Dynamic control system and method for controlled atmosphere room

• US 8,739,694 B2
• Filed: 10/26/2010
• Issued: 06/03/2014
• Est. Priority Date: 10/26/2010
• Status: Active Grant

• Current Assignee: James C. Schaefer
• Original Assignee: James C. Schaefer
• Inventors: Schaefer, James C., Bishop, David J.
• Primary Examiner(s): Ross, Dana
• Assistant Examiner(s): Teaters, Lindsey C
• Application Number:
  US12/911,799
• Publication Number:
  US 20120097050A1
• Time in Patent Office: 1,316 Days
• Field of Search: 994/68, 994/73, 994/74, 700/214, 95/3, 95/26, 951/59, 951/71, 96/19, 426/312
• US Class Current: 99/468
• CPC Class Codes: A23B 7/144 in the form of gases, e.g. fumigation; Compositions or apparatus therefor
• CPC Class Codes: A23B 7/148 in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O
• CPC Class Codes: A23L 3/3418 in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O

Abstract

A control system for a controlled atmosphere room (“CA room”) for storing perishable commodities, such as fruits and vegetables. The control system includes an enclosure that can be placed within the CA room to store a representative sample of the commodities in the CA room. The control system includes an atmosphere valve selectively operable to provide atmospheric communication between the enclosure and the CA room or to isolate the enclosure from the CA room. The control system includes a sampling control system for determining a dynamic control value based on the isolated representative sample. The dynamic control value may be determined by monitoring the respiratory quotient in the enclosure while it is isolated. Once determined, the control system can use the dynamic control value to adjust the atmosphere of the CA room, thereby using tests on a representative sample to control the atmosphere for the full volume of commodities in the CA room. When not testing, the enclosure generally remains in atmospheric communication with the CA room, which improves the correlation of the representative sample with the commodities in the CA room.

Claims

1. A control system for use in a gastight storage facility containing a bulk perishable commodities comprising:

a test enclosure disposed within the gastight storage facility defining an interior space of sufficient size to hold a representative sample of the commodities;

an atmosphere valve selectively movable between an open position in which said interior space is in atmospheric communication with the gastight storage facility, whereby the representative sample of commodities in the interior space and the bulk of commodities in the gastight storage facility are subject to common atmospheric conditions, and a closed position in which said interior space is isolated from the gastight storage facility, whereby the representative sample of the commodities can be subjected to different atmospheric conditions than the bulk of the commodities in the gastight storage facility; and

a controller for dynamically controlling the atmosphere in the gastight storage facility, said controller configured to control said atmosphere valve to selectively isolate said interior space from the gastight storage facility, said controller configured to determine a dynamic control value by analyzing atmosphere within said interior space while said enclosure is in isolation from said gastight storage facility, said dynamic control value derived from a response of the representative sample of commodities to changes in atmosphere within said interior space, said controller configured to control the atmosphere in the gastight storage facility as a function of said determined dynamic control value.

2. The control system of claim 1 wherein said dynamic control value is further defined as an oxygen level.

3. The control system of claim 2 wherein said controller is configured to determine said oxygen level based on a respiratory quotient of said representative sample while said sample is in isolation from the gas tight storage space.

4. The control system of claim 1 further comprising an oxygen analyzer and a carbon dioxide analyzer, said controller configured to determine said respiratory quotient based on readings from said oxygen analyzer and said carbon dioxide analyzer.

5. The control system of claim 1 further comprising a gas analyzer, said controller configured to selectively supply atmosphere from either said interior space or the gastight storage facility to said gas analyzer, whereby a single gas analyzer may be used to monitor the gastight storage facility and to determine a dynamic control value from said representative sample in said interior space.

6. The control system of claim 5 wherein said gas analyzer is further defined as an oxygen analyzer and a carbon dioxide analyzer.

7. The control system of claim 6 wherein said atmosphere valve includes an inlet valve, an outlet valve and a fan for moving atmosphere from the gastight storage facility into said interior space through said inlet valve and from said interior space to the gastight storage facility through said outlet valve.

8. The control system of claim 1 further including a supply line and a return line coupling said interior space to said controller, said controller configured to sample atmosphere from said interior space and to return said sampled atmosphere to said interior space.

