CN110691951A - Passive refrigeration system for the cold chain industry - Google Patents

Abstract

The present invention provides a passive cooler for controlled refrigeration of products, said cooler comprising: an outer carton comprising an outer isolation layer; an inner box comprising an inner barrier and a heat shield located outwardly of the inner barrier, the inner box and the outer box defining a steam passage therebetween; and a thermal link comprising a thermal layer and a plurality of heat pipes or a plurality of thermosiphons, the thermal layer and a top section of the inner tank defining a coolant chamber, the coolant chamber comprising a coolant chamber inlet, the thermal layer and a bottom section of the inner tank defining a load chamber, the load chamber comprising a load chamber inlet, each heat pipe or thermosiphon having a condenser section disposed in the coolant chamber and an evaporator section disposed in the load chamber and extending through the thermal layer.

Description

Passive refrigeration system for the cold chain industry

Technical Field

The present invention relates to the field of passive refrigeration systems for refrigerating perishable products during transport and storage. More particularly, the present invention relates to a refrigeration system that employs carbon dioxide-free cooling in a load compartment and has a high degree of temperature regulation capability. The system can be used, for example, for pallet sized loads, trailer sized loads, and stationary refrigeration equipment, and is therefore scalable.

Background

The cold chain industry is responsible for transporting and storing refrigerated temperature sensitive products such as food and pharmaceuticals. Inadequate refrigeration or improper temperature may result in losses. Currently, companies that participate in the transportation of perishable foods must either own expensive electromechanical refrigerated trucks that have multiple refrigerated compartments that can be set to different temperatures, or must place all items at a single temperature and wish that frozen products not melt and deteriorate prior to delivery.

U.S. patent No.4,891,954 discloses a refrigeration system (10) that utilizes sublimed carbon dioxide (CO)₂) To maintain a good insulated railcar (12) composition of stored products. The insulated rail car (12) includes a divider (22), the divider (22) dividing the insulated rail car (12) into a lower storage area (26) and an upper compartment (24). The chamber (24) contains a distribution manifold (28) for forming carbon dioxide snow and distributing the formed carbon dioxide snow throughout the chamber (24). Sublimation ports (30) along each side wall (18) and end wall (20) allow the sublimated carbon dioxide to flow to an underlying storage area (26) for refrigerating stored product during transport. A plenum (42) and exhaust (44) are provided at each end of the insulated rail car (12) to exhaust the sublimated carbon dioxide to the external atmosphere. The insulated railcar (12) also includes a pressure relief vent (32) located generally below the distribution manifold (28) to vent flash gases generated during the carbon dioxide snow formation process. This technique does not allow temperature control over time and also does not have a uniform temperature throughout the chamber. In addition, CO is added into the load chamber₂。

Us patent No.5,460,013 discloses a thin-walled refrigerated transport container (8) comprising a horizontal partition element (20), the horizontal partition element (20) forming a compartment (22) for containing carbon dioxide snow by passing liquid CO₂Along at least one side of the compartment by means of a manifold (24) and spraying the carbon dioxide snow onto the opposite wall. The combined design of the charge manifold and the pressure relief vent allows operation without excessive structural destructive pressure build-up. This technique does not allow temperature control over time or in different regions of the vessel. In addition, gas is added to the chamberState CO₂。

Us patent No.7,310,967 discloses a cryogenic transport and storage container having an on-board cooling unit in the form of a compartment for containing a solid refrigerant. The unit can be configured in different sizes and used for refrigerated rather than frozen products. Although this system allows better temperature control within the chamber, it requires power and a fan, and is therefore not a passive system. In addition, gaseous CO is introduced into the chamber₂。

Us patent No.8,191,380 discloses a portable active cryogenic container for holding products at refrigerated and/or cryogenic temperatures. The container includes a control system to monitor and control the flow of cooling air from the compartment section to at least one magazine section in which the temperature sensitive product is contained. The control system is coupled to a fan that enhances heat transfer by forced convection when the system exceeds a thermal limit. The cryogenic vessel is powered by a battery pack or by a 12 volt power supply plugged into the vehicle. Although this system allows better temperature control within the chamber, it requires power and a fan, and is therefore not a passive system. Further, the gaseous CO is introduced₂Is added to the chamber. The coolant is liquid nitrogen and flows through a liquid evaporative heat exchanger. Unlike a heat pipe, it has an open end. The open end discharges coolant to the ambient environment within the chamber.

