Conservation insulated container and/or transportation of perishable or heat sensitive products

Abstract

An isothermal container for preserving and/or transporting perishable or heat-sensitive products, includes a cryogenic compartment for a mass of a cryogenic fluid, a product storage compartment for the products to be preserved or transported, at least one Seebeck module, and at least one fan positioned within the product compartment to create forced convention therein that is electrically powered by the Seebeck module, which generates a voltage from the difference in temperature between the mass of cryogen and the ambient air temperature of the product compartment.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. § 119 (a) and (b) to French patent application No. FR 1761996, filed Dec. 12, 2017, the entire contents of which are incorporated herein by reference.

BACKGROUND

Field of the Invention

The invention relates to the field of transporting or distributing perishable foodstuffs and other cooked meals or food in isothermal containers, and that of heat-sensitive products (drugs, vaccines, etc.), whether this for example be, in the case of containers or trucks, where maintaining the cold chain is ensured through the intervention of a refrigerant (cold gas, cryogenic liquid such as liquid nitrogen, dry ice, etc.).

Thus, by way of example, central kitchens or alternatively distribution centers use isothermal trolleys to transport and distribute cooked meals or food from their kitchens or platforms to the site(s) of consumption: hospital catering, company canteens, school canteens, etc.

RELATED ART

The very numerous configurations of container and of types of cooling available on the market, particularly the types of isothermal container/trolley with or without physical cryogenic compartment, with or without a reservoir (“cassette”) containing the cold fluid to be inserted into the container, etc. will not be detailed exhaustively here.

Likewise, the refrigerant (gas, cryogenic liquid, solid, whether this be nitrogen, CO₂ or something else) may be placed directly in the container or in a reservoir to be inserted inside the container, or sent into an exchanger situated in the container, or alternatively still, and again by way of illustration, sent into a capacity situated in the container itself or nearby (or alternatively affixed, for example when the container is a truck), from which capacity fluid is drawn and sent to the container, to a reservoir situated in the container, or to an exchanger situated in the container, etc.

It can be seen from reading the foregoing that the situations and configurations are highly varied.

By way of illustration however, it may be pointed out that the cryogenic trolleys/containers are very often parallelepipedal in shape, they very often comprise a cryogenic compartment arranged in the upper part of the container, above the storage compartment in which the products that are to be kept at a controlled temperature are placed and, traditionally, this upper compartment houses a reservoir intended to contain a refrigerant, for example carbon dioxide in the solid phase, the sublimation of which releases cold gases to compensate for the ingress of heat through the joints between the container and its door or else through the insulating walls of the container. The cooked meals (or other perishable products) are then housed in the product storage compartment of these isothermal containers, which are themselves transported in trucks to the user site (hospital, school canteen, office canteen, etc.).

Cooling occurs by contact between the air and the lower cold plate of the cryogenic compartment or through the fact that the lower face of the compartment is “holed” in order to allow cold gas to pass toward the product compartment.

Depending on the version, the cryogenic compartment comprises a heat screen affording protection to the stored foodstuffs.

The phases of operation of such containers are generally as follows:

1—When the refrigeration system is started up after filling (for example at the start of a round or alternatively after a door has been opened), a mode is adopted in which the temperature is rapidly lowered (this being known in the industry as the “pull-down” phase).

2—Once the reference temperature has been reached in the product storage chamber, a control/regulation mode is adopted that allows the temperature in the product storage chamber to be kept at a reference value (this phase traditionally being known as the “maintain” phase).

It is well known that the legislation currently in force regarding compliance with the cold chain when transporting perishable foodstuffs is becoming increasingly strict and notably leading those involved with such food product distribution to make changes in terms of preparation and in terms of the traceability of the products that are to be transported.

Experiments successfully conducted by the applicant company have revealed:

on the one hand, that the pull-down times for such containers or trolleys, after filling with cryogen, are particularly lengthy, often lasting several hours, and

on the other hand, that exchanges of heat in such systems are far from being optimized.

SUMMARY OF THE INVENTION

It is then one of the objectives of the present invention to propose a solution to the problems listed hereinabove.

As will be seen in greater detail in what follows, the present invention therefore proposes implementing the following means:

• • the use of one (or more) fan(s) which will create forced convection in the product compartment, this fan preferably being operated only during the “pull-down” phases;
  • the use of one (or more) “Seebeck” module(s) exploiting the difference in temperature between the cryogen (for example −80° C. in the case of dry ice) and the initial ambient temperature in the air of the trolley when the cooling process began, making it possible to generate a voltage, which is of particular benefit in electrically powering the fan or fans in question. Experiments conducted by the applicant company have demonstrated that the fan or fans generally switch themselves off as soon as the voltage generated is no longer sufficient to operate this (these) fans, something which generally is the case at the end of the “pull-down”.

It will be appreciated in fact that as the ambient temperature in the product compartment reduces (“pulls down”), so the temperature gradient decreases, resulting in a drop in the amount of voltage generated, something that will progressively cause the fan(s) to come to a standstill naturally and therefore allow autonomous control of the ventilation.

It will therefore be appreciated that, in some instances, the fan(s) may stop before the end of the pull-down phase. The phase then continues without the aid of the forced convection, but by natural convection, therefore somewhat like in the prior art, i.e. through exchange between the cooled air near the cold plate which forms the bottom of the cryogenic compartment, and the air further away in the product compartment.

