MODULAR THERMAL DEVICE

Abstract

A modular cooling/heating device includes a thermal plant such as a micro-refrigeration system with an integrated heater for providing remote, on-site cooling/heating to an insulated enclosure defining a modular cooling volume by exchanging a liquid thermal-transfer medium, such as available tap water or alcohol-glycol mixture, with a thermal exchanger disposed within the insulated enclosure. A thermal source adapted for thermal exchange with a fluidic transfer medium combined with an engageable fluidic coupling between the thermal source and the thermal exchanger provides for detachable engagement of the thermal exchanger in a verity of contexts. The thermal exchange may take the form of a flexible, fluid carrying pouch, or a rigid thermal vessel having substantial vacuum and phase-change lining features for thermal inertia. Both may be combined with an integrated, insulated enclosure including the battery and thermal source as a combined, portable package.

Claims

1. A modular thermal device, comprising: a thermal vessel having a thermally insulated casing surrounding a storage volume, the thermally insulated casing having a thermal transfer chamber, a vacuum chamber, and a phase change layer, the thermal transfer chamber having a plurality of ports for exchanging a transfer medium to conduct heat between the storage volume and a thermal source.

2. The device of claim 1 wherein the transfer medium is defined by a liquid throughput transport between the thermal source and the thermal exchanger.

3. The device of claim 2 wherein the liquid transfer medium flows at a pressure substantially below a gaseous cooling medium in an evaporative refrigeration system.

4. The device of claim 3 wherein the liquid transfer medium remains in a single phase and below 25° C.

5. The device of claim 1 wherein the thermal vessel defines a layered encapsulation around the storage volume, further comprising: a phase change layer having a phase change material; a thermal transfer layer defined by the thermal transfer chamber, the thermal transfer layer configured for fludic flow of the transfer medium between the plurality of ports; a vacuum layer defined by the vacuum chamber, the vacuum layer having an insulating void for maintaining thermal inertia.

6. The device of claim 5 wherein the thermal vessel disposes the phase change layer at an innermost position and adjacent the storage volume; the vacuum layer in an outermost position; and the thermal transfer layer between the phase change layer and the vacuum layer.

7. The device of claim 5 wherein the thermal transfer layer includes a tubular array surrounding the storage volume.

8. The device of claim 5 wherein the phase change material is most responsive between 4°-5° C.

9. The device of claim 5 wherein the thermal vessel maintains a temperate between 4°-10° C. for 10 days.

10. A refrigeration apparatus having high thermal inertia for cooling longevity, comprising: a thermal source adapted for thermal exchange with a fluidic transfer medium; a thermal exchanger receptive to a flow of the cooling/heating medium and adapted for fluidic exchange with the thermal source; an insulated enclosure adapted for item storage in conjunction with the thermal exchanger; and an engageable fluidic coupling between the thermal source and the thermal exchanger for detachable engagement of the thermal exchanger.

11. The apparatus of claim 10 wherein the thermal exchanger is a thermal vessel having a layered construction.

12. The apparatus of claim 10 wherein the thermal exchanger has rigid construction for defining a vacuum enclosure jacket around the cooling volume and is adapted for receiving a PCM (phase change material) coating.

13. The apparatus of claim 10 wherein the thermal exchanger includes at least one of a: thermal dissipater, flexible pouch, thermal transfer chamber, and a modular volume.

14. The apparatus of claim 10 wherein the thermal exchanger and the engageable fluidic coupling are adapted for low pressure transfer of a liquid phase material.

15. A method of portable cooling of perishable items, comprising: connecting a thermal source adapted for thermal exchange with a fluidic transfer medium with a thermal exchanger receptive to a flow of the transfer medium and adapted for fluidic exchange with the thermal source, wherein the thermal exchanger is defined by a thermal vessel having a thermally insulated casing surrounding a storage volume, and the thermally insulated casing has a thermal transfer chamber, a vacuum chamber, and a phase change layer.

16. The method of claim 15 further comprising connecting, via an engageable fluidic coupling, between the thermal source and the thermal exchanger for detachable engagement of the thermal exchanger.

