Patent Application
20160109190
The present invention relates to a flow distribution module for distributing a flow of fluid over a surface to be cooled. The flow distribution module of the invention is capable of cooling the surface in a very efficient manner.
Flow distribution modules f or distributing a flow of fluid over a surface to be cooled, there by providing cooling for the surface, have previously been provided. For instance, WO 2005/040709 discloses a flow distribution unit and cooling unit in which a plurality of flow cells are arranged to convey a flow of fluid over a surface to be cooled. The flow cells are connected fluidly in parallel between an inlet manifold and an outlet manifold, and the flow cells may define meandering flow paths. DE 202 08 106 U1 discloses a similar cooling device.
In the distribution units disclosed in WO 2005/040709 and DE 202 08 106 U1 the surface being cooled is substantially plane.
It is an object of embodiments of the invent ion to provide a flow distribution module in which heat transfer from a surface to be cooled to fluid flowing in the flow distribution module is improved as compared to prior art flow distribution modules.
It is a further object of embodiments of the invention to provide a flow distribution module in which the risk of clogging of the flow distribution module is minimised.
It is an even further object of embodiments of the invention to provide a flow distribution module in which pressure drop of fluid flowing through the flow distribution module is minimised.
The invention provides a flow distribution module for distributing a flow of fluid over a surface to be cooled, said flow distribution module comprising:
The flow distribution module of the invention is adapted to distribute a flow of fluid over a surface to be cooled. Thus, when fluid flows through the flow distribution module, it flows along the surface, and thereby heat is transferred from the surface to the fluid flowing in the flow distribution module. Accordingly, the fluid conveys the heat away from the surface, and the surface is thereby cooled.
The fluid flowing in the flow distribution module may advantageously be a liquid, such as water or a mixture of ethylene-glycol and water. As an alternative, the fluid may be a two-phase refrigerant, such as R134a. As another alternative, the fluid may be gaseous.
The flow distribution module comprises a housing defining at least one flow cell. Each flow cell has an inlet opening arranged to receive fluid and an outlet opening arranged to deliver fluid. Accordingly, fluid can be received at the inlet opening, flow through the flow cell, via a flow path defined by the flow cell, and finally be delivered from the flow cell at the outlet opening. The flow cell(s) is/are arranged in such a way that when fluid flows through the flow cell(s) as described above, the fluid is conveyed over the surface to be cooled. Accordingly, heat is transferred from the surface to the fluid flowing in the flow cell(s).
Each flow cell is formed to cause at least one change in the direction of flow of the fluid flowing through the flow cell. When the direction of flow of the fluid flowing through a flow cell is changed, the fluid is swirled. Thereby the hot fluid, which is in direct contact with the surface to be cooled, is mixed with the cooler fluid flowing at a distance to the surface to be cooled. This allows the cooling capacity of the fluid to be utilised fully. Furthermore, the swirl provided by the change in direction of flow of the fluid in itself forces the fluid towards the surface to be cooled in a beneficial manner. This will be described further below.
Such a change of direction is beneficial to the process of cooling, and it has been found that a significant change of direction is helpful in enhancing cooling. Thus a change in direction of over 20° is beneficial, and one of 180° is particularly beneficial in producing mixing and swirl. Thus the change of direction can be, with benefit, in the range 20° to 180°, such as in the range of 30° to 180°, such as in the range 90° to 180°. The change of direction can be in the direction perpendicular to the plane of the surface to be cooled, in the direction parallel to the plane of the surface to be cooled, or in a combination of the two. A change of direction perpendicular to the plane of the surface to be cooled may, for example, be enabled by the surface pattern provided. A change of direction parallel to the plane of the surface to be cooled may, for example, be enabled by the design of the flow cell(s), in particular by the distribution of walls which cause deviations in the direction of flow of the fluid over the surface to be cooled.
The flow cell(s) may advantageously be formed to cause a plurality of changes in the direction of flow of the fluid flowing through the flow cell(s). Thereby the swirl of the fluid is even more significant.
The flow distribution module further comprises a cover plate arranged adjacent to the flow cell(s). The cover plate defines the surface to be cooled. For instance, the surface to be cooled may be a surface of the cover plate which faces the flow cell(s), i.e. which is arranged directly in contact with the fluid flowing in the flow cell(s).
