Free cooling system suitable for cooling-water machine

Abstract

A heating, ventilation, air conditioning, and refrigeration system includes: two or more cooling coils configured to receive a flow of refrigerant; a mechanical cooling loop in fluid communication with the two or more cooling coils; a free cooling loop in fluid communication with the cooling coil; a pump in fluid communication with the cooling coil; and a controller. The controller is configured to operate a speed of the pump to distribute the flow of refrigerant between the two or more cooling coils such that a first portion of the refrigerant flowing through at least one of the two or more cooling coils is flowing along the mechanical cooling loop and a second portion of the refrigerant flowing through at least one of the two or more cooling coils is flowing along the mechanical cooling loop. And a second portion of the refrigerant flowing through at least one of the two or more cooling coils is flowing along the free cooling loop. The mechanical cooling loop and the free cooling loop are configured to operate simultaneously.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 378,592, filed on October 6, 2022, and the contents of this application are hereby incorporated herein by reference. Background Art

[0003] Aspects of the present disclosure generally relate to systems and methods for use in refrigeration systems. Specifically, the present disclosure relates to systems and methods for use in refrigeration systems including free cooling systems and mechanical cooling systems.

[0004] Refrigeration and air conditioning systems can rely on chillers to reduce the temperature of a working fluid (usually water). In such applications, cold water can pass through downstream equipment such as an air handler to cool other fluids, such as air in a building. In a typical chiller, the working fluid is cooled by an evaporator, which absorbs heat from the working fluid by evaporating a refrigerant. The refrigerant is then compressed by a compressor and transferred to a condenser. In the condenser, the refrigerant is typically cooled by an air or water stream and recondensed into a liquid. An air-cooled condenser typically includes one or more condenser coils and one or more fans that cause an air flow over the coils. Some systems may include free cooling systems and mechanical cooling systems.

[0005] Mechanical cooling system can be a vapor compression refrigeration cycle, which may include a condenser, an evaporator, a compressor and / or an expansion device. In the evaporator, a liquid or mainly liquid refrigerant evaporates by absorbing heat energy from an air stream and / or a cold fluid (e.g., water), which may also flow through a liquid-to-air heat exchanger of a free cooling system. In the condenser, the refrigerant is deheated, condensed and supercooled. In some cases, the refrigeration system can adjust the speed of the fan of the liquid-to-air heat exchanger and / or the speed of the compressor in the mechanical cooling system to meet the desired cooling demand.

[0006] In some aspects, a free cooling system may include a liquid-to-air heat exchanger used throughout industry and in many heating, ventilation, and residential, commercial, and industrial air conditioning applications. During free cooling, cool outdoor air may be used to cool the refrigerant and the compressor is not used, thereby realizing energy savings.

[0007] Conventional cooling systems that use both mechanical cooling and free cooling may use separate cooling coils for the mechanical cooling system and the free cooling system. This may increase the expense and complexity of such systems. Additionally, some conventional cooling systems that use both mechanical cooling and free cooling are limited to operating free cooling when the compressor is not operating. Furthermore, in conventional cooling systems, the available free cooling capacity is limited. Summary of the invention

[0008] In one aspect, a heating, ventilation, air conditioning and refrigeration system includes two or more cooling coils configured to receive a flow of a refrigerant, a mechanical cooling loop in fluid communication with the two or more cooling coils, a free cooling loop in fluid communication with the two or more cooling coils, a pump in fluid communication with the two or more cooling coils, and a controller. The controller is configured to operate the speed of the pump to distribute the flow of the refrigerant between the two or more cooling coils so that a first portion of the refrigerant flowing through at least one of the two or more cooling coils is flowing along the mechanical cooling loop and a second portion of the refrigerant flowing through at least one of the two or more cooling coils is flowing along the free cooling loop. The mechanical cooling loop and the free cooling loop are configured to operate simultaneously.

[0009] In another aspect, a heating, ventilation, air conditioning and refrigeration system includes a condenser, a heat exchanger, a plurality of cooling towers and a controller. Each of the plurality of cooling towers includes a valve that allows access to the cooling tower and a pump configured to pump refrigerant through the cooling tower. The controller is configured to receive information from a temperature sensor indicating one or more of an ambient temperature, a temperature of the refrigerant leaving the plurality of cooling towers, a temperature of building water to be cooled by the heat exchanger, or a combination thereof. The controller is configured to open or close one or more of the valves based on the received temperature information to allow or prevent access to one or more of the plurality of cooling towers. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a perspective view, with portions cut away, of a commercial or industrial environment employing a refrigeration system according to an aspect of the present disclosure.

[0011] Figure 2 According to one aspect of the present disclosure Figure 1 A perspective view of a refrigeration system that may include both a free cooling system and a mechanical cooling system to enhance the efficiency of the refrigeration system.

[0012] Figure 3 is a block diagram of a refrigeration system according to one aspect of the present disclosure, wherein a plurality of cooling coils are shared between a mechanical cooling loop and a free cooling loop;

[0013] Figure 4 is a block diagram of another refrigeration system according to an aspect of the present disclosure, wherein a plurality of cooling coils are shared between a mechanical cooling loop and a free cooling loop;

[0014] Figure 5is a block diagram of a refrigeration system including a mechanical cooling loop, a free cooling loop, and a plurality of cooling towers according to an aspect of the present disclosure;

[0015] Figure 6 is a block diagram of another refrigeration system including a mechanical cooling loop, a free cooling loop, and a plurality of cooling towers according to an aspect of the present disclosure; and

[0016] Figure 7 According to one aspect of the present disclosure, Figures 3 to 6 Block diagram of a controller used in conjunction with a refrigeration system. DETAILED DESCRIPTION

[0017] The present disclosure relates to a refrigeration system, which includes a free cooling system and a mechanical cooling system for cooling a load. As used herein, a free cooling system may include a system that places a fluid in a heat exchange relationship with ambient air. Therefore, a free cooling system can utilize ambient air in the surrounding environment as a cooling and / or heating fluid. As used herein, a mechanical cooling system may include a system that utilizes a refrigeration cycle of a chiller to perform cooling. A refrigeration system may utilize a free cooling system alone (e.g., a free cooling mode), a mechanical cooling system alone (e.g., a mechanical cooling mode), or a free cooling system and a mechanical cooling system at the same time (e.g., a mixed cooling mode). In order to determine which (which) system(s) to operate, the refrigeration system may include various sensors and / or other monitoring devices that measure the operating conditions of the refrigeration system (e.g., the speed of the fan, the speed of the compressor, the ambient air temperature, the cooling fluid temperature). For example, according to various aspects of the present disclosure, the determination of which (which) system(s) to operate may depend at least on the desired cooling load demand (e.g., the desired temperature of the load) and / or the ambient air temperature (e.g., the temperature of the surrounding environment of the refrigeration system).

[0018] The described aspects allow the same cooling element, such as a coil or dry cooling tower, to be used for both free cooling and mechanical cooling, and also provide the option for simultaneous operation of the coil or dry cooling tower switching between mechanical cooling mode and free cooling mode.

[0019] In one exemplary embodiment, a refrigerant liquid pump circulates liquid refrigerant between the condenser coil and the refrigerant-water heat exchanger to provide free cooling without compressor operation. The same condenser coil is used to condense refrigerant leaving the compressor during mechanical cooling mode without operating the free cooling pump. In hybrid cooling mode, the compressor and refrigerant liquid pump operate simultaneously, with liquid or rich liquid two-phase fed from the pump end of the coil header and vapor or rich vapor two-phase fed from the compressor end at the opposite end of the header.

[0020] In another exemplary embodiment, a dry cooling tower system uses two glycol pumps that supply glycol from opposite heads of a header connected to a plurality of coils. One pump circulates glycol through a condenser associated with a chiller or other mechanical cooling system. The other pump circulates liquid through a free cooling loop that includes a glycol-water heat exchanger. The opposing flows of the two pumps form a natural flow boundary to allow free cooling and mechanical cooling to occur simultaneously in the two loops at substantially different glycol temperatures.

[0021] Turning now to the accompanying drawings, Figure 1 Exemplary applications of refrigeration systems are depicted. In general, such systems may be applied in a range of environments both within the field of heating, ventilation, air conditioning, and refrigeration (HVAC&R) and outside of that field. The refrigeration system may provide cooling to a data center, electrical installation, freezer, chiller, or other environment via vapor compression refrigeration, absorption refrigeration, and / or thermoelectric cooling. However, in the applications presently contemplated, the refrigeration system may also be used in residential, commercial, light industrial, industrial, and any other application for heating or cooling a space or enclosure such as a residence, building, structure, or the like. The refrigeration system may be used in industrial applications, where appropriate, for basic cooling and heating of various fluids.

