JP2024145834A - Refrigeration Cycle Equipment - Google Patents

Abstract

The total capacity of compressors is suppressed compared to when refrigeration capacity is ensured by increasing the amount of refrigerant circulated. [Solution] The refrigeration cycle device includes a first compression element that compresses the drawn refrigerant and discharges it into a first flow path, a radiator that is provided in the first flow path and passes the refrigerant through and radiates heat extracted from the passing refrigerant, a branching section that branches the refrigerant that has passed through the radiator in the first flow path into a first branch and a second branch, a first pressure reduction element that reduces the pressure of the refrigerant branched into the first branch and causes it to flow into the second flow path, a heat exchanger that exchanges heat between the refrigerant flowing through the second flow path and the refrigerant branched into the second branch, a second pressure reduction element that reduces the pressure of the refrigerant that has undergone heat exchange in the heat exchanger in the second branch, a cooler that cools an object by exchanging heat between the refrigerant that has been reduced in pressure by the second pressure reduction element and the object, and causes the refrigerant that has undergone heat exchange to be drawn into the first compression element, a second compression element that draws in the refrigerant that has undergone heat exchange in the second flow path through the heat exchanger, compresses it, and discharges it into a third flow path, and a merging section that merges the third flow path into the first flow path. [Selected Figure] Figure 2

Description

The present invention relates to a refrigeration cycle device.

Patent document 1 describes a compressor system in which multiple compressors are connected in parallel.

Patent No. 5758818

For example, there is a refrigeration cycle device that uses the compressor system of Patent Document 1 to increase the amount of refrigerant circulated and increase the amount of refrigerant available for cooling an object, thereby ensuring refrigeration capacity. In such a refrigeration cycle device, the total capacity of the compressors needs to be increased as the refrigeration capacity required for cooling the object increases. More specifically, it is necessary to increase the number of compressors or the capacity of each compressor, which leads to increased equipment costs and an increase in the size of the entire refrigeration cycle device.
The present disclosure proposes a refrigeration cycle device in which the total capacity of the compressors is reduced compared to a case in which the refrigeration capacity is ensured by increasing the amount of refrigerant circulated.

A refrigeration cycle apparatus according to a first aspect includes a first compression element that compresses a drawn refrigerant and discharges it to a first flow path, a radiator that is provided in the first flow path and passes the refrigerant through and radiates heat extracted from the passing refrigerant, a branching section that branches the refrigerant after passing through the radiator in the first flow path into a first branch and a second branch, a first pressure reduction element that reduces the pressure of the refrigerant branched to the first branch and causes it to flow into the second flow path, a heat exchanger that performs heat exchange between the refrigerant flowing through the second flow path and the refrigerant branched to the second branch, a second pressure reduction element that reduces the pressure of the refrigerant after heat exchange by the heat exchanger in the second branch, a cooler that cools an object by heat exchange between the refrigerant after pressure reduction by the second pressure reduction element and the object and causes the refrigerant after heat exchange to be drawn into the first compression element, a second compression element that draws in the refrigerant after heat exchange by the heat exchanger in the second flow path, compresses it, and discharges it to a third flow path, and a junction section that merges the third flow path with the first flow path. In this case, the total capacity of the compressors is reduced compared to when the refrigerant circulation amount is increased to ensure refrigeration capacity.
A refrigeration cycle apparatus according to a second aspect is the refrigeration cycle apparatus according to the first aspect, wherein the junction joins the third flow path at a position in the first flow path after the refrigerant has passed through the radiator, and the junction includes a second radiator that is provided in the third flow path and radiates heat extracted by passing the refrigerant compressed by the second compression element through the second radiator. In this case, heat radiation from the radiator can be increased compared to a case in which the junction joins the third flow path at a position in the first flow path before the refrigerant has passed through the radiator.
A refrigeration cycle apparatus according to a third aspect is the refrigeration cycle apparatus according to the second aspect, in which the capacity of the first compression element is larger than the capacity of the second compression element. In this case, heat dissipation from the radiator can be increased compared to a case in which the capacity of the first compression element is smaller than the capacity of the second compression element.
A refrigeration cycle apparatus according to a fourth aspect is the refrigeration cycle apparatus according to the third aspect, further comprising a third pressure reducing element provided in the third flow path and reducing the pressure of the refrigerant after passing through the second radiator. In this case, a compression ratio in the second compression element can be set large.
A refrigeration cycle apparatus according to a fifth aspect is the refrigeration cycle apparatus according to the second aspect, further comprising a fourth pressure reducing element provided in the first flow path after the refrigerant has passed through the radiator and before the merging portion merges with the third flow path, the fourth pressure reducing element reducing the pressure of the refrigerant after the refrigerant has passed through the radiator. In this case, a compression ratio in the first compression element can be set to be large.
A refrigeration cycle apparatus according to a sixth aspect is the refrigeration cycle apparatus according to any one of the first to fifth aspects, in which at least a part of the refrigerant is carbon dioxide. In this case, heat dissipation in the radiator is greater than in the case of using a non-azeotropic refrigerant not containing carbon dioxide.
A refrigeration cycle apparatus according to a seventh aspect is the refrigeration cycle apparatus according to the first aspect, further comprising: temperature sensors for measuring a temperature of the refrigerant at a position in the first flow path before passing through the radiator and before the third flow path merges with the junction, and at a position in the third flow path before the refrigerant merges with the first flow path at the junction, and a control unit for controlling circulation of the refrigerant based on the temperature of the refrigerant measured by the temperature sensors, wherein the control unit controls the flow resistance of the first pressure reduction element to increase when the temperature of the refrigerant measured in the first flow path is higher than the temperature of the refrigerant measured in the third flow path. In this case, an enthalpy difference between the refrigerant compressed by the first compression element and the refrigerant compressed by the second compression element is reduced.
A refrigeration cycle apparatus according to an eighth aspect is the refrigeration cycle apparatus according to the first aspect, further comprising: temperature sensors for measuring a temperature of the refrigerant at a position in the first flow path before passing through the radiator and before the third flow path merges with the junction, and at a position in the third flow path before the refrigerant merges with the first flow path at the junction, and a control unit for controlling circulation of the refrigerant based on the temperature of the refrigerant measured by the temperature sensors, wherein the control unit controls the flow rate of the second compression element to increase when the temperature of the refrigerant measured in the first flow path is higher than the temperature of the refrigerant measured in the third flow path. In this case, an enthalpy difference between the refrigerant compressed by the first compression element and the refrigerant compressed by the second compression element becomes small.

1 is a diagram showing an example of the schematic configuration of an air conditioning device to which the present embodiment is applied; 1 is a schematic diagram of a refrigerant circuit according to a first embodiment. FIG. 1 is a pressure-specific enthalpy diagram illustrating a refrigeration cycle of a refrigerant circulating in a refrigerant circuit according to a first embodiment. FIG. FIG. 6 is a schematic diagram of a refrigerant circuit according to a second embodiment. FIG. 11 is a schematic diagram of a refrigerant circuit according to a third embodiment. FIG. 10 is a schematic diagram of a refrigerant circuit according to a fourth embodiment. FIG. 10 is a diagram illustrating a refrigerant circuit of an application example. 1A is a schematic diagram of a refrigerant circuit in a conventional refrigeration cycle device, and FIG. 1B is a pressure-specific enthalpy diagram illustrating a refrigeration cycle of a refrigerant circulating in the refrigerant circuit.

