WO2014083650A1 - Air conditioning device - Google Patents

Abstract

A heat source heat exchanger (12) has: fins (61, 62) which are arranged with gaps therebetween so that air passes through the gaps; and heat transfer pipes (64, 65) which penetrate through the fins (61, 62), and through the inside of which a refrigerant flows. Heat source heat exchangers (12a, 12b) are arranged adjacent to each other in such a manner that the fins (61, 62) face the same direction. Heat leakage reduction mechanisms which reduce the amount of heat leakage between the adjacent heat source heat exchangers (12a, 12b) are provided between the adjacent fins (61, 62).

Description

Air conditioner

The present invention relates to an air conditioner.

Conventionally, in an air conditioner such as a multi air conditioning system for buildings, for example, an outdoor unit (outdoor unit) that is a heat source unit arranged outside a building is connected to an indoor unit (indoor unit) arranged inside the building by pipe connection. The refrigerant circuit is configured to circulate the refrigerant. And heating or cooling of the air-conditioning target space is performed by heating and cooling the air using the heat radiation and heat absorption of the refrigerant.

During the heating operation of such a multi air conditioning system for buildings, the heat exchanger of the outdoor unit serves as an evaporator, and the low-temperature refrigerant and air exchange heat, so that moisture in the air is transferred to the fins and heat transfer tubes of the heat exchanger. It condenses and frosts on the heat exchanger.
As described above, when the heat exchanger is frosted, the air path of the heat exchanger is blocked, and the heat transfer area of the heat exchanger that exchanges heat with air is reduced, which causes a problem of insufficient heating capacity. Therefore, the defrosting operation is performed by stopping the heating operation, switching the refrigerant flow switching valve, and using the heat exchanger of the outdoor unit as a condenser. Such a defrosting operation can prevent a decrease in heating capacity. However, since the indoor heating operation is also stopped during the defrosting operation, the indoor temperature is lowered and the comfort of the indoor environment is impaired.

In the prior art, in order to solve such problems, a plurality of outdoor heat exchangers are provided, and bypass piping is provided so that the discharge gas of the compressor can be bypassed to each heat exchanger via an on-off valve. There are technologies that simultaneously perform a defrosting operation and a heating operation by dividing the plurality of heat exchangers into an evaporator and a condenser (for example, Patent Document 1 and Patent Document 2).

WO2010 / 082325 (FIGS. 7, 8, etc.) US2010 / 0170270 (FIG. 2 etc.)

The air conditioning apparatus described in Patent Literature 1 and Patent Literature 2 uses a plurality of outdoor heat exchangers, and simultaneously performs heating operation with an evaporator and defrosting operation with a condenser. However, the positional relationship of each heat exchanger is not clarified. For example, when the evaporator and the condenser are arranged next to each other (for example, arranged one above the other) and the heat exchangers constituting each are connected continuously via fins, At the boundary, heat leakage from the condenser to the evaporator occurs through the connected fins.
Due to the occurrence of heat leakage, the defrosting ability of the condenser decreases near the boundary between the evaporator and the condenser, and defrosting near the boundary becomes insufficient. For this reason, the time required for defrosting becomes long, the indoor heating capability during defrosting operation falls, and the comfort of indoor environment is impaired. Furthermore, water droplets generated after defrosting freeze, generating root ice, reducing the heat transfer area of the heat exchanger, reducing the heating capacity, and impairing the comfort of the indoor environment.

Also, in order to prevent residual frost and root ice, even if the defrosting operation time is set longer, the frosting amount of the heat exchanger operating as an evaporator increases during the defrosting operation. For this reason, the heat transfer area of the heat exchanger operating as an evaporator is reduced, the heating capacity is reduced, and the comfort of the indoor environment is impaired.

The present invention has been made to solve the above-described problem, and provides an air conditioner that can suppress heat leakage through fins between a plurality of heat exchangers arranged adjacent to each other. For the purpose.

In the air conditioner according to the present invention, a compressor, a load-side heat exchanger, a load-side expansion device, and a plurality of heat source-side heat exchangers connected in parallel to each other are sequentially connected by piping so that the refrigerant circulates. A main circuit, a bypass pipe that branches a part of the refrigerant discharged from the compressor, and flows into the heat source side heat exchanger to be defrosted among the plurality of heat source side heat exchangers, and a flow of the bypass pipe A connection for switching the heat source side heat exchanger to be defrosted by switching passage or blocking of the path and passage or blocking of the flow path of the pipe of the main circuit connected to the plurality of heat source side heat exchangers The heat source side heat exchanger includes a plurality of fins arranged at intervals so as to allow air to pass therethrough, and a plurality of heat transfer tubes inserted into the plurality of fins and through which the refrigerant flows. And the plurality of heat source side heat exchangers Heat leakage that is arranged adjacent to each other so that the plurality of fins face the same direction, and reduces the amount of heat leakage between the adjacent heat source side heat exchangers between the plurality of adjacent fins A reduction mechanism is provided.

The present invention can suppress heat leakage through fins between a plurality of heat source side heat exchangers arranged adjacent to each other. Therefore, even when a part of the plurality of heat source side heat exchangers is defrosted and the other part is operated for heating, residual frost and roots at the boundary part of the plurality of adjacent heat source side heat exchangers. Generation of ice can be suppressed. Therefore, it is possible to provide an air conditioner that shortens the defrosting time, suppresses a decrease in heating capacity, and ensures the comfort of the indoor environment.

It is a schematic circuit block diagram which shows an example of a circuit structure of the air conditioning apparatus 100 which concerns on Embodiment 1 of this invention. It is a schematic structure figure which shows an example of the outdoor unit installation state of the heat source side heat exchanger of the air conditioning apparatus 100 which concerns on Embodiment 1 of this invention. It is a refrigerant circuit diagram which shows the flow of the refrigerant | coolant at the time of the cooling only operation mode of the air conditioning apparatus 100 which concerns on Embodiment 1 of this invention. It is a refrigerant circuit diagram which shows the flow of the refrigerant | coolant at the time of the heating only operation mode of the air conditioning apparatus 100 which concerns on Embodiment 1 of this invention. It is a refrigerant circuit diagram which shows the flow of the refrigerant | coolant at the time of implementing the defrost of the heat source side heat exchanger 12b at the time of the defrost operation mode of the air conditioning apparatus 100 which concerns on Embodiment 1 of this invention. It is a refrigerant circuit diagram which shows the flow of the refrigerant | coolant at the time of implementing the defrost of the heat source side heat exchanger 12a at the time of the defrost operation mode of the air conditioning apparatus 100 which concerns on Embodiment 1 of this invention. It is a schematic structure figure showing an example at the time of dividing without sharing a fin of a heat source side heat exchanger of air harmony device 100 concerning Embodiment 1 of the present invention. It is a schematic structure figure which shows an example at the time of dividing | segmenting without sharing the fin of the heat source side heat exchanger of the air conditioning apparatus 100 which concerns on Embodiment 1 of this invention, and providing the notch. It is a schematic structure figure showing an example at the time of sharing a part of fin of a heat source side heat exchanger, and providing a notch of air harmony device 100 concerning Embodiment 1 of the present invention. It is a schematic structure figure showing an example at the time of sharing a part of fin of a heat source side heat exchanger, and providing a slit of air harmony device 100 concerning Embodiment 1 of the present invention. It is a schematic structure figure which shows an example at the time of dividing | segmenting without sharing the fin of the heat source side heat exchanger of the air conditioning apparatus 100 which concerns on Embodiment 1 of this invention, and providing the elliptical notch. It is a schematic structure figure which shows an example at the time of sharing a part of fin and providing two notches of the air conditioning apparatus 100 which concerns on Embodiment 1 of this invention. It is a schematic structure figure which shows an example of the outdoor unit installation state at the time of providing the clearance gap between the upper and lower sides of the heat source side heat exchanger of the air conditioning apparatus 100 which concerns on Embodiment 1 of this invention. It is a comparison figure of the heat transfer area ratio of the air conditioning apparatus 100 which concerns on Embodiment 1 of this invention, and COP which is one of the parameter | indexes showing the magnitude | size of the performance of an air conditioning apparatus. It is a schematic circuit block diagram which shows an example of a circuit structure of the air conditioning apparatus 200 which concerns on Embodiment 2 of this invention. It is a schematic circuit block diagram which shows an example of a circuit structure at the time of changing one of the 3rd opening / closing devices 32 to the expansion device which can change an opening degree of the air conditioning apparatus 200 which concerns on Embodiment 2 of this invention. It is a schematic circuit block diagram which shows an example of a circuit structure at the time of installing only the 3rd switching device 32 which can change an opening degree of the air conditioning apparatus 200 which concerns on Embodiment 2 of this invention. It is a schematic circuit block diagram which shows an example of the circuit structure which can implement the pressure adjustment in the heat source side heat exchanger 12 used as the condenser of the air conditioning apparatus 200 which concerns on Embodiment 2 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a schematic circuit configuration diagram showing an example of a circuit configuration of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.
Based on FIG. 1, the detailed structure of the air conditioning apparatus 100 is demonstrated.
As shown in FIG. 1, the air conditioner 100 includes an outdoor unit 1 and an indoor unit 2, and the outdoor unit 1 and the indoor unit 2 are connected by a refrigerant main pipe 4.
The air conditioning apparatus 100 circulates refrigerant and performs air conditioning using a refrigeration cycle. The air-conditioning apparatus 100 has a cooling only operation mode in which all the indoor units 2 to be operated are cooled, a heating only operation mode in which all the indoor units 2 to be heated are heated, or the indoor unit 2 is continuing the heating operation. A defrosting operation mode for defrosting the heat exchanger in the outdoor unit 1 can be selected.

