SYSTEMS AND METHODS FOR PUMPED REFRIGERANT ECONOMIZATION SUPERHEAT CONTROL

CROSS REFERENCE TO RELATED APPLICATIONS

[0001]This U.S. Non-Provisional Patent Application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/651,617 filed May 24, 2024, the entire disclosure of which is hereby incorporated by reference.

TECHNICAL FIELD

[0002]The present disclosure relates to control routines of refrigeration systems, and in particular, to systems and methods pumped refrigerant economization superheat control.

BACKGROUND

[0003]A refrigeration system may implement different control routines to control the temperature of refrigerant as it moves throughout the refrigeration system. For example, in single circuit systems, the liquid temperature is controlled to remain at a fixed setpoint (e.g., 37° Fahrenheit (F)). This level of control is needed in refrigeration systems, where maintaining specific temperatures is essential for the correct operation of the systems. In relatively more complex systems that use multiple circuits and have a staged economization feature, the control strategy may involve the liquid temperature in the upstream circuit being controlled at a first temperature (e.g., 45° F.), while the downstream circuit is maintained at a second temperature (e.g., 37° F.). The staged economization is a method used to improve energy efficiency in refrigeration systems by recovering waste heat and using it for pre-cooling the refrigerant, which reduces the load on the condenser.

SUMMARY

[0004]This disclosure relates generally to pumped refrigerant systems.

[0005]An aspect of the disclosed embodiments includes a superheat control circuit of a refrigeration system. The superheat control circuit comprises: a temperature sensor configured to measure a temperature of a refrigerant of the refrigeration system and generate temperature data associated with the measured temperature of the refrigerant; a pressure sensor configured to measure a pressure of the refrigerant and generate pressure data associated with the measured pressure of the refrigerant; and a controller. The controller configured to: receive the temperature data and the pressure data; calculate, based on the temperature data and the pressure data, a superheat value of the refrigerant; and adjust a speed of a fan of a condenser of the refrigeration system based on the calculated superheat value of the refrigerant.

[0006]Another aspect of the disclosed embodiments includes a method for operating a superheat control circuit of a refrigeration system. The method comprises: measuring a temperature of a refrigerant of the refrigeration system; measuring a pressure of the refrigerant; calculating, based on the measured temperature and the measured pressure, a superheat value of the refrigerant; and adjusting, based on calculated superheat value, a speed of a fan of a condenser of the refrigeration system.

[0007]Still yet, another aspect of the disclosed embodiments includes a superheat control circuit of a refrigeration system. The superheat control circuit comprises: a temperature sensor configured to measure temperature of refrigerant of the refrigeration system and generate temperature data associated with the measured temperature of the refrigerant; a pressure sensor configured to measure pressure of the refrigerant and generate pressure data associated with the measured pressure of the refrigerant; and a controller configured to receive the temperature data and the pressure data, calculate, based on the temperature data and the pressure data, a superheat value of the refrigerant, and adjust a speed of a fan of a condenser of the refrigeration system based a comparison of the calculated superheat value of the refrigerant and a superheat setpoint.

[0008]These and other aspects of the present disclosure are disclosed in the following detailed description of the embodiments, the appended claims, and the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]The disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity.

[0010]FIG. 1 generally illustrates a schematic of a refrigeration system, depicting the various components of a refrigeration system, according to the principles of the present disclosure.

[0011]FIG. 2 generally illustrates a schematic of a refrigeration system, depicting the various components of a refrigeration system, according to the principles of the present disclosure.

[0012]FIG. 3 generally illustrates a schematic of a refrigeration system including a staged economization feature, according to the principles of the present disclosure.

[0013]FIGS. 4A and 4B generally illustrate what occurs if a loss of superheat occurs in a refrigeration system, according to the principles of the present disclosure.

[0014]FIG. 5 generally illustrates graphically how a setpoint modifier of a control approach or routine may function, according to the principles of the present disclosure.

[0015]FIG. 6 generally provides a visual illustration of how different control mechanisms cooperate to ensure stable pumped refrigerant economization (PRE) operation as a function of superheat, according to the principles of the present disclosure.

[0016]FIG. 7 illustrates a stepped approach to modifying the condenser fan speed based on the superheat level, according to the principles of the present disclosure.

[0017]FIG. 8 depicts a flowchart of a method for a PRE superheat control routine, according to the principles of the present disclosure.

[0018]FIG. 9 is a block diagram of a computing device, according to the principles of the present disclosure.

