Evaporator and cooling element

Abstract

According to an example aspect, there is provided an evaporator (100) comprising a base (110) extending in a first dimension (X) and in a second dimension (Y), which is orthogonal in respect to the first dimension (X), and one or more than one evaporation chamber(s) (130) formed into the base (110), which evaporation chamber(s) (130) are formed, at least in part, by two or more than two elongated holes (121, 122, 123) extending in the first dimension (X), wherein the elongated holes (121, 122, 123) overlap with each other in the first dimension (X) and have central axes in the second dimension (Y) offset from each other.

Description

EVAPORATOR AND COOLING ELEMENTFIELD

[0001] The present invention relates to an evaporator and a cooling element comprising the evaporator. The present invention further relates to a method for producing the evaporator and a method for producing the cooling element comprising the evaporator.BACKGROUND

[0002] The cooling of electric components and power electronic components, such as microprocessors, LEDs, IGBT modules, silicon carbide (SiC) based components, Metal Core PCBs (MCPCB), power modules, etc., is conventionally based on attaching a cooling element to physical and thermally conducting connection to the component. A typical such cooling element comprises a base and a heat-transfer device, such as a heat pipe, connected to thereto and to transfer heat between two solid interfaces.

[0003] The heat pipes are typically joined to the base by mechanical press fitting, gluing, soldering, brazing or welding or a thread connection. Joining by soldering or welding is difficult, because it requires controlling of a temperature and a flow of a connecting alloy to avoid damaging the heat pipes and providing a permanent tight bond between the joined parts. The thread connection requires complex machining of the heat pipes and the base. This may result in a poor joint between the joined parts that hinders the operation of the cooling element.

[0004] When the evaporator is connected to the cooling element, additional interfaces can be formed in the structure, which interfaces impede heat transfer. In some applications, an evaporator may be integrated into the base. However, in this case, the evaporator may have a complex structure to produce and limited volume. Furthermore, the operation of the evaporator may be hindered by the possibility of the evaporator being laterally inclined.

[0005] Therefore, there remains a need to further develop the evaporators and the cooling elements without excessively increasing the complexity or at least to provide the public with a useful alternative.SUMMARY

[0006] According to a first aspect of the present disclosure, there is provided an evaporator comprising:- a base extending in a first dimension and in a second dimension, which is orthogonal in respect to the first dimension, and- one or more than one evaporation chamber(s) formed into the base, which evaporation chamber(s) are formed, at least in part, by two or more than two elongated holes extending in the first dimension, wherein the elongated holes overlap with each other in the first dimension and have central axes in the second dimension offset from each other.

[0007] Significant benefits are gained with aid of the present evaporator. The evaporator provides one or more than one large evaporator chamber(s) formed, at least in part, by two or more than two elongated holes, which collect heat from a large area. The evaporator has a large volume, because almost the entire volume of the base can be utilized to provide the evaporation chamber(s)having room for both vapor and liquid. In addition, the evaporator provides a large surface area for receiving heat from (an) electronic or optical component(s) attached to a mounting surface of the base of the evaporator. Thus, the most of the volume of the evaporator can act as an active evaporator. In addition, the evaporator chamber(s) is / are simple to produce for example, by a reductive manufacturing technique, such as machining, e.g. drilling, milling, boring and / or tooling. The evaporator chamber(s) has / have no additional thermal interfaces between the base and the evaporation chamber(s), because the evaporation chamber(s) is / are formed into the base by the overlapping elongated holes. Due to this special structure, the evaporator is less sensitive for lateral tilt. The evaporator thus enables efficient heat transfer from an electronic or optical component to the evaporation chamber.

[0008] One or more embodiments may comprise one or more features from the following itemized list:- the base comprises a first side and an opposite second side- one or more than one of the elongated hole(s) extend(s) from the first side towards the second side- one or more than one of the elongated hole(s) extend(s) from the second side towards the first side- the elongated holes have round cross-sections on the first side- the elongated holes have round cross-sections on the second side- the elongated holes comprise mechanical plugs for sealing the elongated holes and forming a closed volume extending in the first dimension- the elongated holes overlap with each other in the second dimension- the central axes of the elongated holes in a third dimension offset- the third dimension is orthogonal in respect to the second dimension- the elongated holes are integrated into the base- the elongated holes are inseparable from the base- the elongated holes are formed into a material of the base- the elongated holes are blind holes- the elongated holes comprise one or more than one groove(s)- the base comprises a mounting surface in an X-Y-plane- a portion of the mounting surface covering the evaporation chambers is larger than a portion covering the material of the base- the evaporation chamber(s) comprise one or more than one aperture(s) for connecting of one or more than one profile(s) of a condenser in a fluid contact with the evaporation chamber

[0009] According to a second aspect of the present disclosure, there is provided a method for producing an evaporator, comprising:- providing a base extending in a first dimension and a second dimension, which is orthogonal in respect to the first dimension, and- providing one or more than one evaporation chamber(s) into the base, which evaporation chamber(s) are formed, at least in part, by two or more than two elongated holes extending in the first dimension, wherein the elongated holes overlap with each other in the first dimension and have central axes in the second dimension offset from each other.

