APPARATUS

Abstract

The present disclosure relates to an apparatus having an evaporator with a base plate having a first surface for receiving a heat load from one or more electric components, tubes that partly penetrate into the base plate via a second surface of the base plate for providing evaporator channels which are embedded into the base plate and condenser channels which are located outside of the base plate. In order to obtain a compact and efficient apparatus, the connecting parts can include hollow sections located within the tubes, each hollow section connecting the channels of a tube to each other in a vicinity of an end of the tube in order to allow fluid to flow between the channels of the tube via the hollow section.

Description

RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to European Patent Application No. 1 3170378.7 filed in Europe on Jun. 4, 2013, the entire content of which is hereby incorporated by reference in its entirety.

FIELD

This disclosure relates to an apparatus with an evaporator for receiving a heat load from one or more electric components in order to provide adequate cooling for the components.

BACKGROUND INFORMATION

Closed electric cabinets, such as cabinets containing drives controlling the operation of electric motors, can employ cooling devices for ensuring that heat generated by the electric components do not raise the temperature inside the cabinets to a level where damage may occur.

These known cooling devices can include heat sinks or heat exchangers receiving heat loads from the electric components, and via which a cooling air flow passes for dissipating the heat load to the surrounding environment. Such known cooling devices can include metal pieces without any kind of fluid circulation, or of devices with fluid circulation and which employ a pump for generating the fluid circulation.

There also exists more efficient apparatuses for cooling electric components, such as thermosyphons, capable of circulating a cooling fluid without a need for a pump. It would be desirable to utilize such apparatuses in older electric cabinets which have originally been manufactured to include known heat sinks or heat exchangers.

Such more efficient apparatuses, however, can have shape and dimensions in question. Due to the shape and dimensions these more efficient known apparatuses cannot be utilized to the extent otherwise possible.

SUMMARY

An apparatus is disclosed comprising: an evaporator with a first surface for receiving a heat load from one or more electric components; tubes having internal longitudinal walls dividing the tubes into channels, wherein the tubes partly penetrate into the evaporator for providing evaporator channels which are embedded into the evaporator; and condenser channels which are located outside of the evaporator: connecting parts at first and second ends of the tubes for passing fluid from the evaporator channels into the condenser channels and for passing fluid from the condenser channels into the evaporator channels, the connecting parts having hollow sections located within the tubes, each hollow section connecting the channels of a tube to each other in a vicinity of an end of the tube in order to allow fluid to flow between the channels of the tube via the hollow section; and fins extending between the condenser channels of adjacent tubes.

BRIEF DESCRIPTION OF DRAWINGS

In the following, embodiments of the present invention will be described in closer detail by way of example and with reference to the attached drawings, in which:

FIG. 1 illustrates a working principle of an exemplary apparatus disclosed herein;

FIGS. 2 to 4 illustrate an exemplary apparatus disclosed herein;

FIGS. 5 to 8 illustrate a second exemplary embodiment of an apparatus as disclosed herein; and

FIGS. 9 and 10 illustrate alternative exemplary tube designs.

DETAILED DESCRIPTION

The present disclosure provides an apparatus where the shape and dimensions of the apparatus can place less restrictions on installations where the apparatus can be utilized.

The use of connecting parts including hollow sections located within the tubes, which hollow sections connect the channels of a tube to each other in the vicinity of an end of the tube, makes it possible to obtain efficient circulation between evaporator channels and condenser channels without a need for a large fluid distribution element at the ends of the tubes. Therefore the shape and dimensions of the apparatus may be selected more freely than previously.

The FIG. 1 apparatus 1 includes an evaporator 2 including a base plate for receiving a heat load 3 from one or more electric components. The electric components may be directly attached to the evaporator of aluminum, for instance.

One or more tubes 4 with internal longitudinal walls 5 penetrate partly into the second surface 22 of the evaporator 2 such that at least one channel of the penetrating tubes can be embedded in the base plate 2 to form an evaporator channel 6. Fluid located in this evaporator channel 6 (or evaporator channels 6) receives the heat load 3 via the base plate. Due to temperature rise and evaporation, the fluid will flow upwards in the evaporator channel 6 in the illustrated example.

A hollow section 8 within each tube 4, in other words an end section of the tube where no internal walls are present, connects the channels 6 and 7 of each tube to each other in a first end 10 of the tubes 4 in order to allow fluid to flow between the channels 6 and 7 of the tubes 4.

The channels located outside the evaporator 2 are condenser channels 7. The fluid which has entered the condenser channels 7 will be cooled while moving towards the second end 11 of the tubes 4. The cooling may be accomplished by transfer of heat from the fluid through the walls of the condenser channels 7 to the surrounding air.

