JP7010702B2 - Heat exchanger and cooling tower - Google Patents

Description

The present invention relates to a heat exchanger and a cooling tower, and particularly to a cooling tower with condensation and a heat exchanger used therein.

The cooling tower has realized more efficient cooling by blowing air into the cooling water and exchanging heat between the water and air using latent heat. The invention of the closed cooling tower not only solved the problem of contamination of the cooling water, but also made it possible to cool the refrigerant other than water. As seen in Patent Document 1, in the closed cooling tower, the heat exchange piping inside the cooling tower is installed horizontally and the piping is meandered to increase the surface area in contact with the outside air and water sprinkling, and improve the heat exchange performance. Was going.

While such a method is suitable for cooling the refrigerant without condensation, cooling the refrigerant with condensation causes a decrease in heat transfer coefficient and increases the pressure loss of the system. It was unsuitable. In the closed cooling tower of Patent Document 2, the heat exchanger is installed with an inclination so that the plate fins descend along the ventilation direction without meandering the pipes constituting the heat exchanger, and then heat exchange is performed. A method of sprinkling water from the upper part of the vessel to the heat exchanger has been proposed. By adopting such a method, the condensed refrigerant in the cooling tower can be circulated by gravity, which is expected to improve the heat transfer coefficient and reduce the pressure loss.

Microfilm of Jitsugyo No. 62-78944 (Jitsukai Sho No. 63-190764) Microfilm of Jitsusho 60-86562 (Jitsukaisho 61-204173)

However, the above-mentioned cooling tower has the following problems. When water is sprinkled from above on an inclined heat exchanger as in Patent Document 2, an extra amount of water is required to sprinkle water on the entire heat exchanger. In addition, the amount of water sprinkled on the upper part of the heat exchanger becomes excessive, and latent heat cannot be used efficiently. In addition, a water circulation system for watering is indispensable. When tap water is used for this sprinkling, there arises a problem that components such as calcium, magnesium, and silica contained in the tap water are condensed and crystallized to form a scale. Not only does scale generation significantly reduce heat transfer coefficient, but it also requires frequent maintenance and filter installation. In addition, there are cases where chemical substances that are harmful to the human body are used to remove silica.

An object of the present invention is to provide a cooling tower with condensation and a heat exchanger used therein, which can improve heat exchange performance while reducing the amount of water used.

In order to achieve the above object, the heat exchanger according to the present invention is a plurality of parallel flow paths in which fine particle droplets are sprayed, and the fluid to be cooled is in the direction of gravity, or the fluid after condensation is gravity. Includes multiple parallel channels installed at an angle that can be circulated for use.

The cooling tower according to the present invention is a plurality of parallel flow paths, and includes a plurality of parallel flow paths installed at an inclination in which the fluid to be cooled is in the direction of gravity or the fluid after condensation can be circulated by utilizing gravity. Includes a heat exchanger, a fan that blows air through the heat exchanger, a spray nozzle that sprays fine droplets onto the heat exchanger, and piping connected to the heat exchanger. ..

According to the present invention, the sprayed droplets can be efficiently vaporized on or near the surface of a plurality of parallel flow paths of the heat exchanger, and the fluid to be cooled is condensed while reducing the amount of water used. It is possible to improve the heat exchange performance.

(A) is an overview diagram for explaining a cooling tower according to an embodiment of the uppermost concept, and (b) is an overview diagram of a heat exchanger used for this cooling tower. It is a schematic diagram for demonstrating the cooling tower of 1st Embodiment of this invention. It is an overview view of the heat exchanger used for the cooling tower of FIG. It is a conceptual diagram which shows the air volume distribution near the heat exchanger by the fan of the cooling tower of the embodiment of this invention. It is a conceptual diagram which shows the positional relationship of the fan, the heat exchanger, and the spray nozzle which constitute the cooling tower of embodiment of this invention. (A) is a diagram showing an overview when there is one inlet flow path of the heat exchanger and a flow rate distribution of a spray nozzle that matches the position of the inlet flow path, and (b) is a diagram showing the case where there are a plurality of inlet channels of the heat exchanger. It is a figure which shows the overview and the flow rate distribution of a spray nozzle which matches the position of an inlet flow path. It is a schematic diagram for demonstrating the cooling system of the server room using the cooling tower of embodiment of this invention. It is a schematic diagram for demonstrating the heat exchanger used in the cooling tower of the 2nd Embodiment of this invention. It is a schematic diagram for demonstrating the heat exchanger used in the cooling tower of the 3rd Embodiment of this invention. It is a schematic diagram for demonstrating the heat exchanger used in the cooling tower of the 4th Embodiment of this invention. It is a schematic diagram for demonstrating the heat exchanger used in the cooling tower of the 5th Embodiment of this invention. It is a graph which shows the measurement result of the thermal resistance value by the change of the wet bulb temperature at the time of cooling by using the heat exchanger of the embodiment of this invention.

Preferred embodiments of the present invention will be described in detail with reference to the drawings.

Before explaining a specific embodiment, a cooling tower according to an embodiment of the highest concept of the present invention and a heat exchanger used therein will be described. FIG. 1 (a) is an overview view for explaining a cooling tower according to an embodiment of the highest-level concept, and FIG. 1 (b) is an overview diagram of a heat exchanger used in this cooling tower.

