A cooling arrangement for an electronic device

Abstract

A cooling arrangement (1) for an electronic device, such as an electronic device of a telecommunications network. The electronic device comprises at least one electronic component (2). The cooling arrangement (1) comprises: an evaporator heat exchanger (3) for removing heat from the electronic component (2), an expansion chamber (4) fluidly connected to an outlet (5) of the evaporator heat exchanger (3), a thermosiphon heat exchanger (6) fluidly connected to an upper outlet (7) of the expansion chamber (4), a liquid-to-air heat exchanger (8) fluidly connected to a lower outlet (9) of the expansion chamber (4), and at least one pump (10) fluidly connecting an inlet of the evaporator heat exchanger (3) to the liquid-to-air heat exchanger (8) and to the thermosiphon heat exchanger (6). The pump (10) may be an electrohydrodynamic pump to be used with a dielectric coolant fluid.

Description

[0001] TITLE: A COOLING ARRANGEMENT FOR AN ELECTRONIC DEVICE

[0002] TECHNICAL FIELD

[0003] The present invention relates to a cooling arrangement for an electronic device, such as an electronic device of a telecommunications network.

[0004] BACKGROUND OF THE INVENTION

[0005] Electronic devices for telecommunication networks may be mounted on top of buildings, on masts, or in rural areas. The electronic devices are thus difficult to access for maintenance and repair. Electronics in the electronic device generate heat during use and thus may need cooling to operate. Some electronic devices employ cooling systems with a thermosiphon cooling loop for moving heat from electronic components to a heat exchanger of the base station. Thermosiphon loops are difficult to design for varying heating conditions and varying surrounding temperatures. Also, thermosiphon loops must typically be properly oriented to enable proper operation. Under poor operating conditions thermosiphon loops may fail, for example due to dry out in the thermosiphon preventing circulation of coolant. It is challenging to design a small and robust cooling system for such electronic devices.

[0006] Accordingly, an object of the present disclosure is to provide an improved cooling arrangement suitable for use in an electronic device, such as in an electronic device of a telecommunications network.

[0007] SUMMARY OF THE INVENTION

[0008] According to a first aspect, these and other objects are achieved by a cooling arrangement according to claim 1. The cooling arrangement comprises at least one electronic component, and an evaporator heat exchanger for removing heat from the electronic component. The cooling arrangement further comprises an expansion chamber fluidly connected to an outlet of the evaporator heat exchanger, a thermosiphon heat exchanger fluidly connected to an upper outlet of the expansion chamber, a liquid-to-air heat exchanger fluidly connected to a lower outlet of the expansion chamber, and at least one pump fluidly connecting an inlet of the evaporator heat exchanger to the liquid-to-air heat exchanger and to the thermosiphon heat exchanger. According to a second aspect, these and other objects are also achieved by an electronic device according to claim 13. The electronic device comprises a cooling arrangement 1 as described above, and at least one electronic component 2 arranged adjacent the evaporator heat exchanger 3 such that heat conduction is enabled between at least one electronic component 2 and the evaporator heat exchanger 3.

[0009] BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The appended figures are all schematic illustrations, not drawn to measure. The force of gravity in a typical use situation is indicated in some of the figures with an arrow showing the direction of the force of gravity.

[0011] Figs. 1-6 show a first embodiment of a cooling arrangement according to the present disclosure, and figs. 7-11 show a second embodiment of a cooling arrangement according to the present disclosure.

[0012] Fig. 1 shows a perspective view of the cooling arrangement according to the first embodiment.

[0013] Fig. 2 shows a front view of the cooling arrangement.

[0014] Fig. 3 shows an exploded perspective view of the cooling arrangement.

[0015] Figs. 4 and 5 show enlarged views A and B indicated in fig. 3.

[0016] Fig. 6 shows a perspective view showing the back side of the cooling arrangement along with the six power amplifiers (electronic components) which the cooling arrangement primarily cools. The electronic device to which the electronic components belong is not shown.

[0017] Fig. 7 shows a perspective view of the cooling arrangement according to the second embodiment.