A hollow section 9 within each tube 4, in other words an end section of the tube where no internal walls are present, connects the channels 7 and 6 of each tube to each other in the second end 11 of the tubes 4 in order to allow fluid to flow between the channels 7 and 6 of the tubes 4. Consequently, the cooled fluid is returned from the condenser channels 7 to the evaporator channels 6 for a new cycle. In practice, the returning fluid has condensed into a liquid state.

In the illustrated position the fluid circulation occurs without a pump due to gravity, the temperature differences and the density differences of the fluid (liquid/vapour) in different parts of the apparatus. In order to ensure efficient circulation of the fluid and to ensure that adequate circulation occurs also when the apparatus is in another position (such as in the horizontal position of FIGS. 2 to 4) than in the illustrated upright position, some of the channels 6 or 7 of the tube 4 may have capillary dimensions. In that case, if the condenser channels 7 returning fluid from the first end 10 of the apparatus to the second end 11 of the apparatus have capillary dimensions, a flow of fluid from the first end 10 to the second end 11 may take place also when the apparatus is in another position than the upright position illustrated in FIG. 1. In this context “capillary dimensions” refers to channels that are capillary sized, in which case they have a size small enough so that bubbles can grow uniquely in a longitudinal direction (in other words in the flow direction as opposed to the radial direction) and thereby create a pulsating effect (bubble pumping or bubble lift effect) by pushing the liquid. In this example they are capillary sized so that no additional capillary structures are needed on their internal walls. The diameter of a channel which is considered capillary depends on the fluid that is used (boiling) inside.

The following formula, for example, can be used to evaluate a suitable diameter:

D=(sigma/(g*(rhol−rhov)))̂0.5,

where sigma is the surface tension, g the acceleration of gravity, rhov the vapor density and rhol the liquid density. This formula gives exemplary values from 1 to 3 mm for R134a (Tetrafluoroethane), R145fa and R1234ze (Tetrafluoropropene), which are exemplary fluids suitable for use in the apparatus illustrated in the Figures.

FIGS. 2 to 4 illustrate an apparatus. The working principle and construction of the apparatus explained in FIGS. 2 to 4 are similar to the one explained in connection with FIG. 1, unless otherwise pointed out in the following explanation.

FIG. 2 illustrates the entire apparatus, FIG. 3 is a partial front view of one tube 4 and the base plate 2, and FIG. 4 illustrates a cross section of the tube 4 and base plate 2 along line A-A in FIG. 2. The illustrated apparatus may be installed in a motor drive, such as in a frequency converter utilized for controlling feed of electricity to an electrical motor.

FIG. 2 illustrates, by way of example, that the apparatus 21 includes 16 tubes 4 arranged in parallel to partly penetrate into the base plate of the evaporator 2 via a second surface 22 of the evaporator 2. As best seen in FIG. 3, at least two channels (illustrated by dotted lines) of the tubes are thereby embedded into the evaporator 2. These embedded channels work as evaporation channels 6, receiving a heat load from one or more electric components 23 attached to a first surface 24 of the base plate 2. The remaining channels located outside of the evaporator 2 work as condenser channels 7 which transfer heat from the fluid into air 25 flowing between the condenser channels 7. In order to enhance the transfer of heat into the air 25, fins 26 can, for example, be arranged to extend between the condenser channels 7 of adjacent tubes 4, as illustrated in FIG. 2.

FIG. 4 illustrates an exemplary fluid flow in more detail. The number of channels and the dimensions of the channels and the other elements may, in practice, vary significantly from what is illustrated in FIG. 4. The hollow sections 8 and 9 at the first 10 and second 11 ends of the tubes work as connecting parts allowing fluid to pass between the evaporator channels 6 and the condenser channels 7 without a need for providing the tubes or the apparatus with external fluid distribution elements outside the tubes 4 for this purpose. This makes it possible to obtain a compact and efficient apparatus. Naturally, in some embodiments it is possible to have a hollow section 8 or 9 in only one end of the tubes and a traditional external fluid distribution element in the other end of the tubes, as an extension of the tubes, for instance.

In order to ensure an even distribution of fluid within the entire apparatus, the apparatus 21 illustrated in FIGS. 2 to 4 can be provided with a manifold 27 extending through adjacent side walls of the tubes 4. The manifold 27 interconnects at least one channel of each tube 4 with each other and allows fluid to flow between all tubes. To arrange the manifold in this way has the advantage that the manifold does not require any additional space outside the ends of the tubes 4, for instance. Advantageously, the manifold 27 can include a hole extending through the base plate of the evaporator 2 and the parts of the tubes 4 (evaporator channels 6) which penetrate into the evaporator 2, as illustrated in FIGS. 2 to 4. In this way the need for using separate tubes that need to be attached to the holes in the tubes and additionally sealed against leakage at each such hole can be avoided.