[0022] Figure 1 A heating, ventilation, air conditioning and refrigeration system (HVAC&R) for building environmental management is included, which may employ one or more heat exchangers. For example, a building 10 is cooled by a system including a refrigeration system 12 and a boiler 14. The refrigeration system 12 is disposed on the roof of the building 10 and the boiler 14 is located in the basement, however, the refrigeration system 12 and the boiler 14 may be located in other equipment rooms or areas next to the building 10. The refrigeration system 12 is an air cooling (e.g., free cooling) device and / or a mechanical cooling system that implements a refrigeration cycle to cool water (or another cooling fluid, such as ethylene glycol). The refrigeration system 12 is housed in a single structure that may include a mechanical cooling loop, a free cooling system, and associated equipment such as pumps, valves, and pipes. For example, the refrigeration system 12 may be a separate integrated rooftop unit that incorporates a free cooling system and a mechanical cooling system. The boiler 14 is a closed container that includes a furnace for heating water. Water (or another cooling fluid) from the refrigeration system 12 and the boiler 14 is circulated through the building 10 through a water conduit 16. Water conduits 16 are routed to air handlers 18 located on individual floors and within sections of building 10 .

[0023] The air handler 18 is coupled to a duct system 20 that is adapted to distribute air between the air handlers 18 and may receive air from an external inlet. The air handler 18 includes a heat exchanger that circulates cold water from the refrigeration system 12 and hot water from the boiler 14 to provide heated or cooled air. A fan within the air handler 18 draws air across the coils of the heat exchanger and directs the conditioned air to an environment such as a room, apartment, or office within the building 10 to maintain the environment at a specified temperature. A control device 22 such as a thermostat may be used to specify the temperature of the conditioned air. The control device 22 may also be used to control the flow of air through and from the air handler 18. Other devices may be included in the system, such as control valves that regulate the flow and pressure of water and / or temperature sensors or switches that sense the temperature and pressure of water, air, etc. In addition, the control device may include a computer system (e.g., a memory storing computer-readable instructions, and a processor configured to execute computer-readable instructions to perform the actions described herein) integrated and / or separate from other building control or monitoring systems, including systems remote from the building 10. It should be noted that although water is discussed as the cooling fluid, any suitable cooling fluid may be utilized in the refrigeration system 12 .

[0024] According to aspects of the present disclosure, the refrigeration system 12 may include a mechanical cooling system and a free cooling system that may be modified and / or enhanced to share cooling elements, such as coils or dry cooling towers, to improve the operating efficiency of the refrigeration system 12. For example, Figure 2 1 is a perspective view of a refrigeration system 12, which may include both a mechanical cooling system (e.g., a vapor compression refrigeration cycle) and a free cooling system to enhance the efficiency of the entire refrigeration system 12. In some aspects, the mechanical cooling system of the refrigeration system 12 may be an air-cooled variable speed screw chiller similar to a YVAA chiller, such as provided by Johnson Controls Incorporated. For example, the mechanical cooling system may be a dual-circuit variable speed screw chiller with a variable speed condenser fan (e.g., a fan that may be used with one or more air-cooled heat exchangers). In addition, the refrigeration system 12 may include a free cooling system that may be utilized alone or in combination with a mechanical cooling system (e.g., a vapor compression refrigeration cycle).

[0025] In certain aspects, the refrigeration system 12 may include a control system (e.g., a memory storing computer-readable instructions, and a processor configured to execute the computer-readable instructions to perform the actions described herein) that is configured to determine whether (and how) to operate the mechanical cooling system and / or the free cooling system to allocate the use of the shared cooling elements based on the temperature of the ambient air (e.g., the air in the surrounding environment of the refrigeration system) and / or the cooling load demand (e.g., the amount of cooling required by the load). Thus, the refrigeration system 12 may operate only the mechanical cooling system (e.g., mechanical cooling mode), only the free cooling system (e.g., free cooling mode), or both the mechanical cooling system and the free cooling system (e.g., hybrid cooling mode) to meet the cooling load demand.

[0026] refer to Figure 3 , for example, refrigeration system 300 is configured to be utilized according to aspects of the present disclosure and includes a mechanical cooling loop depicted by arrow A and a free cooling loop depicted by arrow B, which is operable to share the use of cooling coil 308 individually or simultaneously under the control of controller 326 (e.g., a processor) to perform efficient cooling. Refrigeration system 300 can be the same or similar to that discussed above with respect to refrigeration system 12. In the mechanical cooling loop, the refrigerant in evaporator 316 allows the refrigerant received from building 10 ( Figure 1 ) is expanded, and the resulting vapor refrigerant is fed into the compressor 304. In some aspects, the liquid from the building 10 may not be limited to water. The compressor 304 operates to compress the vapor refrigerant into a high temperature and high pressure superheated vapor, which is fed into the cooling coil 308 connected to the fan 310 for condensing the high temperature and high pressure superheated vapor into a liquid. Further, the mechanical cooling loop may include an expansion valve 312 to control the flow of the subcooled liquid refrigerant in the subcooler 340 back to the evaporator 316 and a portion of the compressor 304. In the free cooling loop depicted by arrow B, the pump 320 controllably directs the flow of cooled liquid or another portion of the two-phase flow to the heat exchanger 324, such as based on a command from a controller 326. Further, in the free cooling loop, the cooled liquid refrigerant or a mixture of liquid and vapor refrigerant cools the liquid from the building 10 ( Figure 1 ) and directs the cooled water back to building 10 ( Figure 1 ). Further, in a free cooling loop, the cooled liquid refrigerant or a mixture of liquid and vapor refrigerant flows from the heat exchanger 324 back to the cooling coil 308, as described in more detail below. Thus, the refrigeration system 300 can controllably share the use of the cooling coil 308 to perform mechanical cooling, to perform free cooling, or to perform both simultaneously.

[0027] In some aspects, cooling coil 308 can be a microchannel coil with a single refrigerant passage. In such aspects, cooling coil 308 can be aluminum. In such aspects, cooling coil 308 is unlikely to corrode because refrigerant (e.g., instead of water and / or ethylene glycol) flows through cooling coil 308. In other aspects, cooling coil 308 can be an aluminum plate fin coil or a copper plate fin coil with copper tubes. Cooling coil 308 can be configured to accommodate both condensed vapor and liquid refrigerant without a large pressure drop. In some aspects, heat exchanger 324 can be a brazed plate heat exchanger. In some aspects, pump 320 is a variable speed pump.

[0028] The refrigeration system 300 can operate in a first or mechanical cooling mode, a second or free cooling mode, and a third or hybrid mode that is a combination of the mechanical cooling mode and the free cooling mode. When the system 300 is operating in the mechanical cooling mode, all of the cooling coils 308 can be used as condenser coils for the mechanical cooling loop. Moreover, advantageously, relative to existing systems with limited capacity, when the system 300 is operating in the free cooling mode, all of the cooling coils 308 can be used in the free cooling loop. When the system 300 is operating in the hybrid mode, a first portion of the cooling coils 308 can operate in the mechanical cooling loop, and at the same time, a second portion of the cooling coils 308 can operate in the free cooling loop, wherein the respective portions can be controlled by the controller 326 as described herein so that all of the cooling coils 308 can operate in the hybrid mode.

[0029] More specifically, water (or another cooling fluid, such as brine) that is circulated through the building 10 via the water conduit 16 described above enters the refrigeration system 300 via the conduit 302 and travels through the heat exchanger 324. As described in more detail below, when the system is operating in a free cooling mode or a hybrid mode, the water is cooled by the refrigerant in the heat exchanger 324. The water then travels through the conduit 306. Valves 311 and 314 are two-position valves coupled to the conduit 306. When valve 311 is in an open position and valve 314 is in a closed position, water can flow from conduit 306 to conduit 318, bypassing the evaporator 316. The water in conduit 318 is returned to the building 10 via the water conduit 16 ( Figure 1 ). When valve 311 is in the closed position and valve 314 is in the open position, water is prevented from flowing directly from pipe 306 to pipe 318. Water can flow from pipe 306 to evaporator 316. With valve 314 in the open position, water flows through evaporator 316, where it is cooled, and into pipe 318, where it is returned to building 10 via conduit 16. In some aspects, valve 311 can be optional. In aspects that do not include valve 311, water will always flow through evaporator 316. Alternatively, valve 311 and valve 314 can also be replaced with 3-way proportional valves.

