CN113348333B

CN113348333B - Outdoor unit of refrigeration device and refrigeration device provided with same

Info

Publication number: CN113348333B
Application number: CN201980090375.2A
Authority: CN
Inventors: 石川智隆; 石原宽也
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2019-02-05
Filing date: 2019-02-05
Publication date: 2023-07-11
Anticipated expiration: 2039-02-05
Also published as: EP3922928A4; EP3922928A1; WO2020161803A1; JPWO2020161803A1; CN113348333A; JP7105933B2

Abstract

A refrigeration device (100) is provided with an outdoor unit (101) and an indoor unit (102). The outdoor unit (101) is provided with a first compressor (1), a second heat exchanger (2), a four-way valve (7), and a refrigerant amount adjustment mechanism (10). In a cooling mode, the four-way valve (7) connects the first compressor (1) so that the first refrigerant flows in a forward direction toward the first expansion valve (3) via the first compressor (1) and the second heat exchanger (2). In the defrosting mode, the four-way valve (7) connects the first compressor (1) so that the first refrigerant flows in the opposite direction from the first compressor (1) to the first heat exchanger (4) and from the first expansion valve (3) back to the first compressor (1) via the second heat exchanger (2). The refrigerant quantity adjusting mechanism (10) is configured to adjust the circulation quantity of the first refrigerant in the defrosting mode.

Description

Outdoor unit of refrigeration device and refrigeration device provided with same

Technical Field

The present invention relates to an outdoor unit of a refrigeration apparatus and a refrigeration apparatus provided with the same.

Background

A defrosting mode for melting frost adhering to the cooler is provided in the refrigerating apparatus. As the defrosting method, for example, the following reverse hot gas defrosting method is known: the circulating direction of the refrigerant is changed by the four-way valve to send the high-temperature gas from the compressor to the cooler that normally functions as an evaporator.

Japanese patent No. 5595245 (patent document 1) discloses a refrigerating apparatus that performs defrosting by a reverse hot air defrosting method in a low-temperature side cycle of a binary cycle.

Prior art literature

Patent literature

Patent document 1: japanese patent No. 5595245

Disclosure of Invention

Problems to be solved by the invention

In the refrigeration apparatus disclosed in japanese patent No. 5595245 (patent document 1), the cascade condenser performing heat exchange between the refrigerant circulating on the high temperature side and the refrigerant circulating on the low temperature side is used for cooling, so that the rise in the high pressure during defrosting can be suppressed.

As a cascade condenser of the binary cycle, a plate type heat exchanger is generally used. The internal volume of the plate heat exchanger is small. Therefore, even if the refrigerant condensation at the time of defrosting is promoted by the cascade condenser, the pressure suppressing effect is limited. Therefore, if the defrosting operation of the fan is stopped and the frost adhering to the evaporator is melted, the refrigerant may not be sufficiently cooled, and the refrigerant pressure may rapidly rise to the design pressure, and the operation may be automatically stopped for protection. In the two-cycle, it is preferable to avoid an excessive rise in the refrigerant pressure during the defrosting operation, in addition to the design pressure being low in the normal refrigeration cycle apparatus.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a refrigeration apparatus capable of suppressing an increase in refrigerant pressure during defrosting operation.

Means for solving the problems

The present disclosure relates to an outdoor unit of a refrigeration apparatus having a cooling 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 to circulate the first refrigerant between the first compressor and the second heat exchanger and the indoor unit that connects the first expansion valve and the first heat exchanger in series. The four-way valve changes the connection destination of the discharge port of the first compressor and the connection destination of the suction port of the first compressor so that the first refrigerant flows in the forward direction toward the first expansion valve via the first compressor and the second heat exchanger in the cooling mode, and flows in the reverse direction from the first compressor to the first heat exchanger and from the first expansion valve back to the first compressor via the second heat exchanger in the defrosting mode. The refrigerant amount adjustment mechanism adjusts the circulation amount of the first refrigerant in the defrost mode.

Effects of the invention

According to the refrigeration apparatus of the present disclosure, the circulation amount of the first refrigerant can be adjusted in the operation in the defrost mode, and therefore, the refrigerant pressure can be kept in an appropriate range in the operation in the defrost mode.

