DE102008019829A1 - Mass transport between two fluids, for dehumidifying air in an air conditioning system, uses a membrane absorber formed by permeable and impermeable films - Google Patents

Abstract

The mass transport between two fluids (A,L) through a membrane uses a membrane absorber, e.g. for dehumidifying air in an air conditioning system. Two films (FM1,FM2,AF1,AF2) are bonded together along strips (S) to form a channel (K) between two strips (S1,S2) for the first fluid as an absorber (A). One film acts as a porous membrane, permeable for the absorber to pass into the masses to be absorbed in the other fluid (L). One of the other impermeable films (AF1,AF2) acts as the outer wall against an adjacent heat exchanger plate. The impermeable films are coupled (Z) together at the strips.

Description

The The invention relates to a device for mass transport between two fluids through a membrane, in particular a membrane absorber, after the preamble of claim 1.

For dehumidifying the supply air in air conditioning liquid absorber media can be used, for. B. dissolved in water salts such as LiCl or CaCl ₂ . These are brought into contact with the air; due to the water partial vapor pressure gradient towards the hydrophilic salt solutions, these absorb water vapor from the air.

Techniques, in which such a solution as a trickle film or sprayed directly in contact with the supply air have the disadvantage of lacking Hygiene; there is a risk of having corrosive salt droplets to tear into the room air.

Now separating the salt solution from the air through a microporous membrane (see. EP 0 013 075 B1 ), so this danger no longer exists, but the dehumidification performance decreases due to the diffusion resistance of the membrane for water vapor. Therefore, special attention must be paid to large exchange surfaces and to the geometry and material of the heat / substance carrier in the case of corresponding components.

Basically, the colder the saline solution is, the more water it can absorb. However, during the absorption process, heat is released, so the solution would heat up. To compensate for this effect, you can lead precooled solution in the absorber ( EP 532 368 A2 ). However, this is usually not useful due to the then necessary low temperature.

It the possibility remains, simultaneous to the absorption the solution for example via a cooling water circuit to cool, so you need a water-salt solution-air-heat and cloth exchanger.

• 1. Senkrecht im Luftstrom stehende Röhrchen, abwechselnd
• – einmal aus stabilen porösen Polypropylen-Röhrchen, die von der Lösung durchflossen sind,
• – einmal aus Edelstahl, von Kühlwasser durchflossen, jeweils in Kunststoffrahmen, diese hintereinander gestapelt.
• 2. Matrix aus Polyvinylidenfluorid, bei der benachbarte Kanäle senkrecht zueinander von den unterschiedlichen Medien durchströmt werden.

Implemented and partly available on the market are the following techniques:

• 1. Tubes standing vertically in the airstream, alternating
• - once from stable porous polypropylene tubes, which are flowed through by the solution,
• - Once made of stainless steel, flowed through by cooling water, each in plastic frame, these stacked one behind the other.
• 2. matrix of polyvinylidene fluoride, in which adjacent channels are flowed through perpendicular to each other by the different media.

It Object of the invention, a device with high mass transport performance for mass transport between two fluids through a membrane (in particular a membrane absorber with high dehumidification performance), which can be produced with little effort.

These Task is solved by a device with the features of claim 1

there has started from the idea that on the one hand cooling must take place simultaneously with absorption and that on the other hand, the structure of the device of film webs the Can facilitate series production.

advantageous Embodiments of an inventive Device are specified in the subclaims.

Based two embodiments of a membrane absorber The invention will now be explained in more detail. there the same reference numerals in different figures indicate each other corresponding parts and / or functions.

It show schematically:

1 FIG. 2: a cross section through a basic building block of a first exemplary embodiment of a membrane absorber according to the invention, FIG.

2 : A perspective view of a section of a basic building block of a second embodiment of a membrane absorber according to the invention,

3 : A stack with several basic building blocks 2 .

4 : Part of a cross section of a variant (to 1 ), which allows to carry out the manufacturing process with films of equal length.

