COMPRESSOR OIL INJECTION COOLING

[0001] This disclosure generally relates to operation of a compressor of a working fluid circuit. More specifically, this disclosure relates to injection and supplying of oil in a compressor of a working fluid circuit.

[0002] Heating, ventilation, air conditioning, and refrigeration (HVACR) systems are generally used to heat, cool, and/or ventilate an enclosed space (e.g., an interior space of a commercial building or a residential building, an interior space of a climate controlled transport unit, or the like). A HVACR system includes a working fluid circuit for providing cooled or heated air to the area. The working fluid circuit utilizes a working fluid to cool or heat the air directly or indirectly. Typically, a working fluid circuit includes a compressor for compressing the working fluid, and the compressor utilizes oil for lubricating moving parts with the compressor. The oil mixes into the working fluid within the compressor. The oil can then be separated from the working fluid and provided back to the moving parts.

[0003] A transport climate control system (TCCS) is one example of an HVACR that can include, for example, a transport refrigeration system (TRS) and/or a heating, ventilation, and air conditioning (HVAC) system. A TRS is generally used to control an environmental condition (e.g., temperature, humidity, air quality, and the like) within a cargo space of a transport unit (e.g., a truck, a container (such as a container on a flat car, an intermodal container, etc.), a box car, a semi-tractor, a bus, or other similar transport unit). The TRS can maintain environmental condition(s) of the cargo space to maintain cargo (e.g., produce, frozen foods, pharmaceuticals, etc.). In some embodiments, the transport unit can include an HVAC system to control a climate within a passenger space of the vehicle.

[0004] This disclosure generally relates to operation of a compressor of a working fluid circuit. More specifically, this disclosure relates to injection and supplying of oil in a compressor of a working fluid circuit.

[0005] It will be appreciated that A2L refrigerants can have a higher heat of compression than conventional refrigerants. The higher heat of compression can cause higher discharge temperatures that negatively impact materials in the compressor. Accordingly, cooling the compressor may be required to prevent damage to the compressor. The embodiments described herein can provide cooling to the compressor without negatively impacting a cooling capacity of the working fluid circuit.

[0006] The embodiments described herein can pump away oil from a sump of a compressor towards a cooling device such as, for example, a radiator. The oil can then be returned to the sump or returned to the compressor's oil lubrication system when supplied at an appropriate pressure. A pressure regulator can be used to maintain the appropriate pressure.

[0007] In some embodiments, the oil can be introduced to a compressor suction plenum located, for example, near a suction port of the compressor, near an inlet to a cylinder, etc.

[0008] In some embodiments, a controller can determine when oil is injected to the compressor. The controller can also direct different oil flows during different operating conditions of the working fluid circuit.

[0009] In some embodiments, oil can be cooled and introduced to the compressor suction plenum to reduce a discharge temperature without affecting a mass flow or an oil circulation within the working fluid circuit.

[0010] In some embodiments, an oil separator can be added to the compressor of the working fluid circuit to reduce oil circulation from the added oil injection.

[0011] In an embodiment, a working fluid circuit includes a compressor, an oil sump, and an oil injection system. The compressor includes one or more compression chambers configured to compress working fluid. The oil sump is configured to separate oil in the working fluid. The oil injection system with an oil pathway connected to the oil sump and to a suction pathway of the compressor. The oil pathway is configured to inject the oil from the oil sump into the suction pathway to cool the working fluid in the suction pathway flowing to the one or more compression chambers.

[0012] In an embodiment, a method is directed to controlling a working fluid circuit that includes a compressor. The method includes suctioning a working fluid into the compressor, compressing the working fluid into a compressed working fluid within the compressor, and discharging the working fluid from the compressor. The method also includes separating, via an oil sump, oil from the working fluid, and supplying, via an oil pathway, the oil from the oil sump into a suction pathway of the compressor. The supplying of the oil includes injecting the oil from the oil pathway into the suction pathway and liberating gaseous refrigerant dissolved in the oil from the oil to provide cooling to the working fluid in the suction pathway.

[0016] Like numbers represent like features.

[0017] This disclosure generally relates to operation of a compressor of a working fluid circuit. More specifically, this disclosure relates to injection and supplying of oil in a compressor of a working fluid circuit.

[0018] A heating, ventilation, air conditioning, and refrigeration (“HVACR”) system is generally configured to heat and/or cool an enclosed space (e.g., an interior space of a commercial or residential building, an interior space of a climate controlled transport unit, or the like). The HVACR system includes a working fluid circuit that includes a compressor and a working fluid that circulates through the working fluid circuit. The working fluid is utilized to heat or cool a process fluid (e.g., air, water and/or glycol, or the like).

[0019] The compressor includes components (e.g., driveshaft, scroll, rotor, screws, impeller, bearing(s) and the like) that move relative to the housing of the compressor to compress the working fluid. The working fluid can include refrigerant and oil. The oil can be separated from the working fluid and the separated oil is then circulated back to one or more moving part(s) of the compressor (e.g., to the bearing(s), driveshaft, etc.). The oil can be stored in an oil sump (e.g., oil sump within the compressor, oil sump of an oil separator, etc.) until it is supplied back to the moving part(s) of the compressor.

