EP3931513B1

EP3931513B1 - Plate-type heat exchanger

Info

Publication number: EP3931513B1
Application number: EP20707379.2A
Authority: EP
Inventors: Paolo CALACIURA; Enrico GOLIN
Original assignee: ONDA SpA
Current assignee: Wieland Onda Srl
Priority date: 2019-02-27
Filing date: 2020-02-20
Publication date: 2023-10-25
Anticipated expiration: 2040-02-20
Also published as: US20220146204A1; IT201900000665U1; EP3931513A1; WO2020173797A1

Description

The present invention relates to a plate-type heat exchanger.
In refrigeration systems that execute refrigeration cycles using vapor expansion, for air-conditioning or refrigeration applications, the use is known of plate-type heat exchangers to provide evaporators, in which a heat exchange occurs between a refrigerant fluid, which, flowing inside a series of passage channels defined in the plate-type heat exchanger, progressively evaporates, absorbing heat from a fluid to be cooled, typically water, which, flowing in channels adjacent to the channels flowed through by the refrigerant fluid, is in turn cooled.
More specifically, the plate-type heat exchangers that are used as evaporators in refrigeration systems are, typically, constituted by a "pack" of plates, i.e. by a plurality of plates that are mutually stacked, so as to face each other, and are joined together at various points of mutual contact, by way of brazing or welding, or are interconnected by way of the interposition of gaskets.
In these applications, the refrigerant fluid fed into the plate-type heat exchanger is, generally, in a mixed biphasic state, in which there are a liquid phase and a vapor phase of the coolant fluid.
A technical problem associated with the use of plate-type heat exchangers as evaporators in refrigeration systems consists of ensuring that the entry distributor channel of the heat exchanger can evenly feed the various channels with refrigerant fluid, avoiding feeding some of them with only the vapor phase, with the obvious consequence of reducing the efficiency of the heat exchange between the refrigerant fluid and the fluid to be cooled, as the vapor phase offers a scant contribution to the heat exchange.
In order to attempt to solve this problem, plate-type heat exchangers have been proposed in which the entry distribution channel of the refrigerant fluid is connected to the corresponding passage channels through entry choke points or orifices, of calibrated dimensions, in order to control the passage of the refrigerant fluid from the entry distributor channel to the corresponding passage channels, ensuring an even distribution thereof in its two phases, so as to thus optimize the yield of the heat exchanger if it is used as an evaporator.
A plate-type heat exchanger of this type is described in WO2006/110090 and has a plurality of heat-exchange plates, which face each other and have respective entry apertures that are mutually adjacent and are provided with a respective folded edging so as to form a collar that protrudes in a direction substantially parallel to the axis of the entry apertures, in order to create an entry distributor conduit for the refrigerant fluid that is cylindrical and substantially smooth, and is connected with the passage channels for the refrigerant fluid which are defined between the heat-exchange plates alternately with the passage channels for the fluid to be cooled through orifices or entry ports provided by slots, which are obtained by molding in the heat-exchange plates, at zones of mutual contact between two adjacent plates which extend around the entry apertures.
In an embodiment of the heat exchanger described in WO2006/110090 , a distance is specified between the edges of the collars of two mutually adjacent heat-exchange plates, so as to form a fissure between the edges of the collars facing each other, for the purpose of preventing interference between the edges of two adjacent plates, which can entail problems during the assembly of the heat exchanger.
As a consequence of the presence of this fissure, the mutually facing edges of the mutually opposite collars of mutually adjacent plates are not brazed together, since they are not in contact with each other.
Furthermore, in order to ensure the presence of a distance between the edges of two mutually opposite collars, press-molding of the plates with very fine tolerances is required, with a consequent major impact on the cost of the mold. A plate-type heat exchanger according to the preamble of claim 1 is disclosed in US 2007/089872 A1 .
The aim of the present invention is to provide a plate-type heat exchanger which is capable of improving the known art in one or more of the above mentioned aspects.
Within this aim, an object of the invention is to provide a plate-type heat exchanger that is capable of ensuring an even distribution of the refrigerant fluid in the corresponding passage channels defined between the plates of the exchanger, without the risk of decanting the refrigerant fluid into the passage channels of the fluid to be cooled.
Another object of the invention is to provide a plate-type heat exchanger in which the plates can be provided with a simpler molding process and with a lesser increase in the costs of the mold with respect to the known art.
Another object of the present invention is to provide a heat exchanger that can be easily assembled and which always allows a perfect brazing between adjacent plates.
Another object of the present invention is to provide a plate-type heat exchanger that is capable of ensuring that all of the incoming flow of refrigerant fluid passes solely through special orifices which are distributed along the extension of the entry distributor channel for the refrigerant fluid.
Another object of the invention is to provide a plate-type heat exchanger that, owing to the peculiar implementation characteristics, is capable of offering the highest guarantees of reliability and safety in its operation.
Another object of the invention is to provide a plate-type heat exchanger that can also be competitive from a purely economic viewpoint.
This aim and these and other objects which will become better apparent hereinafter are achieved by a plate-type heat exchanger according to claim 1, optionally provided with one or more of the characteristics of the dependent claims.
Further characteristics and advantages of the invention will become better apparent from the description of preferred, but not exclusive, embodiments of the plate-type heat exchanger according to the invention, which are illustrated for the purposes of non-limiting example in the accompanying drawings wherein:

