EP3696468A1 - Membrane element for a humidifier and method of manufacturing said membrane element - Google Patents

Abstract

Membrane element consisting of flat membrane material on a clamping frame, the clamping frame consisting of injection-moldable plastic and the membrane material preferably being hydrophobic and microporous. Method of manufacturing a membrane element.

Description

Field of invention

The invention relates to the membrane of an air humidifier and membrane elements for forming the membrane. The invention also relates to a method for producing a membrane element.

background

Air humidification devices which use a membrane that is impermeable to water and permeable to water vapor are known. So explained DE 10 2008 038 557 A1 the disadvantages of the known air humidifier and proposes an air humidifier with a separating membrane, in particular with a separating membrane made of a hydrophobic material such as polypropylene (PP) or poly-tetrafluoroethylene (PTFE). It is proposed to regulate the humidification performance by means of the temperature of the water acting on the membrane on one side. The range from 10 to 60 ° C., in particular 15 to 35 ° C., is suggested as the water temperature. Further air humidifiers with a membrane are in US 2005/0252982 A1 and WO 88/06912 shown. DE 10 2012 008 197 A1 shows a special membrane structure with pockets made of membrane material. It can be seen that the water is strongly cooled on the membrane by the energy necessary for evaporation, which makes the operation of such air humidification devices with low water temperatures inefficient. In practice, therefore, a relatively high water temperature is required in order to achieve good humidification performance and to avoid cooling the water into too deep an area.

Presentation of the invention

The invention is based on the object of creating membrane elements for providing a membrane for an air humidifier. This object is achieved by a membrane element according to claim 1 and is achieved by the membrane formed from such elements.

Another membrane element is defined with the features of claim 12 and with the method for its production according to claim 17. The introduction of the membrane directly into the webs creates very good tightness of the membrane elements and inexpensive manufacture.

The flat membrane is advantageously reinforced, which is achieved on the one hand by laminating the membrane with part of its water-side surface onto a thin inner support structure of the flat membrane. A separate outer support structure can preferably also be provided.

If an air humidification device with a preferably hydrophobic membrane, which is impermeable to water but permeable to water vapor, is operated in such a way that the water mass flow in kg / h flowing past the membrane is selected to be a factor X greater than the water vapor mass flow in kg / h exiting the air duct from the membrane , where the factor X is greater than 5, it is found that the cooling of the water on the membrane can be kept so low that a good humidification performance can also be achieved with water at a comparatively low temperature flowing to the membrane. Thus, with the use of a large amount (mass) per time of water in comparison to the amount (mass) per time of the water vapor released into the air, the negative effect of excessive cooling of the water can be avoided, which also makes the practical use of only moderately heated water allowed. It This also results in good heat and mass transfer and good avoidance of deposits due to the shear forces that are generated by the high flow velocity of the water. This also results in a precise control of the concentration of dissolved substances and possibly impurities per pass and also the formation of a so-called biofilm, a layer of slime in which microorganisms such as bacteria, algae and fungi are embedded, can be effectively prevented, which is hygienic Operation made easier. Local dead zones of the flow are also reduced, which results in a homogeneous temperature and concentration distribution over the surface of the membrane. This increases the humidification performance and also avoids local precipitation of dissolved substances and possible impurities on the membrane.

The desired water vapor mass flow can be specified, which results in the corresponding mass of water. The water vapor mass flow can also be measured in any known manner via the air mass and its humidity.

This can enable the use of water, for example, which has a similar temperature to the liquid in floor heating, which makes it possible to operate the air humidifier with energy from floor heating without the temperature of the water having to be additionally increased.

It turns out that a factor greater than 10 is particularly suitable, in particular a factor greater than 20, in particular a factor greater than 50 and in particular a factor greater than 50 to 250. The limitation of the size of the factor is essentially the result for practical reasons, since with a very high factor the water mass flow in the air humidifier becomes very large; As a rule, a factor greater than 500 will therefore not make any technical sense.

