SYSTEM AND METHOD FOR RAPIDLY FREEZING COLD PACKS WITH A FLAT SIDE AND A CONVEX SIDE

Abstract

A system and method for freezing cold packs. The system includes at least one plate containing a low-temperature refrigerant and a mechanical refrigeration system. The system is configured to receive a cold pack on the at least one plate and freeze the cold pack by contacting one of its major faces.

Claims

1. A system for freezing a cold pack comprising: a plate containing a low-temperature refrigerant; and a mechanical refrigeration system, wherein the system is configured to receive a cold pack on top of the plate and freeze the cold pack with a uni-directional freeze gradient.

2. The system of claim 1, wherein the freezing of the cold pack produces a cold pack with one flat major face and one major face with a convex geometry.

3. The system according to claim 1, wherein the low temperature refrigerant is selected from the group consisting of ammonia, carbon dioxide, freon, chlorofluorocarbons, and combinations thereof.

4. The system according to claim 1, wherein the plate is made from a material selected from the group consisting of aluminum or aluminum alloys, stainless steel or steel alloys, copper or copper alloys, and combinations thereof.

5. The system according to claim 1, wherein a thermally conductive tray is used to convey the cold pack onto and off the plate.

6. The system according to claim 5, wherein the thermally conductive tray is made from a material selected from the group consisting of aluminum, copper, stainless steel, and combinations thereof.

7. The system according to claim 1, wherein an evaporator temperature setting for the refrigeration system is less than 0 C.

8. The system according to claim 1, wherein the cold pack is a water-based cold pack, comprising >50% water.

9. The system according to claim 1, wherein the cold pack is encapsulated in a flexible plastic material or flexible paper material.

10. A method for freezing a cold pack, the method comprising: placing a cold pack upon a plate, wherein the plate contains a low-temperature refrigerant; and freezing the cold pack on one of its major faces with a freeze gradient emanating upward.

11. The method of claim 10, wherein the freezing of the cold pack produces a flat surface on a major face of the cold pack and a convex surface on the other major face of the cold pack.

12. The method of claim 10, further comprising placing the cold pack within a tray prior to placing the cold pack on the plate.

13. The method of claim 10, wherein the plate is oriented horizontally, and the cold pack is resting on the top surface of the plate under gravity loads.

14. A method for keeping an item at a desired temperature the method comprising: placing at least one cold pack adjacent to the item, wherein the cold pack includes one flat surface and one convex surface opposite the one flat surface.

15. The method of claim 14, wherein the flat side of the cold pack is adjacent to the item.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0020] The foregoing and other features of this disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the disclosure and are, therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings, in which:

[0021] FIG. 1 illustrates an example system for freezing flat cold packs in accordance with the present disclosure;

[0022] FIG. 2 shows side cross section views of a frozen cold pack in accordance with the present disclosure;

[0023] FIG. 3 includes a top perspective view, side view and top view of a resulting cold pack in accordance with the present disclosure; and

[0024] FIG. 4 shows an illustration of a shipping parcel package with insulation liner and two cold packs in contact with the payload.

DETAILED DESCRIPTION

[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the term and/or includes any and all combinations of one or more of the associated listed items. As used herein, the singular forms a, an, and the are intended to include the plural forms as well as the singular forms, unless the context clearly indicates otherwise. It will be further understood that the terms comprises and/or comprising, when used in this specification, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.

[0026] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one having ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0027] In describing the disclosure, it will be understood that a number of techniques and steps are disclosed. Each of these has individual benefit and each can also be used in conjunction with one or more, or in some cases all, of the other disclosed techniques. Accordingly, for the sake of clarity, this description will refrain from repeating every possible combination of the individual steps in an unnecessary fashion.

[0028] Nevertheless, the specification and claims should be read with the understanding that such combinations are entirely within the scope of the disclosure and the claims.

[0029] Novel methods for rapidly freezing cold packs are discussed herein. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be evident, however, to one skilled in the art that the present disclosure may be practiced without these specific details.

[0030] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.

[0031] FIG. 1 illustrates an example system for freezing single side flat cold packs, arranged in accordance with at least some embodiments presented herein. System 100 may include tray 20, freezing plates 30, a refrigeration system 40 and a refrigerant 50.

[0032] A cold pack 10 may be placed on tray 20 and tray 20 with cold pack 10 may be placed on a plate 30. Tray 20 may be thermally conductive and may convey cold packs 10 onto plates 30 for freezing and off of plates 30 once frozen. Tray 20 may be made of any thermally conductive material such as aluminum, aluminum alloys, steel, stainless steel, copper, copper alloys, and combinations thereof, and may have a thickness of about 1-5 millimeters. A freeze gradient may emanate from a plate 30 below tray 20 and the freeze gradient may translate up through tray 20 to cold pack 10 within tray 20.

[0033] Cold pack 10 may be in direct or indirect (via a thermally conductive layer) contact with plates 30. Plates 30 may be constructed from aluminum, aluminum alloys, steel, stainless steel, steel alloys, copper, copper alloys, or other types of thermally conductive materials, and combinations thereof. Plates 30 may have one or more openings to allow for refrigerant 50 to enter plates 30 and one or more openings to allow refrigerant 50 to exit plates 30.

[0034] Plates 30 may be hollow and may contain low temperature refrigerant 50 which may act to remove heat from cold pack 10, and thus freeze cold pack 10. Refrigerant 50 may be low temperature refrigerant and may be ammonia, carbon dioxide, various types of freon or other types of chlorofluorocarbons, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), or hydrocarbons (HCs), and combinations thereof.

