Continuous feed liquid coolant replacement

Abstract

The present disclosure relates to continuous feed liquid coolant replacement. The present disclosure relates to methods, systems, and apparatuses for replacing liquid coolant in a cooling distribution unit during operation of the cooling distribution unit. While the coolant distribution unit is in operation and providing cooling to an electronic system, the active liquid coolant to be replaced is removed from the flow loop of the cooling distribution unit. Further, while the coolant distribution unit is in operation and providing cooling to the electronic system, replacement liquid coolant is provided to the flow loop.

Description

Technical Field

[0001] This manual relates to liquid coolant systems, and more particularly to the replacement of continuously fed liquid coolants. Background Technology

[0002] Liquid cooling systems are commonly used to cool electronic equipment, and are frequently found in data centers. A typical liquid cooling system includes a coolant distribution unit (CDU) that supplies cooling coolant to various heat exchangers in the equipment being cooled, and receives heated coolant after it has been heated by the heat exchangers. The heated coolant is then cooled through a cooling process, and the cooled coolant is then recirculated. Typically, the liquid coolant flows in a closed-loop path known as the flow circulation.

[0003] A variety of liquids can be used as liquid coolants. These liquids include water, water / glycol mixtures, and other liquids. The type of liquid used may depend on the specifications of the system to be cooled, the type of cooling system used, etc.

[0004] Regardless of the type of liquid used, each of these cooling systems requires maintenance of the liquid coolant. Over time, the coolant will become contaminated with one or more oxides, scale and corrosion particles, biological agents, etc. As contaminants accumulate, the quality of the coolant deteriorates. This leads to increased corrosion of the cooling system (pipes, cold plates, etc.) and reduced cooling efficiency.

[0005] To maintain coolant levels, the cooling system is periodically shut down when the coolant is replaced. Since the electronic equipment being cooled will overheat without proper cooling, it is also shut down during coolant replacement. This results in wasted computing resources and customer downtime. Summary of the Invention

[0006] This specification describes a technique related to a continuously fed liquid coolant replacement system that replaces the liquid coolant while the cooling system is operating. Generally, an innovative aspect of the subject matter described herein can be embodied in the liquid coolant replacement system, comprising: a first reservoir for storing the replacement liquid coolant, which is a liquid coolant, i.e., replacing the active liquid coolant in the coolant distribution unit of the coolant system; a liquid coupling subsystem that supplies the replacement liquid coolant to the flow circulation of the active liquid coolant in the coolant distribution unit and receives the active liquid coolant from the flow circulation of the coolant distribution unit; and a control system coupled to the liquid coupling subsystem that generates control signals for the liquid coupling subsystem for the replacement operation, such that the liquid coupling subsystem: while the coolant distribution unit is operating and providing cooling to the electronic system, receives the active liquid coolant removed from the flow circulation from the coolant distribution unit, and while the coolant distribution unit is operating and providing cooling to the electronic system, supplies the replacement liquid coolant from the first reservoir to the flow circulation. Other embodiments of this aspect include corresponding methods, apparatus, and computer programs configured to perform the actions of the methods and encoded on a computer storage device.

[0007] Specific embodiments of the subject matter described in this specification can be implemented to achieve one or more of the following advantages. Periodic downtime is reduced or even eliminated because the liquid coolant is replaced during cooling system operation. This results in increased utilization of computer resources. Furthermore, automation of coolant maintenance and replacement reduces the support time required by system maintenance personnel, thereby lowering overall operating costs. Because the coolant is maintained at a minimum quality level, the likelihood of system degradation (corrosion, loss of cooling capacity, etc.) is lower compared to situations requiring human-machine interaction, which may involve scheduling that cannot consistently ensure the coolant quality is maintained at at least a minimum level. Furthermore, reduced human-machine interaction also reduces spills, metering errors, and improper timing of coolant replacement. Additionally, the system can monitor the quality and contamination of its own supplied replacement coolant, thereby reducing the possibility of introducing contaminated coolant into the cooling system. Attached Figure Description

[0008] Details of one or more embodiments of the subject matter described in this specification are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages of the subject matter will become apparent from the description, drawings, and claims.