[0030] When the refrigeration system 300 is operated in the mechanical cooling mode, the direction of the refrigerant circulation is indicated by arrow A. Specifically, vapor refrigerant flows from the compressor 304 to the cooling coil 308 via the pipe 328. The vapor refrigerant condenses into a liquid or a mixture of liquid and vapor refrigerant in the cooling coil 308. The fan 310 coupled to the cooling coil 308 can promote heat transfer between the mixture of liquid and gas in the cooling coil 308 and the air. In some aspects, the fan 310 can be a variable speed fan. In such aspects, the controller 326 can be configured to control the speed of the fan 310 based on the desired amount of heat transfer between the cooling coil 308 and the ambient air. The liquid refrigerant leaving the cooling coil 308 is collected via the second pipe 332 and then travels through the expansion valve 312 to the evaporator 316. The liquid refrigerant evaporates in the evaporator 316, thereby absorbing heat from the water from the building 10 that travels to the evaporator 316 via the pipes 306, 318 and travels from the evaporator. The vapor refrigerant travels along the conduit 334 back to the compressor 304, as indicated by arrow A. The pump 320 and the heat exchanger 324 are not used in the mechanical cooling mode. In some aspects, the check valve 336 can prevent fluid from entering the pump 320 during the mechanical cooling mode. In some aspects, the subcooler 340 can be positioned along the second conduit 332 between the cooling coil 308 and the expansion valve 312 to subcool the refrigerant liquid in the second conduit 332 or condense any vapor present in the second conduit 332. In some aspects, a fan 344 can be coupled to the subcooler 340 to facilitate heat transfer between the refrigerant in the subcooler 340 and the ambient air.

[0031] In some aspects, the evaporator 316 may include an evaporator heater 360 to reduce the likelihood of an icing condition occurring in the evaporator. In such aspects, the evaporator heater 360 may be energized during standby to reduce the likelihood of an icing condition occurring in the evaporator. In some aspects, the reservoir may be positioned upstream of the pump and configured to supply liquid refrigerant to the pump 320 when the pump 320 is turned on at the beginning of the free cooling mode or the hybrid mode. In some aspects, the pump 320 may be lower than the other components of the system 300 so that gravity assists in feeding the liquid refrigerant to the pump 320, which may prevent the pump 320 from running dry. In some aspects, the reservoir may be oriented so that the reservoir is located below the conduit 332. In such aspects, the pump 320 may draw refrigerant from the bottom of the reservoir, which may prevent the pump 320 from inhaling air / vapor.

[0032] When the refrigeration system 300 is operated in the free cooling mode, cold liquid refrigerant enters the second pipe 332 from the cooling coil 308, as shown by arrow B. The cold liquid refrigerant is pumped via pump 320 to the heat exchanger 324, where it absorbs heat from water entering the heat exchanger 324 via pipe 302 from the building 10. Liquid refrigerant or a mixture of liquid and vapor refrigerant exits the heat exchanger 324 into pipe 348 and enters three-way valve 352. The three-way valve 352 is configured to prevent the refrigerant in pipe 328 from entering the heat exchanger 324. The three-way valve 352 is configured to allow liquid refrigerant to travel from pipe 348 to pipe 328 via valve 352. The liquid refrigerant then travels from pipe 328 to the cooling coil 308. Check valve 356 may prevent liquid refrigerant from entering the compressor 304. Valve 352 may also allow liquid refrigerant to enter pipe 328 near the outlet of the compressor 304. As described in more detail below, this portion of valve 352 can be opened during the hybrid mode to allow liquid refrigerant to enter the portion of the cooling coil 308 that is operating in the mechanical cooling mode via conduit 354. Arrow B shows the circulation direction of the refrigerant in the free cooling mode. The compressor 304, the subcooler 340, and the evaporator 316 are not used in the free cooling mode. In some aspects, in the free cooling mode, the valve 314 can be in a closed position and the valve 311 can be in an open position, thereby allowing cooled water to bypass the evaporator 316. In some aspects, when no or substantially no water flows through the evaporator 316 under low ambient temperature conditions, the evaporator heater can be energized to reduce the possibility of ice formation on the evaporator 316.

[0033] As indicated above, the cooling coils 308 are used during both mechanical cooling and free cooling. The specific number of cooling coils 308 used for mechanical cooling or free cooling may vary based on commands sent from the controller 326 to the compressor 304 and / or the pump 320 during the hybrid mode. An exemplary operation of the controller 326 to allocate the use of the cooling coils 308 between mechanical cooling and free cooling operations is described in more detail below.

[0034] During the hybrid operating mode, both the mechanical cooling process and the free cooling process are operable, sharing the use of the cooling coil 308 managed by the controller 326. During the hybrid mode, the controller 326 is configured to operate the compressor 304 and the pump 320 to direct a first portion of the refrigerant along a mechanical cooling loop indicated by arrow A using a first portion of the cooling coil 308 and direct a second portion of the refrigerant along a free cooling loop indicated by arrow B using a second portion of the cooling coil 308. Although the number of cooling coils 308 operating in the mechanical cooling loop and the free cooling loop may vary, all coils 308 are operable during the hybrid mode. In some aspects, the pipe 328 may be oriented such that a portion of the pipe 328 proximate the end coupled to the heat exchanger 324 is lower than the end coupled to the compressor 304. This may prevent mixing of the liquid and vapor refrigerant streams when the system 300 is operating in the hybrid mode.

[0035] For example, the controller 326 may be configured to receive temperature information, such as information indicating the ambient temperature of the environment surrounding the cooling system 300, the temperature of the inlet water from the building 10, the temperature of the refrigerant entering the heat exchanger 324 or near the heat exchanger, the temperature of the refrigerant leaving the cooling coil 308, etc., from one or more temperature sensors in the environment, one or more temperature sensors in a pipe near the inlet water from the building 10, one or more temperature sensors near the inlet of the heat exchanger 324, and / or one or more temperature sensors near the outlet of the cooling coil 308, respectively. The controller 326 may be configured to determine, based on the received information, a first portion of the refrigerant that should be operated in the mechanical cooling mode and a second portion of the refrigerant that should be operated in the free cooling mode in order to provide a desired amount of cooling to the inlet water from the building 10. The controller 326 may be configured to determine a pumping rate at which the determined first portion of the refrigerant is operated according to the mechanical cooling mode and the determined second portion of the refrigerant is operated according to the free cooling mode. The pumping rate may be configured to distribute the flow of the refrigerant so that the first portion of the refrigerant flows through the mechanical cooling loop and the second portion of the refrigerant flows through the free cooling loop. Controller 326 may be configured to operate pump 320 at the determined pumping rate.

[0036] In some aspects, in response to determining that the refrigerant leaving the cooling coil 308 (or the temperature of the refrigerant near or entering the heat exchanger 324) is hotter than the water from the building 10, the controller 326 can command the system 300 to exit the hybrid or free cooling mode and operate in the mechanical cooling mode.

[0037] In some aspects, the controller 326 can be configured to receive information indicating a temperature and / or pressure near the inlet of the pump 320. The controller 326 can be configured to determine that subcooled liquid refrigerant is entering the pump 320 and / or the piping 332 near the pump 320 based on the received information. In some aspects, a water bypass valve can be positioned around the evaporator 316, and a heater can be coupled to the evaporator 316 to maintain the temperature of the evaporator 316 above the freezing point of the cold liquid flowing through the evaporator.

