WO2006034666A1 - Microchannel recuperator produced from stacked films - Google Patents

Abstract

The aim of the invention is to provide highly effective microchannel heat exchangers which can be produced at low cost. According to the invention, flat stacked thin layers of film are arranged in such a way that free areas in the stack of film (20) in the arrangement thereof result in two separate microchannel systems. The invention also relates to the use of a perforated or slotted film (21, 22, 23, 24) or strips of film in order to produce a stack of film (20) for a microchannel heat exchanger. The invention further relates to a microchannel heat exchanger.

Description

 MICROCANAL RΞKUPERATOR PRODUCED FROM STACKED FOILS

The invention relates to a recuperator, a micro-channel recuperator, the use of a film, a slotted or perforated film and a method for producing a recuperator and a method for operating the same.

[02] In heat exchangers, the heat transfer takes place by means of solid partitions from the heat releasing medium, usually fluids, which absorb heat. Due to the variety of applicability is in the group of heat exchangers a great importance to the so-called compact heat exchangers. In order to optimize the flow of heat energy despite the compact design, great efforts are being made, especially in compact heat exchangers, to maximize the ratio of heat transferring exchange surface area to volume of the heat exchanger. As part of this effort, the so-called micro-channel heat exchangers were developed.

[03] Heat exchangers with microchannel structures use microfluidic components for the channel structure for guiding the fluids between which the heat is to be exchanged. Often, heat exchangers with microchannel structures are also very small in their absolute size.

[04] Heat exchangers of this type achieve a high heat transfer coefficient with laminar flow. Since they should be able to flow through with the least possible resistance, such heat exchangers usually have a large number of channels, so that the channel guidance results in a rather complex, complicated system. In addition, the production of microstructures makes high demands on production technology. Using a variety of methods such as etching, laser machining, machining and forming, the microstructures are fabricated to safely accommodate low or high operating pressures. Partly results in increased Bearbeitungs¬ difficulties by certain materials, which are required by the requirements of the fluid to be carried and the intended operating parameters.

[05] Microchannel heat exchangers are, for example, by Ehrhard and Meisel (P. Erhard, I. Meisel: "Flow and Transport Problems in Micro Channels", News-Forschungszentrum Karlsruhe Jahrg. 34 2-3 / 2002 P. 137/142) and of Pua and Rumbold (Lee M. Pua, SO Rumbold: "Industrial Microchannel Devices- Where Are We Today?", Abstract, First International Conference on Micro- phones and Minichannels April 24-25, 2003, Rochester, NY, USA; ICMM2003-1101) been discussed. Known microstructure heat exchangers are generally constructed from a stack of alternating layers of metal sheets with channel structures. The heat exchange takes place between the two guided fluids through a separation membrane from a layer with channel structure to the underlying and overlying layer. In this case, channel structures for more than two fluids are possible. The channels of the respective structural surface are geometrically arranged so that they can be combined in common connections.

[07] An exemplary heat exchanger with stacked sheets is shown in US 5,193,611.

[08] The channel guidance and the channel geometry are based on the criterion that, in a compact design, optimum material utilization and at the same time uniform flowability of the structure should be ensured. In addition, if possible by the channel guide and the choice of connections variable applications are given, which are also known from macrostructure heat exchangers, ie in particular an operation as a DC, countercurrent and Kreuz¬ current heat exchanger.

[09] The present invention has for its object to provide a very effective heat exchanger available.

[10] This object is achieved by a microchannel recuperator for exchanging heat between two fluids, which has sheet layers with free spaces in the film stack which are stacked in a planar manner, the free spaces in their arrangement providing two separate microchannel systems.

[11] It should be explained conceptually that a film differs from a metal sheet in particular by its thickness. Self-supporting, flexible structures with a thickness of up to about 1 mm are referred to as films. The films to be used according to the present invention should be within this range, but in particular in the range between 2 microns and 500 microns, especially between 2 microns and 300 microns. Metal foils can be obtained, for example, by rolling processes, while plastic foils are preferably obtained by cutting, stamping, etching, casting, calendering or extruding. Even with composite films, the invention can be realized. These are usually produced by gluing, welding or metallizing in a high vacuum.

