WO2020066000A1

WO2020066000A1 - Outdoor unit for refrigeration cycle device, refrigeration cycle device, and air conditioning device

Info

Publication number: WO2020066000A1
Application number: PCT/JP2018/036525
Authority: WO
Inventors: 智隆石川; 悠介有井
Original assignee: 三菱電機株式会社
Priority date: 2018-09-28
Filing date: 2018-09-28
Publication date: 2020-04-02
Also published as: CN112739961A; JP6972369B2; CN112739961B; JPWO2020066000A1

Abstract

An outdoor unit (2) comprises a compressor (10), a condenser (20), a control device (100), and a sub cooler (40). The control device (100) controls, on the basis of an evaporation temperature to be set for an indoor unit (3) evaporator (60), the pressure of a refrigerant flowing in the evaporator so as to be a target pressure. Using the relationship between the refrigerant pressure and a dew point-boiling point average temperature, which indicates the average of the saturated liquid temperature and saturated gas temperature for the refrigerant at that pressure, the control device (100) sets, as the target pressure, the pressure at which the dew point-boiling point average temperature is a set evaporation temperature. The sub cooler (40) is provided on the outlet side of the condenser (20) and is configured so as to cool the refrigerant output from the condenser (20).

Description

Outdoor unit of refrigeration cycle device, refrigeration cycle device, and air conditioner

The present disclosure relates to an outdoor unit of a refrigeration cycle device, a refrigeration cycle device, and an air conditioner.

冷凍 Refrigeration cycle devices using non-azeotropic refrigerants with low GWP (Global Warming Potential) have attracted attention in consideration of their impact on global warming. For example, Japanese Patent Application Laid-Open No. 8-75280 discloses a refrigerating air conditioner using a non-azeotropic refrigerant mixture. In this refrigerating air conditioner, the rotation speed of the fan of the outdoor unit is controlled so that the evaporation pressure of the evaporator matches the target value. The target value of the evaporation pressure is set as a pressure at which the evaporation temperature becomes 0 ° C.

The non-azeotropic refrigerant mixture has a gradient of saturation temperature (evaporation temperature) according to the dryness of the refrigerant under a constant pressure. Therefore, in this refrigerating air conditioner, the evaporation temperature of the non-azeotropic mixed refrigerant is defined as the average value of the saturated gas temperature and the saturated liquid temperature, and the evaporation pressure is controlled to a pressure target value at which the evaporation temperature becomes 0 ° C. (See Patent Document 1).

JP-A-8-75280

In the refrigerating and air-conditioning apparatus described in Patent Literature 1, the evaporation temperature is represented by the average value of the saturated gas temperature and the saturated liquid temperature. However, when the saturated liquid temperature and the refrigerant temperature on the evaporator inlet side deviate, the above described The difference between the average value and the actual evaporation temperature increases, and the accuracy of the control of the evaporation temperature decreases. In this case, for example, it is conceivable to detect the refrigerant temperature on the evaporator inlet side with a temperature sensor and use the detected value of the temperature sensor in place of the saturated liquid temperature. This leads to an increase in the cost of the device.

The present disclosure has been made in order to solve such a problem, and an object of the present disclosure is to realize, at low cost, improved accuracy of control of the evaporation temperature when a non-azeotropic refrigerant is used in a refrigeration cycle device. That is.

The outdoor unit of the present disclosure is an outdoor unit of a refrigeration cycle device, and includes a compressor that compresses a refrigerant, a condenser that condenses the refrigerant output from the compressor, a control device, and a supercooler. The control device controls the pressure of the refrigerant flowing through the evaporator to a target pressure based on the evaporation temperature set for the evaporator of the indoor unit connected to the outdoor unit. The controller uses the relationship between the refrigerant pressure and the dew-boiling average temperature indicating the average of the saturated liquid temperature and the saturated gas temperature of the refrigerant at that pressure to determine the pressure when the dew-boiling average temperature is the set evaporation temperature. Is set as the target pressure. The subcooler is provided on the outlet side of the condenser, and is configured to cool the refrigerant output from the condenser.

