Heat exchanger

Abstract

A heat exchanger (10) comprises a containing body (11) provided with an inlet (12) for the humid air and with an outlet (13) for the dried air, between which an air path (Pl) develops, and, disposed in succession along said air path (Pl), a heat pre-exchange unit (14) of the air / air type in which the incoming humid air is able to exchange heat with the dried air and a heat exchange unit (15) of the air / coolant type in which the humid air is cooled by exchanging heat with a coolant in order to condense the water present therein and obtain the dried air, wherein said heat pre-exchange unit (14) comprises first humid air passage channels (18) alternating with dried air passage channels (19), respectively separated by a plurality of walls (17), and said heat exchange unit (15) comprises second humid air passage channels (21) interspersed with coolant passage channels (22).

Description

[0001] “HEAT EXCHANGER”

[0002] FIELD OF THE INVENTION

[0003] The present invention concerns a heat exchanger comprising a heat exchange unit of the air-coolant type, suitable to be used even with a slightly flammable or flammable coolant fluid. This heat exchanger can for example be used to dry compressed humid air.

[0004] BACKGROUND OF THE INVENTION

[0005] There are known heat exchangers that comprise a containing body into which humid and hot air is introduced, and from which the air is emitted after it has been dried along a drying path.

[0006] Along this path there are generally provided a heat pre-exchange unit of the air / air type in which the incoming compressed humid air exchanges heat with the outgoing dried air, and a heat exchange unit of the air / coolant type in which the compressed humid air is cooled by exchanging heat with a refrigerating circuit in which a coolant fluid flows in order to lower its temperature to a condensing point, or dew point.

[0007] The dried and cooled air is then conveyed toward the outlet of the containing body, and a condensate separator is disposed downstream of the second heat exchange unit which separates and expels the condensed water from the compressed air.

[0008] The heat pre-exchange and exchange units are generally made of aluminum, with a technology called “bar and plate”. The humid air passage channels are alternating with the dry air passage channels in the pre-exchange unit and with the coolant passage channels in the exchange unit, and they are separated from the dry air passage channels and from the coolant passage channels, respectively, by means of a thin aluminum foil.

[0009] An example of a known heat exchanger with vertical development is described in patent EP 1464887 in the name of the Applicant. Another known heat exchanger with vertical development is described in US 2014007606 Al .

[0010] US 2007 / 169916 Al concerns a plate heat exchanger comprising a plurality of plates that in adjacent pairs form passage channels for a first and a second fluid that exchange heat by flowing counter current on respective opposing surfaces of a plate, worked in relief to increase the contact area, wherein between each pair of plates there is provided a predefined path to discharge any liquid leaks to the outside.

[0011] CN205227939U describes a double wall heat exchanger having a first and a second channel for the passage of respective fluids, each provided with its own contour wall, which walls are disposed in contact with each other.

[0012] US4607684 describes a heat exchanger of the horizontal development type for a combustion engine system, which is used submerged within a liquid fuel tank.

[0013] In the event that, due to corrosive effects or general malfunctions of the heat exchanger, there is a perforation of the thin layer of aluminum that separates the compressed air from the coolant fluid, depending on the operating pressures one of either the air or the coolant can escape from the respective passage channel, entering into the adjacent one.

[0014] In particular, the following situations may occur: a) when the pressure of the coolant fluid is lower than the pressure of the compressed air, the compressed air enters the coolant circuit; b) when the pressure of the coolant fluid is higher than the pressure of the compressed air, the coolant enters the compressed air circuit.

[0015] At present, non-flammable and non-toxic coolant fluids are generally used, classified in the sector as category Al, so that any damage or perforation in the aluminum foil does not pose any risk to human safety in relation to the use and installation of the known heat exchanger.

[0016] Recent changes to regulations in the field of fire prevention, however, leave scope for the use of slightly flammable or highly flammable coolants (categorized as A2L or A3) in heat exchangers for drying compressed air.

[0017] In particular, class A2L coolants, non-toxic and slightly flammable, are gaining ground since they represent a sustainable solution with low global warming potential and require much more energy to catch fire than most class A3 coolants.

[0018] In the event that a class A2L or A3 coolant fluid is used, situations such as those described above can become potentially hazardous to the user. In situation a), in fact, when the compressed air enters the coolant circuit, a stoichiometric ratio can be achieved in the latter such that a combustion can start and, since there is a compressor along the refrigerating circuit, it can become a source of ignition. In situation b), on the other hand, a stoichiometric ratio can be achieved suitable to start a combustion inside the compressed air circuit, over which there is no control whatsoever, and in the presence of a free flame or possible conditions suitable for ignition, an ignition cannot be excluded. There is therefore the need to perfect a heat exchanger that can overcome at least one of the disadvantages of the state of the art.

