Patent Application
20200326117
The subject matter disclosed herein relates to an atmosphere control system for a refrigerated container, and specifically to a system for regulating the atmosphere (e.g., amounts of nitrogen, oxygen, and/or carbon dioxide) inside a refrigerated container resulting in an atmospheric composition that extends post-harvest shelf life or quality of perishables, such as fruits, vegetables, pharmaceuticals, etc.
A typical refrigerated cargo container, such as those utilized to transport cargo via sea, rail or road, is a container modified to include a refrigeration unit located at one end of the container. The refrigeration unit includes a compressor, condenser, expansion valve and evaporator. A volume of refrigerant circulates throughout the refrigeration unit, and one or more evaporator fans of the refrigeration unit blow a flow of supply air across the evaporator thereby cooling the supply air and forcing it out into the container.
An atmosphere control system controls the amount of oxygen and carbon dioxide inside the refrigerated container to, for example, change the rate of ripening of produce stored in the container. The atmosphere control system may control the amount of oxygen (O2) and carbon dioxide (CO2) in the container.
In one embodiment, a refrigeration unit for use with a container includes a compressor, a condenser, an expansion device and an evaporator configured to circulate a refrigerant; a condenser section housing the compressor and the condenser; an evaporator section housing the evaporator; an atmosphere control system including an air compressor configured to generate compressed air; a separator configured to receive the compressed air and output nitrogen; the air compressor located in the condenser section; the separator located in the evaporator section.
In addition to one or more of the features described herein, or as an alternative, further embodiments may include wherein the atmosphere control system comprises a valve between the air compressor and the separator.
In addition to one or more of the features described herein, or as an alternative, further embodiments may include wherein the valve, in an open position, directs compressed air to the container.
In addition to one or more of the features described herein, or as an alternative, further embodiments may include wherein the valve, in a closed position, directs compressed air to the separator.
In addition to one or more of the features described herein, or as an alternative, further embodiments may include a controller configured to control the valve to move between the open position and the closed position.
In addition to one or more of the features described herein, or as an alternative, further embodiments may include wherein the controller is configured to control the compressor.
In addition to one or more of the features described herein, or as an alternative, further embodiments may include a sensor in the evaporator section, the sensor configured to measure a level of a gas in the container; wherein the controller is configured to move the valve between the open position and the closed position in response to the level of the gas in the container.
In addition to one or more of the features described herein, or as an alternative, further embodiments may include wherein the atmosphere control system comprises a heat exchanger positioned between the air compressor and the separator, the heat exchanger configured to cool the compressed air from the air compressor.
In addition to one or more of the features described herein, or as an alternative, further embodiments may include wherein the atmosphere control system comprises a water separator between the heat exchanger and the separator.
In addition to one or more of the features described herein, or as an alternative, further embodiments may include wherein the atmosphere control system comprises at least one filter between the water separator and the separator.
In addition to one or more of the features described herein, or as an alternative, further embodiments may include wherein the at least one filter is located in the condenser section.
In another embodiment, an atmosphere control system for use with a container includes an air compressor configured to generate compressed air, the air compressor located outside the container; and a separator configured to receive the compressed air and output nitrogen into the interior of the container.
In addition to one or more of the features described herein, or as an alternative, further embodiments of the atmosphere control system may include a valve between the air compressor and the separator.
In addition to one or more of the features described herein, or as an alternative, further embodiments of the atmosphere control system may include wherein the valve, in an open position, directs compressed air to the container.
In addition to one or more of the features described herein, or as an alternative, further embodiments of the atmosphere control system may include wherein the valve, in a closed position, directs compressed air to the separator.
In addition to one or more of the features described herein, or as an alternative, further embodiments of the atmosphere control system may include a controller configured to control the valve to move between the open position and the closed position.
In addition to one or more of the features described herein, or as an alternative, further embodiments of the atmosphere control system may include a sensor in the evaporator section, the sensor configured to measure a level of a gas in the container; wherein the controller is configured to move the valve between the open position and the closed position in response to the level of the gas in the container.
In addition to one or more of the features described herein, or as an alternative, further embodiments of the atmosphere control system may include a heat exchanger positioned between the air compressor and the separator, the heat exchanger configured to cool the compressed air from the air compressor.
In addition to one or more of the features described herein, or as an alternative, further embodiments of the atmosphere control system may include the atmosphere control system comprises a water separator between the heat exchanger and the separator.
In addition to one or more of the features described herein, or as an alternative, further embodiments of the atmosphere control system may include at least one filter between the water separator and the separator.
