EP3825636B1 - Heat exchanger and method for its production or design - Google Patents

Description

According to a first aspect, the invention relates to a method for producing or designing a heat exchanger.

A heat exchanger is a device that transfers thermal energy from one material stream to another. The substances are usually fluids, i.e. liquids or gases. Typically one of the substances is a liquid (e.g. water) and the other is a gas (usually air).

For good efficiency, the component that separates the substances must have good thermal conductivity and, in particular, a large surface area. The component is usually provided by pipe sections in which one of the substances, typically a liquid, is carried.

In order to increase the surface area or the thermal conductivity of the pipe section, it is also known from the prior art to rib the pipe or to provide it with circumferential ribs, which leads to improved energy transfer.

A typical heat exchanger has spiral finned tube sections that are bundled into compact heat exchangers. Spiral finned tubes are thin-walled, metallic tubes that have spiral or helical ribs to increase the surface area. The density of ribs is also called “rib pitch” and has a significant influence on the thermal properties.

Since the installation environments of heat exchangers vary in terms of their conditions, it is also known, depending on the application,

Combining finned tubes with a given pitch to form heat exchangers. Depending on the requirements, a (common) rib pitch can be selected for the pipe sections. Depending on the application, the fin height can also be adjusted for all finned tube sections.

Said heat exchangers of the prior art usually work sufficiently well. However, there is a constant urge to optimize the efficiency and also the manufacturing costs of such a heat exchanger.

• Erlangen beziehungsweise Erstellen von Informationen zum Wärmetauschverhalten der Rohrabschnitte auf Basis einer vorgegebenen oder gewählten Rohrabschnittsanordnung (vorzugsweise durch die Durchführung einer Simulation),
• Auswahl unterschiedlicher Rippen für die Rohrabschnitte, basierend auf besagten Informationen.

The invention relates in particular to the following steps:

• Obtaining or creating information about the heat exchange behavior of the pipe sections based on a given or selected pipe section arrangement (preferably by carrying out a simulation),
• Selection of different ribs for the pipe sections based on said information.

Variances, especially regarding the pitch, are generally known in heat exchangers with regard to the ribs; for example, as shown by the US 2006/0008394 A1 , which discloses a heat exchanger with the features in the preamble of claim 1, or the
US 2016/0376986 A1 , although these two publications come from the area of exhaust gas purification in (coal-powered) power plants, in which the fins of the finned tubes usually come from the Pipe to be rolled out. From this area of technology are evidently the DE 10 2011 118 164 A1 Coaxial tubes are also known in which the inner tube is bead-shaped in order to create spiral-like spaces between the two tube walls of the coaxial tube, with comparable beads also being known on outer tubes with flow around them, for example from JP S 57 187 589 A . Finally, ribs are evident in the field of air conditioning systems for cars DE 10 2016 100 192 A1 rolled out, in particular the last-mentioned prior art documents do not disclose pipe sections arranged next to one another which are ribbed differently, certainly not on the basis of any measurements.

It is therefore disclosed to use differently finned pipe sections to produce the heat exchanger. The sections can, for example, have a different rib pitch.

Alternatively or additionally, the ribs of the pipe sections can each have a different height.

Alternatively or additionally, the pipe sections can have ribs made of a different material.

According to the invention, the aforementioned or other parameters are selected on the basis of information that the designer or manufacturer has obtained about the heat exchange behavior of the pipe sections (particularly in the area of the fins) depending on their arrangement in the heat exchanger:
For example, pipe sections which, according to said information (for example due to their arrangement) have particularly good heat exchange behavior, can be particularly narrowly finned and/or provided with particularly high fins because it is particularly worthwhile for these pipe sections.

Pipe sections which, according to said information (for example due to their arrangement), have particularly poor heat exchange behavior, can, for example, have a lower fin density and/or fin height (in extreme cases even no fins at all) because it may not be worthwhile to use expensive fin material for said finned pipe section "to waste".

Of course, exactly the opposite finning situations are also conceivable: It could be that pipe sections that already have good heat exchange behavior are provided with less fin material than those that, according to the information obtained or created, have poor heat exchange behavior. This applies, for example, to the case where you want to achieve a particularly uniform heat exchange behavior when comparing the pipe sections (in other words, the fluids transported in the pipes should be uniformly tempered).