First, a description will be given of the conventional technology to which the embodiment of the present invention is not applicable.
8A is a schematic diagram of a refrigerant circuit 10' in the conventional refrigeration cycle device, and FIG. 8B is a pressure-specific enthalpy diagram illustrating the refrigeration cycle of the refrigerant circulating in the refrigerant circuit 10'. In FIG. 8B, the horizontal axis represents specific enthalpy [kJ/kg], and the vertical axis represents absolute pressure [MPa.abs] based on absolute vacuum.
In Fig. 8(a), the lines connecting the devices are pipes that serve as the flow path of the refrigerant. In Fig. 8(b), a refrigeration cycle 300' is shown using thick lines, and points 10a' to 10f' on the refrigeration cycle 300' correspond to positions 10a' to 10f' of the refrigerant circuit 10', respectively. Therefore, points 10a' to 10f' in the refrigeration cycle 300' are expressed as positions 10a' to 10f'. In addition to the refrigeration cycle 300', Fig. 8(b) also shows a saturated liquid line 301, a saturated vapor line 302, a critical point 303, and a 45°C isotherm 304 of the carbon dioxide refrigerant.

As shown in FIG. 8(a), the refrigerant circuit 10' includes two compressors 12' and 13' connected in parallel, a radiator 14', a pressure reducing valve 18', and a cooler 19', and circulates carbon dioxide, which is an example of a refrigerant. More specifically, the refrigerant that has passed through the cooler 19' and exchanged heat with the object branches into two branches at the branching section 30' (position 10a'). Of the branched refrigerant, the refrigerant that flows through one branch is compressed by the compressor 12', and the refrigerant that flows through the other branch is compressed by the compressor 13', and then merges at the merging section 20' (position 10b'). The merged refrigerant passes through the radiator 14' to radiate heat (position 10e'). Then, the refrigerant after radiating heat is depressurized through the pressure reducing valve 18' (position 10f') and passes through the cooler 19' again (position 10a').

At each position of the refrigerant circuit 10', the specific enthalpy and pressure of the refrigerant change due to each device, and a refrigerant refrigeration cycle is established. More specifically, as shown in FIG. 8(b), from position 10a' to position 10b', the pressure and specific enthalpy of the refrigerant increase due to compression by compressors 12' and 13' and the acquisition of compression heat. Also, from position 10b' to position 10e', the specific enthalpy of the refrigerant decreases due to heat dissipation in the radiator 14'. Furthermore, from position 10e' to position 10f', the pressure of the refrigerant decreases due to pressure reduction by the pressure reducing valve 18'. Furthermore, from position 10f' to position 10a', the specific enthalpy of the refrigerant increases due to heat exchange with the object in the cooler 19'.

In a refrigeration cycle device, the ability of a cooler to cool an object (sometimes referred to as "refrigeration capacity") is determined according to the amount of heat (heat absorption) that the refrigerant passing through the cooler takes from the object. Therefore, in a conventional refrigeration cycle device using a refrigerant circuit 10', the refrigeration capacity of the cooler 19' is determined according to the product of the amount of change in specific enthalpy when moving from position 10f' to position 10a' and the amount of refrigerant passing through the cooler 19'.
In a conventional refrigeration cycle apparatus using the refrigerant circuit 10', in order to increase the refrigeration capacity of the cooler 19', the amount of refrigerant circulating in the refrigerant circuit 10' is increased, and the amount of refrigerant passing through the cooler 19' is increased. More specifically, the number of compressors connected in parallel to the compressors 12', 13' is increased, or the capacities of the compressors 12', 13' are increased. Therefore, in a refrigeration cycle apparatus using the conventional refrigerant circuit 10', the greater the refrigeration capacity to be secured, the greater the total capacity of the compressors. Note that the "total capacity" is the sum of the capacities of all the compressors provided in the refrigerant circuit.

A refrigeration cycle apparatus to which the embodiment of the present invention is applied has a configuration that suppresses the total capacity of the compressors, compared to a case in which the refrigerant circulation amount is increased to ensure refrigeration capacity.
Hereinafter, an embodiment of the present invention will be described in detail.

First Embodiment
(Air Conditioning Apparatus 1)
FIG. 1 is a diagram showing a schematic configuration example of an air conditioning device 1 to which this embodiment is applied.
As shown in the figure, an air-conditioning apparatus 1 to which this embodiment is applied includes a refrigerant circuit 10 through which a refrigerant circulates, and a control unit 50 that controls the circulation of the refrigerant in the refrigerant circuit 10. The control unit 50 is connected by wire or wirelessly to each device (described later using FIG. 2) included in the refrigerant circuit 10, and is capable of transmitting control signals to each device.
The air conditioning device 1 is an example of a refrigeration cycle device in this embodiment.

The air conditioner 1 cools the air it takes in and supplies it to the space as cold air to cool the space. More specifically, the air conditioner 1 cools the air by extracting heat from the air through heat exchange between the air, which is an example of a target object, and the refrigerant passing through a cooler (details of which will be described later using FIG. 2) built into the refrigerant circuit 10. The cooled air is then supplied to the space as cold air from an air outlet of the indoor unit or the like (not shown), to cool the space.

(Control unit 50)
The control unit 50 controls the circulation of the refrigerant in the refrigerant circuit 10 by sending control signals to each device included in the refrigerant circuit 10. It also controls the amount of cool air that the air conditioning device 1 supplies to the space. The control unit 50 according to this embodiment has, for example, an operation panel or a controller that accepts operations from a user, and performs control according to operation input from the user, such as temperature setting and air volume setting. It also has, for example, a temperature sensor that measures the temperature of the space, and performs control according to the measured value. It also has, for example, a temperature sensor that measures the temperature of the refrigerant in the refrigerant circuit 10, and performs control according to the measured value.
Additionally, the control unit 50 may obtain information regarding the operation of each device included in the refrigerant circuit 10, such as an effective value of the operation in response to a control value, and perform control according to the obtained information.

(Refrigerant circuit 10)
The refrigerant circuit 10 is a circuit that establishes a refrigeration cycle of the refrigerant as the refrigerant circulates, and enables cooling of an object by heat exchange with the refrigerant. More specifically, the refrigerant circuit 10 according to the present embodiment establishes a refrigeration cycle of the carbon dioxide refrigerant by circulating the carbon dioxide refrigerant, which is an example of a refrigerant, while adjusting the specific enthalpy and pressure, and enables cooling of the air by extracting heat from the air through heat exchange on the low pressure side. In the following description, the carbon dioxide refrigerant circulating through the refrigerant circuit 10 may be simply referred to as the "refrigerant".
In addition, in the refrigerant circuit 10, not only the refrigerant but also a fluid other than the refrigerant, such as a lubricating oil for ensuring lubrication in the compressor described below, may circulate.

