EP2980517B1

EP2980517B1 - Process of assembling a modular exchanger

Info

Publication number: EP2980517B1
Application number: EP15176465.1A
Authority: EP
Inventors: Gianbattista Pirola; Mario Biancospino
Original assignee: Indesit Co SpA
Current assignee: Whirlpool EMEA SpA
Priority date: 2014-07-31
Filing date: 2015-07-13
Publication date: 2016-11-09
Anticipated expiration: 2035-07-13
Also published as: EP2980517A1

Description

The present invention relates to a process for assembling a heat exchanger for household appliances and a process for assembling a household appliance, in particular a household drying appliance, comprising the exchanger assembled in accordance with the aforementioned assembly process.
The present invention also relates to a household appliance, in particular a household drying appliance, comprising the exchanger assembled in accordance with the aforementioned assembly process.
The exchanger assembled according to the process in accordance with the present invention can be used in a household drying appliance, in particular of the condensation type.
Cross-flow heat exchangers are known for household appliances starting from one or more sheets of metal material, see e.g US 2003093900 disclosing a process in accordance with the preamble of claim 1. The sheets are first cut starting from sheet metal to obtain the pre-chosen dimensions and are subsequently appropriately shaped. The shaping defines surfaces having for example toothed profiles characterised in that they have a regular alternation of indentations and protuberances, or "accordion-shaped" profiles, which have a zig-zag or substantially undulated pattern. Such shaped profiles define channels for the passage of fluid within the condenser. In cross-flow heat exchangers, along the height of the exchanger such shaped sheets are arranged so as to define conduits extending along perpendicular directions to one another and defining the advancement directions of the flows internal to the exchanger.
The coupling between shaped sheets is normally performed through welding or brazing.
However, the exchangers just described have some drawbacks.
The known exchangers have a long and complex production process; for example, if the shaping process of the thermal exchange sheets is not performed appropriately, the free fluid passage sections may be different from the designed ones and therefore the efficiency of the exchanger itself may be undermined.
The known exchangers are also difficult and expensive to assemble.
The assembly of such exchangers also requires specialist labour for performing the welding.
A principal object of the present invention is to resolve one or more of the problems found in the prior art.
An object of the present invention is to provide a simple and rational assembly process of an exchanger.
A further object of the present invention is to reduce the assembly times and costs of an exchanger.
An object of the present invention is also to provide an exchanger and a household appliance comprising such exchanger that are compact, efficient and cheap.
It is also an object of the present invention to provide an assembly process of a household appliance comprising an exchanger assembled in accordance with the aforementioned assembly process that is simple and quick to implement.
These objects and others, which will appear more clearly from the following description, are substantially reached by an assembly process of an exchanger for household appliances according to claim 1 and a household appliance according to claim 9.
There now follows, by way of non-limiting example, a detailed description of one or more preferred embodiments of the invention, in which:

figure 1 represents a schematic view of a dryer, for example of the condensation type;
figure 2 represents a heat exchanger assembled according to the process in accordance with the present invention;
figure 3 represents a beam adapted to house two thermal exchange sheets;
figures 4, 5 and 6 represent respective steps of the assembly process of the exchanger of figure 3;
figures 7 and 8 represent respective variants in sectional view of a heat exchanger in accordance with the present invention;
figure 9 represents a detail of the coupling between thermal exchange sheets and beams.

