WO2021084743A1

WO2021084743A1 - Refrigeration cycle device

Info

Publication number: WO2021084743A1
Application number: PCT/JP2019/043094
Authority: WO
Inventors: 智隆石川; 悠介有井; 素早坂
Original assignee: 三菱電機株式会社
Priority date: 2019-11-01
Filing date: 2019-11-01
Publication date: 2021-05-06
Also published as: CN117329723A; JP2024023437A; JPWO2021084743A1; EP4053470A4; EP4053470A1; CN114585866A

Abstract

In a refrigeration cycle device (100), a refrigerant circulates in the following order: a compressor (1), a first heat exchanger (2), a second heat exchanger (3), a first expansion valve (5), and a third heat exchanger (4). The refrigeration cycle device (100) comprises a receiver (8), a second expansion valve (6), a first flow path (FP1), a second flow path (FP2), a vent pipe (9), and a third expansion valve (7). The second expansion valve (6) is connected to a second port (P72). The first flow path (FP1) connects the second expansion valve (6) to the compressor (1) via the second heat exchanger (3). The second flow path (FP2) connects the first heat exchanger (2) to the second heat exchanger (3). The vent pipe (9) connects a third port (P73) to the portion of the first flow path (FP1) between the second expansion valve (6) and the second heat exchanger (3). The third expansion valve (7) is connected between the second flow path (FP2) and a first port (P71).

Description

Refrigeration cycle equipment

The present invention relates to a refrigeration cycle device including a receiver for storing a refrigerant.

Conventionally, a refrigeration cycle device including a receiver for storing a refrigerant is known. For example, Japanese Patent Application Laid-Open No. 2009-243793 (Patent Document 1) discloses a heat pump type hot water supply outdoor unit including a medium pressure receiver into which a refrigerant decompressed by an expansion valve flows in.

Japanese Unexamined Patent Publication No. 2009-243793

A refrigerant having a pressure (intermediate pressure) smaller than the pressure of the refrigerant discharged from the compressor and larger than the pressure of the refrigerant sucked into the compressor flows into the medium pressure receiver disclosed in Patent Document 1. In a refrigeration cycle device provided with a receiver in which an intermediate pressure refrigerant is stored in this way, when the operating load required for the refrigeration cycle device fluctuates, the pressure and temperature of the refrigerant discharged from the compressor sharply decrease. In some cases. A sharp drop in pressure and temperature of the refrigerant reduces the reliability of the refrigeration cycle device.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to improve the reliability of the refrigeration cycle apparatus.

In the refrigeration cycle apparatus according to the present invention, the refrigerant circulates in the order of the compressor, the first heat exchanger, the second heat exchanger, the first expansion valve, and the third heat exchanger. The refrigeration cycle device includes a receiver, a second expansion valve, a first flow path, a second flow path, a ventilation pipe, and a third expansion valve. The receiver has a first port, a second port, and a third port. The third port is located higher than the second port. The second expansion valve is connected to the second port. The first flow path connects the second expansion valve to the compressor via the second heat exchanger. The second flow path connects the first heat exchanger to the second heat exchanger. The vent pipe connects the third port to the portion of the first flow path between the second expansion valve and the second heat exchanger. The third expansion valve is connected between the second flow path and the first port.

According to the refrigeration cycle apparatus according to the present invention, the reliability of the refrigeration cycle apparatus can be improved by connecting the third expansion valve between the second flow path and the first port.

It is a functional block diagram which shows the structure of the refrigeration cycle apparatus which concerns on embodiment. It is a functional block diagram which shows the structure of the control device of FIG. It is a flowchart which shows the flow of the process performed by the control device of FIG.

Hereinafter, the embodiment will be described in detail with reference to the drawings. In principle, the same or corresponding parts in the drawings are designated by the same reference numerals and the description is not repeated.

FIG. 1 is a functional block diagram showing the configuration of the refrigeration cycle device 100 according to the embodiment. Examples of the refrigerating cycle device 100 include a refrigerator, an air conditioner, and a showcase.

As shown in FIG. 1, the refrigeration cycle apparatus 100 includes a compressor 1, a condenser 2 (first heat exchanger), a HIC (Heat Inter Changer) 3 (second heat exchanger), and an evaporator 4. (Third heat exchanger), expansion valve 5 (first expansion valve), expansion valve 6 (second expansion valve), expansion valve 7 (third expansion valve), receiver 8, vent pipe 9 and the like. , The control device 10, the temperature sensors Sa1 to Sa3, and the pressure sensors Sb1 and Sb2 are provided. Each of the expansion valves 5 to 7 includes, for example, an electronic LEV (Linear Expansion Valve). The vent tube 9 includes, for example, a capillary tube.

The compressor 1 includes a discharge port P11, a suction port P12, and an injection port P13. The compressor 1 is, for example, a high-pressure shell type compressor, and stores the lubricating oil of the compression mechanism inside the compressor 1. In the refrigeration cycle device 100, the refrigerant circulates in the order of the discharge port P11, the condenser 2, the HIC 3, the expansion valve 5, the evaporator 4, and the suction port P12.