According to 1 For example, a basic building block of the first embodiment includes at least one heat exchanger plate and adjacent channels K (for an absorber medium A) between the heat exchanger plate and a surface membrane FM1 adjacent to the fluid (eg, air L) from the mass (eg, moisture ) are to be transported through the surface membrane into the absorber medium A (eg saline solution). In this case, the heat exchanger plate consists of two outer wall films AF1, AF2, which are welded or glued together along mutually parallel strips S, so that between the strip S tunnels T arise through which a heat exchange medium W (for example, cooling water) in the longitudinal direction of the tunnel ( ie perpendicular to the plane of the drawing) can flow. The foils AF1, AF2 in each case between the strips S inflated to the tunnels T by the operating pressure of the heat exchanger medium.

An alternative (to which further details in 1 refer) is that the two outer-wall films AF1, AF2 along the strips S are so patchy welded or glued together that the heat exchange medium W across the strips S from an inflow channel Wz to a drainage Wa through gaps in the welding or Adhesive seam and across the tunnel T can flow, the tunnels in turn are created by the fact that the films AF1, AF2 are inflated in each case between the strips S by the operating pressure of the heat exchange medium.

Between two tunnels have been created along the strips S furrows F, which are corrugated in the direction perpendicular to the plane, because welded / glued Points and passages for the heat exchange medium W alternate with each other.

From the three lines that are in the area of the strip S in the drawing are shown, the middle line illustrates a cut Welding / splice where at least the outer wall foils AF1, AF2 are interconnected (hereinafter coupling element Named Z); the two outer lines point in the view between two (perpendicular to the plane of each other following) welding / splices bloated Slides FM2 with AF2 and FM1 with AF1, where between AF1 and AF2 a passage for the heat exchange medium W emerged is.

in principle need only on one side of the heat exchanger plate (AF1 with AF2) channels for the absorber medium A arranged to be. Preferred and shown here but are channels K on both sides of the heat exchanger plate.

Below of the upper basic module (Wz, T, Z, K, S, F, AF2, FM2, AF1, FM1, Wa) is in the drawing, a second basic building block of the same Kind arranged. In practice, you will be more such basic building blocks complete.

In 2 two foils FM1, AF1 are stitched to one another along strips S, S1, S2, which run essentially parallel to one another, so that a channel K for passing through an absorber medium A results between each two strips S1, S2.

A of the films is formed as a porous surface membrane FM1 and thus permeable to that of the absorber medium A medium to be absorbed, for example for water, which is located in air L, which is below the surface membrane FM1 flows along this.

The second film AF1 serves as the first of two liquid-tight Exterior wall foils AF1, AF2 of an adjacent heat exchanger plate. This consists (as will be apparent from the following) three interconnected foils AF1, G, AF2.

at Operating pressure of a heat exchange medium W, the between the outer wall films AF1, AF2 can be introduced (around there flowing heat), at least forms an outer wall film AF1 with its outer surface Furrows F off, parallel to each other and along the strips S lost.

The both outer wall foils AF1, AF2 are spaced apart Coupling elements Z connected to each other, each at two adjacent Furrows F attack different outer wall films.

The Coupling elements Z are designed so that the heat exchange medium W mainly transverse to the grooves F between the outer wall foils AF1, AF2 can flow past the coupling elements over.

one Relatively easy manufacturability benefits that the coupling elements Z components of a foil grid G are those at the furrow areas the outer wall foils AF1, AF2 is attached.

Farther it makes a relief on the manufacturing process that the foil grid G consists of a perforated foil.

at continuous production of an inventive Membrane absorber made of films, it is advantageous that the foil grid G - transverse to the furrows F of a series of furrows F of one (AF1) or the other (AF2) outer wall film measured - the Same length as that area of the corresponding Exterior wall foil, which has the corresponding sequence of furrows F has. In other words, when not bloated (ie in the production as well as before commissioning) are the Foils AF1, G and AF2 are mutually equal in direction perpendicular to the stripes / furrows. The porous surface membranes FM1, FM2, on the other hand, are longer to operate bulge more than the outer wall foils, so that through the spaces (channels K) the Absorber medium A can flow.

It is according to 4 It is also possible to use surface membranes FM1, FM2 which are as long as the foils AF1, AF2 if the width of the strips S (which respectively connect the foils FM .. to the outside wall foils AF ..) is less than the width the furrows F (which the outer wall Fo In their own right, AF .. are self-sufficient at operating pressure because they are interconnected in the furrow area).