[12] The invention breaks with the erroneous idea that films can not be suitable for producing pressure-resistant and economically producible microchannel structures. It shows that by appropriate placement of the films by means of slots and / or holes in the films suitable currents can be achieved. [13] By using thin foils, the recuperator according to the present invention can be produced in comparison with hitherto known microchannel heat exchangers with considerably more economical production processes. It can also be used for the heat exchange of fluids in the very low to very high temperature range as well as at low pressure and high pressure. In addition, the recuperator can be operated with an almost arbitrarily large pressure gradient between the two fluids, even at very high pressure differences above 1000 bar, which is very surprising given the low inherent strength of a film. In addition, the invention is suitable for liquids, vapors and gases.

It should be noted that the proposed recuperator not only allows the heat exchange between the same media, but that the same and / or other media flow within the micro-channel systems and can exchange their heat energy with each other. Furthermore, it should be emphasized that the proposed recuperator is not limited to two microchannel systems, but that several microchannel systems can also be arranged in it without any problem, it being understood that more than two similar and / or different fluids in the microchannel Systems are guided along each other without unwanted mixing, wherein the channel geometries can be unequal, so for example adapted to the media. It is also readily possible to drive the proposed recuperator in direct current, in countercurrent or locally varying, partly in direct current and partly in countercurrent.

[15] The free spaces in the film stack are formed by recesses in the film layers. The recesses may be produced, for example, in that a film layer has a continuous sheet with slots. In this case, the distances between the strips form the recesses of the film layers, so that practically identical geometries can be produced in the channel system. In addition to and alternatively to elongated slot-shaped recesses or to slot-shaped spacings of film strips, holes of various types may be used, for example round or angular holes.

[16] In the following, the invention will first be presented in more detail in its embodiment with slotted films or film strips. It should be noted that almost all advantages of the invention can be achieved equally both with separate film strips and with slotted continuous films, even if inventive features are described in part only by means of an embodiment variant.

[17] It is preferable that slits in the film layers are extended in a longitudinal direction of the recuperator and / or the respective film layers. In this way, longer channel structures can be achieved. than at an extension of the slots in a direction transverse to the main direction of extension. Due to the usually desired compact construction of a microchannel recuperator, the longitudinal direction of all stacked films will generally be the same and, moreover, coincide with a longitudinal direction of the entire recuperator.

[18] The film layers are particularly suitable for use in the context of the present invention if they each have a plurality of longitudinally extending slots and webs lying between the slots, the webs being wider than the slots. Such a geometry opens up manifold possibilities for guiding the fluids to be conveyed through the recuperator in the longest possible straight flow paths.

[19] In particular, the individual foil layers may have a lateral offset perpendicular to the longitudinal extension direction of the slits lying generally parallel to their mutually parallel adjacent foil layers. In this case, the slots of the film layers can each be covered by webs of the adjacent film layers. If the lands are wider than the slots, the slots are completely covered. Since an offset of the adjacent foil layers is sufficient for this purpose, identically designed foils can be used for each foil layer, which makes the production very cost-effective.

The slot geometry of each individual film layer can be kept simple, preferably by a plurality of slots which are parallel to each other, are the same length and have an equal width over their entire length.

[21] However, films of the same design can not only be positioned with an overall offset such that the slits of each film layer are formed into channels by offsetting the adjacent film layers and thereby covering the slits. Rather, it is also possible to specifically shape the individual foils so that overlap of the slots results in a mirror-inverted placement of the respectively adjacent foil layers, thus forming the desired microchannels. Exactly the same shape films can therefore be simply stacked so that when you create the stack for every other layer, the film is turned over and then placed only.

[22] In a formal geometrical description, this possibility is given when in a film layer along at least almost every distance transversely to the longitudinal direction of the slits the condition satisfies, that at each point on the track, which a first distance to a first edge of the film layer and which lies in a slot of the film layer, a second point results, which has a magnitude matching the first distance second distance to the second edge of the film layer, but on a web between the slots or between an edge slot and the edge of the film layer is located. More simply, each slot of a first film layer must be assigned a web which covers it when the adjacent film layer has an at least substantially identical slot geometry and is placed on the first film layer in an inverted manner.