At least a part of the surface to be cooled is provided with a surface pattern of raised and depressed surface portions. Thereby the surface area of the surface to be cooled is enlarged as compared to a similar surface which is substantially plane. Accordingly, the contact area between the surface to be cooled and the fluid flowing in the flow cell(s) is increased, and thereby the transfer of heat from the surface to be cooled to the fluid flowing in the flow cell(s) becomes more efficient.
It should be noted that the raised and depressed surface portions of the surface pattern are ‘raised’ and ‘depressed’ relative to each other in the sense that the raised surface portions are arranged further away from a surface of the cover plate arranged opposite to the surface to be cooled, than the depressed surface portions. The surface pattern may be provided in such a manner that the depressed surface portions are arranged at a level corresponding to the level of a part of the surface to be cooled which is not provided with the surface pattern, while the raised surface portions protrude outwards from this level. As an alternative, the raised surface portions may be arranged at said level, while the depressed surface portions protrude into the cover plate from this level. As another alternative, the raised surface portions may protrude outwards from said level, while the depressed surface portions protrude into the cover plate from said level. This last alternative has the distinct advantage that it is possible to generate such a pattern by relatively small scale movement of material from which the surface pattern is created. For example, such a pattern may be made by means of punching, stamping, rolling or similar techniques in which with in a local area, a small depression formed in the material is matched by a protrusion of similar size in close proximity. Such manufacturing techniques are relatively cheap, and a surface pattern created using them is easily and cheaply manufactured at low cost, leading to an improved and competitive product.
In order to utilise the enlarged surface area of the surface to be cooled, which is provided by the surface pattern, it must be ensured that the fluid flowing in the flow cell(s) is brought into contact with the entire enlarged surface. Thus, the fluid must be forced ‘into’ the surface pattern. This can, e.g., be achieved by designing the flow cell(s) in such a manner that the cross sectional area of the flow path(s) defined by the flow cell(s) is small, thereby forcing the fluid to follow the raised and depressed surface portions closely. However, this has the disadvantage that the risk of clogging of the flow path(s) is very high. Furthermore, a large pressure drop of the fluid flowing through the flow cell(s) must be expected.
However, in the flow distribution module according to the invention, the flow cell(s) is/are formed to cause at least one change in the direction of flow of the fluid flowing through the flow cell(s). As described above, this causes the fluid to be swirled, and this swirl ensures that the fluid is forced towards the surface to be cooled and into the surface pattern, thereby bringing the fluid into contact with the entire enlarged surface area. Thereby, the enlarged surface area of the surface to be cooled can be utilised, while maintaining relatively large dimensions of the flow path(s) defined by the flow cell(s).
Accordingly, the combination of designing the flow cell(s) to provide at least one change in the direction of flow of the fluid flowing through the flow cell(s), and providing the surface pattern of raised and depressed surface portions on the surface to be cooled, allows efficient heat transfer from the surface to be cooled to the fluid flowing in the flow cell(s), without risking clogging of the flow path(s) of the flow cell(s), and without introducing a large pressure drop of the fluid flowing through the flow cell(s). This is very advantageous. Furthermore, the combination of the increased surface area provided by the surface pattern, and the mixture of the fluid caused by the swirl improves the heat transfer of the flow distribution module, and thereby the cooling performance of the flow distribution module.
The surface pattern may, e.g., be provided by means of punching, stamping, rolling or similar techniques. In this case the surface pattern is formed directly in a surface of the cover plate during manufacture of the cover plate.
It should be noted that, even though the description above refers to ‘a surface to be cooled’ and ‘the surface to be cooled’, the flow distribution module of the invention may be used for cooling two or more surfaces, each being arranged adjacent to one or more flow cells in an appropriate manner.
The flow distribution module may further comprise an inlet manifold and an outlet manifold, and the housing may define at least two flow cells, the inlet opening of each flow cell being fluidly connected to the inlet manifold and the outlet opening of each flow cell being fluidly connected to the outlet manifold, each flow cell thereby establishing a fluid connection between the inlet manifold and the outlet manifold. According to this embodiment, the flow cells cover various parts of the surface to be cooled, and it is thereby possible to provide more intensive cooling to some parts of the surface than to other parts.