[0010] According to a third aspect of the present disclosure, there is provided a cooling element, comprising:- the evaporator, and- a condenser comprising one or more than one profile(s) extending from the base, which profiles are in a fluid contact with the elongated holes.

[0011] According to a fourth aspect of the present disclosure, there is provided a method for producing a cooling element comprising:- providing the evaporator,- providing a condenser comprising one or more than one profile(s), and- connecting the profile(s) to the base for extending from the base.

[0012] According to a fifth aspect of the present disclosure, there is provided a heat transfer system comprising:- the cooling element, and- a heat source connected to the base.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIGURE 1 illustrates an evaporator comprising six evaporation chambers, each of which is formed by two elongated holes, in accordance with at least some embodiments;

[0014] FIGURE 2 illustrates the evaporator of FIGURE 1, which evaporator is tilted, in accordance with at least some embodiments;

[0015] FIGURE 3 illustrates an evaporator comprising four evaporation chambers, each of which is formed by three elongated holes, in accordance with at least some embodiments;

[0016] FIGURE 4 illustrates the evaporator of FIGURE 1 , wherein the elongated holes comprise grooves in accordance with at least some embodiments;

[0017] FIGURE 5 illustrates producing of the evaporator of FIGURE 1 in accordance with at least some embodiments;

[0018] FIGURE 6 illustrates producing of the evaporator of FIGURE 3 in accordance with at least some embodiments;

[0019] FIGURE 7 illustrates a cooling element comprising the evaporator of FIGURE 1 in accordance with at least some embodiments;

[0020] FIGURE 8 illustrates a cooling element comprising the evaporator of FIGURE 1 in accordance with at least some embodiments;

[0021] FIGURE 9 illustrates a cooling element comprising the evaporator of FIGURE 3 in accordance with at least some embodiments; and

[0022] FIGURE 10 illustrates the cooling element of FIGURE9, wherein a large surface area for receiving heat is illustrated in accordance with at least some embodiments.EMBODIMENTS

[0023] In the present context “evaporator” refers to a device used to turn a liquid into a vapour. The evaporator can be a surface evaporator.

[0024] In the present context, “integrated” refers to an element or feature that is an integral part of another element or feature such that said elements or features are inseparable. Further, the term refers to an element or feature that is formed into and from a material of a body.

[0025] In the present context, “cooling element” refers to a device for cooling of electric or optical components. The cooling element enables transferring heat from the electric or optical component to the ambient air.

[0026] In the present context, “profile” refers to a heat-transfer device that employs phase transition to transfer heat between two solid interfaces. A profile can be a thermosiphon, which is a heat pipe where a liquid is returned to the evaporator by gravitational or other accelerational forces. The profile can form a condenser section of a thermosiphon. The profile can be a pipe, which is closed at one end.

[0027] In the present context, “groove” refers to a groove or a pattern, which can be formed on an inner surface of the elongated hole. By “inner surface”, it is meant a surface of the elongated hole, which is configured to be at least partially in contact with heat transfer phase change fluid. The groove can be for example, a helical groove, a thread, a microstructure, a grooved pattern, a grooved mesh or a knurled pattern. The groove can be provided by a threading tool.

[0028] A cooling element can comprise an evaporator attached or integrated into a base of the cooling element. The evaporator can comprise one or more than one vapor chamber(s), which collect(s) heat from an electrical or optical component. When the evaporator is attached to the base, additional thermal interfaces impeding heat transfer canbe formed in the structure and thus the cooling effect may be hindered. Some of the present embodiments provide solutions to at least some of the above-mentioned problems.

[0029] According to an embodiment, there is provided an evaporator 100 comprising:- a base 110 extending in a first dimension X and in a second dimension Y, which is orthogonal in respect to the first dimension X, and- one or more than one evaporation chamber(s) 130 formed into the base 110, which evaporation chamber(s) 130 are formed, at least in part, by two or more than two elongated holes 121, 122, 123 extending in the first dimension X, wherein the elongated holes 121, 122, 123 overlap with each other in the first dimension X and have central axes in the second dimension Y offset from each other.

[0030] The evaporator provides one or more than one large evaporator chamber(s) formed, at least in part, by two or more than two overlapping elongated holes, such that the overlapping holes are in the fluid connection with each other. Thus, the evaporator has a large volume, because almost the entire volume of the base can be utilized to provide the evaporation chambers, which have room for both vapor and liquid. Due to this special structure, the evaporator is less sensitive for lateral tilt. By “lateral tilt”, it is meant tilt in an X-Y-plane.

