WO2023095182A2

WO2023095182A2 - Heat exchanger

Info

Publication number: WO2023095182A2
Application number: PCT/IT2022/050304
Authority: WO
Inventors: Matteo D'ANTONI; Sandro ORTOLANO
Original assignee: Thermokey S.P.A.
Priority date: 2021-11-25
Filing date: 2022-11-25
Publication date: 2023-06-01
Also published as: WO2023095182A3; IT202100029846A1

Abstract

Heat exchanger (100) comprising a plurality of heat exchange elements (10) which are fluidically connected to first recirculation means (11) and second recirculation means (12) disposed respectively at entry to and at exit from said heat exchange elements (10), wherein said first and second recirculation means (11, 12) each comprise at least a first and a second duct (26, 27, 29, 30), for feed and recovery, respectively, separated from each other by respective separation baffles (33, 34), and wherein each element of said plurality of heat exchange elements (10) comprises both a plurality of circulation elements (20) divided into at least a first group (23), in which a first heat transfer fluid (Fl) flows, and into a second group (25), in which a second heat transfer fluid (F2) flows, and also at least one separation portion (31) interposed between the first group (23) and the second group (25).

Description

“HEAT EXCHANGER”

FIELD OF THE INVENTION

The present invention concerns a heat exchanger which can be used, depending on the methods of use, to cool or heat at least one heat transfer fluid flowing inside it. For example, the heat exchanger can be used with the function of condensing a heat transfer fluid.

BACKGROUND OF THE INVENTION

Heat exchangers are known, which comprise a plurality of modular heat exchange elements, each of which has a plurality of circulation elements, that is, a plurality of channels, also referred to as micro-channels or “ports”, which define the passages for at least one heat transfer fluid.

The modular heat exchange elements usually have an oblong development, a flattened shape and are disposed parallel to each other. Moreover, heat exchange fins are externally attached between adjacent modular heat exchange elements.

The channels, or micro-channels, are parallel to each other and distributed longitudinally over the entire width of each modular heat exchange element. Furthermore, in correspondence with the respective inlet and outlet ends, the channels are connected to recirculation means of the heat exchanger, which allow to introduce at least one heat transfer fluid inside the channels and, respectively, to collect or recover the latter once it has passed through the channels.

Solutions are also known from the prior art which provide heat exchangers comprising a plurality of double-flow modular heat exchange elements, that is, which have a plurality of channels in which two different heat transfer fluids flow separately.

In these known solutions, the channels are divided into at least two groups, each of which is dedicated to the passage of a corresponding heat transfer fluid. Moreover, the groups of channels can be separated, and therefore distanced, by a baffle or a solid portion.

An example of such known solutions is described in the patent application for industrial invention in Italy n. IT 102018000007448, in the name of the present Applicant. These known heat exchangers comprise a first manifold, or inlet manifold, and a second manifold, or outlet manifold, which allow to introduce the two heat transfer fluids inside the corresponding group of channels and, respectively, to collect or recover them once they have passed through the corresponding group of channels. The two manifolds are connected to the respective opposite ends of the modular elements.

Generally, both the inlet manifold and also the outlet manifold are divided, by means of a dividing wall, into two parts, each dedicated to the circulation of a corresponding heat transfer fluid. In particular, the dividing wall of the two manifolds is coupled and attached to the internal baffle of each modular element which separates the two groups of channels, so as to structurally separate the part dedicated to the first heat transfer fluid and the part dedicated to the second heat transfer fluid.

In general, the double-flow modular heat exchange elements bring a clear improvement in terms of heat exchange and/or thermal power exchanged, but in order to obtain an optimal effect or improvement they have to be correctly sized.

One disadvantage of these heat exchangers is that it is difficult to achieve the correct sizing of the modular elements, in particular because it is closely linked to the field of application of the heat exchanger, as well as to its operating modes. Furthermore, the thickness of the internal baffle of each modular element has to be such as to allow it to be milled, in order to obtain a suitable coupling seating for the dividing wall of each manifold. The thickness of the dividing wall also has to be adequately sized, since despite its small size it must be such as to resist the operating pressures of the two heat transfer fluids.

Specifically, the internal baffle and the dividing wall are attached by welding or brazing.

Another disadvantage of known heat exchangers is that this operation is particularly difficult and complex, since the space inside the manifolds is very small and, in order to obtain a perfect watertight seal, it is necessary to weld or braze the two parts both externally and also internally.

It is also clear that the milling operation of the internal baffle and the coupling and attachment operations of the dividing walls and each internal baffle have to be performed in a very precise way, in order to prevent, in correspondence with the coupling seating between the dividing wall and internal baffle, the hermetic seal between the two different groups of channels from failing. In fact, in this case the two heat transfer fluids could mix undesirably, causing malfunctions and/or breakages of the heat exchanger.

Furthermore, another disadvantage of known heat exchangers is that, due to the very small spaces of the manifolds, it is also complicated to carry out the maintenance thereof, in particular in correspondence with the dividing wall and the internal baffle.

There is therefore a need to perfect a heat exchanger which can overcome at least one of the disadvantages, or problems, of the state of the art.

To do this it is necessary to solve the technical problem of producing a heat exchanger with correctly sized modular elements and which at the same time does not require the execution of complex assembly operations of the modular elements to the manifolds in order to guarantee, during operation, the correct and effective separation of the circulation circuits dedicated to the two heat transfer fluids.

In particular, one purpose of the present invention is to provide a heat exchanger which is simple to make and maintain and which has a high heat exchange efficiency.

Another purpose of the present invention is to provide a heat exchanger which is versatile, and which allows to obtain optimum heat exchange performance.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claim. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

In accordance with the above purposes, a heat exchanger according to the present invention comprises a plurality of heat exchange elements which are fluidically connected to first recirculation means and second recirculation means disposed respectively at entry to, and at exit from, the heat exchange elements.

According to one aspect of the present invention, the first and second recirculation means each comprise at least a first and a second duct, respectively feed and recovery, separated from each other by respective separation baffles.

According to one aspect of the present invention, each element of the plurality of heat exchange elements comprises both a plurality of circulation elements divided into at least a first group, in which a first heat transfer fluid flows, and into a second group, in which a second heat transfer fluid flows, and also at least one separation portion interposed between the first group and the second group.

According to one aspect of the present invention, each modular element comprises at least one recess made in correspondence with the separation portion so as to define at least a first zone and a second zone of the heat exchange element between which the recess is interposed, into which the circulation elements belonging to the first group and to the second group, respectively, flow.

According to one aspect of the present invention, the first and second recirculation means each comprise a front wall in which at least a first slot and a second slot are made, each configured to receive the first zone and the second zone, respectively, in a sealed manner.

According to one aspect of the present invention, the recess is configured to be disposed aligned with the separation baffles at least in correspondence with the front wall.

According to one aspect of the present invention, the first recirculation means also comprise a third feed duct and the second recirculation means also comprise a third recovery duct.

According to one aspect of the present invention, each of the modular elements also comprises both a third group of said channels inside which the second heat transfer fluid or possibly a third heat transfer fluid can flow, and also an additional separation portion in correspondence with which an additional recess is made to separate the third group from the first and second groups.