17. The method of claim 16 wherein the transfer medium is defined by a liquid throughout transport between the thermal source and the thermal exchanger.

18. The method of claim 17 wherein the thermal vessel defines a layered encapsulation around the storage volume, further comprising: a phase change layer having a phase change material; a thermal transfer layer defined by the thermal transfer chamber, the thermal transfer layer configured for fluidic flow of the transfer medium between the plurality of ports; and a vacuum layer defined by the vacuum chamber, the vacuum layer having an insulating void for maintaining thermal inertia.

19. The method of claim 18 wherein the phase change material is most responsive between 4°-5° C.

20. The method of claim 16 wherein the thermal exchanger and the engageable fluidic coupling are adapted for low pressure transfer of a liquid phase material.

21. The method of claim 16 further comprising powering the thermal source from alternating iterations of solar power.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The foregoing and other objects, features and advantages of the invention will be apparent from the following description of particular embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

[0012] FIG. 1 is a context diagram of a portable refrigeration apparatus suitable for use with configurations herein;

[0013] FIGS. 2A-2B show a flexible thermal exchanger in the modular cooling volume of FIG. 1;

[0014] FIGS. 3A-3C show a rigid vessel thermal exchanger in the modular cooling volume of FIG. 1; and

[0015] FIG. 4 shows the rigid vessel disposed in a transportable pack.

DETAILED DESCRIPTION

[0016] Configurations below depict several configurations of an example modular cooling volume suitable for use with configurations herein. A thermal source adapted for thermal exchange with a fluidic transfer medium combined with an engageable fluidic coupling between the thermal source and the thermal exchanger provides for detachable engagement of the thermal exchanger in a verity of contexts. The thermal exchange may take the form of a flexible, fluid carrying pouch, or a rigid thermal vessel having substantial vacuum and phase-change lining features for thermal inertia. Both may be combined with an integrated, insulated enclosure including the battery and thermal source as a combined, portable package.

[0017] FIG. 1 is a context diagram of a portable refrigeration apparatus suitable for use with configurations herein. Referring to FIG. 1, in an ambient environment 100, a modular cooling volume 110 is cooled by a thermal source 120. In the discussion herein, the thermal flow is described in terms of a cooling operation, in which it is desirable to maintain the modular cooling volume at a temperature lower than an ambient temperature in the ambient environment 100. Configurations discussed below depict an arid setting, such as might be encountered in desert tactical environments, and hence it is desirable to maintain cooled items, such as water, medicine and blood. The same principles could be applied to heating a modular volume 110′ in an artic or cold ambient environment.

[0018] The thermal source 120 delivers a liquid transfer medium 122 for exchanging heat from the modular cooling volume 110. Bidirectional transfer tubes 124 deliver the transfer medium 122 to and from the modular cooling volume 110. The transfer medium 122 may be fulfilled by water, as water has ideal thermal conduction properties and will not freeze in a refrigeration (above 0° C.) setting, as is typically expected of the thermal source 120. Alternatively, other liquid cooling mediums may be employed, such as a solution for lowering the freezing point of water. It should be noted, however, that the low pressure operation of the modular cooling volume 110 and transfer tubes 124 benefit from avoiding the need for a pressurized gaseous medium and high pressure components. Cooled water or other low-pressure liquid transfer medium 122 emanates from the fluid source 120. In the event that the thermal source includes evaporative refrigerant, such refrigerant is entirely contained within the thermal source 120 and need not be plumbed throughout the cooling volume 110.

[0019] The modular cooling volume 110 may take a variety of forms, and interchanges using an engageable fluid coupling 130. The engageable fluid coupling 122 sealably engages both sides (tubes) of the transfer tubes 124. The engageable fluid coupling 130 may be integrated with the modular cooling volume 110 in a variety of configurations, discussed further below.

[0020] Power is provided by a rechargeable lithium ion battery 112 having suitable capacity and portability. A typical battery size may be around 300 watt hours.

