The present invention relates to a refrigerated container for transporting perishable goods (such as food or medicines) and in particular a refrigerated unit load device for transport by air, i.e. a container of the type commonly known as a ULD (Unit Load Device).

As is known, the category of unit load devices includes for example pallets and containers which are used for loading goods of various types on means of transport and in particular on aircraft. Using a unit load device makes it possible to load large quantities of goods with a single unit, which makes it possible to optimize the time and manual labor needed for loading and unloading the aircraft.

Unit load devices and other refrigerated containers are normally used for transporting goods that need to be kept within a certain temperature range in order to not perish, such as for example medicines and food.

In the prior art, the solutions that are used for providing unit load devices and other refrigerated containers can be grouped into three categories: active solutions, semi-passive solutions, and passive solutions.

In active solutions, the container is provided with a refrigeration apparatus that must be powered continuously by mains electricity or by batteries. These conventional active solutions have the disadvantage that the operation of the refrigerated container depends on the availability of mains electricity; otherwise its capacity is limited by batteries. Furthermore the presence of a dedicated refrigeration apparatus makes these containers complex and expensive to produce, maintain and certify for compliance with IATA regulations, under which they are considered part of the aircraft.

In semi-passive solutions, the container is kept refrigerated by dry ice which is loaded in huge quantities before each trip and stored inside a special compartment in the container, which must be provided with battery- powered fans for controlling the temperature. These conventional semi- passive solutions have the disadvantage of requiring considerable logistical effort for loading and mobilizing the dry ice, and also the related and well- known problems of safety.

In passive solutions, usually the refrigerated container contains, inside the walls, a heat storage material such as a phase change material, and the container must be kept in a cold room for a period of time sufficient to freeze the heat storage material (in general at least 24 hours) before each trip. Alternatively, the heat storage material can be contained, instead of in the walls, in removable thermal packs which are frozen separately in a cold room and then installed along the walls of the refrigerated container.

These passive solutions have the disadvantage of requiring the use and availability of large cold rooms, as well as requiring lengthy preparation times for freezing the heat material and also a considerable logistical effort and extensive use of manual labor for shuttling the refrigerated container to and from the cold room (if the heat storage material is integrated in the walls) or for charging and installing the thermal packs.

Furthermore, disadvantageously, this type of procedure of freezing the heat storage material in cold rooms is very wasteful from an energy point of view.

The aim of the present invention is to provide a refrigerated container that is capable of solving the problems and overcoming the limitations of the above-mentioned prior art.

Within this aim, an object of the present invention is to provide a refrigerated container that, in use, does not entail logistical efforts or the problems of safety, explained above, that are typical of the known passive and semi-passive solutions.

Another object of the invention consists in providing a refrigerated container that is more efficient from the energy point of view.

Another object of the invention consists in providing a refrigerated container that has a greater thermal capacity. Another object of the invention consists in providing a refrigerated container that can operate independently of the availability of mains electricity during the trip and without batteries.

Another object of the invention is to provide a refrigerated container that is easy to provide and use, and is also economically competitive.

This aim and these and other objects which will become more apparent hereinafter are achieved by a refrigerated container according to claim 1.

This aim and these and other objects which will become better apparent hereinafter are also achieved by an apparatus according to claim 12 and also by a method according to claim 13.

Further characteristics and advantages of the invention will become better apparent from the description of some preferred, but not exclusive, embodiments of a refrigerated container, which are illustrated by way of non-limiting example with the aid of the accompanying drawings wherein:

Figure 1 is a perspective view of a possible embodiment of a refrigerated container, according to the invention, in which the walls of the container have been made transparent for greater clarity;

Figure 2 is a perspective view of the heat accumulation units of the container of Figure 1;

Figure 3 corresponds to Figure 2, in which part of the external enclosure of a heat accumulation unit has been removed to show its contents;

Figure 4 is a perspective view of the heat accumulation units in the previous figures, from a different viewpoint, in which part of the external enclosure of both of the heat accumulation units has been removed to show their contents;

Figures 5A and 5B are schematic representations of the operation of a refrigerated container together with a heat loading apparatus, in two different configurations; Figure 6 is a perspective view of a different embodiment of a heat accumulation unit present in a different embodiment of the refrigerated container according to the invention.

