WO1995033173A1

WO1995033173A1 - Heat exchanger

Info

Publication number: WO1995033173A1
Application number: PCT/EP1995/002275
Authority: WO
Inventors: Mouw-Ching Tjiok
Original assignee: Tjiok Mouw Ching
Priority date: 1994-05-31
Filing date: 1995-05-31
Publication date: 1995-12-07
Also published as: DE19519511A1; AU2791795A

Abstract

The invention concerns a heat exchanger (10), operating on the countercurrent principle, for two gaseous fluids at different temperatures. The heat exchanger has hollow panels (12) disposed in a stack with a gap between each panel, the broadside walls (18) of the panels forming heat-transfer surfaces and parallel flow channels (16) for one of the fluids passing through the panels while countercurrent channels (20) for the other fluid run between the panels (12). In order to direct the fluid flows fed in and discharged separately from each other at different ends of the stack (30) of plates, deviation channels (42, 44) are provided at opposite ends of the plates. The plates (12) are designed as hollow-extruded plastic or metal sections having a multiplicity of parallel partitions (32) moulded between the broadside walls (18) and delimiting the flow channels (16).

Description

Heat exchangers and their use

description

The invention relates to a heat exchanger for two or more, preferably gaseous, media of different temperatures, with two groups of flow channels separated from one another by heat transfer surfaces and flowable through the two media via respective inlet and outlet openings according to the countercurrent principle, several at a distance from one another arranged in a stack-like manner, with their broad side walls forming the heat transfer surfaces, through which mutually parallel flow channels of the one medium penetrate hollow plates, countercurrent channels of the other medium running between the hollow plates and two edge edges arranged on opposite sides of the stack of hollow plates groups of plate-wise separate deflection chambers which are open on one side and open at mouth openings into the flow channels or counterflow channels and which are deflected by one of the media through the mouth openings from one of the media are flowable. The invention further relates to various types of use of the heat exchanger.

Heat exchangers of the type mentioned have long been state of the art. They enable the targeted transfer of heat in the direction of a temperature gradient between two or more fluid material or media streams and serve, in particular, to recover waste heat. In so-called recuperators, the heat transfer takes place indirectly as a result of heat transfer through a fixed partition wall, along which the media flow in the opposite direction, separated from one another in a material-tight manner. Due to the countercurrent flow, the outlet temperature of the heat-emitting medium approaches the inlet temperature of the heat-absorbing medium. For the heat transport occurring through the partition approximately applies

Q = k AΔT _m , (1)

with k as the heat transfer coefficient, A as the total transfer area touched by the media and ΔTm as the mean temperature difference between the media. The processes relevant for heat transfer are reflected in the k value, which depends on the heat transfer between the flowing medium and the partition wall on both sides thereof and on the heat conduction in the partition wall. The efficiency achieved in the heat transfer performance, i.e. the ratio of the recovered energy to the maximum recoverable energy can be simplified by the number of heat losses or the temperature efficiency

= (T ₂ - T,) / (T ₃ - T.) (2)

are shown, where T, and T ₂ mean the inlet and outlet temperatures of the colder and T ₃ the inlet temperature of the warmer medium. In the case of countercurrent, the efficiencies which can be achieved at a given temperature difference are greatest in comparison with those in the case of a different flow arrangement, such as direct current, crossflow or crosscurrent. In practice, countercurrent heat exchangers achieve efficiencies of 70 to 95%, while cross-flow heat exchangers achieve a significantly lower efficiency, which is in the range from 50 to 70%. Countercurrent heat exchangers, however, generally have a complicated design. The most common countercurrent heat exchangers, as so-called tube bundle exchangers, consist of a jacket and a tube bundle held therein by a tube sheet, as well as connecting pieces for the supply and discharge of the fluid on the tube and jacket side. Such constructions point require a large amount of space, are complex to manufacture and present difficulties in mass production. They are therefore hardly suitable, in particular, for use in air-conditioning systems, where, in addition to the efficiency, the purchase price and the size are important evaluation factors.

Compact designs with a comparatively cheap heat exchange surface can be achieved by so-called plate exchangers. In the case of these, it is known per se to arrange thin, grooved or corrugated plates in a stacked manner and to guide the warmer and colder medium alternately through the spaces formed between the plates. In order to enable the material separation of the heat-exchanging media on the inlet and outlet sides, in the case of plate exchangers the edge openings of the interspaces are closed media-wise separately on two opposite end faces and the external channel strips are connected to the remaining open end faces. With this connection principle, there is inevitably a cross-current guidance, with the mentioned disadvantage of lower efficiency.

In the case of a heat exchanger of the type mentioned at the outset (DE-A-27 06 253), one of the media streams is guided in a U or Z shape using trapezoidal or diamond-shaped intermediate layers, while the other media stream is carried through plate-shaped hollow bodies rectilinear, parallel flow channels is guided. The intermediate layers forming the counterflow channels are delimited by webs arranged parallel to one another, which reduce the available heat transfer area. The known heat exchanger consists of ceramic materials which are primarily intended for high-temperature applications. It is not intended to be used for room air conditioning, especially using evaporative coolers, and because of the relatively small amount of heat The passage coefficients are also not useful.

Proceeding from this, the object of the invention is to develop a heat exchanger of the type specified at the outset which, with a high efficiency based on countercurrent flow, enables economical production and has a compact design with a large heat transfer surface and opens up new application possibilities.

To achieve this object, the combinations of features specified in claims 1, 12 and 18 are proposed. Advantageous refinements, developments and uses of the invention result from the dependent claims.

