EP0982427A1 - Cross flow heat exchanger for laundry drier with condenser - Google Patents

Abstract

The heat exchanger has parallel plates (14) with two plate parts (16, 18), each with integrally formed ribs (26) projecting from one side to form transverse cooling air channels (12). Moist or process air flows transverse to the cooling air through parallel channels (10) formed by annular recesses in each plate part. The plate parts are made from metal foil or thermoplastic film with high thermal conductivity and are sealed at the open ends in a holding frame. An independent claim is also included for the production of the plate parts (16, 18). The plastic film complete with ribs (26) is vacuum formed in a single operation. Metal foil is pre-formed with roof-shaped sections between recess-forming parts and the ribs are subsequently created from the roof sections by pushing the foil together until both parts of the roofs contact each other.

Description

The invention relates to a cross-flow heat exchanger for Condensation clothes dryer with the features of the generic term of claim 1.

Such a heat exchanger is known from DE 30 27 900 C2, FIG. 2 and 3, known.

In this construction, they are the air guide bodies forming plates horizontally and spaced one above the other in a cuboid receptacle housing that is tunnel-like trained or on opposite housing faces is open.

These housing openings form the entry and Outlet openings for the warm, moisture-laden and process air to be cooled or dried Condensation dryer. The process air is in the The interior of the housing is guided through guide channels that pass through the Plates as well as the side walls of the receiving housing are defined are.

The plates form flat, rectangular heat sinks the top and bottom of the plate the moisture precipitate and as condensate from the Housing outlet opening can drain.

The plates or heat sinks are two apart overlapping, parallel and flat plate parts Aluminum sheet on only two opposite Edge parts are connected airtight. Analogous to Accordingly, receiving housings point to each other opposite, open foreheads that with corresponding openings in the side walls of the Align the receiving housing.

Through this plate-shaped heat sink is thus transverse to Flow direction of the process air through the necessary cooling air passed through the heat exchanger.

Between the upper and lower plate part of the plates or Heat sinks are their gap bridging, Upright webs, which are in the direction of flow of the cooling air extend and parallel to each other at a lateral distance assigned. These webs form together with the two Plate parts with rectangular channels in cross section.

The webs are made of a meandering ribbed sheet formed, which alternately glued to both plate parts is.

The meandering folded ribbed sheet gives it Connection of its contact points with the two sheet metal parts the plates the necessary rigidity for their handling for cleaning the cross-flow heat exchanger. Create also a surface enlargement to improve the Heat dissipation on the cooling air side.

The connection is made by gluing using a thermally conductive special adhesive.

The explained structure of the plates for air cooling or Dehumidification requires a variety of steps and is accordingly complex.

It is to form the guide channels for the process air also necessary the plates in a special Install the housing. Overall, it is about is thus a technically complex and accordingly expensive construction.

The invention has for its object cross-flow heat exchanger in a in the preamble of claim 1 explained, to provide known training, which is in constructive aspects through special simplicity and a good heat dissipation on the cooling air side.

This object is achieved by the characterizing Features of claim 1 solved.

The construction of a cross-flow heat exchanger according to the invention allows to form the one to be cooled and channels to be dehumidified process air leading to a Disc receiving housing by now the moist air through channels of the air guide body forming plates is passed through and the webs on the upper and lower, flat outside of the plates provided and are each located on an adjacent upper or Support the lower plate. Sheets and webs thus define together extending across the process air channels Cooling air ducts.

The construction according to the invention is distinguished by this an extremely minimal material requirement by the Plate-forming plate parts only from one good thermally conductive metal or thermoplastic existing film are made to which the webs have them molded on immediately during their manufacture.

The webs as well as the molded in the plate parts channel-like depressions for the formation of moist air guidance or Condensate drainage channels give the plate parts a cross ribbing, which despite the low Film thickness gives a high degree of rigidity.

Through the moist air duct, channel-like depressions come through in addition to the the webs formed surface enlargement of the plate parts a further increase in surface area, which the Heat dissipation on the cooling air side or the efficiency of the Cross-flow heat exchanger still significantly favored.

For the manufacture of the heat exchanger according to the invention individual plates only to be stacked one on top of the other Bars, preferably in the middle, in a gap in the bars of the neighboring plate.

The plate pack created in this way is then at the plate contact points the plates welded, glued or pressurized. This can either be along two opposite edge parts or, preferably, on one A large number of points of contact between the plate parts, preferably in a homogeneous distribution over the surfaces of the Plate parts are made. In this last way one becomes better stability of the composite panels achieved.

