BE1016887A3 - Heat exchanger, has flow channels for second medium defined by profiles with interlocking length direction ribs - Google Patents

Abstract

The profiles (10) defining internal flow channels for a second medium have length direction ribs (13) on the outside so that the ribs on adjoining profiles interlock with each other. Narrow passages each having approximately the same hydraulic diameter are formed between the ribs. The heat exchanger comprises a mantle (2) which defines an enclosed space (3) with an inlet opening and an outlet opening. This space acts as a flow channel (18) for a first medium. Each profile defines a flow channel for the second medium and these profiles form two or more heat exchange elements located in the enclosed space. The two media flow (substantially) parallel to each other through the heat exchanger.

Description

Improved longitudinal flow heat exchanger.

The present invention relates to an improved longitudinal flow heat exchanger.

More specifically, the present invention relates to a longitudinal flow heat exchanger which is provided with a jacket defining an enclosed space with an inlet opening and an outlet opening for a first fluid and with two or more heat exchange elements which are arranged in the above-mentioned jacket and which are designed in the shape of hollow profiles arranged next to each other, each defining an internal channel that forms a passage for a second fluid.

By "longitudinal flow" is here meant that the direction of flow of the heat exchanging media is parallel or substantially parallel to each other.

This should therefore be understood to mean both heat exchangers with an equal flow sense of the fluids or so-called direct current heat exchangers, and heat exchangers in which the flow sense of the fluids is opposite or so-called counter-flow heat exchangers.

The operation of such known heat exchangers is well-known, in which a first fluid flows along the aforementioned supply and outlet opening and through the aforementioned jacket and along the aforementioned profiles, while a second fluid flows through the channels in the profiles, such as that a heat transfer takes place between the first and the second fluid.

It is known that, in order to improve the heat transfer between the two fluids, cooling ribs are provided in the channels on the respective inner walls of the aforementioned heat exchange elements.

Since the flow area of the aforementioned channels is hereby limited, for example, when a gas to be cooled is sent through these channels, the gas velocity through each of these respective channels will be relatively high.

This has the disadvantage that, in order to nevertheless obtain a sufficient capacity of the heat exchanger, a relatively large number of such profiles must be provided in order to keep the overall gas speed at an acceptable level, whereby the cost price of such heat exchangers increases and the assembly takes more time.

A further drawback of such known heat exchangers is that, for example when water is passed through the jacket along the aforementioned profiles, the flow rate of this water is usually very low, as a result of which problems occur with limescale or the like.

In order to improve the heat transfer to some extent and to obtain a certain form of countercurrent, in the known longitudinal flow heat exchangers, reversing plates are often also provided in the heat exchanger which oblige the fluid to perform a zigzag movement, so that the construction of the heat exchanger is still becomes more complex and takes more time to assemble.

An additional disadvantage of heat exchangers with such reversing plates is that they lead to a pressure drop and the presence of "dead zones" where the flow rate of the fluid is practically zero and where precipitation of suspended particles such as sand, lime and the like can take place, which can adversely affects heat exchange.

From GB 637.235, for example, it is also known to provide ribs on the outer walls of the aforementioned profiles, such that the ribs of heat exchange elements placed next to each other form external flow channels with a substantially hexagonal cross-section, whereby a so-called honeycomb structure is obtained around each of the aforementioned internal channels.

A major disadvantage of such known heat exchangers is that, for example, when they are mounted in a cylindrical shell, no full filling of this shell is possible and irregular flow surfaces are obtained around each of the aforementioned heat exchange elements, whereby "leakage currents" are created between the hexagonal channels and the jacket that does not participate in the heat transfer between the fluids.

In addition, the increase in the heat exchanging surface on the outside of the respective profiles is still limited.

Finally, cross-flow heat exchangers are also known in which the flow directions of the heat-exchanging fluids intersect, which heat exchangers exhibit poorer efficiency and must therefore be made larger in order to be able to realize the same heat exchange as known longitudinal-flow heat exchangers which are placed in counter-flow.

The present invention has for its object to provide a solution for one or more of the aforementioned and other disadvantages.

