Optical sensor for measuring liquid level of two-phase cooling steam

Abstract

An immersion cooling system includes an immersion tank defining an immersion chamber therein, an immersion working fluid, an energy source, an optical sensor, and a microcontroller. The immersion working fluid is at least partially located in the immersion chamber, and the immersion working fluid has a liquid phase and a gas phase. An energy source is positioned and oriented to direct an infrared beam through a portion of the gas phase using a beam path and a path length. An optical sensor is located in the beam path. The microcontroller is configured to determine a vapor concentration in the immersion chamber based at least in part on data from the path length, the optical sensor, and the energy source.

Description

Background Art

[0001] Computing devices generate a lot of heat during use. Immersion cooling allows the temperature of computing devices and components to be regulated by an immersion fluid. In two-phase immersion cooling, a portion of the immersion working fluid is vaporized by the heat generated by the computing device. Rapid changes in vapor pressure in an immersion cooling system can be caused by sudden changes in power consumption and heat generation of computing devices. Summary of the invention

[0002] In some embodiments, an immersion cooling system includes an immersion tank having an immersion chamber defined therein, an immersion working fluid, an energy source, an optical sensor, and a microcontroller. The immersion working fluid is at least partially located in the immersion chamber, and the immersion working fluid has a liquid phase and a vapor phase. The energy source is positioned and oriented to direct an infrared beam through a portion of the vapor phase using a beam path and a path length. The optical sensor is located in the beam path. The microcontroller is configured to determine a vapor concentration in the immersion chamber based at least in part on data from the path length, the optical sensor, and the energy source.

[0003] In some embodiments, an immersion cooling system includes an immersion tank having an immersion chamber defined therein, an immersion working fluid, an energy source, a first optical sensor, an optical element, a second optical sensor, and a microcontroller. The immersion working fluid is at least partially located in the immersion chamber, and the immersion working fluid has a liquid phase and a gas phase. The energy source is positioned and oriented to direct an infrared beam through a portion of the gas phase using a beam path and a path length. The first optical sensor is positioned and oriented to direct a first infrared beam through a first portion of the gas phase using a first beam path and a first path length. The optical element is configured to direct at least a portion of the first infrared beam through a second portion of the gas phase using a second beam path and a second path length. The second optical sensor is positioned in the second beam path. The microcontroller is configured to determine a vapor concentration in the immersion chamber based at least in part on data from the first path length, the first optical sensor, the second path length, the second optical sensor, and the energy source.

[0004] In some embodiments, a method of measuring vapor concentration in an immersion cooling system includes positioning a sample portion of an immersion working fluid in a sampling region between an energy source and an optical sensor, providing a beam path and a path length for an infrared beam passing through the sample portion, receiving a transmitted portion of the infrared beam with the optical sensor, measuring an intensity of the transmitted portion relative to a source portion of the infrared beam, and determining a concentration of a vapor phase of the immersion working fluid in the sample portion.

[0005] This summary is provided to introduce a series of concepts in a simplified form, which are further described in the detailed description below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0006] Additional features and advantages will be set forth in the following description, and in part will be apparent from the description, or may be learned by practice of the teachings herein. The features and advantages of the present disclosure may be realized and obtained by the instruments and combinations particularly pointed out in the appended claims. The features of the present disclosure may become more apparent from the following description and the appended claims, or may be learned by practice of the present disclosure as described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order to describe the manner in which the above and other features of the present disclosure may be obtained, a more specific description will be given with reference to the specific embodiments shown in the accompanying drawings. For better understanding, the same elements are represented by the same reference numerals in the various drawings. Although some of the drawings may be schematic or exaggerated representations of concepts, at least some of the drawings may be drawn to scale. It is understood that the drawings depict some example embodiments, and the embodiments will be described and explained with additional specificity and detail through the use of the drawings, in which:

[0008] Figure 1 is a schematic diagram of an immersion cooling system according to at least one embodiment of the present disclosure;

[0009] Figure 2 is a schematic diagram of an immersion cooling system with an external condenser according to at least one embodiment of the present disclosure;

[0010] Figure 3 is an electrical diagram of an optical sensor for measuring vapor concentration according to at least one embodiment of the present disclosure;

[0011] Figure 4 According to at least one embodiment of the present disclosure, Figure 3 Example absorption spectra of immersed working fluids measured by an optical sensor;

[0012] Figure 5 is a schematic diagram of a machine learning model according to at least one embodiment of the present disclosure;

[0013] Figure 6 is a schematic diagram of an immersion cooling system with a vertical optical sensor according to at least one embodiment of the present disclosure;

[0014] Figure 7 is a side view of an optical sensor including multiple beam paths according to at least one embodiment of the present disclosure;

[0015] Figure 8 is a schematic diagram of an immersion cooling system with a diagonal optical sensor according to at least one embodiment of the present disclosure;

[0016] Fig. 9 is a flow chart illustrating a method of measuring vapor concentration in an immersion cooling system according to at least one embodiment of the present disclosure; and

[0017] Fig.10 is a schematic diagram of an immersion cooling system with a pressure remediation feature in accordance with at least one embodiment of the present disclosure. DETAILED DESCRIPTION

[0018] The present disclosure generally relates to systems and methods for thermal management of electronic devices or other heat generating components. More specifically, the present disclosure relates to systems and methods for detecting pressure changes in immersion cooling systems. For example, immersion cooling systems use an immersion working fluid that receives heat from computing devices, electronic components, and other heat generating components. The immersion working fluid then transfers the heat to a heat exchanger to remove the heat from the immersion cooling system.

[0019] In some examples, the amount of heat generated by the computing device changes faster than the heat exchanger can compensate for. More specifically, an increase in vaporization of the immersion working fluid near or in contact with a heat generating component of the computing device can cause an associated increase in pressure in the immersion cooling system before the heat exchanger or condenser can reject the heat and condense the vapor phase of the immersion working fluid back to the liquid phase of the immersion working fluid. Similarly, a decrease in vaporization of the immersion working fluid near or in contact with a heat generating component of the computing device can cause an associated decrease in pressure in the immersion cooling system because the heat exchanger or condenser continues to condense the vapor phase of the immersion working fluid back to the liquid phase of the immersion working fluid after the vaporization rate decreases.

[0020] One or more sensors and / or control services according to the present disclosure may measure changes in vapor concentration in a headspace of an immersion chamber or another portion of an immersion cooling system. The vapor level in the headspace and / or vapor concentration in the headspace is a leading indicator before a substantial pressure change occurs in the immersion cooling system. Conventional immersion tanks and conduits of immersion cooling systems are constructed to withstand pressure differentials between the immersion cooling system and the ambient atmosphere. By more quickly predicting and responding to pressure changes in an immersion cooling system, the reliability and / or service life of the immersion cooling system may be improved.

[0021] In some embodiments, the immersed working fluid is a two-phase working fluid that receives heat from the heat generating component by evaporation. For example, an immersion chamber surrounds the heat generating component in a liquid working fluid that conducts heat from the heat generating component to cool the heat generating component. As the working fluid absorbs heat from the heat generating component, the temperature of the working fluid increases. In some embodiments, the hot working fluid can be circulated through a thermal management system to cool the working fluid and / or replace the working fluid with a cold working fluid. In some embodiments, the working fluid vaporizes, introducing vapor into the liquid of the working fluid rising from the liquid phase, and taking away heat energy from the heat generating component in the vapor phase via the latent heat of vaporization.

[0022] In large computing centers (such as cloud computing centers, data processing centers, data storage centers, or other computing facilities), immersion cooling systems provide an efficient thermal management method for many computing components under various operating loads. In some embodiments, the immersion cooling system includes a working fluid in an immersion chamber and a heat exchanger for cooling the liquid phase and / or a condenser for extracting heat from the gas phase of the working fluid. The heat exchanger may include a condenser that condenses the gas phase of the working fluid into a liquid phase and returns the liquid working fluid to the immersion chamber. In some embodiments, the liquid working fluid absorbs heat from the heat generating components, and one or more fluid conduits direct the hot liquid working fluid outside the immersion chamber to a radiator, a heat exchanger, or an area of ​​lower temperature to cool the liquid working fluid.

[0023] In some embodiments, the computing devices or systems assigned to the immersion cooling system and / or the high computing applications executed thereon require extensive thermal management. Thus, the phase change from liquid to vapor allows the working fluid to absorb a relatively large amount of heat with a slight associated increase in temperature. Additionally, the lower density allows for efficient removal of vapor from the immersion bath to remove the associated heat from the system.

[0024] In some embodiments, the thermal management system includes an immersion tank having an immersion chamber defined therein. The two-phase working fluid receives heat from a heat generating component immersed in the liquid working fluid, and the heat vaporizes the working fluid, causing the working fluid to change from a liquid phase to a vapor phase. The thermal management system includes a condenser for condensing the vapor working fluid back to a liquid phase, such as described herein. In some embodiments, the condenser is in fluid communication with the immersion tank via one or more conduits. In some embodiments, the condenser is positioned within the immersion tank.

