WO2018173854A1

WO2018173854A1 - Cooling system, cooling method, and program

Info

Publication number: WO2018173854A1
Application number: PCT/JP2018/009717
Authority: WO
Inventors: 寿人佐久間; 貴文棗田; 吉川　実
Original assignee: 日本電気株式会社
Priority date: 2017-03-22
Filing date: 2018-03-13
Publication date: 2018-09-27
Also published as: JP2020106151A

Abstract

[Problem] To reduce the possibility of liquid compression occurring in a cooling system. [Solution] A cooling system comprises: an evaporation unit that evaporates refrigerant; a compressor that compresses the refrigerant evaporated with the evaporation unit; a condensation unit that condenses the refrigerant compressed by the compressor; an expansion valve that is provided in the channel from the condensation unit to the evaporation unit and that reduces the pressure of the refrigerant; and a heat exchanger that performs heat exchange between the refrigerant flowing from the evaporation unit to the compressor and the refrigerant flowing in the channel from the compressor to the condensation unit.

Description

Cooling system, cooling method and program

The present invention relates to a cooling system, a cooling method, and a program.

A technique for avoiding liquid compression or wet compression in which a liquid-phase refrigerant is mixed in a compressor of a cooling facility has been proposed. For example, Patent Document 1 discloses a refrigerant circuit having a configuration for preventing wet compression of a compressor. In this refrigerant circuit, a bypass circuit is provided in which a part of the refrigerant flowing through the condenser is flowed out of the condenser and then returned to the condenser. The bypass circuit is provided with a receiver, and the receiver is provided with a refrigerant passage from the expansion valve to the evaporator.
In this refrigerant circuit, in order to prevent wet compression of the compressor, the receiver temperature is brought close to the target receiver temperature by adjusting the amount of refrigerant flowing from the condenser to the receiver by means of an adjusting valve. The refrigerant from the expansion valve to the evaporator is heated by the adjustment by the adjustment valve.

Japanese Patent No. 3956754

In the refrigerant circuit described in Patent Document 1, when the temperature of the refrigerant flowing from the condenser to the receiver is low, the temperature of the receiver cannot be brought close to the target receiver temperature. For this reason, the refrigerant flowing from the expansion valve to the evaporator cannot be sufficiently heated, and liquid compression may occur. For example, when the condenser is configured as an outdoor unit and the outside air temperature is low, and when the condenser has a large cooling capacity such as a large condenser, the temperature of the refrigerant flowing from the condenser to the receiver is low. This may cause liquid compression.

The object of the present invention is to provide a cooling system, a cooling method, and a program capable of solving the above-described problems.

According to the first aspect of the present invention, the cooling system includes an evaporator that evaporates the refrigerant, a compressor that compresses the refrigerant evaporated in the evaporator, and a condenser that condenses the refrigerant compressed by the compressor. An expansion valve that is provided in a flow path from the condensing unit to the evaporation unit to depressurize the refrigerant, a refrigerant that flows through the flow channel from the evaporation unit to the compressor, and from the compressor to the condensing unit A heat exchanger that exchanges heat with the refrigerant flowing through the flow path.

According to the second aspect of the present invention, the cooling method includes: a refrigerant flowing through a flow path from an evaporation unit that evaporates the refrigerant to a compressor that compresses the refrigerant evaporated in the evaporation unit; and the compressor to the compressor Heat exchange between the refrigerant flowing through the flow path to the condensing unit for condensing the refrigerant compressed in step (b).

According to the third aspect of the present invention, the program causes the computer to transmit a refrigerant flowing in a flow path from an evaporation unit that evaporates the refrigerant to a compressor that compresses the refrigerant evaporated in the evaporation unit, and the compressor from the compressor. It is a program for controlling heat exchange between refrigerants flowing through a flow path to a condensing unit for condensing refrigerant compressed by a compressor.

According to the present invention, the possibility of liquid compression can be further reduced.

It is a schematic block diagram which shows the 1st example of the apparatus structure of the cooling system which concerns on embodiment of this invention. It is a figure which shows the example of the process sequence which the controller which concerns on embodiment of this invention controls the opening degree of a bypass valve. It is a schematic block diagram which shows the 2nd example of the apparatus structure of the cooling system which concerns on embodiment of this invention. It is a schematic block diagram which shows the 3rd example of the apparatus structure of the cooling system which concerns on embodiment of this invention. It is a schematic block diagram which shows the 3rd example of the apparatus structure of the cooling system which concerns on embodiment of this invention. It is a schematic block diagram which shows the example of the apparatus structure of the cooling system which performs heat exchange between the flow path from an evaporation part to a compressor, and the flow path from a condensation part to an expansion valve. It is a schematic block diagram which shows the structural example of the controller which concerns on embodiment of this invention. It is a figure which shows the example of the minimum structure of the cooling system which concerns on this invention.