To this end, the present invention relates to an improved longitudinal flow heat exchanger which is provided with a casing that defines an enclosed space with an inlet opening and an outlet opening, which space serves wholly or partly as a flow channel for a first fluid and of two or more heat exchange elements which in the aforementioned space are provided and which are in the form of hollow profiles arranged next to each other, each defining an internal channel that forms a passage for a second fluid, longitudinally oriented ribs being provided on the outer sides of the aforementioned profiles such that ribs of adjacent profiles interlocking, whereby narrow passages are formed between the respective ribs, each having substantially the same hydraulic diameter.

The hydraulic diameter is a known quantity which is defined as follows dh = (4 A) / P, where in this case: dh = the hydraulic diameter of a respective passage, expressed in meters; A = the flow area of a respective passage, expressed in square meters; and P = the circumference of a respective passage, expressed in meters.

Since with an improved longitudinal flow heat exchanger according to the invention the hydraulic diameter of each of the respective narrow passages is substantially the same, a very even distribution of the fluids can be realized, in contrast to the known heat exchangers, for example as described in GB 637.235.

This has the advantage that the formation of leakage currents in the heat exchanger is prevented, as a result of which the efficiency of the heat exchanger improves considerably compared to the traditional heat exchangers.

Another advantage of an improved longitudinal flow heat exchanger according to the invention is that, since the aforementioned ribs engage on the outer walls of the profiles, it is possible to have these profiles connect very closely to each other, whereby a large heat-exchanging surface is obtained without this increases the total volume of the heat exchanger.

Another advantage of such an improved heat exchanger is that the shape of the profiles allows the above-mentioned flow channel through the casing for the first fluid to be filled almost completely with profiles, whereby a large heat-exchanging surface can be realized with a relatively small heat exchanger and consequently a high efficiency can be achieved without a large pressure drop being created, such as, for example, when using reversing plates.

Another additional advantage of an improved heat exchanger according to the invention is that it allows to be used in counter-current, in contrast to conventional cross-flow heat exchangers.

In a preferred embodiment of an improved longitudinal flow heat exchanger, the aforementioned profiles are formed by extrusions.

This has the advantage that such an improved heat exchanger according to the invention can be manufactured in a very simple, fast and inexpensive manner, without having to use cumbersome and expensive connection techniques such as welding, brazing or the like.

With a better understanding of the features of the present invention, some preferred embodiments of an improved longitudinal flow heat exchanger according to the invention are shown below as an example without any limiting character with reference to the accompanying drawings, in which: figure 1 shows a schematic cross-section of an improved represents a longitudinal flow heat exchanger according to the invention; figure 2 shows on a larger scale the part which is indicated in figure 1 by arrow F2; figure 3 represents a section according to line III-III in figure 1; figure 4 represents a variant of a heat exchanger according to figure 1; figure 5 represents a section according to line V-V in figure 4; figures 6 to 11 show variants according to figures 1 and 2; figure 12 shows on a larger scale the part which is indicated in figure 10 by arrow F12; figure 13 represents another variant of an improved heat exchanger according to figure 3; Figure 14 shows yet another embodiment of an improved longitudinal flow heat exchanger according to Figure 1.

Figures 1 to 3 show an improved longitudinal flow heat exchanger 1 according to the invention, which essentially consists of a, in this case, cylindrical casing 2 that encloses a space 3 which is closed on both sides by means of an end wall 4.

In each of the aforementioned end walls 4 an opening is provided which respectively forms an inlet opening 5 or an outlet opening 6 for the aforementioned space 3.

Near each of the aforementioned end walls 4, a plate 7 is also provided in the aforementioned casing 2 in which a large, central passage opening 8 is provided which is connected by means of a tube to the aforementioned inlet opening 5 or to the outlet opening 6.

A number of smaller openings 9 are also provided in the aforementioned plates 7, which openings are arranged around the aforementioned opening 8 at fixed intervals and which, in this case, are all at an equal distance with respect to the aforementioned opening 8.

Heat exchanger elements in the form of extruded, hollow profiles 10 are arranged between the aforementioned plates 7 and are directed in accordance with, or substantially in accordance with, the longitudinal direction of the casing 2 and which define an internal channel 11 which at its both ends opens onto an opening 9 of a respective plate 7, all such that annular spaces 12 between the plates 7 and the end walls 4, which spaces 12 respectively form an inlet collector and an outlet collector, are connected to each other through the internal channels 11.