[0025] like Figure 1As shown, a conventional immersion cooling system 100 includes an immersion tank 102 containing an immersion chamber 104 and a condenser 106 in the immersion chamber 104. The immersion chamber 104 contains an immersion working fluid having a liquid working fluid 108 and a vapor working fluid 110 portion. The liquid working fluid 108 forms an immersion bath 112 in which a plurality of heat generating components 114 are positioned to heat the liquid working fluid 108 on a support 116.

[0026] Reference now Figure 2 In some embodiments, the immersion cooling system 200 includes an immersion tank 202 defining an immersion chamber 204 in which an immersion working fluid is positioned. The immersion working fluid in the immersion tank 202 has a boiling temperature selected at least in part based on one or more operating characteristics of the immersion cooling system, electronic components and / or computing devices in the immersion tank 202, computational or workload of the electronic components and / or computing devices in the immersion tank 202, external and / or environmental conditions, or other characteristics that affect the operation of the immersion cooling system 200.

[0027] In some embodiments, the immersion working fluid transitions between a liquid working fluid 208 phase and a vapor working fluid 210 phase to remove heat from a heat or heat generating component 214 in the immersion chamber 204. The liquid working fluid 208 more efficiently receives heat from the heat generating component 214, and upon transitioning to the vapor working fluid 210, the vapor working fluid 210 can be withdrawn from the immersion tank 202, cooled and condensed by the condenser 206 (or other heat exchanger) to extract heat from the working fluid, and the liquid working fluid 208 can be returned to the liquid immersion bath 212.

[0028] In some embodiments, the bath 212 of the liquid working fluid 208 has a plurality of heat generating components 214 located in the liquid working fluid 208. The liquid working fluid 208 surrounds at least a portion of the heat generating components 214 and other objects or components attached to the heat generating components 214. In some embodiments, the heat generating components 214 are located in the liquid working fluid 208 on one or more supports 216. The supports 216 can support the one or more heat generating components 214 in the liquid working fluid 208 and allow the working fluid to move around the heat generating components 214. In some embodiments, the supports 216 are thermally conductive to conduct heat from the heat generating components 214. The support(s) 216 can increase the effective surface area from which the liquid working fluid 208 can remove heat by convection cooling.

[0029] In some embodiments, the heat generating component 214 includes an electronic component or a computing component or a power supply. In some embodiments, the heat generating component 214 includes a computer device, such as a personal computer or a server blade computer. In some embodiments, one or more heat generating components 214 include a heat sink or other device attached to the heat generating component 214 to conduct away heat energy and effectively increase the surface area of ​​the heat generating component 214. In some embodiments, the heat sink of the heat generating component 214 is a steam chamber having one or more three-dimensional structures to increase the surface area.

[0030] As described above, converting the liquid working fluid 208 to the vapor phase requires input of thermal energy to overcome the latent heat of vaporization, and this can be an effective mechanism for increasing the heat capacity of the working fluid and removing heat from the heat generating components 214. Because the vapor working fluid 210 rises in the liquid working fluid 208, the vapor working fluid 210 can be extracted from the immersion chamber 204 in the upper vapor region of the chamber. The condenser 206 cools a portion of the vapor working fluid 210 back into the liquid working fluid 208 to remove thermal energy from the system, and reintroduces the working fluid into the bath 212 of liquid working fluid 208. The condenser 206 radiates or otherwise dumps the thermal energy from the working fluid into the surrounding environment or into a conduit to remove thermal energy from the cooling system.

[0031] In some embodiments of the immersion cooling system, a liquid-cooled condenser is integrated into the immersion tank and / or chamber to efficiently remove thermal energy from the working fluid. In some embodiments, the immersion cooling system 200 for thermal management of a computing device allows at least one immersion tank 202 and / or chamber 204 to be connected to and in fluid communication with an external condenser 206. In some embodiments, the immersion cooling system 200 includes a vapor return line 218 that connects the immersion tank 202 to the condenser 206 and allows the vapor working fluid 210 to enter the condenser 206 from the immersion tank 202 and / or chamber 204, and a liquid return conduit 220 that connects the immersion tank 202 to the cooler 206 and allows the liquid working fluid 208 to return to the immersion tank 202 or chamber 204.

[0032] The vapor return line 218 may be lower than the boiling temperature of the working fluid. In some embodiments, a portion of the vapor working fluid 210 condenses in the vapor return line 218. In some embodiments, the vapor return line 218 may be oriented at an angle such that the vapor return line 218 is not perpendicular to the direction of gravity. The condensed working fluid may then be discharged rearwardly to the immersion tank 202 or forwardly to the condenser 206, depending on the tilt direction of the vapor return line 218. In some embodiments, the vapor return line 218 includes a liquid collection line or valve, such as a bleed valve, that allows the condensed working fluid to be collected and / or returned to the immersion tank 202 or the condenser 206.

[0033] In some examples, the immersion cooling system 200 includes an air-cooled condenser 206. The air-cooled condenser 206 may require a fan or pump to force ambient air to flow through one or more heat pipes or fins to conduct heat from the condenser to the air. In some embodiments, the circulation of the immersion working fluid through the immersion cooling system 200 causes the liquid working fluid 208 to flow through one or more heat generating components 214. In the example of a heat generating component 214 having a vapor chamber heat sink, the dynamics of the liquid working fluid 208 can be used to move the vapor chamber working fluid within the vapor chamber and / or boiling of the immersion working fluid by the vapor chamber can drive the flow of the immersion working fluid.

[0034] In some embodiments, the liquid working fluid receives heat in a cooling volume of the working fluid in close proximity to the heat generating component. The cooling volume is the area of ​​the working fluid (including liquid and gas phases) that directly surrounds the heat generating component and is responsible for convective cooling of the heat generating component. In some embodiments, the cooling volume is the volume of the working fluid within 5 millimeters (mm) of the heat generating component.

[0035] The immersion working fluid has a boiling point temperature lower than the critical temperature at which the heat generating component is thermally damaged. The immersion working fluid can thereby receive heat from the heat generating component to cool the heat generating component before the heat generating component is damaged.

[0036] For example, the heat generating component can be a computing component that is damaged above 100° Celsius (C). In some embodiments, the boiling temperature of the immersion working fluid is lower than the critical temperature of the heat generating component. In some embodiments, the boiling temperature of the immersion working fluid is less than about 90°C at 1 atmosphere. In some embodiments, the boiling temperature of the immersion working fluid is less than about 80°C at 1 atmosphere. In some embodiments, the boiling temperature of the immersion working fluid is less than about 70°C at 1 atmosphere. In some embodiments, the boiling temperature of the immersion working fluid is less than about 60°C at 1 atmosphere. In some embodiments, the boiling temperature of the immersion working fluid is at least about 35°C at 1 atmosphere. In some embodiments, the working fluid comprises water.

[0037] In some embodiments, the working fluid comprises ethylene glycol. In some embodiments, the working fluid comprises a combination of water and ethylene glycol. In some embodiments, the working fluid comprises an aqueous solution. In some embodiments, the working fluid comprises an electronic liquid, such as FK-649 vapor, or a similar non-conductive fluid. In some embodiments, a heat generating component, a support, or other element of an immersion cooling system positioned in the working fluid has nucleation sites on its surface that promote the nucleation of vapor bubbles of the working fluid at or below the boiling temperature of the working fluid. It should be understood that although the present disclosure will describe the use of the sensor with the FK-649 two-phase immersed working fluid, the systems and methods described herein are applicable to other immersed working fluids.

[0038] In some embodiments, sensors according to the present disclosure detect and / or measure the presence of a vapor phase of one or more immersion working fluids in an immersion cooling system. In some embodiments, the immersion working fluid is a two-phase working fluid that boils during operation of the immersion cooling system. In some embodiments, the immersion working fluid has a vapor phase that is heavier than other gases in the immersion chamber, and the vapor phase of the immersion working fluid can settle toward a boundary of a liquid phase of the immersion working fluid. The vapor level in the headspace of the immersion chamber can be used to measure the amount of change or rate of change of the amount of vapor working fluid in the immersion chamber.

[0039] Figure 3 is a schematic diagram of an optical system 324 for measuring vapor concentration in a sample portion of a headspace or other region of an immersion cooling system. The optical system includes an energy source 326, such as a pulse width modulation (PWM) driver, that provides an infrared beam 328. For example, the infrared beam 328 can have a spectrum, at least a portion of which is in the IR range. In some examples, the infrared beam 328 can have a spectrum with a peak wavelength in the IR range. In at least one example, the infrared beam 328 can have a spectrum with a peak wavelength at 8 microns or between 7500 nanometers (nm) and 8500 nm.

[0040] The infrared beam 328 is provided to a vapor sample portion 330 of the vapor working fluid, and the vapor sample portion 330 absorbs at least a portion of the infrared beam such that a transmitted portion 331 of the infrared beam is transmitted through the vapor sample portion 330. An optical sensor 332 receives the transmitted portion to measure at least one property of the transmitted portion 331, such as an intensity of the transmitted portion 331. The optical sensor 332 provides at least one measurement to a microcontroller 338 to record and / or interpret the measurement.