[0035] Refrigeration system 40 may compress refrigerant 50 when refrigerant 50 is a gas, and then cool gas refrigerant 50 and allow it to condense into a liquid refrigerant 50, then allow liquid refrigerant 50 to expand as it enters plates 30, thereby converting back to a gas refrigerant 50 and absorbing heat in the process. Refrigerant 50 may undergo a vaporization phase change within plates 30, creating an endothermic process. System 40 may include compressors, including screw compressors, condensing units, and various valves to control flow and pressures of refrigerant 50. System 40 may further include a sub system to keep lubrication oil of a compressor at optimal temperatures.

[0036] System 40 may have an evaporator temperature setting below 0 C., with certain embodiments having an evaporator temperature setting range of 60 C. to 20 C.

[0037] FIG. 2 is side cross section views of a frozen cold pack, arranged in accordance with at least some embodiments presented herein. Those components in FIG. 2 that are labeled identically to components of FIG. 1 will not be described again for the purposes of brevity. As shown in FIG. 2, cold pack 10 may be frozen with a unidirectional freeze gradient depicted as arrows 210 moving up from the plate 30 so that it is frozen from bottom to top. Freeze gradients 210 may move up through each cold pack 10 toward the top of the cold pack 10. When cold pack 10 is fully frozen, the top of cold pack 10 will be hard to the touch, thus indicating the cold pack 10 is ready for use. The cold pack is frozen very rapidly given the high efficiency of heat transfer in a conduction-based process.

[0038] FIG. 3 includes a top perspective view, side view and top view of a cold pack, arranged in accordance with at least some embodiments presented herein. Those components in FIG. 3 that are labeled identically to components of FIGS. 1-2 will not be described again for the purposes of brevity. As shown in FIG. 3, cold pack 10 may be comprised of a water-based coolant such as a viscous gel consisting of >50% water that may be encapsulated with a flexible material 310 such as a plastic or paper material. Cold pack 10 may have an essentially rectangular shape with a flat surface 320 on one major face and a convex geometry 330 on the other. The convex geometry 330 may be formed by the natural state of a viscous gel contained in a flexible material and maintains this geometry as it freezes. In other embodiments, the cold pack may be comprised of a semi-solid gel coolant encapsulated with a flexible material such as a plastic or paper. In other embodiments, the semi-solid gel may not be encapsulated. The cold pack may have a freeze/thaw point between 25 C. and 8 C.

[0039] FIG. 4 shows an illustration of a shipping parcel package with insulation liner and two cold packs in contact with the payload. The overall shape of the cold packs are dimensionally appealing for packaging applications. The flat face 220 allows for excellent surface contact with the payload 400 and optimal cooling function. The convex face 230 allows for minimal contact with the parcel shipper's insulation or box walls 410, which is where heat from the environment is emanating from. This minimal contact with the insulation or box walls 410 may slow the heat transfer from the environment into the cold pack, allowing the cooling effect to last longer.

[0040] Another embodiment of the present disclosure includes a thin layer in lieu of thermally conductive tray 20, which may convey cold packs 10 onto and off of plates 30 but may not be thermally conductive when the thinness of the layer does not prevent thermal conduction.

[0041] In another embodiment, tray 20 is not required and cold packs 10 are directly placed onto plates 30.

[0042] Cold pack 10 may be frozen rapidly due to a high efficiency of heat transfer in a conduction-based process. A thickness of cold pack 10, in the z-dimension, may be a major determinant of an amount of time required to fully freeze cold pack 10. As a representative example, in embodiments, water-based cold packs 10 were placed on plate 30. Plate 30 was in contact with Freon R-507A, which was used as refrigerant 50 and an Evaporator Temperature Setting of 40 C. and a Condensing Temperature Setting of +40 C.

TABLE-US-00001 TABLE 1 Example Freeze Times for Different Thicknesses of Cold Packs Cold Pack Thickness Approximate Freeze Time (inches) (minutes) 0.75 49 1.00 63 1.25 79 1.50 99 1.75 120 2.00 145

[0043] A system in accordance with the present disclosure may provide high efficiency of heat transfer and also allow for an energy efficient process with the majority of the refrigeration duty focused on the cold pack target.

[0044] A system in accordance with the present disclosure may provide frozen cold packs which are flat on one major face and convex on the other major face, producing a block like shape that is dimensionally appealing for packaging applications.

[0045] A system and method in accordance with the present disclosure may result in a cold pack that may be free of bulges and tumoring. Bulging and tumoring occur when a cold pack is frozen rapidly in traditional methods of convective freezing. The outside of the cold pack in a traditional method is frozen first and the inner core is still liquid. When the core of the cold pack frozen in the traditional method finally freezes, the liquid must expand (water will expand 9% when it freezes) and this expansion results in a bulging as the expanded ice protrudes through the outer frozen layer. The cold pack resulting from the presently disclosed method is frozen with a uni-directional freeze gradient which controls and directs the expansion of the ice upward. Because the expansion of the ice is consistent across the entire top face of the cold pack, the cold pack is frozen uniformly without tumoring or bulging.

[0046] It should be understood that the foregoing description is only illustrative of the present disclosure. Various alternatives and modifications can be devised by those skilled in the art without departing from the disclosure. Accordingly, the present disclosure is intended to embrace all such alternatives, modifications and variances. The embodiments described with reference to the attached drawing figures are presented only to demonstrate certain examples of the disclosure. Other elements, steps, methods, and techniques that are insubstantially different from those described above and/or in the appended claims are also intended to be within the scope of the disclosure.