Hereinafter, although embodiment of this invention is described, the following embodiment does not limit the invention concerning a claim. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.
FIG. 1 is a schematic block diagram illustrating a first example of a device configuration of a cooling system according to an embodiment of the present invention. In the example of FIG. 1, the cooling system 1 includes an evaporator 101, a compressor 102, a condenser 103, an expansion valve 104, a heat exchanger 301, a bypass valve 302, a temperature sensor 303, and a pressure sensor 304. And a controller 305.

The cooling system 1 is a system that supplies cold heat. The application of the cooling system 1 is not limited to a specific application. For example, the cooling system 1 may be used for cooling the computer by installing the cooling system 1 in the data center. Alternatively, the cooling system 1 may be installed in a living environment such as a home or a workplace, and cool air may be supplied to enhance the comfort of the living environment.

In particular, there may be a case where the cooling system 1 operates throughout the year, such as when the cooling system 1 is installed in a data center. In this case, if the condensing unit 103 is configured as an outdoor unit, the temperature of the refrigerant flowing through the condensing unit 103 may be low in winter. The cooling system 1 can reduce the possibility that liquid compression occurs even in such a case. In this respect, the cooling system 1 can reduce the possibility of liquid compression as compared with the case where liquid compression is prevented using the refrigerant flowing through the condenser.
The cooling system 1 may be configured as a system dedicated to cooling, or may be configured as a system capable of switching between cooling and heating.

The evaporating unit 101 is provided in the cold supply target space by being configured as an indoor unit, for example, and evaporates liquid phase refrigerant flowing into the evaporating unit 101 itself. The evaporating refrigerant exchanges heat with the ambient air to absorb the heat of vaporization, thereby cooling the ambient air. The evaporation unit 101 supplies cold air to the outside of the indoor unit by blowing the ambient air to the outside of the evaporation unit 101.

The compressor 102 compresses the gas-phase refrigerant evaporated in the evaporation unit 101. The refrigerant is compressed by the compressor 102 to become a relatively high-temperature and high-pressure gas-phase refrigerant.
The condensing unit 103 is configured as an outdoor unit, for example, and condenses the gas-phase refrigerant compressed by the compressor 102. The condensing refrigerant exchanges heat with the surrounding air and releases condensation heat.
The expansion valve 104 is provided in the refrigerant flow path from the condensing unit 103 to the evaporation unit 101, and depressurizes the refrigerant flowing through the expansion valve 104 itself. When the expansion valve 104 depressurizes the refrigerant, the refrigerant easily evaporates in the evaporation unit 101.
A compression refrigeration cycle is executed in a refrigerant circuit combining the evaporator 101, the compressor 102, the condenser 103, and the expansion valve 104.

The heat exchanger 301 exchanges heat between the refrigerant flowing through the refrigerant flow path from the evaporation unit 101 to the compressor 102 and the refrigerant flowing through the refrigerant flow path from the compressor 102 to the condensing unit 103.
Since the refrigerant is compressed by the compressor 102 and rises in temperature, the refrigerant flowing out from the compressor 102 has a higher temperature than the refrigerant flowing into the compressor 102 and the refrigerant flowing out from the compressor 102. Therefore, in the heat exchange in the heat exchanger 301, the refrigerant flowing through the refrigerant flow path from the evaporation unit 101 to the compressor 102 (refrigerant flowing into the compressor 102) is heated. Since the refrigerant flowing into the compressor 102 is heated, the possibility that the refrigerant is condensed can be reduced, and the possibility that liquid compression occurs can be reduced.

In addition, the heat exchanger 301 performs heat exchange using the refrigerant that has flowed out of the compressor 102 and before flowing into the condensing unit 103, so that it is not affected by the temperature drop of the refrigerant in the condensing unit 103. Heat exchange can be performed. In this regard, the cooling system 1 can reduce the possibility of liquid compression even when the temperature of the refrigerant flowing through the condensing unit 103 is low. As described above, in this respect, the cooling system 1 can reduce the possibility of liquid compression occurring as compared with the case where liquid compression is prevented using the refrigerant flowing through the condenser.
In order to reduce the pressure loss of the refrigerant in the heat exchanger 301, a shell and tube heat exchanger or a fin and tube heat exchanger may be used as the heat exchanger 301.