[0041] In some embodiments, infrared beam 328 can be directed by energy source 326 toward optical sensor 332. In other embodiments, at least one optical element is located in the beam path of infrared beam 328 (e.g., in transmission portion 331) to change the direction of infrared beam 328 toward optical sensor 332. For example, grating 334, a reflector, a beam splitter, or other optical element can direct infrared beam 328 toward optical sensor 332. In at least one embodiment, grating 334 directs a first portion of infrared beam 328 toward optical sensor 332 and a second portion of infrared beam 328 toward reference sensor 336. For example, grating 334 splits infrared beam 328 into a first portion having a first wavelength (which can be at or near an absorption peak of the vapor working fluid) and a second portion of the infrared beam having a second wavelength that is not strongly absorbed by the vapor working fluid in vapor sample portion 330. The difference between the measurement at optical sensor 332 and the measurement at reference sensor 336 can allow microcontroller 338 to normalize the measurement at optical sensor 332.

[0042] In some embodiments, the signal conditioner 340 is positioned between the optical sensor 332 and the microcontroller 338. In some embodiments, the signal conditioner 340 is positioned between the reference sensor 336 and the microcontroller 338. In some embodiments, the signal conditioner 340 receives information from both the optical sensor 332 and the reference sensor 336 before transmitting the measurements from the optical sensor 332 and the reference sensor 336 to the microcontroller 338.

[0043] In some embodiments, the microcontroller 338 also controls the energy source 326, such as providing a PWM signal to a PWM driver of the energy source 326 to control the infrared beam emission. The emission spectrum of the energy source 326 can be related to the source temperature of the energy source, and the energy source 326 can include or be coupled to a resistor / temperature sensor 342 to control and measure the source temperature of the energy source 326. The resistor / temperature sensor 342 can communicate with the microcontroller 338 to allow the microcontroller 338 to control the source temperature of the energy source 326 and receive information related to the source temperature of the energy source 326 during the emission of the infrared beam 328.

[0044] In some embodiments, the resistor / temperature sensor 342 maintains the source temperature at no less than 90°C. In some embodiments, the resistor / temperature sensor 342 maintains the source temperature at approximately 93°C. In some embodiments, the resistor / temperature sensor 342 maintains the source temperature at least 30°C above the boiling temperature of the immersion working fluid. In some embodiments, the resistor / temperature sensor 342 maintains the source temperature at least 40°C above the boiling temperature of the immersion working fluid. The temperature difference between the liquid phase of the immersion working fluid and the source temperature reduces noise and / or interference from the heat of the immersion working fluid at the optical sensor.

[0045] As described herein, it may be beneficial to provide an infrared light beam having a peak wavelength at or near the peak absorption of the vapor working fluid to increase the contrast of the vapor working fluid absorption signal. Figure 4 44 is an example absorption spectrum 444 of a vapor phase of an immersion working fluid such as FK-649. In some embodiments, the peak absorption wavelength 446 of the vapor working fluid is approximately 8 microns. In some embodiments, the energy source emits an infrared beam including energy in the 8 micron range. In at least one embodiment, the energy source emits an infrared beam having a peak emission wavelength of 8 microns or between 7500 nanometers (nm) and 8500 nm. The optical sensor is sensitive to infrared energy at or near 8 microns (e.g., between 7500 nm and 8500 nm) to receive a transmitted portion of the infrared beam. The microcontroller can compare at least one property (e.g., intensity) of the transmitted portion of the infrared beam received at the optical sensor with a known value of at least one property of the source portion of the infrared beam provided by the energy source.

[0046] In some embodiments, multiple values ​​of at least one property of the transmissive portion and the source portion of the infrared beam are provided to the microcontroller. In some embodiments, multiple values ​​are captured over time to track and / or correlate the values ​​of at least one property of the transmissive portion and the source portion relative to vapor level / concentration. A machine learning (ML) model can be trained based on known vapor levels and / or vapor concentrations of one or more vapor working fluids to allow the ML model to identify or calculate pressure changes based at least in part on vapor level, vapor concentration, rate of change of vapor level or concentration, or a combination thereof.

[0047] Figure 5It is a schematic diagram of an ML model that can be used with one or more embodiments of the systems and methods described herein. As used herein, a "machine learning model" refers to a computer algorithm or model (e.g., a classification model, a regression model, a language model, an object detection model) that can be adjusted (e.g., trained) based on a training input to approximate an unknown function. For example, an ML model can refer to a neural network or other machine learning algorithm or architecture that learns and approximates complex functions and generates outputs based on multiple inputs provided to the machine learning model. In some embodiments, the ML system, model, or neural network described herein is an artificial neural network. In some embodiments, the ML system, model, or neural network described herein is a convolutional neural network. In at least one embodiment, the ML system, model, or neural network described herein is a Bayesian classifier. As used herein, a "machine learning system" can refer to one or more ML models that collaboratively generate one or more outputs based on corresponding inputs. For example, an ML system can refer to any system architecture with multiple discrete ML components that take into account different types of information or inputs.

[0048] As used herein, an "instance" refers to an input object that can be provided as an input to an ML system for generating an output, such as the type of vapor working fluid present, the concentration of the vapor working fluid present, or the rate of change of the vapor working fluid present. For example, an instance can refer to any event in which a vapor working fluid is present. For example, a first absorption measurement or other measurement received at a microcontroller can be associated with the first vapor working fluid present in a sample portion of the vapor working fluid. In another example, a second absorption measurement or other measurement received at the microcontroller can be associated with a second vapor working fluid present in a sample portion of the immersion working fluid. In another example, a change in the absorption measurement or other measurement received at the microcontroller can be associated with an increase in the concentration of the vapor working fluid in the sample portion.

[0049] In some embodiments, the machine learning system has multiple layers having an input layer 548 and an output layer 558, the input layer 548 being configured to receive at least one input training data set 550 or input training instance 552, with multiple additional or hidden layers 556 therebetween. The training data set may be input into the ML system to train the ML system and identify individuals and combinations of vapor working fluids, or other properties of the training instances that allow the microcontroller to identify known or unknown concentrations of the vapor working fluid.

[0050] In some embodiments, the machine learning system may receive multiple training data sets concurrently and learn from different training data sets at the same time.

[0051] In some embodiments, the machine learning system includes multiple machine learning models operating together. Each machine learning model has multiple hidden layers between the input layer and the output layer. The hidden layer has multiple input nodes (e.g., node 560), each of which operates on the input received from the previous layer. In a specific example, the first hidden layer has multiple nodes, and each node performs an operation on each instance from the input layer. Each node of the first hidden layer provides a new input to each node of the second hidden layer, which in turn performs a new operation on each of these inputs. The nodes of the second hidden layer then pass the output (such as the identified cluster 562) to the output layer.

[0052] In some embodiments, each node 560 has a linear function and an activation function. The linear function can attempt to optimize or approximate a solution with a best fit line. The activation function serves as a test to check the validity of the linear function. In some embodiments, the activation function produces a binary output that determines whether the output of the linear function is passed to the next layer of the machine learning model. In this way, the machine learning system can limit and / or prevent the propagation of poor fits to the data and / or non-convergent solutions.

[0053] The machine learning model includes an input layer that receives at least one training data set. In some embodiments, at least one machine learning model uses supervised training. In some embodiments, at least one machine learning model uses unsupervised training. Unsupervised training can be used to infer and find patterns or associations from (multiple) training data sets without known outputs. In some embodiments, unsupervised learning can identify clusters of similar labels or features of various training instances and allow the machine learning system to infer the performance of instances with similar characteristics.

[0054] In some embodiments, semi-supervised learning can combine the advantages of supervised learning and unsupervised learning. As described herein, a machine learning system can identify relevant labels (such as known vapor working fluids or concentrations of vapor working fluids) or characteristics between instances, which can allow for the fusion of a training data set with known outputs and a second training data set including more general input information. Unsupervised training can allow a machine learning system to cluster instances in the second training data set without known outputs and associate the clusters with the known outputs of the first training data set.

[0055] Figure 6is a system diagram of an immersion cooling system 600 having an optical system 624 including at least an energy source 626 and an optical sensor 632 in communication with a microcontroller 638. In some embodiments, the optical system 624 has a substantially vertical beam path in a headspace 664 of the immersion chamber 604. A vapor working fluid 610 is located in the headspace 664 above the liquid working fluid 608.

[0056] In some embodiments, the headspace 664 includes air 666 or other gas and a vapor working fluid 610. As described herein, the vapor working fluid 610 can be heavier than the air 666 or other gas in the headspace 664. In some embodiments, the air / vapor interface 668 is not a well-defined boundary. For example, there can be a vapor concentration gradient that is highest at the interface with the liquid working fluid 608 and decreases as you ascend vertically above the liquid working fluid 608. A beam path through this gradient can measure a larger total path loss when higher vapor levels are present and a smaller total path loss when lower vapor levels are present.

[0057] For example, the vapor concentration level can be calculated using the Beer-Lambert law:

[0058] AεLc

[0059] where A = the energy absorbed by the substance at a specific wavelength; ε = the molar extinction coefficient or absorption coefficient of the substance at a specific wavelength; L = the path length of the energy through the substance; and c represents the concentration of the substance. Thus, for a thin cross section in the vertical direction:

[0060] dA=ε(dL)(dc / dL)

[0061] The total path loss is:

[0062] A=εL∫(dc / dL)

[0063] In some embodiments, multiple optical systems 624 located at different vertical positions in the head space 664 can be used to measure the vapor concentration in the head space using different beam paths and / or path lengths through the head space 664. In some embodiments, the optical system can include at least one optical element to create multiple beam paths with different beam lengths and / or different vertical positions in the head space.

