WO2009095201A1

WO2009095201A1 - Humidifier

Info

Publication number: WO2009095201A1
Application number: PCT/EP2009/000510
Authority: WO
Inventors: Klaus Leister; Harald Ehrentraut
Original assignee: Carl Freudenberg Kg
Priority date: 2008-01-30
Filing date: 2009-01-27
Publication date: 2009-08-06
Also published as: DE102008006793A1

Abstract

The invention relates to a humidifier (1), comprising a housing (2) having inflow openings (3) for supply air flows and outflow openings (4) for discharge air flows, and at least one humidifier module (5), which is disposed in the housing (2), wherein the humidifier module (5) is configured such that at least two flow surfaces (6, 7) are formed for a supply air flow, wherein the flow surfaces (6, 7) are inclined toward each other.

Description

humidifier

Description Technical area

The invention relates to a humidifier, comprising a housing with inflow openings for supply air flows and outflow openings for exhaust air streams and at least one humidifier module, which is arranged in the housing, wherein the humidifier module is formed so that at least two inflow surfaces result for a supply air.

State of the art

Such a humidifier is known from DE 102 44 707 A1. The humidifier described there is mainly used in fuel cells. A humidified supply air is required in particular in polymer electrolyte membrane (PEM) fuel cells, since the power generation efficiency in the electrolyte membrane decreases when the electrolyte membrane dries out. In the humidifier, the water required for humidifying the supply air is taken from the exhaust air of the fuel cell in the humidifier modules. This results in a cycle of water, so that the refilling of water can be omitted, which is particularly advantageous for mobile applications. In the prior art humidifier several humidifier modules are spaced from each other, so that between these humidifier modules free space results. In this free space, which is delimited by inflow surfaces of the adjacent humidifier modules, an air flow is distributed and flows through the inflow surfaces into the humidifier modules. The structure is similar to that of a plate heat exchanger.

Presentation of the invention

The invention has for its object to develop the prior art humidifier so that evened the pressure loss of the penetrating into the room air flow.

This object is achieved with the features of claim 1. In advantageous embodiments, the dependent claims relate.

To solve the problem, the inflow surfaces are inclined to each other. As a result, the cross-sectional area is flowed through by the air flow. The inclination of the inflow surfaces is set according to the invention such that the largest cross-sectional area results at the inflow opening and the cross-sectional area then decreases steadily. This results in a particularly favorable course of the pressure loss, since in the region with the largest volume flow, namely at the inflow opening results in the largest flow-through cross-sectional area. After entering the supply air, the volume flow of the supply air is divided, with part of the volume flow penetrates into the humidifier via the two inflow surfaces. This reduces the remaining in the space defined by the inflow space remaining

Volume flow. However, since the cross-sectional area decreases at the same time, the pressure loss remains substantially constant. The result is that the volume flow over the entire inflow surface uniformly penetrates into the at least one humidifier module and so that the humidifier module is flowed through uniformly and the available exchange surface is fully used. In a humidifier two supply air streams are introduced. A first supply air flow is a moist supply air flow and another supply air flow is the supply air flow to be humidified. In the humidifier according to the invention, the exchange of moisture via a membrane, which is arranged in the humidifier module. For this purpose, the humidifier module may comprise a multiplicity of hollow fibers. For mass transfer then a supply air flow outside the hollow fibers is guided and flows around them and the other supply air flow is passed through the hollow fibers. In most cases, the moist supply air flows around the hollow fibers and the supply air to be humidified flows through the hollow fibers. It follows that the moist supply air over the

Anströmflächen the humidifier module is supplied, penetrates into the humidifier and here flows around the hollow fibers. Due to the decreasing cross section, a comparable volume flow penetrates into the humidifier module in each surface section of the inflow surfaces. In other embodiments, the supply air to be humidified can also be supplied to the humidifier module via the inflow surfaces.

The humidifier module may be V-shaped. In this embodiment, only a single humidifier module is provided in the housing, which is configured so that two within the humidifier

Give flow surfaces. The top and bottom of the humidifier module are then corresponding to the Ausströmflächen. Advantageously, the humidifier module is divided in the middle, resulting in two humidifier module parts with substantially the same thickness. These are then flowed through evenly by the supply air. The cross-section of the space formed between the humidifier module parts decreases from a maximum value in the region of the inflow opening and can be reduced to zero when the humidifier module parts meet at one end face. Preferably, the humidifier module is rectangular. In the embodiment according to the invention, the inflow area increases considerably. With the Increased inflow area is also accompanied by an enlarged exchange surface, which in turn leads to an increased exchange gradient. This means that the humidifier module has a greater humidifier performance for the same thickness.

