System for humidifying gas, in particular air

Abstract

The present invention relates to a system (1) for humidifying gas, in particular air, comprising: - a first branch (2) for transporting dry gas (200) to be humidified, having an inlet (3) and an outlet (4); - a second branch (5) for transporting humid gas (201), having an inlet (6) and an outlet (7); - a humidifier device (8), operatively connected to the first branch (2) and the second branch (5), configured to exchange water between dry gas (200) in the first branch (2) and humid gas (201) in the second branch (5) wherein the humidifier device (8) comprises a membrane humidifier; - at least one accumulator device (9) operatively connected to the humidifier device (8) along the first branch (2) and / or at least one accumulator device (9) operatively connected to the humidifier device (8) along the second branch (5), configured to draw and release water or water vapor from / into the dry gas (200) stream flowing through the first branch (2) or from / into the humid gas (201) stream flowing through the second branch (5), wherein the at least one accumulator device (9) comprises adsorbent material capable of adsorbing and desorbing water or water vapor from / into the dry air (200) stream flowing through the first branch (2) or from / into the humid air (201) stream flowing through the second branch (5).

Description

"System for humidifying gas, in particular air" DESCRIPTIONTECHNICAL FIELD

[0001] The present invention relates to a system for humidifying gas, by way of non-limiting example, the inlet air to a hydrogen fuel cell, i.e. , a device capable of converting hydrogen chemical energy into thermal and electrical energy.STATE OF THE ART

[0002] With reference to the application example of hydrogen fuel cells, Figure 1 depicts a system 101 comprising a polymer membrane type hydrogen fuel cell stack 102, which is continuously supplied with hydrogen H2 and oxygen O2 (present in air 200, taken, for example, from the environment). In each unit cell of stack 102, a hydrogen oxidation reaction takes place on an anode, producing hydrogen ions (H+) and electrons (e-), which are transmitted to a cathode, the former through a proton exchange membrane, the latter through external circuitry. At the cathode, a reaction occurs between the hydrogen ions and electrons transmitted from the anode and oxygen, resulting in the production of electricity and water (H2O).

[0003] It is known that the polymer membrane allows the transport of water between the two sides and that its ionic conductivity increases as its state of hydration increases, which in turn improves the performance of the fuel cell, as well as increasing the life or durability of its components. In particular, the degradation of the polymer membrane and catalytic layers is reduced with proper humidification of the same. For this purpose, it is considered that the air entering the stack 102 should meet specific relative humidity constraints, e.g., about 30% in low-power operation and about 15% in high-power operation.

[0004] In order to ensure such adequate levels of hydration, system 101 includes a humidifier 103 placed upstream of the hydrogen fuel cell stack 102, which is configured to humidify the air 200 entering it. Air 200 is compressed by a compressor 104 placed upstream of humidifier 103. The humidifier 103 also receives incoming exhaust gas stream 201 exiting the hydrogen fuel cell stack 102, loaded with water (H2O), in vapor phase or two-phase (vapor and liquid), produced by the electrochemical reaction, which is exploited for humidification of air 200. Connected to the hydrogen fuel cell stack 102, a device 105 can be provided for recirculation ofhydrogen H2.

[0005] Known humidifiers that are used in such systems are typically of the membrane type, in which thin polymer membranes with poor water adsorption capacity are provided. They are therefore capable of high performance in steady state, but not so much in transient regimes, resulting in uncontrolled changes in the relative humidity of the air entering the cathode of the hydrogen fuel cell stack 102. In addition, such humidifiers are particularly bulky due to their oversizing.SUMMARY OF THE INVENTION

[0006] It is therefore an object of the present invention to provide a system for humidifying gas, particularly air, such as to overcome at least in part the drawbacks mentioned with reference to the known art.

[0007] Specifically, one object of the present invention is to provide a system for humidifying gas, particularly air, that ensures adequate water exchange capacity under stationary conditions and effective water storage / release under dynamic operating conditions.