FIG. 2 is a schematic diagram of the refrigerant circuit 10 according to the first embodiment.
As shown in the figure, a refrigerant circuit 10 according to the first embodiment includes compressors 12, 13 that compress a refrigerant, a radiator 14 that extracts heat from the refrigerant and radiates the heat, a refrigerant-refrigerant heat exchanger 17 that performs heat exchange between the refrigerants, electric valves 16, 18 whose opening degree can be adjusted, and a cooler 19 that cools air by heat exchange with the refrigerant passing through it.
The refrigerant circuit 10 also includes a temperature sensor 501 that measures the temperature of the refrigerant compressed by the compressor 12 and discharged, and a temperature sensor 502 that measures the temperature of the refrigerant compressed by the compressor 13. In addition to the above-mentioned devices, the refrigerant circuit 10 may also include a pressure sensor and a temperature sensor that measure the pressure and temperature of the refrigerant at each point, a receiver that can store the refrigerant, a pressure switch as a protection mechanism, a filter, a heat sink, an oil separator, and the like.

In FIG. 2, the lines connecting the devices are flow paths through which the refrigerant flows, and are, for example, metal pipes.
As shown in the figure, the flow paths of the refrigerant circuit 10 are provided with a branching section 15 that branches the flow paths and a merging section 20 that merges the flow paths. Here, the section from the compressor 12 to the branching section 15 is referred to as a first flow path 101, the section from the motor-operated valve 16 to the compressor 13 is referred to as a second flow path 102, the section from the compressor 13 to the merging section 20 is referred to as a third flow path 103, and the section from the motor-operated valve 18 to the compressor 12 is referred to as a fourth flow path 104. In addition, of the flow paths branched by the branching section 15, one connected to the motor-operated valve 16 is referred to as a first branch 151, and the other connected to the cooler 19 via the motor-operated valve 18 is referred to as a second branch 152. Each flow path may be formed of a single seamless pipe, or may be formed by connecting two or more pipes by a flange structure (not shown). In addition, various devices may be included in the middle of the flow path.

The compressor 12 is a device that compresses the refrigerant drawn from the fourth flow path 104 and discharges the refrigerant to the first flow path 101. The compressor 13 is a device that compresses the refrigerant drawn from the second flow path 102 and discharges the refrigerant to the third flow path 103. The mechanisms of the compressors 12 and 13 are not limited, and various mechanisms such as an oscillating type, a scroll type, or a rotary type may be used.
The compressors 12 and 13 compress and discharge the sucked refrigerant at a compression ratio (=pressure of the discharged refrigerant/pressure of the sucked refrigerant) set according to control from the control unit 50 (see FIG. 1). In the compressors 12 and 13 according to this embodiment, for example, the operating frequency and the amount of sucked/discharged refrigerant are controlled according to a control signal from the control unit 50. The "operating frequency" refers to the frequency of operation of the parts for compressing the refrigerant performed within the compressor. Specifically, for example, it is the frequency of oscillation of an oscillator in an oscillatory compressor, or the frequency of rotation of a rotor in a scroll compressor or a rotary compressor.
The compressor 12 is an example of a first compression element, and the compressor 13 is an example of a second compression element.

The radiator 14 is a device provided in the first flow path 101, which extracts heat from the refrigerant by heat exchange between the passing refrigerant and a fluid such as air or water, and radiates the heat. As shown in the figure, in the refrigerant circuit 10 according to the first embodiment, the radiator 14 is provided between the junction 20 and the branching portion 15 in the first flow path 101. As the radiator 14, various types of heat exchangers, such as a tube-type heat exchanger or a plate-type heat exchanger, can be used.
In the radiator 14, the fluid that has exchanged heat with the refrigerant is heated by the heat extracted from the refrigerant. For this reason, for example, air may be used as the fluid, and the heated air may be supplied to the space as hot air to be used for space heating. Also, for example, water may be used as the fluid, and the heated water may be supplied to a user to be used for hot water supply. In this way, the radiator 14 can also be used as a heater that heats the fluid.

The motor-operated valves 16 and 18 are configured to include a valve such as a ball valve and a motor for driving the valve, and the motor adjusts the valve opening to adjust the pressure of the refrigerant flowing. More specifically, the motor-operated valve 16 is provided between the first branch 151 and the second flow path 102, and reduces the pressure of the refrigerant flowing from the first branch 151 by throttling and expanding the refrigerant according to the valve opening, and then flows it to the second flow path 102. The motor-operated valve 18 is provided between the refrigerant-refrigerant heat exchanger 17 and the cooler 19 in the second branch 152, and reduces the pressure of the refrigerant flowing from the refrigerant-refrigerant heat exchanger 17 side by throttling and expanding the refrigerant according to the valve opening, and then flows it to the cooler 19 side. The opening of the motor-operated valve 16 and the opening of the motor-operated valve 18 are adjusted by driving and controlling the respective motors according to a control signal from the control unit 50.
Moreover, the motor-operated valves 16, 18 have flow resistance according to their respective openings. The flow resistance is an index of how difficult it is for the refrigerant to flow through the motor-operated valves 16, 18. The larger the opening, the more difficult it is for the refrigerant to flow, and therefore the higher the flow resistance, whereas the smaller the opening, the easier it is for the refrigerant to flow, and therefore the lower the flow resistance.
Here, the motor-operated valve 16 is an example of a first pressure reducing element, and the motor-operated valve 18 is an example of a second pressure reducing element. Note that, as the pressure reducing element that can be controlled by the control unit 50 (see FIG. 1), in addition to the motor-operated valve, a solenoid valve that drives a valve using a solenoid may be used.

The refrigerant-refrigerant heat exchanger 17 is a device that performs heat exchange between the refrigerant flowing through the second flow path 102 and the refrigerant flowing through the second branch 152. More specifically, the refrigerant-refrigerant heat exchanger 17 performs heat exchange between the refrigerant that branches into the first branch 151 at the branching section 15 and flows through the second flow path 102 in a state where the pressure is reduced by the motor-operated valve 16, and the refrigerant that branches into the second branch 152 at the branching section 15. In the heat exchange in the refrigerant-refrigerant heat exchanger 17, the refrigerant flowing through the second flow path 102 extracts heat from the refrigerant flowing through the second branch 152, and as a result, the refrigerant flowing through the second branch 152 is cooled.

The cooler 19 is provided in the fourth flow path 104 and is a device that extracts heat from the air and cools the air by heat exchange between the refrigerant passing through the cooler 19. A heat exchanger such as a tube-type heat exchanger can be used as the cooler 19.
The air exchanges heat with the refrigerant in the cooler 19, and the cooled air is supplied to a space through an air passage (not shown) to cool the space. In this way, the cooling function of the air conditioner 1 (see FIG. 1 ) is realized.