In FIG. 2 it is assumed by way of example, that the end of the hole (bore) which works as the manifold 27 is plugged with a suitable plug 28. However, in order to add or remove fluid to the channels of the apparatus 21 an additional filling valve 29 provides access to one or more of the channels of the tubes 4 and/or the manifold 27. Depending on the implementation and the available space, the filling valve 29 may naturally work as the plug that plugs the end of the manifold 27, in which case it is located where the plug 28 is illustrated in FIG. 2.

The apparatus illustrated in FIGS. 2 to 4 may be manufactured such that an evaporator 2 with a base plate having a plurality of parallel grooves in the second surface 22 is produced. This may be carried out by extrusion of aluminum, for instance.

A plurality of tubes 4 with internal longitudinal walls 5 can be produced. The tubes 4 may be MPE (Multi Port Extruded) tubes which have been manufactured by extruding aluminum, for instance.

The hollow sections 8 and 9 can be produced in the selected end (or both ends) of the tubes 4 by first removing the internal walls 5 from the end of the tube. This can be done by milling with a water jet, for example. After this, the end can be plugged 30 by welding, for example, such that fluid leakage from the hollow sections 8 and 9 to the outside can be avoided.

The tubes 4 are placed into the grooves in the evaporator 2 and attached to the grooves by brazing, for instance. In case a manifold 27 is also produced by drilling through the base plate of the evaporator 2 and the parts of the tubes 4 that penetrate into the evaporator 2, then additional attention should be paid during the brazing to ensure that leak proof interfaces are obtained between the base plate 2 and the tubes 4. The plug 28 may then be welded to close the end of the manifold 27.

FIGS. 5 to 8 illustrate a second exemplary embodiment of an apparatus. The embodiment of FIGS. 5 to 8 is very similar to the one explained in connection with FIGS. 1 to 4. Therefore, the embodiment of FIGS. 5 to 8 will be explained mainly by pointing out the differences between these embodiments.

FIG. 5 illustrates the entire apparatus 21′, FIG. 5 is a partial cross section illustrating the tubes 4′ and the elongated spacer elements 31 between the tubes, and FIGS. 7 to 8 illustrate the tubes 4′ in more detail.

In the second embodiment, the tubes 4′ extend through the evaporator 2′. In the illustrated example the evaporator 2′ includes a plurality of elongated spacer elements 31 which are arranged between the tubes 4′ to keep the tubes apart from each other. Therefore, the tubes 4′ partly penetrate into the evaporator 2′ (are located between the spacers of the evaporator), and the channels located in these parts of the tubes 4′ are evaporator channels 6 that are embedded into the evaporator 2′, and the other channels of the tubes are condenser channels 7, located outside of the evaporator 2′.

Similarly, as in the previous embodiment, fins 26 can extend between condenser channels 7 of adjacent tubes 4′. Additionally, secondary spacer elements 32 may be arranged between the condenser channels 7′ of the adjacent tubes at the lower edge of the tubes, as illustrated in FIG. 6.

The second embodiment utilizes an alternative way of implementing a manifold 27′. As best seen in FIG. 5, the manifold 27′ may be arranged as an extension of the tubes 4′ to allow fluid flow via the manifold between the hollow sections of the tubes 4′. The manifold 27′ may also be provided with a filling valve 29 providing access to the channels of the tubes 4′ from the outside of the apparatus 21′.

FIGS. 9 and 10 illustrate alternative tube designs. In the following, it is by way of example assumed that the tube design according to FIG. 9 is utilized in the second embodiment of the apparatus, as illustrated in FIGS. 5 to 8. However, as an alternative, it is possible to utilize the tube design of FIG. 10 in the second embodiment.

FIG. 9 illustrates the assembly of a tube 4′. A MPE (Multi Port Extruded) tube which has been manufactured by extruding aluminum, for instance, is utilized as a wall element 33 between a pair of parallel plates 34. The MPE tube provides the tube 4′ with a plurality of internal longitudinal walls 5. These internal longitudinal walls divide the tube 4′ into channels, of which some are evaporator channels 6 and some condenser channels 7, as has been explained in connection with the embodiment of FIGS. 1 to 4.

The longitudinal length of the wall element 33 is shorter than the longitudinal length of the plates 34, as best seen in FIG. 7. Thus, hollow sections 8 and 9 are formed at the opposite ends of the tube 4′, without any need to remove parts of the internal walls 5 (as for example, in the first embodiment).

The plates 34 and the spacer elements 35 arranged between the plates 34 along opposite first edges of the plates 34, together with plug elements 30 (provided by attaching plates by welding, for example) arranged along opposite second edges of the plates 34 together delimit a fluid tight space within the tube 4′. However, naturally a hole for allowing fluid communication via the manifold 27′ may be provided in the tube 4′. The different parts of the tube 4′ may be soldered together, for example.