With reference to figure 1, 1 indicates a household appliance, for example, a dryer of the condensation type, in accordance with the present invention.
The dryer comprises an external box body 2 and a drum 3 destined to receive garments to be dried. The drum 3 is housed within the box body 2 and is for example rotatably engaged with respect to the latter.
The box body 2 has an overall parallelepiped shape and comprises a lateral wall having sides, a front wall 22 transversal to each side, a rear wall 23 parallel to the front wall 22 and transversal to the sides, and an upper wall 24 transversal to the lateral wall. At the bottom the box body 2 may be at least partially open. It should be noted that, although the box body 2 is normally parallelepiped shaped, other shapes are not excluded in principle.
With respect to the drum 3, it is configured to rotate about a horizontal axis and is accessible from the outside of the box body 2 through a door 4 arranged and hinged at the front wall 22 of the box body 2. In an alternative embodiment, not illustrated, the drum 3 can be made accessible by a door hinged at the upper wall 24.
To allow the garments to dry, the condensation dryer comprises a first drying circuit intended to process a first fluid, usually comprising appropriately heated air (also called "hot air" in the present description), a second cooling circuit intended to process a second fluid, usually comprising air at room temperature (also called "cold air" in the present description), and a condenser 6 that places a length of the first and of the second circuit in thermal communication.
Preferably, the condenser 6 is an exchanger assembled according to the assembly process in accordance with the present invention, which will be described in detail below.
The condenser 6 is arranged at a lower portion of the household appliance 1, below the drum 3 and is for example positioned behind the front wall 22 of the box body 2. The condenser 6 allows thermal exchange between the drying fluid and the cooling fluid in order to reduce the humidity of the drying fluid downstream of the drum 3; for that purpose the condenser 6 has, as can be seen in figure 2, a first inlet 61 and a first outlet 62 for the drying fluid and a second inlet 63 and a second outlet 64 for the cooling fluid.
The first inlet 61 and the first outlet 62 are defined at a first pair of opposite walls of the condenser 6 along a prevalent extension direction of the condenser; the drying fluid passage conduits extend interposed between the first inlet 61 and the first outlet 62.
The second inlet 63 and the second outlet 64 are defined at a second pair of opposite walls of the condenser 6 perpendicular to the walls of the first pair of walls; the cooling fluid passage conduits extend interposed between the second inlet 63 and the second outlet 64.
The condenser 6 is of the "air-air" type, preferably cross-flow, and therefore the drying fluid and cooling fluid passage conduits respectively define two bunches of advancement directions of the respective fluids within the condenser 6 developing respectively between the first inlet 61 and the first outlet 62 and between the second inlet 63 and the second outlet 64 and perpendicular to one another.
From a construction point of view, series of cooling fluid passage conduits and series of drying fluid passage conduits are alternatively arranged within the condenser 6 in a vertical direction.
The dryer further comprises a condensation collection sump 7 placed below the condenser 6, a condensation collection tank 8 arranged for example at an upper front portion of the household appliance and a pump 9 configured to send the condensation, through an appropriate delivery pipe 10, from the sump 7 to the collection tank 8. The collection sump 7 and the collection tank 8 may also be placed in fluid communication through a return pipe 20, which is placed at the lateral wall of the collection tank 8 at a height defining an overflow condition of the tank 8. When the level of condensation within the collection tank 8 exceeds such overflow height, the excess condensation returns towards the collection sump 7 by means of the return pipe 20.
The collection tank 8 is accessible for example from the front wall 22 of the dryer to be extracted and periodically emptied. Preferably, the pump 9 is controlled by an appropriate control system for having continuous operation under operating conditions of the household appliance.
With regard to the first circuit, it comprises a first fan 11, a heating element 12, such as an electric resistance, and a filter 13. Under operating conditions of the dryer, the first fan 11 circulates the drying fluid within the first circuit into the drum 3 in order to dry the garments contained therein. The drying fluid, crossing the rotating drum 3, enters into contact with the garments at least partially removing the moisture; after crossing the drum 3, the drying fluid leaves it with a higher moisture level with respect to that contained when it enters. The hot and moist air at the outlet from the drum 3 is then filtered through the filter 13 to remove fluff or other undesired particles potentially present in the flow of drying air. The filter 13 is usually arranged at a front portion of the household appliance 1, below the access door 4 to the drum 3, as illustrated in figure 1. Downstream of the filter 13 a conduit extends that conveys the hot and moist air into the condenser 6 at the first inlet 61. Such air flow, crossing the condenser 6, exchanges heat with the cooling fluid, causing the condensation of the moisture contained in the drying fluid. In the heat exchange, the flow of hot air is cooled, while the flow of cold air is heated. After crossing the condenser 6, the drying fluid is heated by means of the heating element 12 before being conveyed and then re-introduced into the drum 3.
