Hvac&r system, method of operating the hvac&r system, and chiller system

Abstract

A heating, ventilation, air conditioning and / or refrigeration (HVAC&R) system (10) includes a vapor compression system (14) having an evaporator (38), a condenser (34), and a compressor (32). The compressor (34) is configured to guide refrigerant through the vapor compression system (14) in both a normal operating mode and a natural cooling mode. The HVAC&R system (10) also includes a controller (40) configured to supply power to the motor (50) of the compressor (34) in the normal operating mode and to suspend the supply of power to the motor (50) of the compressor (34) in the natural cooling mode.

Description

Technical Field

[0001] Cross-referencing

[0002] This application claims priority and benefit to U.S. Provisional Application No. 63 / 081,565, filed September 22, 2020, entitled “FREE COOLING OPERATION OF A CHILLER”, the entire contents of which are incorporated herein by reference for all purposes.

[0003] This invention relates to the natural cooling operation of a cooler. Prior Technology

[0004] This section aims to introduce the reader to the various technical aspects that may relate to the various aspects of this disclosure, which will be described below. This discussion is intended to help provide the reader with background information to facilitate a better understanding of the various aspects of this disclosure. Therefore, it should be understood that these statements will be interpreted from this perspective, rather than as an admission of prior art.

[0005] This application relates generally to a cooler system, and more specifically to the natural cooling operation of a cooler system.

[0006] Cooler systems or vapor compression systems utilize a working fluid (e.g., a refrigerant) that changes phase between vapor, liquid, and combinations thereof in response to varying temperatures and pressures exposed within components of the cooler system. A cooler system may include an evaporator configured to place the working fluid (e.g., refrigerant) in a heat exchange relationship with a conditioning fluid (e.g., water), such that the working fluid absorbs heat from the conditioning fluid. The conditioning fluid, cooled by the working fluid, can then be delivered to conditioning equipment and / or the conditioned environment served by the cooler system. In such applications, the conditioning fluid may pass through downstream equipment (e.g., air handling units) to condition other fluids (e.g., air in a building).

[0007] In some cooler systems, a cooling fluid (e.g., water) may be used additionally or alternatively to cool the working fluid. For example, a cooler system may include a cooling tower (or other water or cooling fluid source) configured to supply cooling fluid to the condenser of the cooler system. The cooling fluid may be cooled by ambient air in the cooling tower (or other water or cooling fluid source), and the condenser allows the cooling fluid from the cooling tower to exchange heat with the refrigerant, transferring heat from the refrigerant to the cooling fluid. A compressor may be located between the condenser and the evaporator and may be powered to adjust the refrigerant pressure and circulate the refrigerant between the components of the cooler system.

[0008] In some systems, natural cooling operation can be activated during certain conditions, such as when the ambient air temperature is relatively low (e.g., in spring, winter, and / or autumn). When the ambient air temperature is relatively low, the cooling demand on the cooler may decrease, and / or the operating conditions may allow the cooler to operate with sufficient cooling capacity without powering the compressor. For example, because the cooling fluid supplied by the cooling tower may have a relatively low temperature when the ambient air temperature is relatively low, the cooler system can operate to cool the regulating fluid with sufficient capacity without powering the compressor. In conventional cooler systems utilizing natural cooling, power supply to the cooler system's compressor can be terminated, and the refrigerant can be directed to bypass the compressor via a compressor bypass valve, etc. In conventional systems employing natural cooling, directing the refrigerant to bypass the compressor avoids pressure losses that would otherwise reduce the cooling capacity of the cooler system. However, it is now recognized that conventional or conventional cooler systems utilizing traditional or conventional natural cooling technologies may include irrelevant components that increase the number of system parts and cost (e.g., compressor bypass valves), may be limited in terms of the types of refrigerants that can be used, and may be subject to improvements in terms of available cooling capacity. Summary of the Invention

[0009] The following provides an overview of some embodiments disclosed herein. It should be understood that these aspects are presented only to provide the reader with a brief overview of these particular embodiments, and are not intended to limit the scope of this disclosure. In fact, this disclosure may cover many aspects that may not be stated below.

[0010] In one embodiment, a heating, ventilation, air conditioning and / or refrigeration (HVAC&R) system includes a vapor compression system having an evaporator, a condenser and a compressor. The compressor is configured to guide refrigerant through the vapor compression system in both a normal operating mode and a natural cooling mode. The HVAC&R system also includes a controller configured to supply power to the compressor motor in the normal operating mode and to suspend the motor power supply to the compressor in the natural cooling mode.

[0011] In another embodiment, a method for operating a heating, ventilation, air conditioning and / or refrigeration (HVAC&R) system includes: supplying electrical power to a motor of a compressor of a vapor compression system in response to a normal operating mode of the HVAC&R system, such that the compressor is driven by the motor and refrigerant is biased between the evaporator and the condenser of the vapor compression system. The method further includes: stopping the power supply to the compressor of the vapor compression system in response to a natural cooling mode of the HVAC&R system, such that the compressor rotor is suspended and refrigerant can pass through the compressor.

