Liquid flow channel for improved heat transfer efficiency

Abstract

The facility includes the following: a) a distributor (402) comprising the following: a first surface (452) having a flow outlet opening (410) and a flow inlet opening (411); a first projection (415) that emerges from the first surface (452) between the flow outlet opening (410) and the flow inlet opening (411); b) a thermally conductive grooved structure (407) comprising the following: a second surface (451) opposite the first surface (452) and having a depression to form a flow channel above the first projection (415), wherein the flow outlet opening (410) and the The flow inlet opening (411) is located opposite the recess; characterized in that a width of the projection (415) within the depression narrows towards the first surface (452) along a side surface of the projection (470), which runs in a direction from the flow outlet opening (410) to the flow inlet opening (411), so that the flow channel has a widened opening in the area of ​​the first surface (452) and a narrowed opening (418) between an upper end of the projection (415) and the opposite second surface (451).

Description

Field of invention

[0001] The field of the invention relates generally to temperature control systems and in particular to a liquid flow channel for improved heat transfer efficiency. General state of the art

[0002] US 2004 / 0182560A1 describes a device and a method for manufacturing a device for circulating a cooling material in a heat exchanger.

[0003] From US 4 794 977 A a liquid-cooled melt die casting device is known which is suitable for melt die casting of molten metals or other materials.

[0004] US Patent 4 712 609 A describes a liquid-cooled semiconductor heat sink structure with high heat flux suitable for mounting semiconductor chips such as ICs, hybrids, lasers and power semiconductors.

[0005] Fig. Figure 1 shows a fluid-based temperature control arrangement according to the state of the art. As in Fig. As observed in Figure 1, the arrangement includes a heat-generating element 101 (e.g., an operating semiconductor device) that generates heat. The heat-generating element 101 is thermomechanically connected to a grooved structure 107 in which channels 103 are formed. The grooved structure is thermally conductive to facilitate the transfer of heat from the heat-generating element to the channels 103. A pump 104 pumps fluid 105 through a distributor 102 and into channels 103. The pumped fluid 105 absorbs heat generated by the element 101 as it passes through the channels 103 and then flows back into the distributor 102.

[0006] The heated liquid is then pumped from distributor 102 to a heat exchanger 106, which extracts the heat from the liquid 105. The cooled liquid is then pumped back into distributor 102 to dissipate further heat from the heat-generating element.

[0007] Fig. Figure 2 shows a more detailed view of the channels 103, which are connected by the grooved structure 107 and the distributor 102 of the Fig. 1 are formed. As in Fig. 2 observed, several liquid flows enter a single channel through distributor outlet openings 210 and are drawn out of the channel through distributor inlet openings 211. Summary of the invention

[0008] The problem underlying the invention is solved by the subject matter of the independent claims. Further advantageous embodiments are specified in the dependent claims. Brief description of the drawings

[0009] The present invention is illustrated in the figures of the accompanying drawings, in which similar reference numerals refer to similar elements and in which: Fig. 1 shows a cooling system; Fig. 2 shows a flow channel in accordance with the state of the art; Fig. 3 Performance weaknesses associated with the flow channel according to the state of the art in the Fig. 2 concerns; Fig. 4a shows a first perspective of an improved flow channel; Fig. Figure 4b shows a second perspective of an improved flow channel. Detailed description

[0010] It is appropriate to acknowledge that the cooling / heat transfer efficiency of the entire arrangement is improved by a higher surface velocity of the fluid as it passes over a larger surface area of ​​the grooved structure. The faster the fluid volume can pass over a larger surface area of ​​the heated grooved structure, the more efficient the system. A fluid moving at a higher velocity can dissipate more heat per unit of time than a fluid moving more slowly over the same surface area. Furthermore, fluid coverage over a larger surface area of ​​the grooved structure equates to greater overall heat dissipation from the structure. Moreover, utilizing higher heat transfer with less fluid allows for the use of smaller and / or less expensive pumps.

[0011] Fig. Section 3 outlines some performance weaknesses that, with regard to the channel structure, are in accordance with the state of the art. Fig. 2 were identified.

[0012] First, the structure has right-angled corners 320 above the outlet openings 310 of the distributor 302, where the fluid first reaches the grooved structure 307. The right-angled corners 320 cause the fluid to be abruptly converted from a vertical to a horizontal flow. This abrupt conversion creates eddies 321 or other circular / stationary flows, which deviate from the principle of keeping the fluid in rapid motion and in contact above the surface of the grooved structure 307. Thus, components 321 of the fluid flow do not contribute to the heat dissipation process and instead increase the overall flow resistance of the channel. Both factors reduce system efficiency.