In this outdoor unit, the pressure when the average dew-boiling temperature is the set evaporation temperature is set as the target pressure, and the pressure of the refrigerant flowing through the evaporator is controlled to the target pressure. Accordingly, even when a non-azeotropic refrigerant having a gradient of the evaporation temperature according to the dryness of the refrigerant under a constant pressure is used, the evaporation temperature can be controlled.

Here, the refrigerant on the evaporator inlet side is usually in a gas-liquid two-phase state, and the refrigerant on the evaporator inlet side is higher than the saturated liquid temperature. When the temperature of the refrigerant at the evaporator inlet side deviates from the temperature of the saturated liquid, the accuracy of the control of the evaporating temperature decreases as described above. Therefore, in this outdoor unit, a subcooler is provided on the outlet side of the condenser. By providing the subcooler, the temperature of the refrigerant at the evaporator inlet side can be reduced to approach the saturated liquid temperature. As a result, the difference between the refrigerant temperature on the evaporator inlet side and the saturated liquid temperature can be suppressed, and the accuracy of evaporating temperature control can be improved. Further, according to this outdoor unit, there is no need to provide a temperature sensor for detecting the refrigerant temperature on the evaporator inlet side, and therefore, the cost of the apparatus is also reduced.

According to the outdoor unit, the refrigeration cycle device, and the air conditioner of the present disclosure, when a non-azeotropic refrigerant is used, it is possible to improve the accuracy of controlling the evaporation temperature at low cost.

1 is an overall configuration diagram of a refrigeration apparatus using an outdoor unit according to Embodiment 1 of the present disclosure. It is a ph diagram explaining the property of an azeotropic refrigerant. It is a ph diagram explaining the property of a non-azeotropic refrigerant. FIG. 3 is a ph diagram showing a state of the refrigerant when a non-azeotropic refrigerant is used in the refrigeration apparatus of the present disclosure. 3 is a flowchart illustrating an example of a processing procedure of evaporating temperature control executed by the control device illustrated in FIG. 1. FIG. 4 is a diagram showing an example of a pressure-dew-boiling average temperature map. It is a flow chart which shows an example of the processing procedure of evaporation temperature control in a modification. FIG. 9 is an overall configuration diagram of a refrigeration apparatus using an outdoor unit according to a second embodiment. 1 is an overall configuration diagram of an air conditioner including a refrigeration cycle in which an outdoor unit according to Embodiment 1 is used. FIG. 13 is an overall configuration diagram of an air conditioner including a refrigeration cycle in which an outdoor unit according to Embodiment 2 is used.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

Embodiment 1 FIG.
FIG. 1 is an overall configuration diagram of a refrigeration apparatus using an outdoor unit according to Embodiment 1 of the present disclosure. Referring to FIG. 1, a refrigeration apparatus 1 includes an outdoor unit 2 and an indoor unit 3. The outdoor unit 2 includes a compressor 10, a condenser 20, a fan 22, a subcooler 40, a fan 42,

pipes

80, 81, 83, 85, a pressure sensor 90, and a control device 100. . The indoor unit 3 includes an expansion valve 50, an evaporator 60, a fan 62, and a pipe 84. The indoor unit 3 is connected to the outdoor unit 2 through

pipes

83 and 85.

The pipe 80 connects the discharge port of the compressor 10 and the condenser 20. The pipe 81 connects the condenser 20 and the subcooler 40. The pipe 83 connects the subcooler 40 and the expansion valve 50. The pipe 84 connects the expansion valve 50 and the evaporator 60. The pipe 85 connects the evaporator 60 and the suction port of the compressor 10.

The compressor 10 compresses the refrigerant sucked from the pipe 85 and outputs the compressed refrigerant to the pipe 80. The compressor 10 is configured to adjust the rotation speed according to a control signal from the control device 100. By adjusting the rotation speed of the compressor 10, the circulation amount of the refrigerant is adjusted, and the capacity of the refrigeration apparatus 1 can be adjusted. As described later, in the first embodiment, by adjusting the rotation speed of the compressor 10, the low pressure side pressure of the refrigeration system 1 (the refrigerant pressure from the outlet side of the expansion valve 50 to the inlet side of the compressor 10) is adjusted. ) Is controlled. Various types can be used for the compressor 10, and for example, a scroll type, a rotary type, a screw type, and the like can be used.