According to one of the advantageous implementations of the invention, the trolley is fitted with means that allow a radiative effect to be installed in the product compartment, for example via the presence of metallic plates or of a low-emissivity coating (paint, etc.) on all or part of the vertical walls of the trolley, which radiation is of particular benefit during the “maintain” phase.

According to one of the implementations of the invention, the “Seebeck” effect is obtained by employing:

a “cold” side which is a metallic surface (for example made of copper, of aluminum, or else of stainless steel) in contact with the cold source (i.e. the addition of cryogen) for example with the cold plate which forms the bottom of the cryogenic compartment or one of the lateral surfaces thereof; and

a “hot” side which is embodied by the temperature of the product compartment, which temperature is preferably maintained by dissipating cold using a radiator by exchange with the air prevailing in the product compartment.

Further features and advantages will become apparent from the following description, given solely by way of example and made with reference to FIGS. 1 and 2, which provide schematic depictions of one embodiment of the invention.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic view of a container for preserving and/or transporting perishable products.

FIG. 2 is a partial schematic view of the container of FIG. 1 that also illustrates the location of a Seebeck module used to power a fan.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 depicts an overall diagram of a container 1 preserving and/or transporting perishable products (of parallelepipedal conventional structure equipped with an access and loading door, not visible in this highly schematic figure), of the type comprising a cryogenic compartment 2 able to receive a mass of a cryogenic fluid, for example of dry ice, and a product storage compartment 3 for the products to be preserved or transported, situated in the bottom part of the container, where cooling takes place by contact between the air of the product compartment and the cold plate (10 in FIG. 2) that constitutes the lower part of the cryogenic compartment.

This figure indicates the location of a “Seebeck” module 4 which will be detailed in the context of FIG. 2.

Note that this FIG. 2 is a schematic diagram providing detail and a better understanding of one of the implementations of the invention; it is not drawn to scale and is a kind of zoom in on the “Seebeck” part quite simply permitting a better understanding of this part.

This FIG. 2 shows the cold plate 10 that constitutes the lower part of the cryogenic compartment 2, in contact with which is positioned the “Seebeck” module 4, the two connectors of which are connected to the fan 5.

The detailed view in the left-hand part of FIG. 2 shows one example of a standard Seebeck module that can be used.

It is also possible to note the presence of a radiator 6, for dissipating cold and thus lowering and/or maintaining a temperature in the product compartment.

The experiments successfully conducted by the applicant company demonstrated that a container according to the invention, combining the presence of the fan and of the radiative heat transfer, allowed the following results to be obtained:

an approximately +17% increase in the pull-down speed of the product compartment after the loading of the cryogen

an approximately 45 min reduction in the duration of the “pull-down” phase

in terms of the maintain phase, an approximately +58% increase in the duration of this phase (therefore in the temperature stability around the desired set point)

an at least 22% overall reduction in dry ice consumption for a 58% improvement in maintain performance as signaled hereinabove.

This lower mass of cryogen carried furthermore makes it possible to increase the transported payload accordingly, and has a direct beneficial effect on the cost of the technical solution proposed here.

While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description, Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.

The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.

“Comprising” in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing i.e. anything else may be additionally included and remain within the scope of “comprising.” “Comprising” is defined herein as necessarily encompassing the more limited transitional terms “consisting essentially of” and “consisting of”; “comprising” may therefore be replaced by “consisting essentially of” or “consisting of” and remain within the expressly defined scope of “comprising”.

“Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.

Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.

Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.

All references identified herein are each hereby incorporated by reference into this application in their entireties, as well as for the specific information for which each is cited.

Claims

1-6. (canceled)

7. An isothermal container for preserving and/or transporting perishable or heat-sensitive products, comprising

a cryogenic compartment adapted and configured to accept a mass of a cryogen comprising lateral surfaces and a lower part that comprises a cold plate;

a product storage compartment adapted and configured to store perishable or heat-sensitive products, wherein cooling of the products takes place through contact between the cold plate and air from the product compartment;

at least one Seebeck module adapted and configured to generate a voltage from the difference in temperature between the mass of cryogen and an ambient temperature of air in the product compartment through the Seebeck effect; and

at least one fan positioned within the product compartment that is adapted and configured to create forced convection in the product compartment and to be electrically powered by the voltage generated by the at least one Seebeck module.

8. The container of claim 7, wherein each of the at least one Seebeck module has:

a cold side comprising a metallic surface that is in thermal contact with the cryogenic mass via the cold plate or one of the lateral surfaces; and

a hot side in contact with the air in the product compartment.

9. The container of claim 7, further comprising a radiator within the product compartment that is adapted and configured to dissipate coldness thereby allowing a temperature in the product compartment to be lowered and/or maintained.

10. The container of claim 7, wherein the cryogenic compartment further comprises a cryogenic reservoir that is adapted and configured to be filled with the mass of cryogen.

11. The container of claim 7, wherein all of part of vertical walls of the container are provided with metallic plates or a low-emissivity coating for allowing a radiative effect to be set in place within the product compartment.

12. The container of claim 7, wherein the cryogenic fluid is dry ice.

13. A method of preserving and/or transporting perishable or heat-sensitive products, comprising the steps of:

providing the isothermal container of claim 7; and

cooling perishable or heat-sensitive products through contact between the cold plate and air from the product compartment.

14. The method of claim 13, further comprising the step of transporting the products while stored in the isothermal container.

15. The method of claim 13, wherein the cryogenic fluid is dry ice.

16. The container of claim 13, wherein the at least one fan is used only during a pull-down phase in which a temperature within the product compartment is quickly lowered.