Local PLC controls with state machine for operational cloud

Abstract

Systems and methods for performing immersion cooling of electronics are described, particularly monitoring and controlling immersion cooling processes within an immersion cooling tank. A programmable logic controller (PLC) is described, which may be programmed with a number of PLC states. Each PLC state may indicate a context in which sensor data is to be interpreted. The PLC may control certain aspects of an immersion cooling system and / or process, and may additionally be coupled to one or more higher-level controllers capable of altering a wider range of physical properties of the immersion cooling systems and processes than the PLC.

Description

LOCAL PLC CONTROLS WITH STATE MACHINE FOR OPERATIONAL CLOUDCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Application No. 63 / 519,086, filed August 11, 2023, which is hereby incorporated by reference in its entirety.BACKGROUND

[0002] As feature sizes and transistor sizes have decreased for integrated circuits (ICs) including chips and semiconductor dies, the amount of heat generated by a single chip, such as a microprocessor, has increased. Chips that once were air cooled have evolved to chips needing more heat dissipation than can be provided by air alone. In some cases, immersion cooling of chips in a tank containing a coolant liquid is employed to maintain IC chips at appropriate operating temperatures.

[0003] One type of immersion cooling is two-phase immersion cooling, in which heat from a semiconductor die boils the coolant liquid. The boiling creates a coolant-liquid vapor in the tank, which is condensed by cooling coils back to liquid form. Heat from the semiconductor dies can then be sunk into the liquid-to-gas and gas-to-liquid phase transitions of the coolant liquid. This allows chips to be run at a faster rate and allows for more computationally intensive processes than were previously possible. Controlling immersion cooling systems may be difficult due to the phase transitions, chemistries, volumes, and temperatures involved, and system failures may present human health hazards as well as potentially cost millions of dollars.SUMMARY

[0004] In some aspects, the techniques described herein relate to a system for immersion cooling. The system includes at least one sensor configured to monitor a physical property associated with an immersion cooling tank, a programmable logic controller (PLC) communicatively coupled to the at least one sensor, and a second controller communicatively coupled to the PLC and configured to alter the physical property in response to a change in state of the PLC.

[0005] In some aspects, the techniques described herein relate to a system for immersion cooling, the system including at least one sensor configured to monitor a physical propertyassociated with an immersion cooling process, a programmable logic controller (PLC) communicatively coupled to the at least one sensor, and a second controller communicatively coupled to the PLC and configured to alter the physical property in response to a change in state of the PLC.

[0006] In some aspects, the techniques described herein relate to a method for operating an immersion cooling tank, the method including, receiving, by a programmable logic controller (PLC), an indication of a physical property associated with the immersion cooling tank from at least one sensor, and altering, by a second controller, the physical property in response to a change in state of the PLC.

[0007] In some aspects, the techniques described herein relate to a method for operating an immersion cooling tank. The method includes receiving, by a first controller, a current state of a programmable logic controller (PLC) of a plurality of PLC states. The plurality of PLC states includes one or more of a normal PLC state, a power off PLC state, an open PLC state, or a throttled PLC state. The method further includes sending, by the first controller, a signal to alter a physical property associated with the immersion cooling tank in response to determining the PLC is not in the normal PLC state and receiving, by the PLC, an indication of a new PLC state

[0008] In some aspects, the techniques described herein relate to a method for controlling an immersion cooling process. The method includes receiving, by a programmable logic controller (PLC), an indication of a physical property associated with the immersion cooling process from at least one sensor, and altering, by a second controller, the physical property in response to a change in state of the PLC.

[0009] All combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are part of the inventive subject matter disclosed herein. The terminology used herein that also may appear in any disclosure incorporated by reference should be accorded a meaning most consistent with the particular concepts disclosed herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The skilled artisan will understand that the drawings primarily are for illustrative purposes and are not intended to limit the scope of the inventive subject matter described herein.The drawings are not necessarily to scale; in some instances, various aspects of the inventive subject matter disclosed herein may be shown exaggerated or enlarged in the drawings to facilitate an understanding of different features. In the drawings, like reference characters generally refer to like features (e.g., functionally similar and / or structurally similar elements).

[0011] FIG. 1A illustrates aspects of an immersion cooling system including tank, controllers, and sensors.

[0012] FIG. IB illustrates aspects of an immersion cooling system including tank, PLC, sensors, and power hardware.

[0013] FIG. 2 illustrates PLC states in accordance with embodiments of the invention.

[0014] FIG. 3 illustrates transitions between PLC states in accordance with embodiments of the invention.

[0015] FIG. 4 illustrates exemplary sensor inputs to a PLC.

[0016] FIG. 5 depicts aspects of an immersion-cooling system for dissipating heat from one or more semiconductor die packages via immersion cooling.

[0017] FIG. 6 is a flowchart of an exemplary method for operating an immersion cooling tank.

[0018] FIG. 7 is a flowchart of an exemplary method for controlling an immersion cooling process.

[0019] FIG. 8 is a flowchart of an exemplary method for operating an immersion cooling tank.DETAILED DESCRIPTION

[0020] FIG. 1A illustrates a system 100a for immersion cooling. System 100a may include one or more sensors capable of monitoring a physical property of an immersion cooling tank 102 and / or immersion cooling process. System 100a may further include a programmable logic controller (PLC) operably connected to an immersion cooling tank 102 or other immersion cooling system. The PLC 110 may be further operably connected to the one or more sensors, controller 120, and stack light 180. Controller 120 may be configured to control one or more operational parameters of immersion cooling tank 102 and / or a related immersion cooling process.

[0021] PLC 110 may be a microprocessor (e.g., a central processing unit (CPU)), a digital signal processing (DSP) die, an application- specific integrated circuit (ASIC), field- programmable gate array (FPGA), and / or other densely patterned semiconductor die. PLCs used in accordance with the present invention may be designed specifically for high reliability, low cost, ability to withstand wider temperature ranges, vibrations, or impacts than typical commercial computers, and resistance to electrical noise. PLC 110 may be programmed using an ICE 61131-3 standard and associated Structured Text and / or Instruction List programming languages. PLC 110 may be programmed using the Ladder Diagram, Eunction Block Diagram, or Sequential Eunction Chart graphical programming languages.

[0022] PLC 110 may store programming instructions on non-volatile memory such as flash memory, or may store programming instructions on battery-powered RAM. In some embodiments, PLC 110 may be programmed remotely using the same connections PLC 110 may have in operation. In one or more alternative embodiments, PLC 110 may need to be programmed by the physical removal and replacement of built-in memory (e.g. replacement of a flash drive) or by directly connecting to PLC 110, for example with a USB or similar connection.

