Patent Application
20220099378
The disclosure relates to a web for transfer of thermal energy and/or moisture to and/or from a fluid, the web comprising a plurality of fluid flow channels.
Heat exchangers are used to recycle energy from out-going gas flow to ingoing gas flow in various applications such as ventilation, drying, thermal management of electronic devices, etc. A heat exchanger comprises a plurality of channels configured for fluid flow, which channels may be arranged in a matrix. Oftentimes, the inlet fluid flows in one set of channels in one direction, while the outlet fluid flows in a different set of channels in the opposite direction, as is the case for plate heat exchangers wherein the heat exchanger matrix comprises inlet fluid flows and the outlet fluid flows which are completely separated from each other.
The fluid flow separation of the plate heat exchanger prevents contamination, i.e. transfer of odor or particles between outlet fluid flow and inlet fluid flow. One important parameter for the performance of the plate heat exchanger is the spacing between adjacent plates. A narrower channel, i.e. a smaller height or distance between adjacent plates, leads to a higher pressure drop as well as to higher efficiency, i.e. more heat is transferred. If a lower pressure drop is required, a larger channel height is preferable, the trade-off being lower efficiency. A plate heat exchanger has an approximate temperature efficiency of 65-80%, and the allowable pressure drop is usually within the range of between 20 and 100 kPa.
The matrix of a corresponding rotary heat exchanger instead uses the same channels to accommodate both inlet fluid flow and outlet fluid flow. As the rotor rotates, heat is captured from the outlet fluid in one half of a rotation cycle and released to the inlet fluid during the other half of the rotation cycle. This allows waste energy from the outlet fluid to be transferred to the matrix, and thereafter from the matrix to the inlet fluid. This increases the temperature of the inlet fluid by an amount proportional to the temperature differential between the fluids and depends on the efficiency of the heat exchanger. Since the outlet fluid flow and inlet fluid flow pass through the same rotor channels alternately, the rotor is also, to a large extent, self-cleaning and frost proof.
The rotor's ability to recover both thermal energy and humidity, i.e. latent energy, makes the rotary heat exchanger very efficient. A rotary heat exchanger usually has a temperature efficiency of 70-90% with a pressure drop of between 50 and 300 Pa. The rotor may also be used as a desiccant wheel which is provided with a coating applied for the purpose of transferring humidity from one fluid to the other.
The channels of the matrix of a rotary heat exchanger traditionally have a substantially triangular or sinusoidal shape, facilitating as much matrix surface area as possible which can come into contact with the fluids, improving heat transfer efficiency. However, heat exchange may be made even more efficient if the normally laminar flow of the fluid is interrupted, e.g. by means of heat sinks, and some turbulence within the fluid is created. This is due to laminar flow developing a boundary layer adjacent to the channel wall which restricts heat transfer, and any added turbulence generating significant mixing of the boundary layer and the bulk fluid, allowing highly efficient heat exchange.
The aspects of the disclosed embodiments are directed to an improved web and matrix for a heat exchanger. The foregoing and other aspects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures.
According to a first aspect, there is provided a web for a rotary heat exchanger, the web being configured for transfer of thermal energy and/or moisture to and/or from a fluid, the web comprising a plurality of first profiled sections and a plurality of second profiled sections, the first profiled sections and the second profiled sections being configured to protrude in opposite directions from a main plane of the web, each protrusion comprising a fluid passage, the first profiled sections and the second profiled sections forming a plurality of fluid flow channels, each fluid flow channel having a main fluid flow axis and being configured to allow fluid flow at least partially along the main fluid flow axis, each fluid flow channel being formed by alternating at least one first profiled section and at least one second profiled section along the main fluid flow axis and by aligning the fluid passages of the alternatingly arranged first profiled sections and second profiled sections, each fluid flow channel comprising at least one lateral opening allowing the fluid flow to at least partially travel between adjacent fluid flow channels.
A web like the one described above comprises as few parts as possible, dispensing of the need for separate distancing components such as spacers. This not only reduces material costs but also facilitates assembly and allows for a more compact heat exchanger, when winding the web into a spiral or stacking several webs on top of each other, forming a heat exchanger comprising multiple layers of webs and hence fluid flow channels.
Furthermore, this specific web provides an as large surface area, i.e. energy transfer area, as possible while also allowing the laminar flow of the fluid passing through each fluid flow channel to be interrupted, by a lateral opening in the channel wall, and some turbulence to be created within the fluid. This significantly improves the energy transfer rate of the web, as well as the moisture transfer rate, as the slow-moving boundary layer is broken.
In a possible implementation form of the first aspect, the first profiled sections protruding in a first direction perpendicular to the main plane, the second profiled sections protruding in a second direction opposite to the first direction, such that the profiled sections together form both spacers as well as a fluid flow channel.
