JP7105933B2 - Outdoor unit of refrigerating device and refrigerating device provided with the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an outdoor unit of a refrigerating device and a refrigerating device including the same.

The refrigerating device is provided with a defrosting mode for melting frost adhering to the cooler. As a defrosting method, for example, a reverse hot gas defrosting method is known, in which a four-way valve changes the refrigerant circulation direction so that high-temperature gas from a compressor is sent to a cooler that normally functions as an evaporator.

Japanese Patent No. 5595245 (Patent Document 1) discloses a refrigerating device that performs defrosting by a reverse hot gas defrosting method in a low temperature side cycle of a binary cycle.

Japanese Patent No. 5595245

In the refrigeration system disclosed in Japanese Patent No. 5595245 (Patent Document 1), cooling by a cascade condenser that exchanges heat between the refrigerant in the high temperature side cycle and the refrigerant in the low temperature side cycle prevents the high pressure from rising during defrosting. can be suppressed.

A plate heat exchanger is generally used as a binary cycle cascade condenser. A plate heat exchanger has a small internal volume. Therefore, even if the cascade condenser promotes condensation of the refrigerant during defrosting, there is a limit to the pressure suppression effect. Therefore, if the frost on the evaporator completes melting during defrosting operation with the fan stopped, the refrigerant will not cool sufficiently and the refrigerant pressure will rise to the design pressure, and the operation will automatically stop for protection. there's a possibility that. Not only in the binary cycle, but also in a normal refrigerating cycle device, it is desirable to avoid a situation in which the refrigerant pressure rises excessively during the defrosting operation because the design pressure can be low.

SUMMARY OF THE INVENTION An object of the present invention is to provide a refrigeration system capable of suppressing an increase in refrigerant pressure during defrosting operation.

The present disclosure relates to an outdoor unit of a refrigeration system having a freezing mode and a defrosting mode. The outdoor unit includes a first compressor, a second heat exchanger, a four-way valve, and a refrigerant amount adjustment mechanism. The first compressor and the second heat exchanger are connected so that the first refrigerant circulates with the indoor unit in which the first expansion valve and the first heat exchanger are connected in series. The four-way valve allows the first refrigerant to flow in the positive direction toward the first expansion valve through the first compressor and the second heat exchanger in the freezing mode, and allows the first refrigerant to flow from the first compressor in the defrosting mode. Between the connection destination of the discharge port of the first compressor and the first compressor so that it flows in the first heat exchanger and flows in the opposite direction from the first expansion valve through the second heat exchanger and back to the first compressor. Replace the connection destination of the suction port. The refrigerant amount adjustment mechanism adjusts the circulation amount of the first refrigerant in the defrosting mode.

According to the refrigeration system of the present disclosure, the circulation amount of the first refrigerant can be adjusted during operation in the defrost mode, so the refrigerant pressure can be kept within an appropriate range during operation in the defrost mode. .

1 is a diagram showing the configuration of a refrigeration system according to Embodiment 1; FIG. 3 is a diagram showing the configuration of a control device 50 that controls a refrigeration system; FIG. 4 is a diagram showing the flow of refrigerant in the defrosting mode of the refrigeration system of Embodiment 1; FIG. 4 is a flow chart for explaining control executed by a control device in Embodiment 1. FIG. FIG. 6 is a diagram showing the configuration of a refrigeration system according to Embodiment 2; FIG. 10 is a diagram showing the flow of refrigerant in the defrosting mode of the refrigeration system of Embodiment 2; FIG. 10 is a diagram showing the configuration of a refrigeration system according to Embodiment 3; FIG. 10 is a diagram showing the configuration of a refrigeration system according to Embodiment 4;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. A plurality of embodiments will be described below, but appropriate combinations of the configurations described in the respective embodiments have been planned since the filing of the application. The same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

Embodiment 1.
FIG. 1 is a diagram showing the configuration of a refrigeration system according to Embodiment 1. FIG. Referring to FIG. 1 , refrigerating apparatus 100 includes an outdoor unit 101 , an indoor unit 102 , and pipes 27 and 31 connecting outdoor unit 101 and indoor unit 102 .

