EP0835416A1

EP0835416A1 - Heat exchanger with improved configuration

Info

Publication number: EP0835416A1
Application number: EP96921155A
Authority: EP
Inventors: Wessel Bart Veltkamp
Original assignee: Level Energietechniek BV
Current assignee: Level Energietechniek BV
Priority date: 1995-06-30
Filing date: 1996-06-27
Publication date: 1998-04-15
Anticipated expiration: 2016-06-27
Also published as: ES2129976T3; DK0835416T3; DE69602025D1; EP0835416B1; NL1000706C2; ATE178707T1; WO1997002461A1; DE69602025T2

Abstract

The invention relates to a heat exchanger (1) comprising channels of the first sort and channels of the second sort, wherein the channels extend mutually parallel, are mutually separated by walls, are substantially mutually adjacent and in section are ordered according to a regular pattern, wherein the heat exchanger (1) is assembled from flat plates (2) and profiled plates (3) stacked alternately on each other and forming the walls, wherein the profiled plates (3) come into contact with both adjoining flat plates (2) and each of the plates forms a separation between channels of the first sort on a first side and channels of the second sort on the second side. Stacking of the plates on each other results in a simple construction. It is also less important herein that the plates are placed in mutually displaced manner; in all cases the channels of the first sort are bounded by channels of the second sort. It is herein pointed out that the attractive construction according to the invention makes it possible to apply heat exchangers in areas where until now this was unattractive because of the high costs.

Description

HEAT EXCHANGER WITH IMPROVED CONFIGURATION

The invention relates to a heat exchanger, comprising channels of the first sort and channels of the second sort, wherein the channels extend mutually parallel, are mutually separated by walls, are substantially mutually adjacent and in section are ordered according to a regu¬ lar pattern.

Such a heat exchanger is known inter alia from the patent application with publication number WO 94/100520.

This heat-;exchanger of the prior art has the drawback that the seals between the various walls must satisfy strict requirements relating to the sealing of the fluids to be transported through the heat exchanger in order to prevent fluid flowing in the channels of the first sort from entering fluid flowing through channels of the sec- ond sort and vice versa.

This is of particular importance when use is made of different pressures in the various fluids.

Such a heat exchanger of the prior art is moreover difficult to construct. The greatest precision must in any case be exercised during construction in order to ensure that the channels of the first sort are enclosed on all sides by channels of the second sort.

The object of the present invention is to provide such a heat exchanger, wherein the above mentioned prob- lems are avoided, i.e. a heat exchanger which is simple to construct, wherein less high standards of accuracy of construction are required, and wherein the fluids flowing in the different sorts of channels are prevented from intermixing. This object is achieved in that the heat exchanger is assembled from flat plates and profiled plates stacked alternately on each other and forming the walls, wherein the profiled plates come into contact with both adjoining flat plates and each of the plates forms a separation between channels of the first sort on a first side and channels of the second sort on the second side. Stacking of the plates on each other results in a simple construction. It is also less important herein that the plates are placed in mutually displaced manner; in all cases the channels of the first sort are bounded by channels of the second sort.

It is. herein pointed out that the attractive con¬ struction according to the invention makes it possible to apply heat exchangers in areas where until now this was unattractive because of the high costs. An example here is a fan for use in private houses. The cost price of a heat exchanger according to the invention is so low that it could be used for practically full heating of air en¬ tering the hou^e by air leaving the house.

Another application lies in use as condenser and also recuperator in for instance tumble dryers or refrigera¬ tion installations, or as pre-heater for burners.

According to a preferred embodiment the profiled plates are connected by adhesion to each of the adjoining flat plates. According to a second preferred embodiment the heat exchanger is provided on at least one side with a con¬ necting piece, wherein the connecting piece is formed by continuations of the flat plates and by substantially flat continuations of the profiled plates. This results in an integral construction of the actu¬ al heat exchanger and "the connecting pieces, whereby the total unit of heat exchanger and the connecting pieces formed on both sides thereof is kept as simple as possi¬ ble,- the connecting pieces are formed as it were auto- matically during stacking of the plates of the heat ex¬ changer.