[0013] Secondly, the differently heated liquid flows 331, 332 "collide" above the inlet opening 311 of the distributor 302 before being drawn back into the distributor 302. This generates further turbulent / stagnant liquid flows 333, in which the liquid does not move rapidly across the surface of the grooved structure 307. This also reduces the system efficiency.

[0014] Thirdly, the entire plane of the upper surface 340 of the distributor 302 is flat at the point where it connects with the grooved structure 307. This consequently makes it difficult to create a channel with low flow resistance, which would also cause the fluid to flow over a large surface area of ​​the grooved structure 307. Alternatively, if the height 341 of the channel is increased to reduce the flow resistance of the channel (by increasing the cross-sectional area through which the fluid flows), the fastest components of the fluid will flow through the center of the channel, as shown, without contacting the surface of the grooved structure 307.

[0015] Conversely, if the height 341 of the channel is reduced to force the main flow of the liquid closer to the surface of the grooved structure 307, the flow resistance of the channel increases (since the cross-sectional surface area through which the liquid flows has been reduced). Therefore, at an identical liquid velocity, the earlier approach has reduced efficiency because an insufficient amount of the rapidly flowing liquid is in contact with the surface of the grooved structure 307, while the later approach has lower efficiency because it requires a more powerful pump. Thus, the simplified channel design in Fig. 3 - regardless of dimensions - inevitably exhibit performance weaknesses.

[0016] Fig. 4a and Fig. Figure 4b shows an embodiment of an optimized channel design which incorporates numerous improvements over the prior art in Fig. Contains 2.

[0017] As in Fig. As observed in Figure 4a, the following applies to the optimized channel design: 1) Right-angled corners are eliminated where the fluid flow is transformed from a vertical flow coming through the distributor outlet openings 410 to a horizontal flow flowing over the surface of the grooved structure 407. 2) A projection 416 is included, extending from the grooved structure 407, to prevent colliding flows near the distributor inlet opening 411. 3) Projections 415 are included, extending from the surface of the distributor 402, to provide improved fluidic surface area coverage while keeping the overall flow resistance of the channel low.

[0018] Regarding the removal of the right-angled corners, it should be noted that smoother channel inlet areas 450 are installed in the junction between the grooved structure 407 and the distributor 402 above the distributor outlet openings 410. The surfaces 451, 452 of the smooth channel inlet areas 450 are oriented at angles that are not parallel to the x- and y-axes in order to avoid a sharp change in the fluid flow from a vertical (+y) direction to a horizontal direction (along the x-axis). By avoiding a sharp change in the fluid flow from a vertical to a horizontal direction, the fluid tends not to form eddies or other stagnant currents as it is fed from the distributor 402 into the channel.

[0019] Instead, the momentum of the upward vertical flow emerging from the distributor outlet openings 410 forces the fluid to flow along the surface 451 of the grooved structure 407, which forms part of the inlet region 450. By delivering the fluid into the inlet region 450 at a certain velocity due to the pump's action, and by allowing it to flow close to the surface 451 of the grooved structure 407 without eddies or other stagnation, the fluid flow exhibits the characteristics of a more efficient system (a rapidly moving fluid along a large surface area of ​​the grooved structure 407 with limited flow resistance).

[0020] Simultaneously, the use of the projection 416, formed in the grooved structure 407, in the connection between the grooved structure 407 and the distributor 402 above the distributor inlet opening 411, creates a smooth liquid outlet area 460 to prevent the collision of flows leaving the channel and entering the distributor. Each independent flow can be visualized as having its own associated outlet channel, with channels whose flows enter the same distributor inlet opening 411 merging precisely above the distributor opening 411.

[0021] Similar to the shape of the inlet areas 450, each associated outlet channel for a specific flow has surfaces oriented at angles that are not parallel to the x- and y-axes to avoid a sharp transition from a vertical to a horizontal flow. Likewise, the momentum for the transition from horizontal to vertical forces the fluid to flow along the surface of the grooved structure 407 rather than the surface of the distributor 402. This again avoids eddies and other inefficient disturbances. Instead, the fluid is forced to flow over larger surface areas of the grooved structure 407, thereby increasing the efficiency of the system.

[0022] In summary, when comparing the channel structure according to the state of the art, one can see Fig. 2 with the optimized channel structure in Fig. 4a observe that the prior art approach features a simplified connection between the grooved structure 207 and the distributor 202. The distributor 202 essentially has a flat surface, and the grooved structure 207 has only one depression that covers the flow inlet and outlet openings of the distributor 210, 211 for the flows flowing into the depression.