[0012] In another embodiment, a cooler system includes: a compressor configured to circulate refrigerant through a refrigerant circuit; a motor for the compressor; and a controller configured to supply power to the motor of the compressor in response to a normal operating mode of the cooler system and to stop supplying power to the motor of the compressor in response to a natural cooling mode of the cooler system. Simple Explanation of the Diagram

[0013] A better understanding of the various aspects of this disclosure can be achieved by reading the following detailed description and referring to the accompanying drawings, in which:

[0014] [Figure 1] is a perspective view of an embodiment of a building in a commercial environment that utilizes a heating, ventilation, air conditioning and / or refrigeration (HVAC&R) system, according to one aspect of this disclosure;

[0015] [Figure 2] is a perspective view of an embodiment of the vapor compression system (sometimes referred to as the cooler system) in the HVAC&R system of Figure 1, according to one aspect of this disclosure;

[0016] [Figure 3] is a schematic diagram of an embodiment of the vapor compression system of Figure 2 according to one aspect of this disclosure;

[0017] [Figure 4] is a schematic diagram of an embodiment of the vapor compression system of Figure 2 according to one aspect of this disclosure;

[0018] [Figure 5] is a schematic diagram of an embodiment of a portion of the vapor compression system of Figure 2 according to one aspect of this disclosure, including a controller and a portion of the compressor;

[0019] [Figure 6] is a schematic diagram of an embodiment of the vapor compression system of Figure 2 according to one aspect of this disclosure; and

[0020] [Figure 7] is a process flow diagram based on one aspect of the present disclosure, illustrating an implementation method of the operation of the vapor compression system of Figure 2. Implementation

[0021] One or more specific implementations will be described below. To provide a concise description of these implementations, not all features of the actual implementations are described in the specification. It should be understood that in the process of developing any such actual implementation (as in any engineering or design project), numerous implementation-specific decisions must be made to achieve the developer's specific goals (e.g., compliance with system-related and business-related constraints), which may vary from one implementation to another. Furthermore, it should be understood that such development work can be complex and time-consuming, but remains routine design, production, and manufacturing work for those skilled in the art who benefit from this disclosure.

[0022] When describing the elements of various embodiments of this disclosure, the articles "a," "an," and "the" are intended to indicate the presence of one or more elements. The terms "comprising," "including," and "having" are intended to be inclusive and indicate that additional elements may exist in addition to those listed. Furthermore, it should be understood that references to "an embodiment" or "an embodiment" of this disclosure are not intended to be construed as excluding the existence of additional embodiments that also have the described features.

[0023] This disclosure relates to an embodiment of a heating, ventilation, air conditioning and / or refrigeration (HVAC&R) system utilizing a vapor compression system (hereinafter referred to in some cases as a cooler or cooler system). More specifically, this disclosure relates to the natural cooling mode or operation of the cooler.

[0024] Currently disclosed coolers include a natural cooling mode, in which a passive (e.g., unpowered) compressor of the HVAC&R system receives a refrigerant flow through it. That is, during natural cooling mode, the motor configured to drive the compressor may be unpowered or inactive. For example, the cooler is configured to circulate a working fluid (e.g., refrigerant) through the compressor, evaporator, condenser, expansion valve, and other possible components. The evaporator can place the refrigerant and a conditioning fluid (e.g., water) in a heat exchange relationship, allowing the refrigerant to absorb heat from the conditioning fluid. The conditioning fluid can circulate between the evaporator and a structure (e.g., a building) where it is used to cool airflow delivered to the conditioned space of the structure. In some embodiments, the air handling unit (AHU) of the HVAC&R system can receive conditioning fluid from the cooler and use it to cool the airflow delivered to the conditioned space. The conditioning fluid can then return to the evaporator for further cooling.

[0025] Refrigerant can circulate from the evaporator towards the compressor, which is powered in the cooler's normal operating mode to increase the refrigerant's temperature and pressure before it is delivered to the condenser. After receiving the refrigerant, the condenser exchanges heat between the refrigerant and a cooling fluid (e.g., water) circulating between the condenser and a cooling source (e.g., a cooling tower). The cooling fluid absorbs heat from the refrigerant in the condenser, causing the refrigerant's vapor form to condense into a liquid. The heated cooling fluid can then be transferred from the condenser to the cooling source (e.g., a cooling tower) to be cooled and delivered back to the condenser. For example, a cooling tower can use ambient air to cool the cooling fluid. Other cooling sources are also possible, such as underground cooling storage tanks.

[0026] Under certain conditions, such as during autumn, winter, and / or spring, ambient air or other cooling media may be relatively cool. Relatively cool ambient air can reduce the cooling demand on the condenser. Additionally, relatively cool ambient air can keep the cooling fluid delivered from the cooling source (e.g., a cooling tower) to the condenser relatively cool. The relatively low temperature of the cooling fluid can, to some extent, cool and condense the refrigerant, allowing the condenser to (e.g., via an evaporator, as described above) provide sufficient cooling energy to the building without powering the compressor. This mode of operation, where the refrigerant is compressed without powering the compressor and forced through the vapor compression system, can be referred to as natural cooling or natural cooling mode.

[0027] In conventional coolers employing natural cooling technology, during natural cooling conditions, the refrigerant is directed around the compressor, preventing significant pressure loss that would otherwise reduce the cooler's cooling capacity. According to this disclosure, a natural cooling mode is employed where the compressor is not powered (i.e., the compressor motor is not operated), but rather the compressor is configured or designed to receive and guide the refrigerant through it. For example, the compressor can be configured such that, when the compressor motor is not powered, the compressor rotor is suspended and rotates freely in response to receiving refrigerant, thereby reducing, mitigating, or eliminating pressure losses that might otherwise be caused by the compressor. In one embodiment, the compressor may include a magnetic bearing for suspending the compressor rotor, or, in an oil-free system, a rolling element bearing. Alternatively or concurrently, the compressor's variable geometry diffuser (VGD) and / or pre-rotating vane (PRV) may open in response to the activation of the natural cooling mode.

