The disclosed technology pertains to phase change material insulators for providing passive cooling of shipping containers and storage containers.
Advancements in shipping containers and storage containers have been driven by the increasing quantity, cost, fragility, and perishability of goods that may be shipped using standard infrastructure (e.g., ground and air vehicles used to ship mail and other packages containing non-perishable goods). With such advancements, expensive medicines, electronics, and other goods that may previously have been delivered by a specialized courier services may instead be packed in specialized shipping containers and transported along standard transit routes.
Goods shipped in such containers may have thresholds for such factors as temperature, motion, humidity, and other characteristics during storage and transport. Deviations outside of acceptable ranges for these characteristics may affect the quality or efficacy of a shipped good, or in some cases may even completely ruin a good or make it harmful when used for its intended purpose.
Sensitive goods may be shipped in containers that include active protection features, passive protection features, or both. Active protection features may include temperature control, climate control, internal power supplies, location tracking, and other features. Passive protection features may include insulation materials, shock absorption materials, electromagnetic shielding, and other features.
While active protection features often provide the highest level of protection for sensitive goods, they are often the most complex and most expensive to implement and support. As a result, passive protection features may be combined with active protection features in order to improve overall performance of the shipping container, or may be used as a sole means of protection where appropriate (e.g., goods having low or moderate sensitivity, goods being shipped for short distances). Passive protection features for maintaining temperature or other climate aspects within a shipping container are typically limited in both the extent and the duration for which they can influence temperature. As an example, a block of ice may be considered a passive temperature protection feature that cools the air within a container, as well as any other surfaces or materials that the ice is in direct contact with.
However, the temperature control provided by a block of ice will be limited both by the ice's own temperature (e.g., the temperature to which the ice is cooled prior to being placed in the shipping container) as well as the period of time that it takes to completely melt. Insulation materials and other conventional passive temperature protection features are limited in other ways. As a result, passive temperature protection features are typically incorporated into shipping containers due to their low cost and simplicity rather than their overall effectiveness relative to active temperature protection features.
What is needed, therefore, is an improved passive temperature protection feature for shipping containers.
The drawings and detailed description that follow are intended to be merely illustrative and are not intended to limit the scope of the invention as contemplated by the inventors.
The inventors have conceived of novel technology that, for the purpose of illustration, is disclosed herein as applied in the context of temperature control for shipping containers. While the disclosed applications of the inventors' technology satisfy a long-felt but unmet need in the art of temperature control for shipping containers, it should be understood that the inventors' technology is not limited to being implemented in the precise manners set forth herein, but could be implemented in other manners without undue experimentation by those of ordinary skill in the art in light of this disclosure. Accordingly, the examples set forth herein should be understood as being illustrative only, and should not be treated as limiting.
Variations on the methods, features, and devices described herein may be implemented to provide advanced phase change material (PCM) based passive temperature control for shipping containers and other applications. Such PCM features are advantageous in providing additional or alternative passive temperature control, and thus may be used in conjunction with or as a replacement for conventional passive temperature control features such as ice, insulation, air gaps, and other features. While water (e.g., water in liquid form or, as ice, water in solid form) may itself be considered a basic PCM, the use of water is not always possible or appropriate for shipping containers. As an example, shipped goods are often sensitive to water, and so the use of water as a basic PCM introduces additional risks and requires additional safeguards and systems to address such risks. Additionally, when water is frozen into blocks it may melt unevenly during phase change back into a liquid. Thus, ice cannot maintain a consistent desired form throughout phase change, making it inappropriate for precise contact packing in and around surfaces of a container or good. Additional challenges with water as a basic PCM include weight, difficulty of transport in liquid and solid forms, risk of contamination over time, evaporation, and general fluid dynamics (e.g., movement of water within a container that may shift the containers center of gravity).
As an example of an advanced PCM, a liquid salt hydrate may be encapsulated into a polymer microcapsule of varying sizes that is able to contain the liquid through multiple phase change cycles. When the microcapsule is conditioned for freezing temperatures, the salt hydrate will freeze within the capsule. When exposed to a later temperature differential, the salt hydrate will phase change back to a liquid while absorbing thermal energy from its surroundings. While in liquid state, the impermeable microcapsule prevents the salt hydrate from evaporating or otherwise escaping.
