EP0968393A1

EP0968393A1 - Device for modifying the temperature of a fluid

Info

Publication number: EP0968393A1
Application number: EP98912551A
Authority: EP
Inventors: Marc D'alencon
Original assignee: TEFA
Current assignee: TEFA
Priority date: 1997-02-26
Filing date: 1998-02-26
Publication date: 2000-01-05
Also published as: FR2760078B1; FR2760078A1; AU6734498A; WO1998038464A1; US6205811B1

Abstract

A used fluid passes through an exchange path (1), located in a fluid flow transfer (2), before returning for use (13) at a required temperature (TU2). In the transfer path (2) the exchange path (1) is set between the evaporator (6) and the condenser (8) of a refrigerating circuit (4). The refrigerating circuit (4) is actuated only when the temperature (TA1) of the transfer fluid, consisting for example of ambient air, is unsuitable for properly modifying the used fluid temperature by means of the exchange path (1). The used fluid can be heated by simply reversing the direction of the flow in the transfer path (2). The invention is useful for rearranging exchange paths (1, 6, 8) into a single transfer path (2), for example in a single bundle of tubes arranged in several tube layers of suitably connected tubes.

Description

DESCRIPTION "Device for modifying the temperature of a fluid" The present invention relates to a device for modifying the temperature of a useful fluid.

There is a need in industry to give a useful fluid a moderate temperature, that is to say of the order of magnitude of ambient temperatures. This involves, for example, maintaining a useful fluid, liquid or gaseous at a determined temperature, while this fluid also participates in at least one process tending to separate it from this set temperature. Such situations are encountered, for example in the food industry or in the case of ambient fluids, for example inside compartments containing electrical or electronic installations. It is often possible to regulate very economically from an energy point of view by heat exchange with atmospheric air by means of a device called "air cooler". However, the temperature of the atmospheric air varies greatly depending on climatic conditions. In the frequent case where it is necessary to cool the useful fluid, this is no longer possible when the ambient temperature is higher than the set temperature. Likewise, in an application where the useful fluid would require reheating, this is no longer possible when the atmospheric temperature is lower than the set temperature. To overcome this difficulty, it is known to cool the air by evaporating part of the useful fluid (generally water) or a filler fluid there before causing the heat exchange by convection between the air and the fluid. useful. This process is bulky, produces a plume of vapor and mineral deposits in the apparatus. When the useful fluid is evaporated, it therefore circulates in an open circuit, with the risk of bacterial contamination and fouling. It is also known to pass the useful fluid through another exchange path where the useful fluid undergoes the action of a refrigeration unit. The refrigeration unit is only put into operation when the atmospheric temperature is inappropriate to allow the heat exchange between the working fluid and the ambient air to bring the working fluid back to the set temperature. However, this solution increases the pressure drops and the risks of leakage affecting the useful fluid circuit. To reduce pressure drops, a valve can be provided to bypass the refrigeration exchanger when the refrigeration circuit is at rest, but this further increases the complexity of structure and control, as well as the risk of leakage. Also known from EP-A-0 143 855 is a device in which the useful fluid is incoming air which is heated with heat recovered in outgoing air, via a transfer fluid. To complete the heat supply to the incoming air, the transfer fluid, in its path to the exchanger with the incoming air, receives heat from the condenser of a refrigerating machine and, in its path of return to the exchanger with the outgoing air, is cooled by contact with the evaporator of the same refrigerating machine. Again, such a machine has the aim of thermal optimization at the cost of great technical complexity. The object of the present invention is to remedy these drawbacks by proposing a device making it possible to modify the temperature of a useful fluid, which is both less bulky, more economical and more reliable than known devices.

According to the invention, the device for modifying the temperature of a useful fluid, comprising:

a first heat exchange path crossed by the useful fluid and installed in heat exchange relation with a transfer path traversed by a transfer fluid; and a refrigeration circuit comprising, for a refrigerant, a second and a third heat exchange path having one of a function of absorption of heat by the refrigeration circuit and the other of a function of generation of heat by the circuit refrigeration, at least at certain stages of operation, one of the second and third exchange paths being installed in heat exchange relation with the transfer path upstream of the first exchange path, so that the temperature of the fluid transfer is modified by heat exchange with the refrigerant before the heat exchange between the transfer fluid and the useful fluid traversing the first exchange path, is characterized in that the transfer path is an open path having, in upstream of the exchange paths, an entry path in which the temperature conditions are substantially independent of the operating conditions of the device.