[0009] Figure 1 This is a block diagram of a liquid coolant replacement system.

[0010] Figure 2 yes Figure 1 A block diagram of a modified liquid coolant replacement system.

[0011] Figure 3 Is using Figure 1 or Figure 2 A flowchart of an example process for replacing the liquid coolant in any of the systems.

[0012] Figure 4 This is a flowchart of an example process that triggers a replacement operation.

[0013] Figure 5 This is a flowchart of an example process for metering a liquid coolant containing chemical reagents.

[0014] Figure 6 This is a flowchart of an example process for monitoring coolant quality levels during a replacement operation.

[0015] The same reference numerals and names denote the same elements in each figure. Detailed Implementation

[0016] Figure 1 This is a block diagram of a liquid coolant replacement system 100. System 100 includes a reservoir 102 that stores replacement liquid coolant. The replacement liquid coolant is a coolant used in the coolant distribution unit 150 of the coolant replacement system. During the replacement operation, the liquid coolant being replaced, referred to as "active liquid coolant" or "active coolant," is received and stored in another reservoir 104. The coolant supplied to the coolant distribution unit 150 is referred to as "replacement liquid coolant" or "replacement coolant." The replacement coolant is supplied to the coolant distribution unit 150 while the coolant distribution unit 150 is operable and provides cooling to electronic systems such as servers 190 and 192.

[0017] exist Figure 1 In system 100, replacement coolant is supplied to coolant distribution unit 150 while active coolant is being removed from coolant distribution unit 150, and coolant distribution unit 150 remains operable. A liquid coupling subsystem, including pumps 112 and 118 and valves 116 and 122, is used to deliver replacement liquid coolant to the flow cycle of active liquid coolant in coolant distribution unit 150, and also to remove active liquid coolant from the flow cycle of coolant distribution unit 150. Specifically, a first physical flow path 114 receives active liquid coolant from the flow cycle via valve 116 and pump 112, and a second physical flow path 120 supplies replacement liquid coolant from first reservoir 102 to the flow cycle via pump 118 and valve 122. As shown, flow path 114 exits coolant distribution unit 150 at a separate location from flow path 120 entering coolant distribution unit 150, which allows for the simultaneous extraction of active coolant and addition of replacement coolant.

[0018] Controller 110 is a control system that generates control signals that operate valves 116 and 122, as well as pumps 112 and 118, so that during a replacement operation, a first physical flow path 114 receives active liquid coolant, and a second physical flow path 120 simultaneously provides replacement liquid coolant at substantially equal flow rates.

[0019] The coolant distribution unit 150 may be part of a larger cooling system. The coolant distribution unit 150 includes a control system 152, whose operating unit 150. Active coolant circulates in a flow loop, as indicated by the dashed return arrow in pipe 156 and the supply arrow in pipe 158. Pipe 156 returns heated active coolant, and pipe 158 supplies cooled active coolant. Heat exchangers 170 and 172 circulate active coolant in servers 190 and 192 to provide cooling to servers 190 and 192.

[0020] Cooler 160 cools the active coolant, and optionally reservoir 154 stores a reserve of the active coolant. The cooler may be part of a larger cooling system, not shown.

[0021] System 100 may include sensor 108, or alternatively, may receive data from sensor 159 in coolant dispensing unit 150. Sensor 108 or 159 may be a coolant mass sensor subsystem with a single sensor that senses a specific mass characteristic, or it may be a subsystem with multiple sensors, each sensing a specific mass characteristic. Sensor 108 or 159 generates data indicating the mass of the active liquid coolant. Exemplary sensors include optical sensors (e.g., turbidity sensors), pH level sensors, biosensors, conductivity sensors, particulate sensors, or any other suitable sensors for sensing specific properties of the liquid coolant to determine coolant mass based on the coolant's optical properties.

[0022] Another sensor 109 can also be used to monitor the quality of the replacement coolant in the reservoir 102. This is to ensure that the replacement coolant is not contaminated or unsuitable for use in the replacement operation. If the controller 110 determines from the sensor 109 that the replacement coolant is below a threshold quality level, the system 100 will notify the administrator that coolant service is required.

