WO1996030712A1

WO1996030712A1 - Heat exchanger of the plate fin-type, comprising a removable core with jacket

Info

Publication number: WO1996030712A1
Application number: PCT/NL1996/000135
Authority: WO
Inventors: Walter Bloksma
Original assignee: Bloksma B.V.
Priority date: 1995-03-31
Filing date: 1996-04-01
Publication date: 1996-10-03
Also published as: NL9500633A; AU5125396A

Abstract

A heat exchanger comprising a core placeable into and out of a housing, which core comprises at least a series of plate-shaped fins arranged approximately parallel to each other, which series is bounded on opposite sides by an end plate, with a bundle of tubes extending through the fins and the end plates for passing therethrough a first heat exchanging medium, the housing comprising an inlet and an outlet for passing a second heat exchanging medium through the housing during use, wherein the core is at least partly enclosed by a stiffening protecting jacket.

Description

Title: Heat exchanger of the plate fin-type, comprising a removable core with jacket.

The invention relates to a heat exchanger according to the preamble of claim 1. Such heat exchangers are supplied by the firm Bloksma B.V., Almere, the Netherlands.

These known heat exchangers, which are generally designated as Plate Fin heat exchangers, are suitable in particular for use as oil cooler in, for instance, generators, engines and the like. By the use of the series of fins and the tubes extending through the core, in comparison with other heat exchangers a very compact construction with a high efficiency is obtained. In addition, because the core is removable, maintenance and inspection of the heat exchanger are possible in a simple manner.

These known heat exchangers have the disadvantage that the length and the diameter of the core can only be relatively limited in size. Otherwise, the core is not rigid enough, so that the core is no longer placeable into the housing or removable therefrom, without damage occurring. Moreover, this entails a great risk of damage to the core, in particular of the fins, during placement and removal thereof. Further, the different seals within the housing become problematic as a result. Thus, it is of great importance to prevent heat exchanging medium to be passed through the housing from flowing on the outside past the fins, from the inlet to the outlet, because as a result the efficiency of the heat exchanger is reduced. The abutment 96/00135

2 between the fins and the housing should therefore be as optimal as possible. However, if a maximum seal is aimed for, upon movement of the core, such friction develops between the fins and the housing that removal and placement of the core, given large dimensions, is no longer possible. Moreover, for the same reasons, with these known heat exchangers a very high degree of manufacturing accuracy is necessary, which renders manufacture relatively costly, in particular in the case of larger dimensions. For these reasons, the possible volume and the associated capacity of the known Plate Fin heat exchangers is limited. The maximum diameter that can be achieved with the known Plate Fin heat exchangers is of the order of magnitude of 25 cm.

The object of the invention is to provide a heat exchanger of the type described in the preamble of the main claim, whereby the above-mentioned disadvantages are avoided, while the advantages thereof are maintained. To that end, a heat exchanger according to the invention is characterized by the features according to the characterizing portion of claim 1.

Because the core in the heat exchanger according to the invention comprises a stiffening protecting jacket, in a simple manner a core is obtained which is relatively bending stiff and torsion stiff, also at relatively large cross sections and/or lengths, and moreover provides for a good protection of the fins during assembly and disassembly. Moreover, the jacket enables in a simple manner a proper fit of the core in the housing, since the jacket can more simply be given an external design such that a good guidance thereof within the housing is possible during placement or removal, for instance by guiding means between the jacket and the housing. The fins can then abut against the inside of the jacket with a proper fit, so that the edges of the series of fins no longer scrape along the housing upon displacement within the housing. Thus, damage to the core, such as for instance loosening or bending of one or more fins, and damage to the housing are prevented. During use the first heat exchanging medium, for instance cooling water, is passed through the tube bundle, while the second heat exchanging medium, for instance oil to be cooled, is passed under pressure via the inlet into the housing. The oil is forced through apertures in a first side of the jacket, between the fins and along the outside of the tubes, whereby heat is given off to the first heat exchanging medium or, conversely, is withdrawn therefrom, depending on the application of the heat exchanger. The second heat exchanging medium is thereafter passed on an opposite second side from between the fins and out of the jacket, in the direction of the outlet.