[0019] To do this, it is necessary to resolve the technical problem of preventing the occurrence of conditions that can lead to the start of a combustion in the coolant or compressed air circuit in the event of possible damage to or perforations in the separation foil.

[0020] In particular, one purpose of the invention is to provide a heat exchanger that allows to use both non-flammable coolants and also slightly flammable or flammable type coolants in a manner that is safe for the user.

[0021] Another purpose of the present invention is to provide a heat exchanger that allows to recover any leaks of coolant fluid in a simple and safe manner.

[0022] Another purpose of the invention is to perfect a heat exchanger that allows to restore its operation in the event of any leaks, without risks to the user.

[0023] Another purpose of the invention is to provide an efficient and compact heat exchanger. The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

[0024] SUMMARY OF THE INVENTION

[0025] The present invention is set forth and characterized in the independent claim; the dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

[0026] In accordance with the above purposes and to resolve the technical problem described above in a new and original way, also achieving considerable advantages compared to the state of the prior art, a heat exchanger according to the invention comprises, located in succession with respect to each other along an air path between an inlet for the humid air and an outlet for the dried air, an air / air heat preexchange unit and an air / coolant heat exchange unit.

[0027] The heat pre-exchange unit is connected on one side to the inlet for the humid and compressed air, and on the other side to the heat exchange unit, in which the humid air is cooled by means of the coolant in order to condense it and separate the condensate from the dried air.

[0028] Means for collecting the condensed water can be disposed underneath the heat exchange unit.

[0029] The heat exchange unit is also provided with respective inlet and outlet apertures for a coolant, which can be connected to a refrigerating circuit along which a compressor and a condenser can be disposed, in a known manner, in which the heat exchange unit acts as an evaporator. Preferably, the inlet and outlet apertures for the coolant are located on a same side of the heat exchange unit.

[0030] The heat pre-exchange unit comprises second humid air passage channels alternating with dried air passage channels, separated from each other by a wall, made in particular of aluminum foil. In particular, the pre-exchange unit can comprise a plurality of walls disposed parallel and spaced apart from each other so as to define the humid air and dried air passage channels.

[0031] The heat exchange unit comprises humid air passage channels and coolant fluid passage channels separated by walls.

[0032] According to some embodiments, both the heat pre-exchange unit and also the heat exchange unit are manufactured using “bar and plate” technology.

[0033] According to one aspect of the invention, the heat exchange unit comprises safety chambers and safety compartments disposed on each of the sides of each of the coolant passage channels facing a respective humid and / or dried air passage channel. The air passage channels and the coolant fluid passage channels are separated from each other by two respectively facing walls that delimit between them a chamber or a respective intermediate safety compartment.

[0034] That is to say, the two facing walls of the respective passage channels for the fluid and the coolant are separated and spaced apart from each other. This solution allows to keep the air circuit and the coolant circuit completely separate, even in situations of potential damage to one of the separation walls between air and coolant passage channels.

[0035] According to another aspect of the invention, the safety chambers and compartments are connected to a common safety collector which is able to convey any coolant leaks outside the heat exchange unit and allow to drain the coolant outside the heat exchanger by means of draining means.

[0036] Preferably, the safety collector is disposed on a side of the heat exchange unit that is opposite the side on which the inlet aperture and the outlet aperture for the coolant are located. This solution advantageously allows to be able to collect any losses of coolant present in the safety compartments and chambers, without needing to provide a ring for conveying the leaks which surrounds the entire heat exchange unit. According to another aspect of the invention, the safety chambers and compartments that are disposed on each of the sides of one of the coolant passage channels are separated from and independent of each other. The only common connection point is in fact given by the safety collector.

[0037] According to one aspect of the invention, the second humid air passage channels, the safety chambers and the coolant passage channels extend along planes that are parallel to each other, in particular vertical planes.

[0038] According to another aspect of the invention, the length of the safety chambers in a vertical direction is greater than the respective adjacent coolant passage channels, so as to guarantee an isolation of the latter for the entire space occupied by them.

[0039] According to another aspect of the invention, the coolant passage channels are closed at the upper and lower part by respective upper and lower walls, which in turn delimit one side of the upper and lower safety compartments.

