SYSTEM AND METHOD FOR SWITCHING BETWEEN SINGLE AND MULTIPLE COMPRESSOR CYCLES BASED ON AMBIENT TEMPERATURE

Description

TECHNICAL FIELD

This disclosure relates generally to refrigeration systems. More particularly, this disclosure relates to a system and method for switching between single and multiple compressor cycles based on ambient temperature.

BACKGROUND

Cooling systems are used to cool spaces, such as residential dwellings, commercial buildings, and/or refrigeration units. These systems cycle a refrigerant (also referred to as charge) that is used to cool the spaces.

SUMMARY OF THE DISCLOSURE

Conventional refrigeration systems may include a medium-temperature and a low-temperature compressor. In some conventional refrigeration systems, the low-temperature compressor compresses refrigerant from the low-temperature section (e.g., freezers in a store), while the medium-temperature compressor handles a combination of refrigerants, including the low-temperature compressor's discharge, medium-temperature refrigerant (e.g., from display cases), and flash gas from the flash tank. In some cases, this configuration may suffer from several drawbacks. One drawback is that the medium-temperature compressor is tasked to handle multiple refrigerant streams simultaneously (i.e., refrigerant streams from the low-temperature compressor, liquid refrigerant from the flash tank, and vapor refrigerant from the flash tank). If the refrigeration system experiences inconsistent gas cooler outlet conditions, such as two-phase refrigerant (liquid and gas) instead of subcooled liquid entering the flash tank, excessive flash vapor may be generated at the flash tank. This vapor may cause the bypass valve to open, and the additional flash vapor is leaked into the suction line of the medium-temperature compressor. This may lead to loss of lubrication at the medium-temperature compressor when the additional vapor interferes with the oil return process, and, therefore, damage at the medium-temperature compressor.

Further, the additional bypass refrigerant vapor influx to the medium-temperature compressor is due the inner circulation between the outdoor heat exchanger (e.g., gas cooler), the flash tank, oil separator, and the medium-temperature compressor. Thus, the additional bypass refrigerant vapor does not contribute to the cooling capacity of the refrigeration system. In other words, it does not cool down the refrigerant at the indoor heat exchanger. Therefore, in response to detecting the additional vapor influx to the medium-temperature compressor, the medium-temperature compressor may interpret this as a demand to increase its speed to compress the additional vapor influx. Thus, the medium-temperature compressor ends up cooling the additional bypass refrigerant vapor that is not contributing to the cooling capacity of the system. This leads to wasting energy and power consumption at the medium-temperature compressor as it increases its speed to compress the additional bypass refrigerant vapor.

Another drawback in conventional refrigeration systems is that both the high-temperature compressor and the low-temperature compressor are active in all ambient conditions, including low ambient conditions (e.g., in winter) and high ambient conditions (e.g., in summer). However, in low ambient conditions, the low-temperature compressor is sufficient to compress the refrigerant and provide cooling to the target indoor space. Thus, the conventional refrigeration systems waste energy by operating the high-temperature compressor in low ambient conditions.

Another drawback in conventional refrigeration systems is that they require controlling bypass valves to manage the refrigerant flow from three different streams (i.e., refrigerant streams from the low-temperature compressor, liquid refrigerant from the flash tank, and vapor refrigerant from the flash tank). This increases the control complexity of the systems and makes troubleshooting more difficult.

The disclosed system provides a solution to these and other technical problems of the conventional refrigeration systems. The disclosed refrigeration system is configured to implement a switching valve downstream of the low-temperature compressor to allow the refrigerant flow to bypass the medium-temperature (booster) compressor when the ambient temperature is below a set threshold temperature (e.g., in winter), and utilize the medium-temperature compressor when the ambient temperature is more than or equal to the threshold temperature (e.g., in summer).

This disclosure contemplates an unconventional refrigeration system that obviates the need for the oil separator and dynamically changes the flow path of the refrigerant based on ambient temperature by implementing the switching valve. By controlling the flow of the refrigerant at the switching valve based on the ambient temperature, the liquid refrigerant stream from the flash tank to the compressor can be eliminated. This simplifies the design of refrigeration systems and their control because the bypass valves can be removed from the design. Further, with the disclosed refrigeration system, the control of the high-pressure valve downstream of the outdoor heat exchanger (e.g., gas cooler) in low ambient conditions is simplified because the refrigerant temperature is already low. Therefore, the pressure differential across the high-pressure valve remains stable. Thus, the control of the high-pressure valve is simpler due to the stable pressure differential. For example, the high-pressure valve may be fully opened in low ambient temperature conditions.

Further, by bypassing the medium-temperature compressor during low ambient conditions, the system eliminates the recirculation of refrigerant vapor from the flash tank to the medium-temperature compressor. This leads to reducing the probability of oil entering the medium-temperature compressor. Therefore, the oil separator component may not be needed.