Indoor unit 102 includes a first expansion valve 3 and a first heat exchanger 4 . The first expansion valve 3 and the first heat exchanger 4 are connected in series. As the first expansion valve 3, for example, a temperature expansion valve controlled based on the temperature of the refrigerant outlet of the first heat exchanger 4 can be used.

The outdoor unit 101 includes a first compressor 1 , a second heat exchanger 2 , a four-way valve 7 , a refrigerant amount adjusting mechanism 10 and a controller 50 .

FIG. 2 is a diagram showing the configuration of a control device 50 that controls the refrigeration system. Referring to FIG. 2, control device 50 includes a processor 51, a memory 52, a communication interface (not shown), and the like. The processor 51 controls the operating frequency of the first compressor 1, the connection of the four-way valve 7, etc. according to the data stored in the memory 52 and the information obtained via the communication interface.

The memory 52 includes, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), and a flash memory. The flash memory stores an operating system, application programs, and various data. Control device 50 shown in FIG. 1 is implemented by processor 51 executing an operating system and application programs stored in memory 52 . Various data stored in the memory 52 are referenced when the application program is executed.

Referring to FIG. 1 again, first compressor 1 and second heat exchanger 2 are connected to indoor unit 102 so that the first refrigerant circulates.

Refrigeration apparatus 100 has a freezing mode and a defrosting mode as operation modes. In the freezing mode, the refrigerant flows in the direction indicated by the arrows in FIG. 3 is a diagram showing the flow of refrigerant in the defrosting mode of the refrigeration system of Embodiment 1. FIG.

The four-way valve 7 switches the connection destination of the discharge port of the first compressor 1 and the connection destination of the suction port of the first compressor 1 between the freezing mode and the defrosting mode. In the refrigerating mode shown in FIG. 1, the four-way valve 7 is arranged in the first compressor 1 so that the first refrigerant flows in the positive direction toward the first expansion valve 3 via the first compressor 1 and the second heat exchanger 2. to connect. In the defrosting mode shown in FIG. 3, the four-way valve 7 allows the first refrigerant to flow from the first compressor 1 to the first heat exchanger 4 and from the first expansion valve 3 to the second heat exchanger 2. The first compressor 1 is connected so as to flow in the opposite direction back to the first compressor 1 .

The refrigerant amount adjustment mechanism 10 is configured to adjust the circulation amount of the first refrigerant in the defrost mode.

The refrigerant amount adjustment mechanism 10 includes a liquid receiver 8 , refrigerant discharge pipes 34 and 35 and a flow rate adjustment valve 45 . A liquid receiver 8 is installed between the second heat exchanger 2 and the first expansion valve 3 . Refrigerant discharge pipes 34 and 35 connect between the outlet of the liquid receiver 8 and the suction port of the first compressor 1 . The flow rate adjustment valve 45 adjusts the flow rate of the first refrigerant flowing through the refrigerant discharge pipes 34 and 35 .

In the defrosting mode shown in FIG. 3, the outdoor unit 101 has bypass passages 36 and 37 that flow the first refrigerant from the first expansion valve 3 toward the second heat exchanger 2 without passing through the liquid receiver 8. Prepare more.

The outdoor unit 101 includes a second expansion valve 46 provided in the bypass passages 36 and 37 and a refrigerant flow direction provided in the bypass passage 37 from the second expansion valve 46 to the second heat exchanger 2. and an orientation-limiting check valve 43 .

When the four-way valve 7 is switched to the state shown in FIG. 3, the refrigerant circulates in the direction indicated by the arrows in FIG. 3 because of the check valves 41 to 43. FIG. When switching from the freezing mode to the defrosting mode, a sufficient amount of refrigerant is stored in the liquid receiver 8 of the refrigerant amount adjusting mechanism 10 . In the defrosting mode, opening the flow control valve 45 adds the amount of refrigerant to circulate. Therefore, in order to set the amount of refrigerant circulating in the defrosting mode to an appropriate amount, the flow control valve 45 should be closed when the amount of refrigerant reaches an appropriate amount. In addition, since the check valve 42 is provided between the pipe 25 and the pipe 26 after the refrigerant discharge pipe 34 branches, even if the flow control valve 45 is opened in the defrosting mode, The refrigerant does not flow back to the liquid receiver 8 side.