[0023] Immersion cooling tank 102 may be used with a single-phase or two-phase immersion cooling process. In a single-phase immersion cooling process, an electronic element such as a semiconductor die, integrated circuit (IC), computer chip (such as a CPU, graphics processing unit (GPU), LPGA, ASIC, and the like), motherboard, or similar computing device may be immersed in a dielectric fluid (such as immersion cooling liquid 104) which conducts heat generated by the electronic element without conducting or short circuiting electrical signals. This may provide more efficient cooling than ambient or chilled air alone. In a single-phase immersion cooling process, the heat generated by the electronic element such as a computer chip is not enough to boil the immersion cooling liquid 104, and the immersion cooling liquid 104 stays in a single (liquid) phase.

[0024] Additionally or alternatively, an immersion cooling process used in embodiments of the invention may be a two-phase immersion cooling process, in which heat generated by the electronic element is enough to boil the immersion cooling liquid 104 and form immersion cooling vapor 106. In a two-phase immersion cooling process, the immersion cooling liquid 104 carries heat with it as it boils and exchanges the heat with a cooler surface, such as the condenser coil 570 shown in PIG. 5. Above immersion cooling vapor 106 is headspace 108, which may contain a mixture of air, water vapor, and immersion cooling vapor 106.

[0025] Controller 120 may be a “tank manager” controller configured to control operations of the tank or components inside the tank such as condenser coil flow rate, immersion cooling filter flow rate, server racks or semiconductor dies (e.g. semiconductor dies 550 in FIG. 5) including throttling, rate limiting, or depowering semiconductor dies within an immersion cooling system, ventilation systems, cooling fans, tank power, and the like. Additionally, or alternatively, controller 120 may be a cloud-based control plane such as a distributed computing system programed to monitor and issue commands to a plurality of tanks, immersion cooling systems, servers, computer elements, and the like. In an embodiment, controller 120 may be embodied as a plurality of hierarchical controllers. For example, controller 120 may include a tank manager configured to control one or more immersion cooling tanks and may further include a distributed control plane monitoring the tank manager and programmed to determine one or more actions to take in response to inputs from the tank manager, such as powering down an immersion cooling tank or issuing a notification to a human operator in the event of a malfunction. PLC 110 may not have the functionality (or permission from the owners / operators of those computing hardware) to communicate with computing hardware immersed within immersion cooling liquid 104, whereas controller 120 may be operably coupled to computing hardware immersed within immersion cooling liquid 104 and may be able to checkpoint or save data on immersed computing hardware or adjust, throttle, pause, and / or control processes (e.g. artificial intelligence (Al) model training) running on the immersed computing hardware.

[0026] PLC 110 may be limited to simple functions as compared to controller 120. These functions may include monitoring the one or more sensors, disconnecting power to tank 102, changing to one of a predetermined number of states, and sending notification messages (also referred to as tickets) to an entity such as a human operator or controller 120. The benefit of this simple functionality is increased robustness, reliability, and resistance to environmental disruptions such as power surges, abnormally high or low temperatures, vibrations (e.g. due to seismic activity) as compared to more general-purpose computers. PLC 110 may also provide improved resistance to malware, hacking, and similar digital attack vectors designed to disrupt functioning of systems to which PLC 110 is communicatively coupled when compared to controller 120 or similarly complex control devices.

[0027] PLC 110 may be operably coupled to a wide variety of sensors configured to monitor operational parameters of immersion cooling system 100a, immersion cooling tank 102, or immersion cooling processes associated with system 100a or immersion cooling tank 102. In an embodiment, sensors used in accordance with system 100a may transmit sensor readings oroutputs at regular intervals, such as once per second, once per minute, once per tenth of a second, once per hour, etc. In an embodiment, sensors used in accordance with system 100a may transmit sensor readings when actively polled by PLC 110. FIG. 1 A illustrates a variety of sensors that may be used in accordance with the invention.

[0028] Tank 102 may include water inlets and outlets for the conveyance of cooling water through condenser coils (570 in FIG. 5, not shown in FIG. 1A). Water inlet may include water inlet pressure sensor 126 and water inlet temperature sensor 146 for measuring the pressure and temperature, respectively, of water entering a condenser coil of tank 102. Water inlet pressure sensor 126 and water inlet temperature sensor 146 may be communicatively coupled to PLC 110. Water inlet pressure sensor 126 and water inlet temperature sensor 146 may provide an indication of whether water is flowing at sufficient temperatures and pressures for operation of immersion cooling tank 102 and related cooling processes, e.g. for a given amount of heat generated by computational processes being performed by semiconductor dies immersed in immersion cooling liquid 104.

[0029] Tank 102 may additionally include one or more water outlets for conveying heated water out of condenser coils. Such water outlets may include water outlet pressure sensor 128 and water outlet temperature sensor 148 configured to measure pressure and temperature, respectively, of cooling water leaving tank 102 and / or condenser coils included in tank 102. Water outlet pressure sensor 128 and water outlet temperature sensor 148 may be communicatively coupled to PLC 110. Water outlet pressure sensor 128 and water outlet temperature sensor 148 may provide an indication of whether water is flowing at sufficient temperatures and pressures for operation of immersion cooling tank 102 and related cooling processes, e.g. for a given amount of heat generated by computational processes being performed by semiconductor dies immersed in immersion cooling liquid 104. For example, a difference of pressure readings between water inlet pressure sensor 126 and water outlet pressure sensor 128 may indicate a leak in a cooling water circuit and may indicate a need to immediately depower operation of tank 102 or system 100a.

[0030] System 100a may include liquid level sensor 130, liquid level sensor 132, and liquid level sensor 134. These sensors may provide an indication (such as a binary value indicating the presence or absence of liquid) of a liquid level within tank 102 by detecting the presence of fluid in contact with a detection element, for example when a magnetic or mechanical switch is triggered by a floating element that is lifted in the presence of fluid or by detecting a difference in conductivity or capacitance as compared to air. When the fluid level drops below a certainlevel, the floating element drops with it until the detection element is no longer activated. The fluid sensor may output a logical “1,” for example a “high” voltage such as about 1 V, about 5 V, about 10 V, and the like, when fluid is in contact with the sensor. When fluid is no longer in contact with the sensor, the output may change to a logical “0,” for example 0 V with respect to an electrical ground. Liquid level sensors 130, 132, and 134 may provide advanced warning if the level of immersion cooling liquid 104 is too low for steady or safe operation of system 100a. Liquid level sensor 130 may indicate a “fluid low” level, for example when the fluid is at only about 25% of a maximum level, height, or volume. Liquid level sensor 132 may indicate a “fluid medium” level, for example when the fluid is at about 50% of a maximum level, height, or volume. Liquid level sensor 134 may provide a “fluid high” level, for example when the fluid is at or above about 80% of a maximum level, height, or volume.

