Electronic system, in particular cooling system for a data center

Abstract

A cooling system (1) for a data center, the data center including a plurality of servers (2), the plurality of servers being associated to form a rack (3), each server (2) being provided with one or more heat generating means (4), the system including a plurality of first heat exchange circuits (5) and a second thermosyphon circuit (8). The overall construction of the system is such that the second thermosyphon circuits (8) are fluidly connected to each other in parallel connection.

Description

Technical Field

[0001] The present invention relates to a cooling system, particularly for a data processing center or a data center, and generally for cooling electronic components, i.e., heat-generating means. Background Art

[0002] The cooling of electronic and information systems is crucial for the efficiency and operation of the systems themselves. For example, the heat generated by a processing unit (such as a CPU) can cause multiple components to overheat until a temperature peak is reached, which can invalidate the proper operation of the electronic system under consideration.

[0003] This problem is particularly felt in the field of data processing centers (DPCs) or data centers, where there are typically multiple CPUs and other heat generators in close proximity to each other.

[0004] In fact, due to the development and innovation of information technology and the widespread popularity of the Internet network, the processing, storage, and transmission of data and information are of strategic importance in every field of industry and service. Along with the huge amount of data being processed, data centers can have extremely relevant dimensions, up to occupying an entire room or an entire building.

[0005] Data centers typically include multiple servers configured to manage data. Generally, a server includes a motherboard on which a processing unit (CPU) is placed. Commercial servers usually consist of a motherboard with two CPUs, other low-power components, and a stack of hard drives. The size and type of electronic components vary according to the server manufacturer, but the overall size of the server is usually standardized.

[0006] Servers are usually positioned one above the other in a suitable frame to form a server stack, or alternatively called a server rack, with the aim of optimizing space. Conventionally known arrangements provide multiple server racks that are placed side by side and spaced apart just enough to allow maintenance procedures or other interventions.

[0007] CPUs and servers are usually energy-consuming and generate heat during use, which is the fundamental reason for providing a cooling system suitable for controlling and managing temperature.

[0008] In particular, it is necessary to avoid overheating, which can damage multiple server components by endangering the operation of the data center.

[0009] In the prior art, there are different solutions for the thermal management of data centers, which propose using air as a cooling fluid. These solutions can be applied at different levels. Generally, the thermal management of a data center is divided into five levels:

[0010] 1) "Chip" or CPU level;

[0011] 2) At the "server" level;

[0012] 3) At the "rack" level;

[0013] 4) At the "plenum" level;

[0014] 5) At the "compartment" level.

[0015] Two other levels can be added to these levels, involving:

[0016] 6) The possible air conditioning of the data center compartments - the "Computer Room Air Conditioning" (CRAC) level - and

[0017] 7) A chiller or cryogenic cooler for generating a cooling carrier fluid for cooling data center components - the "cryogenic cooler" level.

[0018] Chip level

[0019] Since the CPU is a high - power component of the motherboard, it generates a significant heat load that must be appropriately removed.

[0020] Similar considerations can also be made for other heat - generating components that are not necessarily used in the data center, such as the moving parts of the motherboard or other electronic components that tend to overheat during operation.

[0021] Currently, known solutions provide local cooling of heat - generating means by applying a suitable heat - exchange device or cooling circuit to one or more heat - generating means. The operation of the device or circuit is combined with the action of a fan that is adapted to force an air flow through the device to cut heat from the heat - generating means.

[0022] For example, to cool the CPU, it is known to use a heat - exchange device applied to the CPU itself, which is equipped with a series of fins made of aluminum bonded to a copper plate and a series of capillary tubes for heat transfer. A set of fans, for example fixed to the structure of the server or anyway located near the heat - generating means, forces an air flow through the fins. The thermal contact between the copper plate and the CPU is ensured by a thermal paste (typical values of thermal conductivity are between 7 W / mK and 12 W / mK). The CPU heat load first flows on the thermal paste, then on the copper plate, on the capillary tubes, on the aluminum fins, and finally is ejected into the air flow. Usually, when the CPU operates near its thermal design power, the total thermal resistance of such a system varies from 0.7 K / W to 1 K / W. When the fans are forced to work at the maximum revolutions per minute (RPM), these values can be reduced, for example, to 0.3 K / W, but this brings a large energy consumption and requires maintenance.

[0023] The reason for such a low thermal resistance is the low thermal conductivity of air and the boiling limit of the capillary.

[0024] In addition, the use of the fan generates heat that must be dissipated by reducing the total output of the heat exchange device.

[0025] Another drawback associated with cooling devices or traditional circuits is associated with the size of the cooling device or traditional circuit. In fact, the height of known devices is related to the thickness of the motherboard, which involves excessive overall dimensions, resulting in a significant reduction in available space.

[0026] Another additional drawback is related to the structural complexity and implementation of known devices and circuits. This complexity not only affects the implementation cost, but also makes the possible maintenance process more difficult.

[0027] Server level

[0028] The air flow required for cooling at the chip level is provided by a set of fans shrouded in the server structure. Typically, there are four to eight fans operating in parallel, but depending on the layout of the electronic components, the server height, and the efficiency of the heat sink, there can be multiple groups of fans operating in series. The heat sink is usually enclosed by a plastic cover, the purpose of which is to direct the air flow to the fins and prevent the latter from being bypassed.

[0029] The speed of the fan is usually managed by the integrated software provided by the motherboard manufacturer. The logic of this software is determined by the trade-off between the energy consumption of the fan, the maintenance requirements, and the CPU temperature.

[0030] At full load, the energy consumption of the fan can vary from 50W to 200W.

[0031] Rack level

[0032] When performing CPU cooling through air flow, the thermal management at the rack level involves the correct distribution and optimization of the air flow coming from the compartment and reaching the server. Common solutions provide modifications to the rack structure and optimization of the positioning of the servers within the rack itself. The successful techniques for thermal management at this level are associated with the air inlets in the rack. In a data center with a raised floor, the volume of air inhaled by the server depends on the pressure drop across the server and the speed of the fan. Since the cable management kit imposes an additional pressure drop, there are other external parameters, such as the holes in the front door of the rack, the heat exchanger on the back door of the rack, and the barriers, which can significantly affect the air flow rate inhaled by the server.

[0033] When the air flow towards the server is insufficient to cool the chip, a centrifugal air manager can be installed at the rear of the rack to suck in more air from the front and push it upwards, for example towards the return air plenum. This solution increases the energy consumption.

[0034] Plenum level

[0035] Even the design of the plenum chamber is very important for the distribution of air flow to the racks. A common solution is to provide a plenum chamber for air transmission under the floor of the computer room and a plenum chamber for air return above the ceiling. The air flow can reach the racks through the floor to cool the racks. The air flow through the floor depends on the planning parameters of the plenum chamber, such as the plenum chamber depth, the specifications of the floor tiles and the partitions under the floor.

[0036] Therefore, it is important to control the pressure distribution through the plenum chamber.

[0037] Compartment level

[0038] Now, the most effective way to supply cold air from the plenum chamber to the rows of racks is to use the so-called "hot aisle / cold aisle" arrangement. The rows of racks are spaced sufficiently apart from each other to allow for the optimal distribution of cold air from the perforated tiles on the floor. In the aisles where there are no perforated tiles, vents are provided in the ceiling to allow the hot air from the servers to reach the CRAC (Computer Room Air Conditioning) unit. This arrangement requires careful planning of the distance between the rows of racks, the height of the racks and the ceiling height.

[0039] CRAC level

[0040] It is known that installing air conditioners in the data center room has the purpose of controlling the temperature. The Computer Room Air Conditioner (CRAC) for the data center must be planned with Class A1 equipment (the allowed conditions in the computer room are more stringent in terms of dry bulb temperature and relative humidity) to limit maintenance and increase the life expectancy of the electronic devices. Typically, but even depending on the location, a complete Air Handling Unit (AHU) suitable for winter and summer is required to maintain the air flow in the computer room according to the Class A1 limitations. The AHU consists of a filter, a blower, heating and cooling coils, a humidifier and a dehumidifier, and a mixer. The strict control of the dry bulb temperature and relative humidity increases the effective cooling load required for the computer room.