In an advantageous embodiment, the apparatus according to the invention is characterized by the features according to claim 2. By at least partly supporting the protective jacket against the housing during use, displacements of the core in the housing are prevented and damage is prevented. During use the heat exchanging medium which is passed via the inlet into the housing exerts a great pressure on the top of the core, in particular in the absence of, for instance, baffles to the described hereinafter. Given one bar of pressure difference between the top and bottom of the core, which pressure difference can easily occur and is far from extreme, in the case of a relatively small heat exchanger, already a pressure equivalent to one to a few tons is exerted on the top. As a result, the core is under a heavy load. The support against the stiff wall of the housing can easily accommodate these pressure differences, so that the core is stably maintained in position and not damaged.

It is then particularly advantageous if the jacket, while it is being slid in and out, is likewise at least partly supported against the inside of the housing. As a result, damage of the core is prevented even better. To that end, the jacket can be provided with guide strips or like means.

In a further elaboration, an apparatus according to the invention is characterized by the features according to claims 3 and 4.

The resilient means designed as strips, included between the protective jacket and the housing have as an advantage that as a result the space between the housing and the jacket is closed off simply and securely, so that leakage around the jacket is prevented. As a result, in use the second heat exchanging medium is forced to pass between the fins through the core, so that an optimum efficiency is obtained and the risk of temperature short circuiting along the jacket is prevented. In this apparatus, tolerances can be chosen to be relatively wide, while a sufficient sealing is yet provided for at all times by the resilient strips. In a particularly advantageous embodiment, a heat exchanger according to the invention is characterized by the features of claim 6 and claim 7. The enclosed space between the jacket and the wall of the housing constitutes a pressure space, in which during use an overpressure is maintained with respect to the rest of the housing. As a result, the amount of second heat exchanging medium locked in the pressure space forms, under overpressure, a good support of the jacket, which is held closely against the fins. As a consequence, leaks between the fins and the jacket are kept to a minimum. The jacket can therefore be manufactured from thin sheet material and hence occupies little space, is moreover relatively light and simple to manufacture.

The operation of the pressure space and the sealing strips can be understood as follows. In use, the second pressure medium flows under pressure into the interior of the housing and then has two flow options, that is, between the fins or along the jacket. The resistance of the core, that is, the resistance experienced by the second heat exchanging medium caused by the fins and tubes will, initially at least, be greater than the resistance offered by the strips springing in the direction of flow. Consequently, the second pressure medium will first flow under the resilient strips into the pressure spaces and then butt against the sealing means arranged on the opposite side of the pressure space. After the pressure in the pressure space has risen sufficiently, the second pressure medium will also start to flow substantially through the core and thereby press against the inside of the jacket. Since the jacket is supported from the other side, viz. by the second pressure medium locked under pressure in the pressure space, with a force that is at least as great as the force that is exerted on the inside of the jacket, the jacket remains pressed against the fins at all times and thereby provides an optimum seal. In this way, a pressure at least equal to the pressure inside the jacket is maintained in the pressure space at all times, in particular during a dynamic process of, for instance, starting up or stopping the heat exchanger or in the case of markedly changing process conditions. Even in the case of fins slightly deviating in shape, for instance unround fins, the jacket is properly pressed down, certainly when it is made from relatively thin, flexible sheet. A further advantage of these embodiments is that no specific retaining means or the like are necessary to keep the core in place.

In a further embodiment, the heat exchanger according to the invention is characterized by the features according to claim 8. As a result, the removal of the jacket is possible in a simple manner, so that maintenance of the fins and tubes in the core after removal of the core from the housing can be properly carried out. In the known Plate Fin heat exchangers, in order to pass the second pressure medium along the fins in optimum manner, in different embodiments the core is provided with at least one baffle which has a cross section substantially corresponding with the inside cross section of the housing at the point where the baffle is situated in use, a passage being formed at one end of the baffle. When using one baffle, the passage should be situated on the side of the fins remote from the inlet; if several baffles are used, the passages are situated alternately on one side and on the other of the fins. Accordingly, by the baffle or the baffles a meandering path is formed which repeatedly extends transversely to the longitudinal direction of the core, between the fins. As a result, the second pressure medium, after being supplied through the inlet, is passed hetween the fins, since it cannot pass the baffle other than through the passage. So, in the case of several baffles, the second pressure medium is passed between the fins several times.