The cooling tower 100 of FIG. 1A includes a fan 109 for blowing air, a heat exchanger 105, and a spray nozzle 106 for spraying fine particle droplets onto the heat exchanger 105. As shown in FIG. 1 (b), the heat exchanger 105 of FIG. 1 (a) is a plurality of parallel flow paths 103 in which fine particle droplets are sprayed, and the fluid to be cooled is in the direction of gravity or condensed. It includes a plurality of parallel flow paths 103 installed at an inclination so that the later fluid can be circulated by utilizing gravity.

The sprayed fine particle droplets can be efficiently vaporized on or near the surface of a plurality of parallel flow paths of the heat exchanger 105 to condense the fluid to be cooled while reducing the amount of water used. And the heat exchange performance can be improved. The heat exchange performance of the heat exchanger 105 can be improved, and the cooling tower 100 with improved heat exchange performance can be realized. Hereinafter, more specific embodiments of the present invention will be described.

[First Embodiment]
First, the cooling tower according to the first embodiment of the present invention and the heat exchanger used therein will be described. FIG. 2 is an overview view for explaining the cooling tower of the first embodiment of the present invention.

[Explanation of structure]
The cooling tower of the first embodiment of the present invention is a closed cooling tower. The closed cooling tower 20 of FIG. 2 includes a fan 9 for blowing air, a heat exchanger 5, and a spray nozzle 6 for spraying fine water droplets as an example of fine particle droplets onto the heat exchanger 5. .. Further, the closed cooling tower 20 includes pipes 12a and 12b connected to the heat exchanger 5. Further, the closed cooling tower 20 of FIG. 2 includes a pressure gauge 7, a flow rate adjusting valve 8, a pump 10, and a water storage tank 11.

The fan 9 is installed in the upper part of the housing 13 of the closed cooling tower 20, and blows air so that air passes through the heat exchanger 5 and flows out from the upper part of the closed cooling tower 20. The air blowing direction to the heat exchanger 5 in the closed cooling tower 20 is from the side where the water droplets of the fine particles are sprayed from the spray nozzle 6 toward a plurality of parallel flow paths to be cooled. More specifically, air is blown to the heat exchanger 5 along the direction of the arrow in FIG. 2 from the outside to the inside of the closed cooling tower 20.

The spray nozzle 6 sprays fine particles of water onto the heat exchanger 5. The spray nozzle 6 is installed with an inclination with respect to the heat exchanger 5 so that the spray distribution amount of the spray nozzle 6 is proportional to the fan air volume gradient. In particular, the spray nozzle 6 is installed so as to spray fine particles of water droplets onto the heat exchanger 5 diagonally downward from the outer upper portion of the heat exchanger 5.

The heat exchanger 5 includes a plurality of parallel flow paths, which are installed in the direction of gravity for the refrigerant to be cooled or at an inclination so that the condensed refrigerant can be circulated by using gravity. Hereinafter, a plurality of parallel flow paths of such a heat exchanger 5 will be referred to as a plurality of flow paths. FIG. 2 shows a case where the heat exchanger 5 is installed so that the plurality of flow paths of the heat exchanger 5 are parallel to the direction of gravity as an example of the installation form. FIG. 2 shows a case where the heat exchanger 5 is installed on both sides of the closed cooling tower 20. A spray nozzle 6, a pressure gauge 7, a flow rate adjusting valve 8, and a pump 10 are installed corresponding to the double-sided installation of the heat exchanger 5.

FIG. 3 is an overview view of the heat exchanger 5 used in the cooling tower of FIG. As shown in FIG. 3, the heat exchanger 5 is provided in the inlet flow path 1 through which the refrigerant to be cooled flows, the header 2 in which the refrigerant flowing in from the inlet flow path 1 branches into the plurality of flow paths 3, and the plurality of flow paths 3. The fins 4 and the obtained fins 4 are included.

The heat exchanger 5 including the plurality of flow paths 3 has an inclination that allows the condensed liquid to efficiently flow out of the closed cooling tower 20 by gravity in parallel with the gravity direction as shown in FIG. 2 or based on the viscosity of the refrigerant. And it will be installed.

In the present embodiment, heat is generated by spraying fine water droplets on the heat exchanger 5 diagonally downward from the outer upper portion of the heat exchanger 5 installed on both sides of the closed cooling tower 20 with a spray nozzle 6 having an inclination. Condensation cooling of the refrigerant to be cooled flowing in the plurality of flow paths 3 of the exchanger 5 is performed.

As seen in FIG. 4, the closed cooling tower 20 according to the embodiment of the present invention has special control from the upper part to the lower part of the heat exchange surface of the heat exchanger 5 by the positions of the fan 9 and the heat exchanger 5. It is an arrangement that allows the air volume distribution to be graded without the need. A spray nozzle 6 is installed there by inclining the heat exchanger 5 from the upper outside of the heat exchanger 5 so that the spray distribution amount is proportional to the fan air volume gradient.

The size of the water droplets sprayed from the spray nozzle 6 is preferably in the state of fine particles that do not completely evaporate before reaching the plurality of flow paths 3 of the heat exchanger 5 from the spray nozzle 6. The diameter of the water droplet sprayed from the spray nozzle 6 is, for example, 150 μm or less. Further, the minimum diameter of the water droplet sprayed from the spray nozzle 6 changes depending on the conditions such as the distance between the spray nozzle 6 and the plurality of flow paths 3 and the air volume. It is preferable that the pipes constituting the plurality of flow paths 3 are arranged so as to avoid overlapping as much as possible so that the water droplets sprayed from the spray nozzles come into contact with each other evenly.

