Hybrid thermal management system

Abstract

A hybrid thermal management system including a thermosyphon cooling system to cool a first heat generating component set to a first operating temperature range and a heating, ventilation, and air conditioning (HVAC) system to cool a second heat generating component set to a second operating temperature range that is at least partially different than the first operating temperature range. The thermosyphon cooling system operates passively and includes an evaporator encompassing a volume of liquid coolant and a condenser positioned above the evaporator and operably connected thereto in a closed loop. The HVAC system cooling the second heat generating component set via a thermal conductor in contact with a heat sink of the second heat generating component set.

Description

HYBRID THERMAL MANAGEMENT SYSTEMBACKGROUND

[0001] Embodiments of the present disclosure generally relate to industrial cooling systems. In some instances, the cooling systems may be deployed to cool electronic and electrical equipment including, for example, various component systems and devices such as, but not limited to computing systems, data centers, energy generation systems, energy storge systems, telecommunications, and the like. In some applications, two or more different component systems may be located or housed in a same room, container, rack, or other enclosure. In some applications, one or more devices of the component systems (e.g., electrical and electronic) may be vertically stacked relative to each other to economize space in a rack or other enclosure housing the component systems. The electrical and electronic equipment typically generates heat when operating, where some such systems might always be on to continuously provide needed / desired services to customers and other users. As such, the cooling systems must be designed and configured to control environmental factors such as excessive heat generated by the component systems that can damage or destroy hardware devices and systems, result in costly or catastrophic downtime(s), and possibly create dangerous situations (e.g., potential fires, etc.).

[0002] One conventional method of cooling electrical and electronic component systems includes traditional heating, ventilation, and air conditioning (HVAC) systems, where the HVAC system operates to cool and dehumidify air in a room, rack, or other enclosure and further circulates the cooled air over the component systems located within the enclosure. Some cooling systems might utilize liquid cooling technologies that may be used in addition to or instead of air cooling. Some such systems operate by pumping a liquid coolant onto contact surface(s) of the heat generating devices (e.g., processors) of the component systems.

[0003] In general, electrical and electronic devices have a characteristic operating temperature range, defined from a minimum operating temperature to a maximum operating temperature, within which the device is designed to safely and efficiently operate and outside of which the device does not operate efficiently, safely, or at all. In an instance where components having different operating temperature ranges are co-located in a same room, rack, or other enclosure and cooled by the same (i.e., a common) cooling system, the coolingsystem must be designed and operated to account for the different operating temperature ranges. For example, in an HVAC cooled equipment rack housing a set of batteries having an operating temperature range of (15 - 35) degrees Celsius (C) and one or more power converters having an operating temperature range up to about 125 degrees C, where the HVAC will cool the entire system, the temperature limits of the set of batteries will drive the set point of the HVAC. In this example, the HVAC set point may be set to about (18 - 25) degrees C to satisfy the operating temperature range required by the battery. Clearly, this temperature setting may be overkill for the one or more power converters, although required for the batteries. As a result, the energy consumption for the HVAC system in this example may be greatly increased due to the requirement to maintain the temperature in the rack below 35 degrees C. Accordingly, in such mixed component environment applications the HVAC sizing is typically larger, the energy consumption is higher, and the carbon footprint impacts are also increased.

[0004] Accordingly, there exists a need for a thermal management system that operates to optimally and efficiently cool multiple different components having different operating temperature ranges.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 is an illustrative depiction of a conventional HVAC cooled equipment rack;

[0006] FIG. 2 is an illustrative depiction of a conventional thermosyphon system;

[0007] FIG. 3 is a tabular listing of candidate coolants, according to some embodiments;

[0008] FIGS. 4A, 4B, and 4C are illustrative examples of various aspects of a hybrid thermal management system, according to some embodiments;

[0009] FIGS. 5A, 5B, and 5C are illustrative examples of a hybrid thermal management system operating in different climatic environments, in accordance with some embodiments;

[0010] FIG. 6 is an illustrative example of a unified thermosyphon loop for multiple components, according to some embodiments;

[0011] FIG. 7 is an illustrative example of a plurality of vertically positioned heat generating devices cooled by a thermosyphon system configured for improved thermosyphon coolant flow, in accordance with some embodiments; and

[0012] FIG. 8 is an illustrative example of a thermosyphon system further configured for fire suppression by a liquid coolant therein, in accordance with some embodiments.

[0013] Throughout the drawings and the detailed description, unless otherwise described, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. The relative size and depiction of these elements may be exaggerated or adjusted for clarity, illustration, and / or convenience.DETAILED DESCRIPTION

[0014] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of embodiments. However, it will be understood by those of ordinary skill in the art that the embodiments may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the embodiments.

[0015] One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers’ specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. Thus, the various embodiments disclosed herein do not constitute a definition of all possible embodiments, and those skilled in the art will understand that the present disclosure is applicable to many other implementations and / or applications.

[0016] In general, and for the purpose of introducing concepts of novel embodiments disclosed herein, presented are systems, apparatus and methods for a hybrid thermal management system that efficiently cools two or more component systems having operating temperature ranges that differ, at least partially, from each other. In some embodiments, a hybrid thermal management system herein may include a thermosyphon cooling system to cool a first heat generating component set to a first operating temperature range and a HVAC system to cool a second heat generating component set to a second operating temperature range that is at least partially different than the first operating temperature range.