U.S. patent No.3,714,793 discloses a liquefied gas vaporizer located at the bottom of a freeze sensitive product storage chamber having insulation surrounding a liquid vaporization conduit and a thermally conductive metal floor means continuously associated with and in heat transfer relationship with the insulation. The coolant is liquid nitrogen, passing through a liquid evaporative heat exchanger. Unlike a heat pipe, it has an open end. The open end discharges coolant to the ambient environment within the chamber.

Us patent No.3,421,336 discloses a system that produces external work that is recovered to circulate the injected cold fluid by intermittently injecting the cold fluid into the product chamber and continuously expanding the vaporized cold liquid into the same chamber, resulting in a more uniform distribution of refrigerant in long-haul trailers and railcars.

U.S. patent No.7,891,575 discloses a heat storage and transfer system including a cooling system and also discloses a method of using ice or other freezing material with heat pipes to create a cooled airflow. Preferably, the ice is placed in a container with a condenser and an evaporator of the heat pipe inside and outside the container, respectively. A fan blows air through the duct across the evaporator section to circulate within the enclosed air space to be cooled. A separate refrigeration system, which may be used to independently cool the air spaces, also freezes water or another liquid to produce ice or other frozen material in the container. The cooling system is widely applicable, including use on motor vehicles, to provide hours of cooling when the vehicle engine is off. The heating system includes an adsorption heat exchanger for extracting heat from the exhaust gas of the engine and heating the enclosed air space. Also, it is not a passive system because it requires a fan.

U.S. patent application publication No. us 2004/0226309 discloses a portable temperature controlled container for storing and transporting temperature sensitive materials. The portable temperature controlled container includes a container having a bottom wall, four side walls and a top wall defining a cargo space. The container includes a temperature regulating unit connected thereto. The temperature adjustment unit includes a refrigeration unit. The temperature regulating unit is in communication with the cargo space of the receptacle. The container includes a temperature controller associated therewith. The temperature controller includes a temperature control unit and a temperature sensor located within the cargo space of the container. The container also includes a power source. The temperature adjusting unit may include a heating unit. Also, it is not a passive refrigeration system.

U.S. patent No.8,162,542 discloses a cargo container including a cargo box secured atop a hollow base, the base including a forklift channel extending therethrough, an elongated bracket disposed parallel to the forklift channel. Each tray includes a removable tray for receiving a battery. And a temperature control system is disposed on the sidewall adjacent the base. The cargo container has both electric heaters and vapor compression refrigeration. During transport, the onboard battery provides power. This is not a passive system.

Us patent application publication No. us2013/0008188 discloses a cryogenic heat exchanger comprising a container having a sidewall defining a chamber in the container for containing a refrigerant, and at least one heat exchange assembly having a first portion arranged in the chamber and extending through the sidewall to a second portion arranged in the atmosphere of a space outside the chamber and on an opposite side of the sidewall for providing heat transfer to the atmosphere. This system uses heat pipes, but also includes at least one fan, and is therefore not a passive system. The temperature can be adjusted by changing the pressure of the refrigerant (liquid nitrogen or liquid carbon dioxide) in the tank (possibly with the aid of a pump) or adjusting the fan speed. Again, none of these methods are passive. Other methods of regulating temperature do not allow for dynamic regulation of temperature, but instead require the use of a variable volume reservoir in the evaporator portion of each heat pipe. The heat pipe is made of stainless steel or copper.