The first circuit is preferably a closed circuit, within which the air leaves the drum 3 hot and moist and is then re-introduced into the drum hot and dry, i.e. with lower moisture than the moisture contained by the hot air leaving the drum 3.
The cooling fluid is in turn processed within the second circuit, which comprises a second fan 14 configured to aspirate the cooling fluid from the environment in which the dryer is installed. For this purpose, the second circuit envisages a suction aperture of the cooling fluid into the box body 2 and a draining portion of the cooling fluid coming out of the box body 2.
Preferably, the second fan 14 is of the centrifugal type and aspirates the air along the direction of the axis of the impeller, before spinning it sending it towards the second outlet 63 in the condenser 6.
The exchanger 6 is assembled based on a plurality of thermal exchange sheets 30 and a plurality of pairs of beams 40 with a prevalently longitudinal extension.
The thermal exchange sheets 30 have a quadrilateral conformation and may for example be square or rectangular. The sheets 30 have a pair of longitudinal edges 50 parallel and opposite to each other and a pair of transversal edges 60, extending in the perpendicular direction to the longitudinal edges 50, also parallel and opposite to one another.
From a material point of view, the thermal exchange sheets 30 may be made of metal, preferably aluminium.
According to the assembly process in accordance with the present invention the thermal exchange sheets 30 may be reciprocally overlapping and constrained by pairs of beams 40.
The beams 40 may have a substantially curved profile, for example, substantially "C"-shaped, as illustrated in figure 3. Advantageously, the beams 40 are made of plastic, in particular of polymeric material.
In order to constrain the thermal exchange sheets 30, the beams 40 have one or more seats 70; preferably, each beam 40 has at least one seat 70 for each sheet 30 destined to be coupled thereto. For example, each beam 40 has at least a first and a second seat 701, 702 reciprocally opposite one another, for example they are afforded at the terminal portions of the "C" outline. Each seat 70 internal to the beams 40 extends longitudinally with respect to the prevalent extension direction of the beams 40 and defines a guide adapted to facilitate the insertion of the sheets 30 within it. Preferably, in a cross-section of the beam, the seat has a lower or substantially equal height with respect to the thickness of the sheets. In order to facilitate the coupling between beams 40 and sheets 30, the seats 70 can be countershaped with respect to the edges of the thermal exchange sheets 30. Advantageously, each seat 70 has a first and a second guide surface 703, 704 opposite one another and an abutment surface 705 interposed between the first and the second guide surface 703, 704 and transversal thereto. Substantially, upon inserting the edges of the thermal exchange sheets 30 into the respective seats 40, the first and the second guide surface 703, 704 are adapted to guide the advancement of the thermal exchange sheet 30 into the seat 70 until it comes into contact with the abutment surface 705, which defines an end stroke portion of the seat 70.
The beams 40 may have corners 41 configured to facilitate their engagement to the thermal exchange sheets 30 and coupling to the adjacent beams 40, i.e. to beams 40 engaged to a same thermal exchange sheet 30; in particular, corners 41 of adjacent beams 40 may be countershaped. For example, beams 40 coupled respectively to longitudinal edges 50 and to transversal edges 60 of thermal exchange sheets 30 of two adjacent modular elements 80 can be coupled at respective countershaped corners 41, as illustrated in figure 9. Preferably the countershaped corners 41 of the longitudinal beams 50 and of the transversal beams 60 are abuttingly positioned against each other, so as to guarantee perpendicularity between the respective development directions, as illustrated in figure 9.
The beams 40 may also have, in proximity to the first and/or the second seat 701, 702, one or more guide portions 42 for the thermal exchange sheets 30. The guide portions 42 may be arranged above and below each seat 70 of the beams 40 (see figure 9) and extend longitudinally with respect to the beams 40 and in a substantially perpendicular direction to the abutment surface 705 of the seat 70 in proximity to which they are defined. Upon the engagement of the beams 40 to the thermal exchange sheets 30, the guide portions 42 are configured to guide the thermal exchange sheets 30 in their advancement towards the seats 70. The guide portions 42 are also configured to be abuttingly positioned with the portions of the thermal exchange sheets 30 arranged in proximity to the edges engaged to the beams 40, as illustrated in figure 9. The abutment of such guide portions 42 on the thermal exchange sheets 30 guarantees the stable engagement of the sheets 30 to the beams 40 and parallelism between sheets 30.