[0019]Those skilled in the art will appreciate and understand that, according to common practice, various features of the drawings discussed below are not necessarily drawn to scale, and that dimensions of various features and elements of the drawings may be expanded or reduced to more clearly illustrate the embodiments of the present disclosure described herein.

DETAILED DESCRIPTION

[0020]The following discussion is directed to various embodiments of the disclosure. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment.

[0021]The present specification and accompanying drawings disclose one or more embodiments that incorporate the features of the present disclosure. The scope of the present disclosure is not limited to the disclosed embodiments. The disclosed embodiments merely exemplify the present disclosure, and modified versions of the disclosed embodiments are also encompassed by the present disclosure. Embodiments of the present disclosure are defined by the claims appended hereto.

[0022]References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0023]In the discussion, unless otherwise stated, adjectives such as “substantially,” “approximately,” and “about” modifying a condition or relationship characteristic of a feature or features of an embodiment of the disclosure, are understood to mean that the condition or characteristic is defined to be within tolerances that are acceptable for operation of the embodiment for an application for which it is intended.

[0024]Furthermore, it should be understood that spatial descriptions (e.g., “above,” “below,” “up,” “left,” “right,” “down,” “top,” “bottom,” “vertical,” “horizontal,” etc.) used herein are for purposes of illustration only, and that practical implementations of the structures described herein can be spatially arranged in any orientation or manner.

[0025]The word “example” is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “example” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word “example” is intended to present concepts in a concrete fashion. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless specified otherwise, or clear from context, “X includes A or B” is intended to mean any of the natural inclusive permutations. That is, if X includes A; X includes B; or X includes both A and B, then “X includes A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Moreover, use of the term “an implementation” or “one implementation” throughout is not intended to mean the same embodiment or implementation unless described as such.

[0026]Numerous exemplary embodiments are described as follows. It is noted that any section/subsection headings provided herein are not intended to be limiting. Embodiments are described throughout this document, and any type of embodiment may be included under any section/subsection. Furthermore, embodiments disclosed in any section/subsection may be combined with any other embodiments described in the same section/subsection and/or a different section/subsection in any manner.

[0027]As described, a refrigeration system may implement different control routines to control the temperature of refrigerant as it moves throughout the refrigeration system. For example, in single circuit systems, the liquid temperature is controlled to remain at a fixed setpoint (e.g., 37° F.). This level of control is needed in refrigeration systems, where maintaining specific temperatures is essential for the correct operation of the systems. In relatively more complex systems that use multiple circuits and have a staged economization feature, the control strategy may involve the liquid temperature in the upstream circuit being controlled at a first temperature (e.g., 45° F.), while the downstream circuit is maintained at a second temperature (e.g., 37° F.). The staged economization is a method used to improve energy efficiency in refrigeration systems by recovering waste heat and using it for pre-cooling the refrigerant, which reduces the load on the condenser.

[0028]Nonetheless, as consumer demands evolve, there is an increasing need for even higher efficiency in thermal management systems to accommodate varying operational environments. Controlling superheat from evaporators using condenser fans can significantly enhance energy efficiency. This not only contributes to energy savings but also facilitates a more straightforward and efficient control routine, particularly as supply and return air temperatures fluctuate.

[0029]Accordingly, systems and methods, such as those described herein, configured to provide pumped refrigerant economization superheat control, may be desirable. With reference to FIG. 1 a schematic of a refrigeration system, depicting the various components of a refrigeration system 100, is generally illustrated.

[0030]The refrigeration system 100 may be configured to manage a condenser fan to ensure that refrigerant temperature is maintained at a predetermined superheat setpoint during a pumped refrigerant economization (PRE) process. Superheat, as referenced herein, refers to the temperature of a vapor above its boiling point at a given pressure. In the context of a refrigeration cycle, it measures how much the refrigerant's temperature has risen above its saturation temperature after it has evaporated. The superheat setpoint is the target temperature above the saturation temperature that the system is designed to maintain. The PRE process, as referenced herein, refers to a refrigeration system component that improves energy efficiency by using a pump to circulate refrigerant through an economizer heat exchange. This process may involve pre-cooling the compressed refrigerant before it enters a condenser. In some embodiments, a pump is not required for this control scheme. This control scheme could work for thermosyphons as well.

[0031]The refrigeration system 100 may include a pump 102, an evaporator (EVAP) 104, a condenser (COND) 106, a compressor (COMP) 108, and a receiver 110, along with piping and valves that connect these components. The evaporator 104 and the compressor 108 are components of the refrigeration system 100 located in an indoor space 120. Although the refrigeration system 100 is shown to include the receiver 110, in some embodiments, the refrigeration system 100 may be implemented without a receiver. Additionally, or alternatively, in some embodiments, compressors may be located outside with the condenser (e.g., as is typical for residential heating, ventilation, and air conditioning (HVAC) systems).

