heat exchanger

Abstract

A heat exchanger having a housing and heat exchanger tubes, the heat exchanger tubes being disposed in an interior space of the housing, the housing having two cover plates, a hollow cylindrical outer wall having a cylindrical axis, and at least two screws, the outer wall extending between the two cover plates such that the two cover plates extend substantially perpendicular to the cylindrical axis, and the two screws axially fastening the cover plates to the outer wall.

Description

[Technical Field]

[0001] Technical Field The present invention relates to a heat exchanger having a housing and heat exchanger tubes disposed within an interior space of the housing. [Background technology]

[0002] Technical background Heat exchangers are used to transfer thermal energy from one material stream flowing through the heat exchanger tubes to another material located inside the housing, or vice versa. This process is used in many technical fields, such as air conditioning technology, cooling technology for industrial production plants, and energy technology working with liquefied gases.

[0003] For example, in the chemical and pharmaceutical industries, heat exchangers are used in which liquid nitrogen passes through the heat exchanger tubes, cooling the heat transfer medium inside the heat exchanger housing. The heat transfer medium can be used, for example, to cool a reactor. This has the advantage that the liquid nitrogen does not come into direct contact with the material being produced. This method allows for better temperature control of the production process, reduces the risk of overcooling the product mixture, and prevents excessive liquid nitrogen consumption.

[0004] When handling liquefied gases, heat exchangers are used in various places. For example, heat exchangers are used to cool or liquefy fluids, but also to heat or re-evaporate them. Fluids include gases and liquids. In particular, helium, hydrogen, argon or nitrogen are used in heat exchanger tubes.

[0005] When using heat exchangers, the heat exchanger tubes and the interior of the heat exchanger housing are often subjected to high pressures that the heat exchanger housing must withstand. For process temperatures in the low temperature range, high-alloy stainless steels are typically used, formed as seamlessly as possible for the housing and heat exchanger tubes. The individual components of the heat exchanger housing are precisely welded using state-of-the-art equipment to ensure sufficient pressure stability.

[0006] To ensure the long-term safety of the heat exchanger, the housing and heat exchanger tubes require regular maintenance. In the case of the welded housing mentioned above, this means welding the housing before maintenance and rewelding the housing after maintenance. This requires a lot of time for maintenance.

[0007] The present invention is therefore based on the aspect of providing a heat exchanger that facilitates maintenance inside the housing while at the same time providing sufficient pressure stability for a variety of applications. Summary of the Invention

[0008] Summary of the Disclosure The underlying aspects of the present disclosure are solved by a heat exchanger as set forth in the attached independent claims, wherein the housing of the heat exchanger comprises the two cover plates mentioned above, a hollow cylindrical outer wall with a cylindrical axis, and at least two screws, the outer wall extending between the cover plates and extending substantially perpendicular to the cylindrical axis, the two screws axially fastening the cover plates to the outer wall.

[0009] In contrast to heat exchangers known in the prior art, the housing of the heat exchanger according to the present invention has multiple components fastened together solely by threaded connections. No welding of the components is required, and maintenance is therefore performed by separating the components from each other by loosening the screws. This significantly reduces the time required for maintenance of the disclosed heat exchanger. At the same time, the two screws that axially fasten the cover plate to the outer wall ensure sufficient pressure stability of the housing.

[0010] Preferably, at least two screws for fastening the cover plates to the outer wall are inserted through corresponding openings in a first of the two cover plates to engage with a second cover plate, so that the cover plates fasten towards each other.

[0011] Alternatively, in a further embodiment, the outer wall is provided with a first collar and a second collar that engage screws that secure the cover plate to the outer wall.

[0012] The threaded joint can have a variety of screw configurations that maintain sufficient clamping force for the cover plate against the outer wall.

[0013] Thus, in one embodiment, each of the two screws is a through bolt that is threaded through a through hole in the second cover plate and securely fastened with a nut, which of course allows for tightening because the screw head is larger in diameter than the opening in the first cover plate.

[0014] Alternatively, in one embodiment, the screw is a threaded rod, the ends of which are fastened to the two cover plates with respective nuts. In either embodiment, the nuts may be configured as hydraulic nuts.

[0015] Alternatively, in one embodiment, one of the cover plates is provided with threads that engage the screw.