[0031] Furthermore, the evaporator provides a large surface area for receiving heat from (an) electronic or optical component(s) attached to a mounting surface 113 of the base 110 of the evaporator 100. Thus, the evaporator chambers 130 can collect heat from a large area. This is illustrated in FIGURE 10, wherein Al denotes a first area of the mounting surface 113, A2 denotes a second area of the mounting surface 113 and A3 denotes a third area of the mounting surface 113. The first areas Al, the second areas A2 and the third areas A3 can alternate along the second dimension Y. The first area Al may cover a volume of the evaporation chamber 130, which is configured to enclose the heat transfer phase change fluid 230 in a liquid form and wherein the heat transfer phase change fluid 230 can boil. The second area A2 may cover a volume of the evaporation chamber 130, which is configured to enclose the heat transfer phase change fluid 230 in a vapor form. In addition, the heat transfer phase change fluid 230 can “splash” to the surfaces of the evaporation chamber 130 in the volume covered by the second area A2. Depending on the level of the heat transfer phase change fluid 230 in the evaporation chamber 130, the second area A2 can be smaller or larger than the first area Al . A portion of the evaporator 100 covered by the third area A3is not configured to act as the evaporator, but the portion encloses material of the base 110. The third area A3 can be a solid portion area between any adjacent evaporation chambers 130. The electrical or optical component(s) can be attached to the mounting surface 113 to cover it at least partially. The electrical or optical component(s) may cover the first area Al and optionally also the second area A2 and / or the third area A3. Preferably, the total area covered by the first area Al and the second area A2 is larger than the third area A3. Thus, most of the volume of the evaporator can act as an active evaporator. The evaporator thus enables efficient transfer of the heat from an electronic or optical component to the evaporation chamber. It should be noted, that sizes and places of the areas Al, A2, A3 may vary according to the application.

[0032] In addition, the evaporator chamber(s) is / are simple to produce for example, by a reductive manufacturing technique, such as machining, e.g. drilling, milling, boring and / or tooling. The evaporator chamber(s) has / have no additional thermal interfaces between the base and the evaporation chamber(s), because the evaporation chamber(s) is / are formed into the material of the base by the elongated holes.

[0033] As described above and illustrated in FIGURE 10, the base 110 can further comprise a mounting surface 113 in an X-Y-plane. The mounting surface 113 can be configured to receive one or more than one electrical or optical component(s). A portion of the mounting surface 113 covering the evaporation chambers 130 is larger than a portion covering the material of the base 110. Therefore, the evaporator provides a large surface area for receiving heat from the electronic or optical component(s) attached to the mounting surface 113 and thus the evaporator chamber(s) 130 can collect heat from a large area.

[0034] Preferably, the evaporator 100 comprises more than one evaporation chambers 130. For example, a number of the evaporation chambers can be four or six, as illustrated in FIGURES 1-6. However, the number of the evaporation chambers can be selected according to the application of the evaporator and / or a volume of the base. The number of the evaporator chambers can be an even or odd number.

[0035] The elongated holes 121, 122, 123 can have a length in the first dimension X and a width in the second dimension Y. The length can be greater than the width. The elongated holes 121, 122, 123 can have either the same length or different lengths. Respectively, the elongated holes 121, 122, 123 can have either the same width or differentwidth. By “width”, it is meant a width of a portion of the evaporation chamber in the second dimension Y, which portion is formed by the respective elongated hole.

[0036] The elongated holes 121, 122, 123 can extend in parallel in the first dimension X. Thus, they are easy to provide by a reductive manufacturing, such as machining, e.g. drilling, milling, boring and / or tooling.

[0037] The elongated holes 121, 122, 123 overlap with each other in the first dimension X. Thus, the elongated holes 121, 122, 123 can cut each other at least partially in the first dimension X. For example, two adjacent elongated holes, namely a first elongated hole 121 and a second elongated hole 122, and respectively the second elongated hole 122 and a third elongated hole 123, may overlap with each other, as illustrated e.g. FIGURE 3.

[0038] The evaporation chamber 130 can be thus formed by a set of the elongated holes 121, 122, 123, which are connected with each other. The set of the elongated holes121, 122, 123 thus form together a cavity forming the evaporation chamber 130 of the evaporator 100. The base 110 can comprise a plurality of sets of the elongated holes 121,122, 123, which each of the sets form separate evaporation chambers 130. The separate evaporation chambers 130 may not be in a fluid contact which each other.

[0039] The elongated holes 121, 122, 123 can overlap with each other in the second dimension Y. Thus, the elongated holes 121, 122, 123 can cut each other in the second dimension Y, but do not fully overlap with each other.

[0040] The evaporation chamber(s) 130 can further comprise one or more than one aperture(s) 140 for connecting of one or more than one profile(s) 210 of a condenser in a fluid contact with the evaporation chamber 130. This enables vapor to flow into the profile(s) 210 and thus dissipating heat away from the electric component to the ambient.