The condenser 20 condenses the refrigerant output from the compressor 10 to the pipe 80 and outputs the refrigerant to the pipe 81. The condenser 20 is configured such that the high-temperature and high-pressure gas refrigerant output from the compressor 10 performs heat exchange (radiation) with the outside air. By this heat exchange, the refrigerant is condensed and changes to a liquid phase. The fan 22 supplies the outside air to the condenser 20 where the refrigerant performs heat exchange in the condenser 20. By adjusting the rotation speed of the fan 22, the refrigerant pressure (high-pressure side pressure) on the outlet side of the compressor 10 can be adjusted.

The subcooler 40 is configured such that the liquid refrigerant output from the condenser 20 to the pipe 81 further performs heat exchange (radiation) with the outside air. The refrigerant becomes a liquid refrigerant whose subcooling degree is further increased by passing through the subcooler 40. The fan 42 supplies the outside air in which the refrigerant performs heat exchange in the subcooler 40 to the subcooler 40. By providing the subcooler 40, the temperature of the refrigerant supplied to the indoor unit 3 can be reduced, and the temperature of the refrigerant on the inlet side of the evaporator 60 can be made closer to the saturated liquid temperature.

The supercooler 40 is not limited to the air-cooled type using the fan 42 as described above, but may be a water-cooled type or a type using a refrigerant cooled by another refrigeration cycle. Is also good. Note that a liquid reservoir for temporarily storing the liquid refrigerant output from the condenser 20 may be provided between the condenser 20 and the subcooler 40.

(4) The expansion valve 50 decompresses the refrigerant output from the subcooler 40 to the pipe 83 and outputs it to the pipe 84. When the opening degree of the expansion valve 50 is changed in the closing direction, the refrigerant pressure on the exit side of the expansion valve 50 decreases, and the dryness of the refrigerant increases. When the opening of the expansion valve 50 is changed in the opening direction, the refrigerant pressure on the outlet side of the expansion valve 50 increases, and the dryness of the refrigerant decreases.

The evaporator 60 evaporates the refrigerant output from the expansion valve 50 to the pipe 84 and outputs the refrigerant to the pipe 85. The evaporator 60 is configured such that the refrigerant decompressed by the expansion valve 50 performs heat exchange (heat absorption) with the air in the indoor unit 3. The refrigerant evaporates by passing through the evaporator 60 to become superheated steam. The fan 62 supplies to the evaporator 60 external air in which the refrigerant performs heat exchange in the evaporator 60. Pressure sensor 90 detects refrigerant pressure (low pressure side pressure) LP on the suction side of compressor 10 and outputs the detected value to control device 100.

The control device 100 includes a CPU (Central Processing Unit) 102, a memory 104 (ROM (Read Only Memory) and RAM (Random Access Memory)), an input / output buffer (not shown) for inputting and outputting various signals, and the like. It is comprised including. The CPU 102 executes a program stored in the ROM by expanding the program in the RAM or the like. The program stored in the ROM is a program in which the processing procedure of the control device 100 is described. The control device 100 controls each device in the outdoor unit 2 according to these programs. This control is not limited to processing by software, and processing by dedicated hardware (electronic circuit) is also possible.

<Description of azeotropic refrigerant and non-azeotropic refrigerant>
The refrigeration apparatus 1 in the present disclosure is configured to operate using either an azeotropic refrigerant or a non-azeotropic refrigerant. The azeotropic refrigerant may be a single refrigerant (single refrigerant) or a refrigerant in which a plurality of refrigerants are mixed (mixed refrigerant). The azeotropic refrigerant is, for example, R410A, R404A, etc., but is not limited thereto.

The non-azeotropic refrigerant is a mixed refrigerant, and has a gradient of a saturation temperature according to the dryness (wetness) of the refrigerant under a certain pressure. Specifically, under a certain pressure, the drying temperature increases and the evaporation temperature increases. Non-azeotropic refrigerants include, for example, R407C, R448A, R463A, etc., but are not limited thereto.