[0018] Fig. 8 shows a front view of the cooling arrangement.

[0019] Fig. 9 shows an exploded perspective view of the cooling arrangement.

[0020] Fig. 10 shows a perspective view showing the back side of the cooling arrangement along with the ASIC (electronic components) which the cooling arrangement primarily cools. The electronic device to which the electronic components belong is not shown.

[0021] Fig. 11 shows perspective view of a cut-away portion C of the second embodiment of the cooling arrangement, the extent of said cut-away portion being indicated with broken lines referred to with C in fig. 8. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0022] Embodiments of a cooling arrangement according to the present disclosure will hereinafter be described with reference to the appended drawings.

[0023] In all embodiments, the cooling arrangement comprises at least one electronic component, and an evaporator heat exchanger for removing heat from the electronic component. The cooling arrangement further comprises an expansion chamber fluidly connected to an outlet of the evaporator heat exchanger, a thermosiphon heat exchanger fluidly connected to an upper outlet of the expansion chamber, a liquid-to-air heat exchanger fluidly connected to a lower outlet of the expansion chamber, and at least one pump fluidly connecting an inlet of the evaporator heat exchanger to the liquid-to-air heat exchanger and to the thermosiphon heat exchanger.

[0024] Before use, a coolant fluid is introduced into the cooling arrangement. The pump moves the coolant fluid such that it circulates through the evaporator heat exchanger, where the coolant fluid removes heat from the at least one electronic component, and further into the expansion chamber. Some of the heated coolant fluid forms gas and the gas-liquid mixture separates in the expansion chamber into liquid at a bottom portion of the expansion chamber, and a gas or gas-liquid mixture in an upper portion of the expansion chamber. The pressure from the pump causes liquid from the bottom portion of the expansion chamber to flow from the lower outlet of the expansion chamber to the liquid- to-air heat exchanger and back to the pump. As the liquid coolant fluid passes through the liquid-to-air heat exchanger, heat is dissipated from the liquid-to-air heat exchanger, thereby cooling the liquid coolant fluid. The pressure from the pump also promotes fluid flow from the upper outlet of the expansion chamber through the thermosiphon heat exchanger by transporting fluid to the expansion chamber where flow towards the potential inherent of the condenser.is promoted by the force of gravity. As the heated gas / gas-liquid mixture moves through the thermosiphon heat exchanger, heat is dissipated from the thermosiphon heat exchanger, thereby cooling the gas / gas-liquid mixture, such that the gas returns to a liquid state. Gravity acts on the liquid state coolant fluid, thereby promoting return flow from the thermosiphon heat exchanger back to the pump. The thermosiphon effect in the thermosiphon heat exchanger thus uses some of the heat energy from the electronic components to promote circulation through the thermosiphon heat exchanger, and gravity then promotes the return flow to the pump, such that a lower-capacity pump can be used. The pump provides forced circulation, and thus mitigates problems associated with dry-out of the thermosiphon heat exchanger and makes it possible to vary the orientation of the cooling arrangement and / or the electronic device in which the cooling arrangement is used, without compromising cooling performance.

[0025] In both embodiments shown in the drawings, both the thermosiphon heat exchanger and the liquid-to-air heat exchanger are designed with dual coolant fluid flow loops. As shown by the arrows in fig. 2, two upper loops are provided for the thermosiphon heat exchanger - one to the left and one to the right. Also shown in fig. 2 are two lower loops for the liquid-to-air heat exchanger - one to the left and one to the right. Each loop comprises a plurality of conduits joined by an inlet and an outlet header. However, the invention relies on only at least one flow loop for each one of the thermosiphon heat exchanger and the liquid-to-air heat exchanger. Accordingly, a single flow loop, or more than two flow loops could alternatively be provided for each one of the thermosiphon heat exchanger and the liquid-to-air heat exchanger, and the number of loops may differ between the thermosiphon heat exchanger and the liquid-to-air heat exchanger. Also, the flow loops may use a mutual header for multiple flow loops. In the embodiments shown in the figures, two expansion chambers are provided. However, the invention relies on only at least one expansion chamber. Hence, a single expansion chamber, or more than two expansion chambers could alternatively be provided.