Refrigerated containers that can hold a tray of product can be used for the transport and storage of perishable products. Preferably, the carbon dioxide or other coolant is not added directly or indirectly to the storage chamber (also sometimes referred to herein as the "load chamber"). Carbon dioxide replaces oxygen and high concentrations of carbon dioxide can suffocate people. The direct discharge of carbon dioxide vapor into the load space can compromise temperature control and, due to its very rapid temperature drop, can damage the structural elements of the load unit. Further, the expansion effect due to the phase change requires a large amount of refrigerant vapor to be discharged out of the atmosphere, which increases the operation cost due to the increase in the required amount of refrigerant. It is further preferred if it has a passive heat transfer system, without forced convection. It would be further advantageous if the system allowed for the transport and storage of cargo at various selected and controlled temperatures.

Disclosure of Invention

Disclosed herein are refrigeration systems and containers for transporting and storing perishable products. In one embodiment, the refrigerated container is sized to hold a tray of product. Carbon dioxide is not added or released directly or indirectly to the storage chamber. The system has a passive heat transfer system, and does not require forced convection. The system may be configured to allow for the transport and storage of cargo at various selected and controlled temperatures.

In one embodiment, a passive refrigeration container for controlled refrigeration of products is provided, the refrigeration container comprising: an outer carton comprising an outer isolation layer; an inner box comprising an inner barrier layer, and a heat shield on an outer side of the inner barrier layer, the inner box and the outer box defining a steam passage therebetween; and a thermal link comprising a thermal layer and a plurality of heat pipes or thermosiphons, the thermal layer and a top section of the inner tank defining a coolant chamber, the coolant chamber comprising a coolant chamber inlet, the thermal layer and a bottom section of the inner tank defining a load chamber, the load chamber comprising a load chamber inlet, each heat pipe or thermosiphon having a condenser section disposed in the coolant chamber and an evaporator section disposed in the load chamber and extending through the thermal layer.

The passive refrigeration container may further include a mesh header (meshheader) positioned below the heat pipes or thermosiphons. The passive refrigeration container may further include an outer shell positioned over the outer barrier and an inner liner positioned over the inner barrier. In the passive refrigerator, the heat shield may be an aluminum shield. In the passive refrigerator, the coolant chamber inlet may include an outer lid and an inner lid. In a passive refrigerator, the inner lid may be located on a step within the inner box. The passive cooler may further include a gasket positioned between the inner lid and the step. In the passive refrigerator, the heat pipe may be a solderless heat pipe.

In a passive refrigerator, the heat pipe may include a working fluid that is one of pentane, propylene, acetone, and methanol. In the passive refrigerator, the thermal link may be a reconfigurable thermal link. The passive cooler may further include a check valve located within the outer lid.

Also disclosed herein is a passive refrigeration system for the cold chain industry, the system comprising a tank and a solid coolant, the tank comprising: an outer carton comprising an outer isolation layer; an inner box comprising an inner barrier layer, and a heat shield positioned outside the inner barrier layer, the inner and outer boxes defining a steam passage therebetween; and a thermal link comprising a thermal layer and a plurality of heat pipes or a plurality of thermosiphons, the thermal layer and a top of the inner tank defining a coolant chamber, the coolant chamber comprising a coolant chamber inlet, the thermal layer and a bottom of the inner tank defining a load chamber, the load chamber comprising a load chamber inlet, each heat pipe or thermosiphon having a condenser portion disposed in the coolant chamber and an evaporator portion disposed in the load chamber and extending through the thermal layer, and the solid coolant being solid carbon dioxide.

In the system, the hot-link may be a reconfigurable hot-link. In the system, the thermal link includes a plurality of heat pipes. In the system, the heat pipe may be a solderless heat pipe. In the system, the heat pipe may include a working fluid, the working fluid being one of pentane, propylene, acetone, and methanol. In the system, the heat shield may be an aluminum shield.