[0041] Cryocooler level

[0042] Typically, a set of chillers is located outside the computer room to supply chilled water to the cooling coils of the CRAC unit. Depending on the location of the data center, the chillers can be of two types:

[0043] - Water-cooled chillers, where the condenser is cooled on the water side of a cooling tower;

[0044] - Air-cooled condenser, in this case the condenser is a coil cooled by a ventilator.

[0045] The coefficient of performance (COP) of a cryogenic cooler strongly depends on the evaporation temperature. The higher the evaporation temperature, the greater the COP.

[0046] In known cooling systems, high COP values cannot be achieved because the evaporation temperature must be kept rather low to be compatible with the coils of the air-cooled condenser.

[0047] In summary, the technology of air cooling for electronic components and systems is well known and requires low investment costs at the chip and server levels. However, it has disadvantages associated with the use of fans and other motorized components, which require energy and generate heat to be disposed of.

[0048] In addition, there are disadvantages to be managed at the levels of racks, plenums, rooms, CRACs, and cryogenic coolers. In particular, the distribution of the air flow becomes a key point because poor air distribution can lead to a reduction in the lifespan of the servers and an increase in the need for maintenance and the risk of failures.

[0049] At the CRAC level, the fact that only the AHU manages the cooling load increases the required cooling load and thus reduces the efficiency of heat removal.

[0050] At the cryogenic cooler level, the inefficiency at the CRAC level reduces the COP of the cryogenic cooler by increasing the total energy consumption for cooling the computer room.

[0051] In addition, known air-cooled systems are complex to implement because they provide assemblies of multi-stage mechanical and electronic components (ventilators, AHU units, cryogenic coolers, room layouts). Even during maintenance phases when the activities of the data center usually need to be interrupted, the implementation complexity has a negative impact. Summary of the Invention

[0052] The technical problem proposed and solved by the present invention is to provide a cooling system for data centers and ordinary electronic components, which allows the elimination of the disadvantages mentioned above with reference to the known technology.

[0053] This problem is solved by the cooling system according to claim 1.

[0054] The preferred features of the present invention are set forth in the dependent claims.

[0055] The present invention provides some related advantages. The main advantage lies in the simple construction and high output of the cooling system.

[0056] According to one aspect of the present invention, the proposed system is used to cool the CPU of a server in an efficient and passive manner, even in the case of a CPU with a much higher power than the current CPU.

[0057] According to one aspect of the present invention, the system allows the cooling of the entire server rack through heat exchange located at the heat generating means and allows the use of the principle of a thermosiphon.

[0058] The system provides a first heat exchange circuit or main circuit at the level of a single server, which includes a heat exchange area coupled to the heat generating electronic components, and provides a secondary circuit at the rack level, which is particularly composed of a plurality of thermosiphon circuits supplied in parallel and is adapted to exchange heat with the main circuit of the corresponding server. The secondary circuit is coupled to the (each) main circuit at the said heat exchange area, i.e., at the heat generating means.

[0059] According to the first embodiment, the main circuit includes at least one thermosiphon circuit. The thermosiphon circuit includes an evaporation part coupled to the electronic component to be cooled and a condensation part overlapping with the evaporation part and coupled to the secondary circuit.

[0060] According to the second embodiment, the main circuit includes a device with a pulsating oscillating motion, or a so-called "pulsating heat pipe" device, which has a reduced weight and production cost. In addition, this device can be easily adjusted and adapted to different applications, and thus it is extremely versatile.

[0061] The pulsating heat pipe device is based on the physical principle of a pulsating heat pipe, in which by utilizing the expansion force of the gas phase and the compression force of the liquid phase, the heat-carrying fluid in a two-phase (liquid and vapor) state is alternately heated and cooled to trigger the oscillating motion therein. Then, even the pulsating heat pipe device is implemented as a passive cooling system that does not require a pump.

[0062] In addition, based on a preferred embodiment, the proposed cooling system requires a smaller height extension because its operation does not require gravity.

[0063] In a specific embodiment, other structural and thermal advantages are associated with the plate-like element used as a heat exchange device. In fact, such a plate-like element, which is described in more detail below in its specific embodiment examples, is inexpensive and efficient and implements microchannel technology.

[0064] Other advantages, features and usage modes of the present invention will be apparent from the following detailed description of some embodiments, which are shown by way of example and not for the purpose of limitation. Description of the Drawings

[0065] Reference will be made to the figures in the accompanying drawings, wherein:

[0066] ■ Figure 1Shows a schematic side view of a cooling system according to the present invention and according to a first embodiment;

[0067] ■ Figures 2 - 3 and Figure 4 Two axonometric views and a side cross-sectional view respectively showing different details of the cooling system according to the first embodiment of the present invention;

[0068] ■ Figure 5 and Figure 6 A general view and a side cross-sectional view respectively showing additional details of a preferred variant of the first embodiment of the present invention;

[0069] ■ Figure 7 Shows a schematic side cross-sectional view of a device including a plurality of cooling systems according to a preferred embodiment of the present invention;

[0070] ■ Figure 8 Shows a schematic side view of a preferred connection configuration of the cooling system implemented in the first embodiment of the cooling system;

[0071] ■ Figure 8A Shows a top view schematic of an additional preferred connection configuration of details of components of the cooling system according to the present invention;

[0072] ■ Figure 9 and Figure 10 Show an axonometric view of different details of the cooling system according to the second embodiment of the present invention;

[0073] ■ Figure 11 Shows Figure 10 a side view;

[0074] ■ Figure 12 Shows a view of cross-section A-A according to Figure 11 ;

[0075] ■ Figures 13 - 16 Shows a plan cross-sectional view of components of the details shown according to a preferred structural variant of Figure 10 ;

[0076] ■ Figure 17 Shows a top view schematic of a fluid component implemented with the structural details shown according to a variant of a preferred embodiment of Figure 10 ;

[0077] The dimensions of the above figures are intended to be only exemplary and not necessarily to scale. Detailed Description

[0078] Embodiments and variants of the present invention will be described below with reference to the above drawings.

[0079] In the multiple figures, similar components are denoted by the same or corresponding reference numerals.

[0080] In the following detailed description, additional embodiments and variants will be restrictively described with respect to the embodiments and variants already addressed in the same description, to distinguish them from what has been disclosed.

[0081] Furthermore, the multiple embodiments and variants described below can be used in combination when compatible.

[0082] First, with reference to Figure 1 , according to an embodiment of the present invention, a cooling system for a data processing center or a data center is generally designated by 1.

[0083] The data center includes a plurality of servers 2, which are associated to form a plurality of racks 3, which are shown in simplified form in the figure. In the figure, the rack 3 is shown with the servers 2 stacked vertically, but other alternative arrangements of the servers 2 are not excluded, such as where the servers 2 are arranged according to a horizontal stacking arrangement or according to a stacking with an inclined orientation.

[0084] Advantageously, each rack 3 can include a frame 3a, in which a seat 2a is defined, configured to accommodate the server 2.

[0085] Each server 2 is equipped with heating means 4, meaning a component or group of components that generate heat to be dissipated during use.

[0086] Preferably, as Figure 2 shown, each server 2 can include a motherboard 23 to which the heating means 4 is applied.

[0087] In particular, each server 2 is equipped with a data processing unit CPU, which generates heat to be dissipated during use. The number of heating means 4 varies according to the type of server. By way of example, the server 2 shown in the figure includes two CPUs 4, but solutions with multiple CPUs 4 are not excluded. Furthermore, the server 2 can accommodate multiple units, such as one rack unit (1U) or two rack units (2U) or more (3U, 4U, etc.).

[0088] Furthermore, solutions are not excluded where the server 2 even includes other heating means 4, such as other hardware units different from the CPU, such as network cards, hard drive management cards, hard drives, and continuity groups.