Microcapsules or other advanced PCMs may then be incorporated into coatings or other treatments that may be applied to target objects. As described herein, advanced PCM coatings and treatments may be advantageously implemented to provide a variety of features and applications for shipping containers. By improving passive temperature control for shipping containers such implementations may reduce the burden on active temperature control features and, in some cases, allow for certain goods that typically require active temperature control to instead be shipped using only passive temperature control.
For example, the shipping container (10) of
I. PCM Fabric Covers
In some implementations, the edges (102, 103) of the PCM cover (100) may be in different positions to allow for varying ways in which it can be placed onto or provide access to the cargo (44) (e.g., a flap may hang from a top of the PCM cover (100) and may couple with overlapping edges on one or more sides). In some implementations, the PCM cover (100) may not include any openable flap portions, and instead may be slid onto the cargo (44) from above Other variations on the shape and characteristics of the PCM cover (100) exist and will be apparent to those of ordinary skill in the art in light of this disclosure.
Once in place, the PCM cover (100) provides a passive temperature control advantage for the cargo (44), especially where a snug fit between the PCM cover (100) and the cargo (44) can be achieved. With reference to
Referring to
Microcapsule 120 may vary in size such that microcapsule 120 is able to contain the salt hydrate 122 through multiple phase change cycles. For instance, when microcapsule 120 is conditioned for freezing temperatures, the salt hydrate 122 can freeze within microcapsule 120. When exposed to a later temperature differential, the salt hydrate 122 can phase change back to a liquid while absorbing thermal energy from its surroundings. While in liquid state, polymer 124 inhibits the salt hydrate 122 from evaporating or otherwise escaping.
With such an arrangement, the cargo (44) receives the reflective benefit of two layers of thermal foil (104, 108), an insulation value from the cloth of the core (106), and also a phase change initiated heat absorption from the PCM treatment of the cloth (106). When the PCM cover (100) is conditioned prior to use (e.g., by placing into a freezer or other cooled environment to reduce the temperature of a PCM such as a salt hydrate) the resulting equivalent insulation value or passive temperature control value exceeds that of cloth or foil alone.
The thickness of each layer and the type of material used for each layer may be varied depending upon a particular application, and the number of layers may also be varied, with such variations being apparent to those of ordinary skill in the art in light of this disclosure. For example, some implementations may lack an inner layer (108) so that the core (106) may directly contact the cargo (44). Some implementations may include two core layers and three foil layers to further increase the volume of PCM microcapsules carried by the PCM cover (100). Layer type may also vary across the PCM cover (100). For example, flat sides of the PCM cover (100) may include a core layer (106) that is semi-rigid and provides a higher concentration or larger size of PCM microcapsules, while each corner (105) of the PCM cover (100) includes a core layer (106) that is more flexible due to a lower concentration or smaller size of PCM microcapsules.
The above described use of PCM treated fabric to implement the core (106) differs from conventional PCM fabric uses in a number of ways. Typically, PCM fabrics are incorporated into personal goods such as cold weather garments, athletic garments, sleeping bags, and other goods that a person is in direct contact with during use. In such scenarios, user comfort (e.g., breathability, comfort against skin, flexibility) is a primary concern. When implementing the core (106) the PCM treatment of fabric can instead maximize thermal performance (e.g., by increasing the size or concentration of microcapsules, or characteristics of the carrier fluid used in coating or treating) without regard to comfort. As a result, the PCM carrier fluid that is applied to the core (106) may dry or cure as a semi-flexible rubberized coating having its own insulation value and carrying a high concentration of encapsulated PCM.
