Wearable thermal management system with convective heating

Abstract

A personal thermal management device includes an outer layer and an inner layer, defining an interior zone with higher pressure and an air-recirculation zone with lower pressure. The device includes a fan that draws air from the lower-pressure zone and delivers it into the higher-pressure zone, where an electrical heater heats the air. The heated air is then released into the lower-pressure zone through an exhaust vent. The device also includes a temperature sensor and circuitry to regulate and dynamically adjust the temperature, fan speed, and heating power based on environmental conditions and user activity. Additionally, the device features a battery integrated within either the outer or inner layer to supply power to the electrical heater and fan.

Description

Docket No. 503488.70001WEARABLE THERMAL MANAGEMENT SYSTEM WITH CONVECTIVE HEATINGRELATED APPLICATION

[0001] This application claims priority benefit of U.S. Provisional Patent Application No.63 / 743,612 filed January 9, 2025, which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] This disclosure generally relates to heating devices for garments and, more particularly, to fan-based heating systems.BACKGROUND INFORMATION

[0003] Patent Application Publication No. US2021 / 0127762A1, titled “Temperature Controlled Garment Assembly,” describes a wearable jacket designed to regulate the temperature of the wearer. The jacket incorporates a system of conduits through which air is circulated by a blower. This air can be heated or cooled to achieve the desired temperature control. The system is designed to be worn by a user, providing a controlled internal environment to enhance comfort in various external conditions.SUMMARY OF THE DISCLOSURE

[0004] This disclosure describes a plenum vest for active heating of a human torso. The plenum vest is a wearable device configured to be worn inside an outer garment, such as a jacket, and over a thin inner layer, such as a T-shirt or long-sleeve shirt. A practical benefit of the plenum vest is that it may be used with a wide variety of existing outer garments. There is no requirement for a specially designed jacket or outer layer to take advantage of the enhanced warmth provided by the vest.

[0005] Innovations in the plenum vest enable a higher capacity of heating and more uniform heating than other heated garments. The design enables a high heat input that is distributed uniformly over the wearer’s torso while maintaining comfort and wearability. The plenum vest actively heats the upper body by circulating warm air within an internal plenum formed inside the vest. One or more fans move air through electrical heating elements and into the internal plenum, where the moving air distributes heat over a large surface area. Convective heat transfer provided by the circulating air produces more uniform heating than existing heated garments that rely on electrical resistance elements embedded in fabric, which typically heat only localized regions.1503488\70001\FG: 104703455.1Docket No. 503488.70001

[0006] The disclosed embodiments address several technical challenges associated with wearable heating devices. These include making the device wearable and comfortable, achieving uniform heating across the wearer’s torso, and maintaining heating performance when the vest is subjected to external loads that might otherwise collapse internal airflow passages. The plenum structure allows airflow to be maintained and redistributed even when portions of the vest are compressed.

[0007] In operation, a user selects a temperature setpoint, and a feedback control system adjusts the heating rate and fan speed to maintain the selected temperature. The control system dynamically responds to changes in user activity, ambient environmental conditions, and user-adjusted setpoints. In contrast, many existing heated garments operate with a limited number of discrete power settings and do not automatically adapt to changing conditions or user activity.

[0008] In one aspect, a personal thermal management device is provided for placement between a user’s torso and an over garment. The personal thermal management device includes an outer layer and an inner layer, the outer layer and the inner layer defining therebetween an interior zone configured as a higher-pressure plenum, and the outer layer and an interior surface of the over garment defining an air-recirculation zone configured as a lower-pressure plenum. A fan is coupled to an intake opening between the air-recirculation zone and the interior zone, the fan being configured to draw air from the lower-pressure plenum and deliver it into the higher-pressure plenum. An electrical heater is positioned downstream of the fan to heat the air drawn from the lower-pressure plenum, thereby supplying heated air into the higher-pressure plenum. An exhaust vent opening extends from the interior zone into the air-recirculation zone, the exhaust vent opening being configured to release heated air flowing from the higher-pressure plenum into the lower-pressure plenum. A temperature sensor and associated circuitry are configured to regulate the temperature of the heated air based on an adjustable setpoint, and the circuitry is further configured to dynamically adjust fan speed and heating power in response to environmental conditions and user activity. A battery is integrated within at least one of the outer layer or the inner layer, the battery being configured to supply power to the electrical heater and the fan.

[0009] In some embodiments, increased pressure of the higher-pressure plenum maintains an increased amount of surface area of contact between the user’s torso and the inner layer. In some embodiments, the device includes a set of air vents positioned on the outer layer, and the air vents are configured to control flow and distribution of heated air into the air-2503488\70001\FG: 104703455.1Docket No. 503488.70001recirculation zone to customize localized heating across different areas of the user’s torso. In some embodiments, the fan and the electrical heater are housed in a modular assembly positioned within a central region of the interior zone, the modular assembly being configured to optimize airflow distribution throughout the higher-pressure plenum. In some embodiments, the temperature sensor is positioned within the air-recirculation zone to measure a temperature of circulating heated air after the air is released from the exhaust vent.

[0010] In some embodiments, the fan is configured to operate at variable speeds, and the associated circuitry dynamically adjusts the fan speed and power to one or more internal heat exchangers based on feedback from the temperature sensor to maintain a user-selected setpoint temperature. In some embodiments, the battery is a removable and rechargeable power pack integrated into a compartment within the outer layer, the power pack being configured to be accessed by the user for replacement or recharging. In some embodiments, the inner layer includes a soft, compliant material to enhance comfort and reduce thermal contact resistance between the user’s torso and the interior zone. In some embodiments, the device includes a wireless communication module integrated into the circuitry, the wireless communication module being configured to communicate with an external device to allow a user to adjust heating settings remotely through a smartphone or smartwatch application.

[0011] In some embodiments, the fan and electrical heater are operated under a control algorithm implemented by the circuitry, the control algorithm being configured to adjust heating power and airflow rate based on user activity levels detected by motion sensors within the personal thermal management device. In some embodiments, the exhaust vent includes multiple exit points distributed across the outer layer, the exit points being configured to release heated air across the user’s torso to avoid localized overheating. In some embodiments, the exhaust vent includes user-adjustable flaps configured to open or close exit points to control flow of heated air based on user preference. In some embodiments, the outer layer is made of a waterproof and wind-resistant material to protect the interior zone and electrical components from environmental exposure. In some embodiments, the inner layer and outer layer are joined by seam-sealed stitching (or heat welding) to maintain pressurization of the higher-pressure plenum during operation.

[0012] In some embodiments, the device includes an impact-resistant cover positioned over a fan intake to prevent accidental blockage of the fan and to protect the fan from external objects. In some embodiments, the fan is a dual-fan assembly, and in some embodiments each fan of the dual-fan assembly operates independently from the other fan3503488\70001\FG: 104703455.1Docket No. 503488.70001to provide redundancy. In some embodiments, the outer layer comprises a rigid, impactresistant shell made of a polymer composite material to protect internal components from external forces. In some embodiments, the device includes a digital display integrated into the outer layer, the digital display being configured to show a current or setpoint temperature, fan speed, and battery status. In some embodiments, the fan and electrical heater are housed in a modular compartment that is removable for maintenance or replacement. In some embodiments, the circuitry is further configured to operate in a ventilation mode in which the fan circulates air through the higher-pressure plenum while the electrical heater is deactivated, thereby promoting convective cooling and moisture removal from the user’s torso.

[0013] In another aspect, a personal thermal management system is provided. The system includes a portable thermal management unit configured to be worn by a user within an over garment. The portable thermal management unit includes a fan configured to move air, an electrical heater configured to heat air moved by the fan, and control circuitry configured to control the fan and the electrical heater. The system further includes a power source configured to supply electrical power to the portable thermal management unit, and a user interface configured to receive user input for controlling operation of the portable thermal management unit. The control circuitry is configured to operate the fan and the electrical heater based on the user input and activity data indicative of user activity.

[0014] In some embodiments, the power source comprises a Universal Serial Bus Power Delivery (USB-C PD) power source. In some embodiments, the power source is configured to provide up to at least approximately 100 watts to the portable thermal management unit, and in some embodiments the power source is configured to provide more than 100 watts to the portable thermal management unit. In some embodiments, the system includes a wearable activity monitoring device communicatively coupled to the control circuitry, and in some embodiments the wearable activity monitoring device comprises a smart watch. In some embodiments, the activity data includes one or more of heart rate, motion, step rate, exertion level, or metabolic estimate. In some embodiments, the control circuitry is configured to adjust at least one of fan speed or heater power in response to changes in the activity data.

[0015] In some embodiments, the user interface is configured to receive a user-selected power level, and the control circuitry maps the user-selected power level to at least one operating parameter including fan speed, heater power, or a limit on fan speed or heater power. In some embodiments, the control circuitry is configured to operate in a ventilation4503488\70001\FG: 104703455.1Docket No. 503488.70001mode in which the fan is activated and the electrical heater is deactivated, and the control circuitry is configured to enter the ventilation mode in response to the activity data indicating increased user activity. In some embodiments, the control circuitry is configured to select an operating combination of fan speed and heater power to increase perceived thermal comfort while reducing electrical power consumption relative to increasing heater power alone. In some embodiments, the portable thermal management unit is configured to be positioned between an inner garment and the over garment and to direct heated air within a volume defined at least in part by the over garment.

