Mechanical relief protection of a co2 system for a power outage

Abstract

A refrigeration system includes a flash tank, a first valve, a safety tank, a controller, and refrigeration components. The flash tank is configured to receive input refrigerant and change the input refrigerant into a first liquid refrigerant and a vapor. The vapor from the flash tank flows through a first valve to the safety tank when the first valve is open, and when the first valve is closed, the vapor is prohibited from flowing to the safety tank. The controller controls the first valve so that the first valve is caused to close when electrical power is provided to the refrigeration components. When electrical power is no longer available, the controller causes the first valve to open. This allows the refrigeration components to continue receiving liquid refrigerant when electrical power is no longer provided.

Description

TECHNICAL FIELD

[0001] This disclosure relates generally to refrigeration systems. More particularly, in certain embodiments, this disclosure relates to mechanical relief protection of a carbon dioxide (CO2) system for a power outage. BACKGROUND

[0002] Refrigeration systems are used to regulate environmental conditions within an enclosed space. Refrigeration systems are used for a variety of applications, such as in supermarkets and warehouses, to cool stored items. For example, refrigeration systems may provide cooling operations for refrigerators and freezers.SUMMARY OF THE DISCLOSURE

[0003] During normal operation, refrigeration systems require electrical power to power components such as compressors. When power outages occur, pressure begins to build in the system as the refrigerant warms up. When this occurs in a flash tank, an associated relief valve often releases some of this pressure to the outside, requiring new refrigerant to be added to the system when power is restored. Further, because of the loss of compression and the rise in temperature, the system is no longer able to provide cooling to a load such as a refrigerated space, potentially resulting in the loss of the product being refrigerated in the refrigerated space.

[0004] Loss of electrical power may be overcome by providing a generator or other forms of backup power, but these have limitations as well. Backup generators may be expensive and require constant maintenance. Further, generators and other forms of backup power may take up valuable real estate. When frequent power outages occur over time, the generators may run out of fuel and no longer be able to provide enough backup power to allow for salvaging any items being refrigerated in the refrigerated space or performing repairs on the power source.

[0005] This disclosure provides technical solutions to the problems of previous technology, including those described above. In one or more embodiments, a refrigeration system is provided that includes a safety tank, which may relieve the buildup of pressure in the flash tank when power is lost and provide additional cooled liquid refrigerant to refrigeration components that may continue to cool the load until power may be restored, using residual cooling in the load. The refrigeration system may include a flash tank, a first valve, a safety tank, a controller, and refrigeration components. The flash tank is configured to receive input refrigerant and change the input refrigerant into a first liquid refrigerant and a vapor. The vapor from the flash tank flows through a first valve to the safety tank when the first valve is open, and when the first valve is closed, the vapor is prohibited from flowing to the safety tank. The controller controls the first valve so that the first valve is closed when electrical power is provided to the refrigeration components. When electrical power is no longer available, the controller causes the first valve to open.

[0006] The system and method provide for relief protection and continued cooling of a load when power is lost without requiring generators and other sources of backup power. Further, unlike other solutions, the system and method do not require extensive changes to the system or additional expensive components. Providing a solution that may be added to already deployed systems to provide more resiliency to power outages without requiring an entirely new system.

[0007] In an embodiment, a refrigeration system is provided. The refrigeration system includes a flash tank configured to receive input refrigerant and change the input refrigerant into a first liquid refrigerant and a vapor. The refrigeration system also includes a first valve positioned between the flash tank and a safety tank. The refrigeration system also includes a plurality of refrigeration components configured to receive the first liquid refrigerant and the second liquid refrigerant from the flash tank, and the first liquid refrigerant and second liquid refrigerant are used to provide refrigeration to a load.

[0008] The refrigeration system is controlled by a controller that is communicatively coupled to the first valve. The controller is configured to cause the first valve to close when the first condition is met. When the first condition is not met, the controller causes the first valve to open. The first condition is that electrical power is provided to the plurality of refrigeration components. Vapor from the flash tank flows through the first valve to the safety tank when the first valve is open, and the vapor is prohibited from flowing to the safety tank when the first valve is closed. The safety tank is configured to receive the vapor from the flash tank when the first valve is open, condense the vapor into a second liquid refrigerant, and pass the second liquid refrigerant to the flash tank.