[23] It is particularly preferred if on each slot of a film layer in the film stack a web of an adjacent film layer comes to rest in the middle. It does not necessarily have a uniform geometry of the film layer. If slots and webs overlap in the middle, the heat is distributed particularly homogeneously in the recuperator while it is being operated.

In the context of the invention it has been found that a particularly effective heat exchange statt¬ finds if by alternately superimposing narrow slits and wider webs within the film stack along an overlap width of the webs of adjacent film layers durchgehen¬ de massive walls in the material build, from which in the cross section of the film stack which do not cover with adjacent layers areas of the webs laterally project as micro ribs.

[25] Again, it was found that the heat flows are very homogeneous when the thickness of these running through the film stack pile walls everywhere is at least substantially the same. If uniform slits and webs are stacked over their longitudinal direction in the width and the slots and webs of the respectively adjacent film layers are centered over one another, the wall thickness in the entire film stack is half the difference between the width of the slits and the width of the slits Stege.

[26] It is readily apparent that the individual film layers are best produced in the same geometry. In order to obtain microchannels each having a thickness of a film layer, it is necessary to either stack the films with an offset or - if a flush finish is to be achieved at the edge of the film stack - each hang mirror-inverted to each other. The mirror-inverted placement can be effected by alternately using two production stacks lying in a mirror-inverted manner in the production of a film stack according to the invention. Alternatively, one-second of a make stack of films may be flipped over before being laid up. Depending on the given boundary conditions, a very economical production can also be achieved in that the foil layers have two different geometries, which in particular can each come to rest alternately in the stack.

Regardless of the above, it is proposed that a respective second film layer has a passage between slots of the adjacent first and adjacent third film layers, while these slots are otherwise separated by a web in the second film layer. The bushing may preferably connect at the end of the slots of the first and third film layers. By providing a feedthrough within the film stack between the slots of different film layers which serve as microchannels, which are otherwise separated, there is no need for a cumbersome routing at the edge of the film stack. In this way, the proposed recuperator in turn builds very cost-effective and compact. The feed is used in a simple manner for distributing the fluid within the microchannel system.

[28] A bushing can advantageously be designed tubular and extend through a plurality of film layers, in particular through all the film layers stacked one above the other. In this way, within the implementation, the hydrodynamic energy loss is minimal. In addition, the microchannels branching off from the bushing are supplied uniformly with the fluid of the respective duct system. A tubular implementation is obtained when the individual films have overlapping holes. These can take any forms. For example, a cylindrical tube-shaped leadthrough results if circular holes are arranged one above the other in the foils so that the holes lie exactly one above the other. With a uniform slight misalignment would result in a tube shape in the form of a crooked cylinder. In the case of rectangular or square holes, accordingly, a rectangular or square tubular passage is obtained. It goes without saying that any other hole shape can also be used, whereby this has only an effect on the resulting cross section of the bushing.

[29] In order to feed the microchannel recuperator with at least two fluids and to discharge them after the heat exchange, it is proposed that the recuperator has a collecting feed and a collecting discharge for each fluid and thus for each microchannel system. These are preferred to all

Microchannel slots of the film layers connected in columns perpendicular to the film planes, each one column is associated with a channel system. The first channel system thus comprises all superimposed microchannels of a first, third, etc. column, whereas the second channel system comprises all the superposed microchannels of the second, fourth, etc.

Column.

[30] At the same time, the two microchannel systems are preferably connected alternately to the individual film layers.

[31] This geometry of the microchannel systems is a clear break with previously known heat exchangers. Although these two fluids are also fed alternately into the layers of sheet stacks. However, the layers are separated by membranes, so along a rectangular Ters in cross-section through the stack of sheets, the two channel systems everywhere have one another alternating channels. In a column superimposed channels thus belong alternately to ers¬ th and the second channel system. In the proposed recuperator this is not the case, since the individual layers with microchannels are not separated by membrane-like components without further function, but by each of the next layer, which in turn also has microchannels, only that they are arranged offset.

[32] In one recuperator according to the present invention, according to one of its aspects, the channels of the Mirokanal structures are arranged diagonally to each other. As a result, there is a heat flow between the respective closest channels of the two separate microchannel structures in two directions, which lead obliquely from each microchannel of a second film layer to the four offset parallel microchannels of the adjacent first and the adjacent third film layer. In contrast, in conventional heat exchangers, the nearest adjacent microchannels are arranged in the grid over a cross section through the film stack just above and exactly below each microchannel of each second film layer. In this respect, in conventional heat exchangers each microchannel only has two nearest microchannels of the other microchannel system.