[0016] In another aspect, the disclosure provides a method performed by a wearable thermal management device configured to be worn between a user’s torso and an over garment. The method includes operating a fan to draw air from a lower-pressure airrecirculation zone surrounding the wearable thermal management device and delivering the air into a higher-pressure plenum defined within the wearable thermal management device. The method further includes heating the air using an electrical heater positioned downstream of the fan and exhausting the heated air from the higher-pressure plenum into the lower-pressure air-recirculation zone to establish a circulating airflow path between the device and the over garment.

[0017] In some embodiments, the method further includes regulating a temperature of the circulating air based on an adjustable temperature setpoint. Regulating the temperature may include dynamically adjusting at least one of fan speed or heating power using control circuitry of the wearable thermal management device. In some embodiments, the method includes receiving temperature data from one or more temperature sensors positioned within the wearable thermal management device and adjusting operation of the fan or the electrical heater based on the temperature data.

[0018] In some embodiments, the method further includes receiving activity data indicative of user activity from a wearable activity monitoring device communicatively coupled to the wearable thermal management device, such as a smart watch. The activity data may include one or more of heart rate, motion, step rate, exertion level, or metabolic estimate. Operation of at least one of the fan or the electrical heater may be modified in response to changes in the activity data.

[0019] In some embodiments, the method further includes receiving a user-selected operating level via a user interface of the wearable thermal management device and mapping the user-selected operating level to one or more operating parameters, including fan speed, heating power, or limits thereon. In some embodiments, the method includes 5503488\70001\FG: 104703455.1Docket No. 503488.70001operating the wearable thermal management device in a ventilation mode by activating the fan while deactivating the electrical heater, and the ventilation mode may be entered automatically in response to activity data indicating increased user activity.

[0020] In some embodiments, the method further includes supplying electrical power to the wearable thermal management device from a power source compliant with a Universal Serial Bus Power Delivery specification. Supplying electrical power may include supplying up to at least approximately 100 watts, or in some embodiments supplying more than 100 watts. In some embodiments, the method further includes selecting an operating combination of fan speed and heating power that maintains a target temperature range while reducing electrical power consumption relative to increasing heating power alone.

[0021] In another embodiment, a method of personal thermal management is provided that is performed by a wearable thermal management device configured to be worn between a user’s torso and an over garment. In this embodiment, the method includes operating a fan to move air within a region defined between the wearable thermal management device and the over garment. The method further includes heating the air using an electrical heater associated with the wearable thermal management device and directing the heated air along a flow path adjacent the user’s torso. The heated air is exhausted from the wearable thermal management device to promote circulation of air within the over garment, thereby providing convective thermal regulation of the user without requiring the air to be confined within a sealed duct or pressurized plenum. This embodiment enables effective heating and air circulation within a garment while allowing flexibility in device structure, airflow paths, and garment configuration.

[0022] Additional aspects and advantages will be evident from the following detailed description of embodiments, taken in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0023] To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced.

[0024] FIG. l is a front elevation view showing an outward appearance of a wearable thermal management system in the form of a plenum vest, including intake openings and exhaust openings, and indicating a representative direction of airflow through the vest during operation, with arrows depicting airflow drawn into the vest through fan intakes and discharged through exhaust openings, and with a dash-dot outline representing an inner surface of an outer garment, such as a jacket, worn over the plenum vest.6503488\70001\FG: 104703455.1Docket No. 503488.70001

[0025] FIG. 2 is an annotated front elevation view showing electrical and mechanical components for heating, airflow, and control of the wearable thermal management system of FIG. 1, with an outline of the plenum vest shown in phantom lines to illustrate internal component placement, including fan-heater assemblies, power and control electronics, a battery, and representative locations of temperature sensors used for feedback control, in which sensors Ti and T2 are positioned near fan inlets and sensors T3 and T4 are positioned within an internal plenum region toward a back of the vest.

[0026] FIG. 3 is a side elevation view showing a wearable thermal management system in the form of a plenum vest annotated with callouts identifying airflow and heat-transfer features during operation, in which arrows indicate circulation of heated air within an internal plenum, and a dashed outline represents an inner surface of an outer garment, such as a jacket, worn over the vest.

[0027] FIG. 4 is a rear elevation view showing three scenarios in which dynamic airflow rerouting occurs within an internal plenum of the plenum vest in response to localized compression against a back of a wearer, in which arrows indicate airflow paths within the internal plenum and airflow exiting the vest is omitted for clarity.

[0028] FIG. 5 is a simplified block diagram illustrating an airflow system of the plenum vest, showing circulation of air from a jacket space through a fan, diffuser, and heating element into an internal plenum and back to the jacket space through exhaust openings, with associated power control, battery, and communication and logic components shown schematically.

[0029] FIG. 6 is a graphical chart showing a balance point at which a fan curve and a system curve intersect to define matching values of pressure change (Ap) and volumetric flow rate (Q) for an airflow system of the plenum vest.

[0030] FIG. 7 is a graphical chart showing dependence of a system balance point on opening diameter for a plenum vest having a fixed number of openings and a representative fan, in which intersections between a fan curve and corresponding system curves indicate balance points at different flow rates and pressure differences.

[0031] FIG. 8 is a graphical chart showing dependence of a system balance point on a number of openings for a plenum vest having openings of a fixed diameter, in which intersections between a fan curve and corresponding system curves indicate balance points at different flow rates and pressure differences for the airflow system.7503488\70001\FG: 104703455.1Docket No. 503488.70001

[0032] FIG. 9 is a front elevation view of a wearable device, such as a smart watch, displaying a user interface for controlling and monitoring operation of the plenum vest, including a target temperature and system status information.

[0033] FIG. 10 is a front elevation view of a mobile device, such as a smart phone, displaying a user interface for controlling and monitoring operation of the plenum vest, including adjustment of a target temperature and presentation of operating status.

[0034] FIG. 11 is a pictorial view illustrating operation of the plenum vest during a first activity condition associated with low metabolic heat generation, in which a control interface indicates a target temperature and a relatively high power output.

[0035] FIG. 12 is a pictorial view illustrating operation of the plenum vest during a second activity condition associated with high metabolic heat generation, in which the control interface indicates the same target temperature and a reduced power output relative to FIG.11.

[0036] FIG. 13 is a pictorial view illustrating operation of the plenum vest during a third activity condition associated with moderate metabolic heat generation, in which the control interface indicates the same target temperature and an increased power output relative to FIG. 12.

[0037] FIG. 14 is a front elevation view showing an alternative embodiment of a wearable thermal management system configured as a rugged vest, illustrating a reinforced outer shell, integrated air intake and exhaust features, adjustable straps, and internal airflow paths for circulating heated air across a wearer’s torso.

[0038] FIG. 15 is a rear elevation view of the wearable thermal management system of FIG. 14, illustrating exhaust vent locations and airflow paths associated with the internal plenum.

[0039] FIG. 16 is a laid-flat planar exterior view of the wearable thermal management system of FIG. 14, showing both front and back exteriors of the vest and including exploded detail views illustrating shell components, integrated airflow features, and representative textile layers and panels used in different regions of the vest.

[0040] FIG. 17 is a laid-flat planar interior view of the wearable thermal management system of FIG. 14, showing both front and back interior of the vest and including exploded detail views illustrating shell components, integrated airflow features, and representative textile layers and panels used in different regions of the vest.8503488\70001\FG: 104703455.1Docket No. 503488.70001

[0041] FIG. 18 is a flow chart of a process performed by a wearable thermal management device configured to be worn between a user’s torso and an over garment in accordance with one embodiment.DETAILED DESCRIPTION OF EMBODIMENTS

[0042] FIG. 1-FIG. 3 shows three views of a wearable thermal management system 100 in the form of a plenum vest 102, according to one embodiment. Plenum vest 102 combines inner and outer textile surfaces with electrical and mechanical components that supply and control the heating effect. In FIG. 1, vest 102 appears as it would while a person wears it (absent the human form), similar to a common fleece vest, but with intake holes and exhaust vents. In FIG. 2, plenum vest 102 is shown in phantom lines to illustrate its internal heating components and controls. The primary heating functions of the plenum vest are described in this section and depicted graphically in FIG. 3.

[0043] With reference to FIG. 1, wearable thermal management system 100 is designed for placement between a user’s torso and an over garment (FIG. 3). In this example, vest 102 is constructed from two layers of textile materials that are impermeable or semipermeable to airflow.

[0044] Wearable thermal management system 100 includes an outer layer 104 and an inner layer 106. Outer layer 104 and inner layer 106 define therebetween an interior zone 108 (see also, FIG. 3) configured as a higher-pressure plenum 110. A plenum refers to an enclosed space, cavity, or chamber that is filled with air or another gas under pressure. In the context of heating, a plenum is a component that helps distribute air evenly and efficiently. Outer layer 104 and an interior surface of the over garment (not shown) define an air-recirculation zone 112 configured as a lower-pressure plenum 114 (see also FIG. 3). (The dash-dot curve surrounding plenum vest 102 in FIG. 1 represents the inner surface of a jacket worn outside of plenum vest 102.)

[0045] As explained below with reference to FIG. 2 and FIG. 3, an intake opening 116 is provided between air-recirculation zone 112 and interior zone 108. Intake openings 116 in the lower front sections of plenum vest 102 are aligned with the inlet to the fans.

[0046] Likewise, an exhaust vent opening 118 is provided from interior zone 108 into airrecirculation zone 112. Exhaust vent opening 118 is configured to release the heated air flowing from higher-pressure plenum 110 into lower-pressure plenum 114. Exhaust vent opening 118 on an outer surface of vest 102 are relatively small holes grouped in patterns to provide optimal air release from higher-pressure plenum 110. The grouping also allows for seam sealing and fabrication processes that integrate the vent holes into the soft external 9503488\70001\FG: 104703455.1Docket No. 503488.70001fabric. Note that the location and number of exhaust vents in FIG. 1 are only suggestive. For example, vents are located on the back of the vest, which is not visible in the images in FIG.1.

