Thermal conditioning of phase change material panels (PCM panels) used in cold chain shipment of thermally labile payloads from a thermally spent condition to a thermally ready-to-use condition (i.e., frozen and thermally tempered to a temperature within the acceptable temperature range for the particular payload when the container is expected to experience external temperatures during shipment above the acceptable temperature range, and thawed and thermally tempered to a temperature within the acceptable temperature range for the particular payload when the container is expected to experience external temperatures during shipment below the acceptable temperature range) is a time consuming process that typically requires a day or more. This places a significant burden upon cold chain shippers who need to provide several days advance notice when they require a cold chain shipping container.
Hence, a significant need exists for a system and process that permits expedited thermal conditioning of thermally-spent phase change material panels into ready-to-use thermally tempered panels.
A first aspect of the invention is a cryogenic freezer for thermal conditioning of cold chain phase change material panels. A second aspect of the invention is a two-stage inline system for thermal conditioning of cold chain phase change material panels. A third aspect of the invention is a redundant two-stage inline system for thermal conditioning of cold chain phase change material panels. A fourth aspect of the invention is a method of expedited ready-for-use thermal conditioning of thermally-spent cold chain phase change material panels.
A particular embodiment of a cryogenic freezer in accordance with the first aspect of the invention includes an enclosure defining a thermal conditioning chamber, a driven conveyor system, two sets of spray nozzles for injecting a controlled quantity of a cryogenic fluid into the thermal conditioning chamber, and a controller for independently controlling the amount of cryogenic fluid sprayed through each of the first and second sets of spray nozzles.
The driven conveyor system is operable for continuously transporting phase change material panels through the thermal conditioning chamber and includes (1) an upstream platform length external to the thermal conditioning chamber for carrying thermally spent phase change material panels into the thermal conditioning chamber, (2) an intermediate platform length in the thermal conditioning chamber for providing a dwell time operable for transitioning thermally spent phase change material panels carried by the upstream length into the thermal conditioning chamber to deep frozen phase change material panels, and (3) a downstream platform length external to the thermal conditioning chamber for transporting deep frozen phase change material panels out from the thermal conditioning chamber.
The first set of the spray nozzles is one or more nozzles spatially configured and arranged relative to the intermediate platform length for emitting a flow of cryogenic fluid for direct contact with select phase change material panels carried on the intermediate platform length to expedite thermal conditioning of the select phase change material panels. The second set of spray nozzles is one or more nozzles spatially configured and arranged relative to the intermediate platform length for emitting a flow of cryogenic fluid into the thermal conditioning chamber for distribution throughout the thermal conditioning chamber for controlling the environmental temperature within the thermal conditioning chamber so as to holistically thermally condition a supply of phase change material panels carried on the intermediate platform length.
The controller is operable for independently controlling spray of cryogenic fluid through each of the first and second nozzles.
A particular embodiment of a two-stage inline system for thermal conditioning of cold chain phase change material panels in accordance with the second aspect of the invention includes first and second enclosures each defining a thermal conditioning chamber, first and second temperature control systems for controlling the temperature within the first and second thermal conditioning chambers respectively, and a driven conveyor system.
The first and second temperature control system each include (i) spray nozzles for introducing a cryogenic fluid from a source of cryogenic fluid into the thermal conditioning chamber, and (ii) a controller for controlling the quantity of cryogenic fluid sprayed into the thermal conditioning chamber to achieve and maintain a desired temperature within the thermal conditioning chamber.
The driven conveyor system is configured and arranged for continuously transporting phase change material panels from a conveyor loading position through the first and second enclosures and then to a conveyor unloading position.
A second embodiment of a two-stage inline system for thermal conditioning of cold chain phase change material panels in accordance with the second aspect of the invention includes first and second enclosures each defining a thermal conditioning chamber, first and second temperature control systems for controlling the temperature within the first and second thermal conditioning chambers respectively, and a driven conveyor system.
The first temperature control system includes (i) spray nozzles for introducing a cryogenic fluid from a source of cryogenic fluid into the first thermal conditioning chamber, and (ii) a controller for controlling the quantity of cryogenic fluid sprayed into the first thermal conditioning chamber to achieve and maintain a desired temperature within the thermal conditioning chamber.