[0040] The upper and lower safety compartments extend in a substantially horizontal direction, transversally to the safety chambers, and are connected to the safety collector on one side.

[0041] The safety collector can advantageously be located to the side of the air / coolant heat exchange unit.

[0042] According to some embodiments, the safety chambers and / or compartments can be empty, or contain a heat transfer medium inside them, such as water / glycol water or a phase change material (PCM). In this case, it is possible to optimize the heat exchange. Furthermore, the use of the phase change material also allows to achieve energy savings, thanks to its ability to accumulate liquid-solid phase change energy.

[0043] According to another aspect of the invention, the heat exchange unit comprises an inlet and an outlet for the coolant which are located in correspondence with a lower and upper zone, respectively, of the heat exchange unit, internally with respect to the safety compartments. The coolant fluid follows a path in counter current with respect to the compressed air, so as to absorb most of the heat from the latter, cooling it sufficiently so that the humidity present in it condenses and can be recovered.

[0044] The path of the coolant fluid can be C-shaped or have a serpentine development, in which respective upper and lower segments act as collectors and place the respective coolant passage channels in communication.

[0045] In accordance with another aspect of the present invention, the heat preexchange and exchange units are disposed vertically aligned on each other so that the compressed humid air at entry can pass directly through them without undergoing any deviation in path. In other words, the air passage channels in the pre-exchange and exchange units are vertically aligned and placed in continuity.

[0046] According to some embodiments, in correspondence with the junction zone between the pre-exchange and exchange units, dividing walls are provided that close part of the first air passage channels at the lower part, and delimit the safety chambers at the upper part.

[0047] Both the dried air passage channels and also the coolant passage channels are closed at the upper and lower part by respective walls.

[0048] According to some embodiments, in the heat pre-exchange unit, the first humid air passage channels have substantially the same depth as the dried air passage channels.

[0049] According to some embodiments, in the heat exchange unit, the second humid air passage channels have substantially the same depth as the coolant passage channels, and preferably equal to approximately half of the width of the passage channels of the pre-exchange unit. This embodiment allows to maintain a compact conformation with small overall dimensions, comparable to those of a traditional heat exchanger, while increasing the versatility and the field of application of the heat exchanger according to the invention. DESCRIPTION OF THE DRAWINGS

[0050] These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein: - fig. 1 is a partly sectioned three-dimensional view of a heat exchanger according to the present invention;

[0051] - fig. 2 is a three-dimensional view of the heat exchange units of the heat exchanger of fig. 1;

[0052] - fig. 3 is a lateral view of fig. 2; - fig. 4 is a view of the heat exchanger of fig. 1 sectioned along the section line AA indicated in fig. 3;

[0053] - figs. 5-7 are section views of the exchange units of the heat exchanger along the section lines BB, CC, DD of fig. 3;

[0054] - fig. 8 is a partial view of the heat exchanger of fig. 3 sectioned along the plane ; - figs. 8a and 8b are enlarged details of fig. 8.

[0055] We must clarify that the phraseology and terminology used in the present description, as well as the figures in the attached drawings also in relation as to how described, have the sole function of better illustrating and explaining the present invention, their purpose being to provide a non-limiting example of the invention itself, since the scope of protection is defined by the claims.

[0056] To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications. DESCRIPTION OF SOME EMBODIMENTS OF THE PRESENT INVENTION

[0057] With reference to fig. 1 , this shows a heat exchanger 10 according to the present invention, suitable to cool a gaseous flow, for example compressed humid air, in order to remove the humidity present therein and obtain dried air.

[0058] The heat exchanger 10 comprises a containing body 11 provided with an inlet 12 for the humid air and an outlet 13 for the dried air, between which an air path

[0059] Pl develops.

[0060] The heat exchanger 10 comprises - disposed in succession along the air path P 1

[0061] - a heat pre-exchange unit 14 of the air / air type in which the incoming humid air is able to exchange heat with the dried air before it reaches the outlet 13, and a heat exchange unit 15 of the air / coolant type in which the humid air is cooled by exchanging heat with a coolant in order to condense the water present therein and obtain the dried air. The coolant can be of the non-toxic and non-flammable type, indicated with category Al, as in traditional heat exchangers, or of the slightly flammable type A2L or flammable type A3.

[0062] Below the heat exchange unit 15, condensed water collection means 16 can be provided, which can be connected to condensate discharging means, of a known type and not shown.

[0063] The dried air downstream of the heat exchange unit 15 can be made to pass through a conveying duct 29 toward the heat pre-exchange unit 14.

