Heat exchanger having multiple tubes

Abstract

A heat exchanger having multiple tubes through which a first medium to be cooled can flow. At least one section of the tubes is respectively surrounded by a space or respectively one section of multiple of the tubes is arranged together in a space. A heat-absorbing second medium can flow through the space or the spaces, and wherein the tubes have a constant outer diameter at least in the section. The tubes each have, at least in at least one sub-area of the respective section, an inner diameter tapering in the direction of flow of the first medium.

Description

FIELD

[0001] The present invention relates to a heat exchanger.BACKGROUND

[0002] Heat exchangers are used to transfer thermal energy from one process medium to a second process medium. In recuperative heat exchangers, each medium has a space separated from the other medium.

[0003] A frequently used type of heat exchanger is the so-called shell-and-tube heat exchanger, in which a medium is guided through multiple parallel tubes arranged in a bundle. The second medium is guided through a space surrounding the tube bundle.

[0004] Heat exchangers are used, for example, to cool process gases at high temperatures, such as 700 to 1,500° C. In most cases, the process gases are guided through the tubes and the heat-absorbing medium is located in the space surrounding the tubes and flows around the tubes on the outside.

[0005] When the process gas cools down in the tubes, fouling can occur, which is an accumulation of deposits and contaminations on the inside of the tube. Fouling is caused by particles in the process gas or by condensing phases of the process gas on the cool inside of the tube.

[0006] The deposits are usually removed by cleaning the tubes, in which case the heat exchanger must be taken out of operation, which leads to undesirable downtimes.SUMMARY

[0007] It is therefore the object of the present invention to provide a heat exchanger in which fouling is reduced.

[0008] The heat exchanger according to the invention comprises multiple tubes through which a first medium to be cooled can flow. At least one section of the tubes is respectively surrounded by a space or respectively one section of multiple of the tubes is arranged together in a space. A heat-absorbing second medium can flow through the space or spaces, wherein the tubes have a constant outer diameter at least in the section. The invention is characterized in that the tubes each have, at least in at least one sub-area of the respective section, an inner diameter tapering in the direction of flow of the first medium.

[0009] The heat exchanger according to the invention can have the structure of a shell-and-tube heat exchanger, in which multiple tubes extend through a common space. The constant outer diameter of the tubes, at least in the section located in the common space, ensures that the second medium can flow around the tubes in a fluidically advantageous manner. At the same time, the device-related effort is kept comparatively low, since the heat exchanger according to the invention can be constructed largely like a conventional heat exchanger. In an alternative embodiment, the heat exchanger can also be configured such that each tube extends through its own space, which is annularly formed around the respective tube, for example.

[0010] The fact that the tubes initially each have an inner diameter tapering in the direction of flow of the first medium in the sub-area of the respective section means that the flow velocity of the first medium along the tube does not decrease, or decreases only slightly, even if the first medium cools and the density changes as a result, and the flow velocity does not fall below a limit velocity.

[0011] With a comparatively high flow velocity, which can thus be maintained, a high shear stress of the flow on the inside of the tube is achieved, so that the deposition of particles can be prevented or particles that have already been deposited can be detached from the wall. As a result, the comparatively high flow velocity can keep the tube largely free of deposits or even clean it.

[0012] The invention thus exploits the fact that by reducing the inner diameter of the tubes, the flow velocity of the first medium can be relatively increased and thus the reduction in flow velocity due to cooling and the resulting change in density can be counteracted.

[0013] Preferably, it is provided that the respective sub-area of a tube forms an end region of the respective section of the tube in the direction of flow of the first medium. In other words, the sub-area of a tube in which the inner diameter is tapered is located in the rear part of the tube in the direction of flow of the first medium, which rear part is located in the respective space. This has the advantage that the inner diameter is tapered in the part of the tube where the first medium has already cooled down considerably and therefore in the area where the tendency to fouling is particularly strong. Due to the tapered inner diameter with a constant outer diameter, the tube wall thickness increases in this area. However, since the inner diameter is tapered in a sub-area of the tube that is located in a comparatively cool section, the relevance of the wall thickness for the heat transfer of the already cooled first medium to the second medium is negligible.

[0014] Preferably, it is provided that the sub-area or the sub-areas of a tube in which the inner diameter is tapered have a cumulative length of between ¼ and 9 / 10 of the total length of the section.