According to yet another embodiment the continuations of the flat plates and the flat continuations of the pro¬ filed plates extend into the region of the first and the second connecting space, and the continuations of the plates are interrupted at the position of the first and second connecting space. Other attractive preferred em¬ bodiments will be found in the following elucidation with reference to the annexed figures, in which: figure 1 shows a schematic perspective view of a heat recovery unit with a heat exchanger according to the in¬ vention; figure 2 shows a schematic perspective view of a portion of a profiled plate for use with the heat exchan¬ ger depicted in figure 1; figure 3 shows a schematic, exploded perspective view of the transition region between the profiled portion and the flat portion of the plate depicted in figure 2; figure 4 is a schematic perspective detail view of the plate depicted in figure 2; figure 5 is a schematic perspective detail view of a heat exchanger, constructed with the plates depicted in figure 4; figure 6 shows a perspective view of a portion of a plate according to a variant of the embodiment depicted in figures 1-5; figure 7 shows a perspective view of a portion of a heat exchanger constructed with the plates depicted in figure 6; figure 8 shows a detail view of a connection of the heat exchanger shown in figure 7; figure 9 shows a further elaborated detail view of the heat exchanger depicted in figure 8,- figure 10 shows a diagram of a tumble dryer, wherein two heat exchangers according to the invention are app¬ lied; figure 11 is a schematic exploded view of an inte¬ grated embodiment of such a tumble dryer,- figure 12 shows a variant of the heat exchanger de¬ picted in figure 8, wherein the connecting elements are adapted such that the heat exchanger functions as con¬ denser and recuperator; figure 13 shows an exploded view of the conden- ser/recuperator depicted in figure 9; figure 14 is a schematic perspective view of a vari¬ ant of the plate shown in figure 2; figure 15 is a schematic perspective view of a part of a heat exchanger constructed from plates shown in fig- ure 14; and figure 16 shows a schematic top view of a variant of the plate depicted in figure 2.

Shown in figure 1 is a heat exchanger 1 which is formed by plates 2, 3 stacked on each other. This configuration is particularly suitable for heat¬ ing fresh.ventilating air flowing into a house by warm ventilating air leaving the house.

The plates are formed alternately by flat plates 2 and by profiled plates 3, as will be elucidated hereinbe- low, inter alia with reference to figure 2. Figure 1 serves only to demonstrate that the heat exchanger 1 is essentially formed by plates 2,3 which are stacked on each other and; which are placed in a housing 4.

In figure 1 the housing 4 is divided on the top of the heat exchanger 1 into a first chamber 5 and a second chamber 6. The first chamber 5 is provided with a connec¬ tion 7 for supply of discharge air, while a connection 8 is arranged in the second space 6 for discharge of the fresh air. A fan 9 is furthermore arranged in the second space 6.

On the underside of the actual heat exchanger 1 the housing 4 is divided into a third space 10 and a fourth space 11. The third space 10 is provided with a connec¬ tion 12 for supply of fresh air, while the fourth space 11 is provided with a discharge connection 13 for used air. A further fan 14 'is moreover arranged in the space 11.

The air for discharge via the connecting piece 7 is guided via the space 5 to the actual heat exchanger which is formed by the plates 2,3 stacked on each other, exits therefrom into the fourth space 11 in housing 4 and is discharged by means of fan 14 and connecting piece 13.

In similar manner the fresh air is fed via connecting piece 12 to the space 10, passes through the actual heat exchanger, arrives in the second space 6 and leaves the heat exchanger via fan 9 and connection 8.

It is of course possible to make use of other config¬ urations which are more suitable for other applications and other fluids. As already stated, the actual heat exchanger is formed by plates 2,3 stacked on each other. Figure 2 shows a detail of a profiled plate 3. As shown in figure 2, the plate 3 comprises a highly profiled portion 15. This portion has in cross section a profile corrugated in V-shape, wherein it is noted that the invention is not limited to a purely V-shape,- it is also possible to use other shapes, for example a sine shape or other slightly rounded shape. On the outside the plate 3 is formed by a flat por¬ tion 16. This flat portion 16 serves respectively to dis¬ charge and supply the fluids for carrying through the V- shaped recesses which are otherwise bounded on their top side by the flat plate 2 for placing on plate 3. On its outside the plate 3 is provided with a standing edge 17 which transposes into a flat edge 18, with which the rel¬ evant plate can be adhered to the flat plate for fixing thereon.