Drawings

Fig. 1 is a diagram showing a structure of a refrigeration apparatus according to embodiment 1.

Fig. 2 is a diagram showing a configuration of a control device 50 that controls the refrigeration apparatus.

Fig. 3 is a diagram showing the flow of refrigerant in the defrosting mode of the refrigeration apparatus according to embodiment 1.

Fig. 4 is a flowchart for explaining control performed by the control device in embodiment 1.

Fig. 5 is a diagram showing a structure of a refrigeration apparatus according to embodiment 2.

Fig. 6 is a diagram showing the flow of refrigerant in the defrosting mode of the refrigeration apparatus according to embodiment 2.

Fig. 7 is a diagram showing a structure of a refrigeration apparatus according to embodiment 3.

Fig. 8 is a diagram showing a structure of a refrigeration apparatus according to embodiment 4.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following, a plurality of embodiments will be described, but it is initially contemplated from the application that the structures described in the embodiments are appropriately combined. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and the description thereof will not be repeated.

Embodiment 1

Fig. 1 is a diagram showing a structure of a refrigeration apparatus according to embodiment 1. Referring to fig. 1, a refrigeration apparatus 100 includes an outdoor unit 101, an indoor unit 102, and

pipes

27 and 31 connecting the outdoor unit 101 and the indoor unit 102.

The indoor unit 102 includes a first expansion valve 3 and a first heat exchanger 4. The first expansion valve 3 is connected in series with the first heat exchanger 4. 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 the first and second compressors 1 and 2, the four-way valve 7, the refrigerant amount adjusting mechanism 10, and the control device 50.

Fig. 2 is a diagram showing a configuration of a control device 50 that controls the refrigeration apparatus. Referring to fig. 2, the control device 50 includes a processor 51, a memory 52, a communication interface, not shown, and the like. The processor 51 controls the operation frequency of the first compressor 1, the connection of the four-way valve 7, and the like, based on the data stored in the memory 52 and the information obtained via the communication interface.

The Memory 52 is configured to include, for example, a ROM (Read Only Memory), a RAM (Random Access Memory: random access Memory), and a flash Memory. In addition, an operating system, application programs, and various data are stored in the flash memory. The control device 50 shown in fig. 1 is realized by the processor 51 executing an operating system and application programs stored in the memory 52. When executing an application program, various data stored in the memory 52 are referred to.

Referring again to fig. 1, the first compressor 1 and the second heat exchanger 2 are connected to circulate the first refrigerant between the first compressor 1 and the second heat exchanger 2 and the indoor unit 102.

The refrigeration apparatus 100 has a cooling mode and a defrost mode as the operation modes. In the cooling mode, the refrigerant flows in the direction indicated by the arrow in fig. 1. Fig. 3 is a diagram showing the flow of refrigerant in the defrosting mode of the refrigeration apparatus according to embodiment 1.

The four-way valve 7 switches between the cooling mode and the defrosting mode between a connection destination of the discharge port of the first compressor 1 and a connection destination of the suction port of the first compressor 1. In the cooling mode shown in fig. 1, the four-way valve 7 connects the first compressor 1 so that the first refrigerant flows in the forward direction toward the first expansion valve 3 via the first compressor 1 and the second heat exchanger 2. In the defrosting mode shown in fig. 3, the four-way valve 7 connects the first compressor 1 such that the first refrigerant flows in the opposite direction from the first compressor 1 to the first heat exchanger 4 and returns from the first expansion valve 3 to the first compressor 1 via the second heat exchanger 2.

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

The refrigerant quantity adjusting mechanism 10 includes the accumulator 8, the

refrigerant discharge pipes

34, 35, and the flow rate adjusting valve 45. A reservoir 8 is provided between the second heat exchanger 2 and the first expansion valve 3. The

refrigerant discharge pipes

34 and 35 connect the outlet of the accumulator 8 with 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.

The outdoor unit 101 further includes

bypass passages

36 and 37, and the

bypass passages

36 and 37 allow the first refrigerant to flow from the first expansion valve 3 to the second heat exchanger 2 without passing through the accumulator 8 in the defrosting mode shown in fig. 3.