The bypass valve 302 is provided in a bypass channel that bypasses the heat exchanger 301, and adjusts the amount of refrigerant flowing through the bypass channel. The bypass valve 302 is configured using a flow rate adjustment valve. The bypass flow path that bypasses the heat exchanger 301 is provided in at least one of the flow path from the evaporation unit 101 to the compressor 102 and the flow path from the compressor 102 to the condensation unit 103.

In the first embodiment, a case where the bypass path is provided in the flow path from the evaporator 101 to the compressor 102 will be described as an example. The case where the bypass path is provided in the flow path from the compressor 102 to the condensing unit 103 will be described later. Furthermore, the bypass flow path may be provided in both the flow path from the evaporation unit 101 to the compressor 102 and the flow path from the compressor 102 to the condensing unit 103. In this case, a bypass valve 302 may be provided in each of the two bypass flow paths.
The bypass valve 302 adjusts the flow rate of the refrigerant gas flowing through the heat exchanger 301 by changing the opening degree of the bypass valve 302 itself according to the control of the controller 305. By adjusting the refrigerant gas flow rate, the bypass valve 302 adjusts the heat exchange amount in the heat exchanger 301.

The temperature sensor 303 is provided on at least one of the inlet side (suction side) and the outlet side (discharge side) of the compressor 102 and measures the temperature of the refrigerant. The pressure sensor 304 is provided on at least one of the inlet side and the outlet side of the compressor and measures the pressure of the refrigerant.
In the first embodiment, a case where the temperature sensor 303 and the pressure sensor 304 are provided on the inlet side of the compressor 102 will be described as an example. The case where the temperature sensor 303 and the pressure sensor 304 are provided on the outlet side of the compressor 102 will be described later. Further, either one or both of the temperature sensor 303 and the pressure sensor 304 may be provided on both the inlet side and the outlet side of the compressor 102. Further, one of the temperature sensor 303 and the compressor 102 may be provided on the inlet side of the compressor 102, and the other may be provided on the outlet side of the compressor 102.

The controller 305 controls the amount of heat exchange in the heat exchanger 301 based on the pressure measurement value of the pressure sensor 304 and the temperature measurement value of the temperature sensor 303. Specifically, the controller 305 controls the amount of heat exchange in the heat exchanger 301 by controlling the opening degree of the bypass valve 302 based on the pressure measurement value of the pressure sensor 304 and the temperature measurement value of the temperature sensor 303. .
More specifically, the controller 305 calculates the degree of superheat of the refrigerant from the pressure measurement value and the temperature measurement value. The degree of superheat here is a temperature rise from the saturation temperature. Therefore, the degree of superheat is obtained by subtracting the saturation temperature from the target temperature.
When the superheat degree of the refrigerant is larger than the predetermined range, the controller 305 increases the opening degree of the bypass valve 302 and increases the amount of refrigerant flowing through the bypass valve 302, thereby reducing the heat exchange amount.
When the degree of superheat of the refrigerant is smaller than the predetermined range, the controller 305 increases the heat exchange amount by reducing the amount of refrigerant flowing through the bypass valve 302 by reducing the opening degree of the bypass valve 302.
When the superheat degree of the refrigerant is within a predetermined range, the controller 305 suppresses the change in the heat exchange amount by maintaining the opening degree of the bypass valve 302 and maintaining the amount of refrigerant flowing through the bypass valve 302.

In this way, the controller 305 avoids liquid compression by keeping the degree of superheat of the refrigerant gas sucked into the compressor 102 within a predetermined range.
The lower limit value of the superheat degree in the predetermined range is provided to avoid liquid compression by the compressor 102. This lower limit is set to a degree of superheat at which the refrigerant is considered to contain no liquid refrigerant.
For example, the controller 305 may set the lower limit value of the superheat degree to a value equal to or higher than the value obtained by adding 3 ° C. to the saturated steam temperature.

The upper limit value of the superheat degree in the predetermined range is that the refrigerant flowing into the compressor 102 is overheated, the efficiency of the cooling system 1 is lowered, and the temperature of the compressor 102 or the refrigerant temperature reaches the usable temperature upper limit. In order to prevent the cooling system 1 from stopping. Generally, the greater the degree of superheat, the greater the work required for adiabatic compression of the refrigerant. Therefore, the greater the heating, the greater the work of the compressor, causing a reduction in efficiency.
For example, the controller 305 may set the upper limit value of the superheat degree to 10 ° C.

