Cabinet with internal heat dissipation system

Abstract

A cabinet (10) with an internal heat dissipation system comprises at least one wall (13, 14, 15) formed by a panel (16) comprising a first plate (17) arranged towards the inside of the cabinet, a second plate (18) arranged towards the outside of the cabinet, and a heat exchange corrugated partition (19) located between the first plate (17) and the second plate (18). The corrugated bulkhead (19) defines a first air circulation vertical channel (20) between the corrugated bulkhead (19) and the first plate (17) and a second air circulation vertical channel (21) between the corrugated bulkhead (19) and the second plate (18), the first vertical channel (20) being part of a first circuit (39) circulating air inside the cabinet and the second vertical channel (21) being part of a second circuit (39) circulating air inside the cabinet. The second vertical channel (21) is part of a second circuit (42) circulating air outside the cabinet.

Description

[0001] This is the specification of an invention patent named "Cabinet with an Internal Cooling System".

[0002] Proprietor: FI.MO. Technology S.p.A.

[0003] Headquartered in: Milan

[0004] The present invention relates to a new metal cabinet with an internal cooling system. In particular, the cabinet is better adapted to accommodate general equipment of an electrical, electronic, chemical, physical or technical nature, the heat generated by which must be dissipated from the cabinet.

[0005] The problem of discharging heat from the interior of a cabinet containing heat-generating equipment is well known. The first solution is to make large holes in the cabinet to allow passive circulation of air inside and outside the cabinet, but this system is often of limited effectiveness and efficiency. Therefore, there have also been proposals to use relatively complex heat exchangers, forced exhaust systems or active air-conditioning systems (refrigerators) inside and outside the cabinet. Whether located inside or outside the cabinet, these systems are generally quite bulky and will reduce the available space in the cabinet.

[0006] Another drawback of systems that force or non-forcibly extract hot air from the cabinet and replace it with fresh outdoor air is that they expose the equipment installed in the cabinet to the external ambient air, which may contain various pollutants and contain, for example, dust, salt deposits, moisture or other general contaminants.

[0007] In the case of active systems such as air conditioners, in addition to being large in size and complex in structure (usually using large centralized systems to connect multiple cabinets), they also require relatively high operating power and frequent and expensive maintenance costs.

[0008] The general object of the present invention is to overcome the drawbacks of the prior art and provide a cabinet with an internal cooling system that is effective, space-saving, durable, relatively cost-effective and low in maintenance costs, and requires only very little energy to operate.

[0009] To achieve this object, a cabinet with an internal cooling system is designed according to the present invention, which is characterized in that the cabinet includes at least one wall formed by panels, the panels including a first plate arranged towards the interior of the cabinet, a second plate arranged towards the exterior of the cabinet, and a heat-exchange corrugated partition located between the first plate and the second plate, and a first vertical air circulation channel is defined between the corrugated partition and the first plate, and a second vertical air circulation channel is defined between the corrugated partition and the second plate, the first vertical channel being part of a first loop for circulating the air inside the cabinet, and the second vertical channel being part of a second loop for circulating the air outside the cabinet.

[0010] To better explain the innovative principles of the present invention and its advantages compared with the prior art, a possible exemplary implementation of applying these principles will be described below with the aid of the accompanying drawings. In the drawings:

[0011] Figure 1 is a front perspective view of a cabinet manufactured according to the present invention;

[0012] Figure 2 is Figure 1 a view of the cabinet shown after removing the access door;

[0013] Figure 3 is a perspective view of a panel of a possible implementation, which forms Figure 1 at least one wall of the cabinet shown;

[0014] Figure 4 is Figure 3 a cross-sectional view along line IV-IV in

[0015] Figure 5 is Figure 3 a partially cut-away perspective view of the panel shown;

[0016] Figure 6 is Figure 3 an exploded perspective schematic view of a region of the panel shown;

[0017] Figure 7 is Figure 3 a perspective schematic view of the panel shown from a top-down perspective;

[0018] Figure 8 is a side view of the cabinet provided by the present invention, in which a possible air flow path is highlighted;

[0019] Figure 9 and Figure 10 are Figure 1 partial perspective views of a possible implementation of the upper part of the cabinet shown, in which some parts of the upper cover are removed.