[0023] In contrast, the connection between the grooved structure 407 and the distributor 402 of the optimized approach in Fig. 4a is more complex and contains several projections 415, 416 and corresponding recesses into which the projections "fit". These projections 415, 416 and opposing recesses, as previously described, effect a more efficient fluid flow by being deliberately designed to force a rapid fluid flow over extended surface areas of the grooved structure 407. This significantly reduces eddies and other stagnant movements that impair the efficiency of the fluid flow through the channel compared to the prior art.

[0024] Additional improvements will be included in Fig. 4b is evident. Fig. 4b shows a cross-section of the channel structure of the Fig. 4a, where the viewpoint is from level 417 of the Fig. 4a is directed in the +x direction. In addition to the improvements described above regarding Fig. 4a, it is pointed out that the liquid in the channel is designed to surround the projection 415 emerging from the distributor 402 in such a way that more liquid can be distributed along the surface of the grooved structure 407.

[0025] In one embodiment, with renewed reference to Fig. 4a, the liquid fed into the channel is directed upwards through a constricted opening 418 between the upper end of the projection 415 and the lower end of the grooved structure 407. However, the constricted opening 418 corresponds to a higher resistance of the liquid channel.

[0026] The width of the projection 415, as measured along the z-axis, is thus tapered 470 such that the width of the projection is continuously narrowed in the movement towards the distributor 402. The reduced width 470 of the projection effectively creates wider openings along the sides of the projection 415 closer to the distributor 402, which in turn corresponds to the reduced flow resistance in the recesses along the side of the projection 415 compared to the upper end of the projection 415.

[0027] Due to the reduced flow resistance along the sides of the projection 415 and the force with which the fluid flows vertically through the distributor outlet opening, the fluid receives momentum to flow along the outer walls of the side channels (along the surface of the distributor 407) while flowing down the channel (instead of along the top of the projection 415). The fluid flow along the outer walls of the side channels corresponds to a greater surface area coverage of the grooved structure 407 by the fluid flow, thereby increasing the amount of heat dissipated. Thus, a more efficient overall solution is achieved.

[0028] Apart from the fluid flow being distributed over larger surface areas of the grooved structure 407 along the channels with lower flow resistance, it should be emphasized again that the system can utilize lower fluid flow rates, further increasing the system's efficiency. In particular, it should be noted that the structures 415, 416, 450, 460, and 470 used to form the channel are designed with a focus on forcing the fluid to flow along the various surfaces of the grooved structure 407. Ideally, no additional fluid volume is required in the channel beyond that necessary for efficient heat transfer. Furthermore, heat transfer from a surface (such as...)Surface 407) is more efficient at moving fluid when the so-called "boundary layer" (where the flow develops from zero velocity (at the surface wall) to a fully developed flow away from the surface) is thinner. Since (for a given flow rate) a narrower flow channel results in a thinner boundary layer, the absence of flow channel features necessitates higher overall fluid flow rates to achieve a thin boundary layer. Higher flow rates place additional stress on the pump, reducing system efficiency and requiring larger and more expensive piping (hose, pipe, fitting, valve, etc., with a larger diameter).

[0029] Fig. Figure 4b further shows a smooth, curved cross-section instead of rigid rectangular structures. The use of smooth curved structures helps to reduce drag (since rectangular structures or sudden changes in orientation can create eddies, etc.).

[0030] In summary, the use of structures designed to support fluid flow through low-resistance channels along the extended surface areas of the grooved structure 407 enables higher-velocity, lower-volume fluid flows, all of which, in combination—even with a less powerful pump—provide significant heat dissipation. It should be noted that lower-volume fluid flows can even contain fluid volumes that do not substantially fill the flow channels. The actual fluid volume can be 25% or less than the original volume of the flow channel.

[0031] It must be pointed out that the characteristics of Fig. 4a and Fig. 4b are examples. Alternative embodiments may exist that differ structurally from the representations in the Fig. 4a and Fig. exhibit 4b, and yet address the lessons of the present discussion.

[0032] To give just one example, the depicted fluid flows can be seen in Fig. 4a. This is reversed. This means that the liquid can enter the channel via the distributor opening 411 and exit the channel via the distributor openings 410. Except for the fact that the flow entering the channel would be "divided" by the projection 416, the same principles as described above still apply.

[0033] Furthermore, while Fig. 4a represents a pair of fluid flows that flow into the same distributor inlet opening 411; in other embodiments, only a single fluid flow flows into and out of a pair of the distributor's inlet and outlet openings. For example, the projection 416 can be extended downwards such that its sides form a further side wall structure, which in its embodiment resembles feature 450.