Particularly when the temperature of the incoming transfer fluid, such as ambient air, is inappropriate for the exchange with the transfer fluid to bring the useful fluid to the desired temperature, the temperature of the transfer fluid is first modified-by the refrigeration circuit. This results in a simple, compact and particularly reliable construction, in particular with regard to the risks of leaks, fouling and bacterial contamination. A person skilled in the art is dissuaded from the solution according to the invention since the heat exchange efficiency between the working fluid and the refrigerating fluid via the transfer fluid is not very favorable due to the multiple interfaces between these fluids. However, it has been found according to the invention that this drawback is more than offset by the advantages set out above, in particular in the preferred applications where the refrigeration circuit is only put into operation in the case of relatively infrequent climatic conditions. The construction according to the invention differs fundamentally from that according to EP 0 143 855 where the transfer fluid circulates in a closed loop and where the refrigerating machine has the essential function of creating a difference between the average temperature in the exchanger with the incoming air and that in the heat recovery exchanger in the outgoing air.

Preferably, at least one of the inlet and outlet paths is connectable to a reserve of transfer fluid belonging to the environment.

The transfer fluid is preferably atmospheric air or ambient air from a room. he can also be sea, lake, river or basin water, or a discharge fluid such as smoke.

Typically, one does not control or badly the temperature of arrival of the transfer fluid, and one cares little or not at all of the temperature at which the transfer fluid is discharged at the other end of the transfer path.

Preferably, the first exchange path is installed in the transfer path in series between the second and the third exchange path.

Thus, the three exchange paths, constituted for example by bundles of tubes, are placed one after the other in the same path of a transfer fluid which can be the air taken from the external atmosphere, the interior atmosphere of a room, sea, lake or river water, etc. This transfer fluid is first cooled by the evaporator of the refrigeration unit, then heated by the first route exchange which is that traversed by the useful fluid, then further heated by the condenser of the refrigeration unit. The observation which is the basis of this embodiment of the invention is that the temperature of the transfer fluid after the heating by the first exchange path is approximately the same as that of atmospheric air or other fluid. transfer entering the device according to the invention. Thus, the condenser undergoes the same cooling effect from the transfer fluid as if a separate flow of transfer fluid struck the condenser directly. This version of the invention therefore saves a second transfer fluid path, a means such as a fan motor for conveying the fluid transfer in this second transfer path, as well as the operating energy of this motor-fan. In addition, since the three heat exchange paths can be mounted one behind the other in the transfer path common to all of them, the construction is both simpler and more compact.

The device according to the invention may also consist of a heating device in which the transfer fluid passes first in contact with the refrigerating condenser and then in contact with the first exchange path leading to the useful fluid. The transfer fluid cooled by contact with the first heat exchange path then passes into contact with one refrigeration evaporator which cools it even more. The refrigeration circuit then operates as a heat pump.

According to an improved version of the invention, means are provided for reversing the direction of circulation of the transfer fluid. Thus, one of the directions of circulation, going from the evaporator to the condenser, serves to cool the useful fluid while the other direction of circulation, from the condenser to the evaporator, serves to heat the useful fluid. This simple reversal is enough to operate the refrigeration unit in the refrigerator or on the contrary in a heat pump. The reversal of the direction of circulation of the transfer fluid can be obtained by reversing the direction of rotation of a motor-fan driving the transfer fluid, or by selective start-up of one or the other of two motor-fans adapted to produce opposite directions of circulation.

To selectively operate the refrigeration circuit in a refrigerator or, on the contrary, in a pump heat, and thus operate the device according to the invention selectively as a cooler or as a reheater of the working fluid, it is also possible to reverse the direction of circulation of the refrigerating fluid. We pass from one mode of operation to the other by debiting a compressor from the refrigeration unit towards the exchange path which previously constituted the evaporator and which therefore now constitutes the condenser, the compressor sucking the refrigerant gas in which now constitutes the evaporator and which previously constituted the condenser. Such a selection between the two operating modes is possible by means of a system of valves placed at the inlet and at the outlet of the compressor and which can be operated so as to carry out either of the two operating modes which have just been described.