[0032]The pump 102 is configured to circulate refrigerant throughout the refrigeration system 100. For example, the pump 102 may move the refrigerant to the evaporator 104 and from there through the refrigeration system 100. The evaporator 104 is a heat exchanger where the refrigerant absorbs heat from the environment being cooled. For example, the evaporator 104 is configured to cause the refrigerant to evaporate, moving from a liquid to a gas phase, which removes heat from the area being cooled. The compressor 108 is configured to increase the pressure of the refrigerant gas, which also raises its temperature. Compressor and pump operation may be mutually exclusive. For example, the compressor runs when the outdoor temperatures are high and the pump runs when the outdoor temperatures are low enough to support the PRE process. This allows for the refrigerant to release its absorbed heat in the condenser 106. The condenser 106 is another heat exchanger where the high-pressure refrigerant gas is condensed into a liquid as it releases the heat that was absorbed in the evaporator 104. The receiver 110 is configured to store the liquid refrigerant that exits the condenser 106 and ensure that the right amount of refrigerant is supplied to the refrigeration system 100.

[0033]The refrigeration system 100 may include a condenser fan 112, a controller 114, a temperature sensor 116, and a pressure sensor 118. The condenser fan 112 is configured to assist in the heat exchange process occurring at the condenser 106 by blowing air across condenser coils of the condenser 106, helping to dissipate the heat more quickly. For example, the speed of the condenser fan 112 can be varied to control the rate at which heat is removed. Controller 114 is configured to monitor superheat of the refrigerant and compare it to a superheat setpoint.

[0034]In some embodiments, the controller 114 may be a Proportional-Integral-Derivative (PID) controller, a type of feedback control loop. A PID controller is designed to maintain a desired setpoint by adjusting the control variable, such as the speed of the condenser fan or a pump, based on the difference between the desired setpoint and the measured variable.

[0035]For example, at the evaporator 104, refrigerant absorbs heat, which causes the refrigerant to boil and evaporate. As described, superheat refers to additional heat that the refrigerant gas absorbs above its boiling point while still in the evaporator 104. The refrigerant, now a superheated vapor, is drawn into the compressor 108. When the compressor is not running, the vapor bypasses the compressor (e.g., a small portion moves through the compressor). The compressor 108 is configured to compress the superheated vapor, which further increases the pressure and temperature. The high-temperature, high-pressure superheated vapor then flows into the condenser 106. In the condenser 106, the refrigerant releases the heat it absorbed in the evaporator 104 during the superheating process. As it cools, it condenses into a high pressure liquid.

[0036]The condenser fan 112 is configured to remove heat from the refrigerant by passing air over condenser coils of the condenser 106. The controller 114 is further configured to adjust a speed of the condenser fan 112 to control the temperature of the refrigerant, ensuring it condenses properly and exits the condenser at the correct temperature and pressure. The temperature sensor 116 is configured to measure the temperature of the refrigerant prior to it entering the condenser 106 and provide the temperature data to the controller 114. The pressure sensor 118 is configured to measure the pressure of the refrigerant prior to it entering the condenser 106 and provide the pressure data to the controller 114. Pressure can affect the temperature at which the refrigerant evaporates and condenses.

[0037]The controller 114 may then use the temperature and pressure data to adjust the speed of the condenser fan 112 accordingly. For example, in some embodiments, the controller 114 receives temperature and pressure data, calculates, based on the temperature data and the pressure data, a superheat value of the refrigerant (e.g., a difference between the actual temperature of refrigerant vapor at a certain point and the saturation temperature of the refrigerant), and compares the calculated superheat value to a predefined setpoint (such as a superheat setpoint). More specifically, a superheat value is the temperature of a vapor above its boiling point at a given pressure. In the context of a refrigeration cycle, superheat value measures how much the refrigerant's temperature has risen above the refrigerant's saturation temperature after the refrigerant has evaporated. The superheat setpoint is the target temperature above the saturation temperature that the system is designed to maintain.