The refrigerant that has flowed into the compressor 102 from the evaporation unit 101 rises in temperature by being compressed by the compressor 102. For this reason, if the temperature of the refrigerant flowing into the compressor 102 is Tin and the temperature of the refrigerant flowing out of the compressor 102 is Tout, Tin <Tout. Therefore, the cooling system 1 includes a heat exchanger 301 between the inlet side and the outlet side of the compressor 102. The heat exchanger 301 causes heat exchange between the refrigerant flowing into the compressor 102 and the refrigerant flowing out of the compressor 102, thereby increasing the temperature of the refrigerant flowing into the compressor 102 and avoiding liquid compression. .

However, there is a possibility that the refrigerant is overheated only by heat exchange with the heat exchanger 301. When the temperature of the refrigerant flowing into the compressor 102 increases due to heat exchange of the refrigerant in the heat exchanger 301, the temperature of the refrigerant flowing out of the compressor also increases. As a result, the temperature difference between the refrigerant that has flowed out of the evaporator 101 and the refrigerant that has flowed out of the compressor 102, which has a substantially constant temperature, increases, and the amount of heat exchange in the heat exchanger 301 increases. Then, the temperature of the refrigerant flowing into the compressor further increases, and the temperature of the refrigerant flowing out from the compressor further increases. This further increases the amount of heat exchange in the heat exchanger 301. As a result, the degree of superheat continues to increase, which can result in increased compressor work, refrigerant breakdown, or compressor failure.

Therefore, the bypass valve 302 adjusts the opening degree of the bypass valve 302 according to the control of the controller 305 to keep the degree of superheat within an appropriate range. The controller 305 calculates the degree of superheat of the refrigerant from the temperature measurement value of the temperature sensor 303 and the pressure measurement value of the pressure sensor 304, and adjusts the opening degree of the bypass valve 302 according to the value.

Control performed by the controller 305 will be described with reference to FIG.
FIG. 2 is a diagram illustrating an example of a processing procedure in which the controller 305 controls the opening degree of the bypass valve 302. In step S <b> 1, the controller 305 acquires the compressor inlet temperature measurement value T by the temperature sensor 303 and the compressor inlet pressure measurement value P by the pressure sensor 304. The measured value T of the compressor inlet temperature indicates a measured value of the refrigerant temperature at the inlet of the compressor 102. The measured value P of the compressor inlet pressure indicates a measured value of the refrigerant pressure at the inlet of the compressor 102.

In step S2, the controller 305 acquires the saturated vapor temperature of the refrigerant at the compressor inlet pressure measurement value P. The relationship between the pressure and the saturated steam temperature is known for each refrigerant, and the controller 305 obtains the saturated steam temperature by applying the compressor inlet pressure measurement value P to this relationship.
The method by which the controller 305 acquires the relationship between the pressure and the saturated steam temperature is not limited to a specific method. For example, the controller 305 may access a database that stores the relationship between pressure and saturated steam temperature in a tabular format. This database may be provided inside the controller 305, or may be configured as a device different from the controller 305. Alternatively, the controller 305 may store in advance a logical expression or an approximate expression indicating the relationship between the pressure and the saturated steam temperature.

In step S3, the controller 305 calculates the degree of superheat by subtracting the saturated steam temperature from the compressor inlet pressure measurement value P.
In step S4, the controller 305 compares the degree of superheat calculated in step S3 with a predetermined range. For example, the controller 305 compares the degree of superheat calculated in step S3 with a range of 3 ° C. to 10 ° C.
If it is determined that the degree of superheat is greater than the predetermined range (step S4: greater than the range), the process proceeds to step S5. When it is determined that the degree of superheat is within a predetermined range (step S4: within range), the controller 305 returns to step S1. In this case, the controller 305 does not change the opening degree of the bypass valve 302. That is, the controller 305 maintains the opening degree of the bypass valve 302. When it is determined that the degree of superheat is smaller than the predetermined range (step S4: smaller than the range), the process proceeds to step S6.