It is advantageous that the means provided for setting in motion the transfer fluid in the transfer path and the useful fluid in the first exchange path can operate when the refrigeration unit is stopped. It is thus possible to reduce the overall energy expenditure of the device and the wear of the refrigeration unit when the temperature of the transfer fluid naturally has a value suitable for bringing, by heat exchange, the temperature of the useful fluid to the desired value. The refrigeration unit only works - as the case may be in a refrigerator or in a heat pump as mentioned above - only if the natural temperature of the transfer fluid is inappropriate to modify or sufficiently modify the temperature of the useful fluid in the desired direction. We can thus have four operating modes: cooling of the useful fluid by the natural temperature of the transfer fluid; - heating of the useful fluid by the natural temperature of the transfer fluid;

- cooling of the useful fluid by transfer fluid previously cooled by one evaporator of the refrigeration unit; - reheating of the useful fluid by transfer fluid previously heated by the condenser of the refrigeration unit.

In the first two cases, regulation is possible by varying the speed of circulation of the transfer fluid. In the second two operating cases, there may be added on / off or more sophisticated regulation, of known type, of the refrigeration unit, to vary the thermal power transferred by the refrigeration unit. An even finer adjustment is possible by providing a refrigeration unit with multiple evaporators, some of which can be deactivated when the need for cooling is not maximum, and / or with multiple condensers, some of which can be deactivated when the need for heating of the cooling fluid. transfer is not maximum.

Other features and advantages of the invention will emerge from the description below, relating to nonlimiting examples. In the accompanying drawings: FIG. 1 is a diagram of a simple embodiment of the invention; Figure 2 is a schematic perspective view of an embodiment of the three exchange paths of the device of Figure 1; Figure 3 is a view of a detail of Figure 1 in an alternative embodiment;

- Figure 4 is a view similar to Figure 1 but relating to another embodiment;

- Figure 5 is a diagram at the end of a bundle of tubes for the exchange paths of Figure 4; and - Figure 6 is a diagram similar to Figure 5 but relating to a variant.

In the example shown in Figure 1, there is provided for a useful fluid a first heat exchange path 1 which is mounted between the outlet 11 and the inlet 12 of a use 13. The use 13 corresponds to a domestic or industrial process which is not part of the invention. The useful fluid leaves the use 13 at a temperature T ₀ ι which must be modified in the first exchange path 1 to become, at the input 12 of the use 13, a temperature T _u2 which is 30 ° C in the nonlimiting example described.

The first heat exchange path 1 is placed in a transfer path 2, in which a transfer fluid can be set in motion in the direction represented by the arrows in solid lines, by means of a motor-fan 3. The useful fluid circulating in the exchange path 1 is in heat exchange relationship with the transfer fluid in the transfer path 2. The transfer fluid may be ambient air, or another gas, or else a fluid consisting of a gas (such as ambient air) and liquid mixture, the gaseous part being predominantly volume percentage, so that the flow preferably has an essentially gaseous character.

There is also in the transfer path 2 a second heat exchange path 6 and a third heat exchange path 8 placed respectively upstream and downstream of the first exchange path 1 relative to the direction of flow. transfer fluid in the transfer path 2. The second heat exchange path 6 constitutes the evaporator of a refrigeration circuit 4. The third exchange path 8 constitutes the condenser of the same refrigeration circuit 4. The circuit 4 further includes a refrigeration compressor 7 mounted between the outlet of the second exchange path 6 and the inlet of the third exchange path 8 so as to draw the refrigerant gas into the second exchange path 6 to discharge it to the compressed state in the third exchange path 8. The refrigeration circuit 4 also includes an expansion device 9 for expanding the refrigerant between the outlet of the third exchange path 8 and the inlet of the second e exchange route 6.

The transfer path 2 is an open path having, upstream of the exchange paths 6, 1, 8, an inlet path 24 starting with an inlet opening 26, and, downstream of the exchange paths 6, 1, 8, an outlet path 27 terminated by an outlet opening 28. The path is open in particular in the sense that the fluid present at the inlet opening 26 is not, or in any case not necessarily, a fluid coming directly from the outlet opening 28. On the contrary, the transfer fluid entering the path 2 has temperature conditions which are independent of the operating conditions of the device, and in particular the temperature of the transfer fluid in the outlet path 28.

Typically, the orifices 26 and 28 are both connected to the same reserve or source of large capacity, preferably belonging to the environment, such as the external atmosphere, the ambient air of a room, a sea, a lake. , a river, or an artificial reserve such as a basin, or two different sources or reserves. In the example shown, the path 2 is defined by a sheath 29 open at its two ends. The fan motor 3 is installed in the outlet path 27 to operate as an extractor.