In this sense, at least two of the pipe sections should have different ribs compared to one another. In particular, all pipe sections can also have different ribs. Depending on the objectives and the information available, it is also possible that a pipe section is not provided with ribs at all (for example in the event that this is not worthwhile).

Taking the information into account when selecting the different ribs can, on the one hand, lead to an improved temperature transfer result (for example, by providing pipe sections with a particularly high or low rib pitch or with particularly high or flat ribs due to their arrangement), and on the other hand, it can also Cost optimization is carried out in such a way that the fin material is only used where it can be effective (whereas the more expensive fin material is minimized for other pipe sections).

The selection of the different ribs is based on information that is typically obtained or created in a previous process step.

This information preferably takes into account the pipe section arrangement (in the heat exchanger). The pipe section arrangement relates in particular to the arrangement of the pipe sections relative to one another or among each other.

Advantageously, in particular the flow direction of the fluid flowing outside the pipe sections can be taken into account.

In some applications, the arrangement of the pipe sections is dictated by the installation space or customer requirements. In other cases, a standard pipe section arrangement may be chosen or one Any, even optimized, arrangement can be made. This arrangement is then typically the basis for the information on heat exchange behavior or has a significant influence on it.

Corresponding information can be obtained by carrying out simulations (particularly computer-aided) or alternatively or additionally by carrying out tests (on real test setups).

The creation of information solely on the basis of assumptions or empirical values is also covered by the invention.

The information obtained or created therefore relates to the heat exchange behavior of the pipe sections, whereby in particular pipe sections can be determined which, in the given or selected arrangement, enable or have better heat exchange behavior or better heat transfer between the two substances or fluids.

For example, if a pipe section has relatively poor heat exchange behavior due to its arrangement (for example because it is arranged downstream in the flow direction of the external fluid), this can be taken into account when selecting the ribs of this pipe section (as described above).

To obtain the information, it has proven to be particularly advantageous if computer-aided simulations are carried out. For example, a computer program or an app can be used. For example, the specified pipe section positions can then be stored or entered in this program and based on assumptions about the flow direction of the external medium (i.e. the fluid that is located outside the pipe sections and is not currently being fed into them), knowledge can then be gained about the heat exchange behavior of the different finned pipe sections.

In particular, the simulation can initially be based on a predetermined rib height. Here, based on the results of the simulation, the rib height can then be adjusted.

Such a program can display the result of a simulation, in particular graphically, preferably color-coded. In particular, the display can show data about the simulated or calculated heat exchange behavior in the area of the finned tube sections, in particular regarding the heat flow (for example, values relating to the heat flow density can be displayed in adjusted colors).

Particularly advantageously, it can be provided that such a computer-aided simulation is compared with measurement data from a real test, and therefore the program is calibrated or calibrated with this data.

In this sense, it could be provided that real measurements are carried out in a previous process step and that these measurements are taken into account in the configuration of a computer program in a further process step (whereby a computer-aided simulation can then be carried out). This has the particular advantage that a real test does not have to be carried out for changed or future test arrangements. Rather, the computer-aided program can then be used.

The method according to the invention relates in particular to the production of a heat exchanger in the sense that, in principle, a method step could also be provided in which the differently finned pipe sections are combined to form a heat exchanger or accommodated or installed in a heat exchanger housing or similar.

Alternatively, the method according to the invention is only used for the design of a heat exchanger, for example in the event that a user only wants to determine data about the arrangement to be selected (or the ribs to be used) for a specific application (but not the heat exchanger itself but only passes on the data created about the design of the heat exchanger or the draft of the heat exchanger - internally or externally).

A heat exchanger according to the invention has at least two (differently) finned pipe sections. Of course, the heat exchanger can also have more pipe sections than two (for example four, six, eight or even more pipe sections). At least two of these must differ in terms of their ribbing.

The finned tube sections are arranged next to one another in the heat exchanger, that is to say essentially assigned to one another. Only in this case does obtaining information, for example through a simulation, make sense.

The ribbed pipe sections are preferably arranged parallel to one another. This is the typical configuration of a tube bundle in a heat exchanger and also makes it easier to obtain or creating information, for example as part of a simulation.

The finned tube sections can be assigned to completely separate finned tubes: For example, a heat exchanger can have several tube sections which are not connected to one another - at least within the heat exchanger housing.

For economic reasons, however, it makes sense that said pipe sections of the heat exchanger are brought together (at least outside of a housing), for example to enable a common inlet or outlet of the material carried in them.