[0016] In a further embodiment, the housing has at least three screws that fasten the cover plate to the outer wall. The more screws that fasten the cover plate, the more evenly the fastening force is transmitted to the outer wall of the housing, preventing deformation of the outer wall.

[0017] In a further embodiment, the two screws are expansion bolts preloaded with tension, so that the cover plates are tightened toward each other and against the outer wall even when the heat exchanger, and therefore the material of the screws, heats up. The expansion screws are elastically expandable screws characterized by a shaft with a smaller diameter than the threaded portion of the screw and operate on the principle of a preloaded tension spring. This offers the advantage that the tension force exerted by the screws only changes slightly even when the screws are plastically deformed, for example, by heating, thus ensuring the pressure stability of the housing according to the present invention, even at different temperatures. Each tension spring is securely fixed on the cover plate with its head or nut attached.

[0018] In a further embodiment, at least one of the two threads has a defined breaking strength to protect the heat exchanger from overpressure in the housing. When the pressure in the housing exceeds a certain value, the thread breaks, allowing the pressure to escape from inside the housing. This, according to the present disclosure, improves the operational reliability of the heat exchanger.

[0019] In a further embodiment, the two cover plates and the outer wall are at least two, preferably three, separate parts that are not physically connected to each other. This simplifies maintenance even when not all parts are rigidly connected to each other. For example, in one embodiment, one of the covers is integrally connected to the outer wall, while the second cover is a separate part.

[0020] In one embodiment, a first annular groove is embedded in the surface of one of the two cover plates, and the outer wall extends axially into the first groove.

[0021] In a further embodiment, an annular first groove is embedded in the surface of each of the two cover plates, and the outer wall extends axially into each of the two first grooves, meaning that the outer wall is tightly confined between the cover plates.

[0022] In a further embodiment, the first groove, and in particular each of the two first grooves, has a substantially U-shaped cross-sectional profile in a radial plane extending from the cylindrical axis to a radius perpendicular to the cylindrical axis, it being understood that other cross-sectional profiles, such as a V-shaped cross-sectional profile or a rectangular cross-sectional profile, are also contemplated for the configuration of the first groove(s).

[0023] In one embodiment, the first groove, particularly each of the two first grooves, has two annular sidewall surfaces facing each other, and a first O-ring seal is disposed in the first groove, particularly each of the two first grooves, and the first O-ring seal is in sealing contact with a first of the two sidewall surfaces and the outer wall. In one embodiment, the first O-ring seal is in sealing contact with a first of the second sidewall surfaces, the outer wall, and a groove bottom of the groove.

[0024] In one embodiment, the O-ring seal is embedded in a first of the two sidewall surfaces of each of the two first grooves.

[0025] In one embodiment, the outer wall has a chamfered end. In one embodiment, the outer wall extends into the first groove or grooves and tapers toward the groove bottom of each groove. In embodiments with a chamfer or taper, a space is created between the sidewall surface, groove bottom, and outer wall of each first groove to receive a first O-ring seal.

[0026] In a further embodiment, a second O-ring seal is disposed in the first groove, particularly in each of the two first grooves, and the second O-ring seal is in sealing contact with the second of the two side wall surfaces and the outer wall. In addition to the first O-ring seal, the second O-ring seal is housed in the groove. In one embodiment, the second O-ring seal is embedded in the second of the two side wall surfaces of the first groove, particularly in each of the two first grooves.

[0027] An O-ring seal keeps the media tightly inside the housing.

[0028] In one embodiment, the outer wall is chamfered on two sides at the end that extends into the first groove such that the outer wall tapers toward the bottom of the first groove, thereby creating space for the first and second O-ring seals.

[0029] In one embodiment, the groove bottom of the first groove transitions further into a rounded second sidewall surface that engages the first O-ring seal, such rounding complementing the cross-sectional shape of the seal and thereby enhancing the sealing effectiveness of the O-ring seal.

[0030] In one embodiment, each rounded transition between the groove bottom and the first and / or second sidewall surfaces has a radius of curvature that is at least 1 / 3 of the diameter of the O-ring seal.

[0031] The placement of the outer wall within the groove in the cover plate further provides the advantage that leaks in the heat exchanger housing can be easily detected within the area of ​​the groove when medium flows from the interior of the housing into the space formed by the groove between the first O-ring seal and the second O-ring seal.