The flow cells may be arranged fluidly in parallel between the inlet manifold and the outlet manifold, the flow cells thereby defining parallel flow paths between the inlet manifold and the outlet manifold. According to this embodiment, each flow cell is directly fluidly connected to the inlet manifold via its inlet opening, and directly fluidly connected to the outlet manifold via its outlet opening. Thereby the fluid entering each of the flow cells has the same temperature. This allows uniform cooling to be provided across the surface to be cooled, i.e. temperature variations across the surface can be minimised.
As an alternative, two or more of the flow cells may be arranged fluidly in series. In this case the inlet opening of a first flow cell may be fluidly connected directly to the inlet manifold, the outlet opening of the first flow cell may be fluidly connected to the inlet opening of a second flow cell, and the outlet opening of the second flow cell may be fluidly connected directly to the outlet manifold. Thus, the first flow cell is fluidly connected to the outlet manifold via the second flow cell, and the second flow cell is fluidly connected to the inlet manifold via the first flow cell.
The inlet manifold and the outlet manifold may be defined by the housing. According to this embodiment, the housing, the inlet manifold, the outlet manifold and the flow cells may be formed as a single part, and the cover plate may be mounted on this part, thereby forming a closed unit with the flow cells and the manifolds arranged inside the closed unit. This allows the manufacturing costs of the flow distribution module to be minimised.
At least one flow cell may define a meandering flow path. According to the this embodiment, the change(s) in direction of flow of the fluid flowing through the flow cell(s) is/are primarily caused by the fluid following the meandering path. As an alternative, the change(s) in direction of flow of the fluid flowing through the flow cell(s) may be obtained in another way.
For instance, each flow cell may comprise a surface arranged opposite and facing the surface to be cooled, the surface of the flow cell being provided with a surface pattern which, e.g., is a mirror image of the surface pattern provided on the surface to be cooled, or a surface pattern which is identical or similar to the surface pattern provided on the surface to be cooled. If the two surfaces are arranged sufficiently close to each other, the surface patterns of the surface to be cooled and the surface of the flow cell, respectively, may cooperate to cause the fluid flow to change direction as the fluid flows through the flow cell. In the case that the two surface patterns are identical, the surface patterns may, e.g., be arranged in such a manner that raised surface portions are arranged opposite to each other and depressed surface portions are arranged opposite to each other. In this case the distance between the surfaces varies across the surface patterns, and this variation gives rise to the swirl of the fluid flowing through the flow cell. As an alternative, the surface patterns may be arranged in such a manner that raised surface portions of one surface pattern are arranged opposite depressed surface portions of the other surface pattern, and vice versa. In this case the distance between the surfaces is substantially constant across the surface patterns, but the direction of flow of the fluid is changes as the fluid follows the raised and depressed surface portions. The change in direction of the fluid flow may occur in a direction towards and away from the surfaces, and/or in a direction substantially parallel to the surfaces, in order to ‘navigate’ the fluid around the surface structures defined by the surface patterns.
The surface pattern may define a sub-pattern which is repeated along at least one direction of the surface pattern. The sub-pattern may be repeated along only one direction of the surface pattern, or it may be repeated along two or more directions of the surface pattern. In the case that the sub-pattern is repeated along only one direction of the surface pattern, the surface pattern may be in the form of a corrugated surface defining ‘grooves’ and ‘ridges’ arranged alternatingly on the surface in a manner which resembles a linearly evolving wave front. The ‘grooves’ and ‘ridges’ may have substantially sinusoidal shapes, triangular shapes, squared shapes, or any other suitable shapes.
In the case that the sub-pattern is repeated along two or more directions of the surface pattern, the surface pattern may comprise ‘islands’ of raised surface portions surrounded by depressed surface portions. In this case the surface pattern may, e.g., comprise structures of pyramid-like, conical, spherical or hemispherical shape. The raised surface portions and the depressed surface portions may have essentially the same shape, for instance the raised surface portion being pyramids protruding from the surface to be cooled, and the depressed surface portions being pyramid shaped depressions in the surface.