[0064] Figure 77 is a side view of an embodiment of an optical system 724 having a beam splitter 770 that splits an infrared beam 728. In some embodiments, the optical system 724 includes an energy source 726 that includes a resistor 742 that provides the infrared beam 728 in a head space 764. The infrared beam 728 begins from a shared path 771 before the beam splitter 770 splits the beam path into a first beam path 772-1 toward a first optical sensor 732-1 and a second beam path 772-2 toward a second optical sensor 732-2. In some embodiments, the first beam path 772-1 and the second beam path 772-2 have different path lengths. In some embodiments, the first beam path 772-1 and the second beam path 772-2 have substantially equal path lengths.

[0065] In some embodiments, the shared path 771 and the first beam path 772-1 sample a first vertical portion 774 of the headspace 764, and the shared path 771 and the second beam path 772-2 sample a second vertical portion 776 of the headspace 764. For example, the first vertical portion 774 and the second vertical portion 776 are located at different vertical locations in the headspace 764. In some embodiments, the first vertical portion 774 and the second vertical portion 776 have different vertical lengths. In some embodiments, the first vertical portion 774 and the second vertical portion 776 have substantially equal vertical lengths.

[0066] The first optical sensor 732-1 and the second optical sensor 732-2 can provide one or more measurements to the microcontroller 738. In some embodiments, the microcontroller 738 can obtain or store information about the relative path lengths and / or positions of the shared path 771, the first beam path 772-1, and the second beam path 772-2. Thus, the microcontroller 738 can determine the vapor level in the head space 764.

[0067] Although the embodiments of the optical systems described herein have substantially vertical beam paths, in other embodiments, the beam paths may be oriented at other angles in the headspace to sample the vapor working fluid therein. For example, multiple optical systems (such as those described with respect to Figure 3 The optical system) can be oriented with a horizontal beam path and positioned at a series of discrete vertical positions to sample the vapor working fluid at a series of discrete vertical positions. In another example, the beam path can be oriented diagonally to increase the path length and increase the absorption of the infrared beam by the vapor working fluid. In other examples, the beam path can be directed through multiple optical elements (prisms, mirrors, etc.) to further extend the path length.

[0068] Figure 88 is a system diagram of one embodiment of an immersion cooling system 800 including an optical system 824 having a diagonal beam path 872. In some embodiments, the diagonal beam path 872 between the energy source 826 and the optical sensor 832 in communication with the microcontroller 838 (which may include a grating 834 or other optical element therebetween) may allow the infrared light beam 828 to experience greater attenuation when passing through the vapor working fluid 810 in the headspace 864 than a substantially perpendicular beam path.

[0069] Fig. 9 is a flow chart illustrating an embodiment of a method 978 for measuring vapor levels and / or concentrations in an immersion cooling system. The method 978 includes positioning a sample portion of an immersion working fluid in a sampling region between an energy source and an optical sensor at 980, and providing a beam path and a path length to an infrared beam passing through the sample portion at 982. The method 978 also includes receiving a transmitted portion of the infrared beam with the optical sensor at 984, and measuring an intensity of the transmitted portion relative to a source portion of the infrared beam at 986. In some embodiments, the energy source and / or the infrared beam is any energy source or infrared beam described herein. For example, the infrared beam can be an IR infrared beam.

[0070] In some embodiments, the source portion of the infrared beam is a portion of the infrared beam emitted from the energy source at a known intensity and / or wavelength near the energy source. The transmitted portion of the infrared beam is a portion of the infrared beam near the optical sensor that has at least a portion of the infrared beam absorbed and / or attenuated by the gas phase of the immersed working fluid in the sample portion.

[0071] The method 978 also includes determining the concentration of the gas phase of the immersion working fluid in the sample portion at 988. For example, determining the concentration can include providing the measured intensity to a microcontroller, and calculating the concentration with the microcontroller. In other examples, the concentration can be calculated elsewhere. In at least one example, the concentration is calculated at least in part based on Beer-Lambert. In at least one example, the concentration is determined by inputting the measured intensity into an ML system.

[0072] In some embodiments, method 978 optionally includes remediating the pressure of the gas phase in the immersion chamber at 990. For example, remediating the pressure of the gas phase may include automatically venting at least a portion of the vapor pressure of the immersion cooling system, such as from the immersion tank or via a vent in a condenser of the immersion cooling system (e.g., a remediation feature).

[0073] In another example, remediating the pressure of the gas phase can include automatically adding cold immersion working fluid (e.g., at least 1°C below the boiling temperature of the immersion working fluid) to the immersion cooling system, such as opening a valve to add cold immersion working fluid to the immersion cooling system to reduce the temperature of the liquid working fluid to reduce the vaporization rate of the immersion working fluid. In at least one embodiment, adding cold immersion working fluid to the immersion cooling system includes opening a valve to allow cold immersion working fluid to flow from a reservoir through the valve into the immersion cooling system. For example, the valve can be controlled by a microcontroller, and the microcontroller can open the valve based at least in part on the determined gas phase concentration.

[0074] In another example, remediating the pressure of the gas phase can include automatically replacing the hot immersion working fluid with a cool immersion working fluid (e.g., at or near the boiling temperature of the immersion working fluid). Replacing the hot immersion working fluid with the cool immersion working fluid can include opening at least a first valve to drain a portion of the hot immersion working fluid from the immersion cooling system, and opening at least a second valve to allow cool immersion working fluid to flow from the reservoir through the valve into the immersion cooling system. In at least one embodiment, the valve can be controlled by a microcontroller, and the microcontroller can open the valve based at least in part on the determined gas phase concentration.

[0075] Fig.10 1 is a system diagram of an immersion cooling system 1000 having an optical system 1024 in communication with one or more remediation features. For example, the immersion cooling system 1000 may include a reservoir 1092 containing a cold immersion working fluid 1094 and a collection tank 1096 configured to capture at least a portion of the hot liquid working fluid 1008. In some embodiments, the reservoir 1092 is connected to the return conduit 1020 or other inlet of the immersion chamber 1004 to introduce the cold immersion working fluid 1094 into the immersion chamber 1004. In other examples, the reservoir 1092 may be connected to the immersion chamber 1004 directly or through a dedicated conduit, or the reservoir 1092 may be connected to the condenser 1006 to deliver the cold immersion working fluid 1094 to the immersion cooling system 1000 via the condenser 1006.

[0076] In some embodiments, a first valve 1098 (e.g., a first remedial feature) controls the flow of cold submerged working fluid 1094 into the immersion cooling system 1000. The first valve 1098 may be controlled by the microcontroller 1038. In other embodiments, the first valve 1098 may be controlled by another control plane that receives vapor level and / or vapor concentration information from the microcontroller 1038.

[0077] The collection tank 1096 can be connected to the immersion cooling system 1000 through a second valve 1099 (e.g., a second remedial feature). In some embodiments, the collection tank 1096 is connected to the return conduit 1020 or other conduit of the immersion chamber 1004 to receive the hot liquid working fluid 1008 from the immersion chamber 1004. In other examples, the collection tank 1096 can be connected to the immersion chamber 1004 directly or through a dedicated conduit, or the collection tank 1096 can be connected to the condenser 1006 to receive the hot liquid working fluid 1008 from the immersion cooling system 1000 via the condenser 1006. Although Fig.10 One embodiment of an immersion cooling system 1000 is illustrated having a collection tank 1096 positioned and configured to receive a hot liquid working fluid 1008, but in some embodiments, the collection tank 1096 is positioned and configured to receive a vapor working fluid 1010 through a vent (e.g., a third remedial feature) that is connected to the immersion chamber, the condenser 1006, or another portion of the immersion cooling system 1000.

[0078] In some embodiments, the second valve 1099 controls the flow of the hot liquid working fluid 1008 from the immersion cooling system 1000. The second valve 1099 can be controlled by the microcontroller 1038. In other embodiments, the second valve 1099 can be controlled by another control plane that receives vapor level and / or vapor concentration information from the microcontroller 1038. In at least one embodiment, the microcontroller 1038 or other control plane at least partially simultaneously opens the first valve 1098 and the second valve 1099 (e.g., the time period during which the first valve 1098 is open at least partially overlaps the time period during which the second valve 1099 is open) to introduce the cold immersion working fluid 1094 from the reservoir 1092 into the immersion cooling system 1000 while moving at least a portion of the hot liquid working fluid 1008 into the collection tank 1096.

[0079] Industrial Applicability

[0080] The present disclosure generally relates to systems and methods for thermal management of electronic devices or other heat generating components. More specifically, the present disclosure relates to systems and methods for detecting pressure changes in immersion cooling systems. For example, immersion cooling systems use an immersion working fluid that receives heat from computing devices, electronic components, and other heat generating components. The immersion working fluid then transfers the heat to a heat exchanger to remove the heat from the immersion cooling system.