[0038] In some aspects, the controller 326 may be configured to receive information indicating a pressure drop across the pump 320 from a pump sensor and to receive information indicating a pressure drop across the cooling coil 308 from one or more pressure sensors. In some aspects, a first pressure sensor may be positioned in the pipe 332 or at the inlet of the pump 320, a second pressure sensor may be positioned at the outlet of the pump 320, and a third pressure sensor may be positioned in the pipe 328. In such aspects, the controller 326 may determine the head of the pump based on the difference between the pressure determined by the first pressure sensor and the pressure determined by the second pressure sensor. The controller 326 may determine the speed of the pump 320 based on the frequency of the pump 320. The controller 326 may then determine the volume flow rate (e.g., gallons per minute) of the refrigerant flowing through the pump 320. In some aspects, the controller 326 may determine the volume flow rate through the pump 320 based on a graph, a lookup table, etc. The controller 326 can then determine the free cooling capacity (Q) based on the temperature and pressure of the refrigerant at or near the inlet of the heat exchanger 324 (e.g., determined by a temperature and pressure sensor positioned at or near the inlet of the heat exchanger 324), the temperature or pressure of the refrigerant at or near the outlet of the heat exchanger 324 (e.g., determined by a temperature and pressure sensor positioned at or near the outlet of the heat exchanger 324), and the volume flow rate of the refrigerant flowing through the pump 320. C ). Then, the controller 326 may C and the target free cooling capacity Q for the current ambient conditions of the system 300 T In response to the instruction Q C <(Q T -ΔQ), the controller 326 may increase the frequency of the pump 320. In response to the indication Q C >(Q T -ΔQ), the controller 326 may reduce the frequency of the pump 320. In response to the indication (Q T -ΔQ) C <(Q T ​+ΔQ), the controller 326 can maintain the current frequency of the pump 320. In some aspects, the ΔQ value can be a configurable value that sets a deadband to prevent excessive changes in the pump frequency. This can prevent mixing of liquid and vapor refrigerant flows traveling through the cooling coil 308. In some aspects, the controller 326 can command the three-way valve 352 to inject liquid refrigerant into the coil 308 operating according to the mechanical cooling loop (and therefore receiving gas refrigerant from the compressor 304) to help match the pressure drop across the first portion of the cooling coil 308 (e.g., the cooling coil 308 operating in the mechanical cooling loop) with the pressure drop across the second portion of the cooling coil 308 (e.g., the cooling coil 308 operating in the free cooling loop).

[0039] refer to Figure 4 , another exemplary refrigeration system 400 also includes a plurality of cooling coils 404 shared between the mechanical cooling loop and the free cooling loop, and wherein the liquid refrigerant of the refrigeration system 400 is configured to cool the second refrigerant of the mechanical cooling system, which is schematically shown as box 406. The free cooling loop is configured to cool water ( Figure 1 ). The system 400 can operate in a first mode, in which all cooling coils 404 are used by the mechanical cooling loop; a second mode, in which all cooling coils 404 are used by the free cooling loop; and a third mode (e.g., a hybrid mode) in which the cooling coils 404 are shared between the mechanical cooling loop and the free cooling loop, as described herein. All cooling coils 404 can be used in the third mode.

[0040] The cooling coil 404 is coupled between the conduit 408 and the second conduit 412. A first end of the conduit 408 is coupled to a first pump or condenser pump 416 that is configured to receive warm liquid refrigerant from the condenser 420. In some aspects, the condenser pump 416 can be a variable speed pump.

[0041] When the system is operating in mechanical cooling mode or hybrid mode, the flow of liquid refrigerant through the mechanical cooling loop is generally shown by arrow C. Specifically, the condenser pump 416 is configured to pump the liquid refrigerant into the cooling coil 404 through the pipe 408. The check valve 424 can be positioned downstream of the condenser pump 416 to prevent the liquid refrigerant from flowing back into the pump 416. The liquid refrigerant then flows to the cooling coil 404, where the ambient air cools the liquid refrigerant. In some aspects, a fan 428 can be coupled to the cooling coil 404. In some aspects, the fan 428 can be operated to increase the heat transfer between the liquid refrigerant flowing through the cooling coil 404 and the ambient air. The cold liquid refrigerant leaving the cooling coil 404 travels through the second pipe 412 to the condenser 420. The condenser 420 is configured to receive a hot vapor flow of another refrigerant from the compressor of the mechanical cooling system 406 via a pipe 432. The cold liquid refrigerant entering the condenser 420 via the second conduit 412 cools the hot vapor phase flow of the other refrigerant from the mechanical cooling system 406, for example, cooling the other refrigerant until the other refrigerant condenses into a liquid. The liquid phase of the other refrigerant leaves the condenser 420 via conduit 436 and then travels therein to an expansion device of the mechanical cooling system 406. This heat exchange converts the cold liquid refrigerant entering the condenser 420 into hot liquid refrigerant, which leaves the condenser 420 and travels to the pump 416 via conduit 440.

[0042] The second end of conduit 408 is coupled to a second pump or free cooling pump 444, which is configured to receive warm liquid refrigerant from heat exchanger 448. In some aspects, free cooling pump 444 can be a variable speed pump.

[0043] When the system is operating in free cooling mode or hybrid mode, the flow of liquid refrigerant through the free cooling loop is generally shown by arrow D. Specifically, the free cooling pump 444 is configured to pump the liquid refrigerant into the cooling coil 404 through the pipe 408. The check valve 452 can be positioned downstream of the free cooling pump 444 to prevent the liquid refrigerant from flowing back into the free cooling pump 444. The liquid refrigerant then flows to the cooling coil 404, where the ambient air cools the liquid refrigerant. In some aspects, a fan 428 can be coupled to the cooling coil 404. In some aspects, the fan 428 can be operated to increase the heat transfer between the liquid refrigerant flowing through the cooling coil 404 and the ambient air. The fan 428 can be a variable speed fan. The controller 426 (e.g., a processor) can control the speed of the fan 428 based on the desired amount of heat transfer with the ambient air. The cold liquid refrigerant leaving the cooling coil 404 travels through the second pipe 412 to the heat exchanger 448. The heat exchanger 448 is configured to receive a warm water flow from the building 10 conduit 16 via conduit 464. The cold liquid refrigerant entering the heat exchanger 448 via the second conduit 412 cools the water flow from the building 10. The cooled water exits the heat exchanger via conduit 460 and then returns to the conduit 16 of the building 10. The warm liquid refrigerant exits the heat exchanger 448 and travels to the pump 444 via conduit 468.

[0044] In some aspects, the cooling coil 404 can be a microchannel coil with a single refrigerant passage. In such aspects, the cooling coil 404 can be aluminum. In other aspects, the cooling coil 404 can be an aluminum plate fin coil or a copper plate fin coil with copper tubes. The cooling coil 404 can be configured to accommodate both condensing vapor and liquid refrigerant without a large pressure drop. In some aspects, the heat exchanger 448 can be a brazed plate heat exchanger.

[0045] During the hybrid operating mode, both the mechanical cooling process and the free cooling process are operable. During the hybrid mode, the controller 426 is configured to operate the condenser pump 416 to direct a first portion of the refrigerant along a mechanical cooling loop indicated by arrow C using a first portion of the cooling coils 404, and to operate the free cooling pump 444 to direct a second portion of the refrigerant along a free cooling loop indicated by arrow D using a second portion of the cooling coils 404. Although the number of cooling coils 404 operating in the mechanical cooling loop and the free cooling loop may vary, all coils 404 may be operable during the hybrid mode. For example, during Figure 4 , the system 400 is operating in a mixed mode. As schematically indicated by flow boundary line 472, Figure 4In some aspects, three cooling coils 404 operate in a mechanical cooling loop and one cooling coil 404 operates in a free cooling loop. However, in other configurations, the use of cooling coils 404 may be different. For example, in some aspects, two cooling coils 404 may operate in a mechanical cooling loop and two cooling coils 404 may operate in a free cooling loop. In another example, one cooling coil 404 may operate in a mechanical cooling loop and three cooling coils 404 may operate in a free cooling loop. The portion of the liquid refrigerant operating in the mechanical cooling loop (e.g., the first portion) may be hotter than the portion of the liquid refrigerant operating in the free cooling loop (e.g., the second portion). This temperature difference may prevent or reduce the amount of mixing between the first portion and the second portion of the liquid refrigerant.

[0046] For example, with the controller 326 ( Figure 3 ), the controller 426 may be configured to receive information indicating an ambient temperature of the environment surrounding the cooling system 300, a temperature of the incoming water from the building 10, etc. The controller 426 may be configured to determine, based on the received information, a first portion of the refrigerant (or cooling coil 404) that should be operated in the mechanical cooling mode and a second portion of the refrigerant (or cooling coil 404) that should be operated in the free cooling mode in order to provide a desired amount of cooling to the incoming water from the building 10 and the second refrigerant from the mechanical cooling system 406. The controller 426 may be configured to determine relative pumping rates (e.g., a first pumping rate for the condenser pump 416 and a second pumping rate for the free cooling pump 444) for the condenser pump 416 and the free cooling pump 444, which is configured to distribute the refrigerant between the mechanical cooling loop and the free cooling loop as needed. The controller 426 may be configured to command the pumps 416, 444 to operate at the determined pumping rates.