In step S5, the controller 305 increases the opening degree of the bypass valve 302.
For example, the controller 305 may increase the opening degree of the bypass valve 302 by a predetermined opening degree change amount every time step S5 is executed. Alternatively, the controller 305 calculates the opening increase amount of the bypass valve 302 based on the difference between the degree of superheat calculated in step S3 and a predetermined range value (for example, a predetermined lower limit value). You may make it do.
When the controller 305 increases the opening degree of the bypass valve 302, the ratio of the refrigerant flowing through the bypass flow passage out of the refrigerant flowing out from the evaporation unit 101 increases, and the compressor is transferred from the evaporation unit 101 via the heat exchanger 301. The amount of refrigerant flowing into 102 decreases. As a result, the amount of heat exchange in the heat exchanger 301 is reduced, and the temperature of the refrigerant flowing into the compressor 102 is reduced as compared to before the opening degree of the bypass valve 302 is increased.

In step S6, the controller 305 decreases the opening degree of the bypass valve 302.
For example, the controller 305 may decrease the opening degree of the bypass valve 302 by a predetermined opening degree change amount every time step S5 is executed. Alternatively, the controller 305 calculates a decrease in the opening degree of the bypass valve 302 based on the difference between the degree of superheat calculated in step S3 and a value in a predetermined range (for example, an upper limit value in the predetermined range). You may make it do.
When the controller 305 decreases the opening degree of the bypass valve 302, the ratio of the refrigerant flowing through the bypass flow path out of the refrigerant flowing out from the evaporation unit 101 is reduced, and the compressor is transferred from the evaporation unit 101 via the heat exchanger 301. The amount of refrigerant flowing into 102 increases. As a result, the amount of heat exchange in the heat exchanger 301 increases, and the temperature of the refrigerant flowing into the compressor 102 rises compared to before the opening degree of the bypass valve 302 is increased.

As described above, the heat exchanger 301 causes heat exchange between the refrigerant flowing through the flow path from the evaporation unit 101 to the compressor 102 and the refrigerant flowing through the flow path from the compressor 102 to the condensing unit 103. .
Thereby, the temperature of the refrigerant | coolant which flows in into the compressor 102 can be raised, and possibility that liquid compression will arise can be reduced.
In particular, the heat exchanger 301 performs heat exchange using the refrigerant that has flowed out of the compressor 102 and before flowing into the condensing unit 103 without being affected by the temperature drop of the refrigerant in the condensing unit 103. Heat exchange can be performed. In this respect, the cooling system 1 can further reduce the possibility that liquid compression occurs as compared with the case where liquid compression is prevented using the refrigerant flowing through the condenser.

The controller 305 controls the heat exchange amount in the heat exchanger based on the pressure measurement value and the temperature measurement value on at least one of the inlet side and the outlet side of the compressor 102.
Thereby, in the cooling system 1, possibility that liquid compression will arise can be reduced and it can avoid that the temperature of the refrigerant | coolant which flows in into the compressor 102 becomes high too much. By avoiding the temperature of the refrigerant flowing into the compressor 102 from becoming too high, a decrease in the efficiency of the cooling system 1 can be avoided, and the possibility that the cooling system 1 stops due to an increase in the refrigerant temperature is reduced. be able to. Furthermore, it is possible to reduce the possibility that the cooling system 1 breaks down due to a rise in the refrigerant temperature.

In addition, the controller 305 compares the degree of superheat of the refrigerant calculated from the pressure measurement value by the pressure sensor 304 and the temperature measurement value by the temperature sensor 303 with a predetermined range. When the superheat degree is larger than the predetermined range, the controller 305 decreases the heat exchange amount in the heat exchanger 301. When the degree of superheat is smaller than the predetermined range, the controller 305 increases the amount of heat exchange in the heat exchanger 301. When the degree of superheat is within a predetermined range, the controller 305 suppresses a change in the heat exchange amount.
Thereby, the controller 305 can reduce the possibility of liquid compression by a simple process of comparing the degree of superheat and a predetermined range, and the temperature of the refrigerant flowing into the compressor 102 becomes too high. You can avoid that.

The bypass valve 302 is a bypass channel that bypasses the heat exchanger 301 for at least one of the channel from the evaporator 101 to the compressor 102 and the channel from the compressor 102 to the condenser 103. Provided. The bypass valve 302 adjusts the amount of refrigerant flowing through the bypass flow path.
Thereby, in the cooling system 1, the heat exchange amount in the heat exchanger 301 can be controlled with a simple configuration in which the bypass path and the bypass valve 302 are provided in the refrigerant flow path.

