REFRIGERATION SYSTEM WITH A DISTRIBUTION SYSTEM AND A REFRIGERATION UNIT.

Abstract

A refrigeration system includes a distribution system and a refrigeration unit; the distribution system is configured to circulate a refrigerant from the distribution system; the distribution system includes a distribution system pump, a main chiller, a distribution system inlet line, and a distribution system outlet line; the main chiller is configured to receive the distribution system refrigerant from the distribution system pump; the distribution system inlet line is configured to receive the distribution system refrigerant from the main chiller; the distribution system outlet line is configured to receive the distribution system refrigerant from the distribution system inlet line and to supply the distribution system refrigerant to the distribution system pump;The refrigeration unit is configured to circulate a refrigerant from the refrigeration unit; the refrigeration unit includes a refrigeration unit pump, an upstream receiver, a condenser, a downstream receiver, and an evaporator; the upstream receiver is configured to receive the refrigerant from the refrigeration unit.

Description

REFRIGERATION SYSTEM WITH A DISTRIBUTION SYSTEM AND A REFRIGERATION UNIT TECHNICAL FIELD This application generally refers to a refrigeration system with a distribution system and a refrigeration unit. BACKGROUND OF THE INVENTION In refrigeration systems, a refrigerant circulates, causing the refrigeration process to undergo a thermodynamic cycle. This cycle causes the refrigerant's temperature to change between a maximum and a minimum. Refrigeration systems transfer heat from a desired space to the refrigerant. BRIEF DESCRIPTION OF THE INVENTION In one configuration, a refrigeration system includes a distribution system and a refrigeration unit. The distribution system is configured to circulate refrigerant from the distribution system. The distribution system includes a distribution system pump, a main chiller, a distribution system inlet line, and a distribution system outlet line. The main chiller is configured to receive refrigerant from the distribution system via the distribution system pump. The distribution system inlet line is configured to receive refrigerant from the distribution system via the main chiller. The distribution system outlet line is configured to receive refrigerant from the distribution system inlet line and to supply refrigerant from the distribution system to the distribution system pump.The refrigeration unit is configured to circulate refrigerant. The refrigeration unit includes a refrigeration unit pump, an upstream receiver, a condenser, a downstream receiver, and an evaporator. The upstream receiver is configured to receive refrigerant from the refrigeration unit pump. The condenser is configured to receive refrigerant from the upstream receiver. The condenser includes the refrigeration unit heat exchanger, which is configured to be connected to the distribution system inlet and outlet lines. The refrigeration unit heat exchanger is also configured to receive refrigerant from the distribution system inlet line.The refrigeration unit's heat exchanger duct is also configured to supply refrigerant from the distribution system to the distribution system's outlet duct. The downstream receiver is configured to receive refrigerant from the condenser refrigeration unit. The evaporator is configured to receive refrigerant from the downstream receiver refrigeration unit and to supply refrigerant from the refrigeration unit to the refrigeration unit's pump. In another configuration, a refrigeration unit is set up to circulate a refrigerant from the refrigeration unit. The refrigeration unit includes an upstream transfer system control valve, a refrigeration unit pump, a transfer system line, an upstream receiver, a condenser, and an evaporator. The refrigeration unit pump is set up to receive refrigerant from the upstream transfer system control valve. The downstream transfer system control valve is set up to receive refrigerant from the refrigeration unit pump. The transfer system line is set up to receive refrigerant from the refrigeration unit from the downstream transfer system control valve.The upstream receiver is configured to receive refrigerant from the refrigeration unit via the downstream control valve of the transfer system. The condenser is configured to receive refrigerant from the refrigeration unit via the upstream receiver. The evaporator is configured to receive refrigerant from the refrigeration unit via the condenser and to supply refrigerant from the refrigeration unit to the upstream control valve of the transfer system. The transfer system duct is configured so that the refrigerant from the refrigeration unit bypasses the upstream receiver, the condenser, and the evaporator as it flows through the transfer system duct between the upstream and downstream control valves of the transfer system. In yet another configuration, a refrigeration unit is configured to circulate a refrigerant. The refrigeration unit includes an upstream expansion control valve, a refrigeration unit pump, a downstream expansion control valve, an expansion tank, a condenser, an evaporator, and a refrigeration unit controller. The refrigeration unit pump is configured to receive refrigerant from the upstream expansion control valve. The downstream expansion control valve is configured to receive refrigerant from the refrigeration unit pump. The expansion tank is connected to both the upstream and downstream expansion control valves.The condenser is configured to receive refrigerant from the refrigeration unit's pump. The evaporator is configured to receive refrigerant from the condenser and to supply refrigerant to the upstream control valve of the expansion system. The refrigeration unit controller is configured to reposition the downstream control valve of the expansion system to facilitate routing refrigerant from the downstream control valve to the expansion tank while bypassing the condenser and evaporator. BRIEF DESCRIPTION OF THE DRAWINGS Details of one or more implementations are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages of the disclosure will become apparent from the description, the drawings, and the claims, in which: Figure 1 is a schematic block diagram of an example refrigeration system; Figure 2 is a block diagram of an example method of using a distribution system to remove heat from a refrigeration unit; Figure 3 is a block diagram of another example method of using a distribution system to remove heat from a refrigeration unit; Figure 4 is a detailed view of an example refrigeration unit shown in DETAIL A of Figure 1; Figure 5 is a block diagram of an example method of utilizing a refrigeration unit transfer system; Figure 6 is another block diagram of an example method of utilizing a refrigeration unit transfer system; Figure 7 is a block diagram of an example method for using an expansion system in a refrigeration unit; and Figure 8 is a block diagram of an example method of using a cooling system of a refrigeration unit. It will be recognized that some or all of the Figures are schematic representations for illustrative purposes. The Figures are provided to illustrate one or more implementations with the explicit understanding that they will not be used to limit the scope or meaning of the claims. tn« Lzn / cznz / q / υιλι DETAILED DESCRIPTION OF THE INVENTION The following are more detailed descriptions of various concepts related to, and implementations of, methods and devices for providing cooling using a refrigeration system with a distribution system and a refrigeration unit. The various concepts introduced earlier and discussed in greater detail below can be implemented in any number of ways, as the concepts described are not limited to any particular implementation method. Examples of specific implementations and applications are provided primarily for illustrative purposes. L Overview Providing a cooling system for a target, such as a temperature-controlled box, is often done to store products, such as refrigerated or frozen goods. In some applications, each of multiple targets is cooled by a local system. For example, when the targets include several temperature-controlled boxes, each box may be cooled by its own local system. These local systems may then be cooled by a common refrigeration system. In some situations, the cooling of these local systems may be inadequate. As a result, the refrigerant within these systems may become pressurized. For example, when energy is lost from the local system and / or the common refrigeration system, the refrigerant temperature may rise because the ambient temperature is higher than the refrigerant temperature. When the refrigerant pressure exceeds a certain threshold, some refrigerant may be released. If a certain amount of refrigerant is released, the local systems must be recharged with refrigerant before subsequent use. As a result, there may be significant overhead and / or maintenance costs associated with operating these local systems. The implementations described herein relate to a refrigeration system that includes both a refrigeration unit, which provides cooling to a target (e.g., counter, refrigerated box, temperature-controlled box, refrigerator, freezer, refrigerated display case, cold room, temperature-controlled cabinet, etc.), and a distribution system that provides cooling to the refrigeration unit. Each of the refrigeration unit and the distribution system independently circulates a refrigerant. In several configurations, the refrigeration unit circulates carbon dioxide. The distribution system may include a main chiller, an auxiliary chiller, and a control valve that routes the refrigerant to the main chiller and / or the auxiliary chiller based on a power source for the distribution system. In some situations, the distribution system is unable to provide cooling to the refrigeration unit. In these situations, the refrigeration unit monitors refrigerant parameters and can implement various actions to mitigate refrigerant pressure increases within the unit without releasing refrigerant. Through these mitigation measures, the refrigeration unit can retain refrigerant for a longer period than other systems. As a result, this refrigeration unit is more desirable than other systems because it does not require refrigerant recharging in a wider variety of situations than other systems that lack mechanisms to mitigate pressure increases without releasing refrigerant. II. Example Cooling System Figure 1 represents an example refrigeration system 100. The refrigeration system 100 includes a distribution system 102 (e.g., circulation system, main system, etc.) and one or more cooling units 104 (e.g., local cooling systems, etc.). The distribution system 102 circulates a refrigerant from the distribution system (e.g., chiller, working fluid, etc.), and the cooling unit 104 circulates a refrigerant from the cooling unit (e.g., chiller, working fluid, etc.). In several embodiments, the refrigerant in the cooling unit is carbon dioxide (CO2). As explained in more detail herein, the distribution system 102 is configured to provide cooling to each of the cooling units 104, and the cooling units 104 are configured to each provide cooling to a target 106 (e.g., counter, refrigerated box, temperature-controlled box, refrigerator, freezer, refrigerated display case, cold room, temperature-controlled cabinet, etc.). For example, the cooling units 104 can be incorporated into the targets 106. Each of the cooling units 104 is configured to operate independently of the other cooling units 104 and the distribution system 102. In other words, cooling unit 104 can operate to cool target 106 associated with it even though the distribution system 102 is not operating to supply cooling to cooling unit 104. However, the distribution system 102 is configured to augment the cooling provided by the cooling units 104 by supplying cooling to the cooling units themselves. As a result, the cooling of targets 106 is enhanced through the cooperation of the distribution system 102 and the cooling units 104. The distribution system 102 circulates the refrigerant from the distribution system within a duct system of the distribution system 108 (e.g., plumbing system, n« Lzn / cznz / q / υιλι) to supply the refrigerant from the distribution system to the second duct of the distribution system 114. In several configurations, the distribution system 102 also includes a distribution system 116 control valve (e.g., three-way valve, ball valve, solenoid valve, etc.). The distribution system 116 control valve is connected to the second line of the distribution system 114 and configured to receive refrigerant from the distribution system via the second line of the distribution system 114. The distribution system 116 control valve is also connected to a third line of the distribution system 118 of the distribution system 108. The distribution system 102 also includes a main chiller 120 (e.g., heat exchanger, cooling tower, chiller, etc.). The main chiller 120 is connected to the third duct of the distribution system 118 and is configured to receive refrigerant from the distribution system via the third duct of distribution system 118. The main chiller 120 is configured to cool (e.g., reduce the temperature of, condense, etc.) the refrigerant from the distribution system. The main chiller 120 is also connected to an inlet duct of distribution system 122 from the ductwork of distribution system 108. The inlet duct of distribution system 122 is configured to receive refrigerant from the distribution system via the main chiller 120. In operation, the refrigerant in the distribution system has a first temperature in the third duct of the distribution system 118 (e.g., upstream of the main cooler 120) and a second temperature inside the inlet duct of the distribution system 122 (e.g., downstream of the main cooler 120), and the second temperature is lower than the first temperature. A difference between the second and first temperatures may be related to the configuration of the main cooler 120 and / or the ambient conditions (e.g., temperature, humidity, etc.) surrounding the main cooler 120. In configurations where the distribution system 102 includes the distribution system control valve 116, the distribution system also includes an auxiliary chiller 124 (e.g., heat exchanger, cooling tower, chiller, condenser, etc.). As explained in more detail herein, the auxiliary chiller 124 is configured to cool the distribution system refrigerant separately from the main chiller 120. The auxiliary chiller 124 is capable of providing greater cooling to the distribution system refrigerant than the main chiller 120. As such, the auxiliary chiller 124 may be used instead of, or in addition to, the main chiller 120 when the main chiller 120 is unable to adequately cool the distribution system refrigerant. The distribution system 108 ductwork also includes a first auxiliary duct 126. The first auxiliary duct 126 is coupled to the distribution system control valve 116 and configured to receive distribution system refrigerant from the distribution system control valve 116. The first auxiliary duct 126 is also coupled to the auxiliary cooler 124 and configured to supply distribution system refrigerant to the auxiliary cooler 124. The distribution system control valve 116 is operable between a first position, where the third distribution system conduit 118 is configured to receive distribution system refrigerant from the second distribution system conduit 114 via the distribution system control valve 116, a second position, where the first auxiliary conduit 126 is configured to receive distribution system refrigerant from the second distribution system conduit 114 via the distribution system control valve 116, and a third position,Where: (i) the third distribution system conduit 118 is configured to receive distribution system refrigerant from the second distribution system conduit 114 via the distribution system control valve 116 and (ii) the first auxiliary conduit 126 is configured to receive distribution system refrigerant from the second distribution system conduit 114 via the distribution system control valve 116. In this way, the distribution system control valve 116 can control: (i) when distribution system refrigerant is supplied to the main chiller 120 and the auxiliary chiller 124 and (ii) how much distribution system refrigerant is supplied to the main chiller 120 and the auxiliary chiller 124. In some embodiments,The distribution system control valve 116 is additionally operable in a fourth position in which the second distribution system conduit 114 is isolated from the third distribution system conduit 118 and the first auxiliary conduit 126. As a result, the main chiller 120 does not receive refrigerant from the distribution system via the distribution system control valve 116. Additionally, the auxiliary chiller 124 does not receive refrigerant from the distribution system via the distribution system control valve 116. The ductwork of distribution system 108 also includes a second auxiliary duct 128. The second auxiliary duct 128 is connected to the auxiliary cooler 124 and is configured to receive refrigerant from the distribution system of the auxiliary cooler 124. The auxiliary cooler 124 is configured to cool (e.g., reduce the temperature of, condense, etc.) the refrigerant from the distribution system independent of the main cooler 120. In operation, the refrigerant from the distribution system has a first temperature in the first auxiliary duct 126 (e.g., upstream of the auxiliary cooler 124) and a second temperature within the second auxiliary duct 128 (e.g., downstream of the auxiliary cooler 124), and the second temperature is lower than the first temperature.A difference between the second temperature and the first temperature may be related to a configuration of the auxiliary cooler 124 and / or ambient conditions (e.g., temperature, humidity, etc.) surrounding the auxiliary cooler 124. The second auxiliary line 128 is also connected to the distribution system inlet line 122 and configured to supply refrigerant from the distribution system to the distribution system inlet line 122. In some embodiments, the distribution system includes a check valve (e.g., a one-way valve, etc.) arranged along the second auxiliary line 128 to prevent backflow of refrigerant from the distribution system into the second auxiliary line 128. Such a check valve can be useful when the distribution system control valve 116 is positioned to prevent refrigerant from flowing from the distribution system to the first auxiliary line 126. The inlet line of distribution system 122 is also connected to each of the cooling units 104 and configured to supply refrigerant from the distribution system to each of the cooling units 104. The ductwork of distribution system 108 also includes an outlet line from distribution system 130. The outlet line from distribution system 130 is connected to each of the cooling units 