[0015] The inner diameter of the tubes can taper continuously in the sub-area. It is also possible for the inner diameter to taper in steps in the sub-area. It may also be provided that the inner diameter tapers in the sub-area by alternately arranging tubular elements with a conically tapering inner diameter and elements with a constant inner diameter. In principle, it is also possible to use a combination of different variants of tapering the inner diameter.

[0016] In a heat exchanger according to the invention, it may be provided that an outer tube is arranged around each tube, one of the spaces being formed by each outer tube. The heat exchanger can therefore be configured in the form of a double-tube heat exchanger.

[0017] Alternatively, it may also be provided that multiple tubes are arranged in parallel in a casing tube, with the casing tube forming the space.

[0018] In the heat exchanger according to the invention, it may be provided that the tubes have a constant inner diameter in other areas that differ from the sub-area.

[0019] The material of a tube or of the tubes is selected depending on the heat-emitting medium and the heat-absorbing medium. If, for example, the heat-absorbing medium is a liquid, water or water / steam mixture, low-alloy steel, high-alloy steel and even stainless steel have proven to be advantageous tube materials. If the heat-absorbing medium is air, process gas or steam, the tube material can be low-alloy steel, high-alloy steel, and even stainless steel or a nickel-based alloy. A tube can also consist of partial sections made of different tube materials.

[0020] One embodiment of the heat exchanger according to the invention can also have a tube through which a first medium to be cooled can flow, wherein at least one section of the tube is surrounded by a space, wherein a heat-absorbing second medium can flow through the space, and wherein the tube has a constant outer diameter at least in the section, wherein the tube has, at least in a sub-area of the section, an inner diameter tapering in the direction of flow of the first medium. In this embodiment of the heat exchanger according to the invention, the other features described above can also be realized.

[0021] In the following, the invention is described in more detail with reference to the following Figures.BRIEF DESCRIPTION OF THE FIGURES

[0022] In the figures:

[0023] FIG. 1 shows a schematic sectional view of a heat exchanger according to the invention in the overall view,

[0024] FIGS. 2a to 2c show schematic sectional views of various embodiments of a sub-area of a tube of a heat exchanger according to the invention, and

[0025] FIG. 3 shows a schematic detailed view of a tube of a heat exchanger according to the invention in the form of a double tube.DETAILED DESCRIPTION

[0026] FIG. 1 shows a schematic sectional view of a heat exchanger 1 according to the invention.

[0027] The heat exchanger comprises a plurality of tubes 3, which are arranged parallel to each other. The tubes 3 pass through a space 5, which is formed by a casing tube 7. In the exemplary embodiment shown in FIG. 1, in which the tubes 3 are arranged vertically, a first medium to be cooled flows through the tubes 3 from top to bottom. In principle, a horizontal arrangement is also possible. The first medium is guided via an inlet 9 into an inlet chamber 11, flows through the tubes 3, wherein it is cooled, and then passes into an outlet chamber 13. The now cooled first medium is discharged from the heat exchanger via an outlet 15.

[0028] A second medium, which is to absorb the heat from the first medium, is guided through space 5. The second medium is introduced into space 5 through a second inlet 17 and flows therethrough to a second outlet 19. In doing so, the second medium flows in counterflow to the first medium. Depending on the heat transfer task, the second medium can alternatively flow in co-current with the first medium by being introduced into space 5 through a corresponding inlet and flowing therethrough to a corresponding outlet.

[0029] The part of the tubes 3 that is located in space 5 is referred to as section 3a. At least in this section, the tubes 3 each have a constant outer diameter A.

[0030] In a sub-area of the respective section 3a, the tubes 3 have an inner diameter i tapering in the direction of flow of the first medium. Sub-area 3b, in which the tubes 3 have a tapering inner diameter i, extends in the illustrated exemplary embodiment across, for example, approximately 50% of the total length of section 3a, which is located in space 5, wherein the respective sub-area 3b of a tube 3 respectively forms an end region of the respective section 3a of the respective tube 3. In the remaining area of the tubes 3, they each have a constant inner diameter i.