[0081] In some examples, the amount of heat generated by the computing device changes faster than the heat exchanger can compensate for. More specifically, an increase in vaporization of the immersion working fluid near or in contact with a heat generating component of the computing device can cause an associated increase in pressure in the immersion cooling system before the heat exchanger or condenser can reject the heat and condense the vapor phase of the immersion working fluid back to the liquid phase of the immersion working fluid. Similarly, a decrease in vaporization of the immersion working fluid near or in contact with a heat generating component of the computing device can cause an associated decrease in pressure in the immersion cooling system because the heat exchanger or condenser continues to condense the vapor phase of the immersion working fluid back to the liquid phase of the immersion working fluid after the vaporization rate decreases.

[0082] One or more sensors and / or control services according to the present disclosure may measure changes in vapor concentration in a headspace of an immersion chamber or another portion of an immersion cooling system. The vapor level in the headspace and / or vapor concentration in the headspace is a leading indicator before a substantial pressure change occurs in the immersion cooling system. Conventional immersion tanks and conduits of immersion cooling systems are constructed to withstand pressure differentials between the immersion cooling system and the ambient atmosphere. By more quickly predicting and responding to pressure changes in an immersion cooling system, the reliability and / or service life of the immersion cooling system may be improved.

[0083] In some embodiments, the immersed working fluid is a two-phase working fluid that receives heat from the heat generating component by evaporation. For example, the immersion chamber surrounds the heat generating component in a liquid working fluid that conducts heat from the heat generating component to cool the heat generating component. As the working fluid absorbs heat from the heat generating component, the temperature of the working fluid increases. In some embodiments, the hot working fluid can be circulated through a thermal management system to cool the working fluid and / or replace the working fluid with a cold working fluid. In some embodiments, the working fluid vaporizes, introducing vapor into the liquid of the working fluid rising from the liquid phase, and taking away heat energy from the heat generating component in the vapor phase via the latent heat of boiling.

[0084] In large computing centers (such as cloud computing centers, data processing centers, data storage centers, or other computing facilities), immersion cooling systems provide an efficient thermal management method for many computing components under various operating loads. In some embodiments, the immersion cooling system includes a working fluid in an immersion chamber and a heat exchanger for cooling the liquid phase and / or a condenser for extracting heat from the gas phase of the working fluid. The heat exchanger may include a condenser that condenses the gas phase of the working fluid into a liquid phase and returns the liquid working fluid to the immersion chamber. In some embodiments, the liquid working fluid absorbs heat from the heat generating components, and one or more fluid conduits direct the hot liquid working fluid outside the immersion chamber to a radiator, a heat exchanger, or an area of ​​lower temperature to cool the liquid working fluid.

[0085] In some embodiments, computing devices or systems assigned to immersion cooling systems and / or high computing applications executed thereon require extensive thermal management. The working fluid boils to absorb heat to overcome the latent heat of boiling. Thus, the phase change from liquid to vapor allows the working fluid to absorb a relatively large amount of heat with a slight associated rise in temperature. In addition, the lower density allows for efficient removal of vapor from the immersion bath to remove the associated heat from the system.

[0086] In some embodiments, the thermal management system includes an immersion tank having an immersion chamber defined therein. The two-phase working fluid receives heat from a heat generating component immersed in the liquid working fluid, and the heat vaporizes the working fluid, causing the working fluid to change from a liquid phase to a vapor phase. The thermal management system includes a condenser for condensing the vapor working fluid back to a liquid phase, such as described herein. In some embodiments, the condenser is in fluid communication with the immersion tank via one or more conduits. In some embodiments, the condenser is positioned within the immersion tank.

[0087] Conventional immersion cooling systems include an immersion tank containing an immersion chamber and a condenser in the immersion chamber. The immersion chamber contains an immersion working fluid having a liquid working fluid and a vapor working fluid portion. The liquid working fluid forms an immersion bath in which a plurality of heat generating components are positioned to heat the liquid working fluid on a support.

[0088] In some embodiments, the immersion cooling system includes an immersion tank defining an immersion chamber in which an immersion working fluid is positioned. The immersion working fluid in the immersion tank has a boiling temperature selected based at least in part on one or more operating characteristics of the immersion cooling system, electronic components and / or computing devices in the immersion tank, computational or workload of the electronic components and / or computing devices in the immersion tank, external and / or environmental conditions, or other characteristics that affect the operation of the immersion cooling system.

[0089] In some embodiments, the immersion working fluid transitions between a liquid working fluid phase and a vapor working fluid phase to remove heat from a heat or heat generating component in the immersion chamber. The liquid working fluid more efficiently receives heat from the heat generating component, and upon transitioning to a vapor working fluid, the vapor working fluid can be withdrawn from the immersion tank, cooled and condensed by a condenser (or other heat exchanger) to extract heat from the working fluid, and the liquid working fluid can be returned to the liquid immersion bath.

[0090] In some embodiments, the bath of the liquid working fluid has a plurality of heat generating components located in the liquid working fluid. The liquid working fluid surrounds at least a portion of the heat generating component and other objects or components attached to the heat generating component. In some embodiments, the heat generating component is located in the liquid working fluid on one or more supports. The supports can support one or more heat generating components in the liquid working fluid and allow the working fluid to move around the heat generating component. In some embodiments, the supports are thermally conductive to conduct heat from the heat generating component. (Multiple) supports can increase the effective surface area from which the liquid working fluid can remove heat by convection cooling.

[0091] In some embodiments, the heat generating component comprises an electronic component or a computing component or a power supply. In some embodiments, the heat generating component comprises a computer device, such as a personal computer or a server blade computer. In some embodiments, one or more heat generating components comprise a heat sink or other device attached to the heat generating component to conduct away heat energy and effectively increase the surface area of ​​the heat generating component. In some embodiments, the heat sink of the heat generating component is a steam chamber having one or more three-dimensional structures to increase the surface area.

[0092] As described above, converting the liquid working fluid to the vapor phase requires input of heat energy to overcome the latent heat of vaporization, and this can be an effective mechanism for increasing the heat capacity of the working fluid and removing heat from the heat generating components. Because the vapor working fluid rises in the liquid working fluid, the vapor working fluid can be extracted from the immersion chamber in the upper vapor region of the chamber. The condenser cools a portion of the vapor working fluid back into the liquid working fluid to remove heat energy from the system and reintroduces the working fluid into the immersion bath of the liquid working fluid. The condenser radiates or otherwise dumps the heat energy from the working fluid into the surrounding environment or into the piping to carry the heat away from the cooling system.

[0093] In some embodiments of the immersion cooling system, a liquid-cooled condenser is integrated into the immersion tank and / or chamber to efficiently remove thermal energy from the working fluid. In some embodiments, an immersion cooling system for thermal management of a computing device allows at least one immersion tank and / or chamber to be connected to and in fluid communication with an external condenser. In some embodiments, the immersion cooling system includes a vapor return line connecting the immersion tank to the condenser and allowing vapor working fluid to enter the condenser from the immersion tank and / or chamber, and a liquid return conduit connecting the immersion tank to a cooler and allowing liquid working fluid to return to the immersion tank or chamber.

[0094] The vapor return line may be lower than the boiling temperature of the working fluid. In some embodiments, a portion of the vapor working fluid condenses in the vapor return line. In some embodiments, the vapor return line may be oriented at an angle such that the vapor return line is not perpendicular to the direction of gravity. The condensed working fluid may then be discharged rearwardly to an immersion tank or forwardly to a condenser, depending on the direction of the inclination of the vapor return line. In some embodiments, the vapor return line includes a liquid collection line or valve, such as a bleed valve, which allows the condensed working fluid to be collected and / or returned to an immersion tank or a condenser.

[0095] In some examples, the immersion cooling system includes an air cooled condenser. The air cooled condenser may require a fan or pump to force ambient air to flow through one or more heat pipes or fins to transfer heat from the condenser to the air. In some embodiments, the circulation of the immersion working fluid through the immersion cooling system causes the liquid working fluid to flow through one or more heat generating components. In the example of a heat generating component with a vapor chamber heat sink, the dynamics of the liquid working fluid can be used to move the vapor chamber working fluid within the vapor chamber and / or boiling of the immersion working fluid by the vapor chamber can drive the flow of the immersion working fluid.

[0096] In some embodiments, the liquid working fluid receives heat in a cooling volume of the working fluid in close proximity to the heat generating component. The cooling volume is the area of ​​the working fluid (including liquid and gas phases) that directly surrounds the heat generating component and is responsible for convective cooling of the heat generating component. In some embodiments, the cooling volume is the volume of the working fluid within 5 millimeters (mm) of the heat generating component.

[0097] The immersion working fluid has a boiling point temperature lower than the critical temperature at which the heat generating component is thermally damaged. The immersion working fluid can thereby receive heat from the heat generating component to cool the heat generating component before the heat generating component is damaged.