Covers such as the PCM cover (100) may be readily implemented in different sizes and shapes to provide custom fitting to cargo or to provide a variety of standard sizes. Additionally, while the cargo pallet (40) includes one cover, multiple covers may be used when preparing a cargo pallet. As an example,
The flexibility in size and shape that PCM covers may be produced in allows for goods to be wrapped in a desired number of layers. For example, room temperature produce placed on a pallet may only require a single layer of PCM covering during transit while a batch of liquid medicine may require several layers, such that the cargo (46) includes additional internal PCM cover layers not shown in
In addition to providing PCM covers as described, other PCM fabrics and structures may be implemented for use in shipping containers. As an example,
It should also be understood that a modular cover may have more than two connecting or overlapping edges as may be desired, or may couple together in positions other than along an edge. For example, in some implementations the modular cover (200) may have more than two overlapping and interconnectable edges. As another example, some implementations of the modular cover (200) may not have dedicated edges for coupling, and instead may have a plurality of Velcro sections across the surface (202) that may couple with a back surface opposite the surface (202). In this manner, the modular covers (200) may be coupled together in nearly any desired shape whether rectangular or irregular.
Some implementations of the modular cover (200) also include a conditioning indicator (206) that indicates the extent to which the modular cover has been conditioned (e.g., cooled and/or frozen) prior to use.
Other variations in the design and placement of conditioning indicators (206) exist and will be apparent to those of ordinary skill in the art in light of this disclosure. It should also be understood that conditioning indicators may also indicate when modular covers (200) should be changed or replaced during transit, where conditioned replacements are available. Additionally, while the conditioning indicator (206) is shown as being included on the modular cover (202), it should be understood that the same or a similar device may also be included on the PCM cover (100) or on any other PCM fabric, structure, or feature described herein.
As another example of a PCM fabric implemented feature,
II. PCM Panels
Several passive temperature management features that may be implemented with flexible PCM fabric have been discussed. Flexible covers like the PCM cover (100) and modular cover (200) are advantageous in that they can be flexibly fit and shaped onto goods as may be desired. However, rigid PCM features are also possible and provide a number of advantages when combined with or used as an alternative to flexible PCM fabrics and other temperature control features.
Rigid PCM components are generally referred to herein as “panels,” even where they include surface contouring or interior spaces designed to fit certain application. PCM panels may be applied to palletized cargo such as the cargo pallet (40), may be used as filler for palletized cargo or within boxes, and may be applied to the shipping container itself to provide additional physical protection and passive temperature control. PCM panels may also be used to fabricate containers such as boxes or envelopes (e.g., such as the PCM envelope (300)) where a rigid structure may be preferable to a flexible body.
As an example of a PCM panel,
The core layer (410) may be formed of a composite material that includes PCM capsules, structural fibers or other filler material, and a binding material such as an adhesive, rubber, or polymer that may be dried or cured to bind the structural material and PCM capsules into a rigid or semi-rigid piece. As an example, one implementation of the core layer (410) may include a mix of PCM capsules and polymer structural fibers suspended within an expanding urethane foam. As another example, a highly porous fibrous structure may be produced that may be permeated with a PCM capsule fluid that dries, cures, or is otherwise contained within porous gaps. As another example, a grid or netting of interconnected structural fibers may also be overlaid on each side of the core layer (410) and/or spread throughout the core layer (410) for additional durability.
The first layer (408) and the second layer (412) may be, for example, foam sheets to provide additional protection and insulation, rigid polymer gridworks to provide additional rigidity, or PCM fabrics such as those described above to provide additional physical protection and concentration of PCM capsules. The type and number of layers included in a particular panel may be varied greatly depending upon a particular application.
For example, some implementations of the PCM panel (400) include only the core layer (410) (e.g., a semi-rigid PCM capsule and fiber composite) and the outer layer (406) (e.g., a thermal foil wrapped vacuum sealed skin). Some implementations may additionally include PCM fabric layers as the first (408) and second layers (412), to provide additional shock and impact protection, insulation, and PCM temperature control. Some implementations may include multiple core layers, multiple outer layers, or multiple other layers, with any such variations being apparent to those of ordinary skill in the art in light of this disclosure.
As has been described, PCM panels (400) may be fabricated in various shapes and sizes by varying the number of layers, the thickness of layers, the shape of the core layer (410), or by separately fabricating and then coupling together multiple individual pieces (e.g., assembling 5 PCM panels to create a box). This flexibility allows PCM panels (400) to be created and used in a variety of applications for shipping containers. As an example, this could include applying panels to surfaces of goods, inserting panels between or within goods, using shaped panels to fill gaps within a container to provide additional temperature control and prevent shifting during transit, and other uses.