[0064] The heat pre-exchange unit 14 comprises first humid air passage channels 18 alternating with dried air passage channels 19, which are separated by a plurality of walls 17 disposed parallel and spaced from each other substantially vertically.

[0065] The walls 17 can be metal plates, for example made of aluminum.

[0066] According to some embodiments, the dried air can enter the heat pre-exchange unit 14 and then the dried air passage channels 19 through an inlet 20 for the dried air located in a lower zone, and flow counter current with respect to the humid air toward the outlet 13 disposed in an upper zone so as to guarantee maximum air-to- air heat exchange efficiency.

[0067] The humid air passage channels 18 can be placed in communication with the inlet 12 for the humid air by means of a collector 30 able to allow the distribution of the air entering each of them. The heat exchange unit 15 comprises second humid air passage channels 21 interspersed with coolant passage channels 22.

[0068] The coolant passage channels 22 develop from an inlet 23 to an outlet 24 for the coolant, which can be connected to a refrigerating circuit of a known type, not shown, along which a compressor and a condenser can be disposed in a known manner.

[0069] According to some embodiments, the coolant follows a “C” or “U” shaped or serpentine path P2; in this case, suitable diverter elements can be provided in the coolant passage channels 22. The second humid air passage channels 21 are connected to the first humid air passage channels 18 on one side, and on the opposite side they are placed in communication with the conveying duct 29 by means of which the dried air exiting from the heat exchange zone 15 is conveyed toward the inlet 20 for the dried air. The heat pre-exchange and exchange units 14, 15 are vertically aligned on each other so that the first 18 and second 21 humid air passage channels are substantially continuous and aligned. This embodiment solution allows to keep the overall dimensions contained, since it is not necessary to provide intermediate connection ducts between the humid air passage channels 18, 21. In particular, the heat pre-exchange unit 14 is disposed above the heat exchange unit 15.

[0070] In this case, the inlet 12 for the humid air and the outlet 13 for the dried air can be disposed in proximity to each other in an upper zone of the containing body 11.

[0071] In accordance with the invention, the heat exchanger 10 comprises safety chambers 25 and safety compartments 26 disposed adjacent to each of the sides of each coolant passage channel 22 facing a respective humid air 18 and / or dried air 19, 29 passage channel or duct.

[0072] According to some embodiments, the safety chambers 25 and compartments 26 are connected to a common safety collector 27 (figs. 1 and 4) able to convey and collect any coolant leaks outside the heat exchange unit 15. The safety collector 27 can comprise an aperture 28 connectable to draining means to allow the coolant to be drained outside the heat exchanger 10.

[0073] According to some embodiments, the safety collector 27 can be disposed in an intermediate position between the heat exchange unit 15 and the conveying duct 29.

[0074] Preferably, the safety collector 27 is disposed on the opposite side of the heat exchange unit 15 with respect to the inlet 23 and outlet 24 for the coolant.

[0075] As can be observed in figs. 8, 8a, 8b, each coolant passage channel 22 is isolated on a first and a second larger side by means of a first 25 A and a second 25B safety chamber, at the upper and lower part by means of respective upper 26A and lower

[0076] 26B safety compartments, thus being surrounded on four sides.

[0077] The first 25A and second 25B safety chambers and the upper 26A and lower 26B safety compartments are separated and do not communicate with each other, but are connected autonomously and independently only to the safety collector 27.

[0078] The remaining two sides face toward the inlet 23 and the outlet 24 for the coolant fluid, respectively, and therefore toward a wall of the containing body 11, and toward the safety collector 27, which acts as an intermediate safety compartment with respect to the conveying duct 29. According to some embodiments, the safety chambers 25 and / or compartments 26 can be empty, or contain a heat transfer medium inside them, such as water / glycol water or a phase change material (PCM).

[0079] According to some embodiments, the second air passage channels 21 , the safety chambers 25 and the coolant passage channels 22 are separated by means of respective substantially vertical walls 30.

[0080] In the event the pre-exchange and exchange units 14, 15 are aligned, some of the walls 30 in the heat exchange unit 15 can be substantially continuous with the walls 17 of the heat pre-exchange unit 14.

[0081] According to some embodiments, in correspondence with the junction zone between the pre-exchange 14 and exchange 15 units, dividing walls 31 are provided that close part of the first air passage channels 18 at the lower part, and delimit the safety chambers 25.