With reference to the figures, the refrigerated container, generally designated by the reference numeral 1, in the preferred embodiments is a unit load device for transport by air. In alternative embodiments, the container 1 can be of the type of a pallet for transport by land.

According to the invention, the refrigerated container 1 comprises a monolithic box-like body 20 made of polymeric material and one or more heat accumulation units 30, 40 which are coupled to respective internal walls 23, 24 of such box-like body 20.

The wording “coupled to the wall” means directly or indirectly fixed to the wall or integrated in the wall.

Advantageously, the monolithic box-like body 20 is made of expanded polyurethane and is provided by means of a single injection molding (using a single mold). In this manner, the box-like body 20, formed by a single monolithic piece of polyurethane, has no joints and has a superior thermal insulation coefficient with respect to traditional containers made of individual panels/assembled walls (a coefficient K has been found approximately 10-30% lower with respect to the above-mentioned traditional containers).

The monolithic box-like body 20 can be covered with composite material and/or with an outer shell and/or with panels and/or with other conventional coating or reinforcement elements.

In embodiments in which the container 1 is of the type of a unit load device for transport by air, there are two heat accumulation units 30, 40:

- a first heat accumulation unit 30, coupled to an upper wall 23 (a ceiling wall) of the monolithic box-like body 20, and

- a second heat accumulation unit 40, coupled to a side wall 23 (vertical, for example an end wall) of the monolithic box-like body 20. In some alternative embodiments that do not form part of the present invention, and in particular in embodiments in which the refrigerated container is of the type of a container for transport by land, there is only one heat accumulation unit 50, preferably coupled to a vertical side wall of the box-like body 20.

According to the invention, embodiments are not ruled out in which there are more than two accumulation units 30, 40, 50.

According to the invention, the heat accumulation units 30, 40, 50 are connected in fluid communication with an inlet 91 for the entry of a refrigerant fluid and with an outlet 92 for the exit of said refrigerant fluid.

According to the invention, each one of the heat accumulation units 30, 40 comprises an external enclosure 31, 41 (preferably made of aluminum) which contains inside it a heat accumulation material (i.e. a material that defines a hermetic containment cavity inside it in which the heat accumulation material is contained) in which a heat exchanger 32, 42 is embedded.

The heat accumulation material to which reference is made is preferably a phase change material (PCM).

The external enclosure 31, 41 can be parallelepiped in shape or it can be conveniently contoured in compliance with IATA regulations for LD3, LD7 etc. ULDs, and defines a parallelepiped cavity inside it.

Even more preferably, the external enclosure 31, 41 is constituted by special high-strength resins having a thickness comprised between 1 and 4 mm, applied directly on the polyurethane shell or directly on the mold prior to spraying (in the “spray in mold” process), making it possible therefore to obtain with a single production step a monolithic product with high impact resistance, low heat conductance, and significantly reduced tare weight compared to conventional construction technologies. The internal capacity is comprised between 50 and 350 liters in embodiments of the type of a unit load device in which there are two heat accumulation units 30, 40 and comprised between 50 and 1500 liters in embodiments of the type of a container for transport by land in which there is a single heat accumulation unit 50.

In the preferred embodiments the heat accumulation units comprise profiled structural elements 35, 45, 55 which in cross-section are preferably T-shaped and preferably have dimensions comprised between 10x10x2 and 50x50x5 mm, which are coupled by welding to the external enclosure 31, 41, 51 so as to reinforce it mechanically and optimize the heat exchange surface which is adapted to maintain a temperature differential between the surface heat accumulator and the internal air that is such as to ensure the maintenance of the internal temperature in the range required by the regulations. These profiled structural elements 35, 45, 55 also serve as spacer elements and to support an interface shield 37, 47, 57 (in practice a panel) fixed to the external enclosure 31, 41, 51 and directed toward the inside of the container 1. This interface shield 37, 47, 57 contributes to limiting heat exchange toward the inside of the container 1.

The heat exchanger 32, 42 comprises a heat exchange duct (and more precisely an evaporator) 43, 33 which is adapted to be passed through by the refrigerant fluid in transit between the inlet 91 and the outlet 92 so that, by transiting the heat exchange duct 33, 43, the refrigerant fluid cools the heat accumulation material, for example by making it change phase (solidifying it).