The outdoor unit 101 further includes a second expansion valve 46 and a check valve 43, the second expansion valve 46 being provided in the

bypass flow paths

36 and 37, the check valve 43 being provided in the bypass flow path 37 to restrict the refrigerant flowing direction from the second expansion valve 46 to the direction of the second heat exchanger 2.

When the four-way valve 7 is switched to the state shown in fig. 3, the check valves 41 to 43 are present, and therefore, the refrigerant circulates in the direction shown by the arrow in fig. 3. When switching from the cooling mode to the defrosting mode, a sufficient amount of refrigerant is stored in the accumulator 8 of the refrigerant amount adjustment mechanism 10. In the defrosting mode, when the flow rate adjustment valve 45 is opened, the circulating refrigerant amount is added. Therefore, in order to set the amount of refrigerant circulating in the defrost mode to an appropriate amount, the flow rate adjustment valve 45 may be closed at a time when the amount of refrigerant reaches the appropriate amount. Further, since the check valve 42 is provided between the pipe 25 and the pipe 26 from which the refrigerant discharge pipe 34 branches, the refrigerant from the first expansion valve 3 does not flow back to the accumulator 8 side even if the flow rate adjustment valve 45 is opened in the defrosting mode.

Fig. 4 is a flowchart for explaining control performed by the control device in embodiment 1. The processing in this flowchart is repeatedly executed every time a predetermined time elapses or every time a preset condition is satisfied during the operation of the refrigeration apparatus. For example, when defrosting is performed at regular intervals, the control device 50 executes the processing of the flowchart of fig. 4 when a regular time has elapsed since the previous defrosting of the first heat exchanger 4. Further, the determination to switch to the defrosting mode may be made based on the detection of the refrigerant temperature or the adhesion state of frost on the first heat exchanger 4.

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

Then, in step S2, the control device 50 monitors the outputs of the temperature sensor 61 and the pressure sensor 62, and determines whether or not the degree of Supercooling (SC) of the first refrigerant in the bypass flow path 36 immediately before the second expansion valve 46 is lower than a determination value.

When SC is lower than the determination value (yes in S2), the control device 50 opens the flow rate adjustment valve 45 to add the circulating refrigerant amount. On the other hand, when SC is equal to or greater than the determination value (no in S2), the control device 50 closes the flow rate adjustment valve 45 because the amount of circulating refrigerant is sufficient.

The processing of steps S2 to S4 is repeated until it is determined in step S5 that defrosting is completed. Thereby, the amount of refrigerant circulating in the defrost mode is adjusted to be appropriate.

When it is determined that defrosting is completed (yes in S5), in step S6, control device 50 returns four-way valve 7 to the state of the cooling mode of fig. 1.

According to the refrigeration apparatus 100 of embodiment 1, the refrigerant circulation amount during defrosting can be appropriately maintained, and therefore, a decrease in defrosting capacity and an excessive increase in high pressure due to a shortage of refrigerant can be avoided. Therefore, the frost can be reliably melted in a short time, and the design pressure can be suppressed low.

Embodiment 2

Fig. 5 is a diagram showing a structure of a refrigeration apparatus according to embodiment 2. Referring to fig. 5, the refrigeration apparatus 200 includes an outdoor unit 201, an indoor unit 202, and

pipes

27 and 31 connecting the outdoor unit 201 and the indoor unit 202.

The indoor unit 202 has the same structure as the indoor unit 102 of embodiment 1.

The outdoor unit 201 includes the configuration of the outdoor unit 101 of embodiment 1 as the first refrigeration cycle device 207 on the low temperature side, the third heat exchanger 214, the second refrigeration cycle device 206 on the high temperature side, and the control device 250 instead of the control device 50. For example, used in the first refrigeration cycle device 207The first refrigerant being CO ₂ Etc., the second refrigerant used in the second refrigeration cycle device 206 is CO ₂ Propane, etc. The configuration of the other portions of the outdoor unit 201 is common to that of the outdoor unit 101 of fig. 1, and thus, a description thereof will not be repeated here. The configuration of the control device 250 is also the same as that of the control device 50 shown in fig. 2, and therefore, the description is not repeated.