[Outdoor unit 1]
The outdoor unit 1 includes a compressor 10, a refrigerant flow switching device 11, such as a four-way valve, a heat source side heat exchanger 12a, a heat source side heat exchanger 12b, an accumulator 13, a refrigerant pipe 3, and a hot gas bypass pipe 5. Mounted.
The compressor 10, the refrigerant flow switching device 11 such as a four-way valve, the heat source side heat exchanger 12 a, the heat source side heat exchanger 12 b, and the accumulator 13 are connected by a refrigerant pipe 3.
The heat source side heat exchanger 12a and the heat source side heat exchanger 12b are connected to each other in parallel by the refrigerant pipe 3. Second opening / closing devices 31a and 31b are provided in the refrigerant pipe 3 on the load side expansion device 22 side of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b.

The hot gas bypass pipe 5 branches a part of the high-temperature refrigerant discharged from the compressor 10 and flows into the heat source side heat exchanger 12 to be defrosted among the heat source side heat exchanger 12a and the heat source side heat exchanger 12b. Let
That is, as shown in FIG. 1, one end of the hot gas bypass pipe 5 is connected to the refrigerant pipe 3 between the discharge unit of the compressor 10 and the refrigerant flow switching device 11.
Further, the other end of the hot gas bypass pipe 5 is branched into two branches, one being connected to the refrigerant pipe 3 between the heat source side heat exchanger 12a and the second switchgear 31a, and the other being the heat source side heat exchanger. It connects to the refrigerant | coolant piping 3 between 12b and the 2nd switchgear 31b.
The hot gas bypass pipe 5 connected to the heat source side heat exchanger 12a is provided with a first opening / closing device 30a. The hot gas bypass pipe 5 connected to the heat source side heat exchanger 12b is provided with a first opening / closing device 30b.

In the first embodiment, the first opening / closing device 30a, the first opening / closing device 30b, the second opening / closing device 31a, and the second opening / closing device 31b constitute the “connection switching device” of the present invention.

The compressor 10 sucks the refrigerant and compresses the refrigerant to a high temperature / high pressure state. The compressor 10 is configured by, for example, an inverter compressor capable of capacity control.
The refrigerant flow switching device 11 switches the refrigerant flow in the heating only operation mode and the refrigerant flow in the cooling only operation mode.

Both the heat source side heat exchanger 12a and the heat source side heat exchanger 12b function as an evaporator during the heating only operation mode and function as a condenser during the cooling only operation mode. Further, during the defrosting operation, one of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b functions as an evaporator and the other functions as a condenser.

FIG. 2 is a schematic structural diagram showing an example of an outdoor unit installation state of the heat source side heat exchanger in the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.
As shown in FIG. 2, the heat source side heat exchanger 12 a and the heat source side heat exchanger 12 b are arranged in the casing 51 of the outdoor unit 1. The heat source side heat exchanger 12a and the heat source side heat exchanger 12b include a plurality of fins arranged at intervals so that air passes, a plurality of heat transfer tubes inserted into the plurality of fins and through which the refrigerant flows, have. The heat source side heat exchanger 12a and the heat source side heat exchanger 12b exchange heat between air supplied from a blower such as the fan 52 and the refrigerant.

The heat source side heat exchanger 12a and the heat source side heat exchanger 12b are arranged adjacent to each other such that the plurality of fins face the same direction. For example, as shown in FIG. 2, the heat source side heat exchanger 12a is disposed on the upper side, and the heat source side heat exchanger 12b is disposed on the lower side. The heat source side heat exchanger 12a and the heat source side heat exchanger 12b are respectively arranged adjacent to each other in the step direction of the heat transfer tubes. That is, the heat source side heat exchanger 12a and the heat source side heat exchanger 12b are arranged in the vertical direction such that the fins face the same direction.
A heat leakage reduction mechanism that reduces the amount of heat leakage between the adjacent heat source side heat exchangers 12a and 12b is provided between the adjacent fins. Details will be described later.

Referring back to FIG.

The accumulator 13 is provided on the suction side of the compressor 10 and stores excess refrigerant due to a difference in operation state between the heating only operation mode and the cooling only operation mode, and excess refrigerant with respect to a transient change in operation. .

When the heat source side heat exchanger 12a operates as a condenser during the defrosting operation mode, the first opening / closing device 30a allows a high-temperature refrigerant to flow into the heat source side heat exchanger 12a from the hot gas bypass pipe 5. Open / close valve. When the heat source side heat exchanger 12b operates as a condenser during the defrosting operation mode, the first switchgear 30b allows a high-temperature refrigerant to flow from the hot gas bypass pipe 5 into the heat source side heat exchanger 12b. Open / close valve. The first opening / closing devices 30a and 30b are constituted by a device capable of opening and closing a refrigerant flow path, such as a two-way valve, a solenoid valve, or an electronic expansion valve.

When the heat source side heat exchanger 12a operates as a condenser during the defrosting operation mode, the second opening / closing device 31a is a low-temperature two-phase flow that flows into the outdoor unit 1 from the indoor unit 2 through the refrigerant main pipe 4. This is an on-off valve for blocking the refrigerant flow path so that the refrigerant does not flow into the heat source side heat exchanger 12a. When the heat source side heat exchanger 12b operates as a condenser during the defrosting operation mode, the second opening / closing device 31b is a low-temperature two-phase flow that flows into the outdoor unit 1 from the indoor unit 2 through the refrigerant main pipe 4. This is an on-off valve for blocking the refrigerant flow path so that the refrigerant does not flow into the heat source side heat exchanger 12b. The second opening / closing devices 31a and 31b are constituted by a device capable of opening and closing a refrigerant flow path, such as a two-way valve, a solenoid valve, or an electronic expansion valve.

The outdoor unit 1 is provided with a first pressure sensor 41 and a second pressure sensor 42 as pressure detection means.
The first pressure sensor 41 is provided in a pipe between the compressor 10 and the refrigerant flow switching device 11. The first pressure sensor 41 detects the pressure of the high-temperature and high-pressure refrigerant discharged from the compressor 10.
The second pressure sensor 42 is provided in a pipe between the refrigerant flow switching device 11 and the accumulator 13. The second pressure sensor 42 detects the pressure of the low-pressure refrigerant sucked into the compressor 10.

The outdoor unit 1 is provided with a first temperature sensor 43, a second temperature sensor 45, a third temperature sensor 48a, and a third temperature sensor 48b as temperature detection means. The first temperature sensor 43, the second temperature sensor 45, the third temperature sensor 48a, and the third temperature sensor 48b are composed of, for example, a thermistor.
The first temperature sensor 43 is provided in a pipe between the compressor 10 and the refrigerant flow switching device 11. The first temperature sensor 43 measures the temperature of the refrigerant discharged from the compressor 10.
The 2nd temperature sensor 45 is provided in the air suction part of either the heat source side heat exchanger 12a or the heat source side heat exchanger 12b. The second temperature sensor 45 measures the air temperature around the outdoor unit 1.
The third temperature sensor 48 a is provided in a pipe between the heat source side heat exchanger 12 a and the refrigerant flow switching device 11.
The third temperature sensor 48a measures the temperature of the refrigerant flowing out from the heat source side heat exchanger 12a operating as an evaporator.
The third temperature sensor 48 b is provided in a pipe between the heat source side heat exchanger 12 b and the refrigerant flow switching device 11. The third temperature sensor 48b measures the temperature of the refrigerant flowing out from the heat source side heat exchanger 12b operating as an evaporator.

