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The present invention provides apparatus and methods for adjusting the atmosphere within a substantially sealed chamber containing respiring produce. The chamber of the present invention includes inlet means to permit ambient atmosphere to enter the chamber, and outlet means to permit chamber atmosp

The present invention provides apparatus and methods for adjusting the atmosphere within a substantially sealed chamber containing respiring produce. The chamber of the present invention includes inlet means to permit ambient atmosphere to enter the chamber, and outlet means to permit chamber atmosphere to exit the chamber. Methods using apparatus of the present invention comprise: (a) monitoring the oxygen concentration within the chamber;(b) following detection that the oxygen concentration in the chamber has fallen below a predetermined amount, opening the inlet means so that the amount of oxygen in the chamber increases; and(c) removing carbon dioxide from the chamber atmosphere substantially at a predetermined rate, the predetermined rate having been selected such that the carbon dioxide concentration within the chamber atmosphere does not substantially exceed a predetermined amount. The methods may also comprise opening the inlet means for a time that is approximately proportional to the difference between the detected oxygen concentration and an oxygen setpoint.

대표청구항 ▼

1. A method for adjusting the atmosphere within a chamber containing respiring produce, the chamber having inlet means to permit ambient atmosphere to enter the chamber, and outlet means to permit chamber atmosphere to exit the chamber, the method comprising: (a) monitoring the oxygen concentration