The controller 305 controls the bypass valve 302 based on the pressure measurement value of the pressure sensor 304 and the temperature measurement value of the temperature sensor 303.
As a result, the cooling system 1 can control the amount of heat exchange in the heat exchanger 301 with a simple configuration in which the pressure sensor 304 and the temperature sensor 303 are provided in addition to the bypass path and bypass valve 302 described above.

Further, the controller 305 calculates the degree of superheat of the refrigerant from the pressure measurement value of the pressure sensor 304 and the temperature measurement value of the temperature sensor 303. When the degree of superheat is larger than the predetermined range, the controller 305 increases the amount of refrigerant flowing through the bypass valve 302. When the degree of superheat is smaller than the predetermined range, the controller 305 decreases the amount of refrigerant flowing through the bypass valve 302. When the degree of superheat is within a predetermined range, the controller 305 maintains the amount of refrigerant flowing through the bypass valve 302.
Thereby, the controller 305 can control the heat exchange amount in the heat exchanger 301 by a simple process of comparing the degree of superheat with a predetermined range and controlling the opening degree of the bypass valve 302 based on the comparison result. it can.

Variations in the configuration of the cooling system 1 will be described with reference to FIGS.
FIG. 3 is a schematic block diagram illustrating a second example of the device configuration of the cooling system 1. 3 differs from the case of FIG. 1 in that the temperature sensor 303 and the pressure sensor 304 are provided on the outlet side of the compressor 102. The rest is the same as in the case of FIG.
FIG. 4 is a schematic block diagram illustrating a third example of the device configuration of the cooling system 1. In the example of FIG. 1, the bypass flow path and the bypass valve 302 are provided in the flow path from the evaporation unit 101 to the compressor 102. On the other hand, in the example of FIG. 4, the bypass flow path and the bypass valve 302 are provided in the flow path from the compressor 102 to the condensing unit 103. The rest is the same as in the case of FIG.

FIG. 5 is a schematic block diagram illustrating a third example of the device configuration of the cooling system 1. In the example of FIG. 5, as in the case of FIG. 3, the temperature sensor 303 and the pressure sensor 304 are provided on the outlet side of the compressor 102. In the example of FIG. 5, as in the case of FIG. 4, the bypass flow path and the bypass valve 302 are provided in the flow path from the compressor 102 to the condensing unit 103. The rest is the same as in the case of FIG.
The control of the controller 305 in the configuration shown in FIGS. 3, 4, and 5 is the same as that in the configuration shown in FIG.

Since the pressure sensor 304 and the temperature sensor 303 are provided on the outlet side of the compressor 102 as in the configuration illustrated in FIG. 3 and the configuration illustrated in FIG. 5, the refrigerant is prevented from being liquefied in the compressor 102. The possibility of being able to be increased. Here, when the slope of the saturated vapor pressure line on the Mollier diagram of the refrigerant is smaller than the slope of the isentropic line, the compressor can be used even if no liquid phase refrigerant is contained when sucked into the compressor 102. As the refrigerant pressure increases at 102, a part of the refrigerant may be liquefied. On the other hand, liquid compression can be avoided by setting the degree of superheat on the outlet side of the compressor 102 within a certain range.

The bypass path and bypass valve 302 are provided in the flow path (high-pressure side flow path) from the compressor 102 to the condenser 103 as in the configuration shown in FIG. 4 and the configuration shown in FIG. When the pressure loss in the cooling system 1 is relatively large, the pressure loss in the entire cooling system 1 can be relatively small.
Here, the heat exchanger generally has a pressure loss. In the case of the cooling system 1 as well, it is generally considered that the pressure loss is smaller when the refrigerant passes through the bypass path than when the refrigerant passes through the heat exchanger 301. Therefore, in the configuration shown in FIG. 1 and the configuration shown in FIG. 3, a bypass path and a bypass valve 302 are provided in the flow path (low pressure side flow path) from the evaporation unit 101 to the compressor 102.
On the other hand, when the heat exchanger 301 is a shell-and-tube type heat exchanger or the like, when the pressure loss in the heat exchanger 301 is extremely small, or when the bypass valve 302 is relatively small, or when passing through the bypass valve 302 Is considered to be larger than the pressure loss when passing through the heat exchanger 301. In this case, the pressure loss in the entire cooling system 1 can be made relatively small by providing the bypass path and the bypass valve 302 in the high-pressure side flow path having a small influence on the performance of the pressure loss.