In principle, the invention also includes tube sections which actually belong to the same finned tube: Even straight, parallel tube sections can, for example, be provided by a meandering overall finned tube: In this case, the individual finned tube sections are arranged straight and parallel to one another. But these are all part of the same overall finned tube. Of course, several such overall finned tubes can be provided in a heat exchanger.

A helical overall finned tube, for example, is also conceivable. Individual turns (or turn sections) can represent the pipe sections which run next to one another (and in particular essentially parallel to one another).

According to the most preferred embodiment of the invention, the pipe sections are essentially straight (their main direction of extension therefore extends along a straight line).

The pipe sections can in particular be arranged offset from one another or aligned with one another.

The base bodies of the pipe sections typically consist of copper (or another suitable metal, in particular stainless steel). The ribs can then, for example, consist of the same material (including copper) or another suitable material, in particular stainless steel (aluminum can also be used as a strip material).

Advantageously, the ribs of a pipe section are provided by more than one band (in particular by two bands or more). In this way, a finned tube section can be completed much more quickly at a given distance between two adjacent fins. On the other hand, the bands can have a higher pitch for the same amount of time (for example, with two bands, twice as high as in the prior art method, in which only one band is arranged on the finned tube).

The bands that provide the ribs are typically welded to the tube bodies using (at least) a laser.

The pipe base body of a pipe section is typically provided by an externally smooth round pipe, which is in the form of a straight line or rod-like, and which is then further processed, in particular ribbed. The finning band is then attached to the pipe base body, usually using a laser, typically in a helical shape.

According to a particularly advantageous embodiment of the invention, it is provided that the ribs of the pipe sections are compared to one another have a different height. In this sense, at least one pipe section has a different rib height than another pipe section. The rib height essentially corresponds to the width of the band that is used to create the ribs.

It can generally be assumed that the heat exchange behavior of the corresponding pipe section improves the higher the rib is designed. However, in practice there are maximum heights that should not be exceeded for stability reasons.

According to a further advantageous embodiment of the invention, it is additionally or alternatively advantageous that the ribs of the pipe sections consist of a different material. In this sense, a first pipe section can be provided which has a rib made of a first material and a second pipe section which has a rib made of a different material.

As already indicated, the rib materials can be, for example, stainless steel or copper or titanium or aluminum or similar materials.

The different materials can advantageously be a rustproof material and a non-rustproof material. In this sense, by changing the material, heat exchangers can be produced that are only equipped with stainless (more expensive) fins for areas of high humidity. In this way, expensive alloys in particular can be saved.

In principle, it is also possible for an individual pipe section to have bands made of different materials, so that the ribs of this pipe section, for example, consist of a first and consist of a second material. In this sense, another pipe section which has ribs of only one of these materials (or another material) would therefore represent a pipe section with ribs made of a different or different material in the sense of the invention.

An embodiment according to the invention is particularly advantageous in which the ribs of the pipe sections have a different pitch compared to one another. In this sense, at least one pipe section is provided with a first pitch, and another or second pipe section with a different pitch.

The pitch indicates the number of ribs per unit length (for example inches). The higher the pitch, the closer the ribs are together and the more rib material is used.

Typically, for example, a higher pitch is used for the pipe sections, which, according to the information obtained or created (due to their arrangement), have better heat exchange behavior, since the use of the fin material is more worthwhile or more efficient here.

According to a particularly advantageous embodiment of the invention, the pipe sections come from the same pipe. In particular, they were cut off from this primordial tube. This means that at least two pipe sections were still part of one pipe before a cutting process. After the separation process, for example after cutting or cutting through or similar, the pipe sections are then used separately in the heat exchanger as (separate) pipe sections.

Preferably, the pipe from which the at least two pipe sections come is already finned before a separation process occurs. This makes it easier to produce.

Particularly advantageously, it is provided that the tube is ribbed in varying ways, in particular varying gradually. This makes it particularly easy and economical to produce, since in this way pipe sections can come from or be separated from a pipe and have a different pitch to one another. The manufacturing process is kept very simple, as only one tube is actually used.

The original tube can in particular be designed to be straight or straight along its longitudinal extent. The separated pipe sections then also have a straight shape along their longitudinal extent.

