JP7635498B2 - Electronic equipment cooling system - Google Patents

Description

The present invention relates to a liquid immersion cooling method for cooling electronic devices using a liquid refrigerant, typically a synthetic oil or a fluorocarbon-based refrigerant, which has better heat transfer performance than gases such as air, among cooling methods for data centers and edge servers that house and operate electronic devices in housings, and to a liquid immersion cooling apparatus to which this method is applied.

As society becomes increasingly digitalized, information from a variety of fields is digitized and processed, and data centers are being built and operated all over the world, and their popularity continues to grow. However, when data centers constantly process large amounts of data, they consume a large amount of electricity to operate and cool the servers, and this electricity consumption results in a large amount of carbon dioxide emissions, so there is a demand for reducing the cooling energy used at data centers and for greening them by using renewable energy.

In addition, with the spread of 5G communication networks and the like, edge computing is expected to become more widespread. This will enable data to be produced and consumed locally by performing high-speed calculations on data generated in locations or nearby areas where large amounts of data are generated, and returning processed and output data at high speed. By distributing edge servers that run on electricity and heat from renewable energy sources to various locations, it will be possible to expand the use of green edge computing, which will enable the local production and consumption of data through the local production and consumption of renewable energy.

Specific examples of this type of green edge computing include setting up wind power plants in windy coastal areas or offshore, and installing servers and information and communications equipment nearby; setting up run-of-river hydroelectric power plants on fast-flowing rivers in mountainous areas, and installing servers and information and communications equipment nearby; and setting up geothermal power generation facilities or hot spring heat binary power generation facilities in geothermal or hot spring areas, along with absorption or adsorption chillers that convert and supply cold energy using hot spring heat, and running servers and information and communications equipment with the green electricity and green cold energy obtained from these.

However, when considering cooling for the above-mentioned on-site data centers or edge servers, there is a risk that the surrounding environment and season of the installation location can cause performance degradation or failure of the electronic devices that make up the server, reducing their durability and accelerating their deterioration.

In other words, when taking in outside air from the coast or ocean to cool servers or information and communications equipment, the salt and excessive moisture in the air can deteriorate the components of the servers and communications equipment, and when taking in outside air near a river, there is a risk of condensation shorts due to the moisture in the air. In addition, when taking in outside air from geothermal or hot spring areas, there is a risk that geothermal-derived gas components such as hydrogen sulfide can deteriorate the components of the servers and communications equipment.

Furthermore, regardless of the installation location, it is difficult to use the outside air to sufficiently cool the electronic devices during times when the outside temperature is high, such as during the daytime in spring and autumn, or in summer. Unless the electronic devices can be constantly and stably cooled by operating large-scale ventilation and cooling equipment that consumes a great deal of energy, there is a risk that the electronic devices will deteriorate, suffer performance degradation or malfunction due to high temperatures.

In response to these challenges, immersion cooling technology is being developed, which cools electronic devices using liquid refrigerants such as synthetic oils and fluorocarbon-based refrigerants, which have better heat transfer properties than gases such as air.This technology does not cool electronic devices by taking in outside air from the data center or edge server, but instead absorbs heat and cools via a liquid refrigerant, making it possible to cool electronic devices efficiently without being affected by chemicals, dust, excessive moisture, etc. contained in the outside air.

Known examples of this immersion cooling technology include a technology for efficiently cooling electronic devices that are packaged at high density and are compatible with immersion cooling (Patent Document 1), a technology for reducing the amount of refrigerant used in an immersion cooling device (Patent Document 2), a technology for using a low-boiling point fluorine-based insulating refrigerant and efficiently cooling electronic devices by boiling cooling using this refrigerant (Patent Document 3), and a technology for eliminating stagnation in the condenser section of a boiling cooling device to improve condensation performance (Patent Document 4).

Patent No. 6644908 JP 2020-136335 A Patent Application No. 2022-30744 Patent Application No. 2010-16049

According to the conventional technology disclosed in the above-mentioned Patent Documents, even in a data processing server such as a supercomputer in which high-performance electronic devices that generate a large amount of heat are densely mounted, it is possible to efficiently cool the electronic devices by using either a liquid immersion cooling technology, which is a single-phase liquid immersion cooling method using synthetic oil or the like, or a boiling cooling type two-phase cooling method using a low-boiling point refrigerant. However, these technologies have the following five problems.