[0038]If the superheat value is higher or lower than the predefined setpoint, the controller determines how much adjustment of the fan speed of the condenser fan 112 is needed to bring the superheat value to the predefined setpoint. Based on the calculations, the controller 114 may provide a command to an actuator connected to the condenser fan 112. The actuator may increase the speed of the condenser fan 112 to increase the rate of heat removal from the condenser 106, causing the refrigerant temperature and pressure to lower. In contrast, the actuator may lower the speed of the condenser fan 112 to lower the rate of heat removal from the condenser 106, causing the refrigerant temperature and pressure to increase.

[0039]In some embodiments, condenser fan speed may be controlled by superheat entering the condenser at a setpoint (e.g., of 5±1° F.). This will allow for the most efficient condenser fan operation. This also allows for sensible cooling of the refrigerant in the discharge/vapor line.

[0040]FIG. 2 generally illustrates a schematic of a refrigeration system, depicting the various components of a refrigeration system 200. In some embodiments, the temperature and pressure of the refrigerant can be measured at various points in the refrigeration system 200. For example, in FIG. 2, the fan speed of the condenser fan 112 is regulated based on the superheat level—specifically, the temperature and pressure of the refrigerant vapor as it exits (e.g., after the refrigerant exits) the evaporator 104 and enters (e.g., before the refrigerant enters) the compressor 108. A temperature sensor 202 is configured to measure the temperature of the refrigerant, and a pressure sensor 204 is configured to measure the pressure of the refrigerant.

[0041]Further, in some embodiments, the refrigeration system 200 may continuously monitor the temperature and pressure conditions and adjust the fan speed accordingly. This allows for the refrigeration system 200 to adapt as the load on the refrigeration system 200 changes or as other environmental conditions vary. This superheat control method improves efficiency. This improvement in efficiency comes from the condenser 106 being able to turn down more quickly to meet the superheat setpoint. This cost savings would be further increased if the system utilized staged economization (i.e., two circuits).

[0042]FIG. 3 generally illustrates a schematic of a refrigeration system including a staged economization feature. Similar to FIG. 1, refrigeration system 300 in FIG. 3 also includes a condenser fan speed control circuit, which includes the condenser fan 112, the controller 114, the temperature sensor 116, and the pressure sensor 118.

[0043]Refrigeration system 300 also includes a pump speed control circuit including controller 302, Call-For-Cooling (CFC) 304, and Electronic Expansion Valve (EEV) 306. In some embodiments, a Thermal Expansion Valve (TEV) and a solenoid valve bypassing around the TEV may be used in place of an Electronic Expansion Valve (EEV). Controller 302 is configured to adjust the speed of the pump 102 to meet cooling demands, CFC 304, dictated by customer requirements. EEV or solenoid is set to a fixed position (such as fully open) to reduce the pump head pressure, allowing the pump to operate more efficiently, likely at a lower power level. These controls enhance the efficiency of refrigeration system 300 by optimizing the refrigerant temperature and pressure throughout the refrigeration cycle.

[0044]To help further illustrate, controller 302 may receive a signal that cooling is required from CFC 304. This may be triggered by a thermostat or a temperature sensor in the indoor space 120 that needs to be cooled. This signal indicates that the indoor temperature has risen above the desired setpoint. In response to the CFC 304, controller 302 may adjust the speed of the pump 102. If more cooling is needed, the speed of the pump 102 increases to circulate more refrigerant though refrigeration system 300. Conversely, if less cooling is needed, the speed of the pump 102 decreases.

[0045]Additionally, a position of EEV 306 may be set to a fixed position or sizing of solenoid valve, which could be fully open or another specific setting, to ensure that the refrigerant flow is maximized or optimized as required. By fixing the position of EEV 306, refrigeration system 300 helps to minimize the resistance against which the pump 102 has to work.

[0046]In some embodiments, while operating in PRE, experiencing a loss of superheat at the evaporators exit may need to be prevented. FIGS. 4A and 4B generally illustrates what occurs if a loss of superheat occurs in a refrigeration system. In particular, FIG. 4A depicts a refrigeration system during normal operation, and FIG. 4B depicts a refrigeration system during the loss of superheat. As illustrated in FIG. 4B, if a loss of superheat occurs, Net Positive Suction Head Available (NPSHa), at the pump inlet will fall below, Net Positive Suction Head Required, (NPSHr) and flow will be lost. To prevent the loss of superheat at the exit of the evaporator, the supply fan and pump may need to be throttled accordingly. The pump speed can decrease as quickly as possible without issue. However, when the pump speed is being increased it may need to be throttled to prevent loss of super-heat as the evaporate exits. The supply fan can be increased as quickly as possible without issue. However, when the supply fan speed is being decreased it may need to be throttled to prevent loss of super-heat as the evaporate exits.

