The invention relates to a recuperator comprising a number of neighbouring hexagonal sheets which extend parallel to each other and which are connected to each other at at least a part of their periphery and wherein flow passages are formed between neighbouring sheets.
Dutch publication NL 1030270 describes a method for producing a heat exchanger having hexagonal sheets which extend parallel to each other. In this case, sheets are stacked on top of each other and then neighbouring sheets are connected to each other at their periphery by means of chemical welding, wherein a solvent is used to partially dissolve the material of the sheets at their periphery. In practice, a housing is subsequently applied in order to the thus obtained stack of sheets welded to each other, which housing is connected to the stack by means of adhesive bonding. The housing ensures that the dimensions of the thus produced heat exchangers are relatively constant and that the heat exchangers are, for example, interchangeable as a result. Moreover, the housing provides mechanical protection to the stack and the possibility of attaching the heat exchanger to air supply and discharge lines which communicate with the flow passages between the sheets. Highly specialized assembly devices are needed to carry out the known method in an automated manner. It is an object of the invention to provide a recuperator according to the preamble, which recuperator can be made in a relatively simply automatable way. To this end, each of the sheets, at its periphery, is at least partially surrounded by and connected to an associated connecting body and neighbouring connecting bodies are connected to each other at at least a part of the periphery of the associated sheets and together the connecting bodies form the wall of a housing, wherein passage openings are provided in the wall which are connected to the flow passages for allowing air into the flow passages via the passage openings, wherein neighbouring connecting bodies are provided with protruding parts and with recesses respectively on sides facing each other, wherein the forms of the protruding parts and of the recesses adjoin each other in order to connect the connecting bodies to each other by a press fit. The use of a connecting body makes it superfluous to connect sheets to each other directly, for example by adhesive bonding or welding, such as in particular chemical welding or ultrasonic welding. Chemical welding and adhesive bonding have the significant drawback that they (may) require solvents which are dangerous and for this reason extra safety provisions are required. Neighbouring sheets of the recuperator according to the invention are connected to each other via the connecting bodies associated with the respective sheets during production of the recuperator. The connecting bodies which are connected to each other further function as a housing in the sense that they protect the sheets. The connecting bodies can further be formed in order to make attachment to supply and discharge lines possible in a simple manner. It is thus not necessary to use separate housings which are tailor made in advance. This also has the advantage that it is more likely to be cost-effective to produce recuperators in smaller numbers, for example specifically for a certain application or to customer specifications.
A correct positioning of the connecting bodies with respect to one another and thus of the sheets can readily be achieved by providing the neighbouring connecting bodies with protruding parts and with recesses respectively on sides facing each other, wherein the forms of the protruding parts and of the recesses adjoin each other in order to connect the connecting bodies to each other. The protruding parts and the recesses may also advantageously be used to produce an airtight or at least substantially airtight connection between the neighbouring connecting bodies. The connection between two neighbouring connecting bodies can be airtight with a high degree of reliability due to the press fit by means of which neighbouring connecting bodies are connected to each other. Such a connection by means of a press fit makes the application of welding or bonding neighbouring connecting bodies to each other superfluous, although it is also possible to combine the clamping connection with a welded or adhesive connection to increase the reliability of the connection. The additional welded or adhesive connection can then, for example, have an extra securing effect. The application, in the event of such a combination, of ultrasonic welding has the advantage that it is then not necessary to use any solvents in any case. For securing purposes, a band may also be arranged around the housing, which is optionally connected to each or at least a portion of the connecting bodies. The invention is particularly suitable for use in recuperators in which the sheets are made of plastic. In an embodiment, the passage openings are formed between neighbouring connecting bodies. In such a variant, the passage openings are formed by connecting the neighbouring connecting bodies to each other, which enables a relatively simple embodiment of the connecting bodies.
Alternatively, it is also possible for the passage openings to be formed in, instead of between, connecting bodies.
The assembly of the connecting bodies with associated sheets can be facilitated if the protruding parts and/or the recesses have a tapered form or at least partially a tapered form, as a result of which it is possible to realize a self-aligning positioning.
A practical embodiment, at least during assembly and optional disassembly, can be obtained if neighbouring connecting bodies are connected to each other by means of a click-fit connection.
In order to bring about an at least substantially airtight connection between neighbouring connecting bodies, it may be advantageous if the recuperator is provided with a sealing body between neighbouring connecting bodies at the location where they are connected to each other, wherein it may be further preferred, with a view in particular to achieving a simple assembly, for the sealing body to be connected to one of the two neighbouring connecting bodies.
The invention is suitable, inter alia, for recuperators of the membrane type. The sheets of such recuperators are suitable for exchanging moisture. The material of such sheets is not suited or is poorly suited to being welded. The use of adhesive for connecting membrane sheets to each other has the drawback that this is a step which is difficult to control and, partly as a result thereof, expensive, particularly if recuperators are produced in relatively large numbers, and that, depending on the type of adhesive that is used, it also involves the use of harmful solvents. Therefore, at least a portion of the sheets of a recuperator according to the invention may advantageously be permeable to moisture.