It is noted herein that it is also useful, although not per se necessary, for the upper tips of the corrugat¬ ed portion 15 to be adhered to the flat plate to be placed thereon.

Use can be made for the adhesion of for instance vibration welding techniques although it is also possible to apply a gluing technique. According to an attractive embodiment the plates "are manufactured from a plastic which is easy to thermally deform.

Figure 2 further shows that the flat portion 16 is provided with ribs 19 and 20 respectively. The guide rib 19 serves to guide to the relevant channels the gases leaving the channels of the first sort or to be fed the¬ reto and also to maintain distance between the flat por¬ tion 16 and the flat plate 2 placed thereon. The same consideration applies for the downward directed guide ribs 20; however, these form the spacer to the flat plate 2 placed under the plate 3.

At the transition between the V-shaped corrugated portion 15 and the flat portion 16 there is a transition area 21 which is shown in more detail in figure 3. Figure 3 shows clearly how the triangular configuration trans- poses into the flat configuration via a gradual transi¬ tion area.

Finally, figure 4 shows in schematic form a complete plate 3. It is pointed out here that the plate shown in figure 4 has relatively few channels; the number of chan¬ nels is in fact much greater relative to the dimensions of the plate.

In the light of the drawings shown it will be appar¬ ent that it is quite possible with the shown configura- tion to mutually separate the two sorts of fluid flowing through the channels. Figure 4 thus shows that fluid en¬ tering on the right front side of plate 3 will remain above plate 3 "and will exit on the left rear side. The relevant space is in any case closed off on the left bot- torn side and on the right top side by the surfaces 17. The exact opposite applies for the underside of the plate.

When the plates are joined together a structure re¬ sults as shown in figure 5. Also shown here is that the plates 2 and 3 are mutually adhered on the edges 18.

Shown in figure 6 is a variant of the profile plate 3 wherein the flat portion 16 of plate 3 is shaped differ¬ ently. In the embodiments shown above it is always the case that each flat portion 16 of plates 3 is bounded on one side by a boundary surface connected to a space of the first sort and another boundary surface connected to a space of the second sor . There are therefore always two boundary surfaces per flat portion 16.

In the embodiment shown in figure 6 there is a larger but still even number of boundary surfaces. This is an attempt to make the flow resistance of the fluid flowing through the heat exchanger as small as possible. It is noted herein that at the location of the flat portions the distance between the flat plates is half this diε- tance at the location of the actual heat exchanger. In the embodiment shown in figure 6 the path which must be covered between the plates lying at a short distance is considerably shorter. There are however a greater number of boundary surfaces. A heat exchanger assembled according to this con¬ struction is shown in figure 7. Here is shown that this embodiment has three boundary surfaces of the first sort 22 as well as three boundary surfaces of the second sort 23. The path of the fluid is hereby considerably short¬ ened, this by a factor of about 3. When a greater number of boundary surfaces is used, for example 8 or 10, this effect is intensified still further.

Figure 8 shows how the heat exchanger according to the embodiment of figure 7 is connected. It can be seen here that each of the boundary surfaces of the first sort is connected to a space 24 of the first sort which is partially closed off on its top side by a surface 25. In similar manner the boundary surfaces of the second sort 23 are closed off by a space of the second sort 26 which is partially closed off by a boundary surface 27.

In figure 9 is shown how the spaces of the first sort 24 are connected to a chamber 15 of the first sort and also how the spaces of the second sort 26 are connected to the chamber 16 of the second sort. The chamber 15 of the first sort 24 and the chamber 16 of the second sort 26 are separated by a surface 28 and enclosed by a hous¬ ing 29.