The second refrigeration cycle device 206 is configured such that the second refrigerant circulates in the order of the second compressor 211, the fourth heat exchanger 212, the third expansion valve 213, and the third heat exchanger 214. The third heat exchanger 214 performs heat exchange between the second refrigerant and the first refrigerant discharged from the second heat exchanger 2 and flowing into the accumulator 8 in the cooling mode. Since the refrigerant flowing into the accumulator 8 is cooled by the third heat exchanger 214, the pressure rise in the accumulator 8 is suppressed.

The first compressor 1 and the second heat exchanger 2 are connected to circulate the first refrigerant between the first compressor 1 and the second heat exchanger 2 and the indoor unit 202.

The refrigeration apparatus 200 has a cooling mode and a defrost mode as the operation modes. In the cooling mode, the refrigerant flows in the direction indicated by the arrow in fig. 5. Fig. 6 is a diagram showing the flow of refrigerant in the defrosting mode of the refrigeration apparatus according to embodiment 2.

The difference in the circulation direction of the refrigerant in the cooling mode and the defrosting mode in embodiment 2 is substantially the same as that in embodiment 1 described in fig. 1 and 3. The control for adjusting the amount of the refrigerant is also common to the flowchart shown in fig. 4. Therefore, the description is not repeated.

In the case of the 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 embodiment 2, the design pressure of the first refrigeration cycle device 207 on the low temperature side is set low. Therefore, the adjustment of the refrigerant circulation amount in the defrosting mode by 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 is effective for the case where carbon dioxide or the like is used as the second refrigerant.

Embodiment 3

Fig. 7 is a diagram showing a structure of a refrigeration apparatus according to embodiment 3. Referring to fig. 7, the refrigeration apparatus 300 includes an outdoor unit 301, an indoor unit 302, and

pipes

27 and 31 connecting the outdoor unit 301 and the indoor unit 302.

The indoor unit 302 has the same structure as the indoor unit 202 of embodiment 2.

The outdoor unit 301 includes a fifth heat exchanger 310 in addition to the structure of the outdoor unit 201 of embodiment 2. The fifth heat exchanger 310 is configured to exchange heat between the first refrigerant discharged from the accumulator 8 and the first refrigerant flowing through the refrigerant discharge pipe 35 in the defrosting mode.

The configuration of the other portions of the outdoor unit 301 is common to that of the outdoor unit 201 of fig. 5, and thus, a description thereof will not be repeated here.

The difference in the circulation direction of the refrigerant in the cooling mode and the defrosting mode in embodiment 3 is substantially the same as that in embodiment 1 described in fig. 1 and 3 and embodiment 2 described in fig. 5 and 6. The control for adjusting the amount of the refrigerant is also common to the flowchart shown in fig. 4. Therefore, the description is not repeated.

In addition to the effect exerted by the refrigeration apparatus 200 according to embodiment 2, the refrigeration apparatus 300 according to embodiment 3 can prevent the flow rate from being reduced by the flow rate adjustment valve 45 by preventing the gas refrigerant from being mixed in, because the refrigerant flowing into the flow rate adjustment valve 45 is liquefied by the fifth heat exchanger 310. This can further achieve the effect of completing the adjustment of the amount of refrigerant in the defrosting mode in advance.

Embodiment 4

Fig. 8 is a diagram showing a structure of a refrigeration apparatus according to embodiment 4. Referring to fig. 8, a refrigeration apparatus 400 includes an outdoor unit 401, an indoor unit 402, and

pipes

27 and 31 connecting the outdoor unit 401 and the indoor unit 402.

The indoor unit 402 has the same structure as the indoor unit 202 of embodiment 2.

The outdoor unit 401 includes, in addition to the configuration of the outdoor unit 201 of embodiment 2, a circulation flow path 410 and an electromagnetic valve 411, the circulation flow path 410 connecting between the inlet of the first refrigerant in the third heat exchanger 214 and the first refrigerant outlet of the accumulator 8, and circulating the first refrigerant between the third heat exchanger 214 and the accumulator 8, and the electromagnetic valve 411 being provided in the circulation flow path 410.

Thus, the circulation flow path 410 is provided, and the solenoid valve 411 is opened in the defrost mode, thereby generating circulation of the first refrigerant as follows: the first refrigerant cooled and liquefied in the third heat exchanger moves to the accumulator 8, and the warm refrigerant in the accumulator 8 moves to the third heat exchanger and is cooled.