[0041] The aperture 140 can be a hole formed into the evaporation chamber 130 via which the profile 210 can be connected into the fluid contact with the evaporation chamber. Preferably, a number of the apertures 140 is the same as the number of the profiles 210 and one profile 210 is connected to each of the apertures 140.

[0042] The base 110 can be rectangular and comprise four sides. However, the base can have any other suitable form. For example, the base can be round.

[0043] The base 110 can comprise a first side 111 and an opposite second side 112, and wherein:- one or more than one of the elongated hole(s) 121 extend(s) from the first side 111 towards the second side 112, and- one or more than one of the elongated hole(s) 122, 123 extend(s) from the second side 112 towards the first side 111.So, the elongated holes can be provided to extend through a surface of the first side 111 inside the base 110 and through a surface of the second side 112 inside the base 110.

[0044] The elongated holes 121, 122, 123 can have round cross-sections on the first side 111 and / or the second side 112. Thus, the round cross-sections can be in a Y-Z-plane on a surface of the base 110.

[0045] The elongated holes 121, 122, 123 comprise mechanical plugs 150 for sealing the elongated holes 121, 122, 123 and forming a closed volume or cavity extending in the first dimension X. The mechanical plugs can be inserted to first ends of the elongated holes 121, 122, 123 on the first side 121 or the second side 122 of the base 110. Cross-sections of the elongated holes 121, 122, 123 on the first side 121 or the second side 122 can be round and thus cross-sections of the mechanical plugs 150 can be also round. This makes closing the elongated holes much easier than with other shapes. In addition, only compressive forces parallel to radiuses of the mechanical plugs are directed to the mechanical plugs. The mechanical plugs prevent the elongated holes 121, 122, 123 from leaking. The mechanical plugs 150 thus protect the evaporator 100 from damaging and enable efficient function of the evaporator.

[0046] The mechanical plugs 150 can be produced from metal, for example, from steel, stainless steel, aluminum, aluminum alloy, copper or copper alloy, such as brass. The mechanical plugs 150 produced from steel can comprise a coating, such as a zinc coating.

[0047] The mechanical plugs 150 may have a cross-section of substantially same shape than the elongated holes 121, 122, 123, such as round.

[0048] The mechanical plugs 150 can be selected for example, from a group consisting of plugs, round cup-shapes plugs, screw plugs or any combination thereof.

[0049] Inserting mechanical plugs 150 into the elongated holes 121, 122, 123 may cause plastic deformation to the mechanical plugs 150 and / or the elongated holes 121, 122,123 to ensure fluid tight fit. The mechanical plugs 150 may comprise a seal between the mechanical plug 150 and the elongated hole 121, 122, 123, i.e. the material of the base 110.

[0050] Alternative, the elongated holes 121, 122, 123 may be sealed by a brazed or welded closure.

[0051] FIGURE 1 illustrates an evaporator 100 comprising six evaporation chambers 130, each of which formed by two elongated holes 121, 122. The base 110 comprises a first side 111 and on opposite second side 112. A first elongated hole 121 extends from the first side 111 towards the second side 112 and a second elongated hole 122 extends from the second side 112 towards the first side 111. The elongated holes 121, 122 overlap with each other in the first dimension X and have central axes offset from each other in the second dimension Y. Each of the evaporation chambers 130 also comprise a plurality of apertures 140 for connecting of profiles of condenser in a fluid contact with the evaporation chamber 130. The elongated holes 121, 122 comprise mechanical plugs 150 for sealing the elongated holes 121, 122 and forming a closed volume extending in the first dimension X. The evaporation chambers 130 enclose heat transfer phase change fluid 230 in a liquid and a vapor form. The apertures are substantially above a level of the liquid in the second dimension Y. Thus, the apertures 140 are formed to a portion of the evaporation chamber 130, which portion encloses mainly the vapor.

[0052] FIGURE 2 illustrates the evaporator 100 of FIGURE 1, which evaporator 100 is tilted. The evaporator 100 can be tilted in a X-Y-plane without markedly effecting to the function of the evaporator due to the special structure of the evaporation chambers 130, which are formed by the overlapping elongated holes 121, 122, 123.

[0053] FIGURE 3 illustrates an evaporator 100 comprising four evaporation chambers 130, each of which is formed by three elongated holes 121, 122, 123. The base l lO comprises a first side 111 and on opposite second side 112. A first elongated hole 121 extends from the first side 111 towards the second side 112, and a second elongated hole 122 and a third elongated hole 123 extends from the second side 112 towards the first side 111. The first elongated hole 121 extends between the second elongated hole 122 and the third elongated hole 123. The elongated holes 121, 122, 123 overlap with each other in the first dimension X and have central axes offset from each other in the second dimension Y. Each of the evaporation chambers 130 also comprises a plurality of apertures 140 for connecting the profiles of a condenser into a fluid contact with the evaporation chamber 130. The elongatedholes 121, 122, 123 comprise mechanical plugs 150 for sealing the elongated holes 121, 122, 123 and forming a closed volume extending in the first dimension X. The evaporation chambers 130 enclose heat transfer phase change fluid 230 in a liquid and a vapor form. The apertures are mainly above a level of the liquid in the second dimension Y. Thus, the apertures 140 are formed into a portion of the evaporation chamber 130, which portion encloses mainly the vapor.