[0047] FIG. 1 uses arrows to indicate how air circulates when its heating system is running. Air is pulled into a fan / heater assembly (see e.g., FIG. 2) through intake openings 116 in the lower front panels of plenum vest 102. Fans force air through heating elements immediately downstream of the fan exit. The flow of warm air leaving the heating elements increases the air pressure in higher-pressure plenum 110. When the air leaves through exhaust vent opening 118, it returns to intake opening 116 by traveling through the air space between plenum vest 102 and the outer jacket (i.e., lower-pressure plenum 114). The jacket air space thereby acts as the return plenum, and the air space in inflated plenum vest 102 acts as a supply plenum. The inflation of plenum 110 and controlled exit of air through exhaust vent opening 118 are described in greater detail below with reference to an engineering model (FIG. 5-FIG. 8) for the air circulation in plenum vest 102 and surrounding jacket space.

[0048] Not shown in FIG. 1 are features that improve the wearability of the vest, and that are unique to vest 102 because of the heating function. The inner and outer materials of the vest have very low permeability to air. For user comfort, those materials are also chosen to be soft and compliant. Straps across the user’s chest secure the two sides of the vest while allowing the user to adjust the fit against their body.

[0049] FIG. 2 shows internal heating system components 202, controls 204, and power components for wearable thermal management system 100 with plenum vest 102. In this example, the phantom lines indicate that electrical and mechanical components are located between inner layer 106 and outer layer 104 of plenum vest 102 and are not visible on a person wearing it. Rectangles also depict printed circuit boards (PCBs) for sensing, communication and logic, and power control. Control circuitry may be implemented on one or more circuit boards, within a system-on-chip, or distributed across multiple electronic components. As used herein, circuitry refers to one or more electronic components, which may include processors, microcontrollers, application-specific integrated circuits, programmable logic, memory, and associated firmware or software, configured to perform control, communication, and signal-processing functions.

[0050] Vest 102 has internal structures to support the components depicted in FIG. 2. For instance, wire containment and routing are part of the structural support. Intake openings 116 have rigid covers that prevent the user from accidentally touching the moving fan 10503488\70001\FG: 104703455.1Docket No. 503488.70001wheels, and that prevent blockage of the intake air flow by the outer jacket or other loose clothing worn outside of the vest. Moreover, the intakes are angled and designed such that they do not choke on a outerwear liner. The stitching is seam sealed so that air leaves pressurized internal higher-pressure plenum 110 through the discrete exhaust vent openings 118 or through semipermeable sections of inner layer 106 and outer layer 104 of plenum vest 102.

[0051] FIG. 2 shows a fan 206 is coupled to intake opening 116 between air-recirculation zone 112 and interior zone 108. Fan 206 is configured to draw air from lower-pressure plenum 114 and deliver it into higher-pressure plenum 110.

[0052] An electric heater 208 is positioned downstream of fan 206 to heat the air drawn from lower-pressure plenum 114, thereby supplying heated air into higher-pressure plenum 110.

[0053] A temperature sensor 210 and associated temperature control circuitry 212 are configured to regulate the temperature of the heated air based on an adjustable setpoint. FIG. 2 shows other optional locations for temperature sensors at one or more Ti, T2, T3, and T4 locations. For example, four temperature sensors are used for feedback control. Each weight factor can be adjusted by the user to influence which areas of their body most strongly affect system response, and hence overall comfort, as explained in greater detail below.

[0054] Temperature control circuitry 212 is further configured to dynamically adjust one or both of the fan speed and heating power in response to environmental conditions and user activity. User interaction with the control system may be provided through integrated controls or through external devices, as described below with reference to FIG. 9-FIG. 13. For instance, temperature control circuitry 212 uses signals from temperature sensors 210, the user’s desired setpoint, and a feedback control algorithm to determine the appropriate heater power level and fan speed. In some embodiments, a temperature sensor is moveable about inner layer 106 or outer layer 104. The temperature control system is discussed in greater detail below.

[0055] Communication and logic circuitry 214 may also support a physical connection for an optional tethered remote control. For instance, communication and logic circuitry 214 also manages a user interface 216 for the wearer of plenum vest 102. Communication and logic circuitry 214 may support BLE for a wireless link to the user’s phone 218 or watch 220. Thus, controls 204 optionally include a smart watch interface 222 (see e.g., FIG. 9) and a smart phone interface 224 (see e.g., FIG. 10).11503488\70001\FG: 104703455.1Docket No. 503488.70001

[0056] A battery 226 is integrated within at least one of outer layer 104 or inner layer 106. Battery 226 is configured to supply power to electric heater 208 and fan 206. In some embodiments, battery 226 is removable from wearable thermal management system 100 and portable for charging.

[0057] Power management circuitry 228 draws power from battery 226 and directs it to fans 206 and heating elements 208, and it supplies power to communication and logic circuitry 214. The power drawn by communication and logic circuitry 214 is typically a fraction of the power supplied to fans 206 and electric heaters 208.

[0058] FIG. 3 illustrates how plenum vest 102 distributes a thermal effect over a wearer’s torso when the source of warm air is one or more discrete convection heaters. The plenum formed between the inner and outer layers of the vest functions as a ductless air distribution structure that allows heated air to spread throughout the vest rather than following predefined flow paths. As a result, warmth is delivered to a broad area of the torso rather than being localized near the heater assemblies.

[0059] The dashed line surrounding plenum vest 102 in FIG. 3 represents an inner surface 302 of an outer garment, such as a jacket, worn over the vest. The space between the outer surface of the vest and the inner surface of the jacket provides a return region for circulated air. Any conventional jacket may serve this function.

[0060] The callout labels A-E in FIG. 3 identify airflow and heat-transfer effects that contribute to the effectiveness and efficiency of the plenum vest.

[0061] A+B: Warm air exiting the heater assembly fills higher-pressure plenum 110 formed between the inner and outer layers of the vest. The circulating air distributes warmth over regions of the torso that are in contact with the inner layer. Convective heat transfer from the moving air spreads thermal energy uniformly, reducing localized hot spots and improving wearer comfort. By distributing heat over a large surface area, the plenum vest is capable of delivering a relatively high total heat transfer rate while maintaining a low local heat flux.

[0062] By way of example, a nominal heat transfer of approximately 100 W distributed over the median torso area of an adult female corresponds to an average heat flux of approximately 157 W / m2. For a median adult male, the corresponding heat flux is approximately 137 W / m2. For comparison, direct solar irradiance on a clear day is on the order of 1 kW / m2, such that the representative vest heat flux is well below typical environmental exposure levels. The assumptions and calculations underlying these estimates are discussed below in connection with heat-flux considerations.12503488\70001\FG: 104703455.1Docket No. 503488.70001

[0063] To achieve a comparable total heat transfer rate using conventional heated garments that rely on embedded resistive elements, substantially higher local heat flux would be required because such elements typically cover only a fraction of the torso area. The plenum vest therefore enables higher overall heating capacity while maintaining safe and comfortable heat-flux levels.

[0064] C: The layer of warm air within the plenum transfers heat to the wearer wherever the inner surface of the vest contacts the body or an intervening thin garment. Although the plenum vest employs convective heating, the final stage of heat transfer to the wearer occurs primarily through conduction across thin material layers between the circulating air and the skin. This conductive heat transfer is driven by the temperature difference between the warmed air in the plenum and the relatively cooler surface of the wearer’s body.

[0065] Operation of the fans produces a pressure difference between the internal plenum and the surrounding environment, for example on the order of approximately 10 mm H2O in some embodiments. This pressure differential causes the plenum to inflate slightly, urging the inner layer of the vest toward the wearer’s torso. Increased contact area between the vest and the body reduces thermal contact resistance and enhances heat transfer effectiveness.

[0066] D: Openings formed in the outer layer of the vest allow warm air to flow from the internal plenum into the space between the vest and the outer garment. The number, size, and placement of these openings are selected to promote airflow throughout the plenum rather than concentrating flow near the heater assemblies.

[0067] First, the placement of openings influences airflow direction within the plenum. Openings positioned farther from the fan inlets, in combination with positive internal pressure, encourage airflow to reach regions of the torso that are distant from the heater assemblies.

[0068] Second, the total number of openings is selected to maintain a minimum internal plenum pressure while permitting sufficient airflow. Maintaining internal pressure enables airflow to reroute dynamically when portions of the vest are locally compressed, as further illustrated and explained in connection with FIG. 4-FIG. 8.

[0069] Third, in some embodiments, one or more openings may be provided with user-adjustable flaps or covers that allow the wearer to modify airflow distribution and localized heating. This adjustability accommodates differences in body shape, clothing configuration, and user preference.

[0070] E: The space between the outer surface of the plenum vest and the inner surface of the outer garment forms a lower-pressure return region that conveys air back to the fan 13503488\70001\FG: 104703455.1Docket No. 503488.70001inlets. Warm air circulating in this return region provides an additional thermal buffer that reduces heat loss from the wearer and enhances overall comfort.

[0071] The following analysis provides estimates of heat flux experienced by a human wearing a plenum vest as described herein. The purpose of this analysis is to place the heating capability and thermal safety of the plenum vest in context. The models presented are illustrative and are not intended to represent high-precision physiological or thermal predictions.

[0072] The analysis begins by estimating the surface area of an adult human torso, which provides an approximate area over which heat exchange occurs between the plenum vest and the wearer. The capacity of commonly available portable power supplies is then used to bound the maximum thermal power delivered by the vest. From the estimated torso area and available power levels, representative heat flux values are computed. These estimates demonstrate that relatively high total heating power can be safely delivered when the heat is distributed over a large area of the torso.