The second temperature control system includes (i) a heat source for introducing heat into the second thermal conditioning chamber, and (ii) a controller for controlling the introduction of heat into the second thermal conditioning chamber to achieve and maintain a desired temperature within the second thermal conditioning chamber.
The driven conveyor system is configured and arranged for selectively and continuously transporting phase change material panels from a conveyor loading position to a selected conveyor unloading position along one of three available paths selected from (i) a primary path through both the first and second enclosures to a primary conveyor unloading position, (ii) a secondary path through only the first thermal conditioning chamber to a secondary conveyor unloading position, and (iii) a tertiary path through only the second thermal conditioning chamber to a tertiary conveyor unloading position. The driven conveyor system includes (1) an upstream platform length external to the first and second thermal conditioning chambers for carrying phase change material panels in need of thermal conditioning from the conveyor loading position along one of the three paths, (2) a first intermediate platform length in the first thermal conditioning chamber for providing a dwell time operable for thermally transitioning the phase change material within phase change material panels carried by the upstream length into the first thermal conditioning chamber from a first thermal state to a second thermal state, (3) a second intermediate platform length in the second thermal conditioning chamber for providing a dwell time operable for thermally transitioning the phase change material within phase change material panels carried by the driven conveyor system into the second thermal conditioning chamber from a first thermal state to a second thermal state, (4) a first diversion platform length external to the first and second thermal conditioning chambers for transporting phase change material panels exiting the first thermal conditioning chamber to a secondary conveyor unloading position, and (5) a second diversion platform length external to the first and second thermal conditioning chamber for transporting phase change material panels from the conveyor loading position into the second thermal conditioning chamber with bypass of the first thermal conditioning chamber.
A particular embodiment of a redundant two-stage inline system for thermal conditioning of cold chain phase change material panels in accordance with the third aspect of the invention includes first and second enclosures each defining a thermal conditioning chamber, first and second temperature control systems for controlling the temperature within the first and second thermal conditioning chambers respectively, and a driven conveyor system.
The first and second temperature control systems each include (1) spray nozzles for introducing a cryogenic fluid from a source of cryogenic fluid into the thermal conditioning chamber, (2) a heat source for introducing heat into the thermal conditioning chamber, and (3) a controller for controlling the quantity of cryogenic fluid sprayed into the thermal conditioning chamber and controlling the introduction of heat into the thermal conditioning chamber to achieve and maintain a desired temperature within the thermal conditioning chamber.
The driven conveyor system transports phase change material panels from a conveyor loading position to a conveyor unloading position through the first and second enclosures.
A particular embodiment of the driven conveyor system is configured and arranged for continuously and selectively transporting phase change material panels from a conveyor loading position to a selected conveyor unloading position along one of three available paths selected from (i) a primary path through both the first and second enclosures to a primary conveyor unloading position, (ii) a secondary path through only the first thermal conditioning chamber to a secondary conveyor unloading position, and (iii) a tertiary path through only the second thermal conditioning chamber to a tertiary conveyor unloading position.
A particular embodiment of a method of expedited ready-for-use thermal conditioning of thermally-spent cold chain phase change material panels in accordance with the fourth aspect of the invention includes the steps of (i) conveying the thermally-spent cold chain phase change material panels into a first thermal conditioning chamber cooled by a spray of a cryogenic fluid into the first thermal conditioning chamber, (ii) maintaining the thermally-spent cold chain phase change material panels within the first thermal conditioning chamber for a dwell time sufficient to thermally transition the thermally-spent cold chain phase change material panels to deep-frozen phase change material panels, (iii) conveying the deep-frozen phase change material panels into a second thermal conditioning chamber warmed by a heat source, and (iv) maintaining the deep-frozen phase change material panels within the second thermal conditioning chamber for a dwell time sufficient to thermally transition the deep-frozen phase change material panels to thermally-tempered phase change material panels.