This could also include applying PCM panels (400) on one or more surfaces of a shipping container, as shown in
In some implementations the panels (420, 422, 424, 426) may be inserted into a set of rails that run along a surface of the interior and slid into place so that the rails align and hold them against the wall. In some implementations, a set of mechanical clips or grips (e.g., a spring grip, screw grip, or insertable grip) may be operated once the panel (420, 422, 424, 426) is in place to secure the panel. In some implementations, each panel may be secured in place by the combined set of installed panels (e.g., the rear wall panel (422) may be friction fit between the other wall panels (420, 424), and each of the set of wall panels (420, 422, 424) may be friction between the floor and a ceiling panel (426)). In some implementations, an air gap may be present between a wall of the interior (36) and an outer wall of the structure (32). In such cases, a panel may be inserted into the air gap between the inner and outer walls. As an example, a floor panel (428) is shown installed within a pocket below the floor of the interior (36).
A door panel (430) can also be seen installed on an interior face of one of the doors (34), while the other door (34) is shown without a panel. As can be seen, the exposed door (34) includes a set of contoured portions (38) along its inner face. The door facing portion of the door panel (430) is shown in
As can be seen in
As another exemplary application of PCM panels,
Production and use of various PCM features has been described in some detail.
Other variations and examples exist and will be apparent to those of ordinary skill in the art in light of this disclosure. For example,
Based upon determined (500) details, one or more core layers may be shaped and produced (502). As an example, this may include fabricating core layers of a certain shape and size to fit an interior of a shipping container based upon determined (500) dimensions, or may include fabricating core layers of a certain thickness or providing multiple core layers based upon determined (500) temperature control requirements. Additional layers may also be created and/or applied (504) to the core layers, which may include adding additional structural substrates, PCM fabrics, reflective or non-conductive surfaces, and other layers. Selection of additional layers may also be base don the determined (500) characteristics, as shipping requirements, shipping container dimensions, and other factors may indicate a need for extra rigidity, physical durability, or PCM based temperature control.
After creating (502) the core layers and applying (504) additional layers, the assembly may be sealed within an outer layer material to produce (506) a usable panel. This may include sealing the layers within a thermal foil vacuum seal exterior skin, wrapping the layers in a plastic or polymer, or sealing the layers within a treated paper product. Produced (506) panels may then be conditioned (508) by placing them in a cool environment until a desired temperature is reached (e.g., a temperature of the core layer or innermost concentration of PMC capsules). Conditioning (508) may also include applying or placing conditioning indicators on panels as they are produced (506) or as they are conditioned (508). When panels have reached a desired temperature, they may be selected (e.g., based upon a total time of conditioning, a visual indication from a conditioning indicator, or other criteria) and installed (510) on or within a shipping container or a set of goods.
It should be understood that any one or more of the teachings, expressions, embodiments, examples, etc. described herein may be combined with any one or more of the other teachings, expressions, embodiments, examples, etc. that are described herein. The following-described teachings, expressions, embodiments, examples, etc. should therefore not be viewed in isolation relative to each other. Various suitable ways in which the teachings herein may be combined will be readily apparent to those of ordinary skill in the art in view of the teachings herein. Such modifications and variations are intended to be included within the scope of the claims.
Having shown and described various embodiments of the present invention, further adaptations of the methods and systems described herein may be accomplished by appropriate modifications by one of ordinary skill in the art without departing from the scope of the present invention. Several of such potential modifications have been mentioned, and others will be apparent to those skilled in the art. For instance, the examples, embodiments, geometrics, materials, dimensions, ratios, steps, and the like discussed above are illustrative and are not required. Accordingly, the scope of the present invention should be considered in terms of the following claims and is understood not to be limited to the details of structure and operation shown and described in the specification and drawings.
This application claims priority to U.S. Provisional Application No. 62/958,361, entitled “Phase Change Material Insulation For Containers,” filed on Jan. 8, 2020, the disclosure of which is incorporated by reference herein.
Number | Date | Country | |
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62958361 | Jan 2020 | US |