Figure 10 shows a diagram of a tumble dryer. The tumble dryer designated integrally with 30 comprises a drying drum* 31, a heating element 32 and a condenser 33, as is the case in conventional tumble dryers. The tumble dryer according to the present invention is further pro¬ vided with a recuperator or heat exchanger 34. It will be apparent that use can be made for recuperator 34 of a heat exchanger according to the present invention. The diverse components are otherwise mutually connected by channels 35.

The recuperator serves herein to pre-heat the air which comes from the condenser and from which the mois¬ ture has been condensed, this with the cooling air coming from outside which is heated in the condenser and the heat of which is transferred at least partially in the recuperator to the air circulating in the tumble dryer. The amount of heat which must be supplied to the air at heating element 32 in order to obtain sufficient evapora¬ tion in drying drum 31 is hereby greatly reduced.

According to an attractive embodiment the recuperator 34 and the condenser 33 are combined into a separate unit which is shown in figure 11. Such a unit 36 is herein divided by means of a substantially vertically extending surface 37 into a condenser 33 and a recuperator or pre¬ heating unit 34. On one side the connecting piece is he¬ rein adapted to guide the cooling air heated in condenser 33 in a U-shape to recuperator 34, while the connecting piece on the other side is adapted to guide the air leav¬ ing condenser 33 in a U-shape back to pre-heater 34.

The construction of the relevant connections is shown in figure 12. It can be seen in this embodiment how the connecting pieces 25 and 27 have the same shape as con¬ necting pieces 25 and 27 of the normal embodiment of a heat exchanger shown in figure 8, but that the housing connecting thereto is provided with partitions 39 and is closed on its underside by a partition 38 in order to form the U-shaped guide.

Further shown in figure 13 is the total assembly is of all relevant parts of the combination of a heat ex¬ changer or recuperator and condenser for use in for in¬ stance a tumble dryer. In figure 14 is shown another embodiment of plates 2 and 3 which'is a varia^'nt of the plate 3 shown in figure 6. Herein the plate 3 is extended beyond the flat portion 16 of profiled plate 3 and beyond the ribs placed hereon and formed by 17 and 18. In the thus formed extension 40 are also formed ribs 41 as well as openings 42. At the corresponding locations of plate 2 recesses 42 are like¬ wise arranged in the extensions 40 thereof. It will be apparent that when the thus formed plates 2, 3 are placed onto each other the configuration results which is shown in figure 15. Substantially vertically extending channels are hereby created which fulfill the function of the space of respectively the first and second sort.

Finally, figure 16 shows an embodiment of a top view of a further embodiment of a plate 3, wherein for correct distribution of the gases flowing through the heat ex- changer the channels are embodied on one side of the heat exchanger at least partially diverging or converging, and diverging in the direction from outside toward the actual heat exchanger. Such an embodiment is of particular im- portance in the case of large temperature gradients whe¬ rein, as a result of a temperature change caused by the fluids passing through, particularly when these fluids are gaseous, a considerable change in volume can occur. In the case of normal supply means to the heat exchanger there could be an unequal distribution of the fluids over the heat exchanger which would result in reduced effec¬ tiveness thereof. It will be apparent that this embodi¬ ment is particularly suitable for heat exchangers with large temperature gradients in the order of magnitude of several hundreds of K, for example as pre-heaters in gas burners. The invention therefore extends to such combina¬ tions of gas burners and heat exchangers.

Claims

1. Heat exchanger comprising channels of the first sort and channels of the second sort, wherein the chan¬ nels extend mutually parallel, are mutually separated by walls, are substantially mutually adjacent and in section are ordered according to a regular pattern, characterized in that the heat exchanger is assembled from flat plates and profiled plates stacked alternately on each other and forming the walls, wherein the profiled plates come into contact with both adjoining flat plates and each of the plates forms a separation between channels of the first sort on a first side and channels of the second sort on the second side.

2. Heat exchanger as claimed in claim 1, character¬ ized in that the profiled plates are connected by adhe- sion to each of the adjoining flat plates.

3. Heat exchanger as claimed in claim 1 or 2, charac¬ terized in that the plates are each manufactured from plastic, for example a thermoplastic plastic.