[0021] A battery operated cooling/heating plant, or micro-fridge/heater, attached to a ruggedized outer pack or storage containment, forms the base of the remotely deployable modular cooling/heating apparatus. The modular cooling/heating apparatus as disclosed herein includes a cooling/heating plant adapted for thermal exchange with a fluidic medium, and a thermal exchanger receptive to a flow of the fluidic medium and adapted for fluidic exchange with the cooling plant. An insulated enclosure having the thermal exchanger disposed therewithin has an interior volume for containing a cooled/heated payload. The engageable fluidic coupling between the cooling plant and the thermal exchanger is adapted for transport of the cooling medium between the cooling plant and the thermal exchanger. Depending on the configuration, a plurality of engageable fluidic couplings are operable for directing the cooling medium through one or more insulated enclosures, such as for disposing a smaller backpack like insulated enclosure inside a larger insulated enclosure, which allows for storing additional payloads which may or may not be actively cooled/heated by the cooling/heating plant, i.e. water, IV bags, etc. The insulated enclosure and any subsequent larger enclosures employ an outer polychromatic coating which is capable of reflecting infrared radiation. This polychromatic layer increases the thermal resistance of the insulated enclosures when exposed to sunlight or placed near hot surfaces.

[0022] In contrast to conventional refrigeration systems, where a refrigerant such as R134a or related compounds alternate between a liquid and a gas under high pressure, the fluidic thermal transfer medium is of relatively low pressure during transport between the cooling plant and the thermal exchanger. Since the fluidic medium flows through low pressure vessels or tubes, a selectively engageable fluidic coupling allows for detachment of the thermal exchanger without any loss of R134a refrigerant for the cooling/heating plant. Therefore, the thermal exchanger may couple/de-couple as many times as necessary to/from the cooling/heating plant by a plurality of selectively engaging bidirectional fluidic couplings, permitting the insulated enclosure to be disposed in any number of larger insulated enclosure or other configurations while maintaining a liquid tight seal on all fluidic vessels as well as the thermal exchanger and cooling/heating plant. Further, since the thermal medium is fluid based and said fluid is not under pressure when the system is not in operation, incidental fluid loss may be easily replaced.

[0023] In a configuration where the cooling medium (water or alcohol/glycol) isn't accessible at the modular cooling volume, as with a vacuum insulated vessel (discussed below), any suitable portion of tubing in the cooling medium circuit (generally a tubing loop) is responsive to disconnection at any junction for insertion of a purge/fill assembly. Such a purge/fill assembly may be as basic as a jar with a screw cap on the top such that one of the coolant lines goes into the lid and the other extends to the bottom of the jar to draw the cooling medium into the cooling/heating plant and subsequent system. This allows one to access the flow within the system and add/remove liquid.

[0024] In an example arrangement, the thermal exchanger includes a fluid bladder having flexible sides and a deformable shape adapted for conformance to an interior of the insulated enclosure, and a plurality of fluidic couplings operable for bidirectional exchange of the fluidic medium between the cooling plant and the thermal exchanger. The fluid bladder may include receptacles adapted to receive containers of payload items to be cooled/heated, to increase surface area contact of the cooling medium with payload items (such as water bottles).

[0025] FIGS. 2A-2B show a flexible thermal exchanger in the modular cooling volume of FIG. 1. Referring to FIGS. 1-2B, in FIG. 2A a fluid bladder 200 employing fluidic tubes 224 contains the transfer medium 122 cooled and pumped from the thermal source 120. The fluidic tubes 224 complete an input and output flow, respectively, from the transfer tubes 124 via ports 225.

[0026] The fluid bladder 200 employs recesses 210 sized for receiving water bottles or similar container. The entire fluid bladder 200 is intended to be disposed in the larger insulated enclosure for providing cooling capability to an interior of the enclosure, discussed further below in FIG. 4. This feature is illustrative of an advantage of a low pressure liquid transfer medium 122. Any suitable fluid receptacle adapted to receive a liquid flow may be employed as the fluid bladder 200 or modular cooling volume 110. The fluid bladder 200 may also be opened and the water bottles can be directly immersed in the fluid for even better heat transfer performance.