In an embodiment in which the thermal exchange sheets 30 are all square shaped, all the beams 40 may be the same length, whereas in an embodiment in which the thermal exchange sheets 30 are all rectangular shaped, pairs of beams 40 may be provided having a first length and pairs of beams 40 having a second length that is greater than the first length. The beams 40 of the first length are intended to be coupled to the transversal edges 60 of the rectangular thermal exchange sheets 30 (corresponding to the short sides of the rectangular perimeter of the sheets), whereas the beams 40 of the second length are intended to be coupled to the longitudinal edges 50 of the rectangular thermal exchange sheets 30 (corresponding to the long sides of the rectangular perimeter of the sheets).
In both embodiments, the beams 40 of a same pair of beams are the same length as each other.
The assembly process of the exchanger 6 comprises one or more engagement steps of the pairs of beams 40 to overlapped thermal exchange sheets 30; such steps, which will be described in detail below, define fluid passage volumes interposed between the thermal exchange sheets 30.
Upon assembly, overlapping sheets 30 are reciprocally spaced out from each other to facilitate their insertion at the seats 70 of a same beam 40; for example, two overlapping sheets 30 are illustrated in figure 4.
The coupling steps between sheets 30 and beams 40 can be performed with the aid of appropriate machinery, for example, automatic or semi-automatic machines, or manually by operators.
The fluid passage volumes defined between the thermal exchange sheets 30 are laterally delimited by the beams 40 and above and below by two thermal exchange sheets 30 and may therefore have a substantially parallelepiped shape. For example, figure 2 illustrates a cross-flow exchanger 6 equipped with three fluid passage volumes, wherein the volume positioned above and the volume positioned below define a first fluid advancement direction, while the volume interposed to them defines a second fluid advancement direction perpendicular to the first.
The assembly process of the exchanger 6 comprises a step consisting of assembling one or more modular elements 80 by coupling the beams 40 with the thermal exchange sheets 30. A modular element 80 is for example illustrated in figure 5. Each modular element 80 constitutes a row of the exchanger 6 and therefore defines a passage volume for a thermal exchange fluid; in an exchanger 6 comprising various rows, there are various modular elements 80, as illustrated for example in figures 2, 7 and 8.
Preferably, the assembly process of the exchanger 6 comprises the assembly of a plurality of modular elements 80, each of which is obtained by engaging two pairs of beams 40 to the respective longitudinal edges 50 of two overlapped thermal exchange sheets 30, and subsequently coupling the modular elements 80 to one another through the engagement of pairs of beams 40 at the free transversal edges 60 of the thermal exchange sheets 30.
The assembly process of an exchanger 6 is described below with reference to a first and a second modular element 801, 802; however, such process should not be considered limited to the assembly of an exchanger 6 comprising only two modular elements 80, but aims to exemplify the process itself.
The assembly process of an exchanger 6 comprises for example the assembly of a first modular element 801 starting from a first and a second thermal exchange sheet 301, 302, and a first pair of beams 401, illustrated in figure 4 in a preliminary step to the coupling of the sheets 301, 302 themselves.
The assembly of the first modular element 801 envisages the engagement of the first pair of beams 401 to the first and the second sheet 301, 302 at the respective longitudinal edges 50; a first modular element 801 assembled in such a way is for example illustrated in figure 5. The first modular element 801 defines a first passage volume for a first thermal exchange fluid.
The process further comprises the assembly of a second modular element 802, created by engaging a third pair of beams 403 to a third and to a fourth sheet 303, 304 at the respective longitudinal edges. The second modular element 802 defines a further first passage volume for the first thermal exchange fluid.
The first and the second modular element 801, 802 can be subsequently overlapping at a reciprocal distance from one another so that the second and the third sheet 302, 303 are respectively facing one another, as illustrated in figure 6. The two modular elements 801, 802 are then coupled to one another through the engagement of a second pair of beams 402 to the second and to the third sheet 302, 303 at the respective free transversal edges 60. For example, figure 2 illustrates the exchanger 6 resulting from the aforementioned coupling.
The coupling of the first and the second modular element 801, 802 defines, between the second and the third sheet 302, 303, a second passage volume for the second thermal exchange fluid, laterally delimited by the second pair of beams 402. As illustrated in the assembled item in figure 2, the beams of the first and the third pair of beams 401, 403 extend parallel to one another and transversally with respect to the beams of the second pair of beams 402, defining a structure adapted to allow, under conditions of use of the exchanger 6, a cross flow of the first and the second thermal exchange fluid. Since the modular elements 80 are comprised of two thermal exchange sheets 30 coupled by a pair of beams 40, the aforementioned coupling between the first and the second modular element 801, 802 further defines a third modular element 803, which extends between the second and the third sheet 302, 303 and is laterally delimited by the second pair of beams 402.