[0023] During the replacement operation, controller 110 operates valves 116 and 122, as well as pumps 112 and 118, to replace the active coolant with replacement coolant. The replacement operation can be performed periodically, such as weekly, and during the operation, only a portion of the active coolant is replaced with replacement coolant. In some implementations, this portion may be a predetermined amount of liquid coolant less than the amount of active liquid coolant in coolant distribution unit 150 prior to the replacement operation. For example, if there are 100 liters of active liquid coolant in the flow cycle, a periodic replacement operation might replace 10 liters of active liquid coolant with replacement liquid coolant.

[0024] In other implementations, the replacement operation can be triggered based on the determination of the quality level of the active liquid coolant. For example, if the controller determines from sensor data that the quality level is below a first threshold quality level, such as a minimum threshold, then the replacement operation is initiated and a predetermined amount of active liquid coolant is replaced with replacement liquid coolant.

[0025] In a variation of this implementation, during the replacement operation, coolant quality sensor 108 or 159 periodically determines the refresh quality level of the active liquid coolant and generates data indicating the refresh quality of the active liquid coolant. Controller 110 receives the determined refresh quality data indicating the active liquid coolant from coolant quality sensor 108 or 159. When the determined refresh quality of the active liquid coolant exceeds a first threshold quality level, controller 110 stops the replacement operation. In some implementations, the quality level of the active liquid coolant must exceed a second threshold quality level, which is greater than the first threshold quality level, before the replacement operation stops. This ensures that the active liquid coolant in the flow cycle is refreshed to a level some threshold amount above the minimum quality level. For example, suppose the turbidity quality metric is rated from 0 to 1, where 0 represents complete opacity and 1 represents clear. The first threshold quality level might be 0.9, and the second threshold quality level might be 0.96. Therefore, the replacement operation will stop when sufficient replacement liquid coolant has been added to the flow cycle and a corresponding amount of active liquid coolant has been removed, resulting in a turbidity level of 0.96 or higher.

[0026] In some implementations, system 100 may include a reservoir storing chemical reagents that are added to the replacement liquid coolant supplied to the flow circulation during the replacement operation. While only one reservoir is shown, multiple reservoirs may be present, each containing a specific reagent, each reagent performing a particular remediation. The amount of reagent added may be based on the mass level of the active liquid coolant. For example, a bactericide may be added when bacteria or fungi are detected; a neutralizing agent may be added to restore the pH to a certain range; and so on. The amount of each chemical reagent to be added can be programmed into controller 110 and based on the detected level of the characteristic the reagent is intended to mitigate. Therefore, controller 110 can regulate both the amount of active liquid coolant replaced and the amount of chemical reagent added. In other implementations, a fixed amount of reagent may be added.

[0027] In some implementations, the coolant replacement flow rate can also be adjusted based on the amount of coolant to be replaced and / or based on a detected quality level. In some implementations, controller 110 will increase the flow rate for more coolant to be replaced. This is done to reduce replacement operation time, especially when system 100 is a mobile system that can be used to service multiple closed-loop cooling systems during a workday.

[0028] In another implementation, system 100 can be configured to replace all the coolant in the flow cycle of coolant distribution unit 150. This can be done, for example, when it is determined that the active coolant is severely contaminated and it is best to replace the entire coolant, or as part of a periodic maintenance schedule, such as every six months. To achieve this, controller 110 is configured to generate another set of control signals to operate pumps and valves to complete the replacement of the active liquid coolant with replacement liquid coolant.

[0029] Figure 1 System 100 has two independent physical paths for coolant exchange, allowing for simultaneous addition and removal of coolant. In another implementation, for example... Figure 2As shown, system 100 may have a flow path portion, i.e., a single physical flow path. For example, controller 110 may accordingly operate three-way valve 216 and pumps 112 and 118 so that the flow path can selectively receive active liquid coolant from the flow cycle during a first selection period, as indicated by arrow 214, and selectively supply replacement liquid coolant to the flow cycle during a second selection period, as indicated by arrow 220. Controller 110 generates a control signal that causes the single physical flow path to selectively receive active liquid coolant during the first time period and selectively supply replacement liquid coolant during the second time period. Typically, a certain volume of active liquid coolant is removed, and then an equal volume of replacement liquid coolant is added. This can be done incrementally; for example, X liters can be removed and then X liters added until a predetermined amount of replacement coolant has been added.

