Temperature controlled cargo containers
Temperature controlled cargo containers may include thermal masses conditioned to temperatures above and/or below a target temperature. Example thermal masses may include plates including phase change materials, such as eutectic materials. One or more fans and flapper valves may be selectively operated to circulate air in the cargo container across one or more of the thermal masses to maintain the temperature within the cargo container within a prescribed temperature band. Some example temperature controlled cargo containers may include refrigeration units and/or heaters for regenerating the thermal masses when receiving power from an external power source and/or may include one or more rechargeable batteries for providing power during transport or storage independent of external power sources.
1. A temperature controlled cargo container for shipping a product at or near a target temperature, the cargo container comprising:
an interior storage space for receiving the product;
a warm phase change plate arranged for selective heat exchange with the interior storage space, the warm phase change plate having a generally flattened rectangular shape including a flat exterior front face and a flat exterior rear face, the warm phase change plate containing a warm phase change material;
a cold phase change plate arranged for selective heat exchange with the interior storage space, the cold phase change plate having a generally flattened rectangular shape including a flat exterior front face and a flat exterior rear face, the cold phase change plate containing a cold phase change material located between the front face and the rear face;
an insulated divider wall interposing the cold phase change plate and the warm phase change plate, the warm phase change plate being mounted such that it is at least partially thermally insulated from the cold phase change plate;
at least one coil extending within the cold phase change plate and in direct contact with the cold phase change material, wherein a chilled fluid is adapted to circulate through the coil to thereby cool the cold phase change material of the cold phase change plate;
wherein the warm phase change plate and the cold phase change plate are at least partially separated from the interior storage space by a separator wall, the separator wall defining a plurality of openings;
a downwardly extending wall located between the separator wall and the warm phase change plate;
an upwardly extending wall located between the separator wall and the cold phase change plate;
a first fan selectively operable to draw air from within the interior storage space, through a first opening in the separator wall, then along a first serpentine flow path comprising a first direction between the separator wall and the downwardly extending wall, a second direction opposite the first direction between the downwardly extending wall and the flat exterior front face of the warm phase change plate, and a third direction opposite the second direction, then through a second opening in the separator wall and into the interior storage space; and
a second fan selectively operable to draw air from within the interior storage space, through a third opening in the separator wall, then along a second serpentine flow path comprising a first direction between the separator wall and the upwardly extending wall, a second direction opposite the first direction between the upwardly extending wall and the flat exterior front face of the cold phase change plate, and a third direction opposite the second direction, then through a fourth opening in the separator wall and into the interior storage space.
2. The temperature controlled cargo container of claim 1 further comprising at least one trap arranged to reduce natural convection heat transfer between at least one of said warm phase change plate and said cold change phase plate and the interior storage space.
3. The temperature controlled cargo container of claim 1 further including at least one valve operable to permit airflow about at least one of said warm phase change plate and said cold phase change plate wherein said at least one valve comprises a flapper valve including a flapper valve backer, wherein flapper valve and said flapper valve backer further comprises a magnet, and wherein said flapper valve and said flapper valve backer further comprises ferrous material, wherein when one of said first and second fans is operating sufficient airflow is generated to overcome an associated magnetic force between said flapper valve and said flapper valve backer such that said flapper valve is open and airflow is permitted therethrough, and wherein when one of said first and second fans is shut off the associated magnetic force between said flapper valve and said flapper valve backer causes said flapper valve to close and obstruct airflow between said interior storage space and at least one of said warm phase change plate and said cold phase change plate.
4. The temperature controlled cargo container of claim 1 including an electrical resistance heater in thermal contact with the warm phase change plate.
5. The temperature controlled cargo container of claim 1 further comprising:
a heat exchanger in thermal contact with the warm phase change plate wherein warmed fluid may be propelled through conduits and quick disconnect fittings and into the warm phase change plate and in direct contact with the warm phase change material.
6. The temperature controlled cargo container of claim 1 wherein the warm phase change plate comprises a front wall and an opposing rear wall and one or more thermally conductive fins extending through the warm phase change plate from the front wall to the opposing rear wall.