There may be provided two humidifier modules which are arranged in a V-shape relative to each other. These are designed and arranged analogously to the single humidifier module described above. It is also conceivable zigzag to arrange several humidifier modules in the manner of a pleated filter.

The humidifier module may comprise hollow fibers. Hollow fibers are water-vapor-permeable fibers in which mass transfer takes place between the volume flow passing through the fibers and the volume flow flowing around the fibers. In a humidifier module a plurality of hollow fibers are arranged and usually connected to each other at the end faces by a potting compound, which simultaneously prevents the two volume flows meet directly.

The hollow fibers may be arranged in the direction of the inclination or transverse to the inclination of the inflow surfaces of the humidifier module. In the first solution results in a mass transfer in cocurrent or countercurrent depending on the flow direction. In the second solution results in a mass transfer in the cross flow. In the second solution, therefore, the moist supply air flow and the supply air flow to be humidified are cross-flowed. In this embodiment, it is advantageous that the inflow openings of the two

Supply air flows are arranged orthogonal to each other and therefore the connections are particularly easy to produce and also the air duct is advantageous, since the air streams do not meet or penetrate before the humidifier. In the housing ribs may be arranged. In particular, flat and rectangular humidifier modules results in a likewise flat trained housing. Ridges disposed in the housing stabilize the housing and may at the same time be configured to act as a flow guide.

The at least one humidifier module can be supported on the ribs. The humidifier module is supported by its outer surfaces on the ribs. Analogous to the decreasing cross-section of the space formed by the inflow surfaces results on the outflow side, ie the outer surfaces of the humidifier a magnifying cross-section of the space formed by the outer surfaces and the housing. This again improves the flow conditions, since only a small volume flow passes through the humidifier module at the outlet corresponding to the inlet of the supply air and at the other end the entire

Volumetric flow was passed through the humidifier module. At this point, the cross section on the outflow side is the largest. The flow conditions are best for a housing with a rectangular cross section. Viewed in cross-section, while the humidifier modules or parts are arranged centrally on a narrow side and arranged on the opposite narrow side outside, so that there is a V-shaped cross-section of the humidifier.

The inlet openings and the outflow openings can be assigned to collectors. The collectors at the inlet openings lead to a homogenization of the flow, so that over the entire cross section, a comparable volume flow occurs. The collectors at the outflow openings lead to a homogenization of the exiting flow, so that the exhaust air can escape over the entire cross section. Such a humidifier is particularly suitable for humidifying the Brennstoffzellenzuluft a PEM fuel cell, which is particularly used in the automotive sector.

The large cross section in the region of the inflow opening is particularly suitable for the integration of a filter, for example a particle filter or a chemical filter or a combination of both. The large cross-section allows the use of a large-area filter, which has a low pressure loss and a high filter performance. This filter can be arranged between the collector and inlet opening or arranged in front of the collector. It is also conceivable to arrange the filter on the inflow surface of the at least one humidifier module. The filter can be designed as a filter mat or as a pleated filter and comprise a chemical and physical filter section. Such a filter comprises, for example, an electret filter material and a filter layer with activated carbon. During operation, a fuel cell can emit substances that can reach the humidifier via the moist supply air. These substances can affect the life of the humidifier, in particular the membrane. It is thus particularly advantageous if the moist supply air supplied to the humidifier from the fuel cell is passed through a filter in order to retain the harmful substances. The integration of the filter in the humidifier results in a particularly space-saving design. Furthermore, due to the arrangement directly adjacent to the humidifier module, the filter acts as a diffuser and thus causes a homogenization of the supply air and a uniform flow through the humidifier module. This is particularly advantageous in humidifiers, which have a low pressure loss due to their design, which may result in partial load operation to a non-uniform flow through the humidifier. This non-uniform flow reduces the humidifier performance of the humidifier module. The upstream filter causes an increased especially in partial load operation Pressure loss, which leads to an improved flow of the inflow surfaces of the humidifier module. The arrangement of the filter is not limited only to the arrangement of the moistening module with inclined inflow surfaces. It is also conceivable to connect such a filter to any desired humidifier module. This can be designed, for example, as a rectangular or even round humidifier module and comprise only one or more inflow surfaces. It is essential that the filter is associated with an inflow surface and is arranged directly adjacent to this. Thus, the advantageous effect of the filter described above also occurs in these humidifier modules.

