JP2018021721A - Freezer and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a freezer capable of changing the mixture ratio of the non-azeotropic refrigerant mixture performing the refrigerating cycle during driving in a simple configuration.SOLUTION: A freezer comprises: takeout piping 19 for taking out a part of the non-azeotropic refrigerant mixture from between a condenser 5 and an expansion valve 7; an on-off valve 20 for the takeout piping; a gas-liquid separator 17 connected to the takeout piping 19 for separating gas-liquid by storing the non-azeotropic refrigerant mixture; gas return piping 21 for connecting between the expansion valve 7 and an evaporator 9 to a gas phase part in the gas-liquid separator 17; an on-off valve 22 for the gas return piping; liquid return piping 23 for connecting between the expansion valve 7 and the evaporator 9 to a liquid phase part in the gas-liquid separator 17; and a control part for controlling the on-off valve 20 for the takeout piping, the on-off valve 22 for the gas return piping, and an on-off valve 24 for the liquid return piping.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a refrigeration apparatus using a non-azeotropic refrigerant mixture and a control method thereof.

  An HFC refrigerant such as R410A is used as the refrigerant used in the air conditioner. However, the HFC refrigerant represented by R410A has a high GWP (global warming potential). Therefore, among HFC refrigerants, R32 having a lower GWP than R410A, and H234 refrigerants 1234yf and R1234ze (E) are listed as candidates for the next refrigerant for R410A. However, the refrigerants that are candidates for the next period have merits and demerits because of the refrigerant physical properties of chlorofluorocarbon refrigerants and natural refrigerants. For example, R32 has a lower GWP than R410A and can obtain the same or higher performance, but has a disadvantage that the discharge temperature is higher than R410A and the reliability in a low temperature range is inferior. R1234yf and R1234ze (E) have the advantage that the GWP with a GWP of 10 or less is low. However, since the density is lower than that of the R410A, the volume capacity is only about 50%. There is a disadvantage that the equipment is increased in size.

  In order to make up for such advantages and disadvantages of the refrigerant, use of a mixed refrigerant in which two or more kinds of refrigerants are mixed has been studied. Patent Document 1 below discloses changing the ratio of the mixed refrigerant in the refrigeration cycle by dissolving the mixed refrigerant in the refrigeration oil and using the difference in the solubility of the refrigerant.

JP-A-7-98161

  Among mixed refrigerants, a non-azeotropic mixed refrigerant in which refrigerants having different boiling points are mixed causes temperature slip as shown in FIG. That is, since the boiling points and condensation points of the mixed refrigerants are different, the isotherm in the wet steam (between the saturated liquid line and the saturated vapor line) does not become constant in pressure (p) as in the case of a single refrigerant. On the -h diagram, it becomes a lower right isotherm. That is, temperature slip occurs in the non-azeotropic refrigerant mixture.

  Further, depending on the ratio of each refrigerant in the non-azeotropic refrigerant mixture, for example, as shown in FIG. 12, the temperature difference of the temperature slip varies. In FIG. 12, the horizontal axis represents the mixing ratio [wt%] of R32 (low boiling point refrigerant) to R1234ze (E) (high boiling point refrigerant), and the vertical axis represents the high pressure side (FIG. 12 (a): saturation temperature 40 (° C.) and the temperature difference [° C.] of the temperature slip on the low pressure side (FIG. 12B: saturation temperature 10 ° C.). As can be seen from the figure, the temperature slip is maximum when the mixing ratio of R32 to R1234ze (E) is around 20 wt%. In this case, since the saturation temperature is set to 10 ° C. on the low pressure side, the low pressure side, that is, the evaporator temperature may be 0 ° C. or less, so that the evaporator may be frosted. When the heating operation is performed, when the evaporator is frosted, the heat exchange performance is lowered and the heat absorption amount is reduced, so that the heating performance is significantly lowered.

  FIG. 13 shows COPs (coefficients of performance) during cooling operation and heating operation when the mixing ratio of R410A and R1234ze (E) is changed. In the figure, the horizontal axis (lower axis) is the mixing ratio [wt%] of R32 to R1234ze (E), the horizontal axis (upper axis) is GWP at each mixing ratio, and the vertical axis is R410A. COP at the same capacity ratio. As can be seen from the figure, when the mixing ratio of R32 decreases, the ratio of R1234ze (E) increases, so although GWP decreases, the COP during cooling operation and heating operation decreases, and in particular, the COP decrease during cooling operation is large. .

  Therefore, it is desired to change the mixing ratio of the non-azeotropic refrigerant mixture for performing the refrigeration cycle during operation. In the above Patent Document 1, the ratio of the mixed refrigerant in the refrigeration cycle can be changed. However, since the solubility of the refrigerant in the refrigeration oil is used, it is necessary to control the temperature of the refrigeration oil and the amount of stored oil. May be complicated.

This invention is made | formed in view of such a situation, Comprising: The freezing apparatus which can change the mixing ratio of the non-azeotropic refrigerant mixture which performs a refrigerating cycle with a simple structure during driving | operation, and its control method are provided. With the goal.
It is another object of the present invention to provide a refrigeration apparatus that can prevent the evaporator temperature from frosting due to temperature slip of the non-azeotropic refrigerant mixture and a control method therefor.
It is another object of the present invention to provide a refrigeration apparatus using a non-azeotropic refrigerant mixture and a method for controlling the refrigeration apparatus that can suppress performance degradation during cooling operation as much as possible.

In order to solve the above problems, the refrigeration apparatus and the control method thereof according to the present invention employ the following means.
That is, the refrigeration apparatus according to the present invention includes a compressor that compresses a non-azeotropic refrigerant mixture in which a low-boiling point refrigerant and a high-boiling point refrigerant having different boiling points are mixed, and a non-azeotropic refrigerant mixture that is led from the compressor. A condenser for condensing, an expansion valve for expanding the non-azeotropic refrigerant mixture led from the condenser, an evaporator for evaporating the non-azeotropic refrigerant mixture led from the expansion valve, the condenser and the expansion An extraction pipe for taking out a part of the non-azeotropic refrigerant mixture from the valve, an extraction pipe on-off valve provided in the extraction pipe, and the non-azeotropic refrigerant mixture stored in the extraction pipe. A gas-liquid separator that performs liquid separation, a gas return pipe that connects between the expansion valve and the evaporator and a gas phase part in the gas-liquid separator, and a gas return pipe that is provided in the gas return pipe On-off valve, between the expansion valve and the evaporator, and a liquid phase part in the gas-liquid separator; A liquid return pipe to be connected, a liquid return pipe on-off valve provided on the liquid return pipe, a control part for controlling the on-off valve for the extraction pipe, the on-off valve for the gas return pipe, and the on-off valve for the liquid return pipe It is characterized by having.