According to one aspect of the present invention, the first recirculation means and the second recirculation means each comprise an additional separation baffle, wherein the separation baffles allow to separate the first feed and recovery ducts from the second and third feed and recovery ducts.

According to one aspect of the present invention, the additional recess is configured to be disposed aligned with the additional separation baffle at least in correspondence with the front wall, so as to define a third zone of the heat exchange element, into which the circulation elements belonging to the third group flow.

According to one aspect of the present invention, at least a third slot is made in the front wall which is configured to receive the third zone in a sealed manner.

According to one aspect of the present invention, the plurality of circulation elements extends parallel to a longitudinal axis, while the separation portion and the additional separation portion extend for a distance measured along a transverse axis which is orthogonal to the longitudinal axis.

According to one aspect of the present invention, the recess and the additional recess extend for a length which is at least double said distance, so that the bottom of the recess is disposed outside the first and second recirculation means so as to define a cavity between the recess and the front wall.

According to one aspect of the present invention, the separation portion and the additional separation portion extend between two opposite ends of the plurality of modular elements, and they can be conformed as a solid or hollow bar, in the latter case being shaped like one of the circulation elements.

According to one aspect of the present invention, the circulation elements are distributed in such a way as to be distanced from each other by a segment, measured parallel to a transverse axis, which has a variable width: the circulation elements of the first group are separated from each other by a segment having a first width, and the circulation elements of the second group are separated from each other, as well as from the circulation elements of the first group, by a segment having a second width, which is greater than the first width.

According to another aspect of the present invention, there is provided a method for assembling a heat exchanger comprising a plurality of heat exchange elements which are fluidically connected to first recirculation means and to second recirculation means, disposed respectively at entry to, and at exit from, the heat exchange elements. Each element of the plurality of heat exchange elements comprises both a plurality of circulation elements divided into at least a first group, in which a first heat transfer fluid flows, and into a second group, in which a second heat transfer fluid flows, and also at least one separation portion configured to separate the first group from the second group, distancing them by a certain distance.

According to one aspect of the present invention, the method comprises the following steps:

- preparing one or more slots in a front wall of the first recirculation means and of the second recirculation means,

- assembling the heat exchange elements to the first and second recirculation means by inserting into a respective one of the slots a first zone and a second zone of the heat exchange element, into which the channels belonging to the first group and to the second group, respectively, flow,

- creating at least one recess in correspondence with the separation portion, wherein the recess separates the first zone from the second zone,

- during the assembling step, it is provided that the recess is disposed outside the first and second recirculation means, aligned with a respective separation baffle at least in correspondence with the front wall, wherein the respective separation baffle separates the inside of the first and second recirculation means into at least two ducts, respectively feed and recovery, into which the channels of the first and second group flow,

- permanently joining the first zone and the second zone to the front wall in correspondence with the slots, with a high temperature joining method.

According to one aspect of the present invention, the method also comprises:

- in the assembling step, inserting into a respective one of the slots a third zone of the heat exchange element, into which the channels belonging to a third group, separated from the first group by an additional separation portion, flow,

- in the creating step, also creating an additional recess in correspondence with the additional separation portion, wherein the additional recess separates the first zone from the third zone,

- in the assembling step, it is provided that the additional recess is disposed outside the first and second recirculation means, aligned with a respective separation baffle disposed inside the first and second recirculation means,

- in the joining step, it is provided to permanently join the third zone to the front wall in correspondence with a respective one of the slots into which the third zone has been inserted.

According to one aspect of the present invention, the high temperature joining method comprises a brazing step.

According to one aspect of the present invention, the recess and the one or more slots are made by means of mechanical machining, in particular milling or shearing, or by means of laser processing. According to one aspect of the present invention, there is also provided a modular heat exchange element for a heat exchanger comprising a plurality of heat exchange elements which are fluidically connected to first recirculation means and second recirculation means disposed respectively at entry to and at exit from the heat exchange elements.

According to one aspect of the present invention, the modular heat exchange element develops along a longitudinal axis and comprises both a plurality of circulation elements each having a certain cross section and divided into at least a first group of circulation elements in which a first heat transfer fluid flows having a first operating temperature, and at least a second group of circulation elements in which a second heat transfer fluid flows having a second operating temperature, wherein the first operating temperature is greater than the second operating temperature, and wherein the first group and the second group of circulation elements have a respective hydraulic diameter, and also at least one separation portion configured to separate the first group from the second group of circulation elements, distancing them by a certain distance.

In accordance with another aspect of the present invention, said distance has a certain size, measured along a transverse axis substantially perpendicular to the longitudinal axis along which the circulation elements develop, which is inversely proportional to a hydraulic diameter of the circulation elements of the first group.

In accordance with another aspect of the present invention, the separation portion has a certain size, measured in a direction parallel to a positioning axis substantially perpendicular to the longitudinal axis and to the transverse axis, which remains constant at least along the longitudinal axis.

In accordance with another aspect of the present invention, the certain size of the separation portion substantially defines the thickness of the modular heat exchange element.

In accordance with another aspect of the present invention, the circulation elements of the first group and of the second group are shaped in such a way as to have a shape and sizes such that the circulation elements of a same group, that is, of the first group and of the second group, have a constant hydraulic diameter. Furthermore, the ratio between the hydraulic diameter of the circulation elements of the first group and a hydraulic diameter of the circulation elements of the second group is comprised between 0.2 and 1.

Using the hydraulic diameter as a reference parameter to size the circulation elements of the first and second group achieves the advantage of being able to determine an optimal sizing of the circulation elements, regardless of the geometric shape of their cross section.

In accordance with another aspect of the present invention, for high pressures exerted by the first heat transfer fluid in the first group of circulation elements, comprised preferably between about 45 and about 100 bar, the certain size of the distance varies on average between 2 and 4.5 times the hydraulic diameter of the certain cross section of the circulation elements of the first group.

In accordance with another aspect of the present invention, for medium pressures exerted by the first heat transfer fluid in the first group of circulation elements, comprised preferably between about 15 and about 45 bar, the certain size of the distance varies on average between 1 and 2 times the hydraulic diameter of the certain cross section of the circulation elements of the first group.

In accordance with another aspect of the present invention, for low pressures exerted by the first heat transfer fluid in the first group of circulation elements, comprised preferably between about 0.1 and about 15 bar, the certain size of the distance varies on average between 0.3 and 1 times the hydraulic diameter of the certain cross section of the circulation elements of the first group.

This achieves the advantage of optimizing the sizes of the modular element in relation to the type of heat transfer fluid, or types of heat transfer fluids, used, thus also achieving a better heat exchange performance of the modular element itself.

The modular heat exchange element, wherein the sum of each certain cross section of the circulation elements of the first group defines a first area, wherein the sum of each certain cross section of the circulation elements of the second group defines a second area, and wherein the sum of the first area and the second area defines a corresponding total area.

In accordance with another aspect of the present invention, the ratio between the second area and the total area is comprised preferably between about 0.05 and 0.5.