[0031] The first medium now flows through the tubes 3 and is cooled by the second medium, which is located in space 5 and flows around the tubes 3. This results in an increase in the density of the first medium, so that the flow velocity of the first medium in the tubes 3 initially decreases. In order to prevent the flow velocity of the first medium from falling below a limit velocity, the inner diameter i of the tubes 3 tapers in sub-area 3b in which the first medium has already cooled down considerably and therefore has a correspondingly reduced flow velocity. By tapering the inner diameter of the tubes, the flow velocity of the first medium is relatively increased again, so that the reduction in flow velocity caused by cooling is counteracted. This can prevent deposits from forming on the inside of the tube, as the tube velocity prevents this or particles that are deposited are carried away again.

[0032] By providing a constant outer diameter A of the tubes 3, a uniform flow around the tubes in space 5 is advantageously made possible.

[0033] FIGS. 2a to 2c show different variants of sub-areas of tubes 3 in which the inner diameter i tapers. In FIG. 2a, the inner diameteri tapers continuously in the direction of flow. FIG. 2b shows a gradual tapering. In FIG. 2c, the tapering is achieved by alternately arranged sections with conically tapering inner diameter and sections with constant inner diameter.

[0034] Depending on the application, purpose and the used first medium to be cooled, the different variants have advantages and disadvantages. For example, a stepped tapering can be produced easily and cost-effectively in terms of design, but in the case of a particle-loaded first medium, the step shapes can tend to an erosive attack or be fluidically unfavorable. A continuously tapering cross-section is fluidically more favorable, but leads to a higher effort in terms of manufacturing.

[0035] Heat exchanger 1 shown in FIG. 1 has the design of a classic shell-and-tube heat exchanger, in which parallel tubes 3 pass together through a space 5 formed by a casing tube 7. In principle, it is also possible for the heat exchanger to be configured as a double-tube heat exchanger. FIG. 3 shows a schematic sectional view of such a double tube. There, tube 3 is surrounded by an outer tube 21. The annular gap formed between tube 3 and the outer tube forms space 5 through which the second medium can flow.

[0036] Heat exchanger 1 according to the invention has the advantage that fouling on the inside of the tube can be reduced or avoided in a structurally simple manner, so that downtimes of heat exchanger 1 for cleaning the tubes 3 can be reduced.

[0037] The first medium can be a process gas or air, for example. The heat-absorbing second medium can be process gas, air, water, another liquid, steam or a mixture of water / steam. Heat exchanger 1 according to the invention can be used, for example, for cooling process gases at high temperatures, for example between 700 and 1,500° C.LIST OF REFERENCE NUMERALS1 heat exchanger

[0039] 3 tube

[0040] 3a section

[0041] 3b sub-area

[0042] 5 space

[0043] 7 casing tube

[0044] 9 inlet

[0045] 11 inlet chamber

[0046] 13 outlet chamber

[0047] 15 outlet

[0048] 17 second inlet

[0049] 19 second outlet

[0050] 21 outer tube

Examples

Embodiment Construction

[0026]FIG. 1 shows a schematic sectional view of a heat exchanger 1 according to the invention.

[0027]The heat exchanger comprises a plurality of tubes 3, which are arranged parallel to each other. The tubes 3 pass through a space 5, which is formed by a casing tube 7. In the exemplary embodiment shown in FIG. 1, in which the tubes 3 are arranged vertically, a first medium to be cooled flows through the tubes 3 from top to bottom. In principle, a horizontal arrangement is also possible. The first medium is guided via an inlet 9 into an inlet chamber 11, flows through the tubes 3, wherein it is cooled, and then passes into an outlet chamber 13. The now cooled first medium is discharged from the heat exchanger via an outlet 15.

[0028]A second medium, which is to absorb the heat from the first medium, is guided through space 5. The second medium is introduced into space 5 through a second inlet 17 and flows therethrough to a second outlet 19. In doing so, the second medium flows in count...

FIELD

[0001] The present invention relates to a heat exchanger.BACKGROUND

[0002] Heat exchangers are used to transfer thermal energy from one process medium to a second process medium. In recuperative heat exchangers, each medium has a space separated from the other medium.

[0003] A frequently used type of heat exchanger is the so-called shell-and-tube heat exchanger, in which a medium is guided through multiple parallel tubes arranged in a bundle. The second medium is guided through a space surrounding the tube bundle.

[0004] Heat exchangers are used, for example, to cool process gases at high temperatures, such as 700 to 1,500° C. In most cases, the process gases are guided through the tubes and the heat-absorbing medium is located in the space surrounding the tubes and flows around the tubes on the outside.

