Heat exchanger for an electronic component cooling system

Abstract

Heat exchanger for an electronic component cooling system. The present invention relates to a heat exchanger (1) for an electronic component cooling system (5) comprising: - a cooling plate (9) configured to be in contact with a first part (P1) of the electronic components (5) and comprising a circulation channel for a first heat transfer fluid, - a two-fluid heat exchanger (7) comprising a first fluid circuit (C1) in fluidic communication with the circulation channel of the cooling plate (9) to form a circulation loop (B) of the first heat transfer fluid and a second fluid circuit (C2) configured to receive a second heat transfer fluid, wherein the heat exchanger (1) also comprises an additional cooling plate (11) disposed in contact with the two-fluid heat exchanger (7) and at least one heat transfer element (13a, 13b,13c) arranged between the additional cooling plate (11) and a second part (P2) of the electronic components (5). Fig.1,

Description

Title of the invention: Heat exchanger for a cooling system for electronic components

[0001] The present invention relates to a heat exchanger for a cooling system for electronic components.

[0002] Servers used for data processing (commonly referred to as information technology or "IT") generally consist of printed circuit boards (PCBs) on which electronic components such as integrated circuits are arranged. These components may include central processing units (CPUs), random access memory (RAM), etc. All these electronic components generate heat when in use. In order to maintain the server contents at an optimal temperature and maximize server performance, it is essential to dissipate the heat generated and / or cool the components involved.

[0003] In general, electronic components used in servers are air-cooled. A heat sink with fins or similar elements is typically used to dissipate heat into the surrounding air. This heat sink is then placed in contact with the surface of the electronic chip. This contact can be direct or achieved through a thermal interface material between the two components. In addition to the heat sink, one or more fans can be used to circulate air and remove heat from the heat sink. Such a heat sink can be used in combination with cooling on the server installation side, such as air conditioning. However, this cooling method is not particularly efficient.It also has high operating costs and requires very large spaces to manage the air used for cooling.

[0004] Liquid immersion cooling is an alternative to air cooling. In some cases, liquid cooling allows for more efficient heat transfer from electronic components, and therefore greater cooling power. These liquids are, for example, dielectric fluids or mineral oil.

[0005] Liquids having a high specific heat capacity are particularly advantageous.

[0006] However, liquid cooling by immersion imposes significant technical constraints related to the sealing of the casings in which the circuits are immersed. printed materials as well as the weight of these boxes which must be able to be supported by the buildings in which they are installed.

[0007] It is therefore necessary to find a solution that allows for the efficient dissipation of heat from the electronic components of servers while limiting the technical constraints imposed by this cooling of the electronic components.

[0008] To this end, the invention relates to a heat exchanger for a cooling system for electronic components comprising: - a cooling plate configured to be in contact with a first set of electronic components and including a circulation channel for a first heat transfer fluid, - a two-fluid heat exchanger comprising a first fluid circuit in fluidic communication with the circulation channel of the cooling plate to form a circulation loop for the first heat transfer fluid and a second fluid circuit configured to receive a second heat transfer fluid, in which the heat exchanger also includes an additional cooling plate disposed in contact with the two-fluid exchanger and at least one heat transfer element disposed between the additional cooling plate and a second part of the electronic components.

[0009] Such a heat exchanger makes it possible to cool several separate elements or several separate circuits from a single source, thus simplifying the circuit. Furthermore, the cooling power can be adapted according to each of the components to be cooled.

[0010] According to another aspect of the present invention, the additional cooling plate is a passive cooling plate. By passive, it is understood that no fluid circulates in the cooling plate.

[0011] According to another aspect of the present invention, the heat transfer element is an element of the following list: - a metallic spring such as a helical spring, - an evaporative-condenser duct or flexible heat pipe comprising a two-phase fluid configured to evaporate at one end in contact with an electronic component and to condense at a second end in contact with the additional cooling plate.

[0012] According to another aspect of the present invention, the heat transfer element is screwed onto the additional cooling plate.

[0013] According to another aspect of the present invention, the additional cooling plate is screwed onto the two-fluid exchanger.

[0014] According to another aspect of the present invention, the additional cooling plate comprises a thermal foam disposed at the interface with the bi- A fluid is used to maximize heat exchange with the two-fluid heat exchanger. The thermal foam, for example, includes a graphite sheet with a thickness ranging from a few microns to a few millimeters.

[0015] According to another aspect of the present invention, the two-fluid exchanger comprises an aluminium support fixed by brazing and on which the additional cooling plate is fixed.

[0016] According to another aspect of the present invention, the two-fluid exchanger is a plate exchanger.