The receiver 8 has a port P71 (first port), a port P72 (second port), and a port P73 (third port). Ports P71 and P73 are formed on the upper surface of the receiver. The port P72 is formed on the bottom surface of the receiver 8 facing the upper surface. The port P73 is located higher than the port P72. Ports P71 to P73 may be formed on the side surface of the receiver 8.

The expansion valve 6 is connected to the port P72. The expansion valve 6 is connected to the injection port P13 via the HIC 3 by the injection flow path FP1 (first flow path). The ventilation pipe 9 connects the port P73 to the portion of the injection flow path FP1 between the expansion valve 6 and the HIC3. The condenser 2 and the HIC 3 are connected by a flow path FP2 (second flow path). The expansion valve 7 is connected between the flow path FP2 and the port P71.

A part of the refrigerant flowing out of the condenser 2 is guided from the flow path FP2 to the expansion valve 7 before flowing into the HI C3, is depressurized by the expansion valve 7, and then flows into the receiver 8 from the port P71. The amount of refrigerant per unit time flowing into the receiver 8 from the port P71 is controlled by the opening degree of the expansion valve 7. The refrigerant flowing out of the receiver 8 is decompressed and then sucked into the compressor 1 from the injection port P13. Since the pressure of the refrigerant flowing into the receiver 8 is an intermediate pressure, a supercritical refrigerant such as carbon dioxide can also be stored as a liquid in the receiver 8. Since the supercritical refrigerant flowing out from the receiver 8 has a degree of supercooling, the performance of the refrigeration cycle device 100 can be improved by using the supercritical refrigerant.

Of the refrigerants flowing into the receiver 8 from the port P71, the liquid refrigerant (liquid refrigerant) is stored from the bottom of the receiver 8, and the gaseous refrigerant (gas refrigerant) is inside the receiver 8 above the liquid level of the liquid refrigerant. get together. A saturated liquid of the refrigerant flows out from the port P72. The saturated liquid is depressurized by the expansion valve 6. The gas refrigerant flowing out of the port P73 is guided to the injection flow path FP1 by the ventilation pipe 9.

The amount of refrigerant flowing out from the port P72 per unit time is controlled by the opening degree of the expansion valve 6. That is, the ratio of the amount of gas refrigerant to the amount of liquid refrigerant in the refrigerant flowing into HIC 3 is adjusted by the opening degree of the expansion valve 6. In the refrigerant sucked into the compressor 1 from the injection port P13, the larger the ratio of the gas refrigerant amount, the more the decrease in the temperature Td can be suppressed, and the larger the ratio of the liquid refrigerant amount, the more the decrease in the pressure Pd can be suppressed. it can. Therefore, by adjusting the ratio, it is possible to adjust the distribution of the effect of suppressing the decrease in pressure Pd and the effect of suppressing the decrease in temperature Td.

The refrigerant from the receiver 8 is guided to the injection port P13 via the HIC 3 by the injection flow path FP1. In the HIC 3, the refrigerant from the condenser 2 is cooled by the refrigerant from the receiver 8. In the refrigeration cycle device 100, the ratio (dryness) of the gas refrigerant to the refrigerant flowing into the receiver 8 can be increased to about 0.5 by guiding the refrigerant before being cooled by the HIC 3 to the receiver 8. As a result, it becomes easy to adjust the ratio of the amount of gas refrigerant to the amount of liquid refrigerant in the refrigerant flowing from the receiver 8 to the HI C3.

The control device 10 acquires the temperature Td and the pressure Pd of the refrigerant discharged from the compressor 1 from the temperature sensor Sa1 and the pressure sensor Sb1, respectively. The control device 10 acquires the temperature Ts and the pressure Ps of the refrigerant sucked into the compressor 1 from the temperature sensor Sa2 and the pressure sensor Sb2, respectively. The control device 10 acquires the temperature T1 of the refrigerant flowing out of the condenser 2 from the temperature sensor Sa3. The control device 10 controls the drive frequency of the compressor 1 to control the amount of refrigerant discharged by the compressor 1 per unit time. The control device 10 controls the opening degree of each of the expansion valves 5 to 7. In the normal operation of the refrigeration cycle device 100, the control device 10 controls the compressor 1 and the expansion valves 5 to 7 so that, for example, the temperature Td and the degree of supercooling of the refrigerant flowing out of the condenser 2 each become target values. .. For example, the target value of the temperature Td is 100 ° C., and the target value of the supercooling degree is 5K.