By opening the open / close valve for the extraction pipe according to a command from the control unit, a part of the non-azeotropic refrigerant mixture is taken out between the condenser and the expansion valve via the extraction pipe, and temporarily stored in the gas-liquid separator. Store. In the gas-liquid separator, the gas-liquid is separated according to the temperature and pressure in the gas-liquid separator, and a liquid phase part and a gas phase part are formed.
When the gas return pipe on-off valve is opened by a command from the control unit, the expansion valve and the evaporator communicate with the gas phase part of the gas-liquid separator via the gas return pipe, and the gas phase part has a low pressure. Thus, the low boiling point refrigerant is preferentially guided to the evaporator. Thereby, the ratio of the low boiling point refrigerant | coolant in the non-azeotropic refrigerant mixture which performs a refrigerating cycle can be increased.
When the on-off valve for the liquid return pipe is opened by a command from the control unit, the liquid refrigerant in the liquid phase is connected between the expansion valve and the evaporator and the liquid phase part of the gas-liquid separator via the liquid return pipe. Is led to the evaporator. In the gas-liquid separator, the low-boiling point refrigerant evaporates and is separated from the liquid phase part, so the high-boiling point refrigerant is present in the liquid refrigerant at a higher rate than when the non-azeotropic refrigerant mixture is taken out from the extraction pipe. doing. Thereby, the ratio of the high boiling point refrigerant | coolant in the non-azeotropic refrigerant mixture which performs a refrigerating cycle can be increased.
As described above, the refrigerant separated by the gas-liquid separator can be returned from the gas phase portion or the liquid phase portion to the refrigeration cycle only by controlling each on-off valve of each pipe connected to the gas-liquid separator. Therefore, the mixing ratio of the low boiling point refrigerant and the high boiling point refrigerant can be arbitrarily changed with a simple configuration.
Examples of the low boiling point refrigerant include R32, and examples of the high boiling point refrigerant include R1234yf and R1234ze (E).

  Further, in the refrigeration apparatus of the present invention, the control unit opens the extraction pipe on-off valve when the outside air temperature is less than a predetermined value or the evaporator temperature is less than a predetermined value during heating operation. A separation operation is performed in which the gas return pipe on-off valve is opened and the gas refrigerant separated by the gas-liquid separator is returned from the gas return pipe to the evaporator side.

During the heating operation, since the outside air temperature is generally low, the temperature of the evaporator becomes low. When the temperature of the evaporator becomes lower than a predetermined value, for example, a problem that frosting occurs in the evaporator occurs. Therefore, when the outside air temperature is lower than the predetermined value or the evaporator temperature is lower than the predetermined value, the gas refrigerant separated by the gas-liquid separator (mainly low boiling point) is opened by opening the gas return pipe on-off valve. Refrigerant) is returned to the evaporator side through the gas return pipe, and the ratio of the low boiling point refrigerant in the refrigeration cycle is increased. At this time, by opening the on-off valve for the extraction pipe, the non-azeotropic refrigerant mixture is guided from the refrigeration cycle to the gas-liquid separator from the refrigeration cycle, and gas-liquid separation is performed in the gas-liquid separator. Returning the refrigerant into the refrigeration cycle further promotes an increase in the proportion of the low boiling point refrigerant in the refrigeration cycle.
By performing such a separation operation, by separating the high boiling point refrigerant from the non-azeotropic refrigerant mixture that performs the refrigeration cycle and increasing the proportion of the low boiling point refrigerant, the temperature slip is reduced, and the evaporator The saturation temperature can be increased, and for example, frost formation can be suppressed.
As the predetermined value of the outside air temperature and the predetermined value of the evaporator temperature, for example, a temperature at which the temperature of the evaporator decreases and frost formation may occur is selected.

  Furthermore, in the refrigeration apparatus of the present invention, the control unit may be configured after a predetermined period has elapsed since the start of the separation operation, or after the degree of superheat of the non-azeotropic refrigerant mixture sucked by the compressor becomes less than a predetermined value. The extraction pipe on-off valve is closed.

A refrigeration cycle is performed by closing the take-off piping on-off valve after a predetermined period has elapsed since the start of the separation operation or after the degree of superheat of the non-azeotropic refrigerant mixture sucked by the compressor becomes less than a predetermined value. Stop taking out part of the non-azeotropic refrigerant mixture to the gas-liquid separator. As a result, the control for increasing the ratio of the low-boiling refrigerant in the non-azeotropic refrigerant mixture that performs the refrigeration cycle is stopped, and the operation can be continued with the composition of the non-azeotropic refrigerant mixture after performing the separation operation. .
The “predetermined period” after the elapse of a predetermined period from the start of the separation operation is selected, for example, as the time from when the separation operation is performed until a desired mixing ratio is obtained.
As the “predetermined value” at which the degree of superheat of the refrigerant sucked by the compressor is less than a predetermined value, for example, a value set to avoid liquid compression of the compressor is used.

  Furthermore, in the refrigeration apparatus of the present invention, the control unit opens the extraction piping on-off valve when the outside air temperature is equal to or higher than a predetermined value or the discharge gas temperature discharged from the compressor is equal to or higher than a predetermined value. The gas return pipe on-off valve is closed, and the liquid return pipe on-off valve is opened.