[0054] FIGURES 1, 2 and 3 illustrate that all the evaporation chambers 130 are formed by two or more than two overlapping elongated holes 121, 122, 123. However, only one of the evaporation chambers, such as the lowest evaporation chamber in the second dimension Y, can be formed by two or more than two overlapping elongated holes and the others can be formed by single elongated holes. Then, the evaporator can further comprise one or more than one connecting holes(s) (not illustrated) extending along the second dimension Y, which connecting hole(s) intersect with the evaporation chamber and the single elongated holes connecting them together. Then, vapor can flow from the evaporation chamber to the single elongated holes, condense into fluid in the single elongated holes and return back to the evaporation chamber. This enables sharing heat between the intersecting holes. More information about the connecting holes is provided in Finnish Patent Application No. 20235317, which is incorporated herein by reference.

[0055] The central axes of the elongated holes 121, 122, 123 in a third dimension Z can offset, which third dimension Z is orthogonal in respect to the second dimension Y (not illustrated). Thus, central points of the elongated holes 121, 122, 123 can be scattered, i.e. they are not in the same line in the second dimension Y, when viewed from the first side 111 or the second side 112 of the base 110. This enables formation of evaporation chambers 130 having different shapes and sizes.

[0056] The elongated holes 121, 122, 123 can be integrated into the base 110. This means that the elongated holes 121, 122, 123 cannot be separated from the base 110. The elongated holes 121, 122, 123 are formed as cavities in the material of the base 110.

[0057] The elongated holes 121, 122, 123 can be blind holes, as illustrated in FIGURES 1-6. Thus, the elongated holes may extend from the first side 121 or the second side 122 inside the base 110, but not through the base 110. The elongated holes 121, 122, 123 can have first ends on the outer surface of the base 110, i.e. on the first side 121 or the second side 122, and second ends inside the base 110. Thus, there is no need for closing theelongated holes 121, 122, 123 from both ends, but placing a mechanical plug 150 only at one end is enough.

[0058] Alternatively, the elongated holes 121, 122, 123 can extend through the base 110.

[0059] The elongated holes 121, 122, 123 can comprise one or more than one groove(s). The groove(s) can be formed on internal surfaces of the elongated hole(s). By “inner surface”, is it meant a surface of the elongated hole, which is configured to be at least partially in contact with the heat transfer phase change fluid 230. The grooves(s) enable increasing a surface area of the elongated holes 121, 122, 123. This reduces the power density (W / cm2) on a boiling surface. The lower power density reduces the so-called superheating phenomenon. The superheating phenomenon means that a boiling surface must be warmer than a boiling point of liquid to initiate boiling. The superheating phenomenon is dependent on the power density on the surface, i.e. the higher the power density the greater the superheating phenomenon. The roughening of the internal surface of the elongated hole 121, 122, 123 also contributes to the emergence of the boiling phenomenon. The boiling needs some imperfections on the surface on which a vapor bubble can nucleate. This reduces a superheating temperature, which in turn improves boiling.

[0060] One or more than one of the elongated holes 121, 122, 123 can comprise one or more than one left-handed thread(s) and / or one or more than one right-handed thread(s). For example, each or some of the elongated holes 121, 122, 123 may comprise two threads. A first of the threads may be a left-hand thread and a second of the threads may be a righthand thread.

[0061] The elongated holes 121, 122, 123 may be formed by a reductive manufacturing technique, such as machining, e.g. drilling, milling, boring and / or tooling. After that, one or more than one groove can be formed into one or more than one of the elongated hole(s) 121, 122, 123 by threading process.

[0062] FIGURE 4 illustrates the evaporator 130 of FIGURE 1, wherein the elongated holes 121, 122 have grooves. The first elongated hole 121 has a first groove extending from the first side 111 towards the second side 112 and the second elongated hole 122 has a second groove extending from the second side 112 towards the first side 111.

[0063] According to an embodiment, there is provided a method for producing an evaporator 100, comprising:- providing a base 110 extending in a first dimension X and a second dimension Y, which is orthogonal in respect to the first dimension X, and- providing one or more than one evaporation chamber(s) 130 into the base 110, which evaporation chamber(s) 130 are formed, at least in part, by two or more than two elongated holes 121, 122, 123 extending in the first dimension X, wherein the elongated holes 121, 122, 123 overlap with each other in the first dimension X and have central axes in the second dimension Y offset from each other.

