JP7258212B2 - air conditioner - Google Patents

Description

The present disclosure relates to an air conditioner having a refrigerant circuit in which a non-azeotropic refrigerant mixture circulates.

In order to suppress global warming, the GWP (Global Warming Potential) of refrigerants is regulated by the Montreal Protocol and European F-gas regulations. Refrigerants with a low GWP are often non-azeotropic mixed refrigerants in which a plurality of refrigerants having different boiling points are mixed. The non-azeotropic refrigerant mixture does not have a constant temperature from the start to the end of the evaporation process and the condensation process, and a temperature gradient occurs. The temperature gradient acts to lower the refrigerant temperature on the refrigerant inlet side of the evaporator during the evaporation process. Therefore, in an air conditioner using a non-azeotropic mixed refrigerant, the refrigerant temperature at the refrigerant inlet of the evaporator drops to 0° C. or less, and frost formation or freezing easily occurs.

Conventionally, an air conditioner that suppresses frost formation of a non-azeotropic mixed refrigerant is known (see, for example, Patent Document 1). The air conditioner disclosed in Patent Document 1 is provided with decompression means such as a capillary tube in an intermediate portion of the evaporator in order to increase the saturation temperature on the refrigerant inlet side of the evaporator and suppress frost formation. .

JP-A-60-140048

However, in the air conditioner disclosed in Patent Document 1, the temperature difference between the refrigerant and the air is small in the section from the refrigerant inlet of the evaporator to the decompression means, so the heat exchange performance is deteriorated.

The present disclosure has been made to solve the above-described problems, and provides an air conditioner that suppresses deterioration in heat exchange performance of a heat source side heat exchanger that acts as an evaporator during heating operation. .

An air conditioner according to the present disclosure includes a compressor, a heat source side heat exchanger including a first heat source side heat exchanger and a second heat source side heat exchanger connected in parallel, a load side throttle device, a load side A refrigerant circuit in which a non-azeotropic mixed refrigerant is circulated, and a first refrigerant that divides the refrigerant flowing out of the load-side expansion device during heating operation and distributes it to the heat source-side heat exchanger. a pipe and a second refrigerant pipe; and a first expansion device provided in the first refrigerant pipe for decompressing refrigerant flowing into the first heat source side heat exchanger through the first refrigerant pipe during the heating operation, a second expansion device provided in the second refrigerant pipe for decompressing the refrigerant flowing into the second heat source side heat exchanger through the second refrigerant pipe during the heating operation; 2 a refrigerant heat exchanger that exchanges heat between refrigerant flowing between the expansion device and the second heat source side heat exchanger and refrigerant flowing into the first expansion device during the heating operation, In the first heat source side heat exchanger and the second heat source side heat exchanger, the pressure loss of the refrigerant flowing through the first heat source side heat exchanger is equal to the pressure loss of the refrigerant flowing through the second heat source side heat exchanger. It is a larger configuration than

According to the present disclosure, the pressure of the refrigerant flowing into the first heat source side heat exchanger during heating operation decreases according to the pressure loss in the first heat source side heat exchanger while maintaining a high temperature. In addition, the refrigerant flowing into the second heat source side heat exchanger is overheated in the heat exchanger between refrigerants and its temperature rises. Therefore, a decrease in the refrigerant temperature on the refrigerant inlet side of the heat source side heat exchanger is suppressed. Therefore, it is possible to suppress deterioration in the heat exchange performance of the heat source side heat exchanger that acts as an evaporator during heating operation.

1 is a schematic diagram showing a configuration example of a refrigerant circuit of an air conditioner according to Embodiment 1. FIG. 2 is a hardware configuration diagram showing one configuration example of a control device shown in FIG. 1; FIG. 2 is a hardware configuration diagram showing another configuration example of the control device shown in FIG. 1; FIG. 4 is a ph diagram for explaining the action of the air-conditioning apparatus according to Embodiment 1 during heating operation. FIG. FIG. 2 is a schematic diagram showing an example of a heat transfer tube provided in the first heat source side heat exchanger shown in FIG. 1; FIG. 2 is a schematic diagram showing an example of a heat transfer tube provided in the second heat source side heat exchanger shown in FIG. 1; FIG. 7 is a schematic diagram for comparing the flow channel cross-sectional area of the plurality of heat transfer tubes shown in FIG. 5 and the flow channel cross-sectional area of the heat transfer tube shown in FIG. 6 ; FIG. 7 is a schematic diagram showing one configuration example of a refrigerant circuit of an air conditioner according to Embodiment 2;

An embodiment of an air conditioner of the present disclosure will be described with reference to the drawings. Equivalent configurations are denoted by the same reference numerals in a plurality of drawings, and once described configurations will be omitted or simplified as appropriate in subsequent other embodiments. Further, the shape, size, arrangement, and the like of the configuration shown in each drawing are not limited to those shown in the drawing.

Embodiment 1.
The configuration of the air conditioner of Embodiment 1 will be described.
[Overall Configuration of Air Conditioner]
FIG. 1 is a schematic diagram showing a configuration example of a refrigerant circuit of an air conditioner according to Embodiment 1. FIG. The air conditioner 100 has an outdoor unit 1 that generates a heat source, and indoor units 2 a and 2 b that utilize the heat source generated by the outdoor unit 1 . In Embodiment 1, the refrigerant circulating between the outdoor unit 1 and the indoor units 2a and 2b is a non-azeotropic refrigerant mixture. The air conditioner 100 has a cooling operation mode and a heating operation mode as operation modes of the indoor units 2a and 2b.

The air conditioner 100 includes a liquid main pipe 3, two liquid branch pipes 5a and 5b branching from the liquid main pipe 3, and gas It has a main pipe 4 and two gas branch pipes 6 a and 6 b branching from the main gas pipe 4 . The outdoor unit 1 and the indoor unit 2a are connected by a liquid main pipe 3 and a liquid branch pipe 5a, and a gas main pipe 4 and a gas branch pipe 6a. The outdoor unit 1 and the indoor unit 2b are connected by a liquid main pipe 3 and a liquid branch pipe 5b, and a gas main pipe 4 and a gas branch pipe 6b.

[Outdoor unit]
The configuration of the outdoor unit 1 shown in FIG. 1 will be described. The outdoor unit 1 is installed, for example, outside of a room. The outdoor unit 1 functions as a heat source unit that discharges or supplies heat for air conditioning. The outdoor unit 1 includes a compressor 10 , a flow path switching device 11 , a heat source side heat exchanger 12 , an accumulator 13 , a heat source side fan 17 and a control device 30 . The outdoor unit 1 also has a first expansion device 16, a second expansion device 15, a heat exchanger between refrigerants 14, and a first refrigerant pipe 18a and a second refrigerant pipe 18b. The heat source side heat exchanger 12 has a first heat source side heat exchanger 12a and a second heat source side heat exchanger 12b that are connected in parallel. Compressor 10, flow path switching device 11, heat source side fan 17, first expansion device 16, and second expansion device 15 are each connected to control device 30 via a signal line (not shown).