In the case that the raised and depressed surface portions have rounded shapes, such as sinusoidal, spherical or hemispherical, the risk of corrosion of the surface structure during operation is minimised.
The raised surface portions of the surface pattern may define raised height levels and the depressed surface portions of the surface pattern may define depressed height levels. In this case an average height difference between the raised height levels and the depressed height levels may be within the interval of 0.2 mm to 5 mm, such as within the interval 0.5 mm to 3 mm, such as within the interval 0.7 mm to 2 mm, such as approximately 1 mm. According to this embodiment, the raised height levels could be the levels of top points of pyramids, cones, ridges, hemispheres, etc. forming the raised surface portions. Thus, the raised height levels may be regarded as local maxima of the surface pattern. Similarly, the depressed height levels could be the levels of local minima of the surface pattern, defined by the depressed surface pattern. Thereby the average height difference between the raised height levels and the depressed height levels is a measure for the depth of the surface pattern, i.e. the typical difference between extremes of the surface pattern. Thus, according to this embodiment, the depth of the surface pattern is relatively low, i.e. the structures of the surface pattern are relatively small. When the structures of the surface pattern are small, it is difficult to ensure that the fluid flowing through the flow cell(s) enters into the surface pattern, and it is therefore in particular an advantage that the fluid is swirled due to the at least one change of direction of the fluid flow in this case.
Alternatively or additionally, the average height difference between the raised height levels and the depressed height levels may be within the interval 10% to 60%, such as within the interval 20% to 55%, such as within the interval 30% to 50% of an average height of a flow channel defined by the flow cell(s). According to this embodiment, the dimensions of the structures of the surface structure are significantly smaller than the typical dimensions of the flow path(s) defined by the flow cell(s). In this case it is also a great advantage that the fluid is swirled due to the at least one change of direction of the fluid flow, thereby forcing the fluid into the surface structure and ensuring that the enlarged surface area is utilised.
Alternatively or additionally, a median surface level over the area provided with the surface pattern may define a surface plane. The median height of peaks defined by the raised surface portions, measured from the surface plane, may define a peak plane. Similarly, the median depth of troughs defined by the depressed surface portions, measured from the surface plane, may define at rough plane. In this case the separation between the peak plane and the trough plane, measured in a direction normal to the surface plane, may be with in the interval 0.2 mm to 5 mm, such as within the interval 0.5 mm to 3 mm, such as with in the interval 0.7 mm to 2 mm, such as approximately 1 mm. This is also a measure for the ‘depth’ or roughness of the surface pattern, and the remarks set forth above are equally applicable here.
The cover plate may be mounted on the housing in a substantially fluid tight manner. This may, e.g., be obtained by welding or gluing the cover plate onto the housing. Alternatively, the cover plate may be mounted on the housing in a reversible manner, e.g. by means of screws or bolts. In this case a sealing element, such as an o-ring, may advantageously be arranged between the housing and the cover plate in order to ensure that the assembly is fluid tight.
The flow distribution module may further comprise at least one power module mounted on a surface the cover plate which is opposite to the surface having the surface pattern provided thereon. The power module may, e.g., be a semiconductor power module. Power modules produce heat. By mounting the power module on the cover plate, the power module can be cooled by means of the fluid flowing in the flow cell(s) of the flow distribution module.
The power module(s) may be arranged in a region of the cover plate where the surface pattern is provided. Thereby the power module is efficiently cooled, as described above.
The surface to be cooled may comprise two or more separate regions, each being provided with a surface pattern, the patterned regions being separated by regions with no surface pattern. In this case two or more power modules, or other heat producing elements, may be mounted on the cover plate, and each power module may be mounted at a position corresponding to the position of a patterned region. Furthermore, a zone along the edge of the cover plate may be left without surface pattern in order to ensure that a proper sealing can be provided between the housing and the cover plate.
At least the cover plate may be made from a metal, such as copper.
The invention will now be described in further detail with reference to the accompanying drawings in which
Six heat producing power modules 4 are mounted on the cover plate 3. The power modules 4 are thereby cooled by means of fluid flowing through the flow cell(s) defined by the housing 2.