When the outside air temperature is equal to or higher than a predetermined value, there is no risk of malfunction such as frost formation on the evaporator. Therefore, when the outside air temperature becomes equal to or higher than a predetermined value, the gas return pipe on-off valve is closed to stop the low-boiling point refrigerant from being preferentially returned during the refrigeration cycle. Then, the on-off valve for the liquid return pipe is opened, and the high-boiling point refrigerant existing in the liquid phase part is returned to the refrigeration cycle. At this time, by opening the on-off valve for the extraction pipe, the non-azeotropic refrigerant mixture is led from the refrigeration cycle to the gas-liquid separator, and gas-liquid separation is performed by the gas-liquid separator. By preferentially returning the boiling point refrigerant into the refrigeration cycle, the rate of the high boiling point refrigerant in the refrigeration cycle is increased.
In this way, by performing the mixing operation in which the high boiling point refrigerant is mixed in the non-azeotropic refrigerant mixture that performs the refrigeration cycle, the ratio of the high boiling point refrigerant in the non-azeotropic refrigerant mixture is increased, and mixing at the time of refrigerant filling is performed. The ratio can be returned.
Further, when the temperature of the discharge gas discharged from the compressor becomes a predetermined value or more, the discharge gas temperature can be lowered by returning the mixing ratio of the refrigerant at the time of filling the refrigerant by the mixing operation.

  Further, in the refrigeration apparatus of the present invention, the control unit opens the extraction piping on-off valve and opens the gas return piping on-off valve during cooling operation.

  A low boiling point refrigerant such as R32 has a higher density than a high boiling point refrigerant such as R1234yf or R1234ze (E), and therefore has a higher COP. Therefore, during the cooling operation, the ratio of the low boiling point refrigerant in the non-azeotropic refrigerant mixture that performs the refrigeration cycle is increased by performing a separation operation in which the open / close valve for the extraction pipe and the open / close valve for the gas return pipe are opened. Thereby, highly efficient cooling operation is realizable.

  Furthermore, in the refrigeration apparatus of the present invention, the control unit opens the extraction pipe on-off valve when the discharge gas temperature discharged from the compressor becomes a predetermined value or more, and opens and closes the gas return pipe on-off. The valve is closed and the liquid return pipe on-off valve is opened.

  When the ratio of the low boiling point refrigerant in the non-azeotropic refrigerant mixture that performs the refrigeration cycle is increased, the discharge gas temperature of the compressor may be excessively increased. Therefore, when the discharge gas temperature exceeds the specified value, a mixing operation is performed in which the open / close valve for the extraction pipe is opened, the open / close valve for the gas return pipe is closed, and the open / close valve for the liquid return pipe is opened. Therefore, the ratio of the high boiling point refrigerant in the non-azeotropic refrigerant mixture is increased to return to the mixing ratio at the time of refrigerant filling. Thereby, protection of an apparatus can be aimed at by avoiding that the discharge gas temperature of a compressor becomes high too much.

  Further, the control method of the refrigeration apparatus according to the present invention includes a compressor that compresses a non-azeotropic mixed refrigerant in which a low-boiling refrigerant and a high-boiling refrigerant having different boiling points are mixed, and a non-azeotropic mixing derived from the compressor. A condenser for condensing the refrigerant, an expansion valve for expanding the non-azeotropic refrigerant mixture led from the condenser, an evaporator for evaporating the non-azeotropic refrigerant mixture led from the expansion valve, and the condenser An extraction pipe for extracting a part of the non-azeotropic refrigerant mixture from the expansion valve, an extraction pipe on-off valve provided in the extraction pipe, and the non-azeotropic refrigerant mixture are connected to the extraction pipe. A gas-liquid separator that performs gas-liquid separation, a gas return pipe that connects between the expansion valve and the evaporator and a gas phase portion in the gas-liquid separator, and a gas provided in the gas return pipe A return pipe on-off valve, between the expansion valve and the evaporator, and a liquid phase part in the gas-liquid separator; A control method of a refrigeration apparatus comprising a liquid return pipe to be connected and a liquid return pipe on-off valve provided on the liquid return pipe, wherein the extraction pipe on-off valve, the gas return pipe on-off valve, and the The on-off control of the on-off valve for liquid return piping is performed.

By simply controlling each on-off valve of each pipe connected to the gas-liquid separator, the gas-liquid separated refrigerant in the gas-liquid separator can be returned to the refrigeration cycle from the gas phase part or liquid phase part. With such a configuration, the mixing ratio of the non-azeotropic refrigerant mixture can be arbitrarily changed.
By separating the high-boiling refrigerant from the non-azeotropic refrigerant that performs the refrigeration cycle and increasing the proportion of the low-boiling refrigerant, the saturation temperature in the evaporator is increased, thereby reducing the frost formation on the evaporator. Can be suppressed.
During the cooling operation, the separation operation is performed by opening the on-off valve for the extraction pipe and the on-off valve for the gas return pipe, thereby increasing the ratio of the low boiling point refrigerant in the non-azeotropic refrigerant mixture that performs the refrigeration cycle. Efficient cooling operation can be realized.

It is a refrigerant circuit of the refrigerating device which concerns on one Embodiment of this invention, and is a schematic block diagram which showed the normal driving | operation (encapsulation composition) at the time of heating operation. It is a schematic block diagram of the refrigerant circuit which showed the separation operation at the time of heating operation. It is a schematic block diagram of the refrigerant circuit which showed the normal operation (separation composition) at the time of heating operation. It is a schematic block diagram of the refrigerant circuit which showed the mixing operation at the time of heating operation. It is the flowchart which showed the control at the time of heating operation. It is a schematic block diagram of the refrigerant circuit which showed the normal operation (enclosure composition) at the time of air_conditionaing | cooling operation. It is a schematic block diagram of the refrigerant circuit which showed the separation operation at the time of air_conditionaing | cooling operation. It is a schematic block diagram of the refrigerant circuit which showed normal operation (separation composition) at the time of air_conditionaing | cooling operation. It is a schematic block diagram of the refrigerant circuit which showed the mixing operation at the time of air_conditionaing | cooling operation. It is the flowchart which showed the control at the time of air_conditionaing | cooling operation. It is the p (pressure) -h (enthalpy) diagram which showed the temperature slip of the non-azeotropic refrigerant mixture. A temperature slip corresponding to the mixing ratio of the non-azeotropic refrigerant mixture is shown, (a) is a temperature slip when the saturation temperature is 40 ° C., and (b) is a temperature slip when the saturation temperature is 10 ° C. It is the graph which showed the change of COP according to the mixing ratio of a non-azeotropic refrigerant mixture.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.
FIG. 1 shows the refrigerant circuit configuration of the refrigeration apparatus 1 of the present embodiment. The refrigeration apparatus 1 is used as an air conditioner, for example, and can perform a heating operation and a cooling operation by switching a four-way valve (not shown) provided on the discharge side of the compressor 3. In FIG. 1, the structure at the time of heating operation is shown.