The first refrigerant pipe 18 a and the second refrigerant pipe 18 b divide the refrigerant flowing into the heat source side heat exchanger 12 . The first refrigerant pipe 18a distributes part of the refrigerant flowing into the heat source side heat exchanger 12 to the first heat source side heat exchanger 12a. The second refrigerant pipe 18b circulates the rest of the refrigerant flowing into the heat source side heat exchanger 12 to the second heat source side heat exchanger 12b.

The first expansion device 16 is provided in the first refrigerant pipe 18a. The second expansion device 15 is provided in the second refrigerant pipe 18b. The heat exchanger between refrigerants 14 is provided in the middle of both the first refrigerant pipe 18a and the second refrigerant pipe 18b. A flow path to which the first heat source side heat exchanger 12a, the first expansion device 16, and the refrigerant heat exchanger 14 are connected via the first refrigerant pipe 18a, and a second heat source side heat via the second refrigerant pipe 18b The flow path to which the exchanger 12b, the heat exchanger between refrigerants 14 and the second expansion device 15 are connected is connected in parallel.

The compressor 10 sucks in low-temperature and low-pressure refrigerant, compresses the sucked refrigerant, and discharges it in a high-temperature and high-pressure state. The compressor 10 is, for example, an inverter compressor whose capacity can be controlled. The heat source side fan 17 supplies outside air to the heat source side heat exchanger 12 . The heat source side fan 17 is, for example, a propeller fan. The number of heat source side fans 17 is not limited to one, and may be plural. The accumulator 13 is connected to the refrigerant suction port side of the compressor 10 . The accumulator 13 prevents liquid refrigerant from flowing into the compressor 10 .

The flow switching device 11 switches the flow direction of the refrigerant circulating through the refrigerant circuits 50a and 50b in correspondence with the heating operation mode and the cooling operation mode. The flow path switching device 11 distributes the refrigerant discharged from the compressor 10 to the load-side heat exchangers 21a and 21b in the heating operation mode, and distributes the refrigerant discharged from the compressor 10 to the heat source-side heat exchangers 21a and 21b in the cooling operation mode. Circulate to the exchanger 12 . The channel switching device 11 is, for example, a four-way valve.

The first heat source side heat exchanger 12a and the second heat source side heat exchanger 12b exchange heat between the air supplied by the heat source side fan 17 and the refrigerant. The first heat source side heat exchanger 12a and the second heat source side heat exchanger 12b function as condensers or gas coolers in the cooling operation mode, and function as evaporators in the heating operation mode. In the configuration example shown in FIG. 1, the second heat source side heat exchanger 12b is arranged on the windward side of the first heat source side heat exchanger 12a.

In the heating operation mode, the first heat source side heat exchanger 12a is configured to generate pressure loss of the refrigerant according to the temperature gradient of the non-azeotropic refrigerant mixture in order to suppress frost formation. The first heat source side heat exchanger 12a is configured to have, for example, a smaller flow passage cross-sectional area for the refrigerant than the second heat source side heat exchanger 12b so as to generate a large pressure loss of the refrigerant. In addition, the first heat source side heat exchanger 12a may have a longer flow path length of the heat transfer tube than the second heat source side heat exchanger 12b.

The first throttle device 16 and the second throttle device 15 are expansion valves whose opening can be controlled. The first throttle device 16 and the second throttle device 15 are, for example, electronic expansion valves. In the heating operation mode, the first expansion device 16 reduces the pressure of the refrigerant flowing from the indoor units 2a and 2b into the first heat source side heat exchanger 12a through the first refrigerant pipe 18a. In the heating operation mode, the second expansion device 15 reduces the pressure of the refrigerant flowing from the indoor units 2a and 2b into the second heat source side heat exchanger 12b via the second refrigerant pipe 18b. The first expansion device 16 and the second expansion device 15 are fully opened in the cooling operation mode.

The heat exchanger between refrigerants 14 includes a refrigerant that flows between the second expansion device 15 and the second heat source side heat exchanger 12b in the second refrigerant pipe 18b, and a refrigerant that flows into the first expansion device 16 during heating operation. heat exchange. The refrigerant-to-refrigerant heat exchanger 14 is, for example, a double-tube heat exchanger, a plate heat exchanger, or a shell-and-tube heat exchanger. The configuration of the control device 30 will be described after the configuration of the indoor units 2a and 2b.

[Indoor unit]
The configuration of the indoor units 2a and 2b shown in FIG. 1 will be described. Each of the indoor units 2a and 2b is installed inside a room, for example. The indoor unit 2a supplies conditioned air to the room in which it is installed. The indoor unit 2b supplies conditioned air to the room in which it is installed. The indoor unit 2a has a load side expansion device 20a, a load side heat exchanger 21a, a load side fan 22a, and a room temperature sensor 23a. The indoor unit 2b has a load side expansion device 20b, a load side heat exchanger 21b, a load side fan 22b, and a room temperature sensor 23b. A refrigerant leakage detector (not shown) may be provided in the indoor units 2a and 2b.

Load-side expansion devices 20a and 20b, load-side fans 22a and 22b, and room temperature sensors 23a and 23b are each connected to control device 30 via signal lines (not shown). The room temperature sensor 23 a detects the room temperature of the room in which the indoor unit 2 a is installed, and outputs the detected room temperature data to the control device 30 . The room temperature sensor 23 b detects the room temperature of the room in which the indoor unit 2 b is installed, and outputs data of the detected room temperature to the control device 30 .

The load-side fan 22a sucks air from the room in which the indoor unit 2a is installed, and supplies the sucked-in air to the load-side heat exchanger 21a. The load-side fan 22b sucks air from the room in which the indoor unit 2b is installed, and supplies the sucked-in air to the load-side heat exchanger 21b. The load-side fans 22a and 22b are, for example, cross-flow fans.

The load-side expansion devices 20a and 20b function as pressure reducing valves or expansion valves that reduce the pressure of the refrigerant to expand it. The load-side throttle devices 20a and 20b are, for example, electronic expansion valves that can change the degree of opening. The load-side throttle device 20a is positioned upstream of the load-side heat exchanger 21a in the refrigerant flow direction when the indoor unit 2a operates in the cooling operation mode. The load-side throttle device 20b is positioned upstream of the load-side heat exchanger 21b in the refrigerant flow direction when the indoor unit 2b operates in the cooling operation mode.