In the known Plate Fin heat exchangers, principally two kinds of leakage occur which adversely affect the efficiency of the heat exchanger. First, the above-mentioned leaks between the fins and the housing, so that the second heat exchanging medium can flow at least partly past the fins from the inlet to the outlet. This leakage is prevented in the manner mentioned before. Second, leaks of the second heat exchanging medium between a baffle and the housing, with comparable consequences. In order to also prevent the second leakages in a Plate Fin heat exchanger of the known type, a heat exchanger according to the invention is characterized in an advantageous embodiment by the features according to claim 11.

By making use of a resilient part which provides for the seal of the baffle against the jacket, a flexible seal is obtained by which tolerances can be accommodated and moreover a good sealing can be obtained while the core can yet be slid into and out of the housing.

In an advantageous further elaboration, a heat exchanger according to the invention is characterized by the features according to claim 12, optionally in combination with the features according to claim 13.

By making use of at least the resilient properties of the material and optionally of the second heat exchanging medium as a pressure medium to press the resilient part against the wall of the housing, the extent of sealing is sufficient at all times and possibly adjusted to the pressure of the second heat exchanging medium. As a result, in each use, also when the pressure of the second pressure medium rises, an adequate sealing is obtained in a simple and secure manner. By inclusion of a spring plate between two adjoining cover plates, a pressure cahmber is enclosed in the spring plate under the springing closing part in simple manner, and open to one of the sides. In some cases, for that matter, two or more pressure chambers and/or resilient closing parts can be included, in corresponding or comparable manner. Other advantageous embodiments of heat exchangers according to the invention are described inter alia in the other claims and in the description of the drawings.

To clarify the invention, an exemplary embodiment of a heat exchanger will be described with reference to the drawings.

Fig. 1 shows a longitudinal section of a heat exchanger in closed, operational condition;

Fig. 2 shows a cover plate for a baffle for a heat exchanger according to Fig. 1;

Fig. 3 shows a spring plate for a baffle in a heat exchanger according to Fig. 1; and

Fig. 4 shows a cross section of a heat exchanger taken along the line IV-IV in Fig. 1. The heat exchanger 1 as shown in the drawing comprises a substantially cylindrical housing 2 with a core 3 included therein. The housing 2 has an inlet 5 adjacent a first end 4 and an outlet 7 on the opposite side 6. The inlet 5 and the outlet 7 can be connected to a supply pipe and a return pipe for a second heat exchanging medium, for instance oil to be cooled. In use, the housing 2 with the core 3 included therein is entirely closed, apart from the inlet 5 and the outlet 7, and the oil can be passed through the housing 2 under high pressure. It is noted that the inlet and outlet can also be positioned differently and several inlets and outlets can be arranged.

The core 3 comprises a bundle of tubes 8 extending approximately parallel to each other and in the longitudinal direction of the housing 2. Arranged at the two ends of the core 3 is an end plate 9 which is receivable with a proper fit in or against the housing 2 in sealing engagement therewith. The tubes 8 extend through the end plates, so that the ends of the tubes can be open and can be connected to, respectively, a supply and a discharge of a first heat exchanging medium, for instance water or a different cooling liquid. Arranged between the end plates 9 are a large number of fins 10 extending approximately parallel to the end plates and to each other, through which extend the tubes.

The fins 10 accordingly extend approximately at right angles to the longitudinal direction of the tubes 8 and are spaced apart a small distance (for instance, approximately a few mm. ) . The fins 10 and tubes 8 are in intimate mutual contact, for instance in that the tubes 8 are slightly flared within the fins 10, so that a good heat conduction between the fins 10 and the tubes 8 is ensured. It is noted that the fins 10 and tubes 8 can obviously be joined together for conduction in different ways. The fins 10 are all approximately identical and are made of relatively thin sheet. Each fin 10, of which Fig. 4 shows a left-hand side in front view, has an approximately circular cross section with a flattened top 11 and bottom 12. Provided across the surface in a uniform distribution are a number of holes 13, corresponding in number with the number of tubes, through which the tubes 8 can be arranged. For the purpose of simple assembly, the holes 13 are slightly greater than the cross section of the tubes 8 in the starting shape. Accordingly, the fins 10 together form an approximately flat top surface 11' and bottom surface 12' .