[0028] Compared to conventional systems that use compressor bypass components for natural cooling operation, this embodiment significantly reduces the number of parts, complexity, and / or cost of the cooler system by suspending the compressor rotor, opening the VGD and PRV, and guiding the refrigerant through the compressor during natural cooling mode without powering the compressor motor. Furthermore, this reduction in the number of cooler parts, complexity, and / or cost is achieved without causing significant pressure loss within the compressor. In this way, this embodiment improves cooler operation and reduces associated manufacturing, operating, and / or maintenance costs. Furthermore, the features described herein enable the use of a wide variety of refrigerants (e.g., low-pressure, medium-pressure, and high-pressure refrigerants), including R-123, R-514A, R-1224yd, R-1233zd, R-134a, R-1234ze, R-1234yf, R-1311, R-32, R-410A, etc. Other features (such as falling film evaporators, expansion valve throttling, refrigerant pumps, etc.) can be incorporated into the system disclosed herein to improve cooling capacity and other aspects to a level superior to conventional embodiments, and will be described in detail below with reference to the accompanying drawings.

[0029] Turning now to the accompanying drawings, Figure 1 is a perspective view of an embodiment of a heating, ventilation, air conditioning and / or refrigeration (HVAC&R) system 10 for use in a building 12 in a typical commercial environment. The HVAC&R system may include a boiler 16 that supplies a warm fluid to heat the building 12, and a vapor compression system 14 that supplies a cooling liquid to cool the building 12. The vapor compression system 14 (sometimes referred to as a cooler) may circulate a working fluid (e.g., refrigerant) that is cooled by a cooling fluid (e.g., a liquid, such as water) in the condenser of the vapor compression system 14 and heated by a conditioning fluid (e.g., a liquid, such as water) in the evaporator of the vapor compression system 14. The cooling fluid may be supplied by a cooling tower that cools the cooling fluid via, for example, ambient air. The conditioning fluid cooled by the working fluid as described above may be used to cool the airflow supplied to the conditioned spaces of the building 12.

[0030] HVAC&R system 10 may also include an air distribution system that circulates air through building 12. This air distribution system may further include air return duct 18, air supply duct 20, and / or air handling unit 22. In some embodiments, air handling unit 22 may include a heat exchanger connected to boiler 16 and vapor compression system 14 via duct 24. The heat exchanger in air handling unit 22 may receive heated liquid from boiler 16 or conditioned fluid (e.g., cooled liquid, such as water) from vapor compression system 14, depending on the operating mode of HVAC&R system 10. HVAC&R system 10 is shown as having a separate air handling unit on each floor of building 12; however, in other embodiments, HVAC&R system 10 may include air handling unit 22 and / or other components that can be shared between two or more floors.

[0031] The vapor compression system 14 or cooler may include a compressor disposed between the evaporator and condenser described above. The compressor can operate in a normal operating mode, in which it receives a working fluid (e.g., refrigerant) and is powered to increase the temperature and pressure of the working fluid before it is delivered to the condenser. According to this disclosure, the compressor can operate in a natural cooling mode when the cooling fluid (or in other words, the ambient air used to cool the cooling fluid via a cooling tower) is at a sufficiently low temperature that the vapor compression system 14 can provide sufficient cooling capacity without powering the compressor motor to force the refrigerant through the vapor compression system 14.

[0032] For example, in natural cooling mode, the compressor receives the working fluid (e.g., refrigerant) but is not powered to force the refrigerant through it. Instead, the compressor is configured to allow the refrigerant to pass through it (e.g., via natural convection). To reduce or eliminate pressure loss in the compressor during natural cooling mode, the compressor can be a centrifugal compressor including a rotor that is suspended via one or more magnetic bearings or, in an oil-free system, via one or more rolling element bearings. Additionally, the variable geometry diffuser (VGD) and / or pre-rotating vane (PRV) of the centrifugal compressor can be opened in natural cooling mode to allow passive refrigerant flow through it. Thus, although the motor of the centrifugal compressor is not powered during natural cooling mode, the rotor of the centrifugal compressor rotates freely in response to receiving refrigerant. By configuring the centrifugal compressor as described above, natural cooling mode can be utilized without bypassing the compressor while still enabling the vapor compression system 14 to provide sufficient cooling capacity to the building 12. Accordingly, the currently conceived embodiment achieves effective natural cooling while reducing the number of parts, pressure loss, and overall cost of conventional embodiments. In addition, unlike traditional implementation methods, the currently envisioned implementation method is compatible with a wide variety of refrigerants, including R-123, R-514A, R-1224yd, R-1233zd, R-134a, R-1234ze, R-1234yf, R-1311, R-32, R-410A, etc.

[0033] Figures 2 and 3 are schematic diagrams of embodiments of the vapor compression system 14 or cooler that can be used in the HVAC&R system 10 of Figure 1. The vapor compression system 14 circulates refrigerant through a loop starting with a compressor 32 (e.g., a centrifugal compressor). This loop may also include a condenser 34, an expansion valve(s) or an expansion device(s) 36, and an evaporator 38. The vapor compression system 14 may further include a control console 40 having an analog-to-digital (A / D) converter 42, a microprocessor 44, non-volatile memory 46, and / or an interface panel 48.

