OUTDOOR UNIT OF AIR CONDITIONER

- NEC Corporation

An outdoor unit in which, by installing small fans near the ventilation surface of a heat exchanger so as to be parallel with the ventilation surface of the heat exchanger and arranging the small fans so that the ventilation areas of the small fans and the heat exchanger are equivalent, the number of small fans that can be installed is maximized while reducing power consumption.

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Description
BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a cooling device for an electronic device. In particular, it relates to an outdoor unit of an air conditioner for a data center using a refrigeration cycle.

Description of Related Art

An air conditioner that uses a refrigeration cycle, which is generally called a packaged air conditioner, is used for cooling a server room of a data center.

The outdoor unit of the air conditioner uses a large fan about 600 mm in diameter driven by an AC motor, with one or two fans being installed horizontally at the upper part of the housing. Further, the heat exchanger is installed obliquely inside the housing in order to secure a heat dissipation area. The structure is such that air is taken in from the lower part of the housing and exhausted from the upper part of the housing (see Japanese Unexamined Patent Application Publication No. S61-128074 and Japanese Unexamined Patent Application Publication No. 2014-163530).

However, the aforementioned structure has the following issues.

In recent years, as a measure to save power in data centers, the use of DC power sources in data centers has been promoted, and so there is a demand for air conditioners to use DC power sources. However, with regard to large fans such as those used in conventional outdoor units, only those driven by AC motors are available. Therefore, in order to make outdoor units run on a DC power source, it is required to use small fans having a diameter of about 300 mm or less that can be driven by a general DC motor.

An object of the present invention is, for example, even when a small fan is used in an outdoor unit of an air conditioner used for a data center, to make the fan power equal to or less than that when a large fan is used while maintaining the heat dissipation performance of the outdoor unit.

SUMMARY OF THE INVENTION

In order to solve the aforementioned problem, the outdoor unit of an air conditioner according to the present invention is provided with a heat exchanger and a plurality of fans installed side by side in the vicinity of the ventilation surface of the heat exchanger.

Effect of the Invention

According to the present invention, for example, in an outdoor unit of an air conditioner used for applications such as for data centers, even when small fans are used, it is possible to make the power consumption equal to or less than that when a large fan is used while maintaining the heat dissipation performance of the outdoor unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing an outdoor unit of an air conditioner according to the minimum configuration of the present invention.

FIG. 2 is a front view showing a cross section of an outdoor unit of an air conditioner according to the first embodiment of the present invention.

FIG. 3 is a graph comparing fan power required to obtain an air volume for dissipating a certain amount of heat in an outdoor unit of an air conditioner.

DETAILED DESCRIPTION OF THE INVENTION

An outdoor unit according to the minimum configuration example of the present invention will be described with reference to FIG. 1.

Fans 1 and a heat exchanger 2 are provided, with a plurality of the fans 1 being installed side by side in the vicinity of a ventilation surface 2a of the heat exchanger 2.

According to the aforementioned configuration, the required air volume can be supplied to the heat exchanger 2 by the plurality of fans 1, and the heat of the refrigerant vapor is dissipated to the outside air supplied by the fans 1 via the heat exchanger 2, whereby the refrigerant vapor condenses and phase changes to a liquid state. The air volume required for the heat dissipation accompanying this phase change can be supplied by the plurality of fans 1, and the driving power of the fans can be reduced as compared with the case where the required air volume is supplied by a single fan.

First Embodiment

The first embodiment according to the present invention will be described. FIG. 2 shows a conceptual diagram of a cross section of the outdoor unit according to the present embodiment as viewed from the front.

The structure of the outdoor unit 10 according to the present embodiment is provided with a housing 100, a plurality of heat exchangers 200, a plurality of small fans 300, and a plurality of guide blades 400.

The housing 100 is provided with an intake port 110 at the lower part and an exhaust port 120 at the upper part. The heat exchangers 200 are installed obliquely inside the housing 100. In FIG. 2, the heat exchangers are installed inclined with respect to the flow directions of the intake air indicated by the arrows A and the exhaust air indicated by the arrows B in the figure.