The operation of the device which has just been described is as follows, in the case where the temperature ₀ ι at which the useful fluid leaves the use 13 is equal to 35 ° C.

It is assumed that the temperature of the incoming transfer fluid, which is for example atmospheric air, is not controlled.

If the natural temperature of the atmospheric air constituting the transfer fluid is for example equal to 20 ° C., the motor-driven fan 3 is put into operation while maintaining the refrigeration circuit 4 at rest. The useful fluid is cooled from Toi ⁼ 35 ° C to T _u2 = 30 ° C by heat exchange of atmospheric air to 20 ° C with the useful fluid in transfer path 2.

If, as shown in FIG. 1, the transfer fluid has a natural temperature T _A ι = 30 ° C, the refrigeration circuit 4 and the fan motor 3 are put into operation simultaneously. The transfer fluid is first cooled to 'at a temperature T _A2 = 20 ° C by heat exchange with one evaporator 6 of the refrigeration circuit 4 then reheated to a temperature T _A3 = 30 ° C by heat exchange, with the useful fluid circulating in the first exchange path 1, this which allows the useful fluid to be brought back as previously to the desired temperature T _u2 = 30 ° C. Then, the transfer fluid is further heated to the temperature T _A4 = 45 ° C by heat exchange with the condenser 8 of the refrigeration circuit 4. It is remarkable to note that the temperatures T _A ι and T _A3 are substantially equal . Thus, the condenser 8 is just as well cooled by the fluid having been successively cooled then reheated in the path 2 by the second then the first heat exchange path, as it would have been by a possible second path of transfer provided only for the condenser 8. The invention therefore makes it possible to group the three exchange paths 6, 1, 8 in the same transfer path 2 with a single motor-fan 3.

FIG. 2 schematically illustrates an embodiment of the three exchange paths in the form of a single bundle of tubes, of generally parallelepipedal shape, placed across the path 2. The bundle tubes are connected with the rest of the device and with the use 13 so that two end plies of the bundle form one the second exchange path 6 and the other the third exchange path 8 of the refrigeration circuit while a central ply forms the first path exchange 1. It has also been illustrated in FIG. 2 that the bundle of tubes can be of the fin type 22. For the clarity of the figure, only a small number have been represented. fins 22, but in practice the fins are provided at regular intervals, relatively small, all along the tubes. The fins are metal plates having perforations in which the metal tubes are crimped so as to achieve good thermal contact between tubes and fins. One can make such a beam using copper tubes having an initial outside diameter allowing the free engagement of the tubes in the perforations of the fins, then the tubes are enlarged by passing through the tubes a widening tool called "olive". The fins increase the contact surface with the transfer fluid. In addition, the fins constitute thermal conductors having in particular the effect of transferring heat directly between the beam exchange paths. In particular, the fins directly evacuate heat from path 1 to path 6 constituting one evaporator. As shown by dashed lines 16 and 18 in FIG. 2, one can alternatively replace the single beam which has just been described by three similar individual beams, stacked one on the other according to the direction of circulation of the transfer fluid in the transfer path 2. If, unlike the example given in FIG. 1, the temperature Toi leaving the use 13 is for example equal to 25 ° C., that is to say more generally lower than the temperature T ₀₂ = 30 ° C desired in this example for entry into use 13, the useful fluid requires heating instead of cooling. This can be obtained by reversing the direction of flow in path 2, which then becomes that represented by dotted arrows in FIG. 1. This reversal can be obtained by reversing the direction of rotation of the motor-fan 3 or by putting a second motor-fan 31 shown in dotted lines in FIG. 1 into service in the entry path. 24, suitable for producing the aforementioned reverse flow. With such a reverse flow, the inlet and outlet paths 24 and 27 take on outlet and inlet functions respectively, the transfer fluid is firstly heated by the condenser 8 to the temperature of 45 ° C. in the example, then cooled to the temperature of 30 ° C by contact with the useful fluid circulating in the first exchange path 1, then further cooled by the second exchange path 6 constituting one evaporator. The transfer fluid is in this case discharged into the atmosphere with a final temperature of 20 ° C, the atmosphere constituting the cold source of the refrigeration circuit 4 then operating as a heat pump. Figure 3 shows another way to operate the refrigeration circuit as a heat pump capable of heating the useful fluid. A four-way valve 71 is placed at the inlet and at the outlet of the compressor 7, between the latter and on the one hand the second heat exchange path 6 and on the other hand the third heat exchange path 8 The valve 71, shown diagrammatically, allows the compressor 7 to operate either as it was said above by sucking in the second exchange path 6 and by discharging into the third exchange path 8, or on the contrary by sucking in the third exchange path 8 which thus becomes an evaporator and by discharging into the second exchange path 6 which thus becomes a condenser. In this case, there is only one motor-fan 3 for path 2 and this does not need to be able to operate in both directions, since the transfer fluid always flows in the same direction along the path 2. When the second exchange path 6 operates as a condenser, it heats the transfer fluid circulating according to the arrows shown in solid lines in FIG. 1, then the transfer fluid is capable of heating the useful fluid. The refrigeration circuit 4 therefore operates, in this way too, as a heat pump.