[0020] A working fluid can include a refrigerant/refrigerant blend. ASHRAE Standard 34 (e.g., ASHRAE 34-2019) provides guidelines for determining the safety classification of a refrigerant or a refrigerant blend. Generally nonflammable refrigerants or blends are classified as Class 1, while flammable refrigerants or blends are classified as Class 2 and highly flammable refrigerants or blends are classified as Class 3. Lower toxicity refrigerants or blends are classified “A”, while higher toxicity refrigerants or blends are classified “B”. Previously, many A1 refrigerants (e.g., R22, R134a, R410A, R125A, etc.) have been used due to generally being safe and providing good performance. Presently, most to all of the A1 refrigerants currently being used have been found to have a high global warming potential (“GWP”) and therefore significantly contribute to global warming when leaked into the environment. A variety of refrigerant and refrigerant blends (e.g., R32, R1234yf, R1234ze(E), R1132a, R1123, R454A, etc.) are mildly flammable and classified as A2L refrigerants. Many of the A2L refrigerants provide a desired lower GWP while generally providing performance (e.g., capacity, temperature glide, operating pressures, etc.) comparable to current A1 refrigerants. Refrigerant and refrigerant blends classified as A3 refrigerants (e.g., R290, etc.) can provide a desired lower GWP while providing adequate performance relative to current A1 refrigerants, while being selectively employed due to their high flammability. However, many flammable refrigerants (e.g., A2, A2L, or A3 refrigerants) can have a greater heat of compression which results in increased discharge temperature of the compressor. In particular, many A2L refrigerants have shown to have such greater heats of compression. Some A1 refrigerants (e.g., R449A) can also have a relatively higher heat of compression. Such increased discharge temperatures may cause damage to the compressor.

[0021] The embodiments described herein are generally directed to supplying oil to the suction of a compressor in a working fluid circuit to provide cooling and decrease a discharge temperature from the compressor. The working fluid circuit includes an oil sump containing oil separated from a working fluid and an oil injection system configured to supply the separated oil into the suction pathway of the compressor to provide cooling of the working fluid. The oil contains dissolved gaseous refrigerant that is liberated from the oil during injection of the oil into the suction pathway, which provides the cooling of the working fluid that is compressed by the compressor. This can advantageously achieve a relatively decreased temperature of the compressed working fluid from the compressor, when using a refrigerant/refrigerant blend with a relatively higher heat of compression, such as for many A2L refrigerants. For example, the oil injection can be used to reduced and/or eliminate the increase in the discharge temperature caused by using a refrigerant/refrigerants with a higher heat of compression (e.g., by using an A2L refrigerant).

[0022] FIG. 1 is a schematic diagram of a working fluid circuit 2 of a HVACR system 1, according to an embodiment. The working fluid circuit 2 includes a compressor 10, a condenser 50, an expansion device 52, and an evaporator 54. Dotted lines are provided in the Figures to indicate fluid flows through some components (e.g., compressor 10, condenser 50, evaporator 54) for clarity, and should be understood as not specifying a specific route within each component.

[0023] The components of the working fluid circuit 2 are fluidly connected. The working fluid circuit 2 can be configured as a climate control system (e.g., a transport climate control system, a fluid chiller of an HVACR, an air conditioning system, or the like) that can be operated in a cooling mode, and/or the working fluid circuit 2 can be configured to operate as a heat pump system that can run in a cooling mode and a heating mode. A working fluid flows through the working fluid circuit 2.

[0024] The working fluid circuit 2 applies known principles of gas compression and heat transfer. The working fluid circuit can be configured to heat or cool a process fluid (e.g., water, air, or the like). In an embodiment, the working fluid circuit 2 may represent a chiller that cools a process fluid such as water or the like. In an embodiment, the working fluid circuit 2 may represent an air conditioner and/or a heat pump that cools and/or heats a process fluid such as air, water, or the like.

[0025] The compressor 10 includes a suction inlet 12, a discharge outlet 14, and a compression mechanism 16 forming one or more compression pockets. During the operation of the working fluid circuit 2, a working fluid flows into the compressor 10 (via the suction inlet 12) from the evaporator 54 in a gaseous state at a relatively lower pressure. The compressor 10 includes a suction pathway 18 that includes the suction inlet 12. The working fluid discharged from the evaporator 54 flows through the suction pathway 18 into the compressor 10 and to the compression mechanism 16 (e.g., supplies the working fluid to the compression pocket(s) of the compression mechanism).

[0026] The compressor 10 compresses the gas into a high pressure state, which also heats the gas. After being compressed, the relatively higher pressure and higher temperature gas flows from the compressor 10 to the condenser 50. In addition to the working fluid flowing through the condenser 50, a first process fluid PF₁ (e.g., external air, external water, chiller water, or the like) also separately flows through the condenser 50. The first process fluid absorbs heat from the working fluid as the first process fluid PF₁ flows through the condenser 50, which cools the working fluid as it flows through the condenser.

[0027] The working fluid condenses to liquid and then flows from the condenser 50 into the expansion device 30. The expansion device 30 allows the working fluid to expand, which converts the working fluid to a mixed vapor and liquid state. An “expansion device” as described herein may also be referred to as an expander. In an embodiment, the expander may be an expansion valve, expansion plate, expansion vessel, orifice, or the like, or other such types of expansion mechanisms. It should be appreciated that the expander may be any type of expander used in the field for expanding a working fluid to cause the working fluid to decrease in temperature. The relatively lower temperature, vapor/liquid working fluid then flows into the evaporator 54. A second process fluid PF₂ (e.g., air, water, or the like) also flows through the evaporator 54. The working fluid absorbs heat from the second process fluid PF₂ as it flows through the evaporator 54, which cools the second process fluid PF₂ as it flows through the evaporator 54. As the working fluid absorbs heat, the working fluid evaporates to vapor. The working fluid then returns to the compressor 10 from the evaporator 54. The above-described process continues while the working fluid circuit 2 is operated, for example, in a cooling mode.