[0005] When the process gas cools down in the tubes, fouling can occur, which is an accumulation of deposits and contaminations on the inside of the tube. Fouling is caused by particles in the process gas or by condensing phases of the process gas on the cool inside of the tube.

[0006] The deposits are usually removed by cleaning the tubes, in which case the heat exchanger must be taken out of operation, which leads to undesirable downtimes.SUMMARY

[0007] It is therefore the object of the present invention to provide a heat exchanger in which fouling is reduced.

[0008] The heat exchanger according to the invention comprises multiple tubes through which a first medium to be cooled can flow. At least one section of the tubes is respectively surrounded by a space or respectively one section of multiple of the tubes is arranged together in a space. A heat-absorbing second medium can flow through the space or spaces, wherein the tubes have a constant outer diameter at least in the section. The invention is characterized in that the tubes each have, at least in at least one sub-area of the respective section, an inner diameter tapering in the direction of flow of the first medium.

[0009] The heat exchanger according to the invention can have the structure of a shell-and-tube heat exchanger, in which multiple tubes extend through a common space. The constant outer diameter of the tubes, at least in the section located in the common space, ensures that the second medium can flow around the tubes in a fluidically advantageous manner. At the same time, the device-related effort is kept comparatively low, since the heat exchanger according to the invention can be constructed largely like a conventional heat exchanger. In an alternative embodiment, the heat exchanger can also be configured such that each tube extends through its own space, which is annularly formed around the respective tube, for example.

[0010] The fact that the tubes initially each have an inner diameter tapering in the direction of flow of the first medium in the sub-area of the respective section means that the flow velocity of the first medium along the tube does not decrease, or decreases only slightly, even if the first medium cools and the density changes as a result, and the flow velocity does not fall below a limit velocity.

[0011] With a comparatively high flow velocity, which can thus be maintained, a high shear stress of the flow on the inside of the tube is achieved, so that the deposition of particles can be prevented or particles that have already been deposited can be detached from the wall. As a result, the comparatively high flow velocity can keep the tube largely free of deposits or even clean it.

[0012] The invention thus exploits the fact that by reducing the inner diameter of the tubes, the flow velocity of the first medium can be relatively increased and thus the reduction in flow velocity due to cooling and the resulting change in density can be counteracted.

[0013] Preferably, it is provided that the respective sub-area of a tube forms an end region of the respective section of the tube in the direction of flow of the first medium. In other words, the sub-area of a tube in which the inner diameter is tapered is located in the rear part of the tube in the direction of flow of the first medium, which rear part is located in the respective space. This has the advantage that the inner diameter is tapered in the part of the tube where the first medium has already cooled down considerably and therefore in the area where the tendency to fouling is particularly strong. Due to the tapered inner diameter with a constant outer diameter, the tube wall thickness increases in this area. However, since the inner diameter is tapered in a sub-area of the tube that is located in a comparatively cool section, the relevance of the wall thickness for the heat transfer of the already cooled first medium to the second medium is negligible.

[0014] Preferably, it is provided that the sub-area or the sub-areas of a tube in which the inner diameter is tapered have a cumulative length of between ¼ and 9 / 10 of the total length of the section.

[0015] The inner diameter of the tubes can taper continuously in the sub-area. It is also possible for the inner diameter to taper in steps in the sub-area. It may also be provided that the inner diameter tapers in the sub-area by alternately arranging tubular elements with a conically tapering inner diameter and elements with a constant inner diameter. In principle, it is also possible to use a combination of different variants of tapering the inner diameter.

[0016] In a heat exchanger according to the invention, it may be provided that an outer tube is arranged around each tube, one of the spaces being formed by each outer tube. The heat exchanger can therefore be configured in the form of a double-tube heat exchanger.

[0017] Alternatively, it may also be provided that multiple tubes are arranged in parallel in a casing tube, with the casing tube forming the space.

[0018] In the heat exchanger according to the invention, it may be provided that the tubes have a constant inner diameter in other areas that differ from the sub-area.

[0019] The material of a tube or of the tubes is selected depending on the heat-emitting medium and the heat-absorbing medium. If, for example, the heat-absorbing medium is a liquid, water or water / steam mixture, low-alloy steel, high-alloy steel and even stainless steel have proven to be advantageous tube materials. If the heat-absorbing medium is air, process gas or steam, the tube material can be low-alloy steel, high-alloy steel, and even stainless steel or a nickel-based alloy. A tube can also consist of partial sections made of different tube materials.