The load side heat exchanger 21a is connected to the flow path switching device 11 of the outdoor unit 1 via the gas branch pipe 6a and the gas main pipe 4, and via the load side expansion device 20a, the liquid branch pipe 5a and the liquid main pipe 3, It is connected to the first refrigerant pipe 18 a and the second refrigerant pipe 18 b of the outdoor unit 1 . The load side heat exchanger 21b is connected to the flow path switching device 11 of the outdoor unit 1 via the gas branch pipe 6b and the gas main pipe 4, and via the load side expansion device 20b, the liquid branch pipe 5b and the liquid main pipe 3, It is connected to the first refrigerant pipe 18 a and the second refrigerant pipe 18 b of the outdoor unit 1 .

The load-side heat exchangers 21a and 21b function as evaporators in the cooling operation mode, and function as condensers in the heating operation mode. The load-side heat exchanger 21a exchanges heat between the air supplied by the load-side fan 22a and the refrigerant to generate heating air or cooling air to be supplied indoors. The load-side heat exchanger 21b exchanges heat between the air supplied by the load-side fan 22b and the refrigerant to generate heating air or cooling air to be supplied indoors.

The compressor 10, the heat source side heat exchanger 12, the load side expansion device 20a and the load side heat exchanger 21a are connected by refrigerant piping to form a refrigerant circuit 50a in which the refrigerant circulates. The compressor 10, the heat source side heat exchanger 12, the load side throttle device 20b, and the load side heat exchanger 21b are connected by refrigerant piping to form a refrigerant circuit 50b in which the refrigerant circulates. In Embodiment 1, each of refrigerant circuits 50a and 50b includes first expansion device 16, second expansion device 15 and refrigerant heat exchanger 14, as shown in FIG.

Although FIG. 1 shows a configuration in which two indoor units 2a and 2b are connected in parallel to the outdoor unit 1, the number of indoor units connected to the outdoor unit 1 may be one. It may be more than one. Moreover, FIG. 1 shows a case where the load side expansion device 20a is provided in the indoor unit 2a and the load side expansion device 20b is provided in the indoor unit 2b. If the first expansion device 16 and the second expansion device 15 serve as the load side expansion devices 20a and 20b, the indoor units 2a and 2b do not need to be provided with expansion devices. When there is only one indoor unit, the expansion device may be provided in the outdoor unit without providing the expansion device in the indoor unit. Further, although FIG. 1 shows a configuration in which the outdoor unit 1 is provided with the flow path switching device 11, a configuration in which the flow path switching device 11 is not provided, such as a dedicated heating machine, may be employed. . Furthermore, the sensors provided in the air conditioner 100 are not limited to the room temperature sensors 23a and 23b, and sensors not shown in the drawing may be provided.

Next, the configuration of the control device 30 shown in FIG. 1 will be described. The control device 30 controls the entire air conditioner 100 . Control device 30 controls the refrigerating cycle of the refrigerant circulating in each of refrigerant circuits 50a and 50b based on the detection values of various sensors such as room temperature sensors 23a and 23b and set temperature Tset.

A user of the indoor unit 2a inputs an operation mode and a set temperature Tset1 to the controller 30 via a remote controller (not shown). A user of the indoor unit 2b inputs an operation mode and a set temperature Tset2 to the controller 30 via a remote controller (not shown). In Embodiment 1, it is assumed that the operation mode selected by the user of the indoor unit 2a and the operation mode selected by the user of the indoor unit 2b are the same.

The control device 30 controls the flow switching device 11 so that the flow direction of the refrigerant flowing through the refrigerant circuits 50a and 50b is switched according to the operation mode selected by the user of the indoor units 2a and 2b. Specifically, when the operation mode is the heating operation mode, the control device 30 controls the flow switching device 11 so that the refrigerant discharged from the compressor 10 flows through the load-side heat exchangers 21a and 21b. When the operation mode is the cooling operation mode, the control device 30 controls the flow path switching device 11 so that the refrigerant discharged from the compressor 10 flows through the heat source side heat exchanger 12 .

When the operation mode is the cooling operation mode, the control device 30 controls the opening degrees of the first expansion device 16 and the second expansion device 15 to be fully open. In the cooling operation mode, the controller 30 controls each of the indoor units 2a and 2b as follows. The control device 30 adjusts the drive rotation speed of the compressor 10, the rotation speed of the heat source side fan 17, the rotation speed of the load side fan 22a, and the load side throttle device 20a so that the detection value of the room temperature sensor 23a matches the set temperature Tset1. to control the opening of the The control device 30 adjusts the drive rotation speed of the compressor 10, the rotation speed of the heat source side fan 17, the rotation speed of the load side fan 22b, and the load side throttle device 20b so that the detection value of the room temperature sensor 23b matches the set temperature Tset2. to control the opening of the

When the operation mode is the heating operation mode, the control device 30 sets the pressure reduction to a minimum so as not to interfere with the heat exchange performed in the refrigerant heat exchanger 14 for the purpose of adjusting the flow rates of the load-side heat exchangers 21a and 21b. The opening degrees of the load side expansion devices 20a and 20b are controlled so that For example, the control device 30 fully opens the load-side expansion devices 20a and 20b. In addition, in the heating operation mode, the controller 30 controls each of the indoor units 2a and 2b as follows. The control device 30 adjusts the drive rotation speed of the compressor 10, the rotation speed of the heat source side fan 17, the rotation speed of the load side fan 22a, the rotation speed of the load side fan 22a, and the first The opening degrees of the diaphragm device 16 and the second diaphragm device 15 are controlled. The control device 30 adjusts the driving rotation speed of the compressor 10, the rotation speed of the heat source side fan 17, the rotation speed of the load side fan 22b, the rotation speed of the load side fan 22b, and the first The opening degrees of the diaphragm device 16 and the second diaphragm device 15 are controlled.

Furthermore, in the heating operation mode, the control device 30 controls the opening degree ratio Rv of the first expansion device 16 and the second expansion device 15 to adjust the flow rate of the refrigerant flowing through the first heat source side heat exchanger 12a, You may control the pressure loss of the refrigerant|coolant in the 1st heat source side heat exchanger 12a. The control device 30 controls the pressure loss of the first heat source side heat exchanger 12 a in accordance with the cooling and heating loads of the air conditioner 100 . For example, in the heating operation mode, the control device 30 opens the first heat source side heat exchanger 12a so that the pressure loss of the first heat source side heat exchanger 12a is small in the case of low load operation where there is no concern about frost formation or operation at a high outside air temperature. control the power ratio Rv. In the heating operation mode, the control device 30 adjusts the opening ratio so that the pressure loss of the first heat source side heat exchanger 12a increases in the case of high-load operation where frost formation is likely to occur or operation at a low outside air temperature. Control Rv.