[0027] The liquid transfer medium 122 flows at a pressure substantially below a gaseous cooling medium in an evaporative refrigeration system. Hence, the fluid bladder 200 need not withstand high pressures of evaporative refrigerant (typically anywhere between 50-500 psi), allowing construction of flexible plastic. Pressure need only be sufficient to force water or a water solution transfer medium through the tubes 124 and fluid bladder 200 or other thermal exchanger. The liquid transfer medium 122 remains in a single liquid phase and below 25° C., down to just above freezing (i.e. 1° C.), for water or similar solution, for maintaining cooling. In a heating context, the liquid transfer medium may be around 83° C. Other fluids used as the transfer medium 122 may have analogous ranges. For example, a glycol/alcohol mixture may be cooled to −18 C.

[0028] Alternatively, a cooling panel 250 defines the thermal exchanger in the modular cooling volume 110. FIG. 2B shows a cooling panel 250 including a planar, flexible shape, in which the fluidic tubes 224 are integrated in or layered between flexible plastic. The tubes 224 traverse the area of the panel in a series of “S” curves and/or parallel arrangement for increasing tubular area. The cooling panel 250 may be placed in the bottom of the insulated enclosure or wrapped around or over items in the insulated enclosure.

[0029] The disclosed insulated enclosure and thermal exchanger pouch are suitable for providing refrigerated storage for perishable, water, and medicinal items for a duration of battery longevity and for a time thereafter. However, in a further embodiment, the insulated enclosure takes the form of a rigid thermal vessel employing a vacuum insulated region and phase change material, which, when coupled with the thermal source, provides an extended duration of refrigeration throughout extreme ambient heat and without external charging.

[0030] FIGS. 3A-3C show a rigid vessel thermal exchanger comprising the modular cooling volume 110 of FIG. 1. Referring to FIGS. 3A and 3B, the thermal vessel 300 defines a layered encapsulation around the storage volume for storing refrigerated items, and is constructed of a rigid metal such as stainless steel. The thermal enclosure 300 includes a vacuum layer 310 defined by the vacuum chamber 320, in which the vacuum layer 310 has an insulating void 320 for maintaining thermal inertia, a thermal transfer layer 312 defined by the thermal transfer chamber 322, in which the thermal transfer layer is configured for fluidic flow of the transfer medium 122 between the plurality of ports 225, and a phase change layer 314 having a phase change material. A lid 305 of similar constructing engages the thermal vessel 300 via threaded, clamped, or other suitable mechanism.

[0031] Any suitable arrangement of the layers 310, 312 and 314 may be employed, however in the example arrangement, the thermal vessel 300 disposes the phase change layer 314 at an innermost position and adjacent the storage volume 301, disposes the vacuum layer 310 in an outermost position, and the thermal transfer layer 312 between the phase change layer 314 and the vacuum layer 310. A stainless steel layer may form the interior of the cooling volume.

[0032] The thermal transfer layer 312 may be an open chamber for receiving the transfer medium 122, as depicted in FIG. 3A. Alternatively, an arrangement of elongated vessels or tubes may be employed. In FIG. 3B, the thermal transfer layer 312 includes a tubular array 350 surrounding the storage volume 301, through which the transfer medium 122 flows. In either the tubing array 350 or the continuous chamber 322, the liquid transfer medium flows in to the cooling volume 110 as cooled water, absorbs heat, and expels heat through the thermal source from the return flow. The phase change layer 314 increases thermal inertia, such that the phase change layer 314 absorbs substantial heat after being cooled below a particular range based on the properties of the phase change material. In the example configuration, the phase change material is most responsive between 4°−5° C., just above the freezing point of a water based transfer medium. In the particular case of blood plasma, for example, once cooled below 4° C., the phase change material will absorb substantial heat before rising above 4° C.

[0033] The phase changer material operates best when the transfer medium is in contact with the phase change material, or when the tubes are in contact with the phase change material for facilitating a re-freeze of the phase change material.

[0034] Suitable phase change materials (PCMs) include salt hydrate based positive temperature PCMs, having a freeze and melt at temperatures above 0 C (32 F). An alternate phase change material range would be phase change material which is rated between 7-8 C, and which could employ a smaller refrigeration system.