The circulation of the refrigerant in the refrigerant circuit 10 will be described. In the refrigerant circuit 10 according to the first embodiment, the refrigerant (position 10a) after passing through the cooler 19 and cooling the air is compressed by the compressor 12 and discharged into the first flow path 101 (position 10b). The refrigerant discharged into the first flow path 101 is merged with the third flow path 103 at the merging section 20 (position 10c), passes through the radiator 14 to dissipate heat, and then branches into the first branch 151 and the second branch 152 at the branching section 15 (position 10d). The refrigerant branched into the first branch 151 is depressurized by the motor-operated valve 16 and flows into the second flow path 102 (position 10g), and exchanges heat with the refrigerant branched into the second branch 152 in the refrigerant-refrigerant heat exchanger 17 (position 10h). Then, the refrigerant is compressed by the compressor 13 and discharged into the third flow path 103 (position 10i), and merges with the first flow path 101 at the junction 20 (position 10c). On the other hand, the refrigerant (position 10e) after branching into the second branch 152 and exchanging heat in the refrigerant-refrigerant heat exchanger 17 is decompressed by the motor-operated valve 18 (position 10f), and passes through the cooler 19 to cool the air (position 10a).
By circulating the refrigerant in this manner, the refrigerant circuit 10 establishes a refrigeration cycle of the refrigerant.

(Refrigeration cycle)
The refrigeration cycle in the refrigerant circuit 10 will be described in detail with reference to FIGS.
3 is a pressure-specific enthalpy diagram illustrating a refrigeration cycle 300 of a refrigerant circulating through the refrigerant circuit 10 according to the first embodiment. In FIG. 3, the horizontal axis represents specific enthalpy [kJ/kg], and the vertical axis represents absolute pressure [MPa.abs] based on an absolute vacuum.
In Fig. 3, the refrigeration cycle 300 is indicated by a thick line. Points 10a to 10i on the refrigeration cycle 300 correspond to positions 10a to 10i of the refrigerant circuit 10 shown in Fig. 2, respectively. For this reason, points 10a to 10i on the refrigeration cycle 300 are expressed as positions 10a to 10i. In addition to the refrigeration cycle 300, Fig. 3 also indicates a saturated liquid line 301, a saturated vapor line 302, a critical point 303, and a 45°C isotherm 304 of the carbon dioxide refrigerant.

In the refrigerant circuit 10 according to the first embodiment, the refrigerant compressed by the compressor 12 and having acquired the heat of compression is discharged into the first flow path 101, so that the pressure and specific enthalpy of the refrigerant rise from position 10a to position 10b of the refrigeration cycle 300. In addition, the third flow path 103 joins at the joining section 20, so that the specific enthalpy of the refrigerant changes from position 10b to position 10c. Furthermore, the refrigerant after joining releases heat by heat exchange with the fluid in the radiator 14, so that the specific enthalpy of the refrigerant drops from position 10c to position 10d. The refrigerant at position 10c is pressurized and heated by the compressors 12 and 13, and reaches a high temperature of, for example, more than 45°C. Therefore, even if the fluid with which the heat exchange takes place in the radiator 14 is at room temperature (15°C to 25°C), it can still take heat from the refrigerant.

At position 10d, the first branch 151 branched at the branching section 15 is depressurized by the motor-operated valve 16 and flows into the second flow path 102, so the pressure of the refrigerant drops from position 10d to position 10g. As the pressure drops, the temperature of the refrigerant flowing into the second flow path 102 drops and becomes lower than the temperature of the refrigerant flowing into the second branch 152. Therefore, the refrigerant flowing into the second flow path 102 absorbs heat from the refrigerant in the first branch 151 through heat exchange with the refrigerant in the first branch 151 in the refrigerant-refrigerant heat exchanger 17, and the specific enthalpy increases from position 10g to position 10h. Conversely, the refrigerant in the second branch 152 absorbs heat through heat exchange, so the specific enthalpy drops from position 10d to position 10e.

The refrigerant in the second branch 152 after passing through the refrigerant-refrigerant heat exchanger 17 is depressurized by the motor-operated valve 18, and the pressure of the refrigerant decreases from position 10e to position 10f. Then, the depressurized refrigerant exchanges heat with the air in the cooler 19 to remove heat, and the specific enthalpy of the refrigerant increases from position 10f to position 10a. Note that the refrigerant at position 10f is in a state where it has been depressurized and cooled by the motor-operated valve 18, and is at a sufficiently low temperature relative to the air to be cooled. Therefore, in the cooler 19, heat can be removed from the air with which it exchanges heat.
Furthermore, after passing through the refrigerant-refrigerant heat exchanger 17, the refrigerant in the second flow path 102 is compressed by the compressor 13 and acquires heat of compression, so that the pressure and specific enthalpy of the refrigerant increase from position 10h to position 10i.

As described above, the refrigeration cycle 300 of the refrigerant circuit 10 is established.
Here, the refrigerant that cools the air in the cooler 19 has had heat removed by heat exchange between refrigerants in the refrigerant-refrigerant heat exchanger 17 before being decompressed by the motor-operated valve 18. For this reason, the refrigerant that cools the air in the cooler 19 of the refrigerant circuit 10 (position 10f in FIGS. 2 and 3) has a lower specific enthalpy than the refrigerant that cools the air in the cooler 19' of the conventional refrigerant circuit 10' (position 10f' in FIG. 8). As a result, in the refrigerant circuit 10, the amount of heat removed by the refrigerant per unit amount in the cooler 19 is larger than in the conventional refrigerant circuit 10' where heat exchange between refrigerants is not performed, and the refrigeration capacity can be ensured without increasing the amount of refrigerant circulating.

In the refrigerant circuit 10, the carbon dioxide refrigerant becomes supercritical in part of the refrigeration cycle 300, and the change in density of the refrigerant caused by the change in refrigerant pressure is greater than when the refrigerant is not in a supercritical state. Therefore, the refrigeration capacity that can be secured for the compression work of the compressors 12 and 13 is greater than when the refrigerant does not go through a supercritical state. This is also true for the refrigerant circuits according to the second to fourth embodiments described below.

Here, the performance of the refrigerant circuit 10 according to the first embodiment will be compared with that of a conventional refrigerant circuit 10' with reference to Figs.
Table 1 shows the capacities and coefficients of performance (COP) of the compressors 12, 13/12', 13' in the air conditioner 1 using the refrigerant circuit 10 according to the first embodiment and in an air conditioner using a conventional refrigerant circuit 10'. The COP is a value obtained by dividing the cooling effect of the cooler 17/17' of the refrigerant circuit 10/10' by the power consumption related to the operation of the refrigerant circuit 10/10', and corresponds to the efficiency of the cooling effect relative to the power consumption.

As shown in Table 1, when the capacity of compressor 12 in refrigerant circuit 10 is 106cc, the capacity of compressor 13 is 33cc, and the total capacity is 139cc, the COP of the air conditioner 1 is 1.90. On the other hand, when the capacity of compressors 12', 13' in conventional refrigerant circuit 10' is 81.5cc, and the total capacity is 163cc, the COP of the air conditioner is 1.60. In other words, if the total capacity and COP of an air conditioner using a conventional refrigerant circuit 10' are 100% (standard), the air conditioner 1 using refrigerant circuit 10 can increase the COP to 119% while suppressing the total capacity to 85%.

As described above, in an air conditioner 1 using a refrigerant circuit 10, refrigeration capacity is secured by heat exchange between refrigerants in the refrigerant-refrigerant heat exchanger 17. Therefore, compared to a conventional refrigerant circuit 10 that secures refrigeration capacity by increasing the amount of refrigerant circulating, the cooling effect of the air conditioner 1 can be increased even when the total capacity of the compressor is reduced.