FIG. 2 is a ph diagram explaining the properties of the azeotropic refrigerant. In FIG. 2, the vertical axis indicates the pressure p, and the horizontal axis indicates the specific enthalpy h (kJ / kg) (hereinafter, simply referred to as “enthalpy”). FIG. 2 does not show the state of the refrigerant in the refrigeration apparatus 1 of the present disclosure, but illustrates the state of the refrigerant in a general refrigeration apparatus using an azeotropic refrigerant.

Referring to FIG. 2, a solid line connecting points P11 to P14 indicates a change in pressure and enthalpy of the refrigerant circulating in the refrigerant device. Point P14 → point P11 indicates compression of the refrigerant in the compressor (isentropic change), and point P11 → point P12 indicates equal pressure cooling in the condenser. Further, a point P12 → point P13 indicates pressure reduction in the expansion valve, and a point P13 → point P14 indicates equal pressure heating in the evaporator. The dotted line indicates the isotherm of the refrigerant, and the lower the pressure, the lower the temperature.

The azeotropic refrigerant has a constant saturation temperature during a phase change of the refrigerant under a constant pressure. For example, as shown in the drawing, when the low pressure side (evaporation pressure) of the refrigerating apparatus is under a constant pressure pe, the evaporation temperature becomes a constant temperature Te during the phase change of the refrigerant regardless of the dryness of the refrigerant. Become.

FIG. 3 is a ph diagram explaining the properties of the non-azeotropic refrigerant. FIG. 3 also does not show the state of the refrigerant in the refrigeration apparatus 1 of the present disclosure, but illustrates the state of the refrigerant in a general refrigeration apparatus using a non-azeotropic refrigerant.

を Referring to FIG. 3, the solid line connecting points P11 to P14 is the same as that shown in FIG. Non-azeotropic refrigerants have a gradient of saturation temperature according to the dryness (wetness) of the refrigerant during a phase change of the refrigerant under a constant pressure. For example, as shown in the drawing, the saturated liquid temperature TL and the saturated gas temperature TG are different from each other when the low-pressure side pressure (evaporation pressure) of the refrigerating apparatus is constant at a pe, and the saturated gas temperature TG is the saturated liquid temperature. Higher than TL. The temperature Ti of the refrigerant on the evaporator inlet side and the temperature To of the refrigerant on the outlet side are different from each other. Even if the degree of superheat on the evaporator outlet side is 0, the temperature To is higher than the temperature Ti.

<Explanation of evaporation temperature control>
In the refrigeration system, a target value of the evaporation temperature (saturation temperature on the low pressure side) of the evaporator is set according to the required refrigeration capacity, and the low pressure side pressure (flow through the evaporator) is adjusted so that the evaporation temperature matches the target value. (Pressure of the refrigerant). More specifically, the target pressure corresponding to the target value of the evaporation temperature is determined, and the rotation speed of the compressor and the like are adjusted such that the low-pressure side pressure matches the target pressure.

When the azeotropic refrigerant is used, the target pressure corresponding to the target value of the evaporation temperature becomes a constant value, and the feedback control is performed based on the pressure deviation from the target pressure. By controlling the low pressure side pressure to the target pressure, the evaporation temperature is controlled to the target value (hereinafter, such control of the evaporation temperature is referred to as “evaporation temperature control”).

On the other hand, when a non-azeotropic refrigerant is used, as described above, the evaporation temperature has a gradient according to the dryness of the refrigerant during the phase change of the refrigerant under a constant pressure. In other words, during the phase change of the refrigerant, the target pressure corresponding to the target value of the evaporation temperature changes. Specifically, the target pressure decreases as the dryness of the refrigerant increases.

して In consideration of such a pressure change, it is conceivable to maintain the evaporation temperature by giving a pressure loss to the refrigerant during the evaporation process in the evaporator. However, such a configuration reduces the suction pressure of the compressor, so that the load on the compressor increases and the performance of the refrigeration system decreases.

