NL2021117B1

NL2021117B1 - System for modifying an atmosphere in a container for transporting or storing perishable goods

Info

Publication number: NL2021117B1
Application number: NL2021117A
Authority: NL
Inventors: Johannes Sjerp Lukasse Leijn; Bart Wissink Edo; Hemmes Westra Eelke
Original assignee: Stichting Wageningen Res
Priority date: 2018-06-14
Filing date: 2018-06-14
Publication date: 2019-12-20

Abstract

The present invention relates to a container for transporting and/or storing perishable goods, in combination with a) at least one fast release compartment comprising dry ice, wherein the at least one fast release compartment has a heat leakage rate of at least 5 W / °C; and b) at least one slow release compartment comprising dry ice, wherein the at least one slow release compartment has a heat leakage rate of between 0.05-5 W/ °C. The present invention also relates to the use of a system comprising the elements a) and b) for achieving and/or maintaining an elevated C02 level, preferably in a confined space, more preferably in a container for transporting and/or storing perishable goods.

Description

Technical field

The present disclosure relates to a system and method for modifying an atmosphere in a confined space, preferably a container for transporting and/or storing perishable goods. In particular, the present disclosure relates to a method for achieving and maintaining an elevated CO2 level in such confined space, as well as means therefor.

Background of the invention

Products such as vegetables, fruit, meat and fish are, after harvest/slaughter/catch, typically stored or transported in a modified atmosphere to maintain high quality of the products and inhibit the growth of unwanted organisms like bacteria, fungi and insects.

For example, the growth of Botryitis cinerea is one of the main post-harvest issues in table grapes (Chervin et al., 2012), and is traditionally controlled by using SO2as fungicide (Lichter et al., 2008), but preferably by the relatively new alternative of CO2 (see e.g. Retamales et al., 2003; Crisosto et al., 2002a; Crisosto et al., 2002b; Artés-Hernandez et al., 2004; Teles et al., 2014; Rosales et al., 2013).

From all this research on the effect of CO2, it appears that an atmosphere with approx. 12 % significantly suppresses the growth of Botryitis cinerea. However, the respiration rate of most products is too low to rapidly achieve and maintain 12 vol.% CO2in a standard transport container. Hence, an additional source of CO2 is needed. This source could be dry ice, which is the solid form of CO2. One of the physical properties of dry ice is that, at atmospheric pressure, it sublimates at -78.5 °C.

EP0368678 discloses a transport container comprising an insulated box with dry ice, having a refrigerating system to control the rate of decay of dry-ice and a heating device to allow the decay process to be temporarily speeded up. However, the arrangement of EP0368678 provides problems, since at least the refrigerating system and the heating device have to be returned to their source, after the products have been delivered.

-2Therefore, there remains a need to develop a new method for modifying an atmosphere in a container for storing or transporting perishable goods, in particular a method for achieving and maintaining a high CO2 level in such container, as well as means therefor.

Detailed description of the invention

The present inventors found that the limitations of the prior art solutions can be overcome by providing a container, e.g. a container for storing and/or transporting perishable goods, in combination with (or comprising):

- at least one fast release compartment which may comprise between 1-50, 5-30, preferably 10-20 kg dry ice, wherein the at least one fast release compartment preferably has a heat leakage rate of at least 2, 5, 10, 15, or 20 W / °C; and

- at least one slow release compartment which may comprise between 5-500, 5-250, 10-100, 10-50, preferably between 20-40 kg dry ice, wherein the at least one slow release compartment preferably has a heat leakage rate of between 0.01-10, 0.05-10, 0.01-2.5 or more preferably 0.05-5 or 0.1 - 2.5, 0.2-0.6, 0.3-0.4 W/ °C.

It was found that the fast release compartment with low or no thermal insulation can provide for an initial boost of CO2 release, while the slow release compartment with high thermal insulation can maintain the CO2 level within a desired range for a prolonged period of time. A particular advantage is that there is no need for gas bottles for containing the CO2, and no need for cooling/heating devices for regulating CO2 release from the dry ice sources.

Figure 6 shows that by using a slow and fast release compartment as according to the present disclosure, a CO2 profile can be achieved which is closer to the desired CO2 level during the entire transport and particularly during the first days thereof, in comparison to prior art methods using only an insulated box for slow release of CO2.

Preferably, the internal volume of the container has an (average) temperature of between -515, preferably between -5 and 10, most preferably between -2 and 5 or between -2 and 2 °C and/or the container has an open (free) internal volume of between 10 - 200 m³, preferably between 50-150 m³, more preferably between 50-100, or 60-90, 75-85 m³. The container can be a storage room or cold room.

