EP0781394A1

EP0781394A1 - Device for the controlled transfer of cold from a cold source to a cooling enclosure

Info

Publication number: EP0781394A1
Application number: EP95933455A
Authority: EP
Inventors: René Vincent Grandi
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-09-30
Filing date: 1995-09-29
Publication date: 1997-07-02
Anticipated expiration: 2015-09-29
Also published as: ES2119479T3; DE69502727T2; EP0781394B1; FR2725265A1; FR2725265B1; DE69502727D1; WO1996010723A1; AU3611095A

Abstract

Device of the type in which cold is transferred from an upper section (2) to a lower enclosure (10) separated by an insulating wall (3a) through a heat pipe of a suitable heat-conducting material, which is filled with a heat-exchanging medium after a vacuum is created therein. According to the invention, the heat pipe consists of an exchange and control plate (7) disposed in the enclosure (10), the plate (7) being fitted with an inner heat exchange fluid coil (6) and, on one side, at least one collecting tube (5, 5a) which communicates with the coil and extends into the upper section (2). The plate is mounted so as to oscillate about a transverse horizontal axis between an exchange position (A) in which slopes down from the collector tube, and a stabilizing position (B) in which it slopes the other way, the plate (7) also being connected to motor means (11 and 9, 28, 28a) which control its oscillation on either side of the horizontal plane according to the temperature in the enclosure (10).

Description

"Device for the regulated transfer of frigories between a reserve of frigories and an enclosure of conservation by the cold".

The invention relates to a device for the controlled transfer of frigories between a reserve of frigories and a cold storage enclosure. Although more specifically targeting isothermal containers intended for the conservation of fresh or frozen products, during their transport and their temporary storage, the device applies to any isolated enclosure in which the frigories ensuring the conservation come from a reserve which can be constituted by a box attached to the enclosure or on the enclosure, or by a separate compartment disposed above the enclosure.

The problem underlying the invention is that of regulating the temperature in the preservation enclosure, while the emission of frigories is permanent and uncontrollable, whatever the source, namely cartons containing a fluid. frozen, plate containing eutectic liquid, brine, or dry ice in the form of snow, sorbet, or bread.

This lack of regulation leads to two drawbacks which limit the application of this method of conservation.

The first is that of the consumption of frigories which, depending on the outside temperature, the overall insulation coefficient of the container, and the duration of transport and / or storage, is very variable and leads to overconsumption, when all the Energy is not consumed, since it is expected to be in excess of actual needs, or to deterioration of the foodstuffs or products to be preserved, when the quantity supplied is insufficient for the duration of conservation.

The second drawback is encountered more particularly in the use of dry ice which, due to its temperature of the order of - 70 ° to - 80 ° C. can succeed, despite the presence of protective screens, in freezing, burn or dehydrate perishable food.

These drawbacks are well known, but despite the numerous solutions proposed in the state of the art, they have not yet been able to be entirely eliminated, by reliable means regulating the temperature in the preservation enclosure.

Thus, for example, EP - A 136 458 and EP - A 166 086, describe devices for distributing frigories between a reserve and an enclosure using networks of thermal tubes, also called heat pipes, composed of closed tubes containing, under vacuum, a heat transfer fluid taking frigories from the reserve to bring them into the enclosure.

Due to the absence of any regulation and the operating principle of the heat pipes, frigories try to accumulate on the arm of the conservation enclosure by emptying the reserve, which does not solve either the problem of consumption, nor that of obtaining an optimal temperature, favorable for the good conservation of foodstuffs. The object of the present invention is to remedy these drawbacks by providing a device for the regulated transfer of frigories between a reserve and a preservation enclosure, a device making it possible to regulate the temperature in the enclosure, independently of the power of the refrigerant means placed in the reserve, while considerably reducing the consumption of this medium.

In this device, of the type using a heat pipe, the heat pipe is composed of an exchange and regulation plate placed in the enclosure, below the reserve and close to but without contact with the insulating wall separating the reserve and the enclosure, this plate, provided with an internal serpentine network for the heat transfer fluid and, on the one hand, at least one sensor tube communicating with the aforementioned network and penetrating into the reserve of frigories by a channel of the insulating wall, being mounted oscillating around a horizontal transverse axis between two positions, arranged on either side of the horizontal plane, namely an exchange position in which it is inclined up and down starting from the sensor tube, and a stabilization position in which it is inclined from the bottom upwards starting from this sensor tube, said plate also being connected, by its side opposite to that provided with the sensor tube, to command motor means. t its oscillation on either side of the horizontal plane as a function of the temperature in the enclosure.