[33] This collection feed and the collection discharge are preferably connected to cover plates or cover plates on different sides of the film stack in such a way that they permit a crossing-free recycling of the two fluids.

[34] If the individual film layers are perforated instead of or in addition to slots, it is proposed that the holes in each film layer be arranged in a grid so that a first group of webs extending between the holes extends on each film layer and a second set of webs arranged perpendicularly to the first group, and that the film layers are stacked with an offset of the holes, so that between two holes of a first and a third layer, which lie one above the other, a web lies in the second film layer which still leaves a passage between the holes of the first and the third layer. In such an arrangement, each hole is connected to two holes arranged congruently, the two film layers are above or two film layers below. In between are two webs, namely one web of the film layer directly above or the film layer directly below. At the same time adjacent holes of a film layer are connected in the offset direction, since they both have access to a hole in the overlying and the underlying film layer. Thus, a flow channel results along the offset direction of the holes, and a meandering streamline is created as the fluids flow through the separate microchannel systems along that direction. Here, too, a heat distribution can be observed particularly homogeneous if the webs of the first pair of webs of a film layer are arranged centrally on the holes of the adjacent film layer.

[36] While one pair of webs is to be placed between the holes of the respectively adjacent film layers as flow-deflecting surfaces in the proposed offset stacking, it is proposed that the webs of the second web section be stacked between adjacent film layers. In this way, the entirety of the webs of the second pair of webs stacked on top of each other in a covering manner results in a family of massive material walls within the present stack, comparable to that solid material wall which was described by the overlapping areas when piled-up slotted films were stacked. The webs of the first set of ridges are laterally from the flock of walls - which consists of the adjacent webs of the second set of ridges - and verbin¬ the individual parallel walls of the flock of mountains. In this respect, a solid material wall created by covering stacking or a group of material walls, which passes through the entire film stack, also results here, each wall having laterally projecting ribs which protrude into the different microchannel systems. The heat exchange can thus take place via the ribs and across the wall during operation of the proposed recuperator.

[37] Both in the proposed variants with slots and in the embodiment with holes are preferably with respect to the stacking direction superimposed clearances - also known as columns - connected to a channel system. By virtue of this arrangement, the microchannel structure is largely independent of any pressure differences between the fluids: whereas in conventional heat exchangers, a thin membrane lies between the two fluids, so that the pressure difference between the two fluids acts between their top and bottom surfaces plate-like ribs according to one aspect of the present invention between channels of the same channel system. So no pressure difference acts on them. The pressure difference acts only laterally within the foil stack, ie between the sides of the solid walls.

[38] The invention will be further explained below with reference to three exemplary embodiments with reference to the drawing. Show here:

1 shows a schematic plan view of a film with slots and feedthroughs,

FIG. 2 is a schematic perspective view of a stack of films according to FIG. 1, the film stack being cut approximately at the height of the marking II-II in FIG. 3 shows a schematic perspective view of a heat exchanger with the Folien¬ stack of Figure 2 as a central component, wherein the film stack of Figure 2 is approximately along the marking III-III cut,

FIG. 4 shows a schematic perspective view of a film stack comparable to the view in FIG. 2, in which film strips are used instead of slotted foils,

FIG. 5 is a schematic plan view of an alternative film for constructing a film stack for a micro-ribbed recuperator and FIG

FIG. 6 shows a foil stack of foils according to FIG. 5 in a perspective view according to the viewing direction and sectional marking VI-VI in FIG. 5.

[39] The film 1 in Figure 1 has a substantially rectangular, elongated shape. In her four slots 2 are provided, which are arranged parallel to each other and to a longitudinal axis of the film 1. In addition, two holes 4 (numbered as an example) are introduced into the film 1 next to each slot at the two slot ends.