The invention is based on the idea that an effective and uniform heat transfer can be achieved in that the hollow plates have thin-walled broad side walls and parallel separating webs arranged between the broad side walls, which delimit a multiplicity of mutually parallel flow channels which are open on the front side. In order to ensure the economical production of such hollow plates, it is proposed according to a first alternative of the invention that the hollow plates are designed as extruded or extruded hollow profile plates made of plastic or metal, which limit a large number of the flow channels , have molded-in, mutually parallel dividers between their broad side walls. With these measures, mass production at low costs is possible. The profile shapes of the hollow profile plates, in particular the thickness of the side walls, the profile shape of the separating webs and the channels and their length can be easily and optimally adapted to the respective requirements. Depending on the application and temperature range of the heat exchanger, the hollow profile plates made of plastics from the group polypropylene, polyethylene, polyvinyl chloride, polystyrene, ABS extruded or extruded from metals from the group aluminum, aluminum alloys. When using these materials, it is possible to produce extremely thin-walled, yet dimensionally stable, hollow profile plates, in particular good heat transfer properties, low weight and low costs associated with material savings.

According to a preferred embodiment of the invention, a two-flow system can be implemented in a particularly simple manner by spacers arranged between the hollow plates, which limit the counterflow channels at least in sections. The spacers can, as strip-shaped sections, consist of the same hollow profile material as the hollow profile plates provided for delimiting the flow channels, which are arranged at equal intervals parallel to one another on the hollow profile plates and whose separating webs run parallel to the separating webs of the hollow profile plates. This ensures sufficient dimensional stability, while at the same time the thickness of the heat transfer surfaces between the media remains essentially limited to the wall thickness of the broad side walls of the hollow profile plates. This increases the heat transfer coefficient k (equation 1) and the heat transfer performance.

Advantageously, the strip-shaped hollow profile plate sections extend with their longitudinal edges running transversely or obliquely to their dividers over the entire height or width of the hollow profile plates and limit the deflection chambers on the mouth side towards the counterflow channels. As a result, the media flow passed through the deflection chambers is divided into individual flow threads, and is supplied in a uniform manner to the counterflow channels formed between the hollow profile plates or discharged from them. The hollow profile plate sections serve immediately as current disturbance elements that destroy the laminar boundary layer of the media flow and thereby improve the heat exchange.

An advantageous embodiment of the invention provides that the spacers consist of corrugated profiled plates made of plastic or metal which, together with the adjacent broad side walls of the hollow profile plates, limit a multiplicity of flow channels running parallel to the separating webs of the hollow profile plates. Deviating from this, the spacers can also consist of a plurality of wavy profiled plate strips which are arranged in the flow direction at a distance from one another between the mutually facing broad side walls of the hollow profile plates and which, together with the adjacent broad side walls, ver essentially parallel to the separating webs of the hollow profile plates ¬ form running channel sections. The wave-shaped profiled plate strips expediently extend with their longitudinal edges running transversely or obliquely to the channel sections over the entire height or width of the hollow profile plates and delimit the deflection chambers on the mouth side towards the counterflow channels.

It is also possible that the spacers consist of guide ribs formed on the plates and running parallel to the flow channels. The guide ribs can be arranged with the same longitudinal offset from one another over the width of the hollow plates at a distance from one another and, with their end faces, limit the orifices of the deflection chambers.

According to a second alternative of the invention, the hollow plates are each composed of a flat base plate and a contact line with the base plate, which has a zigzag or corrugated profile and is broad on parallel to one another. ter formed the formation of the flow channels or counterflow channels connected profile plate. The base plate and the profile plate are preferably designed as an integral extrusion or extrusion made of plastic or metal. However, it is also possible to design the base plate and the profile plate as separate molded parts made of plastic or metal, which are glued or welded to one another at their contact lines. For sealing along the edge edges of a hollow plate, the preferably rectangular base plate is bent at its side edges, preferably towards the side of the profile plate, by approximately 90 °, the bent edges of the base plate having a width corresponding to the maximum profile depth of the profile plate and can be interrupted in the area of the inlet and outlet openings.

According to a third alternative of the invention, the hollow plates are each formed from a flat base plate and a plurality of guide ribs which extend parallel to one another and extend over a broad side surface of the base plate, with lateral delimitation of the flow or counterflow channels and which are integral with the base plate can be connected. The base plate and the guide ribs are advantageously designed as a one-piece extrusion or extrusion made of plastic or metal.

According to a preferred embodiment of the invention, the deflection chambers can be opened in groups via an inlet or outlet opening to opposite end faces of the plate stack that run parallel to the flow channels and can be flowed through at right angles by deflecting the media flow. This makes it possible to guide the media in flow paths that are separated by plates to different end faces of the stack of plates, to which external lines, in particular sewer ducts of ventilation systems, can easily be connected separately from one another are. By deflecting the media flows, the flow or counterflow channels can also be specified in their length independently of the cross sections of the inlet and outlet openings.

Advantageously, the deflection chambers are wedge-shaped in outline and extend over the entire width of the hollow plates with two narrow-sided boundary surfaces adjacent to the inlet or outlet opening and enclosing an acute angle. Due to the wedge shape, a uniform flow distribution or a constant pressure drop across all mouth openings and thus a uniform heat transfer in all the channel strips is achieved. In particular, non-uniform temperature profiles, such as those which occur in known plate exchangers due to the cross-flow guidance over the flow cross section, are avoided.

Advantageously, the deflection chambers open on one of their narrow-side boundary surfaces into the mouth openings of the flow channels or counterflow channels and are closed gas-tight on their other narrow-side boundary surface by an end wall. A deflection of the media flow is thereby achieved in a particularly simple manner, without further measures such as the installation of baffles being necessary.