Also disclosed herein is a passive refrigeration case for controlled refrigeration of products, the refrigeration case comprising: a bottom; four sides attached to the bottom; an inner cover and an outer cover, the sides including an outer barrier layer and an inner barrier layer, the layers and the inner and outer covers defining a vapor passage therebetween; an aluminum cover adjacent to the vapor passage and abutting an outer side of the inner barrier and a top of the inner cover; thermal layers disposed below the inner cover and between the inner insulation layers to define a coolant chamber for holding a coolant; a load chamber defined by the inner barrier layer and the thermal layer; and a plurality of heat pipes or thermosiphons, each heat pipe or thermosiphon having a condenser portion disposed in the coolant chamber and an evaporator portion disposed in the load chamber and extending through the thermal layer.

Also disclosed herein is a method of passively cooling a load using the above-described refrigeration case, the method comprising loading the load into the load chamber and filling the coolant chamber with a solid coolant.

The method may further comprise: the thermal link is configured to regulate the temperature of the load. In this method, the solid coolant may be solid carbon dioxide (or "dry ice").

Drawings

Embodiments of the invention are described below with reference to the accompanying drawings, in which:

FIG. 1 is a longitudinal cross-sectional view of a heat pipe according to one aspect of the present invention.

FIG. 2 is a longitudinal cross-sectional view of an end cap and a tube end of the heat pipe of FIG. 1.

Fig. 3 is a perspective cross-sectional view of a passive cooler in accordance with an aspect of the present invention.

Fig. 4 is a longitudinal cross-sectional view of the passive refrigeration container of fig. 3.

FIG. 5 is a longitudinal cross-sectional view of an alternative embodiment of a passive refrigeration case.

FIG. 6 is a longitudinal cross-sectional view of an alternative embodiment of a passive refrigeration case.

FIG. 7A illustrates the operation of a reconfigurable thermal chain in accordance with an aspect of the present invention.

FIG. 7B illustrates the operation of a reconfigurable thermal chain in accordance with an aspect of the present invention.

Detailed Description

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, which form a part hereof, and which show, by way of illustration, exemplary embodiments by which the invention may be practiced. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The following detailed description is, therefore, not to be taken in a limiting sense.

The following rules of interpretation apply to this specification (written description, claims and drawings) unless explicitly stated otherwise: (a) all terms used herein are to be interpreted as having the meaning or number (singular or plural) as the case requires; (b) as used in the specification and in the claims, the singular terms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise; (c) the antecedent "about" as applied to describing ranges or values represents approximations within the deviation of the ranges or values known or expected from the measurement methods in the art; (d) unless otherwise specified, the words "herein," "before" and "after" and words of similar import, whether or not the specification is in its entirety, but rather in any particular paragraph, claim or other portion; (e) descriptive headings are for convenience only and should not control or influence the meaning or construction of any portion of the specification; and (f) or and any is not exclusive, and "including" and "comprising" are not limiting. Furthermore, unless otherwise indicated, the words "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to").

To the extent necessary to provide descriptive support, the subject matter and/or text of the claims is incorporated by reference herein in its entirety.

Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. Where a particular range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within that particular range. All smaller subranges are also included. The upper and lower limits of these smaller ranges may also be included, subject to any specifically excluded limit in the stated range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the relevant art. Although any methods and materials similar or equivalent to those described herein can also be used, acceptable methods and materials are now described.

Definition of

Heat pipe-in the context of the present invention, a heat pipe is constituted by a sealed tube that non-releasably holds a working fluid. A core is present within the bore of the tube. (essentially, a heat pipe is a heat transfer device that combines the principles of both thermal conductivity and phase change to efficiently transfer heat between two solid interfaces at the thermal interface of a heat pipe, the liquid in contact with the thermally conductive solid surface becomes a vapor by absorbing heat from that surface

Thermosiphon-in the context of the present invention, a thermosiphon is similar in assembly and construction to a heat pipe, except that it contains a large amount of working fluid and does not contain a capillary structure. It non-releasably holds a working fluid.

Solderless heat pipe-in the context of the present invention, a solderless heat pipe is a heat pipe having barbed end caps and having barbs on the inside of the pipe of the heat pipe proximate the ends. The end cap and tube are press fit together.

Braze heat pipes free of fusion welding-in the context of the present invention, copper heat pipes are brazed to seal the end caps to the pipes.