Therefore, in the refrigeration apparatus 1 according to the first embodiment, the evaporation temperature at a certain pressure is represented by the dew-boiling average temperature indicating the average of the saturated liquid temperature and the saturated gas temperature of the refrigerant at a certain pressure. Then, a pressure at which the dew-boiling average temperature becomes a target value of the evaporation temperature is set as a target pressure, and feedback control is performed based on a pressure deviation from the target pressure. Thus, the above-described evaporation temperature control performed when using the azeotropic refrigerant can be applied also when using the non-azeotropic refrigerant.

However, when the saturated liquid temperature of the refrigerant is different from the refrigerant temperature on the evaporator inlet side, the accuracy of the evaporation temperature control is reduced. The refrigerant on the evaporator inlet side is in a gas-liquid two-phase state by passing through the expansion valve, and the refrigerant temperature on the evaporator inlet side is higher than the saturated liquid temperature. If the refrigerant temperature on the evaporator inlet side deviates from the saturated liquid temperature, the departure between the dew-boiling average temperature and the actual evaporating temperature increases, and the accuracy of evaporating temperature control decreases.

In this case, it is conceivable that the temperature of the refrigerant at the evaporator inlet side is detected by a temperature sensor and the detected value of the temperature sensor is used instead of the saturated liquid temperature. Increases costs.

Therefore, in the refrigerating apparatus 1 according to the first embodiment, the subcooler 40 is provided on the outlet side of the condenser 20, and the degree of subcooling of the refrigerant supplied to the indoor unit 3 is increased. As a result, the temperature of the refrigerant on the inlet side of the evaporator 60 decreases, and approaches the saturated liquid temperature. Therefore, the difference between the refrigerant temperature on the inlet side of the evaporator and the saturated liquid temperature is suppressed, and the accuracy of the evaporation temperature control is improved. Further, since there is no need to provide a temperature sensor for detecting the temperature of the refrigerant on the inlet side of the evaporator 60, the cost of the apparatus is also reduced.

FIG. 4 is a ph diagram showing a state of the refrigerant when a non-azeotropic refrigerant is used in the refrigeration apparatus 1 according to the first embodiment. Referring to FIG. 4, a solid line connecting points P21 to P25 indicates a change in pressure and enthalpy of the refrigerant circulating in refrigerant device 1. Point P25 → point P21 indicates compression of the refrigerant in the compressor 10 (isentropic change), and point P21 → point P22 indicates equal pressure cooling in the condenser 20. Point P22 → point P23 indicates equal pressure cooling in the subcooler 40. The point P23 → point P24 indicates the pressure reduction in the expansion valve 50, and the point P24 → point P25 indicates the equal pressure heating in the evaporator 60.

In this refrigerating apparatus 1, the supercooler 40 is provided, so that the degree of supercooling SC of the refrigerant increases, and as a result, the refrigerant temperature Ti (point P24) on the inlet side of the evaporator 60 approaches the saturated liquid temperature TL. I can do it. As the refrigerant temperature Ti on the inlet side of the evaporator 60 approaches the saturated liquid temperature TL, the dew-boiling average temperature Te indicating the average of the saturated liquid temperature TL and the saturated gas temperature TG becomes the temperature of the refrigerant flowing through the evaporator 60. It approaches the average value (the average of the inlet temperature Ti and the outlet temperature To). Therefore, in the refrigerating apparatus 1, it can be said that the temperature of the refrigerant flowing through the evaporator 60 can be accurately represented by the average dew-boiling temperature Te.

FIG. 5 is a flowchart illustrating an example of a processing procedure of the evaporation temperature control performed by the control device 100 illustrated in FIG. A series of processes shown in this flowchart is repeatedly executed during the operation of the refrigeration apparatus 1.

参照 Referring to FIG. 5, control device 100 acquires the set evaporation temperature (step S10). The evaporation temperature may be directly set by the user of the refrigeration apparatus 1 or set based on a temperature setting set by the user (for example, a temperature setting in a warehouse where the refrigeration apparatus 1 is installed). May be used or may be set in advance.