104 and configured to receive refrigerant from the distribution system of each of the cooling units 104. The outlet line from distribution system 130 is also connected to the pump of distribution system 110 and configured to supply refrigerant from the distribution system to the pump of distribution system 110. The distribution system 102 is configured to receive power (e.g., electricity, electric power, etc.) from a primary power source 132 (e.g., the public power grid, etc.). The primary power source 132 is electrically coupled to, and configured to supply power to, the cooling units 104, the distribution system pump 110, and the distribution system control valve 116. In some embodiments, the primary power source 132 is additionally electrically coupled to, and configured to supply power to, the primary chiller 120. For example, the primary chiller 120 may include a controller, valves, fans, or other systems that could utilize power from the primary power source 132. Similarly, in some embodiments, the primary power source 132 is additionally electrically coupled to, and configured to supply power to, the auxiliary chiller 124.For example, auxiliary cooler 124 may include a controller, valves, fans, or other systems that could utilize power from the main power source 132. In addition to the main power source 132, the distribution system 102 is also configured to receive power from an auxiliary power source 133 (e.g., generator, battery bank, capacitor, etc.). As explained in more detail herein, the auxiliary power source 133 is configured to operate as a substitute for the main power source 132 in the event of a failure or temporary unavailability (e.g., due to a power outage, etc.) of the main power source 132. The auxiliary power source 133 is electrically coupled to, and configured to supply power to, the cooling units 104, the distribution system pump 110, and the distribution system control valve 116. In some embodiments, the auxiliary power source 133 is additionally electrically coupled to, and configured to supply power to, the main chiller 120.For example, the main chiller 120 may include a controller, valves, fans, or other systems that could utilize power from auxiliary power source 133. Similarly, in some embodiments, auxiliary power source 133 is additionally electrically coupled to, and configured to provide power to, auxiliary chiller 124. For example, auxiliary chiller 124 may include a controller, valves, fans, or other systems that could utilize power from auxiliary power source 133. The distribution system 102 also includes a distribution system controller 134. The cooling units 104, the distribution system pump 110, the distribution system control valve 116, the main power source 132, and the auxiliary power source 133 are electrically and / or communicatively coupled to the distribution system controller 134. With respect to the main power source 132 and the auxiliary power source 133, the distribution system controller 134 is configured to receive power from the main power source 132 and / or the auxiliary power source 133.Additionally, the distribution system controller 134 may include a battery that is configured to supply power to the distribution system controller 134 for a period of time between when the main power source 132 ceases to supply power to the distribution system controller 134 and when the auxiliary power source 133 supplies power to the distribution system controller 134 (for example, thus counting towards a start-up time associated with the auxiliary power source 133, etc.). In some embodiments, the main chiller 120 is additionally electrically and / or communicatively coupled to the distribution system controller 134. For example, the main chiller 120 may include a controller, valves, fans, or other systems that could be controlled by the distribution system controller 134. Similarly, the auxiliary chiller 124 may be electrically and / or communicatively coupled to the distribution system controller 134. For example, the auxiliary chiller 124 may include a controller, valves, fans, or other systems that could be controlled by the distribution system controller 134. Various sensors (e.g., temperature sensors, flow rate sensors, quality sensors, pressure sensors, etc.) can additionally be electrically coupled and / or communicatively coupled to the distribution system controller 134. The various sensors may be able to determine the refrigerant parameters (e.g., temperature, flow rate, quality, pressure, volumetric flow rate, mass flow rate, etc.) of the distribution system refrigerant and / or the second circuit refrigerant. The distribution system 102 includes an environmental sensor 136. The environmental sensor 136 is configured to measure an environmental parameter (e.g., temperature, pressure, quality, etc.) associated with the environment surrounding the distribution system 102. For example, the environmental sensor 136 can measure ambient temperature. The environmental sensor 136 is electrically and / or communicatively coupled to the distribution system controller 134. As a result, the distribution system controller 134 is configured to receive the environmental parameter from the environmental sensor 136. The distribution system 102 includes a main chiller sensor 138. The main chiller sensor 138 is configured to measure a refrigerant parameter of the distribution system refrigerant within the distribution system inlet duct 122 upstream of the auxiliary chiller 124 and the cooling units 104. For example, the main chiller sensor 138 can measure a distribution system refrigerant temperature within the distribution system inlet duct 122 upstream of the auxiliary chiller 124 and the cooling units 104. The main chiller sensor 138 is electrically and / or communicatively coupled to the distribution system controller 134. As a result, the distribution system controller 134 is configured to receive the refrigerant parameter from the main chiller sensor 138. The distribution system 102 includes an auxiliary sensor 140. The auxiliary sensor 140 is configured to measure a coolant parameter of the distribution system coolant within the second auxiliary line 128 upstream of the distribution system inlet line 122. For example, the auxiliary sensor 140 can measure the temperature of the distribution system coolant within the second auxiliary line 128 upstream of the distribution system inlet line 122. The auxiliary sensor 140 is electrically and / or communicatively coupled to the distribution system controller 134. As a result, the distribution system controller 134 is configured to receive the coolant parameter from the auxiliary sensor 140. The distribution system 102 includes a supply sensor 142. The supply sensor 142 is configured to measure a refrigerant parameter of the distribution system refrigerant within the distribution system inlet duct 122 downstream of the auxiliary cooler 124 and upstream of the cooling units 104. For example, the supply sensor 142 can measure a temperature of the distribution system refrigerant within the distribution system inlet duct 122 downstream of the auxiliary cooler 124 and upstream of the cooling units 104. The supply sensor 142 is electrically and / or communicatively coupled to the distribution system controller 134. As a result, the distribution system controller 134 is configured to receive the refrigerant parameter from the supply sensor 142. The distribution system controller 134 includes a distribution system processing circuit 144. The distribution system processing circuit 144 includes a distribution system processor 146 and a distribution system memory 148. The distribution system processor 146 may include a microprocessor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), other similar components, or combinations thereof. The distribution system memory 148 may include, but is not limited to, electronic, optical, magnetic, or any other storage or transmission device capable of providing a processor, ASIC, FPGA, or other similar components with program instructions.The memory of the distribution system 148 may include a memory chip, Electrically Programmable Erasable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), flash memory, or any other suitable memory from which instructions can be read by the distribution system controller 134. The instructions may include code in any suitable programming language. The memory of distribution system 148 may include several modules containing instructions configured to be implemented by the processor of distribution system 146. The memory of distribution system 148 includes a refrigeration unit module 152. The refrigeration unit module 152 contains instructions configured to be implemented by the processor of distribution system 146 to control the operation of the cooling units 104. The memory of distribution system 148 includes a pump module of distribution system 154. The pump module of distribution system 154 contains instructions configured to be implemented by the processor of distribution system 146 to control the operation of the pump of distribution system 110. The memory of distribution system 148 includes a control valve module of distribution system 156.The distribution system control valve module 156 includes instructions that are configured to be implemented by the distribution system processor 146 to control the operation of the distribution system control valve 116. The distribution system memory 148 includes a distribution system sensor module 158. The distribution system sensor module 158 includes instructions that are configured to be implemented by the distribution system processor 146 to receive communications (e.g., refrigerant parameters, environmental parameters, etc.) from the environmental sensor 136, the main chiller sensor 138, the auxiliary sensor 140, and the supply sensor 142. The distribution system memory 148 includes a distribution system power module 160.The distribution system power module 160 includes instructions that are configured to be implemented by the distribution system processor 146 to receive communications from the main power source 132 and the auxiliary power source 133 and to control the operation of the auxiliary power source 133. As explained in more detail herein, the distribution system controller 134 is configured to control the operation of the cooling units 104 (e.g., based on instructions stored in the refrigeration unit module 152, etc.). For example, the distribution system controller 134 can control the operation of the components (e.g., pumps, etc.) of the cooling units 104 based on an environmental parameter measured by the environmental sensor 136 and / or a refrigerant parameter measured by the main chiller sensor 138, the auxiliary sensor 140, and / or the supply sensor 142. Additionally, the distribution system controller 134 can control the operation of the cooling units 104 based on whether power is supplied by the main power source 132 or the auxiliary power source 133. The distribution system controller 134 is configured to control the operation of the distribution system pump 110 (e.g., based on instructions stored in the distribution system pump module 154, etc.). For example, the distribution system controller 134 can control an operating parameter (e.g., voltage supplied to the distribution system pump 110, current supplied to the distribution system pump 110, etc.) of the distribution system pump 110 to achieve a target refrigerant parameter for the distribution system refrigerant within the distribution system 108 ductwork. Additionally, the distribution system controller 134 can control the operation of the distribution system pump 110 based on whether power is supplied by the main power source 132 or the auxiliary power source 133. The distribution system controller 134 is configured to control the operation of the distribution system control valve 116 (for example, based on instructions stored in the distribution system control valve module 156, etc.). For example, the distribution system controller 134 can selectively reposition (for example, from the first position to the second position, from the first position to the third position, from the second position to the first position, from the second position to the third position, from the third position to the first position, from the third position to the second position, etc.) the distribution system control valve 116.Additionally, the distribution system controller 134 can control the operation of the distribution system control valve 116 based on whether tn« Lzn / cznz / q / υιλι energy is supplied by the main energy source 132 or the auxiliary energy source 133. The distribution system controller 134 is configured to facilitate interactions with the ambient sensor 136, the main chiller sensor 138, the auxiliary sensor 140, and the supply sensor 142 (e.g., based on instructions stored in the distribution system sensor module 158, etc.). For example, the distribution system controller 134 can periodically (e.g., once per hour, etc.) use the ambient parameter provided by the ambient sensor 136 while continuously (e.g., once per minute, etc.) using the refrigerant parameter provided by the supply sensor 142.Additionally, the distribution system controller 134 can facilitate interactions with the environmental sensor 136, the main chiller sensor 138, the auxiliary sensor 140, and the supply sensor 142 based on whether power is supplied by the main power source 132 or the auxiliary power source 133. The distribution system controller 134 is configured to control the operation of the auxiliary power source 133 (for example, based on instructions stored in the distribution system power module 160, etc.). For example, the distribution system controller 134 can cause the auxiliary power source 133 to be switched on in response to a determination that the primary power source 132 has failed and / or is unavailable. In some configurations, the distribution system 102 includes a high-pressure distribution relief valve (HPRR) 162 (e.g., a purge valve, etc.) located along the second line of the distribution system 114. The high-pressure HPRR 162 is configured to open when the refrigerant pressure in the distribution system within the second line of the distribution system 114 exceeds a high-pressure threshold. In this way, the high-pressure HPRR 162 can protect the distribution system 102 from the impact of over-pressurized refrigerant from the distribution system. In several modes, the high-pressure threshold is approximately equal to (e.g., within 5% of, etc.) between 5000 kPa (50 bar) and 7500 kPa (75 bar), inclusive (e.g., 4800 kPa (48 bar), 5000 kPa (50 bar), 5500 kPa (55 bar), 6500 kPa (65 bar), 7500 kPa (75 bar), 7700 kPa (77 bar), etc.). In some embodiments, the distribution system 102 includes a low-pressure PRV of the distribution system 164 (e.g., purge valve, etc.) arranged along the outlet line of the distribution system 130. The low-pressure PRV of the distribution system 164 is configured to open when the refrigerant pressure in the distribution system within the outlet line of the distribution system 130 exceeds a low-pressure threshold. In this way, the low-pressure PRV of the distribution system 164 can protect the distribution system 102 from impacts of over-pressurized refrigerant from the distribution system. In embodiments where the distribution system 102 includes both the high-pressure PRV of the distribution system 162 and the low-pressure PRV of the distribution system 164, the high-pressure threshold is higher than the low-pressure threshold.In several modes, the low pressure threshold is approximately equal to (e.g., within 5% of, etc.) between 3500 kPa (35 bar) and 5000 kPa (50 bar), inclusive (e.g., 3300 kPa (33 bar), 3500 kPa (35 bar), 4000 kPa (40 bar), 4500 kPa (45 bar), 5000 kPa (50 bar), 5200 kPa (52 bar), etc.). In some configurations, the main chiller 120 is configured so that the auxiliary chiller 124 is not required and is therefore not included in the distribution system 102. For example, where the main chiller 120 is a refrigeration unit rather than a condenser, it may be able to operate independently of the auxiliary chiller 124. As such, the auxiliary chiller 124, the first auxiliary duct 126, the second auxiliary duct 128, and the auxiliary sensor 140 are not included in the distribution system 102 in some configurations. In several configurations, the main chiller 120 is replaced with a water circuit (e.g., from a facility) flowing through a heat exchanger. Such configurations can be advantageous in applications where the cooling system is installed in a facility with a relatively large water circuit volume (e.g., because the cooling provided by this water circuit can be utilized, etc.) or in applications where space constraints make it difficult to install an additional component, such as a condenser. Although refrigeration system 100 is shown in Figure 1 as including two cooling units 104, it is understood that refrigeration system 100 may include one, three, four, six, ten, or other numbers of cooling units 104. Similarly, it is understood that refrigeration system 100 may operate without any cooling units 104, such as when the cooling units 104 are removed and new cooling units 104 are being installed. III. First example of operation of the refrigeration system with an auxiliary chiller As shown in Figure 2, a method 200 of utilizing the distribution system 102 to remove heat from the refrigeration unit 104 is shown. In method 200, the distribution system 102 includes the auxiliary cooler 124, the first auxiliary duct 126, the second auxiliary duct 128, and the auxiliary sensor 140. Although the distribution system controller 134 is receiving power from the main power source 132, the distribution system control valve 116 is in the first position (i.e., where the third distribution system duct 118 is configured to receive distribution system refrigerant from the second distribution system duct 114 via the distribution system control valve 116). tn« Lzn / cznz / q / υιλι Method 200 begins in block 202 with the determination, by the distribution system controller 134 (for example, via the distribution system power module 160, etc.), whether the main power source 132 is supplying power to the distribution system controller 134. For example, the distribution system controller 134 may monitor a current and / or voltage supplied by the main power source 132 and determine that the main power source 132 is not supplying power to the distribution system controller 134 when the current and / or voltage falls below a threshold (for example, a minimum current, a minimum voltage, etc.). If the distribution system controller 134 determines that the main power source 132 is supplying power to the distribution system controller 134, method 200 is reset (for example, it ends and continues in block 202 again, etc.). If the distribution system controller 134 determines that the main power source 132 is not supplying power to the distribution system controller 134, method 200 continues in block 204 with the deactivation (for example, via