When spraying the entire multi-channel portion (heat exchange portion), as seen in FIG. 6, the multi-channel portion having a short distance from the inlet flow path 1 of the heat exchanger 5 is compared with the portion having a long distance. If a spray nozzle with a spray distribution that can send a large amount of spray flow is used, the spray water can be effectively used. This is because a large amount of refrigerant flows through the plurality of flow paths 3 near the inlet flow path 1 of the heat exchanger 5, so that the required heat exchange amount of the plurality of flow paths 3 near the inlet flow path 1 also increases accordingly.

The flow rate of water droplets sprayed from the spray nozzle 6 does not evaporate completely by the time the water particles arrive at the heat exchanger 5, but most of them effectively utilize latent heat while passing through the heat exchanger 5. Set the flow rate so that it can be evaporated. It is preferable that the amount is set so that it can evaporate while passing through the heat exchanger 5, and the spraying is performed at a distance as close as possible to the heat exchanger 5. With such a configuration, it is possible to prevent the water sprayed from the spray nozzle 6 from scattering. At this time, the position is adjusted so that the sprayed water is applied to the entire heat exchanger 5. The spray nozzle 6 may use a one-fluid nozzle that sprays only water, or may use a two-fluid nozzle that simultaneously sprays water and compressed air together.

The distance between the heat exchanger 5 and the spray nozzle 6 is set so that the spray width is wide on the front surface of the heat exchanger 5 and the distance is as short as possible. The spray nozzle 6 is installed with an inclination angle proportional to the air volume distribution gradient above and below the heat exchanger 5 caused by the fan 9 installed on the upper part of the closed cooling tower 20.

Since the inclined spray nozzle 6 sprays fine water droplets diagonally downward from the outer upper part of the heat exchanger 5, the upper part of the heat exchanger 5 having a short spray distance from the nozzle has a large amount of spray per unit area. Since the spray amount decreases as the distance from the spray nozzle 6 increases, it is possible to realize a spray amount having a gradient with respect to the same heat exchanger 5. A plurality of heat exchangers 5 are combined with one heat exchanger 5 by increasing the amount of spray by the spray nozzle 6 in a place where the fan air volume is large and decreasing the amount of spray by the spray nozzle 6 in a place where the fan air volume is small. It is possible to optimize the flow path 3 according to the required heat exchange amount.

The water sprayed in the form of fine particles is a device composed of a pump 10, a pressure gauge 7, a breaker (not shown), a flow rate adjusting valve 8, a thermometer (not shown), and a pipe or tube from the tank 11 to the spray nozzle 6. Is supplied by. Since it is assumed that the spraying by the spray nozzle 6 of the present embodiment is applied only when the wet-bulb temperature is high and the condensation performance is lowered, such as in summer, refer to the outside air wet-bulb thermometer and the refrigerant temperature flowing in the system. , Will be done.

By increasing the number of pipes of the plurality of flow paths 3 constituting the heat exchanger 5 in the closed cooling tower 20, the contact area between the outside air and the sprayed water droplets can be increased. In addition, the piping of the plurality of flow paths 3 constituting the heat exchanger 5 is designed in consideration of the influence of an increase in pressure loss due to the reduction in the diameter of the piping.

The fan 9 installed on the upper surface of the housing 13 of the closed cooling tower 20 causes an air volume gradient with respect to the plurality of flow paths 3 of the heat exchanger 5 installed in parallel with the direction of gravity. The air volume gradient caused by the fan 9 is hereinafter referred to as a fan air volume gradient. FIG. 4 is a conceptual diagram showing the air volume distribution in the vicinity of the heat exchanger by the fan of the cooling tower according to the embodiment of the present invention. The fan 9 causes an air volume distribution gradient as shown in FIG. As shown in FIG. 5, a spray nozzle 6 for spraying fine water droplets is provided on the heat exchanger 5 from the outer upper part of the heat exchanger 5 so that the spray distribution amount of the spray nozzle 6 is proportional to the fan air volume gradient. Install with an inclination.

It is conceivable that a plurality of inlet flow paths 1 of the heat exchanger 5 are provided instead of being a single number as shown in FIG. The relationship between the inlet flow path 1 of the heat exchanger 5 and the nozzle flow rate distribution by the spray nozzle will be described. FIG. 6A is a diagram showing an overview when there is only one inlet flow path of the heat exchanger and a flow rate distribution of the spray nozzle matching the position of the inlet flow path, and FIG. 6B is a diagram showing the flow rate distribution of the inlet flow path of the heat exchanger. It is a figure which shows the overview in the case of a plurality of cases, and the flow rate distribution of a spray nozzle which matches the position of an inlet flow path.

As can be seen in FIG. 6A, the selection of the spray nozzle and the position of the spray nozzle are selected in consideration of the fact that the maximum point of the nozzle flow rate distribution is below the inlet flow path and the spray width is within the heat exchanger surface. Select and select the installation direction. When there are a plurality of inlet channels 1 of the heat exchanger 5, as shown in FIG. 6B, the maximum point of the nozzle flow distribution is below the plurality of inlet channels, and the spray width is heat exchange. Select the spray nozzle, select the position of the spray nozzle, and select the installation direction in consideration of fitting on the surface of the vessel. By such selection and installation, the heat flow velocity value distribution inside and outside the heat exchanger can be brought closer, and the flow rate can be optimized.