The housing 2 defines a plurality of flow cells 5. Each flow cell 5 comprises an inlet opening 6, which is fluidly connected to an inlet manifold (not visible), and an outlet opening 7, which is fluidly connected to an outlet manifold (not visible). Thus, each flow cell 5 establishes a flow path between the inlet manifold and the outlet manifold, and the flow paths are arranged fluidly in parallel between the inlet manifold and the outlet manifold.
Each of the flow cells 5 defines a meandering flow path. Thereby fluid flowing through a flow cell 5 from the inlet opening 6 to the outlet opening 7 is caused to perform a plurality of changes in the direction of flow of the fluid. As described above, this causes the fluid to ‘swirl’, thereby forcing the fluid towards a cover plate to be mounted on the housing 2 in such a manner that it covers the flow cells 5, and in such a manner that a surface of the cover plate is arranged in direct contact with fluid flowing through the flow cells 5.
A centre region of the cover plate 3 is provided with a surface pattern 8 of raised and depressed surface portions. Thereby the surface area in the region of the surface pattern 8 is enlarged, and it is therefore possible to provide efficient cooling to heat producing elements, such as the power modules 4 shown in
When the cover plate 3 is mounted on a housing in order to form a flow distribution module, it is mounted in such a manner that the surface pattern 8 faces the flow cell(s), e.g. the flow cells 5 shown in
Whereas the cover plate 3 of
It is clear from
However, the swirl of the fluid provided by the plurality of changes of direction of the fluid flow, caused by the meandering flow path, ensures that the fluid is forced into the surface pattern 8, thereby bringing it into contact with the entire enlarged surface area. As a consequence, the surface of the cover plate 3 being provided with the surface pattern 8 can be efficiently cooled.
In
The housing 2 defines a flow cell comprising a surface which is provided with a surface pattern which is essentially a mirror image of the surface pattern 8 provided on the cover plate 3. When fluid is flowing in the flow cell, it is forced to follow passages defined between raised surface portions of the surface pattern 8 provided on the cover plate 3 and the raised surface portions of the surface pattern 9 provided in the flow cell. Thereby the fluid is forced to perform a plurality of changes in the direction of flow. Accordingly, the fluid is forced into the surface pattern 8 provided on the cover plate 3, and thereby the fluid is brought into contact with the entire enlarged surface area provided by the surface structure 8, and ensuring an efficient cooling of the cover plate 3. This is obtained without having to decrease the distance between the surface patterns 8, 9, thereby increasing the risk of clogging and excessive pressure drop of the fluid flowing through the flow cell.
In the flow distribution module 1 of
As an alternative, the surface patterns 8, 9 could be shifted relative to each other, in such a way that the raised surface portions of surface pattern 8 could be arranged opposite depressed surface portions of surface pattern 9, and depressed surface port ions of surface pattern 8 could be arranged opposite raised surface portions of surface pattern 9. In this case the ‘swirl’ of the fluid is provided by the fluid ‘navigating’ around the raised surface portions of the surface patterns 8, 9. This ‘navigation’ could take place in a direction towards and away from the surface patterns 8, 9, and/or in a direction substantially parallel to the surface patterns 8, 9, i.e. sideways through the flow cell.
Each of the flow cells 5 defines a meandering flow path. Thereby fluid flowing through a flow cell 5 from the inlet opening 6 to the outlet opening 7 is caused to perform a plurality of changes in the direction of flow of the fluid. As described above, this causes the fluid to ‘swirl’, thereby forcing the fluid towards a cover plate to be mounted on the housing 2 in such a manner that it covers the flow cells 5, and in such a manner that a surface of the cover plate is arranged in direct contact with fluid flowing through the flow cells 5.
Although various embodiments of the present invention have been described and shown, the invention is not restricted thereto, but may also be embodied in other ways within the scope of the subject-matter defined in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 12007006.5 | Oct 2012 | EP | regional |
This application is entitled to the benefit of and incorporates by reference subject matter disclosed in International Patent Application No. PCT/EP2013/071006 filed on Oct. 9, 2013 and European Patent Application 12007006.5 filed Oct. 9, 2012.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2013/071006 | 10/9/2013 | WO | 00 |