the distribution system pump module 154, etc.) by the distribution system controller 134 of the distribution system pump 110. For example, the distribution system controller 134 can provide a signal to the distribution system pump 110 to turn off the distribution system pump 110. Method 200 continues in block 206 with the activation (for example, via the distribution system power module 160, etc.) by the distribution system controller 134 of the auxiliary power source 133. For example, the distribution system controller 134 can send a signal to the auxiliary power source 133 to instruct it to turn on. As a result of the activation of the auxiliary power source 133, auxiliary power can be provided to the cooling units 104, the distribution system pump 110, the distribution system control valve 116, and the auxiliary chiller 124, for example. Method 200 continues in block 208 with the determination (for example, via the distribution system sensor module 158, etc.) by the distribution system controller 134 of whether operation of the auxiliary chiller 124 is desired. This determination is based on whether operation of the main chiller 120 alone is sufficient to maintain a distribution system coolant temperature below a threshold temperature associated with the opening of the high-side distribution system PRV 162 and / or the opening of the low-side distribution system PRV 164. The distribution system controller 134 makes this determination by comparing (for example, via the distribution system sensor module 158, etc.)), by the distribution system controller 134, at least one measured parameter (e.g., the ambient parameter from the ambient sensor 136, the coolant parameter of the distribution system coolant measured by the main chiller sensor 138, the coolant parameter of the distribution system coolant measured by the auxiliary sensor 140, the coolant parameter of the distribution system coolant measured by the supply sensor 142, etc.) to a threshold parameter (e.g., stored in the distribution system sensor module 158, etc.) associated with the measured parameter and the threshold temperature. For example, the distribution system sensor module 158 can store a threshold temperature of 5.55 °C (42 degrees Fahrenheit (°F)) associated with supply sensor 142 (for example, in a situation where it is desired to maintain a distribution system coolant temperature below 5.55 °C (42°F) at the location of supply sensor 142, etc.) and the distribution system controller 134 can obtain a measured temperature from supply sensor 142. In this example, if the measured temperature is greater than 5.55 °C (42°F), then the distribution system controller 134 determines that operation of auxiliary cooler 124 is desired. If in block 208 the distribution system controller 134 determines that the operation of the auxiliary cooler 124 is not desired, then method 200 continues in block 210 with the activation (for example, via the distribution system pump module 154, etc.) by the distribution system controller 134 of the distribution system pump 110. For example, the distribution system controller 134 can provide a signal to the distribution system pump 110 to turn it on. After the distribution system pump 110 has been activated, the distribution system refrigerant can be cooled by the main cooler 120 and subsequently supplied to the cooling units 104. Method 200 continues in block 212 with the determination, by the distribution system controller 134 (for example, via the distribution system power module 160, etc.), whether the main power source 132 is supplying power to the distribution system controller 134. For example, the distribution system controller 134 may monitor a current and / or voltage supplied by the main power source 132 and determine that the main power source 132 is supplying power to the distribution system controller 134 when the current and / or voltage exceeds a threshold (for example, a minimum current, a minimum voltage, etc.). If the distribution system controller 134 determines that the main power source 132 is not supplying power to the distribution system controller 134, method 200 continues again to block 212. If the distribution system controller determines in block 212 that the main power source 132 is supplying power to the distribution system controller 134, method 200 continues in block 214 with the deactivation (for example, via the distribution system power module 160, etc.) by the distribution system controller 134 of the auxiliary power source 133. For example, the distribution system controller 134 can send a signal to the auxiliary power source 133 to instruct the shutdown of the auxiliary power source 133. tn« Lzn / cznz / q / υιλι As a result of deactivating auxiliary power source 133, auxiliary power may cease to be supplied to cooling units 104, the distribution system pump 110, the distribution system control valve 116, and the auxiliary cooler 124, for example. Method 200 then continues back to block 202.If in block 208 the distribution system controller 134 determines that the operation of the auxiliary chiller 124 is not desired, then method 200 continues in block 216 with the determination (for example, via the distribution system sensor module 158, etc.) by the distribution system controller 134, of whether the operation of the main chiller 120 is desired. This determination is based on whether the operation of the auxiliary chiller 124 alone is sufficient to maintain the distribution system coolant temperature below the threshold temperature. The distribution system controller 134 makes this determination by comparing (for example, via the distribution system sensor module 158, etc.)), by the distribution system controller 134, at least one measured parameter (e.g., the ambient parameter from the ambient sensor 136, the coolant parameter of the distribution system coolant measured by the main chiller sensor 138, the coolant parameter of the distribution system coolant measured by the auxiliary sensor 140, the coolant parameter of the distribution system coolant measured by the supply sensor 142, etc.) to a threshold parameter (e.g., stored in the distribution system sensor module 158, etc.) associated with the measured parameter and the threshold temperature. If in block 216 the distribution system controller 134 determines that the operation of the main chiller 120 is desired, then method 200 continues in block 218 with the repositioning (for example, via the distribution system control valve module 156, etc.), by the distribution system controller 134, of the distribution system control valve 116 from the first position to the third position (for example, where: (i) the third distribution system duct 118 is configured to receive distribution system refrigerant from the second distribution system duct 114 via the distribution system control valve 116 and (ii) the first auxiliary duct 126 is configured to receive distribution system refrigerant from the second distribution system duct 114 via the distribution system control valve 116).For example, the distribution system controller 134 can send a signal to the distribution system control valve 116 to cause the distribution system control valve 116 to rotate. As a result of being in the third position, the distribution system coolant is cooled by both the main cooler 120 and the auxiliary cooler 124. Method 200 continues in block 220 with the activation (for example, via the distribution system pump module 154, etc.) by the distribution system controller 134 of the distribution system pump 110. For example, the distribution system controller 134 can provide a signal to the distribution system pump 110 to turn it on. After the distribution system pump 110 has been activated, the distribution system coolant can be cooled by the main cooler 120 and subsequently supplied to the cooling units 104, and it can also be cooled by the auxiliary cooler 124 and subsequently supplied to the cooling units 104. Method 200 continues in block 222 with the determination, by the distribution system controller 134 (for example, via the distribution system power module 160, etc.), whether the main power source 132 is supplying power to the distribution system controller 134. For example, the distribution system controller 134 may monitor a current and / or voltage supplied by the main power source 132 and determine that the main power source 132 is supplying power to the distribution system controller 134 when the current and / or voltage exceeds a threshold (for example, a minimum current, a minimum voltage, etc.). If the distribution system controller 134 determines that the main power source 132 is not supplying power to the distribution system controller 134, method 200 continues again to block 222. If the distribution system controller determines in block 222 that the main power source 132 is supplying power to the distribution system controller 134, method 200 continues in block 224 with the deactivation (for example, via the distribution system power module 160, etc.) of the auxiliary power source 133 by the distribution system controller 134. For example, the distribution system controller 134 can send a signal to the auxiliary power source 133 to instruct it to shut down. As a result of deactivating the auxiliary power source 133, the supply of auxiliary power to the cooling units 104, the distribution system pump 110, the distribution system control valve 116, and the auxiliary chiller 124, for example, can cease. Method 200 continues in block 226 with the repositioning (for example, via the distribution system control valve module 156, etc.) by the distribution system controller 134 of the distribution system control valve 116 to the first position (for example, where the third distribution system line 118 is configured to receive distribution system refrigerant from the second distribution system line 114 via the distribution system control valve 116). For example, the distribution system controller 134 can send a signal to the distribution system control valve 116 to cause the valve to rotate from the third position to the first position. Method 200 then continues back to block 202. If in block 216 the distribution system controller 134 determines that operation of the main chiller 120 is not desired, then method 200 continues in block 228 with the repositioning (for example, via the distribution system control valve module 156, etc.) by the distribution system controller 134 of the distribution system control valve 116 from the first position to the second position (for example, where the first auxiliary duct 126 is configured to receive distribution system refrigerant from the second distribution system duct 114 via the distribution system control valve 116). For example, the distribution system controller 134 can send a signal to the distribution system control valve 116 to cause the distribution system control valve 116 to rotate.As a result of being in the second position, the distribution system coolant is cooled only by the auxiliary cooler 124. Method 200 containing block 220. In configurations where distribution system 102 does not include auxiliary cooler 124, first auxiliary duct 126, second auxiliary duct 128, and auxiliary sensor 140, method 200 does not include block 208, block 216, block 218, block 220, block 222, block 224, block 226, or block 228. As a result, block 206 is skipped directly to block 210. IV. Second example of refrigeration system operation with an auxiliary chiller As shown in Figure 3, a method 300 of utilizing the distribution system 102 to remove heat from the refrigeration unit 104 is shown. In method 300, the distribution system 102 includes the auxiliary cooler 124, the first auxiliary duct 126, the second auxiliary duct 128, and the auxiliary sensor 140. In method 300, the distribution system controller 134 is receiving power from the main power source 132 and with the distribution system control valve 116 in the first position (e.g., where the third distribution system duct 118 is configured to receive distribution system refrigerant from the second distribution system duct 114 through the distribution system control valve 116). Method 300 begins in block 302 with the determination (for example, via the distribution system sensor module 158, etc.) by the distribution system controller 134 of whether the auxiliary chiller 124 needs to operate. This determination is based on whether the operation of the main chiller 120 alone is sufficient to provide the cooling units 104 with the desired amount of cooling. For example, the distribution system controller 134 can compare a refrigerant parameter measured by the supply sensor 142 with a target refrigerant parameter associated with the supply sensor 142. In another example, the distribution system controller 134 can compare an ambient parameter measured by the ambient sensor 136 to a target ambient parameter.For example, when the ambient parameter indicates that the temperature is higher than a threshold associated with the desirable cooling of the cooling units 104, the distribution system controller 134 may determine that cooling is desired using the auxiliary cooler 124. If in block 302 the distribution system controller 134 determines that the operation of the auxiliary cooler 124 is not desired, then method 300 continues in block 304 with the determination (for example, via the distribution system control valve module 156, etc.) by the distribution system controller 134, whether the distribution system control valve 116 is in the first position (for example, where the third distribution system line 118 is configured to receive distribution system refrigerant from the second distribution system line 114 via the distribution system control valve 116). If the distribution system controller 134 determines that the distribution system control valve 116 is in the first position, then method 300 continues back to block 304. If the distribution system controller 134 determines that the distribution system control valve 116 is not in the first position (e.g., the distribution system control valve is in the second position, the distribution system control valve is in the third position, etc.), then method 300 continues in block 306 with the repositioning (e.g., via the distribution system control valve module 156, etc.) of the distribution system controller 134 to the first position. For example, the distribution system controller 134 can send a signal to the distribution system control valve 116 to cause the distribution system control valve 116 to rotate. The method then continues to block 302. If, in block 302, the distribution system controller 134 determines that the operation of the auxiliary chiller 124 is desired, method 300 continues in block 308 with the determination (for example, via the distribution system sensor module 158, etc.) by the distribution system controller 134, of whether the operation of the main chiller 120 is desired. This determination is based on whether the operation of the auxiliary chiller 124 alone is sufficient to provide the cooling units 104 with a desired amount of cooling. The distribution system controller 134 makes this determination by comparing (for example, via the distribution system sensor module 158, etc.)), by the distribution system controller 134, at least one measured parameter (e.g., the ambient parameter of the ambient sensor 136, the coolant parameter of the distribution system coolant measured by the main chiller sensor 138, the coolant parameter of the distribution system coolant measured by the auxiliary sensor 140, the coolant parameter of the distribution system coolant measured by the supply sensor 142, etc.) to a threshold parameter (e.g., stored in the distribution system sensor module 158, etc.) associated with the measured parameter and the threshold temperature. If in block 308 the distribution system controller 134 determines that operation of the main chiller 120 is desired, then method 300 continues in block 310 with the repositioning (for example, via the distribution system control valve module 156, etc.) by the distribution system controller 134, of the distribution system control valve 116 from the first position to the third position (for example, where: (i) the third distribution system conduit 118 is configured to receive distribution system refrigerant from the second distribution system conduit 114 via the distribution system control valve 116 and (ii) the first auxiliary conduit 126 is configured to receive distribution system refrigerant from the second distribution system conduit 114 via the distribution system control valve 116).For example, the distribution system controller 134 can send a signal to the distribution system control valve 116 to cause the distribution system control valve 116 to rotate. As a result of being in the third position, the distribution system coolant is cooled by both the main cooler 120 and the auxiliary cooler 124. Method 300 then continues to block 302. If in block 308 the distribution system controller 134 determines that operation of the main chiller 120 is not desired, then method 300 continues in block 312 with the repositioning (for example, via the distribution system control valve module 156, etc.) by the distribution system controller 134 of the distribution system control valve 116 from the first position to the second position (for example, where the first auxiliary line 126 is configured to receive distribution system refrigerant from the second distribution system line 114 via the distribution system control valve 116). For example, the distribution system controller 134 can send a signal to the distribution system control valve 116 to cause the distribution system control valve 116 to rotate.As a result of being in the second position, the distribution system coolant is cooled only by auxiliary cooler 124. Method 300 then continues to block 302. V. Example of the refrigeration unit Figure 4 represents refrigeration unit 104 according to various embodiments. Refrigeration unit 104 circulates the refrigerant from the refrigeration unit within a duct system of refrigeration unit 400 (e.g., plumbing system, piping system, etc.). In several embodiments, the refrigerant in the refrigeration unit is carbon dioxide (CO2). In some embodiments, the refrigerant in the refrigeration unit is different from the refrigerant in the distribution system. For example, the refrigerant in the refrigeration unit may be CO2, and the refrigerant in the distribution system may be a hydrofluorocarbon (HFC) refrigerant, a hydrofluoroolefin (HFO) refrigerant, or a natural refrigerant (e.g., a water-glycol refrigerant, etc.). Refrigeration unit 104 includes a pump from refrigeration unit 402 (e.g., positive displacement pump, positive displacement compressor, rotary pump, compressor, rotary compressor, etc.). The pump from refrigeration unit 402 is coupled to (e.g., attached to, in fluid communication with, secured to, connected to, fluidly coupled to, etc.) a first duct from refrigeration unit 404 of the duct system of refrigeration unit 400. The pump from refrigeration unit 402 