The control of the humidity can only be controlled by the water temperature of the water mass flowing past the membrane, and only by setting the factor X or the water circulation mass flow. A coupled control is preferably carried out so that the amount of water vapor per time or the humidity in the room to be humidified is effected both by influencing the water temperature and the amount of water per time or the factor X. Furthermore, the control with these two influencing variables is preferably dependent on the value of the water temperature. When the water temperature is low (just above the temperature of the air supplied), the influence of an increase in the water circulation mass flow is very small, since the temperature drop in the water when flowing through the membrane elements is also very small here, and thus also the change in the mean water temperature at the membrane. In particular, at a low water temperature of less than approx. 25 ° C, the control can be carried out essentially by influencing (increasing or decreasing) the water temperature, while at a higher water inlet temperature of approx. Greater than 40 ° C, the control can be done essentially by influencing the Factor X (increase or decrease of the same) takes place. In the temperature range between the stated values, the control takes place by influencing both the water temperature and the factor X. This can be a simple linear dependence of the two influences depending on the temperature. The temperature limits mentioned are only to be understood as an example and they can in particular also depend on the respective type and dimensioning of the membrane of the air humidification device, but can easily be determined by the person skilled in the art by means of experiments. An increase or decrease in the circulating water mass flow coupled to the water inlet temperature (to the membrane) is preferred for controlling the amount of water vapor or the humidification performance of the air humidification device. The amount of water is preferably measured with a flow sensor, in particular between a water pump of the air humidification device and the inlet into the container which contains the membrane. The temperature of the water is preferably also measured, in particular at the same point at which the water flow rate is also measured.

An important aspect of supply air humidification is compliance with a high standard of hygiene. While this is guaranteed with steam humidification by the high temperature of the steam, membrane humidification fulfills the hygiene requirements due to the following two aspects: On the one hand, the membrane is preferably hydrophobic and it can therefore be assumed that the germs and microorganisms in the water, such as e.g. Bacteria do not come into direct contact with the micropores of the membrane and thus do not migrate into the air flow. On the other hand, the (mean) pore size of the membrane is 0.05 micrometers to 0.25 micrometers, at most up to 0.5 micrometers and preferably approx. 0.1-0.2 micrometers, usually below the size of the germs or microorganisms.

A hydrophobic polymer such as polytetrafluoroethylene (PTFE), but also polyvinylidene fluoride (PVDF) or polypropylene (PP) or polyurethane (PU) can be used as the material of the membrane. Other, non-hydrophobic membranes and membranes with a hydrophobic surface coating (multilayer membranes / asymmetrical membranes) can also be used.

For the air and water flow, a counter-current arrangement, a cross-flow arrangement or a direct-current arrangement can be provided. A cross-countercurrent arrangement is also preferred as an embodiment described in more detail below.

In the invention, the membrane of the air humidification device is formed from a plurality of membrane elements which each have a frame formed from frame webs with a front side and a rear side and side walls. The membrane material is arranged flat on at least one side of these frames and is preferably flat on both sides, on the front and rear. The membrane material is attached in a watertight manner to the respective frame surfaces of the front and rear of the frame, so that a watertight space, delimited by the frame and the membrane surfaces, is formed within the frame, or, if necessary, a space is formed that is delimited by a membrane surface and a non-membrane surface, if a surface made of membrane material is only provided on one side of the frame, from which space only the water vapor can escape through the membrane. The frame has at least one opening leading into the room as a water inlet and at least one opening leading into the room as a water outlet on the side walls. Furthermore, the frame has in its interior at least one web, preferably several webs, which connect inner side walls of the frame, which webs have essentially the same thickness D over a first section as the frame webs and have a smaller thickness D1 over a second section of their length than the frame bars. The sections with a smaller thickness form water passages within the frame. The membrane surfaces are attached to the first sections of the webs in a watertight manner or, if necessary, a non-membrane surface is connected to the webs in a watertight manner if a membrane surface is only arranged on one side of the frame and the other side of the frame is closed by a non-membrane surface to create the watertight space to build.

This preferred embodiment of the membrane elements results in a very good possibility of fastening and stability of the respective membrane surface on the frame, in that it is also fastened to the webs is. The watertight fastening can be done, for example, by plastic welding of the membrane and the webs formed from a plastic, or by lamination or gluing.

Thanks to the stable attachment, operation with the large water mass flow is possible even with sensitive membranes. Due to the special arrangement of the webs and the water passages in the frame, a desired flow path for the water can be achieved in a simple manner. It is preferred that at least one web is provided, but in particular that several webs are provided, the first sections of which are arranged alternately starting from opposite side walls of the frame. In this way, a cross-countercurrent arrangement can easily be achieved, since the water flow inside the frame is effected accordingly. There is also a higher mean flow velocity, the avoidance or reduction of dead zones and a good heat and mass transfer.