[0031] Immersion cooling tank 102 may include filter flow sensor 140 configured to monitor a fluid flow rate through filter 175. Filter 175 may operate to filter particulates and contaminants from immersion cooling liquid 104 that might negatively impact immersion cooling liquid 104, for example by altering the dielectric constant or dielectric loss tangent of immersion cooling liquid 104 and cause it to introduce undesirable noise, signal loss, or signal interruption to semiconductor dies or other electrical elements operating in immersion cooling liquid 104. PLC 110 may receive one or more sensor readings from filter flow sensor 140 and compare the one or more readings with a threshold. If the flow of immersion cooling liquid 104 through filter flow sensor 140 is below the threshold, the PLC 110 may change to a new state and / or may issue a ticket, warning, or other notification indicating that filter flow is below a threshold level.

[0032] System 100a may include pressure sensor 142 and pressure sensor 144, which are configured to detect and monitor pressure within headspace 108 of immersion cooling tank 102. Tank 102 may be sealed to prevent immersion cooling vapor 106 or gasses from headspace 108 from leaking out of tank 102 and exposing humans near tank 102 to potentially harmful chemicals. This means that during an immersion cooling process, immersion cooling vapor 106 generated from boiled immersion cooling liquid 104 will increase the pressure in tank 102. If the pressure increase is too high, tank 102 may deform or rupture, causing loss of immersion cooling liquid 104, damage to system 100a and adjacent objects, and potentially harming people.Pressure sensor 142 and pressure sensor 144 may provide readings of pressure inside tank 102, which can provide PLC 110 and controller 120 with early indications that the pressure inside tank 102 is higher than a safe operating limit. PLC 110 and / or controller 120 may throttleimmersed computing components or cut power to tank 102 to prevent additional heat from being added to the system and thereby reduce or prevent boiling of immersion cooling liquid 104, which prevents the pressure inside tank 102 from increasing further.

[0033] System 100a may include liquid temperature sensor 150 configured to provide a temperature reading of immersion cooling liquid 104. Liquid temperature sensor 150 may be a thermocouple, a thermometer, a resistance temperature detector, and the like. Liquid temperature sensor 150 may convert a voltage to a temperature reading and may be interpreted by PLC 110 to read Fahrenheit, Celsius, Kelvin, Rankine, or any other desired temperature units.

[0034] System 100a may include humidity sensor 158, which may be operably coupled to PLC 110 and configured to read a relative humidity inside tank 102, and particularly within headspace 108. Monitoring relative humidity is important in two-phase immersion cooling systems and processes due to the potential for oxidation or formation of acids when immersion cooling vapor is mixed with water. This can lead to corrosion of components within tank 102, breakdown of immersion cooling liquid 104, and / or buildup of sludge or other contaminants that might interfere with the proper operation of system 100a. Humidity sensor 158 may output relative humidity to PLC 110. The relative humidity output from humidity sensor 158 may be compared to one or more thresholds. For example, PLC 110 may receive a reading from humidity sensor 158 that the relative humidity in headspace 108 is above 25%. If the relative humidity reading from humidity sensor 158 remains above the 25% threshold for more than a threshold amount of time (for example, 10 minutes), PLC 110 may transition to a different state such as “service,” “throttle,” “soft off,” or may disconnect power to the tank 102 and / or any computing hardware immersed in immersion cooling liquid 104. PLC 110 states are discussed in greater detail in the description of FIG 2.

[0035] System 100a may include lid open sensor 170, which may output a binary signal indicating that a lid 103 of tank 102 is open or closed. A reading from lid open sensor 170 indicating that lid 103 of tank 102 is open may cause PLC 110 to transition to the “Lid Open” state, discussed in more detail in FIG. 2. This may provide an indication that system 100a and / or tank 102 is undergoing servicing or maintenance and that tank 102 or components within or adjacent to tank 102 should not be powered. In an embodiment, lid open sensor 170 may be a mechanical or capacitive switch that is opened or closed by the physical movement of lid 103.

[0036] System 100a may further include stack light 180, which may provide a visual indication of the current state of system 100a and tank 102. Stack light 180 may include multiplelights of different colors, including blue, green, orange, red, and white. PLC 110 may command stack light 180 to display different colors, combinations of colors, or illumination patterns (e.g. flashing, strobing, and / or fluctuating intensities at a predetermined rate) to indicate different states of system 100a such as powered on, emergency off, safe to approach, etc.

[0037] Now referring to FIG. IB, a system 100b including tank 102, PLC 110, power components including power rack 155, and sensors for monitoring various power components is illustrated. System 100b may be integrated into system 100a. System 100b may include one or more emergency stop (E-Stop) buttons 188 for immediately depowering the entirety of system 100a and 100b when pressed, for example if an operator was being electrically shocked by a damaged component and power needed to be disconnected to stop the operator from being shocked. System 100b may include E-Stop sensor 184, which provides a binary indication of whether or not E-Stop button 188 is depressed.

[0038] System 100b may include power supply unit (PSU, also referred to as a rectifier) health sensors PSU1 health sensor 160, PSU2 health sensor 162, PSU3 health sensor 164, and PSU4 health sensor 166. These sensors may provide an indication of the current state or health of PSUs providing power to tank 102 and any components immersed within immersion cooling liquid 104 such as servers 105. PSU health sensors 160-166 may output fault codes indicative of particular states of each PSU.

[0039] System 100b may include PLC fan health sensor 168, which may monitor and provide readings of one or more fans integrated with and providing cooling to PLC 110. Insufficient cooling of PLC 110 may lead to reduced performance and therefore may be advantageous to monitor using PLC fan health sensor 168. Likewise, system 100b may include PLC cabinet temperature sensor 182 for monitoring a temperature of a housing containing PLC 110.