Braze thermosiphon free from welding-in the context of the present invention, thermosiphon is brazed to close the end caps to the tubes.

Working fluid-in the context of the present invention, a working fluid is a fluid that exists in a heat pipe in a saturated liquid phase and a gaseous phase that are the same. The liquid evaporates into a vapor in the evaporator region of the heat pipe and the vapor condenses into a liquid in the condenser region of the heat pipe. For present purposes, any of pentane, propylene, acetone, and methanol may be used as the working fluid; other refrigerants that are also suitable for use as the working fluid will be apparent to those skilled in the art.

Wick-in the context of the present invention, a wick is a material that lines the pores of a heat pipe and exerts a capillary action on the liquid phase of the working fluid.

Thermal link-in the context of the present invention, a thermal link is an interface for managing heat flow (heat energy flow). The design and materials used determine the thermal conductivity of the thermal chain. The thermal link includes a heat pipe and a thermally or conductive layer (thermal layer).

Reconfigurable thermal link-in the context of the present invention, a reconfigurable thermal link refers to a thermal link that can be changed to change or optimize thermal conductivity for a given application (temperature requirement).

Solid coolant-in the context of the present invention, filling the coolant chamber with a solid coolant means adding a solid coolant, or spraying a liquid coolant, which then undergoes a phase change from a liquid to a solid coolant.

Detailed description of the invention

A heat pipe, generally designated 8, is shown in fig. 1. The tube 10 has a first end 12 with a first end cap 14 and a second end 16 with a second end cap 18. The second end cap 18 has a fill tube 20 extending therefrom. The bore 22 extends from the first end cap 14 to the second end cap 18. The fill tube 20 has a crimp end 24 distal to the second end cap 18, and a fill tube aperture 26. The second end cap 18 has a central opening 28. The wall 30 of the central opening 28 has a step 32, and the proximal end 32 of the fill tube 20 is located on the step 32 (as can be seen more clearly in FIG. 2). A weld bead 34 attaches the fill tube 20 to the second end cap 18. In fig. 1, the crimp end 24 is crimped after the working fluid is added to the heat pipe. A bead 40 seals the crimp end 24. The heat pipe 8 has a wick 42 located within the bore 22.

As shown in fig. 2, taking the second end cap as an example, the first and second ends 12, 16 and the end caps 14, 18 have barbs 50, the end caps 14, 18 are preferably male mating members 52, and the ends 12, 16 are female mating members 54 and also have barbs 56. The O-ring 60 is seated in the mating pair. This provides a solderless heat pipe.

As mentioned above, the heat pipe or thermosiphon (in this case) may be non-welded and braze-closed.

A passive refrigeration container, generally designated 80, is shown in fig. 3. The refrigeration case 80 provides passive cooling through the use of heat pipes 8 (only a single row of heat pipes is shown in fig. 3 for ease of illustration, but it should be understood that additional rows of heat pipes or arrays of heat pipes are preferably used) and does not release coolant into the load chamber 82. Outer box 81 includes a bottom 84 attached to four walls 86, and an outer cover 88. The box is preferably configured to provide sufficient strength and support to the load and is configured to be moved using a forklift. An aluminum or steel or plastic housing 90 is optionally supported by the bottom 84 and a metal frame 92 in the four walls 86. The outer barrier layer 94 lines the interior 96 of the housing 90 and the frame 92. The outer insulation 94 is preferably closed cell, extruded or expanded polystyrene or the like, and may comprise vacuum insulated panel insulation. The base 84 includes slots 97 for receiving the forks of a forklift.

The inner box 98 includes four interior walls 100, an insole 102, and an inner lid 104. The inner barrier layer 110 lines the inner lining 112 of the wall 100 and the outer shell 114 of the inner cover 104. The inner insulation 110 is preferably closed cell, extruded or expanded polystyrene or the like (including vacuum insulated panel insulation). The inner liner 112 and outer shell 114 are aluminum or plastic. The liner 112 includes a spacer 116 that extends a short distance into the load chamber 150 to ensure that an air gap 116 is maintained between the liner 112 and the load. Preferably, the outer cover 88 is similarly constructed of an aluminum or plastic housing, and the outer cover 88 is provided with an insulator (including a vacuum insulated panel insulator), preferably closed cell, extruded or expanded polystyrene or the like.