After production of a sufficient number of tubes 4′, spacer elements 31, secondary space elements 32 and fins 26 may be arranged between such tubes in order to assemble the apparatus 2′ illustrated in FIGS. 5 to 8. The different parts of the apparatus 2′ may be soldered together.

The alternative tube design illustrated in FIG. 10 is very similar to the one illustrated in FIG. 9. However, in FIG. 10 the wall element 33′ used in the tube 4″ is not a MPE tube, but instead can be a corrugated plate, for example. By shaping the plate into a suitable form the longitudinal internal walls 5 of the pipe 4″ can be produced.

The spacers 35 and plug elements used in tube 4″ may be similar as explained in connection with tube 4′, and the longitudinal length of the wall element 33′ is shorter than the longitudinal length of the plates 34 in order to produce the hollow sections 8 and 9 at opposite ends of the tube 4″.

It is to be understood that the above description and the accompanying figures are only intended to illustrate exemplary embodiments of the present invention. It will be apparent to a person skilled in the art that the invention can be varied and modified without departing from the scope of the invention.

Thus, it will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.

Claims

1. An apparatus comprising: an evaporator with a first surface for receiving a heat load from one or more electric components;tubes having internal longitudinal walls dividing the tubes into channels, wherein the tubes partly penetrate into the evaporator for providing evaporator channels which are embedded into the evaporator, and condenser channels which are located outside of the evaporator;connecting parts at first and second ends of the tubes for passing fluid from the evaporator channels into the condenser channels and for passing fluid from the condenser channels into the evaporator channels, the connecting parts having hollow sections located within the tubes, each hollow section connecting the channels of a tube to each other in a vicinity of an end of the tube in order to allow fluid to flow between the channels of the tube via the hollow section; andfins extending between the condenser channels of adjacent tubes.

2. The apparatus according to claim 1, comprising: a manifold extending between the tubes for allowing fluid to flow between at least one channel of each tube via the manifold.

3. The apparatus according to claim 1, comprising: a manifold having a hole extending through the evaporator and parts of the tubes which penetrate into the evaporator for allowing fluid to flow between evaporator channels of different tubes via the manifold.

4. The apparatus according to claim 1, comprising: a manifold arranged as an extension of the tubes to allow fluid to flow via the manifold between the hollow sections of the tubes.

5. The apparatus according to claim 1, comprising: at least one filling valve providing access to at least one channel or manifold of the apparatus for filling the at least one channel or manifold with fluid.

6. The apparatus according to claim 1, wherein at least some of the channels comprise: capillary dimensions.

7. The apparatus according to claim 1, wherein at least one of the tubes comprises: a pair of plates with spacer elements arranged between the plates along opposite first edges of the plates, and with plug elements along the opposite second edges of the plates, wherein the spacer elements and the plug elements adjoin the plates to delimit a fluid tight space; anda wall element arranged in the fluid tight space, the wall element having a plurality of internal walls which form longitudinal internal walls into the tube, a longitudinal length of the wall element being shorter than a longitudinal length of the plates for forming hollow sections between the plug elements and the wall element.

8. The apparatus according to claim 1, wherein the evaporator comprises: a plate with grooves into which the tubes are arranged for providing evaporator channels which are embedded into the evaporator.

9. The apparatus according to claim 1, wherein the evaporator comprises: a plurality of elongated spacer elements arranged between the tubes, wherein the spacer elements and the tubes together form said first surface.

10. The apparatus according to claim 2, comprising: at least one filling valve providing access to at least one channel or manifold of the apparatus for filling the at least one channel or manifold with fluid.

11. The apparatus according to claim 10, wherein at least some of the channels comprise: capillary dimensions.

12. The apparatus according to claim 11, wherein at least one of the tubes comprises: a pair of plates with spacer elements arranged between the plates along opposite first edges of the plates, and with plug elements along the opposite second edges of the plates, wherein the spacer elements and the plug elements adjoin the plates to delimit a fluid tight space; anda wall element arranged in the fluid tight space, the wall element having a plurality of internal walls which form longitudinal internal walls into the tube, a longitudinal length of the wall element being shorter than a longitudinal length of the plates for forming hollow sections between the plug elements and the wall element.

13. The apparatus according to claim 12, wherein the evaporator comprises: a plate with grooves into which the tubes are arranged for providing evaporator channels which are embedded into the evaporator.

14. The apparatus according to claim 12, wherein the evaporator comprises: a plurality of elongated spacer elements arranged between the tubes, wherein the spacer elements and the tubes together form said first surface.