In some embodiments, the refrigeration system comprises a temperature sensor circuit configured to detect an ambient temperature within a vicinity of the refrigeration system. The refrigeration system further comprises an indoor heat exchanger configured to receive a working fluid from a flash tank. The refrigeration system further comprises a first compressor positioned downstream of the indoor heat exchanger and configured to compress the working fluid received from the indoor heat exchanger. The refrigeration system further comprises a second compressor positioned downstream of the flash tank and configured to compress the working fluid received at least from the flash tank. The refrigeration system further comprises a switching valve positioned downstream of the first compressor and configured to selectively switch a flow of the working fluid between the second compressor and an outdoor heat exchanger depending on the detected ambient temperature. The refrigeration system further comprises a controller, communicatively coupled with the switching valve and the temperature sensor circuit. The controller comprises a processor configured to receive the detected ambient temperature from the temperature sensor circuit. The processor is further configured to determine whether the detected ambient temperature is less than a threshold temperature. The processor is further configured to communicate a first electronic signal to the switching valve to bypass the second compressor and allow the working fluid to flow from the switching valve toward the outdoor heat exchanger in response to determining that the detected ambient temperature is less than the threshold temperature. The processor is further configured to communicate a second electronic signal to the switching valve to allow the working fluid to flow from the switching valve toward the second compressor before flowing toward the outdoor heat exchanger in response to determining that the received ambient temperature is equal to or more than the threshold temperature.

Certain embodiments of the present disclosure may include some, or none of these advantages. These advantages and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:

FIG. 1A illustrates a diagram of an embodiment of a refrigeration system configured to operate in a high ambient temperature mode;

FIG. 1B illustrates a diagram of an embodiment of a refrigeration system configured to operate in a low ambient temperature mode; and

FIG. 2 illustrates a flowchart of an example method of operating the system of FIGS. 1A and 1B.

DETAILED DESCRIPTION

Embodiments of the present disclosure and its advantages are best understood by referring to FIGS. 1A through 2 of the drawings, like numerals being used for like and corresponding parts of the various drawings.

Conventional refrigeration systems may include a medium-temperature and a low-temperature compressor. In some conventional refrigeration systems, the low-temperature compressor compresses refrigerant from the low-temperature section (e.g., freezers in a store), while the medium-temperature compressor handles a combination of refrigerants, including the low-temperature compressor's discharge, medium-temperature refrigerant (e.g., from display cases), and flash gas from the flash tank. In some cases, this configuration may suffer from several drawbacks. One drawback is that the medium-temperature compressor is tasked to handle multiple refrigerant streams simultaneously (i.e., refrigerant streams from the low-temperature compressor, liquid refrigerant from the flash tank, and vapor refrigerant from the flash tank). If the refrigeration system experiences inconsistent gas cooler outlet conditions, such as two-phase refrigerant (liquid and gas) instead of subcooled liquid entering the flash tank, excessive flash vapor may be generated at the flash tank. This vapor may cause the bypass valve to open, and the additional flash vapor is leaked into the suction line of the medium-temperature compressor. This may lead to loss of lubrication at the medium-temperature compressor when the additional vapor interferes with the oil return process, and, therefore, damage at the medium-temperature compressor.

Further, the additional bypass refrigerant vapor influx to the medium-temperature compressor is due the inner circulation between the outdoor heat exchanger (e.g., gas cooler), the flash tank, oil separator, and the medium-temperature compressor. Thus, the additional bypass refrigerant vapor does not contribute to the cooling capacity of the refrigeration system. In other words, it does not cool down the refrigerant at the indoor heat exchanger. Therefore, in response to detecting the additional vapor influx to the medium-temperature compressor, the medium-temperature compressor may interpret this as a demand to increase its speed to compress the additional vapor influx. Thus, the medium-temperature compressor ends up cooling the additional bypass refrigerant vapor that is not contributing to the cooling capacity of the system. This leads to wasting energy and power consumption at the medium temperature compressor as it increases its speed to compress the additional bypass refrigerant vapor. Another drawback in the conventional refrigeration systems is that both high-temperature compressor and low-temperature compressor are active in all ambient conditions, including low ambient conditions (e.g., in winter) and high ambient conditions (e.g., in summer). However, in low ambient conditions, the low-temperature compressor is sufficient to compress the refrigerant and provide cooling to the target indoor space. Thus, the conventional refrigeration systems waste energy by operating the high-temperature compressor in low ambient conditions. Another drawback in the conventional refrigeration systems is that they require controlling bypass valves to manage the refrigerant flow from three different streams (i.e., refrigerant streams from the low-temperature compressor, liquid refrigerant from the flash tank, and vapor refrigerant from the flash tank). This increases the control complexity of the systems and makes troubleshooting more difficult.

The disclosed system provides a solution to these and other technical problems of the conventional refrigeration systems. The disclosed refrigeration system is configured to implement a switching valve downstream of the low-temperature compressor to allow the refrigerant flow to bypass the medium temperature (booster) compressor when the ambient temperature is below a set threshold temperature (e.g., in winter), and utilize the medium-temperature compressor when the ambient temperature is more than or equal to the threshold temperature (e.g., in summer).