[0009] In one or more embodiments, the load comprises an enclosed environment, and the safety tank is placed inside the enclosed environment. The safety tank is placed in the top portion of the enclosed environment above the flash tank. The second liquid refrigerant is caused to flow to the flash tank by gravity. A second valve may be positioned between the flash tank and the safety tank to allow the second liquid refrigerant to continue to flow from the safety tank to the flash tank when the first valve is closed.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] 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:

[0011] FIG. 1 is a diagram of a first example refrigeration system of this disclosure configured to provide mechanical relief protection during a power outage;

[0012] FIG. 2 is a diagram of a second example refrigeration system of this disclosure configured to provide mechanical relief protection during a power outage; and

[0013] FIG. 3 is a flowchart of an example method of operating the refrigeration system of FIGS. 1 and 2 to provide mechanical relief protection during a power outage.DETAILED DESCRIPTION

[0014] Embodiments of the present disclosure and its advantages are best understood by referring to FIGS. 1 and 2 of the drawings, like numerals being used for like and corresponding parts of the various drawings.

[0015] As described above, conventional refrigeration systems suffer from certain inefficiencies and drawbacks when electrical power is lost. This disclosure's refrigeration system improves upon prior methods for compensating for electrical power outages. In one or more embodiments, the refrigeration system of this disclosure uses a safety tank to take the vapor from a flash tank and relieve pressure in the flash tank when power is lost to a refrigeration system. This safety tank keeps the refrigeration system from having to vent refrigeration and may potentially provide additional cooling to a load until power is restored.

[0016] In one or more embodiments, the load may be a larger freezer or refrigerator, such as a walk-in freezer. Inside this environment, one or more evaporators cool the environment during normal operation. Alternatively, the load may be a refrigerated case, an electronic device enclosure, or any other structure that needs refrigeration. The one or more embodiments are not limited to a refrigeration system and may be any type of system that utilizes refrigerant to cool an environment.

[0017] In one or more embodiments, the refrigeration system of this disclosure may be a CO2 refrigeration system. CO2 refrigeration systems may differ from conventional refrigeration systems in that these systems circulate refrigerant that may become a supercritical fluid (i.e., where distinct liquid and gas phases are not present) above the critical point. For example, the critical point for carbon dioxide (CO2) is 31°C and 73.8 MPa, and above this point, CO2 becomes a homogenous mixture of vapor and liquid called a supercritical fluid. This unique characteristic of transcritical refrigerantsis associated with certain operational differences between transcritical and conventional refrigeration systems. For example, transcritical refrigerants are typically associated with discharge temperatures that are higher than their critical temperatures and discharge pressures that are higher than their critical pressures. When a transcritical refrigerant is at or above its critical temperature and / or pressure, the refrigerant may become a “supercritical fluid”— a homogenous mixture of gas and liquid. Supercritical fluid does not undergo a phase change process (vapor to liquid) in a gas cooler as occurs in a condenser of a conventional refrigeration system circulating traditional refrigerant. Rather, supercritical fluid cools down to a lower temperature in the gas cooler. Stated differently, the gas cooler in a CO2 transcritical refrigeration system may receive and cool supercritical fluid, and the transcritical refrigerant undergoes a partial state change from gas to liquid as it is discharged from an expansion valve.

[0018] While in one or more embodiments, the refrigeration system of this disclosure is described as a CO2 refrigerant system, the disclosure is not limited to a CO2 refrigeration system. The refrigeration system may use other fluids with similar properties to CO2. Alternatively, the refrigeration system of this disclosure may use any refrigerant or system that, combined with the safety tank, flash tank, and valves, provides mechanical relief during a power outage. Refrigeration System

[0019] FIGS. 1 and 2 illustrate examples of refrigeration systems 100 and 200 configured for providing refrigeration to a load (not shown). The refrigeration system 100 includes a first evaporator 106 and a second evaporator 108, along with one or more compressors, e.g., 102 and 104, a flash tank 114, a desuperheater 112, an oil separator 118, a condenser / gas cooler 110, a safety tank 116, and a controller 150 for controlling at least a first valve 122. The refrigeration system 100, shown in FIG. 1, is configured to use the safety tank 116 to relieve pressure in the flash tank 114 and provide additional liquid refrigerant to the first evaporator 106 and second evaporator 108 when the refrigeration system 100 operates without electrical power. When power is restored or during normal operation, the controller 150 of the refrigeration system 100 closes the first valve 122 and operates normally without using the safety tank 116 to relieve pressure from the flash tank 114 and provide condensed vapor to the flash tank 114. While the system of FIG. 1 includes multiple evaporators, e.g., 106 and 108, a condenser, e.g., 102 and 104, an oil separator 118, and a desuperheater 112, the system 100 may comprise more or fewer components without departing from the disclosure. For example, in a non-limiting example, shown in FIG. 2, a refrigeration system 200 may only have a safety tank 116, a flash tank 114, an evaporator 108, a compressor 104, and a condenser 110.

