Patent Grant
10119741
A refrigerant bunker for use with solid refrigerants and a cooler employing the refrigerant bunker.
Insulated containers are used for the transportation of refrigerated and frozen products, and are used in many industries for shipping a wide variety of temperature sensitive products. Additionally, consumers and businesses often use insulated portable, and/or personal coolers, such as ice chests, to transport refrigerated food, frozen food, beverages and a wide spectrum of temperature sensitive products so that they may be stored, sold, enjoyed and/or consumed at specific temperatures, and to prevent spoilage until the products are used.
Based on the desired temperature for a specific product, a user may choose to use a refrigerant such as water ice, gel packs, or dry ice. Each of these refrigerants has a distinct temperature range that it operates within. Water ice operates at a temperature of about 33 degrees Fahrenheit (° F.) and maintains that temperature by changing phases (solid to liquid). Gel packs, also referred to as “ice packs,” are engineered to maintain a similar temperature, but can range from approximately 5 to 50° F. Finally, dry ice sublimates at a temperature of about minus 110° F. Thus, dry ice is known for use as a refrigerant when the product temperature is desired to be in a very low range.
For cooling product at temperatures above freezing, dry ice is often not an acceptable refrigerant. For example, the extreme cold temperatures produced by sublimating dry ice can freeze the contents of beverage containers, such as soda cans, resulting in the beverage container losing its integrity. Likewise, fresh fruits, vegetables, sandwiches, and the like often cannot be packed directly in dry ice because if such foods freeze solid it can affect palatability.
Using dry ice in an insulated bunker as a source of refrigerant to maintain cool or cold temperatures inside of temperature controlled containers is well known. Dry ice cooling techniques often involve insulating the dry ice from the interior of the temperature controlled container while regulating the flow of sublimated CO2 gas into the temperature controlled container as a means of regulating the cooler temperature. This technique works well for larger, commercial type coolers, where the size of the cooler is relatively large compared to the size of the solid refrigerant bunker. However, for smaller, portable type coolers, it can be difficult or impossible to control the temperature of the cooler in order to maintain a temperature that is much warmer than the refrigerant sublimation temperature by regulating convective carbon dioxide gas flow. Further, limiting conductive heat transfer in such convection controlled systems can involve employing large amounts of insulation surrounding the dry ice refrigerant, which increases costs and takes up relatively large amounts of the space.
U.S. Pat. No. 6,212,901 discloses a cooler with a chamber and a cavity in its lid. A block of dry ice is inserted into the cavity. Heat transfers from the chamber through a heat transfer element, such as a plate of aluminum, connecting the chamber to the cavity. The rate of this heat transfer is regulated by covering or uncovering the heat transfer element in the chamber side. However, integrating a separate heat transfer element into the cooler can cause increased fabrication complexity and expense. Further, this design has the undesirable potential of excessively cooling any materials that are too near, or come in contact with, the heat transfer element.
Thus, an improved cooler design that employs a sublimating refrigerant, such as dry ice, would be a welcome addition to the art.
An embodiment of the present disclosure is directed to a refrigerant bunker. The refrigerant bunker comprises a refrigerant covering comprising a first thermally insulating material configured to enclose a solid refrigerant and an outer container comprising a container body and a container cover. The container body comprising an outer surface, an inner surface defining a partially enclosed space configured to accept the solid refrigerant and an opening for accessing the partially enclosed space. The container cover is configured for covering the container opening. The container body comprises a second thermally insulating material. A plurality of spacers protrude from the inner surface of the outer container in the partially enclosed space. The plurality of spacers are positioned to have gas fillable gaps between the spacers.
Another embodiment of the present disclosure is directed to a cooler. The cooler comprises a thermally insulated receptacle comprising one or more sides and a bottom defining a chamber and an opening for accessing the chamber. The sides and bottom comprise a thermally insulating material. A lid comprises a thermally insulating material for covering the opening. The lid is positionable in an open position that allows access to the chamber and a closed position that prevents access to the chamber; A refrigerant bunker is positionable in the cooler. The refrigerant bunker comprises a refrigerant covering comprising a first thermally insulating material configured to enclose a solid refrigerant; and an outer container comprising a container body and a container cover. The container body comprises an outer surface, an inner surface defining a partially enclosed space configured to accept the solid refrigerant and an opening for accessing the partially enclosed space. The container cover is configured for covering the container opening. The container body comprises a second thermally insulating material. A plurality of spacers protrude from the inner surface of the outer container in the partially enclosed space. The plurality of spacers are positioned to have gas fillable gaps between the spacers.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present teachings, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrates embodiments of the present teachings and together with the description, serve to explain the principles of the present teachings.