9. A controlled atmosphere storage system comprising:

a gastight storage facility of sufficient size to store a volume of perishable commodities;

a test enclosure disposed within said gastight storage facility, said enclosure defining an interior space of sufficient size to hold a representative sample of said commodities;

an atmosphere valve selectively movable between an open position in which said interior space is in atmospheric communication with the gastight storage facility such that the volume of perishable commodities and the sample of commodities may mature while subject to a shared atmosphere, and a closed position in which said interior space is isolated from the gastight storage facility such that test can be performed on the representative sample without impacting the volume of perishable commodities; and

a control system for controlling the atmosphere in the gastight storage facility, said control system configured to periodically isolate said interior space from the gastight storage facility by operation of said atmosphere valve and to determine a dynamic control value from said representative sample while said representative sample is in isolation from said gastight storage facility, said dynamic control value derived from a response of the representative sample of commodities to changes in atmosphere within said interior space, said controller configured to adjust the atmosphere in the gastight storage facility as a function of said determined dynamic control value.

10. The storage system of claim 9 wherein said dynamic control value is further defined as an oxygen level, and wherein said control system is configured to determine said oxygen level based on a respiratory quotient of said representative sample while said sample is in isolation from the gas tight storage space.

11. The storage system of claim 9 further comprising a gas analyzer, said control system configured to selectively supply atmosphere from either said interior space or the gastight storage facility to said gas analyzer, whereby said gas analyzer may be used alternately to monitor the gastight storage facility or to determine said dynamic control value from said representative sample in said interior space.

12. The storage system of claim 11 wherein said gas analyzer is further defined as an oxygen analyzer and a carbon dioxide analyzer.

13. The storage system of claim 9 wherein said atmosphere valve includes an inlet valve, an outlet valve and a fan for moving atmosphere from the gastight storage facility into said interior space through said inlet valve and from said interior space to the gastight storage facility through said outlet valve.

14. The storage system of claim 9 wherein said control system includes a supply line and a return line coupling said interior space to a gas analyzer, said control system configured to sample atmosphere from said interior space with said gas analyzer and to return said sampled atmosphere to said interior space.

15. A method for dynamic control in a gastight storage space, comprising the steps of:

providing a gastight storage space for storing a volume of commodities;

providing a test enclosure within said gastight storage space with an interior space for storing a representative sample of the commodities;

generally maintaining the test enclosure in atmospheric communication with the gastight space, whereby the volume of perishable commodities and the sample of commodities may mature while subject to a shared atmosphere;

periodically and temporarily isolating the atmosphere of the test enclosure from the atmosphere in the gastight space, whereby the sample of commodities may be selectively subjected to a different atmosphere than the volume of commodities and tests can be performed on the representative sample in the different atmosphere without having the different atmosphere impact the volume of perishable commodities;

determining a dynamic control value based on the representative sample while the atmosphere of the test enclosure is isolated from the atmosphere in the gastight space, the dynamic control value derived from a response of the representative sample of commodities to changes in atmosphere within the interior space;

adjusting the atmosphere of the gastight storage space as a function of the dynamic control value determined from the isolated sample; and

returning the atmosphere in the test enclosure to communication with the atmosphere in the gastight space between the periodic and temporary isolation periods, such that the representative sample remains substantially correlated with the commodities in the gastight storage space.

16. The method of claim 15 wherein said determining step is further defined as determining the lowest oxygen level that permits normal respiration in the representative sample;

and

wherein said adjusting step includes bringing the oxygen level in the gastight storage space to the determined lowest oxygen level.

17. The method of claim 16 wherein said determining step is further defined as determining the lowest oxygen level that permits normal respiration in the representative sample based on the respiratory quotient of the representative sample.

18. The method of claim 17 wherein said determining step includes the steps of:

moving a sample of gas from the enclosure to an oxygen analyzer and a carbon dioxide analyzer;

determining an oxygen level of the sample of gas and a carbon dioxide level of the sample of gas;

computing the respiratory quotient as a function of the determined oxygen and carbon dioxide levels; and

returning gas to the enclosure to substantially maintain appropriate pressure in the enclosure.

19. The method of claim 18 wherein said determining step includes the step of setting the lowest possible oxygen level as the lowest oxygen level at which the representative sample returned a respiratory quotient within a predetermined range.

20. The method of claim 15 wherein said determining step is further defined as determining a dynamic control value based on ethanol accumulation or chlorophyll fluorescence in the enclosure.