[0073] Human body size and shape vary significantly. For purposes of estimation, body surface area (BSA) may be approximated using the Du Bois body surface area model, originally described by Du Bois and Du Bois in A Formula to Estimate the Approximate Surface Area if Height and Weight Be Known (Archives of Internal Medicine, 1916). The model expresses BSA as a function of body mass and height according to:BSA = (O.OO7184)(W°'425)(H0'725) (Equation 1)where BSA is the total body surface area in square meters, W is body mass in kilograms, and H is height in centimeters.

[0074] Representative anthropometric values for adults aged 20 years and older may be obtained from published data of the U.S. Department of Health and Human Services (Anthropometric Reference Data for Children and Adults: United States 2015-2018). Using median values from that dataset, representative body dimensions are approximately:Female: W-73.1 kg, H-161.3 cm; Male: W-87.4 kg, H-175.4 cm.

[0075] Applying Equation 1 yields approximate total body surface areas of Female: BSA ~ 1.77 m2; Male: BSA ~ 2.03 m2. The surface area of the torso represents a fraction of total body surface area. Using commonly accepted medical conventions for estimating surface area distribution across body regions, including the Wallace Rule of Nines as described in Wallace, The Exposure Treatment of Burns (The Lancet, 1951), the torso may be approximated as approximately 36% of total body surface area, with the upper torso comprising approximately 18%.14503488\70001\FG: 104703455.1Docket No. 503488.70001

[0076] Based on these conventions, representative torso surface areas are approximately: Female torso: 0.64 m2(upper torso ~ 0.32 m2); Male torso: 0.73 m2(upper torso ~ 0.37 m2). These values are used for estimating representative heat flux levels and are non-limiting.

[0077] At a system level, the rate of heat transfer Qbfrom the plenum vest to the wearer may be expressed as:Qb = ^Pin (Equation 2)where Pinis the electrical power supplied to the heating system and iy is an efficiency factor less than unity that accounts for heat losses to the environment, such as through the outer garment. For example, if approximately 10% of the supplied power is lost to the ambient environment, then r « 0.9.

[0078] The efficiency factor r / depends on variables such as outer garment insulation, airflow conditions, and ambient temperature. Introducing iy < 1 provides a conservative representation of heat delivered to the wearer and adds a margin of safety when estimating maximum heat flux.

[0079] In some embodiments, the maximum heating power supplied to the plenum vest is limited by the power source used to energize the device. In one example, the plenum vest is powered using a USB-C Power Delivery (USB-C PD) power source (USB Implementers Forum, USB Power Delivery Specification). Under the USB-C PD standard, commonly available portable power supplies are capable of delivering up to approximately 100 W of continuous power (for example, 20 V at 5 A). In some embodiments, extended USB-C PD power ranges may support delivery of up to approximately 240 W (for example, 48 V at 5 A), which may be used in higher-power or future implementations.

[0080] The foregoing power values are provided by way of example and do not limit the plenum vest to any particular power delivery standard or maximum power level.

[0081] Heat flux q is defined as the heat transfer rate per unit area and may be expressed as:(Equation 3)where Atis the surface area of the torso over which the heat is transferred.

[0082] For purposes of estimation, the entire torso area may be considered available for heat transfer. This assumption is not restrictive, as using larger effective areas results in lower estimated heat flux and therefore provides conservative upper bounds.15503488\70001\FG: 104703455.1Docket No. 503488.70001

[0083] An advantage of the plenum vest is that thermal energy is distributed over a large area of the wearer’s torso, allowing relatively high total heat input without producing excessive local heat flux.

[0084] Using the representative torso areas described above, delivery of approximately 100 W of heating power results in average heat flux values on the order of: approximately 150— 160 W / m2over a full female torso, and approximately 135-140 W / m2over a full male torso.

[0085] If heating power is concentrated primarily on the upper torso, representative heat flux values increase accordingly. For example, delivery of approximately 240 W to the upper torso of a median-sized adult female yields an estimated heat flux of approximately 750 W / m2.

[0086] For comparison, direct solar radiation incident on a surface oriented normal to the sun on a clear day is approximately 1000 W / m2(standard insolation reference). Even the highest estimated heat flux values described above remain below this reference level. In typical operation, heat flux values are lower due to distribution over areas larger than the upper torso and due to heat losses to the environment as represented by Equation 2.Accordingly, the plenum vest is capable of delivering substantial thermal power while maintaining heat flux levels consistent with user comfort and safety.

[0087] With reference to FIG. 4, plenum vest 102 is also capable of dynamic air rerouting. Convective delivery of warmth is enabled by the plenum design. During development of the plenum vest, several design iterations employed discrete ducts to direct air away from the fan / heater subsystem to regions such as the back and shoulders of the wearer.

[0088] A system design based on discrete ducts has two primary limitations. First, a discrete duct system delivers warm air only along predetermined flow paths. Second, when an external object such as a backpack or seat back applies an inward-directed force, a collapsed duct may cease to distribute air. Using rigid materials to prevent duct collapse can increase bulk and stiffness, which may reduce wearer comfort.

[0089] The plenum design addresses both of these limitations. Unlike a system of discrete ducts, the plenum provides airflow over substantially the entire torso area covered by the inner layer of the vest. In some embodiments, the outer layer is deformable and may contact the inner layer. Discrete openings formed in the vest layers provide exit paths for airflow. As a result, airflow direction is governed by the combination of a lightly pressurized internal plenum and the placement of exit openings, rather than by fixed flow paths defined by ducts.16503488\70001\FG: 104703455.1Docket No. 503488.70001

[0090] Further, because the plenum acts as a unified supply of warm air, localized compression affects only the compressed region. Pressure within the plenum causes airflow to reroute around the compressed area and continue to circulate. FIG. 4 illustrates several scenarios in which dynamic airflow rerouting occurs when a portion of the internal plenum is constricted. Although the illustrated examples show constrictions at the back of the wearer, similar rerouting occurs when constrictions arise at the sides or front of the vest.

[0091] The plenum design also provides additional benefits compared to designs that use distinct ducts to distribute air. To drive airflow through the plenum space, the fan / heater subassembly maintains the internal plenum at a positive pressure relative to the jacket air space, for example on the order of approximately 10 mm H2O in some embodiments. This pressure difference, in combination with the compliant textile material of the inner layer, causes the inner layer to press gently against the wearer’s torso. In addition to reducing thermal contact resistance, the resulting conforming contact may be perceived by the wearer as comfortable. The benefit of increased torso contact is also discussed above in connection with heat-flux considerations.

[0092] Compared to a discrete duct design, the plenum vest provides a layer of warm air distributed over a larger area of the wearer’s torso. The comfort benefits of the plenum vest may be associated with two complementary heat-transfer mechanisms. When the wearer is chilled, or when the vest is first activated, heat input from the vest increases the temperature of the wearer’s inner garment and skin. In this condition, the net heat flow is inward, from the vest toward the wearer, thereby alleviating the sensation of cold.

[0093] In steady-state operation, after the wearer is no longer chilled, the layer of warm air within the internal plenum acts as an insulating layer between the torso and the outer garment. In testing, users tend to prefer a setpoint temperature in steady-state operation that is lower than body surface temperature, for example less than approximately 37°C (98.6°F). Under these conditions, the wearer experiences a reduced rate of heat loss compared to the absence of the vest, balancing metabolic heat generation and contributing to thermal comfort. In this scenario, the net heat flow is outward, from the wearer to the ambient environment, but at a reduced and comfortable rate.

[0094] In practical use, both effects (adding heat when the wearer is chilled and reducing heat loss during steady-state conditions) may contribute simultaneously to wearer comfort. Comfort is therefore not limited to a single mode of operation, and may be achieved by selectively adding warmth to more exposed regions, such as the neck, while reducing heat loss from other regions, such as the back.17503488\70001\FG: 104703455.1Docket No. 503488.70001

[0095] Plenum vest 102 and other embodiments described herein operate as airflow systems 500 composed of two interacting subsystems: (i) one or more fans 206 that impart energy to the airflow, and (ii) an airflow path extending from an outlet of each fan 206 to a corresponding inlet of the fan 206. FIG. 5 provides a schematic representation of this airflow system.

[0096] As illustrated in FIG. 5, air is drawn from a jacket space 114 surrounding plenum vest 102, jacket space 114 functioning as a lower-pressure region, into fan 206. Fan 206 directs air through a diffuser 502 and a heating element 504, after which the heated air enters an internal plenum 110 formed between an inner textile layer 106 and an outer textile layer 104 of vest 102. Internal plenum 110 represents a higher-pressure region relative to jacket space 114.

[0097] A plurality of discrete openings 118 formed in at least one of the textile layers allow air to exit internal plenum 110 and return to jacket space 114, thereby completing a closed circulation loop. Although FIG. 5 depicts internal plenum 110 and jacket space 114 as simplified geometric volumes, these regions are, in practice, defined by compliant textile layers that conform to the wearer’s torso.

[0098] The airflow models described herein are simplified and are provided for explanatory purposes. Actual airflow behavior in the plenum vest is influenced by factors including compliance of the textile materials, non-uniform pressure distribution within the internal plenum, body movement, and external compression from garments, backpacks, or seating.

[0099] While analytical modeling provides useful insight into design trends and parameter sensitivity, further refinement may be achieved through experimental measurement, such as flow bench testing, or through computational fluid dynamics modeling. In practice, the location of openings, material selection, and manufacturing techniques may significantly influence airflow distribution, pressure behavior, and overall system performance.