[0032] Thus, in one embodiment, the heat exchanger comprises a housing leak detector constructed and arranged to detect leaks in the housing during operation of the heat exchanger, the housing leak detector being in fluid communication with at least one of the two first grooves via a housing leak detector line, the housing leak detector line opening into an area of ​​the respective groove sealed by two O-ring seals.

[0033] In one embodiment, the housing leak detector is a pressure sensor. In one embodiment of the present invention, the area of ​​each first groove between two O-ring seals is at atmospheric pressure during operation of the heat exchanger. If a leak occurs, pressure in each first groove between the first O-ring seal and the second O-ring seal increases. This increase in pressure is detected by the pressure sensor.

[0034] In a further embodiment, the housing has a hollow cylindrical inner wall and the outer wall concentrically surrounds the inner wall, resulting in an annular interior of the housing. In a further embodiment, the cover plate is also annular, whereby the heat exchanger has a central passage surrounded by the inner wall, through which, for example, lines or fastening means pass.

[0035] In one embodiment, a second annular groove is recessed in a surface of one of the two cover plates, with an inner wall extending axially into the second groove. In one embodiment, a second annular groove is recessed in a surface of each of the two cover plates, with an inner wall extending axially into each of the second grooves.

[0036] It is understood that in one embodiment, the configuration of the second grooves, as well as the seal between each second groove and the outer wall, are the same as those of the first grooves, as described in the embodiment above. This is particularly true for the configuration of the housing leak detector, where in one embodiment the housing leak detector line is in fluid communication with one of the two second grooves.

[0037] In one embodiment, each of the first groove and the second groove is in fluid communication with a housing leak detector via a housing leak detector conduit.

[0038] In a further embodiment, the heat exchanger includes a heat exchanger tube leak detector constructed and arranged to detect leaks in the heat exchanger tubes during operation of the heat exchanger, the heat exchanger tube leak detector being in fluid communication with the interior of the housing via a heat exchanger tube leak detector line, and the heat exchanger tube leak detector line leading to the interior of the housing.

[0039] Preferably, the heat exchanger tube leak detector is a pressure detector or a gas sensor such as a pressure sensor or helium detector, which makes it possible to reliably determine whether the substance flowing through the heat exchanger tube has penetrated into the interior of the housing.

[0040] Heat exchangers known in the prior art are typically configured as shell-and-tube heat exchangers. In this case, a bundle of parallel tube sections carrying a first medium during operation of the heat exchanger is guided through a space containing a second medium. To this end, the first medium is distributed to the individual tubes of the bundle within the heat exchanger housing using distributors. This configuration has the disadvantage that the structure cannot withstand high pressures.

[0041] In contrast to this prior art, in one embodiment of the present invention, the heat exchanger tubes carrying the first medium are completely enclosed within the housing and are technically permanently sealed due to their construction. In one embodiment, the heat exchanger tubes are seamless, i.e., they have no longitudinal seams. In one embodiment, the heat exchanger tubes are cold-formed seamless tubes. In one embodiment, the heat exchanger tubes within the housing are completely seam-free, in particular without welds or solder joints. Such heat exchanger tubes are referred to as completely seamless.

[0042] In such a permanently technically sealed construction, the medium conveyed in the heat exchanger tubes never enters the housing due to its construction, but is conveyed only within the heat exchanger tubes within the housing.

[0043] In one embodiment, the high-pressure resistance of the structure within the housing is ensured solely by the configuration of the heat exchanger tubes. High-pressure resistance means that the heat exchanger tubes can withstand internal pressures of 300 bar or more. However, the housing itself must only withstand the pressure of the second medium. In one embodiment, the pressure of the second medium is lower than the pressure of the first medium.

[0044] In one embodiment, the heat exchanger tubes are work-hardened, non-heat treated tubes, and the manufacture of these types of heat exchanger tubes optimizes the wall thickness based on the internal pressure used.

[0045] In a further embodiment, the heat exchanger tubes pass through one of the two cover plates, particularly in a further embodiment, said passing is achieved using a cutting ring joint.

[0046] In a further embodiment, the heat exchanger tubes are helically shaped, which increases the surface area of ​​the heat exchanger tubes, allowing for particularly efficient transfer of thermal energy from the heat exchanger tubes to the medium inside the heat exchanger.

[0047] Possible materials for the heat exchanger tubes are TP316L, HP120, or HP160, especially when helium or hydrogen flows through the heat exchanger tubes in one embodiment.