In accordance with another aspect of the present invention, the ratio between the second area and the total area is comprised preferably between about 0.1 and 0.35.

In accordance with another aspect of the present invention, it is provided to use a modular heat exchange element configured to function at least in a first operating mode in which an air flow first sweeps the second group of circulation elements, so that the cooling of the air flow allows to maximize the heat exchange between the air flow and the first heat transfer fluid circulating inside the first group of circulation elements.

In accordance with another aspect of the present invention, it is provided to use a modular heat exchange element configured to function at least in a second operating mode in which an air flow first sweeps the first group of circulation elements, so that the heating of the air flow allows to maximize the heat absorbed by the second heat transfer fluid circulating inside the second group of circulation elements.

DESCRIPTION OF THE DRAWINGS

These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a three-dimensional view of a heat exchanger comprising a plurality of modular heat exchange elements according to the present invention;

- fig. 2 is an exploded three-dimensional view of an enlarged detail of fig. 1 ;

- figs. 3, 4, 5, 6, 7, 10, 11 and 15 are section views of a modular heat exchange element for a heat exchanger in accordance with different embodiments of the present invention;

- fig. 8 is a partial and schematic top plan view of a portion of a heat exchanger according to the present invention comprising the modular element of fig. 7;

- fig. 9 is a partly sectioned front view of recirculation means comprised in the exchanger of fig. 8, taken according to the section plane outlined with IX-IX of the same drawing;

- figs. 9a and 9b are section views, taken along the plane IX’-IX’ of fig. 8, of variants of a detail of the modular element of fig. 7;

- fig. 12 is a schematic top plan view of a portion of a heat exchanger according to the present invention comprising the modular element of fig. 11 ;

- fig. 13 is a partly sectioned front view of recirculation means comprised in the exchanger of fig. 12, taken according to the section plane outlined with XIII-XIII of the same drawing;

- fig. 14 is a schematic top plan view of a variant of the heat exchanger of fig. 12;

- figs. 16-19 are graphs showing the trend of certain quantities and/or certain operating parameters, relating to the operation, also according to different operating modes, of the modular heat exchange element comprised in an exchanger according to the present invention.

We must clarify that in the present description the phraseology and terminology used, as well as the figures in the attached drawings also as described, have the sole function of better illustrating and explaining the present invention, their function being to provide a non-limiting example of the invention itself, since the scope of protection is defined by the claims.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications. DESCRIPTION OF SOME EMBODIMENTS OF THE PRESENT INVENTION

With reference to fig. 1, a plurality of modular heat exchange elements 10 according to the present invention can be used in a heat exchanger, substantially similar, in its general features, to the exchangers known in the state of the art, which is indicated as a whole with number 100.

The heat exchanger 100 also comprises first recirculation means 11 and second recirculation means 12 which are fluidically connected to the plurality of modular heat exchange elements 10 and are disposed, respectively, at entry to and exit from the latter.

The modular heat exchange elements 10 have an oblong development, which extends along a longitudinal axis Z, they are placed on reciprocally parallel planes P, disposed in series along a positioning axis X (fig. 2), preferably vertical, and they are separated from each other by a plurality of fins 13. The fins 13 are attached outside the modular heat exchange elements 10 and are configured to increase the heat exchange surface thereof.

In accordance with a preferential embodiment of the present invention, the modular heat exchange elements 10 have a substantially flat cross section, that is, one in which the width is much greater than the thickness; for example, the width can be at least five times the thickness.

In the examples given here, each modular heat exchange element 10 comprises an upper wall 15 and a lower wall 16 (figs, from 3 to 5, 7, 10, 11 and 14) which are flat, and opposite lateral walls 17 and 19 which have a semicircular shape.

In accordance with possible embodiments of the present invention, the upper wall 15 and the lower wall 16, instead of being flat, can be made with a slightly crowned profile, as shown in fig. 6.

Each modular heat exchange element 10 comprises, along its longitudinal development, a plurality of circulation elements, or channels 20, which are disposed parallel to each other, in succession along a transverse axis Y, and which extend, along the longitudinal axis Z, between a first inlet end 21 and a second outlet end 22 of the modular heat exchange element 10.

In the example given here, the channels 20 are divided at least into a first group 23 and a second group 25, and they are fluidically connected, by means of the respective first ends 21 and second ends 22, to the first recirculation means 11 and to the second recirculation means 12, respectively. In particular, the first recirculation means 11 comprise a first feed duct 26 and a second feed duct 27 separated by a first separation baffle 33, while the second recirculation means 12 comprise a first recovery duct 29 and a second recovery duct 30 separated by a second separation baffle 34.

In accordance with the embodiment shown in figs. 1 and 8-9, the first group 23 of channels 20 is fluidically connected to the first feed duct 26 and to the first recovery duct 29, so that a first heat transfer fluid Fl can circulate inside the first group 23 of channels 20. The first heat transfer fluid Fl can be a cooling fluid having a first operating temperature Tl, for example comprised between 20°C and 250°C; wherein, by way of example, the lower limit of 20°C indicates the lowest possible condensation temperature for a cooling gas, or for water in a certain operating mode, or condition, of the modular heat exchange element 10, while the upper limit of 250°C refers, in the industrial field, to the maximum temperature limit of processes which are defined as “low temperature”. Furthermore, we must clarify that in normal applications of the modular heat exchange element 10, the upper limit of the first temperature Tl of the first heat transfer fluid is equal to about 150°C.

In the same way, the second group 25 of channels 20 is fluidically connected to the second feed duct 27 and to the second recovery duct 30, so that a second heat transfer fluid F2 can circulate inside the second group 25 of channels 20. The second heat transfer fluid F2 can be water, possibly in combination with glycol, or another suitable liquid, having a second operating temperature T2 lower than the first temperature Tl, for example comprised between -40°C and 105°C; wherein, by way of example, the lower limit of -40°C indicates the minimum temperature that water combined with glycol can reach, while the upper limit of 105°C is the maximum temperature of use of the water, which, in this case, is considered as consisting of a liquid fraction and a vapor fraction.

In accordance with possible embodiments of the present invention, the number of channels 20 of the first group 23 is greater than or equal to the number of channels 20 of the second group 25. Preferably, as shown in figs, from 1 to 7, the number of channels 20 of the first group 23 is at least double the number of channels 20 of the second group 25. In the example given here, the heat exchanger 100 comprises five modular heat exchange elements 10, all the same as each other, that is, comprising the same relative proportions described above between the number of channels 20 of the first and second group 23, 25. In this way, it is possible to obtain a heat exchange which is substantially uniform along the vertical positioning axis X.

In accordance with one embodiment of the present invention, shown in figs, from 1 to 3, both the channels 20 of the first group 23 and also the channels 20 of the second group 25 have a certain cross section, substantially rectangular in shape with slightly beveled corners.

Please note that the sum of the areas of each cross section of the channels 20 of the first group 23 defines a first area Al, while the sum of the areas of each cross section of the channels 20 of the second group 25 defines a second area A2. The sum of the first area Al and the second area A2 defines a total area AT, which represents the sum of the areas of the cross sections of all the channels 20 of the modular heat exchange element 10.