(Control by the control unit 50)
Incidentally, the control unit 50 (see FIG. 1) of the air conditioning apparatus 1 may control the circulation of the refrigerant based on the temperature of the refrigerant measured by the temperature sensors 501, 502 (see FIG. 2).
For example, when the refrigerant temperature measured by the temperature sensor 501 is higher than the refrigerant temperature measured by the temperature sensor 502, the control unit 50 may control the motor-operated valve 16 to decrease the opening degree so as to increase the flow resistance. Also, when the refrigerant temperature measured by the temperature sensor 501 is higher than the refrigerant temperature measured by the temperature sensor 502, the control unit 50 may control the amount of refrigerant sucked by the compressor 13 to increase the flow rate of the refrigerant in the compressor 13. By performing these controls, the enthalpy difference between the refrigerant compressed by the compressor 12 (position 10b in FIG. 2) and the refrigerant compressed by the compressor 13 (position 10i in FIG. 2) is reduced. As a result, the compression ratio in the compressor 13 can be set to a large value.
The positions at which the temperature sensors 501, 502 used for control are provided are not limited to the positions illustrated in FIG. 2 , and it is sufficient that the temperature sensor 501 is provided at a position before the first flow path 101 passes through the heat sink 14 and before the third flow path 103 joins at the junction 20, and the temperature sensor 502 is provided at a position before the first flow path 101 joins at the junction 20.

Second Embodiment
(Refrigerant circuit 10-2)
The air conditioner 1 to which the second embodiment is applied differs from the first embodiment described above in that it includes a refrigerant circuit 10-2 instead of the refrigerant circuit 10 (see FIG. 2).
FIG. 4 is a schematic diagram of a refrigerant circuit 10-2 according to the second embodiment.
As shown in the figure, the refrigerant circuit 10-2 according to the second embodiment differs from the refrigerant circuit 10 according to the first embodiment only in that a radiator 21 is provided in the third flow path 103, and that the junction 20 merges the third flow path 103 at a position after the first flow path 101 has passed through the radiator 14. Therefore, configurations common to the refrigerant circuit 10 and the refrigerant circuit 10-2 are denoted by the same names and symbols, and detailed descriptions thereof will be omitted.

The radiator 21 is provided in the third flow path 103 and is a device that extracts heat from the refrigerant by heat exchange between the refrigerant passing through it and a fluid such as air or water, and radiates the heat. In other words, the radiator 21 removes heat from the refrigerant compressed by the compressor 13 by heat exchange between the refrigerant compressed by the compressor 13 and the fluid.
The radiator 21 may be a heat exchanger similar to the radiator 14. Similarly to the radiator 14, the radiator 21 may also be used as a heater that heats a fluid.
The heat sink 21 is an example of a second heat sink.

In the refrigerant circuit 10-2, the refrigerant, which has passed through the cooler 19 to cool the air, is compressed by the compressor 12 and discharged to the first flow path 101. The refrigerant discharged to the first flow path 101 passes through the radiator 14 to radiate heat, and after the third flow path 103 is joined at the junction 20, the refrigerant branches into the first branch 151 and the second branch 152 at the branching section 15. The refrigerant branched into the first branch 151 is depressurized by the motor-operated valve 16 and flows into the second flow path 102, and exchanges heat with the refrigerant branched into the first branch 151 in the refrigerant-refrigerant heat exchanger 17. Then, the refrigerant is compressed by the compressor 13 and discharged to the third flow path 103, passes through the radiator 21 to radiate heat, and then merges with the first flow path 101 at the junction 20. On the other hand, the refrigerant which branches into the second branch 152 and exchanges heat in the refrigerant-refrigerant heat exchanger 17 is decompressed by the motor-operated valve 18, and then passes through the cooler 19 to cool the air.
By circulating the refrigerant in this manner, the refrigerant circuit 10-2 establishes a refrigeration cycle of the refrigerant.

In the second embodiment using the above-described refrigerant circuit 10-2, as in the first embodiment, the total capacity of the compressors is reduced compared to the case where the conventional refrigerant circuit 10 is used, in which refrigeration capacity is secured by increasing the amount of refrigerant circulating.
In addition, in the refrigerant circuit 10-2, the confluence section 20 merges the third flow path 103 at a position after passing through the radiator 14 in the first flow path 101, so that the heat dissipation from the radiator 14 can be increased compared to when the third flow path 103 is merged at a position before passing through the radiator 14.

Here, in the refrigerant circuit 10-2 according to the second embodiment, it is preferable that the capacity of the compressor 12 is larger than the capacity of the compressor 13. With this configuration, it is possible to increase the heat dissipation from the radiator 14 compared to when the capacity of the compressor 12 is smaller than the capacity of the compressor 13.

Third Embodiment
(Refrigerant circuit 10-3)
The air conditioner 1 to which the third embodiment is applied differs from the first embodiment described above in that it includes a refrigerant circuit 10-3 instead of the refrigerant circuit 10 (see FIG. 2).
FIG. 5 is a schematic diagram of a refrigerant circuit 10-3 according to the third embodiment.
As shown in the figure, the refrigerant circuit 10-3 according to the third embodiment differs from the refrigerant circuit 10-2 according to the second embodiment only in that the refrigerant circuit 10-3 according to the third embodiment includes an electric valve 22 that reduces the pressure of the refrigerant after passing through a radiator 21. Therefore, the same names and symbols are used for components common to the refrigerant circuits 10-2 and 10-3, and detailed descriptions thereof will be omitted.

The motor-operated valve 22 is provided at a position after the radiator 21 in the third flow path 103, and reduces the pressure of the refrigerant passing therethrough.
The motor-operated valve 22 may have a similar configuration to the motor-operated valves 16 and 18 , and the opening degree of the motor-operated valve 22 may be adjusted by the control unit 50 .
The motor-operated valve 22 is an example of a third pressure reducing element.

In the refrigerant circuit 10-3, the refrigerant, which has passed through the cooler 19 to cool the air, is compressed by the compressor 12 and discharged to the first flow path 101. The refrigerant discharged to the first flow path 101 passes through the radiator 14 to radiate heat, and after the third flow path 103 is joined at the junction 20, the refrigerant is branched into the first branch 151 and the second branch 152 at the branching section 15. The refrigerant branched to the first branch 151 is depressurized by the motor-operated valve 16 and flows into the second flow path 102, and exchanges heat with the refrigerant branched to the first branch 151 in the refrigerant-refrigerant heat exchanger 17. Then, the refrigerant is compressed by the compressor 13 and discharged to the third flow path 103, passes through the radiator 21 to radiate heat, and then is further depressurized by the motor-operated valve 22 and merges with the first flow path 101 at the junction 20. On the other hand, the refrigerant which branches into the second branch 152 and exchanges heat in the refrigerant-refrigerant heat exchanger 17 is decompressed by the motor-operated valve 18, and then passes through the cooler 19 to cool the air.
By circulating the refrigerant in this manner, the refrigerant circuit 10-3 establishes a refrigeration cycle of the refrigerant.