In order to supply and discharge the two media on opposite end faces of the stack of plates, the counterflow channels on the inflow and outflow sides can open into one of the two groups of deflection chambers and the flow channels end at inlet and outlet openings on opposite end faces of the stack of hollow plates or the other way around. As an alternative to this, the media can be moved in and out again via respective end faces of the stack of plates are discharged when the flow channels on the input side and the counterflow channels on the output side are connected to one of the groups of deflection chambers, or vice versa.

A further preferred embodiment of the invention provides that the flow ducts and the counterflow ducts are connected on the inlet and outlet sides to one of the groups of deflection chambers and that the inlet and outlet openings of the hollow plates stacked one above the other at both ends of the stack alternately towards opposite longitudinal sides of the hollow plates. This results in two inlet openings and outlet openings for the two media streams, which are aligned parallel to one another.

An advantageous modification of this design provides that the flow channels are connected on the inlet and outlet sides to one of the groups of deflection chambers, that the counterflow channels are only connected on the inlet or outlet side to one of the groups of deflection chambers and that the inlet and outlet openings of the sandwich-like stacked stack Point the hollow plates at one end of the stack alternately towards opposite longitudinal sides of the hollow plates.

According to a further advantageous embodiment of the invention, flow obstacles are arranged in the flow channels and / or counterflow channels to generate a turbulent flow. This further improves the heat exchange between the media.

For use in evaporative coolers, it is advantageous if the flow ducts and the counterflow ducts of a pair of hollow profile plates or stapleis communicate with one another in the region of their one facing mouth opening to form a closed flow reversal chamber. Water spray nozzles can be located in the flow reversal chamber and a water reservoir through which the medium can flow can be arranged, the water reservoir being able to consist of a textile fiber fabric or nonwoven fabric.

A preferred use of the heat exchanger according to the invention envisages its use in air-conditioning systems for heating or cooling a supplied outside air flow using the heat content of an exhaust air flow. In such applications, no extreme demands are placed on the pressure and temperature resistance of the heat exchanger material, while the low purchase price, the small space requirement with a large heat exchanger area and the high efficiency of the heat exchanger according to the invention are important evaluation criteria.

The invention is explained in more detail below on the basis of the exemplary embodiments shown schematically in the drawing. Show it

1 shows a perspective view of a heat exchanger through which its front sides can flow, according to the countercurrent principle;

FIG. 2 shows the cross-sectional profile of a hollow profile plate of the heat exchanger according to FIG. 1;

3 shows an enlarged perspective view of an exchanger unit of the heat exchanger according to FIG. 1 consisting of a hollow profile plate and spacers;

3a to 6 alternative embodiments of an exchanger unit in the illustration according to FIG. 3;

Fig. 7 is a diagram of an arrangement of the heat exchanger in an air conditioning system;

8 is a perspective view of a cooler unit of an evaporative cooler consisting of a hollow profile plate, spacers and a flow reversal chamber;

9 shows a schematic sectional illustration through an evaporative cooler through which the countercurrent principle can flow;

10 shows a schematic illustration of an air conditioning system for cooling a building space, consisting of a heat exchanger according to FIG. 1 and an evaporative cooler according to FIG. 9;

11a to c show three further alternative embodiments of hollow plates for producing an exchanger unit in a perspective view;

12 shows the hollow plate according to FIG. 11a in a perspective exploded view;

13 shows a perspective view of a heat exchanger through which its longitudinal sides can flow according to the countercurrent principle;

14a and b show two complementary exchanger units of the heat exchanger according to FIG. 1 in an enlarged perspective view;

14c shows a section along the section line C-C of FIG. 14b;

15 is a top view of a heat exchanger according to chend Fig. 13 with two fans;

FIG. 16 is a top view of the heat exchanger according to FIG. 15 with fans driven by a motor;

Fig. 17 is a plan view of a heat exchanger modified compared to Figs. 15 and 16.

The heat exchanger 10 shown in FIG. 1 consists essentially of a plurality of hollow profile plates 12 and spacers 14 arranged in an alternating stack in a stack-like manner, the hollow profile plates 12 being traversed through by flow channels 16 of a medium and with their as Broad side walls 18 serving for heat transfer surfaces are in thermal contact with counterflow channels 20 of another medium arranged between the successive plates 12. The heat-exchanging media can be fed in and out in two separate streams 26, 28 via frontal inlet and outlet openings 22, 22 ', 24, 24' of the plate stack 30 and are thereby removed within the plate stack 30 according to the countercurrent principle passed along the heat transfer surfaces.

The individual hollow profile plates 12 have an elongated, narrow rectangular profile with thin-walled, parallel broad side walls 18 and separating webs 32 which run transversely between the broad side walls 18 and are arranged at equal distances from one another. The flow channels 16, which are delimited by the broad side walls 18 and separating webs 32, thus pass through the hollow profile plate 12 in a parallel, straight-line arrangement and open at the front sides thereof in an inlet and outlet opening 22 ', 24'.

In each case form a hollow profile plate 12 and the spacers 14 arranged on one of its broad side walls 18 together a structural and functional unit of the heat exchanger 10. Such exchanger units 34, which can be joined together or stacked in a freely definable number, are from the media via the flow channels 16 and from the spacers 14 on the inlet and outlet sides limited counterflow channel 20 can be flowed through in opposite flow directions. They can be implemented in various embodiments while maintaining the countercurrent principle, some of which are described below.