For example, a (straight) pipe a few meters long can be ribbed in one piece in this way (preferably ribbed in varying degrees). A first area of the finned tube can have a first slope, a second area a second slope (possibly a third area a third slope, etc.). A separation process can then take place which separates the first area from the second (and possibly the second from the third, etc.). For example, the pipe can be cut off. If the gradient varies gradually, it naturally makes sense for each pipe section to have a constant gradient, with the gradient of the pipe sections varying in comparison to one another.

Such a varying rib pitch of the Urrohr body can be achieved in particular in that one of the Variable band guide developed by the applicant is used, which can vary the angle of attack of the band or bands during the welding process.

Regardless of the type of finning, the original tube can preferably be separated, in particular cut, evenly or into pieces of equal length. This enables the production of a bundle of pipe sections of equal length.

According to a further preferred embodiment of the invention, it is provided that at least one pipe section is not ribbed at all based on the information mentioned. In other words, based on the information obtained or created, it can be decided that it makes no sense to fin a specific pipe section, for example because it does not have any significant heat exchange behavior or something similar. In this way, a particularly large amount of rib band material can be saved.

According to a particularly advantageous embodiment of the invention, the ribs of at least one pipe section consist of at least two bands. Bands are typically welded to tube bases to produce ribs. The width of the band determines, for example, the height of the rib.

According to the invention, it is now provided according to this embodiment that the ribs of a pipe section are provided by at least two bands, which are typically designed separately (that means in this case in particular that they run parallel to one another, preferably helically). In other words, the ribs assigned to one side of the pipe section are always alternately provided by one of the bands.

This embodiment has the particular advantage that this facilitates a varying rib pitch for finning the original tube (from which the tube sections can be cut out). In practice, it is difficult to achieve a varying, in particular a gradually varying, rib pitch on a pipe if only one band is used. This embodiment thus enables a much more reliable control of the rib fastening process, which ultimately also reliably enables varying rib pitches.

In this way - as described above - for example, a finned original tube can be produced, which is then divided into several tube sections by a separation process, which can then in turn be installed in the heat exchanger, such that the individual tube sections actually have different slopes compared to one another.

Preferably, the information on the heat exchange behavior of the pipe sections can be obtained through a computer-aided simulation. For this purpose, for example, a computer program can be used, for example a computer program that can be executed on a conventional PC, a notebook, tablet, cell phone or similar. In this program, pipe sections can preferably be arranged according to certain specifications, and on the basis of this arrangement, the heat exchange behavior of these pipe sections can be calculated, taking into account the flow behavior of the fluid flowing outside the pipe sections.

The simulation can of course take into account any parameters that can be meaningfully selected for the simulation, such as the type of flowing medium, the direction of flow, condensation effects and/or a predeterminable rib height.

Advantageously, such a simulation can be offered, embedded or executed as a tool or app or similar in a CAD program. This has the advantage that the designer who operates the CAD program can directly use the information obtained via this simulation to define different ribs for different pipe sections and to specify, save or take them into account directly in the CAD program. In other words, the simulation tool is integrated into a design program. For example, the results of the simulation are displayed directly to the CAD program user, in particular color-coded to illustrate the calculated/expected heat exchange behavior of the pipe sections.

Particularly advantageously, such a computer-aided program can be calibrated, adjusted or configured at the factory or by the user by taking real measurement data into account. So a measurement can take place in an actual wind tunnel or similar, and these real results can then be taken into account to adjust, correct or calibrate the computer-based simulation.

In such an experiment, for example, data such as pressure loss of the medium as it flows through the finned tube bundle (using an inclined tube manometer) and/or the amount of condensate (using a calibrated measuring vessel and stopwatch) and/or the vapor pressure (using a Urrohr manometer) and/or air can be collected - and outlet, steam and condensate temperatures (with thermocouples) are measured and then taken into account in a simulation.

According to the invention, the underlying object is achieved by a heat exchanger according to claim 1, which therefore has the special feature that the finned tube sections are finned differently, the ribs of a finned tube section being formed by a finned band which is attached to the tube base body in a helical shape, and the heat exchanger having two or more rows of finned tube sections.

In this sense, the heat exchanger has finned tube sections which are provided with different fins. For example, the rib height can differ and/or the pitch of the ribs and/or the material of the ribs. In addition to the finned tube sections, the heat exchanger can in particular also have a housing or the like, or corresponding connections for the finned tube sections and/or for the material conducted within the finned tubes.