[0098] For example, the heat generating component can be a computing component that is damaged above 100° Celsius (C). In some embodiments, the boiling temperature of the immersion working fluid is lower than the critical temperature of the heat generating component. In some embodiments, the boiling temperature of the immersion working fluid is less than about 90°C at 1 atmosphere. In some embodiments, the boiling temperature of the immersion working fluid is less than about 80°C at 1 atmosphere. In some embodiments, the boiling temperature of the immersion working fluid is less than about 70°C at 1 atmosphere. In some embodiments, the boiling temperature of the immersion working fluid is less than about 60°C at 1 atmosphere. In some embodiments, the boiling temperature of the immersion working fluid is at least about 35°C at 1 atmosphere. In some embodiments, the working fluid comprises water.

[0099] In some embodiments, the working fluid comprises ethylene glycol. In some embodiments, the working fluid comprises a combination of water and ethylene glycol. In some embodiments, the working fluid comprises an aqueous solution. In some embodiments, the working fluid comprises an electronic liquid, such as FK-649 vapor, or a similar non-conductive fluid. In some embodiments, a heat generating component, a support, or other element of an immersion cooling system positioned in the working fluid has nucleation sites on its surface that promote the nucleation of vapor bubbles of the working fluid at or below the boiling temperature of the working fluid. It should be understood that although the present disclosure will describe the use of the sensor with the FK-649 two-phase immersed working fluid, the systems and methods described herein are applicable to other immersed working fluids.

[0100] In some embodiments, sensors according to the present disclosure detect and / or measure the presence of a vapor phase of one or more immersion working fluids in an immersion cooling system. In some embodiments, the immersion working fluid is a two-phase working fluid that boils during operation of the immersion cooling system. In some embodiments, the immersion working fluid has a vapor phase that is heavier than other gases in the immersion chamber, and the vapor phase of the immersion working fluid can settle toward a boundary of a liquid phase of the immersion working fluid. The vapor level in the headspace of the immersion chamber can be used to measure the amount of change or rate of change of the amount of vapor working fluid in the immersion chamber.

[0101] In some embodiments, an optical system for measuring vapor concentration in a sample portion of a headspace or other region of an immersion cooling system includes an energy source, such as a pulse width modulation (PWM) driver, that provides an infrared beam. In some embodiments, the infrared beam is an infrared (IR) infrared beam. For example, the infrared beam can have a spectrum, at least a portion of which is in the IR range. In some examples, the infrared beam can have a spectrum with a peak wavelength in the IR range. In at least one example, the infrared beam can have a spectrum with a peak wavelength at 8 microns or between 7500 nanometers (nm) and 8500 nm.

[0102] An infrared beam is provided to a vapor sample portion of the vapor working fluid, and the vapor sample portion absorbs at least a portion of the infrared beam such that a transmissive portion of the infrared beam is transmitted through the vapor sample portion. An optical sensor receives the transmissive portion to measure at least one property of the transmissive portion, such as an intensity of the transmissive portion. The optical sensor provides at least one measurement to a microcontroller to record and / or interpret the measurement.

[0103] In some embodiments, the infrared beam can be directed by the energy source toward the optical sensor. In other embodiments, at least one optical element is located in the beam path of the infrared beam (e.g., in the transmission portion) to change the direction of the infrared beam toward the optical sensor. For example, a grating, a reflector, a beam splitter, or other optical element can direct the infrared beam toward the optical sensor. In at least one embodiment, the grating directs a first portion of the infrared beam toward the optical sensor and directs a second portion of the infrared beam toward a reference sensor. For example, the grating splits the infrared beam into a first portion having a first wavelength (which can be at or near an absorption peak of the vapor working fluid) and a second portion of the infrared beam having a second wavelength that is not strongly absorbed by the vapor working fluid in the vapor sample portion 330. The difference between the measurement at the optical sensor and the measurement at the reference sensor can allow the microcontroller to normalize the measurement at the optical sensor.

[0104] In some embodiments, the signal conditioner is positioned between the optical sensor and the microcontroller. In some embodiments, the signal conditioner is positioned between the reference sensor and the microcontroller. In some embodiments, the signal conditioner receives information from both the optical sensor and the reference sensor before transmitting the measurements from the optical sensor and the reference sensor to the microcontroller.

[0105] In some embodiments, the microcontroller also controls the energy source, such as providing a PWM signal to a PWM driver of the energy source to control the infrared light beam emission. The emission spectrum of the energy source can be related to the source temperature of the energy source, and the energy source can include or be coupled to a resistor / temperature sensor to control and measure the source temperature of the energy source. The resistor / temperature sensor can communicate with the microcontroller to allow the microcontroller to control the source temperature of the energy source and receive information related to the source temperature of the energy source during the emission of the infrared light beam.

[0106] In some embodiments, the resistor / temperature sensor maintains the source temperature at no less than 90°C. In some embodiments, the resistor / temperature sensor maintains the source temperature at approximately 93°C. In some embodiments, the resistor / temperature sensor maintains the source temperature at least 30°C above the boiling temperature of the immersion working fluid. In some embodiments, the resistor / temperature sensor maintains the source temperature at least 40°C above the boiling temperature of the immersion working fluid. The temperature difference between the liquid phase of the immersion working fluid and the source temperature reduces noise and / or interference from the heat of the immersion working fluid at the optical sensor.

[0107] As described herein, it may be beneficial to provide an infrared light beam having a peak wavelength at or near the peak absorption of the steam working fluid to increase the contrast of the steam working fluid absorption signal. In some embodiments, the peak absorption wavelength of the steam working fluid is about 8 microns. In some embodiments, the energy source emits an infrared light beam including light in the 8 micron range. In at least one embodiment, the energy source emits an infrared light beam having a peak emission wavelength of 8 microns or between 7500 nanometers (nm) and 8500 nm. The optical sensor is sensitive to light at or near 8 microns (e.g., between 7500 nm and 8500 nm) to receive a transmitted portion of the infrared light beam. The microcontroller may compare at least one attribute (e.g., intensity) of the transmitted portion of the infrared light beam received at the optical sensor with a known value of at least one attribute of the source portion of the infrared light beam provided by the energy source.

[0108] In some embodiments, multiple values ​​of at least one property of the transmissive portion and the source portion of the infrared beam are provided to the microcontroller. In some embodiments, multiple values ​​are captured over time to track and / or correlate the values ​​of at least one property of the transmissive portion and the source portion relative to vapor level / concentration. A machine learning (ML) model can be trained based on known vapor levels and / or vapor concentrations of one or more vapor working fluids to allow the ML model to identify or calculate pressure changes based at least in part on vapor level, vapor concentration, rate of change of vapor level or concentration, or a combination thereof.

[0109] As used herein, a "machine learning model" refers to a computer algorithm or model (e.g., a classification model, a regression model, a language model, an object detection model) that can be adjusted (e.g., trained) based on training inputs to approximate unknown functions. For example, an ML model can refer to a neural network or other machine learning algorithm or architecture that learns and approximates complex functions and generates outputs based on multiple inputs provided to the machine learning model. In some embodiments, the ML system, model, or neural network described herein is an artificial neural network. In some embodiments, the ML system, model, or neural network described herein is a convolutional neural network. In at least one embodiment, the ML system, model, or neural network described herein is a Bayesian classifier. As used herein, a "machine learning system" can refer to one or more ML models that collaboratively generate one or more outputs based on corresponding inputs. For example, an ML system can refer to any system architecture with multiple discrete ML components that take into account different types of information or inputs.

[0110] As used herein, an "instance" refers to an input object that can be provided as an input to an ML system for generating an output, such as the type of vapor working fluid present, the concentration of the vapor working fluid present, or the rate of change of the vapor working fluid present. For example, an instance can refer to any event in which a vapor working fluid is present. For example, a first absorption measurement or other measurement received at a microcontroller can be associated with the first vapor working fluid present in a sample portion of the vapor working fluid. In another example, a second absorption measurement or other measurement received at the microcontroller can be associated with a second vapor working fluid present in a sample portion of the immersion working fluid. In another example, a change in the absorption measurement or other measurement received at the microcontroller can be associated with an increase in the concentration of the vapor working fluid in the sample portion.

[0111] In some embodiments, the machine learning system has multiple layers, the multiple layers having an input layer and an output layer, the input layer being configured to receive at least one input training data set or input training instance, with multiple additional or hidden layers between the input layer and the output layer. The training data set can be input into the ML system to train the ML system and identify individuals and combinations of vapor working fluids, or other attributes of the training instances, which allow the microcontroller to identify known or unknown concentrations of the vapor working fluid.

[0112] In some embodiments, the machine learning system may receive multiple training data sets concurrently and learn from different training data sets at the same time.

[0113] In some embodiments, the machine learning system includes multiple machine learning models operating together. Each machine learning model has multiple hidden layers between an input layer and an output layer. The hidden layer has multiple input nodes, each of which operates on an input received from a previous layer. In a specific example, a first hidden layer has multiple nodes, and each node performs an operation on each instance from the input layer. Each node of the first hidden layer provides a new input to each node of the second hidden layer, which in turn performs a new operation on each of these inputs. The nodes of the second hidden layer then pass the output (such as an identified cluster) to the output layer.

[0114] In some embodiments, each node has a linear function and an activation function. The linear function can attempt to optimize or approximate the solution with a best fit line. The activation function serves as a test to check the validity of the linear function. In some embodiments, the activation function produces a binary output that determines whether the output of the linear function is passed to the next layer of the machine learning model. In this way, the machine learning system can limit and / or prevent the propagation of poor fits to the data and / or non-convergent solutions.