In the embodiment shown in FIG. 3, the spacers 14 consist of elongated, parallelogram-shaped hollow profile plate sections or plate strips 15, the longitudinal edges 36 of which run obliquely to the separating webs 32. The plate strips 15 are fastened to the broad side wall 18 of the hollow profile plate 12 by suitable connecting means, for example welded or glued. They are arranged at the same distance from each other along the plate 12 and extend with their longitudinal edges 36 over essentially the entire plate height, ie the vertical extent of the hollow profile plate 12 in the arrangement shown. The separating webs 32 in the plate strips 15 run parallel to the separating webs 32 in the hollow profile plate 12. On the broad side wall 18 of the hollow profile plate 12, in addition to the spacers 14, sealing means running along the edge edges are provided, which in the exemplary embodiment shown are in the form of a rod-shaped flat end ¬ wall elements 38 are formed. The end wall elements 38 are used for the edge-side sealing of the intermediate space delimited by mutually facing broad side wall surfaces of successive exchanger elements 34. Basically, curable connecting means or potting compounds are also suitable as a sealing means for sealing the space on the edge in a gastight manner and for rigidly connecting the adjacent hollow profile plates 12 to one another. The horizontal, End wall elements 38 arranged parallel to the flow channels 16 and end edges 40 of the hollow profile plates 12 run from diagonally opposite corners of the hollow profile plate 12 to the most distant longitudinal edge 36 of the plate strips 15 and thus each give an inlet or outlet opening 22, 24 for one of the Media free.

In addition to their function as spacers, the hollow profile plate strips 14 also serve to guide a media flow 26 which is passed through the intermediate space through the inlet and outlet opening 22, 24 (which is illustrated in FIG. 3 by arrows with open arrowheads). Of particular importance in this regard are the two outer plate strips 15, which separate a space in the form of a parallelogram in its base area as a counterflow channel 20 from wedge-shaped spaces on the inlet and outlet sides serving as deflection chambers 42, 44. In the inlet-side deflection chamber 42, the medium flowing in via the inlet opening 22 is deflected at right angles by the separating webs 32 or channel sections 45 of the plate strip 15 adjoining the deflection chamber 42 perpendicular to the inflow direction. Due to the wedge-shaped narrowing of the deflection chamber 42, the media stream 26 is evenly distributed over the mouth openings 46 of the channel sections 45 of the plate strip 14 and directed as individual partial streams 48 into the counterflow channel 20. When flowing through the counterflow channel 20, the partial flows 48 are separated from one another only in the region of the plate strips 15 by solid walls. On the outlet side of the counterflow duct 20, the partial streams 48 introduced through the duct sections 45 of the closing plate strip 14 into the outlet-side deflection chamber 44 are redirected again by 90 ° and again through the outlet opening 24 in the same direction as the inflow direction dissipated. For the purpose of heat transfer, the second, warmer or colder medium is passed through the flow channels 16 of the hollow profile plate 12 (arrows with filled tips in FIG. 3). The direction of flow is opposite to the flow of the first medium in the counterflow channel 20, the heat transfer taking place through the wide side wall 18 of the hollow profile plate 12 serving as a partition and heat transfer surface between the media. The two media streams 26, 28 run in cross flow only in the narrow region of the deflection chambers 42, 44. However, this area can be kept small in relation to the total heat exchange area by appropriate selection of the flow channel length.

The exemplary embodiment shown in FIG. 3a differs from the exemplary embodiment according to FIG. 3 in that the spacers consist of a plurality of wave-shaped profiled plate strips 15 ', which are arranged at a distance from one another between the mutually facing broad side surfaces of the hollow profile plates 12 and which are together form with the adjacent broad side surfaces substantially parallel to the separating webs 32 of the hollow profile plates 12 channel sections 45. In principle, it is also possible to form the spacers from wave-shaped profiled plates made of plastic or metal, which, together with the adjacent broad side walls of the hollow profile plates, delimit a plurality of flow channels 45 running parallel to the separating webs 32 of the hollow profile plates 12 .

In the modified exemplary embodiment of an exchanger unit shown in FIG. 4, instead of a plurality of plate strips 15, a single, parallelogram-shaped hollow profile plate piece 50 is provided, which with its inclined surfaces Front sides 52, 54 delimit the deflection chambers 42, 44, and their channels 56, which run between the deflection chambers 42, 44, in their entirety form the counterflow duct 20. The hollow profile plate piece 50 has essentially the same base area as the counterflow duct 20 delimited by the plate strips 15. However, the partial streams formed at the mouth openings to the inlet-side deflection chamber 42 are constantly separated from one another in the channels 56 of the hollow profile plate piece 50 by solid walls and therefore are not deflected transversely to the intended flow direction. The hollow profile plate piece 50 increases the dimensional stability of the heat exchanger 10 compared to individual plate strips 15, but deteriorates the heat transfer due to the increased thickness of the partition walls between the media due to the wall thickness of its broad side walls. The media not shown in FIG. 4 is guided according to the principle shown in FIG. 3.

In the exemplary embodiment according to FIG. 5, the spacers 14 consist of guide ribs 58 formed on the hollow profile plates 12 or extruded together with them and running parallel to the flow channels 16. The guide ribs 58 are at the same longitudinal offset from one another over the height of the hollow plate 12 are arranged at a distance from one another and their end faces 60 limit the orifices 46 to the deflection chambers 42, 44. In their entirety, the guide ribs 58 likewise delimit a parallelogram-shaped counterflow channel 20 which is subdivided into individual subchannels 62 running between the guide ribs 58. The flow is therefore carried out in the same way as in the exemplary embodiments shown in FIGS. 3 and 4. As illustrated on the top guide rib 58, flow obstacles 64 can be attached to the guide ribs 58 to generate a turbulent flow, as a result of which the heat transfer between the fluidized medium and the heat transfer area improved.