[0020] Refrigeration system 100 may include a plurality of compressors, e.g., 102 and 104. The one or more compressors, e.g., 102 and 104, may include one or more low-temperature (LT) compressors 104 and one or more medium-temperature (MT) compressors 102. In one or more embodiments, the MT compressor(s) 102 and LT compressor(s) 104 may be different types of compressors or maybe the same type of compressor. The MT compressor(s) 102 are configured to compress refrigerant discharged from the LT compressor(s) 104 as well as vapor discharged from the flash tank 114 and one or more medium-temperature (MT) evaporator(s) 106. LT compressors 104 are configured to compress refrigerant discharged from one or more low-temperature (LT) evaporator(s)108.

[0021] Refrigeration system 100 may include any suitable number of MT compressors 102 and LT compressors 104. The MT compressor(s) 102 and LT compressor(s) 104 may vary by design and / or by capacity. For example, some compressor designs may be more energy efficient than others, and some MT compressors 102 and LT compressors 104 may have modular capacity (e.g., a capability to vary capacity). The controller 150 communicates with the MT compressors 102 and LT compressors 104 and controls their operation.

[0022] The one or more LT compressors 104 receive refrigerant from the LT evaporator(s) 108 through conduit 146 after the refrigerant has been used to provide refrigeration to a load (not shown) associated with the LT evaporator(s) 108. The LT compressor(s) 104 compresses the refrigerant and then provides the refrigerant through conduit 148 to an optional desuperheater 112 and then through conduit 140 to the MT compressor(s) 102 for further compression. In one or more embodiments, the MT compressor(s) 102 provides supplemental compression to the refrigerant discharged from the LT compressor(s) 104. The MT compressor(s) 102 may also receive the vapor from the flash tank 114 through conduit 138. The received refrigerant, which is warmer than that received by the LT compressor(s) 104, is then compressed by the MT compressor(s) 102 and provided to an optional gas cooler / condenser 110 through conduit 136.

[0023] In one or more embodiments, a desuperheater 112 is provided to receive compressed refrigerant from the LT compressor(s) 104 through conduit 148. The desuperheater 112 reduces the temperature of the compressed refrigerant so that the MT compressor(s) 102 may operate more efficiently. The desuperheater 112 may comprise a heat exchanger that exchanges heat from the compressed refrigerant received from the LT compressor(s) 104 with a different refrigerant, such as, but not limited to, water. The different refrigerants may then carry away the excess heat to use it for other purposes or discharge it into an external environment. By reducing the temperature of the compressed refrigerant, the MT compressor(s) 102 receiving the compressed refrigerant may work at a lower temperature and with more efficiency.

[0024] In one or more embodiments, an oil separator 118 is provided in conduit 136 to separate the oil from the compressed refrigerant, leaving the MT compressor(s) 102. The oil separator 118 is provided because as the compressors, e.g., 104 and 102, operate, some oil, such as lubrication oil, enters the refrigerant. Oil separator 118 removes this oil and, in one or more embodiments, may recycle it back to one or more of the compressors, e.g., 102. This prevents oil from building up in the condenser 110 and other components of the refrigeration system 100, which may result in damage. There is also the need to constantly provide new lubricant oil to replace that which was lost.

[0025] Once the refrigerant leaves the MT compressor 102 and passes through the optional oil separator 118, the refrigerant enters the condenser / gas cooler 110. Condenser 110 is configured to receive compressed refrigerant from the MT compressor(s) 102 and / or LT compressor(s) 104 received from conduit 136 and cool it before providing it to flash tank 114 through conduit 134. The condenser 110 is generally operable to apply cooling to the received compressed refrigerant. In some embodiments, condenser 110 is a heat exchanger comprising cooler tubes configured to circulate the received refrigerant and coils through which ambient air is forced. Inside condenser 110, the coils may absorb heat from the refrigerant, thereby cooling the refrigerant. The cooled compressed refrigerant is passed through conduit 134 to a flash tank 114.