First, in all of the conventional technologies shown in Patent Documents 1 to 3, when cooling and circulating the high-temperature refrigerant that absorbs heat from the electronic devices, an external cooling device that circulates and cools another refrigerant such as cooling water using a pump, or an auxiliary device for cooling the refrigerant, such as a dry cooler, that has a fan that forcibly dissipates heat into the outside air, is required. Such ancillary devices not only make the entire system larger, increasing initial investment costs, but also increase operating costs due to the power consumption required to run the pumps and fans during operation, and when the power supplied for operation is generated by thermal power generation, there is an issue of increased carbon dioxide emissions due to power consumption.

Furthermore, when the power to operate the pumps and fans is received from the power grid, if the power grid experiences a long-term power outage due to a natural disaster or the like and the power supply from emergency power generators cannot be continued due to a cut in the fuel supply, or if the power supply is cut off due to the discharge limit of the power storage equipment attached to the edge server, there is a problem that the immersion cooling device cannot be operated to cool the electronic devices, and therefore operation cannot be continued during a long-term power outage.

Furthermore, when the immersion cooling refrigerant and cooling water, etc. are cooled through a heat exchanger, if the heat exchanger is stained with scale and its heat exchange performance is reduced, the power consumption of the above-mentioned ancillary equipment will increase. In addition, if the heat exchanger is perforated due to corrosion, deterioration, etc., there is a risk that different types of refrigerants will mix and cause a malfunction in the entire immersion cooling system. Furthermore, if any of the pumps or fans that circulate the immersion cooling refrigerant and the cooling water, etc., breaks down, the entire cooling system will break down and stop, and it will be impossible to continue operating the electronic devices.

Furthermore, among the conventional techniques shown in Patent Document 4, a method in which refrigerant condensation cooling is not performed using cooling water or the like, but a heat exchanger having a plurality of fins is installed on the outer wall surface of the liquid refrigerant storage section to condense and liquefy the refrigerant solves the above-mentioned problems associated with the external cooling water circulation supply. However, the boiling vapor guide pipe arranged around the heating element is not made of a heat insulating material, and the condensed and liquefied low-temperature refrigerant flows down to near the liquid surface of the liquid refrigerant storage section, and then gradually reaches the guide pipe inlet on the bottom side of the heating element in the liquid refrigerant tank. As a result, the refrigerant that has been cooled via the heat exchanger on the outer wall surface is not directly supplied to the guide pipe inlet near the heating element, and therefore circulatory cooling by convection of the liquid refrigerant is not promoted, resulting in a problem of reduced cooling efficiency.

Furthermore, when considering that this technology is applied to outdoor data centers or edge servers where there is a risk of lightning strikes, it is expected that the high-voltage current from the lightning strike will directly hit the heat exchange fins that protrude from the outer wall of the liquid refrigerant storage unit. However, since the heat exchanger and liquid refrigerant storage unit are not earthed in this case, there is an issue that the high-voltage current from the lightning strike will propagate into the liquid refrigerant storage unit, causing insulation breakdown in the liquid refrigerant, increasing the risk of damaging electronic devices inside the refrigerant.

The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a method for simply and efficiently immersion cooling electronic devices while reducing the risk of damage to the electronic devices in the event of a lightning strike by utilizing outside air or renewable energy, and a liquid immersion cooling device for electronic devices etc. to which the present technology is applied.

The invention described in claim 1 is
The device comprises: an insulating liquid refrigerant storage tank having openings on a part or all of a top surface and a bottom surface, housing an electronic device and storing a liquid refrigerant for cooling the electronic device; an outer tank that houses the liquid refrigerant storage tank and forms a heat dissipation cooling flow path for the liquid refrigerant on at least a part of the outer periphery of the liquid refrigerant storage tank; a heat dissipation cooling means that dissipates heat and cools the liquid refrigerant so that the temperature of the liquid refrigerant is lowest at the bottom surface of the liquid refrigerant storage tank when the liquid refrigerant flows down toward the bottom surface of the liquid refrigerant storage tank; and a water storage tank that is provided above the top surface of the outer tank and capable of storing rainwater. the cooling means has a heat absorption portion disposed within the heat dissipation cooling flow path, and a heat dissipation portion protruding from a top surface of the outer tank and disposed in water stored in the water tank, the liquid refrigerant inside the liquid refrigerant storage tank is heated and vaporized due to heat generated by the electronic device and discharged to the outside of the liquid refrigerant storage tank from the opening in the top surface, and is cooled and condensed into a liquid as it flows down the heat dissipation cooling flow path and is stored in a bottom portion of the outer tank, and the liquid refrigerant stored in the bottom portion of the outer tank flows into the liquid refrigerant storage tank from the opening in the bottom surface of the liquid refrigerant storage tank, thereby circulating the liquid refrigerant by natural convection.
In a second aspect of the present invention, the heat dissipation/cooling means is a heat pipe that absorbs heat from the liquid refrigerant in the heat dissipation/cooling passage and dissipates the heat to the outside of the outer tank.
The invention described in claim 3 is characterized in that the water storage tank receives rainfall and stores the received rainwater inside .