6 shows an exemplary embodiment in which the flow guidance is modified such that both media are each passed through a deflection chamber 42, 44 and their flow is deflected by 90 °. For the flow on the hollow profile plate side, the deflection chamber 42 is formed by a wedge-shaped plate end piece 66, the channel strips 68 of which are sealed gas-tight and which is attached to the inlet-side end face of the hollow profile plate 12. Instead of an end piece 66, a wedge-shaped recess can also be provided in the plate 12. In the embodiment shown in FIG. 4, the end piece 66 is fastened to a spacer 14, which is formed from a rectangular plate section 70 and is fastened to the hollow profile plate 12 with lateral coverage of the deflection chamber 42 on the flow channel side. The plate section 70 serves, on the one hand, as a termination of the counterflow channel 20 and for the straight-line discharge of the media flow 28 which is passed through it 3 deflected at right angles.

All of the exemplary embodiments explained above have the common principle that the media streams 26, 28 can be supplied and discharged through the deflection in the deflection chambers 42, 44 at different end faces of the exchanger unit 34. In this way, the respective inlet and outlet openings 22, 22 ', 24, 24' of a group of exchanger units 34 forming a heat exchanger 10 can be connected in groups in a simple manner, each with a connecting piece of an external channel. The illustrated flow directions of the flow or counterflow channels 16, 20 are reversible. Particularly when using the heat exchanger 10 for heat recovery from forwarded room air, there are particularly simple connection options by flange-mounting the external channels, which are usually designed as rectangular shafts, directly on the end faces of the plate stack 30.

7 shows the use of the heat exchanger 10 in an air-conditioning system 72, which is intended to supply a building room 74 with cooled outside air. The outside air stream 76 to be cooled and the exhaust air stream 78 having a lower temperature are directed to the inlet side of the heat exchanger 10. A heat transfer from the outside air 76 to the exhaust air 78 takes place in the heat exchanger 10, i.e. the "residual coolness" of the exhaust air, which would be uselessly lost in normal room ventilation, can be used to pre-cool the outside air. The thus cooled outside air flow 76 is further cooled by the evaporator 80 of a refrigerant circuit 82 of the air conditioning system 72 and supplied as a supply air flow 84 to the room 74 to be air-conditioned. On the other hand, the exhaust air stream 78 which is heated by the outside air stream 76 within the heat exchanger 10, but whose temperature has not yet been fully adjusted to the outside temperature, is used for further cooling the condenser 86 of the refrigerant circuit 82 and is then only released as an exhaust air stream 88. To influence the mass flow ratio between the outside air flow 76 and the exhaust air flow 78 and thus the heat exchange performance of the heat exchanger 10, the exhaust air flow 78 can be partially branched off via a bypass duct 90 provided with an adjustable throttle valve 89 and admixed to the supply air flow 84 as a circulating air flow 92.

The use of the heat exchanger 10 described above is mainly possible during the summer months. At low outside temperatures, on the other hand, it can be in the exhaust air contained heat in the heat exchanger can be recovered by preheating the outside air. The heat transfer takes place in the opposite direction. With a humid exhaust air flow (humidifier 94) and strong cooling, the saturation temperature is reached and the moisture contained in the exhaust air is never reflected with the release of the latent heat of condensation on the heat transfer surfaces.

This reduces the further cooling of the exhaust air, i.e. the temperature difference between the outside and exhaust air flow and thus the efficiency is higher than without condensation. In addition, the deposited water film changes the interface conditions on the heat transfer surfaces and therefore improves the heat transfer.

The cooler unit 100 shown in Fig. 8 has basically the same structure as the exchanger unit of Fig. 3, wherein instead of the inlet and outlet openings 22 and 24 'a flow reversal chamber 102 is provided at one end of the cooler unit 100, which from the hollow profile plate 12 end media flow exiting into the counterflow channels 20. The medium is thus directed to itself through the cooler unit 100 according to the counterflow principle. In order to cool the medium, a number of water spray nozzles 104 are arranged in the flow reversal chamber 102, which humidify the media stream 106 emerging from the hollow profile plate 12 and thereby adiabatic, evaporative cooling of the medium by utilizing the evaporation enthalpy of the water bring about. In addition to the water spray nozzles 104, in the flow reversal chamber 102 there is a water storage element 108 consisting of a natural or synthetic fiber fabric and through which the medium can flow, which is used to further load the media stream with moisture up to its saturation level. supply leads. The water storage element 108 is moistened by means of the water spray nozzles 104.

The mode of operation of the cooler unit 100 is as follows: The inlet opening 22 'of the hollow profile plate 12 is acted upon by the media stream to be cooled, for example the (dry) exhaust air stream from a building room. This passes through the large number of flow channels 16 into the area of the flow reversal chamber 102, where it is moistened by means of the water spray nozzles 104 and the water storage element 108 and deflected into the counterflow channels 20. The humidification of the media flow leads to an adiabatic cooling of the medium, heat being removed from the media flow by the evaporation of the water. As a result, the relative humidity of the medium increases while its temperature drops. The media stream cooled in this way passes through the counterflow channels 20, heat exchange taking place via the heat transfer surface 18 with the media stream in the hollow profile plate 12, so that a pre-cooled media stream enters the flow reversal chamber 102. The media flow in the counterflow channels 20 mainly absorbs the heat without evaporating an excess temperature to evaporate excess water. In this case, even a water film wetting the heat transfer surface 18 can occur.