[0008] This and other objects are achieved by a system for humidifying gas according to claim 1 .

[0009] Dependent claims define possible advantageous embodiments of the invention.

[0010] The combined use of a humidifier device and an accumulator device achieves the above purposes while keeping the size and cost of the humidification system small.

[0011] With specific reference to the use of the humidification system according to the invention in combination with hydrogen fuel cells, the following advantages can be achieved:- decoupling between water storage and transport allows for smaller overall humidifier device size and membrane surface area than conventional humidifiers used in conjunction with polymer membrane hydrogen fuel cells, resulting in lower costs;- flooding of the porous components or dehydration of the polymeric material in the polymer membrane hydrogen fuel cell stack is avoided during transients, increasing its service life;- during dynamic operation of a polymer membrane hydrogen fuel cell system, it is possible to dampen extreme values of gas moisture at the cathode inlet, as well as extreme values of water content of the proton exchange polymer present in the membrane and in the catalytic layers;- thermal management of the fuel cell stack is optimized by cooling the inlet air to the stack during transient phases of load increase, when higher thermal power generation is present.

[0012] Hydrogen fuel cells combined with a gas humidification system according to the invention can find application in, for example, automotive, heavy transportation, marine transportation, aviation transportation, stationary applications, and portable devices.

[0013] It should be noted, however, that although this description refers to examples of application of the gas humidification system in combination with hydrogen fuel cells, the gas humidification system according to the invention may also find application in other areas, particularly in any area where controlled management, stationary or dynamic, of the relative humidity of the gas is required.

[0014] It should also be noted that, although this description refers to humidification and dehumidification of air, the system according to the invention can find equal application for humidification and dehumidification of any gas.BRIEF DESCRIPTION OF THE FIGURES

[0015] To better understand the invention and appreciate its advantages, some of its non-limiting exemplary embodiments will be described below, referring to the attached figures, in which:- Figure 1 is a schematic illustration of a hydrogen fuel cell system according to the prior art;- Figure 2 is a schematic illustration of a hydrogen fuel cell system combined with a gas humidification system according to a possible embodiment of the invention;- Figure 3 is a schematic illustration of a hydrogen fuel cell system combined with a gas humidification system according to another possible embodiment of the invention;- Figure 4 is a schematic illustration of a hydrogen fuel cell system combined with a gas humidification system according to another possible embodiment of theinvention;- Figures 5a-5c are schematic illustrations of a gas humidification system accumulator device according to alternative embodiments of the invention;- Figures 6-8 are schematic illustrations of the gas humidification system according to alternative embodiments of the invention;- Figure 9 is an exploded schematic illustration of a gas humidification system humidifier device according to a possible embodiment;- Figures 10a and 10b are diagrams showing possible trends of water content w in an adsorbent material over time t of a gas humidification system accumulator device according to the invention;- Figures 11 a and 11 b are diagrams illustrating the time t trends, respectively, of a possible load I of a hydrogen fuel cell stack, associated with a system according to the invention, and the corresponding time t trends of the relative humidity RH of the air leaving a humidifier device and an accumulator device of the system according to the invention.DETAILED DESCRIPTION OF THE INVENTION

[0016] With reference to the attached Figures 2-4, 6-8, a system for humidifying gas, specifically for humidifying air, is referred to as 1. The humidification system 1 comprises a first branch 2 for conveying dry air 200 to be humidified (which in the following may be referred to as "dry branch"), having an inlet 3 and an outlet 4, and a second branch 5 for conveying humid air 201 to be dehumidified (which in the following may be referred to as "humid branch"), having an inlet 6 and an outlet 7. Through inlet 3 of the first dry branch 2, air 200 to be humidified containing oxygen (O2) from the environment can be conveyed into system 1 , possibly compressed through a compressor 104, which may be included by or connected to system 1. Through inlet 6 of the second humid branch 5 humid air 201 to be dehumidified can be conveyed into system 1 , e.g., gases exiting from a hydrogen fuel cell stack 102 of the type described with reference to the known art (Figure 1 ), charged with water (H2O), in vapor-phase or two-phase (vapor and liquid), and therefore having a high absolute humidity, greater than that of air 200 entering the first branch 2. Thus, it should be noted that in the present description and in the attached claims, the expressions "dry air" 200 and "humid air" 201 are not to be interpreted strictly, but areto be conventionally understood to mean that the relative humidity of the humid air stream 201 , exiting, for example, the stack 102, is generally greater than the relative humidity of the dry air stream 200 taken from the environment.