The container may be a refrigerated container, and may constitute an intermodal refrigerated shipping container, a.k.a. refrigerated ISO container (ISO 1496). A refrigerated container, or a so-called reefer container, is a shipping container used for temperature-controlled storage or transport of temperature-sensitive freight.

-3Preferably, the at least one fast release compartment according to the present disclosure allows for release of gaseous CO₂, i.e. into the internal volume of the container, by a rate of at least 100, 150, 200, 250, 300, 400, 500, 600, 700, 800, 900 or 1000 g gaseous CO₂per hour, whereas the at least one slow release compartment according to the present disclosure preferably allows for release of gaseous CO₂, i.e. into the internal volume of the container, by a rate of between 1-500, 10-750, 50-500, 100-300, 100-200, or 250-350 g gaseous CO₂per hour.

Solid CO2 at atmospheric pressure has a sublimation point of -78.5 °C, hence the temperature of the dry ice as contained in the compartments (or at least 50, 75, 95, 99, or 100 wt% thereof and/or at least 50, 75, 95, 99, or 100 of the surface thereof) preferably is between -75 and -80 or -78.5 °C, i.e. during sublimation/operation. Further, the gas pressure surrounding the system according to the present disclosure is preferably between 0.8 and 1.2 bar, preferably between 0.9 and 1.1 bar or between 0.95 and 1.05 bar.

The heat leakage rate (U) values of the compartments typically follow from their dimensions, and the heat conduction coefficient A_Com_Partment of the material of which they are made:

In particular, the heat leakage rate (U) of a fast or slow release compartment according to the present disclosure can be determined by activating an electric heater element of known capacity (W) inside a compartment, placing the compartment in a place with constant outside temperature and measuring the equilibrium inside temperature.

There is no particular limitation to the design or arrangement of the slow or fast release compartments. Each compartment has two characteristics: its U-value and its internal volume. Preferably the fast release compartment's internal volume is large enough to contain the amount of dry ice needed to achieve the target CO₂ concentration of e.g. 12%, while in order to rapidly achieve the target CO₂ concentration it should preferably have as little insulation as possible, i.e. the larger its U-value the better. Preferably the slow release compartment has a U-value such that the release rate of gaseous CO₂ from the compartment together with the respiratory CO₂ production of the stored products in the confined space equals the loss of CO₂ from the space due to air leakage, i.e. the unintended exchange of modified atmosphere from inside the container with regular atmosphere from outside the container due to imperfect air tightness. Preferably, the slow release compartment has an internal volume large enough to contain the amount of dry ice needed to continue the

-4intended release over an intended duration. For example in a container transport which takes 35 days from origin to destination the intended duration could be 35 days. If the intended CO2 release rate from the slow release compartment is 4 kg/day then its internal volume should be large enough to contain at least 4 x 35 = 140 kg of dry ice.

Preferably, the slow release compartment is different and/or separate from the fast release compartment. For example, the fast release compartment may be a platform or part of the floor of the container according to the present disclosure, or the fast release compartment may be a container preferably having an opening of at least 100, 200, 500, or 1000 cm²allowing unhindered release of gaseous CO2from the fast release compartment. In an exemplary embodiment, dry ice for fast release is poured out on the floor of the container, e.g. at the door of the container according to the present disclosure. Preferably the slow and/or fast release compartments are not hermetically sealed pressure vessels, i.e. allow flow of gaseous CO2 from the compartment to the container’s internal volume.

In a preferred embodiment, the slow release compartment is an insulated container preferably made of material comprising at least 50, 80, 90, 95, 99 or 100 wt.% closed-cell extruded polystyrene foam.

The at least one fast release compartment typically comprises between 5-100 kg, 5-50 kg, or 5-25, 2-25, or 10-20 kg dry ice, preferably wherein at least 50, 75, 90, or 100% of the outer surface of the dry ice has a temperature of between -75 and -80 °C, preferably -78.5 °C. Additionally or alternatively, the at least one slow release compartment typically comprises between 10-500, 20-200, 10-50, 25-35 kg of dry ice, preferably wherein at least 50, 75, 90, or 100% of the outer surface of the dry ice has a temperature of between -75 and -80 °C, preferably -78.5 °C.