[0100] Notwithstanding the simplifying assumptions of the models, the plenum-based airflow system described herein inherently redistributes airflow in response to localized compression, allowing circulation to be maintained even when portions of the vest are constrained. This behavior distinguishes plenum vest 102 from systems relying on discrete ducts, which may collapse and substantially restrict airflow under similar conditions.

[0101] The volumetric flow rate of air through plenum vest 102 is determined by the interaction between fan performance characteristics and flow resistance of the airflow path. FIG. 6 conceptually illustrates this interaction using a fan curve and a system curve.18503488\70001\FG: 104703455.1Docket No. 503488.70001

[0102] Fan performance is commonly characterized by a relationship between pressure rise and flow rate, supplied by the fan manufacturer. From the perspective of the fan, the remainder of the airflow path presents a resistance that the fan must overcome. This resistance arises from factors including airflow path geometry, surface roughness, the presence of heating elements, and flow restrictions created by openings between the internal plenum and the jacket space.

[0103] The operating point of the airflow system occurs at the intersection of the fan curve and the system curve, as shown schematically in FIG. 6. At this balance point, the pressure rise generated by the fan equals the pressure losses of the airflow path for a corresponding flow rate. In plenum vest 102, the size, number, and placement of openings between the internal plenum and the jacket space are readily adjustable design variables and represent a dominant contributor to flow resistance. Other flow losses, such as those associated with the diffuser, heater, and textile-defined airflow paths, may also contribute to overall resistance but are generally less easily altered.

[0104] For purposes of illustration, the flow resistance of openings between the internal plenum and the jacket space may be approximated using an orifice flow model commonly applied in fluid mechanics. Under this model, each opening is treated as a sharp-edged orifice.

[0105] A standard expression for volumetric flow rate through an orifice is:(Equation 4)where Q is volumetric flow rate, cdis a discharge coefficient, Aois the orifice area, Y is an expansion factor, Ap is the pressure difference across the orifice, p is air density, and ft is the ratio of orifice diameter to upstream cavity diameter.

[0106] For airflow through openings in plenum vest 102, compressibility effects may be neglected and the upstream cavity may be considered large relative to the opening diameter. Under these assumptions, Y « 1 and~ 0, yielding:Q = cdA0J~^- (Equation 5)

[0107] Rearranging Equation 5 gives:PQAp=(Equation 6)19503488\70001\FG: 104703455.1Docket No. 503488.70001

[0108] Equation 6 describes the pressure drop associated with flow through a single opening. For a vest having n openings with approximately equal pressure difference and a total flow rate Qt= nQ, the system pressure-flow relationship may be approximated by:(Equation 7)

[0109] This representation illustrates how opening size and number influence system resistance and plenum pressure.

[0110] The foregoing model neglects additional flow losses in the diffuser, heater, and textile-defined flow paths. Inclusion of such losses would tend to increase system resistance and shift the operating point toward lower flow rates and higher pressure differences, as conceptually indicated in FIG. 6.[OHl] Fan performance curves are typically supplied in graphical form. For purposes of illustration, numerical fan curve data may be obtained by digitizing manufacturer-supplied curves and fitting an analytical expression.

[0112] In one example, a representative centrifugal fan may be approximated by a polynomial relationship of the form:(Equation 8)

[0113] where Ap is pressure rise and Q is volumetric flow rate. The coefficients a0-a3depend on fan design and operating conditions. Coefficients a0,a2, and a3for an example SanAce 9BD12 fan are, respectively, 30.43465, -33.58557, -250.5812,and 8.328714.

[0114] In some embodiments, the plenum vest includes two fan-heater assemblies operating in parallel. For identical fans operating in parallel, the pressure rise remains substantially the same while the total flow rate is approximately doubled.

[0115] FIG. 7 illustrates the effect of varying opening diameter while maintaining a fixed number of openings in the plenum vest. The balance point for each opening diameter is determined by the intersection of the system curve associated with the openings, as described by Equation 7, and the fan curve, as described by Equation 8. In FIG. 7, the balance point for each diameter is indicated by a dot at the intersection of the downwardsloping fan curve and the upward-sloping system curve.

[0116] As opening diameter increases, the aggregate flow area increases and the flow resistance associated with the openings decreases. This reduction in resistance shifts the system curve downward, resulting in a higher flow rate at a lower pressure difference across20503488\70001\FG: 104703455.1Docket No. 503488.70001the openings. Conversely, smaller opening diameters increase flow resistance and shift the balance point toward lower flow rates and higher pressure differences.

[0117] FIG. 7 further illustrates a region corresponding to pressure differences on the order of approximately 10 mm H2O or less between the internal plenum and the surrounding jacket space. Maintaining a positive pressure difference of this magnitude may be desirable in some embodiments to preserve inflation of the internal plenum and to support airflow rerouting when portions of the vest are locally compressed.

[0118] For the illustrative conditions shown in FIG. 7, including a fixed number of openings and representative fan characteristics, opening diameters that produce balance points above this pressure threshold may be considered suitable. At the boundary of this region, the model predicts a maximum opening diameter on the order of approximately 7 / 32 inch for a vest having 20 openings. This value is provided by way of example and depends on assumptions regarding fan performance, air density, discharge coefficient, and the omission of other flow losses.

[0119] Accordingly, FIG. 7 demonstrates how opening diameter functions as a primary design parameter for controlling the tradeoff between airflow rate and internal plenum pressure, while allowing the vest to maintain positive pressure under operating conditions. The illustrated results are representative and non-limiting, and similar trends apply for other fan types, opening counts, and system configurations.

[0120] FIG. 8 illustrates the effect of varying the number of openings while maintaining a fixed opening diameter. As in the case of opening diameter, the operating point for each configuration is determined by the intersection of the system curve associated with the openings, as described by Equation 7, and the fan curve, as described by Equation 8. In FIG.8, the balance point for each number of openings is indicated by a dot at the intersection of the corresponding system curve and the fan curve.

[0121] Increasing the number of openings increases the aggregate flow area between the internal plenum and the surrounding jacket space. This increase in flow area reduces the flow resistance associated with the openings and shifts the system curve downward. As a result, the balance point moves toward higher volumetric flow rates and lower pressure differences. Conversely, reducing the number of openings increases flow resistance and shifts the operating point toward lower flow rates and higher pressure differences.

[0122] FIG. 8 further depicts a region corresponding to pressure differences on the order of approximately 10 mm H2O or less between the internal plenum and the jacket space.Maintaining a positive pressure difference of this magnitude may be desirable in some 21503488\70001\FG: 104703455.1Docket No. 503488.70001embodiments to sustain inflation of the internal plenum and to enable dynamic airflow rerouting under localized compression.

[0123] For the illustrative conditions shown in FIG. 8, including a representative opening diameter and fan characteristic, the model predicts that increasing the number of openings allows higher flow rates while remaining above the pressure threshold associated with plenum inflation. At the boundary of the acceptable region, the model predicts a maximum of approximately 40 openings having a diameter of approximately 5 / 32 inch for one half of the vest. This value is illustrative and depends on assumptions regarding fan performance, discharge coefficient, air density, and the exclusion of additional system losses.

[0124] Accordingly, FIG. 8 demonstrates that the number of openings functions as a primary design variable for controlling the tradeoff between airflow rate and internal plenum pressure. The illustrated trends are representative and non-limiting, and similar relationships apply for other opening diameters, fan configurations, and system parameters.

[0125] FIG. 7 and FIG. 8 collectively demonstrate that similar airflow behavior may be achieved by trading off the number of openings and the diameter of those openings. In particular, different configurations having approximately equal aggregate opening area may exhibit similar pressure, flow characteristics, and balance points.

[0126] More generally, two opening configurations may have approximately equal aggregate opening area when:TVjd « n2dor, equivalently,(Equation 9)

[0127] This relationship provides qualitative guidance for selecting combinations of opening number and opening diameter that yield comparable system behavior. The relationship is derived under simplifying assumptions used in developing the system curve and should not be interpreted as a precise design constraint. Deviations may occur when additional flow losses or non-uniform pressure distributions become significant.

[0128] Accordingly, the number and diameter of openings may be selected in combination to achieve desired airflow rates and internal plenum pressures, while preserving flexibility in vest design and manufacturing.

[0129] The battery pack operates in conjunction with a smart power management system that dynamically controls heating power and fan speed based on sensed conditions and user22503488\70001\FG: 104703455.1Docket No. 503488.70001input. FIG. 9 and FIG. 10 illustrate example user interfaces through which a wearer may interact with the control system.

[0130] FIG. 9 shows a wearable device 220, such as a watch, presenting a user interface 222. FIG. 10 shows a mobile device 218, such as a smart phone, also presenting user interface 224. The user interface may display a selected target temperature, current operating status, battery state, estimated time to reach the target temperature, and other system information. In some embodiments, the same user interface layout and control functions are available across multiple devices. In some embodiments, smart phone interface 224 shows battery status indicating time remaining of battery life at the current set point.

[0131] In operation, the control system employs a feedback control algorithm to regulate delivery of thermal energy to plenum vest 102. In some embodiments, the control algorithm compares a user-selected temperature setpoint to temperature measurements obtained from multiple sensors positioned within and on the vest. The control system may compute a weighted combination of these temperature measurements to generate a control signal.

[0132] When the weighted temperature signal is below the selected setpoint, the control system increases power delivered to one or more heating elements and may also increase fan speed, thereby raising the temperature of the air circulating within the vest. As the measured temperature approaches the setpoint, heating power and fan speed are reduced to maintain the desired thermal condition. In this manner, the control system continuously adjusts system output to maintain comfort, rather than operating at fixed or discrete power levels.