[0028] It should be appreciated that the working fluid circuit 2 in other embodiments can be modified to include additional components. For example, the working fluid circuit 2 in an embodiment can include an economizer heat exchanger, one or more flow control devices, a receiver tank, a dryer, a suction-liquid heat exchanger, or the like. As shown in FIG. 1, the working fluid circuit 2 in an embodiment may include an oil separator 60 connected to discharge outlet 14 of the compressor 10. The oil separator 60 can be configured to separate oil mixed with the refrigerant in the working fluid. The separated oil can then be returned from the oil separator 60 back to the compressor 10 to lubricate the moving parts (e.g., bearing(s), drive shaft, etc.)

[0029] The working fluid circuit 2 can include a controller 90 for controlling operation of working fluid circuit 2 and its components. In an embodiment, the controller 90 may be the controller of the HVACR system 1. In an embodiment, the controller 90 may be the controller of the compressor 10. In an embodiment, the controller 90 includes memory (not shown) for storing information and a processor (not shown). However, it should be appreciated that a “controller” as shown in the Figures and described herein may include multiple discrete or interconnected components that include the memory and a processor in an embodiment.

[0030] The Figures include dashed-dotted lines indicate electrical communication lines. For example, a dashed-dotted line extends from the controller 90 to the compressor 10 as the controller 90 can be configured to control operation the compressor 10 (e.g., speed of the compressor when adjustable, discharge pressure of the compressor 10 when adjustable, and the like). For example, a dashed-dotted line extends from the controller 90 to the expansion device 52 as the expansion device 52 in an embodiment may be an electronic expansion valve operated/controlled by a controller 90 (e.g., controlled based on detections by temperature and/or pressure sensor(s) (not shown) in the working fluid circuit). The Figures include short-dashed lines to indicate different features in different embodiments as discussed. However, it should be appreciated that the short-dashed lines as used herein are not to be considered as limiting which features that may be different in different embodiments. The Figures also include long dashed lines to indicate feature that are obscured in a given view.

[0031] FIG. 2 is a schematic diagram of an embodiment of an oil injection system 140 for a compressor 110. The compressor 110 operates to compress working fluid in a working fluid circuit 102 of an HVACR system 101. The working fluid circuit 102 includes the oil injection system 140 to provide cooling to the compressor 110. For example, the compressor 110 in an embodiment may be the compressor 10 in the working fluid circuit 5 of the HVACR system 1 in FIG. 1. The working fluid circuit 102 may include a controller 190 for controlling operation of working fluid circuit 102 and its components. The working fluid circuit 102 may have features as similarly discussed for the controller 90 in FIG. 1.

[0032] The compressor 110 includes a suction inlet 112, a discharge outlet 114, and one or more compression chambers 120A, 120B. The suction inlet 112 is fluidly connected to the discharge outlet 114 via the compressor chamber(s) 120. The compression chamber(s) 120 compress the working fluid. Working fluid f_I (i.e., working fluid to be compressed) flows into the compressor 110 through the suction inlet 112 (e.g., is suctioned into the compressor 110 through the suction inlet 112). The working fluid flows from the suction inlet 112 into the compression chamber(s) 120 and is compressed within the compression chambers 120. The compressed working fluid f_D is then discharged from the compression chambers 120 out of the compressor 110 via the discharge outlet 114.

[0033] The compressor 110 has a suction pathway 118 that includes the suction inlet 112. For example, the suction pathway 118 can extend from the evaporator (e.g., see suction pathway 18 extending from evaporator 18 in FIG. 1) to the compression pockets 120 of the compressor 110. As shown in FIG. 2, the compressor 110 includes a suction plenum 122 that fluidly connects the suction inlet 112 to each of the one or more compression chambers 120. As shown in FIG. 2, the suction pathway 118 also includes the suction plenum 122.

[0034] As shown in FIG. 2, the compressor 120 can include a plurality of compression chambers 120. In illustrated embodiment, the compressor 120 is a reciprocal compressor. It should be appreciated that the compressor 120 may be a different type of compressor. For example, the compressor 120 may be, but is not limited to, a centrifugal compressor, a rotary compressor, etc.

[0035] The working fluid circuit 102 includes an oil sump 154A/154B. The oil sump contains oil 152 separated from the working fluid. The oil is used to lubricate moving parts of the compressor 110. The oil is supplied from the oil sump 154A/154B to one or more moving parts of the compressor 110 to lubricate said moving part(s). Such moving parts can include one or more of, but are not limited to, bearing(s) (e.g., driveshaft bearing 124, etc.), a driveshaft, piston(s), etc. of the compressor 110.