A further stabilization of the membrane elements or the membrane composed of them results when at least some of the webs, in particular all of the webs, are connected to one another or to a side wall by means of support webs running essentially transversely to the webs, the support webs having the smaller thickness D1 have or have an even smaller thickness so as not to disturb the flow of water.

It is further preferred for the water flow if the respective end of the first section is rounded off in at least one of the webs, in particular in all webs, of the membrane elements. Furthermore, the respective end of the first section in at least one of the webs or in all webs can be bent away from the first opening, and thus from the water inlet. Both measures, individually or preferably in combination, are advantageous for the water flow in the frame and avoid or reduce dead zones.

In the case of the membrane elements, formations can be provided on second sections of smaller thickness D1 within the water passages formed by them, which provide additional surfaces for fastening the membrane material above the water passages in order to stabilize the membrane surface. In particular, such formations can be provided on both sides of a respective second section if a membrane surface is attached to the frame on the front and rear.

It is further preferred that in the membrane elements in the webs in the area of their connection with the side walls channels are provided, the cross section of which is many times smaller than the cross section for the water provided by the respective water passages. This creates channels for any drainage of the membrane elements when the air humidification device or its water system is switched off, in order to be able to avoid standing residual water for reasons of hygiene. However, the channels are designed with such small diameters that they do not disturb the flow of water during operation.

The membrane elements are preferably provided with positioning means arranged on the frame in order to connect several membrane elements to form a large membrane as the sum of the respective membrane areas of the elements. The air passages for the air to be humidified, which air flows past the individual membrane surfaces, are formed between the membrane elements.

In another exemplary embodiment with a flat membrane, at least two vertically running membrane channels through which water flows are arranged one behind the other in the flow direction of the air. In cross section This arrangement is repeated over the width of the channel, separated by an air gap. In the rear membrane channel, viewed in the air flow direction, the warm water flows from the water guide arrangement from bottom to top, i.e. against gravity, into an upper header tank and from there flows further in the front membrane channel from top to bottom into the drain or preferably back into a recirculation cycle. The advantage of this so-called cross-countercurrent arrangement, which also results in this example, is primarily that the difference in the water vapor partial pressure between the two sides of the membrane (i.e. within the water-carrying side of the membrane to the air side of the membrane) is greater on average than if it were only there is a direction of flow on the water-carrying side, and thus the total water vapor diffusion is also higher. Furthermore, it can also be rated as a structural advantage if the entire water supply and the control can be arranged on the underside of the membrane humidifier.

Basically, in the procedure described above, not only - as a primarily desired effect - water vapor diffuses through the membrane wall for humidification, but at the same time the evaporation of a small part of the water to water vapor within the membrane channels gradually cools the water and at the same time also finds its way through the Membrane wall heat transport takes place.

Since a flat membrane has only a low inherent stability, it is preferably reinforced. This can be done on the one hand by fastening, for example by fastening, in particular by means of welding or lamination, of the membrane with part of its water-side surface to an inner support structure. Thus, an inner support structure is provided in the water flow area of the membrane and is designed in such a way as to inhibit the water flow as little as possible. A preferred example of membrane elements designed in this way to form the membrane has been explained above. Furthermore, an outer support structure for the membrane can also be provided in the air flow area. The membrane can be attached to the outer support structure or can only lie loosely or be pressed on by the water pressure. The advantages of the flat membrane are easier cleaning and lower pressure loss in the air duct.

Brief description of the drawings

• Figur 1 eine schematische Darstellung von Ausführungsformen einer Luftbefeuchtungsvorrichtung gemäss der Erfindung, zur Erläuterung von deren Aufbau und deren Betrieb;
• Figur 2 ein Membranelement mit zwei Membranflächen in Draufsicht, wobei die vordere Membranfläche nicht dargestellt ist, so dass das Innere des Membranelements ersichtlich ist;
• Figur 3 schaubildlich einen Teil des Membranelements von Figur 2;
• Figur 4 schematisch eine andere Anordnung von Membranelementen bei einer mit Flachmembranflächen ausgeführten Membran eines Luftbefeuchters mit einem horizontalen Schnitt durch den Behälter der Luftbefeuchtungsvorrichtung;
• Figur 5 eine schematische Darstellung der Membran mit Kapillarmembranflächen anhand eines horizontalen Schnitts durch den Behälter der Luftbefeuchtungsvorrichtung;
• Figur 6 schematisch ein Membranelement mit einem Rahmen und einer Membranfläche; und
• Figur 7 schematisch einen Schnitt durch einen der Stege von Figur 6 mit der Einbettung der Membranfläche im Kunststoff des Stegs.