[0026] Flash tank 114 is configured to receive mixed-state refrigerant and separate the received refrigerant into flash gas or vapor and liquid refrigerant. This reduces the temperature of the refrigerant sent to the evaporators, e.g., 106 and 108, and provides the refrigerant in a purely liquid form to the evaporators, e.g., 106 and 108. Flash tank 114 may include one or more tanks operable to hold refrigerant at least temporarily. Typically, the flash gas collects near the top of flash tank 114, and the liquid refrigerant is collected at the bottom of flash tank 114. A pressure relief valve 130 may be disposed at or near an inlet of the flash tank 114 to reduce the pressure of refrigerant received by the flash tank 114.

[0027] In one or more embodiments, the flash gas or vapor from the flash tank 114 is sent through an outlet through conduit 138 to the MT compressor(s) 102. Additionally, the flash gas may leave the flash tank 114 through conduit 132 to safety tank 116 when first valve 122 is open. In one or more embodiments, conduit 138 may include an optional relief valve 128 to reduce the pressure and / or temperature of the vapor directed from the flash tank 114 to the MT compressor(s) 102. Similarly, the condensed liquid refrigerant from the flash tank 114 is directed to MT evaporator(s) 106 and LT evaporator(s) 108.

[0028] The safety tank 116 may be the form of a low-cost tank that operates at about 45 bars (4.5 MPa) or any other size or type of tank, including a tank similar to or identical to flash tank 114. The safety tank 116 may function at a lower pressure than the flash tank 114 or may be identical to the flash tank 114. The safety tank 116 receives vapor from the flash tank 114 through conduit 132 when the first valve 122 is opened. This vapor then condenses in the safety tank 116 to a second liquid refrigerant that flows back down conduit 132 through bypass valve 120 to the flash tank 114, mixing with the liquid refrigerant from the flash tank 114 to provide cooling to the MT evaporator(s) 106 and LT evaporator(s) 108.

[0029] The first valve 122, in one or more embodiments, is a solenoid valve. The first valve 122 is kept closed when the controller 150 determines that electrical power or a first condition is met. When the first valve 122 is closed, vapor from the flash tank 114 is prohibited from flowing to the safety tank 116. When electrical power is lost and / or the first condition is not met, the first valve 122 may be caused to open or may automatically open due to springs or other structures allowing the vapor from the flash tank 114 to rise into the safety tank 116. Conduit 132 may also include a bypass valve 120, which in one or more embodiments is a check valve that allows the condensed liquid refrigerant to flow around the first valve 122 when the first valve is closed. This allows the liquid refrigerant in safety tank 116 to continue to drain after electrical power has been restored and / or the first condition is met. In one or more embodiments, the bypass valve 120 may also function as a relief valve to vent refrigerant when the pressure of the vapor rises above a safe level to prevent damage to either the safety tank 116 and / or the flash tank 114.

[0030] In one or more embodiments, the safety tank 116 is placed or mounted at a higher height above that of the flash tank 114. This is so that any liquid refrigerant condensed in the safety tank 116 may flow by gravity to the flash tank 114, allowing the safety tank 116 to operate without any pumps or motors. By enabling the safety tank 116 to operate without any pumps or motors, the system is able to function when no electrical power is available simply by using the pressure of the vapor and gravity to operate. In one or more embodiments, the safety tank 116 may be mounted inside an enclosed environment cooled by one or more evaporators, e.g., 108. For example, where the evaporator, e.g., 108, cools a walk-in refrigerator, the safety tank 116 may be mounted in a top portion of the enclosed refrigerator on a top shelf. This also allows the vapor received in the safety tank to be kept cool, keeping the temperature of the refrigeration system 100 stable for a longer time. The safety tank 116 may be mounted at any suitable position, and the disclosure is not limited to mounting it in an environment that is cooled by the one or more evaporators, e.g., 108. The safety tank 116, for example, in a non-limiting example, could be mounted in a ceiling or other location higher than the flash tank 114 without departing from the disclosure. In addition, where needed due to the distance or other factors, optional motors or pumps may be provided, and the disclosure is not limited to a system that operates solely using pressure and gravity to move the refrigerant to the safety tank 116 and back to the flash tank 114.