CO2 release from the two compartments according to the present disclosure is preferably uncontrolled, resulting in a modified atmosphere in the container. CO2 concentrations in the internal atmosphere may exceed the target value of e.g. 12%. In order to maintain a gaseous CO2 level in a container according to the present disclosure below a certain maximum level, e.g. below 90, 85, 80, 75, 70, 60, 50, 45, 40, 35, 30, 25, 20, 15, 14, 13, 12, 11, 10, 9, 8, 6, 5 vol.%, or between 70-90, 5-50, 5-40, 10-15, 5-15 vol.%, the container may comprise a gaseous CO2 monitor and/or a controlled gaseous CO2 extraction system (or outlet), preferably configured to release gaseous CO2from the container when the gaseous CO2 concentration in the container exceeds a gaseous CO2 threshold level set between 2-90 vol.%, preferably between 5-50, more preferably between 10-30 vol.%. The gaseous CO2

-5extraction system may be a fresh air exchange vent. The container does not have to be fully sealed from the outside atmosphere, and a certain degree of air exchange with the outside atmosphere is foreseen.

In a particularly preferred embodiment, the container according to the present disclosure comprises perishable goods, preferably chosen from the group consisting of vegetables, fruit, meat and/or fish, more preferably chosen from the group consisting of grapes, blueberries, redcurrants, lamb, beef, veal, pork, tuna and salmon.

The skilled person will understand that CO2 release rate from the slow and/or fast release compartment, but particularly of the slow release compartment, may be adjusted (e.g. downregulated) proportional to air leakage rate of the container, and/or CO2 production rate of the perishable goods in the container. For example, additional insulation may be applied to lower the heat leakage rate of the slow release compartment, e.g. in applications where the air leakage is less or the CO2 production rate higher.

The present disclosure also provides for a system which can be used e.g. for achieving and/or maintaining an elevated CO2 level, wherein the use may be in a confined space (having a volume of e.g. between 10 - 200 m³, preferably between 50-150 m³, more preferably between 50-100, or 60-90, 75-85 m³), preferably in a container for transporting and/or storing perishable goods, and wherein the device comprises the at least one fast release compartment comprising dry ice and the at least one slow release compartment comprising dry ice as disclosed herein.

Additionally, the present disclosure also provides for a method of modifying or controlling an atmosphere in a confined space or container according to the present disclosure, comprising combining the confined space or container with the at least one fast release compartment comprising dry ice as disclosed herein, and the at least one slow release compartment as disclosed herein.

Preferably, in the method, the atmosphere in the confined space or container is modified over a period of at least 2, 4, 6, 8, 10, 12, 14, 20, 30, 40, 50, or 60 days.

The present disclosure and specifically the method as described above find particular use in controlling bacteria, fungi and/or insects.

-6In this document and in its claims, the verb to comprise and its conjugations is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. In addition, reference to an element by the indefinite article a or an does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements. The indefinite article a or an thus usually means at least one.

Methods of carrying out the conventional techniques used in methods of the present invention will be evident to the skilled worker.

Claims

CLAUSES

1/6

Figure 1

1. Container for transporting and / or storing goods with limited shelf life, in combination with:

- at least one quick release compartment comprising dry ice, wherein the at least one quick release compartment has a heat leak rate of at least 5 W / ° C; and

at least one slow release compartment comprising dry ice, wherein the at least one slow release compartment has a heat leak rate of between 0.05-5 W / ° C.

1) Duration till CO ₂ reaches 12% for the first time: 1.1 days (see Fig. 4). Apparently the fast release rate of the dry ice poured on top of the slow release box is a lot faster than in experiment 1, where it was left in a small insulated box without a member.

1) Duration till CO2 reaches 12% for the first time: 2.8 days (see Fig. 2). Two ways to accelerated this:

a. A more thorough removal of insulation from the small insulated box would be just to pour out the contents of the box on the T-bar at the door-end. That will certainly yield a faster atmosphere build-up.

b. The experiment was in an empty container. A stuffed container contains much less air. Hence CO2 is expected to rise faster.

1. Container for transporting and / or perishable goods, in combination with:

- at least one fast release compartment including dry ice, at least one fast release compartment has a heat leakage rate or at least 5 W / ° C; and

- at least one slow release compartment including dry ice, at least one slow release compartment has a heat leakage rate of between 0.05-5 W / ° C.

2/6

Figure 2

ΟΎΛ

[%] ZOO time (days since experiment start]

Container for transporting and / or storing goods with limited shelf life according to claim 1, wherein the at least one rapid-release compartment allows the delivery of gaseous CO2 at a speed of at least 500 g of gaseous CO2 per hour.

2) A sharp inflection point in the dry ice weight curve (Fig. 5) occurs around day 14. This coincides with the moment the CO ₂ concentration starts to decline (Fig. 4). That clearly is the moment when all dry ice has sublimated.

2). Most likely this is due to offsets in the CO2 sensors.