In accordance with one aspect of the present invention, the cross section of each channel 20 of the first group 23 and of each channel 20 of the second group 25 is advantageously configured, or conformed, in such a way as to have a constant hydraulic diameter. This is the case regardless of the shape that this cross section may have.

In accordance with possible embodiments of the present invention, the cross section of each channel 20 of the first group 23 is advantageously configured in such a way as to have the hydraulic diameter constant throughout the first group 23. Likewise, the cross section of each channel 20 of the second group 25 is also advantageously configured in such a way as to have the hydraulic diameter constant throughout the second group 25.

In accordance with possible embodiments of the present invention, the specific cross sections of the channels 20 of the first group 23 and of the second group 25 can be the same, or they can be different.

The hydraulic diameter is a fluid-dynamic quantity which is very often used to size pipes, or channels, in the event that the cross section of the latter is complex, or in any case non-circular. In mathematical-physical terms, the hydraulic diameter represents an equivalent diameter defined as the diameter that a circular section with the same ratio between Perimeter and Area would have, and it is given by the following formula:

Hydraulic diameter = Dh = 4 Area / Perimeter

The Applicant, through a number of studies and modeling, has therefore identified the hydraulic diameter as a reference parameter to define new constructive logics of the modular heat exchange element 10, advantageously removing the link between operating quantities or parameters and the geometric shape of the cross sections of the channels 20.

In accordance with another aspect of the present invention, the ratio between the hydraulic diameter DIIAI of the channels 20 of the first group 23 and the hydraulic diameter of the channels 20 of the second group 25 is comprised between about 0.2 and 1.

For example, this ratio is equal to about 0.2 when a cooling fluid flows in the first group 23 of channels 20 and cooled water flows in the second group 25 of channels 20; on the other hand, this ratio is equal to about 1 when the same heat transfer fluid flows both in the first group 23 and also in the second group 25 of channels 20, whether it is a cooling fluid or cooled water. In accordance with possible embodiments of the present invention, the channels 20 can have a shape and/or a cross section size different from that shown in fig. 2 or 3, while maintaining the characteristics relating to the hydraulic diameter already described above.

In particular, as shown in fig. 4, the cross section of the first group 23 and of the second group 25 of channels 20 can be quadrilateral, in particular with a gradually more elongated shape toward the lateral walls 17, 19; or, as shown in fig. 5, it can be substantially triangular. Alternatively, the channels 20 could also have a circular or semicircular shape, or other suitable shapes; in the case of polygonal shapes, the vertices can possibly be beveled.

The modular heat exchange element 10 is also provided with a separation portion 31 which extends parallel to the longitudinal axis Z and is configured to separate the first group 23 of channels 20 from the second group 25 of channels 20, distancing them by a certain distance D (figs, from 1 to 5).

As shown in figs, from 1 to 6, the separation portion 31 extends for the entire oblong development of the modular heat exchange element 10 and has a certain size, or height, H, measured in a direction parallel to the positioning axis X, which remains constant at least along its longitudinal development, that is, along the axis Z.

Furthermore, the thickness of the modular element 10, that is, the certain size, or height, H of the separation portion, substantially defines the thickness of the modular heat exchange element 10.

In the embodiments shown in figs, from 1 to 5 and 7, the thickness of the modular element 10 also remains constant along its transverse development, that is, along the axis Y. The Applicant, after a number of studies and modelling, as shown in fig. 15, has identified that it is possible to parameterize this distance D in relation to:

- the pressure exerted by the first heat transfer fluid F 1 and the second heat transfer fluid F2 inside the first group 23 and the second group 25, respectively, of channels 20;

- the hydraulic diameter DIIAI of the channels 20 of the first group 23, taking into account that the hydraulic diameter is constant for each channel 20.

In accordance with another aspect of the present invention, the size of the distance D is inversely proportional to the hydraulic diameter DhAi of the channels 20 of the first group 23.

In accordance with another aspect of the present invention, in the case of high pressures Pl, comprised between about 45 and about 100 bar, the size of the distance D can vary on average between about 2 and 4.5 times the hydraulic diameter Dl r, in the case of medium pressures P2, comprised between about 15 and about 45 bar, the size of the distance D can vary on average between about 1 and 2 times the hydraulic diameter Dl i; and in the case of low pressures P3, comprised between about 0.1 and about 15 bar, the size of the distance D can vary on average between about 0.3 and 1 times the hydraulic diameter Dl i.

By way of example, observing fig. 15, in the case of high pressures Pl, for hydraulic diameters Dl i comprised between 1 and 1.5 mm, the size of the distance D can vary between about 3 and 4.5 mm; in the case of medium pressures P2, for hydraulic diameters DhAi comprised between 1.5 and 2 mm, the size of the distance D can vary between about 2 and 3 mm; and in the case of low pressures P3, for hydraulic diameters Dl i comprised between 2 and 3 mm, the size of the distance D can vary between about 1 and 2 mm.

With reference to figs. 7-9, another embodiment of a heat exchanger 100 according to the present invention is described, in which each modular element 10 comprises a recess 36 (figs. 7 and 8) made in correspondence with the separation portion 31.

The recess 36 extends from the first and second ends 21, 22 of the modular element 10 parallel to the longitudinal axis Z for a length L which, compared to the distance D, is preferably greater than double such distance.

Thanks to the presence of the recess 36, the ends of the channels 20 of the first group 23 are separated from the ends of the channels 20 of the second group 25. This is advantageous since it allows to prevent deformations of the first and second ends 21, 22 of the modular element 10 due to thermal expansions between a first zone 37, into which the channels 20 of the first group 23 flow, and a second zone 38, into which the channels 20 of the second group 25 flow, caused by the significant difference in temperature of the heat transfer fluids which pass through them.

The first zone 37 and the second zone 38 are projecting portions which project toward the first recirculation means 11 and the second recirculation means 12, so that the first zone 37 reaches the first feed and recovery ducts 26, 29 and the second zone reaches the second feed and recovery ducts 27, 30.

The first zone 37 is configured to be inserted into a first slot 14a and the second zone 38 is configured to be inserted into a second slot 14b (fig. 9). The first slot 14a and the second slot 14b are made in a front wall 18 of the first and second recirculation means 11, 12 into which the modular elements 10 are engaged. The first slot 14a and the second slot 14b are aligned with each other in such a way as to be substantially disposed along the same horizontal plane P. Between the first and second slot 14a, 14b there is a space in correspondence with which, inside the first and second recirculation means 11, 12, the separation baffles 33, 34 are disposed, and the outside of which the recess 36 is facing.

The length L of the recess is such that the bottom of the recess 36 is disposed outside the first and second recirculation means 11, 12 so as to define a cavity 41 between the recess 36 and the front wall 18, thanks to which this latter wall is not contacted by the separation portion 31.

This configuration is advantageous since in correspondence with the separation portion 31 it is not necessary to create any sealed coupling between the modular element 10 and the recirculation means 11, 12, thus overcoming the problems of the state of the art.

In the example given here, in which the heat exchanger 100 comprises five modular elements 10 disposed on as many planes P, all parallel to each other, five first slots 14a and five second slots 14b are created in the first and in the second recirculation means 11, 12.