[0020] One embodiment of the heat exchanger according to the invention can also have a tube through which a first medium to be cooled can flow, wherein at least one section of the tube is surrounded by a space, wherein a heat-absorbing second medium can flow through the space, and wherein the tube has a constant outer diameter at least in the section, wherein the tube has, at least in a sub-area of the section, an inner diameter tapering in the direction of flow of the first medium. In this embodiment of the heat exchanger according to the invention, the other features described above can also be realized.

[0021] In the following, the invention is described in more detail with reference to the following Figures.BRIEF DESCRIPTION OF THE FIGURES

[0022] In the figures:

[0023] FIG. 1 shows a schematic sectional view of a heat exchanger according to the invention in the overall view,

[0024] FIGS. 2a to 2c show schematic sectional views of various embodiments of a sub-area of a tube of a heat exchanger according to the invention, and

[0025] FIG. 3 shows a schematic detailed view of a tube of a heat exchanger according to the invention in the form of a double tube.DETAILED DESCRIPTION

[0026] FIG. 1 shows a schematic sectional view of a heat exchanger 1 according to the invention.

[0027] The heat exchanger comprises a plurality of tubes 3, which are arranged parallel to each other. The tubes 3 pass through a space 5, which is formed by a casing tube 7. In the exemplary embodiment shown in FIG. 1, in which the tubes 3 are arranged vertically, a first medium to be cooled flows through the tubes 3 from top to bottom. In principle, a horizontal arrangement is also possible. The first medium is guided via an inlet 9 into an inlet chamber 11, flows through the tubes 3, wherein it is cooled, and then passes into an outlet chamber 13. The now cooled first medium is discharged from the heat exchanger via an outlet 15.

[0028] A second medium, which is to absorb the heat from the first medium, is guided through space 5. The second medium is introduced into space 5 through a second inlet 17 and flows therethrough to a second outlet 19. In doing so, the second medium flows in counterflow to the first medium. Depending on the heat transfer task, the second medium can alternatively flow in co-current with the first medium by being introduced into space 5 through a corresponding inlet and flowing therethrough to a corresponding outlet.

[0029] The part of the tubes 3 that is located in space 5 is referred to as section 3a. At least in this section, the tubes 3 each have a constant outer diameter A.

[0030] In a sub-area of the respective section 3a, the tubes 3 have an inner diameter i tapering in the direction of flow of the first medium. Sub-area 3b, in which the tubes 3 have a tapering inner diameter i, extends in the illustrated exemplary embodiment across, for example, approximately 50% of the total length of section 3a, which is located in space 5, wherein the respective sub-area 3b of a tube 3 respectively forms an end region of the respective section 3a of the respective tube 3. In the remaining area of the tubes 3, they each have a constant inner diameter i.

[0031] The first medium now flows through the tubes 3 and is cooled by the second medium, which is located in space 5 and flows around the tubes 3. This results in an increase in the density of the first medium, so that the flow velocity of the first medium in the tubes 3 initially decreases. In order to prevent the flow velocity of the first medium from falling below a limit velocity, the inner diameter i of the tubes 3 tapers in sub-area 3b in which the first medium has already cooled down considerably and therefore has a correspondingly reduced flow velocity. By tapering the inner diameter of the tubes, the flow velocity of the first medium is relatively increased again, so that the reduction in flow velocity caused by cooling is counteracted. This can prevent deposits from forming on the inside of the tube, as the tube velocity prevents this or particles that are deposited are carried away again.

[0032] By providing a constant outer diameter A of the tubes 3, a uniform flow around the tubes in space 5 is advantageously made possible.

[0033] FIGS. 2a to 2c show different variants of sub-areas of tubes 3 in which the inner diameter i tapers. In FIG. 2a, the inner diameteri tapers continuously in the direction of flow. FIG. 2b shows a gradual tapering. In FIG. 2c, the tapering is achieved by alternately arranged sections with conically tapering inner diameter and sections with constant inner diameter.

[0034] Depending on the application, purpose and the used first medium to be cooled, the different variants have advantages and disadvantages. For example, a stepped tapering can be produced easily and cost-effectively in terms of design, but in the case of a particle-loaded first medium, the step shapes can tend to an erosive attack or be fluidically unfavorable. A continuously tapering cross-section is fluidically more favorable, but leads to a higher effort in terms of manufacturing.