6) Extrapolation of the recorded dry ice weight recordings since day 6 (Fig. 3) indicate that all dry ice had sublimated on day 14. This coincides with an inflection point in the CO2

- readings recorded by the reefer unit (Fig. 2). Apparently, at least after day 6, a less insulated box (Ubox larger) can be beneficial to maintain CO2 at 12%.

Based on this last observations it was decided to repeat the experiment with a larger value for Ubox. The optimal Ubox, at least for that period, is calculated below.

Step 1. Both on day 6 and 8 xcoz was around 10.5%. Hence in that period + was close to optimal. In that period the mass of dry ice declined from 23.3 to

16.4 kg. The actual rate of CO2 release in that period + '(t) was:

+ = ^{s5 * - ^a6 ^ = G.15 [kg.h ' ¹ ] (10)

Because of the weak inflection point in the dry ice weight curve (Fig. 3) around day 6 may have been larger than 0 during a part of the period. Therefore is assessed from a period where is certainly 0 kg / h: day 7 till 12.2.

Step 2. From day 7 to 12.2 the dry ice weight decays linearly (Fig. 3) and = 0.

Hence can be calculated from the weight measurements:

= =. Q.12 [kg.h-η (11)

Step 3. take the value for calculated above and input it in eqn. 8 to calculate the apparent value for Ubox between days 7 and 12.2:

----- = Ö.24

C - 78 [W / ° C] (12)

A priori it was calculated that Ubox = 0.34 W / ° C would suffice to achieve = 0.17 kg / h, which would suffice to maintain xco2 = 12%. The data show that = 0.15 kg / h suffices to maintain xco2 = 10.5%, thus confirming that = 0.17 kg / h would indeed suffice to maintain xco2 = 12%, and hence the target value = 0.34 W / ° C is good.

Step 4. Anticipating the difference between calculated Ubox (0.34 W / ° C) and apparent Ubox (0.24 W / ° C), it was decided to aim for:

34.34 x - = .47 [W / ° C] (13)

Step 5. Using eqn. 9 the dimensions of the large insulated box are redesigned. See Table 5.

- 16 Experiment 2: materials and methods

Only the experimental parameters that differ from experiment 1 are listed.

The fast release portion was now poured out on top of the large heavily insulated carton

2) One would expect a sharp inflection point in the recorded dry ice weight (Fig. 3) when (t) reaches 0 kg. That sharp inflection point does not occur. A weak inflection seems to occur around day 6 (Fig. 3), which more or less coincides with the moment when the CO2 concentration starts to decline (Fig. 2).

2. Container for transporting and / or perishable goods failure according to claim 1, which is the least one fast release compartment allows release of gaseous CO2 by a rate or at least 500 g of gaseous CO2 per hour.

3/6

Figure 3 amount of dry ice [kg

Doretfen [days]

Container for transporting and / or storing goods with limited shelf life according to one of the preceding claims, wherein the at least one slow-release compartment allows the delivery of gaseous CO2 at a speed of between 1 - 500 g of gaseous CO2 per hour .

3) Throughout the experiment there are 34 sharp drops in CO ₂ concentration (Fig. 4). That's because in that period the CCL-regulated car opens the fresh air inlet 34 times.

3) Between day 3 and 6 there are 9 sharp drops in CO2 concentration (Fig. 2). That's because in that period the CO2 regulated car opens the fresh air inlet 9 times.

3. Container for transporting and / or perishable goods failure according to any of the previous claims, including the least one slow release compartment allows release of gaseous CO2 by a rate of between 1 - 500 g of gaseous CO2 per hour.

4/6

Figure 4

time [days smce experiment start}

Container for transporting and / or storing goods with limited shelf life according to one of the preceding claims, wherein the at least one rapid-release compartment comprises between 10 and 100 kg dry ice, preferably wherein the outer surface of the dry ice has a temperature of between -75 and -80 ° C.

4) From day 1 to 14 CO2, measured by the reefer unit, is maintained between 11.6 and 12.4%, with an average of 12.0%. Apparently the change in set point from 12.0% in experiment 1 to 12.4% in experiment 2 is effective in raising the average CO2 concentration to 12.0%.

4) From day 3 to 6 CO2, measured by the reefer unit, is maintained between 11.2 and

12%. This is because the CC> 2-regulated autovent system does not regulate CO2 around, but just below, 12%. To maintain measured CO2 around 12% it can be set e.g. at 12.4%.

4. Container for transporting and / or perishable goods failure according to any of the previous claims, including the at least one fast release compartment comprising between ID100 kg of dry ice, preferably regarding the outer surface of the dry ice has a temperature of between -75 and -80 ° C.

