WO2024009351A1

WO2024009351A1 - Refrigeration cycle device

Info

Publication number: WO2024009351A1
Application number: PCT/JP2022/026588
Authority: WO
Inventors: 健太村田; 謙作畑中
Original assignee: 三菱電機株式会社
Priority date: 2022-07-04
Filing date: 2022-07-04
Publication date: 2024-01-11

Abstract

This refrigeration cycle device (1) comprises a refrigerant circuit (C1) and an injection flow path (F1). The refrigerant circuit (C1) is configured so that a refrigerant circulates in order through a discharge port (PD) of a compressor (10), a condenser (20), a first expansion valve (LEV1), a receiver (30), a second expansion valve (LEV2), an evaporator (40), and a suction port (PS) of the compressor (10). The injection flow path (F1) is configured so as to feed, via a third expansion valve (LEV3), the refrigerant depressurized by the first expansion valve (LEV1) to an injection port (PM). The refrigeration cycle device (1) further comprises a control device (100) that is configured to control the second expansion valve (LEV2) so that the dryness of the refrigerant at the suction port (PS) is less than one.

Description

Refrigeration cycle equipment

The present disclosure relates to a refrigeration cycle device.

When operating a refrigeration cycle device under high compression ratio conditions, the discharge temperature in a single-stage cycle, which is a normal refrigeration cycle, is over 100°C. Refrigerant injection may reduce the discharge temperature. Japanese Unexamined Patent Publication No. 2014-167381 (Patent Document 1) discloses an example of an air conditioner that performs such injection.

Japanese Patent Application Publication No. 2014-167381

When injecting refrigerant into a compressor in a refrigeration cycle device, if the injection flow rate increases too much, compressor efficiency will deteriorate and power consumption will increase. Therefore, the problem is how to determine the injection flow rate of the refrigeration cycle device.

Therefore, an object of the present disclosure is to provide a refrigeration cycle device that can suppress an increase in discharge temperature and suppress a decrease in compressor efficiency.

The present disclosure relates to a refrigeration cycle device. The refrigeration cycle device includes a refrigerant circuit and an injection flow path. The refrigerant circuit includes a compressor having a suction port and a discharge port, a condenser, a first expansion valve, a receiver, a second expansion valve, and an evaporator. The refrigerant circuit is configured such that refrigerant circulates in the order of the discharge port of the compressor, the condenser, the first expansion valve, the receiver, the second expansion valve, the evaporator, and the suction port of the compressor. The compressor further has an injection port. The injection flow path includes a third expansion valve, and is configured to send the refrigerant whose pressure has been reduced by the first expansion valve to the injection port via the third expansion valve. The refrigeration cycle device further includes a control device configured to control the second expansion valve so that the dryness of the refrigerant at the suction port is less than 1.

According to the refrigeration cycle device of the present disclosure, it is possible to suppress a decrease in compressor efficiency while suppressing an increase in discharge temperature.

1 is a diagram showing the configuration of a refrigeration cycle device 1 according to a first embodiment. 2 is a schematic diagram showing a cross section of a scroll portion of the compressor 10. FIG. FIG. 2 is a schematic diagram showing a vertical cross section of a scroll portion of the compressor 10. FIG. FIG. 2 is a PV diagram showing a variation in the amount of work of the compressor depending on the amount of intermediate pressure refrigerant injected. 7 is a flowchart for explaining control of the first expansion valve LEV1 in the first embodiment. 7 is a flowchart for explaining control of the second expansion valve LEV2 in the first embodiment. 7 is a flowchart for explaining control of the third expansion valve LEV3 in the first embodiment. It is a figure showing the composition of refrigeration cycle device 201 of Embodiment 2. 2 is a ph diagram of the refrigeration cycle device 201. FIG. 5 is a diagram showing the temperature distribution inside the heat exchanger 50. FIG. 7 is a flowchart for explaining control of the first expansion valve LEV1 in Embodiment 2. FIG. 7 is a flowchart for explaining control of the second expansion valve LEV2 in Embodiment 2. FIG. 7 is a flowchart for explaining control of the third expansion valve LEV3 in the second embodiment. It is a figure showing the composition of refrigeration cycle device 211 of Embodiment 3. 3 is a ph diagram of the refrigeration cycle device 211. FIG.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, the same reference numerals are given to the same or corresponding parts in the drawings, and the description thereof will not be repeated in principle.

Embodiment 1.
FIG. 1 is a diagram showing the configuration of a refrigeration cycle device 1 according to the first embodiment. The refrigeration cycle device 1 includes a refrigerant circuit C1 and an injection flow path F1. The refrigeration cycle device 1 is used, for example, in an air conditioner.

The refrigerant circuit C1 includes a compressor 10, a condenser 20, a first expansion valve LEV1, a receiver 30, a second expansion valve LEV2, and an evaporator 40. The refrigerant circuit C1 is configured such that refrigerant circulates in the order of the discharge port PD of the compressor 10, the condenser 20, the first expansion valve LEV1, the receiver 30, the second expansion valve LEV2, the evaporator 40, and the suction port PS of the compressor 10. It is composed of The receiver 30 is an example of a liquid receiver that stores refrigerant.