In this device, when the heat pipe, consisting of the exchange plate and the sensor tube is in the exchange position, that is to say when the plate is inclined from top to bottom from the sensor tube, the end of this sensor tube is inside the reserve of frigories, from which it can capture the frigories to transmit them to the coil contained in the exchange plate.

As soon as the temperature in the enclosure reaches a defined threshold, for example 4 °. 0 ° or 20 ° C, the drive means cause the plate to tilt so that, on the one hand, the latter coming into the stabilization position, is inclined from the bottom upwards starting from the sensor tube and the end of the sensor tube is no longer in the reserve, but in the wall separating this reserve from the conservation enclosure. As the sensor tube is no longer in the cold store and the plate no longer has the correct inclination, the cold can no longer be brought to the storage enclosure. It is obvious that a rise in temperature in the enclosure triggers the operation of the motor means to bring the plate from its stabilization position to its exchange position.

In one embodiment of the invention, the sensor tube, rigid and integral with the plate, has at its free end an insulating plug capable, when the plate is in the stabilization position, of closing the communication channel between the reserve and the conservation enclosure to interrupt any heat exchange with the reserve.

This simple arrangement avoids any loss of calories by thermal conductivity through the material constituting the heat pipe. 3

In another embodiment, the sensor tube consists of a tubular body, elastically deformable longitudinally, sealingly crossing the channel of the insulating wall, and the end of which, arranged in the reserve, is connected to the fluid network coolant of a transfer plate which, similar to the exchange and regulation plate with which it forms a single heat pipe, is arranged on the bottom of the reserve, in a fixed manner and is inclined from top to bottom going towards the sensor tube.

This transfer plate, which is therefore permanently placed in the reserve of frigories, reduces the response time of the heat pipe when the exchange and regulation plate is brought into the exchange position but does not influence the emission of frigories when the exchange plate is in the stabilization position, since precisely the circulation of the heat transfer fluid within the heat pipe is interrupted by the inversion of the angular position of the exchange plate.

It already appears that the device according to the invention brings significant progress to the control of the temperature regulation in the preservation enclosure, while allowing, with the same refrigerant mass to save the emission of frigories and increase autonomy, therefore increase the shelf life.

Other characteristics and advantages will emerge from the description which follows with reference to the appended diagrammatic drawing representing, by way of examples, several embodiments of this device in the case of its application to a container. FIGS. 1 and 2 are partial side views in section showing a first embodiment of this device, respectively when it is in the stabilization position, and in the exchange position,

FIG. 3 is a plan view from above of the exchange plate,

FIG. 4 is a side view in cross section and on a reduced scale of a container equipped with the device according to the invention,

Figures 5 and 6 are partial side views in elevation showing another embodiment of the device when the exchange plate is, respectively, in the stabilization position and in the exchange position, and in the context of the application from this device to a reserve of frigories which can be supplied by a refrigerant or by dry ice bars, and by a refrigerant cooled by a coil,

FIG. 7 is a partial side view, in cross section, showing the application of the device to a container equipped with an airtight reserve cooled by an external plate,

FIG. 8 is a partial side view in elevation and in cross section showing the container of FIG. 7, when its reserve is embedded on a supply plate, Figure 9 is a partial side view in elevation with cross section showing the application of the device to a container with reserve of refrigerants refillable by an external regeneration device.

In the embodiment shown in Figures 1 to 4, the reference numeral 1 designates the container with its reserve 2 of frigories. These two elements have insulating walls 3 and are therefore separated by a wall 3a. The conservation enclosure 10, formed in the container 1, communicates with the reserve of cold stores 3 by a channel 4.

The regulation device according to the invention is composed of a plate 7, of transfer and exchange, containing a meandering network 6, shown here by a serpentine. This network, filled with heat transfer fluid after being emptied of air, is part of the heat pipe also comprising at least one sensor tube 5 projecting vertically upwards from the plate 7.

The plate 7, which is made of heat conductive material, and for example of metal such as stainless steel or aluminum, is disposed in the enclosure, below and near, but without contact, of the wall 3a separating enclosure 10 from reserve 2.

Figure 3 shows that this plate has a plan view from above, a generally rectangular shape, whose dimensions are smaller than those of the cross section of the enclosure 10 in which the plate is called to move. In fact, this plate is mounted oscillating around a horizontal transverse axis, materialized by the two pins 12, visible in FIG. 3. It can oscillate on either side of the horizontal plane between an exchange position, represented by A in Figure 2, and a stabilization position, shown in B in Figure 1.