  The refrigeration apparatus 1 uses a non-azeotropic refrigerant mixture in which R32 and R1234ze (E) are mixed as a refrigerant. R32 is a low boiling point refrigerant having a lower boiling point than R1234ze (E). R1234ze (E) is a high boiling point refrigerant having a high boiling point relative to R32. Note that R1234yf may be used instead of R1234ze (E).

  The refrigeration apparatus 1 includes a compressor 3 that compresses a non-azeotropic refrigerant mixture (hereinafter sometimes simply referred to as “refrigerant”), a condenser 5, an expansion valve 7, and an evaporator 9. The refrigerant circuit which performs a refrigerating cycle is comprised by connecting these compressor 3, the condenser 5, the expansion valve 7, and the evaporator 9 with refrigerant | coolant piping.

The compressor 3 is installed inside the outdoor unit, and is a scroll compressor or a rotary compressor, for example, and is driven by an electric motor (not shown). The electric motor includes an inverter device, and the rotation speed is arbitrarily changed by a command from a control unit (not shown).
A suction pressure sensor 11 that measures the suction pressure Ps of the refrigerant is provided on the suction side of the compressor 3, and a discharge temperature sensor 13 that measures the discharge temperature of the refrigerant is provided on the discharge side of the compressor 3. ing. Outputs of the suction pressure sensor 11 and the discharge temperature sensor 13 are transmitted to the control unit.

The condenser 5 is an indoor heat exchanger, and condenses the high-pressure gas refrigerant introduced from the compressor 3 by heating indoor air and exchanging heat during heating operation.
The expansion valve 7 expands the refrigerant condensed and liquefied by the condenser 5. The opening degree of the expansion valve 7 is controlled by the control unit.
The evaporator 9 is an outdoor heat exchanger installed inside the outdoor unit, and evaporates the refrigerant expanded by the expansion valve 7 by exchanging heat with the outside air as an outdoor heat exchanger during heating operation. . An evaporator outlet temperature sensor 15 for measuring the temperature of the evaporated refrigerant is provided at the refrigerant outlet of the evaporator 9. The output of the evaporator outlet temperature sensor 15 is transmitted to the control unit.

  Apart from the main refrigerant circuit that performs the refrigeration cycle by the compressor 3, the condenser 5, the expansion valve 7, and the evaporator 9 described above, a gas-liquid separator 17 is provided. The gas-liquid separator 17 is a tank having a capacity capable of temporarily storing the refrigerant. The gas-liquid separator 17 is installed inside an outdoor unit that houses the compressor 3 and the evaporator 9.

  An extraction pipe 19 is provided between the extraction position A between the condenser 5 and the expansion valve 7 and the upper part of the gas-liquid separator 17. The extraction pipe 19 is provided with an extraction pipe opening / closing valve 20. The extraction piping on-off valve 20 is, for example, an electromagnetic valve, and is opened and closed by a command from the control unit.

  A gas return pipe 21 is provided between the merging position B between the expansion valve 7 and the evaporator 9 and the gas-liquid separator 17. The upstream end 21 a of the gas return pipe 21 is positioned above the gas-liquid separator 17 and opens to the gas phase portion of the refrigerant separated in the gas-liquid separator 17. The gas return pipe 21 is provided with a gas return pipe open / close valve 22. The gas return pipe on-off valve 22 is, for example, an electromagnetic valve, and is opened and closed by a command from the control unit.

  A liquid return pipe 23 is provided between the merging position B between the expansion valve 7 and the evaporator 9 and the gas-liquid separator 17. The upstream end 23 a of the liquid return pipe 23 is located at the lower part (or the bottom part) of the gas-liquid separator 17 and opens to the liquid phase part of the refrigerant separated in the gas-liquid separator 17. The liquid return pipe 23 is provided with a liquid return pipe open / close valve 24. The liquid return piping on-off valve 24 is, for example, an electromagnetic valve, and is opened and closed by a command from the control unit.

  The control unit includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program as an example, and the CPU reads the program into a RAM or the like to execute information processing / arithmetic processing. As a result, various functions are realized. The program is preinstalled in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Etc. may be applied. The computer-readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

<During heating operation>
Next, the operation mode at the time of heating operation of the refrigeration apparatus 1 having the above configuration will be described.
[Normal operation (encapsulated composition): During heating operation]
FIG. 1 shows normal operation (encapsulation composition) during heating operation. This normal operation is performed with a composition having a mixing ratio (for example, a mixing ratio of R32: R1234ze (E) = 1: 1) equivalent to that when the non-azeotropic refrigerant mixture is enclosed in the refrigeration apparatus 1. .

  The extraction piping on-off valve 20 is closed, the gas return piping on-off valve 22 is opened, and the liquid return piping on-off valve 24 is opened. In each figure, the valve opening is indicated by white and the valve closing is indicated by solid color.

By closing the take-off piping on-off valve 20, the refrigerant is not taken out from the refrigeration cycle, and the mixing ratio of the refrigerant that performs the refrigeration cycle is not changed. Further, by opening the on-off valve 24 for the liquid return pipe, the liquid refrigerant is not accumulated in the gas-liquid separator 17 and the mixing ratio of the refrigerant for performing the refrigeration cycle is not changed.
The gas return piping on-off valve 22 is opened and equalized with the refrigerant pressure after being expanded by the expansion valve 7. This makes it possible to prevent the low-boiling point refrigerant from remaining unevaporated during normal operation, thereby preventing a liquid-sealed state in which the gas-liquid separator 17 is filled with unevaporated refrigerant during stoppage. Because.

[Separate operation (heating operation)]
FIG. 2 shows the separation operation during the heating operation. The separation operation is performed after the normal operation (encapsulated composition) described above, and R1234ze (high boiling point refrigerant) is separated from the refrigerant that performs the refrigeration cycle, and R32 (low boiling point refrigerant) in the refrigerant that performs the refrigeration cycle. This is an operation to increase the mixing ratio.

  The extraction piping on-off valve 20 is open, the gas return piping on-off valve 22 is open, and the liquid return piping on-off valve 24 is closed.

