The present invention relates to a flow distributor for guiding a flow of fluid across a surface to be cooled, the flow distributor comprising two or more flow distributor units. More particularly, in the flow distributor according to the invention, a fluid supply to one or more of the flow distributor units can be controlled while allowing the flow distributor unit to be manufactured from a limited number of standard elements.

Large converter designs often comprise several large power modules, each requiring liquid cooling. One challenge when designing a cooling system for such a converter design is to ensure that the power modules are not only homogeneously cooled on module level, but also that all modules are equally well cooled. In order to balance the cooling of the power modules, special designs of inlet and/or outlet manifolds of the cooling system may be provided. For instance, the cooling system may be designed in such a manner that inlet openings leading fluid from the inlet manifold to the modules, or outlet openings leading fluid from the modules to the outlet manifold, have varying sizes from one module to the next. Thereby the fluid supply to the individual modules varies as a function of the size of the openings. One disadvantage of this is that the modules must be

manufactured in a customised manner, thereby increasing the manufacturing costs of the cooling system. Furthermore, the cooling system will be designed to include a fixed number of modules, i.e. the number of modules cannot be changed without fundamentally changing the design of the cooling system.

US 6,733,229 discloses an insert metering plate which is assembled to an impingement insert for use in the nozzle of a gas turbine. The metering plate can have one or more metering holes and is used to balance the cooling flow within the nozzle.

It is an object of embodiments of the invention to provide a flow distributor comprising two or more flow distributor units, in which a fluid flow through the flow distributor units can be controlled, without requiring the manufacture of separate, customised flow distributor units.

It is a further object of embodiments of the invention to provide a flow distributor comprising two or more flow distributor units, the flow distributor units being manufactured from standard parts, while allowing the fluid flow though the flow distributor units to be controlled. The invention provides a flow distributor for guiding a flow of fluid across a surface to be cooled, said distributor comprising an inlet manifold, an outlet manifold, two or more flow distributor units, each comprising a unit inlet fluidly connected to the inlet manifold and a unit outlet fluidly connected to the outlet manifold, each flow distributor unit thereby being arranged to receive fluid from the inlet manifold, via the unit inlet, and to deliver fluid to the outlet manifold, via the unit outlet, and each flow distributor unit being arranged to guide fluid flowing from the unit inlet to the unit outlet across at least a part of a surface to be cooled, and one or more customisable flow restriction devices arranged to control a flow of fluid through one or more of the flow distributor units.

The present invention relates to a flow distributor, i.e. a device which is capable of distributing a flow of fluid, such as a liquid, a gas or a mixture of liquid and gas, across a surface. When the fluid passes across the surface, the surface is cooled by means of the fluid.

The flow distributor comprises an inlet manifold, an outlet manifold and two or more flow distributor units. The inlet manifold receives fluid from a fluid source and supplies the fluid to each of the flow distributor units, i.e. the inlet manifold distributes the fluid received from the fluid source among the flow distributor units. Similarly, the outlet manifold receives fluid from each of the flow distributor units and supplies the received fluid to a fluid drain, i.e. the outlet manifold collects fluid which has passed through the flow distributor units and supplies the collected fluid to the fluid drain.

Each of the flow distributor units comprises a unit inlet and a unit outlet. The unit inlet is fluidly connected to the inlet manifold, and the flow distributor unit therefore receives fluid from the inlet manifold via the unit inlet. Similarly, the unit outlet is fluidly connected to the outlet manifold, and the flow distributor unit therefore delivers fluid to the outlet manifold via the unit outlet. Furthermore, each flow distributor unit is arranged to guide fluid flowing from the unit inlet to the unit outlet across at least a part of a surface to be cooled. Thus, fluid is passed from the inlet manifold to each of the flow distributor units, via the respective unit inlets, passes through the flow distributor units, while being guided across the surface to be cooled, thereby providing cooling to the surface, leaves the flow distributor units via the respective unit outlets, and is thereby collected in the outlet manifold. The flow distributor further comprises one or more customisable flow restriction devices arranged to control a flow of fluid through one or more of the flow distributor units. Thus, simply by customising a customisable flow restriction device for a given flow distributor unit, the flow of fluid through that flow distributor unit can be controlled, without specific design changes to the flow distributor unit, to the inlet manifold and/or to the outlet manifold.