In addition to the suction port PS and the discharge port PD, the compressor 10 further includes an injection port PM. The injection flow path F1 includes a third expansion valve LEV3, and is configured to send the refrigerant depressurized by the first expansion valve LEV1 to the injection port PM via the third expansion valve LEV3. The third expansion valve LEV3 may be a flow rate adjustment valve or the like as long as the opening degree can be changed.

The refrigeration cycle device 1 further includes a control device 100. The control device 100 includes a CPU (Central Processing Unit) 101, a memory 102 (ROM (Read Only Memory) and RAM (Random Access Memory)), an input/output buffer (not shown), and the like. The CPU 101 expands a program stored in the ROM into a RAM or the like and executes the program. The program stored in the ROM is a program in which the processing procedure of the control device 100 is written. Control device 100 executes control of each element in refrigeration cycle device 1 according to these programs. This control is not limited to processing by software, but can also be performed by dedicated hardware (electronic circuit).

The compressor 10 is controlled by an inverter and its operating frequency can be changed. The control device 100 controls the operating frequency of the compressor 10 so that the compressor 10 is controlled in units so that the indoor temperature obtained by a temperature sensor (not shown) becomes a desired temperature (for example, the temperature set by the user). Controls the amount of refrigerant discharged per hour.

The control device 100 is configured to control the amount of air per unit time of the fan 22 that blows air to the condenser 20 and the fan 42 that blows air to the evaporator 40.

The control device 100 detects the degree of subcooling SC of the refrigerant at the outlet of the condenser 20 based on the outputs of a temperature sensor, a pressure sensor, etc. (not shown). The control device 100 controls the opening degree of the first expansion valve LEV1 so that the degree of subcooling SC of the refrigerant at the outlet of the condenser 20 approaches a target value.

By opening the third expansion valve LEV3, the control device 100 injects the low-temperature refrigerant stored in the receiver 30 into the compressor 10, thereby cooling the compressor 10. Thereby, the discharge temperature Td of the compressor 10 can be lowered. The control device 100 acquires the discharge temperature Td of the refrigerant discharged from the compressor 10 from a discharge temperature sensor (not shown).

The control device 100 detects the degree of superheating SH of the refrigerant discharged from the compressor 10 based on the outputs of a temperature sensor, a pressure sensor, etc. (not shown). The control device 100 is configured to control the opening degree of the third expansion valve LEV3 so that the degree of superheating SH of the refrigerant discharged from the compressor 10 approaches a target value.

When the injection is activated in the refrigerant circuit C1, the discharge temperature Td is determined by the injection flow rate, so the following control method is adopted as the control method for the second expansion valve LEV2.

The refrigeration cycle device 1 further includes a capacitive sensor 111 that detects the dryness of the refrigerant in the suction port PS. The control device 100 is configured to control the second expansion valve LEV2 so that the degree of dryness of the refrigerant in the suction port PS is less than 1.

The capacitive sensor 111 is configured to sense the degree of dryness (void ratio of the refrigerant). The sensor 111 is a dryness sensor that uses the fact that the capacitance changes when the dielectric constant between the electrodes of a flat capacitor filled with refrigerant changes with the content of air bubbles in the refrigerant (void ratio). It is a sensor. The control device 100 controls the opening degree of the second expansion valve LEV2 so that the degree of dryness of the refrigerant detected by the sensor 111 becomes a predetermined value of 1 or less. The control device 100 is configured to control the second expansion valve LEV2 so that the output of the sensor 111 approaches the target value.

Here, the compressor 10 is configured so that intermediate pressure refrigerant is injected during compression. In other words, it is not a two-stage compressor with two stages of compression sections. The structure of the compressor 10 will be explained below. Compressor 10 is a scroll compressor.

FIG. 2 is a schematic diagram showing a cross section of the scroll portion of the compressor 10. FIG. 3 is a schematic diagram showing a longitudinal section of the scroll portion of the compressor 10.

The scroll roll section includes a fixed scroll 12 fixed to the lid 15 of the compressor 10, and an orbiting scroll 11 fixed to a pedestal 14 that is arranged so as to partially contact the fixed scroll 12 and rotates by a motor or the like.

As the orbiting scroll 11 rotates, gas refrigerant is taken in from the outer periphery and sent toward the center. As shown in FIG. 2, the step area of the crescent-shaped gap formed between the fixed scroll 12 and the orbiting scroll 11 becomes smaller as it goes toward the center, and the refrigerant gas is gradually compressed, and the compressed gas is discharged from the discharge port PD. The refrigerant gas is discharged.