[0047] In some aspects, the controller 426 can be configured to receive information indicative of the temperature of the refrigerant entering the heat exchanger 448 or near the heat exchanger, the temperature of the refrigerant leaving the cooling coil 404, etc., from one or more temperature sensors in the tubes near the inlet of the heat exchanger 448 and / or near the outlet of the cooling coil 404, etc., respectively. In response to determining that the refrigerant leaving the cooling coil 404 (or the temperature of the refrigerant approaching or entering the heat exchanger 448) is hotter than the refrigerant from the building water 10, the controller 426 can command the system 400 to exit the hybrid or free cooling mode and operate in the mechanical cooling mode.

[0048] In some aspects, the controller 426 may be configured to receive information indicating the temperature of the liquid refrigerant entering each cooling coil 404 from a temperature sensor 476 proximate to the inlet of each of the cooling coils 404. In such aspects, the controller 426 may be configured to change the pumping rates of the condensation pump 416 and the free cooling pump 444 to increase the temperature difference between the cooling coils 404 on either side of the flow boundary between the cooling coils 404 operating in the mechanical cooling loop and the cooling coils 404 operating in the free cooling loop (e.g., the cooling coils 404 on either side of the line 472). For example, the controller 426 may compare the temperature of the liquid refrigerant entering the cooling coils operating in the mechanical cooling loop with the temperature of the liquid refrigerant entering the cooling coils operating in the free cooling loop. The controller 426 may determine the difference between the temperature of the liquid refrigerant entering the cooling coils operating in the mechanical cooling loop and the temperature of the liquid refrigerant entering the cooling coils operating in the free cooling loop, and confirm the temperature difference with the temperature threshold. In response to determining that the temperature difference is below the temperature threshold, the controller 426 may change the pumping rate of the condenser pump 416 and / or the free cooling pump 444 to increase the temperature difference. In response to determining that the temperature difference is greater than or equal to the temperature threshold, the controller 426 may maintain the current pumping rate of the condenser pump 416 and / or the free cooling pump 444.

[0049] The controller 426 may also be configured to control the relative speeds of the pumps 416, 444 based on the number of cooling coils 404 used in the mechanical cooling loop and the free cooling loop, respectively. For example, in the illustrated aspect, the mechanical cooling loop uses three cooling coils 404, while the free cooling loop uses one cooling coil 404. Under such conditions, the controller 426 may be configured to command the condenser pump 416 to operate at a rate three times faster than the free cooling pump 444. In another example, the mechanical cooling may use two cooling coils 404 and the free cooling loop may use two cooling coils 404. Under such conditions, the controller 426 may be configured to command the condenser pump 416 and the free cooling pump 444 to operate at substantially the same rate. In another example, the mechanical cooling may use one cooling coil 404 and the free cooling loop may use three cooling coils 404. Under such conditions, the controller 426 may be configured to command the free cooling pump 444 to operate at a rate three times faster than the rate of the condenser pump 416.

[0050] refer to Figure 5, the exemplary refrigeration system 500 includes a mechanical cooling loop 504 and a free cooling loop 508, wherein the mechanical cooling loop 504 includes a first refrigerant and the free cooling loop 508 includes a second refrigerant different from the first refrigerant. In some aspects, the first refrigerant can be R1234ze, R134a, R410a, and other similar refrigerants suitable for reducing temperature. In some aspects, the second refrigerant can be ethylene glycol liquid, fresh water, or another substance suitable for reducing temperature. Under environmental conditions where the ambient temperature does not drop below the freezing point of water, the second refrigerant can be water. The second refrigerant is configured to cool the first refrigerant. As described in more detail below, the system 500 can operate in a first mode, a second mode, and a third mode, in which the mechanical cooling loop 504 is configured to cool water from the duct 16 of the building 10; in the second mode, the free cooling loop 508 is configured to cool water from the duct 16 of the building 10; and in the third mode, both the mechanical cooling loop 504 and the free cooling loop 508 are configured to cool water from the duct 16 of the building 10.

[0051] Mechanical cooling loop 504 includes compressor 512, condenser 516, expansion device 520 and evaporator 524. A first refrigerant enters compressor 512 (e.g., from the outlet of evaporator 524) through pipe 528. The first refrigerant then travels from compressor 512 to condenser 516 via pipe 532. In condenser 516, the first refrigerant is cooled by the second refrigerant so that the first refrigerant condenses into a liquid or a mixture of liquid or vapor. In some aspects, condenser 516 can be a shell and tube condenser. The first refrigerant then travels from condenser 516 to expansion device 520 via pipe 536. The first refrigerant travels from expansion device 520 to evaporator 524 via pipe 540. The liquid first refrigerant evaporates in evaporator 524, thereby absorbing heat from water from the building as the water travels through evaporator 524. The first refrigerant then travels to compressor 512 via pipe 528.

[0052] The free cooling loop 508 includes a condenser 516, a proportional valve 544, a plurality of cooling towers 548, and a heat exchanger 552. In some aspects, the cooling tower is a dry cooling tower 548. As described above, the second refrigerant cools the first refrigerant in the condenser 516. The warm second refrigerant leaves the condenser 516 via a pipe 556. The warm second refrigerant enters the proportional valve 544 and travels from the proportional valve 544 to the plurality of cooling towers 548 via a pipe 560. The second refrigerant travels through the plurality of cooling towers 548, where it is cooled by ambient air. The cold second refrigerant that leaves the cooling tower 548 enters a pipe 564. A first portion of the cold second refrigerant enters the condenser 516 via a pipe 568. A second portion of the cold second refrigerant travels to the heat exchanger 552 via a pipe 572. When water from the building flows through the heat exchanger 552, the cold second refrigerant absorbs heat from the water from the building. The warm second refrigerant leaves the heat exchanger 552 and travels to the valve 544, and then travels to the cooling tower 548 via the pipe 560. The position of the valve 544 is configured to determine the ratio of the refrigerant entering the pipes 560 and 574. When the system 500 is operating in the mechanical cooling mode, the valve 544 is configured to direct the second refrigerant to the condenser 516 (e.g., substantially all of the second refrigerant is in the first part). When the system 500 is operating in the free cooling mode, the valve 544 is configured to direct the second refrigerant to the heat exchanger 552 (e.g., substantially all of the refrigerant is in the second part). When the system 500 is operating in the mixed mode, the position of the valve 544 is configured to distribute the refrigerant leaving the pipe 564 into the first part and the second part. The warm second refrigerant leaving the heat exchanger 552 enters the pipe 574, and travels through the valve 544 and through the pipe 560 and enters the cooling tower 548.

[0053] In the illustrated aspect, a plurality of cooling towers 548 include three cooling towers 548a, 548b, 548c arranged in parallel. In other aspects, a plurality of cooling towers 548 may include more or less cooling towers. Cooling towers 548a, 548b, 548c are substantially similar, so only cooling tower 548a is described in detail herein. The same number is used to indicate the same assembly between cooling towers 548a, 548b, 548c. Cooling tower 548a includes pump 576a, check valve 580a, a plurality of cooling coils 584a and fan 588a. Pump 576a is configured to pump the second refrigerant into cooling coil 584a. Fan 588a is configured to increase heat transfer with ambient air. Check valve 580a can move between a first or open position and a second or closed position. In some aspects, the controller 526 (e.g., a processor) can be configured to turn one or more of the pumps 576a-576c on or off based on the requirements of the system 500. For example, the controller 526 can be configured to receive information from one or more temperature sensors indicating ambient temperature, the temperature of the second refrigerant exiting the cooling towers 548a, 548b, 548c, the temperature of the building water, etc. The controller 526 can be able to determine the number of cooling towers 548a, 548b, 548c to operate, the pump speed for the pumps 576a, 576b, 576c, the fan speed for the fans 588a, 588b, 588c, etc. based on the received temperature information. For example, for relatively cold ambient temperatures (e.g., ambient temperatures below a predetermined temperature threshold), the second refrigerant can be cooled without using all of the cooling towers 548. Under such conditions, the controller 526 can command one or more of the pumps 576 to shut down. This may occur under conditions where the ambient temperature is much lower than the target temperature for the second refrigerant, and the controller 526 may command one or more of the pumps 576 to turn off. This may achieve energy savings because the pumps 576 and fans 588 for the cooling tower 548 that are not in use are turned off. For example, for relatively warm ambient temperatures (e.g., ambient temperatures above a predetermined temperature threshold), the controller 526 may command one or more of the pumps 576 to turn on, increase the speed of the fans 588a, 588b, 588c, etc. This may occur under conditions where the ambient temperature is close to the target temperature for the second refrigerant, and the controller 526 may command one or more of the pumps 567 to turn on.