The heat shield 122 abuts the upper surface 118 of the insulation 110 of the inner cover 104 and the outer surface 120 of the inner insulation 100. in a preferred embodiment, the heat shield 122 is an aluminum shield 122. The aluminum enclosure 122, together with both the outer insulation layer 94 and the outer cover 88 on the wall 86, define a space referred to as a vapor passage 124. The heat shield 122 helps manage heat leakage and maintain the temperature of the cold space. The time to cool the load from its initial higher temperature to steady state is also reduced while consuming less solid coolant/dry ice.

As shown in fig. 4, the inner cover 104 rests on a step 126 in the liner 112. A gasket 128 fits between the inner cover 104 and the step 126 in the liner 112. The vapor passage 124 is sealed from the ambient environment and from the coolant chamber 140. Optionally, however, a check valve 125 mounted in the outer cover 88 may be provided, so that a small overpressure may be maintained inside the steam channel 124. This prevents the ingress of external moist air when the coolant/dry ice charge is exhausted. A coolant 142, preferably solid carbon dioxide, is loaded and maintained in the coolant chamber 140. Once the coolant chamber 140 is closed, the coolant chamber 140 is not in communication with the ambient environment. The coolant chamber 140 has a plurality of heat pipes 8 extending into the load chamber 150 through the base 143 of the coolant chamber 140. The base 143 and the heat pipe 8 form a reconfigurable thermal link 144. The reconfigurable thermal link 144 (as described in further detail below) may also allow for customization and optimization of thermal energy transfer between the coolant chamber 140 and the coolant 142 in the load chamber 150. The coolant chamber 140 is located in a top section 146 of the inner box 98. The load chamber 150 is located in the bottom section 148 of the inner box 98.

The configuration of the heat pipe 8 helps to provide this customization. The portion of the heat pipe 8 that extends into the coolant chamber 140 includes a condenser section 152. Below the base 143 and the liner 112 is a load chamber 150. The portion of the heat pipe 8 that extends into the load chamber 150 includes an evaporator section 156. The reticulated manifold 160 protects the heat pipes 8 from damage in the event of a load shift in the load chamber 150. The mesh may be made of aluminum, steel or plastic and additionally serves to secure sufficient space for air circulation. Near the top 162 of the load chamber 150, a reticulated manifold 160 extends through the load chamber 150. The load chamber 150 is an enclosed space.

The inner door 170 and the outer door 172 may be constructed in the same manner and in the same material as the covers 88, 104. These doors do not obstruct the steam channel 124. At least one temperature sensor 176 may be located in the load compartment 150 and in electrical communication with a display 178 located remote from the refrigeration case 80 or on an exterior surface 178 of the refrigeration case 80.

In one embodiment, the cooler 80 is sized to receive a tray of loaded products. The load is placed in a refrigerated case, which may then be moved into and out of a storage facility or a transport truck. Different refrigeration cases operating at different temperatures may be placed side by side and may be delivered together or independently of other refrigeration cases in the truck. This increases the flexibility of the truck load to be delivered, allows for optimizing the storage conditions of the product, and reduces the energy consumption and associated pollution associated with running the generator to cool the truck load.

In an alternative embodiment, the side passages allow the coolant chamber 140 to slide out and fill/refill with solid coolant 142, or simply access and fill from the side.

In another embodiment, as shown in FIG. 5, the passive refrigeration container 80 of FIGS. 3 and 4 further comprises: a liquid injection port 180 and a distribution manifold 182 in the coolant chamber 140 for adding liquid carbon dioxide. The liquid carbon dioxide flashes into solid carbon dioxide snow (solid coolant 142), thus filling the coolant chamber with the solid coolant 142.