[0017] System 1 comprises a humidifier device 8 operatively connected to the first dry branch 2 and the second humid branch 5. In particular, humidifier device 8 is configured to exchange moisture between dry air 200 in the first dry branch 2 and humid air 201 in the second humid branch 5. The direction of the moisture exchange is a function of the partial vapor pressures and temperatures of the flows of dry air in the first dry branch 2 and humid air in the second humid branch 5. The humidifier device 8 includes a humidifier of the membrane type, such as planar or tubular, or even with a different geometry. For example, a humidifier of the type described with reference to humidifier 103 in system 101 shown in Figure 1 can be used. Further details on possible alternative embodiments of humidifier device 8 will be provided later.

[0018] The air humidification system 1 further comprises at least one accumulator device 9 operatively connected to the humidifier device 8 along the first dry branch 2 or along the second humid branch 5, or at least one accumulator device 9 in each of the dry branch 2 and the humid branch 5.

[0019] The accumulator device 9 is configured to withdraw and release liquid water or water vapor from / into the air stream flowing through it, specifically the dry air stream 200 flowing through the first dry branch 2 or the humid air stream 201 flowing through the second humid branch 5, depending on the branch to which the accumulator device 9 is operationally connected. The withdrawal or release of liquid water or water vapor from / into the air stream is a function of the latter's relative humidity and temperature. More specifically, the accumulator device 9 is configured to adsorb and desorb water from / into the air stream flowing through it. Such adsorption and desorption are made possible by suitable adsorbent materials provided in the accumulator device 9, such as, but not limited to, zeolites, silica gels, aluminas, SAPO-34, MOFs (metal organic frameworks), polymers, salts, in the form of packed grains, monolithic structures, or corrugated sheets. The adsorbent material can be arranged in the form of a replaceable cartridge arranged within a housing, such as of plastic material. According to one embodiment, the accumulator device 9comprises one or more modules operatively arranged in series or in parallel, comprising the adsorbent material.

[0020] With reference to Figures 10a and 10b, therein are diagrams showing possible trends in the water content w of the adsorbent material of the accumulator device 9 over time t, starting from an equilibrium condition between the adsorbent material and the air flowing into the accumulator device 9.

[0021] In the case where (Figure 10a) at time t1 the air entering the accumulator device 9 has a higher relative humidity than the situation at time to, the adsorbent material tends to adsorb water from the air until an equilibrium condition is reestablished.

[0022] In the case where (Figure 10b) at time t2 the air entering the accumulator device 9 has lower relative humidity than the situation at time to, the adsorbent material tends to desorb water vapor to the air until an equilibrium condition is reestablished.

[0023] In both example cases illustrated with reference to Figures 10a and 10b, the adsorbent material of accumulator device 9 exchanges vapor with air, stabilizing its relative humidity. This allows the relative humidity of the air leaving the accumulator device 9 to be maintained within a desired operating range. In addition, the temperature of the adsorbent material and air increase in the adsorption phase and decrease in the desorption phase.

[0024] The humidifier device 8 and the accumulator device 9 can be connected with each other according to different modes.

[0025] According to the embodiments shown in Figures 2-4, the humidifier device 8 and the accumulator device(s) 9 are distinct and separate from each other.