receives refrigerant from the first duct of refrigeration unit 404. The pump from refrigeration unit 402 is also coupled to a second duct from refrigeration unit 406 of the duct system of refrigeration unit 400.The refrigeration unit 402 pump is configured to supply refrigerant from the refrigeration unit to the second duct of refrigeration unit 406. Refrigeration unit 104 also includes an upstream receiver 408 (e.g., tank, container, etc.). The upstream receiver 408 is connected to the second line of refrigeration unit 406 and configured to receive refrigerant from the second line of refrigeration unit 406. The upstream receiver 408 is also connected to a third line of refrigeration unit 410 in the refrigeration unit 400 duct system. The third line of refrigeration unit 410 is configured to receive refrigerant from the upstream receiver 408. In several embodiments, the upstream receiver 408 is configured so that vapor can flow freely from the upstream receiver 408 into the third line of the refrigeration unit 410 while liquid is retained within the upstream receiver 408. For example, an outlet of the upstream receiver 408 may be located in a higher portion of the upstream receiver 408 so that gravity diverts liquid away from the outlet, thereby causing the liquid to be retained within the upstream receiver 408. The liquid within the upstream receiver 408 may be heated over time, becoming vapor that can flow out of the upstream receiver 408. In some embodiments, the upstream receiver 408 is configured so that a maximum allowable liquid level within the upstream receiver 408 does not inhibit the operation of the refrigeration unit 104.For example, an outlet height within the upstream receiver 408 can be selected so that when a target amount of liquid accumulates within the upstream receiver 408, a portion of the liquid is able to flow out of the upstream receiver 408 and into the third duct of the refrigeration unit 410. Refrigeration unit 104 also includes a condenser 412 (e.g., heat exchanger, chiller, etc.). The third pipe from refrigeration unit 410 extends into the condenser 412. Additionally, a heat exchanger pipe from refrigeration unit 414 extends into the condenser 412. The heat exchanger pipe from refrigeration unit 414 is configured to be coupled to the inlet pipe of distribution system 122 and the outlet pipe of distribution system 130.When the refrigeration unit 414 heat exchanger is coupled to the distribution system inlet duct 122 and the distribution system outlet duct 130, the refrigeration unit 414 heat exchanger is configured to receive distribution system refrigerant from the distribution system inlet duct 122 and to supply distribution system refrigerant to the distribution system outlet duct 130. The condenser 412 may be a water-cooled condenser, an air-cooled condenser, or an adiabatic gas cooler of the type described in Applicant's Pending U.S. Patent Application No. 16 / 878,730. Condenser 412 is configured to cool the refrigerant in the refrigeration unit using the cooling provided by the refrigerant in the distribution system. Specifically, distribution system 102 is configured so that the refrigerant temperature in the distribution system inlet line of distribution system 122 is lower than the refrigerant temperature in the refrigeration unit within the third line of refrigeration unit 410. Distribution system 102 can control the refrigerant temperature in the distribution system inlet line of distribution system 122 (for example, based on the refrigerant temperature in the refrigeration unit within the third line of refrigeration unit 410, etc.) to provide a target amount of cooling to refrigeration unit 104. The heat exchanger duct of refrigeration unit 414 is configured to be selectively coupled to the inlet duct of distribution system 122 and configured to be selectively coupled to the outlet duct of distribution system 130. For example, the heat exchanger duct of refrigeration unit 414 may include a male coupling (e.g., connecting fitting, etc.) that is configured to be coupled to, and uncoupled from, a female coupling (e.g., connecting fitting, etc.) of the inlet duct of distribution system 122 and / or the outlet duct of distribution system 130. In this way, refrigeration unit 104 can be disconnected from the ductwork of distribution system 108. By disconnecting refrigeration unit 104 from the ductwork of distribution system t Lzn / cznz / q / uili 108, the refrigeration unit 104 can be replaced, serviced, or used independently of the distribution system ductwork 108 (for example, because the refrigerant in the refrigeration unit is kept separate from the refrigerant in the distribution system). During operation, the refrigerant in the refrigeration unit has a first temperature in the third line of the 410 refrigeration unit (e.g., upstream of the 412 condenser) and a second temperature inside the third line of the 410 refrigeration unit (e.g., downstream of the 412 condenser), and the second temperature is lower than the first. A difference between the second and first temperatures may be related to the configuration of the 412 condenser and / or the ambient conditions (e.g., temperature, humidity, etc.) surrounding the 412 condenser. Refrigeration unit 104 also includes a downstream receiver 416 (e.g., tank, container, etc.). The downstream receiver 416 is connected to the third line of refrigeration unit 410 and configured to receive refrigerant from the third line of refrigeration unit 410. The downstream receiver 416 is also connected to a fourth line of refrigeration unit 418 in the refrigeration unit 400 duct system. The fourth line of refrigeration unit 418 is configured to receive refrigerant from the downstream receiver 416. In several embodiments, the downstream receiver 416 is configured so that liquid can flow freely from the downstream receiver 416 into the fourth duct of the refrigeration unit 418, while vapor is retained within the downstream receiver 416. For example, an outlet of the downstream receiver 416 may be located in a lower portion of the downstream receiver 416 so that gravity deflects the vapor away from the outlet, thereby causing the vapor to be retained within the downstream receiver 416. The vapor within the downstream receiver 416 may be cooled over time, thus becoming a liquid that can flow out of the downstream receiver 416. Refrigeration unit 104 also includes an evaporator 420 (e.g., heat exchanger, chiller, etc.). The fourth pipe of refrigeration unit 418 extends into evaporator 420, and the first pipe of refrigeration unit 404 is coupled to the fourth pipe of refrigeration unit 418 downstream of evaporator 420. Evaporator 420 is configured to provide cooling to target 106 associated with refrigeration unit 104. As evaporator 420 cools target 106, the refrigerant in the refrigeration unit within evaporator 420 is heated. In operation, the refrigerant of the refrigeration unit has a first temperature in the fourth duct of the refrigeration unit 418 upstream of the evaporator tn« Lzn / cznz / q / υιλι 420 and a second temperature within the fourth duct of the refrigeration unit 418 downstream of the evaporator 420. A difference between the second temperature and the first temperature may be related to a configuration of the evaporator 420, ambient conditions (e.g., temperature, humidity, etc.) surrounding the evaporator 420, and / or a condition of target 106. The refrigeration unit 104 also includes a refrigeration unit controller 422. The refrigeration unit pump 402, the main power source 132, and the auxiliary power source 133 are electrically and / or communicatively coupled to the refrigeration unit controller 422. With respect to the main power source 132 and the auxiliary power source 133, the refrigeration unit controller 422 is configured to receive power from the main power source 132 and / or the auxiliary power source 133.Additionally, the refrigeration unit controller 422 may include a battery that is configured to supply power to the refrigeration unit controller 422 for a period of time between when the main power source 132 ceases to supply power to the refrigeration unit controller 422 and when the auxiliary power source 133 supplies power to the refrigeration unit controller 422 (for example, thus counting towards a start time associated with the auxiliary power source 133, etc.). In some embodiments, the condenser 412 is additionally electrically and / or communicatively coupled to the refrigeration unit controller 422. For example, the condenser 412 may include a controller, valves, fans, or other systems that could be controlled by the refrigeration unit controller 422. Similarly, the evaporator 420 may be electrically and / or communicatively coupled to the refrigeration unit controller 422. For example, the evaporator 420 may include a controller, valves, fans, or other systems that could be controlled by the refrigeration unit controller 422. Various sensors (e.g., temperature sensors, flow rate sensors, quality sensors, pressure sensors, etc.) can be additionally electrically and / or communicatively coupled to the refrigeration unit controller 422. These various sensors can be capable of determining refrigerant parameters (e.g., temperature, flow rate, quality, pressure, volumetric flow rate, mass flow rate, etc.) of the refrigerant in the refrigeration unit and / or the refrigerant in the second circuit. Refrigeration unit 104 also includes a refrigeration unit 424 sensor. The refrigeration unit 424 sensor is configured to measure a refrigerant parameter of the refrigerant in the refrigeration unit. The refrigeration unit 424 sensor can be located in various places within refrigeration unit 104 so that the refrigerant parameter at a target location can be monitored by the refrigeration unit 424 sensor. In some configurations, the refrigeration unit 424 sensor is connected to the second duct of refrigeration unit 406 upstream of the upstream receiver 408. For example, the refrigeration unit 424 sensor can measure the refrigerant temperature of the refrigeration unit within the second duct of refrigeration unit 406 upstream of the upstream receiver 408.The sensor of refrigeration unit 424 is electrically and / or communicatively coupled to the controller of refrigeration unit 422. As a result, the controller of refrigeration unit 422 is configured to receive the refrigerant parameter from the sensor of refrigeration unit 424. The controller for cooling unit 422 includes a processing circuit for cooling unit 426. The processing circuit for cooling unit 426 includes a processor for cooling unit 428 and a memory for cooling unit 430. The processor for cooling unit 428 may include a microprocessor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), other similar components, or combinations thereof. The memory for cooling unit 430 may include, but is not limited to, an electronic, optical, magnetic, or any other storage or transmission device capable of providing a processor, ASIC, FPGA, or other similar components with program instructions.The memory of the refrigeration unit 430 may include a memory chip, Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), flash memory, or any other suitable memory from which the refrigeration unit 422 controller can read instructions. The instructions may include code in any suitable programming language. The memory of refrigeration unit 430 may include several modules containing instructions configured to be implemented by the processor of refrigeration unit 428. The memory of refrigeration unit 430 includes a pump module for refrigeration unit 432. The pump module for refrigeration unit 432 contains instructions configured to be implemented by the processor of refrigeration unit 428 to control the operation of the pump in refrigeration unit 402. The memory of refrigeration unit 430 also includes a sensor module for refrigeration unit 434. The sensor module for refrigeration unit 434 contains instructions configured to be implemented by the processor of refrigeration unit 428 to receive communications (e.g., refrigerant parameters, environmental parameters, etc.) from the sensor in refrigeration unit 424.The memory of cooling unit 430 includes a power module for cooling unit 436. The power module for cooling unit 436 includes instructions that are configured to be implemented by the processor of cooling unit 428 to receive communications from the main power supply 132 and the auxiliary power supply 133. The controller for refrigeration unit 422 is configured to control the operation of the pump for refrigeration unit 402 (e.g., based on instructions stored in the pump module of refrigeration unit 432, etc.). For example, the controller for refrigeration unit 422 can control an operating parameter (e.g., voltage supplied to the pump of refrigeration unit 402, current supplied to the pump of refrigeration unit 402, etc.) of the pump for refrigeration unit 402 to achieve a target refrigerant level within the duct system of refrigeration unit 400. Additionally, the controller for refrigeration unit 422 can control the operation of the pump for refrigeration unit 402 based on whether power is supplied by the main power source 132 or the auxiliary power source 133. The controller for refrigeration unit 422 is configured to facilitate interactions with the sensor of refrigeration unit 424 (for example, based on instructions stored in the sensor module of refrigeration unit 434, etc.). For example, the controller for refrigeration unit 422 can periodically (for example, once an hour, etc.) use the refrigerant parameter provided by the sensor of refrigeration unit 424. Additionally, the controller for refrigeration unit 422 can facilitate interactions with the sensor of refrigeration unit 424 based on whether power is supplied by the main power source 132 or the auxiliary power source 133. The controller for refrigeration unit 422 is configured to control the operation of auxiliary power source 133 (for example, based on instructions stored in the power module of refrigeration unit 436, etc.). For example, the controller for refrigeration unit 422 can cause auxiliary power source 133 to be turned on in response to a determination that the primary power source 132 has failed and / or is unavailable. Refrigeration unit 104 includes a high-pressure relief valve (e.g., bleed valve) from refrigeration unit 438, located in conjunction with the second line of refrigeration unit 406. The high-pressure relief valve of refrigeration unit 438 is configured to open when the refrigerant pressure within the second line of refrigeration unit 406 exceeds a high-pressure threshold. In this way, the high-pressure relief valve of refrigeration unit 438 protects refrigeration unit 104 from the impact of over-pressurized refrigerant from the refrigeration unit. In several modes, the high-pressure threshold is approximately equal to (e.g., within 5% of, etc.) between 5000 kPa (50 bar) and 7500 kPa (75 bar), inclusive (e.g., 4800 kPa (48 bar), 5000 kPa (50 bar), 5500 kPa (55 bar), 6500 kPa (65 bar), 7500 kPa (75 bar), 7700 kPa (77 bar), etc.). Refrigeration unit 104 also includes a low-pressure relief valve (e.g., bleed valve) from refrigeration unit 440, located along the first line of refrigeration unit 404. The low-pressure relief valve of refrigeration unit 440 is configured to open when the refrigerant pressure from the refrigeration unit within the first line of refrigeration unit 404 exceeds a low-pressure threshold. In this way, the low-pressure relief valve of refrigeration unit 440 protects refrigeration unit 104 from over-pressurized refrigerant from the refrigeration unit. The high-pressure threshold is higher than the low-pressure threshold. In various configurations, the low-pressure threshold is approximately equal to (e.g., within 5% of, etc.).) between 3500 kPa (35 bar) and 5000 kPa (50 bar), inclusive (for example, 3300 kPa (33 bar), 3500 kPa (35 bar), 4000 kPa (40 bar), 4500 kPa (45 bar), 5000 kPa (50 bar), 5200 kPa (52 bar), etc.). In several embodiments, the refrigeration unit 104 additionally includes a backup power source 441 (e.g., generator, battery bank, capacitor, etc.). The backup power source 441 is electrically coupled to, and configured to supply power to and receive power from, the refrigeration unit controller 422. The backup power source 441 is configured to supply power to the refrigeration unit 104 when the refrigeration unit 104 is disconnected from the main power source 132 and the auxiliary power source 133 (e.g., during the warm-up of the auxiliary power source 133, during the transport of the refrigeration unit 104, etc.). In some embodiments, the backup power source 441 includes a controller, valves, fans, or other systems that could utilize power from the backup power source 441.As explained in more detail herein, the standby power supply 441 can enable the refrigeration unit 104 to perform various functions after being disconnected from the main power supply 132 and the auxiliary power supply 133. VI. Example of a transfer system In several configurations, the refrigeration unit 104 also includes a transfer system 442. As explained in more detail herein, the transfer system 442 is configured to facilitate the transfer (e.g., ventilation, etc.) of the refrigeration unit refrigerant from upstream of the refrigeration unit 402 pump to downstream of the refrigeration unit 402 pump, thereby decreasing the refrigerant pressure of the refrigeration unit downstream of the refrigeration unit 402 pump. tn« Lzn / cznz / q / υιλι Transfer system 442 includes a conduit from transfer system 444. The transfer system duct 444 is configured to receive refrigerant from the refrigeration unit upstream of the refrigeration unit pump 402 and is coupled to the second duct of the refrigeration unit 406 (e.g., downstream of the refrigeration unit pump 402). The transfer system 442 also includes an upstream control valve for the transfer system 446 (e.g., three-way valve, bullet valve, solenoid valve, etc.) arranged in conjunction with the first duct of refrigeration unit 404 (e.g., coupled to an upstream portion of the first duct of refrigeration unit 404 and coupled to a downstream portion of the first duct of refrigeration unit 404). The upstream control valve for the transfer system 446 is also coupled to the duct of the transfer system 444.The upstream control valve of transfer system 446 is configured to selectively supply refrigerant from the refrigeration unit from upstream of the upstream control valve of transfer system 446 to the first line of refrigeration unit 404 downstream of the upstream control valve of transfer system 446 and / or to transfer line 444. The upstream control valve of transfer system 446 is also configured to supply refrigerant from the refrigeration unit from transfer line 444 to the first line of refrigeration unit 404 downstream of the upstream control valve of transfer system 446. The upstream control valve of transfer system 446 is operable between a first position, where the first conduit of refrigeration unit 404 (e.g., downstream of the upstream control valve of