It should be noted that some details of the figure have been simplified and are drawn to facilitate understanding of the embodiments rather than to maintain strict structural accuracy, detail, and scale.
Reference will now be made in detail to embodiments of the present teachings, examples of which are illustrated in the accompanying drawings. In the drawings, like reference numerals have been used throughout to designate identical elements. In the following description, reference is made to the accompanying drawing that forms a part thereof, and in which is shown by way of illustration a specific exemplary embodiment in which the present teachings may be practiced. The following description is, therefore, merely exemplary.
A refrigerant bunker 22 is positionable in the cooler 10.
Inner refrigerant covering 24 is configured to hold a refrigerant 32. The refrigerant can include any suitable cold source, such as water ice, gel packs, and dry ice. The dry ice can be in any suitable form, such as solid brick or pelletized form. Although dry ice is frequently referred to herein, a skilled artisan will be able to select an appropriate refrigerant for insertion into the enclosed space in a particular embodiment based on various considerations, including the intended use of the refrigerated bunker, the intended arena within which the refrigerated bunker will be used, and the equipment and/or accessories with which the refrigerated bunker is intended to be used, among other considerations. In an embodiment, the refrigerant is dry ice, which can provide dry cooling to a range of temperatures when use in combination with the refrigerant bunker of the present disclosure. It is noted that more than a single type of coolant can be used in a single cooler. For instance, dry ice can be used in combination with water ice, such as where dry ice is used in a refrigerant bunker while water ice is employed in the cooler chamber 12.
The dry ice can have any suitable size or shape, as can the inner refrigerant cover 24 and outer container 26. In an embodiment, the inner refrigerant cover 24 is in the form a sleeve, as shown in
In an embodiment, the inner refrigerant cover 24 can be made from a pliable, thermally insulating material. In an embodiment the material is a polymer, such as polymeric foams and plastics. One example is spun-bonded polyethylene, (a commercial example of which is TYVEK, made by DuPont). Other examples of suitable polymer materials include foam rubber, plastic films, molded plastics, corrugated plastic and bubble wrap, including metal covered bubblewrap, such as aluminum foil covered Mylar bubble wrap. Still other example materials include single-layers or multiple-layers of paper or textiles, such as corrugated paper, paper sheets or cloth, such as nylon or coated nylon. In an embodiment, the material is permeable to gas vaporizing from the solid refrigerant, such as carbon dioxide gas, to allow venting of the gas through the material. In other embodiments, the material may be substantially impermeable.
The structure of the inner refrigerant cover 24 can vary widely. In an embodiment, the structure results in increased ability to allow the creation of layers of sublimating carbon dioxide gas around the refrigerant. For example, the inner refrigerant cover can be a single layer or multiple layers of a suitable insulating material, such as a sheet of the desired material that is designed to wrap around the refrigerant. Examples include a sheet of paper, foam rubber or plastic that has a sufficient size to completely or partially surround the refrigerant when the refrigerant is wrapped therein. An example is shown in
The insulating properties, gas permeability and number of material and gas layers used in the inner refrigerant cover may be varied to provide corresponding differentiated levels of cooling and will depend on the type of outer container in which the inner refrigerant cover is used (e.g., hard plastic outer container vs. pliable material/fabric outer container). Inner refrigerant cover 24 can comprise one or more layers, such as two or three layers, of insulating material and/or gas. The materials can have limited ability to act as a barrier to thermal energy transfer and also as a barrier to the flow of carbon dioxide sublimate through the inner refrigerant cover material itself. In general, inner refrigerant cover 24 is designed to aid in maintaining the temperature inside the cooler 10 by helping to regulate, in combination with the outer container 26, the amount of thermal energy that is removed from the cooler chamber and absorbed by the dry ice refrigerant.
Container body 27 includes an outer surface 38 and an inner surface 40. The inner surface 40 defines a partially enclosed space for holding the inner refrigerant cover 24 and/or the refrigerant 32. The container body 27 can include one or more material and gas layers to control both the transfer of thermal energy and the release of carbon dioxide gas from the container body. In an embodiment, no ventilation port is required and the container body 27 is not required to be airtight or sealed from the outside space adjacent to the refrigerant bunker.