Arranged with a proper fit between the end plates 9 around the fins 10 is a jacket 14 (Figs. 1 and 4) . In the embodiment shown, the jacket comprises two plate parts 15 which can be connected together through lower and upper closing means 16, which will be further discussed hereinafter. Figs. 1 and 4 show in the upper part thereof a first and in the lower part thereof a second embodiment. The jacket 14 has a closed, curved part 17 on opposite sides abutting against the curved part of the series of fins 10. In the embodiment shown in the lower part of Fig. 4, each plate part 15 comprises at the upper side and underside of each curved part 17 a flange part 18 provided with a series of relatively large openings 60. The two flange parts extend approximately parallel to each other and have a width approximately corresponding with half the width of, respectively, half the top surface 11' and half the bottom surface 12'. At the free longitudinal edge remote from the curved part 17, each flange 18 comprises a series of closing strips 19 which extend approximately vertically and parallel to each other. In assembled condition of the jacket 14, the strips 19 of the two halves extend approximately parallel to each other, thereby enclosing a narrow space.

Upon placement of the two plate parts 15 around the fins 10, the free longitudinal edges end up approximately in abutment, with the closing strips 19 ending up side by side. alternately of one and the other flange. The hook-shaped closing strips 19 thus form a passage above the top surface 11 ' and under the bottom surface 12 ' , through which passage extends a closing section 20. The closing strips 19 are thereby forced apart slightly, so that the jacket parts 15 are pulled tightly against each other and/or against the fins 10. As a result, any space, and hence any leak in use between the curved part 17 of each plate member 15 and the curved part of the fins 10 is prevented or at least reduced to a minimum. The closing section 20 preferably has a rectangular cross section which is receivable with a proper fit between the strips 19 and in use can be supported against the inside of the housing 2. As a result, in use the core 3 is maintained in the desired position, also in the event of pressure fluctuations and pressure drop across the core in the housing. Owing to the closing strips 19 and the closing section 20 being straight, no spring action occurs. It is noted that the strips 19 and the closing section 20 can also have a different shape. In the embodiment shown in the upper part, the flanges 18 are relatively short and comprise adjacent the curved parts 17 curved closing strips 19. On each side the curved closing strips 19 can engage around a guiding device 43 which simultaneously forms a part of the jacket 14 and a support bridge for the core 3. The guiding device 43 comprises, in the embodiment shown, on each flange 18 an angled first guide section 44 mounted thereon, of which a first flange part 45 extends approximately radially with respect to the housing 2 and can abut against the inside of the housing 2. On the side remote from the jacket 14, above the second flange part 46 of the first guide section 44 which is mounted against the flange 18, a bridge part 47 is mounted which is held against the jacket 14 by the closing strips 19 and simultaneously holds the two jacket parts 15 mounted against the fins 10. The bridge part 47 comprises a number of bridge pieces 48 which, from section parts 49 extending in longitudinal direction above the first guide strips 44, extend obliquely upwards to a point centrally above the core, approximately centrally between the top surface 12' of the core and the inside wall of the housing. There the bridge pieces 48 are connected to a second guide section 50 extending in radial direction and approximately throughout the length of the housing, which second guide section 50 can abut against the inside of the housing 2. The bridge parts 47 formed by the bridge pieces 48, the second guide section 50 and the section parts 49 are included under a bias between the closing strips 19 of the two jacket parts 15 and thus in principle form part of the jacket 14. It is noted that the same construction can be used on both sides of the jacket.

As appears clearly from Fig. 1, each baffle, at least by the part extending in a channel 26, is locked between two ends 51, 52 of two first 45 and/or second guide sections 50 in line with each other, which simply and effectively prevents the possibility of the relevant part of the baffles 23 being pushed aside, for instance at start-up of the heat exchanger, when a large pressure difference exists between the two sides of the baffle 23.

On the outside, that is, the side of the curved part 17 of each plate member 15 remote from the fins 10 in use, there is arranged adjacent the top side and underside thereof at least one, and in the exemplary embodiment shown three, resilient strips 21. The strips 21 extend throughout the length of the jacket 14 between the two end plates, so that, during use, between the resilient strips 21, the curved part 17 of the plate member 15 and the housing 2 on opposite sides of the core 2 a pressure space 22 is enclosed, in which a part of the second heat exchaning medium can be received. The plate member 15, and hence the jacket 14, is maintained at a distance from the housing 2 by the guide sections 20, 44, 50 and the resilient strips 21, both during use and prior thereto or afterwards. This is of importance, inter alia when placing and removing the core, as will be further explained hereinafter. The free longitudinal edges 53 of the strips 21 are directed towards each other. Since the strips 21 close off the connection between the pressure spaces 22 and the rest of the volume of the housing 2, the volume of second heat exchanging medium trapped in the pressure spaces 22 cannot readily escape therefrom and will thus be subject to an excess pressure, so that the jacket 14 is kept close to the fins 10 and leakage between the fins 10 and the jacket 14 is prevented or at least limited to a minimum, also when during use high pressures and pressure differences occur. By the use of strips 21 moreover great tolerances can be permitted.