  By opening the extraction pipe on-off valve 20, a part of the liquid refrigerant is introduced into the gas-liquid separator 17 from between the condenser 5 and the expansion valve 7. In the gas-liquid separator 17, the gas return pipe on-off valve 22 is opened, and the gas-liquid separator 17 has a low pressure equivalent to the pressure between the expansion valve 7 and the evaporator 9. R32, which is a low-boiling point refrigerant led to (3), is preferentially evaporated over R1234ze (E), which is a high-boiling point refrigerant. The R32 evaporated in the gas-liquid separator 17 passes through the gas return pipe 21 and is returned from the joining position B to the evaporator 9 and used as a refrigerant for performing the refrigeration cycle. This increases the mixing ratio of R32 in the refrigerant that performs the refrigeration cycle.

[Normal operation (separated composition): During heating operation]
FIG. 3 shows a normal operation (separation composition) during the heating operation. This normal operation is performed after the above-described separation operation, and is operated in a state in which R1234ze (E) in the refrigerant that performs the refrigeration cycle is separated and the mixing ratio of R32 is increased. It is.

  The extraction piping on-off valve 20 is closed, the gas return piping on-off valve 22 is open, and the liquid return piping on-off valve 24 is closed.

By closing the take-off piping on-off valve 20, the refrigerant is not taken out from the refrigeration cycle, and the mixing ratio of the refrigerant that performs the refrigeration cycle is not changed. Further, by closing the liquid return pipe open / close valve 24, the liquid refrigerant in the gas-liquid separator 17 is not returned to the refrigeration cycle, and the mixing ratio of the refrigerant for performing the refrigeration cycle is not changed.
The gas return pipe on-off valve 22 is opened, and R32 separated in the gas-liquid separator 17 is guided to the evaporator 9 through the gas return pipe 21.

[Mixed operation: Heating operation]
FIG. 4 shows the mixing operation during the heating operation. The mixing operation is performed after the above-described normal operation (separation composition), and is an operation in which R1234ze (E) is mixed in the refrigerant that performs the refrigeration cycle to reduce the mixing ratio of R32 in the refrigerant.

  The extraction piping on-off valve 20 is open, the gas return piping on-off valve 22 is closed, and the liquid return piping on-off valve 24 is open.

  By opening the extraction pipe on-off valve 20, the liquid refrigerant is introduced into the gas-liquid separator 17 from between the condenser 5 and the expansion valve 7. Since the gas return pipe open / close valve 22 is closed in the gas / liquid separator 17, R32 evaporated in the gas / liquid separator 17 is not supplied from the joining position B to the refrigerant that performs the refrigeration cycle. . On the other hand, since the liquid return pipe opening / closing valve 24 is opened, the liquid refrigerant stored in the gas-liquid separator 17 is guided from the merging position B to the evaporator 9 through the liquid return pipe 23. Thereby, since the liquid refrigerant in the gas-liquid separator 17 in which R1234ze (E) is concentrated by the separation operation (see FIG. 2) is returned to the refrigerant that performs the refrigeration cycle, R1234ze (E) in the refrigerant that performs the refrigeration cycle. ) Mixing ratio increases.

  Next, a control method of the refrigeration apparatus 1 during the heating operation will be described with reference to FIG. Each step shown below is performed by a command from the control unit.

  When the operation is started, it is determined whether or not the outside air temperature is lower than a predetermined value (for example, 10 ° C.) (step S1). As the outside air temperature, a measurement value of an outside air temperature sensor (not shown) is used. When the outside air temperature is less than 10 ° C., a separation operation (see FIG. 2) is performed to increase the mixing ratio of R32 in the refrigerant that performs the refrigeration cycle. Thereby, the temperature slip in the evaporator 9 becomes small (refer FIG.12 (b)), the low pressure in the evaporator 9 rises, and frost formation is prevented.

  When it is determined in step S1 that the outside air temperature is 10 ° C. or higher, the process proceeds to step S3, and normal operation (encapsulated composition) is performed (see FIG. 1). In normal operation (encapsulated composition), the mixing ratio in the refrigerant that performs the refrigeration cycle is equivalent to that in the refrigerant charging, and the mixing ratio of R32 is not excessively large, so the discharge gas temperature of the refrigerant gas discharged from the compressor 3 Is maintained at a predetermined value or less.

If the measured temperature Tho-R of the evaporator outlet temperature sensor 15 is a predetermined value (for example, −3 ° C.) or more during normal operation (encapsulation composition) in step S3 (step S4), the unit is stopped. The presence / absence of a command is determined (step S5). When the unit stop command is issued, the refrigeration apparatus 1 is stopped and the process is terminated. If the unit stop command has not been issued, the process returns to step S3 to continue the normal operation (encapsulated composition).
When the measured temperature Th0-R of the evaporator outlet temperature sensor 15 is less than −3 ° C. in step S4, the process proceeds to step S3 and the separation operation is performed. By the separation operation, the low pressure of the evaporator 9 rises and frost formation is prevented.

  While performing the separation operation in step S2, it is determined whether the suction superheat degree of the compressor 3 is less than 2 ° C. or whether a predetermined time (for example, 1 hour) has elapsed since the separation operation was started ( Step S6). The suction superheat degree is calculated from the difference between the saturation temperature of the pressure obtained by the suction pressure sensor 11 and the temperature obtained by the evaporator outlet temperature sensor 15.

  In step S6, if the suction superheat is not less than 2 ° C. and one hour has not elapsed since the separation operation, the process returns to step S2 and the separation operation is continued.

  In step S6, when the suction superheat degree is less than 2 ° C. or one hour or more has elapsed from the separation operation, the process proceeds to step S7, and normal operation (separation composition) is performed (see FIG. 3). In the normal operation (separation composition), an operation is performed in which R1234ze (E) is separated from the refrigerant that performs the refrigeration cycle to increase the mixing ratio of R32. Thereby, while suppressing the frost formation of the evaporator 9, operation | movement with high COP is performed as shown in FIG.

  During normal operation (separation composition), it is determined whether or not the discharge temperature Tho-D measured by the discharge temperature sensor 13 exceeds a predetermined value (for example, 110 ° C.) (step S8). When the discharge temperature Th0-D exceeds 110 ° C., the process proceeds to step S9 and a mixing operation (see FIG. 4) is performed. In the mixing operation, R1234ze (E) is mixed in the refrigerant performing the refrigeration cycle, and the operation is performed so as to approach the mixing ratio at the time of sealing. Thereby, the mixing ratio of R32 in the refrigerant that performs the refrigeration cycle decreases, and the discharge temperature decreases. The mixing operation is terminated after a predetermined time (for example, 5 minutes) has elapsed, and the routine proceeds to step S3 where the normal operation (encapsulated composition) is performed.