[0034] Some examples of fluids that can be used as refrigerants in the vapor compression system 14 are hydrofluorocarbon (HFC) based refrigerants (e.g., R-410A, R-407, R-134a), hydrofluoroolefins (HFO), "natural" refrigerants (such as ammonia (NH3), R-717, carbon dioxide (CO2), R-744), or hydrocarbon-based refrigerants, water vapor, or any other suitable refrigerant. Other possible refrigerants include R-123, R-514A, R-1224yd, R-1233zd, R-134a, R-1234ze, R-1234yf, R-1311, R-32, and R-410A. In some embodiments, the vapor compression system 14 can be configured to efficiently utilize refrigerants with a standard boiling point of about 19 degrees Celsius (66 degrees Fahrenheit) at one atmosphere (as opposed to medium-pressure refrigerants such as R-134a, also known as low-pressure refrigerants). As used in this article, "standard boiling point" can refer to the boiling point temperature measured at one atmosphere.

[0035] In some embodiments, the vapor compression system 14 may use one or more of a variable speed drive (VSD) 52, a motor 50, a compressor 32, a condenser 34, an expansion valve or expansion device 36, and / or an evaporator 38. The motor 50 may drive the compressor 32 during normal operating mode and may be powered by the VSD 52. The VSD 52 receives alternating current (AC) power (wherein AC power includes a specific fixed line voltage and fixed line frequency from an AC power source) during normal operating mode and supplies power to the motor 50 with variable voltage and frequency. In other embodiments, the motor 50 may be directly powered by AC or direct current (DC) power. The motor 50 may include any type of electric motor that can be powered by a VSD or directly by AC or DC power, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor. It should be noted that the motor 50 and / or the VSD 52 may be considered part of the compressor 32. That is, since the compressor 32 is described in this disclosure as not receiving power during natural cooling mode, it should be understood that the motor 50 and / or VSD 52 may not receive power. However, other components of the compressor 32 (e.g., magnetic bearings configured to levitate the rotor of the compressor 32) may receive power in natural cooling mode.

[0036] During normal operation, compressor 32 compresses refrigerant vapor and delivers it to condenser 34 via a discharge passage. The refrigerant vapor delivered by compressor 32 to condenser 34 can transfer heat to a cooling fluid (e.g., water or air) in condenser 34. Due to heat transfer with the cooling fluid, the refrigerant vapor can condense into liquid refrigerant in condenser 34. The liquid refrigerant from condenser 34 can flow through expansion device 36 to evaporator 38. In the embodiment shown in FIG. 3, condenser 34 is water-cooled and includes a tube bundle 54 connected to a cooling tower 56 that supplies cooling fluid to condenser 34.

[0037] The liquid refrigerant delivered to evaporator 38 can absorb heat from a conditioning fluid, which is then delivered to load 62 (e.g., building 12 of FIG. 1). That is, the conditioning fluid can be cooled by refrigerant in evaporator 38 and then used in building 12 of FIG. 1 to regulate the airflow provided for regulating the space within building 12. The liquid refrigerant in evaporator 38 may undergo a phase change from liquid refrigerant to refrigerant vapor. As shown in the embodiment illustrated in FIG. 3, evaporator 38 may include a tube bundle 58 having a supply line 60S and a return line 60R connected to the cooling load 62. Cooling fluid (e.g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable fluid) enters evaporator 38 via return line 60R and exits evaporator 38 via supply line 60S. Evaporator 38 can reduce the temperature of the cooling fluid in tube bundle 58 by heat transfer with the refrigerant. The tube bundle 58 in the evaporator 38 may include multiple tubes and / or multiple tube bundles. In any case, vaporized refrigerant leaves the evaporator 38 and flows back to the compressor 32 via a suction line to complete the cycle.

[0038] As previously described, the vapor compression system 14 can operate in a natural cooling mode under certain conditions, such as low ambient temperatures. For example, when the ambient temperature is below a temperature threshold, when the cooling fluid associated with the cooling tower 56 is below a temperature threshold, or when the refrigerant circulating through the vapor compression system 14 is below a temperature threshold, the vapor compression system 14 may be able to provide sufficient cooling capacity without powering the compressor 32 (or in other words, the motor 50 and / or VSD 52 of the compressor 32). According to the present embodiment, the compressor 32 may include a centrifugal compressor with a suspended rotor. The rotor may be suspended via one or more magnetic bearings or via one or more rolling element bearings in an oil-free system. Additionally, the variable geometry diffuser (VGD), pre-rotating vane (PRV), and / or expansion device 36 of the compressor 32 may be set to be in a fully open position in response to the activation of the natural cooling mode. The suspended rotor, the open VGD, the open PRV, and / or the open expansion device 36 may allow the impeller of the compressor 32 to rotate freely (although without power) in response to receiving refrigerant during the natural cooling mode. In some implementations, the expansion valve 36 can be throttled during natural cooling mode to maintain the condenser level, thereby increasing the available hydraulic head and reducing immersion losses in the evaporator 38. The condenser level can be detected by a sensor 121 (FIG. 6) communicatively connected to the controller 40, and the controller 40 can operate the throttling of the expansion devices(s) 36, 66 based on the level in the condenser 34.

[0039] Compared to conventional implementations with compressor bypass features, by allowing refrigerant to pass through the compressor 32 during natural cooling mode and enabling the rotor of the compressor 32 to rotate freely in response to receiving refrigerant during natural cooling mode, the number of parts, complexity, and / or cost of the vapor compression system 14 (e.g., cooler) can be reduced. For example, the compressor bypass valve or circuit included in conventional systems can be eliminated. Furthermore, the number of parts, complexity, and / or cost of the vapor compression system 14 can be reduced without causing significant pressure loss in the compressor 32 during natural cooling mode.