Preferably the heat exchanger 32, 42 also comprises a series of fins or slats 34, 44 in order to facilitate the heat exchange between the refrigerant fluid and the heat accumulation material.

According to an optimal solution, in the embodiment of Figures 1-4, the heat exchange duct 33, 43 comprises a plurality of tubes arranged side- by-side along parallel planes, each one of which forms a coil which is arranged along a respective plane, wherein each coil comprises mutually parallel straight portions connected by curved connecting portions (the curved connecting portions can be seen in Figure 4).

Advantageously, each one of the slats 34, 40 is provided with a series of through holes through which the straight portions of the coils pass, such slats being arranged mutually parallel and perpendicular to the planes on which the coils extend.

The heat accumulation material can be a phase change material, preferably in liquid form when at ambient temperature, which solidifies following the cooling caused by the heat exchange with the refrigerant fluid.

Preferably, each one of the heat accumulation units 30, 40 comprises inside it a compressible layer for absorbing the change of volume, interposed between at least some of the external enclosure 31, 41 and the heat accumulation material (i.e. it substantially covers one or more internal walls/parts of internal walls of the external enclosure 31, 41). This compressible layer for absorbing the change of volume is configured to absorb an increase in volume of the heat accumulation material owing to its phase change after cooling: in practice, when the heat accumulation material solidifies, increasing in volume, the compressible layer for absorbing the change of volume is capable of being compressed, so compensating such increase in volume and cushioning the consequent forces so as to prevent damage to the external enclosure 31, 41 and deformations thereof.

In more detail, the compressible layer for absorbing the change of volume comprises a plurality of cells adapted to be compressed and preferably is composed of expanded high density polyethylene (HDPE). Even more preferably, the compressible layer for absorbing the change of volume has a thickness/volume comprised between 8% and 30% of the volume of phase change material.

In the preferred embodiments, the compressible layer for absorbing the change of volume surrounds one face of the heat exchanger 42, covering one of the internal walls of the external enclosure 31, 41.

In embodiments in which there are two heat accumulation units 30, 40, the heat exchange ducts 43, 33 of the first heat accumulation unit 30 and of the second heat accumulation unit 40 are hydraulically connected by means of a hydraulic system 90 which comprises at least one duct for the refrigerant fluid.

In the preferred embodiments, this hydraulic system 90 is configured or can be configured selectively (for example using valves and/or taps 98, 99), in a series connection condition, in which the heat exchange ducts 43, 33 of the first heat accumulation unit 30 and of the second heat accumulation unit 40 are hydraulically connected in series or in parallel so that a refrigerant fluid arriving from the inlet 91 passes first through the heat exchange duct 33 of the first heat accumulation unit 30 and then through the heat exchange duct 43 of the second heat accumulation unit 40 (or vice versa), and then flows toward the outlet 92, as shown in Figure 5 A.

Preferably, such hydraulic system 90 comprises one or more taps and/or valves 98, 99 through which it can be selectively configured both in the above-mentioned series connection configuration, and in a parallel configuration or a disconnection configuration, such as for example shown schematically in Figures 5A and 5B.

In the above-mentioned disconnection configuration the fluid communication between the heat exchange ducts 33, 43 of the two heat accumulation units 30, 40 is interrupted and the heat exchange duct 33 of the first heat accumulation unit 30 (or the second one 40) is connected to the inlet 91 and the outlet 92, so that the refrigerant fluid arriving from the inlet 91 passes through the heat exchange duct 33 of the first heat accumulation unit 30 and then flows directly toward the outlet 92.

In practice, in the disconnection configuration a bypass is created that locks out one of the two heat accumulation units 30, 40 from the circulation of the refrigerant fluid.

Optionally, when there are two heat accumulation units 30, 40, at least the second heat accumulation unit 40 comprises one or more electric resistance heaters 49.

In the embodiment in which there is a single heat accumulation unit 50, this comprises one or more electric resistance heaters 49.

Optionally, the refrigerated container 1 also comprises an electronic control system, programmable, which controls its operation, for example by being functionally connected to the valves and/or taps 98, 99 of the hydraulic system 90 in order to induce the transition from the series connection configuration to the disconnection configuration, and vice versa, for example as a function of the temperature detected by one or more temperature sensors and/or of other parameters detected by adapted sensors.