The webs can either be in the longitudinal direction or Flow direction be formed continuously, which for the formation of a laminar flow as advantageous turns out, or they can be divided lengthways and the Web sections offset to one another transversely to the longitudinal direction be arranged, which is suitable for the formation of a turbulent Flow proves to be advantageous. In the latter case it happens Turbulence and therefore better heat exchange between the flowing medium and the air duct limiting webs and plate parts. Especially in this Case it proves to be advantageous if the film is a Is plastic film and the webs by a corresponding Tooling are formed from the film without the Foil was cut at this point. The web sections then form a rounded, closed peripheral contour.

A plate pack designed for a desired cooling capacity is sealed to the front in a frame fixed.

The dehumidification performance can thus be determined by the number of Set plates, with the number of top and bottom plates Bottom protruding webs should be selected so that an optimal ratio of cooling capacity, depending on the selected surface enlargement, to which by the number of Bridges caused pressure loss in the defined by them Cooling air ducts can be achieved.

The invention makes it possible in a very simple manner powerful cross-flow heat exchanger for different Interpret services without costly interventions in their basic constructive concept to be forced.

It is therefore possible to have an inexpensive Formation of variants both different manufacturers of Condenser tumble dryers to use as well To achieve differentiation within a series of devices.

The invention thus offers a sophisticated, Complete construction system for cross-flow heat exchangers, which for existing device generations are compatible.

Accordingly, both design, testing and monitoring all technical values from the manufacturer of such Heat exchanger can be made yourself.

Various are suitable for producing the plate parts Materials, whereby the use of foil offers the advantage not exclusively on materials with good thermal conductivity to have to fall back.

For example, it is possible to use thermoformed foils To use plastic, where to manufacture the Plate parts with preference to acrylonitrile-butadiene-styrene copolymers (ABS) or polypropylene. This has to be achieved necessary cooling capacities or the necessary Thermal conductivity and stability a film thickness between 0.15 mm and 0.50 mm, preferably 0.3 mm as advantageous proven.

Although such plastics are thermally insulators act, is, compared to materials with good Thermal conductivity, due to its use as a film, just accept a performance loss of 3 - 8%. However, this is compensated for by the fact that the Plastic film is thermoformable and the plate parts accordingly inexpensive and with any Have the surface enlarged.

Recommended as another material to be used with advantage aluminum foil with a thickness of also preferably 0.15 mm to 0.20 mm.

For the production of plate parts from foils from the specified A method with the following is recommended for materials Process steps:

For the production of plate parts from thermoplastic films it is advisable to use the vacuum thermoforming process. The film to be processed is preheated and in one tool into the desired shape in one go. The webs formed transversely to the channel-like depressions are made by thin metal strips inserted into the tool formed, which engage sword-like in the film. Here it proves to be advantageous if the metal strips Do not cut the film, but only deep-draw it. As This proves to be particularly advantageous if the webs are not continuous in the longitudinal direction but divided and preferably offset from one another transversely to the longitudinal direction are arranged, since then the flowing medium is not on Cut surfaces but the web sections a have rounded, closed leading edge.

For the production of plate parts from metal foil in groove-like depressions are formed in a process step. Between recess sections of this gutter-like The film is indented transversely to its longitudinal direction Preformed like a gable roof. Finally the film becomes Web formation in the longitudinal direction of the recess sections pushed together so that the recess sections for the formation of continuous channel-like depressions touch the front and the two halves of the Foil sections shaped like a gable roof for web formation abut each other. The web thickness results from two Material thickness and thus minimizes the pressure loss on the Cooling air side.

It should be mentioned that cross-flow heat exchanger are known, in which, analogously to the invention Construction that passes cooling air between bars is between and across to damp or Process air channels extend. This damp or Process air channels are in this case folded from Al blanks Box tubes formed while the webs to form the Cooling air ducts made of meandering folded aluminum fins are made between the levels of box pipes are introduced or glued.

So for the two types of intersecting channels various, to be manufactured and assembled Components provided.

Such cross flow heat exchangers are manufactured by AKG Thermotechnik GmbH & Co. KG manufactured in 34369 Hofgeismar and distributed.

Figur 1

einen Längsschnitt eines Kreuzstrom-Wärmetauschers entlang der Linie B-B der Figur 2,

Figur 2

einen Querschnitt des Kreuzstrom-Wärmetauschers entlang der Linie A-A der Figur 1 ,

Figur 3

einen durch einen strichpunktierten Kreis angedeuteten Ausschnitt der Darstellung gemäß Figur 1, in stark vergrößertem und verkürztem Maßstab,

Figur 4

eine schaubildliche Darstellung des Plattenpakets des Kreuzstrom-Wärmetauschers gemäß Figur 1 und 2,

Figur 5

einen Teillängsschnitt durch ein vorgeformtes Plattenteil aus Aluminiumfolie,

Figur 6

eine Darstellung des Plattenteils gemäß Figur 5 in zusammengeschobenem Zustand.