[0040] Figure 4 is a schematic diagram of an embodiment of the vapor compression system 14, which has an intermediate loop 64 connected between the condenser 34 and the expansion device 36. The intermediate loop 64 may have an inlet line 68 that is directly fluidly connected to the condenser 34. In other embodiments, the inlet line 68 may be indirectly fluidly connected to the condenser 34. As shown in the embodiment of Figure 4, the inlet line 68 includes a first expansion device 66 located upstream of the intermediate container 70. In some embodiments, the intermediate container 70 may be a flash tank (e.g., a flash intercooler). In other embodiments, the intermediate container 70 may be configured as a heat exchanger or a "surface energy saver". In the embodiment shown in Figure 4, the intermediate container 70 serves as a flash tank, and the first expansion device 66 is configured to reduce the pressure (e.g., expand) of the liquid refrigerant received from the condenser 34. During the expansion process, a portion of the liquid refrigerant may vaporize, and therefore the intermediate container 70 can be used to separate the vaporized refrigerant and liquid refrigerant received from the first expansion device 66. Additionally, because the liquid refrigerant experiences a pressure drop upon entering the intermediate container 70 (e.g., due to a rapid increase in volume upon entering the intermediate container 70), the intermediate container 70 allows the liquid refrigerant to expand further. The vaporized refrigerant in the intermediate container 70 can be drawn from the compressor 32 via the suction line 74 of the compressor 32. In other embodiments, the vaporized refrigerant in the intermediate container 70 can be drawn into an intermediate stage of the compressor 32 (e.g., not the suction stage). Due to the expansion of the refrigerant at the expansion device 66 and / or in the intermediate container 70, the liquid refrigerant collected in the intermediate container 70 can have a lower enthalpy than the liquid refrigerant leaving the condenser 34. The liquid refrigerant from the intermediate container 70 can then flow to the evaporator 38 via line 72 and the second expansion device 36.

[0041] The vapor compression system 14 of Figure 4 can operate in a normal operating mode, wherein the compressor 32 is powered (e.g., by powering the motor 50, VSD 52, and the control console 40 that controls the motor 50 and / or VSD 52) to increase the pressure and temperature of the refrigerant received by the compressor 32 from the evaporator 38 and / or intermediate container 70. As described with respect to the vapor compression system 14 of Figure 3, according to this disclosure, the vapor compression system 14 of Figure 4 can also operate in a natural cooling mode, wherein the compressor 32 is not powered, but refrigerant can still flow through it. As described in detail below with reference to Figure 5, the compressor 32 (e.g., the impeller of the compressor 32) can be configured to rotate freely in response to receiving refrigerant during the natural cooling mode.

[0042] Figure 5 is a schematic diagram of an embodiment of a portion of the vapor compression system 14 of Figure 2, showing a cross-section of a console 40 (e.g., a controller) and a portion of the compressor 32. The compressor 32 shown is a centrifugal compressor suitable for operation in the disclosed natural cooling mode, but other types of compressors can also be used with this technology.

[0043] Compressor 32 can operate in a normal operating mode, in which control console 40 supplies power to compressor 32 (e.g., via motor 50 and / or a corresponding VSD) when compressor 32 receives refrigerant at its suction side 80 (e.g., inlet). In normal operating mode, compressor 32 operates to increase the pressure and temperature of the refrigerant before delivering it to, for example, the condenser 34 of vapor compression system 14. For example, motor 50 can rotate shaft 82 of compressor 32. Shaft 82 can be coupled to impeller 84 having blades or guide vanes 86. Shaft 82 and impeller 84, and other features driven to rotate by motor 50 via shaft 82, can be collectively referred to as rotor 85 of compressor 32. During natural cooling mode, when compressor 32 receives refrigerant and rotor 85 is driven to rotate by motor 50, the rotating guide vanes 86 of impeller 84 can gradually increase the energy of the refrigerant flowing to diffuser 88 of compressor 32. Diffuser 88 converts the kinetic energy of refrigerant into pressure by reducing the refrigerant velocity. For example, the diffuser 88 shown is a variable geometry diffuser (VGD) with a diffuser ring 90, which can be controlled via a control console 40 to open or restrict the refrigerant flow path through the diffuser 88 to varying degrees based on the desired operating parameters and / or performance of the compressor 32. The compressor 32 shown also includes pre-rotating blades 92 arranged upstream of the impeller 84 relative to the refrigerant flow 94 passing through the compressor 32. After passing through or over the pre-rotating blades 92, impeller 84, and diffuser 88, the pressurized refrigerant can accumulate in a collector 96 for subsequent distribution to downstream components of the vapor compression system, such as the condenser 34 in Figures 2 through 4.

[0044] As previously described and in accordance with this disclosure, the vapor compression system 14 can operate in a natural cooling mode, in which the compressor 32 receives refrigerant but is not powered (e.g., driven to rotate). When the vapor compression system 14 operates in natural cooling mode, the compressor 32 (e.g., impeller 84) is configured to rotate freely in response to the receipt of refrigerant. For example, the compressor 32 shown includes bearings, which may be magnetic bearings or rolling element bearings in an oil-free system. By including magnetic bearings or rolling element bearings in an oil-free system, the rotor 85 can be suspended and able to rotate freely in response to the receipt of refrigerant when the compressor 32 (e.g., the motor 50 of the compressor 32 and / or the corresponding VSD 52) is not powered by the control console 40. Additionally, when the control console 40 is activated or the natural cooling mode is operated, the control console 40 can adjust the pre-rotating blades 92 and the variable geometry diffuser 88 to the open position (e.g., the fully open position), thereby reducing or eliminating refrigerant pressure loss during operation of the vapor compression system 14 in natural cooling mode.