The small fans 300 are installed near the ventilation surface of each of the heat exchangers 200 (the surface corresponding to the reference numeral 2a in FIG. 1) so as to be parallel to the ventilation surface of each of the heat exchanger 200. A plurality of the small fans 300 are arranged side by side so that the entire ventilation area of the small fans 300 and the entire ventilation area of the heat exchangers 200 are equivalent.

That is, the small fans 300 are arranged so as to cover the entire ventilation surfaces 2a of the heat exchangers 200. Since the appearance of the small fans 300 (the shape of the frame surrounding the rotation range of the blades) is generally square in the axial direction, a plurality are arranged in a matrix, being lined up side by side not only in the paper direction of FIG. 2, but also in the direction orthogonal to FIG. 2 and the paper surface, in accordance with the planar shape of the heat exchanger 200. Further, the small fans 300 of the embodiment are each driven by a DC motor (not shown) operated by a DC power supply supplied to various devices in a data center or the like.

The guide blades 400 are installed on the intake side and the exhaust side of the small fans 300. The installation angle of each of the guide blades 400 can be changed depending on the installation position so that the ventilation resistance from the intake port 110 to the exhaust port 120 of each of the plurality of small fans 300 is the same. That is, each of the guide blades 400 has a structure capable of making the ventilation resistance uniform by individually adjusting the angle with respect to the direction in which air flows between the intake port 110 and the exhaust port 120 (the directions of arrows A and B).

Further, one guide blade 400 (for example, reference numeral 400A in FIG. 2) and another guide blade 400 (for example, reference numeral 400B in FIG. 2) which are adjacent are arranged in units of two adjacent fans 300 (for example, reference numerals 300A and 300B in FIG. 2), thereby adjusting the ventilation resistance within the range in which air is supplied from these two fans 300. Instead of controlling the angle of the guide blade 400, the air volume may be adjusted by controlling the rotation speed of each fan 300 individually or by controlling a plurality of fans 300 corresponding to each heat exchanger 200.

The number, size, shape, and the like of each of the heat exchangers 200, the small fans 300, and the guide blades 400 of the outdoor unit 10 are not limited. Although the heat exchangers 200 and the small fans 300 are installed in a V shape when viewed from the front of the housing 100, installation in a W shape or the like is also possible. Although the small fans 300 are installed on the exhaust side of the heat exchangers 200, the small fans 300 may be installed on the intake side. The guide blades 400 are installed on the intake side and the exhaust side of the small fans 300, but may also be installed on either side only.

Although not shown, also provided are constituent members of the refrigerant flow path, such as piping like vapor piping and liquid piping for supplying and discharging the refrigerant to the plurality of heat exchangers 200, and a refrigerant tank. Also provided are electronic components such as power cables and electronic boards. The plurality of heat exchangers 200 are connected in parallel between the liquid piping supplying the refrigerant and the vapor piping discharging the refrigerant, being constituted so that the heat exchange medium is supplied and discharged to each, respectively.

In addition, a pump for circulating the refrigerant liquid, a compressor for raising the temperature of the refrigerant vapor, and the like may be provided.

The operation of the outdoor unit having the above configuration will be explained.

When the outdoor unit 10 is operated, the small fans 300 start rotating. Thereby, the outside air is sucked into the inside of the housing 100 through the intake port 110 provided in the lower part of the housing 100. Next, the outside air passes through the flow path formed by the guide blades 400 and the heat exchangers 200. Finally, the outside air is discharged to the outside of the housing 100 through the exhaust port 120 provided at the upper part of the housing 100.

The refrigerant liquid heated by the indoor unit evaporates and undergoes a phase change to refrigerant vapor. The refrigerant vapor moves from the indoor unit to the outdoor unit 10 through the vapor piping and reaches the heat exchangers 200 installed inside the housing 100. The refrigerant vapor dissipates heat to the outside air via the heat exchangers 200, condenses and phase-changes back into the refrigerant liquid. The refrigerant liquid moves from the outdoor unit 10 to the indoor unit through the liquid piping. In this way, the room is cooled by transferring heat using the circulation of the refrigerant and phase changes thereof.

The effect achieved by the above operation will be explained.

Installing the small fans 300 near the ventilation surface of the heat exchangers 200 so as to be parallel to the ventilation surface of the heat exchangers 200 increases the number of fans as compared with the case where the small fans 300 are installed horizontally at the upper part of the housing 100. Thereby, the rotation speed of each fan can be reduced and the total fan power can be reduced.