In a further possible implementation form of the first aspect, the main fluid flow axes extending in parallel with each other and with the main plane. This facilitates having only one common inlet side and one common outlet side in the heat exchanger comprising the web.
In a further possible implementation form of the first aspect, a fluid outlet end of the first profiled section is arranged adjacent a fluid inlet end of an adjacent second profiled section, and/or wherein a fluid inlet end of the first profiled section is arranged adjacent a fluid outlet end of an adjacent second profiled section, the fluid passage of the first profiled section extending from the fluid inlet end to the fluid outlet end along the main fluid flow axis, and the fluid passage of the second profiled section extending from the fluid inlet end to the fluid outlet end along the main fluid flow axis.
In a further possible implementation form of the first aspect, the fluid flow can deviate from the main fluid flow axis as it exits the fluid outlet end of the first profiled section of the fluid flow channel, and travel into the fluid passage of the second profiled section of an adjacent fluid flow channel, and/or the fluid flow can deviate from the main fluid flow axis as it exits the fluid outlet end of the second profiled section of the fluid flow channel, and travel into the fluid passage of the first profiled section of an adjacent fluid flow channel. This way, an opening in the channel wall, i.e. an interruption affecting the laminar flow of fluid, is formed at each transition between a first profiled section and a second profiled section, allowing for more efficient heat exchange.
In a further possible implementation form of the first aspect, the first profiled sections and the second profiled sections of each fluid flow channel have identical shape, an axis of symmetry of the first profiled sections extending coaxially with an axis of symmetry of the second profiled sections, and extending in parallel with the main fluid flow axis of the fluid flow channel. This simplifies the manufacture of the web, since only one shape, though inverted, must be achieved.
In a further possible implementation form of the first aspect, the first profiled sections and the second profiled sections have different cross-sectional shapes as seen in a plane perpendicular to the main fluid flow axis and to the main plane, increasing the flexibility of the web. For example, the height of each profiled section can be selected to provide greater or lesser spacing between adjacent webs of a matrix, thereby establishing a desired surface area density of the matrix. This implementation form allows the heat exchange matrix to be customized by using two different profiled sections of different surface area densities. Furthermore, the height of the profiled sections determines the extent of separation between adjacent webs and, hence, determines the diameter of the fluid flow channel, the surface area density, and subsequently the airflow versus pressure drop relationship, for the matrix.
In a further possible implementation form of the first aspect, the first profiled section and the second profiled section each comprises an apex and a base, the apex of the first profiled section and the base of the second profiled section being arranged at one side of the main plane, and the base of the first profiled section and the apex of the second profiled section being arranged at an opposite side of the main plane. The distance between apex and base, i.e. the height of the profiled section can be selected to provide greater or lesser spacing between adjacent webs, thereby providing a desired surface area density.
In a further possible implementation form of the first aspect, the apex of the first profiled section and the base of the second profiled section are arranged in a first common plane, and the base of the first profiled section and the apex of the second profiled section are arranged in a second common plane. This allows for a symmetrical web that is easy to manufacture and assemble into a matrix.
In a further possible implementation form of the first aspect, the first profiled section and the second profiled section comprise a strip of web material. By dividing a web material into a plurality of strips, a simple way of manufacturing a web, having aligned fluid flow channels as well as lateral openings between adjacent fluid flow channels, is facilitated.
In a further possible implementation form of the first aspect, the shape substantially corresponds to one period of a sine wave.
In a further possible implementation form of the first aspect, the apex corresponds to a crest of the sine wave, and the base corresponds to two troughs of the sine wave.
In a further possible implementation form of the first aspect, the first profiled section and the second profiled section each comprises at least one stepped part, the stepped part of the first profiled section extending adjacent the stepped part of an adjacent second profiled section. The stepped parts provide stability to the web as well as an increase in surface areas of each fluid flow channel.
In a further possible implementation form of the first aspect, the stepped parts of the first profiled sections extend coplanar with the stepped parts of the second profiled sections. The stepped parts provide larger coherent surface sub-areas within each fluid flow channel.
In a further possible implementation form of the first aspect, the stepped part is arranged equidistantly between the apex and the base, facilitating a symmetric web.
In a further possible implementation form of the first aspect, the web comprises a web material such as polymer, steel, or aluminum foil, and, optionally, a hygroscopic or epoxy coating. This allows the web to be thin, lightweight, and to serve for the transfer of moisture in addition to transfer of energy.
According to a second aspect, there is provided a web matrix for transfer of thermal energy and/or moisture to and/or from a fluid, the matrix comprising a plurality of webs according to the above, the webs being superimposed onto each other such that the main fluid flow axes of the webs extend in parallel.
The provision of protruding sections allows the webs of the matrix to be stacked without requiring separate distancing components such as spacers, since each protrusion provides both a fluid channel and vertical separation.