Next, the control device 100 reads the pressure-dew-boiling average temperature map of the refrigerant used in the refrigerating device 1 (step S20). This map is a list showing the relationship between the pressure of the refrigerant being used and the average dew-boiling temperature at that pressure. Using this map, a pressure corresponding to a certain dew-boiling average temperature can be obtained. . A map is prepared in advance for each refrigerant (including both an azeotropic refrigerant and a non-azeotropic refrigerant) that can be used in the refrigeration apparatus 1 and stored in the ROM of the memory 104.

FIG. 6 is a diagram showing an example of a pressure-dew-boiling average temperature map. Referring to FIG. 6, for a certain refrigerant, saturated liquid temperature TL and saturated gas temperature TG are physical values uniquely determined by pressure pe. The average dew-boiling temperature Te is an average value of the saturated liquid temperature TL and the saturated gas temperature TG, and the average dew-boiling temperature Te is also uniquely determined by the pressure pe. In the pressure-dew-boiling average temperature map, the dew-boiling average temperature Te is associated with each pressure Pe. Such a pressure-dew-boiling average temperature map is prepared in advance for each refrigerant usable in the refrigeration apparatus 1.

Referring to FIG. 5 again, control device 100 uses the pressure-dew / boiling average temperature map read in step S20 to determine the pressure corresponding to the dew / boiling average temperature corresponding to the set evaporation temperature acquired in step S10. Is determined as the target pressure for the evaporation temperature control (step S30). If the dew-boiling average temperature that matches the set evaporation temperature obtained in step S10 is not shown in the map, control device 100 performs interpolation calculation using the dew-boiling average temperature close to the set evaporation temperature. To determine the target pressure.

Next, control device 100 acquires a detection value of pressure LP from pressure sensor 90 (step S40). Then, control device 100 determines whether or not the acquired detected value of pressure LP is higher than the target pressure determined in step S30 (step S50).

If the pressure LP is higher than the target pressure (YES in step S50), control device 100 controls compressor 10 to increase the rotation speed of compressor 10 (step S60). On the other hand, if it is determined in step S50 that pressure LP is equal to or lower than the target pressure (NO in step S50), control device 100 controls compressor 10 so as to reduce the rotation speed of compressor 10 (step S70). .

The amount of change in the rotation speed of the compressor 10 may be variable according to the amount of deviation between the pressure LP and the target pressure. As described above, by adjusting the rotation speed of the compressor 10 based on the deviation between the pressure LP and the target pressure, the pressure LP is adjusted near the target pressure. As a result, the evaporation temperature represented by the dew-boiling average temperature is controlled to the set evaporation temperature.

In the above description, the pressure LP is adjusted by adjusting the rotation speed of the compressor 10. However, the rotation speed of the fan 62 of the evaporator 60 or the expansion valve 50 is replaced with the rotation speed of the compressor 10. The pressure LP may be adjusted by adjusting the opening degree. When adjusting the rotation speed of the fan 62 of the evaporator 60 or the opening degree of the expansion valve 50, the outdoor unit 2 provided with the control device 100 and the indoor unit 3 provided with the fan 62 and the expansion valve 50 It is necessary to communicate between

In the above flowchart, it is not determined whether the refrigerant used in the refrigeration apparatus 1 is a non-azeotropic refrigerant or an azeotropic refrigerant. When the refrigerant is an azeotropic refrigerant, the average dew-boiling temperature is the evaporation temperature itself, so this flowchart can be applied to the case where an azeotropic refrigerant is used.

As described above, in the first embodiment, the dew-boiling average temperature at a certain pressure represents the evaporation temperature at that pressure. Then, a pressure at which the dew-boiling average temperature reaches the set evaporation temperature is set as a target pressure, and feedback control based on a pressure deviation from the target pressure is performed. Thereby, the evaporation temperature control performed when using the azeotropic refrigerant can be applied even when using the non-azeotropic refrigerant.

In the first embodiment, the subcooler 40 is provided on the outlet side of the condenser 20 to increase the degree of supercooling of the refrigerant. Thus, the difference between the refrigerant temperature on the inlet side of the evaporator 60 and the saturated liquid temperature is suppressed, and the accuracy of the evaporation temperature control is improved. Further, since there is no need to provide a temperature sensor for detecting the temperature of the refrigerant on the inlet side of the evaporator 60, the cost of the apparatus is also reduced.