Figure 1 is a schematic perspective view of the plate-type heat exchanger according to the invention;
Figure 2 is an exploded perspective view of the heat exchanger according to the invention;
Figure 3 is an enlarged-scale detail of Figure 2;
Figure 4 is a cutaway perspective view of a portion of the heat exchanger according to the invention;
Figure 5 is a cutaway perspective view of a detail of the heat exchanger according to the invention;
Figure 6 is a cross-sectional view taken along the line VI-VI in Figure 1;
Figure 7 is an enlarged-scale view of a detail of Figure 6;
Figure 8 is a schematic cutaway perspective view of a possible variation of embodiment of the heat exchanger according to the invention.

With reference to the figures, the plate-type heat exchanger according to the invention, which is generally designated by the reference numeral 1, comprises a plurality of heat-exchange plates 2 which are mutually stacked and facing each other so as to define, in the space comprised between them, at least two passage channels, in particular at least one first passage channel 3 and at least one second passage channel 4, which alternate with each other along the direction of stacking of the heat-exchange plates 2 and are flowed through by respective fluids that are adapted to exchange heat with each other.
More specifically, the first and the second passage channels 3 and 4 are adapted to be passed through, respectively, by a first fluid, constituted in particular by a refrigerant fluid, and by a second fluid, constituted by a fluid to be cooled.
Conveniently, the heat-exchange plates 2 are interposed between a first outer covering plate 5 and a second outer covering plate 6 and are, advantageously, provided with respective corrugations 7 which are constituted by mutually parallel ridges and recesses that can extend in directions of various kinds and which are, conveniently, arranged so that the corrugations 7 arranged on mutually adjacent heat-exchange plates 2 can intersect with each other.
The heat-exchange plates 2 are, preferably, joined together hermetically by way of brazing and, to this end, along their perimeter, they are, advantageously, provided with a respective folded edging 8 which overlaps on the folded edging 8 of an adjacent heat-exchange plate 2, in order to allow the execution of a perfect perimetric brazing between adjacent heat-exchange plates 2.
Each one of the heat-exchange plates 2 has, conveniently, at one of its ends, a respective entry aperture 9, for one of the two fluids, in particular for the first fluid.
The entry apertures 9 of the heat-exchange plates 2 are substantially adjacent, so as to define, inside the exchanger, an entry conduit 10 for the first fluid, which basically extends parallel to the direction of stacking of the heat-exchange plates 2 and which allows the first fluid to be distributed within the first passage channels 3.
In particular, the entry conduit 10 is, advantageously, connected to a first input connector 9a, which is fixed, conveniently, to the first outer covering plate 5 of the exchanger.
The entry conduit 10 is, furthermore, connected with the passage channels of the corresponding fluid, i.e., in the example illustrated, with the first passage channels 3, through one or more orifices 11, which have, conveniently, a reduced passage section, so as to provide a choked connection between the entry conduit 10 and the first passage channels 3 and thus enable a controlled evaporation of the first fluid, in order to avoid an uneven distribution of the liquid phase of the first fluid into the first passage channels 3.
It should be noted that, conveniently, at the same end where the entry aperture 9 for the first fluid is, the heat-exchange plates 2 also have respective exit openings 12, which define, in the exchanger, an outlet manifold 13 for the second fluid, which is connected to the second passage channels 4 and, in turn, is connected to an exit connector 12a of the second fluid, which is also fixed to the first outer covering plate 5.
At their opposite end, the heat-exchange plates have, furthermore, respective second entry openings 14 which define, inside the exchanger, an inlet manifold for the second fluid, connected to a second entry opening 14a, again fixed to the first outer covering plate 5, and connected with the second passage channels 4, and further exit openings 15, which define an outlet manifold for the first fluid, connected to the first passage channels 3 and connected to an exit connector 15a of the first fluid, and again fixed to the first outer covering plate 5.
It should be noted that the first covering plate 5 is perforated at the connectors 9a, 12a, 14a and 15a, in order to allow the entry and the exit of the first and of the second fluid from the exchanger.
The entry apertures 9 have, in particular, respective collar-like edgings 16 which extend from the edge of the entry apertures 9 along a direction that is substantially parallel to the axis of the entry apertures 9 and the function of which is to close the connection between the entry conduit 10 and the second passage channels 4.
Each collar-like edging 16 has, at its opposite end from the end connected to the edge of the corresponding entry aperture 9, an abutment flange 17 which extends radially with respect to the axis of the entry apertures 9 and is adapted to engage, by contact, the abutment flange 17 of the collar-like edging 16 of an adjacent heat-exchange plate 2.