Of course, when the refrigeration circuit 4 is at rest, the direction of circulation of the transfer fluid along the transfer path 2 is of no importance.

In the example shown in FIG. 4, the first exchange path 1 is extended upstream relative to the direction of circulation of the useful fluid by a fourth exchange path 14 which is not located in the transfer flow 2 bathing the evaporator 6 and the condenser 8 but in a second transfer flow 21 not coming into contact with the second and third exchange paths 6 and 8. Typically, this second transfer flow 21 is constituted as the first flow transfer 2 by air taken from the atmosphere with a possible addition of drops of liquid such as water. The second flow 21 is set in motion by another motor-fan 32 defining a second transfer path parallel to the first transfer path. To simplify the figure, the sheaths that can be used to channel the transfer flows are not illustrated. This embodiment is useful when it is necessary to modify the temperature of the useful fluid relatively much, for example to bring it back from T ₀₁ = 45 ° C to T _u2 = 30 ° C. In this case, using the example of an ambient temperature T _A ι = 30 ° C, the temperature of the useful fluid is lowered from 45 ° C to T _u3 = 35 ° C by heat exchange with the transfer flow 21 no refrigerated, the refrigerated stream then only having to ensure the passage of the useful fluid from the temperature T _ϋ3 = 35 ° C to T _u2 = 30 ° C as in the previous example. Thus, savings are made on the power consumed by the refrigeration circuit.

FIG. 5 illustrates a practical embodiment of a single bundle of tubes for all the exchange paths of the embodiment of FIG. 4. In the part situated to the right of FIG. 5, all the tubes of the bundle belong to the fourth path exchange 14 traversed by the useful fluid. The transfer flow 21, which crosses this right part of the beam, therefore only encounters tubes traversed by useful fluid which has not yet exchanged heat with the transfer flow 2. The left part of the beam is organized so to form three successive groups of tubes constituting, in the order in which they are encountered by the transfer flow 2, the evaporator 6, the exchange path 1 and the condenser 8. It is seen that a thermal optimization can lead to create, on the left of FIG. 1, a zone 23 where each flow stream of the transfer flow 2 encounters more tubes of the evaporator 6 then fewer tubes of the exchange path 1. In zone 23, the veins flow 23 are therefore further cooled by one evaporator 6. Then, these very cooled veins meet the last tubes 17 that the useful fluid travels in the path 1 before returning to use 13. The useful fluid therefore undergoes additional cooling in these latter tubes 17. The sinuous arrows of FIG. 5 indicate the order in which each fluid runs through the tubes assigned to it. In practice, series-parallel connections are possible to optimize the implementation in terms of exchange performance, pressure losses due to flow, volume and cost of the beam, etc.

The example in FIG. 6 will only be described for its differences from that of FIG. 5. The fourth exchange path occupies only one median group of tubes in the right part of the bundle, and it is disposed between an additional evaporator 61, located upstream, and an additional condenser 81, located downstream. The additional evaporator 61 and the additional condenser 81 belong to a second refrigeration circuit 41, which can be put into operation independently of the circuit 4. For example, the putting into operation of the circuit 41 can be reserved for exceptional cases where it is necessary to assist the circuit 4 when the temperature of the useful fluid is very high at the end of use and / or the ambient temperature is very high.