In another embodiment, as shown in FIG. 6, the cooler is sized to fit as a single unit in the ISO container 200, so it is slightly smaller than the interior dimensions of the ISO container 200. The load chamber 150 has a load chamber passage 202, and the load chamber passage 202 may include an inner door 204 and an outer door 206. As shown in fig. 6, the coolant chamber inlet 208 may be through a lid or a side inlet 208. The construction and relationship between the doors is the same as the lid-there is a heat shield 206 on the outside 208 of the inner door 202, and the steam channel 210 has an unobstructed path between the doors 202, 204.

In another embodiment, the cooler is a container for transport on a trailer or platform. It may also be constructed to be doorless and as described and shown in fig. 6.

In another embodiment, the cooler 80 is a trailer. It may also be constructed to be doorless and as described and shown in fig. 6.

In yet another embodiment, the heat pipes in the refrigeration case or system are replaced with thermosiphons.

One embodiment of a reconfigurable thermal link (referred to above as 144), generally labeled herein as 249, is shown in fig. 7A and 7B. The function of the reconfigurable thermal link 249 is to adjust the thermal resistance along a particular heat conduction path connecting a relatively hotter region to a relatively cooler region. By physically adjusting the internal element (or elements) of the reconfigurable thermal link, the thermal resistance of the thermal conduction path described above can be changed to affect changes in the rate at which thermal energy is transferred from relatively hotter areas to relatively cooler areas.

When the reconfigurable heat-train 249 is placed in the thermal path between the load chamber 150 (relatively hotter regions) and the coolant chamber 140 (relatively cooler regions), the heat transfer rate can be adjusted to a point where a degree of load chamber temperature control can be achieved. In one embodiment, the reconfigurable thermal link 249 may be placed at the condenser end (relatively hotter area) of a heat pipe or thermosiphon device and the cooler coolant chamber 140 to affect control of the heat transfer rate that is achieved between the relatively hotter area and the relatively cooler area.

Fig. 7A shows a relatively hotter region 250, a relatively cooler region 251, and a heat transfer path 252. The reconfigurable thermal link is made up of a thermally conductive housing 253 separated into two sections by a thermally insulating housing barrier 254. The thermally conductive housing element 253 and the thermally insulating housing barrier 254 together comprise the entire housing 258. Inside the housing 258, there is a cavity 255 partially occupied by a moving element 259. A portion of the moving member 259 is comprised of a thermally conductive end 256 and a thermally insulative end 257. The moving member 259 is capable of moving across the entire width of the internal cavity 255.

FIG. 7A shows the moving element 259 in an inner position whereby the thermal resistance path from relatively hotter location 250 to relatively cooler location 251 is minimized. The heat passes through the thermally conductive housing 253, the thermally conductive portion of the inner moving element 256, the thermally conductive housing 253, and eventually out of the relatively cooler region 251. At various stages of the thermal path, heat is allowed to transfer through the thermally conductive material, resulting in a lower overall thermal resistance of the path.

Fig. 7B shows a perspective view of a reconfigurable heat chain 249 in which the inner moving elements 259 move in a manner that creates a large thermal resistance, thereby impeding heat transfer from relatively hotter locations 250 to relatively cooler locations 251. In this configuration, the path for heat transfer is substantially blocked by the double insulation material present in inner moving element 257 and shell insulation segment 254. The thermal resistance of both potential heat transfer paths is very high due to the insulating material now occupying the potential heat transfer path 252.

The inner movable thermal element 259 may be energized to change position by a variety of means. Some of these approaches are passive in that they do not use electrical energy to operate, while other actuation mechanisms may use non-passive methods.

While the exemplary embodiments have been described in connection with what are presently considered to be the most practical and/or suitable examples of embodiments, it is to be understood that the description is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the exemplary embodiments. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific exemplary embodiments described specifically herein. Such equivalents are intended to be encompassed within the scope of the claims appended hereto or as subsequently filed.