According to the present invention, in liquid immersion cooling, which can efficiently cool electronic devices, the refrigerant cooling device for cooling the liquid refrigerant can be eliminated or made smaller and simpler, reducing initial investment costs, and the operating power of pumps and fans involved in cooling the liquid refrigerant can be significantly reduced, thereby reducing costs and carbon dioxide emissions associated with this power consumption.

In addition, natural convection-type refrigerant circulation cooling, which uses outside air or renewable energy heat to cool the liquid refrigerant, makes it possible to reduce or downsize pumps and fans and significantly shorten the operating hours of these devices. Therefore, even if the power grid experiences a prolonged power outage, long-term operation of liquid immersion cooling is possible through independent liquid refrigerant circulation cooling using renewable energy, and the excess power can be used to operate the electronic devices, making it possible to extend the operation of the electronic device system.

Furthermore, if a failure occurs in either the pump or the fan that circulates the immersion cooling refrigerant or the refrigerant-cooling medium such as cooling water, it is possible to reduce both the risk that the entire cooling system will fail and stop, making it impossible for the electronic devices to continue operating, and the risk that different types of refrigerants, such as the immersion cooling refrigerant and cooling water, will mix and cause a malfunction in the entire immersion cooling system.

In addition, in immersion cooling of electronic devices, liquid refrigerant that has been cooled by using outside air or renewable energy heat can be efficiently supplied from the bottom of a liquid refrigerant storage tank in which the electronic devices are housed, thereby achieving circulatory cooling that promotes natural convection of the liquid refrigerant, making it possible to achieve highly efficient liquid immersion cooling and also reducing the risk of damage to electronic devices in the event of a lightning strike.

1 is a cross-sectional view of a liquid immersion cooling device that uses a low-boiling point refrigerant for boiling cooling, according to a first embodiment of the present invention. FIG. 1 is a cross-sectional view of a second embodiment of an immersion cooling device according to the present invention, which uses a synthetic oil refrigerant for single-phase immersion cooling. FIG. 11 is a cross-sectional view of an immersion cooling device that uses a low-boiling point refrigerant for boiling cooling, according to a third embodiment of the present invention.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. Note that the scope of the present invention is defined by the claims, and is not limited to the present embodiment.

First Embodiment

First, an immersion cooling apparatus using a low-boiling point refrigerant for boiling cooling according to a first embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 1 , this liquid immersion cooling device 1 is composed of an insulating liquid refrigerant storage inner tank 3 in which a low-boiling point insulating liquid refrigerant 2 for immersion cooling is stored, which can efficiently cool various electronic devices that generate heat when powered through the liquid refrigerant storage inner tank by boiling cooling, and a liquid refrigerant storage outer tank 6 in which the condensed and liquefied liquid refrigerant dissipates heat to the outside air along the outside of the insulating wall of the liquid refrigerant storage inner tank without receiving heat from the electronic devices in the inner tank or from the high-temperature vaporized refrigerant in the tank, and which forms a heat dissipation cooling flow path 4 for the liquid refrigerant that flows down while being cooled, and which seals and stores the flowing-down liquid refrigerant while allowing it to flow in from a bottom opening 5 of the liquid refrigerant storage inner tank 3.

Here, a number of highly thermally conductive heat dissipating fins 7 are fixed to the outer wall of the heat dissipating cooling flow path 4 of the liquid refrigerant storage outer tank 6 from near the vertically downward center of these flow paths toward the bottom of the liquid refrigerant storage outer tank 6 so that the heat dissipating area expands toward the bottom of the outer tank. As the condensed and liquefied liquid refrigerant flows down the heat dissipating cooling flow path 4, it dissipates heat to the outside air to lower its temperature, increases its density and promotes its downward flow, while further dissipating heat to the outside air to cool it, and when the temperature is at its lowest and density is at its highest at the bottom of the outer tank, it flows from the bottom opening 5 into the liquid refrigerant storage inner tank 3 in which electronic devices that require cooling are housed.