The flow distributor may also be designed with advantage so that the two or more flow distributor units are substantially identical, and wherein the flow restriction devices are not identical. My this means the flow distributor units can be mass produced using the same mold, but can still be assembled to form a final flow distributor where the flow is tailored to the exact application desired, by the use of customisable flow restriction devices. Thereby a desired fluid distribution among the flow distributor units can be obtained, while allowing the flow distributor units to be manufactured from identical standard parts. This reduces the manufacturing costs.

The flow distributor may also be constructed wherein the customisable flow restriction devices are not accessible when the flow distributor has been assembled in contact with the surface to be cooled. By this means a flow distributor can be obtained within which the fluid flows are tailored to the exact application that the flow distributor will be used for, but after assembly such tailoring is "locked" so that it is not disturbed by further handling or assembly, or by interference from operators. The choice of how to customise the customisable flow restriction devices can be based on tests conducted under controlled conditions to account for any environmental conditions that will be experienced by the final product. Such customised settings should not be altered during assembly without good reason, and it is therefore a great advantage if the customisable flow restriction devices are inaccessible, and therefore cannot be altered, after the flow distributor has been assembled in contact with the surface to be cooled.

The customisable flow restriction device(s) may comprise one or more replaceable apertures arranged at one or more unit inlets and/or at one or more unit outlets. According to this embodiment, the fluid flow through a given flow distributor unit can be controlled simply by selecting an

appropriate aperture having an appropriate size, and arranging the selected aperture at the unit inlet and/or at the unit outlet. Apertures of various sizes may be selected for the various flow distributor units, thereby obtaining a desired distribution of fluid among the flow distributor units. Thus, the flow of fluid into the flow distributor units may be controlled by selecting replaceable apertures of various sizes.

As an alternative, the customisable flow restriction device(s) may comprise one or more movable blocking parts, each movable blocking part being movable relative to a unit inlet or a unit outlet, the position of the blocking part determining an effective size of the unit inlet or unit outlet. According to this embodiment, the fluid flow through a given flow distributor unit can be controlled simply by arranging the corresponding movable blocking part in an appropriate position, corresponding to an appropriate effective size of the unit inlet or unit outlet. For instance, the position of the blocking part may determine how large a portion of the unit inlet or unit outlet the blocking part blocks. Various positions of blocking parts may be selected for the various flow distributor units, thereby obtaining a desired distribution of fluid among the flow distributor units. The blocking part may be movable along a substantially linear direction. For instance the blocking part may be capable of performing sliding movements, e.g. moving the blocking part in front of the unit inlet or unit outlet.

As an alternative, the blocking part may be movable along a substantially rotational direction. In this case the blocking part may, e.g., be or form part of a rotating valve, controlling the flow of fluid through the unit inlet or the unit outlet.

At least one of the flow distributor units may comprise a unit inlet manifold, a unit outlet manifold, a plurality of flow cells arranged fluidly in parallel between the unit inlet manifold and the unit outlet manifold, each of the flow cells being arranged to guide fluid flowing from the unit inlet manifold to the unit outlet manifold across at least a part of the surface to be cooled. According to this embodiment, when fluid from the inlet manifold enters a flow distributor unit, it is received in the unit inlet manifold. The unit inlet manifold then distributes the fluid among the plurality of flow cells, similarly to the situation described above with respect to the inlet manifold and the flow distributor units. The fluid then passes through each of the flow cells, while being guided across at least a part of the surface to be cooled. Then the fluid is collected in the unit outlet manifold, which delivers the fluid to the outlet manifold.

Thus, according to this embodiment the fluid is guided across the surface to be cooled by means of a plurality of parallel flow paths. This provides very uniform cooling of the surface, i.e. temperature variations across the surface must be expected to be very small. Furthermore, it is possible to design the flow cells in such a manner that, in the case that an area of the surface needs more cooling than other areas of the surface, more fluid may be guided to this part in order to provide additional cooling. This is sometimes referred to as 'tailored cooling'.