[0035] Heat exchanger 1 shown in FIG. 1 has the design of a classic shell-and-tube heat exchanger, in which parallel tubes 3 pass together through a space 5 formed by a casing tube 7. In principle, it is also possible for the heat exchanger to be configured as a double-tube heat exchanger. FIG. 3 shows a schematic sectional view of such a double tube. There, tube 3 is surrounded by an outer tube 21. The annular gap formed between tube 3 and the outer tube forms space 5 through which the second medium can flow.

[0036] Heat exchanger 1 according to the invention has the advantage that fouling on the inside of the tube can be reduced or avoided in a structurally simple manner, so that downtimes of heat exchanger 1 for cleaning the tubes 3 can be reduced.

[0037] The first medium can be a process gas or air, for example. The heat-absorbing second medium can be process gas, air, water, another liquid, steam or a mixture of water / steam. Heat exchanger 1 according to the invention can be used, for example, for cooling process gases at high temperatures, for example between 700 and 1,500° C.LIST OF REFERENCE NUMERALS1 heat exchanger

[0039] 3 tube

[0040] 3a section

[0041] 3b sub-area

[0042] 5 space

[0043] 7 casing tube

[0044] 9 inlet

[0045] 11 inlet chamber

[0046] 13 outlet chamber

[0047] 15 outlet

[0048] 17 second inlet

[0049] 19 second outlet

[0050] 21 outer tube

Examples

Embodiment Construction

[0026]FIG. 1 shows a schematic sectional view of a heat exchanger 1 according to the invention.

[0027]The heat exchanger comprises a plurality of tubes 3, which are arranged parallel to each other. The tubes 3 pass through a space 5, which is formed by a casing tube 7. In the exemplary embodiment shown in FIG. 1, in which the tubes 3 are arranged vertically, a first medium to be cooled flows through the tubes 3 from top to bottom. In principle, a horizontal arrangement is also possible. The first medium is guided via an inlet 9 into an inlet chamber 11, flows through the tubes 3, wherein it is cooled, and then passes into an outlet chamber 13. The now cooled first medium is discharged from the heat exchanger via an outlet 15.

[0028]A second medium, which is to absorb the heat from the first medium, is guided through space 5. The second medium is introduced into space 5 through a second inlet 17 and flows therethrough to a second outlet 19. In doing so, the second medium flows in count...

Claims

1-10. (canceled)11. A heat exchanger having multiple tubes through which a first medium to be cooled can flow, wherein at least one section of the tubes is respectively surrounded by a space or respectively one section of multiple of the tubes is arranged together in a space, wherein a heat-absorbing second medium can flow through the space or the spaces, and wherein the tubes have a constant outer diameter at least in the section,wherein the tubes each have, at least in at least one sub-area of the respective section, an inner diameter tapering in the direction of flow of the first medium.

12. The heat exchanger according to claim 11, wherein the respective sub-area of a tube forms an end region of the respective section of the tube in the direction of flow of the first medium.

13. The heat exchanger according to claim 11, wherein the sub-area or the sub-areas has / have a length which is between 25% and 90% of a total length of the section.

14. The heat exchanger according to claim 11, wherein the inner diameter in the sub-area tapers continuously.

15. The heat exchanger according to claim 11, wherein the inner diameter in the sub-area tapers in steps.

16. The heat exchanger according to claim 11, wherein the inner diameter tapers by alternately arranging sub-areas with conically tapering inner diameters and elements with a constant inner diameter.

17. The heat exchanger according to claim 11, wherein an outer tube is arranged around each tube, one of the spaces being formed by each outer tube.

18. The heat exchanger according to claim 11, wherein multiple tubes are arranged in parallel in a casing tube, with the casing tube forming the space.

19. The heat exchanger according to claim 11, wherein the tubes have a constant inner diameter in other areas different from the sub-area.

20. A heat exchanger having a tube through which a first medium to be cooled can flow, wherein at least one section of the tube is surrounded by a space, wherein a heat-absorbing second medium can flow through the space, and wherein the tube has a constant outer diameter at least in the section,wherein the tube has, in at least one sub-area of the section, an inner diameter tapering in the direction of flow of the first medium.

Images