As the opening degree ratio Rv, the opening degree ratio Rvl in the case of low load operation or operation at a high outside temperature where there is no concern about frost formation, and the opening ratio Rvl in the case of high load operation or operation at a low outside temperature where there is a great concern about frost formation. The opening degree ratio Rvh may be determined in advance. In addition, a refrigerant temperature sensor (not shown) is provided on the refrigerant outlet side of the first heat source side heat exchanger 12a in the heating operation mode, and the controller 30 controls the detection value of the refrigerant temperature sensor to reach a predetermined target temperature Temp. The opening degree ratio Rv may be controlled such that

The control device 30 is composed of, for example, an analog circuit, a digital circuit, or a circuit combining these circuits. The control device 30 is configured by hardware such as circuit devices that implement various functions. Further, the control device 30 may have a configuration in which various functions are realized by an arithmetic device such as a microcomputer executing software.

An example of hardware of the control device 30 shown in FIG. 1 will be described. FIG. 2 is a hardware configuration diagram showing one configuration example of the control device shown in FIG. When the functions of controller 30 are implemented in hardware, controller 30 is configured with processing circuitry 80, as shown in FIG.

When the functions of the controller 30 are implemented in hardware, the processing circuit 80 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field -Programmable Gate Array), or a combination thereof.

Another configuration example of the hardware of the control device 30 shown in FIG. 1 will be described. FIG. 3 is a hardware configuration diagram showing another configuration example of the control device shown in FIG. When the functions of the control device 30 are executed by software, the control device 30 shown in FIG. 1 includes a processor 81 such as a CPU (Central Processing Unit) and a memory 82 as shown in FIG. Functions of control device 30 are implemented by processor 81 and memory 82 . FIG. 3 shows that processor 81 and memory 82 are communicatively connected to each other.

When the functions of the control device 30 are executed by software, the functions of the control device 30 are realized by software, firmware, or a combination of software and firmware. Software and firmware are written as programs and stored in memory 82 . The processor 81 realizes the functions of the control device 30 by reading and executing the programs stored in the memory 82 . The memory 82 may store the opening ratios Rvh and Rvl and the target temperature Temp.

As the memory 82, for example, non-volatile semiconductor memories such as ROM (Read Only Memory), flash memory, EPROM (Erasable and Programmable ROM) and EEPROM (Electrically Erasable and Programmable ROM) are used. As the memory 82, a volatile semiconductor memory of RAM (Random Access Memory) may be used. Furthermore, as the memory 82, removable recording media such as magnetic disks, flexible disks, optical disks, CDs (Compact Discs), MDs (Mini Discs) and DVDs (Digital Versatile Discs) may be used.

Although FIG. 1 illustrates the case where the control device 30 is provided in the outdoor unit 1, the control device may be provided in each of the outdoor unit 1 and the indoor units 2a and 2b. It may be provided in at least one of the indoor units 2a and 2b. When the air conditioning apparatus 100 is provided with a plurality of control devices, the plurality of control devices are connected for communication with each other and perform the functions of the control device 30 described above.

[Operation mode of air conditioner]
Next, each operation mode executed by the air conditioner 100 will be described. The air conditioner 100 performs cooling operation and heating operation of the indoor units 2a and 2b based on instructions input by the user via a remote controller (not shown) for each of the indoor units 2a and 2b. As described above, the operation modes executed by the air-conditioning apparatus 100 of FIG. There is a heating operation mode that performs The refrigerant flow in each operation mode will be described below.

[Cooling operation mode]
The refrigerant flow in the cooling operation mode will be described with reference to FIG. In FIG. 1, the direction of flow of the refrigerant flowing through the refrigerant circuits 50a and 50b in the cooling operation mode is indicated by dashed arrows.

Compressor 10 draws in low temperature and low pressure refrigerant, compresses the drawn refrigerant, and discharges high temperature and high pressure refrigerant. The high-temperature and high-pressure refrigerant discharged from the compressor 10 passes through the flow switching device 11 and is divided into the first heat source side heat exchanger 12a and the second heat source side heat exchanger 12b. The refrigerant that has flowed into the second heat source side heat exchanger 12b and the first heat source side heat exchanger 12a exchanges heat with the outside air supplied by the heat source side fan 17 and condenses. The refrigerant condensed in the first heat source side heat exchanger 12a and the second heat source side heat exchanger 12b flows out of the outdoor unit 1, passes through the liquid main pipe 3 and the liquid branch pipes 5a and 5b, and flows into the indoor unit 2a. and 2b. At this time, the first expansion device 16 and the second expansion device 15 are fully opened so as not to block the flow of the refrigerant.

The refrigerant that has flowed into the indoor unit 2a is expanded by the load side expansion device 20a. The refrigerant expanded by the load-side expansion device 20a flows into the load-side heat exchanger 21a acting as an evaporator, absorbs heat from the room air, and evaporates. In the load-side heat exchanger 21a, the refrigerant absorbs heat from the room air, thereby cooling the room air. Further, the refrigerant that has flowed into the indoor unit 2b is expanded by the load side expansion device 20b. The refrigerant expanded by the load-side expansion device 20b flows into the load-side heat exchanger 21b acting as an evaporator, absorbs heat from indoor air, and evaporates. In the load-side heat exchanger 21b, the refrigerant absorbs heat from the indoor air, thereby cooling the indoor air. The refrigerant that has flowed out of the load-side heat exchangers 21 a and 21 b returns to the outdoor unit 1 via the gas branch pipes 6 a and 6 b and the gas main pipe 4 . The refrigerant that has flowed into the outdoor unit 1 is sucked into the compressor 10 via the flow switching device 11 and compressed again.

From the viewpoint of refrigerant saving, the refrigerant may be expanded by the first expansion device 16 and the second expansion device 15 instead of the load side expansion devices 20a and 20b. In this case, the refrigerant occupying the liquid main pipe 3 can be reduced.

[Heating operation mode]
The refrigerant flow in the heating operation mode will be described with reference to FIG. In FIG. 1 , solid arrows indicate the flow direction of the refrigerant flowing through the refrigerant circuits 50a and 50b in the heating operation mode.

Compressor 10 draws in low temperature and low pressure refrigerant, compresses the drawn refrigerant, and discharges high temperature and high pressure refrigerant. The high-temperature and high-pressure refrigerant discharged from the compressor 10 flows out of the outdoor unit 1 via the flow switching device 11 . The high-temperature and high-pressure refrigerant flowing out of the outdoor unit 1 is branched to the load-side heat exchangers 21a and 21b via the main gas pipe 4 and the gas branch pipes 6a and 6b.