Technical effects of embodiments of the present disclosure include the provision of an air compressor of an atmosphere control system in a condenser section of a refrigeration unit for use with a container.
The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, that the following description and drawings are intended to be illustrative and explanatory in nature and non-limiting.
The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements.
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawing.
Shown in
Referring to
The refrigeration unit 24 is separated into an evaporator section 54 containing the evaporator 32, the evaporator fan 34 and an evaporator fan motor 56 and a condenser section 58 containing the compressor 26, the condenser 28 and the expansion device 30. In some embodiments, the expansion device 30 may be located in the evaporator section 54. The evaporator section 54, located above the condenser section 58 in some embodiments, is separated from the condenser section 58 by a panel 50 that extends across the refrigeration unit 24. The condenser section 58 is exposed to ambient air and may be covered by panels having openings formed therein. In operation, refrigerant is circulated in serial fashion through the compressor 26, the condenser 28, the expansion device 30, the evaporator 32 and back to the compressor 26. It is understood that the refrigeration unit 24 may include additional components (e.g., economizer, receiver, SMV, etc.) that are not shown.
Referring now to
From the second filter 88 and the third filter 89, the compressed air flows to a first valve, V1. The first valve V1 has two outlets, which can be controlled by controller 70. When the first valve V1 is in a first position (e.g., an open position when energized), the compressed air is output from the first valve V1 to the interior of the container 10. The first valve V1 may be located to provide the air upstream of the evaporator 32. When the first valve V1 is in a second position (e.g., a closed position when not energized), the compressed air is directed to a separator 90. The separator 90 may be a membrane separator that generates an output of highly pure, separated nitrogen upstream of evaporator 32. Other atmospheric gases, including oxygen, argon and carbon dioxide, are vented to the condenser section 58 and outside of the refrigeration unit 24. The nitrogen from separator 90 is directed to a second valve V2. The second valve V2 is a bleeder port that allows a small portion of the nitrogen from the separator 90 to be sent to a nitrogen sensor 96 to measure the purity of the nitrogen. The second valve V2 may be controlled by the controller 70.
When nitrogen is provided upstream of the evaporator 32, the nitrogen enters the interior of the container 10 and forces oxygen and carbon dioxide out of the interior of the container 10. Reducing the oxygen level in the container 10 reduces ripening of produce. Reducing the carbon dioxide level in the container 10 prevents damage to cargo in the container due to high carbon dioxide levels.
In operation, the controller 70 monitors levels of at least one gas inside the container 10, using oxygen sensor 92 and/or carbon dioxide sensor 94 in communication with the controller 70. The oxygen sensor 92 and/or carbon dioxide sensor 94 may be located in the evaporator section 54, upstream of the evaporator 32. To add outside air to the container, the controller 70 sends a signal to turn on the air compressor 80 and sends a signal to the first valve V1 to set the first valve V1 to the open position. This directs the compressed air from the air compressor 80 to the interior of the container 10. To add nitrogen to the container to control the levels of other gasses, the controller 70 sends a signal to turn on the air compressor 80 and closes valve VI. This directs the compressed air from the air compressor 80 to the separator 90, which produces nitrogen that is directed to the interior of the container 10 (e.g., upstream or downstream of the evaporator 32). To measure purity of the nitrogen generated by the separator 90, the controller 70 opens the bleeder port of the second valve V2 to direct a portion of the nitrogen to the nitrogen sensor 96 in communication with the controller 70. In some embodiments, a separate nitrogen sensor 96 is not used, as the measurements from the oxygen sensor 92 provides an indication of the nitrogen level in the container 10.
Positioning the air compressor 80 in the condenser section 58 allows use of an air compressor not requiring an enclosed motor and enclosed crankcase, thereby allowing some acceptable amount of air blow (i.e., air leakage due to pressure and movement of the cylinders) from compressor crankcase. If a non-enclosed compressor was placed inside in the evaporator section, air blow from the compressor crankcase would directly impact system performance by not allowing proper control of oxygen. Positioning the air compressor 80 in the condenser section 58 also provides easier access for maintenance on the air compressor 80. A removable shield or plate can be used to protect the air compressor 80 from outside elements such as water and dirt, since the air compressor is located in the condenser section 58 and not inside the container 10. The atmosphere control system 74 is controlled by the same controller 70 used to control the refrigeration unit 24, or by a separate controller.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/833,066, filed Apr. 12, 2019, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62833066 | Apr 2019 | US |