[0048] BRIEF DESCRIPTION OF THE DRAWINGS Further advantages, features and possible applications of the present disclosure will become apparent from the following description of two embodiments and the associated figures, in which identical components are provided with the same reference numerals.

[0049] The foregoing general description, as well as the following detailed description of the embodiments, will be best understood when read in conjunction with the appended drawings. It is understood that the illustrated embodiments are not limited to the precise arrangements shown. [Brief explanation of the drawings]

[0050] [Figure 1a] FIG. 1a shows a schematic cross section parallel to the cylindrical axis of a first variant of the heat exchanger. [Figure 1b] FIG. 1b shows a cross section of the lower left corner of the variant shown in FIG. 1a. [Figure 2] 4 shows a schematic view of a cross section parallel to the cylindrical axis of a second variant of the heat exchanger. [Figure 3] 1 shows a schematic view of a cross section parallel to the cylindrical axis of a third variant of the heat exchanger. DETAILED DESCRIPTION OF THE INVENTION

[0051] Detailed Description The heat exchanger 1 shown in Figures 1a and 1b comprises a housing 2 and a heat exchanger tube 3 disposed within the interior 4 of the housing 2. The heat exchanger tube 3 is spirally shaped and made of TP316L or HP120.

[0052] The housing 2 is formed by two cover plates 2a, 2b and a hollow cylindrical outer wall 2c, which surround an interior 4. The hollow cylindrical outer wall 2c is cylindrically arranged around a cylindrical axis 100, to which the two cover plates 2a, 2b extend substantially perpendicularly. A heat exchanger tube 3 passes through both cover plates 2a, 2b. The two cover plates 2a, 2b and the outer wall 2c are separate components fastened together by eight screws 5a, 5b (only two screws 5a, 5b are visible in the cross-sectional view shown).

[0053] In this regard, the screws 5a, 5b are formed to pass through openings in the first cover plate 2a of the two cover plates 2a, 2b, and the diameter of the screw heads of the screws 5a, 5b is selected so that the screws 5a, 5b cannot pass completely through the openings in the first cover plate 2a. The second cover plate 2b of the two cover plates 2a, 2b has further through-openings for the screws 5a, 5b, through which the threaded portions of the screws 5a, 5b pass. The ends of the threaded portions are respectively provided with hydraulic nuts, which tighten the cover plates 2a, 2b toward each other and against the outer wall 2c. Alternatively, the screws 5a, 5b are threaded rods, the ends of which are tightened by nuts to the cover plates 2a, 2b and the outer wall 2c.

[0054] To accommodate the outer wall 2c, first grooves 21a, 21b are provided in the surfaces 20a, 20b of the cover plates 2a, 2b, respectively, and the outer wall 2c extends axially in the first grooves 21a, 21b.

[0055] By clamping the cover plates 2a, 2b to the outer wall 2c, a pressure stable housing 2 is achieved which also meets the requirements for cryogenic applications of the heat exchanger 1 while providing simplified maintenance options.

[0056] The screws 5a, 5b are preferably expansion screws that are pre-tightened in order to clamp the cover plates 2a, 2b towards each other and against the outer wall 2c, even when the heat exchanger 1 and the screws 5a, 5b are heated. Furthermore, the screws 5a, 5b have a defined breaking strength, which reliably protects the heat exchanger 1 from breaking if the pressure in the interior 4 of the housing 2 exceeds a predetermined value.

[0057] A first O-ring seal 61a, 61b and a second O-ring seal 62a, 62b are arranged in each of the first grooves 21a, 21b to seal the interior 4 of the housing 2. The first grooves 21a, 21b thereby have a substantially U-shaped cross-sectional profile in a radial plane extending between the cylindrical axis 100 and a radius 101 perpendicular to the cylindrical axis 100, so that each of the two first grooves 21a, 21b has two annular side wall surfaces 221a, 221a', 221b, 221b' facing each other. The side wall surfaces 221a, 221a', 221b, 221b' are configured such that the first O-ring seals 61a, 61b contact the first surfaces 221a, 221b of the two side wall surfaces 221a, 221a', 221b, 221b', respectively, and the second O-ring seals 62a, 62b contact the second surfaces 221a', 221b' of the two side wall surfaces 221a, 221a', 221b, 221b', respectively, so that the first and second O-ring seals 61a, 61b, 62a, 62b contact the side wall surfaces 221a, 221a', 221b, 221b' of the outer wall 2c and the first grooves 21a, 21b, respectively. 1b, the ends of the outer wall 2c are chamfered so that the first and second O-ring seals 61a, 61b, 62a, and 62b are received in the first grooves 21a and 21b. This configuration forms spaces for receiving the respective O-ring seals 61a, 61b, 62a, and 62b between the side wall surfaces 221a, 221a', 221b, and 221b', the chamfered portions of the outer wall 2c, and the groove bottoms of the grooves 21a and 21b.