[0031] Once liquid refrigerant has been condensed in either or both the flash tank 114 and safety tank 116, the refrigerant flows in conduit 142 to the MT evaporator(s) 106 and the LT evaporator(s) 108. The optional MT evaporator(s) 106 receives the liquid refrigerant from conduit 142 and uses the liquid refrigerant to provide cooling to a load. For example, the MT evaporator(s) 106 may be part of a refrigerated case and / or cooler for storing items that must be kept at particular temperatures. The refrigeration system 100 may include any appropriate number of MT evaporators, e.g., 106 with the same or a similar configuration to that shown for the example MT evaporator 106 shown in FIG. 1. The MT evaporator(s) 106 may include one or more expansion valves, e.g., 124 configured to receive the liquid refrigerant from flash tank 114 and reduce the pressure and / or temperature of the received refrigerant. In some embodiments, this reduction in pressure causes some of the refrigerant to vaporize. Expansion valve(s) 124 may be configured to cause refrigerant passed into the MT evaporator(s) 106 to be at a predefined temperature for a given application (e.g., about -6 °C). Refrigerant from the MT evaporator(s) 106, once used to cool a load (not shown), is then provided to the MT compressor(s) 102 through conduits 144 and 140.

[0032] The liquid refrigerant also passes from conduit 142 to the LT evaporator(s) 108. The LT evaporator(s) 108 are generally similar to the MT evaporator(s) 106 but are configured to operate at lower temperatures than the MT evaporator(s) 106, such as, for example, near about -30 °C or the like. Both the MT evaporator(s) 106 and the LT evaporator(s) 108 may be operated at any temperature, and the disclosure is not limited to operating at different temperatures or any particular temperature. The operation temperature is determined by the application as well as, or instead, the preferences of the operator of the refrigeration systems 100 and / or 200.

[0033] The LT evaporator(s) 108 both receive cooled liquid refrigerant from the flash tank 114 and / or safety tank 116. This cooled liquid refrigerant is used to provide cooling to an environment around the LT evaporator(s) 108. The liquid refrigerant from the flash tank 114 flows to and cools the LT evaporator(s) 108. Expansion valve(s) 126 may be operated to moderate the liquid refrigerant's pressure and / or temperature to ensure proper operation of the LT evaporator(s) 108. For example, in a non-limiting example, the LT evaporator(s) 108 may be part of a deep freezer for relatively long-term storage of perishable items that must be kept at particular temperatures.

[0034] While the refrigeration system 100 is shown with only one LT evaporator 108 and one MT evaporator 106, the system 100 may include any appropriate number of LT evaporators, e.g., 108, MT evaporators, e.g., 106, with additional corresponding valves, e.g., 124 and 126. For example, a second LT evaporator (not shown) may be provided in a non-limiting example that provides the same load or a separate load as the first LT evaporator 108, with cooling. The third or other evaporator may then pass the refrigerant that has absorbed heat from the load to the LT compressor(s) 104 using a conduit similar to conduit 146.

[0035] The various conduits 132-148 may form a refrigerant conduit subsystem that facilitates the movement of refrigerant (e.g., CO2) through refrigeration cycles, both when the first condition is met, and / or power is provided to the system 100 and when the first condition is no-longer met and first valve 122 is opened as illustrated by the arrows in FIGS. 1 and 2. The subsystem includes conduit, tubing, piping, and the like that facilitate refrigerant movement between components of the refrigeration systems 100 and 200. The conduits 132-148 may be copper conduits or other types of appropriate conduit, tubing, or piping. Different sections of the conduit, e.g., 132, may be made of different materials or take different forms.

[0036] The components of the refrigeration system, 100 and 200, may be controlled by the controller 150. The controller 150 may provide instructions 158 for adjusting first valve 122 to open or close depending on if the first condition is met. In one or more embodiments, the first condition is related to if electrical power is currently being supplied to the refrigeration system. However, the first condition may be any condition, for example, one or more of the compressors, e.g., 104 and 102, being taken offline, and is not limited to when electrical power has been lost. Instruction 158, implemented by a processor 152 of the controller 150, may determine that the first condition has been met, and when the first condition is not met, the controller 150 may cause the first valve 122 to open. Alternatively, in one or more embodiments, the first valve 122 may open automatically due to the mechanical properties of the first valve 122, which allows it to open when power is lost.

[0037] The controller 150 includes a processor 152, memory 154, and input / output (I / O) interface 156. The processor 152 includes one or more processors operably coupled to the memory 154. The processor 152 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 154 and controls the operation of the refrigeration systems 100 and 200.