The refrigerant that has flowed into the load-side heat exchanger 21a is condensed while heating the indoor space by radiating heat to the indoor air in the load-side heat exchanger 21a. The refrigerant condensed in the load side heat exchanger 21a is slightly expanded in the load side expansion device 20a. In addition, the refrigerant that has flowed into the load-side heat exchanger 21b is condensed while heating the indoor space by radiating heat to the indoor air in the load-side heat exchanger 21b. The refrigerant condensed in the load side heat exchanger 21b is slightly expanded in the load side expansion device 20b. The refrigerant flowing out of the load side expansion devices 20 a and 20 b returns to the outdoor unit 1 via the liquid branch pipes 5 a and 5 b and the liquid main pipe 3 .

Here, the load-side expansion devices 20a and 20b function as flow rate regulators of the load-side heat exchangers 21a and 21b, but are set so that the pressure reduction is minimized. The refrigerant that has flowed into the outdoor unit 1 is divided into the first refrigerant pipe 18a and the second refrigerant pipe 18b.

The refrigerant that has flowed into the second refrigerant pipe 18b is expanded to a low pressure by the second expansion device 15 and then partially evaporated in the heat exchanger 14 between refrigerants. The refrigerant that has flowed out of the heat exchanger related to refrigerant 14 flows into the second heat source side heat exchanger 12b. On the other hand, the refrigerant that has flowed into the first refrigerant pipe 18a is supercooled in the heat exchanger between refrigerants 14 in a high-pressure state, expanded to a low pressure in the first expansion device 16, and then passed through the first heat source side heat exchanger. 12a. The refrigerant evaporated in the second heat source side heat exchanger 12b and the first heat source side heat exchanger 12a passes through the flow path switching device 11, is sucked into the compressor 10, and is compressed again.

The operation of the air-conditioning apparatus 100 of Embodiment 1 in the heating operation mode will be described. FIG. 4 is a ph diagram for explaining the action during heating operation of the air conditioner according to Embodiment 1. FIG. The horizontal axis of FIG. 4 is the specific enthalpy h, and the vertical axis is the pressure p.

In FIG. 4, the inclined dashed line in the wet steam region indicates the isotherm of the non-azeotropic refrigerant mixture. The non-azeotrope refrigerant isotherm shows that there is a temperature gradient. The relationship among temperatures T1, T2 and T3 shown in FIG. 4 is T1>T2>T3. T2>0°C. Also, the relationship between the pressures p1 and p2 is p2>p1. A stroke K1 indicates a process in which the refrigerant flowing through the second expansion device 15 is decompressed and expanded. A stroke K2 indicates a process in which the refrigerant flowing through the first expansion device 16 is decompressed and expanded.

As shown in FIG. 4, the refrigerant flowing into the second refrigerant pipe 18b is decompressed to the pressure p1 by the second expansion device 15, and then part of the refrigerant evaporates in the heat exchanger 14 between refrigerants shown in section RR. and overheat. The refrigerant that has flowed out of the heat exchanger related to refrigerant 14 flows into the second heat source side heat exchanger 12b while maintaining the pressure p1. The temperature of the refrigerant is higher than the temperature T2 when flowing into the second heat source side heat exchanger 12b. That is, the temperature of the refrigerant is higher than 0°C at the refrigerant inlet of the second heat source side heat exchanger 12b.

On the other hand, the refrigerant that has flowed into the first refrigerant pipe 18a is supercooled in the heat exchanger between refrigerants 14 shown in section RR while maintaining a high pressure state. After that, the refrigerant that has flowed out of the heat exchanger related to refrigerant 14 is depressurized to the pressure p2 in the first expansion device 16, and then flows into the first heat source side heat exchanger 12a. When the refrigerant flows into the first heat source side heat exchanger 12a, the refrigerant has a temperature T1 higher than the temperature T2. The pressure p of the refrigerant flowing through the first heat source side heat exchanger 12a gradually decreases due to the pressure loss in the first heat source side heat exchanger 12a. The change in the pressure p at this time corresponds to the temperature gradient of the isotherm of the temperature T1 of the non-azeotropic refrigerant mixture. The refrigerant flowing through the first heat source side heat exchanger 12a flows through the first heat source side heat exchanger 12a while maintaining the temperature T1 from the refrigerant inlet to the refrigerant outlet of the first heat source side heat exchanger 12a. It drops to pressure p1.

In this manner, in the heating operation mode, the pressure of the refrigerant flowing into the first heat source side heat exchanger 12a is lowered according to the pressure loss in the first heat source side heat exchanger 12a while maintaining a high temperature. In addition, the refrigerant flowing into the second heat source side heat exchanger is overheated in the heat exchanger between refrigerants and its temperature rises. Therefore, a decrease in the refrigerant temperature on the refrigerant inlet side of the heat source side heat exchanger 12 is suppressed. As a result, it is possible to prevent frost formation and freezing, and to suppress deterioration in the heat exchange performance of the heat source side heat exchanger that acts as an evaporator during heating operation.

As shown in FIG. 4, the pressure loss of the refrigerant generated in the first heat source side heat exchanger 12a is desirably set to a magnitude that follows the isothermal line in the evaporation process of the non-azeotropic refrigerant mixture. The pressure change of the refrigerant due to the pressure loss does not have to completely match the isotherm in the evaporation process of the non-azeotropic refrigerant mixture. Moreover, it is desirable that the pressure loss of the refrigerant generated in the second heat source side heat exchanger 12b be as small as possible in order to increase the temperature difference between the refrigerant and the air and improve the heat exchange performance. Therefore, the pressure loss of the first heat source side heat exchanger 12a is configured to be larger than the pressure loss of the second heat source side heat exchanger 12b.

As a configuration for making the pressure loss of the first heat source side heat exchanger 12a larger than the pressure loss of the second heat source side heat exchanger 12b, by reducing the diameter of the cross section of the heat transfer tube, the cross-sectional area of the refrigerant flow path can be reduced. For example, the channel cross-sectional area of the first heat source side heat exchanger 12a is made smaller than the channel cross-sectional area of the second heat source side heat exchanger 12b. By reducing the flow passage cross-sectional area of the first heat source side heat exchanger 12a, the pressure loss of the first heat source side heat exchanger 12a increases.

Further, when a plurality of heat transfer tubes are provided in parallel in each of the heat exchangers of the first heat source side heat exchanger 12a and the second heat source side heat exchanger 12b, the number of heat transfer tubes of the first heat source side heat exchanger 12a is The number of heat transfer tubes of the second heat source side heat exchanger 12b is reduced. With this configuration, the total cross-sectional area of the heat transfer tubes of the first heat source side heat exchanger 12a is smaller than that of the second heat source side heat exchanger 12b. A flat tube is an example of a case in which a plurality of heat transfer tubes are provided in parallel.