  If it is determined in step S8 that the discharge temperature Tho-D does not exceed 110 ° C., the process proceeds to step S10 to determine whether a unit stop command is present. If the unit stop command has not been issued, the process returns to step S7 and the normal operation (separation composition) is continued. When the unit stop command is issued, the process proceeds to step S11, and after the mixing operation is performed for a predetermined time (for example, 5 minutes), the refrigeration apparatus 1 is stopped and the process is terminated. By performing the mixing operation before stopping the refrigeration apparatus 1, the mixing ratio in the refrigerant that performs the refrigeration cycle at the next start-up is returned when the refrigerant is charged.

<During cooling operation>
Next, the operation mode during the cooling operation of the refrigeration apparatus 1 having the above-described configuration will be described. The cooling operation is changed from the heating operation by switching a four-way valve (not shown) provided on the discharge side of the compressor 3. Thereby, a condenser switches to an evaporator (indoor heat exchanger) at the time of cooling operation, and an evaporator at the time of heating operation switches to a condenser (outdoor heat exchanger) at the time of cooling operation.

[Normal operation (encapsulated composition): During cooling operation]
FIG. 6 shows a normal operation (encapsulation composition) during the cooling operation. This normal operation is performed with a composition having a mixing ratio (for example, a mixing ratio of R32: R1234ze (E) = 1: 1) equivalent to that when the non-azeotropic refrigerant mixture is enclosed in the refrigeration apparatus 1. .

  The extraction piping on-off valve 20 is closed, the gas return piping on-off valve 22 is open, and the liquid return piping on-off valve 24 is closed.

By closing the take-off piping on-off valve 20, the refrigerant is not taken out from the refrigeration cycle, and the mixing ratio of the refrigerant that performs the refrigeration cycle is not changed. Further, by opening the on-off valve 24 for the liquid return pipe, the liquid refrigerant is not accumulated in the gas-liquid separator 17 and the mixing ratio of the refrigerant forming the refrigeration cycle is not changed.
The gas return piping on-off valve 22 is opened and equalized with the refrigerant pressure after being expanded by the expansion valve 7. This makes it possible to prevent the low-boiling point refrigerant from remaining unevaporated during normal operation, and to prevent a liquid-sealed state in which the gas-liquid separator is filled with unevaporated refrigerant during stoppage. It is.

[Separation operation (air-cooling operation)]
FIG. 7 shows the separation operation during the cooling operation. The separation operation is performed after the above-described normal operation (encapsulated composition), and R1234ze (E) (high boiling point refrigerant) is separated from the refrigerant that performs the refrigeration cycle, and R32 (low in the refrigerant that performs the refrigeration cycle). This is an operation for increasing the mixing ratio of the boiling point refrigerant.

  The extraction piping on-off valve 20 is open, the gas return piping on-off valve 22 is open, and the liquid return piping on-off valve 24 is closed.

  By opening the extraction pipe on-off valve 20, the liquid refrigerant is introduced into the gas-liquid separator 17 from between the condenser 5 and the expansion valve 7. In the gas-liquid separator 17, the gas return pipe on-off valve 22 is opened, and the gas-liquid separator 17 has a low pressure equivalent to the pressure between the expansion valve 7 and the evaporator 9. R32, which is a low-boiling point refrigerant led to (3), is preferentially evaporated over R1234ze (E), which is a high-boiling point refrigerant. Then, R32 evaporated in the gas-liquid separator 17 passes through the gas return pipe 22 and is returned from the joining position B to the evaporator 9 to be used as a refrigerant for performing a refrigeration cycle. This increases the mixing ratio of R32 in the refrigerant that performs the refrigeration cycle.

[Normal operation (separated composition): During cooling operation]
FIG. 8 shows a normal operation (separation composition) during the cooling operation. This normal operation is performed after the above-described separation operation, and is operated in a state in which R1234ze (E) in the refrigerant that performs the refrigeration cycle is separated and the mixing ratio of R32 is increased. It is.

  The extraction piping on-off valve 20 is closed, the gas return piping on-off valve 22 is closed, and the liquid return piping on-off valve 24 is closed.

  By closing the take-off piping on-off valve 20, the refrigerant is not taken out from the refrigeration cycle, and the mixing ratio of the refrigerant that performs the refrigeration cycle is not changed. Further, by closing the liquid return pipe open / close valve 24, the liquid refrigerant in the gas-liquid separator 17 is not returned to the refrigeration cycle, and the mixing ratio of the refrigerant for performing the refrigeration cycle is not changed.

  The gas return piping on-off valve 22 is closed, unlike the normal operation (separation composition) during the heating operation shown in FIG. This is because the outdoor temperature during cooling operation is higher than that during heating operation, the ambient temperature in the outdoor unit in which the gas-liquid separator 17 is installed is high, and R1234ze (E), which is a high-boiling refrigerant, also evaporates. This is because there is a risk of joining the refrigerant passing through the return pipe 21 and performing the refrigeration cycle. When the gas-liquid separator 17 is installed in an environment (for example, indoors) that is not affected by the outside air temperature as compared with the inside of the outdoor unit, it is for the gas return pipe as in the normal operation (separation composition) during the heating operation. The on-off valve 22 may be opened.

[Mixed operation: during cooling operation]
FIG. 9 shows the mixing operation during the cooling operation. The mixing operation is performed after the above-described normal operation (separation composition), and is an operation in which R1234ze (E) is mixed in the refrigerant that performs the refrigeration cycle to reduce the mixing ratio of R32 in the refrigerant.

  The extraction piping on-off valve 20 is open, the gas return piping on-off valve 22 is closed, and the liquid return piping on-off valve 24 is open.

  By opening the extraction pipe on-off valve 20, the liquid refrigerant is introduced into the gas-liquid separator 17 from between the condenser 5 and the expansion valve 7. Since the gas return pipe open / close valve 22 is closed in the gas / liquid separator 17, R32 evaporated in the gas / liquid separator 17 is not supplied from the joining position B to the refrigerant that performs the refrigeration cycle. . On the other hand, since the liquid return pipe opening / closing valve 24 is opened, the liquid refrigerant stored in the gas-liquid separator 17 is guided from the merging position B to the evaporator 9 through the liquid return pipe 23. As a result, the liquid refrigerant in the gas-liquid separator 17 in which R1234ze (E) is concentrated by the separation operation (see FIG. 7) is returned to the refrigerant that performs the refrigeration cycle, so that R1234ze (E in the refrigerant that performs the refrigeration cycle). ) Mixing ratio increases.