The aforementioned profiles 10 in this case have a substantially round cross section and are provided on their outer wall with protruding longitudinally oriented ribs 13.

In this case, the aforementioned profile 10 is provided with two sets of parallel ribs 13, respectively a first set of parallel ribs 13A extending on one side of the profile 10, and a second set of parallel ribs 13B extending on the opposite side and which, in the illustrated example of a cylindrical casing 2, enclose an angle A with the first set of ribs 13A of less than 180 ° and which more particularly are oriented substantially tangentially with respect to the casing 2.

The aforementioned ribs 13A and 13B extend, as shown in Figure 3, only over a portion of the profiles 10, more particularly such that near the free end of these profiles 10, portions Y are formed which are free of ribs.

A second inlet opening 14 and a second outlet opening 15 are also provided in the casing 2, which are in communication with the respective spaces 12 between the plates 7 and the end walls 4.

In the space 3 enclosed by the casing 2, a silencer 16 is centrally provided in this case which is formed by a cylindrical casing 17 made of sound-insulating material, which casing 17 is positioned along the longitudinal direction of the casing 2 and concentrically therewith. is open at its end facing the inlet opening 5 and is closed at its end facing the outlet opening 6.

In this case, all the aforementioned profiles 10 are arranged in a flow-through channel 18 which is bounded by an outer jacket formed by the jacket 2 and an inner jacket formed by the jacket 17 of the silencer 16 and which forms a flow-through channel for a first fluid, one and the other such that, in the mounted state of the improved heat exchanger 1 according to the invention, the aforementioned profiles 10 are arranged in the aforementioned space 3 such that each set of ribs 13A of a first profile 10 engages a second set of ribs 13B of an adjacent, second profile 10.

The dimensions of the aforementioned ribs 13 are preferably chosen such that narrow passages are formed between the interlocking ribs 13A and 13B of adjacent profiles 10.

Due to the specific design of the profiles 10, the above-mentioned flow channel 18 according to the invention can be filled almost completely by profiles 10, with the exception of the space occupied by the narrow passages.

According to the invention, the design of the aforementioned profiles 10 is such that the aforementioned narrow passages each have substantially the same hydraulic diameter dh.

The operation of an improved heat exchanger 1 according to the invention is very simple and as follows.

A first fluid, for example a gas to be cooled, is introduced via the aforementioned central inlet opening 5 into the end wall 4 and through a first opening 8 into a plate 7 in the space 3, as indicated by arrow B, whereafter this fluid passes along the rib-free portions Y of the profiles 10 ends up in the cylindrical flow-through channel 18 around the silencer 16, as indicated by arrow C and flows through the narrow flow-through channels between the ribs 13A and 13B to the outlet opening 6 along which it is taken, as shown by arrow D.

As indicated by arrow E, a second fluid is supplied via the second inlet opening 14, for example in the form of a cooling liquid such as water or the like, which flows into a first space 12 or the inlet collector, whereafter this second fluid passes through the openings 9 and through it the channels 11 in the profiles 10 end up in the second space 12 or the outlet collector and are discharged via the outlet opening 15 in the sense of arrow F.

In this way the respective fluids flow in countercurrent, but it is clear that a heat exchanger according to the invention also allows to be used in direct current.

It is also clear that the aforementioned second inlet opening 14 and outlet opening 15 can be connected to a closed cooling circuit.

Due to the presence of the water in the profiles 10, the gas can, via the ribs 13, give off its heat to this water that flows into the channels 11.

Since the aforementioned narrow passages between the respective profiles 10 each have substantially the same hydraulic diameter dh, the generation of leakage currents in the heat exchanger 1 is prevented since the gas is distributed very evenly around the respective profiles 10.

Due to the presence of the aforementioned sound damper 16 centrally in the aforementioned space 3, noise nuisance due to resonance phenomena of the incoming gas stream can be limited.

Figures 4 and 5 show a variant of an improved longitudinal flow heat exchanger 1 according to the invention, which is designed as a so-called "double pass heat exchanger", in other words the fluids fit in two, namely back and forth, through the heat exchanger and wherein an opening is provided in only one of the end walls 4 which in this case forms the inlet opening 5 for the first fluid, while the outlet opening 6 for the first fluid is arranged at the top in the jacket 2 of the heat exchanger, in the vicinity of the end with the aforementioned inlet opening 5.