5/6

Figure 5 amount of dry ice

time sfoee start or experiment [days]

At least one rapid release compartment has a heat leak rate of at least 5 W / ° C; and

A method for modifying an atmosphere in a defined space according to claim 13, wherein the atmosphere in the transport container is modified for a period of at least 2, 4, 6, 8, 10, 12, 14, 20 or 30 days.

15. A method according to any one of claims 13-14, wherein the method is for suppressing the growth of bacteria, fungi and / or insects.

Container for transporting and / or storing goods with limited shelf life according to one of the preceding claims, wherein the at least one slow-release compartment comprises between 20-200 kg dry ice, preferably wherein the outer surface of the dry ice has a temperature of between -75 and -80 ° C.

Container for transporting and / or storing goods with limited shelf life according to one of the preceding claims, wherein the quick-release compartment is a platform, or a container, wherein the container preferably has an opening of at least 100, 200, 500 or 1000 cm ² allowing the release of gaseous CO2 from the rapid release compartment.

Container for transporting and / or storing goods with limited shelf life according to one of the preceding claims, wherein the slow-release compartment is an insulated container, preferably made of material comprising at least 80% by weight of extruded closed-cell polystyrene foam. .

Container for transporting and / or storing limited-shelf goods according to one of the preceding claims, wherein the container for transporting and / or storing limited-shelf goods comprises a monitor for gaseous CO2 and / or a controlled gaseous CO2 extraction system , preferably configured to release gaseous CO2 from the container when the gaseous CO2 concentration in the container exceeds a gaseous CO2 threshold level set between 2-90 vol.%, preferably between 5-50, more preferably between 10-20 full.%.

Container for transporting and / or storing goods with limited shelf life according to one of the preceding claims, wherein the container has an internal volume of between 10 - 200 m ³ , preferably between 50 - 150 m ³ and / or internal volume of the transport container has an average temperature of between -5 and 15 ° C, preferably between -5 and 10 ° C, more preferably between -2 and 2 ° C.

Container for transporting and / or storing goods with limited shelf life according to one of the preceding claims, wherein the container comprises goods with limited shelf life, preferably selected from the group consisting of vegetables, fruit, meat and / or fish.

11. Use of a system for achieving and / or maintaining an increased CO2 level, the system comprising:

Use according to claim 11, wherein the use is in a delimited space, preferably in a container for transporting and / or storing goods with limited shelf life.

A method for modifying an atmosphere in a defined space, preferably a container for transporting and / or storing goods with limited shelf life, comprising combining the defined space with

at least one quick release compartment comprising dry ice, wherein the at

5) Like in experiment 1 there is an offset between the Dance sensor and the reefer unit's CO ₂ recording (Fig. 4).

6) The CO2 concentration only started to drop after all dry ice had sublimated. Hence the results show that the rate of CO ₂ release from the slow-release portion of dry ice, sufficed to maintain CO ₂ at 12% till all dry ice had sublimated. Apparently, the less insulated box used in experiment 2 solved the issues of decreasing CO ₂ since day 6 in experiment 1 (compare Fig. 4 to Fig. 2).

7) FIG. 6 reveals a strong stratification in air temperature inside the slow-release box, which grew bigger over time. Dry ice is -78 ° C, so the unmeasured temperature on the floor of the slow-release box was -78 ° C till all dry ice sublimated. The temperature of the inside of the member gradually rose during the test. The initial rise until about day 2 was relatively fast, because in that period the fast-release portion on top of the member and hence the outside temperature of the member rose. Then there was a linear rise from approx. -60 ° C on day 2 till -40 ° C on day 14. When on approx, day 14 all dry ice had sublimated the temperature inside the box converged to the temperature outside the box.

8) From the CO ₂ recordings since day 14 the container air leakage rate can be estimated.

References

Artés-Hernandez F., E. Aguayo, F. Artés (2004). Alternative atmosphere treatments for keeping quality or "Autumn seedless" table grapes during long-term cold storage. Postharvest Biology and Technology, 31, pp. 59-67.

Chervin, C., Aked, J. and Crisosto, C. H. (2012) Grapes, in Crop Post-Harvest: Science and Technology (ed. D. Rees, G. Farrell and J. Orchard), Wiley-Blackwell, Oxford, UK. doi: 10,1002 / 9781444354652.ch9.

- 18 Crisosto C.H., D. Garner, G. Crisosto (2002a). Carbon dioxide-enriched atmospheres during cold storage limit losses from Botrytis but accelerate rachis browning or "Red globe" table grapes. Postharvest Biology and Technology, 26, pp. 181-189.

Crisosto C.H., D. Garner, G. Crisosto (2002b). High carbon dioxide atmospheres affect stored "Thompson Seedless" table grapes. HortScience, 37 (7), pp. 1074-1078.

