a heat exchanger fluidly coupled to the conduit system and disposed along the conditioning fluid circuit, the heat exchanger is configured to place the chilled fluid in the third heat exchange relationship with the conditioning fluid, and the tank is fluidly coupled to the conduit system upstream of the heat exchanger relative to flow of the chilled fluid through the free-cooling system.

7. The energy efficient HVAC&R system of claim 6, wherein the tank comprises a pressurized gas disposed therein.

8. The energy efficient HVAC&R system of claim 1, wherein the chilled fluid is an aqueous solution comprising potassium formate or aqua ammonia.

9. The energy efficient HVAC&R system of claim 1. comprising a packaged unit, wherein the packaged unit comprises the mechanical cooling system and the free-cooling system.

10. An energy efficient heating, ventilating, air conditioning, and refrigeration (HVAC&R) system, comprising: an air-cooled vapor compression system configured to circulate a working fluid therethrough and configured to place the working fluid in a heat exchange relationship with a conditioning fluid of a conditioning fluid circuit; and a free-cooling system configured to direct a chilled fluid therethrough, wherein the chilled fluid comprises potassium formate or aqua ammonia, and the free-cooling system comprises: a first heat exchanger configured to place the chilled fluid in a heat exchange relationship with ambient air; and a second heat exchanger configured to receive the chilled fluid from the first heat exchanger and to place the chilled fluid in a heat exchange relationship with the conditioning fluid of the conditioning fluid circuit.

11. The energy efficient HVAC&R system of claim 10, wherein the free-cooling system comprises a fan configured to direct ambient air across the first heat exchanger.

12. The energy efficient HVAC&R system of claim 10, wherein the free-cooling system comprises a pump configured to direct the chilled fluid from the second heat exchanger to the first heat exchanger.

13. The energy efficient HVAC&R system of claim 10, wherein the free-cooling system comprises a tank, and the tank is configured to receive at least a portion of the chilled fluid to accommodate thermal expansion of the chilled fluid.

14. The energy efficient HVAC&R system of claim 13, wherein the tank comprises a pressurized gas disposed therein.

15. The energy efficient HVAC&R system of claim 14, wherein the pressurized gas comprises nitrogen or argon.

16. The energy efficient HVAC&R system of claim 10, wherein the chilled fluid does not include glycol.

17. An energy efficient heating, ventilating, air conditioning, and refrigeration (HVAC&R) system, comprising: a vapor compression circuit configured to circulate a working fluid therethrough, wherein the vapor compression circuit comprises an evaporator configured to be disposed along a conditioning fluid circuit and a condenser configured to place the working fluid in a heat exchange relationship with ambient air; and a free-cooling circuit configured to direct a chilled fluid therethrough, wherein the chilled fluid is an aqueous solution comprising potassium formate, aqua ammonia, or a low- pressure refrigerant, and the free-cooling circuit comprises: a first heat exchanger configured to place the chilled fluid in a heat exchange relationship with ambient air; and a second heat exchanger configured to receive the chilled fluid from the first heat exchanger and to place the chilled fluid in a heat exchange relationship with a conditioning fluid of the conditioning fluid circuit.

18. The energy efficient HVAC&R system of claim 17, wherein the aqueous solution comprises the low-pressure refrigerant, and the low-pressure refrigerant comprises R1233zd(E) or R1336mzz(E).

19. The energy efficient HVAC&R system of claim 17, comprising a first fan configured to direct ambient air across the condenser and a second fan configured to direct ambient air across the second heat exchanger.

20. The energy efficient HVAC&R system of claim 17, wherein the free-cooling circuit comprises a tank configured to receive at least a portion of the chilled fluid to accommodate thermal expansion of the chilled fluid, and the tank comprises a pressurized gas disposed therein.