[0054] Building water is configured to enter the system 500 via conduit 584. The water travels through conduit 584 to the heat exchanger 552. In aspects of free cooling loop 508 operation (e.g., when the system 500 is operating in the second mode or the third mode), the water is cooled by the second refrigerant in the heat exchanger 552. The water travels from the heat exchanger 552 to the evaporator 524 via conduit 586. In aspects of mechanical cooling loop 504 operation (e.g., when the system 500 is operating in the first mode or the third mode), the evaporation of the first refrigerant absorbs heat from the water in the evaporator 524. The cooled water is returned to the building duct 16 via conduit 592.

[0055] When the system 500 is operating in hybrid mode, both the mechanical cooling loop 504 and the free cooling loop 508 are operating. During hybrid mode, the building water is cooled by both the heat exchanger 552 and the evaporator 524.

[0056] In some aspects, the compressor 512 can be an oil-injected screw compressor. In such aspects, the condenser 516 can include an integrated oil separator 596. In such aspects, the difference between the discharge pressure at the inlet of the condenser 516 and the suction pressure at the inlet of the compressor 512 can drive oil to the compressor 512 to lubricate the compressor 512.

[0057] In other aspects, condenser 516 can be a brazed plate condenser. In such aspects, a separate oil separator can be used to supply oil to compressor 512. In some aspects, compressor 512 can be a centrifugal compressor, a scroll compressor, or another type of compressor with relatively low oil circulation. In such aspects, an oil separator may not be used.

[0058] refer to Figure 6 , the exemplary refrigeration system 600 includes a mechanical cooling loop 604 and a free cooling loop 608 similar to the refrigeration system 500, but a valve such as valve 644 is positioned between a cooling tower 648 and a condenser 616 including an integrated oil separator 696 so that a portion of the cold refrigerant leaving the cooling tower 648 can travel through a heat exchanger 652 before the condenser 616. The liquid refrigerant absorbs heat from the building water in the heat exchanger 652. The warmer liquid refrigerant flowing from the heat exchanger 652 into the condenser 616 increases the temperature of the liquid second refrigerant entering the condenser 616. This can increase the discharge pressure of the liquid refrigerant leaving the condenser 616, which in turn can exert a force of the discharge pressure on the oil within the oil separator 969, thereby driving the lubricant to the compressor 612. The refrigeration system 600 is substantially similar to the system 500, and because it is different from the system 500, only it will be described in detail herein. Similar components between the system 500 and the system 600 are shown using similar numbers.

[0059] The free cooling loop 608 includes a condenser 616, a proportional valve 644, a plurality of cooling towers 648, and a heat exchanger 652. As described above, the second refrigerant cools the first refrigerant in the condenser 616. The warm second refrigerant leaves the condenser 616 via a pipe 656 and travels to the plurality of cooling towers 648. The second refrigerant travels through the plurality of cooling towers 648, where it is cooled by ambient air. The cold second refrigerant leaving the cooling towers 648 enters a pipe 664 and travels to a valve 644. The valve 644 is configured to direct a first portion of the cold second refrigerant to enter the condenser 616 via a pipe 668. The valve 644 is configured to direct a second portion of the cold second refrigerant to enter the heat exchanger 652 via a pipe 672. When the water from the building and the cold second refrigerant flow through the heat exchanger 652, the cold second refrigerant absorbs heat from the water from the building. The warm second refrigerant leaves the heat exchanger 652 and travels to the condenser 616 via a pipe 660. The position of valve 644 is configured to determine the ratio of refrigerant entering conduits 668 and 672. When system 600 is operating in mechanical cooling mode, valve 644 is configured to direct the second refrigerant to condenser 616 (e.g., substantially all of the second refrigerant is in the first portion). When system 600 is operating in free cooling mode, valve 644 is configured to direct the second refrigerant to heat exchanger 652 (e.g., substantially all of the refrigerant is in the second portion). When system 600 is operating in mixed mode, the position of valve 644 is configured to distribute the refrigerant exiting conduit 664 into the first portion and the second portion.

[0060] When the system 600 is operating in hybrid mode, both the mechanical cooling loop 604 and the free cooling loop 608 are operating. During hybrid mode, the building water is cooled by both the heat exchanger 652 and the evaporator 624.

[0061] In some aspects, the compressor 612 can be an oil-injected screw compressor. In such aspects, the condenser 616 can include an integrated oil separator 696. In such aspects, the difference between the discharge pressure at the inlet of the condenser 616 and the suction pressure at the inlet of the compressor 612 can drive oil to the compressor 612 to lubricate the compressor 612. In some aspects, the controller 626 (e.g., a processor) can be configured to receive information indicating the suction pressure and / or the discharge pressure. The controller 626 can be configured to compare the suction pressure, the discharge pressure, and / or the difference between the suction pressure and the discharge threshold with the target pressure threshold. In response to determining that the suction pressure, the discharge pressure, and / or the difference between the suction pressure and the discharge pressure is lower than the target pressure threshold, the controller 626 can be configured to reposition the valve 644 to increase the amount of cold liquid refrigerant entering the heat exchanger 652, wherein the cold liquid refrigerant absorbs heat from the building water. The liquid refrigerant then flows from the heat exchanger 652 to the condenser 616, thereby increasing the temperature of the liquid second refrigerant entering the condenser 616. Increasing the temperature of the second refrigerant entering the condenser 616 will increase the discharge pressure of the liquid refrigerant leaving the condenser 616 , which increases the force of the discharge pressure on the oil within the oil separator 969 , thereby driving the lubricant to the compressor 612 .

[0062] In some aspects, when the system 600 is operating in a free cooling mode, the controller may operate the pumps 676a, 676b, 676c at high speed to maximize the amount of free cooling.

[0063] In other aspects, condenser 616 can be a brazed plate condenser. In such aspects, a separate oil separator can be used to supply oil to compressor 612. In some aspects, compressor 612 can be a centrifugal compressor, a scroll compressor, or another type of compressor with relatively low oil circulation. In such aspects, an oil separator may not be used.

[0064] In some aspects, during the free cooling mode, the controller 326, 426, 526, 626 can be configured to control the speed of the free cooling pump 320, 444, 576a-576c, 676a-676c to prevent icing conditions in the heat exchanger 324, 448, 552, 652. In some aspects, the system 300, 400, 500, 600 can adjust the speed of the fan 668 when the second refrigerant flows through the cooling coil / cooling tower to prevent icing conditions in the heat exchanger 324, 448, 552, 652. In some aspects, the fan speed can be determined by the refrigerant temperature in the pipe 664. For example, the fan speed can be controlled so that the temperature in the pipe 664 is equal to or above the freezing point of the water from the building 10 or slightly below the freezing point of the water from the building 10.

[0065] Although the systems 300, 400, 500, 600 show a single refrigerant circuit in the examples illustrated herein, it is contemplated that in some aspects, the systems 300, 400, 500, 600 may include multiple refrigerant circuits. In a compact multi-circuit system, stacked cooling coils may be used such that ambient air flows through the cooling coils for the refrigerant circuits in a series configuration. In some aspects, water from the building 10 may flow through the evaporator for each refrigerant circuit in series in the evaporators of the multiple refrigerant circuits.

[0066] Additionally, relative to existing solutions, systems 300, 400, 500, 600 may provide one or more of the following advantages: lower cost, smaller space requirements, simplified piping, higher performance, improved freeze protection, the ability to use aluminum without corrosion issues, simple controls, and / or the ability to select coils for free cooling or condenser heat rejection.

[0067] refer to Figure 7 In one aspect, the controller 326, 426, 526, 626 may further include one or more additional components that can be operated in conjunction with the system 300, 400, 500, 600. For example, each of the controllers 326, 426, 526, 626 may include a processor 704 for performing processing functions associated with one or more of the components and functions described herein. The processor 704 may include a single group or multiple groups of processors or a multi-core processor. In addition, the processor 704 may be implemented as an integrated processing system and / or a distributed processing system. In one aspect, for example, the controller 326, 426, 526, 626 may be implemented as one or more specially programmed or constructed processor modules of the processor 704, or the processor 704 may execute one or more computer executable codes that define the controller 326, 426, 526, 626 (e.g., mechanical cooling mode, free cooling mode, hybrid mode), or some combination thereof.