The sensor tube 5 extends the heat transfer coil and is provided, at its free end, which enters the reserve of frigories 2, with a plug 8 made of insulating material, the usefulness of which will be specified below.

By its edge, which is opposite to that equipped with the sensor tube 5, the plate 7 is connected to motor means which, in the embodiment of Figures 1 to 4, comprise an electric motor 11 powered by batteries 22 actuating a worm 23. This worm cooperates with a nut, not shown, linked to the plate. The supply of the electric motor 1 1 is under the dependence of a thermostat 9, placed in the conservation enclosure 10.

The refrigeration reserve 2 is provided with a hatch 13 allowing it to be filled with refrigeration products which may consist of glycol 19 or dry ice cubes 20. This reserve is also provided with a valve 14 serving for degassing the products gas and a sheet metal 15 protecting the sensor tube, so that its movement is not hampered by any product or coolant. Finally, a trap door 16 is used for exchanging the batteries 22 and for controlling the motor 11, which can moreover be replaced by an electromagnet.

In FIG. 1, the plate 7 is in the stabilization position and therefore inclined from the bottom up starting from the sensor tube. In this position, it opposes the circulation of frigories in the coil 6 of the heat pipe and therefore interrupts any emission of frigories in the direction of the conservation enclosure. Note that, in this position, the plug 8 of the sensor tube 5 seals the end of the conduit 4 for communication between the reserve 2 and the enclosure 10 and thus avoids any heat exchange by direct conduction. When the temperature in the enclosure rises, the thermostat 9 triggers the supply of the motor 1 1 which, by the screw 21, causes the plate to tilt from its stabilization position B to its exchange position A in which it is inclined up and down from the sensor tube 5. This has the effect, on the one hand, of penetrating the upper end of the sensor tube 5 into the reserve 2, and on the other hand, of bringing the heat pipe into its operating position. As a result, the frigories, taken by the sensor tube 5 and circulating in the coil 6, are transferred to the plate 7 which diffuses them into the enclosure 10.

It is very important that, in its exchange position, the plate 7 has an inclination which with respect to the horizontal plane is at least of the order of 3 °, in order to allow the operation of the heat pipe. The inclination of the exchange plate, in its stabilization position, is of the same order, but may be less, the main thing being that the plate passes beyond the horizontal position to stop the operation of the heat pipe.

Of course, as soon as the temperature in the enclosure 10 is sufficiently lowered and reaches the triggering threshold of the thermostat 9, the latter controls the supply of the motor 11 to bring the plate into its stabilization position.

It appears from the above that the regulation of the temperature in the enclosure is carried out according to the all or nothing principle, and automatically. This makes it possible to reduce the consumption of refrigerated products and to increase the duration of consumption compared to current containers which do not include such a device.

Figure 4 shows a complete and equipped transport container. Its enclosure 10 is equipped with shelves 18 and a grid 17 protecting the plate and preventing its clearance space from being cluttered with products or foodstuffs stored in the enclosure.

In the embodiment shown in FIGS. 5 to 9, the sensor tube 5a is constituted by a tubular body which can be deformed longitudinally in an elastic manner and, for example, which has original folding zones which facilitate its longitudinal deformation. As before, this sensor tube communicates by its lower end with the network 6 of the plate 7, but in addition, it communicates by its upper end with a coil 26 circulating in a transfer plate 27, arranged on the bottom of the reserve 2 of frigories. The plate 27 occupies a fixed position and is inclined relative to horizontally, from top to bottom, going towards the sensor tube 5a. The network 26, the network 6 and the intermediate sensor tube 5a define the same heat pipe.

In this embodiment, the transfer plate 27, in direct contact with the refrigeration products 19 or 20, supplies the plate 7 more quickly with frigories when it passes into the exchange position, shown in FIG. 6. It will be noted that, in this exchange position of the plate 7, the tube 5a is compressed longitudinally, without this affecting the circulation of the heat transfer fluid which flows between the transfer plate 27 and the exchange plate 7 and vice versa.

The tilting of the plate 7 can be ensured by the same motor means as those described in the previous embodiment or by those described in Figures 5 and 6. These means are essentially composed of a bar 28 made of a material which is a good conductor of heat constituting, at the same time, means for detecting the temperature in the enclosure 10 and motor means.