[0026] In the first embodiment, the electronic components cooled by the evaporator heat exchanger comprise six power amplifiers, and in the second embodiment, the evaporator heat exchanger is instead moved to an act to cool an ASIC provided at a distance from six power amplifiers, which are instead cooled by conduction of heat to ambient air without involvement of a coolant fluid.

[0027] As shown in figs. 1-6, the cooling device 1 according to the first embodiment is used for cooling of an electronic device comprising at least one electronic component 2. In the example illustrated in fig. 6, six electronic components in the form of power amplifiers are provided, but the cooling device could alternatively be adapted for use with any number of electronic components, and with any other suitable type of electronic component other than power amplifiers, such as an ASIC.

[0028] As shown in fig. 3, the cooling arrangement 1 comprises an evaporator heat exchanger 3 for removing heat from the electronic component 2. The cooling arrangement 1 further comprises an expansion chamber 4 fluidly connected to an outlet 5 of the evaporator heat exchanger 3. Also, the cooling arrangement 1 comprises a thermosiphon heat exchanger 6 fluidly connected to an upper outlet 7 of the expansion chamber 4. A liquid-to-air heat exchanger 8 is fluidly connected to a lower outlet 9 of the expansion chamber 4. At least one pump 10 fluidly connects an inlet of the evaporator heat exchanger 3 to the liquid-to- air heat exchanger 8 and to the thermosiphon heat exchanger 6.

[0029] The pump 10 moves the coolant fluid such that it circulates through the evaporator heat exchanger 3, where the coolant fluid removes heat from the at least one electronic component 2, and further into the expansion chamber 4. Some of the heated coolant fluid forms gas and the gas-liquid mixture separates in the expansion chamber into liquid at a bottom portion of the expansion chamber 4, and a gas or gas-liquid mixture in an upper portion of the expansion chamber 4. A very low amount of gas may also be carried on by the liquid and this small amount of gas is typically condensed in the liquid heat exchanger before again arriving at the pump. The expansion chamber may alternatively have any other suitable shape, allowing such separation into gas and liquid. An additional expansion chamber directly above the evaporator heat exchanger (not present in the embodiments shown in the figures) may be added to release some gas volume to the thermosiphon. However, the bulk of the gas is released in the expansion chamber. The pressure from the pump 10 causes liquid from the bottom portion of the expansion chamber to flow from the lower outlet 9 of the expansion chamber 4 to the liquid-to-air heat exchanger 8 and back to the pump 10. As the liquid coolant fluid passes through the liquid-to-air heat exchanger 8, heat is dissipated from the liquid-to-air heat exchanger 8 to ambient air, thereby cooling the liquid coolant fluid. The pressure from the pump 10 also promotes fluid flow from the upper outlet 7 of the expansion chamber 4 to the thermosiphon heat exchanger 6 and back to the pump 10. As the heated gas / gas-liquid mixture moves through the thermosiphon heat exchanger 6, heat is dissipated from the thermosiphon heat exchanger 6 to ambient air, thereby cooling the gas-liquid mixture, such that the gas returns to a liquid state. Gravity acts on the liquid state coolant fluid, thereby promoting return flow from the thermosiphon heat exchanger 6 to the pump 10. The thermosiphon effect in the thermosiphon heat exchanger 6 thus uses some of the heat energy from the electronic component(s) 2 to promote circulation through the thermosiphon heat exchanger 6, and gravity then drives the return flow to the pump 10, such that a lower-capacity pump 10 can be used. The pump 10 provides forced circulation, and thus mitigates problems associated with dry-out of the thermosiphon heat exchanger 6 and enables variation of the orientation of the cooling arrangement 1 and / or the electronic device in which the cooling arrangement 1 is used, with lower negative impact on cooling performance.

[0030] The pump 10 may be any suitable type of pump, but in the first and second embodiments discussed herein, the pump 10 is an electrohydrodynamic pump to be used together with a dielectric coolant fluid. Coolant fluid may be introduced into the cooling arrangement 1 during manufacturing of the cooling arrangement 1 , or the coolant fluid could be subsequently introduced by an end user who has acquired the cooling arrangement 1. For other types of pumps than electrohydrodynamic pumps, any other suitable type of coolant fluid may alternatively be used instead.