In this manner, the abutment flange 17 provided on the collar-like edgings 16 makes it possible to ensure the perfect brazing between the collar-like edgings 16 of two adjacent heat-exchange plates 2, thus ensuring that all of the flow of the first fluid passes through the orifices 11, without risk of leaks of the first fluid into the second passage channels 4.
It must be noted that the abutment flanges 17 of the heat-exchange plates 2 protrude inward into the entry conduit 10, in so doing rendering the entry conduit 10 not perfectly smooth, as in the known art, but relatively corrugated.
It should be noted that the abutment flanges 17 can protrude from the collar-like edgings 16 for a length comprised, in ratio to the diameter of the entry apertures, of between 1% and 25%, thus giving the entry conduit 10 a light corrugation.
It must also be noted that the abutment flanges 17 can easily be provided in the step of molding the heat-exchange plates 2, at considerably reduced cost, since a dedicated mold to be added downstream is not necessary after the mold-forming of the plates.
In more detail, each one of the heat-exchange plates 2 extends, advantageously, between at least one first plane of arrangement 2a and at least one second plane of arrangement 2b, which are mutually parallel and spaced apart, and has, around the corresponding entry aperture 9, at least one flat annular abutment zone 18 which is adapted to be in contact with a corresponding flat annular abutment zone 18 of an adjacent heat-exchange plate 2.
In particular, the flat annular abutment zone 18 of each heat-exchange plate 2 lies substantially at the corresponding first plane of arrangement 2a, while the abutment flange 17 lies substantially at the corresponding second plane of arrangement 2b.
Advantageously, on the flat annular abutment zone 18 of at least one of the heat-exchange plates 2, a ridge 19 is defined in relief and extends around at least one portion of the edge of the corresponding entry aperture 9.
Such ridge 19 is, in particular, adapted to engage a corresponding indentation 20 which is defined in the flat annular abutment zone 18 of the adjacent heat-exchange plate 2 against which the flat annular abutment zone 18 on which the ridge 19 is defined is adapted to make contact.
The presence of the ridge 19 and of the corresponding indentation 20 on the flat annular abutment zones 18 makes it possible to prevent the first fluid, owing to the difference in pressure that is established between the entry conduit 10 and the first passage channels 3, from leaking radially between two adjacent heat-exchange plates 2, so entering the first passage channels 3 instead of passing through the orifices 11, with consequent loss of thermal yield of the exchanger.
Furthermore, the ridge 19 and the corresponding indentation 20 facilitate the operation of centering the heat-exchange plates 2 during the step of stacking them. In this manner, a perfect brazing is always ensured between the adjacent heat-exchange plates 2 at the flat annular abutment zones 18.
Advantageously, each orifice 11 is defined between the flat annular abutment zones 18 of two mutually adjacent heat-exchange plates 2 and, in particular, is provided by at least one slot 21 which extends radially with respect to the entry apertures 9 and which is defined on the flat annular abutment zone 18 of the mutually adjacent two heat-exchange plates 2.
In practice it has been found that the invention fully achieves the intended aim and objects.
In particular, it has been experimentally verified that with the entry conduit of the exchanger according to the invention, even though it is not perfectly smooth, it is possible to improve and better control the distribution of the refrigerant fluid with respect to the known art.
Furthermore, it has been experimentally verified that the lightlycorrugated entry channel of the exchanger according to the invention makes it possible to increase the number of heat-exchange plates by over 50% with respect to conventional exchangers, thus making the exchanger according to the invention much more competitive, in that for the same exchange surface, it makes it possible to obtain a greater exchanged thermal power.
The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. Moreover, all the details may be substituted by other, technically equivalent elements.
Thus, for example, as shown schematically in Figure 8, the collar-like edgings 16 can be provided in a separate piece with respect to the remaining part of the corresponding plate 2.
In this case, the collar-like edgings 16 can be joined to the remaining part of the corresponding plates 2 by way of brazing and they can, conveniently, have a flat connection section 16a, which protrudes radially from the end of the collar-like edging 16 that is adapted to be connected to the corresponding plate and which is designed to engage by contact on the opposite side of the flat annular abutment zone 18 of the corresponding plate 2 from the one against which the flat annular abutment zone 18 of the adjacent plate rests, so as to enable the joining by way of brazing of the flat connection section 16a to the flat annular abutment zone 18 of the corresponding plate 2.
Also in this case, the collar-like edgings 16 can, optionally, have an inclined extension that progressively approaches the axis of the corresponding entry aperture 9, going from the flat connection section 16a toward the corresponding abutment flange 17.
In practice the materials employed, provided they are compatible with the specific use, and the contingent dimensions and shapes, may be any according to requirements and to the state of the art.
Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