[0017] FIG. 1 is an illustrative depiction of a conventional HVAC cooled equipment rack. In the example of FIG. 1, system 100 includes an equipment rack housing 105 that encloses a set of batteries (e.g., 110, 115, 120, 125, 130, 135, 140, 145, 150, and 155) therein. The batteries might be configured to store and / or provide energy from / to one or more systems or devices (not shown in FIG. 1). The batteries have a characteristic operating temperature range (e.g., lithium ion (Li-ion) batteries with an optimal operating temperature range of about 15 - 35 degrees C (and a safe operating range of about 5 - 60 degrees C) and may generate heat as a result of their charging and discharging of energy. Accordingly, HVAC 160 is positioned inside of housing 105 and controlled to maintain the enclosed environment inside of housing 105, including the rack-mounted batteries, within the operating temperature range of the batteries. Arrows 170 and 175 represent air forcibly circulated throughout the housing by one or more motors, blowers, and fans of the HVAC system. The arrows depicted on each of the batteries are illustrative representations of the HVAC conditioned air moved across and in contact with each of the batteries, thereby cooling the batteries.

[0018] FIG. 2 is an illustrative depiction of a thermosyphon system 200, that might be used in some embodiments herein. Thermosyphon system 200 is an example of a passive two-phase, pump-free or pumpless cooling system. Thermosyphon 200 includes an evaporator 210 located within an enclosure 205 (e.g., a room or other container). One or more component devices, such as, for example, electrical, electronic, and electro-chemical systems that generate heat during an operation thereof may be placed into contact with the evaporator such that the evaporator is heated by the one or more component devices. Evaporator 210 may include a volume of liquid coolant therein, which upon being heated to or above its threshold boiling temperature, changes from a liquid to a vapor. The vapor rises and travels, via conduits or pipes 215 and 220, to a condenser 225 located at a positionelevated above evaporator 210. In the example of FIG. 2, condenser 225 is cooled by air that is forced over the surface(s) of the condenser, which acts to cool the vaporized coolant therein below its boiling point temperature (i.e., threshold value). Upon being cooled and changing to a liquid, the coolant is routed via conduit or pipe 230 by the force of gravity from the elevated position of condenser 225 to the lower positioned evaporator 210. The heat load of the component device(s) is sufficient to cause the coolant to evaporate to a vapor phase and rise through the conduit(s) to the condenser that cools the coolant sufficiently for it to change to a liquid phase and return back to the evaporator by gravity. In this manner, the closed-loop thermosyphon system 200 may operate passively, without a need for pumps or other active energy sources or devices to circulate the coolant therein. In some embodiments, more than one condenser may be used, as determined by specific application requirements.

[0019] In some aspects, because there is a liquid to vapor phase change at the place of energy being generated, the ability to remove heat from the heat generating component is significantly higher compared to air or even compared to liquid cooling because using the phase change to remove heat involves latent heat of energy that is much larger than the specific heat of the coolant. Thus, from a cooling standpoint, the disclosed passive thermosyphon is a significantly high performance methodology.

[0020] In some aspects of a thermosyphon system herein, the only active component requiring energy might be at least one fan, blower, or other device, system, or mechanism attached to the condenser of the thermosyphon to force air over the condenser. In some embodiments, the at least one fan, blower, or other device, system, or mechanism may operate to draw / receive air from the environment outside of the enclosure and blow it across or through the condenser to lower the temperature of the circulating vapor coolant to a liquid state. In some embodiments, depending on the elevation of the condenser, a fan or blower may not be required since ambient air may be flowing freely at a velocity sufficiently high for condensation of vapor into its liquid form.

[0021] In some embodiments, the coolant used in a thermosyphon system herein might include, as an example, 3M NOVEC649, R1233zd(e), and Chemours Opteon SF33. Other coolants may be used in some embodiments of a thermosyphon system herein, depending on a particular application and system requirements. As such, the specific coolants listed here are provided for illustrative purposes, not as limitations or an exhaustive listing. FIG. 3includes a tabular listing of some candidate coolants for a thermosyphon system herein, including various fluid properties associated with each candidate coolant.

[0022] In some aspects, coolants compatible with a thermosyphon system herein may be non-flammable. In some instances, such coolants may also have a freezing point that is less than 100 degrees C. Such example coolants may thus enable operation under extreme cold weather conditions and further have a low global warming potential (GWP) and ozone depleting potential (ODP).

[0023] FIGS. 4A, 4B, and 4C are illustrative examples of various aspects of a hybrid thermal management system 400, according to some embodiments. As shown, the hybrid thermal management system includes two cooling systems, including a thermosyphon system housed in enclosure 405 for cooling a component set of equipment (e.g., power electronic units 440, 445, 450, and 455) housed therein and a HVAC cooling system 420 for cooling a component set of equipment (e.g., batteries 415) housed with an enclosure or compartment 410. As illustrated in FIG. 4A, enclosure or compartment 410 housing the HVAC cooling system that cools the component set of equipment therein is contained within the enclosure 405 (i.e., a container within a container configuration).