Claims (22)

1. A passive refrigeration container for controlled refrigeration of products, said refrigeration container comprising: an outer carton comprising an outer isolation layer; an inner box comprising an inner barrier layer, and a heat shield located outboard of the inner barrier layer, the inner box and the outer box defining a steam passage therebetween; and a thermal link comprising a thermal layer and a plurality of heat pipes or a plurality of thermosiphons, the thermal layer and a top section of the inner tank defining a coolant chamber, the coolant chamber comprising a coolant chamber inlet, the thermal layer and a bottom section of the inner tank defining a load chamber, the load chamber comprising a load chamber inlet, each heat pipe or thermosiphon having a condenser section disposed in the coolant chamber and an evaporator section disposed in the load chamber and extending through the thermal layer.

2. The passive refrigeration container of claim 1, further comprising a mesh header below said heat pipes or thermosiphons.

3. The passive cooler of claim 1 or 2, further comprising an outer shell positioned over the outer insulator and an inner liner positioned over the inner insulator.

4. A passive refrigeration system according to any of claims 1 to 3, comprising a plurality of heat pipes.

5. The passive cooler of any one of claims 1-4, wherein said heat shield is an aluminum shield.

6. The passive cooler of any one of claims 1 to 5, wherein said coolant chamber inlet comprises an outer lid and an inner lid.

7. The passive cooler of claim 6, wherein said inner cover is positioned on a step of said inner box.

8. The passive cooler of any one of claims 1-7, further comprising a gasket positioned between said inner cover and said step.

9. The passive cooler of claim 1, wherein said heat pipe is a solderless heat pipe.

10. The passive refrigeration container of claim 9, wherein said heat pipe comprises a working fluid selected from the group consisting of: acetone, methanol, pentane and propylene.

11. The passive cooler of claim 1, wherein said thermal link is a reconfigurable thermal link.

12. The passive cooler of any one of claims 6-11, further comprising a check valve in said outer lid.

13. A passive refrigeration system for the cold chain industry, the system comprising a tank and a solid coolant, the tank comprising: an outer carton comprising an outer isolation layer; an inner box comprising an inner barrier layer, and a heat shield located outboard of the inner barrier layer, the inner box and the outer box defining a steam passage therebetween; and a thermal link comprising a thermal layer and a plurality of heat pipes or a plurality of thermosiphons, the thermal layer and a top of the inner tank defining a coolant chamber, the coolant chamber comprising a coolant chamber inlet, the thermal layer and a bottom of the inner tank defining a load chamber, the load chamber comprising a load chamber inlet, each heat pipe or thermosiphon having a condenser section disposed in the coolant chamber and an evaporator section disposed in the load chamber and extending through the thermal layer, and the solid coolant being solid carbon dioxide.

14. The system of claim 13, wherein the thermal link is a reconfigurable thermal link.

15. The system of claim 13 or 14, wherein the system comprises the plurality of heat pipes.

16. The system of any one of claims 13 to 15, wherein the heat pipe is a solderless heat pipe.

17. The system of claim 16, wherein the heat pipe comprises a working fluid selected from the group consisting of: acetone, methanol, pentane and propylene.

18. The system of any of claims 13-17, wherein the heat shield is an aluminum shield.

19. A passive refrigeration container for controlled refrigeration of products, said refrigeration container comprising: a bottom; four sides attached to the bottom; an inner cover and an outer cover, the sides including an outer barrier layer and an inner barrier layer, the layers and the inner and outer covers defining a vapor passage therebetween; an aluminum cover adjacent the vapor passage and abutting an outer side of the inner barrier and a top of the inner cover; a thermal layer disposed below the inner cover and between the inner barrier layers to define a coolant chamber for holding a coolant; a load chamber defined by the inner barrier layer and the thermal layer; and a plurality of heat pipes, each heat pipe having a condenser section disposed in the coolant chamber and an evaporator section disposed in the load chamber and extending through the thermal layer.

20. A method of passively refrigerating a load using the cooler of claim 1, said method comprising loading said load into a load chamber and filling a coolant chamber with a solid coolant.

21. The method of claim 20, further comprising configuring a thermal link to regulate a temperature of the load.

22. The method of claim 20 or 21, wherein the solid coolant is solid carbon dioxide.

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