[0045] Figure 6 is a schematic diagram of an embodiment of the vapor compression system 14 of Figure 2. In the illustrated embodiment, the vapor compression system 14 includes features similar to those presented in Figure 4, but without an intermediate container. However, the vapor compression system 14 in Figure 6 also includes a liquid pump 116 disposed between the condenser 34 and the evaporator 38, and a hot gas bypass valve 114 (HGBV). Additionally, the evaporator 38 in Figure 6 is a falling film evaporator, and the vapor compression system 14 (i.e., the cooler) may include a bypass valve 110 operable to direct refrigerant to different portions of the evaporator 38 (e.g., the falling film evaporator) depending on operating conditions.

[0046] As previously described, refrigerant can be directed to evaporator 38 (e.g., a falling film evaporator) and can be used to cool conditioning fluid directed to and from load 62. Load 62 can be, for example, one or more air handling units (AHUs) that utilize cooled conditioning fluid to cool the airflow supplied to the conditioned space. Typically, evaporator 38 (e.g., a falling film evaporator) can be configured to receive refrigerant toward the top of evaporator 38, for example at upper inlet 101, such that the refrigerant is gravity-fed downwards from upper inlet 101 through evaporator 38. During certain conditions, the refrigerant pressure may be such that the refrigerant cannot move to the top of evaporator 38, or that if the refrigerant is moved to the top of evaporator 38 to operate evaporator 38 as a falling film evaporator, system 14 will experience problems (e.g., pressure loss, cooling capacity, etc.). During such conditions, falling film bypass valve 110 can be operated (e.g., opened) to allow refrigerant to travel toward the bottom of evaporator 38, for example, into lower inlet 103. For example, console 40 can instruct (e.g., via a wired connection or a wireless connection via network 115) to open and / or close the falling film bypass valve 110, for example, based on the refrigerant pressure detected by sensor 123 communicatively connected to console 40. Therefore, when the falling film bypass valve 110 is actuated to divert refrigerant from upper inlet 101 to lower inlet 103, evaporator 38 can operate as an overflow evaporator. It should be noted that in another embodiment, the position of the falling film bypass valve 110 may differ from that shown and may be closed to divert refrigerant from upper inlet 101 to lower inlet 103 of evaporator 38.

[0047] As previously described, the vapor compression system 14 may also include an HGBV 114. The HGBV 114 can be operated (e.g., opened) to allow vapor refrigerant to flow from the evaporator 38 into and into the condenser 34. Opening the HGBV 114 to allow vapor refrigerant to flow into the condenser 34 can increase the cumulative refrigerant flow path area or size of the vapor compression system 14 and improve the cooling capacity of the vapor compression system 14. In some embodiments, the HGBV 114 may open in response to the activation of a natural cooling mode.

[0048] Additionally, in some embodiments, the vapor compression system 14 may include a liquid pump 116, which can be operated (e.g., powered) during natural cooling mode to move liquid refrigerant from the condenser 34 to the evaporator 38. Pump 116 eliminates the need for a falling film bypass valve 110 and a lower inlet 103, as well as associated piping. However, in some embodiments, the vapor compression system 14 may operate as a thermosiphon, where natural convection causes the heated liquid refrigerant to move upward within the vapor compression system 14 as it is replaced by a cooler liquid refrigerant flowing downward via gravity.

[0049] In embodiments without pump 116, the falling film bypass valve 110 and its corresponding features may be preferred. If the condenser 34 is physically lower than the upper inlet 101, making it impossible for gravity to provide sufficient liquid refrigerant flow, the falling film bypass valve 110 may be required for natural cooling operation.

[0050] Other features can be combined with and / or used in conjunction with the vapor compression system 14 (and corresponding natural cooling operation) described herein. For example, the capability of the vapor compression system 14 can be modulated based on feedback regarding the temperature of the regulating fluid. More specifically, the console 40 can monitor the temperature of the regulated fluid as it exits the evaporator 38. The sensor 120 can detect the temperature of the regulated fluid as it exits the evaporator 38 and can be communicatively coupled to the console 40, which periodically receives temperature data and modulates the capability of the vapor compression system 14 based on the detected temperature. It should be noted that the sensor 120 or a separate sensor can also be used to determine when to activate the natural cooling operation. For example, the natural cooling operation can be activated during cooler seasons (e.g., autumn, winter, and / or spring) based on the ambient temperature detected by the sensor and / or based on the temperature of the cooling fluid detected by the sensor. As previously described, the vapor compression system 14 may be able to operate with a capability suitable for meeting cooling needs during relatively cold seasons without powering and driving the compressor 32 to rotate. The console 40 may include temperature thresholds stored in memory 46. This temperature threshold can be related to: the temperature of the fluid leaving the evaporator 38 (e.g., detected by sensor 120), the ambient air temperature, the temperature of the cooling fluid being guided into and out of the cooling tower 56, the refrigerant temperature (detected at a selected location along the vapor compression system 14), or a combination thereof. When the detected temperature corresponding to the temperature threshold is lower than the temperature threshold, the control panel 40 can activate natural cooling operation.