Of course, the invention is not limited to the examples described and shown. The exchange paths are not necessarily carried out by bundles of tubes. The transfer fluid can be a fluid other than atmospheric air. The useful fluid can be liquid or gaseous. We could modify the embodiments of Figures 5 and 6 by placing for example two successive evaporators upstream of the exchange path 1 and / or of the exchange path 14. For applications of heating the useful fluid, one could provide several successive condensers. The refrigeration circuit (s) may be of a type other than the condensation-evaporation type described. They can in particular be of the absorption, adsorption, Peltier effect type, etc.

The transfer route is not necessarily open in the immediate vicinity of the exchange routes. Pipes or other passages may be necessary to connect at least one of the ends of the transfer path with a source or reserve of large capacity, supplied in particular by the environment.

Claims

1- Device for modifying the temperature of a useful fluid, comprising: a first heat exchange path (1) traversed by the useful fluid and installed in heat exchange relation with a transfer path (2) traversed by a transfer fluid; and

- a refrigeration circuit (4) comprising, for a refrigerant, a second (6) and a third (8) heat exchange path having one of a function of absorption of heat by the refrigeration circuit and one other a heat release function by the refrigeration circuit, at least at certain stages of operation, one of the second (6) and third (8) exchange paths being installed in heat exchange relation with the transfer path ( 2) upstream of the first exchange path (1) so that the temperature of the transfer fluid is modified by heat exchange with the refrigerant before the heat exchange between the transfer fluid and the useful fluid traversing the first path exchange path, characterized in that the transfer path is an open path having an input path upstream of the exchange paths in which the temperature conditions are substantially independent of the operating conditions d u device.

2- Device according to claim 1, characterized in that at least one of the inlet and outlet path is connectable to a reserve of transfer fluid belonging to the environment.

3- Device according to claim 1 or 2, characterized in that said "one of the second and third exchange path "is that by which the refrigeration circuit absorbs heat.

4- Device according to one of claims 1 to 3, characterized in that the transfer fluid is mainly gaseous, in volume percentage.

5- Device according to claim 4, characterized in that the transfer fluid is mainly composed of ambient air, in volume percentage. 6- Device according to one of claims 1 to 5, characterized in that the first exchange path (1) is installed in series between the second (6) and the third (8) exchange path, relative to the direction of flow of the transfer fluid in the transfer path (2).

7- Device according to claim 6, characterized in that, the refrigeration circuit (4) being in operation, the temperature (T _A ) of the transfer fluid upstream of the three exchange paths (6, 1, 8) and the temperature (T _A3 ) of this fluid at the outlet of the first exchange path are approximately equal.

8- Device according to one of claims 1 to

7, characterized by means (31) for reversing the direction of circulation of the transfer fluid in the transfer path (2).

9- Device according to one of claims 1 to

8, characterized by means for circulating the useful fluid in the first exchange path (1) and the transfer fluid in the transfer path (2) while maintaining the refrigeration circuit (4) at rest.

10- Device according to one of claims 1 to

9, characterized in that at least some of the paths exchange (6, 1, 8) are made in the form of groups of tubes belonging to the same bundle of parallel tubes placed in the transfer path.

11-, Device according to one of claims 1 to 9, characterized in that at least some of said exchange paths (6, 1, 8) are made in the form of bundles of tubes, stacked in the transfer path according to the direction of flow of the transfer fluid. 12- Device according to one of claims 1 to

11, characterized in that it comprises thermal conductors, in particular fins (22), interconnecting the exchange paths (6, 1, 8) in the transfer path. 13- Device according to one of claims 1 to

12, characterized in that it comprises, for the useful fluid, a fourth exchange path (14) placed upstream of the first exchange path (1) relative to the direction of circulation of the useful fluid, and in that the fourth exchange path (14) is placed in heat exchange relationship with a second transfer fluid path (21).

14- Device according to claim 13, characterized in that the second (6) and the third (8) exchange path are thermally separated from the second transfer path (21).

15- Device according to claim 13 or 14, characterized in that at least one of the functions of absorption and release of heat from the refrigeration circuit is carried out in two stages, one of which is carried out by an additional exchange path (61) placed in heat exchange relation with the second transfer path (21) in series, relative to the flow of the transfer fluid, with the fourth exchange path (14).

16- Device according to one of claims 1 to 14, characterized in that at least one of the functions of absorption and release of heat from the refrigeration circuit is performed in two exchange paths (61, 6) placed in series in the transfer path (2).