Alternatively and preferably, the electronic control system (with the same characteristics and functions as those just described) is comprised in the heat loading apparatus 70 which will be described below.

According to a combination of particularly advantageous characteristics, at least the second heat accumulation unit 40 (and preferably also the first 30) comprises a temperature sensor which is functionally connected to the electronic control system, which is configured to activate and deactivate the one or more electric resistance heaters 49 as a function of the temperature detected by the temperature sensor; in particular, the electronic control system is configured to deactivate the electric resistance heaters upon reaching a predetermined threshold temperature.

In some particular embodiments, which are particularly adapted for transport by land, such as for example in the embodiment of Figure 6 in which there is a single heat accumulation unit 50, at least one of the heat accumulation units 50 comprises a series of fans 113 which are configured to extract air from the monolithic box-like body 20, so as to convey it outside the container 1. To this end, in the container 1, and in the monolithic body 20 thereof, there are air passages connected to the fans 113.

Turning now in more detail to the alternative embodiment of Figure 6, the heat accumulation unit 50 in that embodiment comprises a heat exchanger which comprises a plurality of heat exchange ducts which are hydraulically arranged in parallel. This heat exchanger is arranged in contact with a wall of the external enclosure 51, and more precisely with the wall directed toward the inside of the container.

In the preferred embodiments, the inlet 91 and the outlet 92 are configured to be connected to a heat loading apparatus 70 which is adapted to provide the refrigerant liquid by conveying it toward the heat exchange ducts 43, 33 and to extract it from them, for example the inlet 91 and the outlet 92 are fitted with hydraulic connectors, such as for example conventional quick-coupling connectors.

In fact, during operation, and in particular in a step of preparation of the refrigerated container 1 in which the cooling of the heat accumulation material is executed, the container 1 is functionally connected to a heat loading apparatus 70, the function of which is to supply and cool the refrigerant fluid and make it circulate in the heat accumulation units 30, 40, 50 (in particular in the heat exchange ducts 33, 43) in order to cool and preferably solidify the heat accumulation material.

This heat loading apparatus 70 for executing the cooling of the phase change material in the container 1 is also the subject matter of the present invention and comprises:

- a delivery port for the injection of the refrigerant fluid into the inlet 91, configured to be connected to such inlet 91, for example by way of a hydraulic connector;

- an extraction port for the extraction of the refrigerant fluid from the outlet 92, configured to be connected to such outlet 92, for example by way of a hydraulic connector; and

- a cooling circuit, configured to cool the refrigerant fluid directed toward the delivery port and originating from the extraction port.

The cooling circuit can be made in a per se known manner and comprises preferably a power supply assembly, a compressor, a condenser and at least one air extraction fan.

According to an optional and advantageous characteristic, the heat loading apparatus 70 comprises an external containment structure, preferably comprising a protective shell.

Preferably, the heat loading apparatus 70 comprises a (programmable) electronic control system which can be functionally connected to the temperature sensors present in one or more heat accumulation units 30, 40, 50 present in the refrigerated container 1 and preferably also to the electric resistance heaters 49 and even more preferably also to the hydraulic system 90 (when present) in order to control these.

In the preferred embodiments, the electronic control system present in the heat loading apparatus 70 is therefore configured to control (when connected to the container 1) the flow of the coolant liquid and preferably also the actuation of the electric resistance heaters 49 and optionally also the hydraulic system 90 (so inducing the transition from the series connection configuration to the disconnection configuration or vice versa), as a function of the temperature detected by the temperature sensors and optionally of the external environmental conditions. For example, in the embodiment of Figures 1-4, 5A and 5B, when the external ambient temperature is low, the container 1 can function in a “winter” mode as follows:

- the container 1 is connected to the heat loading apparatus 70 in order to execute the heat loading step before the trip and the hydraulic circuit 90 is configured in the disconnection configuration (shown schematically in Figure 5A);

- when the heat loading apparatus 70 is activated, the coolant passes through the heat exchange duct 33 of the first heat accumulation unit 30, the temperature sensor installed in the first heat accumulation unit 30 transfers the data to the electronic control system of the heat loading apparatus 70 and, when the predefined temperature value is reached, the electronic control system automatically stops the flow of coolant; the coolant does not pass through the second heat accumulation unit 40, and the electric resistance heaters 49 present in it are activated in order to increase the temperature of the heat accumulation material from the ambient value to the predefined temperature (typically 60°C) in order to use the heat accumulated in the material to balance the flow of heat through the walls, and the temperature sensor installed in the second heat accumulation unit 40 transfers the data to the electronic control system which automatically switches off the electric resistance heaters 49 when the predetermined temperature is reached.