[0051] In addition to these features, under certain conditions, motor 50 can operate as a generator during natural cooling mode. For example, while console 40 can terminate the supply of power to motor 50 (or VSD 52, which can be considered part of motor 50 and / or compressor 32) during natural cooling mode, the kinetic energy of compressor 32, which rotates freely during natural cooling mode (e.g., caused by the passive refrigerant flow guided through it), can be harvested and used to generate energy via motor 50 or a separate generator connected to rotor 85 of compressor 32. Accordingly, motor 50 can be connected to load 122 via VSD 52 (e.g., electrical system, battery, capacitor, common grid, etc.), and load 122 can utilize or store the electrical energy generated in or by motor 50 during natural cooling mode.

[0052] Additionally, as previously described, the expansion device 36 (or some other expansion device of system 14) can be throttled during natural cooling mode to maintain the condenser level, thereby increasing the available hydraulic head and reducing immersion losses in the evaporator 38. The condenser level can be detected by a sensor 121 connected to the controller 40 via wired or wireless communication, and the controller 40 can operate the throttling of the expansion device 36 based on the level in the condenser 34.

[0053] Figure 7 is a process flow diagram illustrating an implementation of the operation method 200 of the vapor compression system 14 of Figure 2. Method 200 includes: operating the vapor compression system 14 in a normal operating mode (step 202), in which the compressor 32 (or its motor 50 or VSD 52) is powered, receives refrigerant, and increases the temperature and pressure of the refrigerant before it is delivered to the condenser 34.

[0054] Method 200 further includes detecting the actual temperature of the fluid associated with the vapor compression system 14. As previously described, the fluid may be ambient air (e.g., used by cooling tower 56 to cool a fluid that subsequently extracts heat from a refrigerant in condenser 34), a fluid flowing between cooling tower 56 and condenser 34, a fluid flowing between evaporator 38 and load 62 (e.g., air handling unit), or refrigerant. As described below, the detected actual temperature of the fluid can be used to determine whether operation in natural cooling mode is desired. However, in some embodiments, the vapor compression system 14 may be manually operated to activate natural cooling mode.

[0055] The illustrated method 200 also includes comparing the actual temperature discussed above with respect to step 204 with a threshold temperature (step 206). For example, as shown, method 200 includes: determining (step 208) whether the actual temperature is less than a threshold temperature. If the actual temperature is not less than the threshold temperature (step 210), normal operation of the vapor compression system 14 can continue. If the actual temperature is less than the threshold temperature (step 212), then natural cooling mode is activated (step 214).

[0056] As previously described, in natural cooling mode, power to compressor 32 (e.g., to motor 50 or VSD 52 of compressor 32) is terminated. However, compressor 32 is still configured to receive and guide refrigerant through it. In other words, in natural cooling mode, the refrigerant flow does not bypass compressor 32. Compressor 32 is configured to rotate freely during natural cooling mode (e.g., in response to receiving refrigerant). To improve efficiency during natural cooling mode, compressor 32 may include features capable of reducing pressure losses that compressor 32 might otherwise cause during the currently disclosed natural cooling mode. For example, the VGD (e.g., diffuser 88) of compressor 32 may be set to an open (e.g., fully open) position, the PRV 92 of compressor 32 may be set to an open (e.g., fully open) position, the expansion valve (e.g., valve 36) of vapor compression system 14 may be set to an open (e.g., fully open) position, or any combination thereof. However, in some embodiments, the expansion valve 36 can be throttled during natural cooling mode to maintain the condenser level, thereby increasing the available hydraulic head and reducing immersion losses in the evaporator 38. Additionally, in some embodiments, a falling film bypass valve 110 can be included and operated to divert refrigerant from the upper inlet 101 to the lower inlet 103 in response to certain operating conditions, as detailed in Figure 6. Furthermore, an HGBV 114 can be included and operated to allow vaporized refrigerant to flow from the evaporator 38 to the condenser 34 during natural cooling mode. Finally, the motor 50 can be operated as a generator in natural cooling mode to convert the kinetic energy of the freely rotating compressor 32 into electrical energy.

[0057] Although only certain features of this embodiment have been shown and described herein, many modifications and changes will occur to those skilled in the art. Therefore, it should be understood that the appended claims are intended to cover all such modifications and changes falling within the true spirit of this disclosure. Furthermore, it should be understood that certain elements of the disclosed embodiments can be combined or interchanged with each other.

[0058] The techniques presented and claimed herein have been referenced and applied to material objects and concrete examples of practical nature that clearly improve the technical field and are therefore not abstract, intangible, or purely theoretical. Furthermore, if any claim appended to this specification contains one or more elements referred to as "means for [performing] [function]" or "steps for [performing] [function]", it is intended to be interpreted in accordance with 35 USC 112(f). However, for any claim containing elements referred to in any other way, it is intended not to be interpreted in accordance with 35 USC 112(f).