In one embodiment, before coupling one or more pairs of beams to the thermal exchange sheets 30, the seats 70 of the beams are widened, hence facilitating the insertion of the thermal exchange sheets 30. The widening may be mechanical or thermal; in the former case a dilation force may for example be applied, which tends to distance the first and the second surface 703, 704 of the seats 70 internal to the beams 40, for example through elastic deformation of the beams, while in the second case the widening of the seats may be due to heating the beams 40. Following the widening of the seats 70, the edges of the sheets 30 are inserted into them; after this step, the seats 70 are tightened onto the inserted edges of the sheets 30. The tightening of the seats 70 onto the edges inserted therein consists of the contraction of the previously dilated seats, so that the first and the second surface 703, 704 of the seats at least partially abut and exert pressure on the edges of the sheets 30. Like the widening, the tightening may also be mechanical or thermal; in the former case, the tightening may be due to the removal of the dilation force previously applied.
In the case of thermal tightening, the process may comprise a cooling step of the beams 40 which allows their contraction; this step may be performed at ambient temperature or a lower temperature, for example by means of an appropriate refrigerated environment. The cooling of the profiles 40 engaged to the sheets allows the contraction of the previously widened seats 70, which close onto the respective inserted edges of the sheets 30, abutting thereon and exerting a compression force distributed at the surface of the edges inserted in the seats 70. Advantageously, in the embodiment that envisages the thermal widening of the beams 40 and tightening of the beams 40 on the edges of sheets, the beams 40 may be made of plastic material.
The tightening of the beams 40 on the sheets 30 guarantees, as well as stable coupling between beams and sheets, also fluid sealing at the edges of the sheets coupled to the beams.
In accordance with another embodiment, the engagement steps between thermal exchange sheets and beams may be performed by co-moulding the beams 40 at the edges of the sheets 30 themselves. In substance, the sheets 30 are reciprocally overlapped and then one or more pairs of beams 40 are co-moulded, externally to the sheets.
Advantageously, the co-moulding may be of the metal-plastic type, wherein the thermal exchange sheets 30 are made of metal and the beams 40 are made of plastic.
Following the assembly of the exchanger 6, a first head can be coupled to it, for example at the first inlet 61. The first head may be equipped with an extraction handle of the exchanger 6, which is configured to allow the extraction of the exchanger 6 from a household appliance 1 within which the exchanger 6 can be assembled. Advantageously the handle is configured to allow the extraction of the exchanger 6 in the perpendicular direction to a front wall 22 of the box body 2 of the household appliance 1.
A second head opposite the first head can also be coupled to the exchanger 6; for example, the first and the second head can be respectively coupled at opposite portions of the exchanger 6, for example at the first inlet 61 and the first outlet 62. The coupling between the heads and the exchanger 6 may be a snap type coupling, interference coupling or, alternatively, it may be created through gluing (for example through the use of specific glues for plastic or for aluminium) or welding.
The first and the second head may be configured to compress the modular elements 80 between them and guarantee greater structural solidity for the exchanger 6.
The present invention also relates to an assembly process of a household drying appliance 1 comprising a condenser 6.
Such assembly process envisages the coupling of the condenser 6 to the first and the second circuit, so as to allow thermal communication between the drying fluid and the cooling fluid. The condenser 6 is connected to the first circuit at the first inlet 61 and the first outlet 62 of the condenser 6 and to the second circuit at the second inlet 63 and the second outlet 64 of the condenser 6. Advantageously, in the first circuit the condenser 6 is operatively interposed between the filter 13 and the heating element 12 and in the second circuit the condenser 6 is interposed between the suction aperture of the cooling fluid in the box body 2 and the draining portion of the cooling fluid leaving the box body 2.
Prior to the coupling of the condenser 6 to the first and the second circuit, the first head can be coupled to the condenser 6 at the first inlet 61 and optionally the second head at the first outlet 62.
The present invention makes it possible to obtain one or more of the following advantages and to resolve one or more of the problems encountered in the prior art. First of all the invention allows the times, costs and complexity of the assembly process of a heat exchanger for household appliances to be reduced.
The present invention further allows a heat exchanger to be provided that can be assembled by realising as many modular elements as are required by the energy and performance demands of the household appliance.
The modular exchanger assembled in accordance with the process according to the invention also has a reduced weight with respect to traditional exchangers.
The present invention allows the condenser to be assembled according to the size of the dryer, appropriately choosing the necessary number of modules.
The invention is moreover convenient to use, easy to implement and simple and economical to construct.