[0047]In some embodiments, if too much heat is being rejected from the discharge/vapor line due to either poor insulation, long indoor sections, high temperatures (from chases) superheat could be lost at the evaporators exit. To address this, the controller 114 or controller 302 of FIGS. 1-3 can be configured to adjust condenser fan speed controls to a superheat setpoint (e.g., of 5±1° F.) at the lowest location reading the lowest measurement, and switching between either entering the condenser or exiting the evaporator with a hysteresis to prevent erratic switch overs.

[0048]In some embodiments, a control approach for a refrigeration system that adjusts the refrigerant temperature setpoint dynamically, based on superheat, may be implemented. The control approach may also include adapting the setpoint based on various factors, such as ambient air temperature, return and supply air temperatures, and airflow across an evaporator. The control approach may involve a Proportional-Integral control algorithm and a computational process that could adjust the setpoint based on data recorded over a predetermined time period (e.g., the last minute). For example, the control approach may include: recording the data from the predetermined time period (such as over the last minute), taking the minimum value of the superheat from this data, and applying this value to a mapping function to adjust the setpoint. The controller 114 or controller 302 may implement the control approach.

[0049]Further, in some embodiments, the control approach may include a setpoint modifier which could be a linear mapping function. For example, FIG. 5 depicts graphically how the setpoint modifier may function. In FIG. 5, the x-axis, labeled “SH” for superheat and the y-axis shows the modification to the refrigerant temperature setpoint. As depicted in FIG. 5, the plot indicates how the refrigerant temperature setpoint may be adjusted based on the superheat value. For instance, with continued reference to FIG. 5, if the superheat is high enough, a refrigerant temperature setpoint (SP) may be increased, and if the superheat (SH) is lower than a given threshold, the current refrigerant temperature SP may be decreased to ensure correct PRE operation. Additionally, ±0.9 R deadband on the plot represents a range around the setpoint within which no adjustment to the control output would be made. In some embodiments, an allowed operational interval for the refrigerant temperature SP may be implemented (e.g., minimum and maximum operation values) to ensure there would be no numerical issues with the controller and allows the operation range to be controlled by a qualified user.

[0050]In some embodiments, another control approach may be implemented that involves fully switching from refrigerant temperature SP to superheat control (e.g., PRE mode, condenser fan operation). This control approach can involve continuous operation or discrete operation. For example, in one instance of continuous operation, a PID controller may continuously control superheat at a fixed setpoint.

[0051]FIG. 6 provides a visual illustration of how different control mechanisms cooperate to ensure stable PRE operation as a function of the superheat. As an illustrative example, in FIG. 6, if the SH is lower than 9K (Rankine), the EEV valve will start to close to increase the SH. There may also be a mechanism which dynamically sets a maximum allowed EEV opening during the operation to ensure correct PRE functioning. In addition, with continued reference to FIG. 6, if the SH is above 9 R, EEV is used to control the differential pressure (DP) across the pump to keep a certain pressure increase. If SH setpoint is set to 14.4 R for the condenser, energy will be saved while keeping the operation of the PRE mode stable (e.g., no unwanted intervention in the EEV operation).

[0052]In the case of colder ambient air temperature, the use of fixed refrigerant temperature setpoint approach could yield extremely high superheat values. By controlling the superheat, the refrigerant temperature may be controlled indirectly. With lower superheat, higher refrigerant temperature could be achieved by lower condenser fan speeds in case of same ambient air temperature. Lower fan speed translates to lower energy consumption, while maintaining the quality of the PRE operation (e.g., required heat load delivered). By controlling the SH directly, changing ambient air temperature, return and supply air temperature, and air flow is dynamically being reacted to.

[0053]FIG. 7 illustrates a stepped approach to modifying the condenser fan speed based on the superheat level. In case of a discrete approach, this approach may involve replacing the PID controller with a step approach. This control approach would modify the condenser fan speed also as a function of superheat but in a discrete manner. For example, this approach may involve steps or specific points at which the condenser fan speed and the EEV are adjusted in response to changes in superheat. For example, with reference to FIG. 7, there is an increase in fan speed as the superheat rises above a setpoint, with a 50% proportional band indicating that when the superheat is within 50% of the target, the fan speed increases to 100% rate of change, represented in by the Increment Area in FIG. 7. Conversely, there is a decrease in fan speed as the superheat falls below the setpoint, with the fan speed change rate reaching 0% as the superheat reaches the setpoint,, represented in by the Decrement Area in FIG. 7. In some embodiments, the ramping may not be symmetrical (e.g., increasing more rapidly than it decreases); the control response may be tailored to a refrigeration system's needs.