[0020] Referring to the accompanying drawings, Figure 1 there is shown a cabinet manufactured according to the present invention, which is generally labeled 10. The cabinet 10 preferably has the shape of a parallelepiped and the front wall can be opened to form a door 11 for accessing the internal space 12. For example, as can be seen in Figure 2 , the internal space 12 is used to accommodate and protect the heat-generating components (not shown as they can be components of any nature, such as electrical, electronic, chemical, physical or technical general equipment) in the cabinet, and these components must dissipate heat by transferring the heat out of the cabinet.

[0021] Those skilled in the art can easily imagine that the internal space 12 can be completely empty or can be provided with shelves, racks, guide rails, etc., depending on the specific requirements of the items placed in the cabinet. According to the present invention, at least one cabinet wall (preferably, at least the rear wall 15 or at least two side walls 13, 14; more preferably, the side walls 13, 14 and the rear wall 15) comprises or consists entirely of a gas-gas heat exchange plate. Figure 3 And the figure below it shows a possible and advantageous embodiment of such a panel.

[0022] According to this embodiment, one side of the panel (generally labeled 16) comprises a first plate 17 and the other side comprises a second plate 18. These two plates 17 and 18 are preferably made of a metallic material (such as a steel plate or an aluminum plate), and their thickness can be adapted to other elements in the structure to jointly ensure that the cabinet wall reaches the required strength.

[0023] When the panel forms the cabinet wall, the first plate 17 is arranged towards the inside of the cabinet, and the second plate 18 is arranged more towards the outside of the cabinet. More preferably, the first plate 17 forms the inner surface of the corresponding cabinet wall, and the second plate 18 forms the outer surface of the corresponding cabinet wall.

[0024] From Figure 4 As can be seen from the IV-IV section shown, the two plates 17 and 18 are separated by a corrugated partition 19, which is arranged between the first plate 17 and the second plate 18 to form a first vertical channel 20 between the corrugated partition 19 and the first plate 17 and a second vertical channel 21 between the partition 19 and the second plate 18.

[0025] The partition 19 is made of a material with appropriate high thermal conductivity, preferably a metallic material, so as to achieve the required heat transfer between the air in the first channel 20 and the air in the second channel 21. The partition 19 is preferably made of a metal plate with a suitable shape. For example, the material of the partition can be aluminum.

[0026] Therefore, it can be clearly seen that the partition 19 forms a heat exchange partition between the air in the first channel 20 and the air in the second channel 21.

[0027] The corrugations of the partition 19 can be various shapes capable of forming the vertical channels 20 and 21. Especially in the shown embodiment, the corrugations are preferably in a zig-zag shape with sharp edges, so as to form channels 20 and 21 with a cross-section approximately in the shape of a triangle. The advantage of this structure is simple production, good heat exchange effect, and the panel has the required strength and stiffness. But this does not exclude that other corrugation shapes can also be used. For example, it can also be designed as a shape without sharp edges, such as a sine wave shape or a similar shape.

[0028] The partition 19 can also consist of several different elements, such as appropriately shaped strips placed side by side. For example, modular elements with a certain number of corrugations can be used, and the modular elements are placed side by side in the space between the plates, thus forming the complete partition 19.

[0029] As can be clearly seen below, the panel 16 forms an air-to-air exchanger. The first channel 20 is part of the first circuit 39, which circulates the air inside the cabinet; the second channel 21 is part of the second circuit 42, which circulates the air from outside the cabinet.

[0030] To assist, promote, or control the air circulation, suitable circulation fans can also be installed in one or both of the circuits 39 and 42. If necessary, the fans can also be assisted in control by manipulating the control circuit according to the temperature to be maintained in the cabinet.

[0031] In particular, as will be further described below, the two air circulation circuits can include fans located at appropriate positions inside the cabinet (e.g., preferably located at the upper part or the cover of the cabinet), so as to force the movement of the air inside the cabinet, make the internal air circulate through the first channel 20 of the panel, and suck in the air from outside the cabinet, force the external air to circulate through the second channel 21, and then re-discharge it outside the cabinet, while always keeping the two circulation circuits separate.

[0032] For example, from Figure 4 the cross-sectional view shown, it can be seen that the panel preferably has closed sides 22 and 23 to increase the rigidity of the panel and make it easier to be fixed at the edges to form the structure of the cabinet.