Further, as a configuration for making the pressure loss of the first heat source side heat exchanger 12a larger than the pressure loss of the second heat source side heat exchanger 12b, the heat transfer area of the first heat source side heat exchanger 12a is set to that of the second heat source. It is conceivable to make it larger than the heat transfer area of the side heat exchanger 12b. By increasing the heat transfer area of the first heat source side heat exchanger 12a, the heat exchange amount of the first heat source side heat exchanger 12a is increased. By increasing the refrigerant flow rate on the side of the first heat source side heat exchanger 12a, which exchanges a large amount of heat, the pressure loss of the first heat source side heat exchanger 12a increases. For example, by making the flow path length of the heat transfer tubes of the first heat source side heat exchanger 12a longer than the flow path length of the heat transfer tubes of the second heat source side heat exchanger 12b, the heat transfer of the first heat source side heat exchanger 12a The heat area becomes larger than the heat transfer area of the second heat source side heat exchanger 12b. In this case, the pressure loss of the first heat source side heat exchanger 12a becomes larger than the pressure loss of the second heat source side heat exchanger 12b.

Further, the flow passage cross-sectional area of the first heat source side heat exchanger 12a may be configured to increase from the refrigerant inlet side toward the refrigerant outlet side in the heating operation mode. With this configuration, in the heating operation mode, as the refrigerant evaporates, the dryness of the refrigerant increases on the downstream side, preventing excessive pressure loss and maintaining a constant pressure loss along the direction of refrigerant flow. be able to. Moreover, in the cooling operation mode, there is an effect of suppressing a decrease in the heat transfer coefficient due to a decrease in the cross-sectional area of the flow path on the downstream side of the refrigerant as the refrigerant condenses.

Further, the first heat source side heat exchanger 12a and the second heat source side heat exchanger 12b may be arranged side by side in the vertical direction, one heat exchanger being arranged on the windward side and the other heat exchanger being arranged on the leeward side. can be placed in As shown in FIG. 1, when the first heat source side heat exchanger 12a is arranged on the leeward side and the second heat source side heat exchanger 12b is arranged on the windward side, an improvement in the effect of suppressing frost formation is expected. can. Specifically, the second heat source side heat exchanger 12b is more likely to frost than the first heat source side heat exchanger 12a because the refrigerant temperature at the refrigerant inlet is low due to the temperature gradient. By arranging the second heat source side heat exchanger 12b on the windward side where the air temperature is high, the surface temperature of the pipe is increased, the resistance to frost formation is improved, and frost formation is suppressed.

Further, the control device 30 controls the opening degree ratio Rv of the first expansion device 16 and the second expansion device 15, thereby adjusting the flow rate of the refrigerant flowing through the first heat source side heat exchanger 12a, You may control the pressure loss of the refrigerant|coolant of the exchanger 12a. For example, the control device 30 sets the opening degree ratio Rvl in the case of low load operation or operation at a high outside temperature where there is no concern about frost formation, and may be set to different values from the opening degree ratio Rvh of .

Here, a configuration example of the heat transfer tubes provided in the heat source side heat exchanger 12 shown in FIG. 1 will be described. 5 is a schematic diagram showing an example of a heat transfer tube provided in the first heat source side heat exchanger shown in FIG. 1. FIG. FIG. 5 shows a case where the heat transfer tubes provided in the first heat source side heat exchanger 12a are flat tubes 61 in which a plurality of heat transfer tubes 61a are arranged parallel to the flow path. FIG. 5 shows a case where the flat tube 61 has seven heat transfer tubes 61a. FIG. 5 shows the cross-sectional shape of the flat tube 61, where D is the diameter of each heat transfer tube 61a. The plurality of heat transfer tubes 61a extend in a direction perpendicular to the surface of the plate-like heat radiation fins 71 (the Y-axis arrow direction).

Assuming that the channel cross-sectional area of the flat tube 61 shown in FIG. 5 is SA1, the channel cross-sectional area SA1 is represented by the sum of the cross-sectional areas of the seven heat transfer tubes 61a. That is, SA1=7×π×(D/2) ² =(7/4) ^πD2 . Assuming that the heat transfer area of the flat tube 61 shown in FIG. ×D)×L=7πDL.

6 is a schematic diagram showing an example of a heat transfer tube provided in the second heat source side heat exchanger shown in FIG. 1. FIG. FIG. 6 shows a case where the heat transfer tube 62 provided in the second heat source side heat exchanger 12b is a single circular tube. FIG. 6 shows the cross-sectional shape of the heat transfer tube 62, and the diameter of the heat transfer tube 62 is 3×D. That is, the diameter of the heat transfer tube 62 is three times the diameter of the heat transfer tube 61a shown in FIG. The heat transfer tube 62 extends in a direction perpendicular to the plane of the plate-like heat radiation fins 72 (in the direction of the Y-axis arrow).

Assuming that the flow channel ^cross -sectional area of the heat ^transfer tube 62 shown in FIG. be. Assuming that the heat transfer area of the heat transfer tube 62 shown in FIG. =3πDL.

FIG. 7 is a schematic diagram for comparing the flow channel cross-sectional areas of the plurality of heat transfer tubes shown in FIG. 5 and the flow channel cross-sectional areas of the heat transfer tubes shown in FIG. In order to facilitate comparison between the cross-sectional area of the seven heat transfer tubes 61a shown in FIG. 5 and the cross-sectional area of the heat transfer tubes 62 shown in FIG. The seven bundled heat transfer tubes 61a are overlapped with the heat transfer tubes 62 and displayed.

Referring to FIG. 7, it can be seen that the channel cross-sectional area of the seven heat transfer tubes 61 a is smaller than the channel cross-sectional area of the heat transfer tube 62 . It is clear that the relationship SA1<SA2 is established even when the two formulas SA1=(7/4) ^.pi.D2 and ^SA2 =(9/4).pi.D2 are compared. The channel cross-sectional area of the flat tube 61 shown in FIG. 5 is smaller than the channel cross-sectional area of the heat transfer tube 62 shown in FIG.

Next, the heat transfer area of the seven heat transfer tubes 61a shown in FIG. 5 and the heat transfer area of the heat transfer tube 62 shown in FIG. 6 are compared. The heat transfer area HTA1 of the seven heat transfer tubes 61a is HTA1=7πDL, and the heat transfer area HTA2 of the heat transfer tube 62 is HTA2=3πDL. Therefore, the relationship is HTA1>HTA2. The heat transfer area of the flat tube 61 shown in FIG. 5 is larger than the heat transfer area of the heat transfer tube 62 shown in FIG.