[40] Between two slots 2 is in each case a web 5, which is transverse to the longitudinal axis 3 wider than the slots. 2

[41] The slots 2 of the film 1 can be introduced into the film 1, for example, by punching, lasering, etching or other production methods. The same applies to the holes 4. Depending on the gewünsch¬ th geometry of the channel systems in the heat exchanger, both the slots 2 and the webs 5 vary in width, in a heat exchanger according to the embodiment presented here, however, the width of the slots 2 as well the width of the webs 5 over the entire length of the film 1 to be constant. Furthermore, the webs 5 should be wider than the slots. 2

[42] The slots 2 and thus also the webs 5 are arranged on the film 1 outwardly. Specifically, the four slots 2 are offset from a theoretically possible central position in a transverse direction 6. The offset is chosen so that when placing a second film (see Figure 2) on the film 1, each slot 2 in the film 1 is covered with a web, if the aufzulegende second film is identical to the film 1, but with respect to the longitudinal axis is mirrored.

[43] The desired complete coverage of each slot 2 with a web of the overlying film is enforced by the geometry, as along a transverse distance 7 to each point (exemplary numbered 8, 9, 10), which is located within a slot 2, a counter point 8 ', 9', 10 'exists, the be¬ tragsmäßig a same distance from a first edge 11 and to a second edge 12 of the film first has and is located on a bridge 5. The distance between the edge of the special slot 13 and the longitudinal axis 3 is set exactly so that the distance from the edge of the special slot 14 to the longitudinal axis 3 amounts to the width of a slot 2 plus twice the distance of the edge of the special slot 13 to the longitudinal axis 3. As a result, when a mirror-inverted ange¬ arranged, ie, for example, compared to the film 1 twisted, the second slide, the slots of each slide exactly centered under the webs of the other film to lie.

[44] If several foils 1 according to FIG. 1 are superimposed congruently in alternating orientations, the foil stack 20 in FIG. 2 results. Four foils 21, 22, 23, 24 lie one above the other there. It should be noted that the films 21, 22, 23, 24 of the film stack 20 are not completely shown in Figure 2, but the film stack 20 is cut approximately in accordance with the marking II-II in Figure 1. As had to be apparent from the geometry of the films 21, 22, 23, 24 (identical to film 1), each slot (exemplarily numbered 25) is exactly centered exactly with two webs (exemplarily numbered 26, 27) covered.

[45] Since the lands 26, 27 are wider than the slots 25, there is an overlap area (exemplified by 28) in which the lands of each layer 21, 22, 23, 24 are uniform throughout the height of the film stack 20 overlap massively. In this respect, 28 massive walls within the Überblappungsbe¬ arise over the total height of the film stack 20, which extend parallel to each other along the edges of the slots 25 over its entire length.

In addition, the layers of films 21, 22, 23, 24 with the slots 25 completely overlapped or underlaid result in channels 29 in each film layer 21, 22, 23, 24. The channels 29 are laterally separated from each other by the walls 28 separated and lie with respect to each wall 28 over the height alternately. Along the special wall 30 is a first microchannel 31 on the first side. Next, on the opposite side, there is the special channel 32 at the height of the wall 30. Next, the special channel 33 follows obliquely offset. Finally, in turn, diagonally offset to the other side, the special channel 34 is found on the opposite side.

[47] The exact shape of the channels 29 is determined by the thickness of the films 21, 22, 23, 24 and by the width of the slots 25. The width of the walls 28, 30 is determined by the width of the webs and slots: it is half the difference between web and slot width. [48] Due to the geometry of the stacked foils 21, 22, 23, 24, a hole (exemplarily marked 36) of the respectively adjacent foil comes to rest on each end of the channel (exemplarily identified by 35). This results in tube-like channels (not shown in their course), which pass through the film stack over its entire height perpendicular to the film layers 21, 22, 23, 24. These tube-like channels each allow a connection between the superimposed slots of the respective second film layers 21, 23 and 22, 24. In this way, fluid, which runs in the tube-like channels perpendicular through the film stack 20, reach the microchannels 29 in every other film layer ,

With the stacking of the slotted foils 21, 22, 23, 24 to the present stack 20 creates a heat exchanger structure in which the respective superimposed microchannels 29 form columns in the senk¬ right level of the stack 20 by walls 28, 30 from each other are separated.