[Indoor unit 2]
The indoor unit 2 is equipped with a load side heat exchanger 21 and a load side expansion device 22.
The load-side heat exchanger 21 is connected to the outdoor unit 1 through the refrigerant main pipe 4 and refrigerant flows in or out. The load side heat exchanger 21 performs heat exchange between air supplied from a blower such as a fan and a refrigerant, for example. The load-side heat exchanger 21 generates heating air or cooling air to be supplied to the indoor space.
The load side throttle device 22 functions as a pressure reducing valve and an expansion valve, and decompresses the refrigerant to expand it. The load side expansion device 22 is provided on the upstream side of the load side heat exchanger 21 in the refrigerant flow during the cooling only operation mode. The load side throttle device 22 is configured by a valve whose opening degree can be variably controlled. The load side throttle device 22 is composed of, for example, an electronic expansion valve.

The indoor unit 2 is provided with a fourth temperature sensor 46, a fifth temperature sensor 47, and a sixth temperature sensor 44 as temperature detecting means. The 4th temperature sensor 46, the 5th temperature sensor 47, and the 6th temperature sensor 44 comprise a thermistor etc., for example.
The fourth temperature sensor 46 is provided in a pipe between the load side expansion device 22 and the load side heat exchanger 21. The fourth temperature sensor 46 detects the temperature of the refrigerant flowing into the load side heat exchanger 21 or the refrigerant flowing out of the load side heat exchanger.
The fifth temperature sensor 47 is provided in a pipe between the load side heat exchanger 21 and the refrigerant flow switching device 11 of the outdoor unit 1. The fifth temperature sensor 47 detects the temperature of the refrigerant flowing into the load side heat exchanger 21 or the refrigerant flowing out of the load side heat exchanger 21.
The sixth temperature sensor 44 is provided in the air suction portion of the load side heat exchanger 21. The sixth temperature sensor 44 detects the ambient air temperature in the room.

With the above configuration, the air conditioner 100 includes the compressor 10, the refrigerant flow switching device 11, the load side heat exchanger 21, the load side expansion device 22, and the heat source side heat exchanger 12a connected in parallel to each other. 12b are sequentially connected by piping to form a main circuit through which the refrigerant circulates. Further, a part of the refrigerant discharged from the compressor 10 is branched to form a bypass circuit that flows into the heat source side heat exchanger 12 to be defrosted among the heat source side heat exchangers 12a and 12b.

In the configuration example of the first embodiment, as shown in FIG. 1, the case where one indoor unit 2 is connected to the outdoor unit 1 through the refrigerant main pipe 4 is shown as an example. The present invention is not limited to this configuration. A plurality of indoor units 2 may be provided, and the plurality of indoor units 2 may be connected to the outdoor unit 1 in parallel.

The control device 50 is constituted by a microcomputer, and the air conditioning apparatus 100 has a control device 50 constituted by a microcomputer. The control device 50 switches the driving frequency of the compressor 10, the rotational speed of the blower (including ON / OFF), the switching of the refrigerant flow switching device 11, the first, based on detection information from various detection means and instructions from the remote controller. Control of opening / closing of the opening / closing devices 30a, 30b, opening / closing of the second opening / closing device 31, opening degree of the load side expansion device 22, and the like, and each operation mode described later is executed. The control device 50 may be provided for each unit, or may be provided in the outdoor unit 1 or the indoor unit 2.

Next, each operation mode executed by the air conditioner 100 will be described.
Below, each operation mode is demonstrated with the flow of a refrigerant | coolant.

[Cooling operation mode]
FIG. 3 is a refrigerant circuit diagram illustrating the refrigerant flow in the cooling only operation mode of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.
In FIG. 3, the cooling only operation mode will be described by taking as an example a case where a cooling load is generated in the load-side heat exchanger 21. In FIG. 3, the flow direction of the refrigerant is indicated by solid arrows.

In the cooling only operation mode, the refrigerant flow switching device 11 is switched to the state shown by the solid line in FIG. Both the first opening / closing device 30a and the first opening / closing device 30b are switched to the closed state and block the refrigerant. Both the second opening / closing device 31a and the second opening / closing device 31b are switched to the open state and allow the refrigerant to pass therethrough.

When the compressor 10 is driven, the low-temperature and low-pressure refrigerant is compressed and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12a and the heat source side heat exchanger 12b via the refrigerant flow switching device 11.
The high-temperature and high-pressure gas refrigerant that has flowed into the heat-source-side heat exchanger 12a and the heat-source-side heat exchanger 12b is radiated to the outdoor air in each of the heat-source-side heat exchanger 12a and the heat-source-side heat exchanger 12b, and is a high-pressure liquid refrigerant. It becomes. The high-pressure liquid refrigerant that has flowed out of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b merges through the second opening / closing device 31a and the second opening / closing device 31b, respectively, and flows out of the outdoor unit 1.

The high-pressure liquid refrigerant that has flowed out of the outdoor unit 1 flows into the indoor unit 2 through the refrigerant main pipe 4 and is expanded by the load side expansion device 22 to become a low-temperature / low-pressure two-phase refrigerant. The two-phase refrigerant flows into the load-side heat exchanger 21 that operates as an evaporator and absorbs heat from the room air, thereby cooling the room air and becoming a low-temperature and low-pressure gas refrigerant.
The gas refrigerant that has flowed out of the load-side heat exchanger 21 flows into the outdoor unit 1 again through the refrigerant main pipe 4. The refrigerant flowing into the outdoor unit 1 passes through the refrigerant flow switching device 11 and the accumulator 13 and is sucked into the compressor 10 again.

The control device 50 loads the throttle device on the load side so that the superheat (superheat degree) obtained as the difference between the temperature detected by the fourth temperature sensor 46 and the temperature detected by the fifth temperature sensor 47 is constant. The opening degree of 22 is controlled.

[Heating operation mode]
FIG. 4 is a refrigerant circuit diagram illustrating the refrigerant flow in the heating only operation mode of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention.
In FIG. 4, the heating only operation mode will be described by taking as an example a case where a thermal load is generated in the load-side heat exchanger 21. In FIG. 4, the flow direction of the refrigerant is indicated by solid line arrows.

In the heating only operation mode, the refrigerant flow switching device 11 is switched to the state shown by the solid line in FIG. Both the first opening / closing device 30a and the first opening / closing device 30b are switched to the closed state and block the refrigerant. Both the second opening / closing device 31a and the second opening / closing device 31b are switched to the open state and allow the refrigerant to pass therethrough.

When the compressor 10 is driven, the low-temperature and low-pressure refrigerant is compressed and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows out of the outdoor unit 1 through the refrigerant flow switching device 11.

The high-temperature and high-pressure gas refrigerant that has flowed out of the outdoor unit 1 flows into the indoor unit 2 through the refrigerant main pipe 4, and dissipates heat to the indoor air in the load-side heat exchanger 21, thereby heating the indoor air. It becomes a liquid refrigerant.
The liquid refrigerant that has flowed out of the load-side heat exchanger 21 is expanded by the load-side expansion device 22, becomes a low-temperature / medium-pressure two-phase refrigerant or liquid refrigerant, and flows into the outdoor unit 1 again through the refrigerant main pipe 4.

The low-temperature / medium-pressure two-phase refrigerant or liquid refrigerant that has flowed into the outdoor unit 1 flows into the heat source side heat exchanger 12a and the heat source side heat exchanger 12b through the second switchgear 31a and the second switchgear 31b, respectively. To do. The refrigerant that has flowed into the heat source side heat exchanger 12a and the heat source side heat exchanger 12b absorbs heat from the outdoor air and becomes a low-temperature / low-pressure gas refrigerant, and the compressor 10 passes through the refrigerant flow switching device 11 and the accumulator 13. Inhaled again.

The control device 50 has a constant subcool (degree of subcooling) obtained as a difference between a value obtained by converting the pressure detected by the first pressure sensor 41 into a saturation temperature and a temperature detected by the fourth temperature sensor 46. Thus, the opening degree of the load side expansion device 22 is controlled.

[Defrost operation mode]

The defrosting operation mode is performed when the detection results of the third temperature sensors 48a and 48b provided on the outlet sides of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b are equal to or less than a predetermined value. The That is, the control device 50 performs the heating only operation mode, and when the detection result of the third temperature sensors 48a and 48b becomes a predetermined value or less (for example, about −10 ° C. or less), the heat source side heat exchangers 12a and 12b It is determined that a predetermined amount of frost has occurred on the fin, and the defrosting operation mode is performed.

In the defrosting operation mode of the air-conditioning apparatus 100 according to Embodiment 1, the heat source side heat exchanger 12b located on the lower side in the casing 51 is defrosted, and then the upper side in the casing 51 The defrosting of the heat source side heat exchanger 12a located in is performed. Of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b, the heat source side heat exchanger that is not a defrost target is operated as an evaporator, and the load side heat exchanger 21 of the indoor unit 2 is operated as a condenser. Continue heating operation.