[0030] System 100 can be integrated into a larger cooling system; for example, system 100 can be a component or subsystem within cooling distribution unit 150. In other implementations, system 100 can be a standalone device that can be temporarily attached to cooling distribution unit 150. Furthermore, although system 100 is described as communicating with cooling distribution unit, it can be attached to any part of the piping in the flow circulation and does not need to be connected to cooling distribution unit.

[0031] Figure 3 Is using Figure 1 or Figure 2 A flowchart illustrating an example process for replacing the liquid coolant in any of the systems. This process can be... Figure 1 or Figure 2 The system is implemented by controller 110.

[0032] Process 300 determines that a replacement operation signal exists (302). As described above, the replacement operation signal may be generated in response to the expiration of a time period, such as a replacement operation every two weeks; a low coolant level signal; or in response to a quality characteristic indicating a problem with the liquid coolant.

[0033] Process 300 generates a control signal to initiate the replacement operation (304). As described above, the control signal operates the pump and valve to remove the active coolant from the flow cycle and add replacement coolant to the flow cycle. Specifically, during the replacement operation, system 100 receives active liquid coolant from the flow cycle (306) while the coolant distribution unit is operating and providing cooling to the electronic system, and provides replacement liquid coolant to the flow cycle (308) while the coolant distribution unit is operating and providing cooling to the electronic system. The addition and replacement of coolant can occur simultaneously, as described in reference... Figure 1 The aforementioned can also occur independently, as described in the reference. Figure 2 As stated above.

[0034] Figure 4 This is a flowchart of an example process for triggering a replacement operation. This process can be... Figure 1 or Figure 2 The system is implemented by controller 110.

[0035] Process 400 determines whether the quality level of the active liquid coolant is below a quality level threshold (402). As mentioned above, the quality level can be based on turbidity measurements, pH measurements, biological measurements, mineral measurements, or other measurements that indicate coolant quality. Multiple measurements may also be considered.

[0036] If process 400 determines that the mass level of the active liquid coolant is below a mass level threshold, process 400 performs a replacement operation (404). The replacement operation can be as described above.

[0037] If process 400 does not determine whether the quality level of the active liquid coolant is below a quality level threshold, then process 400 determines whether a replacement cycle is due (406). For example, a maintenance operation performed every two weeks may include replacing a portion of the liquid coolant.

[0038] If process 400 determines that the replacement cycle has expired, process 400 performs a replacement operation (404). The replacement operation can be as described above.

[0039] If process 400 does not determine that the replacement cycle has expired, process 400 determines whether the active coolant is low (408). If process 400 determines that the active coolant is low, process 400 performs a replacement operation (410). Replacement operation 410 may involve only replenishing the coolant rather than replacing a portion of the active coolant.

[0040] After changing operation 410 or 404, or if process 400 does not determine that the active coolant is low, process 400 returns to 402.

[0041] Figure 5 This is a flowchart of an example process for metering a liquid coolant containing chemical reagents. This process can be performed... Figure 1 or Figure 2 The system is implemented by controller 110.

[0042] Process 500 determines the chemical reagent dosage based on the coolant quality level (502). As mentioned above, the amount of reagent can be fixed, for example, X mL per 10 liters of liquid coolant. Alternatively, the amount of reagent can depend on the detected quality level, for example, adding a corresponding amount of reagent for each range of various quality grades. Generally, the worse the indicated quality level, the larger the amount of reagent required. These amounts can be specified, for example, in a lookup table in the memory of controller 110, or as a result of a metering function performed by controller 110, which receives the quality level and the amount of coolant as input and calculates the required amount of reagent.

[0043] Multiple reagents can be added. For example, bactericides and pH balancers can be added depending on the detected quality level.