Claims

Process of assembling a heat exchanger (6) for household appliances, comprising the following steps:
- providing a plurality of thermal exchange sheets (30) having longitudinal edges (50), opposite to each other, and transversal edges (60), also opposite to each other and transversally placed to the longitudinal edges (50), characterised by

- providing a plurality of beams (40),

- engaging one or more pairs of beams (40) to longitudinal edges (50) of overlapped thermal exchange sheets (30), and one or more pairs of beams (40) to transversal edges (60) of overlapped thermal exchange sheets (30), to define a plurality of flow passage volumes oriented in a first direction and a plurality of flow passage volumes oriented in a second direction transversal to the first direction.
Process according to claim 1, wherein:
- providing a plurality of thermal exchange sheets (30) comprises providing at least a first, at least a second and at least a third sheets (301, 302, 303) having a quadrilateral shape,

- providing a plurality of beams (40) comprises providing at least a first and a second pair of beams (401, 402) having a prevalent longitudinal development,

- engaging one or more pairs of beams (40) to longitudinal edges (50) of overlapped thermal exchange sheets (30) comprises coupling the first pair of beams (401) to the first and second sheets (301, 302) at the respective longitudinal edges (50) in order to obtain a first modular element (801), said coupling defining between the first and second sheets (301, 302) a first passage volume for a first thermal exchange fluid,

- engaging one or more pairs of beams (40) to transversal edges (60) of overlapped thermal exchange sheets (30) comprises coupling the second pair of beams (402) to the second and third sheets (302, 303) at the respective transversal edges (60), each beam of the second pair of beams (402) developing in a direction perpendicular to the development directions of the beams of the first pair of beams (401), said coupling defining between the second and third sheets (302, 303) a second passage volume for a second thermal exchange fluid.
Process according to the preceding claim, wherein:
- providing a plurality of thermal exchange sheets (30) comprises further providing a fourth sheet (304),

- providing a plurality of beams (40) comprises further providing a third pair of beams (403), and wherein,