In the third embodiment using the above-mentioned refrigerant circuit 10-3, as in the first and second embodiments, the total capacity of the compressors is reduced compared to the case where the conventional refrigerant circuit 10 is used, in which refrigeration capacity is ensured by increasing the amount of refrigerant circulating.
Furthermore, in the refrigerant circuit 10-3, the refrigerant compressed by the compressor 13 is decompressed by the motor-operated valve 22, so that the compression ratio in the compressor 13 can be made larger than in the case where the motor-operated valve 22 is not provided.

<Fourth embodiment>
(Refrigerant circuit 10-4)
The air conditioner 1 to which the fourth embodiment is applied differs from the first embodiment described above in that it includes a refrigerant circuit 10-4 instead of the refrigerant circuit 10 (see FIG. 2).
FIG. 6 is a schematic diagram of a refrigerant circuit 10-4 according to the fourth embodiment.
As shown in the figure, the refrigerant circuit 10-4 according to the fourth embodiment differs from the refrigerant circuit 10-2 according to the second embodiment only in that it includes an electric valve 23 that reduces the pressure of the refrigerant after passing through the radiator 14. Therefore, the same names and symbols are used for components common to the refrigerant circuits 10-2 and 10-4, and detailed descriptions thereof will be omitted.

The motor-operated valve 23 is provided at a position in the first flow path 101 after the first flow path 101 has passed through the radiator 14 and before the first flow path 101 joins with the third flow path 103 at the joining portion 20, and reduces the pressure of the refrigerant passing therethrough.
The motor-operated valve 23 may have a similar configuration to the motor-operated valves 16 , 18 , and 22 , and the opening degree of the motor-operated valve 23 may be adjusted by the control unit 50 .
The motor-operated valve 23 is an example of a fourth pressure reducing element.

In the refrigerant circuit 10-4, the refrigerant, which has passed through the cooler 19 to cool the air, is compressed by the compressor 12 and discharged to the first flow path 101. The refrigerant discharged to the first flow path 101 passes through the radiator 14 to radiate heat, and is depressurized by the motor-operated valve 23. Then, after the third flow path 103 joins at the confluence 20, the refrigerant branches into the first branch 151 and the second branch 152 at the branching section 15. The refrigerant branched into the first branch 151 is depressurized by the motor-operated valve 16 and flows into the second flow path 102, and exchanges heat with the refrigerant branched into the second branch 152 in the refrigerant-refrigerant heat exchanger 17. Then, the refrigerant is compressed by the compressor 13 and discharged to the third flow path 103, passes through the radiator 21 to radiate heat, and then joins the first flow path 101 at the confluence 20. On the other hand, the refrigerant which branches into the second branch 152 and exchanges heat in the refrigerant-refrigerant heat exchanger 17 is decompressed by the motor-operated valve 18, and then passes through the cooler 19 to cool the air.
By circulating the refrigerant in this manner, the refrigerant circuit 10-4 establishes a refrigeration cycle of the refrigerant.

In the fourth embodiment using the above-mentioned refrigerant circuit 10-4, as in the first to third embodiments, the total capacity of the compressors is reduced compared to the case where the conventional refrigerant circuit 10 is used, in which refrigeration capacity is ensured by increasing the amount of refrigerant circulating.
Furthermore, in the refrigerant circuit 10-4, the refrigerant compressed by the compressor 12 is decompressed by the motor-operated valve 23, so that the compression ratio in the compressor 12 can be made larger than in the case where the motor-operated valve 23 is not provided.

<Application Examples>
(Cooling/heating switching)
Incidentally, the air conditioning device 1 may switch between a cooling function that supplies cold air to a space to cool the space, and a heating function that supplies warm air to the space to heat the space. In this case, if a common heat exchanger is used to cool the air in the cooling function and to heat the air in the heating function, it is possible to commonize the supply path for the air used for heat exchange and the ventilation path that supplies the cold air/warm air after heat exchange to the space.
The refrigerant circuit of the application example includes a switching means for switching the cooler 19 (see Figures 2, 4 to 6) in the above-described embodiment between a state in which it functions as a heat exchanger that cools air in the cooling function and a state in which it functions as a heat exchanger that heats air in the heating function.

FIG. 7 is a diagram for explaining a refrigerant circuit 10-5 of an application example.
As shown in the figure, the refrigerant circuit 10-5 of the application example differs from the refrigerant circuit 10 according to the first embodiment only in that it includes a four-way switching valve 60 that switches the connection relationship of the four flow paths. Therefore, the same names and symbols are used for components common to the refrigerant circuit 10 and the refrigerant circuit 10-5, and detailed descriptions thereof will be omitted.

The four-way switching valve 60 is provided to connect a flow path from the cooler 19 to the compressor 12 and a flow path from the junction 20 to the radiator 14. Then, under the control of the control unit 50, the connection relationship of the flow paths is switched between a first state in which the cooler 19 and the compressor 12 are connected and the junction 20 and the radiator 14 are connected, and a second state in which the cooler 19 and the junction 20 are connected and the compressor 12 and the radiator 14 are connected.
The four-way switching valve 60 is an example of a switching means, and switching may be performed using other configurations.

In the refrigerant circuit 10-5 in the first state, the refrigerant circulates in the same manner as in the refrigerant circuit 10 described using Fig. 2, and the air that is the counterpart of the heat exchange in the cooler 19 is cooled. In this way, the cooling function of the air conditioner 1 is realized.
On the other hand, in the refrigerant circuit 10-5 in the second state, the refrigerant circulates in a manner different from that in the first state, and the pressure and specific enthalpy of the refrigerant change in a path opposite to that of the refrigeration cycle 300 described with reference to Fig. 3. More specifically, the refrigerant compressed by the compressors 12 and 13 merges at the merging section 20 and then passes through the cooler 19. Here, the refrigerant passing through the cooler 19 is in a state in which it has been pressurized and heated by the compressors 12 and 13, and is at a sufficiently high temperature relative to the air with which it exchanges heat. Therefore, the air with which it exchanges heat in the cooler 19 is heated by removing heat from the refrigerant. This realizes the heating function of the air-conditioning device 1.

In the example of Figure 7, a switching means is applied to the refrigerant circuit 10 according to the first embodiment, and is shown as an application example refrigerant circuit 10-5. However, a similar switching means can also be applied to the refrigerant circuits 10-2, 10-3, and 10-4 according to the second, third, and fourth embodiments.
In addition, in the air conditioning apparatus 1 of the second, third and fourth embodiments described above, or in application examples in which a switching means is applied, the control unit 50 may control the circulation of the refrigerant based on the temperature of the refrigerant measured by temperature sensors 501, 502 (see Figures 2, 4 to 7).

＜Other＞
In the above embodiment, the refrigeration cycle device is applied to the air conditioner 1, but the scope of application is not limited. The refrigeration cycle device may be applied to various devices that cool objects, such as a freezer, a refrigerator, or an ice maker. As described above with reference to FIG. 2, the refrigeration cycle device may be applied to various devices that heat objects, such as a heater, a water heater, or a water heater, by utilizing heat dissipation from the radiator 14.