Figur 7

eine schematische Schnittansicht der zueinander versetzten Anordnung von Stegteilstücken.

In the drawing, a possible embodiment of the invention is shown. Show it:

Figure 1

2 shows a longitudinal section of a cross-flow heat exchanger along the line BB in FIG. 2,

Figure 2

3 shows a cross section of the cross-flow heat exchanger along the line AA in FIG. 1,

Figure 3

2 shows a section of the illustration according to FIG. 1, indicated by a dash-dotted circle, on a greatly enlarged and shortened scale,

Figure 4

2 shows a diagrammatic representation of the plate pack of the cross-flow heat exchanger according to FIGS. 1 and 2,

Figure 5

a partial longitudinal section through a preformed plate part made of aluminum foil,

Figure 6

a representation of the plate part according to Figure 5 in the pushed together state.

Figure 7

is a schematic sectional view of the staggered arrangement of web sections.

The cross-flow heat exchanger shown has, for example five horizontal levels of humid air flowing through, in Cross section preferably approximately cylindrical Process air channels 10, which are at a radial distance from each other run parallel and preferably from level to level Gap are offset. Across the process air channels 10 and parallel to their levels extend in a total of six Levels in cross section of rectangular cooling air ducts 12.

Both types of channels 10 and 12 are through one above the other stacked, preferably rectangular plates 14 formed, which in turn each consist of two identical shapes and plate parts 16 and 18 symmetrically assigned to one another are made (see Figs. 3 and 4).

In the present case, these plate parts 16, 18 in one piece from a film of thermoplastic material, preferably polypropylene. You may as well in one piece from a foil made of heat-conducting metal, preferably aluminum.

Each plate member 18 is along its two opposite longitudinal edge pieces 20 and 22 with such 20 'and 22' designated the one symmetrically assigned to them Plate part 16 preferably by gluing, welding, Pressure joining or folding tightly connected.

To form the guide channels 10 for the moist air each plate part 16 or 18 with molded to each other parallel, groove-like depressions 24 equipped. For Formation of the cooling air channels 12 are on the plate parts 16, 18 transversely to the recesses 24 or their airtight interconnected longitudinal edge parts 20, 22 extending perpendicularly projecting and mutually parallel webs 26 molded.

Each plate 14 is thus characterized by upper and lower, in webs 26 lying in a common vertical plane. Recesses 24 and webs 26 give the thin Plastic films of preferably only 0.20 mm to 0.40 mm Thickness a stiffness that ensures that in mutual solid bond of stacked plates 14 according to Figure 1 is a stiffened unit is achieved.

3, the webs 26 of a plate 14 for forming the cooling air channels 12 engage between two webs 26 of a plate 14 located below or above them, preferably in such a way that adjacent webs 26 touch one another (1st variant ) . However, it is also conceivable for the webs 26 of two plates 14, as indicated by dash-dotted lines, to engage in the middle between those of the other plate 16, as a result of which the number of cooling air ducts 12 can be doubled and the efficiency of the heat exchanger increases (second variant) .

The plates 14 of the plate pack are at their ends together in a known manner each in a plastic existing holding frame 28 and 30 kept sealed what by means of an adhesive 32, preferably made of cast resin, is accomplished.

The webs 26 of the upper and lower plates 14 are for Formation of the outside of the heat exchanger Cooling air channels 12 each through a circuit board 32 or 34 covered, which is also at the end in the holding frame 28, 30 are set.

The cross-flow heat exchanger thus formed thus has itself none to form the channels 10 for the condensate drain required housing on. It is in one unit Housing opening of a condensation dryer insertable, for its handling on its front A handle 38 is provided on the end face.

A method of manufacturing the plate parts 18 Metal foil is illustrated in Figures 5 and 6.

In an aluminum foil 40 in the longitudinal direction forming guide channels 10 channel-like for the moist air Recess sections 42 and transverse to their longitudinal extent gable roof sections 44, 46 are formed. To do this continuous trough-shaped depressions and across and in same direction of formation gable roof-like sections molded. Finally, the film 40 in Extension direction of the groove-like recess sections 42 pushed together so that they face each other touch and the two halves of the gable roof molded sections 44, 46 for forming the webs 26 in are essentially close to each other.

For manufacturing the plate parts from plastic film, for example polypropylene in a preferred thickness of approx. 0.20 mm, vacuum thermoforming can be used become. The film is preheated and in a tool preferably in a single move to the desired shape drawn. The aforementioned process step of Pushing them together is then not necessary. By doing Tools are fins or sword-like metal strips used, which the webs 26 shown in the figures shape.