(Defrosting of heat source side heat exchanger 12b)
FIG. 5 is a refrigerant circuit diagram illustrating a refrigerant flow when the air-conditioning apparatus 100 according to Embodiment 1 of the present invention is defrosting the heat source side heat exchanger 12b in the defrosting operation mode. is there. In FIG. 5, the flow direction of the refrigerant is indicated by solid line arrows.

In the defrosting operation mode, the refrigerant flow switching device 11 is maintained in the state shown by the solid line in FIG.
In the defrosting operation mode, when the heat source side heat exchanger 12b is to be defrosted, the first opening / closing device 30b is switched to the open state and allows the refrigerant to pass therethrough.
The second opening / closing device 31b is switched to the closed state and blocks the refrigerant.
The first opening / closing device 30a is maintained in a closed state and blocks the refrigerant.
The second opening / closing device 31a is maintained in the open state and allows the refrigerant to pass therethrough.

When the compressor 10 is driven, the low-temperature and low-pressure refrigerant is compressed and discharged as a high-temperature and high-pressure gas refrigerant.
A part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 passes through the hot gas bypass pipe 5 and flows into the heat source side heat exchanger 12b through the first opening / closing device 30b. The high-temperature and high-pressure gas refrigerant flowing into the heat source side heat exchanger 12b becomes a low temperature gas refrigerant while melting frost adhering to the heat source side heat exchanger 12b, and merges with the refrigerant flowing out from the heat source side heat exchanger 12a. To do.
Another part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows out of the outdoor unit 1 via the refrigerant flow switching device 11.

The high-temperature and high-pressure gas refrigerant that has flowed out of the outdoor unit 1 flows into the indoor unit 2 through the refrigerant main pipe 4, and dissipates heat to the indoor air in the load-side heat exchanger 21, thereby heating the indoor air. It becomes a liquid refrigerant.
The liquid refrigerant that has flowed out of the load-side heat exchanger 21 is expanded by the load-side expansion device 22, becomes a low-temperature / medium-pressure two-phase refrigerant or liquid refrigerant, and flows into the outdoor unit 1 again through the refrigerant main pipe 4.

The low-temperature / medium-pressure two-phase refrigerant or liquid refrigerant flowing into the outdoor unit 1 flows into the heat source side heat exchanger 12a via the second opening / closing device 31a. The refrigerant flowing into the heat source side heat exchanger 12a absorbs heat from the outdoor air and becomes a low-temperature and low-pressure gas refrigerant. The gas refrigerant that has flowed out of the heat source side heat exchanger 12a merges with the gas refrigerant that has flowed out of the heat source side heat exchanger 12b, and is sucked into the compressor 10 again via the refrigerant flow switching device 11 and the accumulator 13. .

For example, when the temperature of the gas refrigerant at the outlet of the heat source side heat exchanger 12b detected by the third temperature sensor 48b becomes equal to or higher than a predetermined value (for example, 10 ° C. or higher), the control device 50 The defrosting of the side heat exchanger 12b is completed.
Thereafter, defrosting of the heat source side heat exchanger 12a is performed.

Here, it is assumed that the predetermined time is set to be equal to or longer than the time required until all the frost is melted, assuming that the entire heat source side heat exchanger 12b has been frosted without any gap and injecting a part of the high-temperature / high-pressure refrigerant. Good.

(Defrosting of the heat source side heat exchanger 12a)
FIG. 6 is a refrigerant circuit diagram illustrating a refrigerant flow when the air-conditioning apparatus 100 according to Embodiment 1 of the present invention is performing defrosting of the heat source side heat exchanger 12a in the defrosting operation mode. is there. In FIG. 6, the flow direction of the refrigerant is indicated by solid arrows.

In the defrosting operation mode, the refrigerant flow switching device 11 is maintained in the state shown by the solid line in FIG.
In the defrosting operation mode, when the heat source side heat exchanger 12a is to be defrosted, the first opening / closing device 30a is switched to the open state and allows the refrigerant to pass therethrough.
The second opening / closing device 31a is switched to the closed state and blocks the refrigerant.
The first opening / closing device 30b is switched to the closed state and blocks the refrigerant.
The second opening / closing device 31b is switched to the open state and allows the refrigerant to pass therethrough.

When the compressor 10 is driven, the low-temperature and low-pressure refrigerant is compressed and discharged as a high-temperature and high-pressure gas refrigerant.
A part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 passes through the hot gas bypass pipe 5 and flows into the heat source side heat exchanger 12a through the first opening / closing device 30a. The high-temperature and high-pressure gas refrigerant flowing into the heat source side heat exchanger 12a becomes a low temperature gas refrigerant while melting frost adhering to the heat source side heat exchanger 12a, and merges with the refrigerant flowing out from the heat source side heat exchanger 12b. To do.
Another part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows out of the outdoor unit 1 via the refrigerant flow switching device 11.

The high-temperature and high-pressure gas refrigerant that has flowed out of the outdoor unit 1 flows into the indoor unit 2 through the refrigerant main pipe 4, and dissipates heat to the indoor air in the load-side heat exchanger 21, thereby heating the indoor air. It becomes a liquid refrigerant.
The liquid refrigerant that has flowed out of the load-side heat exchanger 21 is expanded by the load-side expansion device 22, becomes a low-temperature / medium-pressure two-phase refrigerant or liquid refrigerant, and flows into the outdoor unit 1 again through the refrigerant main pipe 4.

The low-temperature / medium-pressure two-phase refrigerant or liquid refrigerant flowing into the outdoor unit 1 flows into the heat source side heat exchanger 12b via the second opening / closing device 31b. The refrigerant flowing into the heat source side heat exchanger 12b absorbs heat from the outdoor air and becomes a low-temperature and low-pressure gas refrigerant. The gas refrigerant that has flowed out of the heat source side heat exchanger 12b merges with the gas refrigerant that has flowed out of the heat source side heat exchanger 12a, and is sucked into the compressor 10 again via the refrigerant flow switching device 11 and the accumulator 13. .

For example, when the temperature of the gas refrigerant at the outlet of the heat source side heat exchanger 12a detected by the third temperature sensor 48a becomes equal to or higher than a predetermined value (for example, 10 ° C or higher), the control device 50 The defrosting of the side heat exchanger 12a is completed.

Here, it is assumed that the predetermined time is set to be equal to or longer than the time required until all the frost is melted when it is assumed that the entire heat source side heat exchanger 12a has been frosted without any gap and a part of the high-temperature / high-pressure refrigerant flows. Good.

By carrying out the defrosting operation mode in this way, the heat source side heat exchangers 12a and 12b can be defrosted while continuing the heating operation.
Moreover, defrosting of the heat source side heat exchanger 12b located below the housing | casing 51 is implemented, and the defrosting of the heat source side heat exchanger 12a located above is implemented after that. For this reason, it is possible to prevent the water melted by the defrosting of the heat source side heat exchanger 12a from being re-frozen in the lower heat source side heat exchanger 12b that has not yet been defrosted. Frost can be done.

In addition, in said description, although the defrost of the heat source side heat exchanger 12b was implemented and the case where the defrost of the heat source side heat exchanger 12a was implemented after that was demonstrated, this invention is not limited to this. For example, when the temperature detected from the third temperature sensor 48a becomes a predetermined temperature or lower (eg, −10 ° C. or lower) prior to the third temperature sensor 48b, defrosting is performed first from the heat source side heat exchanger 12a. May be.

[Heat leakage reduction mechanism]
(Fin structure (1))
FIG. 7 is a schematic structural diagram showing an example of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention that is divided without sharing the fins of the heat source side heat exchanger.
In FIG. 7, 61 is a fin of the heat source side heat exchanger 12a. Reference numeral 64 denotes a heat transfer tube of the heat source side heat exchanger 12a. 62 is a fin of the heat source side heat exchanger 12b. 65 is a heat transfer tube of the heat source side heat exchanger 12b.

The heat source side heat exchanger 12a and the heat source side heat exchanger 12b are arranged adjacent to each other in the vertical direction (stage direction). The lowermost end face of the fin 61 of the heat source side heat exchanger 12a located on the upper side and the uppermost end face of the fin 62 of the heat source side heat exchanger 12b located on the lower side are divided.
Further, the lowermost end surface of the fin 61 of the heat source side heat exchanger 12a located on the upper side and the uppermost end surface of the fin 62 of the heat source side heat exchanger 12b located on the lower side are in contact with each other at the boundary portion 63. Are arranged.

At the boundary 63 between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b, the end surfaces of the fins 61 and the fins 62 are roughened to form a heat leakage reduction mechanism.
Note that at least one of the end surfaces of the fin 61 and the fin 62 in the boundary portion 63 may be roughened.