The flow cells may, e.g., be formed in a baffle which can be arranged in a frame part or housing of the flow distributor unit. Each of the flow cells may define a meandering flow path. According to this embodiment, the fluid will perform a plurality of changes in direction as it flows through the flow cells. Thereby the fluid is mixed in such a manner that fluid which has been in contact with the surface to be cooled, and which has therefore been heated, is mixed with cooler fluid, which has not been in contact with the surface to be cooled. Thereby a uniform temperature distribution of the fluid flowing through a given flow cell is obtained, and the cooling potential of the fluid is utilised more efficiently.

At least one of the flow distributor units may be arranged to guide a flow of fluid across a first surface arranged adjacent to a first side of the flow distributor unit, and across a second surface arranged adjacent to a second side of the flow distributor unit. According to this embodiment, at least one of the flow distributor units guides a flow of fluid across two or more surfaces. This may, e.g., be achieved by arranging the flow cells of the flow distributor unit in such a manner that some of them guide a fluid flow across the first surface and some of them guide a fluid flow across the second surface.

The first surface may be arranged opposite to the second surface. In this case the flow distributor unit may be regarded as a 'double sided' flow distributor unit. The first surface and the second surface may, e.g., arranged opposite each other with the flow cells of the flow distributor unit arranged between the surfaces.

As an alternative, two or more surfaces may be arranged side by side, e.g. in the same plane.

The flow distributor units may be detachable from each other, and the inlet manifold and/or the outlet manifold may be formed by manifold parts forming part of the flow distributor units. According to this embodiment the flow distributor may be modular in the sense that it is formed by two or more flow distributor units which have been attached to each other in such a manner that the inlet manifold parts of the flow distributor units are interconnected in such a manner that they form an inlet manifold and/or in such a manner that the outlet manifold parts of the flow distributor units are interconnected in such a manner that the form an outlet manifold. Thereby a flow distributor having a desired number of flow distributor units can be obtained, simply by attaching the desired number of flow distributor units to each other. This allows flow distributors of various sizes to be constructed using only one kind of flow distributor unit. This reduces the manufacturing costs, without limiting flexibility of the design of the flow distributor.

The invention will now be described in further detail with reference to the accompanying drawings in which Fig. 1 is a perspective view of a part of a flow distributor unit for a flow distributor according to an embodiment of the invention,

Fig. 2 is a perspective view of a flow distributor according to an embodiment of the invention, and comprising seven flow distributor units, Fig. 3 shows a detail of the flow distributor of Fig. 2,

Fig. 4 shows a flow distributor according to an alternative embodiment, illustrating flow cells of the flow distributor units,

Fig. 5 shows a detail of the flow distributor of Fig. 4, Figs. 6-9 illustrate a customisable flow restriction device for a flow distributor according to a first embodiment of the invention, and

Figs. 10-13 illustrate a customisable flow restriction device for a flow distributor according to a second embodiment of the invention.

Fig. 1 is a perspective view of a part of a flow distributor unit 1 according to an embodiment of the invention. The flow distributor unit 1 comprises a unit inlet manifold 2 and a unit outlet manifold 3. The part shown in Fig. 1 is adapted to receive a baffle defining a plurality of flow cells in such a manner that fluid entering the unit inlet manifold 2 is distributed among the flow cells. The fluid then flows through the flow cells and is collected in the unit outlet manifold 3. In Fig. 1 the baffle is not shown in order to allow the interior of the flow distributor unit 1 to be seen.

The flow distributor unit 1 of Fig. 1 further comprises an inlet tube 4 and an outlet tube 5. The unit inlet manifold 2 is fluidly connected to the inlet tube 4, via a unit inlet 6. Thereby fluid is allowed to flow from the inlet tube 4 to the unit inlet manifold 2. Similarly, the unit outlet manifold 3 is fluidly connected to the outlet tube 5, via a unit outlet (not shown). Thereby fluid is allowed to flow from the unit outlet manifold 3 to the outlet tube 5.

The inlet tube 4 and the outlet tube 5 are adapted to be connected to inlet tubes 4 and outlet tubes 5 of another, identical, flow distributor unit 1 in order to form a flow distributor comprising two or more flow distributor units 1 . When the inlet tubes 4 and outlet tubes 5 are connected in this manner, they form an inlet manifold and an outlet manifold, respectively, being fluidly connected to the unit inlet manifolds 2 and unit outlet manifolds 3,

respectively, of each of the flow distributor units 1 . This will be described in further detail below.