As can be seen from Figure 7, according to another Embodiment divided the web sections 50 in the longitudinal direction and offset from one another transversely to their longitudinal direction arranged. The fin or sword-like metal strips do not cut through the plastic film, it will quasi deep-drawn. In this way, one in Circumferential direction closed circumferential contour of the web sections 50 and a rounded leading edge 52 is reached.

Claims (13)

Cross-flow heat exchanger for condensation tumble dryers, with a multiplicity of substantially horizontally arranged, mutually assigned plates which are arranged parallel to one another perpendicularly to the plate plane and which are each formed by two plate parts (16, 18) arranged parallel to one another and along two opposite edge parts (20, 22 or 20 ', 22') are connected to one another in an airtight manner and thus form a flat air guide body which is open at opposite ends, one of the plate parts (16 or 18) on one of its flat sides having a multiplicity of on the Carries molded-on webs (26) which are arranged at a distance parallel to one another, which protrude vertically from the flat side and which, together with a plate part (16 or 18) supported on the webs (26), form air guide channels (12) for the cooling air , characterized in that the plates (14) of moist or process air are flowed through, the two plate parts (16, 18) of which are made of a good heat-conducting metal or thermoplastic film (40) that the plates (14) at their open ends in a holding frame (28 or 30) are fixed in a sealed manner that the webs (26) extend from the outer flat side of each plate part (16 or 18) of a plate (14), transversely to their edge parts (20, 22 or 20 ', 22') which are connected to one another in an airtight manner, protrude and are formed by molding and are supported together on a plate part (16 or 18) of an adjacent plate (14) and that the plates (14) each have a plurality of mutually parallel process air channels (10) extending in the flow direction of the moist air which are formed by groove-like depressions (24) formed symmetrically in their plate parts (16, 18). Cross-flow heat exchanger according to claim 1, characterized characterized in that the film (40) for producing the Plate parts (16, 18) with an aluminum foil Thickness between 0.14 mm to 0.20 mm, preferably 0.15 mm, is. Cross-flow heat exchanger according to claim 2, characterized characterized in that the Al foil (40) existing and along two opposite Edge parts (20, 22 or 20 ', 22') with each other hermetically connected plate parts (16, 18) of Plates (14) glued, folded or mutually are pressurized. Cross-flow heat exchanger according to claim 1, characterized characterized in that the plastic film (40) for Manufacture of the plate parts (16, 18) thermoplastic, such as acrylonitrile-buthadiene-styrene copolymers (ABS) or polypropylene, exists and has a thickness between 0.15 and 0.50 mm, preferably has 0.3 mm. Cross-flow heat exchanger according to claim 4, characterized characterized in that the thermoplastic Plastic film (40) existing plate parts (16, 18) for Formation of a plate (14) on opposite Edge parts (20, 22 or 20 ', 22') by welding, gluing or printing are connected. Cross-flow heat exchanger according to one of the preceding Claims, characterized in that the Plate parts (16, 18) on a variety of Support points, preferably over the whole Plate surface distributed by welding, gluing, Pressure joining are connected. Cross-flow heat exchanger according to one of the preceding Claims, characterized in that the webs (26) continuously formed in its longitudinal direction are. Cross-flow heat exchanger according to one of the preceding Claims 1-6, characterized in that the Divided webs (26) in their longitudinal direction and the Web sections (50) transverse to their longitudinal direction are offset from one another. Cross-flow heat exchanger according to claim 8, characterized characterized that the film is a plastic film and the webs (26) from the plastic film are shaped without them at this point was severed so that the webs (26) in Are closed circumferentially. Process for the production of plate parts (16, 18) to form a cross-flow heat exchanger according to Claims 2 and 4, characterized in that in the foils (40) are spaced one behind the other Depression sections (42) of the channel-like Wells (24) are formed and that the Foil (40) between the recess sections (42) transverse to their longitudinal direction for web formation is formed. A method according to claim 10, characterized in that a plastic film (40) is preheated and in a tool is vacuum-thermoformed. A method according to claim 11, characterized in that the process in one Forming process is carried out. A method according to claim 10, characterized in that when processing metal foil (40) this between the recess sections (42) transverse to their Longitudinal direction and in their molding direction is preformed like a gable roof and that finally Foil (40) for web formation in the longitudinal direction of the Depression sections (42) are pushed together in such a way that the recessed sections (42) face touch and the two halves of the gable roof molded sections (44, 46) close to the web formation lie together or lie against each other.

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