For convenience of explanation, the radiation fins 71 shown in FIG. 5 are part of the actual radiation fins cut along the periphery of the flat tube 61, and FIG. 5 does not show the overall shape of the radiation fins 71. . The radiation fins 72 shown in FIG. 6 also do not show the overall shape of the radiation fins 72, like the radiation fins 71 shown in FIG. Furthermore, although FIG. 5 shows a case where the number of heat transfer tubes 61a is seven, the number of heat transfer tubes 61a used for the flat tubes 61 is not limited to seven.

In the air conditioner 100 of Embodiment 1, the compressor 10, the heat source side heat exchanger 12, the load side expansion devices 20a and 20b, and the load side heat exchangers 21a and 21b are connected by piping. It has refrigerant circuits 50a and 50b in which an azeotropic mixture refrigerant circulates. The heat source side heat exchanger 12 has a first heat source side heat exchanger 12a and a second heat source side heat exchanger 12b that are connected in parallel. The air conditioner 100 includes a first refrigerant pipe 18a and a second refrigerant pipe 18b that divide the refrigerant flowing out of the load-side expansion devices 20a and 20b during heating operation and distribute the refrigerant to the heat source-side heat exchanger 12, and the first expansion device. 16 , a second expansion device 15 and a heat exchanger between refrigerants 14 . The first expansion device 16 reduces the pressure of the refrigerant flowing into the first heat source side heat exchanger 12a through the first refrigerant pipe 18a during heating operation. The second expansion device 15 reduces the pressure of the refrigerant flowing into the second heat source side heat exchanger 12b through the second refrigerant pipe 18b during heating operation. The heat exchanger between refrigerants 14 includes a refrigerant that flows between the second expansion device 15 and the second heat source side heat exchanger 12b in the second refrigerant pipe 18b, and a refrigerant that flows into the first expansion device 16 during heating operation. heat exchange. In the first heat source side heat exchanger 12a and the second heat source side heat exchanger 12b, the pressure loss of the refrigerant flowing through the first heat source side heat exchanger 12a is equal to the pressure loss of the refrigerant flowing through the second heat source side heat exchanger 12b. It is a larger configuration than

According to the first embodiment, in the heating operation mode, the refrigerant flowing into the first heat source side heat exchanger 12a maintains a high temperature, and the pressure increases according to the pressure loss in the first heat source side heat exchanger 12a. decreases. Further, the refrigerant flowing into the second heat source side heat exchanger 12b is overheated in the heat exchanger between refrigerants 14 and the temperature thereof rises. Therefore, a decrease in the refrigerant temperature on the refrigerant inlet side of the heat source side heat exchanger 12 is suppressed. As a result, during heating operation, it is possible to prevent the heat source side heat exchanger 12 from frosting and freezing, and to suppress deterioration of the heat exchange performance of the heat source side heat exchanger 12 acting as an evaporator.

Embodiment 2.
The air conditioner of Embodiment 2 effectively utilizes the heat exchanger between refrigerants 14 shown in FIG. 1 in the cooling operation mode. In the second embodiment, the same reference numerals are assigned to the configurations described in the first embodiment, and detailed description thereof will be omitted. Also, in the second embodiment, differences from the configuration described in the first embodiment will be described in detail, and descriptions of the same configurations will be omitted.

The configuration of the air conditioner of Embodiment 2 will be described. FIG. 8 is a schematic diagram showing a configuration example of a refrigerant circuit of an air conditioner according to Embodiment 2. FIG. The air conditioner 101 shown in FIG. 8 differs from the air conditioner 100 shown in FIG. 1 in the configuration of the outdoor unit. The outdoor unit 1a of the air conditioner 101 has, in addition to the configuration of the outdoor unit 1 shown in FIG. It has a pipe 44 .

The first on-off valve 41 is provided in the first refrigerant pipe 18a. Specifically, the first on-off valve 41 includes a confluence point MP between the first refrigerant pipe 18a, the second refrigerant pipe 18b, and the pipes connected to the load-side expansion devices 20a and 20b, and the heat exchanger between refrigerants. 14. The third refrigerant pipe 19 is arranged between the first heat source side heat exchanger 12a and the first expansion device 16 in the first refrigerant pipe 18a, and between the second heat source side heat exchanger 12b and the refrigerant in the second refrigerant pipe 18b. between the devices 14; The second on-off valve 42 is provided in the third refrigerant pipe 19 . The injection pipe 44 branches from between the refrigerant heat exchanger 14 and the first on-off valve 41 and is connected to the suction side of the compressor 10 . The third on-off valve 43 is provided in the injection pipe 44 .

The first on-off valve 41, the second on-off valve 42 and the third on-off valve 43 are, for example, electromagnetic valves. Each of the first on-off valve 41, the second on-off valve 42 and the third on-off valve 43 is connected to the controller 30 via a signal line (not shown). When the operation mode of the indoor units 2a and 2b is the heating operation mode, the control device 30 opens the first on-off valve 41 and closes the second and third on-off valves 42 and 43 . When the operation mode of the indoor units 2a and 2b is the cooling operation mode, the control device 30 closes the first opening/closing valve 41 and opens the second opening/closing valve 42 and the third opening/closing valve 43 .

The operation of the air conditioner 101 of Embodiment 2 will be described. In FIG. 8 , solid line arrows indicate the flow direction of the refrigerant flowing through the refrigerant circuits 50a and 50b in the heating operation mode, and dashed line arrows indicate the flow direction of the refrigerant flowing through the refrigerant circuits 50a and 50b in the cooling operation mode. showing.

In the heating operation mode, the first on-off valve 41 is open, and the second and third on-off valves 42 and 43 are closed. Since the refrigerant flow in the heating operation mode is the same as that described in the first embodiment, detailed description thereof will be omitted in the second embodiment.

In Embodiment 2, the flow of refrigerant in the cooling operation mode will be described with reference to FIG. In the cooling operation mode, the first on-off valve 41 is closed, and the second and third on-off valves 42 and 43 are open.