[0054]In some embodiments, another control approach may be implemented. This control approach of the PRE operation may involve: an evaporator controlled independently (e.g., by return air temperature); pump is controlled by CFC (e.g., PID output to control the supply air temperature); differential pressure is controlled by the EEV valve; minimum superheat is controlled by the EEV valve and complimentary logic to limit the maximum opening of the EEV; a condenser fan speed is controlled by the superheat value (high superheat allow for lower condenser ramping, thereby, causing lower energy consumption).

[0055]Each of the above listed control approaches can sufficiently support the PRE operation regime. Different methods could be used for units of different types (e.g., number of circuits), size (e.g., capacity), geographical installation location, etc.

[0056]FIG. 8 is a flowchart generally illustrated a method 800 for a PRE superheat control routine, according the principles of the present disclosure. At 802, the method 800 measures a temperature of refrigerant of a refrigeration system.

[0057]At 804, the method 800, measures a pressure of the refrigerant.

[0058]At 806, the method 800, calculates a superheat of the refrigerant based on the measured temperature and the measured pressure.

[0059]At 808, the method 800, adjusts a speed of a fan of a condenser of the refrigeration system based on calculated superheat value.

[0060]FIG. 9 generally illustrates a processor-based computer system 900 that may be used to implement various embodiments described herein, such as any of the embodiments described in the above and in reference to FIGS. 1-8. For example, the processor-based computer system 900 may be used to implement any of the components of the refrigeration system 100 and the refrigeration system 200 as described above in reference to FIGS. 1-8. The description of the processor-based computer system 900 provided herein is provided for purposes of illustration and is not intended to be limiting. Embodiments may be implemented in further types of computer systems, as would be known to persons skilled in the relevant art(s).

[0061]As shown in FIG. 9, the processor-based computer system 900 includes one or more processors, referred to as a processor circuit 902, a system memory 904, and a bus 906 that couples various system components including the system memory 904 to the processor circuit 902. The processor circuit 902 is an electrical and/or optical circuit implemented in one or more physical hardware electrical circuit device elements and/or integrated circuit devices (semiconductor material chips or dies) as a central processing unit (CPU), a microcontroller, a microprocessor, and/or other physical hardware processor circuit. The processor circuit 902 may execute program code stored in a computer readable medium, such as program code of the operating system 930, the application programs 932, the other programs 934, etc. The bus 906 represents one or more of any of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, and a processor or local bus using any of a variety of bus architectures. The system memory 904 includes a read only memory (ROM) 908 and a random access memory (RAM) 910. A basic input/output system 912 (BIOS) is stored in the ROM 908.

[0062]The processor-based computer system 900 also has one or more of the following drives: a the hard disk drive 914 for reading from and writing to a hard disk, a magnetic disk drive 916 for reading from or writing to a removable magnetic disk 918, and an optical disk drive 920 for reading from or writing to a removable optical disk 922 such as a CD ROM, DVD ROM, or other optical media. The hard disk drive 914, the magnetic disk drive 916, and the optical disk drive 920 are connected to the bus 906 by a hard disk drive interface 924, a magnetic disk drive interface 926, and an optical drive interface 928, respectively. The drives and their associated computer-readable media provide nonvolatile storage of computer-readable instructions, data structures, program modules and other data for the computer. Although a hard disk, a removable magnetic disk and a removable optical disk are described, other types of hardware-based computer-readable storage media can be used to store data, such as flash memory cards, digital video disks, RAMS, ROMs, and other hardware storage media.

[0063]A number of program modules may be stored on the hard disk, magnetic disk, optical disk, ROM, or RAM. These programs include an operating system 930, one or more application programs 932, the other programs 934, and program data 936. The application programs 932 or the other programs 934 may include, for example, computer program logic (e.g., computer program code or instructions) for implementing the systems described above, including the embodiments described in reference to FIGS. 1-8.

[0064]A user may enter commands and information into the processor-based computer system 900 through input devices such as a keyboard 938 and a pointing device 940. Other input devices (not shown) may include a microphone, joystick, game pad, satellite dish, scanner, a touch screen and/or touch pad, a voice recognition system to receive voice input, a gesture recognition system to receive gesture input, or the like. These and other input devices are often connected to processor the processor circuit 902 through a serial port interface 942 that is coupled to the bus 906, but may be connected by other interfaces, such as a parallel port, game port, or a universal serial bus (USB).