[0068] The controller 326, 426, 526, 626 may further include a memory 708, such as for storing data used herein and / or a local version of an application program executed by the processor 704. The memory 708 may include any type of computer-readable medium available to the computer or processor 704, such as a random access memory (RAM), a read-only memory (ROM), a tape, a disk, an optical disk, a volatile memory, a non-volatile memory, and any combination thereof. In one aspect, for example, the memory 708 may be a computer-readable storage medium that stores one or more computer-executable codes defining the controller 326, 426, 526, 626 or data associated therewith when the controller 326, 426, 526, 626 is operating the processor 704 to perform operations of the system 300, 400, 500, 600 (e.g., operating components of the system 300, 400, 500, 600 in a mechanical cooling mode, a free cooling mode, a hybrid mode, or some combination thereof).

[0069] Moreover, the controller 326, 426, 526, 626 may further include a communication component 712, which includes one or more buses that enable internal communication between components of the controller 326, 426, 526, 626, and includes one or more interfaces that enable communication with external devices. In this way, the communication component 712 is configured to establish and maintain communication with one or more entities using the hardware, software, and services described herein. In one aspect, for example, with respect to external communications, the communication component 712 may further include a transmission chain component (e.g., a protocol layer entity, a processor, a modulator, an antenna) and a reception chain component (e.g., a protocol layer entity, a processor, a demodulator, an antenna) associated with one or more transmitters and receivers, respectively, or one or more transceivers operable to interface with an external device. In one aspect, for example, the communication component 712 can operate in cooperation with the components of the systems 300, 400, 500, 600 described herein to exchange and / or generate communications and / or signaling described herein.

[0070] Optionally, in one aspect, the controller 326, 426, 526, 626 may further include a data storage area 716, which may be any suitable combination of hardware and / or software that provides mass storage of information, databases, and programs employed in conjunction with the various aspects described herein. For example, the data storage area may store temperature and pressure tables for thermodynamic properties of the refrigerant used in the system 300, 400, 500, 600. For example, the data storage area 716 may be a computer-readable storage medium, such as a data repository, for computer-executable code and / or applications not currently being executed by the processor 704.

[0071] In another optional embodiment, controller 326,426,526,626 may additionally include user interface component 720, which is operable to receive input from users of system 300,400,500,600, and further operable to generate output for presenting to the user.User interface component 720 may include but is not limited to one or more input devices, which may include but is not limited to keyboard, numeric keypad, mouse, touch-sensitive display, positioning key, function key, microphone, voice recognition component or the mechanism that can receive input from the user or any combination thereof.Further, user interface component 720 may include but is not limited to one or more output devices, which may include but is not limited to display, loudspeaker, tactile feedback mechanism, printer, the mechanism that can present output to the user or any combination thereof.On the one hand, for example, user interface component 720 may cooperate with controller 326,426,526,626 to exchange and / or generate communication and / or signaling as described herein.

[0072] The present disclosure may include aspects according to one or more of the following clauses.

[0073] Clause 1. A heating, ventilation, air conditioning and refrigeration system comprising: two or more cooling coils, the two or more cooling coils being configured to receive a flow of refrigerant; a mechanical cooling loop, the mechanical cooling loop being fluidly connected to the two or more cooling coils; a free cooling loop, the free cooling loop being fluidly connected to the two or more cooling coils; a pump, the pump being fluidly connected to the two or more cooling coils; and a controller, the controller being configured to: operate the speed of the pump to distribute the flow of the refrigerant between the two or more cooling coils so that a first portion of the refrigerant flowing through at least one of the two or more cooling coils is flowing along the mechanical cooling loop, and a second portion of the refrigerant flowing through at least one of the two or more cooling coils is flowing along the free cooling loop; wherein the mechanical cooling loop and the free cooling loop are configured to operate simultaneously.

[0074] Clause 2. The heating, ventilation, air conditioning, and refrigeration system of Clause 1, wherein the controller is configured to control the speed of the pump so that the actual free cooling capacity is substantially the same as the target free cooling capacity under ambient conditions.

[0075] Clause 3. A heating, ventilation, air conditioning and refrigeration system according to clause 1 or clause 2, further comprising: a compressor, which is fluidly connected to the two or more cooling coils and is configured to circulate at least a first portion of the flow of the refrigerant through the mechanical cooling loop of the heating, ventilation, air conditioning and refrigeration system; an evaporator, which is configured to receive at least the first portion of the flow of the refrigerant from the two or more cooling coils and is configured to place the first portion of the flow of the refrigerant in a first heat exchange relationship with a fluid to be cooled by the mechanical cooling loop; a pump, which is fluidly connected to the two or more cooling coils and is configured to circulate at least a second portion of the flow of the refrigerant through the free cooling loop of the heating, ventilation, air conditioning and refrigeration system; and a heat exchanger, which is fluidly connected to the pump and is configured to place the second portion of the flow of the refrigerant in a second heat exchange relationship with the fluid to be cooled by the free cooling loop.

[0076] Clause 4. A heating, ventilation, air conditioning and refrigeration system as described in clause 3, wherein the controller is configured to stop operation of the free cooling loop in response to determining that the temperature of the refrigerant leaving the heat exchanger is higher than the temperature of the fluid to be cooled.

[0077] Clause 5. A heating, ventilation, air conditioning and refrigeration system as described in clause 3, wherein the controller is configured to command a valve positioned near the outlet of the heat exchanger to move to a configuration in which refrigerant leaving the heat exchanger is injected into the first portion of the flow of refrigerant through the mechanical cooling loop.

[0078] Clause 6. The heating, ventilation, air conditioning, and refrigeration system of Clause 3, wherein the controller is configured to control the pump to prevent an icing condition in the heat exchanger during operation of the free cooling loop.

[0079] Clause 7. A heating, ventilation, air conditioning and refrigeration system according to any preceding clause, wherein the pump is a first pump and further includes a second pump, and wherein the controller is configured to control the speed of the first pump and the second pump to distribute the flow of the refrigerant.

[0080] Clause 8. The heating, ventilation, air conditioning, and refrigeration system of Clause 7, wherein the first pump is configured to direct refrigerant to the mechanical cooling loop and the second pump is configured to direct refrigerant to the free cooling loop.

[0081] Clause 9. A heating, ventilation, air conditioning and refrigeration system according to clause 7, wherein the controller is configured to control the speed of the first pump and the second pump so that the difference between the temperature of the first portion of the refrigerant traveling through the cooling coil and the temperature of the second portion of the refrigerant traveling through the cooling coil is at least a predetermined threshold.

[0082] Clause 10. The heating, ventilation, air conditioning and refrigeration system of any preceding clause, wherein the number of the two or more cooling coils used for mechanical or free cooling is variable based on the speed of the pump.

[0083] Clause 11. A heating, ventilation, air conditioning and refrigeration system as described in any of the preceding clauses, wherein: the first portion of the refrigerant is configured to cool another refrigerant, the second portion of the refrigerant is configured to cool a water flow from a building, and the controller is configured to distribute the flow of refrigerant between the two or more cooling coils so that the first portion of the refrigerant provides a desired amount of cooling to the other refrigerant and the second portion of the refrigerant provides a desired amount of cooling to the water flow from the building.

[0084] Clause 12. A heating, ventilation, air conditioning and refrigeration system comprising: a condenser, a heat exchanger, a plurality of cooling towers, each of the plurality of cooling towers comprising a valve allowing access to the cooling tower and a pump configured to pump refrigerant through the cooling tower; and a controller configured to: receive information from a temperature sensor indicating one or more of an ambient temperature, a temperature of the refrigerant leaving the plurality of cooling towers, a temperature of building water to be cooled by the heat exchanger, or a combination thereof; and turn one or more of the pumps on or off based on the received temperature information to allow or prevent access to one or more of the plurality of cooling towers.

[0085] Clause 13. The heating, ventilation, air conditioning, and refrigeration system of Clause 12, wherein the controller is configured to shut down one or more of the pumps in response to determining that the ambient temperature is below a predetermined threshold.

[0086] Clause 14. The heating, ventilation, air conditioning, and refrigeration system of clause 12 or 13, wherein the controller is configured to turn on one or more of the pumps in response to determining that the ambient temperature is above a predetermined threshold.