[0089] The system 1 advantageously includes at least one first heat exchange circuit or main circuit, designated by the reference numeral 5, and includes a heat exchange area placed at the heating means 4, said specific positioning allowing for the local dissipation of the heat generated by the heating means 4.

[0090] In the present specification, the term "first heat exchange circuit" or "main circuit" includes any circuit, preferably a closed circuit, within which a first carrier fluid allows heat exchange based on its phase change and / or by circulation (miniature heat pipe) or oscillation (pulsating heat pipe) movement.

[0091] In use, the first heat-carrying fluid circulates within the main circuit.

[0092] For example, referring Figures 2 - 6 and Figure 8 to the embodiment shown, the first heat exchange circuit includes a first heat pipe circuit 5. Preferably, the number of the first heat pipe circuits 5 corresponds to the number of heat-generating means 4 provided by each server 2. Each first heat pipe circuit is connected to the corresponding heat-generating means 4 at the heat exchange area.

[0093] Each main circuit 5 is configured to allow the circulation of the first heat-carrying fluid suitable for heat exchange with the heat-generating means 4.

[0094] This configuration enables the first fluid to extract heat from the heat-generating means 4.

[0095] The heat exchange occurring within the main circuit 5 causes a phase change, which triggers the spontaneous convective movement of the first fluid within the main circuit.

[0096] Advantageously, the system provides the main circuit 5 for each heat-generating means 4 by allowing local cooling of each heat-generating means 4.

[0097] The system 1 further includes a secondary circuit composed of a plurality of second heat pipe circuits 8, which are fluidly connected to each other in particular and arranged according to a parallel configuration with respect to each other. Each second heat pipe circuit 8 is associated with a corresponding server 2 among the above-mentioned plurality of servers.

[0098] In particular, the above-mentioned second heat pipe circuits 8 are thermally connected to the main circuit 5 at the heat exchange area placed at the heat-generating means 4.

[0099] More specifically, each of the second heat pipe circuits 8 is thermally connected to the main circuit 5 placed at the corresponding server 2.

[0100] In use, the second heat-carrying fluid circulates within the second heat pipe circuit, aiming to exchange heat with the above-mentioned first working fluid.

[0101] Preferably, the second thermosyphon circuit 8 is fluidly connected to each other through a single delivery pipe 15 and a single return pipe 16. In this way, the second circuit 8 defines an architecture that is easily self-regulating and has a simple structure because they do not require multiple parallel delivery pipes and return pipes. In fact, the solution with a single delivery pipe 15 and a single return pipe 16 (from which the thermosyphon circuit 8 branches) minimizes the overall size and, at the design stage, makes it easier to dimension the pipes themselves in order to avoid unstable states of the working fluid.

[0102] As Figure 1 shown in the example of, the delivery pipe 15 and the return pipe 16 are arranged in parallel with each other and are in a substantially vertical position.

[0103] The second carrier fluid flows in the delivery pipe 15 in a substantially liquid state, flows downward by gravity and branches into each second thermosyphon circuit 8.

[0104] In the second thermosyphon circuit 8, the second carrier fluid is heated by extracting heat from the main circuit 5 and changes its state from a substantially liquid state to a substantially gaseous state.

[0105] The second thermosyphon circuit transfers the second carrier fluid in a substantially gaseous state in a single return pipe 16, in which the second carrier fluid returns and exits the rack 3.

[0106] In this way, the principle of the thermosyphon is applied at the rack level, with the second carrier fluid flowing downward in a liquid state in the delivery pipe 15 by gravity, being heated in the second parallel thermosyphon circuit 8, and rising in a gaseous state in the return pipe 16.

[0107] Advantageously, the second thermosyphon circuit 8 is configured to allow the circulation of a second heat-carrying fluid adapted to exchange heat with the first heat-carrying fluid.

[0108] This configuration enables the second fluid to extract heat from the first fluid circulating in the respective main circuit 5.

[0109] The heat exchange that then occurs within the second thermosyphon circuit 8 causes a phase change, which triggers a spontaneous convective movement of the second fluid within the second circuit itself.

[0110] As described, the overall system configuration 1 enables the second thermosyphon circuits 8 to be fluidly connected to each other according to a parallel connection.

[0111] This connection enables the second fluid to circulate in parallel at each server 2 by extracting heat from the fluid circulating in the main circuit 5.

[0112] In an advantageous embodiment, the second thermosiphon circuit 8 is arranged such that the vapor line exiting from the corresponding server 2 is staggered with respect to the liquid line entering the same server 2.

[0113] In other words, each server 2 is fluidly connected to the delivery pipe 15 at a height lower than the height at which the return pipe 16 is fluidly connected to the same server 2, the height being considered with respect to the extension direction of the delivery pipe 15 and the return pipe 16 with respect to a reference plane, such as the resting plane of the corresponding server 2.

[0114] Advantageously, when increasing the height difference between the inlet of the liquid line and the outlet of the vapor line exiting from the same server 2, the maximum flow rate of the second carrier fluid passing through each server 2 increases.

[0115] In this way, the cooling system 1 of the present invention allows a higher thermal load to be disposed of, while ensuring the overall stability of the system itself.

[0116] According to a preferred embodiment, at the level of each server 2, a collector element for distributing the second carrier fluid can be provided. In particular, in the case where there are multiple heat-generating means 4 in the same server 2, this solution allows the architecture of the cooling system 1 to be simplified, with specific reference to the implementation of the second thermosiphon circuit 8.

[0117] Reference Figure 8A , which shows a top view schematic of the server level 2 and the secondary circuit 8 connected to each of the four main circuits 5, the four main circuits being associated with corresponding heat-generating components 4 (hidden in the perspective of the figure).

[0118] Advantageously, in order to reduce the complexity and branching of the connections required to bring the second thermosiphon circuit 8 to each heat-generating component 4, the server 2 can have or be associated with a first collector 13A for the liquid line and a second collector 13B for the vapor line. As can be seen, the same number of corresponding connection parts 13a, 13b branch out from the first collector and the second collectors 13A, 13B as there are main circuits 5 that extract heat from the heat-generating components 4.

[0119] Then the cooling system 1 according to the present invention allows the physical principle of the thermosiphon to be applied to multiple "heat exchange levels":

[0120] The local level or "chip level", which is achieved by locally cooling each heat-generating means 4 through the first heat exchange circuit or main circuit 5;

[0121] The "server" level, which is achieved by cooling each server 2 through the corresponding second thermosiphon circuit 8, which extracts heat from the first carrier fluid of each main circuit 5 present at the heat-generating means 4 in the same server.

[0122] At the "rack" level, this is achieved by the parallel connection of the second circuit 8, which allows the heat removed from the first carrier fluid to be taken out of the rack 3 through the parallel circulation of the second fluid in a plurality of servers 2.

[0123] Aspects of the function and structure of one or more embodiments of the present invention are described below. For easier understanding, the present invention is described below with respect to a plurality of "heat exchange levels".

[0124] Now will be described Figures 1 - 6 the first embodiment of the cooling system 1 schematically shown in

[0125] Chip level

[0126] The "chip level" means that heat exchange is "localized" at a single heat generating means 4.

[0127] According to the first embodiment of the cooling system 1, the main circuit includes a thermosyphon circuit 5 for each heat generating means 4.

[0128] Preferably, the first carrier fluid can be selected from the following refrigerant fluids, the abbreviations of which refer to the international standard Nr.34 ASHRAE: R1234ze(E), R1233zd(E), R1234yf. These are particularly useful for thermal performance, saturation pressure and low global warming potential (GWP). Refrigerant fluids having properties similar to those of the above fluids are not excluded.

[0129] See Figures 2 - 4 , usefully, the first thermosyphon circuit 5 can be of the type of device including an evaporation section 6 and a condensation section 7, the evaporation section can be placed in thermal contact with the corresponding heat generating means 4, and the condensation section is placed in thermal connection with one or more second thermosyphon circuits 8 or with another external system. Preferably, the evaporation section 6 and the condensation section 7 are each implemented as a single piece.