In the embodiment shown in Figures 5 and 6, this bar is arranged vertically against one of the vertical walls of the enclosure 10 relative to which it is guided in longitudinal translation. It rests on the lower wall of the enclosure and is provided at its upper end with a head 29 pressing with the interposition of a spring 30 against the free end of the plate 7. It is easy to see that the variations in temperature in the enclosure 10 cause variations in the length of the bar 8 and, consequently, variations in the angular position of the plate 7 relative to the horizontal plane. The spring 30 makes it possible to absorb the large elongations of the bar 28. for example, in the case of very hot weather, by preventing the bar from destroying the plate 7 and the regulating device.

In the embodiment shown in Figures 7 to 9, the bar 28a is arranged horizontally in sliding bearings not shown, below the plate 7 in the gap between the plate 7 and the protective grid 17. The one of its ends is fixed against the vertical wall of the container disposed on the side of the sensor tube 5 a and its other end is in abutment against a lever 31 actuating a finger 32 projecting downwards from the plate 7. The bar can be made by metal, but it can also be made of synthetic material and, for example, in a polyethylene having a good coefficient of expansion such as a high density polyethylene having a coefficient of expansion of the order of 0.004.

These drive means are particularly advantageous since they require no energy, are reliable, are compact and can work equally well for the storage at 4 ° C or 0 ° C of fresh products, or at - 25 ° C of frozen products, and this by simple modification of the position of their anchoring relative to the container. The regulating device according to the invention can be used regardless of the nature of the products or means constituting the reserve of frigories. Thus, as shown in Figure 6, the reserve 2a can be arranged to receive a liquid 35, freezing at a temperature below the storage temperature in the enclosure, and include, for this purpose, a conduit 36 for supplying the liquid reserve and a conduit 37 for draining this liquid, but also a coil 38 for cooling this liquid. The two ends respectively 38a and 38b of the coil pass through one of the insulating walls 3 of the reserve 2 and are provided with connections 39a, 39b which can be connected to a refrigeration unit supplying a refrigerant at a temperature lower than that of the liquid 35 contained in the reserve.

FIG. 9 shows the regeneration of the reserve of frigories 2 by means of a device 40 comprising a cold production group 42 whose coil 43 ensures the cooling of a refrigerant liquid 44, disposed in an insulating container 45. Two conduits flexible 46a and 46b, including the one 46a with a pump 47, lead to fittings 48a, 48b which can be connected to the fittings 39a, 39b of the coil 38 of the calorie reserve of the container. The reserve 2a is regenerated by circulating the refrigerant 44 in the direction of this reserve. Traversing the coil 38, this liquid causes the freezing of the fluid 35. As soon as this is reached, the fittings 48a and 48b are disconnected and the container can be used to receive the products which must be preserved.

It will be noted that, under these conditions, the exchange plate 27, by its large contact surface with the frozen product, promotes the transmission of frigories to the heat pipe.

When all the frigories are consumed, and in anticipation of a new use, the container is brought back to the loading station 40. This can be of the type described in European patent no. 639,256 in the name of the applicant , takes the fluid having lost its frigories by the circuit 39b, 48b, 46d, to direct it towards a first reserve then replaces it with a refrigerated fluid coming from another reserve by the circuit 46a, 48a, 39a.

With this arrangement, the container has a large reserve of frigories, without being equipped with a refrigeration unit.

By way of example, in order to obtain, in a storage enclosure 10 having a capacity of 900 liters, a storage temperature of the order of - 20 to - 25 ° C, the refrigerant 35 placed in the reserve 2a is brought to a freezing temperature of the order of - 30 to - 33 ° C by the coil 38, the fluid 44 of which is itself brought to a temperature of the order of - 37 ° C. Such a refrigerating charge allows, even in summer conditions, to ensure the conservation of frozen products for a period of several days, thanks to the regulation device according to the invention. In the embodiment shown in Figures 7 and 8, the reserve 2b can also be arranged to be recharged with calories by the device described in French patent 2,689,222 in the name of the applicant. For this purpose, the reserve 2b comprises a sealed cavity opening to the outside and which can be closed by a hatch 52. The wall of this cavity is made of heat conductive material and is in direct contact with the refrigerant 53 placed in the reserve. .

The loading of refrigerants is carried out by introducing into the cavity 50 a plate 54 internally traversed by the evaporator 55 of a refrigeration unit 56. After the refrigerant 53 has been brought to the appropriate temperature, which can go up to its freezing, the plate 54 carried by a bracket 57 is uncoupled from the container 1, and the hatch 52 is closed.

This charging technique also makes it possible to regenerate the reserve of frigories at a fixed station, without the need to equip the container with a refrigeration unit.