[0040] System 100b may include busbar voltage sensor 174 and busbar voltage sensor 176 for determining the voltage on busbar 172 providing power to each of the devices being immersion cooled within tank 102, such as servers 105. Proper operation of these devices may depend on voltage being set within a predetermined range, and busbar voltage sensor 174 and busbar voltage sensor 176 may provide PLC 110 with readings of the voltage on busbar 172 to determine if the readings are within the proper range for normal operation of servers 105 or other devices immersed in immersion cooling liquid 104. System 100b may further include power enable sense 186 configured to indicate if a main power switch of power rack 155 is in an “on”position. PLC 110 may be further communicatively coupled to harness detection sensor 190, which may provide an reading indicating that PLC 110 is connected to power rack 155. PLC 110 may disconnect power from tank 102 or other components if harness detection sensor 190 indicates that PLC 110 is not communicatively coupled to power rack 155. PLC 110 may be further communicatively coupled to breaker state sensor 194, which may provide a reading from each circuit breaker within a circuit breaker panel 193 indicating the status of the circuit breaker, including whether each breaker has been tripped or is enabled.

[0041] Now referring to FIG. 2, PLC 110 may be programmed with a number of states which provide a context- specific framework for interpreting sensor readings and characterizing operational conditions of system 100a, system 100b, and tank 102. These states may be represented by state machine 200, illustrated in FIG. 2. State machine 200 may include a collection of PLC states that enable PLC 110 to provide context- specific information to controller 120 based on the combination of sensor readings and PLC state. In an embodiment, PLC 110 may be in one of eight PLC states: energize state 210, normal state 220, service state 230, lid open state 240, throttle state 250, soft off state 260, critical off state 270, and critical power state 280.

[0042] PLC 110 may issue a ticket upon initially transitioning into a second state from a first state. A ticket may be a message or similar data structure indicating the current state of the PLC 110 and / or a current state of immersion cooling equipment to which PLC 110 is communicatively coupled, such as tank 102. Tickets illustrated in FIG. 2 include energize ticket 212, normal ticket 222, service ticket 232, lid open ticket 242, throttle ticket 252, soft off ticket 262, critical off ticket 272, and critical power ticket 282.

[0043] Tickets generated by PLC 110 may have different severity or priority levels indicating an order in which they should be addressed, where the tickets are routed (including whether human intervention is required), and a time limit for responding to each ticket. In an embodiment, severity levels associated with events or state transitions may include: informational, low, medium, high, and severe. An informational severity level may mean that no human intervention is required and no timeframe is set for responding to the event, but a record of the event causing the informational severity level may be created. A low severity level may indicate that customers (e.g. users of tank 102) may not be impacted, but a repair or servicing may eventually be required. A low severity ticket may have a one week timeframe for addressing the event. A medium severity ticket may indicate that repair or servicing is required within 24 hours, but customers will not be immediately impacted. A high severity ticket may immediatelymove the issue to the front of a servicing or repair queue and indicate that the appropriate personnel should begin addressing the issue right away. A high severity ticket may indicate that the event may potentially result in a failure of customer hardware or computational processes, or that a safety issue exists. A ticket labeled severe may require immediate attention from on-site personnel as well as an escalation to higher- level management personnel such as operations leadership. A severe ticket may indicate an immediate health risk and / or critical impacts to customers hardware and processes.

[0044] Energize state 210 indicates that system 100a, system 100b, and / or tank 102 are or are about to be in the process of being energized prior to steady-state operation. Upon entering energize state 210, PLC 110 may activate one or more lights from stack light 180 to provide a visual indication to any humans nearby that system 100a, system 100b, and / or tank 102 are potentially in the process of being powered up. PLC 110 may additionally issue energize ticket 212 indicating that breakers in circuit breaker panel 193 should be closed. Energize ticket 212 may also provide a record of when system 100a, system 100b, and / or tank 102 were energized. Energize state 210 may be accompanied by a predetermined lighting state of stack light 180, for example, a pulsing of the red light in stack light 180.

[0045] Normal state 220 indicates steady-state operation of system 100a, system 100b, and tank 102 and is the state accompanying proper operation of tank 102 and associated components. Upon entering normal state 220, PLC 110 may issue normal ticket 222 indicating that tank 102 is ready for operation including provisioning of computational tasks to computing hardware inside tank 102 such as servers 105. Normal state 220 indicates to controller 120 and any operators responsible for tank 102 and systems 100a and 100b that all aspects of system 100a, system 100b, and tank 102 are operating within normal bounds. Normal state 220 may be accompanied by a predetermined lighting state of stack light 180; for example, a steady illumination of red light in stack light 180.

[0046] Service state 230 indicates that one or more components of system 100a, system 100b, or tank 102 require servicing. Examples of required service may include immersion cooling liquid 104 below a threshold level, e.g. when the level of immersion cooling liquid 104 falls below liquid level sensor 132 indicating immersion cooling liquid 104 may be below about 50% of a maximum level. Upon entering service state 230, PLC 110 may issue service ticket 232 indicating that servicing of one or more components is required. Service ticket 232 may additionally indicate which component requires servicing, a timeframe for responding to the issue causing the transition to service state 230, a timestamp indicating when the issue occurred,and the like. Service state 230 may be accompanied by a predetermined lighting state of stack light 180; for example, a steady illumination of orange light in stack light 180.

[0047] Lid open state 240 indicates that the lid 103 of tank 102 is open, for example if a technician is performing maintenance on tank 102, adding immersion cooling liquid 104, placing or removing one or more computing hardware in immersion cooling liquid 104, etc. Upon entering lid open state 240, PLC 110 may lid open ticket 242 indicating that lid 103 is open, the tank 102 should not be powered, computing hardware within immersion cooling liquid 104 should be depowered or throttled below a maximum computational speed or throughput, etc. Lid open state 240 may be accompanied by a predetermined lighting state of stack light 180; for example, a pulsing of orange light in stack light 180.

[0048] Throttle state 250 may indicate that computing hardware within immersion cooling liquid 104 is being throttled. Throttling computing hardware may mean lowering a frequency of a processor such as a CPU so that calculations are not performed as quickly and less heat is generated. Throttling may additionally or alternatively mean lowering an operational voltage of a component. Throttling computing hardware within immersion cooling liquid 104 may be important when a level of immersion cooling liquid 104 is below a threshold, when a condenser system is not working properly, when immersion cooling liquid 104 has degraded and is not conducting heat well enough to provide sufficient cooling to immersed computing hardware, and the like. Upon entering throttle state 250, PLC 110 may issue throttle ticket 252 indicating that PLC 110, controller 120, or a human operator has commanded the throttling of computing hardware within immersion cooling liquid 104 and indicating that additional follow-up actions are required. Throttle ticket 252 may have a high severity level. Throttle state 250 may be accompanied by a predetermined lighting state of stack light 180; for example, a pulsing illumination of blue light in stack light 180.