Lighter A., Y. Zutahy, T. Kaplunov, S. Lurie. Evaluation of table grape storage in boxes with sulfur dioxide-releasing pads with Either an internal plastic liner or external wrap. HorTechnology, 18 (2), pp. 206-214.

Retamales J., B.G. Defilippi, M. Arias, P. Castillo, D. Manriquez (2003). High-CO2 controlled atmospheres reduce decay incidence in Thompson Seedles and Red Globe table grapes. Postharvest Biology and Technology, 29, pp. 177-182.

Rosales R., C. Fernandez-Caballero, I. Romero, Μ. I. Escribano, C. Merodio, Μ. T. SanchezBallesta (2013). Molecular analysis of the improvement in rachis quality by high CO2 levels in table grapes stored at low temperature. Postharvest Biology and Technology. 77, pp. 50-58.

Teles C. S., B. C. Benedetti, W. D. Gubler, C.H. Crisosto (2014). Prestorage application of high carbon dioxide combined with controlled atmosphere storage as a dual approach to control Botrytis cinerea in organic "Flame Seedless" and "Crimson Seedless" table grapes. Postharvest Biology and Technology, 89, pp. 32-39.

- 19 Conclusions

5 containing two small dry ice cartons, and placed together on a scale at the container's door-end.

A temperature logger is taped to the member inside one of the boxes containing the slow release portion of dry ice. The aim of this logger is to gain insight into the possible vertical stratification 10 or air temperature inside the boxes.

Table 5, specifications of large external EPS box, containing two small boxes with dry ice.

Parameter Value external dimensions L x W x H = 900 x 500 x 500 mm internal dimensions L x W x H = 800 x 400 x 400 mm thickness of floor and member 50 mm thickness or long side walls 50 mm thickness or short side walls 50 mm Calculated U-value or large box + small box inside 0.46 W. ° C ^-1 "IM 16 kg 50 kg

15 Table 6, test conditions.

Parameter I Value atmosphere control method CC> 2-regulated autovent @ CO2 set = 12.4%

Experiment 2: results

FIG. 4 presents the CO2 concentrations recorded by the Dance sensor, and the reefer unit's CO2 sensor. The recorded dry ice mass is presented in Fig. 5.

Experiment 2: discussion

Some observations in the recordings for CO2 and dry ice mass:

5) There is an offset between the Dance sensors and the reefer units CO2 recording (Fig.

5 Table 3, specifications of large external EPS box, containing two small boxes with dry ice: the slow release compartment.

Parameter Value external dimensions LxWxH = 1000 x 500 x 700 mm internal dimensions L x W x H = 800 x 400 x 400 mm thickness of floor and member 150 mm thickness or long side walls 50 mm thickness or short side walls 100 mm Specified thermal resistance or 50 mm thick panels from which it is built up 1.30 m ^2. ° C / W (ie λ = 0.039 W.mTX ' ¹ ) Calculated U-value or large box 0.64 W. ° C ^-1 Calculated U-value or large box + small box inside 0.34 W. ° C ^-1

The calculate U-value Ubox or the large box + the small box inside is 0.34 W. ° C ' ¹ , exactly equal to the theoretical target value for Ubox (eqn. 8).

10 Table 4 test conditions.

Parameter Value Tset 0.0 ° C Text 15 ~ 30 ° C (uncontrolled, truly ambient) fresh air exchange closed atmosphere control method CO ₂ -regulated autovent @ CO2 set = 12% CA door curtain installed? yes drain holes closed power supply 400 V / 50 Hz log interval or dry ice weight 5 min log interval or Dance sensor CO ₂ measurement 7 min log interval or reefer unit datalog 15 min

CO ₂ logger PBI Dance sensor Checkmate II scale Mettler Toledo 0805 ί-ϊ-ίέ »ƒ sSSf '···. 21 kg Go) 43 kg

Experiment 1: results

FIG. 2 presents the CO2 concentrations recorded by the Dance sensor, and the reefer unit's CO2 sensor. The recorded dry ice mass is presented in Fig. 3. The recording of the Dance sensor and the scale was stopped around day 12, about two days before all dry ice had sublimated. The recording of CO2 by the reefer unit continued until the end of the experiment on day 17.

Experiment 1: discussion

Some observations in the recordings for CO2 and dry ice mass:

5 scale recorded the weight of dry ice + packaging at a 5 minute log interval. A Dance sensor (CheckMate II 02 (Zr) 002-100%) logged the CO2 concentration inside the container at a 7 minute log interval. The Dansensor was placed outside the container and sampled the atmosphere through a small air sampling tube.