A sealed fixed lid 9 having a plurality of highly thermally conductive heat dissipation fins 8 fixed thereto for condensing and liquefying the evaporated liquid refrigerant while covering and sealing the top surface of the outer tank 6 is sealed and fixed to the outer wall of the outer tank 6. A power cable connection port 10 for supplying power to electronic devices and an antenna 11 for data communication are also sealed and fixed to the top surface of the fixed lid 9.

The fixed lid 9 is sealed and fixed so that the inner wall of the lid coincides with the surface of the outer wall of the heat dissipation cooling flow path 4, and an insulating condensed refrigerant flow down plate 12 is fixed inside the lid. The refrigerant flow down surface of this refrigerant flow down plate on the bottom side of the lid is connected to the inner wall of the heat dissipation cooling flow path 4 so as to form the same surface. On the other hand, an opening is formed on the top side of the lid. When the refrigerant vapor generated from the liquid refrigerant storage inner tank 3 flows from the opening along the inner wall of the fixed lid and is condensed and liquefied and flows down, it flows down in liquid form to the heat dissipation cooling flow path 4 without being heated by heat from the refrigerant vapor filling the lower part of the condensed refrigerant flow down plate 12, forming a condensation cooling flow path 13.

With this configuration, when the electronic device housed in the liquid refrigerant storage inner tank 3 is operating and the liquid refrigerant in the storage tank inner tank boils and vaporizes to become refrigerant vapor and rises, in the process of passing through the condensation cooling flow path 13 formed in the fixed lid, the refrigerant vapor is cooled by heat radiation through the heat dissipation fins 8 and condenses and liquefies, flows down through the condensation cooling flow path 13 and flows into the heat dissipation cooling flow path 4, and in the process of flowing down through the heat dissipation cooling flow path 4, the liquid refrigerant is further cooled by heat radiation through the heat dissipation fins 7 and becomes colder, and as the density increases, it flows down towards the bottom of the refrigerant storage outer tank 6, and when it has been cooled by heat radiation to the lowest temperature, it flows into the storage inner tank 3 from the bottom opening 5 of the refrigerant storage inner tank, forming a circulating flow of liquid refrigerant.

In other words, the circulating flow of this liquid refrigerant is an independent circulating flow that utilizes natural convection, using the heat generated by the operation of the electronic devices and the temperature difference between the liquid refrigerant and the outside air surrounding the immersion cooling apparatus 1 as its driving source, to generate an upward flow by evaporating the liquid refrigerant during the boiling cooling process, and then the refrigerant vapor is condensed and liquefied by heat dissipation from the outside air, and a downward flow is generated in which the condensed and liquefied liquid refrigerant is cooled and densified by heat dissipation from the outside air, and then the refrigerant is returned.This enables efficient immersion cooling by promoting refrigerant circulation using the liquid refrigerant alone, while eliminating the need for a refrigerant circulating power source such as a pump.

The heat dissipation fins 7 are extended at the bottom and buried in the ground, and this is to maximize the heat dissipation and cooling of the liquid refrigerant at the bottom of the outer tank 6 of the liquid storage tank, and in addition to dissipating heat into the ground, they are configured to also have an earthing function that quickly discharges current outside the apparatus when a power leak occurs or lightning strikes the immersion cooling apparatus 1. This makes it possible to significantly reduce the risk of damage by lightning strikes that occurs when the apparatus is installed outdoors, where heat dissipation into the outside air can be promoted.

In this embodiment, as another method of cooling the liquid refrigerant flowing down the heat dissipation cooling flow path 4, renewable energy electricity obtained by the solar power generation system 14 can be supplied to the cold water chiller circulation device 16 and the cold water circulation pump 17 via the power storage system 15.When the outside temperature is high, such as during the day in spring or autumn, or in summer, and the liquid refrigerant cannot be sufficiently cooled by heat dissipation cooling alone using the heat dissipation fins 7, the liquid refrigerant is forcibly cooled through heat exchange using the circulating supply of cold water using renewable energy electricity, allowing the system to continue operating independently, even when the outside air is hot.

In addition, it is desirable to arrange the power storage system, cold water chiller circulation device, and immersion cooling device 1 behind the solar power generation panel that constitutes the above-mentioned solar power generation system so that these devices are not exposed to direct sunlight and their temperature does not rise as a whole.