Above and under the jacket 14, between the jacket 14 and the housing 2, extends an open channel 26, through which the second heat exchanging medium can flow freely during use. In order to prevent a part or all of the second heat exchanging medium from flowing through this channel, directly from the inlet 5 to the outlet 7, a number of baffles 23 are arranged, which also extend into these channels 26. In the exemplary embodiment shown, three baffles 23 are arranged between the fins 10 and parallel thereto, at intervals relative wide with respect to the intervals between the fins 10. In the exemplary embodiment shown, each baffle 23 consists of three cover plates 24 (Fig. 2) and two spring plates 25 (Fig. 3) interposed between them. For clarity, in Figs. 2 and 3, the contour of a housing 2 is represented schematically in broken lines.

Each cover plate 24 and spring plate 25 has a basic part 31 which has approximately the same cross section as the fins 10, and therefore can be received in the jacket 14 with a proper fit. At each cover plate 24, at the top or bottom thereof, extends a closing part 27 which has a curved top 28 with a radius approximately corresponding with the radius of the inside of the housing 2. In use, the closing part 27 extends outside the flanges 18 at the top or the bottom of the jacket, into the relevant channel 26, so that the channel 26 is virtually closed off at that point. In order to allow displacement of the core 3 within the housing 2 and to be able to accommodate tolerances, the radius of the closing part 27 of the cover plates 24 is at least not greater than that of the inside of the housing.

In known Plate Fin heat exchangers, leakage of the second heat exchanging medium between the baffles and the housing is an important source of efficiency loss. In order to avoid this leakage, the spring plate 25 is included between the cover plates 24. The spring plate 25 has approximately the same outer contour as the cover plates 24, but the radius of the top 29 of the closing part 30 resiliently arranged adjacent the spring plate is slightly greater than the radius of the inside of the housing 2. The cover plates 24, at least in use, abut against the two sides of each spring plate 25 and the closing part 30 extends on the same side of the jacket 14 as the closing parts 27 of the cover plates 24.

The resilient closing part 30 of the spring plate 25 is connected to the basic part 31 in a first top corner via a narrow connection 33. The resilient closing part 30 consists of a narrow curved first strip 34 which extends from the connection 33 to a point adjacent the second top corner 35 situated opposite the first top corner 32. From there extends a second strip 36, connected to the first strip 34, to a point above the first top corner 32. The second strip 36 defines the curved top 29 of the resilient closing part 30. Enclosed between the basic part 31 and the first strip 35 is a first chamber 37 which is in open communication with the inside of the housing 2 via a narrow first passage 38. Enclosed between the first strip 34 and the second strip 36 is a second chamber 39 which is also in open communication with the inside of the housing 2 via a narrow second passage 40. The first 37 and the second chamber 39 are closed off on opposite sides by the cover plates 24. It is noted that it is also possible to include more or fewer resilient segments.

For the three baffles 23 it holds that the closing parts 27, 30 extend alternately in the upper and lower channel 26, in such a manner that between the inlet 5 and the outlet 7 a labyrinthine or meandering path extends which passes four times through the core 3, between the fins 10 and tubes 8. The shape of this path is naturally determined by inter alia the number of baffles; if more baffles are used, the meandering configuration is enhanced. At their lower end the cover plates 24 comprise closing lugs 51 which extend through the jacket in the assembled condition thereof. The cover plates are firmly pressed against the spring plate 25 by the lugs 51, which are received with a proper fit in recesses in the jacket 14, for the purpose of closing off the chambers 37, 39 and properly positioned.

A heat exchanger as shown in the drawings can be used as follows.