Here, the effects of the configuration of the cooling system 1 will be further described in comparison with the configuration shown in FIG.
FIG. 6 is a schematic block diagram illustrating an example of a device configuration of a cooling system that performs heat exchange between the flow path from the evaporation section to the compressor and the flow path from the condensation section to the expansion valve. A cooling system 900 illustrated in FIG. 6 includes an evaporation unit 901, a compressor 902, a condensing unit 903, an expansion valve 904, and a heat exchanger 911.

6, the evaporation unit 901 evaporates the refrigerant by performing heat exchange between the liquid-phase refrigerant flowing into the evaporation unit 901 and the ambient air. The compressor 902 compresses the gas-phase refrigerant evaporated in the evaporation unit 901. The condensing unit 903 condenses the refrigerant by causing heat exchange between the gas-phase refrigerant that has become high temperature and pressure due to compression and the ambient air. The expansion valve 904 depressurizes the liquid-phase refrigerant condensed in the condensing unit 903. When the refrigerant is depressurized by the expansion valve 904, the evaporating unit 901 easily evaporates.

The heat exchanger 911 is provided for the purpose of reducing the possibility of liquid compression by heating the refrigerant flowing into the compressor 902. The heat exchanger 911 exchanges heat between the gas-phase refrigerant flowing from the evaporation unit 901 to the compressor 902 and the liquid-phase refrigerant flowing from the condensing unit 903 to the expansion valve 904.

When the cooling system 900 is used for cooling the server in the data center, the evaporation unit 901 is configured as an indoor unit to lower the room temperature of the server room, and the condensing unit 903 is configured as an outdoor unit. In data centers, the introduction of outside air is limited in order to prevent dust, not only in summer when the outside air temperature is high and cooling is required, but also in winter when the outside air temperature is low. For this reason, it is conceivable to operate the cooling system 900 throughout the year.

When the outside air temperature is low, such as in winter, it is conceivable that the temperature of the refrigerant greatly decreases in the condensing unit 903. In this case, the temperature of the refrigerant flowing into the compressor 902 is not sufficiently increased by heat exchange in the heat exchanger 911, and liquid compression may occur. Even when the heat exchange performance of the condensing unit 903 is high, the temperature of the refrigerant flowing into the compressor 902 does not sufficiently increase due to the heat exchange in the heat exchanger 911, and liquid compression may occur.
In this case, as a method of avoiding liquid compression, the performance of the condensing unit 903 is lowered by reducing the number of rotations of the fan of the outdoor unit or by shutting off a part of the heat exchanger in the outdoor unit. It is conceivable to raise the temperature of the refrigerant liquid that comes out. However, in that case, the performance of the condenser 903 is not fully utilized, and the cooling capacity of the cooling system 900 is limited.

In contrast, in any of the configurations of FIGS. 1, 3, 4, and 5, the heat exchanger 301 of the cooling system 1 includes a refrigerant that flows from the evaporator 101 to the compressor 102, and a refrigerant that flows from the compressor 102 to the condenser 103. Heat exchange between the two. By causing the refrigerant before flowing into the condensing unit 103 to perform heat exchange, it is not affected by the temperature drop in the condensing unit 103. In this regard, in the cooling system 1, the temperature of the refrigerant flowing into the compressor 102 can be effectively increased, and the possibility of liquid compression occurring can be reduced.

Next, a configuration example of the controller 305 will be described with reference to FIG. The controller 305 may be configured using a computer such as a microcomputer.
FIG. 7 is a schematic block diagram illustrating a configuration example of the controller 305. In the example of FIG. 7, the controller 305 includes a CPU (Central Processing Unit) 311, a storage device 312, and an interface 313. The operation of the controller 305 is performed by the CPU 311 reading a program from the storage device 312 and executing it. The interface 313 performs input / output such as communication with other devices.
However, the controller 305 may have a configuration other than a configuration using a computer, such as a configuration using dedicated hardware.