Further refinements, advantages and applications of the invention emerge from the dependent claims and from the description that follows based on the figures. Show:

• Figure 1 a schematic representation of embodiments of an air humidifying device according to the invention, to explain its structure and its operation;
• Figure 2 a membrane element with two membrane surfaces in plan view, the front membrane surface not being shown, so that the interior of the membrane element can be seen;
• Figure 3 diagrammatically part of the membrane element of FIG Figure 2 ;
• Figure 4 schematically another arrangement of membrane elements in a membrane of an air humidifier designed with flat membrane surfaces with a horizontal section through the container of the air humidification device;
• Figure 5 a schematic representation of the membrane with capillary membrane surfaces based on a horizontal section through the container of the air humidification device;
• Figure 6 schematically a membrane element with a frame and a membrane surface; and
• Figure 7 schematically a section through one of the webs of Figure 6 with the embedding of the membrane surface in the plastic of the bar.

Way (s) for carrying out the invention

Figure 1 shows schematically and by way of example an air humidification device 10, the parts belonging to the device being shown within the area delimited by the broken line. The air humidification device 10 is arranged, for example, in a technical room 11 and serves to humidify the air that is supplied to a room, for example the living room 22, which is only indicated. However, the invention can generally be used in the field of air conditioning (HVAC).

Air that is discharged from the living space 22 is in this example fed by a fan 24 via a line 23 to an air-to-air heat exchanger 25 in the technical room 11 and from there via the line 27 into the surroundings outside the building, in where the technical room and the living room are located. Air entering from the environment via the line 26 passes through the heat exchanger 25 and the fan 24 'into the air humidification device 10 and from there via the line 28 into the living space 22. The fans 24, 24' and thus the flow rate of the air also have a Influence on the humidification performance. The absolute humidification performance in kg / h tends to increase somewhat with increased air speed. As a rule, however, the fans are not part of or are not under the control of the air humidification device 10. The (rather minor) influence of the fans is therefore not considered here.

The air humidification device 10 comprises a diaphragm 1, shown only schematically, by means of which the air to be humidified is supplied with water vapor in the amount M1 per hour (kg / h). The membrane 1 usually consists of several membrane elements or membrane surfaces which together form the membrane with an effective total membrane surface. Warm water is supplied to one side of the membrane and evaporating water can pass through the membrane to the other side in the form of water vapor, where it is absorbed by the air carried past the other side of the membrane as an air stream. This is known in principle and was explained at the beginning.

The membrane 1 is arranged in a container 2 which contains the membrane elements or the individual membrane surfaces which together form the membrane. These can in particular flat elements, as also already explained. In the container, the membrane elements forming the membrane 1 are arranged and designed so that the water flows past on one side and the air to be humidified on the other side. For this purpose, the container has an inlet 3 and an outlet 3 'for the air flow, as well as an inlet 4 for the warm water and an outlet 4' for the less warm water, which has a lower temperature than that at inlet 4 in FIG water that has entered the container. The inlets and outlets for the air and the inlets and outlets for the water are only indicated in the figure; the person skilled in the art knows how such inlets and outlets or connections for air and water pipes are designed.

The air humidification device has a water guide arrangement, which is intended to denote the entirety of the lines, water containers, valve and pump means which serve to bring the water used for humidification into the container 2 and thus to the membrane 1 to lead and to take up the water emerging from the container 2 again. The water guide arrangement preferably has a water circuit so that water emerging from the container 2 can re-enter the container. In between there is at least one step of heating the water so that it again contains enough energy to evaporate part of the water on the membrane.