[0082] According to some embodiments, the dried air passage channels 19 are closed at the upper and lower part by respective horizontal walls 32, 33 (figs. 3, 6 and 7).

[0083] According to some embodiments, the coolant passage channels 22 are closed at the upper and lower part by respective horizontal walls 34, 35 (figs. 3, 6 and 8-8b) and by lateral walls 39 transverse to the vertical walls 30.

[0084] According to some embodiments, the safety chambers 26 are closed by means of respective walls on all sides by lateral 39 and horizontal 31, 40 walls, and only one aperture 36 is provided for communication with the safety collector 27 (figs. 5 and 7).

[0085] Preferably, the air passage channels 18, 19, 21 and the coolant passage channels 22 have a box-like parallelepiped shape, making them easier to manufacture using walls created with metal plates.

[0086] According to some embodiments, the first humid air passage channels 18 have a depth DI substantially the same as the depth D2 of the dried air passage channels 19 (fig. 8).

[0087] According to some embodiments, the second humid air passage channels 21 have a depth D3 substantially the same as the depth D4 of the coolant passage channels 22, and preferably equal to about half of the width of the air passage channels 18, 19.

[0088] The safety chambers 25 extend mainly on vertical planes, and in particular they can have a length in the vertical direction greater than the respective adjacent and bordering coolant passage channels 22, so as to guarantee the complete isolation of the latter on the directly facing sides.

[0089] The depth D5 of the safety chambers 25 can be substantially the same as the air passage channels 21 and coolant passage channels 22. The upper and lower safety compartments 26 extend in a substantially horizontal direction, transversally to the safety chambers 25, and connect to the safety collector 27.

[0090] According to some embodiments, the upper and lower safety compartments 26 are closed by means of respective walls on all sides by vertical 30 and horizontal 35, 40 lateral walls, and only one aperture 37, 38, respectively, is provided for communication with the safety collector 27 (figs. 6, 8a and 8b).

[0091] Figs. 4-7 schematically show, for successive sections taken along the lines from AA to DD shown in fig. 3, how the humid air passage channels 18, 21, the dried air passage channels 19 and the coolant passage channels 22 are disposed and interspersed, where the pre-exchange 14 and exchange 15 units are stacked vertically.

[0092] An equal or similar arrangement could also be created by providing the two units 14, 15 disposed side by side and connected with suitable ducts for the humid and dried air. Fig. 4 shows the heat exchanger 10 in which the exchange units 14, 15 are sectioned along the line A-A, allowing to see the humid air passage channels 18, 21 placed in continuity with each other.

[0093] As can be observed, the first humid air passage channel 18 has a greater depth than the second humid air passage channel 21, since the space adjacent thereto and separated by the wall 30 is occupied by a safety chamber 25. The air path Pl extends with continuity in a rectilinear direction between the inlet 12 and the conveying duct 29.

[0094] Fig. 5 shows the section BB in a more internal layer, beyond the wall 30 shown in fig. 4. In this case, the first humid air passage channel 18 is partly closed by the dividing wall 31, and a safety chamber 25 A is delimited below it, closed on all sides by respective walls and communicating with the safety collector 27 by means of the aperture 36. Fig. 6 shows the section CC in an even more internal layer, beyond the walls 17, 30 shown in fig. 5. In this section, a dry air passage channel 19 provided with the inlet 20 and outlet 13 for the dry air can be seen in the heat pre-exchange unit 14, and at the lower part a coolant passage channel 22 with the inlet 23 and outlet 24 apertures can be seen in the heat exchange unit 15. As can be observed, the upper safety compartment 26A develops between the respective walls 33, 34 that delimit the dried air passage channel 19 on one side and the coolant passage channel 22 on the other side, and it has an aperture 37 only on the side that faces the safety collector 27.

[0095] The lower safety compartment 26B develops between the respective walls 35, 40 that delimit the coolant passage channel 22 on one side and the conveying duct

[0096] 29 on the other side, and it has an aperture 38 only on the side that faces the safety collector 27.

[0097] Fig. 7 shows the section DD in an even more internal layer, beyond the walls 17, 30 in fig. 6. In this case, the dried air passage channel 19 is the same as in fig. 6, and a safety chamber 25B is delimited below it, which is also closed on all sides by respective walls and communicates with the safety collector 27 by means of the aperture 36.

[0098] It is clear that modifications and / or additions of parts may be made to the heat exchanger 10 as described heretofore, without thereby departing from the field and scope of the present invention, as defined by the claims.