4. Heat exchanger as claimed in claim 1, 2 or 3, which is provided on at least one side with a connecting piece, characterized in that the connecting piece com¬ prises continuations of the flat plates and substantially flat continuations of the profiled plates.

5. Heat exchanger as claimed in claim 4, character- ized in that at the connecting pieces the continuations of the flat plates and the profiled plates are equidis¬ tant.

6. Heat exchanger as claimed in claim 4 or 5, charac¬ terized in that at least one of each of the sorts of plates is provided with spacer ribs.

7. Heat exchanger as claimed in claim 6, character¬ ized in that only the profiled plates are provided with spacer ribs.

8. Heat exchanger as claimed in claim 6 or 7, charac- terized in that the spacer ribs arranged on a plate are arranged on both sides of the plate.

9. Heat exchanger as claimed in any of the claims 4- 8, characterized in that

- on at least one first connecting surface extending substantially perpendicular to the surfaces of the plates the connecting piece is coupled to a first connecting space,

- that the spaces lying between the plates and con¬ nected to channels of the second sort at the location of the coupling to the first connecting space are closed off,

- on at least one second connecting surface extending substantially perpendicular to the surfaces of the plates the connecting, piece is coupled to a second connecting space, and - the spaces lying between the plates and connected to channels of the first sort at the location of the cou¬ pling to the second connecting space are closed off.

10. Heat exchanger as claimed in claim 9, character¬ ized in that the continuations of the flat plates and the flat continuations of the profiled plates extend into the area of the first and the second connecting space, and the continuations of the plates are interrupted at the location of the first and second connecting space.

11. Heat exchanger as claimed in claim 10, character- ized in that around the first respectively second space the continuations of the flat respectively profiled plates are mutually connected.

12. Heat exchanger as claimed in claim 9, 10 or 11, characterized in that each connecting piece comprises only a first and a second connecting surface.

13. Heat exchanger as claimed in claims 6 and 9, 10, 11 or 12, characterized in that the spacer ribs are adap¬ ted as guides for the fluid for transporting through the channels.

14. Heat exchanger as claimed in any of the claims 9, 10, 11, 12 or 13, characterized in that each connecting piece comprises at least two of each of the first and second connecting surfaces.

15. Heat exchanger as claimed in any of the foregoing claims, characterized in that the dimensions of the heat exchanger are selected such that the heat exchanger can be used at least partially as condenser.

16. Combination of a heat exchanger as claimed in claim 15 with a heat exchanger as claimed in any of the claims 1-14, characterized in that both heat exchangers are coupled such that the gas for condensing is guided through the heat exchanger performing the condenser func¬ tion and is subsequently guided through the actual heat exchanger to heat a cooling medium, and that the cooling medium is supplied initially to the heat exchanger ful¬ filling the condenser function and then to the actual heat exchanger.

17. Combination as claimed in claim 16, characterized in that the heat exchanger fulfilling the condenser func- tion and the heat exchanger fulfilling the actual heat exchanger function are combined into a single unit and that the connecting pieces are adapted to guide the gas¬ es.

18. Combination as claimed in claim 17, characterized in that the combination is adapted to be built into a tumble dryer.

19. Combination as claimed in claim 17 or 18, charac¬ terized in that in the unit the heat exchanger fulfilling the condenser function and the actual heat exchanger are placed adjacently of each other in the unit, wherein each of the connecting pieces is adapted to guide the gases coming from the one heat exchanger to the other heat ex¬ changer along substantially a U-bend.

20. Combination of a gas burner and a heat exchanger as claimed in any of the claims 1-15, characterized in that the heat exchanger is adapted to pre-heat the com¬ bustion air of the burner with at least a part of the combustion gases coming from the burner.

21. Combination as claimed in claim 20, characterized in that the combination is adapted to fire with a large overmeasure of air.

22. Combination as claimed in claim 20 or 21, charac¬ terized in that the connecting pieces are adapted to dis¬ tribute the combustion gases uniformly over the sectional plane of the heat exchanger.

23. Combination as claimed in claim 22, characterized in that the connecting pieces are provided with guide ribs which are placed such that the channels diverge be¬ tween the ribs.

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