[0036] In an embodiment, the oil sump 154A may be disposed within the compressor 110. For example, the oil separates from the working fluid within the compressor 110 and flows to the oil sump 154A. For sump 154A, the oil 152 is internally supplied within the compressor to the moving part(s) of the compressor 110. In one example, the compressor 110 may include an oil pump (not shown) configured to provide the oil 152 from the oil sump 154A to the moving part(s) of the compressor 110.

[0037] In an embodiment, the working fluid circuit 110 can optionally include an oil separator 150 connected to the discharge outlet 114 of the compressor 110. For example, the oil separator 150B can be an external oil separator that fluidly connects the discharge outlet 114 of the compressor 110 to the condenser (e.g., condenser 50 in FIG. 1). The separated oil is supplied back to the compressor 110, which is then directed within the compressor 150A to the moving part(s) of the compressor 110. In an embodiment, the oil separator 150B may include an oil sump 154B. In an embodiment, oil separator 150B may be configured to direct the separated to an oil sump 154A disposed within the compressor 110. The oil is then directed from the internal oil sump 154A to the moving part(s) from the oil sump.

[0038] The oil injection system 140 of the working fluid circuit 102 includes an oil pathway 142. The oil pathway 142 connects to the oil sump 154A/154B and the suction pathway 118. As shown in FIG. 2, the oil pathway 142 fluidly connects the oil sump 154A/154B to the suction pathway 118. The oil pathway 142 has an inlet 144 and an outlet 146. The inlet 144 of the oil pathway 142 is connected to the oil sump 154A/154B. The outlet 146 of the oil pathway 142 is connected to the suction pathway 118. The oil pathway 142 extends from the oil sump 154A/154B to the suction pathway 118. As shown in FIG. 2, at least part of the oil pathway 142 can extend outside the compressor 110 (e.g., outside a housing of the compressor 110).

[0039] The oil pathway 142 is configured to inject oil 152 from the oil sump 154A/154B into the suction pathway 118. In particular, the oil pathway 142 injects a portion of the oil f_O in the oil sump 154A/154B into the suction pathway 118. The injection of the oil f_O provides cooling to the working fluid in the suction pathway 118. In an embodiment, the working fluid circuit 102 has an oil circulation rate of 10% or less (i.e., while the oil pathway 142 is injecting the oil). In an embodiment, the working fluid circuit 102 has an oil circulation rate of 5% or less. Oil circulation rate is based on the mass percentage of the oil in the working fluid (i.e., OCR=(mass of oil in the working fluid/total mass of the working fluid)*100). For example, the oil circulation rate may be measured at or downstream of the discharge of the compressor 110 (e.g., at discharge outlet 114, at the inlet of the oil separator 150, and an inlet of a condenser in the working fluid circuit 102 (e.g., at the inlet of the condenser 50 in FIG. 1).

[0040] In an embodiment, the oil pathway 142 may be configured to inject at or less than about 0.5 gallons per minute (GPM) of oil into the suction stream. In an embodiment, the oil pathway 142 may be configured such that about 1-22% by the volume of the oil sump 154A/154B per minute is injected into the suction pathway 118 via the oil pathway 142. For example, other portion of the oil 152 contained in the sump 154A/154B can be supplied to, for example, the moving parts of the compressor 110. In an embodiment, at or less than 20% by volume of the oil 152 in the oil sump 154A/154B per minute is injected into the suction pathway 118 via the oil pathway 142. In another embodiment, at or less than 15% by volume of the oil 152 in the oil sump 154A/154B per minute is injected into the suction pathway 118 via the oil pathway 142. In another embodiment, at or less than 10% by volume of the oil 152 in the oil sump 154A/154B per minute is injected into the suction pathway 118 via the oil pathway 142. In another embodiment, at or less than 5% by volume of the oil 152 in the oil sump 154A/154B per minute is injected into the suction pathway 118 via the oil pathway 142.

[0041] The oil pathway 142 is configured to inject the oil f_O into the suction pathway 118 at a higher pressure than the working fluid flowing through the suction pathway 118 (i.e., pressure P_O of the injected oil f_O>pressure P_S of the working fluid in the suction pathway 118). As shown in FIG. 2, the oil pathway 142 may include an oil pump 160. The oil pump 160 operates to direct the oil f_O from the oil sump 154A/154B into oil pathway 142 (e.g., suctions the oil f_O into the oil pathway 142) and through the oil pathway 142 (e.g., pumps the oil f_O through the oil pathway 142 and from the oil pathway 142 into the suction pathway 142). For example, the oil pump 160 operates to inject the oil f_O into the suction pathway 142.

[0042] As shown in FIG. 2, the oil pump 160 can be external to the compressor 110. In an embodiment, the oil pump 160 may be within the compressor 110. For example, the oil pump 160 may be an internal oil pump that is driven by the driveshaft (not shown) of the compressor 110. The internal oil pump may be configured to supply oil to both a flow of oil to the oil pathway 142 and a flow of oil to the internal moving parts of the compressor 110. In an embodiment, the oil pathway 142 may include an intermediate outlet 148 that allows for a portion of the oil suctioned into the oil pathway 142 to be discharged back into the oil sump 154A/154B. For example, the intermediate outlet 148 may be an overflow pathway for the oil pump 160.