This disclosure contemplates an unconventional refrigeration system that obviates the need for the oil separator and dynamically changes the flow path of the refrigerant based on ambient temperature by implementing the switching valve. By controlling the flow of the refrigerant at the switching valve based on the ambient temperature, the liquid refrigerant stream from the flash tank to the compressor can be eliminated. This simplifies the design of refrigeration systems and their control because the bypass valves can be removed from the design. Further, with the disclosed refrigeration system, the control of the high-pressure valve downstream of the outdoor heat exchanger (e.g., gas cooler) in low ambient conditions is simplified because the refrigerant temperature is already low. Therefore, the pressure differential across the high-pressure valve remains stable. Thus, the control of the high-pressure valve is simpler due to the stable pressure differential. For example, the high-pressure valve may be fully opened in low ambient temperature conditions.

Further, by bypassing the medium-temperature compressor during low ambient conditions, the system eliminates the recirculation of refrigerant vapor from the flash tank to the medium-temperature compressor. This leads to reducing the probability of oil entering the medium-temperature compressor. Therefore, the oil separator component may not be needed.

Refrigeration System

FIGS. 1A and 1B illustrate an example refrigeration system 100, operating in a high ambient temperature mode and a low ambient temperature mode, respectively, according to some embodiments of the present disclosure. In general, the refrigeration system 100 is configured to control the flow of refrigerant via a switching valve 122 based on the ambient temperature 154. In some embodiments, the refrigeration system 100 comprises refrigerant conduit subsystems 102, a flash tank 112, check valves 114, 130, an indoor heat exchanger 116, a first compressor 118, a desuperheater 120, the switching valve 122, a second compressor 124, an outdoor heat exchanger 126, a temperature sensor circuit 128, and a controller 140. In some embodiments, the refrigeration system 100 is a transcritical refrigeration system that circulates a working fluid, such as a transcritical refrigerant (e.g., CO₂).

FIG. 1A illustrates the flow of the refrigerant through the refrigeration system 100 operating in a high ambient temperature mode 104. In FIG. 1A, the refrigerant conduit subsystems 102 through which the refrigerant flows to operate the refrigeration system 100 in a high ambient temperature mode 104 are shown with solid lines, and other refrigerant conduit subsystems 102 that are not in use are shown with dash lines. The refrigeration system 100 may be configured as shown in FIG. 1A or in any other suitable configuration. For example, the refrigeration system 100 may include additional components or may omit one or more components shown in FIG. 1A. The refrigeration system 100 is controlled by the controller 140.

FIG. 1B illustrates the flow of the refrigerant through the refrigerant system 100 operating in a low ambient temperature mode 106. In FIG. 1B, the refrigerant conduit subsystems 102 through which the refrigerant flows to operate the refrigeration system 100 in the low ambient temperature mode 106 are shown with solid lines, and other refrigerant conduit subsystems 102 that are not in use are shown with dash lines. The refrigeration system 100 may be configured as shown in FIG. 1B or in any other suitable configuration. For example, the refrigeration system 100 may include additional components or may omit one or more components shown in FIG. 1B. The refrigeration system 100 is controlled by the controller 140.

System Components

Each component labeled with the same reference number in FIG. 1A and FIG. 1B represents the same physical component in the system 100; however, the specific function of each component may vary depending on whether the system 100 is operating in high ambient temperature mode 104 (in FIG. 1A) or low ambient temperature mode 106 (in FIG. 1B). The components of the system 100 are described below.

Referring to FIG. 1A, the refrigerant conduit subsystems 102 facilitate the movement of a working fluid (e.g., refrigerant) through a refrigeration cycle such that the working fluid flows as illustrated by arrows in FIG. 1A. The refrigerant conduit subsystem 102 includes any conduit, tubing and the like that is illustrated in FIG. 1A fluidly connecting components of the refrigeration system 100. The refrigerant conduit subsystems 102 illustrated in FIG. 1B are the same or similar to the refrigerant conduit subsystems 102 illustrated in FIG. 1A.

The flash tank 112 may generally be a storage component to store refrigerant in vapor and liquid forms. The flash tank 112 is fluidly coupled to the refrigerant conduit subsystem 102 and is positioned downstream of the outdoor heat exchanger 126. The flash tank 112 is configured to separate the refrigerant into a vapor refrigerant and a liquid refrigerant. Typically, the vapor refrigerant collects near the top of the flash tank 112 and the liquid refrigerant is collected at the bottom of the flash tank 112. In some embodiments, when the refrigerant system 100 operates in the high ambient temperature mode 104 (see FIG. 1A), the liquid refrigerant flows from flash tank 112 toward the indoor heat exchanger 116 and provides cooling to the indoor heat exchanger 116, and the vapor refrigerant flows from the flash tank 112 toward the second heat exchanger 126 and provides cooling to second heat exchanger 126. In some embodiments, when the refrigeration system 100 operates in the low ambient temperature mode 106 (see FIG. 1B), the liquid refrigerant flows from the flash tank 112 toward the indoor heat exchanger 116 and provides cooling to the indoor heat exchanger 116. When operating in the low ambient temperature mode 106 (see FIG. 1B), the vapor refrigerant does not flow from the flash tank 112 to the second compressor 124.