The compressor 10 is provided with an injection port PM. A check valve 18 is arranged at the injection port PM. Refrigerant is injected from the injection port PM into the crescent-shaped gap during compression. When the refrigerant pressure inside the receiver 30 is higher than the pressure in the crescent-shaped gap during compression, the refrigerant passes through the check valve 18 and flows into the compressor 10 .

FIG. 4 is a PV diagram showing variations in the amount of work of the compressor depending on the amount of intermediate pressure refrigerant injected. Waveform W1 shows a case where the amount of injected refrigerant is large, and waveform W2 shows a case where the amount of injected refrigerant is less by ΔINJ. Since the area surrounded by the waveform W2 on the PV diagram is smaller, it can be said that the waveform W2 is energy saving.

Here, we will consider how the amount of refrigerant to be injected is determined. In a general refrigeration cycle device without an injection flow path, the first expansion valve LEV1 controls the degree of subcooling SC of the refrigerant at the outlet of the condenser to a target value, and the second expansion valve LEV2 controls the subcooling degree SC of the refrigerant at the outlet of the condenser to a target value. The discharge temperature Td of No. 10 is controlled to be the target value.

However, in the refrigeration cycle device provided with the injection flow path F1, the third expansion valve LEV3 is controlled so that the discharge temperature Td of the compressor 10 is set to the target value. For this reason, if the second expansion valve LEV2 is also controlled to bring the discharge temperature Td to the target value, the control will conflict and will not work. For this reason, it is conceivable to control the second expansion valve LEV2 so that the degree of superheating SH of the refrigerant sucked into the compressor 10 is set to the target value.

Here, when the second expansion valve LEV2 controls the superheat degree SH of the suction refrigerant of the compressor 10 to the target value, in order to ensure the superheat degree SH of 0 or more (approximately 3 to 5 K in an actual unit). , the opening degree of the second expansion valve LEV2 is controlled to be smaller. If the heating capacity is not changed at this time, the injection flow rate will increase in order to keep the same amount of refrigerant flowing into the condenser. Here, when the injection method is port injection and the injection flow rate increases, compressor efficiency deteriorates due to the following factors.

In the case of ideal two-stage compression, the refrigerant, which has reached an intermediate pressure in the first stage compression, joins the injection refrigerant and is then compressed in the second stage compressor. In contrast, in the compressor 10 shown in FIGS. 2 and 3, the refrigerant injected from the injection port PM and the refrigerant in the compression chamber mix, and the pressure in the compression chamber increases, resulting in two-stage compression. By comparison, the compression power corresponding to the first stage increases. In other words, compressor efficiency deteriorates.

The larger the flow rate of the injection refrigerant, the larger the increase in pressure within the compression chamber, and therefore the larger the amount of increase in the compression power described above. For this reason, the larger the flow rate of the injection refrigerant, the greater the deterioration of the compressor efficiency, as explained in FIG. 4.

In other words, when trying to produce the same capacity, the capacity is determined by the flow rate of refrigerant passing through the condenser, so if the amount of refrigerant is throttled with the second expansion valve LEV2, the lack of capacity must be made up from the third expansion valve LEV3. No. In that case, as shown by the waveform W1 in FIG. 4, the input to the compressor 10 increases, and energy saving is no longer achieved.

Furthermore, in the case of a configuration in which injection is performed from the injection port PM, a check valve 18 is installed within the compressor to prevent backflow when the pressure inside the compression chamber exceeds the injection pressure. The volume between the check valve 18 and the injection port PM becomes a dead volume in which refrigerant that is not discharged is compressed. If the diameter of the flow path in which the check valve 18 is provided is increased in order to increase the injection flow rate, the dead volume will increase, so the loss of compressing the dead volume will increase.

As described above, the problem with compressors that inject refrigerant through the injection port is that compressor efficiency deteriorates and power consumption increases due to an increase in the injection flow rate.

For the above reasons, during injection operation, power consumption is reduced by reducing the dryness of the refrigerant sucked in to increase the amount of refrigerant sucked into the compressor.

The control device 100 shown in FIG. 1 controls the opening degree of the first expansion valve LEV1 so that the degree of subcooling SC of the refrigerant at the outlet of the condenser 20 approaches the target degree of supercooling SC*, and the The opening degree of the third expansion valve LEV3 is controlled so that the degree of superheat SH2 of the refrigerant to be heated approaches the target degree of superheat SH2*.

The control of the first to third expansion valves executed in the refrigeration cycle device 1 of the first embodiment will be explained below.

FIG. 5 is a flowchart for explaining control of the first expansion valve LEV1 in the first embodiment. First, in step S11, the control device 100 detects the degree of subcooling SC of the refrigerant at the outlet of the condenser 20. The degree of supercooling SC can be detected by various known methods. For example, the saturation temperature corresponding to the high pressure detected by the pressure sensor provided between the discharge side of the compressor 10 and the first expansion valve LEV1 and the detection temperature of the temperature sensor that detects the temperature of the refrigerant at the outlet of the condenser 20. The degree of supercooling SC may be determined by the difference between the two. Note that the saturation temperature may be detected by a temperature sensor provided in the two-phase region of the condenser 20.