Refrigerant flowing out of the compressor 10 passes through the flow switching device 11 and is branched to the first refrigerant pipe 18a and the second refrigerant pipe 18b. The refrigerant flowing into the second refrigerant pipe 18b flows into the heat exchanger between refrigerants 14 after being condensed in the second heat source side heat exchanger 12b. After the refrigerant that has flowed into the first refrigerant pipe 18a is condensed in the first heat source side heat exchanger 12a, a portion of the refrigerant flows into the first expansion device 16, and the remaining refrigerant remains in a high pressure state, and the third refrigerant It flows into the pipe 19 . Since the second on-off valve 42 is open, the refrigerant flowing from the first refrigerant pipe 18a into the third refrigerant pipe 19 joins the refrigerant flowing through the second heat source side heat exchanger 12b and passes through the second refrigerant pipe 18b. Then, it flows into the heat exchanger between refrigerants 14 and is condensed. On the other hand, the refrigerant that has flowed into the first expansion device 16 from the first heat source side heat exchanger 12 a flows into the heat exchanger between refrigerants 14 after being decompressed in the first expansion device 16 .

Here, as indicated by the dashed arrow in FIG. When the flow rate is large, the refrigerant flowing direction of the second on-off valve 42 may be reversed.

Since the first on-off valve 41 is closed and the third on-off valve 43 is open, the refrigerant that has flowed through the first expansion device 16 flows through the injection pipe 44 into the suction side of the compressor 10. . Thus, the refrigerant flowing through the first expansion device 16 does not flow into the refrigerant pipes flowing toward the indoor units 2a and 2b. Therefore, there is an effect of reducing the pressure loss in the refrigerant pipes flowing from the outdoor unit 1 to the indoor units 2a and 2b.

Further, in the cooling operation mode of the second embodiment, the opening degree of the first expansion device 16 may be increased. By making the refrigerant outlet of the heat exchanger between refrigerants 14 wet, the wet refrigerant flows into the compressor 10 and the discharge temperature can be reduced.

In the second embodiment, in the cooling operation mode, the intermediate-pressure refrigerant flows into the suction side of the compressor 10, thereby preventing the temperature of the refrigerant discharged from the compressor 10 from becoming too high. In addition, since the intermediate-pressure refrigerant does not flow into the refrigerant pipes that flow to the indoor units 2a and 2b, it is possible to suppress reduction in pressure loss. Therefore, the refrigerant heat exchanger 14 can be effectively used even in the cooling operation mode.

1, 1a outdoor unit 2a, 2b indoor unit 3 liquid main pipe 4 gas main pipe 5a, 5b liquid branch pipe 6a, 6b gas branch pipe 10 compressor 11 flow path switching device 12 heat source side heat exchanger , 12a first heat source side heat exchanger, 12b second heat source side heat exchanger, 13 accumulator, 14 heat exchanger between refrigerants, 15 second expansion device, 16 first expansion device, 17 heat source side fan, 18a first refrigerant Piping 18b Second refrigerant pipe 19 Third refrigerant pipe 20a, 20b Load side expansion device 21a, 21b Load side heat exchanger 22a, 22b Load side fan 23a, 23b Room temperature sensor 30 Control device 41 Third 1 on-off valve, 42 second on-off valve, 43 third on-off valve, 44 injection piping, 50a, 50b refrigerant circuit, 61 flat tube, 61a heat transfer tube, 62 heat transfer tube, 71, 72 radiation fins, 80 processing circuit, 81 processor , 82 memory, 100, 101 air conditioner.

Claims (9)

A compressor, a heat source side heat exchanger including a first heat source side heat exchanger and a second heat source side heat exchanger connected in parallel, a load side throttle device, and the load side heat exchanger are connected by piping. , a refrigerant circuit in which a non-azeotropic mixture refrigerant circulates;
a first refrigerant pipe and a second refrigerant pipe that divide the refrigerant flowing out of the load-side expansion device during heating operation and distribute the refrigerant to the heat source-side heat exchanger;
a first expansion device provided in the first refrigerant pipe for decompressing refrigerant flowing into the first heat source side heat exchanger through the first refrigerant pipe during the heating operation;
a second expansion device provided in the second refrigerant pipe for decompressing refrigerant flowing into the second heat source side heat exchanger through the second refrigerant pipe during the heating operation;
Inter-refrigerant heat exchange between the refrigerant flowing between the second expansion device and the second heat source side heat exchanger in the second refrigerant pipe and the refrigerant flowing into the first expansion device during the heating operation an exchanger;
In the first heat source side heat exchanger and the second heat source side heat exchanger, the pressure loss of the refrigerant flowing through the first heat source side heat exchanger is equal to the pressure loss of the refrigerant flowing through the second heat source side heat exchanger. is a configuration that is greater than
Air conditioner. The heat transfer area of the first heat source side heat exchanger is larger than the heat transfer area of the second heat source side heat exchanger,
The air conditioner according to claim 1. The flow path length of the heat transfer tubes of the first heat source side heat exchanger is longer than the flow path length of the heat transfer tubes of the second heat source side heat exchanger,
The air conditioner according to claim 2. The flow channel cross-sectional area of the first heat source side heat exchanger is smaller than the flow channel cross-sectional area of the second heat source side heat exchanger,
The air conditioner according to any one of claims 1 to 3. The first heat source side heat exchanger has a configuration in which the cross-sectional area of the flow passage increases as it approaches the outlet side where the refrigerant flows out from the inlet side where the refrigerant flows during the heating operation.
The air conditioner according to claim 1. The second heat source side heat exchanger is arranged on the windward side of the first heat source side heat exchanger,
The air conditioner according to any one of claims 1 to 5. further comprising a control device for controlling an opening degree ratio of the first throttle device and the second throttle device;
The control device is
controlling the opening degree ratio so that the pressure loss of the refrigerant flowing through the first heat source side heat exchanger is greater than the pressure loss of the refrigerant flowing through the second heat source side heat exchanger;
The air conditioner according to any one of claims 2-6. During the heating, the pressure change of the refrigerant flowing through the first heat source side heat exchanger corresponds to the temperature gradient of the non-azeotropic refrigerant mixture,
The air conditioner according to any one of claims 1 to 7. a flow path switching device that circulates the refrigerant discharged from the compressor during the heating operation to the load side heat exchanger, and circulates the refrigerant discharged from the compressor during the cooling operation to the heat source side heat exchanger;
a first on-off valve provided in the first refrigerant pipe between a confluence point of the first refrigerant pipe and a pipe connected to the load side expansion device and the heat exchanger between refrigerants;
The first refrigerant pipe connects between the first heat source side heat exchanger and the first expansion device, and the second refrigerant pipe connects between the second heat source side heat exchanger and the heat exchanger between refrigerants. a third refrigerant pipe to
a second on-off valve provided in the third refrigerant pipe;
an injection pipe branched from between the refrigerant heat exchanger and the first on-off valve and connected to the suction side of the compressor;
a third on-off valve provided in the injection pipe,
During the cooling operation, the first on-off valve is closed, and the second on-off valve and the third on-off valve are open.
The air conditioner according to any one of claims 1 to 8.

Images