Advantageously, the recuperator may be configured to have sheets which are all provided with a profile. In this case, the connecting bodies can contribute to a correct positioning of the sheets, more specifically the profiles thereof, with respect to each other, since the sheets can behave in a relatively stiff way owing to the connection with the connecting bodies.
Alternatively, the invention is also suitable for a more traditional way in which sheets can be provided in a recuperator, namely wherein the neighbouring sheets are flat and are provided with a profile in an alternating fashion.
Especially as the invention makes it superfluous to directly connect neighbouring sheets to each other, the recuperator according to the invention may also advantageously be used if sheets are made of different materials, for example if neighbouring sheets are made of different materials in an alternating fashion.
An advantageous application of the invention may be in recuperators wherein a portion of the number of sheets is made of a moisture-permeable material and the other portion of the number of sheets is made of a material which is not permeable to moisture. In traditional recuperators, such materials are difficult to combine.
In order to produce a good connection between a connecting body and an associated sheet, it may be preferred, in the event that sheets made of different materials are used, for the connecting bodies to be made of different materials. In this case, a fixed combination is formed of the material of the connecting body and the material of the associated sheet.
In terms of construction, it may be advantageous if each of the sheets is at least substantially, including also completely, surrounded by an associated connecting body.
It may be preferred for the connecting bodies to be injection moulded, particularly in the case of relatively large production numbers.
According to a possible embodiment, the periphery of the housing is bar-shaped. The bar shape of the housing facilitates the attachment of other parts, such as in particular air ducts, to the recuperator. The invention provides the possibility of providing the housing with a bar-shaped periphery in a simple manner, namely by adapting the design of the connecting bodies hereto. Bar-shaped is understood to mean all forms in which six main surfaces are connected to each other at right angles. The definition of bar-shaped therefore also includes the form of a cube.
By positioning the peripheral edge of the sheet associated with the connecting body at least partially in the mould during the injection moulding, the connection between the sheet and the connecting body can be produced directly during the injection moulding. In the latter context, it may be advantageous if the sheets are over-moulded with the material of the connecting bodies along the first part of the periphery of the connecting bodies during the injection moulding of the connecting bodies at the periphery of the sheets. The invention therefore also relates to a method for producing a connecting body for use in a recuperator according to the invention, the method comprising the following steps
After or even during the solidification of the material that is injection moulded in order to form the connecting body, it is also possible to injection mould another material against the connecting body in order to form a sealing body. This is possible by temporarily enlarging the mould cavity locally after allowing the liquid injection moulding material into the mould cavity and before the mould is opened to remove the connecting body from the mould and injection moulding the other material in said enlarged part of the mould cavity.
The invention further provides a method for producing a recuperator according to the invention, the method comprising the following steps
The invention will be explained in more detail below on the basis of the description of a possible embodiment of a recuperator according to the invention with reference to the following figures which are not to scale:
In this example, the sheets 4 associated with the different connecting bodies 3, that is with the different layers 2, are made of the same material, namely of polystyrene (PS) that is not permeable to moisture. Alternatively, it is also possible, however, for all of the sheets 4 to be made of another material, typically of a plastic such as, for example, high-density polyethylene (HDPE), but also, for example, of a metal such as aluminium. The material used for the sheets 4 may further be permeable to moisture. It is also possible for the sheets 4 within a heat exchanger, in that case preferably in an alternating fashion, to be made from different materials, for example selected from the materials as mentioned above. The geometries of the sheets 4 differ from one another in an alternating fashion between profiled sheets 4a and flat sheets 4b. Insofar as the distinction is not important, this document uses reference numeral 4 for sheets 4a and 4b, thus irrespective of whether these are flat sheets or profiled sheets. Insofar as the distinction is important, reference numerals 2a and 2b are used for layers with a profiled sheet 4a and a flat sheet 4b respectively. In
Although twelve layers 2 are shown in
Flow passages for air are formed between neighbouring sheets 4. During operation of the heat exchanger 1, energy is exchanged between air that flows in opposite directions through adjoining flow passages. To allow air into flow passages, inflow openings 11a are formed between two neighbouring connecting bodies 3a, 3b, more specifically at the location of hexagonal side 10a of heat exchanger 1. Outflow openings 12a (not visible in
The layers 2 are connected to each other via the connecting bodies 3 by means of a clamping connection. To this end, the connecting bodies 3 are each provided with a hexagonal part 14 with an encircling rib 15 on its upper side and in which hexagonal part 14 an encircling groove 16 is provided on the underside. For connecting bodies 3a, the encircling rib 15 is interrupted at the location of the hexagonal sides 10a and 10d in order to form an inflow opening 11a and an outflow opening 12a, respectively. For connecting bodies 3b, the encircling rib 15 is interrupted at the location of the hexagonal sides 10b and 10e in order to form an outflow opening 12b and an inflow opening 11b, respectively. Furthermore, at the location of hexagonal sides 10b and 10e the hexagonal part 14 of connecting bodies 3a is provided on the underside with recesses 18b, 18a, respectively, as a result of which the groove 16 is interrupted in these areas and in order to form inflow opening 11b and outflow opening 12b. In a similar way, at the location of hexagonal sides 10a and 10d, the hexagonal part 14 of connecting bodies 3b is provided on the underside with recesses 19a, 19b (not illustrated), as a result of which groove 16 is interrupted in these areas and in order to form inflow opening 11a and outflow opening 12a.