In this application, the regulating device is very important because it protects the dissipation of frigories and makes it possible to increase the shelf life of the products and foodstuffs arranged in the container.

In FIG. 8, the references 58, 59 and 60 designate a cover and insulating flaps which fold over the plate 55 to avoid heat losses from the plate 58 when it is not in use. Although, very advantageous in the case of its application to the regulation of the temperature in the storage enclosure of a container, the regulated transfer device according to the invention can also be applied to any container having insulated walls and intended to contain any products. It can, for example, be placed in a box placed on an insulating box of the type used to contain fresh fish, or any other fishery product immersed in a bed of crushed ice, or for the transfer of corpses.

Claims

1. Device for the regulated transfer of frigories between a reserve of frigories and a cold preservation enclosure in which the transfer of frigories, between the upper reserve (2) and the lower enclosure (10) separated by an insulating wall ( 3a), is provided by a thermal tube or heat pipe made of a material which is a good conductor of heat and containing, under vacuum, a heat transfer fluid, characterized in that the heat pipe is composed of a plate (7) for exchange and regulation arranged in the enclosure (10), below the reserve (2) and near but without contact with the insulating wall (3a) separating the reserve and the enclosure, this plate (7) being provided with an internal network winding (6) for the heat transfer fluid and, on the one hand, at least one sensor tube (5, 5a) communicating with the above-mentioned network and entering the reserve (2) of frigories by a channel (4) formed in the insulating wall (3 a) and being mounted oscillating around d '' a horizontal transverse axis between two positions, arranged on either side of the horizontal plane, namely an exchange position (A), in which it is inclined up and down starting from the sensor tube, and a position of stabilization (B), in which it is inclined from the bottom upwards starting from this sensor tube (5, 5a), said plate (7) being also connected, by its side opposite to that provided with the sensor tube (5, 5a) to motor means (1 1 and 9, 28, 28a) controlling its oscillation on either side of the horizontal plane as a function of the temperature in the enclosure (10).

2. Device according to claim 1, characterized in that the plate (7) for exchange and regulation forms, with respect to the horizontal, and when in the exchange position, an angle of at least 3 ° C.

3. Device according to any one of claims 1 and 2, characterized in that the sensor tube (5), rigid and integral with the plate, comprises at its free end an insulating plug (8) suitable, when the plate is in stabilization position, to close the communication channel (4) between the reserve (2) and the conservation enclosure (10) to interrupt any heat exchange with the reserve.

4. Device according to any one of claims 1 and 2, characterized in that the sensor tube (5a) consists of a tubular body deformable longitudinally in an elastic manner, sealingly passing through the channel (4) of the insulating wall, and whose end disposed in the reserve is connected to the network (26) of heat transfer fluid of a transfer plate (27) which, similar to the plate (7) for exchange and regulation with which it forms a single heat pipe , is arranged on the bottom of the reserve (2), in a fixed manner and is inclined from top to bottom going towards the sensor tube (5a).

5. Device according to any one of claims 1 to 4, characterized in that the motor means consist of an electromagnet powered by batteries (22) and the supply of which is controlled by a thermostat (9) arranged in the 'conservation enclosure (10).

6. Device according to any one of claims 1 to 4, characterized in that the motor means consist of an electric motor (11) linked to a worm

(21) cooperating with a nut integral with the plate (7), this motor being powered by batteries

(22) under the control of a thermostat (9) arranged in the conservation enclosure (10).

7. Device according to any one of claims 1 to 4, characterized in that the motor means consist of a bar (28, 28a), made of heat conductive material and with a high coefficient of expansion, one end of which is fixed against one of the walls of the enclosure (10), and the other end of which comes into contact with the plate (7), directly or by means of a bevel gear.

8. Device according to claim 7, characterized in that the bar (28a) is arranged horizontally below the exchange plate (7), between this plate and a protective grid, and its free end bears against a lever (31) actuating a finger (32) projecting vertically downwards from the plate (7).

9. Device according to any one of claims 1 to 8, characterized in that the reserve of frigories (2a) contains a fluid (35), freezing at a temperature below the storage temperature in the enclosure (10) , and a freezing coil (38), the two ends (38a, 38b) of this coil passing through one of the insulating walls of the reserve (2a), being provided with connectors (39a, 39b) for connection to the conduits (46a ) inlet and outlet (46b) of a refrigeration unit (40) ensuring the cooling of the refrigerant (44) contained in the coil (38) to a temperature below that of freezing the fluid (35) contained in the reserve (2a).