For operation as a heat exchanger, the film stack 20 is used as follows: The film stack 20 is covered on its top 40 and on its bottom 41 with cover plates 42, 43. The rohrähn¬ union channels 44, 45 in the film stack 20 are connected by bores 46, 47 in the cover plates 42, 43 with Sammelzufuhrrohren and Sammelabfuhrrohren 48, 49, 50, 51. In this case, a first group 44 of tube-like channels is connected to the collecting feed 48 and the collecting discharge 49, while the second group 45 of the tube-like channels is connected to the collecting feed 50 and the Samnielabfuhr 51. When used as a countercurrent heat exchanger, a first fluid 52 (represented by a flow direction arrow) is supplied through the collection feed 48 to the microchannel heat exchanger. Via the bores 46, the first fluid 52 is distributed into the first family 45 of the tube-like channels and from there into the numerous microchannels which pass through the film stack 20 along the respective slot length to the other side. On the opposite side, the first fluid 52 is collected again by the tube-like channels (not shown) present there and fed to the collecting discharge 49.

[51] Simultaneously, a second fluid 53 passes through the heat exchanger 54 in the opposite direction: it flows through the collection supply 50 (collecting supply pipe on the back of the heat exchanger 54, not shown) via local tube-like channels (not shown) in the horizontal microchannels, passes through them towards the front of the heat exchanger 54, there is collected in the first group of rohrähnli¬ chen channels 54 and the collection discharge 51 is supplied. With this arrangement of the leads and leads, the collection of fluids flowing through the microchannels takes place without intersection of the fluids. The heat exchange takes place as follows: The first fluid 52 is fed through a separate microchannel system to every other microchannel column and flows through all microchannels of these columns in full length. The second fluid 53 is supplied on the opposite side of the heat exchanger 54 to every other second microchannel column and flows through the heat exchanger 54 in the opposite direction. The two flowing fluids 52, 53 are thus in completely separate channel systems, wherein the microchannels and the tube-like channels 44, 45 are each separated by solid walls (designated 55 by way of example). By alternately arranged on both sides of the walls 55 over the height thereof, laterally projecting webs of the individual film layers of the film stack 40 results in a two-sided structure of micro ribs on the walls 55. Through the walls 55 with the double-sided micro rib structure of the heat exchange between the two fluids 52, 53, wherein the micro-ribs have large-area contact with the flowing fluids 52, 53.

[53] The film stack 20 'in FIG. 4 uses individual strip-shaped films 21a, 21b, 21c, 2Id to form webs of a film layer (exemplarily numbered 21', 24 '). or 24a, 24b, 24c, 24d. The slots are thus formed by the distance between the individual film strips. Otherwise, the use of foil strips leads to no structural differences compared to the slotted foils 21, 22, 23, 24.

[54] The alternative film 70 in FIG. 5 is perforated in a grid. Holes (exemplified gekenn¬ with 71, 72) are arranged in a longitudinal direction 73 and a transverse axis 74 parallel rows. The perforations are almost square in the embodiment shown. It should be understood that they may also take many other forms, for example, they may be circular or rectangular.

[55] Between the perforations 71, 72 extend on the film 70 longitudinal webs (exemplified gekennzeich¬ net with 75) and transverse webs (exemplified by 76). The perforations 71, 72 and webs 75, 76 are arranged on the film 70 according to the geometry already described with reference to a slotted film so that upon rotation of the film 70 by 180 ° about its transverse axis 74 and when placed on a non-rotated film the Transverse webs 76 of the overlying film cover the square holes 72 of darun¬ ter lying film exactly in the middle. However, the width of the transverse webs 76-measured along the longitudinal direction 73 of the film 70 -is shorter than the width of the holes 72-also measured-so free perforations remain at both ends 77, 78 of the perforations 71, 72 covered by the transverse webs 76 79 exist (see in particular on the film stack 80 in Figure 6). [56] When the film stack 80 in FIG. 6 is filled with fluids, they can thus flow meandering in the direction of the longitudinal webs 75 and in the vertical direction 81 through the film stack 80. The transverse webs (identified by 90 by way of example) of adjacent film layers form large areas in each perforation 71, 72 in order to conduct heat from a fluid or to conduct heat into the fluid. End faces 77, 78 of the perforations 71, 72 and the transverse webs 76 are flown in the vertical direction 81 normal and in the longitudinal direction frontally and serve as additional heat exchange surfaces and Verwwirer.