The valve 114 may generally be a flow control valve, flash gas valve, a solenoid valve, a motorized valve, a check valve, an electronic expansion valve (EEV), a thermal expansion valve (TXV), and the like. The valve 114 may be positioned in the refrigerant conduit subsystem 102 and located in a portion of the refrigerant conduit subsystem 102 that connects the flash tank 112 to the indoor heat exchanger 116. The valve 114 is configured to open and close to control the flow of the refrigerant discharged from flash tank 112. The controller 140 may be in signal communication with the valve 114 (e.g., via wired and/or wireless communication) and control its operation by sending electronic signals to the valve 114, in the examples of EEV valve 114.

The indoor heat exchanger 116 may be a low-side heat exchanger and generally include one or more indoor condenser coils and fans to move air across the coils. The indoor heat exchanger 116 may act as an evaporator. When the refrigerant reaches the indoor heat exchanger 116, the refrigerant absorbs heat from the surrounding air in the target indoor space and releases cooled or conditioned air into the target space. For example, the refrigerant cools metallic components (e.g., metallic coils, plates, and/or tubes) of the indoor heat exchanger 116 as the refrigerant passes through them. These metallic components may then cool the air around them. The cooled air may then be circulated such as, for example, by a fan to cool a space such as, for example, a freezer and/or a refrigerated shelf. The indoor heat exchanger 116 is in signal communication with the controller 140 using wired and/or wireless connection. The controller 140 may send control signals to the indoor heat exchanger 116 control the speed of the fans based on temperature conditions.

The indoor heat exchanger 116 is fluidly coupled to the refrigerant conduit subsystem 102 and is located downstream of the flash tank 112. The indoor heat exchanger 116 is configured to receive liquid refrigerant from the flash tank 112 through the refrigerant conduit subsystem 102. The indoor heat exchanger 116 is configured to use the refrigerant to provide cooling to the space proximate to the indoor heat exchanger 116. As an example, the indoor heat exchanger 116 may be part of a refrigerated case and/or cooler for storing items that should be kept at particular temperatures. The refrigeration system 100 may include any appropriate number of indoor heat exchangers 116 with the same or a similar configuration to that shown for the example the indoor heat exchanger 116 in each of FIGS. 1A and 1B.

The first compressor 118 may be a variable speed compressor or multiple-stage compressor and generally configured to compress (e.g., increase the pressure) of the refrigerant. The first compressor 118 is fluidly coupled with the refrigerant conduit subsystem 102. The first compressor 118 is in signal communication with the controller 140 using wired and/or wireless connection. The controller 140 may communicate electronic signals to the first compressor 118 to control its speed. A variable-speed compressor is generally configured to operate at different speeds to increase the pressure of the refrigerant to keep the refrigerant moving along the refrigerant conduit subsystem 102. In the variable-speed compressor configuration, the speed of compressor 118 can be modified to adjust the cooling capacity and/or load of the refrigerant system 100. Meanwhile, in the multi-stage compressor configuration, one or more compressors can be turned on or off to adjust the cooling capacity of the refrigeration system 100. The first compressor 118 may be positioned downstream of the indoor heat exchanger 116 and configured to compress the refrigerant received from the indoor heat exchanger 116. The first compressor 118 may be a low-temperature compressor configured to compress refrigerant from low-temperature applications, such as freezers, by increasing the refrigerant pressure.

The desuperheater 120 may be a heat exchanger and generally configured to reduce the temperature of the superheated refrigerant discharged from the first compressor 118 before the refrigerant mixes or getting mixed with the working fluid from the flash tank 112, when operating in the high ambient temperature mode 104. The desuperheater 120 may be positioned between the first compressor 118 and the switching valve 122. The desuperheater 120 is fluidly coupled to the refrigerant conduit subsystem 102. The desuperheater 120 may be in signal communication with the controller 140 using wired and/or wireless connection. The desuperheater 120 may be optional, and some configurations may not be implemented. When included, the desuperheater 120 may reduce the thermal load on the second compressor 124 by reducing the temperature of the refrigerant before it is provided to the second compressor 124.