[0130] The evaporation section and the condensation section are implemented as the above heat exchange regions.

[0131] Thermal bonding materials or other elements are not necessary to allow their removal.

[0132] Preferably, each first thermosyphon 5 can have an evaporation section 6 and a condensation section 7. By ensuring and improving the cooling performance of the first thermosyphon circuit 5, this solution prevents instability from occurring in the second thermosyphon circuit 8.

[0133] In particular with reference to Figure 5 and Figure 6 , the evaporation section 6 and the condensation section 7 can include heat exchange means 11b, 12a, 12b.

[0134] In particular, the evaporation section 6 and the condensation section 7 include respective plate-like elements 11, 12 equipped with heat exchange means.

[0135] Advantageously, the heat exchange means 11b, 12a, 12b may include a plurality of fin elements 11b, 12a, 12b which define flow-through channels for the first heat-carrying fluid and / or the second heat-carrying fluid, also known as "microchannels".

[0136] The microchannels can be designed so as to optimize both the heat transfer coefficient and the pressure drop of the carrier fluid and to avoid the occurrence of trapped bubbles. Advantageously, for the process of manufacturing the microchannels, a milling and cutting process using a numerically controlled machine tool starting from an initial element can be provided.

[0137] Preferably, the plate-like elements 11, 12 may be made of copper because of its high thermal conductivity. Alternative solutions are not excluded, for example the entire first thermosyphon loop 5 is made of aluminium.

[0138] Reference Figure 3 、 Figure 4 、 Figure 5 and Figure 6 In the illustrated embodiment, the evaporation section 6 includes a plate-like element 11 placed in thermal contact with the heating means 4. Thus, the plate-like element 11 has the function of cooling the heating means 4 and can therefore be referred to as a "cold plate".

[0139] Advantageously, the thermal contact between the plate-like element 11 and the heating means 4 can be implemented by means of a thermal paste or other thermal interface material (TIM). The thermal paste can be interposed between the cold plate 11 and the heating means 4 and is suitable for promoting heat exchange between the two.

[0140] Advantageously, a thermal paste with a thermal conductivity equal to or higher than 12.5 W / mK can be used.

[0141] Advantageously, the evaporation section 6 may include a cover-like element 27 associated with the plate-like element 11 to define an evaporation volume 6a in which the first carrier fluid can exchange heat from a substantially liquid phase to a substantially gaseous phase. This configuration allows the cover-like element 27 and the plate-like element 11 to define the evaporation volume 6a. The condensation section 7 may include a plate-like element 12 which is equipped with fin elements 12a on one side and fin elements 12b on the opposite side. The fin elements 12a define microchannels through which the first carrier fluid can flow to give up heat. Conversely, the fin elements 12b define microchannels in thermal contact with the fin elements 12a and through which the second carrier fluid can flow, which latter acquires the heat given up by the first carrier fluid.

[0142] In particular, the condensation section 7 may include a second cover-like element 26 associated with the plate-like element 12 to define a condensation volume 7a in which the first carrier fluid may further exchange heat from a substantially gaseous phase to a substantially liquid phase. The fin elements 12a of the plate-like element 12 are included in the condensation volume 7a. This configuration may enable the cover-like element 26 and the plate-like element 12 to define the condensation volume 7a.

[0143] Within the evaporation volume 7a and / or volume 6a, at least one element 37a, 37b for distributing the fluid may be inserted into the respective covers 26, 27. The distribution elements 37a, 37b are suitably configured to optimize the distribution of the fluid circulating within the respective covers 26, 27.

[0144] Advantageously, the first thermosyphon circuit 5 may include a delivery channel 25 and a return channel 24 connecting the evaporation section 6 and the condensation section 7.

[0145] Solutions are not excluded in which, depending on the type of fluid used and the heat load of the heat generator, there are different numbers of delivery channels 25 and return channels 24.

[0146] Advantageously, the channels 24, 25 may be arranged vertically and in parallel with each other.

[0147] Preferably, within the evaporation volume 6a, the first distributor element 37a may be interposed between the delivery channel 25 and the fin element 11a. The distributor element 37a is configured to reduce the passageways available for the fluid exiting from the delivery channel 25 before entering the fin element 11a.

[0148] Within the condensation volume 7a, the second distributor element 37b may be interposed between the return channel 24 and the fin element 12a. The distributor element 37b is configured to reduce the passageways available for the fluid exiting from the return channel 2a before entering the fin element 12a.

[0149] Then, the distribution elements 37a, 37b allow the regulation of the flow of the first carrier fluid.

[0150] The distribution elements 37a, 37b are configured to reduce the passageways of the fluid exiting from the delivery channel 25 and the return channel 24, respectively.

[0151] The first carrier fluid in the liquid state may flow from the condensation section 7 to the evaporation section 6 by gravity.

[0152] Upon entering the evaporation section 6, particularly the evaporation volume 6a, the first carrier fluid traverses the microchannels defined by the fin elements 11a on the first plate-like element, where the first carrier fluid extracts heat from the heating means 4.

[0153] Upon heating, the first carrier fluid evaporates and returns via the return channel 24 to reach the condensation section 7.

[0154] In the condensation section 7, particularly in the condensation volume 7a, the first carrier fluid traverses the microchannels defined by the fin elements 12a, gives off heat and returns to a substantially liquid state.

[0155] According to the present embodiment, the condensation section 7 includes a cover-like element 28 associated with the plate-like element 12 to define a second evaporation volume 7b configured to at least partially accommodate the fin elements 12b of the plate-like element 12, the second evaporation volume 7b being separated from the condensation volume 7a by the plate-like element 12. Within the second evaporation volume 7b, a second carrier fluid can be conveyed such that the latter can exchange heat with the fin elements 12b. In particular, the fin elements 12b heated by the first carrier fluid via the fin elements 12a give off heat to the second carrier fluid.

[0156] Server level

[0157] "Server level" refers to the heat exchange occurring at each server 2.

[0158] As described above, the system 1 includes a plurality of second circuits 8, each second circuit being configured to cut heat from the corresponding server 2 by means of the flow of a second heat-carrying fluid.

[0159] Preferably, the second carrier fluid can be selected from the following refrigerant fluids, the abbreviations of which refer to the international standard Nr.34 ASHRAE: R1234ze(E), R1233zd(E), R1234yf. These are particularly useful for thermal performance, saturation pressure and low global warming potential (GWP). Refrigerant fluids having properties similar to those of the above-mentioned fluids are not excluded.

[0160] For each server 2, there is a second circuit 8 thermally connected at the first thermosyphon circuit 5, which first thermosyphon circuit is in turn thermally connected at the heat-generating means 4 of the same server 2.

[0161] Generally, it is constructed such that the heat exchange and physical connection between the second thermosyphon circuit 8 and the main circuit 5 occur at the heat-generating means 4.

[0162] In the example now described, the heat exchange between the second thermosyphon circuit 8 and the first thermosyphon circuit 5 occurs at the first thermosyphon circuit itself and then at the heat-generating means 4.

[0163] Returning to Figure 1 、 Figure 2 Advantageously, the second thermosyphon circuit 8 includes connection means 13 configured to effect a thermal connection in series and / or in parallel with the corresponding first thermosyphon circuit 5.

[0164] Reference Figure 2 In the embodiment of Figure 2 , the connection means 13 includes a first supply pipe 13a adapted to convey a second carrier fluid into the first thermosyphon circuit 5, and a second supply pipe 13b adapted to convey the second carrier fluid out of the first thermosyphon circuit 5.

[0165] In Figure 2 In the embodiment of Figure 2 , the connection means 13 implements a thermal connection in parallel between the second thermosyphon circuit 8 and the first thermosyphon circuit 5.