[0024] In some embodiments, hybrid thermal management system 400 includes a thermosyphon system for cooling a first component set of equipment (e.g., power electronic units) and a HVAC cooling system for cooling a second component set of equipment (e.g., a bank of batteries), where the first component set of equipment and second component set of equipment have different operating temperature ranges. In some instances, the operating temperature ranges of the different component sets of equipment are at least partially different. That is, the operating temperature ranges of the different component sets of equipment need not be mutually exclusive of each other, there may be some overlap of the operating temperature ranges in some instances.

[0025] In some aspects of a hybrid thermal management system herein, the thermosyphon system may be optimized to efficiently cool the component set of equipment associated with and cooled by the thermosyphon system and the HVAC system may be optimized to efficiently cool the component set of equipment associated with and cooled by the HVAC system. In contrast to a HVAC cooling system that has to cool an entire system comprising different component sets of equipment having different operating temperature ranges wherethe HVAC system is oversized to compensate for the mismatch in operating temperature ranges, an embodiment of a hybrid thermal management system herein includes a thermosyphon system designed to efficiently cool the component set of equipment associated therewith while the HVAC system is designed to efficiently cool the component set of equipment associated with just the HVAC system. In this manner, a hybrid thermal management system herein may achieve a significant reduction in the requisite energy consumption. In some instances, a reduction in energy consumption by about 50% might be realized by a hybrid thermal management system herein, as compared to a conventional HVAC cooling system wherein the HVAC is solely responsible for all cooling needs of the system including different component sets of equipment having different operating temperature ranges.

[0026] Still referring to FIG. 4A, the thermosyphon system therein operates to cool the component set of equipment including power electronic (PE) devices 440, 445, 450, and 455 illustratively located on the left side of enclosure 405. The thermosyphon system is configured to maintain the temperature in the vicinity of the PE devices within the operating temperature range of the PE devices. In some embodiments, another component set of equipment might be located on the right side of enclosure 405 and configured similarly (not shown in FIG. 4A for clarity). The thermosyphon system in FIG. 4A further includes a condenser 425, a conduit 460 connecting an evaporator (not shown in FIG. 4A for clarity; shown in FIG. 4C) to condenser 425 to route vaporized coolant from the evaporator to the condenser, and a conduit 465 connecting the condenser to the evaporator to route liquid coolant from the condenser to the evaporator. In some embodiments, condenser 425 may be air or liquid cooled. The PE devices in FIG. 4A are positioned in thermal contact with the evaporator of the thermosyphon system (e.g., via a thermal interface material, a thermally conductive material, etc.) and cooled by a process as explained in the discussion above regarding the thermosyphon depicted in FIG. 2.

[0027] The HVAC system 420 in FIG. 4 A, located in enclosure 410 inside of housing or enclosure 405, is designed to cool the component set of equipment including batteries 415. In some instances, batteries 415 may be configured to store energy provided by the PE devices or other devices / sy stems (not shown) or provide energy to the PE devices or other devices / sy stems (not shown). HVAC 420 is configured to maintain cooling of the batteries so that they stay within their designed operating temperature range. HVAC 420 operates tocirculate air throughout enclosure 410. In some embodiments, HVAC 420 includes one or more fans, blowers, or other devices (not shown) to direct and encourage the cool air generated by the HVAC to move across surface(s) of the batteries. For example, cold air or liquid from HVAC 420 may flow through one or a plurality of heat sinks, included within the battery modules, to cool the batteries via a thermal conductor, thermal interface material, or the like in contact with the batteries.

[0028] Enclosure 405 may further include one or more vents to facilitate the inflow and outflow of air into and out of the enclosure. For example, enclosure 405 includes an inlet vent 430 for the inlet of passive or forced air circulation and an outlet vent 435 for the outlet of passive or forced air circulation for the cooling of auxiliary components in the hybrid thermal management system.

[0029] In some embodiments, the battery (or other component devices such as auxiliary devices cooled by the HVAC system) might generate about 50% or a slightly lower (e.g., 30 to 50%) amount of the heat generated in enclosure 405, whereas the remaining percent of the heat generated within the enclosure (e.g., 50 to 70%) might typically be produced by the PE units (and other devices) cooled by the thermosyphon system.

[0030] In some aspects, hybrid thermal management system 400 may include a modular architecture for a single rack enclosure to house a single rack of component set devices (e.g., batteries and other electronic and electrical equipment), dual rack systems, and multi-rack systems. That is, in some embodiments a hybrid thermal management system herein may be configured in a modular, repeatable format (e.g., a modular energy storage / conversion or a a modular energy storage and conversion system) that may be scalable to accommodate a variety of deployments and applications.

[0031] FIG. 4B is an illustrative side view of the hybrid thermal management system shown in FIG. 4A, where like devices have the same associated reference numbers. FIG. 4B illustratively depicts an air flow generated by HVAC 420, as indicated by arrows 470 and 475.