A tube 19 also extends in the cylindrical space 18 between the jacket 2 and the silencer 16 and between the aforementioned plates 7, along the length direction of the heat exchanger 1, which tube connects against a plate 7, on the side of the inlet opening 5, while on the other side of the heat exchanger 1 it is separate from the other plate 7.

In this case two sets of openings 9 are provided in the plates 7, respectively a first series of openings 9A, which extend at fixed intervals relative to each other around the longitudinal axis XX 'of the heat exchanger 1 and all extend at a fixed distance relative to these axis XX 'and a second series of openings 9B which also extend at fixed intervals around the aforementioned axis XX', but which are closer to this axis XX 'than the first series of openings 9A.

The first series of openings 9A in the respective plates 7 are in this case connected to each other by means of a first set of profiles 10A, while the second series of openings 9B in the respective plates 7 are connected to each other by means of a second set of profiles 10B.

In the space 12 between the end wall 4 with the inlet opening 5 and the plate 7, a cylindrical dividing wall 20 is additionally provided, which in this case is concentric with the aforementioned inlet opening 5, all such that the first series of openings 9A are outside these partition 20 are located and issue on a first annular space 21 which in this case forms the inlet collector for the second fluid, while the second series of openings 9B are located within this partition wall 20 and issue on a second annular space 22 which is separate from the aforementioned first annular space 21 and which forms an outlet collector for the second fluid.

The aforementioned second inlet opening 14 for the second fluid is arranged in this case in the casing 2, such that it opens onto the aforementioned first annular space 21 or the inlet collector, while the second outlet opening 15 for the second fluid is arranged in a end wall 4 and onto the second annular space 22 or the exhaust collector.

The operation of such an embodiment of an improved heat exchanger 1 according to the invention is practically analogous to that of the previous embodiment, wherein also in this case a first fluid, such as a gas to be cooled, is supplied through the inlet opening 5, which then proceeds along the rib-free portions Y of the second series of profiles 10B enter the cylindrical space 18 between the silencer 16 and the tube 19 and flow along the ribs 13 of this second series of profiles 10B.

The gas then proceeds between the tube 19 and the jacket 2, whereafter it flows between the ribs 13 of the first series of profiles 10A to the outlet opening 6, where it can be taken off for use in, for example, a compressed air network.

Along the second inlet opening 14, a second fluid, such as, for example, water, is introduced, which enters the first annular space 21 or the inlet collector and is then passed through the channels 11 of the first series of profiles 10A.

Subsequently, as shown by arrow G, the water flows into the channels 11 of the second series of profiles 10B, whereafter it enters the second annular space 22 or the outlet collector and can be discharged via the second outlet opening 15.

The advantage of such an embodiment is that the heat-exchanging surface between the fluids increases considerably without thereby increasing the total volume of the heat exchanger 1.

Figures 6 and 7 show a variant of an improved heat exchanger according to Figure 1, wherein additional ribs 23 are arranged on the surface of the aforementioned ribs 13, as a result of which the heat-exchanging surface is still considerably larger than in the previous embodiment.

The operation of such a variant is analogous to that of the embodiment shown in Figures 1 to 3.

Figures 8 and 9 show yet another embodiment of a heat exchanger according to the invention, which also has substantially an analogous structure to the embodiment of Figure 1, but in which the profiles 10 have a substantially rectangular cross-section.

The channels 11 in the profiles 10 also have a substantially rectangular cross section.

The operation of such an embodiment is identical to that of the embodiment described with respect to Figure 1.

Figures 10 and 11 show yet another embodiment of an improved heat exchanger according to the invention, wherein no sound damper is provided in the aforementioned space 3, but where this space 3 fully serves as a flow channel for the first fluid and is completely filled with profiles 10.

The profiles 10 in this case consist of a central tube 24 on which on the outside, in this case, three main ribs 25 extend which enclose an angle H of approximately 120 ° with respect to each other.

In this case, between each two adjacent main ribs 25, additional parallel intermediate ribs 26 are provided which run in a direction parallel to the bisector of the respective angle H extending between these main ribs 25.

Each profile 10 is arranged in the space 3 such that its intermediate ribs 26 engage in intermediate ribs 26 of an adjacent profile 10, all such that narrow passages are formed between the respective ribs 26 of interlocking profiles 10 which according to the invention each have substantially the same hydraulic diameter dh.