A core 3 is slid into the open housing 2 from one end thereof, with the strips 21 being pressed slightly in the direction of the jacket 14 and providing for a proper sealing of the core against the housing 2. The jacket 14, inasmuch as it in fact constitutes a tubular section, provides for a sufficient stiffness of the core, so that in particular undue bending and/or torsion of the core is prevented. As a result, the core 3 can have a relatively large cross section and/or length. The core 3 is guided through the first 44 and second 50 guide sections and/or reclosing section 20. Each time a baffle 23 is slid into the housing, the resilient closing part 30 of the relevant spring plate 25 is slightly compressed, with the second strip 36 being pressed slightly in the direction of the first strip 34 and/or the first strip 34 being pressed slightly in the direction of the basic part 31. The closing parts 27, 30 can then be simply moved along the inside of the housing. After the core 3 has been slid entirely into the housing 2, the housing, as stated, is entirely closed, with the exception of the inlet 5 and the outlet 7. The core 3 is secured to the housing 2, for instance via the end plates 9 and/or additional means, not shown in the drawings.

To the inlet 5 a supply pipe for, for instance, oil to be cooled is connected, and to the outlet 7 a return pipe for the cooled oil is connected. To the ends of the tubes 8, a supply pipe and a return pipe for a first heat exchanging medium, for instance cooling water, is connected, whereafter the heat exchanger can be set into operation. It is noted that the heat exchanger can also be connected the other way around.

Oil is introduced under pressure via the inlet into the housing 2 and fills the upper channel 26 up to the first baffle 23. Since it cannot move on there, it is forced through the openings 60 in the flanges 18, between the fins 10, along the tubes 8 and in the direction of the lower channel 26. In addition, initially on both sides of the core 3 the pressure space 22 is filled with oil, so that the jacket 14 is optimally supported. It gives off a part of its heat to the fins 10 which thereupon transfers the heat to the cooling water flowing through the tubes 8. The oil then flows through the passage 41 formed between the underside of the first baffle 23 and the housing 2 to the section of the heat exchanger between the first and second baffle 23, where it is forced upwards between the fins 10 and tubes 8 to the upper channel 26, again while giving off heat to the cooling water. In the same manner, the oil is forced twice more between the fins and the tubes, before it can be discharged in cooled condition via the outlet 7.

In use, the oil flows via the narrow passages 38, 40 into the first chamber 37 and the second chamber 39, respectively, with the first strip 34 and the second strip 36 being forced in the direction away from the basic part 31 against the inside of the housing 2 and an optimum sealing of the resilient closing part 30 against the housing 2 is obtained substantially through the resilient properties of the material of the spring plates. In use, the oil moreover flows into the pressure spaces 22 and is locked therein under pressure, inter alia through the position of the strips 21. Since the oil cannot leave the pressure space 22, it is subject to an excess pressure with respect to the oil on the inside of the jacket 14. As a result, a good support of the curved parts 17 of the jacket 14 is obtained, so that relatively thin sheet material can be used for the jacket 14, without the risk of deformation or damage. Moreover, in use the jacket is held against the fins, so that leakage of oil between the jacket 14 and the fins 10 is prevented or at least is limited to a minimum.

For the purpose of maintenance of the heat exchanger 1, the core 3 can be simply removed. To that end, the oil and water supply are stopped and optionally the respective supply and discharge pipes are uncoupled. Then the core 3 is detached and slid out of the housing 2 to one side. During displacement of the core in the housing, guidance of the core 3 relative to the housing 2 is exclusively obtained through the guide sections 20, 44, 50 and optionally the strips 21. The stiffening jacket 14 provides substantially for the form retention of the core 3.

Upon removal of the core 3 from the housing 2, the closing sections 20 or bridge parts 47 can be pulled away at the top and bottom, whereafter the two plate members 15 can be pulled away laterally and the fins 10 are cleared for inspection and maintenance. Assembly of the core 3 proceeds in the reverse order.

The heat exchanger 1 as shown in the drawings is for instance suitable in particular as an oil cooler in turbines, generators, engines and the like. A heat exchanger according to the invention may for instance have the following dimensions:

Diameter housing: 200 - 1000 mm; length housing: 500 - 5000 mm; power: 5 kW/°C - 1000 kW/°C

kW/°C is the power of the heat exchanger calculated according to logarithmic mean temperature difference (LMTD) between the first and second heat exchanging media. The dimensions and power outputs given are intended solely as an indication and should not be construed as being limitative. It will be clear that the invention is not in any way limited to the embodiment shown and described, which is shown only by way of illustration. Many variations and modifications are possible. Thus, more or fewer baffles can be arranged, or the baffles can be omitted, while the inlet and outlet can be arranged on opposite sides, that is, the top and bottom of the heat exchanger, so that the second heat exchanging medium flows diagonally through the housing. Furthermore, all kinds of other applications of the heat exchanger are possible, for instance for heating the second heat exchanging medium. Also, the baffles according to the invention can be used in a heat exchanger without a jacket around the core. The shape of the housing, and hence of the fins and baffles, can be one other than substantially circular, and the number of fins and tubes can obviously be adjusted as desired. These and many other modifications are considered to fall within the scope of the invention.