Optionally there can be slots which can be open or closed according to the requirements of the cargo transported, where food requires 0/+4°C and pharmaceuticals +2/+8°C. The temperature inside the container 1 is the result of the interaction between the transfer of heat modulated by the interface screens 37, 47, the heat absorbed by the first heat accumulation unit 30, the heat released by the second heat accumulation unit 40, and the flow of heat through the walls 23, 24.

In another example, again relating to the embodiment of Figures 1-4, 5 A and 5B, when the external ambient temperature is high, the container 1 can function in a “summer” mode as follows:

- the container 1 is connected to the heat loading apparatus 70 in order to execute the heat loading step before the trip, and the hydraulic circuit 90 is configured in the series connection configuration, as shown schematically in Figure 5B; when the heat loading apparatus 70 is activated, the coolant passes through the heat exchange ducts 33, 43 of both heat accumulation units 30, 40 and the temperature sensors installed in them transfer the data to the electronic control system of the heat loading apparatus 70, then when the preset temperature value is reached the electronic control system automatically stops the flow of coolant; in the meantime, the electric resistance heaters 49 of the second heat accumulation unit 40 are deactivated.

In substance, generally, the method of transporting and/or preserving perishable goods in a refrigerated container 1, according to the invention, comprises the steps of:

- cooling a refrigerant fluid in an apparatus 70 outside the container 1 (in particular in the described heat loading apparatus 70);

- making the refrigerant fluid pass within at least one heat exchange duct 33, 43 comprised in a heat accumulation unit 30, 40, 50 of the container 1 so as to cool the heat accumulation material, preferably until it is made to change phase (solidifying it);

- extracting the refrigerant fluid from the container 1 ;

- transporting and/or preserving the perishable goods in the refrigerated container 1.

Advantageously, the refrigerant fluid is completely extracted from the container 1 before the transport trip.

In practice it has been found that the refrigerated container, according to the present invention, achieves the intended aim and objects in that it simplifies the logistics and avoids the safety problems typical of the conventional passive and semi-passive solutions.

Another advantage of the refrigerated container, according to the invention, consists in that it is markedly more efficient in energy terms.

Another advantage of the refrigerated container, according to the invention, consists in that it has increased capacity which allows end-to-end transport with transit time up to 15 days without interruption of the cold chain and the possibility of opening the door for customs inspections even for prolonged periods (typically up to 1-2 hours) without deterioration of the overall thermal performance; in fact the increase in the temperature inside is subsequently reabsorbed in a short time.

Another advantage of the refrigerated container, according to the invention, consists in that it can function independently of the availability of mains electricity during the trip.

Furthermore, the refrigerated container, according to the invention, is easy to implement and to use, as well as being economically competitive.

The refrigerated container, thus conceived, is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

Thus, for example, the heat accumulators 32, 42 can be provided with a heat shield preferably constituted by a sheet of HDPE that covers most or all of the exposed surface of the heat accumulators. The function of heat shields is to increase the delta of temperature between the temperature of the surface of the heat accumulators and the internal air, so as to be able to use the same container for the transport both of food products which require a temperature comprised between 0/+4°C and also of pharmaceutical products which require a temperature comprised between +2/+8°C, while the surface of the heat accumulator is typically at 0°C.

The heat accumulators 32, 42 can be provided with a heat shield with a shutter for each heat accumulator in order to be able to manually adjust the flow of natural convection as a function of its use in winter or summer.

Moreover, all the details may be substituted by other, technically equivalent elements.

In practice the materials employed, and the contingent shapes and dimensions, may be any according to requirements and to the state of the art.

The disclosures in Italian Patent Application No. 102022000012824 from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.