[0166] Advantageously, the first supply pipe 13a branches off from a single conveying pipe 8a and enters the second evaporation section 7 of the first thermosyphon circuit 5.

[0167] Conversely, the second supply pipe 13b exits from the second evaporation section 7 of the first thermosyphon circuit 5 and is connected to a single return pipe 8b for exiting from the server 2.

[0168] This configuration allows the system 1 to transfer the second carrier fluid at the same temperature in each first thermosyphon circuit 5 existing in the server itself within a single defined server 2.

[0169] Alternative solutions are not excluded, in which the connection means 13 includes a first pipe 13a and a second pipe 13b connected in series.

[0170] In this case, the second pipe 13b of a defined first thermosyphon circuit 5 may coincide with the first pipe 13a of the first thermosyphon circuit 5 preceding it.

[0171] In a solution with a combination of series and parallel, the case of multiple first thermosyphon circuits 5 is also not excluded.

[0172] As previously referenced Figure 8A As described, a collecting element for the second working fluid may also be provided.

[0173] The above example refers to a server 2 having two heating means 4, but the same considerations can also be made even for embodiments in which the server 2 is provided with a different number of heating means 4, such as a four-CPU server.

[0174] In each case, since the cooling of the heating means 4 is directly performed at the "chip" level, advantageously by means of a plate-like element 11 acting as a microchannel heat exchanger, there is no need for a specific design of the inlet holes for the air flow, or for the optimization of the air flow pressure drop, or for the layout of the electronic components, and for the control logic of the fan speed. Thus, the system 1 results in a simple configuration even at the "server level".

[0175] Rack level

[0176] "Rack level" refers to the heat exchange that allows the heat generated by the heating means 4 to be removed from the rack 3.

[0177] Referring again to Figure 1 , as would be expected from the foregoing, the overall system configuration provides a second loop 8 connected in parallel such that the second carrier fluid successfully removes heat from each server 2 in parallel.

[0178] Preferably, the system 1 includes a condensation unit 14 connected to a delivery pipe 15 and a return pipe 16.

[0179] The condensation unit 14 is configured to remove heat from the second carrier fluid by cooling the second carrier fluid and returning it to a substantially liquid state.

[0180] Advantageously, the condensation unit is placed outside the rack 3, preferably above the rack, so as to supply the second loop 8 by gravity.

[0181] According to a possible embodiment, the condensation unit 14 can be of the shell-and-tube heat exchanger type, in which a third carrier fluid removes heat from the second carrier fluid. In this way, the entire heat load is taken outside the rack 3 and given to the third carrier fluid.

[0182] Different solutions are not excluded, for example where, depending on the heat load of the rack, overall dimensions or supply priorities, the condensation unit 14 is of the plate exchanger, microchannel exchanger type or another known type.

[0183] Advantageously, the third carrier fluid can be water, but other carrier fluids are not excluded, such as the air of the surrounding environment or other heat-carrying fluids.

[0184] Now the first embodiment of the cooling system 1 schematically shown in Figures 9 - 17 will be described.

[0185] According to this variant, the cooling system 1 allows both the physical principle of the thermosiphon and the physical principle of the pulsating heat pipe or also called "pulsating heat pipe" to be applied.

[0186] In a pulsating heat pipe, by utilizing the expansion force of the gas phase and the compression force of the liquid phase, the heat-carrying fluid in a two-phase (liquid and vapor) state is alternately heated and cooled in order to trigger an oscillatory motion therein. Thus, as in the principle of the thermosiphon, the pulsating heat pipe is implemented as a passive cooling system that does not require a pump, but different from the principle of the thermosiphon that requires a relatively small height extension, because its operation does not require gravity.

[0187] In the second embodiment, the principle of the pulsating heat pipe is applied at the "chip level", while at other levels ("server level" and "rack level"), the principle of the thermosiphon is applied, where the modes and characteristics are similar to those previously described in the first embodiment.

[0188] The second embodiment will be described hereinafter only with reference to the heat exchange referred to as the "chip level".

[0189] In particular, the first heat exchange circuit or main circuit, denoted by reference numeral 5, will be described. In this second embodiment, it is of the type of device configured to implement the physical principle of the pulsating heat pipe or also referred to as the "pulsating heat pipe". As described above, in a pulsating heat pipe, the heat-carrying fluid in a two-phase (liquid and vapor) state is alternately heated and cooled by utilizing the expansion force of the gas phase and the compression force of the liquid phase, so as to trigger an oscillatory motion therein. This device is implemented as a passive cooling system that does not require a pump and does not require a highly extended structure, since its operation does not require gravity.

[0190] Even in this case, the device also provides an evaporation section 6 and a condensation section 7, which are connected to each other to form a single integral component. No heat-bonding material or other elements are required to allow its removal.

[0191] The evaporation section and the condensation section are implemented as the above-described heat exchange regions.

[0192] Advantageously, each main circuit 5 includes an evaporation section 6 and a condensation section 7. This solution achieves the heat exchange efficiency between the second thermosiphon circuit 8 and the main circuit 5 by improving the cooling performance of the main circuit 5.

[0193] The system 1 provides a pulsating heat-based heat exchange circuit 5 for each heat-generating means 4. In the second embodiment ( Figure 9 and Figure 10 ), the pulsating heat-based heat exchange circuit 5 is constructed such that the first two-phase carrier fluid can be alternately heated and cooled, and then undergoes a phase change from liquid to vapor and vice versa. Then, within the pulsating heat-based heat exchange circuit 5, due to the effects of the expansion force and compression force generated by the vapor / liquid phase change, an oscillatory motion of the fluid is triggered.

[0194] Preferably, the first carrier fluid can be selected from the following refrigerant fluids, whose abbreviations refer to the international standard Nr.34 ASHRAE: R1234ze(E), R1233zd(E), R1234yf. These are particularly useful for thermal performance, saturation pressure, and low global warming potential (GWP). Refrigerant fluids having performance similar to those of the above fluids are not excluded.

[0195] Even in the second embodiment, the first of the heat exchange circuit 5 based on pulsating heat includes an evaporation section 6 placed in thermal contact with a corresponding heat generating means 4, and a condensation section 7 placed in thermal contact with one or more second thermosyphon circuits 8. In Figure 9 , the heat generating means 4 is not visible, but it is placed below the evaporation section 6. In this possible form of use, two devices 1 are associated with the second circuit 8 in which a second carrier fluid can flow to remove heat from the first carrier fluid. In particular, the two devices 1 are associated with the second circuit 8 by a parallel connection. Each device is associated with a first supply pipe 13a through which the second carrier fluid can enter, and each device is associated with a second supply pipe 13b through which the second carrier fluid can exit.

[0196] The evaporation section 6 and the condensation section 7 overlap each other to define the heat exchange circuit 5 based on pulsating heat or the heat exchange device based on pulsating heat.

[0197] Referring Figures 12 - 15 , advantageously, the heat exchange device based on pulsating heat includes a circulating means 50 for a first two-phase carrier fluid, which is adapted to exchange heat with one or more heat generating means 4.

[0198] The circulating means 50 is configured to allow the first carrier fluid to circulate from the evaporation section 6 to the condensation section 7 in a pulsating oscillating motion and vice versa.

[0199] Usefully, the circulating means 50 is associated with the evaporation section 6 and the condensation section 7 and is configured to allow the first carrier fluid to exchange heat.

[0200] In particular, the circulating means 50 includes a coil element through which the first carrier fluid can flow. The coil element 50 is constructed such that the capillary phenomenon acting on the circulating carrier fluid is stronger than gravity.

[0201] Usefully, the coil element 50 has successive extensions according to a curved path that extends alternately from the evaporation section 6 to the condensation section 7 and closes on itself.

[0202] This construction allows the first carrier fluid to circulate from the evaporation section 6 to the condensation section 7 in a pulsating oscillating motion and vice versa.

[0203] The coil element 50 includes a first part 50a located in the condensation section 6 and a second part 50b located in the evaporation section 7, and the first part 50a is placed in fluid communication with the second part 50b.