The purchased amount of dry ice was 70 kg, it was delivered in three normally insulated

10 small EPS boxes (Table 2) or equal weight. Before the start of the experiment already had 6 kg of sublimated, leaving 64 kg of dry ice at the start of the experiment. At the start of the experiment two small boxes, containing together 43 kg or dry ice = 43 kg, were placed in a heavily insulated large box: the slow release portion. The large insulated box was tailor-made from 5 cm thick EPS foam panels purchased from the local lumberyard

15 (Table 3). The third normally insulated small box was then placed on top of this large box = 21 kg, and its member was removed: the fast release portion. Together this was all placed on a scale in the container. A door curtain for controlled atmosphere was installed before closing the container for a closed atmosphere inside the container. See Table 4 for a further specification of test conditions.

Table 2, specifications of small internal EPS box, containing dry ice.

Parameter I Value external dimensions L x W x H = 380 x 380 x 380 mm internal dimensions Lx Wx H = 310x310x310 mm

thickness of all sides 35 mm Specified thermal resistance unknown, assumed λ = 0.039 W.m ' ^1. ° C' ¹ , though probably a bit lower. Calculated U-value or small box 0.44 W. ° C ^-1

The calculated U-value in both Table 2 and Table 3 assumes an air-to-wall heat transfer coefficient a = 5 W.nr ^2. ° C ' ¹ on all sides of the boxes, both internally and externally.

5. Container for transporting and / or perishable goods failure according to any of the previous claims, including the at least one slow release compartment comprising between 20200 kg of dry ice, preferably regarding the outer surface of the dry ice has a temperature of between -75 and -80 ° C.

6. Container for transporting and / or perishable goods failure according to any of the previous claims, the fast release compartment being a platform or container

-7 container preferably has an opening or at least 100, 200, 500, or 1000 cm ² allowing release or gaseous CO2from the fast release compartment.

7. Container for transporting and / or perishable goods failure according to any of the previous claims, the slow release compartment being an insulated container preferably made of material including at least 80 wt.% Closed-cell extruded polystyrene foam.

8. Container for transporting and / or failing perishable goods according to any of the previous claims, including the container for transporting and / or failing perishable goods comprising a gaseous CO2 monitor and / or a controlled gaseous CO2 extraction system, preferably configured to release gaseous CO2from the container when the gaseous CO2 concentration in the container exceeds a gaseous CO2 threshold level set between 2-90 vol.%, preferably between 5-50, more preferably between 10-20 vol.%.

9. Container for transporting and / or perishable goods failure according to any of the previous claims, whether the container has an internal volume of between 10 - 200 m ³ , preferably between 50-150 m ³ and / or concerning the internal volume or the transport container has an average temperature of between -5 and 15 ° C, preferably between -5 and 10 ° C, more preferably between -2 and 2 ° C.

10. Container for transporting and / or perishable goods failure according to any of the previous claims, including the perishable goods container, preferably chosen from the group consisting of vegetables, fruit, meat and / or fish.

11. Use of a system for achieving and / or maintaining an elevated CO2 level, considering the system comprises

- at least one slow release compartment including dry ice, at least one slow release compartment has a heat leakage rate of between 0.05-5 WI ° C.

12. Use according to clause 11, where the use is in confined space, preferably in a container for transporting and / or perishable goods.

13. Method of modifying an atmosphere in confined space, preferably a container for transporting and / or disturbing perishable goods, including combining the confined space with

14. Method of modifying an atmosphere in a confined space according to claim 13, where the atmosphere is modified over a period or at least 2, 4, 6, 8, 10, 12, 14, 20, or 30 days.

15. Method according to any one of claims 13-14, the method is for suppressing the growth of bacteria, fungi and / or insects.

Brief description of the figures

FIG. 1: schematic drawing of slow and fast release compartments including dry ice in a reefer container (scale is only there in experimental set-up).

FIG. 2: CO2 recorded by Dance sensor and by unit sensor for Experiment 1.

FIG. 3: weight of remaining dry ice in Experiment 1.

FIG. 4: CO2 recorded by Dance sensor and by unit sensor for Experiment 2.

FIG. 5: weight of remaining dry ice in Experiment 2.

FIG. 6: Figure 6 shows that by using a slow and fast release compartment as according to the present disclosure, a CO2 profile can be achieved which is closer to the desired CO2 level during the entire transport and particularly during the first days thereof, in comparison to prior art methods using only an insulated box for slow release or CO2.

Example section

The following illustrates different numbers of the present disclosure.