FIG. 4 is a flowchart for explaining control executed by a control device in Embodiment 1. FIG. The processing of this flow chart is repeatedly executed every time a certain period of time elapses or every time a predetermined condition is satisfied during the operation of the refrigeration system. For example, when defrosting is performed at regular time intervals, the control device 50 executes the process of the flowchart of FIG. 4 when a certain time has passed since the previous defrosting of the first heat exchanger 4 . It should be noted that the decision to switch to the defrost mode may be made based on the detection of the refrigerant temperature or the state of frost on the first heat exchanger 4 .

Referring to FIG. 4, control device 50 switches four-way valve 7 from the state shown in FIG. 1 to the state shown in FIG. 3 in step S1 when the condition for switching to the defrosting mode is established.

Then, in step S2, the control device 50 monitors the outputs of the temperature sensor 61 and the pressure sensor 62, and determines that the degree of subcooling (SC: subcooling) of the first refrigerant in the bypass flow path 36 before the second expansion valve 46 is It is judged whether or not it is lower than the judgment value.

If SC is lower than the judgment value (YES in S2), controller 50 opens flow control valve 45 to increase the amount of refrigerant to be circulated. On the other hand, when SC is equal to or greater than the judgment value (NO in S2), the control device 50 closes the flow control valve 45 because the amount of refrigerant to be circulated is sufficient.

The processes of steps S2 to S4 are repeated until it is determined in step S5 that the defrosting is completed. As a result, the amount of refrigerant circulating in the defrost mode is adjusted appropriately.

When it is determined that the defrosting is completed (YES in S5), in step S6, the control device 50 returns the four-way valve 7 to the freezing mode of FIG.

According to the refrigerating apparatus 100 shown in Embodiment 1, since the refrigerant circulation amount during defrosting can be properly maintained, it is possible to avoid a decrease in defrosting capability and an excessive increase in high pressure due to insufficient refrigerant. Therefore, the frost can be reliably melted in a short time, and the design pressure can be kept low.

Embodiment 2.
FIG. 5 is a diagram showing the configuration of a refrigeration system according to Embodiment 2. As shown in FIG. Referring to FIG. 5 , refrigerating apparatus 200 includes an outdoor unit 201 , an indoor unit 202 , and pipes 27 and 31 connecting outdoor unit 201 and indoor unit 202 .

The indoor unit 202 has the same configuration as the indoor unit 102 of the first embodiment.
The outdoor unit 201 has the structure of the outdoor unit 101 of Embodiment 1 as a low-temperature side first refrigerating cycle device 207, and further includes a third heat exchanger 214 and a high-temperature side second refrigerating cycle device 206. A control device 250 is provided instead of the device 50 . For example, the first refrigerant used in first refrigeration cycle device 207 is CO ₂ or the like, and the second refrigerant used in second refrigeration cycle device 206 is CO ₂ , propane, or the like. Other parts of the configuration of the outdoor unit 201 are the same as those of the outdoor unit 101 in FIG. 1, and therefore description thereof will not be repeated here. The configuration of control device 250 is also the same as that of control device 50 shown in FIG. 2, and therefore description thereof will not be repeated.

The second refrigerating cycle device 206 is configured such that the second refrigerant circulates through the second compressor 211, the fourth heat exchanger 212, the third expansion valve 213 and the third heat exchanger 214 in this order. The third heat exchanger 214 exchanges heat between the second refrigerant and the first refrigerant discharged from the second heat exchanger 2 and flowing into the liquid receiver 8 in the refrigerating mode. Since the refrigerant flowing into the liquid receiver 8 is cooled by the third heat exchanger 214, pressure rise in the liquid receiver 8 is suppressed.