[0115] The machine learning model includes an input layer that receives at least one training data set. In some embodiments, at least one machine learning model uses supervised training. In some embodiments, at least one machine learning model uses unsupervised training. Unsupervised training can be used to infer and find patterns or associations from (multiple) training data sets without known outputs. In some embodiments, unsupervised learning can identify clusters of similar labels or features of various training instances and allow the machine learning system to infer the performance of instances with similar characteristics.

[0116] In some embodiments, semi-supervised learning can combine the advantages of supervised learning and unsupervised learning. As described herein, a machine learning system can identify relevant labels (such as known vapor working fluids or concentrations of vapor working fluids) or characteristics between instances, which can allow for the fusion of a training data set with known outputs and a second training data set including more general input information. Unsupervised training can allow a machine learning system to cluster instances in the second training data set without known outputs and associate the clusters with the known outputs of the first training data set.

[0117] In some embodiments, an immersion cooling system with an optical system includes at least an energy source and an optical sensor in communication with a microcontroller. In some embodiments, the optical system has a substantially vertical beam path in a headspace of an immersion chamber. A vapor working fluid is located in the headspace above a liquid working fluid.

[0118] In some embodiments, the headspace includes air or other gas and a vapor working fluid. As described herein, the vapor working fluid can be heavier than the air or other gas in the headspace. In some embodiments, the air / vapor interface is not a well-defined boundary. For example, there can be a vapor concentration gradient that is highest at the interface with the liquid working fluid and decreases as you rise vertically above the liquid working fluid. A beam path through this gradient can measure a greater total path loss when higher vapor levels are present and a smaller total path loss when lower vapor levels are present.

[0119] For example, the vapor concentration level can be calculated using the Beer-Lambert law:

[0120] AεLc

[0121] where A = the energy absorbed by the substance at a specific wavelength; ε = the molar extinction coefficient or absorption coefficient of the substance at a specific wavelength; L = the path length of the energy through the substance; and c represents the concentration of the substance. Thus, for a thin cross section in the vertical direction:

[0122] dA=ε(dL)(dc / dL)

[0123] The total path loss is:

[0124] A=εL∫(dc / dL)

[0125] In some embodiments, multiple optical systems located at different vertical positions in the headspace can be used to measure vapor concentration in the headspace using different beam paths and / or path lengths through the headspace. In some embodiments, the optical system can include at least one optical element to create multiple beam paths with different beam lengths and / or different vertical positions in the headspace.

[0126] In some embodiments, an optical system has a beam splitter that divides an infrared beam. In some embodiments, the optical system includes an energy source that provides the infrared beam in a headspace. The infrared beam begins from a shared path before the beam splitter splits the beam path into a first beam path toward a first optical sensor and a second beam path toward a second optical sensor. In some embodiments, the first beam path and the second beam path have different path lengths. In some embodiments, the first beam path and the second beam path have substantially equal path lengths.

[0127] In some embodiments, the shared path and the first beam path sample a first vertical portion of the headspace, and the shared path and the second beam path sample a second vertical portion of the headspace. For example, the first vertical portion and the second vertical portion are located at different vertical locations in the headspace. In some embodiments, the first vertical portion and the second vertical portion have different vertical lengths. In some embodiments, the first vertical portion and the second vertical portion have substantially equal vertical lengths.

[0128] The first optical sensor and the second optical sensor can provide one or more measurements to the microcontroller. In some embodiments, the microcontroller can obtain or store information about the relative path lengths and / or positions of the shared path, the first beam path, and the second beam path. Thus, the microcontroller can determine the vapor level in the headspace.

[0129] Although the embodiments of the optical systems described herein have substantially vertical beam paths, in other embodiments, the beam paths can be oriented at other angles in the headspace to sample the vapor working fluid therein. For example, multiple optical systems (such as the optical systems described herein) can be oriented with horizontal beam paths and positioned at a series of discrete vertical positions to sample the vapor working fluid at a series of discrete vertical positions. In another example, the beam path can be oriented diagonally to increase the path length and increase the absorption of the infrared beam by the vapor working fluid. In other examples, the beam path can be directed through multiple optical elements (prisms, mirrors, etc.) to further extend the path length.

[0130] In some embodiments, an immersion cooling system includes an optical system having a diagonal beam path. In some embodiments, the diagonal beam path between the energy source and the optical sensor in communication with the microcontroller (which may include a grating or other optical element therebetween) may cause the infrared beam to experience greater attenuation when passing through the vapor working fluid in the headspace than a substantially perpendicular beam path.

[0131] In some embodiments, a method for measuring vapor level and / or concentration in an immersion cooling system includes positioning a sample portion of an immersion working fluid in a sampling region between an energy source and an optical sensor, and providing a beam path and path length to an infrared beam passing through the sample portion. The method also includes receiving a transmitted portion of the infrared beam with the optical sensor, and measuring the intensity of the transmitted portion relative to a source portion of the infrared beam. In some embodiments, the energy source and / or infrared beam is any energy source or infrared beam described herein. For example, the infrared beam can be an IR infrared beam.

[0132] In some embodiments, the source portion of the infrared beam is a portion of the infrared beam emitted from the energy source at a known intensity and / or wavelength near the energy source. The transmitted portion of the infrared beam is a portion of the infrared beam near the optical sensor that has at least a portion of the infrared beam absorbed and / or attenuated by the gas phase of the immersed working fluid in the sample portion.

[0133] The method also includes determining a concentration of a gas phase of the immersion working fluid in the sample portion. For example, determining the concentration can include providing the measured intensity to a microcontroller, and calculating the concentration with the microcontroller. In other examples, the concentration can be calculated elsewhere. In at least one example, the concentration is calculated at least in part based on Beer-Lambert. In at least one example, the concentration is determined by inputting the measured intensity into an ML system.

[0134] In some embodiments, the method optionally includes remediating the pressure of the gas phase in the immersion chamber. For example, remediating the pressure of the gas phase may include automatically venting at least a portion of the vapor pressure of the immersion cooling system, such as from the immersion tank or via a vent in a condenser of the immersion cooling system.

[0135] In another example, remediating the pressure of the gas phase can include automatically adding cold immersion working fluid (e.g., at least 1°C below the boiling temperature of the immersion working fluid) to the immersion cooling system, such as opening a valve to add cold immersion working fluid to the immersion cooling system to reduce the temperature of the liquid working fluid to reduce the vaporization rate of the immersion working fluid. In at least one embodiment, adding cold immersion working fluid to the immersion cooling system includes opening a valve to allow cold immersion working fluid to flow from a reservoir through the valve into the immersion cooling system. For example, the valve can be controlled by a microcontroller, and the microcontroller can open the valve based at least in part on the determined gas phase concentration.

[0136] In another example, remediating the pressure of the gas phase can include automatically replacing the hot immersion working fluid with a cool immersion working fluid (e.g., at or near the boiling temperature of the immersion working fluid). Replacing the hot immersion working fluid with the cool immersion working fluid can include opening at least a first valve to drain a portion of the hot immersion working fluid from the immersion cooling system, and opening at least a second valve to allow cool immersion working fluid to flow from the reservoir through the valve into the immersion cooling system. In at least one embodiment, the valve can be controlled by a microcontroller, and the microcontroller can open the valve based at least in part on the determined gas phase concentration.

[0137] In some embodiments, an immersion cooling system has an optical system in communication with one or more remediation features. For example, the immersion cooling system may include a reservoir containing a cold immersion working fluid and a collection tank configured to capture at least a portion of the hot liquid working fluid. In some embodiments, the reservoir is connected to a return conduit or other inlet of the immersion chamber to introduce the cold immersion working fluid into the immersion chamber. In other examples, the reservoir may be connected to the immersion chamber directly or through a dedicated conduit, or the reservoir may be connected to a condenser to deliver the cold immersion working fluid to the immersion cooling system via the condenser.

[0138] In some embodiments, the first valve controls the flow of cold submerged working fluid into the immersion cooling system. The first valve may be controlled by a microcontroller. In other embodiments, the first valve may be controlled by another control plane that receives steam level and / or steam concentration information from the microcontroller.

[0139] The collection tank can be connected to the immersion cooling system through a second valve. In some embodiments, the collection tank is connected to a return conduit or other conduit of the immersion chamber to receive the hot liquid working fluid from the immersion chamber. In other examples, the collection tank can be connected to the immersion chamber directly or through a dedicated conduit, or the collection tank can be connected to a condenser to receive the hot liquid working fluid from the immersion cooling system via the condenser. In some embodiments, the collection tank is positioned and configured to receive the vapor working fluid through a vent that communicates with the immersion chamber, the condenser, or another portion of the immersion cooling system.

[0140] In some embodiments, the second valve controls the flow of hot liquid working fluid from the immersion cooling system. The second valve can be controlled by a microcontroller. In other embodiments, the second valve can be controlled by another control plane that receives vapor level and / or vapor concentration information from the microcontroller. In at least one embodiment, the microcontroller or other control plane at least partially simultaneously opens the first valve and the second valve (e.g., the time period during which the first valve is open at least partially overlaps the time period during which the second valve is open) to introduce cold immersion working fluid from the reservoir into the immersion cooling system while moving at least a portion of the hot liquid working fluid into the collection tank.