[0065]A display screen 944 is also connected to the bus 906 via an interface, such as a video adapter 946. The display screen 944 may be external to, or incorporated in the processor-based computer system 900. The display screen 944 may display information, as well as being a user interface for receiving user commands and/or other information (e.g., by touch, finger gestures, virtual keyboard, etc.). In addition to the display screen 944, the processor-based computer system 900 may include other peripheral output devices (not shown) such as speakers and printers.

[0066]The processor-based computer system 900 is connected to a network 948 (e.g., the Internet) through an adaptor or a network interface 950, a modem 952, or other means for establishing communications over the network. The modem 952, which may be internal or external, may be connected to bus 406 via the serial port interface 942, as shown in FIG. 9, or may be connected to the bus 906 using another interface type, including a parallel interface.

[0067]As used herein, the terms “computer program medium,” “computer-readable medium,” and “computer-readable storage medium” are used to generally refer to physical hardware media such as the hard disk associated with the hard disk drive 914, the removable magnetic disk 918, the removable optical disk 922, other physical hardware media such as RAMs, ROMs, flash memory cards, digital video disks, zip disks, MEMs, nanotechnology-based storage devices, and further types of physical/tangible hardware storage media (including the system memory 904 of FIG. 9). Such computer-readable storage media are distinguished from and non-overlapping with communication media (do not include communication media). Communication media typically embodies computer-readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wireless media such as acoustic, RF, infrared and other wireless media, as well as wired media. Embodiments are also directed to such communication media.

[0068]As noted above, computer programs and modules (including the application programs 932 and the other programs 934) may be stored on the hard disk, magnetic disk, optical disk, ROM, RAM, or other hardware storage medium. Such computer programs may also be received via the network interface 950, the serial port interface 942, or any other interface type. Such computer programs, when executed or loaded by an application, enable the processor-based computer system 900 to implement features of embodiments discussed herein. Accordingly, such computer programs represent controllers of the processor-based computer system 900.

[0069]Embodiments are also directed to computer program products comprising computer code or instructions stored on any computer-readable medium. Such computer program products include hard disk drives, optical disk drives, memory device packages, portable memory sticks, memory cards, and other types of physical storage hardware.

[0070]In some embodiments, a superheat control circuit of a refrigeration system, the superheat control circuit comprises: a temperature sensor configured to measure a temperature of a refrigerant of the refrigeration system and generate temperature data associated with the measured temperature of the refrigerant; a pressure sensor configured to measure a pressure of the refrigerant and generate pressure data associated with the measured pressure of the refrigerant; and a controller configured to: receive the temperature data and the pressure data; calculate, based on the temperature data and the pressure data, a superheat value of the refrigerant; and adjust a speed of a fan of a condenser of the refrigeration system based on the calculated superheat value of the refrigerant.

[0071]In some embodiments, in the superheat control circuit described above, the measured temperature and the measured pressure of the refrigerant are measured prior to the refrigerant entering the condenser.

[0072]In some embodiments, in the superheat control circuit described above, the measured temperature and the measured pressure of the refrigerant are measured as the refrigerant exits an evaporator of the refrigeration system and enters a compressor of the refrigeration system.

[0073]In some embodiments, in the superheat control circuit described above, the controller is further configured to adjust the speed of the fan based on the calculated superheat value.

[0074]In some embodiments, in the superheat control circuit described above, the controller is further configured to adjust the speed of the fan based on a superheat setpoint.

[0075]In some embodiments, in the superheat control circuit described above, the superheat setpoint is adjusted based on at least one of ambient air temperature, return and supply air temperatures, or airflow across an evaporator of the refrigeration system.

[0076]In some embodiments, in the superheat control circuit further comprises: an electronic expansion valve configured to control flow of the refrigerant entering an evaporator of the refrigeration system, and wherein the controller is further configured to adjust a position of the electronic expansion valve based on the calculated superheat value to adjust the flow of the refrigerant.

[0077]In some embodiments, in the superheat control circuit described above, the controller is further configured to adjust the speed of the fan based on a mapping function, the mapping function being based on a relationship between the calculated superheat value of the refrigerant and a refrigerant temperature setpoint.

[0078]In some embodiments, a method for operating a superheat control circuit of a refrigeration system, the method comprises: measuring a temperature of a refrigerant of the refrigeration system; measuring a pressure of the refrigerant; calculating, based on the measured temperature and the measured pressure, a superheat value of the refrigerant; and adjusting, based on calculated superheat value, a speed of a fan of a condenser of the refrigeration system.