[0017] According to another aspect of the present invention, the first heat transfer fluid circulating in the circulation loop is a two-phase fluid and the heat exchanger is configured to allow said two-phase fluid to evaporate when passing through the circulation channel of the cooling plate and to condense when passing through the first fluid circuit of the two-fluid exchanger.

[0018] According to another aspect of the present invention, the cooling plate is configured to control the flow of the two-phase fluid by capillary pumping.

[0019] According to another aspect of the present invention, the cooling plate comprises a porous structure forming a wick configured to control the flow of the two-phase fluid by capillary pumping.

[0020] According to another aspect of the present invention, the cooling plate includes a floating valve configured to regulate the flow of the two-phase liquid fluid entering the circulation channel of the cooling plate as a function of the amount of two-phase liquid fluid present in the circulation channel of the cooling plate so that the greater the evaporation of the two-phase fluid in the cooling plate, the greater the flow of two-phase liquid fluid entering the cooling plate.

[0021] The present invention also relates to a system comprising a heat exchanger as described above and electronic components in which the first part of the electronic devices is associated with a first thermal power and the second part of the electronic devices is associated with a second thermal power, lower than the first thermal power.

[0022] According to another aspect of the present invention, the electronic devices are arranged on a printed circuit board, the first part of the electronic devices comprising one or more processors and the second part of the electronic devices comprising other components of the printed circuit board.

[0023] According to another aspect of the present invention, the system is a data server.

[0024] The present invention also relates to a method of using a heat exchanger as described above, comprising a two-phase fluid circulation loop connecting a hot source and a cold source, and in which the The two-phase fluid is configured to evaporate when passing through the hot source and to condense when passing through the cold source.

[0025] According to another aspect of the present invention, the hot source comprises one or more electronic components and the cold source comprises a two-fluid exchanger.

[0026] Other advantages and features will become apparent from the description of several illustrative but not limiting examples of the present invention, as well as the accompanying drawings in which:

[0027] [Fig-1] Fig. 1 is a schematic representation of a heat exchanger according to a first embodiment of the present invention;

[0028] [Fig.2] Fig.1 is a schematic representation of a heat exchanger according to a second embodiment of the present invention;

[0029] [Fig.3] The [Fig.3] is a schematic representation of a circulation loop of a two-phase fluid between two thermal devices;

[0030] [Fig.4] The [Fig.4] is a schematic representation of a cooling plate comprising a floating valve allowing regulation of the flow of two-phase fluid.

[0031] In these figures, identical elements bear the same reference numbers.

[0032] The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Simple features from different embodiments can also be combined or interchanged to provide other embodiments.

[0033] In this description, certain elements or parameters can be indexed, such as first element or second element, first parameter and second parameter, first criterion and second criterion, etc. In this case, it is simply a matter of indexing to differentiate and name similar but not identical elements, parameters, or criteria. This indexing does not imply any priority of one element, parameter, or criterion over another, and such designations can easily be interchanged without departing from the scope of this description. Nor does this indexing imply any order in time, for example, for evaluating one criterion or another.

[0034] The present invention relates to a heat exchanger for a cooling system for electronic components, in particular for electronic components of a data server.

[0035] Fig. 1 represents a schematic view of such a heat exchanger 1 according to a first embodiment.

[0036] The electronic components 5 and the heat exchanger 1 can be arranged in a housing 3.

[0037] The different electronic components 5 can be associated with different thermal powers, that is to say they can generate more or less heat and therefore require a greater or lesser dissipation of heat to limit their temperature.

[0038] The electronic components 5 are for example subdivided into a first part PI associated with a first thermal power, a second part P2 associated with a second thermal power lower than the first thermal power and a third part P3 associated with a third thermal power lower than the second thermal power.

[0039] The first part PI of the electronic components 5 includes, for example, a processor 5a (“Central Processing Unit (CPU)” in English) or several processors 5a, the second part P2 of the electronic components 5 includes, for example, random access memory (“Random Access Memory (RAM)” in English) and / or a power supply, and the third part includes, for example, transistors and other simple electronic components.

[0040] The set of electronic components 5 can be arranged on a single printed circuit board 6 (“Printed Circuit Board (PCB)” in English).

[0041] The heat exchanger 1 includes a cooling plate 9 configured to be in contact with the first part PI of the electronic components 5, here the processor 5a. The cooling plate 9 includes a circulation channel configured to receive a first heat transfer fluid.

[0042] The heat exchanger 1 also includes a two-fluid exchanger 7.

[0043] The two-fluid exchanger 7 includes a first fluid circuit Cl in fluidic communication with the circulation channel of the cooling plate 9 to form a circulation loop B of the first heat transfer fluid.