[0044] Process 500 adds a dose of chemical reagent to the replacement liquid coolant supplied to the flow circulation (504). In some implementations, process 500 may then stop the replacement operation (510), as shown by the dashed streamline. In another implementation, process 500 may monitor the active liquid coolant, for example, via sensor 159, to determine whether the quality level is at or above a target quality level (506). For example, after a period of time following the addition of the reagent, such as one hour, process 500 may determine how the reagent affects the quality level by updating the detected quality level through the sensor subsystem.

[0045] If process 500 determines that the quality level is not at or above the target quality level, process 500 adds additional chemical reagents and returns to 506 (508). The amount of reagent can be less than the initially added amount, or it can be the same amount, or it can be based on other functions.

[0046] If process 500 determines that the quality level is at or above the target quality level, process 500 stops the replacement operation (510). Otherwise, process 500 may add additional reagents again.

[0047] Figure 6 This is a flowchart of an example process for monitoring coolant quality levels during a replacement operation. This process can be... Figure 1 or Figure 2 The system is implemented by controller 110.

[0048] Process 600 determines the quality level of the replacement operation (602). The quality level can be determined as described above with reference to step 502.

[0049] The process 600 removes the active liquid coolant and replaces it with a replacement liquid coolant while monitoring the quality level (604). Here, the quality level is improved by adding replacement liquid coolant.

[0050] Process 600 determines whether the quality level is at or above the target quality level (606). If process 600 determines that the quality level is not at or above the target quality level, process 600 returns to 604 and removes more active liquid coolant and adds additional replacement liquid coolant.

[0051] If process 600 determines that the quality level is at or above the target quality level, process 500 stops the change operation (608).

[0052] The embodiments of the control circuitry and operation described in this specification can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or combinations thereof. Embodiments of the subject matter described in this specification can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions encoded on a computer storage medium for execution by or control of its operation by a data processing device. Alternatively or additionally, the program instructions may be encoded on artificially generated propagated signals, such as machine-generated electrical, optical, or electromagnetic signals, which are generated as encoded information to be transmitted to a suitable receiver device for execution by the data processing device. The computer storage medium may be or is included in a computer-readable storage device, a computer-readable storage substrate, a random or serial access memory array or device, or a combination thereof. Furthermore, although the computer storage medium is not a propagated signal, it may be a source or destination of computer program instructions encoded in artificially generated propagated signals. The computer storage medium may also be or be included in one or more separate physical components or media (e.g., multiple CDs, disks, or other storage devices).

[0053] The term "data processing apparatus" includes various means, devices, and machines for processing data, including, for example, programmable processors, computers, systems-on-a-chip, or a combination thereof. The apparatus may include special-purpose logic circuitry, such as FPGAs (Field-Programmable Gate Arrays) or ASICs (Application-Specific Integrated Circuits). In addition to hardware, the apparatus may also include code that creates an execution environment for the computer program in question, such as code constituting processor firmware, protocol stacks, database management systems, operating systems, cross-platform operating environments, virtual machines, or combinations thereof. The apparatus and execution environment can implement various different computing model infrastructures, such as web services, distributed computing, and grid computing infrastructures.

[0054] Computer programs (also known as programs, software, software applications, scripts, or code) can be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and can be deployed in any form, including as standalone programs or as modules, components, subroutines, objects, or other units suitable for use in a computing environment. A computer program may (but does not need to) correspond to a file in a file system. A program may be stored as part of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to a related program, or in multiple coordinating files (e.g., a file storing one or more modules, subroutines, or portions of code). A computer program can be deployed to execute on a single computer or on multiple computers located at a single site or distributed across multiple sites and interconnected by a communication network.

[0055] The processes and logic flows described in this specification can be executed by one or more programmable processors that execute one or more computer programs to perform actions by manipulating input data and generating outputs. The processes and logic flows can also be executed by dedicated logic circuitry, and the device can be implemented as dedicated logic circuitry, such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit).