The width of the recess 36, measured parallel to the transverse axis Y, is correlated to the thickness of the first and of the second separation baffle 33, 34.

In one variant, shown in fig. 9a, between the two recesses 36 created at the opposite ends 21, 22 of the modular element 10, there extends a channel 20 which, in this embodiment, no fluid passes through. In this variant, the channel 20 can possibly remain open in correspondence with its opposite ends. This variant is advantageously very versatile since it is not necessary to know the exact location of the separation portion 31 in order to make the modular element 10. In fact, once the position of the first and second separation baffle 33, 34 is known, it will be possible to create the recess 36 in correspondence with one of the channels 20, precisely the one whose position matches that of the baffles.

In another variant, alternative to the previous one and shown in fig. 9b, the separation portion 31 is formed by a solid segment for its entire longitudinal extension, parallel to the longitudinal axis Z, between the two opposite recesses 36.

With reference to figs. 10-14, additional embodiments are described in which, in addition to the first group of channels 23 and the second group of channels 25, a third group of channels 28 is provided. In addition to the separation portion 31 , there is also provided an additional separation portion 31 ’, which separates the different groups of channels. In the embodiment of fig. 10, each group 23, 25 and 28 comprises three channels.

In the embodiment of figs. 11-14, the first group of channels 23 comprises ten channels 20, while both the second group as well as the third group, 25 and 28 respectively, each comprise only one channel 20.

Unlike the embodiment of fig. 10, which is without the recesses 36, in the embodiment of figs. 11-14 the modular element 10 also comprises, in addition to the recess 36 created in correspondence with the separation portion 31, an additional recess 36’ created in correspondence with the additional separation portion 31 ’.

The recess 36 and the additional recess 36’ are created at the opposite ends 21, 22 of the modular element 10, therefore four recesses 36, 36’ are provided overall, each having a length L, preferably at least double the distance D.

Consequently, the first and second recirculation means 11 and 12 also comprise, in addition to the first and second separation baffle 34, 35, an additional separation baffle 35.

In the example of this embodiment given here, in which only the first recirculation means 11 are shown, it can be observed that the first separation baffle 33 allows to separate the first feed duct 26 from the second feed duct 27, and the additional separation baffle 35 allows to separate the first feed duct 26 from a third feed duct 32, configured to feed a heat transfer fluid to the third group 28 of channels 20. The second recirculation means 12, not shown in this embodiment, will be the same as the first recirculation means, a third recovery duct being provided therein, separate both from the first and also from the second recovery duct.

In this embodiment, therefore, three independent circulation circuits are provided for as many heat transfer fluids.

The variants referred to in embodiments 9a and 9b can also be combined with the example shown in figs. 11-14.

Thanks to the presence of the recess 36 and of the additional recess 36’, the ends of the channels 20 of the first group 23 are separated from the ends of the channels 20 of the second and third groups 25, 28. This is advantageous, since it allows to prevent deformations of the first and second ends 21, 22 of the modular element 10 due to thermal expansions between the first zone 37, into which the channels 20 of the first group 23 flow, the second zone 38, into which the channels 20 of the second group 25 flow, and a third zone 39, into which the channels 20 of the third group 28 flow, caused by the significant difference in temperature of the heat transfer fluids which pass through them.

The first, second and third zones 37, 38 and 39 are projecting portions which project toward the first recirculation means 11 and the second recirculation means 12, respectively, so that the first zone 37 reaches the first feed and recovery ducts 26, 29, the second zone reaches the second feed and recovery ducts 27, 30 and the third zone 39 reaches the third feed and recovery ducts.

The first zone 37 is configured to be inserted into the first slot 14a, the second zone 38 is configured to be inserted into a second slot 14b and the third zone 39 is configured to be inserted into a third slot 14c (fig. 13). The first slot 14a, the second slot 14b and the third slot 14c are created in the front wall 18 of the first and second recirculation means 11, 12 into which the modular elements 10 are engaged. The first slot 14a, the second slot 14b and the third slot 14c are aligned with each other in such a way as to be substantially disposed along the same horizontal plane P. Between the first and second slot 14a, 14b, as well as between the second and third slot 14b, 14c, there is a space in correspondence with which, inside the first and second recirculation means 11, 12, the separation baffles 33, 34 and the additional separation baffle 35 are disposed, and the outside of which the recess 36 and the additional recess 36’ are facing.

The length L of the recess 36 and of the additional recess 36’ is such that their bottom is disposed outside the first and second recirculation means 11, 12 so as to define a cavity 41 between the recesses 36, 36’ and the front wall 18, thanks to which this last wall is not contacted by the separation portion 31 and by the additional separation portion 31 ’.

This configuration is advantageous because in correspondence with the separation portions 31 , 31 ’ it is not necessary to create any sealed coupling between the modular element 10 and the recirculation means 11, 12, thus overcoming the problems of the state of the art.

In the example given here, in which the heat exchanger 100 comprises five modular elements 10 disposed on as many planes P, all parallel to each other, five first slots 14a, five second slots 14b and five third slots 14c are created in the first and second recirculation means 11, 12.

With reference to fig. 14, a variant of the embodiment of figs. 11-13 is described, in which, instead of the presence of the additional separation baffle 35, only a single shaped separation baffle 40 is provided. In this variant, although there are provided three groups 23, 25 and 28 of channels 20 and the three zones 37, 38 and 39, separated by two recesses 36, and into which the channels of the respective groups flow, the heat exchanger only operates with two heat transfer fluids Fl and F2. In this example, in correspondence with the first recirculation means 11, the first zone 37 flows into the first feed duct 26, while the second zone 38 and the third zone 39 flow into the second feed duct 27. Similarly, in correspondence with the second recirculation means 12 (not shown in fig. 14), the first zone 37 flows into the first recovery duct 29, while the second zone 38 and the third zone 39 flow into the second recovery duct 30.

With reference to fig. 15, another embodiment of a modular heat exchange element 10 according to the present invention is described.

In this embodiment, the channels 20 are distributed in such a way as to be distanced from each other by a segment, measured parallel to the transverse axis Y, characterized by having a variable width as a function of the arrangement of the channels 20.

The modular element 10 comprises a first group 23 of channels 20 which are separated from each other by a segment having a first width W 1 , measured parallel to the transverse axis Y. The channels of the first group 23 are configured so that the same first heat transfer fluid passes through them.

The modular element 10 comprises a second group 25 of channels 20 configured so that the same second heat transfer fluid passes through them. The channels of the second group are separated from each other by a segment having a second width W2, measured in a direction parallel to the transverse axis Y. This second width W2 also separates the two adjacent channels, one belonging to the first group 23 and the other belonging to the second group 25.

The modular element 10 also comprises a third group 28 of channels 20 configured so that the same third heat transfer fluid passes through them. The channels of the third group are separated from each other by a segment having the second width W2, measured in a direction parallel to the transverse axis Y. This second width W2 also separates the two adjacent channels, one belonging to the first group 23 and the other belonging to the third group 28.