Subsequently, in step S12, the current degree of supercooling SC and the target degree of supercooling SC* are compared. If SC>SC* holds true (YES in S12), the control device 100 increases the opening degree of the first expansion valve LEV1 by a certain degree in step S13. On the other hand, if SC>SC* does not hold (NO in S12), the control device 100 decreases the opening degree of the first expansion valve LEV1 by a certain degree in step S14.

By repeating the above process, the degree of supercooling SC at the outlet of the condenser 20 is maintained near the target value SC*.

FIG. 6 is a flowchart for explaining control of the second expansion valve LEV2 in the first embodiment. First, in step S21, the control device 100 detects the degree of dryness D of the refrigerant sucked into the compressor 10. For example, the capacitive sensor 111 shown in FIG. 1 can detect the degree of dryness D by capturing a change in the void ratio of the refrigerant as a change in capacitance.

Subsequently, in step S22, the current degree of dryness D and the target degree of dryness D* are compared. The target dryness is set to a value that does not damage the compressor 10 due to liquid compression, that is, a value slightly smaller than 1. Thereby, an increase in the injection flow rate can be suppressed.

If D>D* holds true (YES in S22), the control device 100 decreases the opening degree of the second expansion valve LEV2 by a certain degree in step S23. On the other hand, if D>D* does not hold (NO in S22), the control device 100 increases the opening degree of the second expansion valve LEV2 by a certain degree in step S24.

By repeating the above process, the dryness D of the refrigerant sucked into the compressor 10 is maintained near the target value D*.

FIG. 7 is a flowchart for explaining control of the third expansion valve LEV3 in the first embodiment. First, in step S31, the control device 100 detects the degree of superheat SH2 of the refrigerant discharged from the compressor 10. For example, the degree of superheating SH2 is calculated from the difference between the saturation temperature corresponding to the high pressure detected by a pressure sensor provided on the discharge side of the compressor 10 and the temperature detected by a temperature sensor that detects the temperature of the refrigerant discharged from the compressor 10. It's okay. Further, the saturation temperature may be detected by a temperature sensor provided in the two-phase region of the condenser 20.

Subsequently, in step S32, the current degree of superheat SH2 and the target degree of superheat SH2* are compared. If SH2>SH2* holds true (YES in S32), the control device 100 increases the opening degree of the third expansion valve LEV3 by a constant opening degree in step S33. On the other hand, if SH2>SH2* does not hold (NO in S32), the control device 100 decreases the opening degree of the third expansion valve LEV3 by a certain degree in step S34.

By repeating the above process, the degree of superheating SH2 is maintained near the target value SH2* of the degree of superheating.

In this embodiment, as shown in FIG. 6, the injection flow rate can be reduced by controlling the suction dryness D to a target dryness D* smaller than 1 using the second expansion valve LEV2. Therefore, the amount of work required by the compressor to achieve the same capacity (circulation amount) on the condenser side is reduced. In other words, the efficiency of the refrigeration cycle device is improved.

Embodiment 2.
FIG. 8 is a diagram showing the configuration of a refrigeration cycle device 201 according to the second embodiment. In Embodiment 2, a configuration that is effective when a non-azeotropic mixed refrigerant is employed will be described.

The refrigerant flowing through the refrigerant circuit C2 and the injection flow path F1 shown in FIG. 8 is a non-azeotropic mixed refrigerant. In addition to the configuration of the refrigeration cycle device 1 shown in FIG. It further includes a heat exchanger 50 for exchanging heat with the refrigerant headed for. The refrigerant circuit C2 includes the discharge port PD of the compressor 10, the condenser 20, the first expansion valve LEV1, the receiver 30, the second expansion valve LEV2, the first flow path of the heat exchanger 50, the evaporator 40, and the heat exchanger 50. The refrigerant is configured to circulate in this order through the second flow path of the compressor 10 and the suction port PS of the compressor 10.

The refrigeration cycle device 201 further includes a temperature sensor 112 that measures the saturation temperature of the low-pressure refrigerant flowing through the evaporator 40 and a temperature sensor 113 that measures the refrigerant temperature at the outlet of the evaporator 40.

The configuration of other parts of the refrigeration cycle device 201 is the same as that of the refrigeration cycle device 1 shown in FIG. 1, so the description will not be repeated.

In the configuration shown in FIG. 8, the control device 100 controls the second expansion valve LEV2 so that the degree of superheat SH1 of the refrigerant passing through the evaporator 40 and flowing toward the heat exchanger 50 approaches the target degree of superheat SH1*. configured to do so.

In this configuration, the degree of superheat is imparted to the refrigerant anywhere from the outlet of the evaporator 40 to the inlet of the heat exchanger 50. Therefore, the second expansion valve LEV2 can be controlled so that the degree of superheat matches the target value at the location where the degree of superheat is applied.