[0204] When the first fluid is in the first part 50a, it absorbs heat by means of the evaporation section 6 by cooling the heat-generating means 4. The absorbed heat causes a phase change of the first carrier fluid, which changes from a substantially liquid state to a substantially gaseous state. The expansion force generated by the state change pushes the first carrier fluid towards the corresponding second part 50b.

[0205] Vice versa, when the first fluid is in the second part 50b, it gives heat to the second carrier fluid by means of the condensation section 7. When giving heat, the first carrier fluid changes state, changing from a substantially gaseous state to a substantially liquid state. The compression force generated by the state change pushes the first carrier fluid towards the corresponding first part 50a.

[0206] By combining the expansion force and the compression force generated due to the state change of the fluid with the capillary action of the coil element 50, a pulsating oscillating motion of the first fluid within the coil element 50 itself is obtained, so that there is no need to use a pump or other moving elements. Due to the pulsating oscillating motion of the first carrier fluid, heat is cut from the heat-generating means 4 and transferred to an external system, for example, transferred to the second carrier fluid.

[0207] Advantageously, the coil element 50 may have a circular, or square, or rectangular cross-section, but other compatible shapes such as oval, egg-shaped, trapezoidal, etc. are not excluded.

[0208] The equivalent diameter of the cross-section of the coil element 50 must be small enough to limit the vapor bubbles of the two-phase fluid, that is, to prevent the stratification of the liquid in the lower part of the channel and the vapor in the upper part.

[0209] Here, it is emphasized that under the "equivalent diameter" of the cross-section of the coil element 50, it should be understood as the diameter of an assumed circular cross-section having the same geometric shape, hydrodynamic, optical, and electrical characteristics with the same cross-section.

[0210] To determine the size of the coil channel, a dimensionless number called the "Bond number" or "Confinement number" can be referred to: the diameter of the coil channel must be less than or equal to the size obtained from the above dimensionless number.

[0211] Usefully, by referring to the above refrigerant fluid, the equivalent diameter of the cross-section of the coil element 50 can be less than 2 mm.

[0212] Advantageously, the equivalent diameter of the cross-section of the coil element 50 can be between 0.5 mm and 1 mm. In fact, these are the optimal values for the compromise between efficiency and production cost.

[0213] The coil element 50 may have a cross-section with a constant equivalent diameter along its entire curved path. Alternative solutions are not excluded, where the coil element 50 may have a narrowing or widening of the cross-section along the curved path, and the equivalent diameter can vary from one cross-section to another.

[0214] Advantageously, the coil element 50 can be implemented by winding a capillary tube a determined number of times, or by milling and extruding one or more channels from an initial element, such as a plate or block made of copper or aluminum, using a numerically controlled machine tool.

[0215] Preferably, the evaporation section 6 may include a first plate-like element 44 configured to be placed in contact with the corresponding heating means 4.

[0216] In the first plate-like element 44, a portion 50a of the coil element 50 is obtained. In this way, the first carrier fluid can extract heat from the heating means 4.

[0217] The first plate-like element 44 thus has the function of cooling the heating means 4, for which it can be referred to as a "cold plate".

[0218] The horizontal cross-section of the plate-like element 44 is shown in Figure 13 In.

[0219] Advantageously, the thermal contact between the first plate-like element 44 and the heating means 4 can be implemented by means of a thermal paste or other thermal interface material (TIM). The thermal paste can be interposed between the cold plate 44 and the heating means 4 and is suitable for promoting heat exchange between the two of them.

[0220] Advantageously, a thermal paste with a thermal conductivity equal to or higher than 12.5 W / mK can be used.

[0221] Advantageously, the condensation section 7 may include a second plate-like element 45 configured such that the first carrier fluid can give up heat. In particular, the second plate-like element 45 is configured to allow heat exchange between the first carrier fluid and a system thermally coupled to the device, for example, heat exchange between the first carrier fluid and a second carrier fluid without bringing them into direct contact. In Figure 15 And Figure 16 The horizontal cross-section of the second plate-like element 45 is preferably shown.

[0222] A portion 50b of the coil element 50 is obtained in the second plate-like element 45.

[0223] Referring to Figure 16 , the second plate-like element 45 preferably may include a circulation area 47 in which a second carrier fluid can circulate, such as the second carrier fluid of a circuit thermally coupled to the device.

[0224] The circulation region 47 may include at least two distribution regions 47a, 47b configured to distribute the second fluid into / from the condensation section 7, respectively.

[0225] The distribution regions 47a, 47b may be in fluid communication with the first supply pipe 13a and the second supply pipe 13b, respectively. The latter may be, for example, part of a circuit outside the device, and the second carrier fluid may circulate therein.

[0226] Returning to Figure 12 the embodiment shown, the condensation section 7 may also include a closing plate 48 placed to close the plate-like element 45. A replaceable solution in which the closing plate 48 and the plate-like element 45 are implemented as a single piece is not excluded.

[0227] The structure of the heat exchange device based on pulsating heat may include additional heat exchange means, such as fin elements 51 obtained in the condensation section 7, which may cut heat from the first carrier fluid by heating. Thus, if traversed by the colder second carrier fluid, they may give heat to the second carrier fluid by acting as an exchange surface.

[0228] Advantageously, the fin elements 51 may define a circulation channel, or also called a microchannel, configured to be traversed by the second carrier fluid.

[0229] In particular, the heat exchange means may include fin elements 51 obtained on at least one of the plate-like element 45 and the closing plate 48.

[0230] Preferably, the fin elements 51 may be arranged in the circulation region 47, between the distribution regions 47a and 47b, to define a circulation channel, or also called a microchannel, in fluid communication with the distribution regions themselves. The second carrier fluid may circulate from the distribution region 47a to the distribution region 47b, passing through the channel defined by the fin elements 51, and thereby cut heat from the first carrier fluid, particularly from the first carrier fluid present in section 50b.

[0231] The microchannel may be designed such that the heat transfer coefficient and pressure drop of the carrier fluid are optimized and the occurrence of stagnant bubbles is avoided. Advantageously, for the process of manufacturing the microchannel, a milling and cutting process using a numerically controlled machine tool from an initial element may be provided.

[0232] Advantageously, the heat exchange device based on pulsating heat may include an additional plate-like element 46, also called an "insulating plate". In Figure 14 it, a horizontal cross-sectional view of the insulating plate 46 is shown.

[0233] The insulating plate 46 is configured to fluidly connect the evaporation section 6 to the condensation section 7.

[0234] Advantageously, the insulating plate 46, the evaporation section 6 and the condensation section 7 are joined and overlapped with each other to define a compact body. In particular, as Figure 11 and Figure 12 shown, the plate-like element 44, the insulating plate 46, the plate-like element 45 and the closing plate 48 are joined to define a compact body. This brings structural advantages as the device is more durable and long-lasting, and even functional advantages as the space required to accommodate the device is reduced and there is no need for a high extension.

[0235] Preferably, the plate-like elements 44, 45 and the insulating plate 46 can be made of copper as copper has a high thermal conductivity, but solutions in which they are made of aluminum or other heat-conducting materials are not excluded. Replaceable solutions are not excluded, such as where the entire device is made of aluminum.

[0236] The third part 50c of the coil element 50 is inserted into the insulating plate 46. Each part 50c is interposed between the corresponding first part 50a and the corresponding second part 50b and is placed in fluid communication therewith.

[0237] In particular, with reference to Figure 17 , in particular with reference to the operating principle of controlling the circulation of the first heat-carrying fluid, a schematic view of a part of the heat exchange device 5 based on pulsating heat is shown.

[0238] Specifically, the circulation means 50 is shown as a structure passing through the overlapping part of the evaporation section 6 and the condensation section 7, and in this embodiment in more detail, where the insulating plate 46 intervenes between the plate-like elements 44, 45.