An embodiment of the present disclosure is described with reference to Figs. 1, depicting the experimental system. To rapidly build-up an atmosphere with 12% CO2 after closing the doors of a reefer container with an amount of 3η ““ ζ ^{ίΑ / Οϊί} (ί.β) or dry ice is placed in the container without any insulation: the fast-release portion or dry ice.

To maintain the atmosphere at 12% an amount (t _s ) or dry ice is placed in the container in a heavily insulated box: the slow-release portion of dry ice. The insulation value Ubox or the box is designed such that the release rate of gaseous CO2 from the box equals 120% of the anticipated loss or gaseous CO2 from the container due to container air leakage, minus the anticipated CO2 production rate by the cargo.

-9Ever more reefer containers are equipped with CC> 2-regulated autovents. In CC> 2-regulated autovents a CO2 sensor measures CO2 in the container atmosphere, and relays the reading to a controller. When the measured CO2 exceeds the CO2 set point (CO2 set) the controller opens the ventilation, and closes it again when measured that CO2 drops below CO2 set 0.8%. To avoid CO2 concentrations higher than intended the reefer units CCU regulated autovent regulates CO2 to 12%.

The parameters? N ^ ^sAjFasf (ta), (te) and Ubox are calculated in relation to the CO2 mass balance over a container:

See Table 1 for the nomenclature. In the above equation 0.34, a conversion factor from respiratory heat production is _reS p in W / tonne to CO2 production rate in [(mg CC> 2) / (kg prod.). H].

The mass is the amount of dry ice needed to raise from the initial to the target value of 12%:

1C-G,

---- = lb.4 [kg] (2)

The rate at which this mass sublimates should be as high as possible, hence it can be placed inside the container without any insulation around it.

In the maintenance phase, after completion of the initial rise to 12%, the CO2 production rate should balance the loss or CO2 due to air leakage minus the possible respiratory CO2 production, i.e.

= x [( ^k 9 CO ₂ ). h ^-1 ] (3)

For assumed values of m _prod and r _resp , solving the above equation for the target value ' ^or ' ^{n an em} Pty container yields:

= 0.7 xx 1.98 = 0.17 [kg.h ' ¹ ] (4)

- 10Once the required production rate is known the required initial mass follows from _{= χ 24 χ [kg] (5)}

For a 12 day shipment this is = ^{12 x} 24 X 0.17 = 48 [kg] (6)

To control the slow-release production rate the initial mass can be packed in an insulated box with heat leakage Ubox. At atmospheric pressure CO2 has a sublimation point of -78.5 ° C, then during sublimation the dry ice temperature Tdryjce inside the box is -78.5 ° C. In this specific case the set temperature T _se t of the container is 0 ° C. The required box heat transfer coefficient Ubox * is the only unknown in - iff:

[W] (7) and hence

G.1? XS71X ^ - ___________ g-fgff - Q

G-72 [W / ° C] (8)

The U-value of a box follows from its dimensions, and the heat conduction coefficient Abox or the material or which it's made:

₌ X _Li _ X [W / ° C] (9)

Obviously the box's internal length, width and height must suffice to contain which leaves Abox and the 6 wall thicknesses as design parameters.

Table 1, nomenclature

symbol description | unit value [unit] PCO2 density of gaseous CO2 @ 0 ° C and ambient pressure | kg / m ³ 1.98 . ss-rsdï¿½ · ££ fast-release CO2 production rate kg / h m '. t-Ul slow-release CO2 production rate kg / h £ ambient CO2 % 0.04

concentration i id..ƒ ast mass or fast-release portion or dry ice at time t kg mass or slow-release portion or dry ice at time t kg air leakage rate m ³ / h d _s thickness or box side s m Hey internal height container m 2.60 L _c internal length container m 11.59 Ldryjce latent heat or sublimation or dry ice kJ / kg 571 L _s length or box side s m mfruit mass or fruit in container tonne 0 Tresp respiration rate of the carried fruit W / tonne to initial time h 0 T dryjee temperature of sublimating dry ice ° C -78.5 tfinal final time till which CO2 is maintained at 12% days T set container set temperature ° C 0 Ubox heat leakage rate of the box containing the slow-release portion of dry ice W / ° C Vair air volume inside container m ³ V _c internal volume m ³ 69

container WC internal width container m 2.29 Ws width or box side s m XCO2 CO2 concentration in container % Xbox heat conduction coefficient or box ’wall material Wm ^-1 ° C ^-1

Experiment 1: materials and methods

Experiment 1 was performed in ambient conditions. In this first experiment, dry ice was placed on a scale in a 40 ft. HC reefer container equipped with a CO2 regulated car oven. The

6/6

Figure 6