A plate-type heat exchanger which comprises a plurality of heat-exchange plates (2) which are mutually stacked and facing each other so as to define, in the space comprised between them, at least two passage channels (3, 4), which alternate with each other along the direction of stacking of the heat-exchange plates (2) and are passed through by respective fluids that are adapted to exchange heat with each other, said heat-exchange plates (2) having respective entry apertures (9) which are substantially mutually adjacent so as to define an entry conduit (10) for one of said fluids, said entry conduit (10) being connected with the passage channel (3) of the respective fluid through at least one orifice (11), said entry apertures (9) having respective collar-like edgings (16) which extend from the edge of said entry apertures (9) along a direction that is substantially parallel to the axis of said entry apertures (9), wherein each one of said collar-like edgings (16) has, at its opposite end from the end connected to the edge of the corresponding entry aperture (9), an abutment flange (17) which extends radially with respect to the axis of said entry apertures (9) and is adapted to engage, by contact, the abutment flange (17) of the collar-like edging (16) of an adjacent heat-exchange plate (2) and wherein each one of the heat-exchange plates (2) extends between at least one first plane of arrangement (2a) and at least one second plane of arrangement (2b), which are mutually parallel and spaced apart, and has, around the corresponding entry aperture (9), at least one flat annular abutment zone (18) which is adapted to be in contact with a corresponding flat annular abutment zone (18) of an adjacent heat-exchange plate (2) characterized in that said flat annular abutment zone (18) of at least one of said heat-exchange plates (2) has a ridge (19) in relief, which extends around at least one portion of the edge of the corresponding entry aperture (9) and is adapted to engage a corresponding indentation (20) which is defined in the corresponding flat annular abutment zone (18) of the adjacent heat-exchange plate (2).
The plate-type heat exchanger according to claim 1, characterized in that, said at least one flat annular abutment zone (18) lies substantially at said first plane of arrangement (2a) and said abutment flange (17) lies substantially at said second plane of arrangement (2b).
The plate-type heat exchanger according to claim 2, characterized in that said at least one orifice (11) is provided by at least one slot (21) which is defined on the flat annular abutment zone (18) of at least one of the mutually adjacent heat-exchange plates (2).
The plate-type heat exchanger according to claim 1, characterized in that said collar-like edgings (16) are provided in a separate piece with respect to the remaining part of the corresponding heat-exchange plate (2).
The plate-type heat exchanger according to claim 1, characterized in that said collar-like edgings (16) are joined to the remaining part of the corresponding heat-exchange plate (2) by way of brazing.