The switching valve 122 may be a motorized valve, a solenoid valve, an EEV, or any other suitable valve configured to selectively switch the flow of refrigerant between two paths (e.g., from the first compressor 118 towards either the second compressor 124 or the outdoor heat exchanger 126 depending on the detected ambient temperature 154 (indicated in the ambient temperature data 152)). In other words, the switching valve 122 may selectively switch the flow of the working fluid between the second compressor 124 and the outdoor heat exchanger 126 depending on the detected ambient temperature 154. The switching valve 122 is positioned downstream of the first compressor 118 (and the desuperheater 120 when included). The switching valve 122 is fluidly coupled to the refrigerant conduit subsystem 102. The switching valve 122 may be in signal communication with the controller 140 using wired and/or wireless connection. The switching valve 122 may include one inlet 132 and two outlets 134a and 134b, where the first outlet 134a is toward the second compressor 124 and the second outlet 134b is toward the outdoor heat exchanger 126. The outlet 134a connects the refrigerant conduit subsystem 102 from the switching valve 122 to the refrigerant conduit subsystem 102 that is connected to the flash tank 112 and the second compressor 124. The second outlet 134b connects the refrigerant conduit subsystem 102 from the switching valve 122 to the refrigerant conduit subsystem 102 that is connected to the outdoor heat exchanger 126.

The flow of the refrigerant is controlled by opening and closing the outlets 134a and 134b based on the detected ambient temperature 154 to bypass the second compressor 124 when operating in low ambient temperature mode 106 (see FIG. 1B) and cause the refrigerant to flow from the switching valve 122 to the outdoor heat exchanger 126 via the at least partially open outlet 134b and closed outlet 134a. When operating in high ambient temperature mode 104 (see FIG. 1A), the flow of the refrigerant is from the switching valve 122 to the second compressor 124 via the at least partially open outlet 134a and closed outlet 134b.

The second compressor 124 may be a variable speed compressor or multiple-stage compressor and generally configured to compress (e.g., increase the pressure) of the refrigerant. The second compressor 124 is fluidly coupled with the refrigerant conduit subsystem 102. The second compressor 124 is in signal communication with the controller 140 using wired and/or wireless connection. The controller 140 may communicate electronic signals to the second compressor 124 to control its speed. A variable-speed compressor is generally configured to operate at different speeds to increase the pressure of the refrigerant to keep the working fluid moving along the fluid conduit subsystem 102. In the variable-speed compressor configuration, the speed of compressor 124 can be modified to adjust the cooling capacity and/or load of the refrigerant system 100. Meanwhile, in the multi-stage compressor configuration, one or more compressors can be turned on or off to adjust the cooling capacity of the refrigeration system 100. The second compressor 124 may be a medium-temperature compressor configured to compress refrigerant from medium-temperature applications, such as medium cooling, by increasing the refrigerant pressure.

Referring to FIG. 1A, when the system 100 operates in high ambient temperature mode 104 the second compressor 124 may be positioned downstream of the flash tank 112 and the indoor heat exchanger 116 (via the switching valve 122). Thus, in high ambient temperature mode 104, the second compressor 124 is configured to compress the refrigerant received from flash tank 112 and the indoor heat exchanger 116 (passed through the switching valve 122 and optionally the desuperheater 120 when its included).

Referring to FIG. 1B, when the system 100 operates in the low ambient temperature mode 106, the second compressor 124 may be bypassed by the switching valve 122. In this mode, the refrigerant flows directly from the first compressor 118 to the outdoor heat exchanger 126 without passing through the second compressor 124.

Referring to FIG. 1A, the outdoor heat exchanger 126 may be a high-side heat exchanger, such as a gas cooler or a condenser, and generally includes one or more coils and fans to move the air across the coils. The outdoor heat exchanger 126 is fluidly coupled with the refrigerant conduit subsystem 102. The outdoor heat exchanger 126 is in signal communication with the controller 140 using wired and/or wireless connection. The controller 140 may send electronic signals to the outdoor heat exchanger 126 to control the speed of the fans based on temperature conditions. The outdoor heat exchanger 126 is configured to transfer heat from the refrigerant into the surrounding outdoor environment. The outdoor heat exchanger 126 removes heat from the refrigerant. When heat is removed from the refrigerant, the refrigerant is cooled. The outdoor heat exchanger 126 may be operated as a condenser and/or a gas cooler. When operating as a condenser, outdoor heat exchanger 126 cools the refrigerant such that the state of the refrigerant changes from a gas to a liquid. When operating as a gas cooler, outdoor heat exchanger 126 cools gaseous refrigerant and the refrigerant remains a gas. In certain configurations, the outdoor heat exchanger 126 is positioned such that heat removed from the refrigerant may be discharged into the air. For example, the outdoor heat exchanger 126 may be positioned on a rooftop so that heat removed from the refrigerant may be discharged into the air. As another example, the outdoor heat exchanger 126 may be positioned external to a building and/or on the side of a building. This disclosure contemplates any suitable refrigerant (e.g., carbon dioxide) being used in any of the disclosed cooling systems. The refrigeration system 100 may include any appropriate number of outdoor heat exchangers 126 with the same or a similar configuration to that shown for the example the outdoor heat exchanger 126 in each of FIGS. 1A and 1B.