[0032] FIG. 4C provides an illustrative example view of the evaporator of the thermosyphon system of the hybrid thermal management system 400. As shown, each of the PE devices (e.g., 440, 445, 450, and 455) is positioned with a surface thereof in contact withevaporator 480. The PE (e.g., a printed circuit board (PCB) or other) devices may have a surface thereof attached onto the evaporator with a thermal connection (e.g., a thermal interface material, a thermal conductor, etc.) therebetween. In some embodiments, the thermal connection might include a thermal interface material to efficiently transfer heat from the PE (PCB or other) device onto the evaporator. The heat generated by the PE devices may be transferred to the coolant in the evaporator, where the coolant is heated to or above its boiling point and vaporizes. The vaporized coolant then rises and is routed to the condenser shown in FIGS. 4A and 4B via conduit 460. Liquid coolant from the condenser may be returned to the evaporator via conduit 465.

[0033] As used herein, an evaporator generally refers to a liquid containment structure constructed, at least partially, of a thermally conductive material with a thermal conductivity of about at least 0.5 W / m-K. In some embodiments, internal features of an evaporator herein may include features for uniform fluid distribution across flow channels, may have extended surfaces to improve surface area, and may include surface roughness features and other specific features for one or more of bubble nucleation, heat transfer enhancement, etc. In some embodiments, an evaporator may have at least one inlet conduit for coolant to enter the evaporator and at least one outlet conduit for the coolant to leave the evaporator, where the conduit(s) might include a material the same as or different than the evaporator material.

[0034] In some embodiments of a hybrid thermosyphon cooling system disclosed herein, an enclosure (e.g., FIGS. 4A and 4B, 405) may have feature(s) to enable natural or forced air convection cooling of auxiliary electrical / electronic components other than the electrical, electronic, and electro-chemical components cooled by the HVAC or thermosyphon cooling systems. For example, air might be drawn into the enclosure naturally or by a fan, blower, etc. through inlet conduit 430 of FIG. 4 A. The air drawn into the enclosure may circulate and encounter auxiliary components (not shown in FIGS. 4A and 4B) (i.e., electrical and electronic components other than batteries 410 and PE 440, 445, 450, and 455), thereby cooling those components. The hot air heated by the auxiliary components is exhausted through outlet conduit 435. In the case of natural convection cooling, the hot air rises within the enclosure naturally due to buoyancy and vents out of the enclosure through outlet 435 without the use of fans / blowers.

[0035] Regarding the various features of the hybrid thermal management system depicted in FIGS. 4 A, 4B, and 4C, the various devices and systems therein may be implemented to accomplish different specific tasks and functions. Accordingly, the various components may each be designed to have a range of operating capacities, values, and ranges. For example, the PE devices might include one or more of an EV DC fast charger, a grid forming inverter, a PV (photovoltaics) DC / DC optimizer, a DC / DC BPU (battery protection unit) converter, etc. The evaporator of a thermosyphon evaporator in one embodiment might include a 1 kW evaporator / converter, about 10 kW total. An example of an HVAC unit in some embodiments includes a 1.5 kW capacity unit. In some embodiments, batteries cooled by the HVAC system may include, for example, Li-ion (lithium-ion) batteries having a capacity of about 400 kWh, and a max C-rate of about 0.5. The foregoing are example capacities and values for one or more embodiments herein.

[0036] In some embodiments, a hybrid thermal management system herein including a thermosyphon system for cooling a first component set of equipment and a HVAC cooling system for cooling a second component set of equipment where the different component sets of equipment having different operating temperature ranges provides a number of useful benefits, applications, and advantages. For example, the HVAC system in a hybrid thermal management system herein may be reduced in size and capacity since it is limited to cooling a specific component set of equipment or devices, rather than an entire system. Additionally, the thermosyphon system of a hybrid thermal management system herein does not require an HVAC or a pump (or other active, energy consuming devices). As such, the energy consumption to cool the entire system may be significantly less than prior systems.

[0037] In some aspects, operating costs to cool a system may be reduced by using a hybrid thermal management system as disclosed herein.

[0038] In some embodiments and applications, a battery in a hybrid thermal management system herein (e.g., FIGS. 4 A, 4B) may be liquid cooled. In such embodiments, there may not be a need for the battery (or bank of batteries) to be enclosed or contained an inner battery compartment separate from the thermosyphon portion of the hybrid thermal management system since the liquid to cool the batteries may be contained within pipes in the vicinity of the batteries. That is, the liquid to cool the batteries is contained in a sealed system and is notfree to flow throughout the overall hybrid thermal management system enclosure like air would in an embodiment including air cooled batteries.

[0039] FIGS. 5A, 5B, and 5C are illustrative examples of a hybrid thermal management system 500 operating in different climatic environments, in accordance with some embodiments. In FIG. 5A, hybrid thermal management system 500 includes a thermosyphon system to cool PE devices 525 and a HVAC system to cool batteries 510. The thermosyphon system includes PE devices 525 mounted to an evaporator (not shown in FIG. 5 A for purposes of clarity), a condenser 520, and conduits 530, 535 to route coolant between the evaporator and the condenser. Ambient air is drawn into enclosure 505 of the hybrid thermal management system via vent 540 and exhausted out of the enclosure at vent 545. Hybrid thermal management system 500 also includes HVAC system 515 that generates and circulates cooled air over and across batteries 51 Oto cool the batteries. Note that the batteries in some embodiments of FIG. 5 A are air cooled and HVAC system and other component devices to be cooled by the HVAC system (e.g., batteries and other (auxiliary) heat generating devices) are isolated from the thermosyphon system of the hybrid thermal management system by being enclosed within an enclosure (not shown in FIG. 5 A for clarity reasons) within enclosure or housing 505.