[0043] As shown in FIG. 2, the oil pathway 142 may include a restriction 162. The restriction 162 is configured to compress the oil flowing through the oil pathway 142. The oil f_O is compressed by the restriction 142 as the oil f_O flows through the oil pathway 142. This compression of the oil f_O increases a pressure P_O of oil f_O injected into the suction pathway 118. In an embodiment, the restriction 162 may be an adjustable valve (e.g., needle valve, etc.) configured to be mostly closed during operation of the oil pathway 142. For example, the adjustable valve can be configured to be at least 80% closed while the oil pathway 142 is operating to inject oil into the suction pathway 118. For example, the adjustable valve can be configured to be at least 85% closed while the oil pathway 142 is operating to inject oil into the suction pathway 118. In an embodiment, the restriction 162 can be configured such that the pressure drop from the oil pathway 142 to the suction pathway 118 is least 10 pounds per square inch (“psi”). In an embodiment, the restriction 162 can be configured such that the pressure drop from the oil pathway 142 to the suction pathway 118 is least 20 psi. In an embodiment, the restriction 162 can be configured such that the pressure drop from the oil pathway 142 to the suction pathway 118 is at least 30 psi.

[0044] The working fluid includes refrigerant. The refrigerant in the working fluid is soluble (i.e., substantially soluble) in the oil. For example, oil 152 in the oil sump contains at least 1 wt % of gaseous refrigerant dissolved in the liquid oil. The refrigerant component of the working fluid may be a single refrigerant or a blend of refrigerants. Unless specified otherwise, the term “refrigerant” used herein refers to the entire refrigerant component in the working fluid. In an embodiment, the working fluid includes refrigerant that is a flammable refrigerant (e.g., A2 refrigerant, A2L refrigerant, A3 refrigerant). In an embodiment, the working fluid includes refrigerant that is A2L refrigerant. In an embodiment, the working fluid includes R454A refrigerant.

[0045] In an embodiment, the oil may be one or more of polyolester (“POE”) oil, polyalkylene glycol (“PAG”) oil, polyvinyl ether (“PVE”) oil, A/B oil, and mineral oil. For example, the mineral oil may be one or more of S-2630 mineral oil, S-2050 mineral oil, S-1250 mineral oil, etc. In an embodiment the oil is POE oil (e.g., Solest 35 POE, Icematic 5020 POE, etc.).

[0046] The oil f_O contains dissolved gaseous refrigerant (i.e., oil f_O includes gaseous refrigerant dissolved in liquid oil). The injection of the oil f_O into the suction pathway 118 liberates the dissolved gaseous refrigerant from the oil (i.e., the dissolved gaseous refrigerant separates from the liquid oil to form a mixture of the gaseous refrigerant and the liquid oil). For example, the pressure drop (e.g., relatively sudden pressure drop) of the injected oil f_O liberates an amount of the dissolved gaseous refrigerant from the oil f_O. The liberation of dissolved gaseous refrigerant causes cooling of the oil f_O. The expansion of the liberated gaseous refrigerant also provides cooling.

[0047] In an embodiment, a higher pressure P_O of the injected oil f_O may be provided by one or more of the oil pump 160 and/or the restriction 162. In an embodiment, the oil f_O in the oil sump 154A/154B may be at a higher pressure that results in the injected oil f_O having the relatively higher pressure P_O. For example, the higher pressure of the oil f_O in the oil sump 154A/154B may cause the flow of the oil f_O into and through the suction pathway 118. In such an embodiment, the restriction 162 may be configured to limit flow through the suction pathway 118 to a desired amount. In an embodiment, the desired amount may be an amount that limits the discharge temperature by a predetermined amount. The restriction 162 in an embodiment may have a static configuration. The restriction 162 in some embodiments may have an adjustable configuration (e.g., a valve controlled by the controller 190, a valve adjustable by hand and set to a predetermined opening amount based on a configuration of the working fluid circuit 102, etc.).

[0048] The oil pump 160 can provide an increase in the pressure of the oil f_O in the suction pathway 142, which can cause an increased pressure drop in the oil f_O injected into the suction pathway 118. The compression by the restriction 162 can provide an increased pressure drop in the oil f_O injected into the suction pathway 118. The increased pressure drop provided by the oil pump 160 and/or the restriction 162 can ensure the liberation of the dissolved refrigerant in the injected the oil f_O (e.g., provide a greater amount of the dissolved gaseous refrigerant is liberated from the liquid oil) and a greater amount of cooling of the working fluid f_I provided by the injected oil f_O.

[0049] The oil injection system 140 includes an oil cooler 170A/170B for cooling the oil f_O prior to injection. The oil cooler 170A/170B is an oil heat exchanger that cools the oil. The oil heat exchanger cools with an oil coolant f_C. The oil heat exchanger may cool the oil with a portion of the working fluid in the working fluid circuit 102 (e.g., oil coolant f_C is a portion of the working fluid, oil coolant is an intermediate fluid cooled by the working fluid in the working fluid circuit, etc.) In an embodiment, the oil coolant f_C can be a portion of the relatively colder working fluid (e.g., a portion of the relatively colder, expanded working fluid in the working fluid circuit 102). In one example, the oil cooler 170A/170B may be a second evaporator configured to cool the oil f_O using a portion of the working fluid discharged from an expander in the working fluid circuit 102 (e.g., a portion of the working fluid discharged from the expander 52 in the working fluid circuit 2 in FIG. 1). In another embodiment, the oil coolant f_C may be a fluid different from the working fluid used to provide cooling (e.g., oil coolant f_C being the first process fluid in FIG. 1, oil coolant f_C being ambient air, cooling water, etc.). In one example, the oil cooler 170A/170B may be liquid-air heat exchanger (e.g., a radiator, etc.) that cools the oil using ambient air. In another example, the oil cooler 170A/170B may be a liquid-liquid heat exchanger (e.g., tube and shell heat exchanger, plate heat exchanger, etc.) that cools the air using engine coolant. In another example, the oil cooler 170A, 170B may be heat exchanger in the form of a tube, passageway, etc. that extends near or through the evaporator in the refrigerant circuit 102 (e.g., evaporator 54) and is cooled by the refrigerant in the refrigerant circuit 102 or by cooled air discharged from the evaporator.