[0033] For example, to form the two sides 22 and 23, profiles with a U-shaped or rectangular longitudinal section can be used. Or one or both of the sides of the plates 17 and 18 have appropriate bends and shaping, so that the plates are connected to each other along these edges while keeping a gap between the plates to accommodate the corrugated partition 19.

[0034] For example, from Figure 4 it can be clearly seen that the two sides of a plate (in the case shown in the figure, it is the outer plate 18) can be folded into a U-shape, and the free ends 24, 25 (inner or outer) of the U-shaped sides are connected to the corresponding planar sides of another plate.

[0035] In any case, it is advantageous to enclose the sides with two general box-shaped profiles to form two regions 51 and 52. For example, to provide additional structural stiffness to the panel and / or facilitate its assembly to form the cabinet. This also provides additional structural strength to the cabinet formed by the panel 16.

[0036] In addition, the regions 51 and 52 on the two sides of the panel can be easily isolated from the channels 20 and 21, and holes can be easily drilled therein to fix the panel to form a cabinet or attach accessories to the panel (such as rails or brackets inside the cabinet), without worrying about the air circulation channels being drilled and requiring airtight sealing.

[0037] Two partition walls 26, 27 extend transversely between the two plates 17, 18 and are parallel to the closed edges 22, 23 of the panel. These two partition walls 26, 27 can be used to form these regions 51 and 52 separated from the channels. These partition walls 26, 27 can be integrally formed with the two side edges of the partition 19 or can be part of an additional profile.

[0038] As can be clearly seen from Figure 4 these two regions 51 and 52 can also be formed by a special profile having a rectangular cross-section fixed to the panel edges between the two plates 17 and 18.

[0039] For example, as can be seen from Figure 3 and Figure 5 it can be seen that ( Figure 5 the middle plate 17 is offset relative to the rest of the panel to schematically show the possible internal structure of the panel). In a possible preferred embodiment of the air circulation system according to the present invention, the first plate 17 on the panel 16 can include a first upper groove 28 and a second lower groove 29, which communicate with the upper end and the lower end of the first vertical channel 20 near the inside of the panel respectively.

[0040] Therefore, the first and second grooves 28, 29 are close to the upper and lower edges of the panel respectively.

[0041] For example, as can be seen from Figure 5 the vertical length of the partition 19 can be shorter than the total height of the panel 16 so as to leave gaps on the panel above and below the partition 19, the purpose of which will be clear later.

[0042] As can also be seen from Figure 5 at the upper and lower ends of the channel 20 behind the upper and lower grooves 28, 29 are preferably sealed with plugs 30 and 31 (such as plastic material). As shown by the arrows, the air flow can enter from the upper groove 28, pass downward through the vertical channel 20, and flow out from the lower groove 29, thereby obtaining the corresponding part of the first air circulation loop in the air-air exchanger. The plugs (such as made of plastic) are preferably directly installed at both ends of the pipeline.

[0043] The first groove 28 is used to receive the air inside the cabinet and let it enter the upper end of the channel 20. The second groove 29 is used to introduce the air after passing through the channel 20 into the cabinet.

[0044] For example, from Figure 5 and Figure 6 , it can be seen that the outer panel 18 preferably has a lower groove 32 facing the outside of the panel (i.e., located outside the cabinet, as shown in Figure 1 ). The lower end of the channel 21 communicates with the groove 32, preferably below the plug 31, and the plug 31 closes the first channel 20 at the bottom. The communication can be achieved through the area 34 of the panel below the lower end of the channel 21, and this area is the end point of all the channels 21.

[0045] The edge or lower region of the panel 16 can be closed, so that the air flowing downward in the channel 21 can only flow out through the groove 32. For example, the lower edge of the panel can have a closed reinforcing wall 46, and the wall 46 is located between the plates 17 and 18. For example, the wall 46 can be composed of a U-shaped wall fixed between the plates and forms the lower edge of the panel as shown in the figure. Alternatively, the lower edge can also be closed after the panel is installed to form the cabinet.

[0046] On the other hand, the upper end of the second channel 21 is preferably open from the top of the upper edge region of the panel, and this region includes the upper channel 33. For example, in the form of a groove or hole, the groove or hole is arranged side by side along the upper edge of the panel made of the reinforcing wall 47 and is placed between the plates. For example, the wall 47 can be composed of a U-shaped wall fixed between the plates along the upper edge of the panel as shown in the figure.