[0026] In accordance with the embodiment shown in Figure 2, the accumulator device 9 is operatively arranged downstream of the humidifier device 8 along the first dry branch 2. It should be noted that in this description and the attached claims, the terms "upstream" and "downstream" refer to the direction of air flow, as also indicated by the arrows in the Figures. Specifically, the humidifier device 8 comprises an inlet 10 and an outlet 11 along the first dry branch 2 and an inlet 12 and an outlet 13 in the second humid branch 5. In the first dry branch 2, humidifier device 8 receives at inlet 10 dry air 200 from, for example, the environment. Inlet 10 may coincide with inlet 3of the whole system 1 , or, alternatively, additional elements, such as compressor 104, may be provided between inlets 3 and 10. In the second humid branch 5, the humidifier device 8 receives, at inlet 12, humid air 201 from, for example, the hydrogen fuel cell stack 102, which then flows out of outlet 13, which may coincide with outlet 7 of system 1 , or, alternatively, additional elements (not shown) may be provided between the two outlets 13 and 7.

[0027] Dry air 200 exiting humidifier device 8 from outlet 11 enters an inlet 14 of accumulator device 9, from which it exits at an outlet 15. The latter may coincide with outlet 4 of system 1 or, alternatively, additional elements (not shown) may be provided between outlet 15 and outlet 4. Humidified air exiting accumulator device 9, containing oxygen O2, may, for example, enter hydrogen fuel cell stack 102 at its inlet 106. Similarly to what is described with reference to Figure 1 , the hydrogen fuel cell stack 102 further comprises an inlet 107 for hydrogen H2 and an outlet 108 for air 201 , i.e. , specifically, water-laden (H2O) exhaust gases charged, in vapor phase or two- phase, connected to the inlet 6 of the second humid branch 5 of the system 1 , through which the water-laden exhaust gases reach the humidifier device 8, into which they enter through inlet 12. The air 201 exiting the device accumulator 8 via outlet 13 can then be exhausted from system 1 via outlet 7. The hydrogen fuel cell stack 102 may further comprises a device 105 for recirculating excess hydrogen H2, exiting the stack via an outlet 109 and recirculated back to the inlet 107.

[0028] System 1 in the embodiment shown in Figure 2 is particularly suitable for dynamic (i.e., non-stationary) use in combination with the hydrogen fuel cell stack 102, e.g., in transients in automotive, heavy transport, marine transport, and aviation transport. In fact, the dry air 200 compressed downstream from the compressor 104 is humidified in the humidifier device 8, which recovers some of the water contained in the exhaust from the cathode stream 201 leaving the stack 102 via the outlet 108. Exiting humidifier device 8, dry air 200 then enters accumulator device 9 where, depending on the moisture level of the adsorbent material, it receives or gives up water. The two cases are illustrated with reference to Figures 11 a and 11 b, which show the time t trend, respectively, of a possible load I of stack 102, expressed, for example, as current density in A / cm2(Figure 11 a), and the corresponding time t trend of the relative humidity RH of dry air 200 at outlet 11 of humidifier device 8 (dashedline in Figure 11 b) and at outlet 15 of accumulator device 9 (solid lines in Figure 11 b, for two different adsorbent material loads, e.g., 1 kg and 3 kg). Figure 11 b also highlights the desired relative humidity limit of 30 percent at the inlet in stack 102, as discussed above.

[0029] In the first case, which occurs, for example, in the transition from a low-load to a high-load condition of stack 102 (zone 301 of Figures 11 a and 11 b), humidifier device 8 alone causes a lowering of the relative humidity of the air entering stack 102. The storage device 9 maintains a higher humidification of air 200 by partly desorbing the water contained in the adsorbent material.

[0030] In the second case, which occurs, for example, in the transition from a high- load to a low-load condition of stack 102 (zone 302 of Figures 11 a and 11 b), the flow rate to be humidified decreases and the relative air humidity guaranteed by humidifier device 8 alone increases. Some of the water is then adsorbed by the adsorbent material of the accumulator device 9, allowing a more uniform relative air humidity 200 to be maintained.