The encircling form and the cross sections of the ribs 15 and the grooves 16 are dimensioned with respect to each other in such a way that they can engage with each other by a press fit in a clamping, airtight or at least substantially airtight manner. The ribs 15 are provided with aligning edges 17a, 17b in order to facilitate engaging with each other during assembly. In order to produce the press-fit connection between neighbouring connecting bodies 3, the connecting bodies 3 are pressed onto each other, wherein the flanks of the ribs 15 of one connecting body 3 slide along the flanks of the grooves 16 with friction. This results in the situation wherein the ribs 15 and the grooves 16 fit into each other without play and the respective flanks of the ribs 15 and the grooves 16 adjoin one another in a clamping manner, which clamping force provides the connection between the connecting bodies 3. Alternatively or in combination, the ribs 15 and the grooves 16 may also have a slightly tapered form, without departing from the principle of a press fit as explained above. Alternatively, it is then further possible to use a soft seal between the ribs 15 and grooves 16, which could optionally be connected to the ribs 15 or the grooves 16 as will be explained below with reference to
The above-mentioned cover body 41 of heat exchanger 1 has a hexagonal plate-shaped part 43, the periphery of which is the same as that of hexagonal part 14. The plate-shaped part is provided on the underside with an encircling (interrupted) groove similar to groove 16 for adjoining to the rib 15 of the top layer 2. The above-mentioned base body 42 of heat exchanger 1 has a hexagonal plate-shaped part 45, the periphery of which is also similar to that of hexagonal part 14. On the top side of the plate-shaped part 45, the base body 42 is provided with an encircling (interrupted) rib 46 similar to rib 15 for adjoining to groove 16 of the bottom layer 2. Incidentally, the cover body and the base body could alternatively also have a differently shaped periphery, for example for the purpose of attachments to air supply and air discharge facilities.
In the form used, two air supply ducts (not shown in more detail) are attached to hexagonal sides 10a and 10e of heat exchanger 1 in an airtight manner, via which two air flows are supplied to the flow passages on one side which adjoin the inflow openings 11a and 11b. Furthermore, two air discharge ducts (not shown in more detail) are attached to the hexagonal sides 10b and 10d of heat exchanger in an airtight manner so that the outflow openings 12b, 12a open into such an air discharge duct and the air flows leave the heat exchanger 1 again after they have passed through the flow passages. The various attachments and connections between the connecting bodies 3 with respect to each other and between the connecting bodies 3 on the one hand and the sheets 4 on the other hand are such that at least 97% of the air which flows into the heat exchanger 1 via inflow openings 11a, 11b flows out of the heat exchanger 1 again via outflow openings 12a, 12b. During operation, energy will be exchanged between, on the one hand, the air which flows through the flow passages that adjoin inflow openings 11a and, on the other hand, the air which flows through the flow passages that adjoin inflow openings 11b.
For the sake of completeness, it should be noted that the hexagonal sides of the recuperator could also differ from each other in terms of their length. More specifically, for example, the hexagonal sides 10c and 10f may be longer than the remaining hexagonal sides 10a, 10b, 10d and 10e. In that case, the hexagonal form of the recuperator is thus not rotationally symmetrical, as is illustrated in the figures. Although the inflow openings and outflow openings are now surrounded by two neighbouring connecting bodies 3, it is also possible to provide the inflow openings and/or the outflow openings in a single connecting body. Each of the inflow openings and/or the outflow openings are then fully surrounded by material of an associated connecting body. It is furthermore possible that the connecting bodies are not fully encircling or in fact consist of two or even more parts which are each provided on just a part of the periphery of a sheet, wherein use is possibly made of separate seals to prevent leakage of air.
It will be clear to those skilled in the art that a layer 2b with a completely flat sheet 4b can also be produced in a similar way. The layers 2a and 2b can be alternately clamped on top of one another (
Number | Date | Country | Kind |
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2018175 | Jan 2017 | NL | national |
Filing Document | Filing Date | Country | Kind |
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PCT/NL2018/050032 | 1/16/2018 | WO | 00 |