[0058] To detect leaks in the housing 2, the heat exchanger 1 further comprises a housing leak detector 6, which is fluidly connected to at least one of the two first grooves 21 a, 21 b via a housing leak detector line 7, which communicates with the sealed area 8 of each groove 21 a, 21 b by two O-ring seals 61 a, 62 a and 61 b, 62 b. With this arrangement, the housing leak detector 6 detects a pressure change in the sealed area 8, for example, when a medium from the interior 4 actually enters the sealed area 8.

[0059] 1 further includes a heat exchanger tube leak detector 9 that is fluidly connected to the interior 4 via a heat exchanger tube leak detector line 10. For example, the heat exchanger tube leak detector 9 is a gas sensor that detects a particular gas within the interior 4 that has unintentionally leaked through the heat exchanger tube 3.

[0060] The heat exchanger variant shown in Figure 2 differs from the variant shown in Figures 1a and 1b in that the outer wall 2c has first and second collars 32a and 32b protruding from the outer wall 2c in the direction of the radius 101, and the screws 5a and 5b engage with the collars 32a and 32b of the outer wall 2c to pre-tighten the cover plates 2a and 2b against the outer wall 2c. The heat exchanger 1 shown in Figure 3 differs from the heat exchanger 1 shown in Figures 1a and 1b in that the housing 2 further has a hollow cylindrical inner wall 2d, which the outer wall 2c concentrically surrounds, so that the interior space 4 of the housing 2 is annular. The heat exchanger tubes 3 are wound in a spiral shape and attached to the inner wall 2d of the housing 2.

[0061] To clamp the inner wall 2d, the surfaces 20a, 20b of the two cover plates 2a, 2b each have a second groove 22a, 22b, into which the inner wall 2d extends axially. For simplicity, the seal of the inner wall 2d is not labeled. However, its structure is similar to that described for the outer wall 2c, and it also has first and second O-ring seals that contact the inner and side wall surfaces of the second grooves 22a, 22b. [Explanation of symbols]

[0062] 1 heat exchanger 2. Housing 2a, 2b Cover plates 2c Exterior wall 2d interior wall 3 Heat Exchanger Tubes 4. Interior space 5a, 5b screws 6 Housing Leak Detector 7 Housing Leak Detector Line 8 Confined Areas 9. Heat Exchanger Tube Leak Detector 10 Heat Exchanger Tube Leak Detector Line 20a, 20b Surface of cover plate 21a, 21b First groove 22a, 22b Second groove 32a, 32b Exterior wall color 61a, 61b First O-ring seal 62a, 62b Second O-ring seal 100 Cylindrical shaft 101 Radius 221a, 221b, 221a', 221b' Side wall surfaces of the first groove

Claims

1. A heat exchanger (1), comprising: Housing (2) and Heat exchanger tube (3) and A heat exchanger (1) having The heat exchanger tubes (3) are arranged in the interior space (4) of the housing (2), The housing (2) two cover plates (2a, 2b), A hollow cylindrical outer wall (2c) comprising a cylindrical shaft (100) and at least two threads (5a, 5b). and the outer wall (2c) extends between the cover plates (2a, 2b), the two cover plates (2a, 2b) extending substantially perpendicular to the cylindrical axis (100); A heat exchanger (1), characterized in that the two screws (5a, 5b) axially fasten the cover plates (2a, 2b) to the outer wall (2c).

2. 2. The heat exchanger (1) according to claim 1, wherein the two screws (5a, 5b) are pre-tightened expansion screws, whereby the two screws (5a, 5b) tighten the cover plates (2a, 2b) towards each other and against the outer wall, even when the heat exchanger (1) is heated.