[0099] It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art will be able to achieve other equivalent forms of a heat exchanger 10, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

[0100] In the following claims, the sole purpose of the references in brackets is to facilitate their reading and they must not be considered as restrictive factors with regard to the field of protection defined by the claims.

Claims

CLAIMS1. Heat exchanger (10) comprising a containing body (11) provided with an inlet and an outlet (12, 13) for the humid air and for the dried air, respectively, between which an air path (Pl) develops in which, in succession, there are disposed, vertically aligned on each other, a heat pre-exchange unit (14) of the air / air type in which the incoming humid air is able to exchange heat with the dried air and a heat exchange unit (15) of the air / coolant type in which the humid air is cooled by exchanging heat with a coolant in order to condense the water present therein and obtain dried air, wherein said heat pre-exchange unit (14) comprises first humid air passage channels (18) alternating with dried air passage channels (19), respectively separated by a plurality of walls ( 17), and said heat exchange unit (15) comprises second humid air passage channels (21) interspersed with coolant passage channels (22), wherein said humid air passage channels (18, 21) are vertically aligned and placed in continuity with each other, characterized in that said heat exchange unit (15) comprises respective safety chambers (25, 25 A, 25B) and safety compartments (26, 26A, 26B) disposed on each of the sides of each of said coolant passage channels (22) facing a respective humid and / or dried air passage channel (18, 19, 29).

2. Heat exchanger (10) as in claim 1, characterized in that it comprises a safety collector (27) connected to each of said safety chambers (25, 25A, 25B) and said safety compartments (26, 26A, 26B), and able to convey any coolant leaks outside said heat exchange unit (15).

3. Heat exchanger (10) as in claim 2, characterized in that said safety collector (27) is disposed in an intermediate position between said heat exchange unit (15) and a conveying duct (29) which connects an outlet end of said second humid air passage channels (21) to an inlet (20) for the dried air in said heat pre-exchange unit (14).

4. Heat exchanger (10) as in claim 2 or 3, characterized in that said safety collector (27) is disposed on a side of said heat exchange unit (15) that is opposite a side on which an inlet aperture (23) and an outlet aperture (24) for the coolant are disposed, which are connected to said coolant passage channels (22).

5. Heat exchanger (10) as in one or the other of claims from 2 to 4, characterized in that said safety chambers (25, 25A, 25B) and said safety compartments (26,26 A, 26B) are closed on all sides and comprise only one respective aperture (36, 37, 38) for communication with said safety collector (27).

6. Heat exchanger (10) as in one or the other of the previous claims, characterized in that each coolant passage channel (22) is isolated on a first and a second larger side by means of a first (25A) and a second (25B) safety chamber, at the upper and lower part by means of respective upper (26A) and lower (26B) safety compartments.

7. Heat exchanger (10) as in one or the other of the previous claims, characterized in that said safety chambers (24), said second humid air passage channels (21) and said coolant passage channels (22) are disposed parallel on respective vertical planes.

8. Heat exchanger (10) as in claim 7, characterized in that said safety chambers (25, 25A, 25B) extend for a length in a vertical direction greater than the respective adjacent and bordering coolant passage channels (22).

9. Heat exchanger (10) as in one or the other of the previous claims, characterized in that it comprises an upper safety compartment (26, 26A) and a lower safety compartment (26, 26B), which extend in a substantially horizontal direction, transversally to said safety chambers (26), and isolate said coolant passage channels (22) from said dried air passage channels (19) and from a dried air conveying duct (29), respectively.

10. Heat exchanger (10) as in any claim hereinbefore, characterized in that said safety chambers (25, 25 A, 25B) and / or said safety compartments (26, 26 A, 26B) contain inside them a heat transfer medium.

11. Heat exchanger (10) as in any claim hereinbefore, characterized in that said safety chambers (25, 25 A, 25B) and / or said safety compartments (26, 26A, 26B) contain inside them a phase-change material.

12. Heat exchanger ( 10) as in any claim hereinbefore, characterized in that said safety chambers (25, 25A, 25B) and / or said safety compartments (26, 26A, 26B) are independent of and separated from each other.

13. Heat exchanger (10) as in any claim hereinbefore, characterized in that in said heat pre-exchange unit (14) said first humid air passage channels (18) have substantially the same depth as said dried air passage channels (19), and in said heat exchange unit (15) said second humid air passage channels (21) havesubstantially the same depth as said coolant passage channels (22), and preferably equal to half of the width of said passage channels (18, 19) in said heat preexchange unit (14).

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