The fin 61 and the fin 62 are only in contact with each other at the boundary portion 63 by this heat leakage reduction mechanism. For this reason, the amount of heat leakage from the condenser to the evaporator due to heat conduction between the fin 61 and the fin 62 is suppressed as compared with the case where the fin 61 and the fin 62 are integrally formed (shared).

The amount of heat leakage Q1 between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b can be expressed by the following equation (1) using a general equation for heat exchange by heat conduction.
Here, T1 [° C.] is the refrigerant gas temperature of the heat source side heat exchanger 12 serving as a condenser among the heat source side heat exchangers 12a and 12b.
T2 [° C.] is an inlet two-phase refrigerant temperature of the heat source side heat exchanger 12 serving as an evaporator among the heat source side heat exchangers 12a and 12b.
λ [W / mK] is the thermal conductivity of the fin.
δ [m] is a distance between fins indicating the distance between the heat transfer tube end near the boundary 63 of the heat source side heat exchanger 12a and the heat transfer tube end near the boundary 63 of the heat source side heat exchanger 12b.
A [m ² ] is an area calculated by multiplying the fin width [m], the fin thickness [m], and the number of fins.

Here, the amount of heat leakage Q1 when the fin 61 and the fin 62 are integrally formed (shared) will be examined.
For example, the average temperature T1 of the gas refrigerant flowing in the condenser for defrosting is set to 20 ° C., and the temperature T2 of the refrigerant flowing in the evaporator used in the heating operation is set to −15 ° C. Further, the distance δ between fins of the heat transfer tube end of the evaporator at the boundary 63 and the heat transfer tube end of the condenser is 12.5 mm, and the fin width is 17 mm and the fin thickness when the heat exchange is not divided. The thickness is 0.1 mm and the number of fins is 3700.
In this case, from equation (1), the heat leakage amount Q1 from the condenser to the evaporator when the fins are shared without being divided is about 3.60 kW.

On the other hand, as shown in FIG. 7, the amount of heat leakage Q1 when the fins at the boundary 63 between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b are divided is examined.
For example, the product of the heat transfer area (contact area) of the contact portion between the fin 61 of the upper heat source side heat exchanger 12a and the fin 62 of the lower heat source side heat exchanger 12b and the heat passage rate is Assume that the heat transfer area (contact area) in the case of sharing is half the product of the heat transmission rate.
In this case, the heat leakage amount Q1 from the condenser to the evaporator due to heat conduction of the fins is suppressed by about 25% or more compared to the case where all the fins are connected in common, and the heat leakage amount Q1 is about 2%. .7 kW.
In addition, it is thought that it is the influence of the temperature distribution in a fin that heat leak amount Q1 does not reach to half compared with the case where all the fins are connected and connected.

Next, the time required to complete the defrosting is examined.
For example, the amount of heat Q2 (calculated by multiplying the frost melting latent heat and the weight of frost) necessary to melt the frost frosted on the evaporator is about 1.5 MJ, from the condenser to the evaporator due to heat conduction of the fins. The amount of heat exchange Q3 between the refrigerant and frost used for defrosting when there is no heat leakage amount is about 5.5 kW.
The time required for completing the defrosting is obtained by dividing the frost melting heat amount Q2 by the difference between the heat exchange amount Q3 and the heat leakage amount Q1.
When the fin 61 and the fin 62 are integrally formed (shared), if the heat leakage amount Q1 is about 3.60 kW and the heat exchange amounts Q2 and Q3 are the above conditions, the time required for completing the defrosting is as follows: About 13 minutes.
On the other hand, as shown in FIG. 7, when the fins are divided, the heat leakage amount Q1 is suppressed by about 25% to be about 2.7 kW, and the defrosting is completed when the heat exchange amounts Q2 and Q3 are the above conditions. The time required to do this is about 9 minutes.
Therefore, the time required to complete the defrosting can be shortened by about 4 minutes.

Thus, by shortening the time until completion of defrosting, compared with the case where there is heat leakage from the condenser to the evaporator due to heat conduction of the fins, the discharge from the compressor 10 is used for defrosting. A part of the refrigerant can be used for heating quickly. Therefore, a reduction in heating capacity can be suppressed. Moreover, the indoor temperature fall can be suppressed and the comfort of the indoor environment can be ensured.
Furthermore, since the temperature drop is suppressed in the fin on the condenser side of the boundary portion 63 between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b, water droplets generated by defrosting the heat exchanger on the upper side of the condenser Icing can be suppressed, and generation of root ice can be suppressed.

(Fin structure (2))
Next, another configuration of the heat leakage reduction mechanism will be described.
FIG. 8 is a schematic structural diagram showing an example of a case where the air-conditioning apparatus 100 according to Embodiment 1 of the present invention is divided without sharing the fins of the heat source side heat exchanger and provided with notches.
As shown in FIG. 8, a part of the lowermost end surface of the fin 61 of the heat source side heat exchanger 12a located on the upper side or a part of the uppermost end surface of the fin 62 of the heat source side heat exchanger 12b located on the lower side. Then, a notch 66 is formed. This notch 66 constitutes a heat leakage reduction mechanism.
In addition, also in the example of FIG. 8, the heat source side heat exchanger 12a and the heat source side heat exchanger 12b are arranged adjacent to each other in the vertical direction (step direction). The lowermost end face of the fin 61 of the heat source side heat exchanger 12a located on the upper side and the uppermost end face of the fin 62 of the heat source side heat exchanger 12b located on the lower side are divided.
Further, the lowermost end surface of the fin 61 of the heat source side heat exchanger 12a located on the upper side and the uppermost end surface of the fin 62 of the heat source side heat exchanger 12b located on the lower side are in contact with each other at the boundary portion 63. Are arranged.

Thus, by providing the notch 66 in a part of fin of the boundary part 63 of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b, the heat source side heat exchanger 12a and the heat source side heat exchanger 12a The contact area of the fins at the boundary 63 with the heat source side heat exchanger 12b is reduced. Therefore, the amount of heat leakage from the condenser to the evaporator due to heat conduction of the fins can be further reduced.

The thermal conductivity of air is much smaller than that of the fin material (eg, aluminum). The thermal conductivity of air is about 0.026 [W / (m · K)], whereas the thermal conductivity of aluminum is about 200 [W / (m · K)].
For this reason, even if the height of the fin notch 66 in the step direction is about 0.1 mm, the amount of heat leakage due to heat conduction of air is as much as 1% of the amount of heat leakage due to heat conduction of aluminum which is the material of the fin. The effect of suppressing heat leakage is sufficiently obtained. For this reason, the height of the notch 66 of a fin should just be about 0.1 mm or more, for example.

Also, the longer the width (in the horizontal direction) of the fin cutout 66, the smaller the amount of heat leakage. For this reason, it is good to set with the longest length which is not crushed with the weight of the heat source side heat exchanger 12a located in the upper direction of the step direction of the heat source side heat exchanger 12. For example, if the length of the notch 66 is set to be at least half the width of the fin, defrosting can be performed without residual frost.

(Fin structure (3))
Furthermore, another configuration of the heat leakage reduction mechanism will be described.
FIG. 9 is a schematic structural diagram showing an example of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention in which a part of the fins of the heat source side heat exchanger is shared and a notch is provided.
As shown in FIG. 9, the fins 61 of the heat source side heat exchanger 12a located on the upper side and the fins 62 of the heat source side heat exchanger 12b located on the lower side are integrated (shared). That is, the fin 61 and the fin 62 are shared without being divided.
One of the fin boundary portions 63 between the lowermost stage of the heat transfer tube 64 of the heat source side heat exchanger 12a located on the upper side and the uppermost stage of the heat transfer tube 65 of the heat source side heat exchanger 12b located on the lower side. A notch 66 is formed in the portion. This notch 66 constitutes a heat leakage reduction mechanism.

Even in such a configuration, the same effect as the configuration shown in FIGS. 7 and 8 can be obtained.
Further, by sharing a part of the fin and providing the notch 66 at the fin boundary 63, the heat source side heat exchanger 12a and the heat source side heat exchanger 12b can be manufactured simultaneously. For this reason, compared with the case where the heat source side heat exchanger 12a and the heat source side heat exchanger 12b are manufactured separately, a manufacturing process reduces and the manufacturing cost of the heat source side heat exchanger 12 can be reduced.