The valve 130 may be a high-pressure valve, a motorized valve, a solenoid valve, an EEV, a TXV, or any other suitable valve configured to control the flow of the refrigerant. The valve 130 is fluidly coupled with the refrigerant conduit subsystem 102. The valve 130 is in signal communication with the controller 140 using wired and/or wireless connection. The valve 130 is positioned downstream of the outdoor heat exchanger 126 and configured to receive the refrigerant discharged from the outdoor heat exchanger 126. The valve 130 is configured to reduce the pressure of the refrigerant received from the outdoor heat exchanger 126 before it reaches the flash tank 112. The valve 130 may regulate the pressure of the refrigerant.

Referring to FIG. 1A, in the high ambient temperature mode 104, the valve 130 may be configured to maintain a high pressure (e.g., 80, 90, 100 bars) for the refrigerant before it flows to the flash tank 112. Referring to FIG. 1B, in the low ambient temperature mode 106, the valve 130 may be configured to be fully opened to allow unrestricted flow of the refrigerant. In some

embodiments, the valve 130 may be automatically adjusted based on an operating pressure differential configured in the system 100, e.g., in case of TXV or high-pressure valve 130. In some embodiments, the controller 140 may send electronic signals to the valve 130 to control the flow of the refrigerant based on the configured operating pressure differential, e.g., in case of EEV valve 130.

Referring to FIG. 1A, the temperature sensor circuit 128 may include a temperature sensing circuitry. The temperature sensor circuit 128 may be implemented by a hardware circuit and configured to detect the ambient temperature 154 within a vicinity of the refrigeration system 100, e.g., the temperature 154 of the air surrounding the outdoor heat exchanger 126 within a detection range, such as within ten inches, five feet, or any other detection range. The temperature sensor circuit 128 may include a thermocouple, a thermistor, a semiconductor-based temperature detecting circuit board, or any other type of temperature sensor. The temperature sensor circuit 128 is in signal communication with the controller 140 using wired and/or wireless connection. The temperature sensor circuit 128 may be positioned adjacent to the outdoor heat exchanger 126. The temperature sensor circuit 128 may be attached on a surface and/or the outdoor heat exchanger 126 using any appropriate means (e.g., threaded connections, clamps, adhesives, or the like). The temperature sensor circuit 128 is configured to detect the ambient temperature 154 periodically (e.g., every second, every minute, etc.) or on demand (e.g., in response to a request from a user provided to the controller 140 or a thermostat). The temperature sensor circuit 128 may provide the detected temperature 154 to the controller 140. The controller 140 may store the data points indicating a set of detected ambient temperature 154 in the ambient temperature data 152.

The controller 140 is communicatively coupled to other components in the refrigeration system 100 via wired and/or wireless connection. The controller 140 is configured to control the operations of the other components of the refrigeration system 100. In some embodiments, controller 140 can be one or more controllers associated with one or more components of the refrigeration system 100. The controller 140 includes a processor 142 communicatively coupled to and in signal communication with a memory 146 and an input/output (I/O) interface 144. The processor 142 comprises one or more processors. The processor 142 is any electronic circuitry including, but not limited to, state machines, one or more central processing unit (CPU) chips, logic units, cores (e.g., a multi-core processor), field-programmable gate array (FPGAs), application-specific integrated circuits (ASICs), or digital signal processors (DSPs) that communicatively couples to memory 146 and controls the operation of refrigeration system 100. The processor 142 may be a programmable logic device, a microcontroller, a microprocessor, or any suitable combination of the preceding. The one or more processors are configured to process data and may be implemented in hardware or software. For example, the processor 142 may be 8-bit, 16-bit, 32-bit, 64-bit or of any other suitable architecture. The processor 142 may include an arithmetic logic unit (ALU) for performing arithmetic and logic operations, processor registers that supply operands to the ALU and store the results of ALU operations, and a control unit that fetches instructions from memory 146 and executes them by directing the coordinated operations of the ALU, registers, and other components. The processor 142 may include other hardware and software that operates to process information, control the refrigeration system 100, and perform any of the functions described herein. The processor 142 may be configured to execute software instructions to perform operations of the controller 140. For example, the processor 142 may be configured to execute the software instructions 148 to cause the refrigeration system 100 to enter the high ambient temperature mode 104 (see FIG. 1A) or the low ambient temperature mode 106 (see FIG. 1B) depending on the detected ambient temperature 154. The processor 142 may execute code/software instructions 148 to perform any of its operations. The processor 142 is not limited to a single processing device and may encompass multiple processing devices. The processor 142 may be configured to perform one or more operations of the controller 140 described in FIGS. 1A and 1B, and one or more operations of the method 200 described in FIG. 2.