Modified example.
In the first embodiment, the pressure-dew-boiling average temperature map is used even when the azeotropic refrigerant is used without discriminating whether the refrigerant used is an azeotropic refrigerant or a non-azeotropic refrigerant. The target pressure was determined. In this modification, it is determined whether the refrigerant is an azeotropic refrigerant or a non-azeotropic refrigerant. When the azeotropic refrigerant is used, a pressure (evaporation pressure) uniquely determined from the set evaporation temperature is set as the target pressure. Is set.

FIG. 7 is a flowchart illustrating an example of a processing procedure of evaporating temperature control in a modification. This flowchart corresponds to the flowchart of FIG. 5, and a series of processes shown in this flowchart is also repeatedly executed during the operation of the refrigeration apparatus 1.

Referring to FIG. 7, the processes in steps S110 and S140 to S190 are the same as the processes in steps S10 to S70 shown in FIG. 5, respectively. In this modification, when the set evaporation temperature is obtained in step S110, control device 100 determines whether or not the refrigerant used in refrigerating device 1 is a non-azeotropic refrigerant (step S120). ). Whether or not the refrigerant is a non-azeotropic refrigerant can be determined, for example, based on the type of refrigerant used by the user.

If it is determined in step S120 that the used refrigerant is not a non-azeotropic refrigerant, that is, it is an azeotropic refrigerant (NO in step S120), control device 100 sets target pressure based on the set evaporation temperature. Is set (step S130). In an azeotropic refrigerant, the relationship between pressure and evaporation temperature is one-to-one, and the target pressure can be determined based on the set evaporation temperature. The relationship between the pressure and the evaporation temperature is stored in the ROM of the memory 104 as a map. Then, after execution of step S130, control device 100 shifts the processing to step S160, and acquires a detection value of pressure LP from pressure sensor 90.

On the other hand, if it is determined in step S120 that the used refrigerant is a non-azeotropic refrigerant (YES in step S120), control device 100 shifts the processing to step S140 and sets the pressure of the used refrigerant. Reading the dew-boiling average temperature map from the memory 104; The processing after step S150 is the same as the processing after step S30 in the flowchart shown in FIG. 5, and thus the description will not be repeated.

As described above, according to this modified example, the same effect as in the first embodiment can be obtained.
Embodiment 2 FIG.
The second embodiment differs from the first embodiment in the configuration of the subcooler.

FIG. 8 is an overall configuration diagram of a refrigerating apparatus using the outdoor unit according to the second embodiment. Referring to FIG. 8, this refrigeration apparatus 1A includes an outdoor unit 2A and an indoor unit 3. The outdoor unit 2A includes a subcooler 40A and a compressor 10A instead of the subcooler 40 and the compressor 10 in the outdoor unit 2 of the first embodiment shown in FIG. And a bypass circuit for returning the refrigerant to the compressor 10A.

The subcooler 40A includes an internal heat exchanger 44 and an expansion valve 46. The internal heat exchanger 44 is configured to exchange heat between the refrigerant flowing through the pipe 81 on the outlet side of the condenser 20 and the refrigerant flowing through the pipe 87 forming the bypass circuit.

The expansion valve 46 reduces the pressure of the refrigerant flowing through the pipe 86 branched from the pipe 83 and outputs the reduced pressure to the pipe 87. The refrigerant that has passed through the expansion valve 46 is decompressed by the expansion valve 46 and has a reduced temperature. Accordingly, in the subcooler 40A, the refrigerant output from the condenser 20 can be further cooled by the refrigerant flowing through the pipe 87. That is, the degree of supercooling of the refrigerant output from the condenser 20 to the pipe 81 is increased by passing through the subcooler 40A.

The compressor 10A has an injection port. By connecting the pipe 87 to the injection port and returning the refrigerant flowing through the bypass circuit to the injection port, the temperature of the refrigerant discharged from the compressor 10A can be reduced. In this example, in order to obtain the effect of injection, the refrigerant flows through the bypass circuit even when using an azeotropic refrigerant that does not require supercooling of the refrigerant.