(Fin structure (4))
Furthermore, another configuration of the heat leakage reduction mechanism will be described.
FIG. 10 is a schematic structural diagram showing an example of the case where the air-conditioning apparatus 100 according to Embodiment 1 of the present invention shares some fins of the heat source side heat exchanger and is provided with slits.
As shown in FIG. 10, the fins 61 of the heat source side heat exchanger 12a and the fins 62 of the heat source side heat exchanger 12b are integrated (shared), and the fins at both ends of the notch are formed at the fin boundary 63. A slit 67 is provided which is processed without being cut off (cut and raised). The slit 67 constitutes a heat leakage reduction mechanism.

Even in such a configuration, since a space is formed in the boundary portion 63 between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b, the same effects as the configurations shown in FIGS. 7, 8, and 9 described above are obtained. It is done.

(Fin structure (5))
Furthermore, another configuration of the heat leakage reduction mechanism will be described.
FIG. 11 is a schematic structural diagram showing an example in which the air-conditioning apparatus 100 according to Embodiment 1 of the present invention is divided without sharing the fins of the heat source side heat exchanger and provided with an elliptical cutout. It is.
The shape of the notch 66 or the slit 67 of the fin at the boundary between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b is not limited to the rectangular shape shown in FIGS. It is sufficient if there is a space in the fin contact portion of the boundary portion 63 between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b.
For example, even in various shapes such as a semi-elliptical shape as shown in FIG. 11, the same effects as those of the configurations shown in FIGS.
In addition, although the example which provided the notch 66 or the slit 67 in the heat-source side heat exchanger 12a was shown in the structure of FIG.7, FIG.8, FIG.10, this invention is not limited to this. Even if the notch 66 or the slit 67 is provided in the heat source side heat exchanger 12b, the same effect as the configuration shown in FIGS. 7, 8, and 10 can be obtained.

(Fin structure (6))
Furthermore, another configuration of the heat leakage reduction mechanism will be described.
FIG. 12 is a schematic structural diagram showing an example of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention in which a part of the fin is shared and two notches are provided.
The number of fin notches 66 or slits 67 at the boundary 63 between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b is one notch 66 or slit as shown in FIGS. It is not limited to 67.
For example, two notches 66 as shown in FIG. 12 may be formed, or three or more notches 66 may be formed. Also in this configuration, the same effect as the configuration shown in FIGS. 7, 8, and 10 can be obtained. In other words, if the product of the heat transfer area between the fins sandwiching the notch 66 and the heat transmission rate are the same, the configuration shown in FIGS. 7, 8, and 10 has the same effect of reducing the amount of heat leakage.

7, 8, and 10, an example in which the notch 66 or the slit 67 is provided at the lower end of the heat source side heat exchanger 12 a is shown. However, the present invention is not limited thereto, and the upper end of the heat source side heat exchanger 12 b is provided. Even if the notch 66 or the slit 67 is provided, the same effect as the configuration shown in FIGS. 7, 8, and 10 can be obtained.

(Fin structure (7))
Furthermore, another configuration of the heat leakage reduction mechanism will be described.
FIG. 13 is a schematic structural diagram showing an example of an outdoor unit installation state in the air-conditioning apparatus 100 according to Embodiment 1 of the present invention when a gap is provided between the upper and lower sides of the heat source side heat exchanger.
As shown in FIG.
The heat source side heat exchanger 12a and the heat source side heat exchanger 12b are arranged adjacent to each other in the vertical direction (stage direction). The lowermost end face of the fin 61 of the heat source side heat exchanger 12a located on the upper side and the uppermost end face of the fin 62 of the heat source side heat exchanger 12b located on the lower side are divided.
Further, a gap 54 is provided between the lowermost end surface of the fin 61 of the heat source side heat exchanger 12a located on the upper side and the uppermost end surface of the fin 62 of the heat source side heat exchanger 12b located on the lower side. It has been. The gap 54 constitutes a heat leakage reduction mechanism.

As described above, even if the gap 54 is provided between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b, the same effect as the configuration shown in FIGS. 7 to 12 can be obtained.

The arrangement method of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b may be any method as long as it is set so that a space exists between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b. .
For example, as shown in FIG. 13, a receiving plate 53 formed of, for example, a SUS plate or a coated steel plate is provided at the lowermost portion of the heat source side heat exchanger 12 a to support the heat source side heat exchanger 12 a.
In such an arrangement method, there is a case where the wind bypasses from the gap 54 between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b, and the amount of air passing through the heat source side heat exchanger 12a decreases. is there. For this reason, the air path of the gap 54 between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b is preferably closed by, for example, a SUS plate, a coated steel plate, or the like to suppress wind bypass. .

Next, the distance of the gap 54 will be considered.
When the gap 54 is provided between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b, the heat source side heat exchanger 12a and the heat source side heat exchanger 12a that can be installed in the casing of the outdoor unit 1 are compared with the case where the gap 54 is not provided. The height of the heat source side heat exchanger 12b is shortened. For this reason, the number of stages of the heat transfer tubes decreases, and the heat transfer area of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b as a whole decreases.

FIG. 14 is a comparison diagram of the heat transfer area ratio of the air-conditioning apparatus 100 according to Embodiment 1 of the present invention and COP, which is one of the indexes representing the performance of the air-conditioning apparatus.
The relationship between the heat transfer area ratio of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b and the COP is, for example, as shown in FIG.
FIG. 14 shows an example in which the capacity of the outdoor unit 1 is 10 horsepower (28 kW) and the air volume is constant.
The COP (coefficient of performance) is a value (efficiency) obtained by dividing the heating capacity by the total input power of the outdoor unit 1 and the indoor unit 2.

As shown in FIG. 14, in order to maintain the performance of the air conditioner 100, assuming that the COP reduction rate is suppressed to within about 1%, the heat transfer area ratio of the heat source side heat exchanger 12 is about 96.7%. That's it.
When the total number of stages of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b is 60, the product of the number of stages and the heat transfer area ratio is about 58 stages. That is, in order to keep the COP reduction rate within 1%, the number of stages of about 58 or more is required.
The length in the step direction of the gap 54 is obtained by multiplying the difference between the number of steps when there is no gap 54 and the number of steps when there is the gap 54 by the distance between the center portions of the heat transfer tubes in the step direction. For example, when the distance between the center portions of the heat transfer tubes in the step direction is about 20 mm, the length in the step direction of the gap 54 is the difference between 60 steps when there is no gap 54 and 58 steps when there is a gap 54. It is necessary to multiply the two stages by about 20 mm to be about 40 mm or less.

Therefore, the length Ls in the step direction of the gap 54 is defined as Ac [−] for the heat transfer area ratio, Dd [step] when there is no gap 54, and Ld [mm] for the distance between the heat transfer tube centers in the step direction. ], It is represented by Formula (2).
Further, when the COP reduction rate is suppressed to about 1% or less, 96.7% is substituted into Ac in Equation (2), and becomes equal to or less than Equation (3).

By setting the distance Ls of the gap 54 in this way, the amount of heat leakage between the heat source side heat exchanger 12a and the heat source side heat exchanger 12a is reduced while suppressing the COP reduction rate to within about 1%. Can be made.

As described above, in the first embodiment, in the defrosting operation mode, heat leakage between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b can be suppressed. Therefore, even if a part of the plurality of heat source side heat exchangers 12 is defrosted and the other part is operated for heating, the remaining part is left at the boundary 63 of the plurality of adjacent heat source side heat exchangers 12. Generation of frost and root ice can be suppressed. Therefore, the defrosting time can be shortened, the decrease in heating capacity can be suppressed, and the comfort of the indoor environment can be ensured.

Embodiment 2. FIG.
FIG. 15 is a schematic circuit configuration diagram showing an example of a circuit configuration of the air-conditioning apparatus 200 according to Embodiment 2 of the present invention.
Based on FIG. 15, the configuration of the air-conditioning apparatus 200 according to Embodiment 2 will be described focusing on differences from the air-conditioning apparatus 100 according to Embodiment 1 described above.

As shown in FIG. 15, the second opening / closing device 31 a that blocks the refrigerant in the heat source side heat exchanger 12 a is installed between the heat source side heat exchanger 12 a and the refrigerant flow switching device 11. The second opening / closing device 31 b that blocks the refrigerant of the heat source side heat exchanger 12 b is installed between the heat source side heat exchanger 12 b and the refrigerant flow switching device 11.

One end of the hot gas bypass pipe 5 is connected to the refrigerant pipe 3 between the discharge part of the compressor 10 and the refrigerant flow switching device 11. Further, the other end of the hot gas bypass pipe 5 is branched into two branches, one being connected to the refrigerant pipe 3 between the heat source side heat exchanger 12a and the second switchgear 31a, and the other being the heat source side heat exchanger. It connects to the refrigerant | coolant piping 3 between 12b and the 2nd switchgear 31b.
The hot gas bypass pipe 5 connected to the heat source side heat exchanger 12a is provided with a first opening / closing device 30a. The hot gas bypass pipe 5 connected to the heat source side heat exchanger 12b is provided with a first opening / closing device 30b.