[0056] Processors suitable for executing computer programs include, by way of example, both general-purpose and special-purpose microprocessors, as well as any one or more processors in any type of digital computer. Typically, a processor receives instructions and data from read-only memory or random access memory, or both. The basic components of a computer are the processor for performing operations according to instructions and one or more memory devices for storing instructions and data.

[0057] While this specification contains numerous specific implementation details, these details should not be construed as limiting the scope of any invention or what may be claimed, but rather as descriptions of specific features of a particular embodiment of a particular invention. Certain features described in this specification in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually in multiple embodiments, or in any suitable sub-combination. Furthermore, although features may be described above as functioning in certain combinations, or even initially claimed, in some cases one or more features from a claimed combination may be removed from the combination, and the claimed combination may refer to a sub-combination or a variation of a sub-combination.

[0058] Similarly, although operations are described in a specific order in the accompanying drawings, this should not be construed as requiring such operations to be performed in the specific order or sequence shown, or requiring all of the operations shown to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system components in the above embodiments should not be construed as requiring such separation in all embodiments; rather, it should be understood that the described program components and systems can generally be integrated into a single software product or packaged into multiple software products.

[0059] Therefore, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the following claims. In some cases, the actions referenced in the claims may be performed in a different order and the desired result may still be achieved. Furthermore, the processes described in the drawings do not necessarily require the specific order or sequence shown to achieve the desired result. In some implementations, multitasking and parallel processing may be advantageous.

Claims

1. A liquid coolant replacement system, comprising: A first reservoir is used to store replacement liquid coolant, which is the liquid coolant of the active liquid coolant in the coolant distribution unit of the coolant system to be replaced. A liquid coupling subsystem through which the replacement liquid coolant is supplied to the flow circulation of the active liquid coolant in the coolant distribution unit, and the active liquid coolant is received from the flow circulation of the coolant distribution unit via the liquid coupling subsystem; The control system is coupled to the liquid coupling subsystem and generates control signals for the liquid coupling subsystem for switching operations, such that the liquid coupling subsystem: While the coolant distribution unit is operating and providing cooling to the electronic system, it receives active liquid coolant that has been removed from the flow cycle. as well as While the coolant distribution unit is operating and providing cooling to the electronic system, replacement liquid coolant is supplied from the first reservoir to the flow circulation; A coolant mass sensor subsystem determines the mass level of the active liquid coolant and generates data indicating the determined mass of the active liquid coolant. as well as The control system receives data from the coolant mass sensor subsystem indicating the determined mass of the active liquid coolant; and When the determined mass of the active liquid coolant falls below a first threshold mass level, the control system initiates the replacement operation; and During the replacement operation: The coolant quality sensor subsystem periodically determines the updated quality level of the active liquid coolant and generates data indicating the determined updated quality of the active liquid coolant; and The control system receives data from the coolant quality sensor subsystem indicating the determined updated quality of the active liquid coolant; and When the determined replacement quality of the active liquid coolant exceeds the first threshold quality level, the control system stops the replacement operation.

2. The liquid coolant replacement system according to claim 1, wherein, During the replacement operation, the liquid coolant replacement system replaces a predetermined amount of active liquid coolant with replacement liquid coolant, wherein the predetermined amount of active liquid coolant is less than the amount of active liquid coolant in the coolant distribution unit before the replacement operation.

3. In the liquid coolant replacement system according to claim 1, when the determined replacement quality of the active liquid coolant exceeds a second threshold quality level greater than the first threshold quality level, the control system stops the replacement operation.

4. The liquid coolant replacement system according to claim 1, wherein, The coolant mass sensor subsystem includes an optical sensor that determines the coolant mass based on the optical properties of the active liquid coolant.

5. The liquid coolant replacement system according to claim 1, wherein, The coolant quality sensor subsystem includes a biosensor that determines the coolant quality based on the biological characteristics of the active liquid coolant.

6. The liquid coolant replacement system according to claim 1, further comprising: A second reservoir for storing chemical reagents, which are added to the replacement liquid coolant supplied to the flow circulation during the replacement operation.