In a possible implementation form of the second aspect, the web matrix further comprises at least one integral sheet material, each sheet material being arranged between two adjacent webs. The integral sheet material provides separation between adjacent webs.
In a further possible implementation form of the second aspect, each sheet material is configured to support the apexes of the first profiled sections and the bases of the second profiled sections, or to support the apexes of the second profiled sections and the apexes of the second profiled sections.
In a further possible implementation form of the second aspect, the apex and/or the base of the first profiled sections and/or the second profiled sections of the webs are fixedly attached to the sheet material.
According to a third aspect, there is provided a rotor for a heat exchanger comprising the matrix according to the above, a rotation axis of the rotor extending in parallel with the main fluid flow axes of the webs of the matrix. Such a solution facilitates not only a rotor having improved energy transfer rates as well as improved moisture transfer rates, but also enables considerable savings of material in the manufacture of the rotor.
In a possible implementation form of the third aspect, each fluid flow channel of the webs is configured to accommodate bidirectional fluid flow at least partially along the main fluid flow axis, the fluid flowing in a first direction, along the main fluid flow axis, within a rotor section when the rotor section is in a first angular position, the fluid flowing in a second, opposite direction, along the main fluid flow axis, within the rotor section when the rotor section is in a second angular position.
In a further possible implementation form of the third aspect, the rotor is configured for air-to-air heat transfer.
In a further possible implementation form of the third aspect, the rotor is configured for air-to-liquid.
According to a fourth aspect, there is provided a rotary heat exchanger comprising the rotor according to the above. This solution facilitates not only a heat exchanger having improved energy transfer rates as well as improved moisture transfer rates, but also enables considerable savings of material in the manufacture of the heat exchanger.
In a possible implementation form of the fourth aspect, the rotary heat exchanger is configured for use in ventilation systems.
This and other aspects will be apparent from the embodiments described below.
In the following detailed portion of the present disclosure, the aspects, embodiments, and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which:
configured for air-to-air heat transfer, air-to-liquid heat transfer, or liquid-to-liquid heat transfer. Furthermore, the rotor 12 may be configured for moisture transfer. The rotor 12 may have a temperature efficiency of 70-90% with a pressure drop of between 50 and 300 Pa.
The rotor 12 comprises a web matrix 10 comprising a plurality of webs 1, or foils, described in more detail further below. The rotation axis A4 of the rotor 12 extends in parallel with the main fluid flow axes A1 of the webs 1 of the web matrix 10, as indicated in
The webs 1 comprise a plurality of fluid flow channels 5 which are configured to accommodate bidirectional fluid flow at least partially along the main fluid flow axis A1, which reduces the buildup of laminar flow. By bidirectional is meant that the fluid flows in a first direction D3 along the main fluid flow axis A1 of a fluid flow channel 5 arranged within a specific rotor section, when the rotor section is momentarily in a first angular position R1. Correspondingly, the fluid flows in a second, opposite direction D4 along the same main fluid flow axis A1, when the same rotor section is momentarily in a second angular position R2. The first angular position R1 may for example be any position in the upper 180° of one revolution of the rotor 12 around the rotation axis A4, and the second angular position R2 may be any position in the lower 180° of the revolution.
The web 1 comprises a plurality of first profiled sections 2 and a plurality of second profiled sections 3. The first profiled sections 2 and the second profiled sections 3 are configured such that they protrude in opposite directions from the main plane P1 of the web 1. Each protrusion forms a fluid passage 4, in other words, the first profiled sections 2 and the second profiled sections 3 are shaped such that they extend in opposite directions, and a fluid passage 4 being created by and within this protrusion. Furthermore, the plurality of first profiled sections 2 and the plurality of second profiled sections 3, since they protrude in opposite directions from the main plane P1, form distances between adjacent, i.e. stacked, webs 1.
The first profiled sections 2 and the second profiled sections 3 together form a plurality of fluid flow channels 5. Each fluid flow channel 5 has a main fluid flow axis A1 and is configured to allow fluid flow at least partially along the main fluid flow axis A1, in first direction D3 and second direction D4. The plurality of fluid flow channels 5 within one web 1 is arranged such that they extend substantially in parallel, i.e. the main fluid flow axes A1 of the fluid flow channels 5 are parallel with each other, within the main plane P1. The main plane P1 may be is curved, e.g. when the web 1 is used in the matrix of a rotary heat exchanger 13. This curvature or arching requires the plurality of webs 1 of the web matrix 10 to be stacked or wound such that each layer of web 1 is correctly arched as well as distanced from each other.
Each fluid flow channel 5 is formed by alternating at least one first profiled section 2 and at least one second profiled section 3 along the main fluid flow axis A1, such that every second section is a first profiled section 2 and every second profile is a second profiled section 3. The first profiled sections 2 protrude in a first direction D1 which is perpendicular to the main plane P1, and the second profiled sections 3, correspondingly, protrudes in a second direction D2 opposite to the first direction D1, as illustrated in
The size of the fluid passages 4 and, hence, fluid flow channels 5 in the first direction D1 and the second direction D2 is usually called well height. Different well heights and rotor diameters give different efficiencies, pressure drops, and airflow rates.