Furthermore, the 3rd opening-and-closing apparatus 32a which can change an opening degree is provided in piping of the load side expansion apparatus 22 of the heat source side heat exchanger 12a. Moreover, the 3rd opening-and-closing apparatus 32b which can change an opening degree is provided in piping of the load side expansion apparatus 22 of the heat source side heat exchanger 12b.
The third opening / closing devices 32a and 32b are throttle devices whose opening degree (opening area) is changed in order to adjust the pressure in the heat source side heat exchanger 12 serving as a condenser.

The other configuration is the same as that of the air conditioning apparatus 100 according to Embodiment 1, and thus the description thereof is omitted.
Further, the flow of the refrigerant in the cooling only operation mode and the heating only operation mode of the air conditioner 200 is the same as that of the air conditioner 100 according to the first embodiment, and thus the description thereof is omitted.

In the second embodiment, the first switchgear 30a, the first switchgear 30b, the second switchgear 31a, the second switchgear 31b, the third switchgear 32a, and the third switchgear 32b Configure the “connection switching device”.

(Defrost operation mode)
Also in the defrosting operation mode of the air-conditioning apparatus 200 according to Embodiment 2, the heat source side heat exchanger 12b located on the lower side in the casing 51 is defrosted, and then the upper side in the casing 51 The defrosting of the heat source side heat exchanger 12a located in is performed.
The conditions for starting the defrosting operation mode are the same as those of the air conditioner 100 according to Embodiment 1.

(Defrosting of heat source side heat exchanger 12b)
In FIG. 15, the flow direction of the refrigerant | coolant in case defrosting of the heat source side heat exchanger 12b is shown with the solid line arrow.
In the defrosting operation mode, the refrigerant flow switching device 11 is maintained in the state shown by the solid line in FIG.
In the defrosting operation mode, when the heat source side heat exchanger 12b is to be defrosted, the first opening / closing device 30b is switched to the open state and allows the refrigerant to pass therethrough.
The second opening / closing device 31b is switched to the closed state and blocks the refrigerant.
The first opening / closing device 30a is maintained in a closed state and blocks the refrigerant.
The second opening / closing device 31a is maintained in the open state and allows the refrigerant to pass therethrough.
The third opening / closing device 32b is set to a fully open state and allows the refrigerant to pass therethrough.
The third opening / closing device 32a is opened by the control device 50 so that the saturation pressure of the two-phase refrigerant calculated from the detection result of the sixth temperature sensor 48b is equal to or higher than a certain value (for example, about 0.8 MPa for the R410A refrigerant). The degree is controlled.

When the compressor 10 is driven, the low-temperature and low-pressure refrigerant is compressed and discharged as a high-temperature and high-pressure gas refrigerant.
A part of the high-temperature / high-pressure gas refrigerant discharged from the compressor 10 is depressurized by the hot gas bypass pipe 5 and the first opening / closing device 30b so as to be higher than 0 ° C. in terms of saturation temperature, It becomes a gas refrigerant and flows into the heat source side heat exchanger 12b. The medium-pressure and high-temperature gas refrigerant that has flowed into the heat source side heat exchanger 12b becomes a two-phase refrigerant having a low intermediate pressure or a medium pressure refrigerant while melting frost adhering to the heat source side heat exchanger 12b. And passes through the third opening / closing device 32b. The refrigerant that has passed through the third opening / closing device 32b joins the two-phase refrigerant or liquid refrigerant having a low intermediate pressure / low temperature flowing into the outdoor unit 1 from the indoor unit 2 on the upstream side of the third opening / closing device 32a. .

The other part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows out of the outdoor unit 1 via the refrigerant flow switching device 11. The high-temperature and high-pressure gas refrigerant that has flowed out of the outdoor unit 1 flows into the indoor unit 2 through the refrigerant main pipe 4, and dissipates heat to the indoor air in the load-side heat exchanger 21, thereby heating the indoor air. It becomes a liquid refrigerant. The liquid refrigerant that has flowed out of the load-side heat exchanger 21 is expanded by the load-side expansion device 22, becomes a low-temperature / medium-pressure two-phase refrigerant or liquid refrigerant, and flows into the outdoor unit 1 again through the refrigerant main pipe 4.

The low-temperature / medium-pressure two-phase refrigerant or liquid refrigerant that has flowed into the outdoor unit 1 merges with the refrigerant from the third switchgear 32b upstream of the third switchgear 32a, and flows into the heat source side heat exchanger 12a. The refrigerant flowing into the heat source side heat exchanger 12a absorbs heat from the outdoor air and becomes a low-temperature and low-pressure gas refrigerant. The gas refrigerant that has flowed out of the heat source side heat exchanger 12a is again sucked into the compressor 10 via the refrigerant flow switching device 11 and the accumulator 13.

The controller 50 opens the opening of the third opening / closing device 32a so that the saturation pressure of the two-phase refrigerant calculated from the detection result of the sixth temperature sensor 48b is equal to or higher than a certain value (for example, about 0.8 MPa for R410A refrigerant). To control. That is, the control device 50 controls the opening degree of the third opening / closing device 32a so that the saturation pressure of the two-phase refrigerant calculated from the detection result of the sixth temperature sensor 48b becomes greater than 0 ° C. in terms of saturation temperature. To do.

The determination of the completion of defrosting of the heat source side heat exchanger 12b may be determined, for example, when the temperature of the third temperature sensor 48b is equal to or higher than a predetermined value (for example, 5 ° C.), that the frost has melted.
Other operations in the defrosting operation mode are the same as those of the air conditioning apparatus 100 according to the first embodiment.

When defrosting of the heat source side heat exchanger 12b is performed after the defrosting of the heat source side heat exchanger 12b is completed, the alphabet a in the description of the defrosting operation of the heat source side heat exchanger 12b is used. It becomes the operation | movement which replaced b. That is, the open / close states of the first switchgears 30a and 30b and the second switchgears 31a and 31b are reversed, and the refrigerant flows between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b are switched. Further, the third opening / closing device 32a is fully opened, and the opening degree of the third opening / closing device 32b is controlled.

Thus, in the defrosting operation mode of the heat source side heat exchanger 12, the saturation temperature of the refrigerant in the heat source side heat exchanger 12 serving as a condenser is set to a medium pressure (for example, higher than 0 ° C., which is higher than the frost temperature). R410A refrigerant is about 0.8 MPa or more). For this reason, the two-phase region (latent heat) of the refrigerant can be used, and an equivalent defrosting capability can be obtained with a smaller amount of refrigerant circulation than the configuration of the air conditioner 100 according to the first embodiment.

Next, the amount of heat leakage Q1 between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b is examined.
In the air conditioner 200 according to the second embodiment, as a configuration of the heat leakage reduction mechanism, as shown in FIG. 7, a fin 63 is formed at the boundary 63 between the heat source side heat exchanger 12 a and the heat source side heat exchanger 12 b. Consider the case where is divided without being shared.
For example, the saturation temperature T1 of the two-phase refrigerant flowing in the condenser for defrosting is set to 5 ° C., and the temperature T2 of the refrigerant flowing in the evaporator used in the heating operation is set to −25 ° C. Further, the distance δ between the fins of the heat transfer tube end of the evaporator and the heat transfer tube end of the condenser at the boundary 63 is 12.5 mm, and the fin width is 17 mm and the fin thickness when the heat exchange is not divided. 0.1 mm and 3700 fins.
In this case, from the above formula (1), the heat leakage amount Q1 from the condenser to the evaporator when the fins are shared without being divided is about 3.22 kW.

On the other hand, as shown in FIG. 7, the amount of heat leakage Q1 when the fins at the boundary 63 between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b are divided is examined.
For example, the product of the heat transfer area (contact area) of the contact portion between the fin 61 of the upper heat source side heat exchanger 12a and the fin 62 of the lower heat source side heat exchanger 12b and the heat passage rate is Assume that the heat transfer area (contact area) in the case of sharing is half the product of the heat transmission rate.
In this case, the heat leakage amount Q1 from the condenser to the evaporator due to heat conduction of the fins is suppressed by about 25% or more compared to the case where all the fins are connected in common, and the heat leakage amount Q1 is about 2%. .42 kW.