Fig. 2 is a perspective view of a flow distributor 7 comprising seven flow distributor units 1 of the kind shown in Fig. 1 . It can be seen from Fig. 2 that the inlet tubes 4 of the seven flow distributor units 1 have been

interconnected in such a manner that an inlet manifold 8 has been formed, and that the outlet tubes 5 of the seven flow distributor units 1 have been interconnected in such a manner that an outlet manifold 9 has been formed. It is also clear from Fig. 2 that, in the case that a flow distributor 7 having eight flow distributor units 1 is desired, a further flow distributor unit 1 can simply be added to the flow distributor 7. Similarly, in the case that a flow distributor 7 having six flow distributor units 1 is desired, one of the flow distributor units 1 can simply be removed.

Fluid flowing into the inlet manifold 8 is distributed among the flow distributor units 1 , flows through the flow distributor units 1 in the manner described above, and is collected in the outlet manifold 9. Fig. 3 shows a detail of the flow distributor 7 of Fig. 2. In Fig. 3 the unit inlets 6 of three of the flow distributor units 1 have been provided with a customisable flow restriction device in the form of a replaceable aperture. The apertures are formed in plates 10a, 10b, 10c which can be attached in a removable manner at the unit inlet 6. The aperture formed in plate 10a is larger than the aperture formed in plate 10b, which in turn is larger than the aperture formed in plate 10c. Thus, the fluid flow through the flow distributor unit 1 having the plate 10a attached at the unit inlet 6 is higher than the fluid flow through the flow distributor unit 1 having the plate 10b attached at the unit inlet 6. Furthermore, the fluid flow through the flow distributor unit 1 having the plate 10b attached at the unit inlet 6 is higher than the fluid flow through the flow distributor unit 1 having the plate 10c attached at the unit inlet 6.

Thus, the fluid flow through each of the flow distributor units 1 can be controlled simply by selecting a plate 10 with an aperture of an appropriate size, and attaching the plate 10 at the unit inlet 6 of the flow distributor unit 1 . In particular, the distribution of fluid among the flow distributor units 1 can be controlled or adjusted by selecting appropriate plates 10 for the various flow distributor units 1 . The plates 10 may be provided with different marks and/or colours in order to allow personnel assembling the flow distributor 7 to easily distinguish the plates 10.

In one of the flow distributor units 1 a plurality of flow cells 1 1 are provided in the form of a baffle mounted in the flow distributor units 1 .

Fig. 4 shows a flow distributor 7 according to an alternative embodiment of the invention. In Fig. 4 each of the flow distributor units 1 has been provided with a plurality of flow cells 1 1 formed as an integral part of each flow distributor unit 1 , each flow cell being fluidly interconnected between the unit inlet manifold and the unit outlet manifold of the corresponding flow distributor unit 1 . As an alternative, the flow cells could be provided by means of a separate baffle mounted in the flow distributor unit, e.g. a flow distributor unit of the kind illustrated in Figs. 1 -3. Fig. 5 shows a detail of the flow distributor 7 of Fig. 4, the flow distributor 1 comprising a customisable flow restriction device as illustrated in Fig. 3. Fig. 5 illustrates how the plate 10a with the aperture is arranged at the unit inlet 6 of a flow distributor unit 1 . It is clear from Fig. 5 that the plate 10a is a separate part, which can be detached and possibly replaced by another plate 10 having an aperture of a different size. As described above, the fluid flow through the flow distributor unit 1 can thereby be controlled or adjusted.

Figs. 6-9 illustrate a customisable flow restriction device for a flow distributor 7 according to a first embodiment of the invention. The flow distributor 7 may, e.g. be the flow distributor 7 illustrated in one or more of Figs. 2-5.

Fig. 6 shows a part of a flow distributor unit 1 of the flow distributor 7 with a manipulating button 12 which can be rotated from a position indicating '0' to a position indicating Ί ΟΟ'. Rotating the manipulating button 12 between these two extreme positions will cause a movable blocking part (not shown) being operatively connected to the manipulating button 12 to move between a position in which 0% of the unit inlet is un-blocked by the movable blocking part, i.e. a maximum flow passage, and a position in which 100% of the unit inlet is un-blocked, i.e. no flow passage. Thus, the effective size of the unit inlet can be selected by rotating the manipulating button 12 to a suitable position. This will be described in further detail below.