[Explanation of cooling operation]
The refrigerant to be cooled, which has become steam due to the heat from the heat generation source, flows into the heat exchanger 5 from the inlet flow path 1 via the pipe 12a. The fine particle-like water droplets sprayed from the spray nozzle 6 are efficiently vaporized at or near the surface of the plurality of flow paths 3 of the heat exchanger 5 with the contribution of the air blown by the fan 9. The heat exchange by the heat exchanger 5 causes condensation of the refrigerant to be cooled. The liquid refrigerant to be cooled is sent to the vicinity of the heat generation source again via the pipe 12b by using gravity. The closed cooling tower 20 of the present embodiment cools by circulating the refrigerant to be cooled via the heat exchanger 5.

[Explanation of effect]
According to the closed cooling tower 20 of the present embodiment, the fine particles sprayed by blowing water with the fan 9 while spraying water with the spray nozzle 6 to the heat exchanger 5 including the plurality of flow paths 3. Water droplets are efficiently vaporized on or near the surface of the plurality of flow paths 3. The heat exchanger 5 condenses the refrigerant to be cooled by the heat exchange action. The heat exchange performance can be improved by vaporizing the water droplets of the sprayed fine particles.

By using the sprayed fine particle water droplets, the refrigerant to be cooled can be condensed while reducing the amount of water used, and the heat exchange performance can be improved. The heat exchange performance of the heat exchanger 5 can be improved, and the closed cooling tower 20 with improved heat exchange performance can be realized.

Compared with the cooling tower of Patent Document 2 in which water is sprinkled from the upper part of the heat exchanger, the amount of water used can be reduced, so that there is a problem that an extra amount of water is required and the upper part of the heat exchanger is scattered. It is possible to solve the problem that the amount of water is excessive and the latent heat cannot be used efficiently. Further, by reducing the amount of water used, it is possible to delay the manifestation of the problem that components such as calcium, magnesium and silica contained in tap water are condensed and crystallized to form a scale. The problem of reduced heat transfer coefficient caused by scale generation can be solved, and frequent maintenance and filter installation can be eliminated.

As a result, in a closed cooling tower with condensation, heat exchange performance is improved, the load on the system is reduced due to pressure loss, the circulation system is eliminated by reducing the amount of water sprinkled, and reliability is improved by solving problems such as scale related to water circulation. Can be realized.

The closed cooling tower 20 of the embodiment of the present invention is suitable for a cooling method utilizing latent heat when the sprayed water efficiently evaporates when it is difficult to cool with only the fan 9 due to an increase in the outside air temperature. .. It is conceivable to measure the outside air temperature and the temperature of the refrigerant to be cooled, and to make a mechanism for spraying when necessary conditions are met.

[Usage example of closed cooling tower]
As a method of using the closed cooling tower according to the embodiment of the present invention, cooling of IT (Information Technology) equipment such as a server in a data center can be mentioned. The server rack 22 is installed in the server room 21 of the data center 30 of FIG. 7, and the heat receiving unit 23 is installed on the rack rear door side. A server is installed in the server rack 22, and the heat generated from the IT equipment in the server is air-cooled by the fan mounted on the server, and the air warmed at that time is cooled by the heat receiving unit 23 installed on the rack rear door side. As a result, the air discharged to the outside of the server rack 22 is cooled. At this time, the heat absorbed by the heat receiving unit 23 is carried into the heat exchanger of the closed cooling tower 20 by the circulation of the refrigerant, and is dissipated to the outside air there. The heat receiving unit 23 and the heat exchanger of the closed cooling tower 20 are connected by a liquid pipe 24 and a steam pipe 25. The closed cooling tower 20 is installed above the server room 21, and the refrigerant in the heat receiving unit 23 becomes steam due to the phase change, and the refrigerant steam is directly supplied by the closed cooling tower 20 according to the embodiment of the present invention. It will be cooled. The heat exchanger of the closed cooling tower 20 becomes a condensing part, and the refrigerant liquid after being condensed by the heat exchanger is returned to the heat receiving part 23 via the liquid pipe 24 to circulate the refrigerant, and the outside air is radiated. Perform cooling. The refrigerant liquid condensed by the heat exchanger reaches the heat receiving unit 23 via the liquid pipe 24 due to the gravitational action.

In the closed cooling tower 20 with condensation as in the present embodiment, there are problems such as improvement of heat exchange performance, reduction of load on the system due to pressure loss, elimination of circulation system by reduction of water sprinkling amount, and scale related to water circulation. It is expected that the solution will improve reliability. Note that FIG. 7 shows a case where the closed cooling tower 20 is installed above the server room 21, but the closed cooling tower 20 is installed above the server room 21 and a refrigerant using a pump. May be installed in a place other than above by forced circulation.

A large amount of cooling power is consumed for exhaust heat of IT equipment such as servers in data centers, and it is possible to significantly reduce cooling power by directly dissipating outside air instead of using a cooling air conditioner for cooling. It becomes. The heat transport to the outside air by the fan has sufficient cooling capacity when the outside temperature is low, but the cooling capacity is lost in an environment where the outside temperature is high such as summer. By using a cooling tower with a high cooling capacity, it is possible to dissipate heat from the outside air even in an environment with a high outside temperature, and as a result, it can greatly contribute to the reduction of cooling power.