[0031] The electrohydrodynamic pump 10 is free from moving parts, yet able to pump a fluid, such as the dielectric coolant fluid. The electrohydrodynamic pump 10 works well both with pure liquid and with a mix of both liquid state and gas state coolant fluid. Accordingly, the combination of an electrohydrodynamic pump 10 and a dielectric liquid coolant works well with the combination of the thermosiphon heat exchanger 6 and the liquid-to-air heat exchanger, promotes increased reliability of the cooling arrangement, and reduces service need related to worn moving parts.

[0032] As shown in figs. 3, the thermosiphon heat exchanger 6 may comprise a first manifold 11 fluidly connected to the upper outlet 7 of the expansion chamber 4, a second manifold 12 fluidly connected to the pump 10, and a plurality of primary fins 13, each primary fin 13 being provided with a primary fluid conduit 14 fluidly connecting the first manifold 11 to the second manifold 12.

[0033] In other embodiments, any other design of fluid conduits suitable for routing coolant fluid in a thermosiphon coolant fluid flow loop may alternatively be used instead, and headers may thus be redesigned, or omitted as needed.

[0034] The manifolds 11, 12 enable easier fluid distribution to a larger number of primary fins, and the larger number of fins provide increased surface area for increased cooling capacity of the thermosiphon heat exchanger. Yet, a single manifold on each end of the fins reduces the amount piping required and thus reduces flow resistance for ambient air passing between the primary fins.

[0035] The primary fins 13 are oriented such that the primary fluid conduits 14, in use, are nonhorizontally arranged with an inlet of a primary fluid conduit 14 of each primary fin 13 elevated higher than an outlet of the respective primary fluid conduit 14. Such elevation of the primary fluid conduits enables gravity to act on liquid-state coolant fluid in the primary fluid conduits such that the force of gravity promotes fluid flow in the thermosiphon loop back to the inlet of the pump. Hence, heat energy provided by the electronic component cooled, brings some of the coolant fluid to gas phase, promoting increase of potential energy of the coolant fluid, bringing it to a higher level in the thermosiphon loop where the gas-state coolant fluid cools off and returns to liquid-state. In this way, heat energy from the electronic component cooled drives the fluid flow through the thermosiphon heat exchanger, thereby reducing energy needed to operate the cooling arrangement.

[0036] Herein, ‘in use’ refers to an orientation of the cooling arrangement when it is mounted in or on an electronic device to be cooled. In the first embodiments, the intended use position is the one shown in figs. 2 and 8, where the direction of gravity is indicated.

[0037] The primary fins 13 are oriented such that, in use, a major portion of each primary fluid conduit 14 extends vertically. In other embodiments, the primary fluid conduit may have any other suitable design, as long as a thermosiphon effect is enabled.

[0038] The liquid-to-air heat exchanger 8 comprises a plurality of secondary fluid conduits 15 fluidly connected to the expansion chamber and to the pump 10. A plurality of secondary fins 17 are attached to the secondary fluid conduits 15 such that heat conduction is enabled between the secondary fins 17 and the secondary fluid conduits 15.

[0039] The cooling arrangement further comprises a third manifold 16, fluidly connecting the expansion chamber 4 to at least some of the secondary fluid conduits 15. The cooling arrangement 1 further comprises a fourth manifold 19, fluidly connecting at least some the secondary fluid conduits 15 to the pump 10. Manifolds may be provided in any suitable form, such as by pipes / headers, or as conduits formed in plates or other members of the cooling arrangement.

[0040] In other embodiments, any other design of fluid conduits suitable for routing coolant fluid in a liquid-to-air heat exchanger coolant fluid flow loop may alternatively be used instead, and headers may thus be redesigned, or omitted as needed.