The second width W2 is greater than the first width Wl, since it is preferably about double the latter. The second width W2 characterizes the separation wall between two different groups of channels 20 and is sized in such a way as to guarantee adequate resistance to the pressures exerted against it by the first heat transfer fluid.

The modular element 10 of this embodiment is extremely versatile since it allows to define the number of channels 20 belonging to the first, second and third group 23, 25 and 28 once the conformation of the first and second recirculation means 11, 12 is known.

This conformation defines the position of the separation portion/s 31 in the modular element 10, which could be placed in correspondence with one of the channels 20 of the second and/or of the third group 25, 28, in particular in the group/s which prove/s to be adjacent to the first group, in order to perform the separation between the groups of channels.

In the example shown in fig. 15, a first example of distribution of the channels 20 is indicated above the modular element, in which the second and third groups 25, 28 each comprise the two outermost channels 20, the separation portion 31 is disposed in correspondence with the third channel 20 starting from the right and from the left, respectively, and the first group 23 comprises five channels 20.

According to another distribution, shown by way of example below the modular element 10 in fig. 15, the second and third groups 25, 28 each comprise only the outermost channel 20, the separation portion 31 is disposed in correspondence with the second channel 20 starting from the right and from the left, respectively, and the first group 23 comprises seven channels.

In a variant of this embodiment, only two groups of channels can be provided, separated by a separation portion 31 , the position of which varies as a function of the conformation of the recirculation means 11, 12.

In another variant of this embodiment, it is provided to create a recess 36 in correspondence with each separation portion 31, since this embodiment can be combined with those described with reference to figs. 7-14. Two different operating modes of the heat exchanger according to the present invention are described below.

The studies and modeling carried out have simulated the operation of the heat exchanger 100 at least in these operating modes, in particular in a first operating mode MOI, also called “Adiabatic mode”, and in a second operating mode MO2, also called “Heat recovery mode”. This makes the heat exchanger 100 very flexible in its use, and is achieved thanks to the fact that the modular heat exchange element 10 exploits the heat exchange between three fluids, that is, between the first heat transfer fluid Fl, the second heat transfer fluid F2 and an air flow that sweeps the modular heat exchange element 10.

The air flow can originate from a natural or forced convection, for example by means of a suitable ventilation device. Furthermore, the air that sweeps the modular heat exchange element 10 usually has a higher temperature than the second temperature T2 of the second heat transfer fluid F2, but lower than the first temperature T1 of the first heat transfer fluid Fl.

In the first operating mode MOI, the modular heat exchange element 10 is disposed in such a way that the air flow first sweeps the second group 25 of channels 20, that is, it comes from the right side with reference to figs, from 3 to 7, 10, 11 and 15, as schematically indicated by a first arrow FR1 in these drawings. By doing so, the air cools down and its temperature decreases even by 15 Kelvin before reaching the first group 23 of channels 20; this temperature reduction advantageously occurs regardless of the relative humidity content present in the ambient air. This allows to maximize the heat exchange that occurs between the air flow and the first heat transfer fluid F 1 which circulates inside the first group 23 of channels 20, thus allowing to further reduce its temperature T1.

Therefore, an operation comparable to that of “adiabatic” type systems, well known to the people of skill in the art, is achieved, in which the air entering the heat exchanger is cooled in order to improve its heat exchange capacity. For example, these known adiabatic systems provide to use evaporative panels on which water is sprayed at a suitable temperature.

Furthermore, in addition to the heat exchanges which are generated between the air flow and the two groups 23 and 25 of channels 20, there is also an additional heat exchange, predominant with respect to those just described, which occurs between the first and the second heat transfer fluids Fl, F2 which circulate respectively in the first group 23 and in the second group 25 of channels 20.

In this regard, the Applicant has carried out various studies and modeling with the aim of defining and/or characterizing an optimal sizing relation linked to the first operating mode MOI, relating:

- the performance of the modular heat exchange element 10 (ordinate), determined as the ratio between the thermal power dissipated by the first heat transfer fluid F 1 if the second group 25 of channels 20 is in an operating condition (that is, the second heat transfer fluid F2 passes through it), and the thermal power dissipated by the first heat transfer fluid Fl if the second group 25 of channels 20 is in a stop condition (that is, no heat transfer fluid passes though it); and

- the ratio between the second area A2 and the total area AT (abscissa).

By means of this relation, shown graphically in fig. 17 with a first dashed curvilinear strip, delimited at the upper and lower part by increasing monotone curves, it was possible to identify a first optimal sizing interval, expressed in terms of ratios between the second area A2 and the total area AT. Furthermore, from the results obtained it can be seen that with the modular heat exchange element 10 it is possible to have exchanged thermal power performance even much higher than the maximum performance that can be achieved with known adiabatic systems, which are indicated with a dotted strip in fig. 17. Please note that known adiabatic systems use, for example, evaporative panels wetted with cold water to increase the respective performance, which, unlike the present invention, is strongly affected by the external environmental conditions, and in particular by the relative humidity of the air.

We must clarify that the studies and modeling were conducted with a substantially constant temperature and speed of the air flow; a possible variation in the temperature or in the speed of the air flow could significantly impact the values obtained in the ordinate.

In the second operating mode MO2, the modular heat exchange element 10 is disposed in such a way that the air flow first sweeps the first group 23 of channels 20, that is, it comes from the left side with reference to figs, from 3 to 7, 10, 11 and 15, as schematically indicated by a second arrow FR2 in these drawings. By doing so, the air heats up and its temperature increases, for example, even by 25 Kelvin (at atmospheric pressure) before reaching the second group 25 of channels 20. We must clarify that the value of this temperature increase naturally depends on the temperatures T1 and T2 of the first and second heat transfer fluid Fl and F2, respectively; therefore, there could be increases in temperature even higher than the one indicated above.

This allows to maximize the heat recovery through the second group 25 of channels 20, thus allowing the second heat transfer fluid F2 to increase its temperature T2 maximally. In particular, heat recovery is achieved both with the heat exchange which occurs between the air flow and the second group 25 of channels 20, and also with the heat exchange which occurs between the first and second heat transfer fluids Fl, F2, which circulate in the first and second group 23 and 25 of channels 20, respectively. As for the first operating mode MOI, the heat exchange between the first group 23 and the second group 25 of channels 20 is predominant compared to that with the air flow.

Also in this case, the Applicant has carried out various studies and modeling with the aim of defining and/or characterizing an optimal sizing relation linked to the second operating mode MO2, this time relating:

- the efficiency of the modular heat exchange element 10 (ordinate), indicated as a percentage, is determined as the ratio between the heat recovered by the second group 25 of channels 20 and the thermal power dissipated by the first heat transfer fluid Fl if the second group 25 of channels 20 is in an operating condition (that is, the second heat transfer fluid F2 passes through it); and

- the ratio between the second area A2 and the total area AT (abscissa). By means of this relation, shown graphically in fig. 18 with a second dashed curvilinear strip, delimited at the upper and lower part by increasing monotone curves, it was possible to identify a second optimal sizing interval, expressed in terms of ratios between the second area A2 and the total area AT. Furthermore, from the results obtained it can be seen that with the modular heat exchange element 10 it is possible to have efficiency values that are even much higher than the maximum efficiency values achievable with modular heat exchange elements with a single heat transfer fluid, indicated with a dotted strip in fig. 18.