[0031] It should be noted that the desorption / adsorption process is associated with a decrease / increase in the local temperature of the adsorbent material in the accumulator device 8, respectively, resulting in a consequent cooling / heating of the air 200. The desorption phases in accumulator device 9 are associated with the phases in which more power is required from stack 102, which in turn causes the stack 102 to produce more heat. As indicated earlier, the desorption phase results in cooling of the adsorbent material, thus of the circulating air. This promotes the removal of thermal energy from the same, decreasing, for example, the thermal load on the cooling system of the stack 102.

[0032] In accordance with the embodiment shown in Figure 3, the accumulator device 9 is operationally arranged upstream of the humidifier device 8 along the second humid branch 5. For example, the accumulator device 9 can receive via inlet 14 exhausted air 201 rich in H2O, in vapor phase or two-phase, particularly gases exiting from the outlet 108 of the hydrogen fuel cell stack. Air 201 exiting the accumulator device 9 through outlet 15 reaches along the second humid branch 5 the humidifier device 8, into which it enters through inlet 12. Generally, the air 201 exiting the cathode of the hydrogen fuel cell stack 102 has a very high relativehumidity or is in a two-phase condition. Therefore, the adsorbent material of the accumulator device 9 generally has a high water load. This configuration of system 1 is particularly advantageous, for example, in the transition from a high-load condition - with high water production - to a low-load condition of stack 102. In the latter condition, the relative humidity of the airflow leaving the 108 outlet of the 102 stack will be lower. Then the air, in passing through the accumulator device 9, will become humidified, and subsequently, as it enters the humidifier device 8 along the second humid branch 5, it will withdraw vapor to the air 200 passing through the humidifier device 8 along the first dry branch 2.

[0033] In accordance with the embodiment illustrated in Figure 4, a first 9' accumulator device is operatively arranged downstream of humidifier device 8 along the first dry branch 2, and a second 9” accumulator device is operatively arranged upstream of humidifier device 8 along the second humid branch 5. This configuration is a combination of the embodiments shown in Figures 2 and 3 and combines their advantages, in the different transients, highlighted above.

[0034] According to further possible variants, the accumulator device 9 comprises one or more of the additional devices listed below for its active control, as depicted in Figures 5a-5c.

[0035] In accordance with an embodiment (Figure 5a), the accumulator device 9 comprises a by-pass branch 16 between inlet 14 and outlet 15, comprising a controllable valve 17. The presence of the by-pass branch 16, which can be opened and closed, possibly with intermediate degrees of opening, by means of valve 17, makes it possible to prevent the accumulator device 9 from overcharging or overdischarging, i.e. , its water content rising or falling beyond a predefined threshold.

[0036] In accordance with an embodiment (Figure 5b), the accumulator device 9 comprises an auxiliary inlet 18 for controlled feed of water (H2O) in the liquid phase or additional vapor, e.g., taken from devices producing excess water, to which system 1 can be connected, which can be adsorbed by the adsorbent material. Feeding can be done, for example, by a pump (not shown in the Figures), or by gravity, or by pressure differences.

[0037] In accordance with an embodiment (Figure 5c), the accumulator device 9 comprises a device 19 for temperature control (i.e., a device for controlled heatingand / or cooling) of the adsorbent material. The presence of the temperature control device 19 facilitates the process of water desorption by the adsorbent material, a process that is endothermic, or the adsorption process, which is exothermic. Preferably, the temperature control device 19 is controlled in such a way as to keep the temperature of the adsorbent material substantially constant. For example, the temperature control device 19 may be of the electrical type (e.g., it may be of the electric resistance type, or Peltier cell type), or fluid thermovector type, or it may include an evaporator / condenser of a refrigeration machine.

[0038] According to alternative embodiments, illustrated in Figures 6-8, the accumulator device(s) 9 is / are integrated into the humidifier device 8, forming a single integrated device with it.