For better utilization of the exchanger surface, it is advantageous if, in particular at partial load, the back pressure increases in front of the inflow surface, thereby resulting in a better distribution of the supply air over the inflow surface. It is also conceivable that the humidifier module is preceded by a device which causes a dynamic adjustment of the dynamic pressure. Such a device may comprise an actuator which adjusts the back pressure of the device in dependence on the load behavior of the humidifier. For this purpose, the actuator is connected to at least one sensor. Advantageously, the adjustment of the back pressure by a self-regulating system. For this purpose, the device may for example comprise a memory in the form of a spring. The spring causes an adjustment of the device in the unloaded state. Depending on the pending on the device dynamic pressure is then an adjustment of the device, so that in each load case optimum flow of the humidifier is guaranteed. The control of the dynamic pressure can be done by a variety of spring-loaded flaps. These can be arranged on a carrier and be connected by film hinges with this, wherein the film hinges can simultaneously take over the spring function. In other embodiments, the device may comprise an adjustable perforated plate, wherein the regulation of the dynamic pressure by Change of the perforated plate geometry takes place. The device may be part of the filter, for example, the device may be part of the support that positions the filter in the humidifier. In this embodiment, the device is arranged on the supply side of the humidifier module. But it is also conceivable to arrange the device on the exhaust side.

Brief description of the drawing

Some embodiments of the humidifier according to the invention are explained below with reference to the figures. These show, in each case schematically:

1 shows a humidifier in cross section;

FIG. 2 shows the humidifier according to FIG. 1 in plan view; FIG. 3 shows a humidifier with several humidifier modules;

FIG. 4 shows a humidifier according to FIG. 1 with integrated filter; FIG.

5 shows a humidifier with integrated filter;

FIG. 6 shows the humidifier according to FIG. 1 in a spatial representation; FIG.

7 shows a humidifier with integrated filter; 8 shows a device for flow regulation;

9 shows another device for flow regulation.

Embodiment of the invention

FIG. 1 shows a humidifier 1 with a housing 2 which is flat and rectangular in cross-section. The housing 2 has two inlet openings 3 for supply air streams and two outlet openings 4 for exhaust air streams and at least two humidifier modules 5 which are arranged in the housing 2. One supply air flow is a moist supply air flow and another supply air flow is a supply air flow to be humidified. When used as a humidifier 1 for a Fuel cell is the moist supply air the fuel cell exhaust air and the supply air to be humidified is the Brennstoffzellenzuluft. The humidifier 5 are arranged in the housing 2, that there are two inflow surfaces 6, 7 for a supply air. The humidifier 5 are V-shaped to each other, whereby the inflow surfaces 6, 7 are inclined to each other. Hollow fibers 8 are arranged in the humidifier module 5, one air stream flowing through the hollow fibers 8 and the other air flow flowing around the hollow fibers 8. The hollow fibers 8 are oriented orthogonally to the flow direction of the air stream flowing around, so that a cross-flow mass transfer results via the hollow fibers 8. At the inlet openings 3 and the outflow openings 4 collector 10 are assigned.

FIG. 2 shows a humidifier 1 according to FIG. 1 in plan view. In this view, the other inflow opening 3 and the other outflow opening 4 can be seen. Both openings 3, 4 is also a collector 10 upstream. In this figure, in particular, the flow guidance in the cross flow can be seen.

FIG. 3 shows a humidifier 1 according to FIG. 1, wherein in this embodiment a plurality of humidifier modules 5 are arranged in a zigzag shape, so that a plurality of inflow surfaces 6, 7 results, which are inclined relative to one another.

FIG. 4 shows a humidifier according to FIG. 1, in which embodiment a filter 11 is integrated between inflow opening 3 and collector 10. This filter 11 is a combined filter and includes a particulate filter based on a non-woven fabric electret filter material and a chemical filter comprising activated carbon. The filter is used to filter the fuel cell exhaust air, which forms the moist supply air flow in this embodiment. Through the filter 11 impurities from the fuel cell are retained. Furthermore, through the filter 11 a Homogenization of the supply air and thus an improved distribution of the supply air over the inflow surface 6, 7 of the humidifier 5.

Figure 5 shows a humidifier according to Figure 4, wherein the filter 11 is arranged in this embodiment on the inflow surfaces 6, 7 of the humidifier 5. This embodiment leads to an improved distribution of the supply air over the inflow surfaces 6, 7.