The air volume V per fan 300 is proportional to the fan rotation speed, and is inversely proportional to the number of fans N when the total air volume (total required air volume) is determined. Further, the electric power per fan is proportional to the fan rotation speed to the third power. Therefore, as shown in Equation (1), the total fan power W is inversely proportional to the square of the number of fans N.


W∝V3×N∝N−3×N∝N−2  (1)

From Equation (1), it can be seen that the total fan power W can be reduced by increasing the number of fans N.

In the first embodiment, a plurality of the small fans 300 are installed near the ventilation surface of each heat exchanger 200 so as to be parallel to the ventilation surface of each heat exchanger 200, being arranged side by side so that the ventilation areas of the small fans 300 and the heat exchangers 200 are equivalent. As a result, the number of small fans installed can be increased by 1.5 times as compared with the case of installing the fans in the upper part (exhaust port side) of the housing as adopted in a general outdoor unit.

Further, by changing the installation angle of the guide blades 400 depending on the installation position, the ventilation resistance from each intake port 110 to the exhaust port 120 of each small fan 300 is made as uniform as possible (preferably the same). As a result, the total fan power can be reduced by making the wind speed of the outside air supplied to the heat exchangers 200 uniform and improving the heat dissipation performance.

FIG. 3 is a graph of an example of comparing required fan power under the conditions of the dimensions and arrangement of the housing and heat exchanger except for the fans, and the intake/exhaust positions being the bottom intake/top exhaust in order to obtain the air volume (160 m3/min) for dissipating the heat equivalent to 40 kW by the outdoor unit. When using a large fan, the fan power is 1.2 kW (bar graph with horizontal line hatching). In contrast, when the small fans are used side by side at the upper part of the housing, the fan power is 2.3 kW (bar graph with diagonal line hatching), which is about twice as much as the conventional one.

As a result, the total fan power W has been halved to 1.1 kW (shown in the bar graph in FIG. 3 with the wavy line hatching), which is the same as the conventional one.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, with design changes and the like within a range that does not deviate from the gist of the present invention also being included.

By being able to reduce the fan power during the use of small fans, the present invention can be effectively applied to an outdoor unit that uses a DC power supply.

While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.

Priority is claimed on Japanese Patent Application No. 2020-152354, filed Sep. 10, 2020, the content of which is incorporated herein by reference.

Claims

1. An outdoor unit of an air conditioner comprising a heat exchanger, and a plurality of the fans installed side by side in a vicinity of the ventilation surface of the heat exchanger.

2. The outdoor unit of an air conditioner according to claim 1, wherein the fans and the heat exchanger are obliquely installed when viewed from the front of a housing, and the fans are located near the ventilation surface of the heat exchanger so that the ventilation area of the fans and the ventilation area of the heat exchanger are equivalent.

3. The outdoor unit of an air conditioner according to claim 1, further comprising a guide blade that changes the wind direction, wherein the installation angle of the guide blade is changed depending on the installation position so that the ventilation resistance from the intake port to the exhaust port of the outdoor unit is the same for each of the plurality of fans.

4. The outdoor unit of an air conditioner according to claim 1, wherein the number of fans installed is determined so that the total fan power is equal to or less than an allowable value.

5. The outdoor unit of an air conditioner according to claim 1, wherein each of the fans is driven by a DC power source.

6. An outdoor unit of an air conditioner comprising:

a heat exchanger that exchanges heat between air to be cooled and a refrigerant; and
a plurality of fans arranged along a ventilation surface intersecting the passage direction of the air to be cooled in the heat exchanger.

7. The outdoor unit of an air conditioner according to claim 6, wherein the entire ventilation surface of the heat exchanger is covered by the plurality of fans.

Patent History
Publication number: 20220074607
Type: Application
Filed: Sep 2, 2021
Publication Date: Mar 10, 2022
Applicant: NEC Corporation (Tokyo)
Inventors: Mahiro HACHIYA (Tokyo), Minoru YOSHIKAWA (Tokyo)
Application Number: 17/464,907
Classifications
International Classification: F24F 1/38 (20060101);