We must clarify that the studies and modeling were conducted with a constant air flow temperature. Also in this case, a possible variation in the temperature or in the speed of the air flow could significantly impact the values obtained in the ordinate.

However, the sizing relations relating to the two operating modes MOI and MO2 of the modular heat exchange element 10, represented in the graphs of figs. 16 and 17, respectively, provide only a partial indication of the optimal sizing of the second group 25 of channels 20. This is due both to the fact that the relations thus obtained only take into account the respective operating mode MOI or MO2, and also to the fact that the performance parameters used are closely linked to the values of the second area A2; in fact, observing the graphs in figs. 17 and 18, the performance parameters, expressed in terms of maximum values, tend to increase with the increase in the ratio between the second area A2 and the total area AT.

For this reason, the Applicant has carried out further studies and modeling with the aim of defining and/or characterizing an additional optimal sizing relation, which can take into account both operating modes MOI and MO2, as well as performance parameters which are not affected by the variability of the ratio between the second area A2 and the total area AT, thus relating:

- the performance of the modular heat exchange element 10 in absolute terms, determined as the thermal power exchanged by the modular heat exchange element 10 related to the maximum obtainable value of this exchanged thermal power (ordinate);

- the ratio between the second area A2 and the total area AT (abscissa).

In particular, the graph shown in fig. 19 was obtained by calculating, for each operating mode MOI and MO2, the thermal power exchanged by the modular heat exchange element 10 with a given ratio between the second area A2 and the total area AT, dividing it by the maximum obtainable value of thermal power exchanged by the modular heat exchange element 10.

By means of this additional relation, shown graphically with a first dashed curve for MOI and with a second dashed curve for MO2, it was possible to identify an optimal sizing interval, expressed in terms of ratios between the second area A2 and the total area AT.

In accordance with another aspect of the present invention, as shown in fig. 19, the best heat exchange performance is achieved when the ratio between the second area A2 and the total area AT is comprised preferably between about 0.05 and 0.5, more preferably when this ratio is comprised between about 0.1 and 0.35.

In this regard, observing the first dashed curve (MOI), although the best heat exchange performance is achieved with a ratio between A2 and AT equal to about 0.35, a reduction in this performance by about 10% can also be provided, in order to advantageously achieve a significant saving in the consumption of the second heat transfer fluid F2. Specifically, observing the graph of fig. 19, with a 10% reduction in performance there is a reduction in the ratio between A2 and Al; this implies a reduction in the second area A2 of the second group 25 of channels 20 in which the second heat transfer fluid F2 flows, which is usually cold water, possibly combined with glycol, consequently resulting in a saving of water during use of the modular heat exchange element 10.

In accordance with possible embodiments of the present invention, the modular heat exchange elements 10 are extruded elements made of plastic materials, for example polyethylene, polypropylene or suchlike.

It is clear that modifications and/or additions of parts may be made to the heat exchanger 100, and in particular to the modular heat exchange element 10, as described heretofore, without departing from the field and scope of the present invention, as defined by the claims.

For example, if several separation portions 31 are present, the sizes D and H of the latter could also be different from one separation portion 31 to another. For example, at least one separation portion 31 could have symmetrical or asymmetrical narrowings or recesses with respect to the regular thickness of the modular heat exchange element 10, defined - as previously disclosed - by the height H.

Furthermore, as an alternatively to what is shown in the drawings, the lateral walls 17 and 19 of the modular heat exchange element 10 could be flat or have other suitable shapes. It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of heat exchanger, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby. In the following claims, the sole purpose of the references in brackets is to facilitate their reading and they must not be considered as restrictive factors with regard to the field of protection defined by the same claims.

Claims

27 CLAIMS

1. Heat exchanger (100) comprising a plurality of heat exchange elements (10) which are fluidically connected to first recirculation means (11) and second recirculation means (12) disposed respectively at entry to and at exit from said heat

5 exchange elements (10), wherein:

- said first and second recirculation means (11, 12) each comprise at least a first and a second duct (26, 27, 29, 30), for feed and recovery, respectively, separated from each other by respective separation baffles (33, 34),

- each element of said plurality of heat exchange elements (10) comprises both a 10 plurality of circulation elements (20) divided into at least a first group (23), in which a first heat transfer fluid (Fl) flows, and into a second group (25), in which a second heat transfer fluid (F2) flows, and also at least one separation portion (31) interposed between said first group (23) and said second group (25), said heat exchanger (100) being characterized in that:

15 - each modular element (10) comprises at least one recess (36) made in correspondence with said separation portion (31) so as to define at least a first zone (37) and a second zone (38) of said heat exchange element (10) between which said recess (36) is interposed, into which said circulation elements (20), belonging to said first group (23) and to said second group (25), respectively, flow,

20 - said first and second recirculation means (11, 12) each comprise a front wall (18) in which at least a first slot (14a) and a second slot (14b) are made, each configured to receive said first zone (37) and said second zone (38), respectively, in a sealed manner, wherein said recess (36) is configured to be disposed aligned with said separation 25 baffles (33, 34) at least in correspondence with said front wall (18).

2. Heat exchanger (100) as in claim 1, characterized in that:

- said first recirculation means (11) also comprise a third feed duct (32) and said second recirculation means (12) also comprise a third recovery duct,

- each of said modular elements (10) also comprises both a third group (28) of said

30 channels (20) inside which said second heat transfer fluid (F2) or possibly a third heat transfer fluid can flow, and also an additional separation portion (31 ’) in correspondence with which an additional recess (36’) is made to separate said third group (28) from the first and second groups (23, 25).

3. Heat exchanger (100) as in claim 2, characterized in that said first recirculation means (11) and said second recirculation means (12) each comprise an additional separation baffle (35), wherein said separation baffles (33, 34, 35) allow to separate said first feed and recovery ducts (26, 29) from said second and third feed and recovery ducts (27, 30, 32).

4. Heat exchanger (100) as in claim 3, characterized in that said additional recess (36’) is configured to be disposed aligned with said additional separation baffle (35) at least in correspondence with said front wall (18), so as to define a third zone (39) of said heat exchange element (10), into which said circulation elements (20) belonging to said third group (28) flow, and in that at least a third slot (14c) is made in said front wall (18) which is configured to receive said third zone (39) in a sealed manner.

5. Heat exchanger (100) in any claim from 2 to 4, characterized in that said plurality of circulation elements (20) extends parallel to a longitudinal axis (Z), and in that said separation portion (31) and said additional separation portion (31 ’) extend for a distance (D) measured along a transverse axis (Y) which is orthogonal to said longitudinal axis (Z).

6. Heat exchanger (100) in claim 5, characterized in that said recess (36) and said additional recess (36’) extend for a length (L) which is at least double said distance (D), so that the bottom of said recess (36) is disposed outside said first and second recirculation means (11, 12) so as to define a cavity (41) between said recess (36) and said front wall (18).