[0133] In some embodiments, the power output percentage indicated in FIG. 9 and FIG. 10 represents the fraction of maximum available power. For example, the fraction is equal to the (fractional) duty cycle for the PWM signal controlling the heater. (Power consumed by the fan is negligible, which is on the order of 4W). In other embodiments, power output percent may be a representation of the percentage of the perceived maximum temperature, maximum heat flux, or other metric.

[0134] FIG. 11-FIG. 13 further illustrate internal control and power-management functions in different exercise and environmental conditions. The control system responds dynamically to changes in wearer activity and environmental conditions. For example, if the wearer generates additional metabolic heat during physical activity, measured temperatures may increase, causing the control system to reduce heating power or suspend heating operation. Similarly, changes in ambient temperature or wind conditions may be detected23503488\70001\FG: 104703455.1Docket No. 503488.70001indirectly through temperature measurements, prompting corresponding adjustments in heating power and airflow.

[0135] Dynamic responsiveness is facilitated by the convective air-heating approach used in the vest, which enables relatively rapid changes in delivered thermal output compared to garments that rely on resistive heating elements embedded in fabric. In resistive systems, heat is stored in the garment material itself, resulting in slower response times and reduced ability to adapt to rapidly changing conditions.

[0136] In some embodiments, the control system implements a heuristic relationship between heater power and fan speed. For example, when commanded heater power is at or below a predetermined fraction of maximum heater power, such as approximately fifty percent, the fan may operate at a substantially constant fraction of its maximum speed. When commanded heater power exceeds that threshold, fan speed may increase as a function of heater power, for example by varying approximately linearly between a minimum allowable fan speed and a maximum fan speed as heater power approaches its maximum value. In one illustrative implementation, when heater power is commanded at one hundred percent of maximum, the fan may likewise operate at one hundred percent of its allowable speed range.

[0137] The minimum allowable fan speed may be selected based on characteristics of the fan and airflow system, and in some embodiments may be greater than fifty percent of maximum fan speed to ensure reliable airflow through the system. The specific relationship between heater power and fan speed may vary depending on design goals, acoustic constraints, and airflow requirements, and may be modified in different operating modes.

[0138] In addition to automatic control, the system may permit user-defined constraints on airflow behavior. For example, a user may select an operating mode that limits maximum fan speed, maintains a substantially constant fan speed, or prioritizes reduced acoustic output. In such modes, the control system may continue to regulate heater power within the bounds of the selected fan-speed constraint. This can be advantageous in scenarios where quiet operation is desired, such as hunting or other noise-sensitive activities.

[0139] Unlike simple convective heating devices in which heating output is inherently tied to fan speed (such as systems that rely on positive temperature coefficient (PTC) heaters whose heat output varies primarily as a function of airflow) the wearable thermal management system described herein supports decoupled control of fan speed and heater power. In such simple systems, increasing fan speed inherently increases heating output by24503488\70001\FG: 104703455.1Docket No. 503488.70001drawing additional power through the heater, while reducing fan speed correspondingly reduces heating, thereby limiting control flexibility.

[0140] By contrast, the control system of the present device may regulate heater power independently of fan speed, allowing heat output to be increased or decreased without necessarily increasing airflow, and allowing airflow to be adjusted without directly altering heater power. For a given heater power, increasing airflow may reduce the temperature rise across the heater while increasing total heat delivery through increased mass flow.Accordingly, fan speed and heater power may be controlled independently or jointly based on desired performance characteristics, including thermal responsiveness, acoustic output, and power consumption.

[0141] Other control strategies, including alternative mappings, rule sets, heuristics, or optimization routines, may be employed in some implementations. Such strategies may balance comfort, responsiveness, noise, and battery life differently at different operating points. Accordingly, the control system provides a combination of automatic feedback control, heuristic-based coordination between airflow and heating, and user-selectable operating preferences, without being limited to a single fixed control algorithm.

[0142] FIG. 14-FIG. 17 illustrate another embodiment of a wearable thermal management system 1400 that incorporates the features described previously. In this embodiment, system 1400 is configured as a rugged vest 1402 suitable for use in demanding environments in which durability, user adjustability, and thermal comfort are desired. The illustrated embodiment combines a reinforced outer structure with an internal airflow and heating system to provide controlled thermal regulation across a wearer’s torso.

[0143] Unlike single fabric-based heated garments, vest 1402 includes a reinforced outer shell 1404 formed from impact-resistant materials, such as polymer composites or high-density synthetic layers, as described in greater detail below with reference to FIG. 16 and FIG. 17. Outer shell 1404 is configured to resist environmental exposure, including moisture, particulate matter, and abrasion, while protecting internal airflow, heating, and control components. Molded air intake vents 1406 are positioned on opposite sides of vest 1402, for example below a lower rib region of a wearer, and are integrated into outer shell 1404 to promote airflow while maintaining a compact external profile. In some embodiments, intake vents 1406 include angled intake openings, or facets, configured to direct incoming air along a non-normal path relative to the vest surface, thereby reducing a tendency of adjacent garment liners or fabric layers to be drawn directly against the intake opening during fan operation.25503488\70001\FG: 104703455.1Docket No. 503488.70001

[0144] In addition, intake vents 1406 may include a raised or stand-off intake structure that protrudes outward from outer shell 1404, creating a spacing between the intake opening and adjacent fabric layers of the outer garment. The raised intake structure may include lateral or side-facing vent openings, such that airflow enters through side passages while the forward-facing surface remains substantially shielded. This configuration functions analogously to a chimney or rain-hood structure, allowing air to be drawn into the system while mitigating blockage caused by flexible garment liners, moisture, or external contact.

[0145] FIG. 14 shows that vest 1402 incorporates a modular airflow and heating system configured to circulate air through a pressurized internal plenum 1408, as described previously. One or more fan and heating element assemblies 1410 are housed within protected compartments 1412 to reduce exposure to external impacts and to facilitate servicing or replacement.

[0146] In FIG. 14 and FIG. 15, unfilled or white arrows indicate a direction of internal airflow within the vest, including airflow driven by fan assemblies 1410 through the internal plenum and toward exhaust vents. Curved or squiggly arrows indicate convective heat transfer from circulating air toward the wearer’s body, including heat transfer that may occur through porous or semi-permeable materials described later.

[0147] When fan assemblies 1410 are active, the internal plenum may inflate slightly, causing vest 1402 to conform to the wearer’s torso and increasing effective surface contact for heat transfer. Dashed outlines surrounding the torso represent an air-recirculation region 1414 between vest 1402 and an outer garment 1416, which functions as a lower-pressure return plenum. In this region, air discharged from exhaust vents 1418 and underarm vents 1420 may flow within the outer garment and return toward intake vents 1406 to complete a circulation cycle.

[0148] A user interface 1422 is integrated into outer shell 1404 and provides visual indications of one or more operating parameters, such as temperature, fan speed, or battery level. One or more tactile buttons 1424 positioned adjacent the display allow a user to manually adjust system settings. In the illustrated embodiment, components of user interface 1422 are configured to be weather-resistant and operable while the wearer is wearing gloves. As described previously, vest 1402 also supports control via a smart watch 1426 and a phone (not shown) or other wireless accessory device 1428.

[0149] Vest 1402 further includes adjustable shoulder straps 1430, chest strap 1432, and rib strap 1434 formed from durable webbing material, allowing the fit of vest 1402 to be adjusted to accommodate different body shapes and layers of clothing. The straps are 26503488\70001\FG: 104703455.1Docket No. 503488.70001configured to retain vest 1402 in a stable position during physical activity and while carrying additional equipment.

[0150] As shown in FIG. 15, the airflow system includes multiple exhaust vents 1418 located on one or more of a front surface and a back surface of vest 1402. In some embodiments, one or more of exhaust vents 1418 may be adjustable to selectively restrict or permit airflow. The airflow system is configured to redistribute air across the torso in response to wearer movement or localized compression, thereby reducing formation of hot spots and promoting uniform thermal comfort.

[0151] FIG. 15 further illustrates that vest 1402 includes one or more underarm vents 1420 positioned in a region adjacent an underarm of the wearer. Underarm vents 1420 facilitate airflow in a ventilation or cooling mode in which the fan assemblies operate while the heating elements are deactivated, allowing circulating air to remove heat and moisture from the wearer’s body. In such a mode, air is drawn through intake vents 1406, circulated through the internal plenum, and exhausted through exhaust vents 1418 and underarm vents 1420 to enhance convective cooling and ventilation.

[0152] FIG. 15 also shows that wearable thermal management system 1400 includes a removable and rechargeable battery pack 1502 stored within a protected compartment of outer shell 1404. Battery pack 1502 is accessible via a zipper 1504 or other access port, enabling replacement or charging without removing vest 1402 from the wearer.

[0153] FIG. 16 and FIG. 17 illustrate a set of materials 1600 corresponding to wearable thermal management system 1400 of FIG. 14, shown laid flat and annotated to identify material constructions used in different regions of vest 1402. In this example, vest 1402 is formed from a combination of base material layer stack 1602 used throughout a majority of the product and four other region-specific composite material layer stacks (1604, 1606, 1608, and 1702) that provide enhanced durability, padding, airflow containment, or structural support in selected areas. Material layer stacks 1602-1702 are illustrated as representative stacks, and individual materials within each stack may be substituted with equivalent materials providing comparable abrasion resistance, padding, rigidity, and / or air retention.