The above-described configuration not only makes it possible to make the immersion cooling apparatus, including the ancillary equipment for circulating and cooling the liquid refrigerant in immersion cooling, smaller and simpler, but also reduces the power consumption associated with the operation of the ancillary equipment. It also makes it possible to significantly reduce the risk of the apparatus shutting down due to failure of the ancillary equipment components, and the risk of the apparatus shutting down due to the occurrence or prolonged duration of a power outage or lightning strike.
Second Embodiment

Next, a liquid immersion cooling apparatus using a synthetic oil refrigerant for single-phase liquid immersion cooling according to a second embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 2, in the device of the second embodiment, when the liquid refrigerant 18, which is an insulating synthetic oil used for liquid immersion cooling, rises in temperature and decreases in density during cooling of electronic devices, and rises inside the liquid refrigerant storage inner tank 3, a part of a wall surface 19 constituting the inner tank 3 is notched below the liquid level to allow the heated liquid refrigerant to flow down into the heat dissipation cooling flow path 4, and a heat pipe 20 is installed inside the heat dissipation cooling flow path 4 to promote endothermic cooling of the liquid refrigerant that has flowed down inside the flow path. This is different from the first embodiment in that

Here, the heat pipe 20 is different in that a heat absorption cooling section 21 is arranged at the bottom of the heat dissipation cooling flow path 4 of the liquid refrigerant so that the temperature of the liquid refrigerant is at the lowest, and a heat dissipation section 22 that dissipates heat absorbed from the liquid refrigerant is arranged in stored rainwater in a rainwater tank 23 installed at the top of the immersion cooling apparatus 1, and these are connected by an insulating reduced pressure heat pipe tube 24, and an earth rod 25 is grounded and connected to the wall of the rainwater tank.

With this configuration, even in the case of immersion cooling using a single-phase cooling type liquid refrigerant in which the liquid refrigerant does not boil, it is possible to perform immersion cooling by circulating the liquid refrigerant while dissipating the heat of the heated liquid refrigerant into water, which has a high thermal conductivity and makes heat dissipation easier.
Third Embodiment

Next, an immersion cooling apparatus using a low boiling point refrigerant for boil cooling according to a third embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 3 , the device of the third embodiment is different in that, when condensing and cooling the vapor of the low-boiling point liquid refrigerant 2 for immersion cooling, a plurality of refrigerant vapor condensation and liquefaction heat pipes 26 are arranged to cover the top surface of the liquid refrigerant storage tank and condense and liquefy the evaporated liquid refrigerant while sealing and fixing it, and a heat-insulating condensed refrigerant flow-down plate 28 is fixed below the heat absorption cooling section 27 of the heat pipes so that the condensed and liquefied liquid refrigerant flows into the heat dissipation cooling flow path 4.

Furthermore, in the device of the third embodiment, the device is installed on the bottom surface of the irrigation channel 29 and the lower part of the device is submerged in the irrigation channel, so that when the liquid refrigerant performs heat dissipation cooling as it flows down the heat dissipation cooling channel 4, in addition to heat dissipation to the outside air from the outer wall of the channel, the liquid refrigerant is cooled by submersion cooling with the low-temperature water flowing in the irrigation channel, and in the event of a lightning strike, high-voltage current is quickly propagated into the irrigation channel via the surface of the metal casing of the device, thereby protecting the electronic devices in the device.

With this configuration, it is possible to perform immersion cooling while efficiently cooling the liquid refrigerant even in warm regions where condensation and liquefaction of the liquid refrigerant and cooling are difficult, or during periods of prolonged high outdoor temperatures in the summer, and it is also possible to protect the electronic devices inside the device in the event of a lightning strike.

As in the other embodiments, this device keeps the entire device airtight by a sealed, fixed lid that seals and fixes the top surface of the liquid refrigerant storage tank, and maintains the power supply and antenna exposure while maintaining airtightness via the sealed, fixed lid. Therefore, even if the irrigation channel or the device installation site is flooded by heavy rain or a typhoon, etc., and the water level at the time of flooding is higher than the top surface of the sealed, fixed lid and the entire device is completely submerged, it is desirable to configure the device so that the electronic devices can continue to operate while maintaining immersion cooling, thereby allowing continuous processing and transmission and reception of digital data.