In the example shown, the water emerging from the container 2 at the outlet 4 'passes via a line 4 ″ and elements 30 and 31, which are optional and will be explained later, by means of the line 5 into a water container or tank 6 and from there over a pump 7 into the line 8, which feeds the water back to the container 2 and thus to the membrane 1. A sensor 33 is preferably provided which emits an output signal which gives a measure of the concentration of the substances dissolved in the water the tank 6 and the pump 8, a conductivity sensor can be installed in the line as a sensor 33, which outputs the conductivity of the water as a measured value, which is a measure of the concentration of the dissolved substances in the water, which measured value is transmitted to the control arrangement 35 a high conductivity value, which is above a suitable, predetermined limit value, the control unit gives a control signal to blow down water with ho Her concentration of dissolved substances at the drain valve 34. The tank 6 is preferably present in order to be able to provide a sufficient amount of water in a simple manner. Furthermore, the tank allows the amount of water in the system to be determined in a simple way and to keep the system generally depressurized. Furthermore, as mentioned, a tank allows the minerals that have accumulated in the water to be discharged by draining water with a comparatively high concentration of dissolved substances and replacing it with fresh water with a lower concentration of dissolved substances. This process is carried out in the Technical terminology often referred to as "blowdown". If a sufficiently long line length is accepted, the tank can be dispensed with; the amount of water for operating the device is then available in the line sections of the water conduction arrangement.

At least one sensor is preferably provided which determines the water temperature in the water guide arrangement. A sensor 33 'is preferred, which determines the water temperature at a point between the pump 7 and the membrane. The water temperature value determined by this sensor is preferably transmitted to the control arrangement. The control arrangement can use this temperature value in order to influence the water vapor generation by increasing or decreasing the water temperature and / or by increasing or decreasing the factor X, which has been described as a preferred procedure at the beginning. Furthermore, a sensor is preferably provided, for example sensor 33 ″, which determines the water mass flow in the circuit and which preferably transmits the flow rate of the water to the control arrangement, which leads to a controlled setting of factor X. As a preferred embodiment, the sensor is a combined temperature and flow sensor.

The water is heated with a heating device which can heat the water in any known manner. An example is an electric water heater 32, which is preferably arranged in the tank 6 but could also be present elsewhere in the water guide arrangement. This heating device can be operated electrically or in another known manner. The heating device can comprise a fluid-fluid heat exchanger and in particular a water-water heat exchanger 31 as a further means, this instead of the water heater 32 or in addition to it. With the heat exchanger 31, the water cycle in a floor heating system of the building is preferred and particularly preferred Heat is withdrawn from the water circuit of the floor heating of the room 2 in order to heat the water in the water guide arrangement of the air humidifier 10.

Since water is withdrawn from the water guide arrangement during the humidification by means of the membrane 1, a means is preferably provided in order to supply water to the water guide arrangement continuously or discontinuously from a water source external to the device 10. This is in the schematic view of Figure 1 with the schematically shown water connection 9 and the valve 9 'and the line 9 ", with which water from an external water source can be added via the collector 30 to the water that is discharged from the container 2 via the outlet 4' and the line 4" exit. This is only shown roughly schematically, but the person skilled in the art knows how to combine the two water lines 4 ″ and 9 ″ to form the line 5. The valve 9 'is actuated by the control arrangement 35 of the air humidification device, which will be explained below. For this purpose, the valve 9 ′ is an electrically controllable valve which is connected to the control arrangement 35 via an electrical control line (not shown).

The water tank preferably has an element which determines the fill level of the tank and which is preferably connected to the controller. This is preferably a schematically illustrated float whose position serves as a level control and this float can be connected to the control arrangement so that the control arrangement can derive information about the amount of water in the water supply arrangement via the float level. The tank 6 is provided with a drain, in particular for the so-called blowdown. Mineralization of the water in the tank or, in extreme cases, sludge formation on the tank bottom, can occur in particular when using tap water in the water cycle and such substance concentrations can be removed via an openable drain, whereupon the drain is closed again. The drain can also be activated via a controllable valve if maintenance or cleaning work necessitates emptying the tank and possibly the entire water supply system.

The control arrangement can be implemented by means of a computer or an industrial controller in a manner known to the person skilled in the art. The controller receives information via a signal line 36 and a sensor 37, for example, which provides information about the amount of water vapor mass flow at the outlet of the container 2, and thus information about the amount of water vapor per time that is supplied to the room 22. It can compare this with the information about the target humidity in the room and thus determine the requirement for the amount of water vapor per time. The mere specification of the nominal humidity can also suffice, since with a given room size it is basically known how much water vapor is required per unit of time. The setpoint humidity can be set on the control arrangement or via a separate setting element connected to it. It can also be provided that the actual humidity in the room is determined by at least one humidity sensor and transmitted to the control arrangement. These means are not shown here, but are known to the person skilled in the art and need not be explained further here. With this information, the control arrangement ensures that sufficient moisture is supplied to the room. The air flow into the room can be controlled by the control arrangement or usually a separate control arrangement of the so-called ventilation device, in particular by controlling the fans 24 and 24 '. This is not explained further here.