When Absorber medium A is preferably a hygroscopic saline solution.

When Heat exchange medium W can serve cooling water.

The basic building block after 2 can also be understood as a heat exchanger plate (consisting of the elements AF1, AF2, Z) with saddled channels K for the absorber medium. Although the principle of the present invention is already given, if only K on one side of the heat exchanger plate (ie on the first outer wall film AF1) channels K are provided, shows 2 the preferred embodiment of a membrane according to the invention, in which both sides of the heat exchanger plate AF1, AF2, Z channels K are provided for an absorber medium A, which are bounded away from the heat exchanger plate in each case by a porous surface membrane FM1, FM2, respectively along the strips S and Furrows F is connected to the heat exchanger plate.

3 indicates how a stack of several basic building blocks can be arranged. The stack is to be installed in a conventional manner in a housing, and the spaces between the basic blocks are flushed during operation of the mass to the absorber medium donating medium (for example, air to be dehumidified).

In the production of a basic building block, the production of a heat exchanger plate is started. For that, the EP 0 952 913 B1 (= DE 698 01 982 T2 ) Give suggestions.

• – Foliengitter G: Dickere Trägerfolie (z. B. 150–200 μm), mit regelmäßigem Lochmuster (z. B. 4 mm Lochdurchmesser, 6 mm Lochmittenabstand in beiden Dimensionen), welche die Koppelelemente Z enthält,
• – Zwei Außenwand-Folien AF1, AF2: evtl. dünner (z. B. 50–100 μm), einfache Folien.

In the heat exchanger plate of the membrane absorber according to the invention, water serves as a heat exchange medium, so that it can also be referred to as a water surface channel. This consists basically of three originally flat film layers which are equal to each other in the direction perpendicular to the strips S, namely:

• Foil foil G: thicker carrier foil (eg 150-200 μm), with regular hole pattern (eg 4 mm hole diameter, 6 mm hole center distance in both dimensions), which contains the coupling elements Z,
• - Two outer wall foils AF1, AF2: possibly thinner (eg 50-100 μm), simple foils.

The to become two originally flat exterior wall foils along the strips S1, S2, S and the (forming during operation) Furrows F in one dimension between the holes of the foil lattice firmly, permanently and consistently tightly connected to it (eg. Glued or welded seam, z. B. 1 mm wide). this happens with one of the outer wall slides on one side after each second row of holes (i.e., for example, line seams, each in the Distance from z. B. 12 mm), with the other outer wall film on the other side of the perforated foil grid at each before free line.

Thereby arise tunnel T between the Foliengitter- and the outer wall film along the seams. These tunnels are now in the transverse direction the holes in the film grid G connected together; it creates a surface channel for the heat exchange medium W (water). In principle, this surface channel in each Be flowed through the direction.

Around However, to realize a cross flow, water is in this Surface channel through the holes perpendicular to the Seam lines flow, the absorbent medium to be cooled (Salt solution), however, outside, and in each case between two seam lines (strip S / furrows F) and parallel to this in the channels K.

The water pressure stabilizes a film stack according to 2 by itself; It is therefore sufficient to clamp the edges in a suitable frame with low mechanical stress.

All Seams should not be continuous to the edge of a foil surface go, but from the outside wall slides must be at all Pages stop one edge. On the one hand, this one can possibly in combination with a thicker foil or a sturdy U-profile frame establish the inflow channels / distribution of the liquid and on the other hand by subsequent welding / gluing on the sides, on which no liquid supply line is necessary, the surface channel on very simple Close tightly.

to Creation of channels K for the absorber medium A is a flat, porous surface membrane FM1, FM2 with each of the two outer wall foils AF1, AF2 along the existing seams (strip S) connected. Indeed After that, a small (eg 1 mm thicker) distance should be used during operation the outer wall foil and the associated surface membrane to be available; therefore, must while connecting suitable spacers are used.

There the saline cycle through the channels K almost should be depressurized, the channel K forming a gap already be founded in the construction and not about by different stretching behavior of the outer wall film and the surface membrane arise.

At the Welding of the films may preferably each all three layers (foil lattice, outer wall foil, surface membrane) be connected at the same time, and the materials have to have the same melting point (eg all polypropylene).