transfer system 446) is configured to receive refrigerant from the first conduit of refrigeration unit 404 (e.g., upstream of the upstream control valve of transfer system 446) through the upstream control valve of transfer system 446, and a second position, where the transfer conduit 444 is configured to receive refrigerant from the first conduit of refrigeration unit 404 (e.g., upstream of the upstream control valve of transfer system 446) through the upstream control valve of transfer system 446.and a third position, wherein: (i) the first conduit of refrigeration unit 404 is configured to receive refrigerant from the first conduit of refrigeration unit 404 through the upstream control valve of transfer system 446 and (ii) transfer conduit 444 is configured to receive refrigerant from the first conduit of refrigeration unit 404 through the upstream control valve of transfer system 446. In some embodiments, the upstream control valve of the transfer system 446 is additionally operable in a fourth position in which the first conduit of the refrigeration unit 404 (e.g., upstream of the upstream control valve of the transfer system 446) is isolated from the first conduit of the refrigeration unit 404 (e.g., downstream of the upstream control valve of the transfer system 446) and the transfer conduit 444. As a result, the pump of the refrigeration unit 402 does not receive refrigerant from the refrigeration unit of the upstream control valve of the transfer system 446. Additionally, the transfer conduit 444 does not receive refrigerant from the refrigeration unit of the upstream control valve of the transfer system 446. In some embodiments, the upstream control valve of the transfer system 446 is additionally operable in a fifth position where the transfer line 444 is configured to supply refrigerant from the refrigeration unit to the first line of the refrigeration unit 404 (e.g., downstream of the upstream control valve of the transfer system 446) through the upstream control valve of the transfer system 446. The transfer system 442 also includes a downstream control valve of the transfer system 447 (e.g., three-way valve, ball valve, solenoid valve, etc.) arranged in conjunction with the second duct of the refrigeration unit 406 (e.g., coupled to an upstream portion of the second duct of the refrigeration unit 406 and coupled to a downstream portion of the second duct of the refrigeration unit 406). The downstream control valve of the transfer system 447 is also coupled to the duct of the transfer system 444.The downstream control valve of transfer system 447 is configured to selectively supply refrigerant from the refrigeration unit upstream of the downstream control valve of transfer system 447 to the second refrigeration unit 406 line downstream of the downstream control valve of transfer system 447 and / or to transfer line 444. The downstream control valve of transfer system 447 is also configured to receive refrigerant from the refrigeration unit from transfer line 444 and supply refrigerant from the refrigeration unit to the first refrigeration unit 404 line downstream of the downstream control valve of transfer system 447. The downstream control valve of transfer system 447 is operable between a first position, where the second conduit of refrigeration unit 406 (e.g., downstream of the downstream control valve of transfer system 447) is configured to receive refrigerant from the second conduit of refrigeration unit 406 (e.g., upstream of the downstream control valve of transfer system 447) via the downstream control valve of transfer system 447, and a second position, where the transfer conduit 444 is configured to supply refrigerant from the refrigeration unit to the second conduit of refrigeration unit 406 (e.g., downstream of the downstream control valve of transfer system 447) via the downstream control valve of transfer system 447. In some embodiments, the downstream control valve of transfer system 447 is additionally operable in a third position where: (i) the second conduit of refrigeration unit 406 is configured to receive refrigerant from the second conduit of refrigeration unit 406 through the downstream control valve of transfer system 447 and (ii) the transfer conduit 444 is configured to receive refrigerant from the second conduit of refrigeration unit 406 through the downstream control valve of transfer system 447. In some embodiments, the downstream control valve of the transfer system 447 is additionally operable in a fourth position where the transfer line 444 is configured to receive refrigerant from the refrigeration unit from the first line of the refrigeration unit 404 (e.g., upstream of the upstream control valve of the transfer system 446) through the upstream control valve of the transfer system 446. The downstream control valve of transfer system 447 can cooperate with the upstream control valve of transfer system 446 to control when refrigerant from the refrigeration unit is supplied through the transfer line 444 in order to bypass the pump of refrigeration unit 402. By bypassing the pump of refrigeration unit 402, the refrigerant from the refrigeration unit is vented from the low-pressure side of refrigeration unit 104 to the high-pressure side of refrigeration unit 104. Such venting may be desirable when refrigeration unit 104 is not circulating refrigerant from the refrigeration unit (e.g., during a power outage, etc.).and a refrigerant pressure in the refrigeration unit upstream of the refrigeration unit 402 pump (for example, within the first duct of refrigeration unit 404) exceeds a pressure threshold that is lower than the low-pressure threshold associated with the low-side PRV of refrigeration unit 440. As a result of venting refrigerant from the refrigeration unit from the first duct of refrigeration unit 405 to the second duct of refrigeration unit 406, transfer system 442 lowers the refrigerant pressure in the refrigeration unit within the first duct of refrigeration unit 404. In this way, transfer system 442 can mitigate the increase in refrigeration unit refrigerant pressure that can occur when the refrigerant temperature of the refrigeration unit rises. tn« Lzn / cznz / q / υιλι Additionally, the downstream control valve of transfer system 447 can cooperate with the upstream control valve of transfer system 446 to control when refrigerant from the refrigeration unit is supplied through the transfer line 444 to bypass the upstream receiver 408, condenser 412, downstream receiver 416, and evaporator 420. By bypassing the upstream receiver 408, condenser 412, downstream receiver 416, and evaporator 420, the refrigerant from the refrigeration unit is supplied as relatively hot vapor back to the first line of refrigeration unit 404. This can raise the temperature of the refrigerant received by the pump of refrigeration unit 402.By controlling the upstream control valve of transfer system 446 and the downstream control valve of transfer system 447, superheating of the target refrigerant received by the pump of refrigeration unit 402 can be achieved. Achieving target superheating facilitates the desired operation of the pump of refrigeration unit 402. Before achieving target superheating, the pump of refrigeration unit 402 can be controlled by a variable speed drive or other control mechanism to protect the pump of refrigeration unit 402. The memory of refrigeration unit 430 also includes a transfer system control valve module 448. The transfer system control valve module 448 includes instructions that are configured to be implemented by the processor of refrigeration unit 428 to control the operation of the upstream transfer system control valve 446 and the downstream transfer system control valve 447. The controller of refrigeration unit 422 is configured to control the operation of the upstream transfer system control valve 446 (e.g., based on the instructions stored in the transfer system control valve module 448, etc.) and the downstream transfer system control valve 447 (e.g., based on the instructions stored in the transfer system control valve module 448, etc.).For example, the refrigeration unit controller 422 can selectively reposition (for example, from the first position to the second position, from the first position to the third position, from the second position to the first position, from the second position to the third position, from the third position to the first position, from the third position to the second position, etc.) the upstream control valve of the transfer system 446 and / or the downstream control valve of the transfer system 447. Additionally, the refrigeration unit controller 422 can control the operation of the upstream control valve of the transfer system 446 and / or the downstream control valve of the transfer system 447 based on whether power is supplied by the main power source 132, the auxiliary power source 133, or the backup power source 441. For example, the refrigeration unit controller 422 can initiate a timer in response to a power loss event (e.g., in response to a loss of power from the main power source 132, etc.) and compare the timer to a threshold. When the timer exceeds the threshold, the refrigeration unit controller 422 can reposition the upstream control valve of the transfer system 446 (e.g., from the first position to the second position, etc.).) and / or the downstream control valve of the transfer system 447 to cause the refrigerant from the refrigeration unit to flow from the first duct of the refrigeration unit 404 to the transfer duct 444. VIL Example of the expansion system In several configurations, the refrigeration unit 104 also includes an expansion system 450. As explained in more detail herein, the expansion system 450 is configured to facilitate the expansion of the refrigerant from the refrigeration unit upstream of the pump of refrigeration unit 402, thereby lowering the refrigerant pressure of the refrigeration unit upstream of the pump of refrigeration unit 402. Expansion system 450 includes a first expansion system 452 line. The first expansion system 452 line is connected to the first line of refrigeration unit 404. Expansion system 450 also includes a second expansion system 454 line. The second expansion system 454 line is connected to the second line of refrigeration unit 406. Expansion system 450 also includes a third expansion system 458 line. The third expansion system 458 line is configured to receive refrigerant from the refrigeration unit via the first expansion system 452 line and the second expansion system 454 line, and to supply refrigerant from the refrigeration unit to the first expansion system 452 line and the second expansion system 454 line. The expansion system 450 also includes an upstream control valve for the expansion system 460 (e.g., three-way valve, ball valve, solenoid valve, etc.). The upstream control valve for the expansion system 460 is connected to the first line of the expansion system 452 and the third line of the expansion system 456. The upstream control valve for the expansion system 460 is configured to selectively supply refrigerant from the refrigeration unit from the first line of the expansion system 452, and therefore from the first line of the refrigeration unit 404, to the third line of the expansion system 456, and to supply refrigerant from the refrigeration unit from the third line of the expansion system 456 to the first line of the expansion system 452, and therefore to the first line of the refrigeration unit 404.In some embodiments, the upstream expansion system control valve 460 includes an upstream expansion system control valve vent 462 that is configured to expel refrigerant from the refrigeration unit 104 (e.g., to the atmosphere). The upstream control valve of expansion system 460 is operable between a first position, where the first line of expansion system 452 is not connected to the third line of expansion system 456 (for example, so that the first line of refrigeration unit 404 is isolated from the third line of expansion system 456), and a second position where the first line of expansion system 452 is connected to the third line of expansion system 456 (for example, so that the first line of refrigeration unit 404 is not isolated from the third line of expansion system 456). As a result, the upstream control valve of expansion system 460 is configured to control the flow of refrigerant from the refrigeration unit between the first line of refrigeration unit 404 and the third line of expansion system 456. In some embodiments, the upstream control valve of the expansion system 460 is additionally operable in a third position in which the first conduit of the expansion system 452 is connected to the upstream control valve vent of the expansion system 462. As a result, the upstream control valve of the expansion system 460 is configured to vent the refrigerant from the refrigeration unit of the first conduit of the expansion system 452, and therefore from the first conduit of the refrigeration unit 404, to the atmosphere. In some embodiments, the upstream control valve of the expansion system 460 is additionally operable in a fourth position in which the third conduit of the expansion system 456 is connected to the upstream control valve vent of the expansion system 462. As a result, the upstream control valve of the expansion system 460 is configured to vent the refrigerant from the refrigeration unit of the third conduit of the expansion system 456 to the atmosphere. The expansion system 450 also includes a downstream control valve for the expansion system 464 (e.g., three-way valve, ball valve, solenoid valve, etc.). The downstream control valve for the expansion system 464 is connected to the second line of the expansion system 454 and the third line of the expansion system 456. The downstream control valve for the expansion system 464 is configured to selectively supply refrigerant from the refrigeration unit of the second line of the expansion system 454, and therefore from the second line of the refrigeration unit 406, to the third line of the expansion system 456, and to supply refrigerant from the refrigeration unit of the third line of the expansion system 456 to the second line of the expansion system 454, and therefore to the second line of the refrigeration unit 406.In some embodiments, the downstream control valve of the expansion system 464 includes a downstream control valve vent of the expansion system 466 that is configured to expel refrigerant from the refrigeration unit of the refrigeration unit 104 (e.g., to the atmosphere). The downstream control valve of expansion system 464 is operable between a first position, where the second conduit of expansion system 454 is not connected to the third conduit of expansion system 456 (e.g., so that the second conduit of refrigeration unit 406 is isolated from the third conduit of expansion system 456), and a second position where the second conduit of expansion system 454 is connected to the third conduit of expansion system 456 (e.g., so that the second conduit of refrigeration unit 406 is not isolated from the third conduit of expansion system 456). As a result, the downstream control valve of expansion system 464 is configured to control the flow of refrigerant from the refrigeration unit between the second conduit of refrigeration unit 406 and the third conduit of expansion system 456. In some embodiments, the downstream control valve of expansion system 464 is additionally operable in a third position in which the second conduit of expansion system 454 is connected to the downstream control valve vent of expansion system 466. As a result, the downstream control valve of expansion system 464 is configured to vent refrigerant from the refrigeration unit's second conduit of expansion system 454, and therefore from the second conduit of refrigeration unit 406, to the atmosphere. In some embodiments, the downstream control valve of the expansion system 464 is additionally operable in a fourth position in which the third conduit of the expansion system 456 is connected to the downstream control valve vent of the expansion system 466. As a result, the downstream control valve of the expansion system 464 is configured to vent the refrigerant from the refrigeration unit of the third conduit of the expansion system 456 to the atmosphere. The expansion system 450 also includes an expansion tank 468 (e.g., vessel, etc.). The expansion tank 468 is arranged along the third conduit of the expansion system 456. As explained in more detail herein, the expansion tank 468 is configured to hold the refrigerant from the refrigeration unit. The memory of refrigeration unit 430 also includes a valve module tn« Lzn / cznz / q / uli for expansion system control 470. The expansion system control valve module 470 includes instructions that are configured to be implemented by the processor of refrigeration unit 428 to control the operation of the upstream control valve of expansion system 460 and the downstream control valve of expansion system 464. The controller of refrigeration unit 422 is configured to control the operation of the upstream control valve of expansion system 460 (e.g., based on the instructions stored in the expansion system control valve module 470, etc.).and to control the operation of the downstream control valve of the expansion system 464 (for example, based on instructions stored in the control valve module of the expansion system 470, etc.). For example, the controller of the refrigeration unit 422 can selectively reposition (for example, from the first position to the second position, from the first position to the third position, from the second position to the first position, from the second position to the third position, from the third position to the first position, from the third position to the second position, etc.) the upstream control valve of the expansion system 460 and / or the downstream control valve of the expansion system 464. Additionally, the refrigeration unit controller 422 can control the operation of the upstream control valve of the expansion system 460 and / or the downstream control valve of the expansion system 464 based on whether power is supplied by the main power source 132, the auxiliary power source 133, or the backup power source 441. For example, the refrigeration unit controller 422 can initiate a timer in response to a power loss event (e.g., in response to a loss of power from the main power source 132, etc.) and compare the timer to a threshold. When the timer exceeds the threshold, the refrigeration unit controller 422 can reset the upstream control valve of the expansion system 460 and / or the downstream control valve of the expansion system 464. When refrigeration unit 104 is receiving power from the main power source 132, the upstream control valve of the expansion system 460 is in the second position (e.g., where the first pipe of expansion system 452 is connected to the third pipe of expansion system 456) and the downstream control valve of the expansion system 464 is in the first position (e.g., where the second pipe of expansion