- before coupling the second sheet to the third sheet (302, 303), engaging one or more pairs of beams to longitudinal edges of overlapped thermal exchange sheets (30) comprises coupling the third pair of beams (403) to the third and fourth sheets (303, 304) at the respective longitudinal edges (50) in order to obtain a second modular element (802), said coupling defining between the third and fourth sheets (303, 304) a further first passage volume for a first thermal exchange fluid, the third pair of beams (403) developing parallel to the first pair of beams (401) and perpendicular to the second pair of beams (402).
Process according to any one of the preceding claims, wherein each beam (40) is provided with at least a first seat (701) and with at least a second seat (702) opposite to the first seat (701), the engagement of the thermal exchange sheets (30) to the beams (40) providing the insertion of the edges (50, 60) of the thermal exchange sheets (30) into the respective seats.
Process according to any one of the preceding claims, wherein, before engaging one or more pairs of beams (40) to the edges of overlapped thermal exchange sheets (30), the seats are widened, particularly by heating, and wherein, after the insertion of the edges into the widened seats, the process comprises blocking the seats (70) on the inserted edges, particularly by cooling the beams (40).
Process according to any one of claims from 1 to 4, wherein the beams (40) are made of plastics material and the thermal exchange sheets (30) are made of metal material, and wherein the steps of engaging the beams (40) to the sheets (30) of metal material are executed by co-moulding at least one beam (40) and at least one sheet (30) of metal material.
Process according to any one of the preceding claims, wherein each beam (40) has a transversal cross-section having a curvilinear outline, particularly a substantially "C" outline, wherein each beam (40) is provided with at least a first seat (701) and a second seat (702) made at terminal portions of the "C" outline.
Process of assembling a household drying appliance (1) comprising:
- an external box body (2);

- a drum (3) housed inside the box body (2) and destined to receive garments to be dried;

- a first circuit configured for circulating the drying fluid between an exit portion of the drum (3) and an inlet portion of the drum (3);

- a second circuit configured for circulating the cooling fluid from a suction aperture provided on the box body (2) to a draining portion externally of the box body (2),
wherein the process comprises the following steps:
- providing an exchanger (6) assembled according to the process in accordance to any one of the preceding claims,

- operatively interposing the exchanger (6) between the first and second circuits in order to thermally connect a length of the first circuit with a length of the second circuit.
Household drying appliance (1) comprising:
- an external box body (2);

- a drum (3) housed in the box body (2) and destined to receive garments to be dried;

- an exchanger (6), particularly assembled according to the process in accordance to any one of claims from 1 to 7, the exchanger (6) comprising:
o a plurality of thermal exchange sheets (30) having longitudinal edges (50) opposite to each other, and transversal edges (60) also opposite to each other and placed transversally to the longitudinal edges (50), and

o a plurality of beams (40) having a longitudinal development, and wherein:
one or more pairs of beams (40) are engaged to longitudinal edges of one or more pairs of overlapped sheets (30) and one or more pairs of beams are engaged to transversal edges of overlapped sheets (50) in order to reciprocally constrain the sheets and define, between them, a plurality of fluid passage volumes laterally delimited by the beams (40) and oriented in a first and second direction transversal to the first direction,

wherein the exchanger (6) comprises, in a direction transversal to the thermal exchange sheets (30), a succession of passage volumes alternatively constrained to longitudinal and transversal edges (50, 60) of the sheets (30), and wherein the exchanger (6) further comprises a first inlet (61) and a first outlet (62) for a drying fluid and a second inlet (63) and second outlet (64) for a cooling fluid,

and wherein the household appliance (1) further comprises:
- a first circuit configured for circulating the drying fluid from an outlet portion of the drum (3) to the first inlet (61) of the exchanger (6) and from the first outlet (62) of the exchanger (6) to an inlet portion of the drum (3),

- a second circuit configured for circulating the cooling fluid from a suction aperture provided on the box body (2) to the second inlet (63) of the exchanger (6) and from the second outlet (64) of the exchanger (6) to a draining portion externally of the box body (2).
Household appliance (1) according to the preceding claim, wherein at least one beam (40) engaged to longitudinal edges (50) of thermal exchange sheets (30) and at least one beam (40) engaged to transversal edges (60) of thermal exchange sheets (30) of two adjacent modular elements (80) are coupled at respective corners (41), said corners (41) being countershaped and abuttingly positioned against each other.