EP0337860B1 - Isothermal container with refrigerant tank and application to fresh product transport - Google Patents

Description

The present invention relates to an insulated container, in particular an itinerant trolley intended for the transport of fresh products, of the type with insulated walls defining an interior space divided horizontally by a screen, in an upper zone receiving an open reservoir of a subliming refrigerant product, and a lower zone receiving at least one compartment of products to be kept cold, the upper and lower zones being accessible by access means arranged on the same side of the container, a space being provided between the coolant reservoir and the screen.

Document FR-A-2,178,437 describes a drink car of the above type comprising an upper drawer for coolant and at least one lower drink drawer, the drawers being supported on slides mounted on the flat interior walls of the container , the screen being constituted by a metal separating sheet extending between the slides of the upper drawer and simply allowing a downward exhaust, forward and backward, of CO₂ gaseous cold.

Document US-A-1,997,936 further describes a container for bulk products with a closed chamber of refrigerant disposed in a housing made of porous or perforated insulating material.

The Applicant has demonstrated that in order to be able to perform, for example, long-term transport (30 hours) at low temperatures, close to 0 ° C., but without freezing the products, taking into account the doses of solid CO₂ to be used. work, various adjustments to the containers of the type defined above were necessary.

An object of the present invention is to provide an insulated container, in particular an itinerant trolley, of simple and reliable design, easy to use and allowing long-term storage of fresh products without risk of local freezing or heating of these products.

To do this, according to a characteristic of the invention, the screen is made of thermally insulating material and has dimensions slightly smaller than the internal section of the container to leave at its periphery a space suitable for the passage of gas, in that the coolant reservoir is arranged in the upper zone, and in particular at a sufficient distance above the screen, so that this upper zone constitutes a zone of heat exchange by natural convection, and in that the compartment for fresh product is arranged in the lower zone so as to provide a free space around the compartment, its dimensions in particular being substantially smaller than the internal volume of the container.

Another object of the present invention is to provide a traveling trolley for storing and transporting fresh products comprising such an insulated container, and the applications of such containers or trolleys to the conservation and transport of products at temperatures close to 0 ° C. .

Preferably, solid carbon dioxide stored in the tank is used as the refrigerant.

• . les produits stockés à proximité du réservoir sont protégés du rayonnement et donc des trop basses températures par l'écran qui forme barrière thermique ;
• . les gaz de sublimation peuvent s'écouler le long des parois du conteneur, dans l'espace libre laissé entre l'écran et les parois internes verticales. Lors de la sublimation de départ, les gaz froids descendent vers le bas du conteneur en échangeant leurs frigories au fur et à mesure. L'ambiance chaude du conteneur remonte par convection naturelle et passe dans la zone propre à l'échange par convection naturelle, en particulier entre l'écran et le réservoir de produit réfrigérant où elle refroidit.

The invention has the following advantages:

• . the products stored near the tank are protected from radiation and therefore from too low temperatures by the screen which forms a thermal barrier;
• . the sublimation gases can flow along the walls of the container, in the free space left between the screen and the vertical internal walls. During the initial sublimation, the cold gases descend to the bottom of the container, exchanging their frigories as they go. The hot atmosphere of the container rises by natural convection and passes into the area suitable for exchange by natural convection, in particular between the screen and the coolant tank where it cools.

The refrigerant is then a cooling agent for a radiant thermally conductive exchange surface which allows permanent cooling of the atmosphere by natural convection.

The food compartment may or may not be removable. There is free space around the compartment in the container. The cold gas flowing along the walls of the container also flows along the walls of the compartment and cools it uniformly. The double envelope formed plays the role of a new thermal barrier with low insulating power, but compensated by the fact that the gas / solid exchange (without circulation) provides a low coefficient of thermal transfer.

In the case of transporting meal trays, for example, the fresh products can optionally be stored on several trays arranged in the food compartment.

The food compartment can be opened, for example, at the front and / or rear to allow easy loading and unloading of fresh products, and in this case the refrigerant gases are in contact with fresh products during storage . It can also be airtight.

Carbon dioxide is however detrimental to the good conservation of certain fresh products. Therefore, in this case, the food compartment must be airtight.

There is within the container a structure of cleats made of food-grade polyethylene permanently fixed to the walls of the container. This internal structure makes it possible to load the products to be transported without special precautions, its role being essentially to ensure the circulation of gaseous CO₂ around the product in the container fitted with a double envelope. The double envelope or compartment formed by a watertight metal box made of thin sheet metal is deposited on the internal structure of the insulated container, that is to say on the lower battens and between the lateral battens, and its watertightness guaranteed on the front, loading side, by a metal door secured to the insulated door of the container.

In this case, the door can also be equipped with a plate fixed on its internal face, the plate being spaced from the internal face of the door to ensure the double envelope, the sealing of the compartment then being guaranteed by a seal at lips. This seal makes it possible to seal the compartment even when the excess CO₂ escapes through the door while moving away from the container.

As will appear later, the containers according to the invention perfectly meet the conditions of temperature, temperature stability during storage and temperature uniformity for the preservation of fresh products.

This is why the present invention also relates to the application of these containers to the storage of products at temperatures close to 0 ° C.