[0049] Soft off state 260 may indicate that computing hardware within immersion cooling liquid 104, tank 102, system 100a, and / or system 100b must power down or reduce operational power below a threshold level (for example, reduce power delivered to computing hardware within immersion cooling liquid 104 to less than about 5 kW) and may indicate that an issue must be addressed by a technician or other personnel before resuming normal operation. Upon entering soft off state 260, PLC 110 may issue soft off ticket 262 with high severity indicating that power should be shut off within a predetermined timeframe (although not instantaneously as with critical off state 270 and critical power state 280). Soft off state 260 may occur in response to any of a plurality of events such as relative humidity exceeding a threshold level for athreshold amount of time or immersion cooling liquid 104 below a critical level for a threshold amount of time. Soft off state 260 may differ from critical off state 270 and critical power state 280 in that the power may not necessarily need to be cut immediately (immediately indicating the order of milliseconds, or at most a single digit number of seconds) in soft off state 260, whereas power may need to be cut as quickly as possible by PLC 110, controller 120, or a human operator in critical off state 270 and critical power state 280. Soft off state 260 may be accompanied by a predetermined lighting state of stack light 180; for example, a steady illumination of blue light in stack light 180.

[0050] Critical off state 270 may indicate that a critical condition has occurred and the power should be disconnected from one or more of tank 102, system 100a, or system 100b as quickly as possible. Critical off state 270 may be triggered by a press of E-Stop button 188, upon PLC 110 receiving an indication that the level of immersion cooling liquid 104 is below the “low” level measured by liquid level sensor 130 (which may be a level considered likely to do significant damage to the tank 102 or computing hardware within tank 102 if operation continues), or another suitably urgent condition arises. Upon entering critical off state 270, PLC 110 may issue critical off ticket 272 with a high severity indicating that power should be (or already was) shut off. Critical off state 270 may be accompanied by a predetermined lighting state of stack light 180; for example, a steady illumination of green light in stack light 180 and an accompanying buzz for one second from buzzer 198.

[0051] Critical power state 280 may indicate that a busbar voltage providing power to electronics inside tank 102 is above a maximum threshold or below a minimum threshold, that a harness line is disconnected (as indicated by harness detection sensor 190), or that PLC 110 does not have an indication of the current power state of system 100a, system 100b, power rack 155, or other critical components as indicated by power enable sense 186. Critical power state 280 may indicate that power is still connected to system 100a, system 100b, tank 102, or other components even after E-Stop button 188 has been pressed. Upon entering critical power state 280, PLC 110 may issue critical power ticket 282 with high severity indicating that a critical power error has occurred. Critical off state 270 may be accompanied by a predetermined lighting state of stack light 180; for example, a steady pulsing of orange, blue, and red lights in stack light 180 and an accompanying pulsing buzz for one second from buzzer 198.

[0052] Now referring to EIG. 3, transitions between PLC states are described with reference to state transition map 300. State transition map 300 groups states into two categories of potentially “healable” and not “healable.” “Healable,” as used herein, indicates a PLC statemay transition back to normal state 220 by itself without being forced back into normal state 220 by controller 120 or a human operator. For example, if lid 103 is opened, PLC 110 will transition into lid open state 240. Once lid 103 is closed again, PLC 110 will transition from lid open state 240 back into normal state 220 without any additional commands from controller 120 or a human operator. However, if PLC 110 transitions into a non-healable state (any of states 250- 280), it will not be able to transition back into the normal state until controller 120 or a human operator issues an instruction for PLC 110 to do so.

[0053] PLC 110 may transition from any state to critical off state 270 if the fluid level is critically low (for example, below low low liquid level sensor 130) shown as 378 in FIG. 3 or if E-Stop button 188 is pressed, shown as 379 in FIG. 3. Similarly, PLC 110 may transition from any state to critical power state 280 if a critical power error is encountered, shown as 389 in FIG. 3.

[0054] PLC 110 may transition from energize state 210 to a variety of different states based on sensor inputs received by PLC 110 while in energize state 210. FIG. 3 illustrates transition 312 showing a transition from energize state 210 to normal state 220. A transition from energize state 210 to critical off state 270 may occur if PLC 110 receives an indication that the level of immersion cooling liquid 104 is below liquid level sensor 130 or liquid level sensor 132. A transition from energize state 210 to critical off state 270 may occur if PLC 110 receives an indication that the level of immersion cooling liquid 104 is above liquid level sensor 134. A transition from energize state 210 to critical off state 270 may occur if PLC 110 receives an indication that an inlet water temperature is above a threshold as indicated by water inlet temperature sensor 146, that inlet water temperature is below a threshold as indicated by water inlet pressure sensor 126, that E-Stop button 188 has been pressed, and that a difference between water inlet pressure and water outlet pressure is less than a threshold. PLC 110 may transition from energize state 210 to critical power state 280 in response to a busbar voltage exceeding a maximum threshold or falling below a minimum threshold, that a harness line is disconnected (as indicated by harness detection sensor 190), or that PLC 110 does not have an indication of the current power state of system 100a, system 100b, power rack 155, or other critical components as indicated by power enable sense 186.

[0055] PLC 110 may transition from normal state 220 to service state 230 (shown as transition 323 in FIG. 3) if immersion cooling liquid 104 falls below medium liquid level sensor 132, if a water inlet temperature is above a threshold, if a water inlet pressure is below a threshold, if inlet and outlet water pressure difference is below a threshold, if a pressuredifference across filter 175 is above a maximum threshold or below a minimum threshold, if aPSU fails, if the PLC cooling fan fails, or if the PLC cabinet temperature rises above a threshold.

[0056] PLC 110 may transition from normal state 220 to lid open state 240 (shown as transition 324 in FIG. 3) if lid 103 is open, and may transition from lid open state 240 back to normal state 220 (shown as transition 342 in FIG. 3) if lid 103 is closed.

[0057] PLC 110 may transition from normal state 220 to throttle state 250 (shown as transition 325 in FIG. 3) if the level of immersion cooling liquid 104 is above high liquid level sensor 134 or if headspace pressure is greater than a maximum threshold for longer than a specified length of time.

[0058] PLC 110 may transition from normal state 220 to soft off state 260 (shown as transition 326 in FIG. 3) if relative humidity is above a threshold for longer than a specified length of time.

[0059] PLC 110 may transition from normal state 220 to critical off state 270 if level of immersion cooling liquid 104 is below low liquid level sensor 130 or if E-Stop button 188 is pressed.