[0040] FIG. 5 A illustrates some aspects of operating a hybrid thermal management system 500 herein where the ambient temperature range is approximately 25 degrees C to about 50 degrees C (i.e., scenario I). In this example where the batteries 510 have an operating temperature range of about 25 degrees C to about 35 degrees C, HVAC system 515 is needed since the ambient may be much hotter (e.g., 36 - 50 degrees C) outside than the operating temperature range of the batteries. Accordingly, for scenario I depicted in FIG. 5A, HVAC system 515 may operate in a HVAC cooling mode to cool the batteries to ensure the batteries are maintained at a temperature within their operating temperature range. In some embodiments, a PE system with a maximum temperature >100 C, may be cooled by thermosyphon without the need for HVAC even under hot environments.

[0041] In an instance the ambient outside is much colder at about 15 degrees C to about 25 degrees C (i.e., scenario II) as illustrated in FIG. 5B, the air for cooling batteries 510 may bypass HVAC system 515 since the ambient air may be sufficient to cool the batteries to remain within their operating temperature range. In this scenario, fresh ambient air 540 maybe received or drawn into enclosure 505 and used to cool the batteries. In some embodiments, the air drawn into the enclosure might be, for example, filtered to remove particulates therefrom or otherwise minimally processed ( e.g., dehumidified, etc.) to make it suitable for circulating within the battery compartment. In scenario II, HVAC system 515 might be operated in an economizer mode and ambient air is fed into the battery compartment for battery cooling. The PE system is cooled by thermosyphon without the need for HVAC under scenario II.

[0042] In an instance the ambient outside is even colder (e.g., about -30 degrees C to about 15 degrees C), the ambient air temperature may be too cold for directly cooling batteries 510 since the batteries have a lower operating temperature boundary than the temperature range of the ambient air in this example scenario. For example, if the air is too cold (i.e., below the operating temperature range of batteries 510), then the battery system 510 might slow or even stop functioning. Accordingly, HVAC system 515 may be operated as a heat pump. In some embodiments, electrical resistance heaters may be used where air may be heated by circulating it over the heating element of the electrical heater. In a cold climate such as that represented in scenario III depicted in FIG. 5C, the ambient air 540 brought into the enclosure 505 may be heated (e.g., by a heat pump, electrical heater, solar powered electric heater, etc.) and circulated across / through the batteries. Of note, PE units 525 generate heat so long as they are operating, whether it's summer or winter (i.e., regardless of the ambient temperature). In some instances of scenario III, the heat generated by the PE devices 525 may be directed or routed into the battery compartment (not shown in FIG. 5C for purposes of clarity) to supplement or alleviate an operational need for the heating aspects of HVAC system 515 (e.g., a heat pump, etc.) to heat the batteries in cold weather scenario III. In this example scenario, ambient air 540 may be brought into enclosure 505 and forced over the condenser 520 to cool the thermosyphon coolant. Thereafter, the air may be heated by the heat removed from the thermosyphon coolant at the condenser. Instead of discharging warmed air from the PE compartment out of the enclosure at 545 to the surrounding environment, the heat generated by the PE and transferred to the air by condenser 520 may be efficiently utilized by selectively routing it into the battery compartment (as shown in FIG. 5C by arrow 550) to heat the air that is circulating therein amongst the batteries. In this manner, heat generated by the PE may be used to heat the batteries (or other devices associated with and typically cooled by the HVAC system), thereby reducing or eliminatingthe energy needed to sufficiently heat the batteries so that the batteries are operating within their acceptable temperature range. In some instances for scenario III, air recirculated from the thermosyphon system to the battery compartment might be used to supplement or even replace the need for operating the heater of the HVAC system. The waste heat recovered from condenser 520 may be transferred to the air, water, or other coolants that are being used to cool the battery either directly, or indirectly through a heat exchanger.

[0043] In an embodiment where air flow is to be routed from the thermosyphon system to the battery compartment (e.g., FIG. 5C) an air flow control mechanism such as a damping plate, a blanking plate, a valve, or other air flow control device might be used to selectively regulate air flow from the thermosyphon system into the air cooled battery compartment. The present disclosure is not limited to any particular mechanism for directing and controlling a flow of air from the thermosyphon system to another portion of the hybrid thermal management system (e.g., a battery compartment in a system having a battery compartment). Any compatible feature, device, or mechanism suitable to direct the (warm) air either out of the system’s enclosure to the ambient environment or to direct it into the battery compartment or other parts of the system are applicable herein.

[0044] Accordingly, FIGS. 5A, 5B, and 5C illustratively demonstrate example operational features (e.g., useful applications) of a hybrid thermal management system disclosed herein across multiple different operating scenarios.