First compressor 1 and second heat exchanger 2 are connected to indoor unit 202 so that the first refrigerant circulates.

Refrigeration apparatus 200 has a freezing mode and a defrosting mode as operation modes. In the freezing mode, the refrigerant flows in the directions indicated by the arrows in FIG. FIG. 6 is a diagram showing the flow of refrigerant in the defrosting mode of the refrigeration system of Embodiment 2. FIG.

The difference in the refrigerant circulation direction between the freezing mode and the defrosting mode in the second embodiment is basically the same as in the first embodiment described with reference to FIGS. 1 and 3 . Also, the control for adjusting the amount of refrigerant is common to the flowchart shown in FIG. Therefore, description of these will not be repeated.

In the case of a binary cycle including the second refrigeration cycle device 206 on the high temperature side and the first refrigeration cycle device 207 on the low temperature side, as shown in the second embodiment, the first refrigeration cycle device 207 on the low temperature side Design pressure is set low. Therefore, adjusting the refrigerant circulation amount in the defrosting mode with the refrigerant amount adjustment mechanism 10 is effective for suppressing the pressure of the first refrigeration cycle device 207 on the low temperature side, and when carbon dioxide gas or the like is applied as the second refrigerant effective for

Embodiment 3.
FIG. 7 is a diagram showing the configuration of a refrigeration system according to Embodiment 3. FIG. Referring to FIG. 7 , refrigerating apparatus 300 includes an outdoor unit 301 , an indoor unit 302 , and pipes 27 and 31 connecting outdoor unit 301 and indoor unit 302 .

The indoor unit 302 has the same configuration as the indoor unit 202 of the second embodiment.
Outdoor unit 301 further includes a fifth heat exchanger 310 in addition to the configuration of outdoor unit 201 of the second embodiment. The fifth heat exchanger 310 is configured to exchange heat between the first refrigerant discharged from the liquid receiver 8 and the first refrigerant flowing through the refrigerant discharge pipe 35 in the defrosting mode.

Other parts of the configuration of the outdoor unit 301 are the same as those of the outdoor unit 201 in FIG. 5, and therefore description thereof will not be repeated here.

The difference in the refrigerant circulation direction between the freezing mode and the defrosting mode in Embodiment 3 is basically the same as in Embodiment 1 described in FIGS. 1 and 3 and Embodiment 2 described in FIGS. are the same. Also, the control for adjusting the amount of refrigerant is common to the flowchart shown in FIG. Therefore, description of these will not be repeated.

In addition to the effects of the refrigerating device 200 according to the second embodiment, the refrigerating device 300 according to the third embodiment liquefies the refrigerant flowing into the flow control valve 45 by the fifth heat exchanger 310, so that the flow rate can be adjusted. It is possible to prevent the gas refrigerant from entering the valve 45 and flowing into the valve 45 to reduce the flow rate. As a result, the effect that the adjustment of the refrigerant amount in the defrosting mode is completed early is obtained.

Embodiment 4.
FIG. 8 is a diagram showing the configuration of a refrigeration system according to Embodiment 4. As shown in FIG. Referring to FIG. 8 , refrigerating apparatus 400 includes an outdoor unit 401 , an indoor unit 402 , and pipes 27 and 31 connecting outdoor unit 401 and indoor unit 402 .

The indoor unit 402 has the same configuration as the indoor unit 202 of the second embodiment.
In addition to the configuration of the outdoor unit 201 of Embodiment 2, the outdoor unit 401 connects between the first refrigerant inlet of the third heat exchanger 214 and the first refrigerant outlet of the liquid receiver 8, It further includes a circulation passage 410 for circulating the first refrigerant between the heat exchanger 214 and the liquid receiver 8 , and an electromagnetic valve 411 provided in the circulation passage 410 .

Thus, by providing the circulation flow path 410 and opening the solenoid valve 411 during the defrosting mode, the first refrigerant cooled and liquefied in the third heat exchanger moves to the liquid receiver 8 and Circulation of the first refrigerant occurs in which the warm refrigerant moves to the third heat exchanger and is cooled.