The control arrangement sets the water mass flow through the container 2 per time so that the water mass flow (which is also determined in kg / h, for example) is at least 5 times greater than the water vapor mass flow. For this purpose, the control arrangement can use the information from the flow meter mentioned and control the pump 7 accordingly.

The factor is preferably greater than 10 and in particular the factor is greater than 20 and in particular the factor is greater than 50. In particular, the factor is set in the range from 20 to 250.

The factor can be used to ensure that even with little warm water, for example with a temperature of only 25 degrees Celsius and particularly preferably in the range of 20 degrees Celsius to 60 degrees Celsius and in particular in the range of 25 degrees Celsius to 45 degrees Celsius safe operation of the humidifier is possible. For this purpose, the control arrangement 35 is connected to the water supply arrangement by means of a control line 38 and can thus, as mentioned, control in particular the pump 7, which conveys the amount of water per time that is required to maintain the factor. The control arrangement also controls the valves explained and receives information about the water level and the water temperature. It also controls the heating of the water. All of these control signals and feedback signals from sensors (some of which are not shown) are in the Figure 1 summarized in the control line 38 for their simplification.

The container 2 can - unlike in the schematic Figure 1 shown, vertically or arranged so that the water flows from bottom to top or against gravity through the container, which makes it easier to control the water flow.

Based on Figures 2 and 3 a preferred membrane element 60 is described. At least one such membrane element and, as a rule, several such membrane elements 60 together form the membrane 1 in the container 2. The membrane element according to this preferred embodiment has a frame 65, which in the example shown is rectangular and the frame webs 61, 62, 63 and 64 has. The webs have a web width B (which does not have to be the same for all webs), a web thickness D and a length, wherein in the case of a rectangular frame 65 opposing webs 61 and 63 or 62 and 64 have the same length. In the case of this membrane element 60, two membrane surfaces M are provided, which are opposite one another and are spaced apart by the web thickness D. In the Figures 2 and 3 only the rear membrane surface M made of the membrane material is shown in the figure and the front membrane surface is not shown so that the frame and the interior of the membrane element can be seen. Both membrane surfaces M together with the frame delimit the interior of the membrane element 60 in which the water flows. In one embodiment, only one side of the frame can be provided with a membrane surface and a cover not made of membrane material is provided on the other side of the frame.

The materials mentioned above as examples are also preferred as membrane material in this exemplary embodiment. In this example, the respective membrane surface M is fastened to the outer sides of the frame webs, which outer sides have the width B or widths B different from one another. On these outer sides, the respective membrane surface is fastened lying on the respective outer side. The material of the webs of the frame 65 is preferably a plastic material which allows the membrane surfaces M along the frame webs to be attached to the frame in a watertight and cohesive manner by plastic welding or to the frame by laminating the membrane material onto the frame webs. Instead of or in addition to welding, adhesive bonding could also be provided, for example by means of a hot-melt adhesive.

On the side walls, the frame has at least one first opening 70 as a water inlet and at least one second opening 71 as a water outlet. The opening 70 stands with the line 8 or the inlet 4 of Figure 1 in communication and the opening 71 is with the outlet 4 'of Figure 1 in connection, this being the case for a membrane formed from a plurality of membrane elements for all corresponding openings 70 and 71 of the frames 65, which are connected to the common line via distributors.

In its interior, the frame has at least one web 67. The frame preferably has several webs 67; eight webs 67 are provided in the example shown. The web connects, or these webs connect, inner side walls of the frame, in the example shown the inner side walls 62 ″ and 64 ″, since the webs 67 connect the frame webs 62 and 64 in this example. The webs 67 each have a first Section 68 has essentially the same thickness D as the frame webs 61 to 64, so that the membrane surface M of the respective membrane element rests both on the frame webs and on the webs 67 and can also be attached to the webs 67 at their first sections 68. This is usually done in the same way as the attachment to the frame webs, that is, by welding or by lamination or by gluing or a combination of these fastening options. The membrane is also attached to the webs 67 in a watertight manner, so that the water at these locations or does not flow through between the membrane and the web in the area of the sections 68. In contrast, the webs 67 each have a second section 69 their length in which the webs have a smaller thickness D1 than the frame webs. The membrane material M is not attached to these sections 69, which are set back in relation to the outer sides of the frame webs and in relation to the sections 68 in the direction of the inside of the frame. In comparison with the sections 68 which block the flow, the recessed sections form, on the contrary, passages for the water through which the water on its way can flow through from the water inlet 70 to the water outlet 71. Thus, the arrangement of the webs 67 can predetermine a path for the water within the membrane element 60, the water flowing past the inside of the frame or in the interior 66 on the inside of the membrane surfaces M.