7. The liquid coolant replacement system according to claim 6, further comprising: in, The control system receives data from the coolant mass sensor subsystem indicating the determined mass of the active liquid coolant; as well as The control system adjusts the replacement of the active liquid coolant and the addition of the chemical reagent to the replacement liquid coolant based on the determined mass of the active liquid coolant.

8. The liquid coolant replacement system according to claim 1, wherein, During the replacement operation, the liquid coolant replacement system replaces the active liquid coolant with replacement liquid coolant at a flow rate based on a determined mass of the active liquid coolant.

9. The liquid coolant replacement system according to claim 1, wherein, The control system generates control signals for the liquid coupling subsystem for repetitive, periodic replacement operations.

10. The liquid coolant replacement system according to claim 1, wherein, The replacement operation includes a first replacement operation and a second replacement operation, and wherein the control signal includes: A first set of control signals is used for the first replacement operation, which causes the liquid coupling subsystem to replace a first predetermined amount of active liquid coolant with replacement liquid coolant, wherein the first predetermined amount of active liquid coolant is less than the amount of active liquid coolant in the coolant distribution unit before the first replacement operation; and The second set of control signals is used for the second replacement operation, which causes the liquid coupling subsystem to replace a second predetermined amount of active liquid coolant with a replacement liquid coolant, wherein the second predetermined amount of active liquid coolant is equal to the amount of active liquid coolant in the coolant distribution unit before the second replacement operation.

11. The liquid coolant replacement system according to claim 1, wherein: The liquid coupling subsystem includes: A first physical flow path, wherein the first physical flow path receives active liquid coolant from the flow cycle; and A second physical flow path, the second physical flow path providing replacement liquid coolant from the first reservoir to the flow cycle; and The control system generates a control signal that causes the first physical flow path to receive the active liquid coolant and causes the second physical flow path to simultaneously provide replacement liquid coolant at substantially equal flow rates.

12. The liquid coolant replacement system according to claim 10, wherein: The liquid coupling subsystem includes: A single physical flow path, wherein the single physical flow path selectively receives active liquid coolant from the flow cycle during a first selection period and selectively supplies replacement liquid coolant from the first reservoir to the flow cycle during a second selection period; and The control system generates a control signal that causes the single physical flow path to selectively receive active liquid coolant during a first time period and selectively provide replacement liquid coolant during a second time period.

13. A method for replacing liquid coolant in a coolant distribution unit, comprising: Generate a replacement operation signal; In response to the replacement operation signal, the liquid coupling system is controlled to perform the following operations: supplying replacement liquid coolant to the flow circulation of active liquid coolant in the coolant distribution unit via the liquid coupling system, and receiving active liquid coolant from the flow circulation of the coolant distribution unit via the liquid coupling system: While the coolant distribution unit is operating and providing cooling to the electronic system, it receives active liquid coolant that has been removed from the flow cycle. as well as While the coolant distribution unit is operating and providing cooling to the electronic system, it also provides replacement liquid coolant to the flow circulation. The operation includes: Determine the mass of the active liquid coolant; The replacement operation is initiated when the determined mass of the active liquid coolant falls below a first threshold mass level; and During the replacement operation: Periodically determine the refresh quality level of the active liquid coolant, and The replacement operation is stopped when the determined renewal quality of the active liquid coolant exceeds the first threshold quality level.

14. The method of claim 13, further comprising: Chemical reagents are added to the replacement liquid coolant based on the determined mass of the active liquid coolant.

15. The method according to claim 13, wherein, The operation of receiving active liquid coolant removed from the flow cycle from the coolant distribution unit while the coolant distribution unit is in operation, and the operation of supplying replacement liquid coolant to the flow cycle while the coolant distribution unit is in operation, are performed periodically.

16. The method of claim 13, wherein: Receiving the active liquid coolant removed from the flow cycle is accomplished via a first physical flow path; and The replacement liquid coolant is supplied to the flow circulation via a second physical flow path that is different from the first physical flow path.

17. The method of claim 13, wherein: Receiving the active liquid coolant removed from the flow cycle and supplying replacement liquid coolant to the flow cycle is accomplished via a single physical flow path at separate first and second time periods.

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