[0087] Clause 15. A heating, ventilation, air conditioning and refrigeration system according to any one of clauses 12 to 14, wherein the refrigerant is a second refrigerant and the heating, ventilation, air conditioning and refrigeration system comprises: a mechanical cooling loop, the mechanical cooling loop comprising a compressor, the condenser, an expansion device and an evaporator, the mechanical cooling loop being configured to cool the first refrigerant; a free cooling loop, the free cooling loop comprising the condenser, the heat exchanger and the plurality of cooling towers, the free cooling loop being configured to cool the second refrigerant; and wherein the heating, ventilation, air conditioning and refrigeration system is operable in a mixed mode in which both the mechanical cooling loop and the free cooling loop operate.

[0088] Clause 16. The heating, ventilating, air conditioning, and refrigeration system of Clause 15, wherein during the mixed mode, the building water is cooled by both the evaporator and the heat exchanger.

[0089] Clause 17. The heating, ventilating, air conditioning, and refrigeration system of Clause 15, wherein the second refrigerant exiting the heat exchanger is cooled by the cooling tower during the mixed mode.

[0090] Clause 18. The heating, ventilation, air conditioning, and refrigeration system of Clause 15, wherein the controller is configured to control the pump to prevent an icing condition in the heat exchanger when the free cooling loop is operable.

[0091] Clause 19. A heating, ventilation, air conditioning and refrigeration system according to clause 15, wherein the condenser includes an integrated oil separator containing a lubricant, and wherein the controller is configured to: receive information indicating a discharge pressure at the inlet of the condenser; receive information indicating a suction pressure at the inlet of the compressor; and in response to determining that the difference between the suction pressure and the discharge pressure is below a predetermined threshold, increase the amount of cold liquid refrigerant entering the heat exchanger, thereby increasing the amount of lubricant distributed from the integrated oil separator.

[0092] Clause 20. A heating, ventilation, air conditioning and refrigeration system as described in any of clauses 12 to 19, wherein the condenser includes an integral oil separator containing a lubricant, and wherein a portion of the refrigerant leaving the cooling tower passes to a heat exchanger before passing to the condenser and is warmed before passing to the condenser, and wherein the warmed portion of the refrigerant is configured to drive the lubricant to the compressor.

Claims

1. A heating, ventilation, air conditioning and refrigeration system comprising: two or more cooling coils configured to receive a flow of refrigerant; a mechanical cooling loop in fluid communication with the two or more cooling coils; a free cooling loop in fluid communication with the two or more cooling coils; a pump in fluid communication with the two or more cooling coils; as well as A controller, the controller being configured to: operating the speed of the pump to distribute the flow of the refrigerant between the two or more cooling coils such that a first portion of the refrigerant flowing through at least one of the two or more cooling coils is flowing along the mechanical cooling loop and a second portion of the refrigerant flowing through at least one of the two or more cooling coils is flowing along the free cooling loop; Wherein the mechanical cooling loop and the free cooling loop are configured to operate simultaneously.

2. The heating, ventilation, air conditioning and refrigeration system of claim 1, wherein the controller is configured to control the speed of the pump so that an actual free cooling capacity is substantially the same as a target free cooling capacity under ambient conditions.

3. The HVAC system of claim 1, further comprising: a compressor in fluid communication with the two or more cooling coils and configured to circulate at least a first portion of the flow of the refrigerant through the mechanical cooling loop of the HVACR system; an evaporator configured to receive at least the first portion of the flow of the refrigerant from the two or more cooling coils and configured to place the first portion of the flow of the refrigerant in a first heat exchange relationship with a fluid to be cooled by the mechanical cooling loop; a pump in fluid communication with the two or more cooling coils and configured to circulate at least a second portion of the flow of the refrigerant through the free cooling loop of the HVACR system; as well as A heat exchanger is in fluid communication with the pump and is configured to place the second portion of the flow of the refrigerant in a second heat exchange relationship with the fluid to be cooled by the free cooling loop.

4. The HVAC system of claim 3, wherein the controller is configured to stop operation of the free cooling loop in response to determining that the temperature of the refrigerant leaving the heat exchanger is higher than the temperature of the fluid to be cooled.

5. The heating, ventilation, air conditioning, and refrigeration system of claim 3, wherein the controller is configured to command a valve positioned proximate an outlet of the heat exchanger to move to a configuration in which refrigerant exiting the heat exchanger is injected into the first portion of the flow of the refrigerant through the mechanical cooling loop.

6. The HVAC system of claim 3, wherein the controller is configured to control the pump to prevent an icing condition in the heat exchanger during operation of the free cooling loop.

7. The HVAC system of claim 1, wherein the pump is a first pump and further comprises a second pump, and wherein the controller is configured to control the speeds of the first pump and the second pump to distribute the flow of the refrigerant.

8. The heating, ventilation, air conditioning, and refrigeration system of claim 7, wherein the first pump is configured to direct refrigerant to the mechanical cooling loop and the second pump is configured to direct refrigerant to the free cooling loop.

9. The HVAC system of claim 7, wherein the controller is configured to control the speeds of the first pump and the second pump so that a difference between a temperature of the first portion of the refrigerant traveling through the cooling coil and a temperature of the second portion of the refrigerant traveling through the cooling coil is at least a predetermined threshold.

10. The HVAC system of claim 1, wherein a number of the two or more cooling coils used for mechanical or free cooling is variable based on the speed of the pump.

11. The heating, ventilation, air conditioning and cooling system of claim 1, wherein: the first portion of the refrigerant being configured to cool another refrigerant, The second portion of the refrigerant is configured to cool a flow of water from a building, and The controller is configured to distribute the flow of the first refrigerant between the two or more cooling coils such that the first portion of the refrigerant provides a desired amount of cooling to the another refrigerant and the second portion of the refrigerant provides a desired amount of cooling to the water flow from the building.

12. A heating, ventilation, air conditioning and cooling system comprising: Condenser, Heat exchangers, a plurality of cooling towers, each cooling tower of the plurality of cooling towers comprising a valve allowing access to the cooling tower and a pump configured to pump a refrigerant through the cooling tower; as well as A controller, the controller being configured to: receiving information from a temperature sensor indicative of one or more of an ambient temperature, a temperature of refrigerant exiting the plurality of cooling towers, a temperature of building water to be cooled by the heat exchanger, or a combination thereof; as well as One or more of the pumps are turned on or off based on the received temperature information to allow or prevent access to one or more of the plurality of cooling towers.

13. The HVAC system of claim 12, wherein the controller is configured to shut down one or more of the pumps in response to determining that the ambient temperature is below a predetermined threshold.

14. The HVAC system of claim 12, wherein the controller is configured to activate one or more of the pumps in response to determining that the ambient temperature is above a predetermined threshold.

15. The HVAC system of claim 12, wherein the refrigerant is a second refrigerant and the HVAC system comprises: a mechanical cooling loop including a compressor, the condenser, an expansion device, and an evaporator, the mechanical cooling loop being configured to cool a first refrigerant; a free cooling loop, the free cooling loop comprising the condenser, the heat exchanger, and the plurality of cooling towers, the free cooling loop being configured to cool the second refrigerant; as well as Wherein the heating, ventilation, air conditioning and refrigeration system is operable in a hybrid mode wherein both the mechanical cooling loop and the free cooling loop are operable.

16. The heating, ventilation, air conditioning and refrigeration system of claim 15, wherein during the hybrid mode, the building water is cooled by both the evaporator and the heat exchanger.

17. The HVAC system of claim 15, wherein the second refrigerant exiting the heat exchanger is cooled by the cooling tower during the hybrid mode.

18. The HVAC system of claim 15, wherein the controller is configured to control the pump to prevent an icing condition in the heat exchanger when the free cooling loop is operable.

19. The HVAC system of claim 15, wherein the condenser includes an integral oil separator containing a lubricant, and wherein the controller is configured to: receiving information indicative of a discharge pressure at an inlet of the condenser; receiving information indicative of a suction pressure at an inlet of the compressor; as well as In response to determining that the difference between the suction pressure and the discharge pressure is below a predetermined threshold, the amount of cold liquid refrigerant entering the heat exchanger is increased, thereby increasing the amount of lubricant dispensed from the integrated oil separator.

20. The HVAC system of claim 12, wherein the condenser includes an integral oil separator containing a lubricant, and wherein a portion of the refrigerant exiting the cooling tower travels to a heat exchanger prior to traveling to the condenser and is warmed prior to traveling to the condenser, and wherein the warmed portion of the refrigerant is configured to drive the lubricant to a compressor.

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