[0041] In the first embodiment, all fluid conduits are fluidly connected to the expansion chamber

[0042] 4 and to the pump 10 via the third manifold 16 and the fourth manifold 19. In other embodiments, such as in the second embodiment shown in figs. 7-11 , at least some of the secondary fluid conduits may be connected directly to the expansion chamber 4, and / or be connected directly to the pump 10.

[0043] Preferably, the design of the primary fins and the secondary fins, is such that ambient air flows through the thermosiphon heat exchanger and through the liquid-to-air heat exchanger by natural convection of ambient air promoted by the heat from the respective heat exchanger.

[0044] The secondary fins 17 comprise a plurality of peripheral edges and / or ridges 18, and wherein the secondary fluid conduits 15 are attached to the peripheral edges and / or ridges 18 of the secondary fins 17. Such positioning of the secondary fluid conduits 15 promotes improved flow of ambient air between the secondary fins 17, since the secondary fluid conduits 15 run along a periphery of the secondary fins 17, rather than for example centrally straight through the secondary fins 17. In the illustrated embodiments, the secondary fins are separate fins, but in other embodiments the secondary fins may alternatively be formed from a single piece of material shaped to form the fins. An example of such a piece of material is a plate deformed to have a wave-shaped cross- sectional profile wherein the material between the fins form said peripheral ridges. The waves may have any suitable shape such as smoothly curved or trapezoidal. As an alternative to deforming a plate, the fins could instead be formed by extrusion or any other suitable method.

[0045] Attaching the secondary fluid conduits to peripheral edges or ridges of the secondary fins keeps space between the secondary fins free from the secondary fluid conduits, thus reducing flow resistance for air passing between the fins. Reduced flow resistance increases cooling efficiency of the liquid-to-air heat exchanger by enabling improved natural convection air cooling through the secondary fins 17. This also reduces the flow resistance to the thermosiphon heat exchanger located upstream of the liquid-to-air exchanger.

[0046] In both the first and second embodiments, the secondary fluid conduits 15 extend perpendicular to the secondary fins 17. However, the orientation of the secondary fluid conduits 15 may in other embodiments be varied in any other suitable way.

[0047] The primary fins 13 preferably extend parallel to the secondary fins 17, as shown in figs. 2 and 8. Such orientation promoted natural convection of ambient air, but the relative orientation of the primary fins 13 with respect to the secondary fins 17 may in other embodiments alternatively be varied.

[0048] As shown in figs. 2 and 8, the thermosiphon heat exchanger 6 is, in use, positioned above the expansion chamber 3. Such positioning enables natural flow upwards of heated gaseous coolant fluid from the expansion chamber 3 into the thermosiphon heat exchanger, improving efficiency and reliability of the thermosiphon heat exchanger. In other embodiments, a certain vertical overlap between the thermosiphon heat exchanger 6 and the expansion chamber 3 may alternatively be used; For example, an upper portion of the thermosiphon heat exchanger may be provided above the expansion chamber, whilst a lower portion of the thermosiphon heat exchanger may be provided below the expansion chamber, meaning that the thermosiphon heat exchanger vertically overlaps with the entire vertical extent of the expansion chamber.

[0049] As shown in figs. 3 and 9, the cooling arrangement 1 may comprise a support plate 20 to which the components of the heat exchanger are attached. In the embodiment shown in figs. 9 and 19, recesses may be provided in the support plate to make room for fluid conduits for coolant fluid. The support plate may for example be made of aluminum. Also shown in fig. 10, is the optional provision of internal guide walls in the evaporator heat exchanger 6 for guiding the flow of coolant fluid. The evaporator heat exchanger 6 may be an extruded profile.

[0050] According to an aspect, an electronic device may be provided (not illustrated in the figures), said electronic device comprising the above-described cooling arrangement 1 , and at least one electronic component 2 arranged adjacent the evaporator heat exchanger 3 of the cooling arrangement 1 such that heat conduction is enabled between the at least one electronic component 2 and the evaporator heat exchanger 3. The electronic component 2 may be a power amplifier or an ASIC, or some other type of heat generating electronic component 2. The electronic device may be an electronic device of a tele communications network.