In this case, fittings 27 are provided against the inside of the casing 2 with ribs 28 which engage in the intermediate ribs 26 of profiles 10 placed next to them.

As can be seen from Figure 12, in this case, but not necessarily, internal channels 29 are also provided in the aforementioned fittings 27, the cross-section of which preferably, but not necessarily, has a circumference equal to 2/3 times the circumference of the cross-section of a channel 11 and / or whose cross-sectional area is equal to 4/9 times the cross-sectional area of a channel 11.

It is clear that the channels 29 according to the invention should not be designed round, but that they can have any shape in order to be able to optimize the ratio between the flow-through section and the heat-exchanging surface.

If required, additional ribs can be provided on the aforementioned intermediate ribs 26, such as on the profile 10 shown in Figure 7.

The operation of such a variant is substantially analogous to that of the embodiment shown in Figure 1, wherein a first fluid flows through the flow channel 18, between the respective ribs 26 of the profiles and the ribs 28 of the fittings 27, while passing through the channels 11, a second fluid flows into the profiles.

According to the invention, it is not excluded that the aforementioned accessories 27 can be integrated into the aforementioned jacket 2.

Figure 13 shows another variant of an improved heat exchanger 1 according to Figure 3, wherein the aforementioned sound damper is also provided with a jacket 17 which in this case is open at both ends, but in which an intermediate wall 30 is provided which forms a separation between a first space 31 which is opposite the inlet opening 5 and a second space 32 which is opposite the aforementioned outlet opening 6.

The aforementioned tubes connecting the inlet opening 5 and outlet opening 6 respectively to a respective opening 8 in a plate 7 extend in this case into a respective space 31 or 32.

A drain opening 33 is also provided at the bottom of the casing 2 along which condensate can be discharged.

The operation of such an embodiment is analogous to that of Fig. 3, but, in this case, condensate can be discharged via the aforementioned outlet opening 33.

Figure 14 shows yet another embodiment of an improved longitudinal flow heat exchanger 1 according to the invention, wherein the inner and outer casing are formed by the outer ribs 13B of the respective profiles 10, which for this purpose are each connected to an adjacent profile, for example by means of of welding, brazing or the like. It goes without saying that according to the invention only the inner jacket or the outer jacket can also be formed by ribs of adjacent profiles 10.

It is clear that the aforementioned profiles can also be provided with coupling means (not shown in the figures) which enable joining profiles placed next to each other, which coupling means can for instance be embodied in the form of a snap system with lips which at the free end of one or more ribs 13A and / or 13B are provided with a first profile 10 and which can cooperate with recesses in the ribs 13B and / or 13A of an adjacent second profile 10.

It goes without saying that the flow sense of the fluids in a heat exchanger 1 according to the invention can have both the same sense, as in the embodiments of figures 3 and 12, and an opposite sense of flow, for example as in the embodiment of figure 5.

It is also obvious that the first fluid is not limited to a gas to be cooled, such as compressed air, but that any fluid is eligible for this. The second fluid is also not limited to a cooling liquid, such as, for example, water.

It is also not excluded according to the invention that the first fluid forms the cooling medium, while the first fluid is a gas or liquid to be cooled.

According to the invention, at least one longitudinally oriented rib can be provided in the inner channel 11 of one or more of the aforementioned hollow profiles 10, 10A and / or 10B in order to increase the heat-exchanging surface between the respective first and second fluid.

The present invention is by no means limited to the embodiments described as examples and shown in the figures, but an improved heat exchanger according to the invention can be embodied in all shapes and sizes without departing from the scope of the invention.