It should be noted at this point that all advantages and subclaims or special training explained in connection with the methods described above can of course also be transferred to the independent claim directed to a heat exchanger.

In this sense, it should only be pointed out as an example that heat exchangers are also intended to be disclosed in which the pipe sections have a different pitch and/or a different height and/or a different material compared to one another. The pipe sections can belong to the same pipe or come from the same pipe. Regardless of this, they can be designed separately - at least within the housing. For example, they can be merged outside the case (or inside) for one common connection or drain or similar. This list should be understood as explicit but not exhaustive.

Further advantages of the invention result from the subclaims, which may not be cited, as well as from the description of the figures that follows.

Fig. 1a

in einer sehr schematischen, teilgeschnittenen Seitenansicht einen Wärmetauscher mit einem in einem Gehäuse angeordneten Rippenrohrabschnittsbündel, wobei der Übersichtlichkeit halber lediglich zwei der Rippenrohrabschnitte (mit unterschiedlicher Rippensteigung) dargestellt sind,

Fig. 1b

eine sehr schematische Aufsicht auf einen Schnitt durch die in Fig. 1a dargestellte Vorrichtung, etwa gemäß den Ansichtspfeilen Ib in Fig. 1a, wobei die Rippenhöhe aller Rippenrohrabschnitte identisch ist,

Fig. 2

eine sehr schematische Ansicht des Ergebnisses einer Simulation des Wärmetauschverhaltens von vier exemplarischen Rippenrohrabschnitten in einer Aufsichtsdarstellung, etwa gemäß Fig. 1b, samt Legende,

Fig. 3

in einer Ansicht, etwa gemäß Fig. 1b, ein anderes Ausführungsbeispiel eines erfindungsgemäßen Wärmetauschers mit unterschiedlich hohen Rippen,

Fig. 4

eine sehr schematische Seitenansicht eines berippten Urrohres zur Herstellung von vier separaten Rippenrohrabschnitten,

Fig. 5

in einer sehr schematischen Darstellung vier Rohrabschnitte, welche einem gemeinsamen Rippenrohr eines ansonsten nicht dargestellten Wärmetauschers zugeordnet sind, und

Fig. 6

ein wendelartiges Rippenrohr eines Wärmetauschers eines ansonsten nicht dargestellten weiteren Ausführungsbeispiels.

The figures show:

Fig. 1a

in a very schematic, partially sectioned side view of a heat exchanger with a bundle of finned tube sections arranged in a housing, for the sake of clarity only two of the finned tube sections (with different fin pitches) are shown,

Fig. 1b

a very schematic top view of a section through the in Fig. 1a Device shown, approximately according to the view arrows Ib in Fig. 1a , where the fin height of all finned tube sections is identical,

Fig. 2

a very schematic view of the result of a simulation of the heat exchange behavior of four exemplary finned tube sections in a top view, approximately according to Fig. 1b , including legend,

Fig. 3

in one view, something like this Fig. 1b , another embodiment of a heat exchanger according to the invention with ribs of different heights,

Fig. 4

a very schematic side view of a finned original tube for producing four separate finned tube sections,

Fig. 5

in a very schematic representation, four pipe sections, which are assigned to a common finned tube of a heat exchanger that is not otherwise shown, and

Fig. 6

a helical finned tube of a heat exchanger of a further exemplary embodiment not otherwise shown.

The following description of the figures should be preceded by the fact that the same or comparable parts may be provided with identical reference numbers, sometimes with the addition of small letters or apostrophes. The same applies to the subsequent patent claims.

Fig. 1a first shows a very schematic side view of a first exemplary embodiment of a heat exchanger 10 according to the invention.

The heat exchanger 10 essentially consists of a housing 11 with an inlet 12 and an outlet 13 for a first fluid 14 flowing through the housing of the heat exchanger, which can in particular be a gas, for example air, such as smoke air or the like.

The first fluid 14 flows from the inlet 12 to the outlet 13 of the housing 11 and flows around a finned tube bundle 15 in the main flow direction H.

Such a finned tube bundle 15 typically consists of a plurality of finned tube sections 16 arranged next to one another.

According to the view Fig. 1a Two finned tube sections 16a and 16b are shown as an example, which in this exemplary embodiment are straight and arranged parallel to one another.