[0045] FIG. 6 is an illustrative example of a unified thermosyphon loop system 600 for multiple components, according to some embodiments. In some instances, unified thermosyphon loop system 600 may be used in one embodiment including solid state batteries. In some implementations, solid state batteries have a higher operating temperature range as compared to other types of batteries. For example, a Li-ion battery might typically have an operating temperature range of about 25 degrees C to about 35 degrees C. In some implementations, a solid-state battery might have an operating temperature range of about 60 degrees C to about 70 degrees C, typically greater than 50 degrees C. In some aspects and applications, a solid-state battery may be safer to operate compared to other types of batteries. For such batteries deployed in environments and systems having multiple different types of component devices, the cooling of the multiple different types of component devices mightbe efficiently and safely provided by a unified cooling approach provided by a unified thermosyphon loop system as exemplified in FIG. 6.

[0046] In the example unified thermosyphon system 600, a number of different heat generating component sets of equipment are shown in a housing or enclosure 605, including component set 610 including a plurality of power electronics, component set 615 including one or more solid state batteries, and component set 620 including one or more auxiliary devices (e.g., power supplies, control units, etc.). All of the heat generating component sets 610, 615, and 620 may be mounted to, interfaced with, or otherwise in thermal contact with a common evaporator 625. In some embodiments, evaporator 625 may comprise a system of one or more evaporator devices. Coolant in evaporator 625, whether the condenser is a single device or multiple devices, may be heated by heat generating component sets 610, 615, and 620 to or above its boiling point and vaporize. The vapor may be routed, via one or more conduits or pipes 630, 635, 640, and 645, to a condenser 650 located at an elevated position relative to the evaporator. The condenser, based on at least one of air cooling and liquid cooling, may cool the coolant therein sufficiently to change the vapor to a liquid. The liquid coolant may flow by the force of gravity back to the evaporator via conduit(s) or pipe(s) 655. In this manner, the heat generated by all of the heat generating component sets 610, 615, and 620 is dissipated by condenser 650 of the unified thermosyphon system 600. In some embodiments, unified thermosyphon system 600 may be utilized for a wide range (e.g., all) of ambient temperatures. In some embodiments, more than one condenser may be used, as determined by specific application requirements.

[0047] As illustrated in FIG. 6, some of the heat generating component sets include vertically stacked or configured devices. For example, heat generating component set 615 includes a plurality of batteries, where the batteries are arranged in a vertically stacked configuration. The heat generating component sets in the example thermosyphon system in FIG. 6 are also horizontally arranged or configured relative to each other. For example, each of the heat generating component sets in FIG. 6 are shown horizontally offset from the other heat generating component sets. Of note, all of the heat generating component sets are mounted to, interfaced with, or otherwise in thermal contact with common evaporator 625 having a volume of coolant therein, the evaporator is connected to condenser 650 by one or more conduits to guide vapor coolant from the evaporator to condenser 650, and the condenser is connected to evaporator 625 by one or more conduits 655 that route liquidcoolant back to the evaporator, thereby forming the example closed loop thermosyphon in FIG. 6 wherein the elevation differences in the thermosyphon loop drives the coolant flow.

[0048] In general, the heat generating component sets and devices cooled by a thermosyphon of the present disclosure may be arranged in a vertical configuration, a horizontal configuration, and combinations thereof in the disclosed thermosyphon systems.

[0049] FIG. 7 is an illustrative example of a plurality of vertically positioned heat generating devices cooled by a thermosyphon system configured for improved thermosyphon coolant flow, in accordance with some embodiments. In FIG. 7, a portion of a passive two- phase thermosyphon system is illustrated. In particular, depicted are representations of an evaporator 705, a plurality of vertically stacked heat generating component devices (e.g., batteries 705, 710, 715, 720, 725, 730, 735, 740, 745, 750, and 755), a conduit 760 connected to a condenser (not shown in FIG. 7, but located above the evaporator 705) to take vapor coolant from evaporator 705 to the condenser, and a conduit 765 to return liquid coolant from the condenser to evaporator 705. In some aspects, because of the configuration of a two- phase thermosyphon’s evaporator and condenser where the condenser is positioned at a relative higher elevation than the evaporator, the coolant flow is influenced by hydrostatic pressure due to the liquid head difference between the evaporator inlet at 765 and the return at 760.

[0050] In a vertically stacked heat source arrangement, such as vertically stacked PE units (e.g. a multi-converter arrangement) or a vertically stacked multi-battery arrangement as depicted in the example of FIG. 7, the difference in elevation of each heat generating device or module may result in changes or variations in flow rate distribution to the plurality of devices, with the uppermost device or module experiencing the lowest flow. A technical solution to address the uneven or variations in flow rate to the different heat generating devices in the vertically stacked configuration is provided herein. In some embodiments, one or more pumps, pulsed piezoelectric jets, and other types of coolant movers may be positioned internal / external to a heat source cold plate or externally positioned and actuated as a function of the flow rate, as measured by, for example, chip junction temperature.