[0035] In operation, to leverage the thermal inertia of the phase change layer, the approach includes pre-freezing the thermal vessel 300 vacuum chamber before use at around 0 F (−18 C), for example, using a phase change material of the 4-5 C kind. This freezes the phase change material and provides a significant extension of storage time during operation. During deployment, re-freezing the phase change material would not be needed, as this would consume substantial power. Rather, the thermal vessel 300 cycles between 6-10 C. as an optimal range, this reduces the system's run time per cycle. However, refreezing of the PCM is attainable with a larger refrigeration unit and/or additional batteries or hardwiring of the system to a continuous power source. PCMs of the disclosed 4-5° C. range or—PCMs with 7-80° C. properties could be employed, for either an initial freeze or cyclic freezing.

[0036] A solar panel or flexible solar panel may be used to charge the system's battery while the system is in operation or in an idle mode via a digital charge controller to extend the operational time of a single battery. Said flexible solar panel may be attached to the system's insulated enclosure in a plurality of ways and may also be used to shade from solar radiation during operation.

[0037] The heating/cooling plant's operation may be automated via a digital controller and thermocouple sensors which monitor the cooling/heating medium and or the thermal vessel 300 vacuum chamber's internal temperature. Said digital controller can also display in real-time the temperature readings from the thermocouples.

[0038] FIG. 3C shows a perspective view of the rigid thermal vessel 300, cooled volume 301 and lid 305.

[0039] FIG. 4 shows the rigid vessel disposed in a transportable pack including the insulated enclosure 160 as the modular cooling volume 110. The transportable pack disposes the battery 112 and thermal source 120 in close proximity and within reach of the transfer tubes 124. The engageable fluidic coupling 130 passes through the exterior of the insulated enclosure 160 for connection to a transfer element such as the cooling pouch 200, cooling panels 250, or thermal vessel 300, shown by cutaway 162. The volume within the insulated enclosure may be used for cooling from the transfer medium 122, and the thermal vessel 300 employed for greater longevity and/or for particularly temperature sensitive items. In an example arrangement, the thermal vessel maintains a temperate between 4°−10° C. for 10 days. at an ambient outside temperature of 105° F., as might be encountered in a desert environment, however various combinations of temperature and longevity are available based on power and the thermal source, detailed below in TABLE I and TABLE II below.

TABLE-US-00001 TABLE I Time 62 Watt Anticipated Sunlight Capable of Solar Panel Storage time Ambient at 1000 storing 1 in use of 1 Liter of Cooling Temperature W/M{circumflex over ( )}2 Liter of during liquid below Unit Day (8 Hours) On Liquid daylight 50 F. if solar Battery Power Night (16 Hours) System below 50 F. hours panel used used Draw 95° F.-85° F. Yes  80 Hours No 112 300 100 W W/Hrs 95° F.-85° F. No 112 Hours YES 80 300 100 W W/Hrs 115° F.-95° F.  Yes  60 Hours No 84 300 100 W W/Hrs 135° F.-105° F. Yes  30 Hours No 42 300 100 W W/Hrs

[0040] Table I shows testing results based on the thermal vessel 300 being tested under various diurnal cycles. Various parameters may be extrapolated, for example doubling the battery capacity would double the runtime. Typical battery runtime (300 W/Hrs) is around 4 hours. Anticipated storage times where the solar panel could be used are derived from test results where the solar panel was used.

TABLE-US-00002 TABLE II Time to Cool 2 Liter of uncirculated liquids (IV BAG/bottled water, etc) LOWEST TEMP of Cooling AND 1 Gallon of circulated Circulated liquid Unit Ambient liquid to 98 F. from achievable and in Battery Power Temperature ambient starting temp what timeframe used Draw  95° F.  8 MIN 219 MIN to 49 F. 300 W/Hrs 100 W 110° F. 11 MIN .sup. 190 MIN to 56.6 F. 300 W/Hrs 100 W 120° F. 15 MIN 180 MIN to 61 F. 300 W/Hrs 100 W

[0041] Table II depicts various parameters and effects on performance of the fluid bladder 200 configuration above.

[0042] While the system and methods defined herein have been particularly shown and described with references to embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.