The memory 146 may be a non-transitory computer-readable medium. The memory 146 includes one or more disks, tape drives, or solid-state drives, and may be used as an overflow data storage device, to store programs when such programs are selected for execution, and to store instructions and data that are read during program execution. The memory 146 may be volatile or non-volatile and may comprise read-only memory (ROM), random-access memory (RAM), ternary content-addressable memory (TCAM), dynamic random-access memory (DRAM), and static random-access memory (SRAM). The memory 146 is operable to store any suitable set of instructions, logic, rules, and/or code for executing the functions described in this disclosure. For example, the memory 146 may store software instructions 148, electronic signals 150a-b, ambient temperature data 152, threshold temperature 156, and/or other data, instructions, and operating parameters for components in the system 100.

The I/O interface 144 is configured to communicate data and signals with other devices. For example, the I/O interface 144 may be configured to communicate electrical signals with the other components of the Refrigeration systems 100. The I/O interface 144 may comprise ports and/or terminals for establishing signal communications between the controller 140 and other devices. The I/O interface 144 may be configured to enable wired and/or wireless communications. Connections between various components of the refrigeration system 100 and between components of system 100 may be wired or wireless. For example, conventional cable and contacts may be used to couple the controller 140 and various components of the refrigeration system 100. In some embodiments, a wireless connection may be employed to provide at least some or all of the connections between components of the refrigeration system 100. In some embodiments, a data bus may couple various components of the refrigeration system 100 together such that data is communicated therebetween. In some embodiment, the data bus may include, for example, any combination of hardware, software embedded in a computer-readable medium, or encoded logic incorporated in hardware or otherwise stored (e.g., firmware) to couple components of the refrigeration system 100 to each other.

As an example and not by way of limitation, the data bus may include an accelerated graphics port (AGP) or other graphics bus, a controller area network (CAN) bus, a front-side bus (FSB), a hypertransport (HT) interconnect, an infiniband interconnect, a low-pin-count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a serial advanced technology attachment (SATA) bus, a video electronics standards association local (VLB) bus, or any other suitable bus or a combination of two or more of these. In various embodiments, the data bus may include any number, type, or configuration of data buses, where appropriate. In certain embodiments, one or more data buses (which may each include an address bus and a data bus) may couple the controller 140 to other components of the refrigeration system 100.

Operational Flow for Operating in High or Low Ambient Temperature Mode

In operation, the controller 140 may operate the refrigeration system 100 in either high ambient temperature mode 104 (see FIG. 1A) or low ambient temperature mode 106 (see FIG. 1B) depending on the detected ambient temperature 154. To this end, the controller 140 may monitor the ambient temperature 154 detected and received from the temperature sensor circuit 128. The controller 140 may receive the ambient temperature 154 and determine whether the detected ambient temperature 154 is less than a threshold temperature 156. In some examples, the threshold temperature 156 may be 58, 59, 60, 61 degrees or any other temperature. In response to determining that the detected ambient temperature 154 is less than the threshold temperature 156, the controller 140 may initiate operating the refrigeration system 100 in the low ambient temperature mode 106 as shown in FIG. 1B.

Operating in Low Ambient Temperature Mode

Referring to FIG. 1B, when operating in the low ambient temperature mode 106, the controller 140 may communicate a first electronic signal 150a to the switching valve 122 to bypass the second compressor 124 and allow the working fluid (e.g., the refrigerant) to flow from the switching valve 122 toward the outdoor heat exchanger 126. The first electronic signal 150a may cause the first outlet 134a of the switching valve 122 to at least partially close and the second outlet 134b of the switching valve 122 to at least partially open. This results in the refrigerant flow from the inlet 132 of the switching valve 122 to the outdoor heat exchanger 126 (via the opened second outlet 134b) and restrict or prevent the refrigerant flow from the inlet 132 of the switching valve 122 to the second compressor 124 (via the closed first outlet 134a). In this mode, the first compressor 118 handles the compression of the refrigerant. The controller 140 operates the refrigeration system 100 in the low ambient temperature mode 106 until the ambient temperature 154 increases to be more than or equal to the threshold temperature 156.

The outdoor heat exchanger 126 may receive the refrigerant from the first compressor 118 and transfer the heat from the refrigerant to the surrounding outdoor air. This cools the refrigerant before it goes to a next cycle in the system 100. The cooled refrigerant flows through the valve 130 and then to the flash tank 112, operating as a receiver.

The liquid refrigerant flows from the flash tank 112 to the valve 114 and the indoor heat exchanger 116. The valve 114 may control the flow of the refrigerant flowing into the indoor heat exchanger 116. The indoor heat exchanger 116 may provide conditioned air to the target indoor space when the refrigerant flows through the coils of the indoor heat exchanger 116. As the refrigerant flows through the coils, it absorbs heat from the indoor space, which cools the air in the indoor target space. This raises the temperature of the refrigerant.

The refrigerant flows toward the first compressor 118 and the first compressor 118 compresses the refrigerant to increase its pressure and/or temperature. In configurations where the desuperheater 120 is implemented, the refrigerant may flow from the first compressor 118 to the desuperheater 120 to reduce the temperature of the superheated refrigerant before it continues through the system. The refrigerant is provided from the switching valve 122 to the outdoor heat exchanger 126. This cycle may continue while the ambient temperature 154 is less than the threshold temperature 156.