At this time, at the outlet of the evaporator 40, the degree of superheat is given and the degree of dryness of the refrigerant is 1, but since the refrigerant is then cooled by the heat exchanger 50, the degree of dryness of the refrigerant sucked into the compressor 10 increases. degree can be less than 1.

FIG. 9 is a ph diagram of the refrigeration cycle device 201. The states of the refrigerant at points A1 to A8 in FIG. 8 are indicated by points A1 to A8 in FIG. 9, respectively. On a pH diagram, in the case of a normal refrigerant, the isotherm line is parallel to the horizontal axis in the two-phase region, but in the case of a non-azeotropic mixed refrigerant, the isotherm line is downward-sloping in the two-phase region. Become. Here, the temperature of the heat exchanger 50 is around temperatures T1 and T2.

FIG. 10 is a diagram showing the temperature distribution inside the heat exchanger 50. Since the non-azeotropic refrigerant mixture has a temperature gradient, points A1 and A8 at the evaporator outlet are higher in temperature than points A6 and A7 at the evaporator inlet, respectively.

In FIG. 9, the temperature at point A8 is higher than temperature T2, and points A1, A7, and A6 move away from the isothermal line indicating temperature T2 in the order of temperature T1. This state is as shown in FIG. 10, where the vertical axis is the temperature and the horizontal axis is the position of the flow path of the heat exchanger.

Therefore, by exchanging heat in the heat exchanger 50, the enthalpy decreases from point A8 to point A1, so the refrigerant sucked into the compressor 10 becomes a wet refrigerant with a degree of dryness smaller than 1.

In this way, even if the exit portion of the evaporator 40 is given a degree of superheat, the refrigerant sucked into the compressor 10 can be a wet refrigerant. By setting the superheat degree SH1 at the outlet of the evaporator 40 to be fed back in the control of the second expansion valve LEV2, a dryness sensor is not required even when the suction dryness is controlled to be wet.

The control of the first to third expansion valves executed in the refrigeration cycle device 201 of the second embodiment will be described below.

FIG. 11 is a flowchart for explaining control of the first expansion valve LEV1 in the second embodiment. First, in step S111, the control device 100 detects the degree of subcooling SC of the refrigerant at the outlet of the condenser 20. The degree of supercooling SC can be detected by various known methods. For example, the saturation temperature corresponding to the high pressure detected by the pressure sensor provided between the discharge side of the compressor 10 and the first expansion valve LEV1 and the detection temperature of the temperature sensor that detects the temperature of the refrigerant at the outlet of the condenser 20. You can also find it by the difference between Further, the saturation temperature may be detected by a temperature sensor provided in the two-phase region of the condenser 20.

Subsequently, in step S112, the current degree of supercooling SC and the target degree of supercooling SC* are compared. If SC>SC* holds true (YES in S112), the control device 100 increases the opening degree of the first expansion valve LEV1 by a constant opening degree in step S113. On the other hand, if SC>SC* does not hold (NO in S112), the control device 100 decreases the opening degree of the first expansion valve LEV1 by a certain degree in step S114.

FIG. 12 is a flowchart for explaining control of the second expansion valve LEV2 in the second embodiment. First, in step S121, the control device 100 detects the degree of superheat SH1 of the refrigerant discharged from the evaporator 40. The degree of superheat SH1 can be determined, for example, by the difference between the saturation temperature corresponding to the low pressure detected by the sensor 112 and the temperature detected by the temperature sensor 113 that detects the temperature of the refrigerant at the outlet of the evaporator 40.

Subsequently, in step S122, the current degree of superheat SH1 and the target degree of superheat SH1* are compared. If SH1>SH1* holds true (YES in S122), the control device 100 increases the opening degree of the second expansion valve LEV2 by a certain opening degree in step S123. On the other hand, if SH1>SH1* does not hold (NO in S122), the control device 100 decreases the opening degree of the second expansion valve LEV2 by a certain degree in step S124.

By repeating the above process, the degree of superheat SH1 of the refrigerant at the outlet of the evaporator 40 is maintained near the target degree of superheat SH1*.

FIG. 13 is a flowchart for explaining control of the third expansion valve LEV3 in the second embodiment. First, in step S131, the control device 100 detects the degree of superheat SH2 of the refrigerant discharged from the compressor 10. For example, the degree of superheating SH2 is calculated from the difference between the saturation temperature corresponding to the high pressure detected by a pressure sensor provided on the discharge side of the compressor 10 and the temperature detected by a temperature sensor that detects the temperature of the refrigerant discharged from the compressor 10. It's okay. Further, the saturation temperature may be detected by a temperature sensor provided in the two-phase region of the condenser 20.

Subsequently, in step S132, the current degree of superheat SH2 and the target degree of superheat SH2* are compared. If SH2>SH2* holds true (YES in S132), the control device 100 increases the opening degree of the third expansion valve LEV3 by a constant opening degree in step S133. On the other hand, if SH2>SH2* does not hold (NO in S132), the control device 100 decreases the opening degree of the third expansion valve LEV3 by a certain degree in step S134.