Although carbon dioxide refrigerant has been given as an example of the refrigerant circulating through each refrigerant circuit, the type of refrigerant is not limited. A mixed refrigerant in which carbon dioxide is mixed with other components may be used, or a single refrigerant or mixed refrigerant that does not contain carbon dioxide may be used. However, by using a refrigerant that contains carbon dioxide in at least part of its composition, such as the carbon dioxide refrigerant in the above-mentioned embodiment, the heat dissipation in the radiators 14, 21 is greater than when a non-azeotropic mixed refrigerant that does not contain carbon dioxide is used.

Furthermore, the first compression element and the second compression element may be integrated into one device, and the operation for compression in each compression element may be realized by a common motor or the like. However, by making each compression element a separate device as in compressors 12 and 13 in the above-described embodiment, each compression element can be individually controlled according to the state of the refrigerant being sucked in, etc.
Furthermore, a plurality of compressors connected in parallel may be used in place of the compressor 12, and a plurality of compressors connected in parallel may be used in place of the compressor 13. In this case, too, the total capacity can be made smaller than in the case where the refrigerant circulation amount is increased in the conventional refrigerant circuit 10' to ensure refrigeration capacity.

In addition, in the above-described embodiment, motorized valves or solenoid valves are used as pressure reducing elements to enable the control unit 50 to control the opening degree. If control by the control unit 50 is not performed, capillary tubes, orifice plates, etc. may be used for each pressure reducing element.

In addition, in the above-described embodiment, the refrigerant is illustrated as being split into two branches, the first branch 151 and the second branch 152, but it may be split into three or more branches including the first branch 151 and the second branch 152. Correspondingly, a plurality of flow paths including the third flow path 103 may merge into the first flow path 101. Note that when splitting into three or more branches, the branching may occur at a plurality of branching parts including the branching part 15, and the merging may occur at a plurality of merging parts including the merging part 20.

<Additional Notes>
The above-described embodiment can be understood as follows.
The air-conditioning apparatus 1 of the above-described embodiment includes a compressor 12 that compresses the sucked refrigerant and discharges it to a first flow path 101, a radiator 14 that is provided in the first flow path 101 and passes the refrigerant through and radiates heat extracted from the passing refrigerant, a branching section 15 that branches the refrigerant after passing through the radiator 14 in the first flow path 101 into a first branch 151 and a second branch 152, an electric valve 16 that reduces the pressure of the refrigerant branched into the first branch 151 and flows it into the second flow path 102, and a refrigerant-refrigerant heat exchanger 17 that exchanges heat between the refrigerant flowing through the second flow path 102 and the refrigerant branched into the second branch 152. The refrigerant circuits 10, 10-2, 10-3, 10-4, and 10-5 include a refrigerant exchanger 17, an electric valve 18 that reduces the pressure of the refrigerant after heat exchange in the refrigerant-refrigerant heat exchanger 17 in the second branch 152, a cooler 19 that cools the air by heat exchange between the refrigerant after pressure reduction by the electric valve 18 and the air and causes the refrigerant after heat exchange to be drawn into the compressor 12, a compressor 13 that draws in the refrigerant after heat exchange in the refrigerant-refrigerant heat exchanger 17 in the second flow path 102, compresses it, and discharges it into the third flow path 103, and a junction section 20 that merges the third flow path 103 with the first flow path 101. In this case, the total capacity of the compressors 12 and 13 is suppressed compared to an air conditioner equipped with a conventional refrigerant circuit 10' that ensures refrigeration capacity by increasing the amount of refrigerant circulating.

In the refrigerant circuit 10-2 according to the second embodiment, the confluence 15 merges with the third flow path 103 at a position in the first flow path 101 after passing through the radiator 14. The third flow path 103 is also provided with a radiator 21 that radiates heat extracted by passing through the refrigerant compressed by the compressor 13. In this case, the amount of heat dissipated from the radiator 14 can be increased compared to when the confluence 15 merges with the third flow path 103 at a position in the first flow path 101 before passing through the radiator 14.

In addition, in the refrigerant circuit 10-2, the capacity of the compressor 12 is larger than the capacity of the compressor 13. In this case, the heat dissipation from the radiator 14 can be increased compared to when the capacity of the compressor 12 is smaller than the capacity of the compressor 13.

In the refrigerant circuit 10-3 according to the third embodiment, in addition to the configuration of the refrigerant circuit 10-2, a motor-operated valve 22 that reduces the pressure of the refrigerant after passing through the radiator 21 is provided in the third flow path 103. In this case, the compression ratio of the compressor 13 can be set to a large value.

In the refrigerant circuit 10-4 according to the fourth embodiment, in addition to the configuration of the refrigerant circuit 10-2, a motor-operated valve 23 that reduces the pressure of the refrigerant after passing through the radiator 14 is provided at a position in the first flow path 101 after passing through the radiator 14 and before the third flow path 103 joins at the joining section 20. In this case, the compression ratio in the compressor 12 can be set to a large value.

Here, in the air conditioning device 1 of the above-mentioned embodiment, a carbon dioxide refrigerant is used. In this case, the heat dissipation in the radiator 14 is greater than when a non-azeotropic refrigerant that does not contain carbon dioxide is used.

In the air conditioning device 1 of the above-mentioned embodiment, temperature sensors 501, 502 for measuring the temperature of the refrigerant are provided at a position in the first flow path 101 before passing through the radiator 14 and before the third flow path 103 is joined at the junction 15, and at a position in the third flow path 103 before the junction 15 joins the first flow path 101. The control unit 50 of the air conditioning device 1 may control the flow resistance of the motor-operated valve 16 to increase when the temperature of the refrigerant measured by the temperature sensor 501 is higher than the temperature of the refrigerant measured in the third flow path 103. In this case, the enthalpy difference between the refrigerant compressed by the compressor 12 and the refrigerant compressed by the compressor 13 becomes smaller.

Furthermore, in the air conditioning device 1 of the above-described embodiment, the control unit 50 may control the flow rate of the compressor 13 to increase when the temperature of the refrigerant measured in the first flow path 101 is higher than the temperature of the refrigerant measured in the third flow path 103. In this case as well, the enthalpy difference between the refrigerant compressed by the compressor 12 and the refrigerant compressed by the compressor 13 becomes smaller.

Although the embodiment has been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims.
For example, some of the components may be omitted, or other functions may be added to each component. Furthermore, for example, a component included in one example configuration may be replaced with a component included in another example configuration, or a component included in one example configuration may be added to another example configuration.