[0039] According to these embodiments, the integrated device comprises a common housing 20 containing both the humidifier device 8 and the storage device(s) 9 inside it.

[0040] In particular, according to the embodiment in Figure 6, the storage device 9 is arranged downstream of the humidifier device 8 along the first dry branch 2. From a functional point of view, this embodiment coincides with that shown in Figure 2, where, however, the accumulation device 9 and the humidifier device 8 are distinct and separate.

[0041] According to the form of realization in Figure 7, the accumulation device 9 is arranged upstream of the humidifier device 8 along the second humid branch 5. From a functional point of view, this form of realization coincides with that shown in Figure 3, where, however, the accumulation device 9 and the humidifier device 8 are distinct and separate.

[0042] According to the embodiment in Figure 8, a first storage device 9' is arranged downstream of humidifier device 8 along the first dry branch 2 and a second storage device 9" is arranged upstream of humidifier device 8 along the second humid branch 5. From a functional point of view, this embodiment coincides with that shown in Figure 4, where, however, accumulation devices 9' and 9" and humidifier device 8 are distinct and separate.

[0043] Figures 6-8 also show the inputs / outputs 3, 4, 6, 7, 10, 11 , 12, 13, 14, 15, functionally corresponding to those described with reference to the embodimentsshown in Figures 2-4.

[0044] With reference to Figure 9, a possible humidifier device 8 of system 1 according to an embodiment of the invention is illustrated schematically therein. Specifically, according to the illustrated embodiment, the humidifier device 8 is of the planar membrane type. It comprises at least one planar membrane 21 , which separates the air flow in the first dry branch 2 and the air flow in the second humid branch 5, interposed between two separators 22, e.g., made of plastic material. Advantageously, the separators 22 comprise channels 23 delimited, for example, by ribs 24, within which air can flow on either side of and in contact with the membrane 21 , allowing moisture exchange between the first dry branch 2 and the second humid branch 5. According to a possible variant, the humidifier device 8 comprises layers of macroporous material 25 placed on two opposite sides of the planar membrane 21 , interposed between the latter and the separators 22. The layers of macroporous material 25, made, for example, of plastic material, allow for a high homogeneity of dry and humid air flows in contact with the membrane 21 , improving the vapor diffusion process.

[0045] According to a further variant, the humidifier device 8 also comprises adsorbent material. For example, separators 22 can be made of composite materials, such as resins or plastics, mixed with adsorbent material powders. The distribution of the adsorbent material along the separators 22 can be variable and / or localized. In particular, adsorbent material can be provided along the channels 23, possibly in variable quantities.

[0046] Alternatively or additionally, the layers of macroporous material 25 may themselves be made of, or comprise, adsorbent material, for example as a surface coating. Again, the distribution of the adsorbent material in the layers of macroporous material 25 can be variable and / or localized.

[0047] Alternatively or additionally, planar membrane 21 can comprise adsorbent material, for example, as a surface coating. Again, the distribution of adsorbent material in membrane 21 can be variable and / or localized.

[0048] It should be noted that the provision of adsorbent material in humidifier device 8 is an alternative way to at least partially integrate accumulator device 9 inside it. According to these configurations, an additional accumulator device 9external to humidifier device 8 may not be necessary. However, one or more accumulator devices 9 can be provided, as described above, even if the device humidifier 8 includes adsorbent material.

[0049] The distribution of the adsorbent material in the humidifier device 8, according to one or more of the modes said above, can be chosen in such a way as to replicate, from a functional point of view, the positioning of the accumulator devices 9 described with reference to the embodiments in Figures 2-4. Specifically, the adsorbent material may be positioned, or be present in larger quantities, near the air outlet 200 along the first dry branch 2 (corresponding to outlet 11 , analogous to the embodiment in Figure 2), or near the air inlet 201 along the second humid branch 5 (corresponding to inlet 12, analogous to the embodiment in Figure 3), or in both positions (analogous to the embodiment in Figure 4).