In this way, since the temperature of the refrigerant in the accumulator 8 is maintained low in the defrost mode, cooling at a low temperature in the indoor unit 402 can be quickly restarted when the mode is returned from the defrost mode to the cooling mode.

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

Description of the reference numerals

1 a first compressor; 2 a second heat exchanger; 3 a first expansion valve; 4 a first heat exchanger; 7 a four-way valve; 8 a reservoir; 10 refrigerant quantity adjusting mechanism; 25 to 27, 31 pipes; 34. 35 a refrigerant discharge pipe; 36. 37, 410 flow paths; 41-43 check valves; a 45 flow rate regulating valve; 46 a second expansion valve; 50. 250 control means; a 51 processor; 52 a memory; a 61 temperature sensor; 62 pressure sensors; 100. 200, 300, 400 refrigeration units; 101. 201, 301, 401 outdoor units; 102. 202, 302, 402 indoor units; 206 a second refrigeration cycle device; 207 a first refrigeration cycle device; 211 a second compressor; 212 a fourth heat exchanger; 213 a third expansion valve; 214 a third heat exchanger; 310 a fifth heat exchanger; 411 solenoid valve.

Claims

1. An outdoor unit which is an outdoor unit of a refrigeration apparatus having a cooling mode and a defrosting mode, and is connected to an indoor unit by a pipe, the outdoor unit comprising:

a first compressor and a second heat exchanger connected to circulate a first refrigerant between the first compressor and the second heat exchanger and the indoor unit having a first expansion valve and a first heat exchanger connected in series;

a four-way valve that changes a connection destination of a discharge port of the first compressor and a connection destination of a suction port of the first compressor so that, in the cooling mode, the first refrigerant flows in a forward direction toward the first expansion valve via the first compressor and the second heat exchanger, and, in the defrosting mode, the first refrigerant flows in a reverse direction from the first compressor to the first heat exchanger and from the first expansion valve back to the first compressor via the second heat exchanger; and

a refrigerant amount adjusting mechanism that adjusts a circulation amount of the first refrigerant in the defrosting mode,

the refrigerant amount adjusting mechanism includes:

a reservoir disposed between the second heat exchanger and the first expansion valve;

a refrigerant discharge pipe connecting between an outlet of the accumulator and a suction port of the first compressor; and

a flow rate adjustment valve for adjusting a flow rate of the first refrigerant flowing through the refrigerant discharge pipe,

the outdoor unit further includes:

a bypass flow path that flows the first refrigerant from the first expansion valve toward the second heat exchanger without passing through the accumulator in the defrosting mode;

a second expansion valve provided in the bypass flow path;

a first check valve provided in the bypass flow path and restricting a refrigerant flow direction to a direction from the second expansion valve toward the second heat exchanger; and

a second check valve provided between an outlet of the accumulator and a branching point at which the bypass flow path branches, the second check valve restricting a refrigerant flowing direction to the bypass flow path so that the refrigerant does not flow into the outlet of the accumulator,

the first compressor, the second heat exchanger, the first expansion valve, and the first heat exchanger constitute a first refrigeration cycle apparatus using the first refrigerant,

the outdoor unit further includes:

a third heat exchanger that performs heat exchange between the first refrigerant discharged from the second heat exchanger and flowing into the accumulator in the cooling mode;

a second refrigeration cycle device that circulates the second refrigerant in the order of a second compressor, a fourth heat exchanger, a third expansion valve, and the third heat exchanger;

a circulation flow path that connects an inlet of the first refrigerant of the third heat exchanger and an outlet of the first refrigerant of the accumulator, and circulates the first refrigerant between the third heat exchanger and the accumulator; and

and a solenoid valve provided in the circulation flow path.

2. The outdoor unit of claim 1, wherein,

the outdoor unit further includes a fifth heat exchanger that exchanges heat between the first refrigerant discharged from the accumulator and the first refrigerant flowing through the refrigerant discharge pipe in the defrost mode.

3. A refrigerating device is provided with:

the outdoor unit of claim 1 or 2; and

the indoor unit.