system 454 is not connected to the third pipe of expansion system 456). As a result, refrigerant from the refrigeration unit (e.g., in vapor form, etc.) is supplied from the first pipe of refrigeration unit 404 to the expansion tank 468. When the refrigeration unit 104 ceases to receive power from the main power source 132, the auxiliary power source 133, or the backup power source 441 (for example, such as when the refrigeration unit 104 has been disconnected from the refrigeration system 100 and is in transit, etc.), the upstream control valve of the expansion system 460 changes from the second position to the first position (for example, where the first pipe of the expansion system 452 is not connected to the third pipe of the expansion system 456), and the downstream control valve of the expansion system 464 changes from the first position to the second position (for example, where the second pipe of the expansion system 454 is connected to the third pipe of the expansion system 456). As a result, the refrigerant in the refrigeration unit (for example, in liquid form, etc.)The expansion tank 468 is supplied from the second line of refrigeration unit 406 to the expansion tank 468. The expansion tank 468 thus provides a volume increase for the refrigerant from the upstream refrigeration unit pump of refrigeration unit 402, thereby decreasing the refrigerant pressure of the refrigerant unit within the second line of refrigeration unit 406. By decreasing the refrigerant pressure of the refrigerant unit within the second line of refrigeration unit 406, the expansion system 450 functions to extend the amount of time before the refrigerant pressure of the refrigerant unit within the second line of refrigeration unit 406 exceeds the high-pressure threshold associated with the high PRV of refrigeration unit 438. When refrigeration unit 104 receives power again from the main power source 132 (for example, after refrigeration unit 104 has been reconnected to refrigeration system 100, etc.) or receives power from auxiliary power source 133, the upstream control valve of the expansion system 460 changes from the first position to the second position (for example, where the first pipe of expansion system 452 is connected to the third pipe of expansion system 456), and the downstream control valve of the expansion system 464 changes from the second position to the first position (for example, where the second pipe of expansion system 454 is not connected to the third pipe of expansion system 456). As a result, refrigerant from the expansion tank 468 is supplied to the first pipe of refrigeration unit 404. In several embodiments, the expansion tank 468 is a replaceable tank configured to be coupled to, and uncoupled from, the third conduit of the expansion system 456. For example, the third conduit of the expansion system 456 may include two male couplings, and the expansion tank 468 may include two female couplings, each configured to be coupled to, and uncoupled from, one of the male couplings of the third conduit of the expansion system 456. In such embodiments, the expansion tank 468 may be designed, for example, to accommodate elevated temperatures and pressures required for shipping. When the expansion tank 468 is not connected to the third pipe of the expansion system 456, the upstream control valve of the expansion system 460 is in the first position (for example, where the first pipe of the expansion system 452 is not connected to the third pipe of the expansion system 456) and the downstream control valve of the expansion system 464 is in the first position (for example, where the second pipe of the expansion system 454 is not connected to the third pipe of the expansion system 456). As a result, the refrigerant from the refrigeration unit does not flow through the third pipe of the expansion system 456.Once the expansion tank 468 has been coupled to the third conduit of the expansion system 456, the upstream control valve of the expansion system 460 can be changed from the first position and / or the downstream control valve of the expansion system 464 can be changed from the first position. In some configurations, expansion tank 468 is charged with refrigerant from the refrigeration unit before being connected to the third line of expansion system 456. As a result, additional refrigerant can be added to refrigeration unit 104 by connecting expansion tank 468 to the third line of expansion system 456. This can be particularly beneficial after, for example, a power outage when a portion of the refrigeration unit's refrigerant has been vented via the high-pressure PRV of refrigeration unit 438 and / or the low-pressure PRV of refrigeration unit 440.In these modes, the refrigerant for the refrigeration unit can be supplied from the expansion tank 468 into the first duct of the refrigeration unit 404 by repositioning the upstream control valve of the transfer system 446 and / or into the second duct of the refrigeration unit 406 by repositioning the downstream control valve of the transfer system 447. The refrigerant for the refrigeration unit can be supplied from the expansion tank 468 into the first duct of the refrigeration unit 404 and / or the second duct of the refrigeration unit 406 in response to, for example, a refrigerant parameter of the refrigeration unit that is outside a target threshold.For example, if a refrigerant pressure in the refrigeration unit falls below a target pressure, the upstream control valve of the transfer system 446 and / or the downstream control valve of the transfer system 447 may be caused to supply refrigerant from the expansion tank 468 to the first duct of the refrigeration unit 404 and / or the second duct of the refrigeration unit 406. In some situations, it may be desirable to purge air into the third line of the expansion system 456 before supplying refrigerant from the expansion tank 468 to the first line of the refrigeration unit 404 and / or the second line of the refrigeration unit 406. In these situations, and after connecting the expansion tank 468 to the third line of the expansion system 456, the upstream control valve of the expansion system 460 can be set to the fourth position (for example, where the third line of the expansion system 456 is connected to the upstream control valve vent of the expansion system 462 and isolated from the first line of the expansion system 452) so that the pressurized refrigerant in the expansion tank 468 purges air from the third line of the expansion system 456 via the upstream control valve vent of the expansion system 462.Similarly, the downstream control valve of expansion system 464 can be caused to be in the fourth position (e.g., where the third conduit of expansion system 456 is connected to the downstream control valve vent of expansion system 466 and isolated from the second conduit of expansion system 454) so ​​that the pressurized refrigerant inside the expansion tank 468 purges air from the third conduit of expansion system 456 via the downstream control valve vent of expansion system 466. HIV. Example of a cooling system In several configurations, the refrigeration unit 104 also includes a cooling system 472. As explained in more detail herein, the cooling system 472 is configured to facilitate the cooling of the refrigeration unit refrigerant from upstream of the refrigeration unit pump 402 using the refrigeration unit refrigerant within, or near, the evaporator 420. Cooling system 472 includes a first conduit from cooling system 474. As explained in more detail herein, the first conduit of cooling system 474 is configured to receive refrigerant from the cooling unit via the second conduit of cooling unit 406. Cooling system 472 also includes a second conduit from cooling system 476. As explained in more detail herein, the second conduit of cooling system 476 is configured to supply refrigerant from the cooling unit to the first conduit of cooling unit 404. Cooling system 472 also includes a cooling system control valve 478 (e.g., three-way valve, ball valve, solenoid valve, etc.). The cooling system control valve 478 is arranged along the second duct of refrigeration unit 406 and coupled to the first duct of cooling system 474. The cooling system control valve 478 is configured to selectively supply refrigerant from the second duct of refrigeration unit 406 (e.g., upstream of the cooling system control valve 478, etc.) to the second duct of refrigeration unit 406 (e.g., downstream of the cooling system control valve 478, etc.).) and to supply the refrigerant from the cooling unit's second duct of the cooling unit 406 (for example, upstream of the control valve of the cooling system 478, etc.) to the first duct of the cooling system 474. The cooling system control valve 478 is operable between a first position, where the second conduit of the cooling unit 406 (e.g., upstream of the cooling system control valve 478, etc.) is connected to the second conduit of the cooling unit 406 (e.g., so that the second conduit of the cooling unit 406 is isolated from the first conduit of the cooling system 474) and a second position where the second conduit of the cooling unit 406 (e.g., upstream of the cooling system control valve 478, etc.) is connected to the first conduit of the cooling system 474 (e.g., so that the second conduit of the cooling unit 406 is not isolated from the first conduit of the cooling system 474).As a result, the cooling system control valve 478 is configured to control a flow of refrigerant from the cooling unit between the second duct of the cooling unit 406 and the first duct of the cooling system 474. In some embodiments, the cooling system control valve 478 is additionally operable in a third position in which the second conduit of the refrigeration unit 406 (e.g., upstream of the cooling system control valve 478, etc.) is connected to both the first conduit of the cooling system 474 and the second conduit of the refrigeration unit 406 (e.g., downstream of the cooling system control valve 478, etc.). Cooling system 472 also includes a cooling tank 480 (e.g., vessel, etc.). Cooling tank 480 is connected to the first line of cooling system 474 and the second line of cooling system 476. As explained in more detail herein, cooling tank 480 is configured to receive refrigerant from the cooling unit via the first line of cooling system 474, supply refrigerant from the cooling unit to the second line of cooling system 476, and contain the refrigerant from the cooling unit. Cooling tank 480 is located in close physical proximity to evaporator 420. For example, cooling tank 480 may be located within a target distance of evaporator 420 (i.e., such that no portion of cooling tank 480 is separated from the evaporator by a distance greater than the target distance). In various embodiments, the target distance is approximately between 5.08 cm (2 in.) and 40.64 cm (16 in.), inclusive. As a result, the cooling provided by evaporator 420 is supplied to cooling tank 480 (e.g., in conjunction with objective 106, etc.). Therefore, in the event that refrigerant circulation from the refrigeration unit through refrigeration unit 104 ceases, the cooling provided by evaporator 420 (e.g., due to refrigerant from the refrigeration unit remaining within evaporator 420, etc.) can be supplied to cooling tank 480. Cooling tank 480 can contain refrigerant during such situations. Therefore, evaporator 420 can be used to provide cooling to the refrigerant from the refrigeration unit when refrigerant circulation from the refrigeration unit through refrigeration unit 104 ceases. As a result, an increase in the refrigerant pressure of the refrigeration unit can be minimized during such situations. The cooling system 472 also includes a first cooling system check valve 482 (e.g., one-way valve, etc.) arranged along the first cooling system conduit 474. The first cooling system check valve 482 can prevent backflow of refrigerant from the cooling unit of the cooling tank 480 to the second conduit of the cooling unit 406. The cooling system 472 also includes a second cooling system check valve 484 (e.g., one-way valve, etc.) arranged along the second cooling system conduit 476. The second cooling system check valve 484 can prevent backflow of refrigerant from the cooling unit's first conduit 404 to the cooling tank 480. The memory of refrigeration unit 430 also includes a cooling system control valve module 486. The cooling system control valve module 486 includes instructions that are configured to be implemented by the processor of refrigeration unit 428 to control the operation of cooling system control valve 478. The controller of refrigeration unit 422 is configured to control the operation of cooling system control valve 478 (for example, based on the instructions stored in the cooling system control valve module 486, etc.).For example, the refrigeration unit controller 422 can selectively reposition (for example, from the first position to the second position, from the first position to the third position, from the second position to the first position, from the second position to the third position, from the third position to the first position, from the third position to the second position, etc.) the cooling system control valve 478. Additionally, the refrigeration unit controller 422 can control the operation of the cooling system control valve 478 based on whether power is supplied by the main power source 132, the auxiliary power source 133, or the backup power source 441. For example, the refrigeration unit controller 422 can start a timer in response to a power loss event (e.g., in response to a loss of power from the main power source 132, etc.) and compare the timer to a threshold. When the timer exceeds the threshold, the refrigeration unit controller 422 can reset the cooling system control valve 478. When refrigeration unit 104 is receiving power from the main power source 132, the cooling system control valve 478 is in the first position (for example, where the second duct of refrigeration unit 406 is isolated from the first duct of cooling system 474). As a result, the refrigerant from the refrigeration unit is diverted to cooling system 472. When the refrigeration unit 104 ceases to receive power from the main power source 132, the auxiliary power source 133, or the standby power source 441, the cooling system control valve 478 switches from the first position to the second position (e.g., where the second duct of the refrigeration unit 406 is connected to the first duct of the cooling system 474). As a result, the refrigerant from the refrigeration unit flows from the second refrigeration unit line 406 upstream of the cooling system control valve 478 into the cooling system control valve 478 and from the cooling system control valve 478 into the first cooling system line 474. The refrigerant from the refrigeration unit then flows through the first cooling system check valve 482 and into the cooling tank 480. The cooling tank 480 receives cooling from the evaporator 420. This cooling causes the refrigerant from the refrigeration unit to cool within the cooling tank 480. By cooling the refrigerant from the refrigeration unit, a rise in the pressure of the refrigerant from the refrigeration unit due to the surrounding environment is minimized. Additionally, cooling tank 480 provides an increase in volume for the refrigerant of the refrigeration unit upstream of the pump of refrigeration unit 402, thereby decreasing the refrigerant pressure of the refrigeration unit within the second line of refrigeration unit 406. By decreasing the refrigerant pressure of the refrigeration unit within the second line of refrigeration unit 406, the cooling system 472 functions to lengthen the amount of time before the refrigerant pressure of the refrigeration unit within the second line of refrigeration unit 406 exceeds the high-pressure threshold associated with the high PRV of refrigeration unit 438. The second cooling system conduit 476 is coupled to the cooling tank 480 to minimize liquid transfer in the second conduit of the cooling system 476. For example, the second cooling system conduit 476 and / or the cooling tank 480 can be configured so that vapor can flow freely from the cooling tank 480 into the second conduit of the cooling system 476 while liquid is retained within the cooling tank 480. In some embodiments, an outlet of the cooling tank 480 that is coupled to the second cooling system conduit 476 is located in a higher portion of the cooling tank 480 so that gravity deflects the liquid away from the outlet, thereby causing the liquid to be retained within the cooling tank 480.By being configured to mitigate the transmission of liquid to the second conduit of the cooling system 476, the cooling unit pump 402 can be protected from cavitation. While the refrigeration unit 104 is not receiving power from the main power source 132, the auxiliary power source 133, or the standby power source 441, the refrigerant of the refrigeration unit can flow from the cooling tank 480 into the second cooling system conduit 476, through the second cooling system check valve 484, and into the first refrigeration unit conduit 404. As a result, the low-pressure PRV of the refrigeration unit 440 continues to provide a mechanism to mitigate against undesirable refrigerant pressures in the refrigeration unit. When the refrigeration unit 104 receives power again from the main power source 132 (for example, after the refrigeration unit 104 has ceased to receive power from the main power source 132) or receives power from the auxiliary power source 133, the cooling system control valve 478 changes from the second position to the first position (for example, where the second duct of the refrigeration unit 406 is isolated from the first duct of the cooling system 474). Although vapor can exit cooling tank 480 via the second conduit of cooling system 476, liquid can be retained within cooling tank 480. In some embodiments, it is desired that the liquid exit cooling tank 480. In such embodiments, cooling tank 480 is heated to cause the liquid to change to vapor, which can then exit cooling tank 480 via the second conduit of cooling system 476. In several embodiments, refrigeration unit 104 includes a cooling tank heater 488 (e.g., electric heater, heat exchanger, etc.) that is coupled to refrigeration unit 104 and configured to heat liquid within refrigeration unit 104.For example, the refrigeration unit controller 422 can cause the cooling tank heater 488 to turn on, and thus provide heating to the liquid inside the cooling tank 480, in response to the refrigeration unit 104 receiving power again from the main power source 132 or the auxiliary power source 133. tn« Lzn / cznz / q / υιλι IX. First example of transfer system operation As shown in Figure 5, a method 500 of utilizing the transfer system 442 to transfer refrigerant from the refrigeration unit downstream of the refrigeration unit pump 402 to upstream of the refrigeration unit pump 402. Method 500 begins in block 502 with the determination, by the refrigeration unit controller 422 (for example, via