[Second Embodiment]
Next, the cooling tower according to the second embodiment of the present invention will be described. The cooling tower of the present embodiment uses a different heat exchanger as compared with the cooling tower of the first embodiment. Since the configuration other than the heat exchanger is the same as that of the cooling tower according to the first embodiment, detailed description thereof will be omitted. FIG. 8 is an overview view for explaining a heat exchanger used in the cooling tower of the second embodiment of the present invention.

[Explanation of structure]
In the heat exchanger 5a of the present embodiment, the pipe diameter of the plurality of flow paths 3 constituting the heat exchanger 5a is sloped so as to become thicker as the distance from the inlet flow path 1 increases. In FIG. 8, of the pipes of the plurality of flow paths 3, the pipe diameter of the pipe 3b is larger than the pipe diameter of the pipe 3a close to the inlet flow path 1. Further, among the pipes of the plurality of flow paths 3, the pipe diameter of the pipe 3c, which is farther from the inlet flow path 1, is larger than the pipe diameter of the pipe 3b.

In the heat exchanger 5a of the present embodiment, in which the pipe diameter of the plurality of flow paths 3 located at a distance close to the inlet flow path 1 is increased as the distance from the inlet flow path 1 increases, the heat exchanger 5a has an inlet flow. The refrigerant steam flowing from the path 1 can be evenly distributed over the entire plurality of flow paths 3. By evenly distributing the refrigerant flowing from the inlet flow path 1 to the plurality of flow paths 3, it is possible to improve the cooling capacity and reduce the size of the heat exchanger 5a and the closed cooling tower 20.

[Third Embodiment]
Next, the cooling tower according to the third embodiment of the present invention will be described. The cooling tower of the present embodiment uses a different heat exchanger as compared with the cooling tower of the first embodiment. Since the configuration other than the heat exchanger is the same as that of the cooling tower according to the first embodiment, detailed description thereof will be omitted. FIG. 9 is an overview view for explaining a heat exchanger used in the cooling tower according to the third embodiment of the present invention.

[Explanation of structure]
In the heat exchanger 5b of the present embodiment, the header volume of the upper part of the plurality of flow paths 3 constituting the heat exchanger 5b is graded so as to increase as the distance from the inlet flow path 1 increases. As can be seen in FIG. 9, the pipe diameter of the plurality of flow paths 3 is made constant, and as the distance from the plurality of flow paths 3 near the inlet flow path 1 increases from the plurality of flow paths 1, the upper portion of the plurality of flow paths 3 3 increases. The volume of the header 2a of the above is increased by adding a gradient.

In the heat exchanger 5b having a gradient so that the header volume of the upper part of the plurality of flow paths 3 increases as the distance from the inlet flow path 1 increases in the present embodiment, a plurality of refrigerant vapors flowing in from the inlet flow path 1 are used. It can be evenly distributed over the entire flow path 3. By evenly distributing the refrigerant flowing from the inlet flow path 1 to the plurality of flow paths 3, it is possible to improve the cooling capacity and reduce the size of the heat exchanger 5b and the closed cooling tower 20.

[Fourth Embodiment]
Next, the cooling tower according to the fourth embodiment of the present invention will be described. The cooling tower of the present embodiment uses a different heat exchanger as compared with the cooling tower of the first embodiment. Since the configuration other than the heat exchanger is the same as that of the cooling tower according to the first embodiment, detailed description thereof will be omitted. FIG. 10 is an overview view for explaining a heat exchanger used in the cooling tower of the fourth embodiment of the present invention.

[Explanation of structure]
In the heat exchanger 5c of the present embodiment, as shown in FIG. 10, a recessed portion 2c is formed on the bottom surface of the header 2b located below the inlet flow path 1. In the recessed portion 2c, the height of the bottom surface of the header 2b is lower than the height of other portions of the bottom surface of the header 2b. By attaching the recessed portion 2c to the bottom surface of the header 2b located below the inlet flow path 1, the refrigerant liquid contained in the refrigerant vapor flowing from the inlet flow path 1 is collected in the recessed portion 2c. Due to the structure in which the refrigerant liquid contained in the refrigerant vapor is partially aggregated, the liquid film formed by the condensation of the refrigerant in the plurality of flow paths 3 of the heat exchanger 5c can be thinned. By thinning the liquid film, the heat transfer coefficient is improved, and as a result, the cooling capacity can be improved and the size of the heat exchanger 5c and the closed cooling tower 20 can be reduced.

In the heat exchanger 5c of FIG. 10, similarly to the heat exchanger 5a of the second embodiment, the pipe diameters of the plurality of flow paths constituting the heat exchanger 5c are increased as the distance from the inlet flow path 1 increases. The slope is set so that it does. In FIG. 10, the pipe diameter of the pipe 3b is larger than the pipe diameter of the pipe 3a near the inlet flow path 1. Further, the pipe diameter of the pipe 3c, which is farther from the inlet flow path 1, is larger than the pipe diameter of the pipe 3b.

In the heat exchanger 5c having a gradient such that the pipe diameter of the plurality of flow paths 3 located at a distance close to the inlet flow path 1 becomes thicker as the distance from the inlet flow path 1 increases, as in the present embodiment. The refrigerant steam flowing from the inlet flow path 1 can be evenly distributed to the entire plurality of flow paths 3. By using the gradient of the pipe diameter of the plurality of flow paths 3 together, it is possible to further improve the cooling capacity and further reduce the size of the heat exchanger 5c and the closed cooling tower 20.