[0060] PLC 110 may transition from normal state 220 to critical power state 280 if busbar voltage exceeds a high voltage threshold or drops below a low voltage threshold, if PLC 110 cannot detect certain power levels or activation states (such as power rack 155), or if PLC 110 cannot detect the power harness from harness detection sensor 190.

[0061] PLC 110 may transition from service state 230 to normal state 220 if all of the following conditions are true: fluid level of immersion cooling liquid 104 is above medium liquid level sensor 132, inlet water temperature is below a threshold for a predetermined length of time, inlet water pressure is above a threshold for a predetermined length of time, inlet and outlet water pressure differential is above a threshold for a predetermined length of time, pressure across filter 175 is below a maximum threshold and above a minimum threshold, sensors 160-168 are all indicating healthy readings, and PLC cabinet temperature is below a threshold.

[0062] PLC 110 may transition from service state 230 to lid open state 240 (shown as transition 334 in FIG. 3) upon lid 103 being opened. PLC 110 may transition from service state 230 to throttle state 250 if immersion cooling liquid 104 is below medium liquid level sensor 132 for a predetermined length of time, if immersion cooling liquid 104 is above high liquid levelsensor 134, or if pressure in headspace 108 is above a threshold for a predetermined amount of time.

[0063] PLC 110 may transition from service state 230 to soft off state 260 if relative humidity of headspace 108 exceeds a threshold for a predetermined length of time.

[0064] PLC 110 may transition from service state 230 to critical off state 270 if fluid level of immersion cooling liquid 104 is below low liquid level sensor 130 or if E-Stop button 188 is pressed.

[0065] PLC 110 may transition from service state 230 to critical power state 280 if busbar voltage exceeds a high voltage threshold or drops below a low voltage threshold, when PLC 110 cannot detect certain power levels or activation states (such as power rack 155), or when PLC 110 cannot detect the power harness from harness detection sensor 190.

[0066] PLC 110 may transition from lid open state 240 to critical off state 270 if fluid level of immersion cooling liquid 104 is below low liquid level sensor 130 or if E-Stop button 188 is pressed.

[0067] PLC 110 may transition from lid open state 240 to critical power state 280 if busbar voltage exceeds a high voltage threshold or drops below a low voltage threshold, when PLC 110 cannot detect certain power levels or activation states (such as power rack 155), or when PLC 110 cannot detect the power harness from harness detection sensor 190.

[0068] PLC 110 may transition from throttle state 250 to soft off state 260 (shown as transition 356 in FIG. 3) if relative humidity of headspace 108 exceeds a threshold for a predetermined length of time, if immersion cooling liquid 104 is below medium liquid level sensor 132 for a predetermined length of time, or if pressure in headspace 108 is above a threshold for a predetermined amount of time.

[0069] PLC 110 may transition from throttle state 250 to critical off state 270 if fluid level of immersion cooling liquid 104 is below low liquid level sensor 130 or if E-Stop button 188 is pressed.

[0070] PLC 110 may transition from throttle state 250 to critical power state 280 if busbar voltage exceeds a high voltage threshold or drops below a low voltage threshold, when PLC 110 cannot detect certain power levels or activation states (such as power rack 155), or when PLC 110 cannot detect the power harness from harness detection sensor 190.

[0071] PLC 110 may transition from to soft off state 260 to critical off state 270 (shown as transition 367 in FIG. 3) if fluid level of immersion cooling liquid 104 is below low liquid level sensor 130, if fluid of level immersion cooling liquid 104 is below medium liquid level sensor 132 for more than a predetermined length of time, if E-Stop button 188 is pressed, or relative humidity of headspace 108 exceeds a threshold for a predetermined length of time.

[0072] PLC 110 may transition from soft off state 260 to critical power state 280 if busbar voltage exceeds a high voltage threshold or drops below a low voltage threshold, when PLC 110 cannot detect certain power levels or activation states (such as power rack 155), or when PLC 110 cannot detect the power harness from harness detection sensor 190.

[0073] PLC 110 may transition from critical off state 270 to critical power state 280 if busbar voltage is greater than 0, when PLC 110 cannot detect certain power levels or activation states (such as power rack 155), or when PLC 110 cannot detect the power harness from harness detection sensor 190.

[0074] Once PLC 110 is in any of states 250-280, it may be prohibited from transitioning back to normal state 220 until commanded to by controller 120 or a human operator.

[0075] Now referring to EIG. 4, exemplary sensor inputs 400 to PLC 110 are described. These inputs 400 may be sensor signals, readings, data packets, or similar indications of at least one physical property associated with the tank that sensors may be configured to monitor. Inputs 400 may indicate physical properties of any element of system 100a, system 100b, tank 102 or immersion cooling processes being controlled by or performed in an appropriate element of the foregoing. PLC 110 may receive readings of immersion cooling liquid 104 fluid level from level switch low 410, level switch low 411, level switch medium (med) 412, level switch med 413, level switch high 414, and level switch high 415. Pressure in headspace 108 may be monitored and reported to PLC 110 from headspace total pressure 422 and headspace total pressure 424. PLC 110 may receive inlet water pressure as inlet water pressure input 426 and outlet water pressure from outlet water pressure input 428. Relatively humidity in headspace 108 may be indicated by headspace relative humidity input 430 and 432. Eilter flow input 440 may indicate the flow rate through filter 175, for example as input from a flow rate sensor, a pressure sensor at a filter inlet or outlet, or current sensor measuring an electrical current drawn by a pump that is forcing immersion cooling liquid 104 through filter 175. Lid open input 450 may give an indication of the open or closed state of lid 103. PSU health monitoring inputs 460, 462, 464, and 466 indicate the operational health of PSUs 1-4 and may provide an indication of the availabilityof power for computing hardware immersed in immersion cooling liquid 104. PLC fan health input 468 may indicate a status or health of a fan used to cool PLC 110 and ensure that the PLC maintains a satisfactory operating temperature. PLC 110 may use input from PLC fan health input 468 in concert with PLC cabinet temperature input 482 to determine if service needs to be provided to the PLC 110 or any housing in which it is contained. Busbar voltage inputs 474 and 476 may indicate a voltage on busbar 172. ESTOP sense 484 may provide an indication of whether or not an emergency stop button such as E-Stop button 188 has been pressed and the power to system 100a, system 100b, tank 102, or other related equipment should be cut. Power enable sense 486 may indicate whether or not power from power rack 155 is being delivered to tank 102, system 100a, or system 100b. Harness detection line input 490 may provide an indication of whether or not PLC 110 is communicatively coupled to power rack 155. Breaker state R1-R4 / L1-L4 input 494 may provide an indication of whether the breakers within circuit breaker panel 193 are in an electrically open or closed state.