[0064] The method provides an evaporator having at least one large evaporation chamber, which enables collecting heat from a large area. This in further provides more efficient cooling of the electrical or optical component. The evaporation chamber(s) 130 is / are easy to produce for example, by a reductive manufacturing technique, such as machining, e.g. drilling, milling, boring and / or tooling, by providing the elongated holes 121, 122, 123 having central axes offset from each other in the second dimension Y.

[0065] The method can comprise:- providing a base 110, which comprises a first side 111 and on opposite second side H2,- providing one or more than one of the elongated holes 121 extending from the first side 111 towards the second side 112, and- providing one or more than one of the elongated holes 122, 123 extending from the second side 112 towards the first side 111.First, the elongated hole(s) 121 extending from the first side 111 towards the second side 112 can be provided, for example. After that, the elongated hole(s) 122, 123 extending from the second side 112 towards the first side 111 can be provided.

[0066] The method can further comprise providing mechanical plugs for sealing the elongated holes 121, 122, 123 and forming a closed volume in the first dimension X. The mechanical plugs can be formed separately and then connected to the elongated holes 121, 122, 123.

[0067] Alternatively, the elongated holes 121, 122, 123 may be sealed for forming a closed volume extending in the first dimension X for example, by brazing or welding.

[0068] The base 110 can be provided with an additive manufacturing technique and / or the evaporation chamber(s) 130 is / are provided with a reductive manufacturing technique. The elongated holes 121, 122, 123 forming the evaporation chamber(s) 130 can be provided by machining, e.g. drilling, milling, boring and / or tooling into the base 110.

[0069] FIGURE 5 illustrates producing of the evaporator 100 of FIGURE 1. The first elongated hole 121 is provided in the base 110 by forming a hole by a tool 301, such as a drill, which hole extends from the first 111 side to the second side 112 inside in the first dimension X. Then, the second elongated hole 122 is provided by forming the hole by a tool 302, such as a drill, which hole extends from the second side 112 to the first side 111 in the first dimension X.

[0070] FIGURE 6 illustrates producing of the evaporator of FIGURE 3. The first elongated hole 121 is provided in the base 110 by forming a hole by a tool 301, such as a drill, which hole extends from the first 111 side to the second side 112 in the first dimension X. Then, the second elongated hole 122 and the third elongated hole 123 are provided by forming holes by tools 302, 303, such as drills, which holes extends from the second side 112 to the first side 111 in the first dimension Z. The second elongated hole 122 and the third elongated hole 123 can be formed one after another by the same tool or simultaneously by the different tools.

[0071] According to an embodiment, there is provided a cooling element 200 comprising:- the evaporator 100 according to any one of the present embodiments, and- a condenser comprising one or more than one profile(s) 210 from the base 110, which profiles 210 are in a fluid contact with the elongated holes 121, 122, 123.

[0072] The profile(s) 210 can be (a) separate piece(s) from the base 110 and connected thereto. This enables producing the parts of the cooling element separately. So, the parts can be connected together to form a preferred entity.

[0073] The profile(s) 210 is / are preferably made from a thermally conducting material, such as aluminium or an aluminium alloy. (A) cross-section(s) of the profile(s) 110 can be circular or any suitable shape.

[0074] The profile(s) 210 can be used as a heat pipe. The profile(s) 210 can have an enclosed volume, in which a heat transfer phase change fluid 230 is arranged to act.

[0075] The elongated holes 121, 122, 123 can comprise heat transfer phase change fluid 230. The heat transfer phase change fluid is preferably a saturated vapour with little or no impurities.

[0076] A first portion of the evaporation chamber(s) 130 can enclose the heat transfer phase change fluid 230 in a fluid form and a second portion of the evaporation chamber(s) 130 can enclose the heat transfer phase change fluid 230 in a vapor form, wherein the profiles(s) 210 can be connected to the second portion.

[0077] The evaporator chamber(s) 130 can be configured to form (an) evaporator(s) and the profile(s) 210 can be configured to form (a) condenser(s), when the profile(s) are connected to the evaporator chamber(s) 130. This enables formation of a thermosiphon cycle, wherein liquid turns into vapor in the evaporator(s). The vapor that reaches the profile(s) 210 turns back into liquid and flows back to the evaporation chamber(s) 130.

[0078] The profile(s) 210 can extend in an inclined angle in respect to the base 110.

[0079] The inclined angle can be 5 to 45 degrees, preferably 10 to 15 degrees.

[0080] The cooling element 200 can further comprise a plurality of fins 220 connected to or formed onto the profile(s) 210. The profile(s) 210 can extend through the fins 220 or the fins 220 can be connected to the profile(s) 210 by soldering, gluing or brazing. Alternatively, the fins 220 and the profile 210 can form an integral and inseparable part. The fins provide a large heat dissipation area for dissipating heat away from the electric component to the ambient.