[0050] The oil cooler 170A/170B can be configured to provide cooling to the oil in the oil sump 154A/154B and/or to provide cooling to the oil f_O in the oil pathway 142. In one example, an oil cooler 170A is configured to cool the oil 152 within the oil sump 154A/154B (e.g., within the oil sump 154A of the compressor 110, within the oil sump 154B of the oil separator 150). The oil cooler 170A cooling all of the oil in the oil sump 154A/154B. The oil injection system 140 can include a second oil pump 172 configured to circulate the oil 152 in the oil separator 150A through the oil cooler 170A. In FIG. 2, the oil cooler 170A is illustrated for cooling the oil in the oil sump 154A within the compressor 110. It should be appreciated that when the oil separator includes the oil sump 154B, the oil cooler 170A can be configured to cool the oil in the oil sump 154B of the oil separator 150.

[0051] In another example, the oil pathway 142 includes an oil cooler 170B configured to cool the oil f_O in the oil pathway 142. The oil f_O in the oil pathway 142 passes through the oil cooler 170B as the oil f_O flows through the oil pathway 142, and the oil f_O is cooled by the oil cooler 170B as the oil f_O flows through the oil cooler 170B. In an embodiment, the intermediate outlet 148 can be disposed downstream of the oil cooler 170B such that the oil cooler 170B can also provide cooling of the oil 152 in the oil sump 154A/154B. In another embodiment, the intermediate pathway 160 may be provided upstream of the oil cooler 170B (e.g., between the oil pump 160 and the oil cooler 170B, at the oil pump 160).

[0052] The oil injection by the oil pathway 142 provides cooling to the working fluid f_I, which decreases a discharge temperature T_D of the compressed working fluid f_D discharged from the compressor 110. In an embodiment, the oil injection by the oil pathway 142 decreases the discharge temperature T_D of the compressed working fluid f_D by at least 5° F. In an embodiment, the oil injection by the oil pathway 142 decreases the discharge temperature T_D of the compressed working fluid f_D by at least 10° F. In an embodiment, the oil injection by the oil pathway 142 decreases the discharge temperature T_D of the compressed working fluid f_D by at least 15° F. Said cooling can be achieved without providing the oil cooling by an oil cooler 170A/170B. This cooling amount can be provided without a substantial increase in torque of the compressor 110.

[0053] In an embodiment, the oil pathway 142 is configured to provide cooling such that the discharge temperature T_D of the compressed working fluid f_D is 325° F. or less. In an embodiment, the oil pathway 142 is configured to provide cooling such that the discharge temperature T_D of the compressed working fluid f_D is 315° F. or less. In an embodiment, the oil pathway 142 is configured to provide cooling such that the discharge temperature T_D of the compressed working fluid f_D is 300° F. or less. In an embodiment, the oil pathway 142 is configured to provide cooling such that the discharge temperature T_D of the compressed working fluid f_D is 290° F. or less. The above temperatures can be the maximum steady state temperature of the discharge temperature T_D of the compressor 110.

[0054] It should be appreciated that the oil pathway 142 may be configured to provide an amount of cooling such that the discharge temperature T_D of the compressed working fluid f_D is at or within a desired temperature range. Said amount of cooling may also vary depending on the configuration of the compressor (e.g., heat of compression of employed refrigerant, solubility of employed oil in the refrigerant, flow rate of working fluid being compressed, compression ratio of the working fluid by the compressor, etc.). For example, but not limited to, one or more of the amount of oil injected by the oil pathway, providing oil cooling and/or the amount of oil cooling provided (in the oil sump and/or in the oil pathway), and providing the restriction and/or a size of the restriction 162, etc. may be adjusted to provide cooling that results in the discharge temperature T_D of the compressed working fluid f_D at the desired range (e.g., below the desired temperature).

[0055] As discussed above, the oil injection system 140 can include an oil cooler 170A/170B for cooling the oil f_O prior to injection. The oil cooling by oil cooler 170A/170B, without oil injection by the oil pathway 142, can provide cooling and a decrease the discharge temperature T_D. The oil cooling by oil cooler 170A/170B can increase a cooling effect of the oil injection by the oil pathway 142. The oil cooling can cause an increase in torque of the compressor. With an oil cooler 170A/170B providing cooling, the oil injection by the oil pathway 142 is configured to decrease the discharge temperature T_D of the compressed working fluid f_D by at least 10-30° F. With an oil cooler 170A/170B providing cooling, the oil injection by the oil pathway 142 is configured to decrease the discharge temperature T_D of the compressed working fluid f_D by at least 10° F. With an oil cooler 170A/170B providing cooling, the oil injection by the oil pathway 142 is configured to decrease the discharge temperature T_D of the compressed working fluid f_D by at least 15° F.