With the above-described configuration, liquid immersion cooling has a higher cooling efficiency than gas cooling of electronic devices using outside air, and by making it smaller and simpler ancillary equipment such as a cooling water supply for cooling the refrigerant liquid and a refrigerant cooling device that uses circulating cooling water, it becomes possible to install and operate data centers and edge servers that are densely packed with highly efficient liquid immersion cooling-type high-performance servers, even in a small area.

The present invention is not limited to the above-described embodiments. For example, the illustrated embodiments may be applied not only to cooling applications in data centers and edge servers, but also to applications such as temperature control in constant temperature storage of heat-generating materials.

In addition, the refrigerant used for heat radiation, heat absorption or cooling of the liquid refrigerant via the heat radiation fins or heat pipes in the present invention is not limited to the outside air around the device, but may be rain or snowfall, stored rainwater or snow and ice stored in a snow cellar, or may be groundwater, fresh water from rivers or lakes or seawater, as well as geothermal heat which is maintained at 10 to 20°C regardless of the season at depths of 10 m or more underground, or cooling water obtained by cold-heat conversion from an absorption or adsorption refrigerator driven by solar heat, geothermal heat, hot spring heat or biomass combustion heat.

As described above, the above-described embodiments are merely illustrative, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included within the technical scope of the present invention.

1... Liquid immersion cooling device 2... Liquid refrigerant for immersion cooling 3... Inner tank for storing liquid refrigerant 4... Heat dissipation cooling flow path for liquid refrigerant 5... Bottom opening of inner tank for storing liquid refrigerant 6... Outer tank for storing liquid refrigerant 7... Heat dissipation fins for cooling liquid refrigerant 8... Heat dissipation fins for condensing and liquefying liquid refrigerant vapor 9... Sealed fixed lid 10... Power cable for powering electronic equipment 11... Data communication antenna 12... Condensed refrigerant flow down plate 13... Flow down path for condensed refrigerant liquid 14... Solar power generation system 15... Electricity storage system 16...Cold water chiller circulation device 17...Cold water circulation pump 18...Insulating synthetic oil refrigerant for liquid immersion cooling 19...Notched surface of liquid refrigerant storage inner tank 20...Heat pipe 21...Heat absorption and cooling section of heat pipe 22...Heat dissipation section of heat pipe 23...Rainwater tank 24...Heat pipe tube 25...Earth rod 26...Heat pipe for promoting refrigerant vapor condensation and liquefaction 27...Heat absorption and cooling section of heat pipe for promoting refrigerant vapor condensation and liquefaction 28...Condensed refrigerant flow down plate 29...Water channel

Claims (3)

a heat-insulating liquid refrigerant storage tank having openings on a part or all of a top surface and a bottom surface, housing an electronic device therein, and storing a liquid refrigerant for cooling the electronic device;
an outer tank that houses the liquid refrigerant storage tank and forms a heat dissipation/cooling flow path for the liquid refrigerant at at least a part of an outer periphery of the liquid refrigerant storage tank;
a heat dissipation cooling means for dissipating heat and cooling the liquid refrigerant so that the temperature of the liquid refrigerant is lowest at the bottom portion of the liquid refrigerant storage tank when the liquid refrigerant flows down toward the bottom surface of the liquid refrigerant storage tank;
A water storage tank is provided above the top surface of the outer tank and capable of storing rainwater .
the heat dissipation cooling means has a heat absorption portion disposed within the heat dissipation cooling flow path, and a heat dissipation portion protruding from a top surface of the outer tank and disposed in water stored in the water storage tank;
a cooling device for electronic devices, characterized in that the liquid refrigerant inside the liquid refrigerant storage tank is heated and vaporized due to heat generated by the electronic device and is discharged to the outside of the liquid refrigerant storage tank from the opening in the top surface, where it cools and condenses into a liquid as it flows down the heat dissipation cooling flow path and is stored in the bottom portion of the outer tank, and the liquid refrigerant stored in the bottom portion of the outer tank flows into the liquid refrigerant storage tank from the opening in the bottom surface of the liquid refrigerant storage tank, thereby circulating the liquid refrigerant by natural convection. 2. The cooling device for electronic equipment according to claim 1, wherein the heat dissipation cooling means is a heat pipe that absorbs heat from the liquid refrigerant in the heat dissipation cooling flow path and dissipates the heat to the outside of the outer tank. 2. The cooling device for electronic equipment according to claim 1, wherein the water storage tank receives rainwater and stores the rainwater therein.