[0154] In the illustrated embodiment, a majority of vest 1402 is formed from base material layer stack 1602 that provides general structural integrity, flexibility, and air containment. Base material layer stack 1602 includes an exterior layer 1602a, a middle layer 1602b, and a bottom layer 1602c that collectively define a plenum (air) layer 1408 therebetween.27503488\70001\FG: 104703455.1Docket No. 503488.70001

[0155] Exterior layer 1602a comprises a durable outer textile formed from a high-tenacity nylon fabric, for example a 500D or WOOD nylon 6,6 fabric (Cordura-grade), optionally having a matte finish and a durable water repellent (DWR) treatment. Exterior layer 1602a provides abrasion resistance and load-bearing durability and is configured to resist scuffing and tearing in regular use.

[0156] Middle layer 1602b and the bottom layer 1602c each comprise a laminate including a woven ripstop textile, for example a 70D-210D nylon ripstop fabric, bonded to a polymer membrane such as a poly-ether thermoplastic polyurethane (TPU) film. In some embodiments, the TPU film has a thickness in a range of approximately 0.12 mm to 0.20 mm. The laminate construction of middle layer 1602b and bottom layer 1602c provides low air permeability (i.e., substantially air-tight behavior), while maintaining flexibility and durability suitable for a wearable garment.

[0157] Plenum (air) layer 1408 is defined between middle layer 1602b and bottom layer 1602c and forms at least a portion of an internal airflow volume of vest 1402. In operation, air delivered by one or more fan assemblies flows through the internal airflow volume, and the low-permeability laminate layers 1602b and 1602c contribute to maintaining a pressure differential that supports airflow distribution and optional plenum inflation.

[0158] Base material layer stack 1602 further includes one or more non-perforated tacking tabs (not shown) configured for later attachment to the plenum structure. In some embodiments, the tacking tabs are initially formed without through-holes, and one or more holes are formed during a later assembly stage to mate the tabs to corresponding plenum attachment points.

[0159] Base material layer stack 1602 further includes one or more mechanical joints (not shown) between a shell portion and a plenum portion of vest 1402. In some embodiments, the mechanical joints include double-cap rivets used with TPU backers to distribute load and reduce tearing or leakage at the joint, thereby providing a durable shell-to-plenum attachment.

[0160] In addition, vest 1402 may include reinforcement pads (not shown) positioned in one or more high-wear zones. In some embodiments, the reinforcement pads comprise ultra-high-molecular-weight polyethylene (UHMWPE) materials (for example, Dyneema-grade pads) to increase strength and abrasion durability in localized regions subject to elevated wear.

[0161] First material layer stack 1604 is used in regions of vest 1402 associated with shoulder padding and waist padding, where enhanced structural integrity, wearer comfort,28503488\70001\FG: 104703455.1Docket No. 503488.70001and load distribution are desired. In the illustrated embodiment, first material layer stack 1604 includes an exterior layer 1604a (corresponding to exterior layer 1602a), a middle laminate layer 1604b (corresponding to middle laminate layer 1602b), an intermediate spacer layer 1604c, and a bottom laminate layer 1604d (corresponding to bottom laminate layer 1602c).

[0162] The inclusion of spacer layer 1604c further assists in maintaining plenum geometry in the shoulder and waist regions during movement or external loading. Intermediate spacer layer 1604c comprises a three-dimensional spacer textile, for example a polyester spacer mesh having a thickness on the order of approximately 6 mm. Spacer layer 1604c provides structural integrity, cushioning, and impact protection, while maintaining separation between the adjacent laminate layers to improve wearer comfort, load distribution, and resistance to localized compression.

[0163] Second material layer stack 1606 is used in regions of vest 1402 associated with exterior detailing and surface protection, where enhanced durability and visual definition are desired while maintaining airflow containment. In the illustrated embodiment, second material layer stack 1606 includes an exterior detail layer 1606a, an abrasion-resistant intermediate layer 1606b, and plenum-forming laminate layers 1606c and 1606d.

[0164] Exterior detail layer 1606a comprises a quilted textile, for example a hexagonal-quilted nylon fabric having a nominal weight of approximately 70 denier and optionally foam-backed. Exterior detail layer 1606a provides surface protection, localized cushioning, and exterior visual structure while remaining flexible and conformable.

[0165] Abrasion-resistant intermediate layer 1606b is positioned beneath exterior detail layer 1606a and corresponds to exterior layer 1602a. Layer 1606b provides load-bearing capability and resistance to scuffing and tearing in exterior regions subject to contact or abrasion.

[0166] Second material layer stack 1606 further includes a middle plenum-forming laminate layer 1606c and a bottom plenum-forming laminate layer 1606d, each corresponding to the laminate layers described above with respect to base material layer stack 1602. Laminate layers 1606c and 1606d cooperate to define a plenum (air) layer 1408 therebetween, forming part of the internal airflow volume of vest 1402.

[0167] Third material layer stack 1608 is used in regions of vest 1402 associated with housing and supporting internal components, such as airflow hardware, control electronics, power electronics, or battery interfaces. These regions require enhanced structural support, protection of internal hardware, and maintenance of the internal airflow plenum.29503488\70001\FG: 104703455.1Docket No. 503488.70001

[0168] In the illustrated embodiment, third material layer stack 1608 includes an exterior detail layer 1608a, an abrasion-resistant intermediate layer 1608b, a rigid support layer 1608c, and one or more plenum-forming laminate layers 1608d and 1608e.

[0169] Exterior detail layer 1608a comprises a quilted textile, for example a hexagonal-quilted nylon fabric having a nominal weight of approximately 70 denier and optionally foam-backed. Exterior detail layer 1608a provides surface protection, localized cushioning, and exterior visual structure while remaining flexible and conformable.

[0170] Abrasion-resistant intermediate layer 1608b corresponds to exterior layer 1602a and provides load-bearing capability and resistance to scuffing and tearing in regions subject to external contact.

[0171] Rigid support layer 1608c comprises a semi-rigid or rigid polymer component, for example a high-density polyethylene (HDPE) housing or panel, configured to mount and support internal hardware. Rigid support layer 1608c provides structural support for internal components and associated cabling, reduces deformation of the vest in regions subject to localized loading, and protects internal components from impact and compression.

[0172] Third material layer stack 1608 further includes a middle plenum-forming laminate layer 1608d and a bottom plenum-forming laminate layer 1608e, each corresponding to the laminate layers described above with respect to base material layer stack 1602. Laminate layers 1608d and 1608e cooperate to define a plenum (air) layer 1408 therebetween, forming part of the internal airflow volume of vest 1402.

[0173] FIG. 16 further illustrates exterior locations associated with internal airflow hardware, control electronics, and power storage, as well as representative attachment features such as reinforced stitching, bonded seams, hook-and-loop 1610 attachment regions, and protective exterior patches.

[0174] FIG. 17 illustrates vest 1402 laid flat and viewed from an interior side of the vest. Interior-facing regions intended to contact the wearer incorporate base material layer stack 1602 to provide comfort, conformability, and controlled airflow containment. The exploded callouts in FIG. 17 illustrate how a fourth material layer stack 1702 is used on the interior.

[0175] Fourth material layer stack 1702 is used in regions of vest 1402 associated with back padding, where a combination of wearer comfort, structural support, and protection against external loading is desired. In the illustrated embodiment, fourth material layer stack 1702 includes an exterior layer 1702a (corresponding to exterior layer 1602a), an intermediate padding layer 1702b, and one or more plenum-forming laminate layers 1702c and 1702d (corresponding to laminate layers 1602b and 1602c).30503488\70001\FG: 104703455.1Docket No. 503488.70001

[0176] Intermediate padding layer 1702b comprises a foam laminate selected to provide a semi-rigid hand while remaining flexible and wearable. In some embodiments, padding layer 1702b includes an EVA foam, a polyurethane (PU) foam, or a combination thereof, having a thickness in a range of approximately 3 mm to 4 mm. Padding layer 1702b provides cushioning, impact protection, and load distribution in back regions that may be subject to contact with external objects, such as seat backs, backpacks, or carried equipment.

[0177] Fourth material layer stack 1702 further includes middle plenum-forming laminate layer 1702c and bottom plenum-forming laminate layer 1702d. Laminate layers 1702c and 1702d cooperate to define a plenum (air) layer 1408 therebetween, forming part of the internal airflow volume of vest 1402.

[0178] Together, FIG. 16 and FIG. 17 demonstrate that the vest uses a combination of base material layers and region-specific composite material layers to achieve durability, airflow control, wearer comfort, and structural integrity while maintaining a flexible, wearable form factor.

[0179] FIG. 18 is a flow diagram illustrating one example of a process 1800 performed by a wearable thermal management device configured to be worn between a user’s torso and an over garment. Process 1800 may be executed by control circuitry of the wearable thermal management device during operation.

[0180] At item 1802, process 1800 includes operating a fan to draw air from a lower-pressure air-recirculation zone surrounding the wearable thermal management device. The lower-pressure air-recirculation zone may be defined, at least in part, by a space between the wearable thermal management device and an interior surface of the over garment worn by the user.

[0181] At item 1804, process 1800 includes delivering the air drawn by the fan into a higher-pressure plenum defined within the wearable thermal management device. The fan increases the pressure of the air within the higher-pressure plenum relative to the lower-pressure air-recirculation zone, thereby promoting distribution of air within the device.

[0182] At item 1806, process 1800 includes heating the air using an electrical heater positioned downstream of the fan. This can happen simultaneously, before, or after item 1804. The electrical heater may be controlled by control circuitry to supply a variable amount of heating power based on an adjustable temperature setpoint, sensed operating conditions, or both.31503488\70001\FG: 104703455.1Docket No. 503488.70001

[0183] At item 1808, process 1800 includes exhausting the heated air from the higher-pressure plenum into the lower-pressure air-recirculation zone to establish a circulating airflow path. The circulating airflow path allows air to move repeatedly between the wearable thermal management device and the space defined by the over garment.