[0079]In some embodiments, in the method described above, the measured temperature and the measured pressure of the refrigerant are measured prior to the refrigerant entering the condenser.

[0080]In some embodiments, in the method described above, the measured temperature and the measured pressure of the refrigerant are measured as the refrigerant exits an evaporator of the refrigeration system and enters a compressor of the refrigeration system.

[0081]In some embodiments, in the method described above, the method further comprises: adjusting the speed of the fan in a stepped response based on the calculated superheat value.

[0082]In some embodiments, in the method described above, the method further comprises: adjusting the speed of the fan based on a superheat setpoint.

[0083]In some embodiments, in the method described above, the method further comprises: adjusting the superheat setpoint based on at least one of ambient air temperature, return and supply air temperatures, or airflow across an evaporator of the refrigeration system.

[0084]In some embodiments, in the method described above, the method further comprises: controlling, through an electronic expansion valve, flow of the refrigerant entering an evaporator of the refrigeration system; and adjusting a position of the electronic expansion valve based on the calculated superheat value to adjust the flow of the refrigerant.

[0085]In some embodiments, in the method described above, the method further comprises: adjusting the speed of the fan based on a mapping function, the mapping function being based on a relationship between the calculated superheat value of the refrigerant and a refrigerant temperature setpoint.

[0086]In some embodiments, a superheat control circuit of a refrigeration system comprises: a temperature sensor configured to measure temperature of refrigerant of the refrigeration system and generate temperature data associated with the measured temperature of the refrigerant; a pressure sensor configured to measure pressure of the refrigerant and generate pressure data associated with the measured pressure of the refrigerant; and a controller configured to receive the temperature data and the pressure data, calculate, based on the temperature data and the pressure data, a superheat value of the refrigerant, and adjust a speed of a fan of a condenser of the refrigeration system based a comparison of the calculated superheat value of the refrigerant and a superheat setpoint.

[0087]In some embodiments, in the superheat control circuit described above, the measured temperature and the measured pressure of the refrigerant are measured prior to the refrigerant entering the condenser.

[0088]In some embodiments, in the superheat control circuit described above, the measured temperature and the measured pressure of the refrigerant are measured as the refrigerant exits an evaporator of the refrigeration system and enters a compressor of the refrigeration system.

[0089]In some embodiments, in the superheat control circuit described above, the controller is further configured to adjust the speed of the fan in a stepped response based on the calculated superheat value.

[0090]Implementations of the systems, algorithms, methods, instructions, etc., described herein can be realized in hardware, software, or any combination thereof. The hardware can include, for example, computers, intellectual property (IP) cores, application-specific integrated circuits (ASICs), programmable logic arrays, optical processors, programmable logic controllers, microcode, microcontrollers, servers, microprocessors, digital signal processors, or any other suitable circuit. In the claims, the term “processor” should be understood as encompassing any of the foregoing hardware, either singly or in combination. The terms “signal” and “data” are used interchangeably.

[0091]As used herein, the term module can include a packaged functional hardware unit designed for use with other components, a set of instructions executable by a controller (e.g., a processor executing software or firmware), processing circuitry configured to perform a particular function, and a self-contained hardware or software component that interfaces with a larger system. For example, a module can include an application specific integrated circuit (ASIC), a Field Programmable Gate Array (FPGA), a circuit, digital logic circuit, an analog circuit, a combination of discrete circuits, gates, and other types of hardware or combination thereof. In other embodiments, a module can include memory that stores instructions executable by a controller to implement a feature of the module.

[0092]Further, in one aspect, for example, systems described herein can be implemented using a general-purpose computer or general-purpose processor with a computer program that, when executed, carries out any of the respective methods, algorithms, and/or instructions described herein. In addition, or alternatively, for example, a special purpose computer/processor can be utilized which can contain other hardware for carrying out any of the methods, algorithms, or instructions described herein.

[0093]Further, all or a portion of implementations of the present disclosure can take the form of a computer program product accessible from, for example, a computer-usable or computer-readable medium. A computer-usable or computer-readable medium can be any device that can, for example, tangibly contain, store, communicate, or transport the program for use by or in connection with any processor. The medium can be, for example, an electronic, magnetic, optical, electromagnetic, or a semiconductor device. Other suitable mediums are also available.

[0094]The above-described embodiments, implementations, and aspects have been described in order to allow easy understanding of the present disclosure and do not limit the present disclosure. On the contrary, the disclosure is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation to encompass all such modifications and equivalent structure as is permitted under the law.