The configurations of the outdoor unit 2A according to the second embodiment and the refrigeration apparatus 1A using the same are the same as the configuration shown in FIG. 1 except for the configuration described above. The processing procedure of the evaporating temperature control executed by the control device 100 is the same as the flowchart shown in FIG. 5, and the flowchart shown in FIG. 7 can be adopted as a modification.

In the above description, the refrigerant flowing through the bypass circuit is returned to the injection port of the compressor 10A. However, instead of the compressor 10A, a compressor 10 having no injection port is employed, and the bypass circuit is used. The flowing refrigerant may be returned to the pipe 85 on the suction side of the compressor 10. In this case, when the azeotropic refrigerant is used, the expansion valve 46 is fully closed to shut off the bypass circuit, and when the non-azeotropic refrigerant is used, the expansion valve 46 is opened (with the throttle) and the bypass circuit and The supercooler 40A may function.

As described above, according to the second embodiment, since the subcooler 40A can be configured by the internal heat exchanger 44, the supercooling of the refrigerant can be performed without separately providing a configuration for using an external heat source. Can be enlarged. By providing such a supercooler 40A, the difference between the refrigerant temperature on the inlet side of the evaporator 60 and the saturated liquid temperature is suppressed, and the accuracy of the evaporation temperature control can be improved.

In the above first and second embodiments and the modifications, the outdoor unit and the refrigeration apparatus mainly used for a warehouse, a showcase, and the like have been representatively described. However, the outdoor unit according to the present disclosure is shown in FIGS. As described above, the present invention is also applicable to the

air conditioners

200 and 200A using the refrigeration cycle.

実施 The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description of the embodiments, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1,1A refrigerator, 2,2A outdoor unit, 3 indoor unit, 10,10A compressor, 20 condenser, 22,42,62 fan, 40,40A subcooler, 44 internal heat exchanger, 46,50 expansion Valve, 60 evaporator, 80-87 pipe, 90 pressure sensor, 100 control device, 102 CPU, 104 memory, 200, 200A air conditioner.

Claims

An outdoor unit of a refrigeration cycle device,
A compressor for compressing the refrigerant,
A condenser for condensing the refrigerant output from the compressor,
A control device that controls the pressure of the refrigerant flowing through the evaporator to a target pressure, based on an evaporation temperature set for the evaporator of the indoor unit connected to the outdoor unit,
The controller, the pressure, using the relationship between the dew-boiling average temperature indicating the average of the saturated liquid temperature and the saturated gas temperature of the refrigerant at the pressure, when the dew-boiling average temperature is the evaporation temperature Setting the pressure as the target pressure,
An outdoor unit of a refrigeration cycle device, comprising: a supercooler provided on an outlet side of the condenser and configured to cool a refrigerant output from the condenser.
The control device sets the pressure when the dew-boiling average temperature is the evaporation temperature as the target pressure regardless of whether the refrigerant is an azeotropic refrigerant or a non-azeotropic refrigerant. An outdoor unit of the refrigeration cycle apparatus according to item 1.
The control device includes:
If the refrigerant is a non-azeotropic refrigerant, the pressure when the dew-boiling average temperature is the evaporation temperature is set as the target pressure,
The outdoor unit of the refrigeration cycle device according to claim 1, wherein when the refrigerant is an azeotropic refrigerant, the pressure corresponding to the evaporation temperature is set as the target pressure.
The subcooler is
A bypass circuit configured to return a part of the refrigerant on the outlet side of the subcooler to the compressor without passing through the indoor unit,
An expansion valve provided in the bypass circuit;
4. The internal heat exchanger according to claim 1, further comprising an internal heat exchanger configured to perform heat exchange between the refrigerant output from the expansion valve and the refrigerant output from the condenser. 5. An outdoor unit of the refrigeration cycle apparatus according to item 1.
An outdoor unit according to any one of claims 1 to 4,
A refrigeration cycle device comprising: an indoor unit connected to the outdoor unit.
An air conditioner comprising the refrigeration cycle device according to claim 5.