[0056] FIG. 3 is a block flow diagram of an embodiment of a method 1000 of controlling a working fluid circuit. The working fluid circuit includes a compressor. The working fluid circuit can be a working fluid circuit for an HVACR system. For example, the method 1000 may be employed to control the working fluid circuit 2 of the HVACR system 1 in FIG. 1. For example, the method 1000 may be employed to control the working fluid circuit 102 of the HVACR system 1 in FIG. 2. The working fluid circuit contains working fluid and includes a compressor (e.g., compressor 10, compressor 110). The method 1000 starts at 1010.

[0057] At 1010, the working fluid is suctioned into a compressor. For example, the suctioning of the working fluid at 1010 can include suctioning working fluid through a suction inlet of the compressor (e.g., suction inlet 12, suction inlet 112) into one or more compression pockets of the compressor (e.g., compression pocket(s) 120). For example, a suction pathway of the compressor (e.g., suction pathway 18, suction pathway 118) supplies the working fluid to the compression pocket(s). The method 1000 then proceeds to 1020.

[0058] At 1020, the working fluid is compressed within the compressor into a compressed working fluid. For example, the working fluid is compressed by the compression pockets into the compressed working fluid. The compressed working fluid is discharged from the compressor via a discharge outlet of the compressor (e.g., discharge outlet 14, discharge outlet 114). For example, the working fluid is suctioned into the compression pockets, compressed within the compression pockets, and the compressed working fluid is discharged from the compression pockets and the compressor via the discharge outlet. The method 1000 then proceeds to 1030.

[0059] At 1030, oil in the working fluid is directed to an oil sump (e.g., oil sump 154A, oil sump 154B). For example, the working fluid contains oil and refrigerant, and the oil separates from the refrigerant in the working fluid and flows to the oil sump 154. In an embodiment, the oil separated from the working fluid by flowing to the oil sump within the compressor. The oil may be separated from the working fluid within the compressor at 1030 prior to be compressed, during the compression, and/or after being compressed. In an embodiment, an oil separator (e.g., oil separator 150) is provided to separate the oil from the working fluid (e.g., from the compressed working fluid). In an embodiment, the oil separator (e.g., oil separator 56, oil separator 150) is connected to the discharge outlet of the compressor. The method 1000 proceeds to 1040.

[0060] At 1040, oil from the oil sump is supplied via an oil pathway into the suction pathway of the compressor. In particular, a portion of the oil in the oil sump is supplied from the oil sump into the suction pathway. In an example, the supplying of the oil at 1040 can include an oil pump (e.g., oil pump 160) to pump the oil through the oil pathway and into the suction pathway. In an example, supplying of the oil at 1042 can include passing the oil through a restriction (e.g., restriction 162) in the oil pathway. The passing of the oil through the restriction can compress the oil. The supplying of the oil at 1040 includes injecting the oil from the oil pathway into the suction pathway 1042 and liberating gaseous refrigerant dissolved in the oil at 1044.

[0061] At 1042, the oil pathway injects the oil from the oil pathway into the suction pathway. The oil is injected into the suction pathway and mixes with the working fluid flowing in the suction pathway. In an embodiment, the oil injected into the suction pathway at 1042 upstream of the suction inlet of the compressor. In an embodiment, the oil injected into the suction pathway at 1042 at the suction plenum of the compressor (e.g., suction plenum 122).

[0062] At 1044, gaseous refrigerant dissolved in the oil is liberated from the oil. The dissolved gaseous refrigerant is liberated from the liquid oil. For example, the injection of the oil into the suction pathway can cause the liberation of dissolved gaseous refrigerant from the oil. The pressure drop in the oil when injected from the oil pathway into the suction pathway can cause the liberation of dissolved gaseous refrigerant from the oil. The liberation of the gaseous refrigerant provides cooling to the oil, which cools the working fluid.

[0063] The injected oil then mixes into the working fluid. The method 1000 can then return to 1010 from 1040. For example, the working fluid (that contains the oil injected at 1042) is then suctioned into the compressor at 1010, and the oil separated from the working fluid at 1030 includes the oil injected at 1044.

[0064] In an embodiment, the method 1000 can include cooling of the separated oil at 1046. As shown in FIG. 2, the supplying of the oil from the oil sump into the suction pathway at 1040 can include the cooling of the oil 1046. For example, the oil pathway can include an oil cooler (e.g., oil cooler 170A), and the oil is cooled in the oil pathway (e.g., the oil is cooled by the oil cooler as it flows through the oil cooler in the oil pathway). In an embodiment, the cooling of the separated oil 1046 may include cooling, with an oil cooler (e.g., oil cooler 170B) cooling the separated oil prior to being supplied at 1040.

[0065] It should be appreciated that the method 1000 in an embodiment may be modified to have features of the working fluid circuit 2 as discussed herein and/or shown in FIG. 1 and/or to have features of the working fluid circuit 102 as discussed herein and/or shown in FIG. 2. For example, the method 1000 in an embodiment may include the operation of other components in the working fluid circuit 1 as discussed herein (e.g., cooling of the compressed working fluid in the condenser, expanding of the working fluid cooled in the condenser, cooling of a process fluid in the evaporator by the expanded working fluid).