Operating in High Ambient Temperature Mode

Referring to FIG. 1A, in response to determining that the detected ambient temperature 154 is more than or equal to the threshold temperature 156, the controller 140 may initiate operating the refrigeration system 100 in the high ambient temperature mode 104, as shown in FIG. 1A. To this end, the controller 140 may communicate second electronic signal 150b to the switching valve 122 to allow the refrigerant to flow from the switching valve 122 toward the second compressor 124 before flowing toward the outdoor heat exchanger 126. The second electronic signal 150b may cause the first outlet 134a of the switching valve 122 to at least partially open and the second outlet 134b of the switching valve 122 to at least partially close. This results in the refrigerant flow from the inlet 132 of the switching valve 122 to the second compressor 124 (via the opened first outlet 134a) and restrict or prevent the refrigerant flow from the inlet 132 to the outdoor heat exchanger 126 (via the closed second outlet 134b). In this mode, the first compressor 118 and the second compressor 124 handle the compression of the refrigerant.

The outdoor heat exchanger 126 may receive the refrigerant from the second compressor 124 and transfer the heat from the refrigerant to the surrounding outdoor air, similar to that described above with respect to the operation of the outdoor heat exchanger 126. The cooled refrigerant flows through the valve 130 and then to the flash tank 112. The vapor refrigerant flows from the flash tank 112 towards the second compressor 124 and the liquid refrigerant flows from the flash tank 112 towards the valve 114 and the indoor heat exchanger 116.

The indoor heat exchanger 116 may provide conditioned air to the target indoor space. The refrigerant flows toward the first compressor 118 and the first compressor 118 compresses the refrigerant to increase its pressure and/or temperature. In configurations where the desuperheater 120 is implemented, the refrigerant may flow from the first compressor 118 to the desuperheater 120 to reduce the temperature of the superheated refrigerant before it continues through the system. The second compressor 124 may compress the refrigerant received from the flash tank 112 and the switching valve 122 and provide the compressed refrigerant to the outdoor heat exchanger 126. This cycle may continue while the ambient temperature 154 is more than or equal to the threshold temperature 156. The controller 140 operates the refrigeration system 100 in the high ambient temperature mode 104 until the ambient temperature 154 drops below the threshold temperature 156.

The controller 140 is configured to selectively switch between the low ambient temperature mode 106 (see FIG. 1B) and the high ambient temperature mode 104 (see FIG. 1A) depending on the detected ambient temperature 154. The low ambient temperature mode 106 corresponds to when the detected ambient temperature 154 is less than the threshold temperature 156. The high ambient temperature mode 104 corresponds to when the detected ambient temperature 154 is more than or equal to the threshold temperature 156.

Example Method for Switching Between Single and Multiple Compressor Cycles Based on Ambient Temperature

FIG. 2 illustrates a flowchart of an example method 200 of operating the system 100 of FIGS. 1A and 1B for switching between single and multiple compressor cycles based on ambient temperature. The method 200 may be performed by the controller 140 (see FIGS. 1A and 1B) when one or more processors (e.g., processor 142 of FIGS. 1A and 1B) execute software instructions (e.g., software instructions 148) stored in one or more memories (e.g., memory 146 of FIGS. 1A and 1B). The method 200 may include operations 202-208.

At operation 202, the controller 140 may receive an ambient temperature 154 from the temperature sensor circuit 128, similar to that described in FIGS. 1A and 1B.

At operation 204, the controller 140 may determine whether the ambient temperature 154 is less than the threshold temperature 156. If it is determined that the ambient temperature 154 is less than the threshold temperature 156 (“Yes”), the method 200 proceeds to operation 206. Otherwise (“No”), the method 200 proceeds to operation 208.

At operation 206, the controller 140 may communicate the first electronic signal 150a to the switching valve 122 to bypass the second compressor 124 and allow the refrigerant to flow from the switching valve 122 towards the outdoor heat exchanger 126, similar to that described in FIG. 1B.

At operation 208, the controller 140 may communicate the second electronic signal 150b to the switching valve 122 to allow the refrigerant to flow from the switching valve 122 toward the second compressor 124 before flowing toward the outdoor heat exchanger 126, similar to that described in FIG. 1A.

Modifications, additions, or omissions may be made to method 200. Method 200 may include more, fewer, or other operations. For example, operations may be performed in parallel or in any suitable order.

While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated with another system or certain features may be omitted, or not implemented.

In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled or directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.

To aid the Patent Office, and any readers of any patent issued on this application in interpreting the claims appended hereto, applicants note that they do not intend any of the appended claims to invoke 35 U.S.C. § 112(f) as it exists on the date of filing hereof unless the words “means for” or “step for” are explicitly used in the particular claim.