[0141] The present disclosure relates to systems and methods for cooling heat generating components of a computer or computing device according to at least the examples provided in the following sections:

[0142] [A1] In some embodiments, an immersion cooling system includes an immersion tank having an immersion chamber defined therein, an immersion working fluid, an energy source, an optical sensor, and a microcontroller. The immersion working fluid is at least partially located in the immersion chamber, and the immersion working fluid has a liquid phase and a vapor phase. The energy source is positioned and oriented to direct an infrared beam through a portion of the vapor phase using a beam path and a path length. The optical sensor is located in the beam path. The microcontroller is configured to determine a vapor concentration in the immersion chamber based at least in part on data from the path length, the optical sensor, and the energy source.

[0143] [A2] In some embodiments, the beam path of [A1] samples a gas phase in a vapor conduit in fluid communication with the immersion chamber.

[0144] [A3] In some embodiments, the beam path of [A1] samples the gas phase in the headspace of the immersion chamber.

[0145] [A4] In some embodiments, the grating is configured to direct a first portion of the infrared light beam of any one of [A1] to [A3] toward the optical sensor.

[0146] [A5] In some embodiments, the grating of [A4] is configured to direct a reference portion of the infrared light beam toward a reference sensor.

[0147] [A6] In some embodiments, the energy source of any one of [A1] to [A5] is configured to provide the infrared light beam with a wavelength at the peak absorption of the gas phase of the working fluid.

[0148] [A7] In some embodiments, the optical sensor of any one of [A1] to [A6] measures the transmitted portion of the infrared light beam at 8 microns.

[0149] [A8] In some embodiments, the beam path of any of [A1] to [A7] is oriented diagonally through the head space in the immersion chamber.

[0150] [A9] In some embodiments, the beam path of any of [A1] to [A7] is oriented vertically through the head space in the immersion chamber.

[0151] [A10] In some embodiments, the energy source of any one of [A1] to [A9] includes a resistor for maintaining a source temperature greater than 90°C.

[0152] [A11] In some embodiments, the difference between the source temperature of [A10] and the boiling temperature of the liquid phase of the immersion working fluid is at least 30°C.

[0153] [A12] In some embodiments, the system of any of [A1] to [A11] includes a computing device located in a liquid phase of the immersion working fluid.

[0154] [A13] In some embodiments, the microcontroller of any of [A1] to [A12] is configured to control at least one remediation feature.

[0155] [A14] In some embodiments, at least one remedial feature of [A13] includes at least one valve to allow fluid communication between the immersion chamber and at least one additional fluid tank.

[0156] [B1] In some embodiments, an immersion cooling system includes an immersion tank having an immersion chamber defined therein, an immersion working fluid, an energy source, a first optical sensor, an optical element, a second optical sensor, and a microcontroller. The immersion working fluid is at least partially positioned in the immersion chamber, and the immersion working fluid has a liquid phase and a gas phase. The energy source is positioned and oriented to direct an infrared beam through a portion of the gas phase using a beam path and a path length. The first optical sensor is positioned and oriented to direct a first infrared beam through a first portion of the gas phase using a first beam path and a first path length. The optical element is configured to direct at least a portion of the first infrared beam through a second portion of the gas phase using a second beam path and a second path length. The second optical sensor is positioned in the second beam path. The microcontroller is configured to determine a vapor concentration in the immersion chamber based at least in part on data from the first path length, the first optical sensor, the second path length, the second optical sensor, and the energy source.

[0157] [B2] In some embodiments, the optical element of [B1] is a beam splitter.

[0158] [B3] In some embodiments, a first portion of the gas phase of [B1] or [B2] is located in a first vertical position in the head space of the immersion chamber, and a second portion of the gas phase is located in a second vertical position in the head space.

[0159] [C1] In some embodiments, a method for measuring vapor concentration in an immersion cooling system includes positioning a sample portion of an immersed working fluid in a sampling region between an energy source and an optical sensor, providing a beam path and a path length for an infrared light beam passing through the sample portion, receiving a transmitted portion of the infrared light beam with the optical sensor, measuring an intensity of the transmitted portion relative to a source portion of the infrared light beam, and determining a concentration of a vapor phase of the immersed working fluid in the sample portion.

[0160] [C2] In some embodiments, the method of [C1] includes determining a pressure change in the immersion chamber based at least in part on a concentration of the gas phase.

[0161] [C3] In some embodiments, the method of [C2] includes automatically remediating pressure changes in the immersion chamber.

[0162] The articles "a", "an" and "the" are intended to indicate the presence of one or more of the elements in the preceding description. The terms "comprising", "including" and "having" are intended to be inclusive, indicating that there may be other elements in addition to the listed elements. In addition, it should be understood that reference to "one embodiment" or "embodiment" of the present disclosure does not exclude the existence of other embodiments that also contain the features. For example, any element associated with the embodiments described herein can be combined with any element of any other embodiment shown herein. As will be understood by those of ordinary skill in the art covered by the embodiments of the present disclosure, the numbers, percentages, ratios or other values ​​described herein are intended to include the value, as well as other values ​​that are "approximately", "substantially" or "approximate" to the value. Therefore, the stated values ​​should be interpreted broadly enough to include values ​​that are at least close enough to the stated values ​​to perform the desired function or achieve the desired result. The stated values ​​include at least the expected changes in suitable manufacturing or production processes, and may include values ​​within 5%, within 1%, within 0.1% or within 0.01% of the stated values.

[0163] Those skilled in the art will recognize that, in light of the present disclosure, equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions, and modifications may be made to the embodiments disclosed herein without departing from the spirit and scope of the present disclosure. Equivalent constructions (including functional "means plus function" clauses) are intended to cover structures described herein that perform the functions described, including structural equivalents that operate in the same manner and equivalent structures that provide the same functions. It is the express intent of the applicant not to invoke means plus function or other functional claims for any claim, except for claims in which the term "parts for..." appears together with the associated function. Every addition, deletion, and modification to the embodiments that falls within the meaning and scope of the claims will be covered by the claims.

[0164] It should be understood that any directions or reference frames in the foregoing description are merely relative directions or motions. For example, any reference to "front" and "back" or "up" and "down" or "left" and "right" is merely a description of the relative position or motion of the relevant elements.

[0165] The present disclosure may be embodied in other specific forms without departing from its spirit or features. The described embodiments should be regarded as illustrative rather than restrictive. Therefore, the scope of the present disclosure is indicated by the appended claims rather than by the above description. Changes within the equivalent meaning and scope of the claims should be included within their scope.

Claims

1. A system for immersion cooling, the system comprising: an immersion tank having an immersion chamber defined therein; an immersion working fluid at least partially positioned in the immersion chamber, the immersion working fluid having a liquid phase and a vapor phase; an energy source positioned and oriented to direct an infrared beam through a portion of the gas phase using a beam path and a path length; an optical sensor positioned in the light beam path; as well as A microcontroller is configured to determine a vapor concentration in the immersion chamber based at least in part on data from the path length, the optical sensor, and the energy source. 2 . The system of claim 1 , wherein the light beam path samples the gas phase in a vapor conduit in fluid communication with the immersion chamber.

3. The system of claim 1, wherein the beam path samples the gas phase in a headspace of the immersion chamber. 4 . The system of claim 1 , further comprising a grating configured to direct a first portion of the infrared light beam toward the optical sensor.

5. The system of claim 4, wherein the grating is configured to direct a reference portion of the infrared beam toward a reference sensor.

6. The system of any of the preceding claims, wherein the energy source is configured to provide the infrared beam with a wavelength at a peak absorption of the gas phase of the working fluid.

7. The system of any of the preceding claims, wherein the optical sensor measures the transmitted portion of the infrared light beam at 8 microns.

8. The system of claim 1, wherein the beam path is oriented diagonally across a headspace in the immersion chamber.

9. The system of claim 1, wherein the beam path is oriented vertically across a headspace in the immersion chamber.

10. The system of any preceding claim, wherein the energy source comprises a resistor to maintain a source temperature greater than 90°C.

11. The system of claim 10, wherein the difference between the source temperature and the boiling temperature of the liquid phase of the immersion working fluid is at least 30°C.

12. The system of any preceding claim, further comprising a computing device positioned in the liquid phase of the immersion working fluid.

13. The system of any preceding claim, wherein the microcontroller is configured to control at least one remedial feature.

14. The system of claim 13, wherein the at least one remedial feature comprises at least one valve to allow fluid communication between the immersion chamber and at least one additional fluid tank.

15. A method of measuring steam concentration in an immersion cooling system according to any one of the preceding claims, the method comprising: positioning a sample portion of the immersion working fluid in a sampling region between the energy source and the optical sensor; providing a beam path and a path length for an infrared beam passing through the sample portion; receiving a transmitted portion of the infrared light beam with the optical sensor; measuring the intensity of the transmitted portion relative to the source portion of the infrared beam; as well as A concentration of a gas phase of the immersion working fluid in the sample portion is determined.

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