[0050] To the described embodiments of the gas humidification system, particularly air humidification system, the skilled person, in order to meet specific contingent needs, may make numerous additions, modifications, or substitutions of elements with functionally equivalent ones, without, however, departing from the scope of the attached claims.

Claims

CLAIMS1. System (1 ) for humidifying gas, in particular air, comprising:- a first branch (2) for transporting dry gas (200) to be humidified, having an inlet (3) and an outlet (4);- a second branch (5) for transporting humid gas (201 ), having an inlet (6) and an outlet (7);- a humidifier device (8), operatively connected to the first branch (2) and the second branch (5), configured to exchange water between dry gas (200) in the first branch (2) and humid gas (201 ) in the second branch (5) wherein the humidifier device (8) comprises a membrane humidifier;- at least one accumulator device (9) operatively connected to the humidifier device (8) along the first branch (2) and / or at least one accumulator device (9) operatively connected to the humidifier device (8) along the second branch (5), configured to draw and release water or water vapor from / into the dry gas (200) stream flowing through the first branch (2) or from / into the humid gas (201 ) stream flowing through the second branch (5), wherein the at least one accumulator device (9) comprises adsorbent material capable of adsorbing and desorbing water or water vapor from / into the dry air (200) stream flowing through the first branch (2) or from / into the humid air (201 ) stream flowing through the second branch (5).

2. System (1 ) according to claim 1 , wherein the at least one accumulator device (9) is operatively arranged downstream of the humidifier device (8) along the first branch (2).

3. System (1 ) according to claim 1 , wherein the at least one accumulator device (9) is operatively arranged upstream of the humidifier device (8) along the second branch (5).

4. System (1 ) according to claim 1 , comprising a first accumulator device (9') operatively arranged downstream of the humidifier device (8) along the first branch (2), and a second accumulator device (9") operatively arranged upstream of the humidifier device (8) along the second branch (5).

5. System (1 ) according to any one of claims 1 to 4, wherein the humidifier device (8) and the at least one accumulator device (9) are separate and distinct from each other.

6. System (1 ) according to any one of claims 1 to 4, wherein the at least one accumulator device (9) is integrated into the humidifier device (8).

7. System (1 ) according to any of the preceding claims, wherein the humidifier device (8) comprises at least one planar membrane (21 ) and at least two separators (22) between which the at least one planar membrane (21 ) is interposed, said separators comprising channels (23) for the dry gas (200) flow of the first branch (2) and / or for the humid gas (201 ) flow of the second branch (5), respectively.

8. System (1 ) according to claim 7, wherein the humidifier device (8) further comprises layers of macroporous material (25) placed on two opposite sides of the at least one planar membrane (21 ), interposed between the latter and the at least two separators (22).

9. System (1 ) according to claim 7 or 8, wherein the humidifier device (8) comprises adsorbent material in the at least two separators (22) and / or in the layers of macroporous material (25) and / or in the at least one planar membrane (21 ), uniformly and / or variably distributed, and / or localized.

10. System (1 ) according to any of the preceding claims, wherein the at least one accumulator device (9) comprises a device (19) for controlling temperature of the adsorbent material of the accumulator device (9).

11. System (1 ) according to any one of the preceding claims, wherein the at least one accumulator device (9) comprises a by-pass branch (16) comprising a controllable valve (17).

12. System (1 ) according to any one of the preceding claims, wherein the at least one accumulator device (9) comprises an auxiliary inlet (18) for additional and controlled input of water (H2O) in vapor and / or liquid phase.

13. Hydrogen fuel cell system, comprising:- a hydrogen fuel cell stack (102);- a system (1 ) for humidifying gas according to any of the preceding claims, connected to the hydrogen fuel cell stack (102) so to supply it with humidified dry gas (200) exiting the first branch (2) and to receive in the second branch (5) humid gas (201 ) exiting the hydrogen fuel cell stack (102).

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