[0081] The fins 220 can be plate-like planar or curved elements. The fins 220 can be cut or stamped from sheet metal. Holes for the profiles 210 can be cut or stamped through as well. When the holes are properly sized, the fins press fit tightly on the profiles and the heat transfer is very good. Optionally, to optimize thermal transfer, the fins can be soldered, glued or connected by brazing to the profiles.

[0082] FIGURE 7 illustrates a cooling element 200 comprising the evaporator 100 of FIGURE 1. The cooling element 200 comprises a plurality of profiles 210, which are connected to the base 110. The first elongated hole 121 encloses mainly vapor, and the second elongated hole 122 is filled by the heat transfer phase change fluid 230 in the liquid form. The second elongated hole 122 expands the evaporation zone and may provide a betterescape for the vapor. The profiles 210 are connected to the first elongated holes 121 thus allowing the vapor to enter the profiles 210 for the thermosiphon cycle. When the vapor reaches the profiles 210, it turns back into liquid and flows back to the evaporation chamber 130. The cooling element 200 further comprises a plurality of fins 220. The profiles extend through the fins 220.

[0083] FIGURE 8 illustrates a cooling element 200 comprising the evaporator 100 of FIGURE 1. The base 110 is turned 90 degrees in the Y-Z-plane so that the base 110 is arranged horizontally. The first elongated hole 121 and the second elongated hole 122 are partially filled by the heat transfer phase change fluid 230 in the liquid form. Furthermore, the first elongated hole 121 and the second elongated hole 122 are partially free from the liquid, enclosing mainly vapor. A plurality of profiles 210 are connected to a portion of the evaporation chambers 130 enclosing mainly vapor. The cooling element 200 further comprises a plurality of fins 220. The profiles extend through the fins 220.

[0084] FIGURE 9 illustrates a cooling element 200 comprising the evaporator 100 of FIGURE 3. The cooling element 200 comprises a plurality of profiles 210, which are connected to the base 110. The second elongated hole 122 encloses mainly the heat transfer phase change fluid 230 in the vapor form, and the first elongated hole 121 and the third elongated hole are filled by the heat transfer phase change fluid 230 in the liquid form. The third elongated hole 123 expands the evaporation zone and may provide a better escape for the vapor. The profiles 210 are connected to the second elongated holes 122 thus allowing the vapor to enter the profiles 210 for the thermosiphon cycle. When the vapor reaches the profiles 210, it turns back into liquid and flows back to the evaporation chamber 130. The cooling element 200 can further comprise a plurality of fins 220. The profiles extend through the fins 220.

[0085] According to an embodiment, there is provided a method for producing a cooling element 200 comprising:- providing the evaporator 100 according to any one of the embodiments,- providing a condenser comprising one or more than one profile(s) 210, and- connecting the profile(s) 210 to the base 110 for extending from the base 110.

[0086] The method can further comprise:- providing a plurality of fins 220, and- connecting the plurality of the fins 220 to the profile(s) 210.

[0087] The fins 220 can be cut or stamped from sheet metal. Then, holes for the profiles can be cut or stamped through the sheet metal as well. Finally, the profiles 210 can be arranged through the holes. This provides a simple and low-cost way to produce and connect the fins to the profiles. When the holes are properly sized, the fins press fit tightly on the profiles and heat transfer is very good.

[0088] Optionally, the fins 220 can be soldered, welded or glued to the profiles. This enables optimizing thermal transfer.

[0089] According to an embodiment, there is provided a heat transfer system comprising the cooling element 200 according to any one of the preceding embodiments, and a heat source connected to the base 110. The heat source can be an optical or electric component.

[0090] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0091] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention.

[0092] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", i.e. a singular form, throughout this document does not exclude a plurality.REFERENCE SIGNS LIST100 evaporator110 base111 first side112 second side113 mounting surface121, 122, 123 elongated hole130 evaporator chamber140 aperture 150 mechanical plugs200 cooling element210 profile220 fin230 heat transfer phase change fluid 301, 302, 303 tool

Claims

CLAIMS:

1. An evaporator (100) comprising :- a base (110) extending in a first dimension (X) and in a second dimension (Y), which is orthogonal in respect to the first dimension (X), and- one or more than one evaporation chamber(s) (130) formed into the base (HO), which evaporation chamber(s) (130) are formed, at least in part, by two or more than two elongated holes (121, 122, 123) extending in the first dimension (X), wherein the elongated holes (121, 122, 123) overlap with each other in the first dimension (X) and have central axes in the second dimension (Y) offset from each other.

2. The evaporator (100) of claim 1, wherein the base (110) comprises a first side (111) and an opposite second side (112), and wherein:- one or more than one of the elongated hole(s) (121) extend(s) from the first side (111) towards the second side (112), and- one or more than one of the elongated hole(s) (122, 123) extend(s) from the second side (112) towards the first side (111).

3. The evaporator (100) of claim 2, wherein the elongated holes (121, 122, 123) have round cross-sections on the first side (111) and / or the second side (112).