[0044] The first heat transfer fluid is for example a two-phase fluid configured to evaporate when passing through the cooling circulation channel 9 and to condense when passing through the first fluid circuit Cl of the two-fluid exchanger.

[0045] The two-fluid exchanger 7 also includes a second fluid circuit C2 configured to receive a second heat transfer fluid.

[0046] The inlet of the second fluid circuit C2 is, for example, connected to a supply line 12 for the second heat transfer fluid. The supply line 12 may be a line supplying various cabinets (“racks”) of the data server and may be connected to a central heat exchanger (not shown) of the data server.

[0047] The outlet of the second fluid circuit C2 is, for example, connected to a return line 18 of the second heat transfer fluid. The return line 18 of the heat transfer fluid is, for example, connected to the central heat exchanger of the data server. The second heat transfer fluid is, for example, water or glycol water.

[0048] The two-phase fluid of the circulation loop B is chosen such that, during its circulation in the circulation loop B, the two-phase fluid evaporates as it passes through the cooling plate 9, which, together with the first part PI of the electronic components 5, constitutes a hot source, and condenses as it passes through the two-fluid heat exchanger 17, which constitutes a cold source. This evaporation and condensation allow the two-phase fluid to circulate in the circulation loop B, with the flow rate of the two-phase fluid being greater as the temperature of the cooling plate 9 increases.

[0049] According to an alternative embodiment shown in [Fig. 3], the circulation loop B comprises a porous structure 19 forming a wick at the level of the cooling plate 9. The porous structure 19 is disposed in the circulation channel of the two-phase fluid in the cooling plate 9. The porous structure 19 is configured to control the flow rate of the two-phase fluid by capillary pumping. Indeed, the gaseous phase of the two-phase fluid evaporated in the cooling plate 9 returns to the two-fluid heat exchanger 17 via a first section SE1 of the circulation loop B. This evaporation causes the two-phase fluid in liquid phase from the two-fluid heat exchanger 17 to be drawn into the second section SE2 of the circulation loop B, the two-phase fluid condensing as it passes through the two-fluid heat exchanger 17.

[0050] According to an alternative embodiment shown in [Fig.4], the circulation loop B includes a floating valve 21 at the level of the cooling plate 9. The floating valve 21 is disposed in the circulation channel of the two-phase fluid of the cooling plate 9. The floating valve 21 is configured to regulate the flow of the two-phase fluid in liquid phase entering the cooling plate 9 according to the quantity of two-phase fluid in liquid phase present in the cooling plate 9 so that the greater the evaporation of the two-phase fluid in the cooling plate 9, the lower the level of the floating valve 21 and the greater the flow of two-phase fluid in liquid phase from the two-fluid exchanger 17 and entering the cooling plate 9.The two-phase gaseous fluid evaporated in the cooling plate 9 returns to the two-fluid heat exchanger 17 via the circulation loop B. The two-phase fluid is then condensed in the two-fluid heat exchanger 17 to return to the cooling plate 9 in liquid form.

[0051] Thus, the circulation of the two-phase fluid in the circulation loop B can be without requiring a pump and without energy input other than the heat produced by the processor 5a in contact with the cooling plate 9.

[0052] The heat exchanger 1 also includes an additional cooling plate 11 arranged in contact with the two-fluid exchanger 7 and in particular near the second fluid circuit C2 in which the second heat transfer fluid circulates.

[0053] The additional cooling plate 11 may be passive, i.e., without a fluid circulation channel. The additional cooling plate 11 allows, in particular, heat exchange by conduction. The additional cooling plate 11 may be a metallic plate, in particular made of steel or aluminum.

[0054] The additional cooling plate 11 may include a thermal pad disposed at the interface with the two-fluid heat exchanger 7 to maximize heat exchange with the two-fluid heat exchanger 7. The thermal pad may include, for example, a graphite sheet with a thickness between 100 microns and a few millimeters. The thermal pad may also include other elements such as silicone.

[0055] The heat exchanger 1 also includes at least one heat transfer element disposed between the additional cooling plate 11 and the second part P2 of the electronic components 5. The heat transfer element is in contact on one side with the additional cooling plate 11 at a first end and on the other side with at least one of the electronic components 5 of the second part P2 of the electronic components 5.

[0056] The heat transfer element is for example a metal spring 13a such as a helical spring.

[0057] The heat transfer element can also be a flexible evaporator-condenser duct 13b, also called a heat pipe, containing a two-phase fluid configured to evaporate at one end of the heat transfer element in contact with the electronic component(s) 5 of the second part P2 and to condense at the second end of the heat transfer element in contact with the additional cooling plate 11.