[0038] The processor 152 may be a programmable logic device, a microcontroller, a microprocessor, or any suitable combination of the preceding. The processor 152 is communicatively coupled to and in signal communication with the memory 154. The one or more processors 152 are configured to process data and may be implemented in hardware or software. For example, the processor 152 may be 8-bit, 16-bit, 32-bit, 64-bit, or of any other suitable architecture. The processor 152 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 154 and executes them by directing the coordinated operations of the ALU, registers, and other components. The processor 152 may include other hardware and software that operates to process information, control the refrigeration systems 100 and 200, and perform any of the functions described herein (e.g., with respect to FIGS. 1-3). The processor 152 is not limited to a single processing device and may encompass multiple processing devices. Similarly, the controller 150 is not limited to a single controller but may encompass multiple controllers.

[0039] The I / O interface 156 is configured to communicate data and signals with other devices. For example, the I / O interface 156 may be configured to communicate electrical signals with components of the refrigeration system 100, including, but not limited to, the first valve 122. The I / O interface 156 may be configured to communicate with other devices and systems and is not limited to those just described or those present in FIGS. 1 and 2. The I / O interface 156 may provide and / or receive, for example, compressor speed signals, compressor on / off signals, valve open / close signals, temperature signals, pressure signals, temperature setpoints, environmental conditions, and an operating mode status for the refrigeration system 100 and 200 and send electrical signals to the components of the refrigeration system 100 and 200. The I / O interface 156 may include ports or terminals for establishing signal communications between the controller 150 and other devices. The I / O interface 156 may be configured to enable wired and / or wireless communications.

[0040] The memory 154 includes one or more disks, tape drives, or solid-state drives. It may be used as an over-flow data storage device to store programs when such programs are selected for execution and to store instructions 158 and data read during program execution. The memory 154 may be volatile or non-volatile and may include ROM, RAM, ternary content-addressable memory (TCAM), dynamic random-access memory (DRAM), and static random-access memory (SRAM). The memory 154 is operable (or configured) to store information used by the controller 150 and / or any other logic and / or instructions for performing the function described in this disclosure.

[0041] The instructions 158 may determine when a first condition is met and when it is not met. As discussed above, the first condition may be met in one or more embodiments when power is supplied to the refrigeration systems 100 and 200. The controller 150 may determine how to adjust first valve 122 as well as bypass valve 120 based on settings recorded in the memory 154 as valve settings 160. For example, in a non-limiting example, when the first condition is that power is being supplied after power has been restored, it may be desirable to leave bypass valve 120 open for a period of time to allow liquid refrigerant to drain from the safety tank 116 when power is supplied. The first condition is not limited to when power is supplied or not supplied; these are just non-limiting examples.

[0042] The valve settings 160 and / or instructions 158 may also provide other conditions when the first valve 122 may be opened, such as for example when one or more sensors (not shown) indicate one or more refrigeration components, e.g., 104, are no longer functioning or not functioning within at a desired level. For example, in a non-limiting example, if a sensor (not shown) indicates that the compressed refrigerant in conduit 134 has a temperature that is above a threshold, it may be desirable to open the first valve 122 to prevent refrigerant from needing to be vented by pressure relief valve 130. The valve settings 160 may also indicate that bypass valve 120 and first valve 122 should remain open or closed for a predetermined amount of time after the first condition is met after the valve has been opened due to the first condition not being met.

[0043] The controller 150 may control other components of the refrigeration systems 100 and 200 and is not limited to just controlling bypass valve 120 and first valve 122. Although this disclosure describes and depicts refrigeration systems 100 and 200, including specific components, it recognizes that refrigeration systems 100 and 200 may include any suitable components. For example, refrigeration systems 100 and 200 may include one or more additional sensors configured to detect temperature and / or pressure information.

[0044] In an example operation of the refrigeration system 100, when the controller 150 detects a first condition is no longer met, for example that electrical power has been lost to the system 100, the controller causes the first valve 122 to open. When the first valve 122 opens, vapor from the flash tank 114 flows up conduit 132 to safety tank 116, reducing the refrigerant pressure in flash tank 114. The vapor in the safety tank 116, in one or more embodiments, may then condense and flow back down conduit 132 as a cooled liquid to flash tank 114, which then flows to the evaporators 106 and 108 to continue providing cooling to the loads. Once the first condition is met again, for example, power is restored, the controller causes the first valve 122 to close, stopping vapor from the flash tank from flowing to the safety tank. The vapor remaining in safety tank 116 may continue to condense into liquid and flow back through conduit 132 by flowing through bypass valve 120. The remaining components of the system 100 are then allowed to run in refrigeration mode until the first condition is no longer met. The refrigeration system 200 of FIG. 2 operates similarly to that of the refrigeration system 100 of FIG. 1. It is provided only to show an example of a system 200 that has fewer components than that of the refrigeration system 100 but still uses the safety tank 116 to provide mechanical relief protection.Example method of operation

[0045] FIG. 3 illustrates an example method 300 of operating the refrigeration systems 100 and 200 wherein the first condition is that the electrical power is being provided as described above with respect to FIGS. 1 and 2. Method 300 may be implemented using the processor 152, memory 154, and I / O interface 156 of the controller 150 of FIG. 1. While described with the first condition being that the electrical power is provided, method 300 may be used for any condition without departing from the disclosure. The method 300 may begin at operation 305.