1. A method for adjusting the atmosphere within a chamber containing respiring produce, the chamber having inlet means to permit ambient atmosphere to enter the chamber, and outlet means to permit chamber atmosphere to exit the chamber, the method comprising: (a) monitoring the oxygen concentration within the chamber;(b) following detection that the oxygen concentration in the chamber has fallen below a predetermined amount as a result of the consumption of oxygen by the respiring produce, causing or permitting ambient atmosphere to enter the chamber so that the amount of oxygen in the chamber increases to maintain the oxygen concentration above a preset oxygen concentration to prolong the storage life of the respiring produce, the preset oxygen concentration being greater than zero but less than an oxygen concentration in ambient air; and(c) without actively monitoring and actively controlling the carbon dioxide concentration within the chamber, continuously removing the carbon dioxide from the chamber atmosphere substantially at a predetermined carbon dioxide removal rate by using an amount of a carbon dioxide absorbing material in the chamber in communication with the chamber atmosphere, the predetermined carbon dioxide removal rate having been selected such that a non-zero carbon dioxide concentration is maintained within the chamber atmosphere, which does not substantially exceed a predetermined level, in order to maintain the carbon dioxide concentration within a pre-determined desired range to inhibit deterioration of the respiring produce, wherein the amount of carbon dioxide absorbing material in the chamber maintains the carbon dioxide concentration within the predetermined range. 2. The method according to claim 1, wherein the predetermined carbon dioxide removal rate is calculated from a formula derived from a mathematical model of the proportions of the chamber atmosphere subject to the requirement that the oxygen concentration within the chamber be substantially maintained at a predetermined amount, and wherein said predetermined carbon dioxide removal rate is calculated from a formula that produces a result substantially equal to the result produced by a calculation in accordance with the following formula: aCO2=rCO2-0.79⁢pCO2⁢rO2(0.21-pO2)-0.21⁢pCO2where aCO2 is the carbon dioxide removal rate; pO2 is the oxygen setpoint, expressed as a proportion; pCO2 is the desired carbon dioxide concentration within the chamber, expressed as a proportion; rO2 is the respiration rate; and rCO2 is the rate of production of carbon dioxide through respiration. 3. The method according to claim 1, wherein said carbon dioxide absorbing material is contained in at least one carbon dioxide transmissible container, said at least one carbon dioxide transmissible container being selected so that the rate of carbon dioxide transmission into said at least one carbon dioxide transmissible container is substantially equal to said predetermined carbon dioxide removal rate. 4. The method according to claim 2, wherein said carbon dioxide absorbing material is contained in at least one carbon dioxide transmissible container, said at least one carbon dioxide transmissible container being selected so that the rate of carbon dioxide transmission into said at least one carbon dioxide transmissible container is substantially equal to said predetermined carbon dioxide removal rate. 5. The method according to claim 1, wherein ambient atmosphere is caused to enter the chamber by way of the inlet means, including the step of opening the inlet mean for a time approximately proportional to the difference between a detected oxygen concentration and an oxygen setpoint. 6. The method according to claim 5, wherein, if the difference between the detected oxygen concentration and the oxygen setpoint exceeds a predetermined amount, the inlet means is maintained open until detection that the oxygen concentration in the chamber has exceeded a predetermined value. 7. The method according to claim 1, wherein removal of chamber atmosphere from the chamber by way of the outlet means causes ambient atmosphere to enter the chamber by way of the inlet means. 8. The method according to claim 1, wherein the chamber is substantially sealed against leakage, such that the rate of consumption of oxygen by the respiring produce exceeds the rate of leakage of oxygen into the chamber from the ambient atmosphere. 9. A method for adjusting the atmosphere within a chamber containing respiring produce, the respiring produce being maintained within the chamber for a storage time, the method comprising: (a) placing an amount of carbon dioxide absorbing material in communication with the chamber so as to absorb the difference between a predicted level of carbon dioxide in the chamber based on the rate of consumption of oxygen by the produce and a desired carbon dioxide level so that a non-zero carbon dioxide concentration within a pre-determined range is maintained in the chamber during the storage time without active monitoring and control of the carbon dioxide concentration within the chamber, the non-zero carbon dioxide concentration not substantially exceeding said desired level in order to inhibit deterioration of the respiring produce;(b) substantially sealing the chamber;(c) monitoring oxygen concentration within the chamber;(d) adjusting an oxygen level in the chamber to a level above a desired oxygen setpoint to prolong the storage life of the respiring produce, the desired oxygen setpoint being greater than zero but less than an oxygen concentration in ambient air;(e) permitting the oxygen level in the chamber to degrade to about the oxygen setpoint as a consequence of oxygen consumed by the respiring produce being converted to carbon dioxide;(f) removing chamber atmosphere from the chamber and admitting ambient atmosphere into the chamber; and(g) repeating steps (f), (g) and (h) as required if the oxygen level falls below the oxygen setpoint, to maintain the oxygen level in the region of the oxygen setpoint. 10. The method according to claim 9, wherein a rate of removal of carbon dioxide from the chamber is calculated from a formula that produces a result substantially equal to the result produced by a calculation in accordance with the following formula: aCO2=rCO2-0.79⁢pCO2⁢rO2(0.21-pO2)-0.21⁢pCO2where aCO2 is the carbon dioxide removal rate; pO2 is the oxygen setpoint, expressed as a proportion; pCO2 is the desired carbon dioxide concentration within the chamber, expressed as a proportion; rO2 is the respiration rate; and rCO2 is the rate of production of carbon dioxide through respiration. 11. A method for adjusting the atmosphere within a chamber containing respiring produce, the respiring produce being maintained within the chamber for a storage time, the method comprising: (a) maintaining the oxygen concentration in the chamber atmosphere substantially at a predetermined oxygen setpoint to prolong the storage life of the respiring produce, the oxygen setpoint being greater than zero but less than an oxygen concentration in ambient air; and(b) without active monitoring and control of carbon dioxide concentration within the chamber, continuously removing the carbon dioxide from the chamber atmosphere substantially at a predetermined carbon dioxide removal rate with an amount of carbon dioxide absorbing material in communication with the chamber atmosphere, the predetermined rate having been selected such that a non-zero carbon dioxide concentration is maintained within the chamber atmosphere, which does not substantially exceed a predetermined amount, thereby to maintain the carbon dioxide concentration within a pre-determined desired range for the storage time in order to inhibit deterioration of the respiring produce,wherein the oxygen concentration in the chamber atmosphere is maintained substantially at the setpoint by: (i) monitoring the oxygen concentration in the chamber and following detection that the oxygen concentration has fallen below the setpoint, or below a tolerance about the setpoint; (ii) admitting ambient air into the chamber so that the amount of oxygen in the chamber increases; and (iii) causing or permitting chamber atmosphere to exit the chamber. 12. The method according to claim 11, wherein said predetermined carbon dioxide removal rate is calculated from a formula that produces a result substantially equal to the result produced by a calculation in accordance with the following formula: aCO2=rCO2-0.79⁢pCO2⁢rO2(0.21-pO2)-0.21⁢pCO2where aCO2 is the carbon dioxide removal rate; pO2 is the oxygen setpoint, expressed as a proportion; pCO2 is the desired carbon dioxide concentration within the chamber, expressed as a proportion; rO2 is the respiration rate; and rCO2 is the rate of production of carbon dioxide through respiration. 13. The method according to claim 11, wherein the carbon dioxide absorbing material is contained in at least one carbon dioxide transmissible container, the at least one carbon dioxide transmissible container being selected so that the rate of carbon dioxide transmission into said at least one carbon dioxide transmissible container is substantially equal to said predetermined carbon dioxide removal rate. 14. The method according to claim 11, wherein ambient atmosphere is admitted into the chamber by way of an inlet means opened for a time determined in accordance with a difference between the detected oxygen concentration and the oxygen setpoint. 15. A method for adjusting the atmosphere within a chamber containing respiring produce, the method involving monitoring the oxygen concentration within the chamber without actively monitoring and controlling the carbon dioxide concentration within the chamber, the method comprising the steps of maintaining the oxygen concentration in the chamber atmosphere substantially at a predetermined oxygen setpoint to prolong the storage life of the respiring produce, the predetermined oxygen setpoint being greater than zero but less than an oxygen concentration in ambient air, predicting the carbon dioxide concentration in the chamber that would be expected to result in the absence of any adjustment to the carbon dioxide concentration, and independently adjusting the carbon dioxide concentration in the chamber by determining the difference between the predicted level of carbon dioxide in the chamber and a desired carbon dioxide concentration so that the carbon dioxide concentration in the chamber is maintained at a non-zero equilibrium concentration within a pre-determined range for the storage time, and installing in the chamber one or more containers of hydrated lime of predetermined carbon dioxide transmissibility in communication with the chamber atmosphere whereby carbon dioxide is absorbed into the containers so that the concentration of carbon dioxide in the chamber is maintained at the non-zero equilibrium concentration, in order to inhibit deterioration of the respiring produce. 16. The method according to claim 9, further comprising, before said step of substantially sealing the chamber, the step of flushing the chamber with a purging gas having a low oxygen concentration or no oxygen.