By repeating the above process, the degree of superheat SH2 is maintained near the target degree of superheat SH2*.

As explained above, since there is a temperature gradient in the non-azeotropic refrigerant mixture, the evaporator inlet temperature is less than the evaporator outlet temperature, so the heat exchanger 50 can reduce the enthalpy of the suction refrigerant.

At this time, even if the opening degree of the second expansion valve LEV2 is controlled so that the degree of superheating of the refrigerant at the outlet of the evaporator 40 reaches the target value, the degree of dryness of the sucked refrigerant cannot be made smaller than 1 by the heat exchanger 50. It becomes possible.

Embodiment 3.
FIG. 14 is a diagram showing the configuration of a refrigeration cycle device 211 according to the third embodiment. In Embodiments 1 and 2, the refrigerant piping was provided so as not to pass through the inside of the receiver 30, but the refrigerant piping may be made to pass inside the receiver 30 for heat exchange.

The refrigerant flowing through the refrigerant circuit C3 and the injection flow path F1 shown in FIG. 14 is a non-azeotropic mixed refrigerant. In addition to the configuration of the refrigeration cycle device 1 shown in FIG. It further includes a heat exchanger 50 that exchanges heat with the refrigerant, and includes a receiver 30A instead of the receiver 30. The receiver 30A is configured such that the refrigerant passing through the evaporator 40 and heading toward the heat exchanger 50 and the refrigerant stored in the receiver 30A exchange heat. The refrigerant circuit C3 includes the discharge port PD of the compressor 10, the condenser 20, the first expansion valve LEV1, the reservoir of the receiver 30A, the second expansion valve LEV2, the first flow path of the heat exchanger 50, the evaporator 40, and the receiver. The refrigerant is configured to circulate in the order of the heat exchange channel 30A, the second channel of the heat exchanger 50, and the suction port PS of the compressor 10.

The control device 100 shown in FIG. 14 is configured to control the second expansion valve LEV2 so that the degree of superheat of the refrigerant passing through the evaporator 40 and the receiver 30A and flowing toward the heat exchanger 50 approaches a target value. be done. Regarding the first to third expansion valves LEV1 to LEV3, the same control as in FIGS. 11, 12, and 13 is performed in the third embodiment as well.

FIG. 15 is a ph diagram of the refrigeration cycle device 211. In FIG. 9, point A8 is in the gas phase region, but in FIG. 15, it can be seen that point A8 is in the two-phase region. This means that in the second embodiment, the refrigerant near the exit of the evaporator 40 is a gas refrigerant, but in the third embodiment, the refrigerant up to the exit of the evaporator 40 is a two-phase refrigerant. Since the evaporator generally has better heat exchange performance in the two-phase region than in the gas region, the third embodiment can improve the performance of the evaporator 40 more than the second embodiment.

In FIG. 15, point A8 at the outlet of the evaporator 40 is wet refrigerant, but by exchanging heat with the intermediate pressure refrigerant by the receiver 30A, the refrigerant is heated and given a degree of superheat as shown at point A9. Therefore, the degree of superheat SH1 of the refrigerant at point A9 can be controlled to a target value.

That is, the degree of superheat is imparted somewhere from the outlet of the evaporator 40 to the low-pressure side inlet of the heat exchanger 50, and the heat exchanger 50 causes the refrigerant sucked into the compressor 10 to become wet refrigerant. Any refrigerant circuit may be used.

In the third embodiment as well, since a non-azeotropic refrigerant mixture is used, the inlet temperature of the evaporator 40 becomes lower than the outlet temperature of the evaporator 40 due to the temperature gradient. Therefore, the enthalpy of the refrigerant sucked into the compressor 10 can be reduced by the heat exchanger 50.

At this time, by passing the receiver 30A before the temperature sensor 113, even if the second expansion valve LEV2 is controlled to set the degree of superheat to the target value, the gas phase in the evaporator 40 can be reduced. The performance of the evaporator 40 can be improved.

(summary)
The present embodiment will be summarized below with reference to the drawings again.

(1) The present disclosure relates to a refrigeration cycle device 1. The refrigeration cycle device 1 shown in FIG. 1 includes a refrigerant circuit C1, an injection flow path F1, and a control device 100. Refrigerant circuit C1 includes a compressor 10 having a suction port PS and a discharge port PD, a condenser 20, a first expansion valve LEV1, a receiver 30, a second expansion valve LEV2, and an evaporator 40. The refrigerant circuit C1 is configured such that refrigerant circulates in the order of the discharge port PD of the compressor 10, the condenser 20, the first expansion valve LEV1, the receiver 30, the second expansion valve LEV2, the evaporator 40, and the suction port PS of the compressor 10. It is composed of Compressor 10 further includes an injection port PM. The injection flow path F1 includes a third expansion valve LEV3, and is configured to send the refrigerant depressurized by the first expansion valve LEV1 to the injection port PM via the third expansion valve LEV3. The control device 100 is configured to control the second expansion valve LEV2 so that the degree of dryness of the refrigerant in the suction port PS is less than 1.