1...air conditioner, 10, 10-2, 10-3, 10-4, 10-5...refrigerant circuit, 12, 13...compressor, 14, 21...radiator, 15...branching section, 16, 18, 22, 23...motor valve, 17...refrigerant-refrigerant heat exchanger, 19...cooler, 20...junction section, 50...control section, 60...switching circuit, 101...first flow path, 102...second flow path, 103...third flow path, 151...first branch, 152...second branch, 501, 502...temperature sensor

A refrigeration cycle apparatus according to a first aspect includes a first compression element that compresses a drawn refrigerant and discharges it into a first flow path, a radiator that is provided in the first flow path and passes the refrigerant through and radiates heat extracted from the passing refrigerant, a branching section that branches the refrigerant after passing through the radiator in the first flow path into a first branch and a second branch, a first pressure reducing element that reduces the pressure of the refrigerant branched into the first branch and flows it into the second flow path, a heat exchanger that exchanges heat between the refrigerant flowing through the second flow path and the refrigerant branched into the second branch, and a refrigerant after heat exchange by the heat exchanger in the second branch. a second pressure reducing element that reduces pressure, a cooler that cools an object by heat exchange between the refrigerant reduced by the second pressure reducing element and the object and causes the refrigerant after heat exchange to be drawn into the first compression element, a second compression element that draws in the refrigerant after heat exchange in the heat exchanger in the second flow path, compresses it, and discharges it to a third flow path, a junction that merges the third flow path with the first flow path, and a four-way switching valve that connects the flow path from the cooler to the first compression element and the flow path from the junction to the radiator . In this case, the total capacity of the compressor is reduced compared to a case in which the refrigeration capacity is ensured by increasing the amount of refrigerant circulated.
A refrigeration cycle apparatus according to a second aspect is the refrigeration cycle apparatus according to the first aspect, wherein the junction joins the third flow path at a position in the first flow path after the refrigerant has passed through the radiator, and the junction includes a second radiator that is provided in the third flow path and radiates heat extracted by passing the refrigerant compressed by the second compression element through the second radiator. In this case, heat radiation from the radiator can be increased compared to a case in which the junction joins the third flow path at a position in the first flow path before the refrigerant has passed through the radiator.
A refrigeration cycle apparatus according to a third aspect is the refrigeration cycle apparatus according to the second aspect, in which the capacity of the first compression element is larger than the capacity of the second compression element. In this case, heat dissipation from the radiator can be increased compared to a case in which the capacity of the first compression element is smaller than the capacity of the second compression element.
A refrigeration cycle apparatus according to a fourth aspect is the refrigeration cycle apparatus according to the third aspect, further comprising a third pressure reducing element provided in the third flow path and reducing the pressure of the refrigerant after passing through the second radiator. In this case, a compression ratio in the second compression element can be set large.
A refrigeration cycle apparatus according to a fifth aspect is the refrigeration cycle apparatus according to the second aspect, further comprising a fourth pressure reducing element provided in the first flow path after the refrigerant has passed through the radiator and before the merging portion merges with the third flow path, the fourth pressure reducing element reducing the pressure of the refrigerant after the refrigerant has passed through the radiator. In this case, a compression ratio in the first compression element can be set to be large.
A refrigeration cycle apparatus according to a sixth aspect is the refrigeration cycle apparatus according to any one of the first to fifth aspects, in which at least a part of the refrigerant is carbon dioxide. In this case, heat dissipation in the radiator is greater than in the case of using a non-azeotropic refrigerant not containing carbon dioxide.
A seventh aspect of the present invention relates to a refrigeration cycle apparatus including a first temperature sensor provided in the first flow path before passing through the radiator and before merging with the third flow path at the junction, a second temperature sensor provided in the third flow path before merging with the first flow path at the junction, and a control unit that performs control related to circulation of the refrigerant based on temperatures of the refrigerant measured by the first temperature sensor and the second temperature sensor , wherein the control unit controls the flow resistance of the first pressure reducing element to increase when the temperature of the refrigerant measured in the first flow path is higher than the temperature of the refrigerant measured in the third flow path. In this case, an enthalpy difference between the refrigerant compressed by the first compression element and the refrigerant compressed by the second compression element becomes small.
A refrigeration cycle apparatus according to an eighth aspect includes a first temperature sensor provided in the first flow path before passing through the radiator and before the third flow path merges with the first flow path at the junction, a second temperature sensor provided in the third flow path before the third flow path merges with the first flow path at the junction, and a control unit that performs control related to circulation of the refrigerant based on temperatures of the refrigerant measured by the first temperature sensor and the second temperature sensor, wherein the control unit controls the flow rate of the second compression element to increase when the temperature of the refrigerant measured in the first flow path is higher than the temperature of the refrigerant measured in the third flow path. In this case, an enthalpy difference between the refrigerant compressed by the first compression element and the refrigerant compressed by the second compression element becomes small.

Claims (8)

a first compression element that compresses a drawn refrigerant and discharges the refrigerant into a first flow path;
a radiator provided in the first flow path to pass a refrigerant therethrough and radiate heat extracted from the refrigerant passing through the radiator;
a branching portion that branches the refrigerant after passing through the radiator in the first flow path into a first branch and a second branch;
a first pressure reducing element that reduces the pressure of the refrigerant branched into the first branch and causes the refrigerant to flow into a second flow path;
a heat exchanger that performs heat exchange between the refrigerant flowing through the second flow path and the refrigerant branched into the second branch;
a second pressure reducing element that reduces the pressure of the refrigerant after heat exchange by the heat exchanger in the second branch;
a cooler that cools an object by heat exchange between the refrigerant decompressed by the second decompression element and the object, and draws the refrigerant after heat exchange into the first compression element;
a second compression element that draws in the refrigerant that has been heat exchanged by the heat exchanger in the second flow path, compresses the refrigerant, and discharges the refrigerant to a third flow path;
a junction portion that merges the third flow path with the first flow path. The junction portion joins the third flow path at a position in the first flow path after the first flow path has passed through the radiator,
2. The refrigeration cycle apparatus according to claim 1, further comprising a second radiator provided in the third flow path and configured to radiate heat extracted by passing the refrigerant compressed by the second compression element. The refrigeration cycle device according to claim 2, characterized in that the capacity of the first compression element is greater than the capacity of the second compression element. The refrigeration cycle device according to claim 3, further comprising a third pressure reducing element provided in the third flow path to reduce the pressure of the refrigerant after passing through the second radiator. The refrigeration cycle device according to claim 2, further comprising a fourth pressure reducing element that is provided in the first flow path after the refrigerant has passed through the radiator and before the junction where the third flow path joins, and reduces the pressure of the refrigerant after the refrigerant has passed through the radiator. The refrigeration cycle device according to claims 1 to 5, characterized in that at least a portion of the refrigerant composition is carbon dioxide. a temperature sensor for measuring a temperature of the refrigerant at a position in the first flow path before the refrigerant passes through the radiator and before the third flow path merges with the first flow path at the merging portion, and at a position in the third flow path before the third flow path merges with the first flow path at the merging portion;
A control unit that controls the circulation of the refrigerant based on the temperature of the refrigerant measured by the temperature sensor,
2. The refrigeration cycle apparatus according to claim 1, wherein the control unit controls the flow resistance of the first pressure reducing element to increase when a temperature of the refrigerant measured in the first flow path is higher than a temperature of the refrigerant measured in the third flow path. a temperature sensor for measuring a temperature of the refrigerant at a position in the first flow path before the refrigerant passes through the radiator and before the third flow path merges with the first flow path at the merging portion, and at a position in the third flow path before the third flow path merges with the first flow path at the merging portion;
A control unit that controls the circulation of the refrigerant based on the temperature of the refrigerant measured by the temperature sensor,
2. The refrigeration cycle apparatus according to claim 1, wherein the control unit controls a flow rate of the second compression element to increase when a temperature of the refrigerant measured in the first flow path is higher than a temperature of the refrigerant measured in the third flow path.