[0051] Another technical solution to the varied flow rate problem that may be exhibited at the evaporator with vertically stacked heat generating devices in a passive two-phase thermosyphon includes the use of valves (e.g., a solenoid, a manual valve, etc.), orifices, andother controlled ob struct! on(s) 770, 775 at the flow inlet of each heat generating device or module (or a group of modules) to control the flow resistance for the modules. In some embodiments, one or more of the flow control valves, orifices, and other controlled obstruction(s) 770, 775 may be positioned at the flow inlet of a group of the heat generating devices or modules to control the flow resistance to the group of devices.

[0052] In various embodiments, the flow control mechanism(s) 770, 775 may create an obstruction either in the form of, for example, a valve, an orifice, or an electronically controlled device or system that may be controlled to dynamically change the size of the obstruction so that the amount of flow directed to each one (or group) of the vertically stacked heat generating devices at the evaporator can be selectively managed and controlled.

[0053] As an example, an orifice or valve775 might be adjusted to have higher flow resistance at the bottom of the vertical stack (e.g., battery 760) than the devices locate at the top of the vertical stack top (e.g., battery 710) to enable a more uniform flow distribution in FIG. 7. In this example, a control of the flow resistance enables an ability to redistribute the flow more evenly across the multiple, vertically stacked heat generating devices. As an example, an orifice could be adjusted to have higher flow resistance at the bottom modules than the top, to enable a more uniform flow distribution.

[0054] FIG. 8 is an illustrative example of a thermosyphon system 800 further configured for fire suppression by a liquid coolant therein, in accordance with some embodiments. Thermosyphon system 800 includes an evaporator 810 with one or more heat generating devices located thereon within enclosure 805. Evaporator 810 includes a volume of liquid coolant therein, which upon being heated to or above its threshold boiling temperature, changes from a liquid to a vapor. The vapor travels, via conduits or pipes 815 and 820, to condenser 825 that is air cooled. The air-cooled condenser functions to cool the vaporized coolant therein below its boiling point temperature and the liquid coolant is routed via conduit or pipe 830 by the force of gravity to the lower positioned evaporator 810.

[0055] In some aspects, the coolant used in thermosyphon system 800 might also be used as a fire suppressant. For example, if a temperature drives batteries (e.g., Li-ion batteries) cooled by evaporator 810 to be unsafe, there might be a risk of a fire within the system. For example, if some Li-ion batteries exceed a temperature in excess of about 60 degrees C to about 70 degrees C, then the batteries might enter a thermal runaway situation. In someembodiments, the coolant(s) used in a thermosyphon system disclosed herein may serve dual purposes. That is, the coolant can operate as a coolant in the thermosyphon system (i.e., transfer heat) and also act as a fire suppressant.

[0056] In some embodiments, thermosyphon system 800 further includes a controllable mechanism 845 that might perform or operate as a sprinkler, a valve, or otherwise as a delivery system for the coolant in the thermosyphon system. Controllable mechanism 845 may be controlled to open up and disperse the coolant within the thermosyphon system over, for example, at least a portion of the interior of the housing (e.g., the battery compartment) to mitigate a potential or actual fire condition. In one embodiment, controllable mechanism 845 may be implemented as a valve with a nozzle that opens to spray coolant (i.e., pressure is higher at the bottom of the liquid conduit / column 830) in response to an indication from one or more enclosure temperature sensors detecting an unsafe temperature, one or more smoke alarms detecting an unsafe temperature and / or smoke, a gas sensor detecting the presence of a specified gas, and other control devices and systems. In some embodiments, one or more separate reservoirs of the coolant type might be dispersed which could be released into system 800 for fire suppression or mitigation.

[0057] In some aspects, a coolant herein may act as a fire suppressant by having chemical characteristics that allow the coolant to perform efficiently as a fire suppressant in addition to being an efficient heat transfer fluid. For example, a coolant herein might include dielectric fluid such as NOVEC649 that has fire suppression properties due to its ability to cool and the coolant’s vapor is heavier than air and will thereby displace air out of the system to suppress / mitigate combustion.

[0058] Aspects of the present disclosure have been described in terms of several embodiments solely for the purpose of illustration. Persons skilled in the art will recognize from this description that the present disclosure is not limited to the embodiments described but may be practiced with modifications and alterations limited only by the spirit and scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A hybrid thermal management system, the system comprising: a thermosyphon cooling system to cool a first heat generating component set to a first operating temperature range, the thermosyphon cooling system comprising: an evaporator encompassing a volume of liquid coolant, the first heat generating component set having at least one heat generating surface thereof positioned in contact with a surface of the evaporator through a thermal interface material; a first conduit operably connected to the evaporator; a condenser positioned above the evaporator and operably connected to the first conduit; and a second conduit operably connected between the condenser and the evaporator forming a closed loop between the condenser and the evaporator, wherein during a cooling operation gravity directs the liquid coolant, via the second conduit, towards the at least one heat generating surface that causes, when a temperature threshold value of the liquid coolant is reached or exceeded, a phase change of the liquid coolant to a vapor that rises, via the first conduit, from the evaporator to the condenser that cools the vapor to cause a phase change of the vapor coolant to a liquid that moves, by force of gravity, back to the evaporator via the second conduit; and a heating, ventilation, and air conditioning (HVAC) system to cool a second heat generating component set to a second operating temperature range that is at least partially different than the first operating temperature range, the HVAC system producing at least one of chilled air and chilled coolant that flows across at least one surface of the second heat generating component set, the at least one surface of the second heat generating component set being at least one of in direct contact with the at least one of cooled air and cooled coolant and indirectly contacted by the at least one of cooled air and cooled coolant through a heat sink attached to the second heat generating component set via a thermal conductor.