Next, the minimum configuration of the present invention will be described with reference to FIG.
FIG. 8 is a diagram showing an example of the minimum configuration of the cooling system according to the present invention. A cooling system 10 illustrated in FIG. 8 includes an evaporation unit 11, a compressor 12, a condensing unit 13, an expansion valve 14, and a heat exchanger 15.
With this configuration, the evaporating unit 11 evaporates the refrigerant. The compressor 12 compresses the refrigerant evaporated in the evaporation unit 11. The condensing unit 13 condenses the refrigerant compressed by the compressor. The expansion valve 14 is provided in the flow path from the condensation unit 13 to the evaporation unit 11 to depressurize the refrigerant. The heat exchanger 15 exchanges heat between the refrigerant flowing through the flow path from the evaporator 11 to the compressor 12 and the refrigerant flowing through the flow path from the compressor 12 to the condenser 13.
Thereby, in the cooling system 10, the temperature of the refrigerant | coolant which flows in into the compressor 12 can be raised, and possibility that liquid compression will arise can be reduced.
In particular, the heat exchanger 15 performs heat exchange using the refrigerant that has flowed out of the compressor 12 and before flowing into the condensing unit 13, so that it is not affected by the temperature drop of the refrigerant in the condensing unit 13. Heat exchange can be performed. In this regard, the cooling system 10 can further reduce the possibility that liquid compression occurs as compared with the case where liquid compression is prevented using the refrigerant flowing through the condenser.

It should be noted that a program for realizing all or part of the functions of the controller 305 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed. Processing may be performed. The “computer system” here includes an OS (Operating System) and hardware such as peripheral devices.
The “computer-readable recording medium” means a portable medium such as a flexible disk, a magneto-optical disk, a ROM (Read only memory), a CD-ROM (Compact Disc Read only memory), or a hard disk built in the computer system. This means a storage device such as The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

The present invention has been described above based on the embodiment. The embodiment is an exemplification, and various modifications, increases / decreases, and combinations may be added to the above-described embodiments without departing from the gist of the present invention. It will be understood by those skilled in the art that modifications to which these changes, increases / decreases, and combinations are also within the scope of the present invention.
This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2017-056146 for which it applied on March 22, 2017, and takes in those the indications of all here.

DESCRIPTION OF

SYMBOLS

1,10 Cooling system 11,101 Evaporating part 12,102 Compressor 13,103 Condensing part 14,104 Expansion valve 15,301 Heat exchanger 302 Bypass valve 303 Temperature sensor 304 Pressure sensor 305 Controller

Claims

An evaporation section for evaporating the refrigerant;
A compressor for compressing the refrigerant evaporated in the evaporation section;
A condensing unit for condensing the refrigerant compressed by the compressor;
An expansion valve provided in a flow path from the condensing unit to the evaporation unit to depressurize the refrigerant;
A heat exchanger that exchanges heat between the refrigerant flowing through the flow path from the evaporator to the compressor and the refrigerant flowing through the flow path from the compressor to the condenser;
With cooling system.
A pressure sensor and a temperature sensor provided on at least one of the inlet side and the outlet side of the compressor;
A controller for controlling a heat exchange amount in the heat exchanger based on a pressure measurement value of the pressure sensor and a temperature measurement value of the temperature sensor;
The cooling system according to claim 1.
The controller reduces the heat exchange amount when the degree of superheat of the refrigerant calculated from the pressure measurement value and the temperature measurement value is larger than a predetermined range, and when the degree of superheat of the refrigerant is smaller than the predetermined range. Increases the heat exchange amount, and suppresses a change in the heat exchange amount when the superheat degree of the refrigerant is within the predetermined range,
The cooling system according to claim 2.
The bypass flow path is provided in a bypass flow path that bypasses the heat exchanger with respect to at least one of the flow path from the evaporation section to the compressor and the flow path from the compressor to the condensation section. A flow rate adjusting valve for adjusting the amount of refrigerant flowing through the
The cooling system according to claim 3.
The controller controls the flow regulating valve based on the pressure measurement value and the temperature measurement value;
The cooling system according to claim 4.
The controller increases the amount of refrigerant flowing through the flow rate adjustment valve when the superheat degree of the refrigerant calculated from the pressure measurement value and the temperature measurement value is larger than a predetermined range, and the superheat degree is less than the predetermined range. Reducing the amount of refrigerant flowing through the flow rate adjustment valve when small, and maintaining the amount of refrigerant flowing through the flow rate adjustment valve when the superheat is within the predetermined range;
The cooling system according to claim 5.
A refrigerant flowing through a flow path from an evaporation section that evaporates the refrigerant to a compressor that compresses the refrigerant evaporated in the evaporation section, and a flow path from the compressor to a condensation section that condenses the refrigerant compressed by the compressor A cooling method including causing heat exchange between flowing refrigerants.
On the computer,
A refrigerant flowing through a flow path from an evaporation section that evaporates the refrigerant to a compressor that compresses the refrigerant evaporated in the evaporation section, and a flow path from the compressor to a condensation section that condenses the refrigerant compressed by the compressor A computer-readable recording medium recording a program for controlling heat exchange between flowing refrigerants.