[0239] It should be noted that the first part 50a of the circulation means 50, i.e., the part associated with the evaporation section 6, includes a coil in which the vapor bubbles B of the first carrier fluid are trapped.

[0240] The heating component 4 is in contact with the evaporation section 6, and the bubbles B expand due to the heat received during heat exchange with it.

[0241] Preferably, the first part 50a of the circulation means 50 includes a pipe system obtained in the evaporation section 6, particularly in the plate-like element 46. In the embodiment described here, the pipe system is closed at the top by the insulating plate 46.

[0242] Thus, the bubbles B are confined between the side walls of the coil 50a, and their expansion generates a push in the axial extension direction of the pipe system constituting the coil itself, tending to push the first carrier fluid (which is a liquid phase of a gas phase) contained therein.

[0243] Then, the bubbles B are forced to flow axially along the coil 50a until they find an outlet produced by the part 50c of the insulating plate 46.

[0244] Said part 50c preferably includes a plurality of openings which are distributed in the overlapping region S of the first part 50a of the circulation means 50 of the condensation part 7 and the corresponding second part 50b.

[0245] This part 50c advantageously allows the first working fluid to be transferred from the evaporation part 6 to the condensation part 7 on top.

[0246] Advantageously, as can be understood from Figure 13 , Figures 15 - 17 the pipe system 50a of the evaporation part 6 extends in a certain plane, and the pipe system 50b of the condensation part 7 extends in a parallel plane arranged above this plane.

[0247] In particular, referring to Figure 17 , the pipe system 50a and the pipe system 50b are interlaced with each other, so that the third part 50c can fluidly connect at least one pipe system 50b of the condensation part 7 with two different pipe systems 50a, 50a' of the evaporation part 6 at the overlapping region S.

[0248] In this way, the vapor of the first carrier fluid re-condensed in the pipe system 50b of the condensation part 7 can fall into the opening 50c again, and this opening is connected to a different second pipe system 50a' of the evaporation part 6 relative to the first pipe system 50a it has reached.

[0249] Then, it should be understood that the circulation means 50 of the evaporation part 6 and the condensation part 7 are placed in series and alternately with each other, and actually implement a single capillary in a structure with overlapping plates.

[0250] Advantageously, the said solution with plate-like elements implements the main circuit 5 through a pulsating heat-based heat exchange device which is much more compact than the known solutions of the capillary type.

[0251] In this sense, this solution can further be provided as a radiator for very high-power electronic devices or devices with multiple electronic units or devices with even very different powers from each other.

[0252] Furthermore, the structure with overlapping plate-like elements allows the implementation of the main circuit 5 with a pipe system of variable width during the planning, so as to optimize the heat exchange. In this way, it can be ensured that the fluid has a preferred directionality, so that the heat exchange can be carried out more effectively.

[0253] By making this solution particularly suitable for the implementation of a plurality of heat-generating components 4 with a dispersed distribution, pipe systems with different lengths can also be obtained in the same plate-like element.

[0254] Furthermore, in addition to the thickness and length of the circulation means 50, the number and arrangement of the openings 50c in the insulating plate 46 can be advantageously acted upon, providing greater flexibility during the planning phase with respect to heat exchange devices based on pulsating heat with known types of capillaries.

[0255] According to an advantageous embodiment, that is, the available number and arrangement of the openings 50c can be determined according to the type of application.

[0256] Generally, for medium to low power consumption, a larger number of openings 50c is preferred, with the openings being implemented with a wide distribution on the insulating plate 46. In fact, for these powers, the vapor bubbles B are shorter but more numerous, so they must reach the condensation section 7 as quickly as possible.

[0257] Differently, for high power, the openings 50c are preferably implemented concentrated at the ends of the pipe systems 50a, 50b, for example concentrated in a "U" - shaped path in their own axial extension direction, in order to obtain the maximum expansion push.

[0258] Furthermore, the different extension geometries of the circulation means 50 can be set relative to Figure 13 、 Figures 15 - 17 those shown in

[0259] Advantageously, by implementing suitable guiding paths, such as annular or petal - shaped paths, in the corresponding plates, the presence of the insulating plate 46 and the openings 50c carried by it allows the pipe systems 50a, 50a' of the evaporation section 6 to be fluidly connected to multiple pipe systems 50b (for example, four or more different pipe systems) of the condensation section 7.

[0260] In addition, other embodiments are not excluded in which the pulsating heat pipe has a shape different from the above - mentioned pulsating heat pipes, for example of the tubular type.

[0261] A cooling method for electronic heating means can provide heat exchange between the heating means and a first two - phase carrier fluid having a pulsating oscillatory motion. In particular, the heat exchange can occur through the device as previously described.

[0262] This device is particularly useful for cooling the heating means present in a server 1U, because they have a reduced height compared to servers 2U, 4U or other new - type servers, and the second embodiment can be adapted to different shapes and different orientations.

[0263] The advantages associated with this second embodiment involve that the two-phase flow can take different paths through the holes of the adiabatic plate 46. The holes define different lengths in the evaporation section 6 and the condensation section 7, such that the fluid selects the best hole through which it can flow according to the flow resistance and the heat load. Additionally, by adding multiple pulsation modes to the flow, the paths defined by the coil elements 50 in the evaporation section 6 and the condensation section 7 define a U-shaped inversion for the pulsation movement.

[0264] Furthermore, the second embodiment of the system 1 is compatible with the previously described device 20.

[0265] The first and second embodiments as previously described can be used in combination with each other, for example, in the case where the rack has different types of servers (1U, 2U, etc.). In this case, the user can apply the cooling system by selecting the solution that best suits the configuration of the rack to be cooled, where both the first heat-siphon loop (miniature heat-siphon) as described in the first embodiment and the second heat-siphon loop (pulsating heat pipe) as described in the second embodiment are present.

[0266] Additional features of cooling system 1

[0267] Advantageously, the system 1 can include connector means configured to effect and / or interrupt the physical and / or thermal coupling between the second heat-siphon loop 8 and the single delivery pipe 15 and / or the single return pipe 16.

[0268] The connector means can be a quick-install connector between the second heat-siphon loop and the delivery pipe 15 or the return pipe 16. Such a connector allows for easy connection / disconnection of the second loop to / from the rest of the architecture without interrupting the fluid circulation in the other second loops 8.

[0269] This feature is particularly useful in the case where maintenance or replacement of the server 2 is required, as it allows for disconnection of the server and the associated loop without interrupting the fluid circulation in the remaining loops.

[0270] The connector is configured to interrupt the flow line such that in the case where it is necessary to remove the server from the rack, the fluid does not flow in the evaporator of the second heat-siphon loop 8. For this reason, flow bypass can be avoided. Flow bypass generally must be avoided to prevent instability of the flow itself, which is a common problem in loops with traditional heat-siphons and in heat-siphons with a bypass between the liquid main line and the vapor main line.

[0271] Advantageously, the quick - mounting connector can be composed of a male body and a female body, which are not shown in the figures. The male body and the female body allow fluid transport when they are coupled. Both the male body and the female body can be equipped with spring means configured to close the corresponding circuit portions when the two bodies are disconnected. Thus, in both positions, the working fluid does not disperse into the environment.

[0272] Alternative solutions are not excluded where the connector has a different construction or where the connector means are known from the prior art but are different from the above - mentioned connector.

[0273] Reference Figure 8 , advantageously, the system 1 can include phase - separation means 17, 18 configured to separate the gaseous portion of the second heat - carrying fluid entering the return duct 16 from the substantially liquid portion of the same second carrier fluid.

[0274] In this way, the gaseous and liquid portions can be controlled, with the aim of optimizing the heat - exchange yield without causing a pressure drop that could lead to malfunctions. In this regard, it should be noted that

[0275] - The fact that the liquid - vapor mixture flows within the return duct 16 can cause a significant pressure drop in the return duct itself, thus reducing the mass range of the carrier fluid. In fact, the liquid phase in the return duct 16 reduces the density difference between the fluid in the return duct 16 and the fluid in the delivery duct 15, and it has a higher viscosity than the gaseous phase.