[0058] The heat transfer element can also be made of a thermally conductive material such as a plastic material filled with metallic particles or any other material having a high thermal conductivity (e.g., >1W.ml.Kl). The heat transfer element is, for example, screwed onto the additional cooling plate 11 like the heat transfer element 13c of [Fig. 2]. The heat transfer element can also be glued.

[0059] A fan 14 can also be arranged in the housing 3 to promote cooling of the electronic components by convection, in particular for the Electronic components 5 of the third part P3 that are not in contact with a heat transfer element. The heat produced by the electronic components of the third part P3 is then transferred to the two-fluid heat exchanger 7 by convection via the air present in the housing 3. In the absence of housing 3, the heat from the components of the third part is dissipated into the surrounding air.

[0060] The present invention also relates to a system comprising a heat exchanger 1 as described above and electronic components 5. The system is for example a data server comprising a plurality of heat exchangers 1 as described above connected to a central heat exchanger and a general circuit allowing the circulation of the heat transfer fluid to the various heat exchangers via supply ducts 12 and return ducts 18.

[0061] The present invention also relates to a method of using a heat exchanger 1 as described above comprising a circulation loop of a two-phase fluid, for example the circulation loop B, connecting a hot source, for example the cooling plate 9 in contact with the processor 5a, and a cold source, for example the two-fluid exchanger 7, and in which the two-phase fluid is configured to evaporate when passing through the hot source, here the cooling plate 9, and to condense when passing through the cold source, here the two-fluid exchanger 7. The flow rate of the two-phase fluid is, for example, controlled by a floating valve 21 or a porous structure 19 forming a wick configured to perform capillary pumping.

[0062] Thus, the present invention makes it possible, by using a heat exchanger 1 comprising at least two separate cooling devices for different electronic components 5 having different thermal powers from a single heat transfer fluid, to cool the different electronic components 5 simply and efficiently while limiting the weight of the cooling device for the electronic components 5.

Claims

Demands

1. Heat exchanger (1) for a cooling system for electronic components (5) comprising: - a cooling plate (9) configured to be in contact with a first part (PI) of the electronic components (5) and comprising a circulation channel for a first heat transfer fluid, - a two-fluid heat exchanger (7) comprising a first fluid circuit (C1) in fluidic communication with the circulation channel of the cooling plate (9) to form a circulation loop (B) of the first heat transfer fluid and a second fluid circuit (C2) configured to receive a second heat transfer fluid, characterized in that the heat exchanger (1) also comprises an additional cooling plate (11) disposed in contact with the two-fluid heat exchanger (7) and at least one heat transfer element (13a, 13b,13c) arranged between the additional cooling plate (11) and a second part (P2) of the electronic components (5), and in that the additional cooling plate (11) is a passive cooling plate.

2. Heat exchanger (1) according to claim 1 wherein the heat transfer element (13a, 13b, 13c) is an element of the following list - a metal spring (13a) such as a helical spring, - a flexible evaporator-condenser duct (13b) comprising a two-phase fluid configured to evaporate at a first end in contact with an electronic component (5) and to condense at a second end in contact with the additional cooling plate (H).

3. Heat exchanger (1) according to the preceding claim in which the heat transfer element (13c) is screwed onto the additional cooling plate (11).

4. Heat exchanger (1) according to any one of the preceding claims wherein the two-fluid exchanger (7) comprises an aluminium support (7a) fixed by brazing and on which the additional cooling plate (11) is fixed.

5. Heat exchanger (1) according to any one of the preceding claims wherein the two-fluid exchanger (7) is a plate exchanger.

6.

7.

8.

9. Heat exchanger (1) according to any one of the preceding claims in which the first heat transfer fluid circulating in the circulation loop (B) is a two-phase fluid, the heat exchanger (1) being configured to allow said two-phase fluid to evaporate during its passage through the circulation channel of the cooling plate (9) and to condense during its passage through the first fluid circuit (Cl) of the two-fluid exchanger (7). Heat exchanger (1) according to the preceding claim in which the cooling plate (9) is configured to control the flow of the two-phase fluid by capillary pumping. Heat exchanger (1) according to the preceding claim in which the cooling plate (9) includes a floating valve (21) configured to regulate the flow of the two-phase liquid fluid entering the circulation channel of the cooling plate (9) as a function of the amount of two-phase liquid fluid present in the circulation channel of the cooling plate (9) such that the greater the evaporation of the two-phase fluid in the cooling plate (9), the greater the flow of two-phase liquid fluid entering the cooling plate (9).Method of using a heat exchanger (1) according to any one of the preceding claims comprising a two-phase fluid circulation loop connecting a hot source and a cold source and wherein the two-phase fluid is configured to evaporate when passing through the hot source and to condense when passing through the cold source.

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