• à la figure 1, une vue de face en coupe selon A-A d'un conteneur selon l'invention ;
• à la figure 2, une vue de côté partielle en coupe selon B-B du même conteneur ;
• à la figure 3, une vue en perspective de l'ensemble du réservoir et de l'écran selon l'invention.

Other characteristics and advantages of the invention will appear on reading the following detailed description and in the light of the appended drawings which represent:

• in Figure 1, a sectional front view along AA of a container according to the invention;
• in Figure 2, a partial side view in section along BB of the same container;
• in Figure 3, a perspective view of the entire reservoir and the screen according to the invention.

As shown in FIG. 1, the rectangular container 1 consists of walls provided with insulating material 2. Above a lower zone receiving at least one compartment C for fresh produce extends a polyethylene plate 3 forming a screen suspended by four suspension columns 4 from the upper wall 5 of the container 1. This screen forming plate 3 delimits an area 6 suitable for exchange by natural convection where the hot gases which rise from the lower part of the container through the free space 8 between the screen 3 and the vertical walls 9 of the container cool in passing between the screen 3 and the coolant reservoir 10.

Usually, the containers further include in their lower part a grating 11 or cleats made of plastic, for example polyethylene on which the fresh products to be transported are arranged.

In FIG. 2 appears in section, and seen from the side, the same container 1 provided with the screen 3 suspended by the columns 4 and with the reservoir 10 placed in the area 6.

In this side view appears a door 19 of the container 1, also thermally insulated, the door 19 being provided with door seals 20 ensuring sealing.

In Figure 3 appear in perspective the screen 3 and the tank 10 as they are arranged in the upper part of the container to form the natural convection zone. The screen forming plate 3 is provided as described above with four suspension columns 4. The reservoir 10 is a drawer made of 304L stainless steel provided with slides 12 capable of sliding in translation on slides 13 parallel to the drawer and themselves provided with pads of suspension 14 to the upper wall 5 of the container 1.

The studs 15 located at the end of the slides 13 on the side of the bottom 16 of the drawer 10 form a stop. The drawer 10 is equipped, on the side opposite the bottom 16, with a handle 17 allowing the user to handle the drawer in translation when filling or checking the level of coolant. The bottom 18 of the reservoir 10 is located at a distance of a few centimeters from the screen 3. A suitable convection zone is defined in the upper part of the container, for example if the bottom 18 of the drawer 10 is approximately halfway between the screen 3 and the upper wall of the container where the studs and suspension columns are fixed (4, 14, 15).

Alternatively, two superimposed plates can be provided, separated by washers. As a material for the plate (s), expanded PVC is suitable.

Tests were carried out with a container according to the invention. The tank 10 is a 304L stainless steel drawer with internal dimensions (in mm) 500 x 420 x 50 (thickness 12/10). The screen 3, a 10 mm thick polyethylene plate, is suspended from 100 mm and the drawer is suspended from 10 mm from the wall 5. The free space 8 is 30 mm at the front and at the rear and 55 mm on the sides.

The temperature between the reserve drawer provided with solid CO₂ and the thermal barrier formed by the screen plate is at an average of -18 ° C. the temperatures measured in the container outside this zone have remained above -5 ° C., with a gap between the bottom and the top of the container of around 2 ° C. The tests lasted more than 5 hours at ambient temperatures of around 15 ° C. The products stored in the container remained between 0.5 and 2 ° C.

Claims (10)

1. Isothermal container with isothermal walls defining an interior space divided horizontally by a screen (3) into an upper area (6) receiving an open reservoir (10) of a sublimating refrigerant, and a lower area receiving at least one compartment of products to be kept cold, the upper and lower areas being accessible through access means (19) disposed on the same side of the container, a space being provided between the reservoir of refrigerant and the screen, characterised in that the screen is produced from a thermally insulating material and is slightly smaller than the internal section of the container, to leave at its periphery a space (8) suitable for the passage of gas, in that the reservoir of refrigerant is arranged in the upper area (6), and notably at a sufficient distance above the screen, so that this upper area forms an area of heat exchange by natural convection, and in that the compartment for fresh products is arranged in the lower area so as to form a free space around the compartment, its size notably being substantially less than the internal volume of the container.
2. Container according to Claim 1, characterised in that the screen (3) consists of at least one plate made of plastic suspended by suspension columns (4) from the top wall (5) of the container.
3. Container according to one of Claims 1 or 2, characterised in that the reservoir is produced in the form of a drawer (10) having runners (12) cooperating with slides (13) supported, through suspension studs (14, 15), by the top wall (5) of the container.
4. Container according to one of Claims 1 to 3, characterised in that the bottom (18) of the reservoir (10) is disposed approximately half-way between the screen (3) and the top wall (5) of the container (1).
5. Container according to one of Claims 1 to 4, characterised in that the width of the space (8) between the edge of the screen (3) and the vertical walls of the container is 3 to 6 cm.
6. Container according to one of the preceding claims, characterised in that at least the lower area has ledges fixed on the walls of the container.
7. Container according to one of Claims 1 to 6, characterised in that the compartment has an access door fixed to the isothermal door of the container.
8. Mobile trolley for storage and transport of cool products, characterised in that it includes a container (1) according to one of the preceding claims.
9. Trolley according to Claim 8, characterised in that the compartment has plates for storage of fresh products.
10. Application of a container or trolley according to one of the preceding claims to the conservation and transport of products at temperatures close to 0°C.

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