Any one of Aspects 1-13 may be combined with any of Aspects 14-18
Aspect 1. A working fluid circuit, comprising:

• • [0066] a compressor including a suction inlet, a discharge outlet, and one or more compression chambers connecting the suction inlet to the discharge outlet and configured to compress working fluid;
  • [0067] an oil sump configured to contain oil separated from the working fluid; and
  • [0068] an oil injection system with an oil pathway connected to the oil sump and to a suction pathway of the compressor, the suction pathway including the suction inlet, the oil pathway configured to inject the oil from the oil sump into the suction pathway to cool the working fluid in the suction pathway flowing to the one or more compression chambers.
    Aspect 2. The working fluid circuit of Aspect 1, wherein the oil pathway injects the oil into the suction pathway at a higher pressure than the working fluid in the suction pathway, such that gaseous refrigerant dissolved in the portion of the oil is liberated from the oil and cools the oil.
    Aspect 3. The working fluid circuit of any one of Aspects 1-2, wherein the oil pathway includes an oil pump, the oil pump configured to direct the oil from the oil sump into and through the oil pathway to inject the oil into the suction pathway of the compressor.
    Aspect 4. The working fluid circuit of any one of Aspects 1-3, wherein the oil pathway includes a restriction, the restriction configured to compress the oil as the oil in the oil pathway flows through the restriction.
    Aspect 5. The working fluid circuit of any one of Aspects 1-4, wherein the injection of the oil into the suction pathway by the oil pathway is configured to decrease a discharge temperature of the compressed working fluid discharged from the compressor by at least 5° F.
    Aspect 6. The working fluid circuit of any one of Aspects 1-5, wherein the injection of the oil into the suction pathway by the oil pathway is configured to decrease a discharge temperature of the compressed working fluid from the compressor by at least 10° F.
    Aspect 7. The working fluid circuit of any one of Aspects 1-6, wherein the compressor includes the oil sump.
    Aspect 8. The working fluid circuit of any one of Aspects 1-6, further comprising:
  • [0069] an oil separator connected to the discharge outlet of the compressor, the oil separator configured to receive the compressed working fluid that contains the oil and to separate the oil therefrom.
    Aspect 9. The working fluid circuit of any one of Aspects 1-8, wherein the compressor including a suction plenum for the one or more compression chambers, the suction inlet connecting to the suction plenum, and an outlet of the oil pathway connects to the suction pathway at a suction plenum of the compressor such that the that the suction pathway injects the oil into the suction pathway at the suction plenum.
    Aspect 10. The working fluid circuit of any one of Aspects 1-9, further comprising:
  • [0070] an oil heat exchanger configured to cool one or more of:
    • [0071] the oil flowing through the oil pathway, and
    • [0072] the oil in the oil sump.
      Aspect 11. The working fluid circuit of any one of Aspects 1-10, wherein the oil heat exchanger is configured to cool the oil by at least 50° C.
      Aspect 12. The working fluid circuit of any one of Aspects 1-11, wherein the working fluid circuit has an oil circulation rate of 10% or less.
      Aspect 13. The working fluid circuit of any one of Aspects 1-12, wherein the working fluid contains A2L refrigerant.
      Aspect 14. A method of controlling a working fluid circuit including a compressor, the method comprising:
  • [0073] suctioning a working fluid into the compressor;
  • [0074] compressing, within the compressor, the working fluid into a compressed working fluid;
  • [0075] discharging the compressed working fluid from the compressor;
  • [0076] directing oil from the working fluid into an oil sump;
  • [0077] supplying, via an oil pathway, the oil from the oil sump into a suction pathway of the compressor, which includes:
    • [0078] injecting the oil from the oil pathway into the suction pathway, and
    • [0079] liberating gaseous refrigerant dissolved in the oil from the oil to provide cooling to the working fluid in the suction pathway.
      Aspect 15. The method of Aspect 14, wherein the injecting of the oil into the suction pathway decreases a pressure of the oil causing the liberating of the gaseous refrigerant dissolved in the oil from the oil.
      Aspect 16. The method of any one of Aspects 14-15, further comprising:
  • [0080] cooling of the oil prior to the injecting of the oil, which includes one or more of:
    • [0081] cooling the oil flowing through the oil pathway, and
    • [0082] cooling of the oil disposed in the oil sump.
      Aspect 17. The method of any one of Aspects 14-16, wherein the supplying of the oil, via an oil pathway, from the oil sump into the suction pathway of the compressor decreases a discharge temperature of the compressor by at least 5° F.
      Aspect 18. The method of any one of Aspects 14-17, wherein the supplying of the oil, via an oil pathway, from the oil sump into the suction pathway of the compressor decreases a discharge temperature of the compressor by at least 10° F.

[0083] The terminology used herein is intended to describe particular embodiments and is not intended to be limiting. The terms “a,” “an,” and “the” include the plural forms as well, unless clearly indicated otherwise. The terms “comprises” and/or “comprising,” when used in this Specification, specify the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and/or components. In an embodiment, “connected” and “connecting” as described herein can refer to being “directly connected” and “directly connecting”.

[0084] With regard to the preceding description, it is to be understood that changes may be made in detail, especially in matters of the construction materials employed and the shape, size, and arrangement of parts without departing from the scope of the present disclosure. This Specification and the embodiments described are exemplary only, with the true scope and spirit of the disclosure being indicated by the claims that follow.