4. The evaporator (100) of claim 3, wherein the elongated holes (121, 122, 123) comprise mechanical plugs (150) for sealing the elongated holes (121, 122, 123) and forming a closed volume extending in the first dimension (X).

5. The evaporator (100) of any one of the preceding claims, wherein the elongated holes (121, 122, 123) overlap with each other in the second dimension (Y).

6. The evaporator (100) of any one of the preceding claims, wherein the central axes of the elongated holes (121, 122, 123) in a third dimension (Z) offset, which third dimension (Z) is orthogonal in respect to the second dimension (Y).

7. The evaporator (100) of any one of the preceding claims, wherein the elongated holes (121, 122, 123) are integrated into the base (110).

8. The evaporator (100) of any one of the preceding claims, wherein the elongated holes (121, 122, 123) are blind holes.

9. The evaporator (100) of any one of the preceding claims, wherein the elongated holes (121, 122, 123) comprise one or more than one groove(s).

10. The evaporator (100) of any one of the preceding claims, wherein the base (100) comprises a mounting surface (113) in a X-Y -plane, wherein a portion of the mounting surface (113) covering the evaporation chambers (130) is larger than a portion covering a material of the base (110).

11. A method for producing an evaporator (100), comprising:- providing a base (110) extending in a first dimension (X) and a second dimension (Y), which is orthogonal in respect to the first dimension (X), and- providing one or more than one evaporation chamber(s) (130) into the base (HO), which evaporation chamber(s) (130) are formed, at least in part, by two or more than two elongated holes (121, 122, 123) extending in the first dimension (X), wherein the elongated holes (121, 122, 123) overlap with each other in the first dimension (X) and have central axes in the second dimension (Y) offset from each other.

12. The method of claim 11, comprising:- providing a base (110), which comprises a first side (111) and on opposite second side (112),- providing one or more than one of the elongated holes (121) extending from the first side (111) towards the second side (112), and- providing one or more than one of the elongated holes (122, 123) extending from the second side (112) towards the first side (111).

13. The method of claim 12, wherein the elongated holes (121, 122, 123) have round crosssections on the first side (111) and / or the second side (112).

14. The method of any one of the preceding claims 11 to 13, further comprising providing mechanical plugs for sealing the elongated holes (121, 122, 123) and forming a closed volume extending in the first dimension (X).

15. The method of any one of the preceding claims 11 to 14, wherein the elongated holes (121, 122, 123) overlap with each other in the second dimension (Y).

16. The method of any one of the preceding claims 11 to 15, wherein the central axes of the elongated holes (121, 122, 123) in a third dimension (Z) offset, which third dimension is orthogonal in respect to the second dimension (Y).

17. The method of any one of the preceding claims 11 to 16, wherein the elongated holes (121, 122, 123) are blind holes.

18. The method of any one of the preceding claims 11 to 17, wherein the base (100) is provided with an additive manufacturing technique and / or the evaporation chamber(s) (130) is / are provided with a reductive manufacturing technique.

19. The method of any one of the preceding claims 11 to 18, wherein the elongated holes (121, 122, 123) are provided by machining, such as drilling, milling, boring and / or tooling.

20. The method of any one of the preceding claims 11 to 19, wherein the elongated holes (121, 122, 123) comprise one or more than one groove(s).

21. A cooling element (200), comprising:- the evaporator (100) of any one of the preceding claims 1 to 10, and- a condenser comprising one or more than one profile(s) (210) extending from the base (HO), which profiles (210) are in a fluid contact with the elongated holes (121, 122, 123).

22. The cooling element (200) of claim 21, wherein the elongated holes (121, 122, 123) comprise heat transfer phase change fluid (230).

23. The cooling element (200) of claim 22, wherein a first portion of the evaporation chamber(s) (130) enclose the heat transfer phase change fluid (230) in a liquid form and a second portion of the evaporation chamber(s) (130) can enclose the heat transfer phase change fluid (230) in a vapor form, wherein the profiles(s) (210) are connected to the second portion.

24. The cooling element (200) of any one of the preceding claims 21 to 23, wherein the profile(s) (210) extend(s) in an inclined angle in respect to the base (110).

25. The cooling element (200) of claim 24, wherein the inclined angle is 5 to 45 degrees, preferably 10 to 15 degrees.

26. The cooling element (200) of any one of the preceding claims 21 to 25, further comprising a plurality of fins (220) connected to the profile(s) (210).

27. A method for producing a cooling element (200) comprising:- providing the evaporator (100) of any one of the preceding claims 1 to 10,- providing a condenser comprising one or more than one profile(s) (210), and- connecting the profile(s) (210) to the base (110) for extending from the base (110).

28. The method of claim 27, further comprising:- providing a plurality of fins (220), and- connecting the plurality of the fins (220) to the profile(s) (210).

29. A heat transfer system comprising:- the cooling element (200) of any one of the preceding claims 21 to 26, and- a heat source connected to the base (110).

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