Isothermal container with refrigerant tank and application to fresh product transport.

p0001The present invention relates to an insulated container, especially a traveling trolley for the transport of fresh products, used for example for transporting food trays.

p0002It is known from US 1,997,936 10 October 1932 (Kiesel) an insulated container with insulated walls comprising a reservoir for coolant arranged in the upper part of the container a heat-insulating material in screen, leaving clean areas the free passage of gas is horizontally disposed below the tank.

p0003The present invention particularly relates to trolleys for transporting fresh products that can be used in particular for storing and transporting fresh produce and such food before distribution in planes, trains or hospitals and at specific temperatures storage of fresh products, that is to say close to 0 ° C. Insulated containers are in this case slightly insulated, lightweight structure, for example only comprise a double-walled, and are arranged or integrally mounted on displacement means, such as trolleys or wheels or gear wheels for example.

p0004However, the applicant has demonstrated that to run by exemplen long-term transportation (30 hours) without freezing the products given the solid CO2 doses to implement an auxiliary device is needed. Therefore the present invention relates to a container, especially a traveling trolley for the transport of fresh products, insulated walls of the type comprising a tank for coolant in which the reservoir is located in the upper part of the container, and where a screen thermally insulating material, slightly smaller dimensions to the internal section of the container and leaving at its periphery an own annular space the free passage of gas is arranged horizontally below the tank at a sufficient distance to define in the upper part of container a clean area for the exchange by natural convection, and in which the tank and the screen comprise fastening means and / or support in the container, characterized in that it comprises at least one food compartment disposed in the container, below the screen plate, of dimensions substantially less than the internal volume of the container, a free space remaining around the compartment in the container.

p0005Preferably is used as the coolant of solid carbon dioxide stored in the tank.

p0006The invention has the following advantages: . products stored near the tank are protected from radiation and therefore too low temperatures by the screen that forms a thermal barrier; . sublimation gases can flow along the walls of the container, in the free space left between the screen and the vertical inner walls. At the start of sublimation, the cold gases descend to the bottom of the container by exchanging their frigories to As. The warm atmosphere of the container rises by natural convection and pass the clean area for exchange by natural convection, particularly between the screen and the coolant reservoir where it cools.

p0007The coolant is then a coolant of a thermally conductive exchanger surface which radiates and which ensures the permanent cooling of the atmosphere by natural convection.

p0008The food compartment may be removable or not. He remains a 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 cooled homogeneously. The jacket formed acts as a thermal barrier to new low power isolation, but offset by the fact that the gas / solid exchange (without traffic) provides a low heat transfer coefficient.

p0009In the case of transportation such meal trays, fresh produce can be stored possibly on several plates arranged in the food compartment.

p0010The food compartment can be opened, for example, the front and / or rear to allow easy loading and unloading of the fresh produce, and in this case the refrigerant gases are in contact with fresh produce during storage . It can also be sealed.

p0011Carbon dioxide is however detrimental to the good conservation of certain fresh products. Therefore, in this case, the food compartment must be sealed.

p0012Is arranged within the container a food grade polyethylene cleats structure permanently attached to the container walls. This internal strucutre loads the products to be transported without special precautions, its role is primarily to ensure the flow of gaseous CO2 around the product that the container is equipped with or without jacket. The jacket formed by a sealed metal box made of thin sheet will déposéer on the internal structure of the insulated container, that is to say on the lower blocks and between the side brackets, and the sealing provided at the front, side loading, by an integral metal door of the isothermal door of the container.

p0013In this case, the door can be also equipped with a plate fixed on its inner face, the plate being spaced from the inner face of the door to make the jacket, the sealing of the compartment then being ensured by a seal lips. This seal ensures the sealing of the compartment even when excess CO2 escapes through the door away from the container.

p0014As will appear later, the containers according to the invention perfectly fulfills the conditions of temperature, stability of temperature during storage and temperature homogeneity for preserving fresh produce.

p0015Therefore the present invention also concerns the application of these containers to the product storage at temperatures near 0 ° C.

p0016Other characteristics and advantages of the invention will appear on reading the following detailed description and in view of the accompanying drawings which represent:<ul><li>- In Figure 1 a perspective sectional front along AA of a container according to the invention;</li><li>- The 2 is a partial side view along BB of the same container;</li><li>- In Figure 3 a perspective view of the assembly of the tank and the screen according to the invention.</li></ul>

p0017As seen in Figure 1, the container 1 is parallelepiped constituted by walls provided with insulating material 2. A polyethylene plate 3 forming screen is suspended by four suspension column 4 to the top wall 5 of the container 1. This shield plate 3 delimits a clean zone 6 to the exchange by natural convection where the hot gases rising from the bottom of the container through the free space 8 between the screen 3 and the vertical walls 9 of the container cool at the transition between the screen 3 and the reservoir 10 of coolant.

p0018Usually, the containers further comprise in their lower part a grating 11 or plastic cleats, for example in polyethylene onto which are arranged the fresh products to be transported.

p0019In Figure 2 appears in section and side view of the same container 1 provided with the screen 3 suspended by the columns 4 and the reservoir 10 disposed in the region 6.

p0020In this view appears a side door 19 of the container 1, also thermally insulated, the gate 19 being provided with door gaskets 20 ensuring the sealing.

p0021In Figure 3 are shown in the perspective 3 and the reservoir 10 screen as they are arranged in the upper part of the container to form the convection zone. The shielding plate 3 is provided as described above of four columns 4. The slurry tank 10 is a drawer in 304L stainless steel provided with guides 12 suitable for sliding in translation on slides 13 parallel to the drawer and they even provided with studs suspension 14 to the top wall 5 of the container 1.

p0022The pads 15 located at the end of the slides 13 of the bottom side 16 of the drawer 10 form stop. The drawer 10 is equipped, on the side opposite the bottom 16, a handle 17 allowing the user to manipulate the slide in translation during filling or in coolant level control. The bottom 18 of the reservoir 10 is at a distance of a few centimeters from the screen 3. A suitable convection zone is bounded in the upper part of the container, for example if the bottom 18 of the drawer 10 is about halfway between screen 3 and the upper wall of the container where are fixed the pads and columns suspension (4, 14, 15).

p0023Can alternatively provide two superposed plates separated by washers. As the material for the plate or plates, expanded PVC is suitable.

p0024Tests were carried out with a container according to the invention. The container 10 is a drawer in 304L stainless steel inner dimensions (in mm) 500 x 420 x 50 (thickness 12/10). The display 3 is a 10 mm thick polyethylene plate is suspended to 100 mm and the slide is suspended at 10 mm from the wall 5. The gap 8 is 30 mm at the front and rear and 55 mm on the sides.

p0025The temperature between the drawer reserve provided solid CO₂ and thermal barrier that forms the shield plate is an average of -18 ° C temperatures measured in the container outside this area remained above -5 ° C, with a gap between the bottom and the top of the container in the order of 2 ° C. The trials 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.