The webs 67 are preferably arranged in the frame in such a way that their thicker sections are alternately arranged starting from opposite side walls 62 ″, 64 ″ of the frame in order to create a meandering path for the water or a cross-countercurrent arrangement for the water and the air flow to form like this in Figure 2 is indicated by the arrows F for the water directions, while the arrow L indicates the direction of the air flowing through the container 1, which flows past the outer membrane surfaces of the membrane elements or outside the frame.

It can be provided, and is shown in the example, that on second sections 69 of lesser thickness D1 of the webs within the water passages formed by them, formations 56 are provided on the webs, which provide a surface for fastening the membrane material also inside or above the water passages . The surfaces of these formations 56 are preferably arranged again in such a way that the frame thickness D results there again, so that the membrane surfaces M can also be attached to these surfaces 56. Despite these formations, the water can flow through the passages in the second sections 69 of the webs. The formations 56, however, provide a further stabilization of the membrane surface, so that it can withstand the pressure and the flow of the water in the membrane element. In the case of membrane surfaces on both sides of the frame, a recess 56 is preferably provided on both sides of a respective second section 69. This can also be used to prevent or reduce vortex and dead zones.

To stabilize the webs 67 and thus to reduce the load on the membrane surfaces M attached to the sections 68 and possibly surfaces 56 of the webs, it is preferred that webs 67 run essentially transversely to the webs or possibly obliquely to the webs Support webs 59 are connected to one another or to a side wall 61 ″, 63 ″, the support webs 59 having the smaller thickness D1 or preferably an even smaller thickness in order to impede the water flow only slightly.

In order to influence the water flow, provision can also be made for the end 58 of the first section 68 in at least one of the webs 67 to be rounded, as shown in FIG Figures 2 and 3 is shown at all bridges. In addition or as a sole measure, it can be provided that in at least one of the webs 67 the end 58 of the first section 68 is bent away from the first opening 71, as is the case in FIG Figures 2 and 3 is shown at all webs. In order to influence the flow in the frame, a recess can also be provided on the inner side wall adjacent to the opening forming the water inlet, as in FIG Figure 2 and Figure 3 shown.

Furthermore, channels 55 can be provided in the webs 67 in the area of their connection to the side walls (not all of which are designated 55 in the figure), the cross-section of which is many times smaller than the cross-section for the water provided by the respective water passages . These channels facilitate the drainage of the membrane elements or the membrane when the hydraulic system of the air humidification device is switched off or when it is out of operation and thus make it possible to avoid residual water that is undesirable from a hygiene point of view.

So that the large number of membrane elements can be easily connected in a defined position, Positioning means 73 arranged on the frame are also preferred, which also facilitates the formation of a membrane in which uniform air passages are formed between the membrane elements.

In a further embodiment of a membrane with membrane elements, shown only in a very simplified manner, is with Figure 4 a horizontal section through a vertically arranged container 2, the container wall of which is only indicated with broken lines, is shown roughly schematically. In the container membrane elements 41 are arranged, in which the water flows. Together, the membrane elements 41 form the entire membrane 1. In this example, membrane elements 41 arranged at the bottom of the container are shown in which the water introduced into the container (via the inlet 4 of Figure 1 ) flows upwards in the container and membrane elements 41 shown at the top in the container, in which the water flows back down to the outlet of the container (outlet 4 'in Figure 1 ). The air, which is indicated by the arrow L and which absorbs the water vapor emerging from the membrane elements 41, is guided through the spaces 45 between the membrane elements.

Figure 5 shows a schematic horizontal section through a container 2, the container wall of which is only indicated with broken lines, in which container the membrane not according to the invention is formed by a plurality of cylindrical membrane elements 40 arranged in rows, which together form the membrane (only two rows are shown , the other rows are only indicated with dash-dotted lines). The water flows in the cylindrical membrane elements 40 and the air is guided through the spaces 45 according to arrow L in order to moisten the air.