[Fifth Embodiment]
Next, the cooling tower according to the fifth embodiment of the present invention will be described. The cooling tower of the present embodiment uses a different heat exchanger as compared with the cooling tower of the first embodiment. Since the configuration other than the heat exchanger is the same as that of the cooling tower according to the first embodiment, detailed description thereof will be omitted. FIG. 11 is an overview view for explaining a heat exchanger used in the cooling tower according to the fifth embodiment of the present invention.

[Explanation of structure]
The heat exchanger 5d of the present embodiment has a configuration in which a recessed portion 2c is formed on the bottom surface of the header 2d located below the inlet flow path 1 with respect to the heat exchanger of the third embodiment described above. In the recessed portion 2c, the height of the bottom surface of the header 2d is lower than the height of other parts of the bottom surface of the header 2d. By attaching the recessed portion 2c to the bottom surface of the header 2d located below the inlet flow path 1, the refrigerant liquid contained in the refrigerant vapor flowing from the inlet flow path 1 is partially collected in, for example, the recessed portion 2c. ..

Due to the structure in which the refrigerant liquid contained in the refrigerant vapor is partially aggregated, the liquid film formed by the condensation of the refrigerant in the plurality of flow paths 3 of the heat exchanger 5d can be thinned. By thinning the liquid film, the heat transfer coefficient is improved, and as a result, the cooling capacity can be improved and the size of the heat exchanger 5d and the closed cooling tower 20 can be reduced.

Further, in the heat exchanger 5d having a gradient so that the header volume of the upper part of the plurality of flow paths 3 increases as the distance from the inlet flow path 1 increases as in the present embodiment, the refrigerant flowing in from the inlet flow path 1 The steam can be evenly distributed over the entire plurality of flow paths 3. By evenly distributing the refrigerant flowing from the inlet flow path 1 to the plurality of flow paths 3, it is possible to further improve the cooling capacity and further reduce the size of the heat exchanger 5d and the closed cooling tower 20.

FIG. 12 shows the measurement results of the thermal resistance value due to the change in the wet-bulb temperature when cooling is performed by using the heat exchanger 5 configured by the plurality of flow paths 3 parallel to the direction of gravity as in the embodiment of the present invention. It is a graph which shows. FIG. 12 shows a case where water droplets of fine particles are sprayed and cooled together with air blown by a fan 9 as in the above-described embodiment, and a case where large water droplets which are not fine particles are sprinkled on the same heat exchanger and cooled. In FIG. 12, the diameter of the water droplets of the sprayed fine particles used for cooling is set to be 150 μm or less.

The refrigerant to be cooled is heated by the heat receiving unit and cooled by the closed cooling tower. Rcv shown in FIG. 12 is the thermal resistance of the heat receiving section, Rvw is the thermal resistance of the heat radiating section (cooling tower), and Rcw is the sum of the thermal resistance Rcv of the heat receiving section and the thermal resistance Rvw of the radiating section (cooling tower).

Rcv spray is the thermal resistance of the heat-receiving part when water droplets of fine particles are sprayed and cooled, and Rvw spray is the thermal resistance of the heat-dissipating part (cooling tower) when water droplets of fine particles are sprayed and cooled. Further, Rcw spray shows the sum of the thermal resistance Rcv spray of the heat receiving part when the water droplets of the fine particles are sprayed and cooled, and the thermal resistance Rvw spray of the heat radiating part (cooling tower) when the water droplets of the fine particles are sprayed and cooled.

From the measurement results of the thermal resistance value, a significant improvement in thermal resistance was seen, indicating an improvement in cooling capacity. According to the embodiments and examples of the present invention, it is possible to improve the cooling capacity by improving the thermal resistance and reducing the pressure loss, and as a result, the cooling using the outside air at the time when the wet-bulb temperature is high can be realized.

Although preferred embodiments and examples of the present invention have been described above, the present invention is not limited thereto. In the above-described embodiment, for example, FIG. 2, the case where the heat exchanger 5 is installed so that the plurality of flow paths of the heat exchanger 5 are parallel to the direction of gravity has been described, but the present invention is not limited to this. It can also be applied to the heat exchanger 5 installed at an inclination so that the fluid to be cooled can be circulated by utilizing gravity after the fluid to be cooled exchanges heat with the heat exchanger 5 and is condensed. Then, it can be applied to a closed cooling tower using a heat exchanger 5 installed at such an inclination.

Further, the fluid to be cooled, for example, used in the closed cooling tower 20, may be water or another refrigerant. The fluid to be cooled is assumed to be a liquid, a gas, or a mixed fluid. Further, the amount of water sprayed from the spray nozzle 6 to the closed cooling tower 20 is about the latent heat of vaporization, and therefore the circulation system of the sprayed water and the filter are not required.

Further, the cooling tower of the embodiment of the present invention is a cooling system using a refrigerant circulation cycle in which the exhaust heat of a data center or the like is cooled by absorbing heat using a refrigerant as a medium at a heat receiving unit, and the absorbed refrigerant is circulated. Can be used.

As a method of use in the refrigerant circulation cycle, by installing the heat dissipation part at a position higher than the heat receiving part, an application in natural circulation using the density difference of the gas liquid due to the phase change of the refrigerant in the circulation cycle can be considered. Alternatively, as a method of use in the refrigerant circulation cycle, an application in forced circulation using a pump or the like without considering the position of the heat radiating part can be considered.