Fig. 7 shows the flow distributor unit of Fig. 6. It can be seen that the manipulating button 12 is connected to a rotatable blocking part 13 having an aperture formed therein. In Fig. 7 the aperture of the blocking part 13 is arranged in such a manner that it is aligned with the unit inlet 6 of the flow distributor unit 1 . Thus, the manipulating button 12 is arranged in the position indicating Ί 00Λ Accordingly, the flow passage from the inlet manifold 8 into the flow distributor unit 1 is as large as possible, and therefore the fluid flow through the flow distributor unit 1 is at a maximum level.

In Fig. 8 the manipulator button 12 has been rotated away from the position indicating '100' in a direction towards the position indicating Ό'. Thereby the blocking part 13 has been rotated in such a manner that the aperture of the blocking part 13 is no longer completely aligned with the unit inlet 6.

Accordingly, the size of the flow passage from the inlet manifold 8 into the flow distributor unit 1 has decreased as compared to the situation illustrated in Fig. 7. However, the unit inlet 6 is not completely blocked by the blocking part 13, and a fluid flow through the flow distributor unit 1 is therefore allowed, even though it is reduced as compared to the situation illustrated in Fig. 7.

In Fig. 9 the manipulator button 12 has been rotated even further in a direction towards the position indicating Ό'. As a result the blocking part 13 has been rotated to a position, where the unit inlet 6 is almost blocked by the blocking part 13, i.e. the flow passage from the inlet manifold 8 into the flow distributor unit 1 has decreased even further, and is very small. Accordingly, the fluid flow through the flow distributor unit 1 is very low.

If each of the flow distributor units 1 of a flow distributor 7 is provided with a manipulator button 12 and a blocking part 13 as illustrated in Figs. 6-9, the distribution of fluid among the flow distributor units 1 can be controlled simply by rotating the manipulator button 12 of each flow distributor unit 1 to an appropriate position. Figs. 10-13 illustrate a customisable flow restriction device 14 for a flow distributor 7 according to a second embodiment of the invention. The flow distributor 7 may, e.g. be the flow distributor 7 illustrated in Figs. 2-5. Fig. 10 is a perspective view of the flow restriction device 14, illustrating a unit inlet 6, a manipulator button 12 and a movable blocking part 13. The manipulator button 12 is movable along a substantially linear direction. The manipulator button 12 is further connected to the blocking part 13 in such a manner that when the manipulator button 12 is moved linearly, the blocking part 13 performs a corresponding linear or sliding movement. Thereby the blocking part 13 is moved relative to the unit inlet 6 in a manner which will be described in further detail below.

Figs. 1 1 -13 are side views of the flow restriction device 14 of Fig. 10. The flow restriction device 14 is shown transparently in order to show the blocking part 13 moving inside the flow restriction device 14.

In Fig. 1 1 the manipulator button 12 is arranged as far as possible to the left. Thereby the blocking part 13 is arranged in a position where it completely blocks the unit inlet 6. Accordingly, a fluid flow into the flow distributor unit is prevented.

In Fig. 12 the manipulator button 12 has been moved away from the position illustrated in Fig. 1 1 , towards the right. Thereby the blocking part 13 has been moved partly away from the unit inlet 6. Accordingly, a fluid flow through the flow distributor unit is allowed, but it is restricted due to the blocking part 13 being arranged in such a manner that it partly blocks the unit inlet 6.

In Fig. 13 the manipulator button 12 has been moved even further to the right. Thereby the blocking part 13 has been moved completely away from the unit inlet 6. Accordingly, a maximum fluid flow is allowed through the flow distributor unit.

If each of the flow distributor units 1 of a flow distributor 7 is provided with a manipulator button 12 and a blocking part 13 as illustrated in Figs. 10-13, the distribution of fluid among the flow distributor units 1 can be controlled simply by sliding the manipulator button 12 of each flow distributor unit 1 to an appropriate position.