In the case of such a layering of the perforated foils 70, channel shafts (identified by way of example by 82) which extend in each case over the entire length and the entire height 81 of the foil stack 80 are formed. The longitudinal webs 75 form by the layering of the individual films 70 Trennwän¬ de 83 with double-sided structure of micro-ribs (exemplified by 84, 85 on the spielsweise wall 86) on the heat exchange between the meandering in the direction 87 of Kanal¬ wells 82nd flowing fluids, wherein the flow of fluids can also take place over several Folien¬, since along the vertical direction 81, the meandering elongate channels are also connected. Due to the layering of the perforated foils, provision is also made over the entire height 81 of the foil stack 80 when providing longer rectangular perforations 88. Through this passage, a fluid in each foil plane has a low-flow access to the corresponding channel shaft. The individual manholes, that is to say the individual microchannels, each with a meandering course guide, thus have connections at their ends upwards and downwards, just as has been achieved with the slotted foils 1 via the holes 4.

[58] In the alternative embodiment with perforated foils 70, just as with foil slices with slotted foils 1, walls 30 and 83 form with laterally projecting micro-ribs. In the case of the slotted foils 1, however, the micro-ribs on a wall 30 are alternately at different heights and on different sides. In the case of the perforated foils 70, each wall 86 has along its height 81 always alternately two ribs 84, 85 lying at the same height or a free space. Therefore, in the case of a film stack with slit foils 1, the heat exchange takes place diagonally between the microchannels, whereas with the film stack 80 with perforated foils 70, the heat exchange takes place horizontally in the plane of the foil layers. In both cases, however, the two channel systems are separated by the described walls with micro-ribs, so that without any concerns for the system can also be significant pressure differences in the two channel systems.

It should be noted that the proposed heat exchanger structure is not limited to recuperators, but rather also advantageous as a structure for a regenerator heat exchanger can be used. The exchange of the heat of the at least two fluids can take place in cocurrent or countercurrent. In any case, the microchannels can be connected so that the inflow and outflow of the fluids can take place without crossing. The structure of the proposed micro ribbed wall heat exchanger allows the heat exchange of fluids in the low to high temperature range and in the low pressure and high pressure ranges.

[60] Furthermore, it should be expressly pointed out that the proposed geometry of the individual foils and the overall arrangement of the microchannel systems in the film stacks can also be advantageously used with metal sheets, ie generally with thicker sheet-like components. Even with the use of such components, a device improved over previously known heat exchangers is achieved. The invention is thus not limited to the use of thin films. For thin films, however, it achieves a surprisingly high degree of efficiency.