the refrigeration unit power module 436, etc.), whether the main power source 132 is supplying power to the refrigeration unit controller 422. For example, the refrigeration unit controller 422 may monitor a current and / or voltage supplied by the main power source 132 and determine that the main power source 132 is not supplying power to the refrigeration unit controller 422 when the current and / or voltage falls below a threshold (for example, a minimum current, a minimum voltage, etc.). If the refrigeration unit controller 422 determines that the main power source 132 is supplying power to the refrigeration unit controller 422, method 500 restarts (for example, it terminates and continues to block 502 again, etc.). If the refrigeration unit 422 controller determines that the main power source 132 is not supplying power to the refrigeration unit 422 controller, method 500 continues in block 504 with the refrigeration unit 422 controller determining whether the refrigerant parameter measured by the refrigeration unit 424 sensor is within a range (e.g., 2%, 5%, 10%, etc.) of a target refrigerant parameter. For example, the refrigeration unit 422 controller might determine that the refrigerant pressure in the refrigeration unit is outside the target pressure range. If the refrigeration unit 422 controller determines that the refrigerant parameter is within the target refrigerant parameter range, method 500 restarts (e.g., it terminates and continues to block 502 again, etc.). If the controller of refrigeration unit 422 determines that the refrigerant parameter is not within the target refrigerant pressure range, method 500 continues in block 506 by repositioning the upstream control valve of transfer system 446 to couple the first line of refrigeration unit 404, upstream of the upstream control valve of transfer system 446, to transfer line 444. Method 500 then continues in block 508 by repositioning the downstream control valve of transfer system 447 to couple the second line of refrigeration unit 406, downstream of the downstream control valve of transfer system 447, to transfer line 444.As a result, the refrigerant of the refrigeration unit tn« Lzn / cznz / q / υιλι is supplied upstream of the refrigeration unit 402 pump around the refrigeration unit 402 pump and downstream of the refrigeration unit 402 pump, thereby diverting the refrigeration unit 402 pump. Method 500 continues in block 510 with the determination, by the refrigeration unit 422 controller (for example, via the refrigeration unit 436 power module, etc.), of whether the main power source 132 is supplying power to the refrigeration unit 422 controller. For example, the refrigeration unit 422 controller may monitor a current and / or voltage supplied by the main power source 132 and determine that the main power source 132 is supplying power to the refrigeration unit 422 controller when the current and / or voltage drop exceeds a threshold (for example, a minimum current, a minimum voltage, etc.). If the refrigeration unit 422 controller determines that the main power source 132 is not supplying power to the refrigeration unit 422 controller, method 500 continues back to block 510. If the refrigeration unit 422 controller determines that the main power source 132 is supplying power to the refrigeration unit 422 controller, method 500 continues in block 512 with repositioning the upstream control valve of the transfer system 446 to isolate the first duct of the refrigeration unit 404 from the transfer duct 444 (for example, to couple the first duct of the refrigeration unit 404 upstream of the upstream control valve of the transfer system 446 to the first duct of the refrigeration unit 404 downstream of the upstream control valve of the transfer system 446).Method 500 then continues in block 514 with the repositioning of the downstream control valve of transfer system 447 to isolate the second duct of refrigeration unit 406 from the transfer duct 444 (e.g., to couple the second duct of refrigeration unit 406 upstream of the downstream control valve of transfer system 447 to the second duct of refrigeration unit 406 downstream of the downstream control valve of transfer system 447). Method 500 then restarts (e.g., it ends and continues in block 502 again, etc.). X,Second example of transfer system operation As shown in Figure 6, a method 600 of utilizing the transfer system 442 to transfer refrigerant from the refrigeration unit upstream of the refrigeration unit pump 402 to downstream of the refrigeration unit pump 402. tn« Lzn / cznz / q / υιλι Method 600 begins in block 602 with the determination, by the controller of refrigeration unit 422 (for example, via the sensor module of refrigeration unit 434, etc.), of a superheat of the refrigerant in the first duct of refrigeration unit 404. For example, the controller of refrigeration unit 422 can use the refrigerant parameter measured by the sensor of refrigeration unit 424 to determine the superheat. Method 600 continues in block 604 with the determination, by the refrigeration unit 422 controller, of whether the superheat is within a range (e.g., 2%, 5%, 10%, etc.) of a target superheat. If the refrigeration unit 422 controller determines that the superheat is within the target superheat range, method 600 is restarted (e.g., it ends and continues in block 602 again, etc.). If the controller of refrigeration unit 422 determines that the superheat is not within the target superheat range, method 600 continues in block 606 by repositioning the upstream control valve of transfer system 446 to couple the first duct of refrigeration unit 404, downstream of the upstream control valve of transfer system 446, to transfer duct 444. Method 600 then continues in block 608 by repositioning the downstream control valve of transfer system 447 to couple the second duct of refrigeration unit 406, upstream of the downstream control valve of transfer system 447, to transfer duct 444.As a result, the refrigerant for the refrigeration unit is supplied downstream of the refrigeration unit pump 402 around the refrigeration unit pump 402 and upstream of the refrigeration unit pump 402, thereby diverting the upstream receiver 408, the condenser 412, the downstream receiver 416, and the evaporator 420. Method 600 continues in block 610 with the determination, by the refrigeration unit 422 controller (for example, via the refrigeration unit 436 power module, etc.), whether the superheat is within the target superheat range. If the refrigeration unit 422 controller determines that the superheat is not within the target superheat range, method 600 continues back to block 610. If the controller of refrigeration unit 422 determines that the superheat is within the target superheat range, method 600 continues in block 612 with the repositioning of the control valve upstream of the transfer system 446 to isolate the first duct of refrigeration unit 404 from the transfer duct 444 (e.g., to couple the first duct of refrigeration unit 404 upstream of the control valve upstream of the transfer system 446 to the first duct of refrigeration unit 404 downstream of the control valve upstream of the transfer system 446).Method 600 then continues in block 614 with the repositioning of the downstream control valve of transfer system 447 to isolate the second conduit of refrigeration unit 406 from the transfer conduit 444 (e.g., to couple the second conduit of refrigeration unit 406 upstream of the downstream control valve of transfer system 447 to the second conduit of refrigeration unit 406 downstream of the downstream control valve of transfer system 447). Method 600 then restarts (e.g., it ends and continues in block 602 again, etc.). XI. Example of expansion system operation As shown in Figure 7, a method 700 of utilizing the expansion system 450 to transfer refrigerant from the upstream refrigeration unit pump 402 to the expansion tank 468. Method 700 begins in block 702 with the determination, by the refrigeration unit 422 controller (e.g., via the refrigeration unit 436 power module, etc.), whether the main power source 132 is supplying power to the refrigeration unit 422 controller. For example, the refrigeration unit 422 controller may monitor a current and / or voltage supplied by the main power source 132 and determine that the main power source 132 is not supplying power to the refrigeration unit 422 controller when the current and / or voltage falls below a threshold (e.g., a minimum current, a minimum voltage, etc.). If the refrigeration unit 422 controller determines that the main power source 132 is supplying power to the refrigeration unit 422 controller, method 700 restarts (e.g., it terminates and continues to block 702 again, etc.). If the refrigeration unit 422 controller determines that the main power source 132 is not supplying power to the refrigeration unit 422 controller, method 700 continues in block 704 with the refrigeration unit 422 controller determining whether the refrigerant parameter measured by the refrigeration unit 424 sensor is within a range (e.g., 2%, 5%, 10%, etc.) of a target refrigerant parameter. For example, the refrigeration unit 422 controller might determine that the refrigerant pressure in the refrigeration unit is outside the target pressure range. If the refrigeration unit 422 controller determines that the refrigerant parameter is within the target refrigerant parameter range, method 700 restarts (e.g., it ends and continues to block 702 again, etc.). If the refrigeration unit 422 controller determines that the refrigerant parameter is not within the target refrigerant pressure range, method 700 continues in block 706 by repositioning the control valve downstream of the expansion system 464 to connect the second line from refrigeration unit 406 to the expansion tank 468 (for example, via the second line from expansion system 454 and the third line from expansion system 456). As a result, refrigerant from the refrigeration unit is supplied downstream from the pump of refrigeration unit 402 to the expansion tank 468. Method 700 continues in block 708 with the determination, by the refrigeration unit 422 controller (for example, via the refrigeration unit 436 power module, etc.), of whether the main power source 132 is supplying power to the refrigeration unit 422 controller. For example, the refrigeration unit 422 controller may monitor a current and / or voltage supplied by the main power source 132 and determine that the main power source 132 is supplying power to the refrigeration unit 422 controller when the current and / or voltage drop exceeds a threshold (for example, a minimum current, a minimum voltage, etc.). If the refrigeration unit 422 controller determines that the main power source 132 is not supplying power to the refrigeration unit 422 controller, method 700 continues back to block 708. If the refrigeration unit 422 controller determines that the main power source 132 is supplying power to the refrigeration unit 422 controller, method 700 continues in block 710 with the repositioning of the downstream control valve of the expansion system 464 to isolate the second duct of the refrigeration unit 406 from the expansion tank 468. Method 700 then restarts (e.g., ends and continues in block 702 again, etc.). XIL· Example of cooling system operation As shown in Figure 8, one method 800 of utilizing the cooling system 472 to transfer refrigerant from the upstream cooling unit pump of the cooling unit 402 to the cooling tank 480. Method 800 begins in block 802 with the determination, by the refrigeration unit controller 422 (for example, via the refrigeration unit power module 436, etc.), whether the main power source 132 is supplying power to the refrigeration unit controller 422. For example, the refrigeration unit controller 422 can monitor a current and / or voltage supplied by the main power source 132 and determine that the main power source 132 is not supplying power to the refrigeration unit controller 422 when the current and / or voltage falls below a threshold (for example, a minimum current, a minimum voltage, etc.).If the refrigeration unit controller 422 determines that the main power source 132 is providing power to the refrigeration unit controller 422, method 800 is restarted (e.g., it terminates and continues to block 802 again, etc.). If the refrigeration unit 422 controller determines that the main power source 132 is not supplying power to the refrigeration unit 422 controller, method 800 continues in block 804 with the refrigeration unit 422 controller determining whether the refrigerant parameter measured by the refrigeration unit 424 sensor is within a range (e.g., 2%, 5%, 10%, etc.) of a target refrigerant parameter. For example, the refrigeration unit 422 controller might determine that the refrigerant pressure in the refrigeration unit is outside the target pressure range. If the refrigeration unit 422 controller determines that the refrigerant parameter is within the target refrigerant parameter range, method 800 restarts (e.g., it terminates and continues to block 802 again, etc.). If the refrigeration unit 422 controller determines that the refrigerant parameter is not within the target refrigerant pressure range, method 800 continues in block 806 by repositioning the cooling system control valve 478 to connect the second refrigeration unit 406 line to the cooling tank 480 (for example, via the first cooling system 474 line). As a result, the refrigerant from the refrigeration unit is supplied downstream from the refrigeration unit 402 pump to the cooling tank 480. Method 800 continues in block 808 with the determination, by the refrigeration unit 422 controller (for example, via the refrigeration unit 436 power module, etc.), of whether the main power source 132 is supplying power to the refrigeration unit 422 controller. For example, the refrigeration unit 422 controller may monitor a current and / or voltage supplied by the main power source 132 and determine that the main power source 132 is supplying power to the refrigeration unit 422 controller when the current and / or voltage drop exceeds a threshold (for example, a minimum current, a minimum voltage, etc.). If the refrigeration unit 422 controller determines that the main power source 132 is not supplying power to the refrigeration unit 422 controller, method 800 continues back to block 808. If the refrigeration unit 422 controller determines that the main power source 132 is supplying power to the refrigeration unit 422 controller, the method tn« Lzn / cznz / q / υιλι 800 continues in block 810 with the repositioning of the cooling system control valve 478 to isolate the second duct of the refrigeration unit 406 from the cooling tank 480. Method 800 then restarts (e.g., it ends and continues in block 802 again, etc.). XIII. Construction of the example modalities Although this specification contains many implementation-specific details, these should not be considered limitations on the scope of what can be claimed, but rather descriptions of features specific to particular implementations. Certain features described in this specification in the context of separate implementations can also be implemented in combination within a single implementation. Conversely, several aspects described in the context of a single implementation can also be implemented in multiple separate implementations or in any suitable subcombination.Furthermore, although features can be described as acting in certain combinations and are even initially claimed as such, one or more features of a claimed combination may, in some cases, be removed from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. As used herein, the term "generally" and similar terms are intended to have a broad meaning in harmony with the common usage accepted by those of ordinary experience in the art to which the subject matter of this disclosure pertains. Those skilled in the art who review this disclosure should understand that these terms are intended to permit a description of certain described and claimed characteristics without restricting the scope of these characteristics to the precise numerical scales provided. Accordingly, these terms should be interpreted as indicating that non-substantial or non-consequential modifications or alterations to the described and claimed subject matter are considered to be within the scope of the appended claims. The term "coupled" and the like, as used herein, means the joining of two components directly or indirectly to one another. Such joining may be stationary (e.g., permanent) or movable (e.g., removable or detachable). Such joining may be achieved with the two components, or the two components and any additional intermediate components, being integrally formed as a single unitary body with one another, or with the two components, or with the two components and any additional intermediate components, being joined together. The terms fluid communication with and similar, as used herein, mean two components or objects having a path formed between them through which a fluid, such as air, liquid refrigerant, gaseous refrigerant, mixed-phase refrigerant, etc., can flow, with or without intermediate components or objects. Examples of configurations to enable fluid communication may include piping, channels, or any other components suitable for enabling the flow of a fluid from one component or object to another. It is important to note that the construction and arrangement of the system shown in the various example implementations is for illustrative purposes only and is not restrictive. All changes and modifications that fall within the spirit and / or scope of the described implementations are protected. It should be noted that some features may not be necessary, and that implementations lacking certain features may be considered within the scope of the application. The scope is defined by the following claims. When the phrase "a portion" is used, the article may include a portion and / or the entire article unless specifically stated otherwise. Also, the term "or" is used in its inclusive (and not its extended) sense, so that when used, for example, to connect a list of items, the term "or" means one, some, or all of the items in the list. Conjunctive language such as the phrase "at least one of X, Y, and Z," unless specifically stated otherwise, is understood from context as generally used to imply that an item, term, etc., can be any of X, Y, Z, X and Y, X and Z, Y and Z, or X, Y, and Z (i.e., any combination of X, Y, and Z). Thus, conjunctive language generally does not intend to imply that certain modalities require at least one of X, at least one of Y, and at least one of Z to be present each, unless otherwise stated. Additionally, the use of value ranges (e.g., W to P, etc.) herein includes both maximum and minimum values ​​(e.g., W to P includes W and includes P, etc.), unless otherwise stated. Furthermore, a value range (e.g., W to P, etc.) does not necessarily require the inclusion of intermediate values ​​within the range (e.g., W to P may include only W and P, etc.), unless otherwise stated.