At the Gluing the surface membrane can subsequently However, this will not be flat in a plane be possible because of the above-mentioned necessary Distance between outer wall foil and surface membrane.

Consequently can flow cooling water in the inner flat channel, in the parallel to the air stream lying on it, very thin Channels K the saline solution. The contact surfaces Water-salt solution (dense) and saline-air (microporous) are maximum size.

Of the Membrane absorber is arranged so that the admission of the Channels with the saline solution from above, d. H. in most cases along the air outlet side.

The constriction of the air flow cross section (ie the distance between the basic building blocks in 3 ) can be kept very low, since the width of the already closed at this point water channel sufficient for a channel for transverse distribution of the solution to the individual flat spaces. For this purpose, the final seam of the water channels is made sufficiently wide or double, the porous surface membrane then connected only at the extreme end with the bonded / welded outer wall films.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 0013075 B1 [0004]
• - EP 532368 A2 [0005]
• EP 0952913 B1 [0038]
• - DE 69801982 T2 [0038]

Claims (15)

Device for mass transport between two Fluids (A, L) through a membrane (FM1), in particular membrane absorbers, with the following features: a) Two foils (FM1, AF1) are along of strips (S) which run essentially parallel to one another, stapled together so that between each two strips (S1, S2) a channel (K) for passing through an absorber medium (A) results, which forms the first fluid; b) one of the films is designed as a porous surface membrane (FM1) and thus permeable to the absorber medium to be absorbed masses contained in the second fluid (L), which can be guided past the surface membrane, on the side facing away from the channels (K); c) the second film serves as the first (AF1) of two liquid-tight Outer wall foils (AF1, AF2) of an adjacent heat exchanger plate; d) at operating pressure of a heat exchange medium (W), the between the outer wall films can be introduced forms at least an outer wall foil (AF2) with its outer surface Furrows (F) extending along the strips (S); e) the two outer wall films are connected by coupling elements (Z) connected to each other, which attack the strip (S); Device according to claim 1, characterized the strips (S) are narrower than the grooves (F). Device according to claim 1 or 2, characterized by the following feature: the coupling elements (Z) are designed that the heat exchange medium (W) mainly transverse to the furrows (F) between the outer wall foils (AF1, AF2) can flow past the coupling elements. Device according to claim 3, characterized that the coupling elements (Z) each along the strip (S) are arranged and by a multi-interrupted connection seam formed between the outer wall films (AF1, AF2). Device according to Claim 4, characterized that the connecting seam is formed as a broken weld is. Device according to Claim 4, characterized that the Vebindungsnaht formed as a broken adhesive seam is. Device according to claim 1, 2 or 3, characterized that distance-holding coupling elements (Z) are provided and these each at two adjacent furrows (F) of different outer wall films attack. Device according to claim 7, characterized that the coupling elements (Z) components of a foil grid (G) are alternately at furrow areas of the one (AF1) or the other outer-wall film (AF2) is attached. Device according to claim 8, characterized in that in that the foil grid (G) consists of a perforated foil. Device according to claim 8 or 9, characterized that the foil grid (G) - transverse to the furrows (F) of a Sequence of grooves (F) of an outer wall foil (AF1 or AF2) measured - the same length as that Area of this outer wall film, which is the corresponding Sequence of furrows F has. A film heat exchanger according to claim 9 or 10, characterized in that foil grid (G) is thicker than a Outer wall film. A film heat exchanger according to claim 11, characterized characterized in that the outer wall foils with each other are the same thickness. Device according to one of the preceding claims, characterized in that as the absorber medium (A) a hygroscopic Saline solution is used. Device according to one of the preceding claims, characterized in that as the heat exchange medium (W) Cooling water is used. Device according to one of the preceding claims, characterized in that on both sides of the heat exchanger plate (AF1, AF2, Z) channels (K) for at least one absorber medium (A) are provided, the side of the heat exchanger plate each of a porous surface membrane (FM1, FM2) are limited, which respectively along the strip (S) or Furrows (F) is connected to the heat exchanger plate, each extending on both sides of a strip, adjacent to each other Channels (K) are not necessarily complete sealed against each other.