The main extension direction E, or the longitudinal extension of the finned tube sections 16, is aligned transversely or orthogonally to the main flow direction H of the first fluid 14. The finned tube sections 16 pass through the interior of the housing 11 transversely to the main flow direction H.

At their ends, the finned tube sections 16 are aligned with outputs 17 of the housing 11. In the area of the inputs and outputs, typically in the Fig. 1a Seals (not shown) may be arranged to seal the interior of the housing 11 from the atmosphere.

Outside the housing 11, the finned tube sections 16 can be continued as desired. For example, further tubes, in particular smooth tubes, can be connected to the finned tube sections and can further transport a second fluid 18 transported in the finned tube sections 16.

Fig. 1a The dashed line outside the housing 11 deliberately leaves open whether the channels formed by the finned tube sections 16a and 16b are brought together outside the housing 1a (as with regard to Fig. 1a indicated below the housing 11) or whether these are continued separately (as with regard to Fig. 1a indicated above the housing 11). This is not important for the main aspect of the invention. Rather, it is important that the second fluid is transported within the finned tube sections 16, whereby it is the second fluid can be, for example, a liquid such as water or the like.

The heat exchanger 10 according to the invention enables heat transfer between the first fluid 14 within the housing 11 (but outside the finned tube sections 16) and the second fluid 18 within the finned tube sections 16. In order to improve this heat exchange effect, the two finned tube sections 16 (in particular to increase the Surface of the pipe section) ribs 19.

These ribs 19 are provided by bands running helically around the respective pipe section, which bands are typically welded to the pipe section base body (in particular using lasers).

The ribs 19, or bands, can typically be made of copper or stainless steel or another suitable material. The basic tube bodies of the finned tube sections 16 usually consist of stainless steel or copper or another suitable material, in particular metal.

While the rib height h of the ribs of the two ribbed tube sections 16a and 16b is evident Fig. 1a is identical for both finned tube sections 16a and 16b, the finned tube sections 16a and 16b differ according to the invention in that they have a different fin pitch. The rib pitch essentially describes the density of the ribs, i.e. the number of ribs per unit length (for example per inch or per centimeter or similar).

Fig. 1a In this regard, it can be seen that the finned tube section 16a has a higher fin pitch than the finned tube section 16b. This has to do in particular with the fact that the finned tube section 16a is located closer to the inlet of the first fluid than the second finned tube section 16b. It is based on the assumption that the heat flow density or the heat flow behavior on the ribs 19a of the first finned tube section 16a tends to be greater than on the ribs 19b of the second finned tube section 16b.

Under this assumption, more strip material is assigned to the first finned tube section 16a (or a higher fin pitch), while in the second finned tube section 16b, from which such effective heat transfer is not expected anyway, strip material is saved (i.e. there is a smaller fin pitch).

The heat transfer takes place between the first fluid 14 and the second fluid 18, in the exemplary embodiment according to Fig. 1a For example, from the first gaseous fluid 14 to the liquid fluid 18 conducted in the finned tube sections 16. For example, the water conducted in the tubes 16 is heated by hot gas 14.

The efficiency of the heat exchanger can be increased by allocating more strip material to the finned tube section 16a and less to the finned tube section 16b (assuming that the same amount of strip material should be used as with an even distribution of the strip material between the two finned tube sections 16).

To Fig. 1a Finally, for the sake of completeness, it should be noted that the ribs 19a and 19b can be formed by only a single band. But there is also that Possibility that the ribs 19a and / or 19b are each formed by several bands, which then typically run parallel in a helical manner.

Fig. 1b For the sake of completeness, shows a very schematic, sectional top view of the device 10 Fig. 1a , approximately along the view arrows lb in Fig. 1a. Fig. 1b clearly shows that the finned tube bundle 15 consists not only of a pair of finned tube sections 16a and 16b, but typically of a larger plurality, in the case shown, namely of four exemplary finned tube sections 16a to 16d (but in practice they are actually for a finned tube bundle 15 significantly more finned tube sections are provided).

In the Fig. 1b The configuration or arrangement of finned tube sections 16 visible for the finned tube bundle 15 represents only an example of an offset arrangement of the tubes. Depending on the application, an aligned tube arrangement can of course also be provided or an aligned offset tube arrangement. In the exemplary embodiment, two rows of finned tube sections (each with two finned tube sections) are provided. In practice, however, finned tube bundles 15 actually have more rows, in particular with more tube sections than two in a row. In this respect the configuration is as per Figs. 1a and 1b can only be understood as an example.