7. Heat exchanger (100) as in any claim from 2 to 6, characterized in that said separation portion (31) and said additional separation portion (31 ’) extend between two opposite ends (21, 22) of said plurality of modular elements (10) and can be conformed as a solid or hollow bar, in the latter case being shaped like one of said circulation elements (20).

8. Heat exchanger (100) as in any claim hereinbefore, characterized in that said circulation elements (20) are distributed in such a way as to be distanced from each other by a segment, measured parallel to a transverse axis (Y), which has a variable width: said circulation elements (20) of said first group (23) are separated from each other by a segment having a first width (Wl), and said circulation elements (20) of said second group (25) are separated from each other, as well as from said circulation elements (20) of said first group (23), by a segment having a second width (W2), which is greater than said first width (Wl).

9. Method for assembling a heat exchanger (100) comprising a plurality of heat exchange elements (10) which are fluidically connected to first recirculation means (11) and to second recirculation means (12) disposed respectively at entry to and at exit from said heat exchange elements (10), wherein each element of said plurality of heat exchange elements (10) comprises both a plurality of circulation elements (20) divided into at least a first group (23), in which a first heat transfer fluid (Fl) flows, and into a second group (25), in which a second heat transfer fluid (F2) flows, and also at least one separation portion (31) configured to separate said first group (23) from said second group (25), distancing them by a certain distance (D), said method being characterized in that it comprises the steps of:

- preparing one or more slots (14a, 14b) in a front wall (18) of said first recirculation means (11) and of said second recirculation means (12),

- assembling said heat exchange elements (10) to said first and second recirculation means (11, 12) by inserting into a respective one of said slots (14a, 14b) a first zone (37) and a second zone (38) of said heat exchange element (10), into which said channels (20) belonging to said first group (23) and to said second group (25), respectively, flow,

- making at least one recess (36) in correspondence with said separation portion (31), wherein said recess (36) separates said first zone (37) from said second zone (38),

- during said assembling it is provided that said recess (36) is disposed outside said first and second recirculation means (11, 12), aligned with a respective separation baffle (33, 34) at least in correspondence with said separation wall (18), wherein said respective separation baffle (33, 34) separates the inside of said first and second recirculation means (11,12) into at least two ducts (26, 27, 29, 30), for feed and recovery, respectively, into which the channels (20) of said first and second group (23, 25) flow,

- permanently joining said first zone (37) and said second zone (38) to said front wall (18) in correspondence with said slots (14a, 14b) with a high temperature joining method.

10. Method as in claim 9, characterized in that said high temperature joining method comprises a brazing step, and in that said recess (36) and said one or more slots (14a, 14b) are made by means of mechanical machining, in particular milling or shearing, or by means of laser processing.

11. Heat exchanger (100) comprising a plurality of heat exchange elements (10) which are fluidically connected to first recirculation means (11) and second recirculation means (12) disposed respectively at entry to and at exit from said heat exchange elements (10), wherein said modular heat exchange elements (10) develop along a longitudinal axis (Z) and each comprises both a plurality of circulation elements (20) each having a certain cross section and being divided into at least a first group (23) of said circulation elements (20) in which a first heat transfer fluid (Fl) flows having a first operating temperature (Tl), and at least a second group (25) of said circulation elements (20) in which a second heat transfer fluid (F2) flows having a second operating temperature (T2), wherein said first operating temperature (Tl) is greater than said second operating temperature (T2), and wherein said first group (23) and said second group (25) of said circulation elements (20) have a respective hydraulic diameter, and also at least one separation portion (31) configured to separate said first group (23) from the said second group (25) of said circulation elements (20), distancing them by a certain distance (D), said modular heat exchange element (10) being characterized in that said distance (D) has a certain size, measured along a transverse axis (Y) substantially perpendicular to said longitudinal axis (Z), which is inversely proportional to a hydraulic diameter (DIIAI) of said circulation elements (20) of said first group (23).

12. Heat exchanger (100) as in claim 11, characterized in that said separation portion (31) has a certain size (H), measured in a direction parallel to a positioning axis (X) substantially perpendicular to said longitudinal axis (Z) and to said transverse axis (Y), which remains constant at least along said longitudinal axis (Z).

13. Heat exchanger (100) as in claim 12, characterized in that said certain size (H) of said separation portion (31) substantially defines the thickness of each of said modular heat exchange elements (10).

14. Heat exchanger (100) as in any claim from 11 to 13, characterized in that said circulation elements (20) of said first group (23) and of said second group (25) are shaped in such a way as to have a shape and sizes such that the circulation 31 elements (20) of a same group, that is, of said first group (23) and of said second group (25), have a constant hydraulic diameter, and in that the ratio between said hydraulic diameter (DIIAI) of said circulation elements (20) of said first group (23) and a hydraulic diameter of said circulation elements (20) of said second group (25) is comprised between 0.2 and 1.

15. Heat exchanger (100) as in claim 14, characterized in that for high pressures (Pl) exerted by said first heat transfer fluid (Fl) in said first group (23) of said circulation elements (20), comprised preferably between about 45 and about 100 bar, said certain size of said distance (D) varies on average between 2 and 4.5 times said hydraulic diameter (DII I) of said circulation elements (20) of said first group (23).

16. Heat exchanger (100) as in claim 14 or 15, characterized in that for medium pressures (P2) exerted by said first heat transfer fluid (Fl) in said first group (23) of said circulation elements (20), comprised preferably between about 15 and about 45 bar, said certain size of said distance (D) varies on average between 1 and 2 times said hydraulic diameter (Dl i) of said circulation elements (20) of said first group (23).

17. Heat exchanger (100) as in any claim from 14 to 16, characterized in that for low pressures (P3) exerted by said first heat transfer fluid (Fl) in said first group (23) of said circulation elements (20), comprised preferably between about 0.1 and about 15 bar, said certain size of said distance (D) varies on average between 0.3 and 1 times said hydraulic diameter (Dl i) of said circulation elements (20) of said first group (23).

18. Heat exchanger (100) as in any claim from 11 to 17, wherein the sum of each certain cross section of said circulation elements (20) of said first group (23) defines a first area (Al), wherein the sum of each certain cross section of said circulation elements (20) of said second group (25) defines a second area (A2), and wherein the sum of said first area (Al) and said second area (A2) defines a corresponding total area (AT), said modular heat exchange element (10) being characterized in that the ratio between said second area (A2) and said total area (AT) is comprised preferably between about 0.05 and 0.5, more preferably between about 0.1 and 0.35.

19. Use of a heat exchanger (100) as in any claim from 11 to 18, configured to 32 function at least in a first operating mode (MOI) in which an air flow first sweeps said second group (25) of circulation elements (20), so that the cooling of said air flow allows to maximize the heat exchange between said air flow and said first heat transfer fluid (Fl) circulating inside said first group (23) of circulation elements (20).

20. Use of a heat exchanger (100) as in any claim from 11 to 18, configured to function at least in a second operating mode (MO2) in which an air flow first sweeps said first group (23) of circulation elements (20), so that the heating of said air flow allows to maximize the heat absorbed by said second heat transfer fluid (F2) circulating inside said second group (25) of circulation elements (20).