3. 3. The heat exchanger (1) according to claim 1 or 2, wherein at least one of the two screws (5a, 5b) has a predetermined breaking strength to provide damage protection for the heat exchanger (1) against excessive pressure in the housing (2).

4. 4. A heat exchanger (1) according to any one of claims 1 to 3, wherein the two cover plates (2a, 2b) and the outer wall (2c) are at least two, preferably three, separate parts that are not physically connected to each other.

5. 5. The heat exchanger (1) according to claim 1, wherein annular first grooves (21 a, 21 b) are recessed in the surfaces (20 a, 20 b) of the two cover plates (2 a, 2 b), respectively, and the outer wall (2 c) extends axially into each of the two first grooves (21 a, 21 b).

6. Each of the two first grooves (21a, 21b) has a substantially U-shaped cross-sectional profile in a radial plane extending from the cylindrical axis (100) to a radius (101) perpendicular to the cylindrical axis (100), whereby preferably each of the two first grooves (21a, 21b) has two annular sidewall surfaces (221a, 221a', 221b, 221b') facing each other.

6. The heat exchanger (1) according to claim 5, further comprising: a first groove (221a, 21b) and a second groove (221b) and a second groove (221c) and a third groove (221d) and a fourth groove (221e) and a fifth groove (221f) and a fifth groove (221f) in the second groove (221f), respectively, and a first O-ring seal (61a, 61b) arranged in each of the two first grooves (21a, 21b) such that the first O-ring seal (61a, 61b) is in sealing contact with a first one of the two side wall surfaces (221a, 221a', 221b, 221b') and the outer wall (2c).

7. 7. The heat exchanger (1) according to claim 6, wherein a second O-ring seal (62a, 62b) is arranged in each of the two first grooves (21a, 21b) such that the second O-ring seal (62a, 62b) is in airtight contact with a second side wall surface (221a', 221b') of the two side wall surfaces (221a, 221', 221b, 221b') and the outer wall (2c).

8. 8. The heat exchanger (1) of claim 7, wherein the outer wall (2c) in the first groove (21a, 21b) extends tapered toward the groove bottom of the first groove, such that the first O-ring seal (21a) contacts the tapered outer wall (2c), the first side wall surface (221a, 221b) and the groove bottom, and the second O-ring seal (21b) contacts the tapered outer wall (2c), the second side wall surface (221a', 221b') and the groove bottom.

9. 9. The heat exchanger (1) according to claim 7 or 8, wherein the heat exchanger (1) comprises a housing leak detector (6) configured and arranged to detect leaks in the housing (2) during operation of the heat exchanger (1), the housing leak detector (6) being fluidly connected to at least one of the two first grooves (21 a, 21 b) via a housing leak detector line (7), the housing leak detector line (7) leading to an area (8) of each of the grooves (21 a, 21 b) sealed by the two O-ring seals (61 a, 61 b).

10. 10. The heat exchanger (1) according to any one of claims 1 to 9, wherein the housing (2) has a hollow cylindrical inner wall (2d), and the outer wall (2c) concentrically surrounds the inner wall (2d), whereby the internal space (4) of the housing (2) is annular.

11. 11. The heat exchanger (1) according to claim 10, wherein annular second grooves (22a, 22b) are recessed in the surfaces (20a, 20b) of the two cover plates (2a, 2b), respectively, and the inner wall (2d) extends axially into each of the second grooves (22a, 22b).

12. 12. The heat exchanger (1) according to claim 1, wherein the heat exchanger (1) comprises a heat exchanger tube leak detector (9), the heat exchanger tube leak detector (9) being installed and arranged to detect leaks in the heat exchanger tubes (3) during operation of the heat exchanger (1), the heat exchanger tube leak detector (9) being fluidly connected to the interior space (4) of the housing (2) via a heat exchanger tube leak detector line (10), the heat exchanger tube leak detector line (10) leading into the interior space (4).

13. 13. Heat exchanger (1) according to any one of the preceding claims, wherein the heat exchanger tubes (3) pass through at least one of the two cover plates (2a, 2b).

14. 14. The heat exchanger (1) according to any one of claims 1 to 13, wherein the heat exchanger tubes (3) are completely seamless tubes at least within the housing (2).

15. 15. The heat exchanger (1) according to any one of the preceding claims, wherein the heat exchanger tubes (3) are formed in a helical shape.

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