The cooler unit 100 combines the direct evaporative cooling with the indirect evaporative cooling via the heat transfer surface 18 according to the countercurrent principle and thereby achieves a high degree of efficiency.

The evaporative cooler 110 (FIG. 9) consists, analogously to the heat exchanger 10 of FIG. 1, of a freely definable number of stacked cooler units 100, the flow reversal chamber 102 extending over the entirety of the cooler units 100. The medium to be cooled is fed to the inlet openings 22 'of the hollow profile plates 12 by means of a blower 112 and leaves the evaporative cooler 110 via the outlet openings 24 of the counterflow channels 20, from where it can be fed to a further utilization via a collecting shaft, for example in an air conditioning system according to FIG. 10.

The system according to FIG. 10 is used to cool the building space 114, the cool exhaust air flow illustrated by the arrows with filled tips being passed through the evaporative cooler 110 for further cooling and, after exiting from it, is fed to the heat exchanger 10 via the connecting shaft 116 becomes. The warm supply air flow illustrated by the arrows with open tips is directed in counterflow to the cooled exhaust air flow while cooling through the heat exchanger 10 by means of the fan 118 into the room 114, which is thus supplied with dry and cool fresh air.

The heat exchanger 10 shown in FIG. 13 has a multiplicity of hollow plates 12 ′, 12 ″, which are arranged in an alternating sequence in stacks in a stack, one above the other, and which can in principle be constructed in the manner shown in FIGS. 11a to c .

The hollow plates 12 ', 12''shown in FIGS. 11a and b consist of a flat base plate 100 and a contact line with the base plate 100, which has a zigzag or corrugated profile and is broadly parallel to one another, with the formation of flow channels 16', 16 ″ or corresponding countercurrent channels 20 ′, 20 ″ connected profile plate 102. The base plate 100 and the profile plate 102 can be composed of two parts in the sense of FIG. 12 and glued or welded together. However, they can also be in one piece, for example in the extrusion or extrusion process. be produced.

In the exemplary embodiment according to FIG. 11c, the hollow plate 12 ', 12' 'consists of a flat base plate 100 and a multiplicity of guide ribs 104 projecting over a broad side surface of the base plate 100 and extending parallel to one another. The base plate 100 and the guide ribs 104 are also expediently produced in this embodiment as a one-piece extrusion or extrusion made of plastic or metal.

To complete the exchanger units 12 ', 12' ', the side edges 106 of the base plate 100 are bent 90 ° to the side of the profile plate 102 in the sense of FIGS. 14a to c and are dimensioned such that they are one of the maximum profile depth have the corresponding width of the profile plate 102. In addition, the profile plates 102 are cut obliquely to form the deflection chambers 42, 44 and the orifices 46. Furthermore, to form the inlet and outlet openings 22, 24, the longitudinal side edge 106 is cut off at the relevant point. The exchanger units 12 ', 12' 'for the different media are provided with differently designed deflection chambers 42, 44 and inlet and outlet openings 22, 24 by appropriately cutting the profile plates 102 at the orifices 46. The flow channels or counterflow channels of an exchanger unit are divided into two channel areas 16 ', 16' 'or 20', 20 '' by the profile plates 102, of which the channel area 16 ', 20' is open to the base plate 100 of the relevant exchanger element while the channel region 16 ″, 20 ″ is open to the base plate 100 of the adjacent exchanger unit. The stacked hollow plates 12 ', 12' 'are connected airtight at the joints of their side edges 106.

13 to 16 are the Flow channels 16 ', 16''and the counterflow channels 20', 20 '' on the input side and on the output side are each connected to a deflection chamber 42, 44, so that the inlet and outlet openings 22, 24 of the sandwich-like stacked hollow plates in the vicinity of the two stack ends alternately point to one or the other long side of the hollow plates 12 ', 12''. The two exchange media (arrows 108 and double arrows 110) are supplied in parallel from one long side of the exchanger, while the two exchange media are also removed in parallel on the other side of the exchanger. The blowers 112, 114 necessary for this are shown in the exemplary embodiment according to FIG 16 driven by a common motor 116.

The exemplary embodiment according to FIG. 17 differs from that according to FIG. 15 in that only three of the input and output-side media streams are directed in parallel, while the fourth media stream is oriented perpendicularly thereto. This is made possible by a corresponding design of the deflection chambers 42, 44 within the heat exchanger units.

In summary, the following can be stated: The invention relates to a heat exchanger 10 through which the countercurrent principle can flow, for two gaseous media of different temperatures. The heat exchanger has stacked hollow plates 12 which are spaced apart from one another and which, with their wide side walls 18, form heat transfer surfaces and are penetrated by parallel flow channels 16 of one medium, while counterflow channels 20 of the other medium run in the area between the hollow plates 12. Deflection chambers 42, 44 are provided for deflecting the flow of the media flows, which are supplied and discharged separately from one another on different end faces of the hollow plate stack 30, and are arranged on opposite sides of the hollow plates. are ordered. The hollow plates 12 are designed as extruded or extruded hollow profile plates made of plastic or metal, which have a large number of separating webs (32) which delimit the flow channels (16) and are formed between their broad side walls (18).

Claims

1. Heat exchanger for two or more, preferably gaseous media of different temperatures, with two separated by heat transfer surfaces (18) from the two media via respective inlet and outlet openings (22, 24, 22 ', 24') groups of flow channels (16) through which the countercurrent flows, a plurality of which are arranged in a stack at a distance from one another, with their wide side walls (18) forming the heat transfer surfaces and parallel flow channels (16) of the one hollow medium (12) penetrated by one medium, between the counterflow channels (20) of the other medium running the hollow plates and two edges which are arranged on opposite sides of the stack of hollow plates (30), open at the edge and end at orifices (46) into the flow channels (16) or counterflow channels (20) Groups of deflection chambers (42, 44) which are separated from one another in plates and which, via the orifices (46), form vo n one of the media can be flowed through while deflecting the flow, characterized in that the hollow plates (12) are designed as extruded or extruded hollow profile plates made of plastic or metal, which delimit a plurality of the flow channels (16) between their broad side walls (18) arranged, mutually parallel dividers (32).