  Next, a control method of the refrigeration apparatus 1 during the cooling operation will be described with reference to FIG. Each step shown below is performed by a command from the control unit.

  When the operation is started, the process proceeds to step S21, where the separation operation (see FIG. 7) is performed, and the mixing ratio of R32 in the refrigerant that performs the refrigeration cycle is increased. Thereby, the cooling operation with improved COP is performed (see FIG. 13).

  While performing the separation operation in step S21, it is determined whether the suction superheat degree of the compressor 3 is less than 2 ° C. or whether a predetermined time (for example, 1 hour) has passed since the separation operation was started ( Step S22).

  In step S22, if the suction superheat is not less than 2 ° C. and one hour has not passed since the separation operation, the process returns to step S21 and the separation operation is continued.

  In step S22, when the suction superheat degree is less than 2 ° C. or one hour or more has elapsed from the separation operation, the process proceeds to step S23, and normal operation (separation composition) is performed (see FIG. 8). In the normal operation (separation composition), an operation is performed in which R1234ze (E) is separated from the refrigerant that performs the refrigeration cycle to increase the mixing ratio of R32. Thereby, the cooling operation with high COP is continued.

  During the normal operation (separation composition) in step S23, it is determined whether or not the discharge temperature Tho-D measured by the discharge temperature sensor 13 exceeds a predetermined value (for example, 110 ° C.) (step S24). When the discharge temperature Th0-D exceeds 110 ° C., the process proceeds to step S25 and a mixing operation (see FIG. 9) is performed. In the mixing operation, R1234ze (E) is mixed in the refrigerant performing the refrigeration cycle, and the operation is performed so as to approach the mixing ratio at the time of sealing. Thereby, the mixing ratio of R32 in the refrigerant that performs the refrigeration cycle decreases, and the discharge temperature decreases. The mixing operation is terminated after a predetermined time (for example, 5 minutes) has elapsed, and the routine proceeds to step S26 where the normal operation (encapsulated composition) is performed (see FIG. 6).

  In normal operation (encapsulated composition), the mixing ratio in the refrigerant that performs the refrigeration cycle is equal to that at the time of refrigerant charging, and the mixing ratio of R32 is not large, so the discharge gas temperature of the refrigerant gas discharged from the compressor 3 is predetermined. The operation is kept below the value.

  During normal operation (encapsulation composition) in step S26, it is determined whether there is a unit stop command (step S27). When the unit stop command is issued, the refrigeration apparatus 1 is stopped and the process is terminated. If the unit stop command has not been issued, the process returns to step S26 to continue the normal operation (encapsulated composition).

  If it is determined in step S24 that the discharge temperature Tho-D does not exceed 110 ° C., the process proceeds to step S28 to determine whether a unit stop command is present. If no unit stop command has been issued, the process returns to step S23 to continue normal operation (separation composition). When the unit stop command is issued, the process proceeds to step S29, and after the mixing operation is performed for a predetermined time (for example, 5 minutes), the refrigeration apparatus 1 is stopped and the process is terminated. By performing the mixing operation before stopping the refrigeration apparatus 1, the mixing ratio in the refrigerant that performs the refrigeration cycle at the next start-up is returned when the refrigerant is charged.

As described above, according to the present embodiment, the following operational effects are obtained.
The pipe 19, 21, 23 is connected to the gas-liquid separator 17, and the gas refrigerant or liquid refrigerant separated by the gas-liquid separator 17 can be refrigerated by simply controlling the on-off valves 20, 22, 24. Since it can be returned to the inside, the mixing ratio of the low-boiling point refrigerant (R32) and the high-boiling point refrigerant (R1234ze (E)) can be arbitrarily changed with a simple configuration.

  During the heating operation, since the outside air temperature is generally low, the temperature of the evaporator 9 becomes low. When the temperature of the evaporator 9 becomes equal to or lower than a predetermined value, for example, a problem that frost formation occurs in the evaporator occurs. Therefore, when the outside air temperature is lower than a predetermined value (for example, 10 ° C.) or the evaporator outlet temperature is lower than the predetermined value (for example, −3 ° C.), the gas return pipe on-off valve 22 is opened to Increase the ratio of R32 (low boiling point refrigerant) in the cycle. At this time, by opening the take-off piping on-off valve 20 as well, the refrigerant is guided from the refrigeration cycle to the gas-liquid separator 17, and the gas-liquid separator 17 performs gas-liquid separation so that R32 is placed in the refrigeration cycle. By returning, the rate increase of R32 in the refrigeration cycle is further promoted. By performing such a separation operation (see FIG. 2), by performing a separation operation in which R1234ze (E) (high boiling point refrigerant) is separated from the refrigerant that performs the refrigeration cycle and the ratio of R32 is increased, temperature slip is reduced. The frosting can be suppressed by reducing the temperature and increasing the saturation temperature in the evaporator 9.

  After a predetermined period (for example, 1 hour) has elapsed since the separation operation (see FIG. 2), or after the intake superheat has become less than a predetermined value (for example, 2 ° C.), the extraction pipe on-off valve 20 is closed. Thus, taking out a part of the refrigerant that performs the refrigeration cycle to the gas-liquid separator 17 is stopped (see FIG. 3). Thereby, the control which raises the ratio of R32 in the refrigerant | coolant which performs a refrigerating cycle can be stopped, and a normal driving | operation (separation composition) can be performed with the composition of the mixed refrigerant after performing a separation driving | operation.