While a generally right, rectangular parallelepiped shape is utilized for the exemplary outer container 26 in
In an embodiment, a plurality of spacers 42, such as those illustrated in
In an embodiment, the outer container body 27 and cover 28 comprise a thermally insulating material that is substantially less permeable, such as relatively impermeable, to carbon dioxide gas compared with the thermally insulating material used to form the inner refrigerant cover 24. Alternatively, the material for the outer container body may have the same permeability or an increased permeability relative to the material of the inner refrigerant cover 24. In an embodiment, the outer container body 27 and/or lid 28 comprise a rigid or pliable plastic that can provide the desired reduced permeability and structural stability under extremely cold conditions. Examples of suitable plastics include high molecular weight plastics, such as ultrahigh molecular weight polyethylene, high density polyethylene (“HDPE”) or foam rubbers, such as high density polyurethane foam. Other materials could include woven fabrics, such as Nylon fabric, rubber and/or composite materials. The materials used for the outer container body 27 and lid 28 can be the same or different. The material selected to construct the outer container 26 may be rigid, semi-rigid or flexible, and may depend upon the refrigerant bunker's ultimate use, for example, military combat use or recreational consumer applications such as backpacking or picnic use.
In an embodiment, the use of thermally conductive materials is avoided in making the inner refrigerant cover and/or the outer container. For example, the inner refrigerant cover 24 and outer container 26 can include no metal. In other embodiments, metal may be employed in a suitable manner so as not to affect the insulation properties of the refrigerant bunker by an unacceptable degree.
In an embodiment, outer container 26 includes only a single layer of thermally insulating material, such as a plastic as described above. In another embodiment, multiple layers can be used. For instance, the outer container 26 can comprise a layered sandwich type structure. For example, referring to
The sides and bottom of the outer container body 27 can be relatively thin, due at least in part to the improved design of the bunker that utilizes the gaps 44 between the refrigerant and the bunker wall as a trapped gas insulation layer. This allows relatively small amounts of insulating material to be employed while still providing the desired insulation of the refrigerant 32 from the outside atmosphere. For example, the outer container sides and/or bottom can have a wall material thickness, Tw, (excluding the gap 44) that is one inch thick or less, such as about 1/16 inch to about ¾ inch, or about ⅛ inch to about ¼ inch or ½ inch. Thicknesses outside these ranges can be employed. Employing the gaps 44 with relatively thin walls can provide for a less bulky container, which is less expensive and takes up a relatively small amount of cooler space. For example, for a 10×10×2 sized refrigerant having a volume of about 200 in3, the refrigerant bunker may occupy a total volume of space inside the cooler of about 300 to about 400 in3 or possibly 600 in3, depending on the materials employed, the size of the gaps 44 and the desired insulation properties of the bunker. Thus, the increase in volume relative to the refrigerant volume can range, for example, from about a 50% to about a 200% increase, and may be less than 100% for some bunker designs.
In an embodiment, the decreased permeability of outer container 26 allows the carbon dioxide gas leaking from the inner refrigerant cover 24 to remain trapped in the outer container 26 for a period of time. The carbon dioxide gas can fill gaps 44 so as to surround the inner refrigerant cover 24 and may also provide carbon dioxide filled spaces in the inner refrigerant cover 24 itself, depending on design of the inner refrigerant cover. Carbon dioxide gas has a relatively low thermal conductivity (e.g., lower than the thermal conductivity of air at temperatures near freezing). Thus, the formation of layers of carbon dioxide gas in outer container 26 and/or inner refrigerant cover 24 can act as an insulator to thermally insulate the refrigerant 32 from outside warmer air and heat that would otherwise be conducted through the outer container 26. The increased insulation can extend the useful life of the refrigerant 32 and allow an increased temperature (e.g., above freezing) to be maintained inside the cooler chamber 12.
Because the outer container 26 completely surrounds the refrigerant, and because the refrigerant bunker 22 results in a reduced rate of sublimation of gas from the refrigerant compared to dry ice without the refrigerant bunker, refrigerant bunker 22 can significantly reduce any cooling effect that may be caused by the flow of carbon dioxide gas from the refrigerant bunker 22 compared to the cooling effect produced by thermal conduction through the refrigerant bunker 22. Thus, while not intending to be limited by theory, it is believed that the primary mechanism for cooling employed when using refrigerant bunker 22 is by conduction through the outer container 26 and inner refrigerant cover 24.