[0034] Furthermore, even if the surfaces of the grooved structure 407 and the distributor 402 in Fig. 4a sudden changes in angle become apparent; instead, such changes are made gradually, so that the surfaces are continuously smooth (similar to those in Fig. 4b visible structures). The specific angles that are in Fig. As can be seen in section 4a, these features may also vary from embodiment to embodiment. Furthermore, a single surface (e.g., surface 451 or 452 in) may be used. Fig. 4a show further changes in the angular alignment than in Fig. 4a shown).

[0035] As discussed previously, the grooved structure 407 should be thermally conductive so that heat can be transferred from the heat-generating element to the lower surface of the grooved structure 407 (or alternatively, the heat-generating element can be replaced by a "cold sink," where heated fluid is pumped into the channel to warm it). The grooved structure should be made of a material that, depending on the requirements, can be milled, turned, cast, or 3D printed to produce the described features for the channel 407 and projection 416. Examples include aluminum, copper, ceramics, etc., with appropriately compatible machining processes.

[0036] The distributor structure 402 does not have strict heat transfer requirements, and the material selection is not critical. In fact, any heat transfer to the fluid outside the grooved channel structure 407 should preferably be avoided, and a material with low thermal conductivity is appropriate for the distributor 402. Materials include plastics, polymers, ceramics, etc. In any case, when selecting the distributor material, the production of the projection 415 and the fluid path channels using processes such as drilling, milling, forming, etching, etc., should be taken into account.

[0037] Even if the grooved structure is thermally conductive, it may or may not be electrically conductive depending on the application (e.g., if the grooved structure is designed to be electrically conductive, it can be used as a ground plate). The distributor may or may not be thermally conductive or electrically conductive, depending on the application. Furthermore, even though the embodiments discussed above feature a configuration in which the surfaces of the projections are angular, other configurations are possible, allowing the fluid flow to enter the distributor perpendicular to the surface of the connection between the grooved structure and the distributor (e.g., where, however, the shape of the channel formed by the grooved structure changes gradually in such a way as to avoid abrupt changes in the direction of fluid flow).

[0038] The teachings presented here can be extended to many different application types. In one family of application types, the heat-generating element is a semiconductor chip or an enclosed semiconductor chip. In the first case, the cooling arrangement may be located within the chip package. In the second case, the cooling arrangement may be located outside the chip package (e.g., as part of the underlying PCB platform for the enclosed device). In other applications, the heat-generating element may be any device or unit that produces heat (e.g., a solar cell panel, a drive motor, an exothermic reaction, a light source, etc.).

Claims

[1] Facility comprising the following: a) a distributor (402) comprising the following: a first surface (452) having a flow outlet opening (410) and a flow inlet opening (411); a first projection (415) that emerges from the first surface (452) between the flow outlet opening (410) and the flow inlet opening (411); b) a thermally conductive grooved structure (407) comprising the following: a second surface (451) opposite the first surface (452) and having a depression to form a flow channel above the first projection (415), wherein the flow outlet opening (410) and the The flow inlet opening (411) is located opposite the depression; characterized by , that a width of the projection (415) within the depression narrows towards the first surface (452) along a side surface of the projection (470), which runs in a direction from the flow outlet opening (410) to the flow inlet opening (411), so that the flow channel has a widened opening in the area of ​​the first surface (452) and a narrowed opening (418) between an upper end of the projection (415) and the opposite second surface (451). [2] Device according to claim 1, wherein the grooved structure (407) comprises a second recess to form a second flow channel, wherein the second recess is formed above a flow opening in the first surface (452) of the distributor (402), wherein one of the flow outlet opening (410) and flow inlet opening (411) is provided for transporting liquid of the second flow channel. [3] Device according to claim 2, wherein the distributor (402) comprises a second projection (415), wherein the second projection is arranged in the second recess such that the fluid of the second flow channel flows over the second projection (415). [4] Device according to claim 3, wherein the grooved structure (407) includes a third projection (416) between the recesses, wherein the third projection (416) has side surfaces which each form parts of the first and second flow channel. [5] Device according to claim 4 wherein the second projection (415) has a narrowed width (470) towards the first surface (452) when viewed along a direction of the fluid flow. [6] Device according to claim 1, wherein the flow channels are connected to a pump (104). [7] Device according to claim 6, wherein the pump (104) is in operation and the flow channels are not filled with liquid. [8] Device according to claim 7, wherein the grooved structure (407) is electrically conductive. [9] Device according to claim 7, wherein the grooved structure (407) is not electrically conductive. [10] Device according to claim 7, wherein the distributor (402) is electrically conductive. [11] Device according to claim 7, wherein the distributor (402) is not electrically conductive.

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