Claims

1. A heat exchanger comprising a core placeable into and out of a housing, which core comprises at least a series of plate-shaped fins arranged approximately parallel to each other, which series is bounded on opposite sides by an end plate, with a bundle of tubes extending through the fins and the end plates for passing therethrough a first heat exchanging medium, the housing comprising an inlet and an outlet for passing a second heat exchanging medium through the housing during use, characterized in that the core is at least partly enclosed by a stiffening protecting jacket.

2. A heat exchanger according to claim 1, characterized in that the protecting jacket during use is supported at least partly against the inside of the housing.

3. A heat exchanger according to claim 1 or 2, characterized in that resilient means are included between the jacket and the housing.

4. A heat exchanger according to claim 3, characterized in that the resilient means comprise sealing strips extending approximately in the longitudinal direction of the core, which are resiliently arranged along the jacket.

5. A heat exchanger according to any one of claims 2-4, characterized in that the resilient means comprise leaf springs.

6. A heat exchanger according to claim 4 or 5, characterized in that at least the jacket, the resilient means and the housing during use enclose at least one pressure space in which an excess pressure prevails with respect to the pressure in the core, the arrangement being such that the jacket during use is pressed in the direction of the fins at all times.

7. A heat exchanger according to any one of claims 4-6, characterized in that the resilient means designed as strips have their free longitudinal edges directed towards each other, in such a manner that heat exchanging medium present in the space enclosed between the strips is substantially locked therein by at least the strips.

8. A heat exchanger according to any one of the preceding claims, characterized in that the jacket is of divisible design, such that it can be removed from the core so as to clear the fins.

9. A heat exchanger according to claim 8, characterized in that the jacket comprises at least two parts, and at least on one side the longitudinal edges directed towards each other in assembled condition of the jacket are provided with complementary hooking means together forming a passage through which a closing section extends which can be pulled away, which closing section via the hooking means secures the jacket parts in the closed position.

10. A heat exchanger according to claim 8 or 9, characterized in that the jacket on at least one side is provided with a bridge part which connects on opposite sides adjacent a longitudinal edge of the jacket, and the bridge part in a central area comprises a guide rail which in use can abut against the inside of the housing and provides for guidance of the core in the slide-in and slide-out direction of the core.

11. A heat exchanger according to any one of the preceding claims, wherein at least one fin is designed as a baffle which has a cross section to some extent corresponding to the internal cross section of the housing at the point where the baffle is situated in use, while at least one passage has been formed, characterized in that at least a part of the circumference of the or each baffle is of resilient design, the arrangement being such that during use the resilient part of the baffle is pressed against the wall of the housing in sealing engagement therewith, while the second pressure medium can flow through the passage relatively freely.

12. A heat exchanger according to claim 11, characterized in that in use the resilient part is pressed against the wall of the housing in sealing engagement therewith.

13. A heat exchanger according to claim 11 or 12, characterized in that the or each baffle comprises at least two cover plates and a spring plate confined therebetween, while the spring plate comprises a basic part and a closing part resiliently connected therewith, while between the closing part and the basic part at least one chamber has been formed, in which during use the second heat exchanging medium can flow, in such a manner that as a result the closing part is pressed against the inside of the housing in sealing engagement therewith, the arrangmeent being such that during use the second pressure medium cannot pass the or each baffle other than via the passage.

14. A heat exchanger according to claim 12, characterized in that at least one baffle comprises at least two spring plates and at least three cover plates.

15. A heat exchanger according to claim 6 or 7 and any one of claims 11-14, characterized in that the housing has an approximately circular cross section, the fins are substantially circular with a straight top side and underside, the radius of the circular part is slightly smaller than that of the housing, the jacket has a cross section corresponding with the cross section of the fins, and each baffle is receivable within the jacket substantially with a proper fit but at least the closing part extends outside the jacket at the top or bottom, and on opposite sides of the jacket a pressure space extends.

16. A heat exchanger according to any one of claims 11-15 and claim 10, characterized in that each baffle during use can be supported on at least one side against an end of a guide rail.