2. Heat exchanger according to claim 1, characterized gekennzeich¬ net that the hollow profile plates (12) consist of an extruded plastic from the group of polypropylene, polyethylene, polyvinyl chloride, polystyrene, ABS.

3. Heat exchanger according to claim 1, characterized gekennzeich¬ net that the hollow profile plates (12) made of an extruded metal from the group aluminum, aluminum alloy conditions exist.

4. Heat exchanger according to one of claims 1 to 3, da¬ characterized in that spacers (14; 15,50,58,70) are arranged between facing broad side walls (18) of the hollow profile plates (12), which the counterflow channels ( 20) limit at least in sections.

5. Heat exchanger according to claim 4, characterized gekennzeich¬ net that the spacers from a plurality, in the flow direction at a distance from each other between the facing broad side walls (18) of the hollow profile plates (12) arranged strip-shaped hollow profile plate sections (15), the separators (32) run essentially parallel to the separating webs (32) of the hollow profile plates.

6. Heat exchanger according to claim 5, characterized gekennzeich¬ net that the strip-shaped Hohlprofilplattenabschnit¬ te (15) with their transverse or oblique to their Trenn¬ webs (32) extending longitudinal edges (36) substantially over the entire width of the hollow profile plates (12) extend and limit the deflection chambers (42, 44) on the mouth side to the counterflow channels (20).

7. Heat exchanger according to claim 4, characterized gekennzeich¬ net that the spacers consist of wave-shaped profiled plates made of plastic or metal, which together with the adjacent broad side walls of the hollow profile plates (12) a plurality of parallel to the dividers ( 32) limit the flow channels (45).

8. Heat exchanger according to claim 4, characterized in net that the spacers consist of several, in the flow direction at a distance from each other between the mutually facing broad side surfaces (18) of the hollow profile plates (12), wavy profiled plate strips (15 '), which together with the neighboring ones Broad channel surfaces (18) delimit channel sections (45) which run essentially parallel to the separating webs (32) of the hollow profile plates (12).

9. Heat exchanger according to claim 8, characterized gekennzeich¬ net that the wavy profiled plate strips (15 ') with their transverse or oblique to the separating webs (32) extending longitudinal edges (36) extend substantially over the entire width of the hollow profile plates (12) and delimit the deflection chambers (42, 44) on the mouth side towards the counterflow channels (20).

10. Heat exchanger according to claim 4, characterized gekennzeich¬ net that the spacers (14) formed on the broad side walls (18) of the hollow profile plates (12), parallel to the flow channels (16) extending guide ribs (58) consist.

11. Heat exchanger according to claim 10, characterized gekennzeich¬ net that the guide ribs (58) with the same longitudinal offset to each other over the height of the hollow profile plates (12) are arranged at a distance from each other and with their front ends (60), the mouth openings (46) limit the deflection chambers (42, 44).

12. Heat exchanger for two or more, preferably gaseous media of different temperatures, with two separated by heat transfer surfaces (18) from the two media via respective inlet and outlet openings (22, 24, 22 ', 24') the countercurrent principle Flow-through groups of flow channels (16), a plurality of which are arranged in a stack-like manner at a distance from one another, with their broad side walls (18) forming the heat transfer surfaces and parallel flow channels (16) of the hollow plates (12, 12 ', 12 through which one medium passes) ''), countercurrent channels (20) of the other medium which run between the hollow plates and two edge edges which are arranged on opposite sides of the stack of hollow plates (30) and open at the mouth openings (46) into the flow channels (16) or countercurrent channels ( 20) opening groups of plate-wise separate deflection chambers (42, 44), through which flow through the mouth openings (46) one of the media can be flow-deflected, characterized in that the hollow plates (12 ', 12'') each consisting of a flat base plate (100) and a contact line that is parallel to one another and has a zigzag or corrugated profile n are formed with the base plate (100) to form the profile plate (102) connected to the flow channels (16 ', 16'') or counterflow channels (20', 20 '').

13. Heat exchanger according to claim 12, characterized gekennzeich¬ net that the base plate (100) and the profile plate (102) are formed as a one-piece extrusion or extrusion made of plastic or metal.

14. Heat exchanger according to claim 12, characterized gekennzeich¬ net that the profile plate (102) and the base plate (100) are formed as separate molded parts made of plastic or metal, which are glued or welded together at their contact lines.

15. Heat exchanger according to one of claims 12 to 14, da¬ characterized in that the preferably rectangular base plate (100) on its side edges (106) preferred is bent to the side of the profile plate (102) by approximately 90 °.

16. The heat exchanger according to claim 15, characterized in that the bent side edges (106) of the base plate (100) have a width corresponding to the maximum profile depth of the profile plate (102).

17. Heat exchanger according to claim 15 or 16, characterized ge indicates that the bent side edges (106) are interrupted in the region of the inlet and outlet openings.