FIG. 6 shows the humidifier 1 according to FIG. 1. In this illustration, the ribs 9 can be seen, which on the one hand stiffen the housing 2 and on which the humidifier modules 5 are supported and at the same time act as a flow guide.

FIG. 7 shows two exemplary embodiments of a humidifier 1 in which the housings are flat and rectangular in cross-section. Both housings 2 have two inflow openings 3 for supply air flows and two outflow openings 4 for exhaust air flows. One embodiment comprises a humidifier module 5 and the other embodiment comprises two humidifier modules 5 which are arranged parallel to one another in the housing 2. One supply air flow is a moist supply air flow and another supply air flow is a supply air flow to be humidified. When used as a humidifier 1 for a fuel cell, the moist supply air flow is the fuel cell exhaust air and the supply air flow to be humidified is the Brennstoffzellenzuluft. In the humidifier module 5 hollow fibers 8 are arranged, wherein an air flow flows through the hollow fibers 8 and the other air flow flows around the hollow fibers 8. The hollow fibers 8 are oriented orthogonally to the flow direction of the air stream flowing around, so that a mass transfer occurs in cross flow via the hollow fibers 8. At the inlet openings 3 and the outflow openings 4 collector 10 are assigned. The inflow surfaces 6, 7 is associated with a filter 11. This filter 11 is multi-layered and has a chemical filter layer with activated carbon and a physical filter layer with electret filter material.

FIG. 8 shows a device 12 for flow regulation of the supply air. Such a device 12 is used adjacent to a humidifier module 5 in accordance with one of the previous examples or a humidifier known from the prior art in order to bring about a homogenization of the supply air, so that the humidifier module 5 is uniformly flowed over the entire inflow surface 6. In the embodiment shown in Figure 8 above, the device 12 consists of a

Base body 13 in which a plurality of openings 15 are introduced, which are each closed by a flap 14. The flap 14 is resiliently arranged on the base body 13, that the flap 14, the aperture 15 at a low dynamic pressure and thus at a low flow rate of supply air almost closes. As a result, the supply air over the entire surface of the device 12 and thus spread over the entire surface of the humidifier 5. If the volume flow of supply air increases, and the dynamic pressure increases and the flaps 14 open, whereby the air flow rate increases in each opening 15 , As a result, an increase in the back pressure is avoided, with a uniform flow of humidifier 5 is ensured. The device thus leads to a uniform flow of the humidifier is guaranteed especially in partial load operation.

A similar device 12 is shown in Figure 8 below. In this

Embodiment, the base body 13 is formed as a perforated plate, wherein the openings 15, which are located in the base plate 12, are variable by a displaceable second formed as a perforated plate base 13 in their cross-sections. FIG. 9 shows a device 12 in which two flat elements 16 are hinged together at one edge. By a spring means 17, the two flat elements 16 are folded apart at a low dynamic pressure. At the one edge opposite the other edge strips 18 are arranged. As the dynamic pressure increases, the strips 18 bend and the two flat elements 16 move toward one another and release an enlarged cross-section.

Claims

claims

1. humidifier (1), comprising a housing (2) with inflow openings (3) for supply air and outflow openings (4) for exhaust air streams and at least one humidifier module (5) which is arranged in the housing (2), wherein the humidifier module (5 ) is formed so that at least two inflow surfaces (6, 7) for a supply air flow, characterized in that the inflow surfaces (6, 7) are inclined to each other.

2. Humidifier according to claim 1, characterized in that a supply air flow is a moist supply air flow and another supply air flow to be humidified supply air flow.

3. Humidifier according to claim 1 or 2, characterized in that the humidifier module (5) is V-shaped.

4. humidifier according to claim 1 or 2, characterized in that two humidifier modules (5) are provided, which are arranged in a V-shape to each other.

5. Humidifier according to one of claims 1 to 4, characterized in that the humidifier module (5) comprises hollow fibers (8).

6. A humidifier according to claim 5, characterized in that the moist supply air flows around the hollow fibers (8) and flows to be humidified supply air through the hollow fibers (8).

7. Humidifier according to one of claims 1 to 6, characterized in that the moist supply air flow and to be humidified supply air flow are performed in cross flow.

8. humidifier according to one of claims 1 to 7, characterized in that in the housing (2) ribs (9) are arranged.

9. humidifier according to claim 8, characterized in that the at least one humidifier module (5) on the ribs (9) is supported.

10. Humidifier according to one of claims 1 to 9, characterized in that the inlet openings (3) and the outflow openings (4) associated with collector (10).