[0047] As Figure 5 indicated by the arrow in, in the said panel, the air flow can enter from the upper channel 33, flow downward through the vertical channel 21, and flow out from the lower groove 32, thereby forming the corresponding part of the second air circulation loop of the air-air exchanger.

[0048] For example, all or part of the said grooves 28, 29, 32 can be a plurality of holes opened on the corresponding plates 17, 18, arranged horizontally side by side and communicating with the corresponding channels 20 or 21 on the other side of the plate. For example, each of the plurality of holes can correspond to a channel on the other side of the corresponding plate. Screens, filters, and / or grilles can also be provided on the grooves to prevent foreign objects (dust, air with too high humidity, etc.) from entering the internal air circulation loop.

[0049] Figure 6 The lower structure of the panel 16 is also schematically shown (the wall 46 is removed for clarity), while Figure 7 the upper structure of the panel 16 is schematically shown.

[0050] In particular, in Figure 7 , it can be clearly seen that the upper channel 33 is connected to the open upper end of the second channel 21, and the upper end of the first channel 20 has a corresponding plug 30.

[0051] Figure 8 The flow of air entering the cabinet 10 is schematically shown by arrows, as well as the case where the cabinet is formed by one of the above-mentioned panels 16.

[0052] As described above, in order to manufacture the cabinet 10, according to the present invention, the heat exchange plates 16 can be installed on one, two or preferably three walls of the cabinet. The fan can also force the air to circulate in the two circulation loops 39 and 42 of the panel 16 to perform the required heat exchange between the inside and outside of the cabinet. In particular, in the cabinet embodiment described herein, it has been found that it is very advantageous to place the fan directly inside the cabinet structure.

[0053] More preferably, the first gap 35 in the cabinet is connected to the air outlet of the first fan 37 that sucks air from inside the cabinet. The fan 37 is preferably a centrifugal fan.

[0054] The first gap 35 is connected to the first slot 28 for sending the air sucked by the first fan 37 and forced into the gap 35 into the first vertical channel 20. After the air passes through the first vertical channel 20, it can re-enter the internal space of the cabinet through the lower slot 29 just above the bottom plate inside the cabinet.

[0055] In this way, the first circulation loop 39 is formed, and the first circulation loop 39 is Figure 8 shown by a continuous arrow passing through one of the panels 16 (the circulation loops of all the panels 16 forming the cabinet are similar).

[0056] Advantageously, the first gap 35 is located on the top wall inside the cabinet, and its periphery is directly open to the slot 28 so as to be closely connected to the slot 28 and introduce the air sucked by the fan 37 (the fan is preferably located at the central position of the top wall of the cabinet). At least part of such a fan can be inserted into the first gap 35, so that the air intake port 41 is opened on the inner side of the top wall of the cabinet, and the exhaust port 43 is in the first gap 35.

[0057] The cabinet preferably further has a second gap 36, and the second gap 36 is connected to the discharge port 44 of the second fan 40 that sucks air from outside the cabinet.

[0058] The second gap 36 is preferably parallel to the first gap 35 and extends above the first gap 35.

[0059] The second gap 36 is connected to the channel 33 at the upper edge of the panel 16 to force the air sucked by the second fan 40 into the gap 36. More preferably, at least part of the second fan 40 is located in the gap 36 so as to directly discharge the air into the gap. The second fan 40 is preferably located at the center of the top wall of the cabinet and above the first fan 37. The two fans can have vertical rotation axes, and the two fans can be coaxially arranged.

[0060] For example, it can be schematically seen from Figure 8 that the upper end of each panel 16 used in the cabinet preferably faces directly towards the gap 36, so as to facilitate the simple and direct connection of the intake channel 33 and the vertical channel 21.

[0061] Air passes through the channel 33 along the vertical channel 21, undergoes the required heat exchange with the air in the first vertical channel 20 through the partition 19, and then leaves the cabinet through the external groove 32. In this way, the second circulation loop 42 is formed, as Figure 8 shown by the dashed arrow in the panel 16 (the circulation of all the panels 16 constituting the cabinet is similar).

[0062] Advantageously, the fan 40 sucks air from the external environment through the air inlet 38 in the box-shaped cover plate 45, and the box-shaped cover plate 45 is placed on the external top cover of the cabinet, and the top cover may be equipped with a suitable known filter. For example, the filter can be used to prevent dust inhalation, or can be made into a labyrinth shape to prevent rainwater from entering.