[0059] 10: System 12: Buildings 14: Vapor compression system 16: Boiler 18: Air return duct 20: Air supply duct 22: Air Handling Unit 24: Catheter 32: Compressor 34: Condenser 36: Device 38: Evaporator 40: Console 42: Converter 44: Microprocessor 46: Non-volatile memory 48: Interface panel 50: Motor 52: Variable speed drive unit 54: Tubes 56: Cooling Tower 58: Tubes 60: Supply pipeline 62: Load 64: Intermediate circuit 66: First expansion device 68: Inlet Pipeline 70: Intermediate container 72: Pipeline 74: Suction tubing 80: Suction side 82: Axis 84: Impeller 85: Rotor 86:Guide film 88: Diffuser 90: Diffuser ring 92: Pre-rotating blade 94: Flow 96: Collector 101:Upper entrance 103:Lower entrance 110: Bypass valve 114: Hot gas bypass valve 115: Internet 116: Liquid pump 120: Sensor 121: Sensor 122: Load 123: Sensor 200: Method 202: Steps 206: Steps 204: Steps 208: Steps 210: Steps 212: Steps 214: Steps

Claims

1. A heating, ventilation, air conditioning and / or refrigeration (HVAC&R) system, comprising: A vapor compression system including an evaporator, a condenser, and a compressor, wherein the compressor includes an impeller and is configured to guide refrigerant through the impeller in a normal operating mode and a natural cooling mode of the vapor compression system; and a controller configured to supply power to the motor of the compressor in the normal operating mode and to suspend the supply of power to the motor of the compressor in the natural cooling mode.

2. The HVAC&R system as described in claim 1, wherein, The compressor includes a suspended rotor.

3. The HVAC&R system as described in claim 2, wherein, The compressor includes a magnetic bearing, through which the suspended rotor is suspended, and the controller is configured to supply additional power to the magnetic bearing in the natural cooling mode.

4. The HVAC&R system as described in claim 1, wherein, The compressor is configured to receive a portion of the refrigerant vapor from the evaporator in both the normal operating mode and the natural cooling mode.

5. The HVAC&R system as described in claim 2, wherein, The compressor includes rolling element bearings, and the suspended rotor is suspended via the rolling element bearings.

6. The HVAC&R system as described in claim 1, wherein, The compressor includes: a variable geometry diffuser (VGD), and the controller is configured to indicate the VGD to a fully open position in response to the activation of the natural cooling mode; or a pre-rotating vane (PRV), and the controller is configured to indicate the PRV to a fully open position in response to the activation of the natural cooling mode.

7. The HVAC&R system as described in claim 1, wherein, The compressor includes a variable speed drive (VSD) configured to supply power to the motor, and the controller is configured to control the VSD to supply power to the motor in the normal operating mode and to control the VSD to suspend supplying power to the motor in the natural cooling mode.

8. The HVAC&R system as claimed in claim 1, comprising a temperature sensor configured to detect the temperature of the refrigerant, the temperature of a conditioning fluid directed through the evaporator, the temperature of a cooling fluid directed through the condenser, or the temperature of ambient air, wherein, The controller is configured to receive data indicating the temperature from the temperature sensor, and wherein the controller is configured to activate the natural cooling mode in response to determining that the temperature is below a temperature threshold.

9. The HVAC&R system as described in claim 1, including a refrigerant pump, wherein, The controller is configured to activate the refrigerant pump in response to the opening of the natural cooling mode, so that the refrigerant pump forces at least the liquid phase of the refrigerant through the vapor compression system.

10. The HVAC&R system as described in claim 1, wherein, The motor is configured to convert the kinetic energy of the compressor's rotor into electrical energy during this natural cooling mode.

11. A method for operating a heating, ventilation, air conditioning and / or refrigeration (HVAC&R) system, comprising: In response to the normal operating mode of the HVAC&R system, power is supplied to the motor of the compressor of the vapor compression system, such that the compressor is driven by the motor and the refrigerant is biased between the evaporator and the condenser of the vapor compression system; in response to the natural cooling mode of the HVAC&R system, power supply to the compressor of the vapor compression system is stopped; and the rotor of the compressor is suspended as the refrigerant passes through the impeller of the compressor during the natural cooling mode.

12. The method as described in claim 11, including suspending the compressor rotor via a magnetic bearing.

13. The method as described in claim 11, comprising: The compressor receives a portion of the refrigerant vapor from the evaporator in both the normal operating mode and the natural cooling mode.

14. The method as described in claim 11, including suspending the compressor rotor via a rolling element bearing.

15. The method as described in claim 11, comprising converting the kinetic energy of the compressor rotor into electrical energy.

16. A cooler system, comprising: A compressor configured to circulate refrigerant through a refrigerant circuit during a normal operating mode of the cooler system, and configured to receive a vapor portion of the refrigerant from an evaporator during both the normal operating mode and a natural cooling mode of the cooler system; and a motor for the compressor. And a controller configured to supply power to the motor of the compressor in response to the normal operating mode of the cooler system, and to stop supplying power to the motor of the compressor in response to the natural cooling mode of the cooler system.

17. The cooler system as described in claim 16, wherein, The compressor includes a rotor that is suspended by a magnetic bearing or a rolling element bearing.

18. The cooler system as claimed in claim 16, wherein the compressor includes an impeller and the compressor is configured to guide the refrigerant through the impeller in both the normal operating mode and the natural cooling mode.

19. The cooler system as claimed in claim 16, comprising a temperature sensor configured to detect the temperature of the refrigerant, the temperature of a conditioning fluid directed through the evaporator, the temperature of a cooling fluid directed through the condenser in the refrigerant circuit, or the temperature of ambient air, wherein, The controller is configured to receive data indicating the temperature from the temperature sensor, and wherein the controller is configured to activate the natural cooling mode in response to determining that the temperature is below a temperature threshold.

20. The cooler system as described in claim 16, wherein, The motor is configured to convert the kinetic energy of the compressor's rotor into electrical energy during this natural cooling mode.

Images