[0076] FIG. 5 depicts aspects of an immersion-cooling system 560 for dissipating heat from one or more semiconductor die packages 505 via immersion cooling. Each package 505 can include one or more semiconductor dies that produce heat when the system is in operation. The immersion-cooling system 560 in the illustrated example of FIG. 5 is a two-phase immersion-cooling system, though the invention can also be implemented in a single-phase immersion-cooling system.

[0077] The immersion-cooling system 560 includes a tank 507 filled, at least in part, with coolant liquid 564. The immersion-cooling system 560 can further include at least one chiller 580 that flows a heat-transfer fluid through at least one condenser coil 570 that is disposed in the tank 507 and headspace 508. The packages 505 can be mounted on one or more printed circuit boards (PCBs) 557 that are immersed, at least in part, in the coolant liquid 564. Immersioncooling system 560 may further include a filter 575 disposed within or adjacent to the tank 507.

[0078] Filter 575 may include a pump, a housing, and filtration media configured to force coolant liquid 564 through filter 575 to remove contaminants, particulates, or other impurities that may be added to coolant liquid 564 during use. Filter 575 may be fully submerged within coolant liquid 564. In such an embodiment, the entirety of a pump, housing, and filtration media are completely immersed in coolant liquid 564. Alternatively, filter 575 may be housed outside of tank 507 while being in fluidic communication with coolant liquid 564 in tank 507.

[0079] Coolant liquid 564 may be a hydrocarbon, a fluoroketone, an oil, or a similar dielectric liquid that will act as an insulator while simultaneously transferring heat from package 505 more efficiently than air. An example of cooling liquid 564 is Novec™ 649 produced by 3M™. An exemplary coolant liquid 564 used in accordance with embodiments of the present invention may have a dielectric constant baseline value of about 1.8-2 at a frequency of about 1 kHz.

[0080] In an embodiment of the invention, coolant liquid 564 may be considered unacceptably contaminated if the dielectric constant and / or dielectric loss tangent of coolant being used in an immersion-cooling system 560 differs by a threshold amount as compared to unused or pure coolant liquid 564. For example, coolant liquid 564 may be considered unacceptably contaminated or degraded if the dielectric constant and / or dielectric loss tangent differs by a threshold of 10% or more as compared to unused or pure coolant liquid 564. In an embodiment, a dielectric constant and / or dielectric loss tangent variation threshold may be 20%, 15%, 5%, 3%, 1%, or any suitable threshold.

[0081] Contamination of the coolant liquid 564 and resulting changes to dielectric constant and / or dielectric loss tangent may alter or negatively impact operation of components within coolant liquid 564 including semiconductor die(s) 550. An altered dielectric constant and / or dielectric loss tangent may result in undesirable cross-talk between components on a PCB, additional noise or reduction in signal strength transmitted along exposed wires of a PCB or semiconductor die(s) 550 submerged in immersion fluid, and / or signal dissipation through the coolant liquid 564. Signal loss may be severe enough that two elements may be effectively represented as being separated by an open circuit despite being physically connected. In an embodiment, a dielectric constant and / or dielectric loss tangent variation threshold may be selected based on an observed or inferred effect on one or more submerged semiconductor die(s) 550. For example, an increase in PCIe bit error rate above an error rate baseline may be correlated with an increase in dielectric constant and / or dielectric loss tangent above a dielectric constant and / or dielectric loss tangent baseline. Accordingly, operation of semiconductor die(s) 550 may be throttled or suspended when a dielectric constant and / or dielectric loss tangent of coolant liquid 564 exceeds a predetermined threshold.

[0082] Changes to dielectric constant and / or dielectric loss tangent may be caused by contaminants within coolant liquid 564. In some cases, changes to dielectric constant and / or dielectric loss tangent may be reversed by filtering the contaminants from coolant liquid 564. In some embodiments, upon detecting an increase in dielectric constant and / or dielectric losstangent of coolant liquid 564, controller 502 may instruct filter 575 to increase filtration throughput or notify a user that a coolant liquid 564 filtration media may need to be replaced. If a dielectric constant and / or dielectric loss tangent exceeds a predetermined threshold, controller 502 may throttle or shut down one or more semiconductor die(s) 550, generate a notification that coolant liquid 564 should be replaced, trigger an alarm, etc.

[0083] The illustrated example of FIG. 5 is not intended to be to scale. The immersioncooling system 560 may house and provide coolant liquid 564 to tens, hundreds, or even thousands of packages 505. In some cases, the immersion-cooling system 560 can be small (e.g., the size of a floor unit air conditioner, approximately 1 meter high, 0.5 meter width, 0.5 meter depth or length). In some implementations, the immersion-cooling system can be large (e.g., the size of a van or larger, approximately 2.5 meters high, 2.5 meters width, 4 meters depth or length).

[0084] The immersion-cooling system 560 can also include a controller 502 (e.g., a microcontroller, programmable logic controller, microprocessor, field-programmable gate array, logic circuitry, memory, or some combination thereof) to manage system operation. The controller 502 can perform various system functions such as monitoring temperatures of system components, coolant liquid fluid level, tank access, chiller operation etc. The controller 502 can further issue commands to control system operation such as executing a start-up sequence, executing a shut-down sequence, assigning workloads among the packages, changing coolant liquid fluid level, changing the temperature of the heat-transfer fluid circulated by the chiller 580, etc. In some implementations, the controller 502 can include (or itself be) a baseboard management controller (BMC) 504. That is, the BMC 504 may monitor and control all aspects of system operation for the immersion-cooling system 560 in addition to monitoring and controlling workloads of the semiconductor dies 550 in the packages 505 cooled by the system. The immersion-cooling system 560 can also include a network interface controller (NIC) 503 to allow the system to communicate over a network, such as a local area network or wide area network. The immersion-cooling system 560 can further include a fluid sensor array 590 having a plurality of fluid sensors 510.

[0085] The semiconductor die(s) 550 and can be mounted on and attached to a printed circuit board (PCB) 555 (sometimes referred to as a substrate) in the device package 505. The package 505 can be made commercially available as an off-the-shelf (OTS) product. The package 505 can be used for single-phase or two-phase immersion cooling of at least one semiconductor die 550, such as a microprocessor (e.g., a central processing unit (CPU) and / orgraphic processing unit (GPU)), voltage regulator (VR), high bandwidth memory (HBM), a digital signal processing (DSP) die, an application-specific integrated circuit (ASIC), field- programmable gate array (FPGA), and / or other densely patterned semiconductor die.