As utilized herein, the phrase “deep-frozen” means frozen phase change material having a temperature more than 5° C. below the melt temperature of the phase change material. By analogy, the phrase “deep-frozen phase change material panels” means phase change material panels containing frozen phase change material having a temperature more than 5° C. below the melt temperature of the phase change material within the panel.
As utilized herein, the phrase “thermally tempered” means (1) as to phase change material for use in maintaining a payload chamber below anticipated environmentally experienced temperatures, frozen phase change material having a temperature no more than 5° C. below the melt temperature of the phase change material, and (2) as to phase change material for use in maintaining a payload chamber above anticipated environmentally experienced temperatures, liquid phase change material having a temperature no more than 5° C. above the freeze temperature of the phase change material. By analogy, the phrase “thermally tempered phase change material panels” means phase change material panels containing frozen phase change material having a temperature no more than 5° C. below the melt temperature of the phase change material within the panel, or phase change material panels containing liquid phase change material having a temperature no more than 5° C. above the freeze temperature of the phase change material within the panel.
As utilized herein, the phrase “thermally spent”, when used in connection with a cold chain phase change material panel, means an appreciable or complete phase change from a solid to a liquid when cooling is desired or from a liquid to a solid when warming is desired.
Referring to
Referring to
The intermediate platform length 120b is preferably a spiral conveyor 120, such as depicted in
The LN2 can be sprayed into the thermal conditioning chamber 109 defined by an enclosure 100 using spray nozzles 112 distributed throughout the thermal conditioning chamber 109 and connected to a supply of LN2 (not shown) via a manifold (not shown) with at least two branches (not shown). The manifold includes two valved branches, with each valve controlled by a temperature control system 110. The first branch is controlled by a first valve (not shown) in fluid communication with a first set of one or more spray nozzles 1121 that spray LN2 directly onto the PCM panels 300 on the conveyor 120 (“direct injection”) and a second branch controlled by a second valve (not shown) in fluid communication with a second set of one or more spray nozzles 1122 that spray LN2 into the holistic environment of the thermal conditioning chamber 109 (e.g., sprays LN2 into the airstream of one or more fans (not shown) positioned on the perimeter of the thermal conditioning chamber 109 to provide cyclonic airflow within the environment) (“indirect injection”). Ideally, these fans are configured and arranged to provide a cyclonic airflow within the environment that flow counter to the direction of conveyance to maximize convective heat transfer on the PCM panels 300.
A controller 116, such as a proportional-integral-derivative (PID) controller, controls the amount of LN2 injected into the thermal conditioning chamber 109 to control the environment temperature within the thermal conditioning chamber 109 at a specific setpoint. To ensure proper thermal conditioning of each and every PCM panel 300 it is imperative that the directly injected LN2 (i.e., the LN2 sprayed directly into contact with the PCM panels 300 on the conveyor 120) operates at a constant injection rate, while the indirectly injected LN2 (i.e., the LN2 sprayed into the environment of the thermal conditioning chamber 109) operates at a variable injection rate as necessary to maintain the overall environmental temperature of the thermal conditioning chamber 109 at a previously established setpoint. The amount of directly injected LN2 is selected below the total calculated heat load required to achieve and maintain the overall environmental temperature of the thermal conditioning chamber 109 at the previously established setpoint (e.g., 1%) to ensure that runaway low temperatures do not occur as is possible since the amount of LN2 directly injected is constant and independent of the environmental temperature within the thermal conditioning chamber 109. This allows the temperature dependent indirect injection valve to control the environmental temperature within the thermal conditioning chamber 109.
Referring to
The environments of each of the enclosures 2001 and 2002 can also be outfitted with heating elements 2141 and 2142 respectively, preferably elements capable of warming the environments up to +60° C. Controllers 2161 and 2162 can control both LN2 injection and operation of the heating elements 2141 and 2142 on each of the enclosures 2001 and 2002 respectively, to attain and maintain a set environmental temperature within the respective thermal conditioning chambers 2091 and 2092.