(Summary of effect)
The effects of the closed cooling tower according to the embodiment of the present invention can be summarized as follows.

The first effect is to install the piping of multiple flow paths for heat exchange parallel to the direction of gravity, or by installing the condensed liquid based on the viscosity of the refrigerant at an inclination that efficiently flows out of the cooling tower using gravity. , Make the thickness of the liquid film formed by the condensate in the piping of multiple channels as thin as possible. This promotes the improvement of the heat transfer coefficient. As a result, the cooling capacity per unit volume is improved and the size of the heat exchanger is reduced. Further, by reducing the thickness of the liquid film formed by the condensed liquid, the cross-sectional area in the effective pipe through which the vapor before condensation passes is increased, and as a result, the pressure loss is reduced. In the heat transport process with phase change, the pressure loss has a great influence on the heat transport amount, and as a result, the cooling capacity is improved.

The second effect is that due to the positional relationship between the fan and the heat exchanger as shown in FIG. 4, the air volume passing through the heat exchanger is graded from the top to the bottom without requiring special control. It is possible. By inclining the spray nozzle from the upper part of the outside of the heat exchanger so that the spray distribution amount is proportional to the fan air volume gradient, it becomes possible to promote evaporation efficiently. As a result, the cooling capacity is improved. In addition to the effect of saving water by efficient evaporation, it is possible to expand the spray width and reduce the number of required nozzles by making an inclination.

Similarly, as can be seen in FIG. 6, by selecting the nozzle and the position where the maximum point of the nozzle flow rate distribution is below the inlet flow path and the spray width is within the heat exchanger surface, the inside of the heat exchanger can be selected. The outer heat flow velocity value distribution is brought closer, and the flow rate can be optimized.

The third effect is that by spraying fine water droplets in the cooling tower, it is possible to promote the vaporization of water and improve the heat transfer coefficient even under a high environmental wet-bulb temperature. The heat transfer coefficient is calculated by a mathematical formula (heat transfer coefficient = heat conductivity x area x ΔT ÷ thickness). Here, ΔT is the temperature difference. When the diameter of the water droplet is reduced, the (thickness) of the above formula becomes smaller, and as a result, the heat transfer coefficient becomes larger. Therefore, the heat transfer coefficient is improved by reducing the diameter of the water droplets in the form of fine particles to be sprayed.

Further, in order for the water particles to exist as droplets, the surface tension must be balanced with the internal pressure, and the internal pressure increases as the water droplet diameter decreases. Therefore, when the water droplet diameter decreases, it becomes difficult to maintain the stability of the water droplet. At this time, if other water droplets are present in the vicinity of the water droplets, they are merged and exist as large water droplets, but if there is a distance from the other water droplets, the evaporation of the droplets whose stability is not maintained is promoted. As a result, it promotes vaporization.

Not only can water consumption be reduced by spraying water in the form of fine particles for an evaporable flow rate, but also the water circulation system for watering and the associated circulation power (pump power, filtering) are not required. It eliminates the problem of scale generation due to crystallization of components (calcium, magnesium, silica, etc.) contained in tap water, and maintenance of them. Since there are cases where chemical substances that are harmful to the human body are used to remove silica, it contributes to the improvement of safety. In addition, the size of the water storage tank can be reduced by reducing the required flow rate.

In addition, all the problem-solving methods specified below contribute to the improvement of cooling capacity. First, by installing the pipes constituting the plurality of flow paths 3 of the heat exchanger 5 so as to be parallel to the direction of gravity, the pipes are installed horizontally as in Patent Document 1, and then inside the cooling tower. It is possible to increase the heat exchangeable surface area within the same volume as compared with the pipe shape that is meandered by and gains distance.

This is because the pipe can be installed more densely by eliminating the volume loss of the curved portion of the pipe. Further, in the method of the present invention in which the distance between each pipe is shortened and the number of pipes is increased, the time for holding the liquid produced by condensation in a plurality of pipes is short, and as a result, not only the heat transfer coefficient is improved but also the liquid is maintained. It is also possible to significantly reduce the pressure loss that occurs when transporting the water to the outside of the cooling tower.

Secondly, as shown in FIGS. 8 and 10, the method of making the pipe diameter of the plurality of flow paths 3 thicker as the distance from the inlet flow path increases is to heat exchanger the refrigerant to be cooled. It is evenly distributed to contribute to the improvement of cooling capacity. Third, as shown in FIGS. 9 and 11, the pipe diameter of the multiple flow paths is made constant, and the header volume at the upper part of the multiple flow paths is increased with a gradient as the distance from the inlet flow path increases. Has the same effect as the previous example. Fourth, as seen in FIGS. 10 and 11, the height of the bottom surface of the header located below the inlet flow path is made lower than the other parts of the bottom surface of the header, or by making a dent, the refrigerant steam to be cooled By concentrating the liquid mixed in, it contributes to the improvement of the heat transfer coefficient.

As described above, various modifications are possible within the scope of the claimed invention, and it goes without saying that they are also included in the scope of the present invention.