[0086] In the two-phase immersion-cooling system 560 of FIG. 5, heat flows from the semiconductor die 550 where it is generated into the heat spreader 552. The heat spreader 552 is in thermal contact with a coolant liquid 564 that can flow over and extract heat from the heat spreader 552. The amount of heat delivered by the heat spreader 552 to the coolant liquid 564 is enough to boil the coolant liquid 564 that contacts the heat spreader 552 (creating bubbles 565 and potentially creating froth 567 when bubbles 565 reach the surface of coolant liquid 564). The vapor 566 from the boiled coolant liquid 564 can be cooled and condensed back to liquid droplets 568, for example, by the condenser coil 570. The heat-transfer fluid, such as chilled water, from the chiller 580 can be circulated through the condenser coil 570 to lower the temperature of the condenser coil 570 below the condensation point in the headspace 508 of the tank 507. As a result, the vapor 566 condenses on exterior surfaces of the condenser coil 570 and liquid droplets 568 from the condensed vapor can drip and / or flow back to the coolant liquid 564. Although a single condenser coil 570 is depicted in FIG. 5, there can be a plurality of condenser coils 570 in the tank 507 to condense the vapor 566 into droplets. Some or all of the condenser coils 570 may or may not be located directly over the PCBs 557. Instead, the condenser coil(s) 570 can be located near one or more walls of the tank 507, such that the condenser coil(s) 570 are not directly over the PCBs 557 on which the packages 505 are mounted.

[0087] To improve thermal performance in two-phase immersion-cooling system 560, the heat spreader 552 can include a boiling enhancement coating (BEC) on at least one surface. The BEC can be formed from copper or a copper alloy and can be porous, for example, though BECs can take various forms. In some cases, the BEC is a micro porous copper coating having a thickness from approximately or exactly 50 microns to 500 microns thick (which may be produced by electroplating and / or etching). In some implementations, the BEC comprises a mesh copper layer bonded (e.g., via resistance heating) to at least an outer surface of the heat spreader 552. In some cases, the BEC is applied as particulates to at least one smooth surface of the heat spreader 552 and then subsequently sintered to adhere to one another and to the heat spreader 552. The BEC provides an improved surface area to contact the coolant liquid 564 and can increase the heat transfer coefficient from the heat spreader 552 to the coolant liquid 564 byup to a factor of 15 versus a smooth surface on the heat spreader 552. Accordingly, BECs can increase thermal conductivity to, and accelerate the boiling of, the coolant liquid 564.

[0088] FIG. 6 is a flowchart of an example method 600 for operating an immersion cooling tank, the method comprising steps 610 and 620 as follows:

[0089] At step 610, receiving, by a programmable logic controller (PLC), an indication of a physical property associated with the immersion cooling tank from at least one sensor.

[0090] At step 620, altering, by a second controller, the physical property in response to a change in state of the PLC.

[0091] FIG. 7 is a flowchart of an example method 700 for controlling an immersion cooling process, the method comprising steps 710 and 720 as follows:

[0092] At step 710, receiving, by a programmable logic controller (PLC), an indication of a physical property associated with the immersion cooling process from at least one sensor.

[0093] At step 720, altering, by a second controller, the physical property in response to a change in state of the PLC.

[0094] FIG. 8 is a flowchart of an example method 800 for operating an immersion cooling tank, the method comprising steps 810-830 as follows:

[0095] At step 810, receiving, by a first controller, a current state of a programmable logic controller (PLC) of a plurality of PLC states, the plurality of PLC states comprising one or more of a normal PLC state, a power off PLC state, an open PLC state, or a throttled PLC state.

[0096] At step 820, sending, by the first controller, a signal to alter a physical property associated with the immersion cooling tank in response to determining the PLC is not in the normal PLC state.

[0097] At step 830, receiving, by the PLC, an indication of a new PLC state.CONCLUSION

[0098] While various inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and / or structures for performing the function and / or obtaining the results and / or one or more of the advantages described herein, and each of such variations and / or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the artwill readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and / or configurations will depend upon the specific application or applications for which the inventive teachings is / are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and / or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and / or methods, if such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure.

[0099] Also, various inventive concepts may be embodied as one or more methods, of which an example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.

[0100] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0101] The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”

[0102] The phrase “and / or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and / or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and / or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionallyincluding elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[0103] As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of’ or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law.

[0104] As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and / or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0105] In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of’ and “consisting essentially of’ shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

Claims

CLAIMS1. A system for immersion cooling, the system comprising: at least one sensor configured to monitor a physical property associated with an immersion cooling tank; a programmable logic controller (PLC) communicatively coupled to the at least one sensor; and a second controller communicatively coupled to the PLC and configured to alter the physical property in response to a change in state of the PLC.

2. A system for immersion cooling, the system comprising: at least one sensor configured to monitor a physical property associated with an immersion cooling process; a programmable logic controller (PLC) communicatively coupled to the at least one sensor; and a second controller communicatively coupled to the PLC and configured to alter the physical property in response to a change in state of the PLC.

3. A method for operating an immersion cooling tank, the method comprising: receiving, by a programmable logic controller (PLC), an indication of a physical property associated with the immersion cooling tank from at least one sensor; and altering, by a second controller, the physical property in response to a change in state of the PLC.

4. A method for operating an immersion cooling tank, the method comprising: receiving, by a second controller, a current state of a programmable logic controller(PLC) of a plurality of PLC states, the plurality of PLC states comprising one or more of a normal PLC state, a power off PLC state, an open PLC state, or a throttled PLC state; sending, by the second controller, a signal to alter a physical property associated with the immersion cooling tank in response to determining the PLC is not in the normal PLC state; and receiving, by the PLC, an indication of a new PLC state.

5. A method for controlling an immersion cooling process, the method comprising: receiving, by a programmable logic controller (PLC), an indication of a physical property associated with the immersion cooling process from at least one sensor; and altering, by a second controller, the physical property in response to a change in state of the PLC.

6. The system of any one of claims 1 or 2, wherein the physical property comprises at least one of a pressure, a temperature, a voltage, an electrical current, a humidity, a flow rate, or a fluid level.

7. The method of any one of claims 3-5, wherein the physical property comprises at least one of a pressure, a temperature, a voltage, an electrical current, a humidity, a flow rate, or a fluid level.

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