As already mentioned Fig. 1a noted, can also be Fig. 1b see that the finned tube sections 16a and 16b (like the other finned tube sections 16c and 16d) each have the same fin height h. However, the finned tube sections 16 differ - as well Fig. 1a executed - in the rib pitch, which is shown in the top view Fig. 1b is indistinguishable. But it is in this regard It is acceptable that the finned tube section 16c should have a higher pitch than the finned tube sections 16d and 16b.

As indicated above, in the exemplary embodiment Figs. 1a and 1b the finned tube sections 16 are provided with different pitches based on information that the user himself has created based on considerations and assumptions (finned tube sections in an arrangement closer to the inlet 12 provide a more effective heat exchange).

Typically, however, simple assumptions and considerations can sometimes prove to be insufficient or incorrect, so that according to the invention it could be advantageous to base the information underlying the choice of the rib pitch not on assumptions, but on knowledge acquired through tests or simulations.

In particular, the applicant has found that a computer-aided simulation of the heat transfer behavior, in particular the heat flux density, on the fins can provide particularly meaningful information about the finning to be selected for a finned tube section:
So shows Fig. 2 a schematic representation of the result of a computer-aided simulation of the heat flux density along the fins 19 of finned tube sections 16, in a configuration approximately according to Fig. 1b . The result of the computer-aided simulation clearly shows Fig. 2 a broken window area, for example in the manner of a flow channel, with a main flow direction H being specified for the first fluid 14.

Taking various parameters into account, such as tube and fin materials (e.g. copper), surface quality of tube and/or ribs (for example smooth), the temperature, the flow velocity of the first fluid, possibly the density and/or the type of the first fluid, a (saturated) steam temperature, the consideration of possible condensation effects and/or a fundamental By taking into account the temperature coupling between a finned tube and the air, knowledge can be gained about the flow behavior outside the tubes within the framework of a simulation. This includes in particular the pressure loss but also the heat transfer and/or the temperatures in the heat exchanger in general.

Fig. 2 shows an example of the distribution of the heat flow density on the fins 19 of the four exemplary finned tube sections 16 when specifying specific parameters that are not mentioned in more detail here.

The legend, which is also shown, illustrates the hatching as heat density increases, although in practice a display uses color coding instead of hatching.

According to the result Fig. 2 It can be seen that the ribs 19a and 19c of the finned tube sections 16a and 16c (as expected) have much higher heat flux densities and are therefore more effective in heat transfer between the two fluids (inside and outside the finned tube sections) than the ribs 19b and 19d of the finned tube sections 16b and 16d.

Based on this simulation result, in order to increase effectiveness, a user could now come to the conclusion that a higher fin pitch should be provided for the finned tube sections 16a and 16c than for the finned tube sections 16b and 16d.

Instead of or in addition to the fin pitch, other finning parameters can also be changed depending on the simulation results (to achieve a more effective heat exchanger or to save strip material):
So shows Fig. 3 in a very schematic supervision, which roughly corresponds to the supervision Fig. 1b corresponds to a second embodiment 10` of a heat exchanger according to the invention. The finned tube sections 16 are according to Fig. 3 in their position identical to those according to Fig. 1b arranged in a housing 11. Instead of or in addition to a different fin pitch, the finned tube sections 16 - which can be clearly seen when viewed from above - now have different fin heights h: As the finned tube section 16a shows according to the simulation result Fig. 2 Participates particularly well in heat transfer, or supports it particularly effectively, this finned tube section 16a has now been assigned a particularly large fin height h ₁ , which is, for example, much larger than the fin height h ₂ of the finned tube section 16d following in the flow direction H. In this way, finned tube material can be saved in the finned tube section 16d, which does not participate particularly effectively in heat transfer anyway.

As the finned tube section 16b shows Fig. 2 Participates particularly little in the heat transfer, or does not have particularly good heat transfer properties due to its arrangement, is shown in the exemplary embodiment Fig. 3 In this finned tube section, finning is completely dispensed with, so that the finned tube material can be saved particularly effectively.