Claims

1. A refrigeration system comprising: a distribution system configured to circulate a refrigerant from the distribution system, the distribution system comprising: a distribution system pump; a main chiller configured to receive the distribution system refrigerant from the distribution system pump; a distribution system inlet duct configured to receive the distribution system refrigerant from the main chiller; and a distribution system outlet duct configured to receive the distribution system refrigerant from the distribution system inlet duct and to supply the distribution system refrigerant to the distribution system pump; and a refrigeration unit configured to circulate a refrigerant from the refrigeration unit, the refrigeration unit comprising: a refrigeration unit pump;an upstream receiver configured to receive refrigerant from the refrigeration unit's pump; a condenser configured to receive refrigerant from the upstream receiver's refrigeration unit and comprising a heat exchange duct from the refrigeration unit that is configured to be coupled to the distribution system's inlet duct and the distribution system's outlet duct, receive refrigerant from the distribution system's inlet duct, and supply refrigerant from the distribution system to the distribution system's outlet duct; a downstream receiver configured to receive refrigerant from the condenser's refrigeration unit;and an evaporator configured to receive refrigerant from the downstream receiver refrigeration unit and to supply refrigerant from the refrigeration unit to the refrigeration unit pump.

2. The refrigeration system according to claim 1, further characterized in that the refrigeration unit additionally comprises: a distribution system control valve disposed between the refrigeration unit pump and the main chiller and configured to receive distribution system refrigerant from the refrigeration unit pump and to supply distribution system refrigerant to the main chiller; an auxiliary chiller configured to receive distribution system refrigerant from the distribution system control valve and to supply distribution system refrigerant to the distribution system inlet duct; wherein the distribution system control valve is operable between a first position and a second position;wherein, in the first position, the distribution system control valve engages the distribution system pump and the main cooler and isolates the distribution system pump and the auxiliary cooler; and wherein, in the second position, the distribution system control valve engages the distribution system pump and the auxiliary cooler and isolates the distribution system pump and the auxiliary cooler.

3. The cooling system according to claim 2, further characterized in that: the distribution system control valve is operable between the first position, the second position and a third position; wherein, in the third position, the distribution system control valve engages the distribution system pump and the main cooler and engages the distribution system pump and the auxiliary cooler.

4. The cooling system according to claim 2, further characterized in that it additionally comprises a distribution system controller that communicates with the distribution system control valve and is configured to receive power from a main power supply and to reposition the distribution system control valve from the first position to the second position in response to detecting that the main power supply is not providing power to the distribution system controller.

5. The cooling system according to claim 4, further characterized in that it additionally comprises an auxiliary power source that can communicate with the distribution system controller and is configured to provide power to the distribution system controller independently of the main power supply; wherein the distribution system controller is further configured to communicate with the auxiliary power source to provide power to the distribution system controller in response to detecting that the main power supply is not providing power to the distribution system controller.

6. The cooling system according to claim 5, further characterized in that the distribution system controller is additionally configured to reposition the distribution system control valve from the second position to the first position in response to detecting that the auxiliary power source is supplying power to the distribution system controller.

7. The cooling system according to claim 2, further characterized in that it additionally comprises: a sensor configured to determine a parameter; a distribution system controller that can communicate with the distribution system control valve and the sensor, the distribution system controller being configured to receive the parameter from the sensor, compare the parameter to a target parameter, and reposition the distribution system control valve from the first position to the second position in response to the determination that the parameter is not within a range of the target parameter. 8.The refrigeration system according to claim 7, further characterized in that: the parameter is a refrigerant parameter; and the refrigeration unit comprises a refrigeration unit low pressure relief valve (RPV) defined by a low pressure threshold; the target parameter is associated with the low pressure threshold.

9. The refrigeration system according to claim 2, further characterized in that: the refrigerant of the refrigeration unit is carbon dioxide; and the refrigerant of the distribution system is not the same as the refrigerant of the refrigeration unit.

10. A refrigeration unit configured to circulate a refrigerant from the refrigeration unit, the refrigeration unit comprising: an upstream transfer system control valve; a refrigeration unit pump configured to receive refrigerant from the refrigeration unit from the upstream transfer system control valve; a downstream transfer system control valve configured to receive refrigerant from the refrigeration unit from the refrigeration unit pump; a transfer system conduit configured to receive refrigerant from the refrigeration unit from the downstream transfer system control valve; an upstream receiver configured to receive refrigerant from the refrigeration unit from the downstream transfer system control valve;a condenser configured to receive refrigerant from the upstream receiver refrigeration unit; and an evaporator configured to receive refrigerant from the condenser refrigeration unit and to supply refrigerant from the refrigeration unit to the upstream control valve of the transfer system; wherein the transfer system duct is configured so that refrigerant from the refrigeration unit bypasses the upstream receiver, the condenser, and the evaporator as the refrigerant from the refrigeration unit passes through the transfer system duct between the upstream control valve of the transfer system and the downstream control valve of the transfer system.

11. The refrigeration unit according to claim 10, further characterized in that it additionally comprises a refrigeration unit controller that can communicate with the upstream control valve of the transfer system and the downstream control valve of the transfer system; wherein the upstream control valve of the transfer system is operable between a first position of the upstream control valve of the transfer system and a second position of the upstream control valve of the transfer system, the upstream control valve of the transfer system is configured to: isolate the transfer system conduit from the refrigeration unit pump in the first position of the upstream control valve of the transfer system;and couple the transfer system duct and the refrigeration unit pump in the second position of the upstream transfer system control valve; and where the downstream transfer system control valve is operable between a first position of the downstream transfer system control valve and a second position of the downstream transfer system control valve, the downstream transfer system control valve is configured to: isolate the transfer system duct from the evaporator in the first position of the downstream transfer system control valve; and couple the transfer system duct and the evaporator in the second position of the downstream transfer system control valve.

12. The refrigeration unit according to claim 11, further characterized in that it additionally comprises a sensor configured to obtain a refrigerant parameter from the refrigerant of the refrigeration unit; wherein the controller of the refrigeration unit is configured to: receive the refrigerant parameter from the sensor; compare the refrigerant parameter with a target refrigerant parameter; reposition the upstream control valve of the transfer system from the first upstream control valve position of the transfer system to the second upstream control valve position of the transfer system in response to detecting that the refrigerant parameter is not within a range of a target refrigerant parameter;and reposition the downstream control valve of the transfer system from the first downstream control valve position of the transfer system to the second downstream control valve position of the transfer system in response to detecting that the refrigerant parameter is not within the target refrigerant parameter range.

13. The refrigeration unit according to claim 12, further characterized in that it additionally comprises a refrigeration unit low pressure relief valve (RPV) configured to receive refrigerant from the evaporator refrigeration unit and to supply refrigerant from the refrigeration unit to the refrigeration unit pump, the refrigeration unit low PRV being defined by a low pressure threshold; wherein the target refrigerant parameter is a pressure that is less than the low pressure threshold.

14. The refrigeration unit according to claim 11, further characterized in that it additionally comprises: a sensor configured to obtain a refrigerant parameter from the refrigerant of the refrigeration unit; an expansion tank;an upstream expansion system control valve configured to receive refrigerant from the refrigeration unit from the refrigeration unit pump and supply refrigerant from the refrigeration unit to the expansion tank, the upstream expansion system control valve is operable between a first upstream expansion system control valve position and a second upstream expansion system control valve position, the upstream expansion system control valve isolates the expansion tank from the upstream receiver in the first upstream expansion system control valve position and couples the expansion tank and the upstream receiver in the second upstream expansion system control valve position;and a refrigeration unit controller can communicate with the upstream expansion system control valve and the sensor, the refrigeration unit controller is configured to: receive the refrigerant parameter from the sensor; compare the refrigerant parameter with a target refrigerant parameter; and reposition the upstream expansion system control valve from the first upstream expansion system control valve position to the second upstream expansion system control valve position in response to detecting that the refrigerant parameter is not within a range of a target refrigerant parameter.

15. The refrigeration unit according to claim 11, further characterized in that it additionally comprises: a cooling tank configured to be cooled by the evaporator; a cooling system control valve configured to receive refrigerant from the refrigeration unit pump and to supply the cooling tank with refrigerant from the refrigeration unit.

16. The refrigeration unit according to claim 15, further characterized in that it additionally comprises: a sensor configured to obtain a refrigerant parameter from the refrigerant of the refrigeration unit; a controller of the refrigeration unit that can communicate with the upstream control valve of the transfer system, the downstream control valve of the transfer system, the control valve of the cooling system, and the sensor, the controller of the refrigeration unit being configured to: receive the refrigerant parameter from the sensor; compare the refrigerant parameter with a target refrigerant parameter;Use the upstream transfer system control valve and the downstream transfer system control valve to cause the refrigerant from the refrigeration unit to bypass the upstream receiver, condenser, and evaporator, in response to the refrigerant parameter not being within a range of the target refrigerant parameter; and use the cooling system control valve to cause the refrigerant from the refrigeration unit to bypass the upstream receiver, condenser, and evaporator, in response to the refrigerant parameter not being within a range of the target refrigerant parameter.

17. A refrigeration unit configured to circulate a refrigerant from the refrigeration unit, the refrigeration unit comprising: an upstream control valve of the expansion system; a refrigeration unit pump configured to receive refrigerant from the refrigeration unit from the upstream control valve of the expansion system; a downstream control valve of the expansion system configured to receive refrigerant from the refrigeration unit from the refrigeration unit pump; an expansion tank coupled to the upstream control valve of the expansion system and the downstream control valve of the expansion system; a condenser configured to receive refrigerant from the refrigeration unit from the refrigeration unit pump;an evaporator configured to receive refrigerant from the condenser refrigeration unit and to supply refrigerant from the refrigeration unit to the upstream control valve of the expansion system; and a refrigeration unit controller configured to reposition the downstream control valve of the expansion system to facilitate routing refrigerant from the downstream control valve of the expansion system to the expansion tank while bypassing the condenser and evaporator.

18. The refrigeration unit according to claim 17, further characterized in that it additionally comprises a control valve upstream of the expansion system configured to receive refrigerant from the refrigeration unit from the expansion tank, supply refrigerant from the refrigeration unit to the refrigeration unit pump, and supply refrigerant from the refrigeration unit to a vent; wherein the refrigeration unit controller is configured to reposition the control valve downstream of the expansion system to couple the expansion tank and the vent while isolating the expansion tank from the refrigeration unit pump.

19. The refrigeration unit according to claim 17, further characterized in that it additionally comprises: an upstream receiver configured to receive refrigerant from the refrigeration unit pump and to supply refrigerant from the refrigeration unit to the condenser; and a downstream receiver configured to receive refrigerant from the refrigeration unit from the condenser and to supply refrigerant from the refrigeration unit to the evaporator; and a refrigeration unit low pressure relief valve (RPV) configured to receive refrigerant from the refrigeration unit from the evaporator and to supply refrigerant from the refrigeration unit to the refrigeration unit pump.

20. The refrigeration unit according to claim 19, further characterized in that it additionally comprises: an upstream control valve of the transfer system configured to receive refrigerant from the evaporator refrigeration unit; a downstream control valve of the transfer system configured to supply refrigerant from the refrigeration unit to the upstream receiver; and a conduit of the transfer system coupled to the upstream control valve of the transfer system and the downstream control valve of the transfer system and configured to facilitate the diversion of the upstream receiver, the condenser, the downstream receiver and the evaporator.

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