2. The hybrid thermal management system of claim 1, further comprising a first housing enclosing the thermosyphon cooling system and the HVAC system.

3. The hybrid thermal management system of claim 2, further comprising a second housing within the first housing, the second housing enclosing and isolating the HVAC system from the thermosyphon cooling system.

4. The hybrid thermal management system of claim 2, further comprising an inlet vent to facilitate an inlet of air into the first housing and an outlet vent to facilitate an outflow of air out of the first housing.

5. The hybrid thermal management system of claim 3, wherein, during the cooling operation, ambient air is received into the second housing enclosing the HVAC system to at least supplement cooling of the second heat generating component set.

6. The hybrid thermal management system of claim 3, wherein, during the cooling operation, exhaust air from the condenser is received into the second housing enclosing the HVAC system to heat the second heat generating component set.

7. The hybrid thermal management system of claim 3, further comprising an air flow controller to selectively regulate air flow from the thermosyphon cooling system into the second housing enclosing the HVAC system.

8. The hybrid thermal management system of claim 1, further comprising at least one of a fan, a blower, and a pump to direct at least one of a gas and a liquid to cool the condenser.

9. The hybrid thermal management system of claim 1, wherein the first heat generating component set comprises a plurality of heat generating devices positioned vertically relative to each other and each having a heat generating surface positioned in contact with the liquid coolant.

10. The hybrid thermal management system of claim 9, wherein the heat generating surface of each of the plurality of vertically positioned heat generating devices of the first heat generating component set is provided with the liquid coolant via the first conduit operably connected to the evaporator and returns vapor to the condenser via the second conduit.

11. The hybrid thermal management system of claim 9, further comprising one or more of a fan and an air mover device to selectively control a flow of air in a vicinity of the plurality of vertically positioned heat generating devices to mitigate a temperature rise of components other than the first heat generating component set and the second heat generating component set.

12. The hybrid thermal management system of claim 10, further comprising at least one of a valve and a flow control orifice positioned to selectively control, via the first conduit, a flow rate distribution of the liquid coolant to the plurality of vertically positioned heat generating devices of the first heat generating component set.

13. The hybrid thermal management system of claim 10, further comprising at least one valve positioned near the first conduit of each of the plurality of vertically positioned heat generating devices of the first heat generating component set and operable to improve a flow rate distribution of liquid coolant to each of the plurality of vertically positioned heat generating devices.

14. The hybrid thermal management system of claim 1, wherein the liquid coolant of the thermosyphon cooling system has fire suppression properties that mitigates a combustion within the hybrid thermal management system when the liquid coolant is dispersed within the hybrid thermal management system.

15. The hybrid thermal management system of claim 14, further comprising at least one flow controller to regulate a flow of the liquid coolant from at least one of the first conduit and the second conduit.

16. The hybrid thermal management system of claim 15, wherein the at least one flow controller is actuated to direct the flow of the liquid coolant from at least one of the first conduit and the second conduit in response to a signal from at least one of a temperature sensor, a fire sensor, a smoke sensor, and a gas sensor.

17. The hybrid thermal management system of claim 1, wherein the second heat generating component set comprises a plurality of heat generating devices with at least two of the plurality of heat generating devices of the second heat generating component set being horizontally parallel relative to each other.

18. The hybrid thermal management system of claim 2, wherein the first heat generating component set comprises one or more power electronic devices and the second heat generating component set comprises one or more batteries.

19. A thermal management system, the system comprising:a thermosyphon cooling system to cool a plurality of heat generating component sets, the thermosyphon cooling system comprising: at least one evaporator encompassing a volume of liquid coolant, each of the plurality of heat generating component sets having at least one heat generating surface thereof positioned in contact with a surface of the at least one evaporator through a thermal conductor; at least one first conduit operably connected to the at least one evaporator; at least one condenser positioned above the at least one evaporator and operably connected to the at least one first conduit; and a second conduit operably connected between the at least one condenser and the at least one evaporator forming a closed loop between the at least one condenser and the at least one evaporator, wherein during a cooling operation gravity directs the liquid coolant, via the second conduit, towards the at least one heat generating surface of the plurality of heat generating component sets that causes, when a temperature threshold value of the liquid coolant is reached or exceeded, a phase change of the liquid coolant to a vapor that rises, via the at least one first conduit, from the at least one evaporator to the at least one condenser that cools the vapor to cause a phase change of the vapor coolant to a liquid that moves, by force of gravity, back to the at least one evaporator via the second conduit.

20. The thermal management system of claim 19, further comprising a first housing enclosing the at least one evaporator and the plurality of heat generating component sets.

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