[0184] In some embodiments, process 1800 further includes regulating a temperature of the circulating air based on an adjustable temperature setpoint. Regulating the temperature may include dynamically adjusting at least one of fan speed or heating power using control circuitry of the wearable thermal management device. Temperature regulation may be based on temperature data received from one or more temperature sensors positioned within the wearable thermal management device, such as within the higher-pressure plenum or along an airflow path.

[0185] In some embodiments, process 1800 further includes receiving activity data indicative of user activity from a wearable activity monitoring device communicatively coupled to the wearable thermal management device. The wearable activity monitoring device may comprise a smart watch, and the activity data may include one or more of heart rate, motion, step rate, exertion level, or a metabolic estimate. Operation of at least one of the fan or the electrical heater may be modified in response to changes in the activity data.

[0186] In some embodiments, process 1800 further includes receiving a user-selected operating level via a user interface of the wearable thermal management device or via a remote user interface. The user-selected operating level may be mapped by the control circuitry to one or more operating parameters, including fan speed, heating power, or limits on fan speed or heating power.

[0187] In some embodiments, process 1800 further includes operating the wearable thermal management device in a ventilation mode in which the fan is activated while the electrical heater is deactivated. The ventilation mode may be entered automatically in response to activity data indicating increased user activity, thereby promoting convective cooling and moisture removal.

[0188] In some embodiments, process 1800 further includes supplying electrical power to the wearable thermal management device from a power source compliant with a Universal Serial Bus Power Delivery specification. The supplied electrical power may include up to at least approximately 100 watts, or in some embodiments more than 100 watts, depending on the power source and operating mode.32503488\70001\FG: 104703455.1Docket No. 503488.70001

[0189] In some embodiments, process 1800 further includes selecting an operating combination of fan speed and heating power that maintains a target temperature range while reducing electrical power consumption relative to increasing heating power alone.

[0190] In light of this disclosure, skilled persons will appreciate that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present invention should, therefore, be determined only by claims and equivalents.33503488\70001\FG: 104703455.1

Claims

Docket No. 503488.70001CLAIMSWhat is claimed is:

1. A personal thermal management device for placement between a user’s torso and an over garment, the personal thermal management device comprising:an outer layer and an inner layer, the outer layer and the inner layer defining therebetween an interior zone configured as a higher-pressure plenum, and the outer layer and an interior surface of the over garment defining an air-recirculation zone configured as a lower-pressure plenum;a fan coupled to an intake opening between the air-recirculation zone and the interior zone, the fan configured to draw air from the lower-pressure plenum and deliver it into the higher-pressure plenum;an electrical heater positioned downstream of the fan to heat the air drawn from the lower-pressure plenum, thereby supplying heated air into the higher-pressure plenum;an exhaust vent opening from the interior zone into the air-recirculation zone, the vent configured to release the heated air flowing from the higher-pressure plenum into the lower-pressure plenum;a temperature sensor and associated circuitry configured to regulate the temperature of the heated air based on an adjustable setpoint, the circuitry further configured to dynamically adjust fan speed and heating power in response to environmental conditions and user activity; anda battery integrated within at least one of the outer layer or the inner layer, the battery configured to supply power to the electrical heater and the fan.

2. The personal thermal management device of claim 1, in which increased pressure of the higher-pressure plenum maintains an increased amount of surface area of contact between the user’s torso and the inner layer.

3. The personal thermal management device of claim 1, further comprising a set of air vents positioned on the outer layer, in which the adjustable air vents are configured to control the flow and distribution of heated air into the air-recirculation zone to customize localized heating across different areas of the user’s torso.

4. The personal thermal management device of claim 1, in which the fan and the electrical heater are housed in a modular assembly positioned within a central region of the interior34503488\70001\FG: 104703455.1Docket No. 503488.70001zone, the modular assembly configured to optimize airflow distribution throughout the higher-pressure plenum.

5. The personal thermal management device of claim 1, in which the temperature sensor is positioned at a location within the air-recirculation zone to measure the temperature of the circulating heated air.

6. The personal thermal management device of claim 1, in which the fan is configured to operate at variable speeds, and the associated circuitry dynamically adjusts the fan speed and power to an internal heat exchanger based on feedback from the temperature sensor to maintain the user-selected setpoint temperature.

7. The personal thermal management device of claim 1, in which the battery is a removable and rechargeable power pack integrated into a compartment within the outer layer, the power pack configured to be easily accessed by the user for replacement or recharging.

8. The personal thermal management device of claim 1, in which the inner layer includes a soft, compliant material to enhance comfort and reduce thermal contact resistance between the user’s torso and the interior zone.

9. The personal thermal management device of claim 1, further comprising a wireless communication module integrated into the circuitry, the module configured to communicate with an external device, allowing the user to adjust heating settings remotely through a smartphone or smartwatch application.

10. The personal thermal management device of claim 1, in which the fan and electrical heater are powered by a control algorithm implemented in the circuitry, the algorithm configured to adjust heating power and airflow rate based on user activity levels detected by motion sensors within the personal thermal management device.

11. The personal thermal management device of claim 1, in which the exhaust vent comprises multiple exit points distributed across the outer layer, the exit points configured to release heated air uniformly across the user’s torso to avoid localized overheating.

12. The personal thermal management device of claim 1, in which the exhaust vent includes us er- adjustable flaps, the flaps configured to open or close the exit points to control the flow of heated air based on the user’s preference.35503488\70001\FG: 104703455.1Docket No. 503488.7000113. The personal thermal management device of claim 1, in which the outer layer is made of a waterproof and wind-resistant material to protect the interior zone and the electrical components from environmental exposure.

14. The personal thermal management device of claim 1, in which the inner layer and outer layer are joined by seam-sealed stitching to ensure that the higher-pressure plenum remains pressurized during operation.

15. The personal thermal management device of claim 1, further comprising an impactresistant cover positioned over the fan intake to prevent accidental blockage of the fan and to protect the fan from external objects.

16. The personal thermal management device of claim 1, in which the fan is a dual-fan assembly.

17. The personal thermal management device of claim 16, in which each fan of the dual-fan assembly operates independently from the other fan to support redundancy.

18. The personal thermal management device of claim 1, further comprising a digital display integrated into the outer layer, the display configured to show the current or setpoint temperature, fan speed, and battery status.

19. The personal thermal management device of claim 18, further comprising an input device configured to allow a user to control a setpoint temperature of the personal thermal management device.

20. The personal thermal management device of claim 1, in which the fan and electrical heater are housed in a modular compartment, the compartment being removable for maintenance or replacement.

21. The personal thermal management device of claim 1, in which the circuitry is further configured to operate in a ventilation mode in which the fan circulates air through the higher-pressure plenum while the electrical heater is deactivated, thereby promoting convective cooling and moisture removal from the user’s torso.

22. A method performed by a wearable thermal management device, the wearable thermal management device being configured to be worn between a user’s torso and an over garment, the method comprising:36503488\70001\FG: 104703455.1Docket No. 503488.70001operating a fan to draw air from a lower-pressure air-recirculation zone surrounding the wearable thermal management device;delivering the air into a higher-pressure plenum defined within the wearable thermal management device;heating the air using an electrical heater positioned downstream of the fan; and exhausting the heated air from the higher-pressure plenum into the lower-pressure air-recirculation zone to establish a circulating airflow path.

23. The method of claim 22, further comprising regulating a temperature of the air circulated through the wearable thermal management device based on an adjustable temperature setpoint.

24. The method of claim 23, wherein regulating the temperature comprises dynamically adjusting at least one of fan speed or heating power using control circuitry of the wearable thermal management device.

25. The method of claim 22, further comprising receiving temperature data from at least one temperature sensor positioned within the wearable thermal management device and adjusting operation of the fan or the electrical heater based on the temperature data.

26. The method of claim 22, further comprising receiving activity data indicative of user activity from a wearable activity monitoring device communicatively coupled to the wearable thermal management device.

27. The method of claim 26, wherein the wearable activity monitoring device comprises a smart watch.

28. The method of claim 26, wherein the activity data includes one or more of heart rate, motion, step rate, exertion level, or metabolic estimate.

29. The method of claim 26, further comprising modifying operation of at least one of the fan or the electrical heater in response to changes in the activity data.

30. The method of claim 22, further comprising receiving a user-selected operating level via a user interface of the wearable thermal management device.

31. The method of claim 30, further comprising mapping the user-selected operating level to one or more operating parameters including fan speed, heating power, or limits thereon.37503488\70001\FG: 104703455.1Docket No. 503488.7000132. The method of claim 22, further comprising operating the wearable thermal management device in a ventilation mode by activating the fan while deactivating the electrical heater.

33. The method of claim 32, further comprising entering the ventilation mode in response to activity data indicating increased user activity.

34. The method of claim 22, further comprising supplying electrical power to the wearable thermal management device from a power source compliant with a Universal Serial Bus Power Delivery specification.

35. The method of claim 34, wherein supplying electrical power includes supplying up to at least approximately 100 watts to the wearable thermal management device.

36. The method of claim 34, wherein supplying electrical power includes supplying more than 100 watts to the wearable thermal management device.

37. The method of claim 22, further comprising selecting an operating combination of fan speed and heating power that maintains a target temperature range while reducing electrical power consumption relative to increasing heating power alone.38503488\70001\FG: 104703455.1

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