By alternating first profiled sections 2 and second profiled sections 3, a fluid outlet end 2b of a first profiled section 2 may be arranged adjacent a fluid inlet end 3a of an adjacent second profiled section 3, and/or a fluid inlet end 2a of a first profiled section 2 may be arranged adjacent a fluid outlet end 3b of an adjacent second profiled section 3. The fluid passage 4 of the first profiled section 2 extends from the fluid inlet end 2a to the fluid outlet end 2b, of the first profiled section 2, along main fluid flow axis A1. The fluid passage 4 of the second profiled section 3 extends from the fluid inlet end 3a to the fluid outlet end 3b, of the second profiled section 3, along main fluid flow axis A1.
The use of two alternating first profiled sections 2 and second profiled sections 3 not only provides fluid flow channels but also distancing between directly adjacent webs 1, as well as facilitates arching of the webs and a stable yet efficient web matrix 10. An increased number of profiled sections would complicate manufacture as well as arching.
Each fluid flow channel 5 comprises at least one lateral opening 6 allowing the fluid flow to at least partially travel between adjacent fluid flow channels 5, and not only along the main fluid flow axis A1. A lateral opening 6 may be formed at each transition between a first profiled section 2 and a second profiled section 3, as shown in
The fluid flow may deviate from the main fluid flow axis A1, i.e. travel through a lateral opening 6, as it exits the fluid outlet end 2b of a first profiled section 2 of a fluid flow channel 5a, and travel into the fluid passage 4 of a second profiled section 3 of an adjacent fluid flow channel 5b. Correspondingly, the fluid flow may deviate from the main fluid flow axis A1, i.e. travel through a lateral opening 6, as it exits a fluid outlet end 3b of a second profiled section 3 of a fluid flow channel 5a, and travel into the fluid passage 4 of a first profiled section 2 of an adjacent fluid flow channel 5b.
The first profiled sections 2 and the second profiled sections 3 of each fluid flow channel 5 may have identical shapes, as illustrated in
Furthermore, the first profiled sections 2 and the second profiled sections 3 may have different cross-sectional shapes as seen in a plane P2 perpendicular to the main fluid flow axis A1 and to the main plane P1. The axes of symmetry A2, A3 may, in this case, extend either coaxially or in parallel.
As illustrated in
The cross-sectional shapes of the first profiled section 2 and the second profiled section 3 may substantially correspond to a period of a sine wave. The apex 7 may correspond to a crest of the sine wave, and the base 8 may correspond to two troughs of the sine wave. The cross-sectional shapes of the first profiled section 2 and the second profiled section 3 may also substantially correspond to a period of a square wave, a triangular wave, a sawtooth wave or any other suitable periodic wave.
The first profiled section 2 and the second profiled section 3 may be shaped such that they have substantially identical apexes 7 and bases 8. This is illustrated in
As shown in
The first profiled section 2 and the second profiled section 3 may also have complex periods as shown in
The first profiled section 2 and the second profiled section 3 may each comprise at least one stepped part 9. As shown in
The first profiled section 2 and the second profiled section 3 may each comprise a strip of web material. The web material may be one integral piece of sheet material, into which parallel, throughgoing slits are cut and strips are formed by the material located between two such adjacent slits. A number of profiled sections may be formed by one such integral piece of material, as suggested in
The web 1 may comprise a web material such as polymer, steel, or aluminum foil, and, optionally, be covered by a hygroscopic or epoxy coating.
The present invention also relates to a web matrix 10 for transfer of thermal energy and/or moisture to and/or from a fluid. The web matrix 10 comprises a plurality of webs 1 which are superimposed onto each other such that the main fluid flow axes A1 of the webs 1 extend in parallel. This is illustrated schematically in
As shown in
The apex 7 and/or the base 8 of the first profiled sections 2 and/or the second profiled sections 3 of the webs 1 may be fixedly attached to the sheet material 11, e.g. by means of adhesive such as glue, or may be non-fixed in relation to the sheet material 11. The apex 7 and/or the base 8 of the first profiled sections 2 may also be in fixed, or non-fixed, contact with adjacent and a corresponding apex 7 and/or base 8 of the second profiled sections 3.
The various aspects and implementations have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.
The reference signs used in the claims shall not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure. As used in the description, the terms “horizontal”, “vertical”, “left”, “right”, “up” and “down”, as well as adjectival and adverbial derivatives thereof (e.g., “horizontally”, “rightwardly”, “upwardly”, etc.), simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2051118-4 | Sep 2020 | SE | national |