The driven conveyor system 220 includes (i) an upstream platform length 220a external to a first of the thermal conditioning chambers 2091 in sequence, for carrying phase change material panels 3000 in need of thermal conditioning from the conveyor loading position 230a along one of several paths, (ii) intermediate platform lengths 220bn, each providing a dwell time in one of the thermal conditioning chambers 209n for thermally transitioning a phase change material panel 300, (iii) a final downstream platform length 220c for conveying fully thermally conditioned phase change material panels 300 out from the last of the thermal conditioning chambers 209n in sequence, and optionally (iv) one or more diversion platform lengths 220dn, each allowing diversion of thermally transitioned phase change material panels 300 exiting one of the thermally conditioning chambers 209n from a primary path to a diversion path that bypasses one or more of the stages or enclosures 200n.
When the multi-stage inline conveyance system 200n is a two-stage system 200n, the conveyor system 220n includes (i) a first intermediate platform length 220b1 in the first thermal conditioning chamber 2091 for providing a dwell time operable for thermally transitioning the phase change material within phase change material panels 300 carried by the upstream length 220a into the first thermal conditioning chamber 2091 from a first thermal state to a second thermal state, (ii) a second intermediate platform length 220b2 in the second thermal conditioning chamber 2092 for providing a dwell time operable for thermally transitioning the phase change material within phase change material panels 300 carried by the driven conveyor system 200n into the second thermal conditioning chamber 2092 from a first thermal state to a second thermal state and optionally (iii) diversion platform lengths 220dn including one or both of (A) a first diversion platform length 220d1 external to the first and second thermal conditioning chambers 2091 and 2092 for transporting phase change material panels 300 exiting the first thermal conditioning chamber 2091 to a secondary conveyor unloading position 230b2, and (B) a second diversion platform length 220d2 external to the first and second thermal conditioning chambers 2091 and 2092 for transporting phase change material panels 300 from the conveyor loading position 230a directly into the second thermal conditioning chamber 2092 with bypass of the first thermal conditioning chamber 2091 to a tertiary conveyor unloading position 230b3.
Spiral conveyors 220, such as depicted in
By equipping each stage 200n (i.e., 2001 and 2002 for a two-stage system) of the system 200n with a temperature control system 210n (i.e., 2101 and 2102 for a two-stage system) that include both spray nozzles 2121 and 2122 for spraying a cryogenic fluid into the thermal conditioning chamber 2091 and 2092 respectively, and with heating elements 2141 and 2142 for warming the thermal conditioning chamber 2091 and 2092 respectively, the system 200n becomes a redundant system 200n whereby either of the stages 2001 and 2002 can be used for both deep freeze and thermal tempering of PCM panels 300 should one of the stages 2001 and 2002 suffer a mechanical failure. If, for example, the second unit 2002 is unavailable, deep-frozen PCM panels 3001 exiting the first unit 2001 may be diverted to a temperature-controlled storage (not shown). Upon batch completion of deep-frozen PCM panels 3001, the deep-freeze environment of the first unit 2001 can be converted into a thermal tempering environment and the stored deep-frozen PCM panels 3001 run through the first unit 2001 again to thermally transition the deep-frozen PCM panels 3001 to thermally tempered ready-to-use PCM panels 3002. This works mutatus mutandis when the first unit 2001 is unavailable and the second unit 2002 must be used for both thermal conditioning stages.
The two stage system 200n is flexible for handling a variety of different temperature conditioning requirements, including specifically but not exclusively the following examples of PCMs with unique freeze points.
Upon exit from the second stage unit 2002, thermally tempered ready-to-use PCM panels 3002 continue to an unloading position 230b1 where they can be installed into position within a thermally insulated shipping container (not shown). Upon completion of the install the now passive thermally controlled shipping container is immediately ready to receive a thermally labile temperature-sensitive payload (not shown) such as blood, organs, or pharmaceuticals for shipment.
Many such thermally insulated shipping containers require multiple sizes of thermally conditioned PCM panels 3002. The two stage system 200n can properly thermally condition an intermingled set of differently sized PCM panels 300 whereby a full set of intermingled PCM panels 300 necessary to complete a given thermally insulated shipping container can be processed together.
Number | Date | Country | |
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63609039 | Dec 2023 | US |