Referring again to
Additionally, the amount of contact surface area between outer container 26 and the inner refrigerant cover 24 can also be determined by the number and shape of the spacers 42. For example, by reducing the contact surface area between the outer container 26 and the inner refrigerant cover, thermal conduction can be reduced, which can also effectively increase the R value of the refrigerant bunker. Thus, the particular size, shape and number of the spacers 42 and gaps 44 can be chosen to vary the effective R value of the bunker and control the cooler temperature. For example, the width, WG, of the gaps 44 between adjacent spacers 42, as measured at the tops of the spacers can generally be greater than the width, WS, of the top most surface of the spacers 42, so that the total area of the gaps 44 at the tops of the spacers is relatively large compared to the area of the top surfaces of the spacers. In an example, the ratio of WG to WS can be more than 2:1, such as 3:1 to about 1000:1 or more, or 4:1 to about 100:1. Example ratios of the total area of the gaps 44, as measured in an imaginary plane that extends across the tops of the spacers, to the total area of the top most surface of the spacers extending from the bottom of the outer container can range from about 2:1 to about 1000:1 or more, such as about 3:1 to about 10:1 or 50:1.
In addition to the insulation value provided by the outer container 26, there is an increased insulating ability provided by the inner refrigerant cover 24, which can also result in a significant increase in the life of the refrigerant and its ability to maintain a relatively constant cold temperature. In an embodiment, the inner refrigerant cover 24 is removable from the outer container 26, as shown in
The inner refrigerant cover of
Spacers 42 are also made from a pliable, thermally insulating material, such as plastic or cloth. The inner refrigerant cover 24, as described above, is attached in any suitable manner to the outer container 26 by spacers 42. For example, the inner refrigerant cover can be fixedly attached to the outer container using any suitable technique, such as by sewing, plastic welding or using an adhesive to attach the spacers 42 to both the inner refrigerant cover and the outer container. Alternatively, the inner refrigerant cover can be removably attached to the outer container, such as by using VELCRO or snaps.
In an embodiment, the material of inner refrigerant cover 24 is relatively permeable to sublimating gases compared to the outer container 26. Alternatively, the material of inner refrigerant cover 24 can have about the same permeability or a reduced permeability relative to the permeability of the outer container 26. The materials and design of the outer container 26 and inner refrigerant cover 24 can be chosen to provide a desired permeability that allows refrigerant gas to fill spaces between the inner refrigerant cover 24 and the refrigerant 32 and/or to pressurize gaps 44. Thus, during use, sublimating gas from the refrigerant can fill the gaps 44 sufficiently so as to maintain a carbon dioxide gas filled space between the inner refrigerant cover 24 and outer container 26. In this manner, the gas filled gaps 44 provide enhanced thermal insulation.
Referring to
In any of the refrigerant bunkers described herein, a pressure release mechanism can optionally be included to vent over-pressurization of the sublimated gas from the outer container 26. In an embodiment, the pressure release mechanism can include, for example, a pressure regulating valve and/or built in leak paths in the container. Such leak paths can include, for example a loose fitting container cover 28, to provide the desired venting between the cover 28 and the container body 27. In an embodiment, gas leakage through a hook and loop type fastener, such as VELCRO®, that is employed to fasten the cover 28 to the body of the outer container 26 can provide the desired leakage path. Any other suitable leakage path that can maintain the desired pressure range of carbon dioxide gas in the refrigerant bunker can be employed, such as by leakage through seams between container pieces, or the permeability of the container materials. In an embodiment, the desired pressure levels, which may be approximately the same as ambient pressures (e.g., about 1 atmosphere) or any desired amount above ambient pressures, are maintained using built in leak paths, such as through use of permeable materials, seams and/or or fasteners such as VELCRO, and no additional convection ports or valves are employed in either the inner refrigerant cover 24 or container 26. In an embodiment, forced convection is not used to move refrigerant gases (e.g., carbon dioxide sublimated from dry ice) into or out of the refrigerant bunker. For example, no fans or other gas moving devices are employed in the bunkers 22 or coolers 10 of the present disclosure.