[0051] Any suitable material may be used for the various components of the cooling arrangement, for example materials, such as aluminum or copper having good heat conductive properties. Suitable materials are well known in the field of heat exchangers.

[0052]

[0053] Table of reference numerals

Claims

CLAIMS1. A cooling arrangement (1) for an electronic device comprising at least one electronic component (2), said cooling arrangement (1) comprising: an evaporator heat exchanger (3) for removing heat from the electronic component (2), an expansion chamber (4) fluidly connected to an outlet (5) of the evaporator heat exchanger (3), a thermosiphon heat exchanger (6) fluidly connected to an upper outlet (7) of the expansion chamber (4), a liquid-to-air heat exchanger (8) fluidly connected to a lower outlet (9) of the expansion chamber (4), and at least one pump (10) fluidly connecting an inlet of the evaporator heat exchanger (3) to the liquid-to-air heat exchanger (8) and to the thermosiphon heat exchanger (6).

2. A cooling arrangement (1) according to claim 1 , further comprising a dielectric coolant fluid, wherein the pump (10) is an electrohydrodynamic pump.

3. A cooling arrangement (1) according to any one of claims 1-2, wherein the thermosiphon heat exchanger (6) comprises a first manifold (11) fluidly connected to the upper outlet (7) of the expansion chamber (4), a second manifold (12) fluidly connected to the pump (10), and a plurality of primary fins (13), each primary fin (13) being provided with a primary fluid conduit (14) fluidly connecting the first manifold (11) to the second manifold (12).

4. A cooling arrangement (1) according to claim 3, wherein the primary fins (13) are oriented such that the primary fluid conduits (14), in use, are non-horizontally arranged with an inlet of a primary fluid conduit (14) of each primary fin (13) elevated higher than an outlet of the respective primary fluid conduit (14).

5. A cooling arrangement (1) according to any one of claims 3-4, wherein the primary fins (13) are oriented such that, in use, a major portion of each primary fluid conduit (14) extends vertically.

6. A cooling arrangement (1) according to any one of claims 1-5, wherein the liquid-to-air heat exchanger (8) comprises a plurality of secondary fluid conduits (15) fluidly connected to the expansion chamber and to the pump (10), and a plurality of secondary fins (17) attached to the secondary fluid conduits (15) such that heat conduction is enabled between the secondary fins (17) and the secondary fluid conduits (15).

7. A cooling arrangement (1) according to claim 6, further comprising a third manifold (16), fluidly connecting the expansion chamber (4) to at least some of the secondary fluid conduits (15).

8. A cooling arrangement (1) according to any one of claims 6-7, further comprising a fourth manifold (19), fluidly connecting at least some of the secondary fluid conduits (15) to the pump (10).

9. A cooling arrangement (1) according to any one of claims 6-8, wherein at least some of the secondary fluid conduits are connected directly to the expansion chamber (4), and / or are connected directly to the pump (10).

10. A cooling arrangement (1) according to any one of claims 6-9, wherein the secondary fins (17) comprise a plurality of peripheral edges and / or ridges (18), and wherein the secondary fluid conduits (15) are attached to the peripheral edges and / or ridges (18) of the secondary fins (17).11 . A cooling arrangement (1) according to any one of claims 6-10, wherein the secondary fluid conduits (15) extend perpendicular to the secondary fins (17).

12. A cooling arrangement (1) according to any one of claims 6-11 dependent on any one of claims 3-5, wherein the primary fins (13) extend parallel to the secondary fins (17).

13. A cooling arrangement (1) according to any one of claims 1-12, wherein the thermosiphon heat exchanger (6), in use, is positioned above the expansion chamber (3).

14. An electronic device comprising a cooling arrangement (1) according to any one of claims 1-6, and at least one electronic component (2) arranged adjacent the evaporator heat exchanger (3) such that heat conduction is enabled between the at least one electronic component (2) and the evaporator heat exchanger (3).

15. An electronic device according to claim 14, wherein the electronic component (2) is a power amplifier.

16. An electronic device according to any one of claims 14-15, wherein the electronic device is an electronic device of a tele communications network.

Images