[0276] - To avoid premature drying of the two - phase flow within the connection means 13, it is preferable to have a low - quality vapor at the outlet of the same second circuit. In fact, the fact that the fluid is partially liquefied until it exits the connection means 13 allows for higher values of the heat - transfer coefficient.

[0277] According to Figure 8 the preferably - illustrated embodiment, the phase - separation means 17, 18 include a separation drum 17 that is in fluid communication between the return duct 16 and the second thermosyphon circuit 8.

[0278] The separation drum 17 is in communication with the return duct 16 at the top. The diameter of the cross - section of the separation drum 17 can be greater than the diameter of the cross - section of the second thermosyphon circuit 8. In this way, the second carrier fluid entering the separation drum 17 is subject to a pressure drop that allows the gaseous portion to continue upward in the return duct 16 while the liquid portion descends to the bottom of the drum itself.

[0279] The phase - separation means 17, 18 can also include a recirculation duct 18 that is in communication with the separation drum 17 and the delivery duct 15. The recirculation duct is configured to transfer the liquid portion into the delivery duct 15.

[0280] Advantageously, the recirculation pipe 18 is connected to the separation drum tank 17 at the bottom thereof, and extends by sloping downwardly towards the delivery pipe 15.

[0281] In this way, the liquid portion accumulating at the bottom of the separation drum tank 17 can be transferred by gravity into the delivery pipe 15 and reused.

[0282] The present invention also provides a cooling device 20 for a data center having a plurality of racks 3. Figure 7 An embodiment of the device 20 is schematically shown in

[0283] As previously mentioned, for each rack 3, the device 20 may include one or more systems 1. Referring to Figure 7 , the device 20 includes four systems 1, each of which is in turn associated with a respective rack 3. Devices 20 including a different number of systems 1 are not excluded.

[0284] Advantageously, the device 20 includes at least one third cooling circuit 21 thermally coupled to the systems 1 and configured to allow circulation of a third heat-carrying fluid.

[0285] The third carrier fluid is adapted to exchange heat with the second heat-carrying fluid circulating in each of the systems 1. Thus, by cooling the racks 3, the third carrier fluid can extract heat from the second carrier fluid.

[0286] Advantageously, the third circuit 21 may be provided with a delivery side 21a and a return side 21b in communication with the condensation units 14 of each system 1.

[0287] In particular, the third carrier fluid is transferred through the delivery side 21a into each of the condensation units 14. Here, the third fluid is heated by extracting heat from the second carrier fluid, and it is transferred through the return side 21b and exits the condensation units 14.

[0288] Referring to Figure 7 , the delivery side 21a is supplied in parallel, but solutions providing a series or series-parallel hybrid energy supply between the same delivery sides are not excluded.

[0289] Even the return side 21b is supplied in parallel, but solutions providing a series or series-parallel hybrid energy supply between the same return sides are not excluded.

[0290] Advantageously, the device 20 may include at least one cooling unit 22 associated with the third circuit 21 and configured to extract heat from the third carrier fluid by cooling it.

[0291] Preferably, the cooling unit 22 can be of the type of a refrigeration unit or a cryogenic cooler. By increasing the COP, the cryogenic cooler can operate at a higher evaporation temperature than a conventional cooling system. The increase in the evaporation temperature can eliminate the need for an expensive cooling tower, which requires a large amount of maintenance.

[0292] Alternative embodiments in which the cooling unit 22 is absent are not excluded. For example, the heat-carrying fluid that exchanges heat with the second thermosyphon loop 8 can dissipate heat directly into the air outside the data center using finned batteries. Alternatively, since the heat-carrying fluid can operate at a temperature between 40°C and 60°C, the heat-carrying fluid can be used for other purposes, such as heating the environment or generating electrical energy.

[0293] Thus, due to the system 1, the device 20 is easy to construct and easy to maintain.

[0294] Furthermore, if appropriately configured, the device 20 allows the principle of the thermosyphon to be extended even to the third loop 21.

[0295] In this case, the third carrier fluid can be of the type of a heat-carrying fluid similar to the first fluid and the second fluid described previously, and the movement within the third loop 21 will be provided by the phase change required at each system 1.

[0296] So far, the present invention has been described with reference to the preferred embodiments. This means that there can be other embodiments belonging to the same inventive core, which is defined by the scope of protection of the claims reported below.

Claims

1. A cooling system for a data center, the data center including a plurality of servers associated to form a rack, each server being provided with heating means, the system comprising: - A main circuit for each server, the main circuit configured to allow circulation of a first heat-carrying fluid adapted to exchange heat with the heating means, wherein the main circuit includes a heat exchange area coupled to the heating means, - A plurality of second thermosyphon circuits, each second thermosyphon circuit associated with a respective one of the plurality of servers and coupled to the corresponding main circuit at the heat exchange area, the plurality of second thermosyphon circuits configured to allow circulation of a second heat-carrying fluid adapted to exchange heat with the first heat-carrying fluid, The overall configuration of the system being such that the plurality of second thermosyphon circuits are fluidly connected to each other according to a parallel connection, wherein each main circuit includes means including an evaporation section and a condensation section placed in thermal contact with the heating means, the condensation section overlapping the evaporation section and placed in thermal contact with a respective one of the plurality of second thermosyphon circuits.

2. The cooling system according to claim 1, wherein, The plurality of second thermosyphon circuits are connected to each other by a single delivery pipe and a single return pipe.

3. The system according to claim 1 or 2, wherein, The means includes heat exchange means associated with the evaporation section and the condensation section, the heat exchange means configured to allow heat exchange of the first heat-carrying fluid.

4. The system according to claim 3, wherein, The heat exchange means includes a plurality of fin elements defining through-channels for the first heat-carrying fluid and / or the second heat-carrying fluid.

5. The system according to claim 1 or 2, wherein The main circuit includes a thermosyphon circuit.

6. The system according to claim 1 or 2, wherein The main circuit includes a heat exchange device based on pulsating heat.

7. The system according to claim 6, wherein the heat exchange device based on pulsating heat includes an evaporation section and a condensation section, the evaporation section and the condensation section being coupled to each other and overlapping to form a single unitary body.

8. The system according to claim 7, wherein, The heat exchange device based on pulsating heat includes a coil element through which the first heat-carrying fluid flows, the coil element being obtained in the evaporation section and the condensation section.

9. The system according to claim 8, wherein the coil element includes a first portion positioned at the condensation section and a second portion positioned at the evaporation section, the first portion and the second portion being placed in fluid communication with each other.

10. The system according to claim 8, wherein the coil element has a cross-section with an equivalent diameter less than 2 mm.

11. The system according to claim 10, wherein the coil element has a cross-section with an equivalent diameter between 0.5 mm and 1 mm.

12. The system according to claim 9, including a heat insulating plate between the evaporation section and the condensation section.

13. The system according to claim 12, wherein, The heat insulating plate includes a plurality of openings distributed in an overlapping area of the first portion and the corresponding second portion.

14. The system according to claim 1 or 2, wherein, The plurality of second thermosyphon circuits include connection means configured to effect a series and / or parallel thermal connection with the corresponding main circuit.

15. The system according to claim 2, further including at least one recirculation pipe configured to effect fluid communication between the single delivery pipe and the single return pipe.

16. The system according to claim 2, further comprising connector means configured to effect and / or interrupt a physical and / or thermal coupling between the plurality of second thermosyphon loops and the single delivery conduit and / or the single return conduit.

17. A cooling device for a data center having a plurality of server racks, the device comprising: - a cooling system according to any one of claims 1 to 16 for each of the plurality of server racks; - at least one third cooling loop thermally coupled to the cooling system and configured to allow circulation of a third heat transfer fluid adapted to exchange heat with the second heat transfer fluid.

18. The device according to claim 17, comprising at least one cooling unit associated with the third cooling loop and configured to remove heat from the third heat transfer fluid.

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