[0046] In operation 305, the controller 150 monitors the refrigeration system 100 electrical power. This may be done by monitoring the electrical power being provided to the controller 150, by monitoring sensors (not shown), or by receiving feedback from components such as compressors 102 and 104 of system 100. The controller 150 monitors the refrigeration system 100 to determine when system 100 or one or more components, e.g., 102, have lost power. If the controller 150 determines that power has not been lost in operation 310, then the controller 150 continues to monitor the refrigeration system’s 100 electrical power. However, if in operation 310, the controller 150 determines that power has been lost to one or more components, e.g., 102, of the refrigeration system 100, then the controller 150 causes the first valve 122 to open in operation 315. In one or more embodiments, operation 315 may be optional, where when power loss occurs, the controller 150 would not be able to open the first valve 122. Instead, the first valve 122, in one or more embodiments, may be designed to open automatically when power is lost without the input of electrical power from any other source.

[0047] Once the first valve 122 is opened in operation 315, the controller 150 determines if power has been restored in operation 320. If the power has not been restored in operation 320, the first valve 122 is kept open in operation 325, and operations 315-325 are repeated until the controller 150 determines power has been restored in operation 320. When the controller 150 determines that power has been restored in operation 320, it closes the first valve 122 in operation 330. In one or more embodiments, the controller 150 may cause bypass valve 120 to open or continue to be open in order to allow refrigerant from safety tank 116 to drain to the flash tank 114; after a sufficient amount of time, the bypass valve 120 may also be closed, or bypass valve 120 may always be kept open and may only function as a pressure relief valve, to relieve pressure in safety tank 116 when power has not been restored in a sufficient amount of time to prevent the flash tank 114 and / or safety tank 116 from reaching their maximum safe operating pressure.

[0048] Once the controller 150 determines the power has been restored in operation 320 and closes the first valve 122 in operation 330, the method 300 may end. In one or more embodiments, method 300 may be continuously performed, and after operation 330, operations 305-330 may be repeated continuously as long as system 100 continues to be used / operated.

[0049] Method 300 may include more, fewer, or other operations. For example, operations may be performed in parallel or any suitable order. Modifications, additions, or omissions may be made to method 300, depicted in FIG. 3. While at times discussed as controller 150, refrigeration system 100, or components thereof performing the operations, any suitable refrigeration system or components of the refrigeration system may perform one or more operations of method 300.

[0050] 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 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 into another system, or certain features may be omitted or not implemented.

[0051] 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.

[0052] 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.

Claims

1. A refrigeration system, comprising:a flash tank configured to receive input refrigerant and change the input refrigerant into a first liquid refrigerant and a vapor;a first valve positioned between the flash tank and a safety tank, wherein the vapor from the flash tank flows through the first valve to the safety tank when the first valve is open and the vapor is prohibited from flowing to the safety tank when the first valve is closed;a safety tank configured to receive the vapor from the flash tank when the first valve is open, condense the vapor into a second liquid refrigerant, and pass the second liquid refrigerant to the flash tank;a plurality of refrigeration components configured to receive the first liquid refrigerant and the second liquid refrigerant from the flash tank and use the first liquid refrigerant and second liquid refrigerant to provide refrigeration to a load; a controller communicatively coupled to the first valve, wherein the controller is configured to cause the first valve to close when a first condition is met; wherein when the first condition is not met, the controller causes the first valve to open; andthe first condition is that electrical power is provided to the plurality of refrigeration components.

2. The refrigeration system of claim 1, wherein the safety tank is placed above the flash tank and the second liquid refrigerant is caused to flow to the flash tank by gravity.

3. The refrigeration system of claim 1, wherein the load comprises an enclosed environment and the safety tank is placed inside the enclosed environment.

4. The refrigeration system of claim 3, wherein the safety tank is placed in a top portion of the enclosed environment.

5. The refrigeration system of claim 1, further comprising a second valve positioned between the flash tank and the safety tank wherein:the first valve is a solenoid valve; andthe second valve is a check valve that allows the second liquid refrigerant to flow to the flash tank, at least when the first valve is closed.