If the outside air temperature becomes a predetermined value (for example, 10 ° C.) or more during the heating operation, there is no possibility of a problem such as frost formation on the evaporator 9. Therefore, when the outside air temperature becomes equal to or higher than a predetermined value, the gas return pipe on-off valve 22 is closed to stop the R32 from being returned preferentially during the refrigeration cycle. Then, the on-off valve 24 for the liquid return pipe is opened to return R1234ze (E), which is present in the liquid refrigerant in the gas-liquid separator 17, to the refrigeration cycle. At this time, by opening the take-off piping on-off valve 20 as well, the refrigerant is led from the refrigeration cycle to the gas-liquid separator 17, and the gas-liquid separator 17 performs gas-liquid separation, so that R1234ze ( By preferentially returning E) into the refrigeration cycle, the rate of R1234ze (E) in the refrigeration cycle is increased.
Thus, by performing the mixing operation in which R1234ze (E) is mixed in the refrigerant that performs the refrigeration cycle, the ratio of R1234ze (E) in the refrigerant can be increased and returned to the mixing ratio at the time of filling the refrigerant. .
Further, when the discharge gas temperature discharged from the compressor 3 becomes a predetermined value (for example, 110 ° C.) or higher, the discharge gas temperature is lowered by returning the mixing ratio of the refrigerant at the time of filling the refrigerant by the mixing operation. Can do.

  During the cooling operation, by performing a separation operation (see FIG. 7) in which the extraction piping on-off valve 20 and the gas return piping on-off valve 22 are opened, the ratio of R32 in the refrigerant that performs the refrigeration cycle is increased. Thereby, highly efficient cooling operation is realizable.

  Even during the cooling operation, when the discharge gas temperature becomes a predetermined value (for example, 110 ° C.) or more, the extraction piping on-off valve 20 is opened, the gas return piping on-off valve 22 is closed, and the liquid return piping is on. By performing the mixing operation (see FIG. 9) in which the on-off valve 24 is opened, the ratio of R1234ze (E) in the refrigerant is increased and returned to the mixing ratio at the time of charging the refrigerant. Thereby, protection of an apparatus can be aimed at by avoiding that the discharge gas temperature of the compressor 3 becomes high too much.

  In the above-described embodiment, the refrigeration apparatus capable of switching between cooling and heating has been described. However, the present invention is not limited to this and is also applied to a refrigeration apparatus that performs only heating operation or cooling operation. be able to.

DESCRIPTION OF SYMBOLS 1 Refrigeration apparatus 3 Compressor 5 Condenser 7 Expansion valve 9 Evaporator 11 Suction pressure sensor 13 Discharge temperature sensor 15 Evaporator outlet temperature sensor 17 Gas-liquid separator 19 Extraction piping 20 Extraction piping on-off valve 21 Gas return piping 22 Gas return Pipe open / close valve 23 Liquid return pipe 24 Liquid return pipe open / close valve A Extraction position B Merge position

Claims (7)

A compressor that compresses a non-azeotropic refrigerant mixture in which a low-boiling refrigerant and a high-boiling refrigerant having different boiling points are mixed;
A condenser for condensing a non-azeotropic refrigerant mixture led from the compressor;
An expansion valve for expanding the non-azeotropic refrigerant mixture led from the condenser;
An evaporator for evaporating the non-azeotropic refrigerant mixture led from the expansion valve;
An extraction pipe for taking out part of the non-azeotropic refrigerant mixture from between the condenser and the expansion valve;
An opening / closing valve for the extraction pipe provided in the extraction pipe;
A gas-liquid separator connected to the extraction pipe and storing a non-azeotropic refrigerant mixture for gas-liquid separation;
A gas return pipe connecting between the expansion valve and the evaporator and a gas phase part in the gas-liquid separator;
An on-off valve for the gas return pipe provided in the gas return pipe;
A liquid return pipe connecting between the expansion valve and the evaporator and a liquid phase part in the gas-liquid separator;
An opening / closing valve for the liquid return pipe provided in the liquid return pipe;
A control unit for controlling the on-off valve for the extraction pipe, the on-off valve for the gas return pipe, and the on-off valve for the liquid return pipe;
A refrigeration apparatus comprising:   The controller opens the extraction pipe on-off valve and opens the gas return pipe on-off valve when the outside air temperature is lower than a predetermined value or the evaporator temperature is lower than a predetermined value during heating operation. The refrigeration apparatus according to claim 1, wherein a separation operation is performed in which the gas refrigerant separated by the gas-liquid separator is returned from the gas return pipe to the evaporator side.   The control unit closes the extraction pipe on-off valve after a predetermined period has elapsed since the start of the separation operation, or after the degree of superheat of the non-azeotropic refrigerant mixture sucked by the compressor becomes less than a predetermined value. The refrigeration apparatus according to claim 2, wherein:   When the outside air temperature is equal to or higher than a predetermined value or the discharge gas temperature discharged from the compressor is equal to or higher than a predetermined value, the control unit opens the extraction pipe on-off valve and opens the gas return pipe on-off valve. The refrigeration apparatus according to claim 2 or 3, wherein the refrigeration apparatus is closed and the on-off valve for the liquid return pipe is opened.   2. The refrigeration apparatus according to claim 1, wherein the control unit opens the extraction pipe on-off valve and opens the gas return pipe on-off valve during cooling operation.   The control unit opens the extraction piping on-off valve, closes the gas return piping on-off valve, and closes the liquid return piping when the temperature of the discharge gas discharged from the compressor exceeds a predetermined value. 5. The refrigeration apparatus according to claim 4, wherein the on-off valve is opened. A compressor that compresses a non-azeotropic refrigerant mixture in which a low-boiling refrigerant and a high-boiling refrigerant having different boiling points are mixed;
A condenser for condensing a non-azeotropic refrigerant mixture led from the compressor;
An expansion valve for expanding the non-azeotropic refrigerant mixture led from the condenser;
An evaporator for evaporating the non-azeotropic refrigerant mixture led from the expansion valve;
An extraction pipe for taking out part of the non-azeotropic refrigerant mixture from between the condenser and the expansion valve;
An opening / closing valve for the extraction pipe provided in the extraction pipe;
A gas-liquid separator connected to the extraction pipe and storing a non-azeotropic refrigerant mixture for gas-liquid separation;
A gas return pipe connecting between the expansion valve and the evaporator and a gas phase part in the gas-liquid separator;
An on-off valve for the gas return pipe provided in the gas return pipe;
A liquid return pipe connecting between the expansion valve and the evaporator and a liquid phase part in the gas-liquid separator;
An opening / closing valve for the liquid return pipe provided in the liquid return pipe;
A method for controlling a refrigeration apparatus comprising:
A control method for a refrigerating apparatus, wherein opening / closing control of the extraction piping on-off valve, the gas return piping on-off valve, and the liquid return piping on-off valve is performed.

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