As a result, the temperature of the refrigerant in the liquid receiver 8 is kept low during the defrosting mode, so that when the defrosting mode returns to the freezing mode, the indoor unit 402 can quickly resume cooling at a low temperature.

The embodiments disclosed this time should be considered as examples and not restrictive in all respects. The scope of the present invention is indicated by the scope of the claims rather than the description of the above-described embodiments, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

1 first compressor, 2 second heat exchanger, 3 first expansion valve, 4 first heat exchanger, 7 four-way valve, 8 liquid receiver, 10 refrigerant amount adjustment mechanism, 25 to 27, 31 piping, 34, 35 refrigerant discharge pipe, 36, 37, 410 flow path, 41 to 43 check valve, 45 flow control valve, 46 second expansion valve, 50, 250 control device, 51 processor, 52 memory, 61 temperature sensor, 62 pressure sensor , 100,200,300,400 Refrigerating device 101,201,301,401 Outdoor unit 102,202,302,402 Indoor unit 206 Second refrigerating cycle device 207 First refrigerating cycle device 211 Second compressor , 212 fourth heat exchanger, 213 third expansion valve, 214 third heat exchanger, 310 fifth heat exchanger, 411 solenoid valve.

Claims (6)

An outdoor unit of a refrigeration system having a freezing mode and a defrosting mode,
a first compressor and a second heat exchanger connected so that the first refrigerant circulates between the indoor unit in which the first expansion valve and the first heat exchanger are connected in series;
In the freezing mode, the first refrigerant flows through the first compressor and the second heat exchanger in the positive direction toward the first expansion valve, and in the defrosting mode, the first refrigerant flows in the first direction. From the first compressor to the first heat exchanger, and from the first expansion valve through the second heat exchanger and back to the first compressor, the discharge port of the first compressor is flowed in the opposite direction. a four-way valve for exchanging the connection destination and the connection destination of the suction port of the first compressor;
A refrigerant amount adjustment mechanism that adjusts the circulation amount of the first refrigerant in the defrosting mode ,
The refrigerant amount adjustment mechanism is
a liquid receiver installed between the second heat exchanger and the first expansion valve;
a refrigerant discharge pipe connecting between the outlet of the liquid receiver and the suction port of the first compressor;
a flow rate adjustment valve that adjusts the flow rate of the first refrigerant flowing through the refrigerant discharge pipe,
The outdoor unit is
The outdoor unit further comprising a bypass flow path that allows the first refrigerant to flow from the first expansion valve toward the second heat exchanger without passing through the liquid receiver in the defrosting mode . a second expansion valve provided in the bypass flow path;
2. The outdoor unit according to claim 1 , further comprising a check valve that is provided in said bypass flow path and restricts a direction in which refrigerant flows from said second expansion valve toward said second heat exchanger. The first compressor, the second heat exchanger, the first expansion valve and the first heat exchanger constitute a first refrigeration cycle device using the first refrigerant,
a third heat exchanger that performs heat exchange between the first refrigerant and the second refrigerant discharged from the second heat exchanger and flowing into the liquid receiver in the freezing mode;
The outdoor unit according to claim 1 , further comprising a second refrigerating cycle device in which said second refrigerant circulates through a second compressor, a fourth heat exchanger, a third expansion valve and said third heat exchanger in this order. 4. The defrosting mode further comprises a fifth heat exchanger that exchanges heat between the first refrigerant discharged from the liquid receiver and the first refrigerant flowing through the refrigerant discharge pipe. The outdoor unit described in . connecting between an inlet of the first refrigerant of the third heat exchanger and an outlet of the first refrigerant of the liquid receiver, and connecting the first refrigerant between the third heat exchanger and the liquid receiver; a circulation channel for circulating the coolant;
4. The outdoor unit according to claim 3 , further comprising a solenoid valve provided in said circulation passage. The outdoor unit according to any one of claims 1 to 5 ;
A refrigeration system comprising the indoor unit.

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