Figure 6 shows schematically a frame 42 in which a flat membrane part M made of the aforementioned membrane material is clamped. Such an element 41 ' forms with a second such element or with a closed rear wall a membrane element in which a space for the water is formed which is delimited by the membrane element. In this space there is usually also a support structure - not shown here - for the membrane surface, on which the water-side membrane surface is fastened with part of its surface, in particular is welded or laminated. The support structure is designed in such a way that it enables the flow of water or inhibits it as little as possible. Instead of being clamped in the frame as shown, the membrane can also be attached to the outside of the frame webs, in particular by welding or lamination or gluing.

According to one aspect of the invention, a membrane element for an air humidifier, in particular for the air humidifier described above, is formed in such a way that the membrane material M of the membrane arrangement is a microporous material and is preferably a hydrophobic microporous material. In particular is a material with a nominal pore diameter in the range from 0.05 to 0.5 micrometers and in particular a material with a nominal pore diameter of 0.05 to 0.25 micrometers, and in particular with a pore diameter in the range from 0.1 to 0.2 micrometers. The microporous material is formed from a, preferably hydrophobic, polymer, for example from polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF) or polypropylene (PP) or polyurethane (PU). The membrane material M is arranged flat and with its edge 44 fastened in a clamping frame 42, for example in a square or rectangular clamping frame 42, the cross-section of the frame webs being at least partially made of an injection-moldable plastic and the membrane material being fastened to the webs by being surrounded by the plastic with its edge areas. Figure 7 which shows a section through the frame and membrane material along line A - A of figure 6 shows that the edge of the flat part 40 of the membrane material is embedded in the edge. Such a membrane arrangement is preferably produced in such a way that the frame webs are at least partially injection molded from a plastic, viewed over their cross-section, the membrane being fastened in the webs by being cast with its edge regions 44 directly into the frame webs during the injection molding process. A reinforcement 43 made of a different material than the plastic web material can be provided in the frame webs. As mentioned, however, a membrane can also be fastened on the outside of the web instead of the shown fastening around the web, in particular by welding or gluing to the web.

It can further be provided that the membrane surface is reinforced by an outer support structure made of a material different from the membrane material, or that the membrane surface is reinforced by an outer support structure made of the same material as the membrane surface. The membrane surface can be laminated onto the support structure, or the membrane surface can rest loosely on such a support structure. The support structure is not shown in the figure. It can also be web-shaped and form a grid, for example. Such a support structure can also serve to bring about a turbulent air flow over the membrane. This must be distinguished from the already mentioned inner support structure on the water flow side.

While preferred embodiments of the invention are described in the present application, it should be clearly pointed out that the invention is not restricted to these and can also be carried out in other ways within the scope of the following claims.

Claims (6)

Membrane element for an air humidification device, the membrane material (M) of the membrane element being a preferably hydrophobic, microporous material, in particular a material with a nominal pore diameter in the range 0.05 to 0.5 micrometers, in particular a material with a nominal pore diameter of 0.05 to 0.25 micrometers, and in particular a material with a nominal pore diameter of 0.1 to 0.2 micrometers, and wherein the material is formed in particular from polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF) or polypropylene (PP) or polyurethane (PU), the membrane material being arranged flat is and is fastened with its edge (44) in a clamping frame (42), the frame webs seen over their cross section are at least partially formed from an injection-moldable plastic, and the membrane material is attached to the webs by having its edge areas of the Plastic is surrounded, or that the membrane material is attached with its edge resting on the outside of a clamping frame by welding or lamination or gluing. Membrane element according to claim 1, characterized in that the membrane surface is reinforced by an outer support structure made of a material different from the membrane material, or that the membrane surface is reinforced by a support structure made of the same material as the membrane material. Membrane element according to Claim 2, characterized in that the membrane is laminated onto the outer support structure, or that the membrane rests loosely on an outer support structure. A membrane element according to any one of claims 1 to 3, wherein the membrane element has an internal support structure has, on which the membrane surface or the membrane surfaces are laminated or welded or glued with part of their water-side surface. Membrane, formed from several membrane elements according to one of Claims 1 to 4. Method for producing a membrane element according to one of claims 1 to 4, wherein the frame webs, viewed across their cross-section, are at least partially injection molded from a plastic, the membrane surface being attached to the webs by inserting their edge regions directly into the frame webs during the injection molding process is poured.

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