Claims (20)

An improved longitudinal flow heat exchanger comprising a casing defining an enclosed space (3) with an inlet opening (5) and an outlet opening (6), which space (3) serves wholly or partly as a flow channel (18) for a first fluid and of two or more heat exchange elements which are arranged in the aforementioned space (3) and which are in the form of hollow profiles (10, 10A, 10B) arranged next to each other, each defining an internal channel (11) which forms a passage for a second fluid, characterized in that longitudinally oriented ribs (13Δ, 13B, 25, 26) are provided on the outer sides of the aforementioned profiles (10) such that ribs (13A, 13B, 26) have adjacent profiles (10, 10A, 10B) interlock, whereby narrow passages are formed between the respective ribs (13A, 13B, 26), each having substantially the same hydraulic diameter (dh). Improved longitudinal flow heat exchanger according to claim 1, characterized in that the aforementioned profiles (10, 10A, 10B) are formed by extrusions. Improved longitudinal flow heat exchanger according to claim 1 or 2, characterized in that the aforementioned profiles (10, 10A, 10B) are provided with two sets of ribs (13A and 13B) that enclose an angle (A) with each other. Improved longitudinal flow heat exchanger according to claim 3, characterized in that the aforementioned enclosed angle (A) is smaller than 180 °. Improved longitudinal flow heat exchanger according to one or more of the preceding claims, characterized in that the above-mentioned profile (10, 10A, 10B) has a substantially round cross-section. Improved longitudinal flow heat exchanger according to one or more of claims 1 to 4, characterized in that said profile (10, 10A, 10B) has a substantially rectangular cross section. Improved longitudinal flow heat exchanger according to one or more of the preceding claims, characterized in that at least one longitudinally oriented rib is provided in the internal channel (11) of one or more of the aforementioned hollow profiles (10, 10A, 10B). Improved longitudinal flow heat exchanger according to one or more of the preceding claims, characterized in that the above-mentioned jacket is formed by ribs (13B) of adjacent profiles (10). Improved longitudinal flow heat exchanger according to claim 1, characterized in that said profiles (10, 10A, 10B) are provided with a central tube (24) on which three main ribs (13) are provided on the outside which enclose an angle (H) of approximately 120 ° to each other; and that a number of intermediate ribs (26) are provided between each pair of adjacent main ribs (25) which are parallel, or substantially parallel, to the bisector of said enclosed angle (H). Improved longitudinal flow heat exchanger according to claim 9, characterized in that between the inside of the casing (2) and the profiles (10) a number of fittings (27) are provided with ribs (13A, 13B) which engage in the ribs (1333, 13A) of an adjacent profile (10). Improved longitudinal flow heat exchanger according to claim 10, characterized in that the aforementioned accessories (27) are integrated in the jacket (2) or arranged against it. Improved longitudinal flow heat exchanger according to one or more of the preceding claims, characterized in that additional ribs (23) are provided on said ribs (13A, 13B). Improved longitudinal flow heat exchanger according to one or more of the preceding claims, characterized in that a silencer (16) is provided centrally in the aforementioned space (3) and that the said flow channel (18) extends between said silencer (16) and the mantle (2). Improved longitudinal flow heat exchanger according to claim 13, characterized in that two plates (7) are provided in said casing (2) in which an opening (8) is provided which is connected to said inlet opening (5) and to said outlet opening respectively (6) and which is also provided with a number of smaller openings (9, 9A, 9B) which extend at equal intervals around said opening (8) and are located at an equal distance therefrom; and that the aforementioned smaller openings (9, 9A, 9B) of the respective plates (7) are in communication with each other via the channels (11) of the profiles (10, 10A, 10B). Improved longitudinal flow heat exchanger according to claim 14, characterized in that a space (12 or 21) is enclosed between the respective end walls (4) and each plate (7), which space is connected to a second inlet opening or a second outlet opening and which has an inlet -, respective exhaust collector. Improved longitudinal flow heat exchanger according to one or more of the preceding claims, characterized in that it is in the form of a double pass heat exchanger that contains two series of profiles (10). Improved longitudinal flow heat exchanger according to one or more of the preceding claims, characterized in that a drain opening (33) is provided in the above-mentioned jacket (2) for discharging condensate. Improved longitudinal flow heat exchanger according to one or more of the preceding claims, characterized in that the aforementioned profiles (10, 10A, 10B) are provided with coupling means that allow each profile (10, 10A, 10B) to be connected to an adjacent profile (10, 10A, 10B). Improved longitudinal flow heat exchanger according to claim 18, characterized in that the above-mentioned coupling means are formed by a snap system. Improved longitudinal flow heat exchanger according to claim 19, characterized in that the aforementioned click system is provided with lips which are provided at the free end of one or more ribs (13) with a first profile (10) and with recesses in the ribs (13) of a second profile (10) placed next to it, wherein the aforementioned lips can cooperate with these recesses.