(2) In the refrigeration cycle device described in (1), the refrigeration cycle device 1 further includes a capacitive sensor 111 that detects the dryness of the refrigerant in the suction port PS. The control device 100 is configured to control the second expansion valve LEV2 so that the degree of dryness D indicated by the output of the sensor 111 approaches the target degree of dryness D*.

(3) In the refrigeration cycle device described in (2), as shown in FIG. 6, when the dryness D indicated by the output of the sensor 111 is larger than the target dryness D*, the control device The opening degree of the expansion valve LEV2 is decreased, and when the degree of dryness D indicated by the output of the sensor 11 is smaller than the target degree of dryness D*, the degree of opening of the second expansion valve LEV2 is increased.

(4) In the refrigeration cycle device described in (1), the refrigerant flowing through the refrigerant circuits C2 and C3 and the injection flow path F1 shown in FIGS. 8 and 14 is a non-azeotropic mixed refrigerant. The

refrigeration cycle devices

201 and 211 include a heat exchanger 50 that exchanges heat between the refrigerant that passes through the second expansion valve LEV2 and goes to the evaporator 40, and the refrigerant that passes through the evaporator 40 and goes to the suction port PS of the compressor 10. Be prepared for more.

(5) In the refrigeration cycle device described in (4), the control device 100 shown in FIGS. 8 and 14 sets the degree of superheat SH1 of the refrigerant passing through the evaporator 40 and flowing toward the heat exchanger 50 as a first target. The second expansion valve LEV2 is configured to be controlled so as to approach the degree of superheat SH1*.

(6) In the refrigeration cycle device described in (5), as shown in FIG. When the superheat degree SH1* is larger than the first target superheat degree SH1*, the opening degree of the second expansion valve LEV2 is increased, and when the superheat degree SH1 of the refrigerant flowing toward the heat exchanger 50 is smaller than the first target superheat degree SH1*. , is configured to reduce the opening degree of the second expansion valve LEV2.

(7) In the refrigeration cycle device described in (1), the refrigerant flowing through the refrigerant circuit C3 and the injection flow path F1 shown in FIG. 14 is a non-azeotropic mixed refrigerant. The refrigeration cycle device 211 further includes a heat exchanger 50 that exchanges heat between the refrigerant that passes through the second expansion valve LEV2 and heads toward the evaporator 40 and the refrigerant that passes through the evaporator 40 and heads toward the suction port PS of the compressor 10. . The receiver 30A is configured such that the refrigerant passing through the evaporator 40 and heading toward the heat exchanger 50 exchanges heat with the refrigerant stored in the receiver 30A.

(8) In the refrigeration cycle device described in (7), the control device 100 shown in FIG. The second expansion valve LEV2 is configured to be controlled so as to approach the degree of superheat SH1*.

(9) In the refrigeration cycle device described in (8), the control device 100 controls the degree of superheat SH1 of the refrigerant passing through the evaporator 40 and the receiver 30A and flowing toward the heat exchanger 50, as shown in FIG. When the degree of superheat is larger than the first target degree of superheat SH1*, the opening degree of the second expansion valve LEV2 is increased, and the degree of superheat SH1 of the refrigerant flowing toward the heat exchanger 50 is smaller than the first target degree of superheat SH1*. In this case, the opening degree of the second expansion valve LEV2 is reduced.

(10) In the refrigeration cycle device according to any one of (1) to (9), the control device 100 shown in FIGS. 1, 8, and 14 controls the degree of subcooling of the refrigerant at the outlet of the condenser 20. The opening degree of the first expansion valve LEV1 is controlled so as to approach the target supercooling degree, and the opening degree of the third expansion valve LEV3 is controlled so that the degree of superheating of the refrigerant discharged by the compressor 10 approaches the second target superheating degree. configured to control.

(11) In the refrigeration cycle device described in (10), as shown in FIG. 5 or FIG. If the degree of subcooling SC of the refrigerant at the outlet of the condenser 20 is smaller than the target degree of subcooling SC*, the opening degree of the first expansion valve LEV1 is increased. configured to reduce the degree of As shown in FIG. 7 or 13, when the degree of superheat SH2 of the refrigerant discharged by the compressor 10 is larger than the second target degree of superheat SH2*, the control device 100 controls the opening degree of the third expansion valve LEV3. When the degree of superheat SH2 of the refrigerant discharged by the compressor 10 is smaller than the second target degree of superheat SH2*, the opening degree of the third expansion valve LEV3 is decreased.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is indicated by the claims rather than the above description, and it is intended that equivalent meanings to the claims and all changes within the range are included.