FIG. 2 is a functional block diagram showing the configuration of the control device 10 of FIG. As shown in FIG. 2, the control device 10 includes a processing circuit 11, a memory 12, and an input / output unit 13. The processing circuit 11 may be dedicated hardware or a CPU (Central Processing Unit) that executes a program stored in the memory 12. When the processing circuit 11 is dedicated hardware, the processing circuit 11 includes, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA ( Field Programmable Gate Array) or a combination of these is applicable. When the processing circuit 11 is a CPU, the function of the control device 10 is realized by software, firmware, or a combination of software and firmware. The software or firmware is described as a program and stored in the memory 12. The processing circuit 11 reads and executes the program stored in the memory 12. The memory 12 includes a non-volatile or volatile semiconductor memory (for example, RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), or EEPROM (Electrically Erasable Programmable Read Only Memory). )), And includes magnetic discs, flexible discs, optical discs, compact discs, mini discs, or DVDs (Digital Versatile Discs). The CPU is also called a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor).

FIG. 3 is a flowchart showing a flow of processing performed by the control device 10 of FIG. The process shown in FIG. 3 is called at regular time intervals by the main routine that performs the integrated process of the refrigeration cycle apparatus 100. In the following, the step is simply referred to as S.

As shown in FIG. 3, the control device 10 determines in S101 whether or not the pressure Pd is smaller than the reference pressure Pref. The reference pressure Pref is a lower limit value of the pressure Pd that can secure a desired compression ratio (Pd / Ps), and can be appropriately calculated by an actual machine experiment or a simulation.

When the pressure Pd is equal to or higher than the reference pressure Pref (NO in S101), the control device 10 controls the normal operation in S102 and returns the process to the main routine. When the pressure Pd is smaller than the reference pressure Pref (YES in S101), the control device 10 reduces the opening degree of the expansion valve 6 in S103 and advances the process to S104.

The control device 10 determines whether or not the superheat degree SH of the refrigerant discharged from the compressor 1 in S104 is larger than the reference value δ. The reference value δ is a value for determining whether or not the degree of superheat of the refrigerant is small enough to be regarded as 0K, and can be appropriately calculated by an actual machine experiment or a simulation.

When the superheat degree SH is larger than the reference value δ (YES in S104), the control device 10 increases the opening degree of the expansion valve 6 in S105 and returns the process to the main routine. When the superheat degree SH is equal to or less than the reference value δ (NO in S104), the control device 10 reduces the opening degree of the expansion valve 6 in S106 and returns the process to the main routine.

In the refrigeration cycle apparatus 100, it is possible to realize both suppression of a decrease in pressure Pd and suppression of a decrease in temperature Td. By suppressing the decrease in the pressure Pd, it is possible to prevent the pressure Pd from deviating from the allowable range of the compressor 1. By securing a desired compression ratio, the performance of the refrigeration cycle apparatus 100 can be stabilized. Further, by suppressing the decrease in temperature Td, the superheat degree SH of the refrigerant discharged from the compressor 1 can be maintained within a desired range. Since the liquid refrigerant is prevented from being sucked into the compressor 1 and the lubricating oil being diluted by the liquid refrigerant, wear of the compression mechanism of the compressor 1 can be prevented.

As described above, according to the refrigeration cycle device according to the embodiment, the reliability of the refrigeration cycle device can be improved.

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

1 Compressor, 2 Condenser, 3 HIC, 4 Evaporator, 5-7 Expansion valve, 8 Receiver, 9 Vent pipe, 10 Control device, 11 Processing circuit, 12 Memory, 13 Input / output section, 100 Refrigeration cycle device, FP1 , FP2 flow path, P11 discharge port, P12 suction port, P13 injection port, P71 to P73 ports, Sa1 to Sa3 temperature sensor, Sb1, Sb2 pressure sensor.

Claims

A refrigeration cycle device in which the refrigerant circulates in the order of a compressor, a first heat exchanger, a second heat exchanger, a first expansion valve, and a third heat exchanger.
A receiver having a first port, a second port, and a third port located higher than the second port, and
The second expansion valve connected to the second port and
A first flow path that connects the second expansion valve to the compressor via the second heat exchanger, and
A second flow path that connects the first heat exchanger to the second heat exchanger,
A vent pipe connecting the third port to the portion of the first flow path between the second expansion valve and the second heat exchanger.
A refrigeration cycle apparatus including a third expansion valve connected between the second flow path and the first port.
The opening degree of the third expansion valve when the pressure of the refrigerant discharged from the compressor is smaller than the reference pressure is smaller than the opening degree of the third expansion valve when the pressure is larger than the reference pressure. , The refrigeration cycle apparatus according to claim 1.
When the pressure is smaller than the reference pressure, the opening degree of the second expansion valve when the degree of superheat of the refrigerant discharged from the compressor is larger than the reference value is such that the degree of superheat is smaller than the reference value. The refrigeration cycle apparatus according to claim 2, which is larger than the opening degree of the second expansion valve at the time.
The first port and the third port are formed on the upper surface of the receiver.
The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the second port is formed on the bottom surface of the receiver facing the upper surface.
The compressor includes a discharge port, a suction port, and an injection port.
The refrigerant circulates in the order of the discharge port, the first heat exchanger, the second heat exchanger, the first expansion valve, the third heat exchanger, and the suction port.
The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein the first flow path connects the second expansion valve to the injection port via the second heat exchanger.