[0063] Figure 9 and Figure 10 also schematically shows the preferred structure for connecting the upper panels of the cabinet, which has various required air channels.

[0064] In Figure 9 the cover plate 45 is removed to show the lower suction fan 40, while in Figure 10 the conveying cover 48 constituting the external top cover of the cabinet and the side wall and upper wall of the gap 36 are further removed to show the upper channel 33 usually located in the gap 36, which allows air to enter the channel 21 from the gap 36.

[0065] Advantageously, the air circulation fans in the two circulation loops can also be equipped with electrical or electronic control circuits (schematically shown as 49 in Figure 8 ) to control their starting and / or rotational speed. According to the description herein, those skilled in the art can easily imagine such a control circuit. In particular, the circuit 49 can also include one or more temperature sensors 50 for measuring the temperature inside the cabinet, so as to start or rotate the fan at an appropriate speed according to the temperature detected by the sensors inside the cabinet. For example, keeping the temperature inside the cabinet below a predetermined threshold value, while not starting the fan unnecessarily when not necessary.

[0066] For example, there can be two sensors 50, one placed at the bottom of the cabinet and the other at the top of the cabinet, so that at least the rotational speed of the internal circulation fan can be adjusted proportionally according to the temperature difference measured by the two sensors. For example, a well-known differential amplifier circuit can be used to detect the temperature difference, which is not difficult for those skilled in the art to imagine.

[0067] Now, we can clearly see how to achieve the preset goal. Despite its simple structure, it can maintain the best heat exchange. The cabinet has a strong ability to mitigate internal temperature changes and can withstand the heat dissipation of the equipment installed in the cabinet and the temperature changes of the environment where the cabinet is located. According to the present invention, heat regulation is achieved by the panel, which can basically form the structure of the cabinet itself or can be easily used to form the side wall and / or rear wall of the cabinet. Therefore, the heat exchange system occupies very little space and does not cause waste of space inside and outside the cabinet.

[0068] Advantageously, the internal air circulates downward in the panel, and the external air is also pumped downward, thus forming a gas-gas exchanger with a "co-current" structure.

[0069] The hot air in the upper part of the interior has a lower density. Through the partition on the side plate, the internal hot air contacts the external cold air, causing the former to cool faster and its density to increase, so that it descends faster. This promotes the air circulation inside the cabinet. This also reduces the power consumption of the internal circulation fan. By forcing the air circulation (the flow rate can be dynamically adjusted) of the internal environment through the channels and partitions on the side plate (the side plate itself can also be a structural member of the cabinet, which can be clearly seen from the description), the temperatures of the lower and upper parts of the cabinet are kept consistent. Inhaling the external air and pumping it outside the partition of the side plate can effectively improve the dissipation ratio of the cabinet. Changing the pumping flow rate of the external air will also change the cooling capacity of the cabinet.

[0070] In addition, there is no hydraulic or pneumatic connection between the inside and outside of the cabinet, and there is no need for air exchange between the inside and outside, thus avoiding the entry of pollutants. The closed door can easily achieve airtightness, and the same is true for the entire cabinet structure.

[0071] In addition, due to the simple structure of the cabinet, the energy consumption required for production is relatively low. The processing of metal parts can also be easily completed by low-energy-consuming machines. For example, metal plate cutting can be completed with a simple punching machine, without high-absorption equipment such as a laser cutting system.

[0072] The components that make up the cabinet are assembled quickly and simply. For example, they can be assembled by bolts or rivets without using welding.

[0073] For example, the support structure of the cabinet can be easily made of extruded aluminum profiles, which are connected together by bolts or rivets, as can be easily imagined by those skilled in the art. Welding is not required. The side plates, top plates, bottom plates and frames of the door can be easily connected to the profile plates by bolts or rivets, and the profile plates have also been fixed to the frame by specific bolts or rivets beforehand. In this case, the bolt connection can be achieved inside the structure, so that if there is a lock on the door, the panel cannot be disassembled.

[0074] With the above structure, since no special mechanical equipment is required, a nearly or fully recyclable system (even more than 99% of its weight) can be obtained with only a moderate amount of energy.

[0075] Obviously, the above description of the embodiments applying the innovative principle of the present invention is by way of example to illustrate such an innovative principle, and thus cannot be regarded as limiting the scope of the patent claimed by the present invention.