1,201,211 Refrigeration cycle device, 10 Compressor, 11 Orbiting scroll, 12 Fixed scroll, 14 Pedestal, 15 Lid, 18 Check valve, 20 Condenser, 22, 42 Fan, 30, 30A receiver, 40 Evaporator, 50 Heat exchanger, 100 Control device, 101 CPU, 102 Memory, 112, 113 Temperature sensor, C1, C2, C3 Refrigerant circuit, F1 Injection flow path, LEV1 First expansion valve, LEV2 Second expansion valve, LEV3 Third expansion Valve, PD discharge port, PM injection port, PS suction port.

Claims

Comprising a refrigerant circuit, an injection flow path, and a control device,
The refrigerant circuit includes a compressor having a suction port and a discharge port, a condenser, a first expansion valve, a receiver, a second expansion valve, and an evaporator, the discharge port of the compressor, the The refrigerant is configured to circulate in the order of the condenser, the first expansion valve, the receiver, the second expansion valve, the evaporator, and the suction port of the compressor,
The compressor further includes an injection port,
The injection flow path includes a third expansion valve, and is configured to send the refrigerant depressurized by the first expansion valve to the injection port via the third expansion valve,
A refrigeration cycle device, wherein the control device is configured to control the second expansion valve so that the degree of dryness of the refrigerant in the suction port is less than 1.
further comprising a capacitive sensor that detects the dryness of the refrigerant in the suction port,
The refrigeration cycle device according to claim 1, wherein the control device is configured to control the second expansion valve so that the degree of dryness indicated by the output of the sensor approaches a target degree of dryness.
When the degree of dryness indicated by the output of the sensor is larger than the target degree of dryness, the control device reduces the opening degree of the second expansion valve, and the degree of dryness indicated by the output of the sensor is equal to the target degree of dryness. The refrigeration cycle apparatus according to claim 2, wherein the refrigeration cycle apparatus is configured to increase the opening degree of the second expansion valve when the opening degree is smaller than .
The refrigerant flowing through the refrigerant circuit and the injection flow path is a non-azeotropic mixed refrigerant,
The refrigerant according to claim 1, further comprising a heat exchanger that exchanges heat between the refrigerant passing through the second expansion valve and heading toward the evaporator, and the refrigerant passing through the evaporator heading toward the suction port of the compressor. Refrigeration cycle equipment.
The control device is configured to control the second expansion valve so that the degree of superheat of the refrigerant passing through the evaporator and flowing toward the heat exchanger approaches a first target degree of superheat. Item 4. Refrigeration cycle device according to item 4.
The control device increases the opening degree of the second expansion valve when the degree of superheat of the refrigerant passing through the evaporator and flowing toward the heat exchanger is larger than the first target degree of superheat, The refrigeration system according to claim 5, configured to reduce the opening degree of the second expansion valve when the degree of superheat of the refrigerant flowing toward the heat exchanger is smaller than the first target degree of superheat. cycle equipment.
The refrigerant flowing through the refrigerant circuit and the injection flow path is a non-azeotropic mixed refrigerant,
Further comprising a heat exchanger for exchanging heat between the refrigerant passing through the second expansion valve and heading to the evaporator, and the refrigerant passing through the evaporator heading towards the suction port of the compressor,
The refrigeration cycle device according to claim 1, wherein the receiver is configured so that the refrigerant passing through the evaporator and heading toward the heat exchanger exchanges heat with the refrigerant stored in the receiver.
The control device is configured to control the second expansion valve so that the degree of superheat of the refrigerant passing through the evaporator and the receiver and flowing toward the heat exchanger approaches a first target degree of superheat. The refrigeration cycle device according to claim 7.
The control device increases the opening degree of the second expansion valve when the degree of superheat of the refrigerant passing through the evaporator and the receiver and flowing toward the heat exchanger is larger than a first target degree of superheat. and is configured to reduce the opening degree of the second expansion valve when the degree of superheat of the refrigerant flowing toward the heat exchanger is smaller than the first target degree of superheat. Refrigeration cycle equipment.
The control device controls the opening degree of the first expansion valve so that the degree of supercooling of the refrigerant at the outlet of the condenser approaches the target degree of supercooling, and also controls the degree of superheating of the refrigerant discharged by the compressor to a first degree. 10. The refrigeration cycle apparatus according to claim 1, wherein the refrigeration cycle apparatus is configured to control the opening degree of the third expansion valve so as to approach the second target superheat degree.
When the degree of subcooling of the refrigerant at the outlet of the condenser is larger than the target degree of subcooling, the control device increases the opening degree of the first expansion valve to reduce the degree of supercooling of the refrigerant at the outlet of the condenser. configured to reduce the opening degree of the first expansion valve when the degree of cooling is smaller than the target degree of supercooling;
When the degree of superheat of the refrigerant discharged by the compressor is larger than the second target degree of superheat, the control device increases the opening degree of the third expansion valve to reduce the superheat of the refrigerant discharged by the compressor. The refrigeration cycle device according to claim 10, wherein when the degree of superheat is smaller than the second target degree of superheat, the opening degree of the third expansion valve is decreased.