18. Heat exchanger for two or more, preferably gaseous media of different temperatures, with two separated by heat transfer surfaces (18) from the two media via respective inlet and outlet openings (22, 24, 22 ', 24') Groups of flow channels (16) through which the countercurrent flows, a plurality of which are arranged in a stack-like manner at a distance from one another, with their broad side walls (18) forming the heat transfer surfaces and having parallel flow channels (16) of the hollow medium (12 ', 12) passing through them with one another ''), between the hollow plates running counterflow channels (20) of the other medium and two edges on opposite sides of the hollow plate stack (30), open at the edge and at mouth openings (46) into the flow channels (16) or counterflow channels ( 20) opening groups of deflecting chambers (42, 44) which are separated from one another in plates, and which run over the opening n (46) can be flowed through by one of the media with flow deflection, characterized in that the hollow plates (12 ', 12'') each consist of a flat base plate (100) and a plurality of over a broad side surface of the base plate protruding, with lateral limitation of the flow channels (16) or counter flow channels (20) parallel to each other leading vanes (104) are formed.

19. Heat exchanger according to claim 18, characterized gekennzeich¬ net that the base plate (100) and the guide ribs (104) are designed as one-piece extrusion or extrusions made of plastic or metal.

20. Heat exchanger according to one of claims 1 to 19, da¬ characterized in that the deflection chambers (42, 44) in groups via an inlet or outlet opening (22, 24) to opposite, parallel to the flow channels end faces of the plate stack (30) are open towards the edge and can be flowed through with a right-angled deflection of the media flows (26, 28).

21. Heat exchanger according to one of claims 1 to 20, characterized by the fact that the deflection chambers (42, 44) are wedge-shaped in outline and adjoin an acute angle with two adjacent to the inlet and outlet opening (22, 24) Narrow-side boundary surfaces extend over the entire height of the hollow profile plates (12).

22. Heat exchanger according to one of claims 1 to 21, characterized by the fact that the deflection chambers (42, 44) open at one of their narrow-side boundary surfaces into the mouth openings (46) of the flow channels (16) or countercurrent channels (20), and that the other narrow-sided boundary surface is sealed gas-tight by an end wall (38).

23. Heat exchanger according to one of claims 1 to 22, da¬ characterized in that the counterflow channels (20) on the inflow and outflow sides open into one of the two groups of deflection chambers (42,44) and the flow channels (16) end at inlet and outlet openings (22 ', 24') on opposite end faces of the stack of hollow plates (30), or vice versa.

24. Heat exchanger according to one of claims 1 to 23, characterized in that the flow channels (16) on the input side and the counterflow channels (20) on the output side are connected to one of the groups of deflection chambers (42, 44), or vice versa .

25. Heat exchanger according to one of claims 1 to 24, characterized in that the hollow plates (12) have rectangular, elongated in the direction of the flow channels (16), preferably thin-walled broad side walls (18).

26. Heat exchanger according to one of claims l to 25, da¬ characterized in that the spaces between the countercurrent channels (20) forming the hollow plates (12) on the end faces of the stack of hollow plates (30) are closed gas-tight.

27. Heat exchanger according to one of claims 1 to 26, characterized by the fact that the flow channels (16 ', 16' ') and the counterflow channels (20', 20 '') on the input side and on the output side each with one of the groups of deflection chambers (42, 44) are connected, and that the inlet and outlet openings (22, 24, 22 ', 24') of the hollow plates (12 ', 12' ') stacked one above the other in the vicinity of the two stack ends alternate point to opposite long sides of the hollow plates (12 ', 12' ').

28. Heat exchanger according to one of claims 1 to 27, characterized in that the flow channels (16) on the input side and on the output side with one of the groups of Deflection chambers (42, 44) are connected such that the counterflow channels (20) are connected to one of the groups of deflection chambers only on the input or output side and that the inlet and outlet openings (22, 24, 22 ', 24') of the sand ¬ point-like stacked hollow plates (12 ', 12'') only at one end of the stack alternately pointing to opposite longitudinal sides of the hollow plates.

29. Heat exchanger according to one of claims 1 to 28, characterized by ge in the flow channels (16) and / or counterflow channels (20) arranged flow obstacles (64) for generating a turbulent flow.

30. Heat exchanger according to one of claims 1 to 29, da¬ characterized in that the flow channels (16) and the countercurrent channels (18) of a pair of hollow profile plates or -stapeis communicate with each other in the region of one of its orifices (46) to form a flow reversal chamber (102) .

31. Heat exchanger according to claim 30, characterized gekennzeich¬ net that the flow reversal chamber (102) with water be¬ be¬.

32. Heat exchanger according to claim 30 or 31, characterized ge indicates that a water storage element (108) through which the medium can flow is arranged in the flow reversal chamber.

33. Heat exchanger according to claim 32, characterized gekennzeich¬ net that the water storage element (108) consists of a fiber fabric or a nonwoven fabric.

34. Heat exchanger according to claim 33, characterized gekennzeich¬ net that the fiber fabric or nonwoven fabric made of textile There is fiber material.

35. Use of a heat exchanger according to one of claims 1 to 34 in air conditioning systems (72) for heating or cooling a supplied outside air flow (76) by utilizing the heat content of an exhaust air flow (78).

36. Use according to claim 35, wherein the outside air flow (76) or exhaust air flow (78) is additionally cooled using the enthalpy of vaporization of a slightly evaporating cooling liquid, in particular water.

37. Use according to claim 35 or 36 in combination with an evaporator (80) and a condenser (86) of an air conditioning system (72), the outside air flow (76) through the evaporator (80) and the condenser (86) through the exhaust air flow ( 88) is additionally cooled.

38. Use according to one of claims 35 to 37, characterized in that the throughput of the outside air flow (76) is adjusted by admixing a recirculated air flow (92) branched off from the exhaust air flow (78) and admixed with the supply air flow (84).