6. The refrigeration system of claim 1, wherein the plurality of refrigeration components comprises a first evaporator, a first compressor, and a condenser.

7. The refrigeration system of claim 6, wherein the plurality of refrigeration components further comprises a second evaporator and a second compressor, wherein the first evaporator and the second evaporator receive the first liquid refrigerant and second liquid refrigerant from the flash tank and pass refrigerant to at least one of the first compressor and the second compressor.

8. The refrigeration system of claim 7, wherein the first evaporator is a low-temperature evaporator, the first compressor is a low-temperature compressor, the second evaporator is a medium-temperature heat evaporator, and the second compressor is a medium-temperature compressor.

9. The refrigeration system of claim 7, wherein the plurality of refrigeration components further comprises a desuperheater that receives a first compressed refrigerant from the first compressor, reduces its heat, and passes the first compressed refrigerant to the second compressor.

10. The refrigeration system of claim 9, wherein the second compressor further receives vapor from the flash tank and refrigerant from the second evaporator, performs compression and provides a second compressed refrigerant to an oil separator and the condenser.

11. A method of operating a refrigeration system, the method comprising:determining if a first condition is not met, wherein the first condition is that electrical power is provided to a plurality of refrigeration components;causing a first valve to open when the first condition is determined not to have been met; andoperating the plurality of refrigeration components using a first liquid refrigerant and a second liquid refrigerant to provide refrigeration to a load;wherein:the first valve is positioned between a flash tank and a safety tank, wherein vapor from the flash tank flows through the first valve to the safety tank when the first valve is open, and the vapor is prohibited from flowing to the safety tank when the first valve is closed; the flash tank is configured to receive input refrigerant and change the input refrigerant into the first liquid refrigerant and the vapor; andthe safety tank is configured to receive the vapor from the flash tank when the first valve is open, condense the vapor into the second liquid refrigerant, and pass the second liquid refrigerant to the flash tank.

12. The method of claim 11, further comprising: causing the second liquid refrigerant to flow by gravity by placing the safety tank is placed above the flash tank.

13. The method of claim 12, further comprising: wherein the load comprises an enclosed environment and the safety tank is placed inside the enclosed environment at a position that is higher than the flash tank.

14. The method of claim 13, further comprises: determining if a first condition is met; causing the first valve to close; andoperating the plurality of refrigeration components using only the first liquid refrigerant to provide refrigeration to the load.

15. The method of claim 14, wherein the plurality of refrigeration components comprises a first evaporator, a first compressor, and a condenser.

16. A controller of a refrigeration system, the controller comprising:an input / output interface communicatively coupled to:a flash tank configured to receive input refrigerant and change the input refrigerant into a first liquid refrigerant and a vapor;a first valve positioned between the flash tank and a safety tank, wherein the vapor from the flash tank flows through the first valve to the safety tank when the first valve is open and the vapor is prohibited from flowing to the safety tank when the first valve is closed;a safety tank configured to receive the vapor from the flash tank when the first valve is open, condense the vapor into a second liquid refrigerant, and pass the second liquid refrigerant to the flash tank;a plurality of refrigeration components configured to receive the first liquid refrigerant and the second liquid refrigerant from the flash tank and use the first liquid refrigerant and second liquid refrigerant to provide refrigeration to a load; anda processor configured to:determining if a first condition is not met, wherein the first condition is that electrical power is provided to the plurality of refrigeration components;causing the first valve to open when the first condition is determined not to have been met; andoperating the plurality of refrigeration components using the first liquid refrigerant and the second liquid refrigerant to provide refrigeration to the load.

17. The controller of claim 16, wherein the safety tank is placed above the flash tank, and the second liquid refrigerant is caused to flow to the safety tank by gravity.

18. The controller of claim 17, wherein the input / output interface is further communicatively coupled to:a second valve positioned between the flash tank and the safety tank wherein:the first valve is a solenoid valve; andthe second valve is a check valve that allows the second liquid refrigerant to flow to the flash tank, at least when the first valve is closed.

19. The controller of claim 16, wherein the load comprises an enclosed environment and the safety tank is placed inside the enclosed environment.

20. The controller of claim 19, wherein the processor is further configured to:determine if a first condition is met; cause the first valve to close; andoperate the plurality of refrigeration components using only the first liquid refrigerant to provide refrigeration to the load.

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