In an embodiment, the outer container 26 comprises a releasable mounting fixture or unfixed platform for mounting said refrigerated bunker within the cooler 10. For example, as shown in
In an embodiment, refrigerant bunkers 22 are configured for placement and/or mounting within a portable insulated, personal cooler or commercial shipping container, and can be sold either with the coolers or separately from the coolers. The refrigerant bunkers of the present disclosure can be included in the cooler 10 in any suitable manner. In an embodiment, the refrigerant bunker 22 can simply be placed in any desired fixed or non-fixed position in the cooler chamber 12 by a user, such as is shown in
In an alternative embodiment, all or a portion of the refrigerant bunker 10 can be made an integral part of a cooler 10. For example, the outer container 26 of the refrigerant bunker can be integrated into the lid 14, as illustrated in any of
The refrigerant bunkers of the present disclosure can be used with any sized cooler, such as portable coolers or commercial coolers. In an embodiment, the cooler has a total internal capacity (e.g., volume of chamber 12) of about 150 quarts or less, such as about 8 quarts to about 140 quarts, or about 20 quarts to about 120 quarts, or about 40 quarts to about 100 quarts.
The refrigerant bunkers 22 of the present disclosure can thus employ appropriate level of insulation to reduce, as desired, the transfer of thermal energy from the interior of the cooler 10 to the refrigerant 32. This is accomplished by using a combination of the space in the refrigerant bunker, such as the gaps 44, the inner refrigerant cover material properties and the layers of sublimated carbon dioxide that fills the space of the outer container and/or inner refrigerant cover to achieve this desired level of thermal shielding. This may help reduce the amount of expensive, heavy and/or bulky insulation or the use of expensive vacuum insulated panels used to achieve a similar level of thermal resistance. This may also allow a reduced size and/or cost of the refrigerant bunkers of the present disclosure.
The present disclosure is also directed to a method for controlling the temperature of a cooler. The method comprising inserting dry ice into any of the refrigerant bunkers of described herein. In an embodiment, the dry ice is enclosed in the refrigerant covering and the outer container. The refrigerant bunker is maintained in a cooler having a chamber, such as any of the coolers described herein. The refrigerant bunker is positioned so that the dry ice cools the chamber. In an embodiment, the cooler can be maintained at temperatures suitable for refrigeration, such as above 32° F. to about 40° F., or 33° F. to about 38° F. As described herein, a user can optionally maintain the temperature at below freezing temperatures, e.g., below 32° F., by inserting the dry ice into the refrigerant bunker without the refrigerant covering.
A refrigerant bunker was made from foam insulation with an R-5 insulation value and a plastic lid. Spacers were positioned in the bottom and sides of the foam bunker to provide an offset, Do, of about ⅜ inch. Holes of about ⅜ inch diameter were made in the bunker to act as convection ports for testing purposes. A 10×10×2 inch block of dry ice was used as a coolant. Several pages of crinkled paper were wrapped around the dry ice as an inner refrigerant cover during portions of the testing.
Testing included positioning dry ice in the foam bunker. The bunker containing the dry ice was placed in a rotationally molded, 50 quart cooler and the temperature inside the cooler was measured over a period of 24 hours. Separate tests were run in which 1) the convection ports in the bunker were opened and no paper inner refrigerant cover was wrapped around the dry ice; 2) the convection ports were closed and no paper inner refrigerant cover was wrapped around the dry ice; and 3) the convection ports were closed and a paper inner refrigerant cover was wrapped around the dry ice.
The results of the tests are shown in the graph of
Other testing was performed in which the size of the ribbing was reduced to produce a smaller offset (offset decreased from ⅜″ to ⅛″) and the paper inner refrigerant cover was tightly wrapped around the dry ice. This resulted in less effective insulation properties for the bunker that in turn resulted in below freezing temperatures in the cooler. It is hypothesized that the decrease in insulation performance was due to reduced carbon dioxide gas-layering potential of the bunker caused by the smaller offset and tightly wrapped inner paper cover.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein.
While the present teachings have been illustrated with respect to one or more implementations, alterations and/or modifications can be made to the illustrated examples without departing from the spirit and scope of the appended claims. In addition, while a particular feature of the present teachings may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular function. Furthermore, to the extent that the terms “including,” “includes,” “having,” “has,” “with,” or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.” Further, in the discussion and claims herein, the term “about” indicates that the value listed may be somewhat altered, as long as the alteration does not result in nonconformance of the process or structure to the illustrated embodiment. Finally, “exemplary” indicates the description is used as an example, rather than implying that it is an ideal.
It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompasses by the following claims.
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| Number | Date | Country | |
|---|---|---|---|
| 20170003063 A1 | Jan 2017 | US |