While the device 10 'according to Fig. 3 thus (also) different rib heights of the different ribbed tube sections 16, should at this point once again refer to the exemplary embodiment of the heat exchanger 10 according to Figs. 1a and 1b be jumped back: This is how the finned tube sections 16 clearly point there Fig. 1b an identical rib height h. However, the rib pitches of the individual ribbed tube sections 16 differ. According to a further aspect of the invention, the applicant has now developed a particularly elegant manufacturing process for such an embodiment: In this sense, shows Fig. 4 a (still connected) original tube 21 with a length I (typically a few meters), which has a gradual, variable ribbing:
A first sector 22a has a particularly high rib pitch, sector 22b has a medium rib pitch and sector 22c has a low rib pitch. The sector 22d then has no ribs at all. The ribs in this embodiment typically have an identical height h and are typically provided by more than one band. In this exemplary embodiment, the length of the sectors is I/4.

The applicant has found that such a (gradual) finning of a single original tube 21 is advantageously possible using several bands (and then also typically several lasers for welding the several bands). Such gradual finning thus allows the particularly simple production of a heat exchanger according to the invention, namely in that the in Fig. 4 shown, gradually ribbed, typically a few meters long primordial tube 21 is separated along its sector boundaries.

If the original pipe is 21 according to Fig. 4 Separated along the sector boundaries, four independent, typically straight, finned tube sections of length l/4 are created, which are then according to Fig. 1b can be installed in a corresponding heat exchanger.

At this point it should be noted that the sectoring and finning of the original tube 21 according to Fig. 4 is to be understood only as an example and in particular the sector 22d without any ribbing certainly represents a special case (which corresponds to the exemplary embodiment Fig. 1b cannot be transferred directly, since all finned tube sections 16 are finned). The heat exchanger 10 is not exactly made from the original tube 21 Figs. 1a and 1b made, but a heat exchanger, not shown, with an identical finned tube section arrangement but with Fig. 1b different ribbing (particularly different rib pitch).

Alternatively or in addition to varying the fin height and/or the fin pitch between the individual finned tube sections, the invention also includes heat exchangers whose finned tube sections have (at least partially) different materials: Since this cannot or can hardly be represented graphically, a corresponding one is used Figure omitted. It is only suggested that, for example, the ones in the Figs. 1a and 1b or 3 finned tube sections 16 shown could have different materials: For example, in Fig. 1a the rib material of the ribs 19a may be different than the rib material of the ribs 19b (but this also applies to the Figure 3 ).

In particular, the ribs of a single finned tube section (for example the finned tube section 16a according to Fig. 1a consist of several bands of different materials; In contrast, the ribs 19b of the finned tube section 16b could then only consist of one material, completely independent of whether the finned tube sections 16 have the same rib pitch and/or height).

Fig. 5 should then make it clear that the finned tube sections 16 are not as in Fig. 1a (indicated there in particular above the housing 11) must run independently of one another. Rather, they can be assigned to a common pipe or can be formed by sections of this pipe: This shows Fig. 5 that the finned tube sections 16' are all cohesive components of an overall tube 23, which, in addition to the straight finned tube sections 16', also has arcuate finned tube sections 24. Such finned tube sections, or such an entire tube 23, can in principle be used in heat exchangers, with the arrangement in a housing then of course being somewhat different from that according to Fig. 1a differs. Nevertheless, they are fundamentally suitable for guiding the second fluid 18 inside them.

A further different exemplary embodiment of an entire tube 23 'then shows Fig. 6 : Here the finned tube sections 16 belong as in Fig. 5 to a common overall tube 23`. However, in this case they are not straight, or are not aligned along a straight line in their main direction of extension, but are curved like an arc. This is due to the fact that the overall tube 23 has a substantially helical configuration. 9 is intended to make it clear that finned tube sections 16 arranged next to one another in this way (for example finned tube sections 16i, 16ii and 16iii) can also have different finning: Even if this is not visible in FIG. 9 for the sake of clarity, the rib pitch and / or or the rib height can vary. In particular, the entire tube 23 'could be ribbed similarly, as in Fig. 4 represented (i.e. gradually or continuously variable) and then converted or bent into its helical final shape. This should also be covered by the invention.

Claims (1)

1. Heat exchanger (10) having several ribbed pipe sections (16) arranged next to one another, in particular parallel to one another, wherein the ribs (16) of a ribbed pipe section (16) are formed from a ribbing band, which is attached to the basic pipe body in a helical shape, and wherein the heat exchanger (10) has two or more rows of ribbed pipe sections (16), characterised in that the ribbed pipe sections (16) are ribbed differently.

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