Some or all of the above embodiments and examples may be described as in the appendix below, but are not limited to the following.
(Appendix 1) A plurality of parallel flow paths in which fine particle droplets are sprayed, and a plurality of parallel channels installed at an inclination in which the fluid to be cooled is circulated in the direction of gravity or the fluid after condensation can be circulated by utilizing gravity. A heat exchanger that includes a flow path.
(Supplementary Note 2) The description in Appendix 1 further includes an inlet flow path into which the fluid to be cooled flows, and a header in which the fluid to be cooled flowing from the inlet flow path branches into the plurality of parallel flow paths. Heat exchanger.
(Appendix 3) The heat exchanger according to Appendix 2, wherein the pipe diameters of the plurality of parallel flow paths are graded so as to become thicker as the distance from the inlet flow path increases.
(Appendix 4) The heat exchanger according to Appendix 2, wherein the volume of the header is graded so as to increase as the distance from the inlet flow path increases.
(Appendix 5) The heat exchanger according to Appendix 3 or Appendix 4, which is located below the inlet flow path and has a recess formed in the bottom surface of the header.
(Supplementary note 6) The heat exchanger according to any one of Supplementary note 2 to Supplementary note 5, wherein a plurality of inlet flow paths are provided.
(Appendix 7) The heat exchanger according to Appendix 6, wherein fine particle droplets are sprayed corresponding to the plurality of inlet flow paths.
(Appendix 8) The heat exchanger according to any one of the appendices 1 to 7, the fan that blows air so as to pass through the heat exchanger, and the heat exchanger are sprayed with fine particle droplets. A cooling tower that includes a spray nozzle and a pipe connected to the heat exchanger.
(Supplementary note 9) The cooling tower according to Supplementary note 8, wherein the spray nozzle sprays the fine particle-like droplets onto the heat exchanger in a direction inclined with respect to the direction of gravity.
(Appendix 10) The heat exchanger is installed so that the plurality of parallel flow paths of the heat exchanger are substantially parallel to the direction of gravity, and the spray nozzle obliquely downwards the heat. The cooling tower according to Appendix 8, wherein the fine particle droplets are sprayed onto the exchanger.
(Appendix 11) The fan causes an air volume gradient with respect to the plurality of parallel flow paths of the heat exchanger, and the spray nozzle uses the heat exchanger so that the spray distribution amount is proportional to the air volume gradient. The cooling tower according to any one of Supplementary note 8 to Supplementary note 10, which is installed with an inclination with respect to the plurality of parallel flow paths of the above.
(Supplementary note 12) The cooling according to any one of Supplementary note 8 to Supplementary note 11, wherein the spray nozzle is installed so that the maximum point of the nozzle flow rate distribution is located below the inlet flow path of the heat exchanger. Tower.

The present invention has been described above as a model example of the above-described embodiments and examples. However, the present invention is not limited to the above-described embodiments and examples. That is, the present invention can apply various aspects that can be understood by those skilled in the art within the scope of the present invention.

This application claims priority on the basis of Japanese application Japanese Patent Application No. 2015-251191 filed on December 24, 2015, the entire disclosure of which is incorporated herein by reference.

1 Inlet flow path 2, 2a, 2b, 2d Header 2c Indentation 3 Multiple flow paths 3a, 3b, 3c Piping 4 Fins 5, 105 Heat exchanger 6, 106 Spray nozzle 7 Pressure gauge 8 Flow control valve 9, 109 Fan 10 Pump 11 Water storage tank 12a, 12b Piping 13 Housing 20 Sealed cooling tower 21 Server room 22 Server rack 23 Heat receiving part 24 Liquid pipe 25 Steam pipe 30 Data center 103 Parallel flow path 100 Cooling tower

Claims (9)

With a fan that blows air,
A plurality of parallel flow paths in which fine particle droplets are sprayed, and a plurality of parallel flow paths installed at an inclination in which the fluid to be cooled can circulate in the direction of gravity or the fluid after condensation can be circulated by utilizing gravity. Including heat exchanger and
A spray nozzle that sprays fine particles of droplets onto the heat exchanger, and is installed so that the maximum point of the nozzle flow distribution is located directly below the inlet flow path into which the fluid to be cooled of the heat exchanger flows. With the spray nozzle that is
A cooling tower that includes piping connected to the heat exchanger. The cooling tower according to claim 1, wherein the heat exchanger further includes a header for branching a fluid to be cooled flowing from the inlet flow path into the plurality of parallel flow paths. The cooling tower according to claim 2, wherein the pipe diameters of the plurality of parallel flow paths of the heat exchanger are sloped so as to become thicker as the distance from the inlet flow path increases. The cooling tower according to claim 2, wherein the volume of the header of the heat exchanger is graded so as to increase as the distance from the inlet flow path increases. The cooling tower according to claim 3 or 4, wherein a recess is formed in the bottom surface of the header, which is located below the inlet flow path of the heat exchanger. The cooling tower according to any one of claims 2 to 5, wherein the heat exchanger is provided with a plurality of inlet flow paths into which the fluid to be cooled flows. The cooling tower according to any one of claims 1 to 6, wherein the spray nozzle sprays the fine particle-like droplets onto the heat exchanger in a direction inclined with respect to the direction of gravity. The heat exchanger is installed so that the plurality of parallel flow paths of the heat exchanger are substantially parallel to the direction of gravity.
The cooling tower according to any one of claims 1 to 6, wherein the spray nozzle sprays the fine particle-like droplets diagonally downward onto the heat exchanger. The fan causes an airflow gradient for the plurality of parallel channels of the heat exchanger.
7. The cooling tower described in.

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