Claims

claims: 1. microchannel recuperator for heat exchange between two fluids in two separate micro- channel systems, characterized by flat stacked thin film layers with free space in the film stack, which result in the arrangement of the separate microchannel systems. 2. recuperator according to spoke 1, characterized in that the free spaces in the foil pillar at least predominantly result through slits, while walls of the free spaces result from webs. 3. recuperator according to spoke 2, characterized in that the slots are aligned in a Längsrich¬ direction of the film layers. 4. recuperator according to one of claims 2 or 3, characterized in that a web width is greater than a slot width. 5. recuperator according to one of claims 2 to 4, characterized in that slots in be¬ adjacent film layers are offset in parallel. 6. recuperator according to one of claims 2 to 5, characterized in that a width of the slots over a total slot length is constant. 7. recuperator according to one of claims 2 to 6, characterized in that each slot of a first film, a web can be assigned, which completely covers it when a mirror-inverted, but otherwise at least largely identical second film is stacked on the first film. 8. recuperator according to one of claims 2 to 7, characterized by massive walls with Micro-ribs, wherein the walls are formed by overlapping areas of webs of adjacent Folienla¬ gene and the micro-ribs by non-contact overlapping areas of webs. 9. recuperator according to spoke 8, characterized in that a wall thickness in the entire film stack is constant and is half the difference between a width of a web and ei¬ ner width of a slot. 10. recuperator according to one of claims 2 to 9, characterized by a passage of each second film between channels of an adjacent first and an adjacent third film. 11. recuperator according to claim 10, characterized in that the implementation of the second film at slot ends at the first and the third film connects. 12. recuperator according to claim 10 or 11, characterized in that the passage extends over an entire height of the film stack. 13. Recuperator according to one of the preceding claims, characterized by a collecting feed and a Sammelabführ for each microchannel system, wherein the collecting supply and the collecting discharge are each connected to each second microchannel at an edge of the film stack. 14. recuperator according to any one of the preceding claims, characterized in that two separate microchannel systems are connected alternately to laterally adjacent, but separate micro-channels rokanal. 15. recuperator according to claim 1, characterized by arranged in a grid holes in each film layer, so that between the holes a first and a second set of sheets erge¬ Ben, wherein the film layers are stacked offset in such a way that the transverse webs of a second film the the respective perforations of the adjacent overlying third film and the underlying adjacent first film centrally cover, wherein the transverse webs have a ge¬ smaller width than a width of the perforation, so that openings for the passage of a fluid in the overlap between the crossbar and perforations remain , 16. Recuperator according to claim 15, characterized in that the longitudinal webs of the films in the film stack are continuous one above the other and form a wall with lateral ribs. 17. recuperator according to one of the preceding claims, characterized in that sämtli¬ che films of the film stack have a uniform geometry. 18. recuperator according to one of claims 1 to 16, characterized in that the films of the film stack have two different geometries and are preferably alternately stacked. 19. recuperator according to one of claims 2 to 14, characterized in that a film layer has a plurality of film strips which are separated from each other and their distances form the slots and form the webs themselves. 20. Slit or perforated foil, wherein the slots or rows of holes are arranged along a first direction, characterized by an outward arrangement of the slots or holes such that at least substantially every distance transversely to the first direction - in the case of Slit film - or parallel to the first direction - in the case of a perforated film - at each point on the track, the auf¬ has a first distance to a first edge of the film auf¬ and lies in a slot or in a hole, a counter point exists which has a second distance to an opposite second edge of the film and lies on a web or which lies on an edge region between the slot and the edge, wherein the second distance is identical in magnitude to the first distance. 21. Use of a slotted or perforated film, in particular according to claim 20, as Bau¬ element for a microchannel recuperator. 22. A method for producing a microchannel recuperator, in particular according to one of Ansprü¬ che 1 to 19, characterized in that in films slots and / or holes are introduced and the slotted or perforated films or film strips are stacked so that free spaces in the film stack resulting in their arrangement two separate systems of microchannels. 23. A manufacturing method according to claim 22, characterized in that the individual Folienla¬ conditions are brought by punching, laser cutting or etching in their final geometry, be¬ before they are stacked. 24. A manufacturing method according to claim 22 or 23, characterized in that the individual layers of the film stack are connected by diffusion bonding, soldering, gluing or other surface bonding technology surface. 25. A manufacturing method according to any one of claims 22 to 24, characterized in that by overlapping webs massive walls are formed during stacking, which pass through the Fo¬ lienstapel and laterally adjacent to the two separate microchannel systems. 26. Production method according to claim 25, characterized in that films of a geometry are used in producing the film stack and the films are stacked alternately in unter¬ different orientation. 27. Production method according to one of claims 22 to 26, characterized in that films of two different geometries are stacked alternately. 28. A method for operating a microchannel recuperator, in particular according to one of Ansprü¬ che 1 to 19, characterized in that the two microchannel systems are fed with fluids with ei¬ nem considerable pressure gradient, in particular with a pressure ratio of more than 2: 1, especially more than 3: 1, especially more than 10: 1. 29. recuperator in particular according to one of claims 1 to 19 for the heat exchange between two fluids in two separate channel systems auf¬, have a plurality of parallel channels, characterized in that each channel of a channel system has four nearest channels of the other channel system. 30. recuperator to spoke 29, characterized in that the four nearest channels are offset from the considered channel with respect to planes flat stacked channel system components dia¬ gonal. 31. recuperator in particular according to one of claims 1 to 19 or 29 to 30 for heat exchange between two fluids in two separate channel systems, which have a plurality of paralle¬ len channels, characterized in that a first distance between a first and a nearest second channel of a channel system is smaller than a distance between the first channel and a channel closest to this channel of the other channel system and as a distance between the second channel and a channel nearest this of the other channel system