[0076] For example, if needed, the cabinet can easily be made of materials suitable for outdoor all-weather arrangements (such as stainless steel or treated and / or painted metal). A special air circulation with no air exchange between the outside and the inside can still prevent the entry of moist air or environmental pollutants.

Claims

1. Cabinet with an internal cooling system, characterized in that, The cabinet includes at least one wall (13, 14, 15) formed by a panel (16), the panel (16) including a first plate (17) arranged towards the inside of the cabinet, a second plate (18) arranged towards the outside of the cabinet, and a heat exchange corrugated partition (19) located between the first plate (17) and the second plate (18), so as to define a first vertical air circulation channel (20) between the corrugated partition (19) and the first plate (17), and a second vertical air circulation channel (21) between the corrugated partition (19) and the second plate (18), the first vertical channel (20) being part of a first loop (39) for circulating air inside the cabinet, and the second vertical channel (21) being part of a second loop (42) for circulating air outside the cabinet.

2. The cabinet according to claim 1, wherein The panel (16) includes a first upper groove (28) and a second lower groove (29) located on the first plate (17), the first upper groove (28) and the second lower groove (29) communicating with the first vertical channel (20) respectively at positions close to the upper end and the lower end, the first groove (28) receiving air from inside the cabinet, and the second groove (29) introducing air into the cabinet to form the first air circulation loop (39).

3. The cabinet according to claim 2, characterized in that, At opposite upper and lower ends within the panel (16), the first vertical channel (20) is closed by plugs (30, 31).

4. The cabinet according to claim 1, characterized in that, The first and / or second loop (42, 39) includes fans (40, 37) for forcing air circulation.

5. The cabinet according to claims 2 and 4, characterized in that, The cabinet includes a first gap (35) which is connected to the air outlet of a first fan (37) that sucks air from inside the cabinet, and the first gap (35) is also connected to the first groove (28) so as to send the air sucked by the first fan (37) into the first vertical channel (20).

6. The cabinet according to claim 5, characterized in that The first gap (35) is located on the top wall of the cabinet, and its periphery is directly open towards the first groove (28).

7. The cabinet according to claim 5, wherein The first fan (37) is at least partially located within the first gap (35) to have a suction port (41) opening on the inner top wall of the cabinet and an exhaust port (43) located within the first gap (35).

8. The cabinet according to claim 1, characterized in that, The panel (16) includes an external groove (32) located on the second plate (18) and communicating with the lower end of the second vertical channel (21), and a channel (33) located at the upper edge of the panel (16) and communicating with the upper end of the second vertical channel (21), the channel (33) receiving air from outside the cabinet, and the external groove (32) discharging air to the outside of the cabinet to form the second air circulation loop (42).

9. The cabinet according to claims 4 and 8, characterized in that, The cabinet includes a second gap (36) which is connected to the exhaust port of a second fan (40) that sucks air from outside the cabinet, and the second gap (36) is connected to the channel (33) at the upper edge of the panel (16) so as to send the air sucked by the second fan (40) into the second vertical channel (21).

10. The cabinet according to claim 9, characterized in that, The second gap (36) is located on the top wall of the cabinet, and the channel (33) opens directly therein.

11. The cabinet according to claim 9, wherein, The second fan (40) is installed on the top wall of the cabinet so as to have a suction port (38) connected to the outside of the cabinet and a discharge port (44) located within the second gap (36).

12. The cabinet according to claims 5 and 9, characterized in that, The second gap (36) is parallel to the first gap (35) and extends above the first gap (35).

13. The cabinet according to claim 1, wherein, The cabinet wall formed by the panel (16) is the rear wall (12) of the cabinet.

14. The cabinet according to claim 1, characterized in that, The cabinet wall formed by the panel (16) is at least two side walls (13, 14) of the cabinet.

15. The cabinet according to claim 1, characterized in that, The cabinet wall formed by the panel (16) is at least two side walls (13, 14) and the rear wall (12) of the cabinet.

16. The cabinet according to claim 4, characterized in that The cabinet includes a temperature measurement sensor (50) within the cabinet and a control circuit (49) connected to the air circulation fans in the first air circulation loop (39) and / or the second air circulation loop (42), the control circuit (49) being configured to receive temperature measurement values from the sensor (50) and control the fans based on the measurement values.

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