Next, the time required to complete the defrosting is examined.
For example, the amount of heat Q2 (calculated by multiplying the frost melting latent heat and the weight of frost) necessary to melt the frost frosted on the evaporator is about 1.5 MJ, from the condenser to the evaporator due to heat conduction of the fins. The amount of heat exchange Q3 between the refrigerant and frost used for defrosting when there is no heat leakage amount is about 5.5 kW.
The time required for completing the defrosting is obtained by dividing the frost melting heat amount Q2 by the difference between the heat exchange amount Q3 and the heat leakage amount Q1.
When the fin 61 and the fin 62 are integrally formed (shared), if the heat leakage amount Q1 is about 3.22 kW and the heat exchange amounts Q2 and Q3 are the above conditions, the time required for completing the defrosting is About 11 minutes.
On the other hand, in the air conditioner 200 according to Embodiment 2, when the fins are divided, the heat leakage amount Q1 is suppressed by about 25% to be about 2.42 kW, and the heat exchange amounts Q2 and Q3 are the above conditions. Then, the time required to complete the defrosting is about 8 minutes.
Therefore, the time required to complete the defrosting can be shortened by about 3 minutes.

Thus, by shortening the time until completion of defrosting, compared with the case where there is heat leakage from the condenser to the evaporator due to heat conduction of the fins, the discharge from the compressor 10 is used for defrosting. A part of the refrigerant can be used for heating quickly. Therefore, a reduction in heating capacity can be suppressed. Moreover, the indoor temperature fall can be suppressed and the comfort of the indoor environment can be ensured.
Furthermore, since the temperature drop is suppressed in the fin on the condenser side of the boundary portion 63 between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b, water droplets generated by defrosting the heat exchanger on the upper side of the condenser Icing can be suppressed, and generation of root ice can be suppressed.

In the above description, in the air-conditioning apparatus 200 according to Embodiment 2, the configuration of FIG. 7 is applied as the configuration of the heat leakage reduction mechanism, but the configuration is not limited thereto. As the configuration of the heat leakage reducing mechanism, the same effects as the configuration shown in FIG. 7 can be obtained even with the configurations of FIGS. 8 to 13 described in the first embodiment.

In the air conditioner 200 shown in FIG. 15, the example in which the third opening / closing device 32a and the third opening / closing device 32b are throttle devices that can change the opening degree (opening area) is shown. Is not limited to this.
(Modification 1)
For example, as shown in FIG. 16, in the air-conditioning apparatus 200 according to Embodiment 2, one of the third opening / closing devices 32b (or the third opening / closing device 32a) is a throttle whose opening degree (opening area) can be changed. You may change to an apparatus. In this case, during the defrosting operation, the third opening / closing device changed to a throttling device in which the third opening / closing device 32a (or the third opening / closing device 32b) that has not been changed is always opened and the opening degree (opening area) can be changed. The pressure in the heat source side heat exchanger 12 serving as a condenser is adjusted using 32b (or the third opening / closing device 32a). Even in such a configuration, the same operation as the air conditioner 200 shown in FIG. 15 is possible, and the same effect can be obtained.

That is, at the time of defrosting operation, the saturation temperature of the refrigerant in the heat source side heat exchanger 12 serving as a condenser is set to a medium pressure higher than 0 ° C. that is higher than the frost temperature (for example, about 0.8 MPa or more with R410A refrigerant). Any circuit configuration can be used. For example, the number of the second opening / closing device 31 that is a throttling device whose opening degree (opening area) can be changed may be one.
With this configuration, the number of throttle devices that can change the opening degree (opening area) of an electronic expansion valve equipped with a stepping motor, which is generally more complicated and expensive than a solenoid valve, is reduced. The outdoor unit 1 can be manufactured at a low cost.

(Modification 2)
For example, as shown in FIG. 17, in the air conditioning apparatus 200 according to Embodiment 2, the opening degree (opening area) of one of the third opening / closing devices 32b (or the third opening / closing device 32a) is changed. It may be changed to a diaphragm device. In this case, only one third opening / closing device 32 is installed, and the pressure in the heat source side heat exchanger 12 serving as a condenser is adjusted during the defrosting operation. Even in such a configuration, the same operation as the air conditioner 200 shown in FIG. 15 is possible, and the same effect can be obtained. Furthermore, with the configuration shown in FIG. 17, the circuit configuration is simplified, and the outdoor unit 1 can be manufactured at low cost.

(Modification 3)
For example, as shown in FIG. 18, in the air conditioning apparatus 200 according to Embodiment 2, the opening degree (opening area) of one of the third opening / closing devices 32b (or the third opening / closing device 32a) is changed. In this case, only one third opening / closing device 32 is installed. Then, the heat source side heat exchanger 12a or the heat source side heat exchanger 12a or the heat source side heat exchanger 12b is newly connected to the refrigerant pipe 3 between the third switchgear 32b (or the third switchgear 32a). A fourth switchgear 33a and a fourth switchgear 33b are installed to shut off the refrigerant in the heat source side heat exchanger 12b.
Further, a refrigerant bypass pipe 6 is installed. One end of the refrigerant bypass pipe 6 is connected to each of the heat source side heat exchangers 12a and 12b and the refrigerant pipe 3 between the fourth switchgear 33, and the other end is connected to the third switchgear 32 and the load side throttle device. 22 to the flow path between the two. The refrigerant in the heat source side heat exchanger 12 serving as a condenser is caused to flow into the refrigerant pipe 3 by the refrigerant bypass pipe 6 in the defrosting operation mode.
Further, the fifth opening / closing device 34a and the fifth opening / closing device 34b for switching the refrigerant flow path of the refrigerant bypass pipe 6 are connected between the heat source side heat exchanger 12 and the fourth opening / closing device 33 each corresponding to one end. The refrigerant bypass pipe 6 is installed.

In the air conditioning apparatus 200 shown in FIG. 18, when the defrosting operation of the heat source side heat exchanger 12 b is performed, the fourth opening / closing device 33 a is opened. The fourth opening / closing device 33b is closed. The fifth opening / closing device 34a is closed. The fifth opening / closing device 34b is opened.
In the defrosting operation mode, the pressure in the heat source side heat exchanger 12b serving as a condenser is adjusted by the third switching device 32b (or the third switching device 32a). In addition, a part of the condensed refrigerant is passed through the fifth opening / closing device 34b in the refrigerant pipe 3 between the third opening / closing device 32b (or the third opening / closing device 32a) and the load-side throttle device 22 on the load side. The refrigerant is combined with other refrigerant flowing into the outdoor unit 1 from the expansion device 22. Further, all the refrigerant absorbs heat from the air through the third opening / closing device 32b (or the third opening / closing device 32a) and the fourth opening / closing device 33a in the heat source side heat exchanger 12a, which is an evaporator. Then, the air is sucked into the compressor 10 through the second opening / closing device 31a, the refrigerant flow switching device 11, and the accumulator 13.
Other operations are the same as those in FIG.

When defrosting of the heat source side heat exchanger 12b is performed after the defrosting of the heat source side heat exchanger 12b is completed, the alphabet a in the description of the defrosting operation of the heat source side heat exchanger 12b is used. It becomes the operation | movement which replaced b.
That is, the opening / closing states of the first opening / closing devices 30a, 30b, the fourth opening / closing devices 33a, 33b, and the fifth opening / closing devices 34a, 34b are reversed, and the refrigerant flows between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b. Will be replaced.

[Refrigerant]
Examples of the heat source side refrigerant in the first and second embodiments include non-combustible refrigerants such as R410A, R407C, and R22, mixed refrigerants including HFO1234yf, HFO1234ze (E), R32, HC, R32, and HFO1234yf, and the aforementioned refrigerants A refrigerant exhibiting slight flammability, such as a refrigerant using a mixed refrigerant containing at least one component, a highly flammable refrigerant such as propane (R290), a refrigerant whose high pressure side operates supercritically, such as CO2 (R744), Can be used as

[First switchgear]
Although the example which uses a solenoid valve was demonstrated as 1st opening-and-closing apparatus 30a, 30b of the said Embodiment 1 and Embodiment 2, an opening degree can be varied like an electronic expansion valve other than a solenoid valve. A valve may also be used as an on-off valve.

[Second switchgear]
Although the example which uses an electromagnetic valve was demonstrated as 2nd opening-and-closing apparatus 31a, 31b of the said Embodiment 1 and Embodiment 2, an opening degree can be varied like an electronic expansion valve other than an electromagnetic valve. A valve may also be used as an on-off valve.

[Third switchgear]
In the second embodiment, the third opening / closing devices 32a and 32b are throttle devices that can change the opening degree (opening area), but any device that can change the opening area of the flow path may be used.
For example, the expansion device may be an electronic expansion valve that is driven by a stepping motor, or a plurality of small electromagnetic valves arranged in parallel and switched to change the opening area.

[Fourth switchgear]
Although the example which uses a solenoid valve was demonstrated as the 4th opening / closing apparatus 33 of this Embodiment 2, the valve which can change an opening degree like a solenoid valve other than a solenoid valve is also used as a switching valve. May be.

[Fifth switchgear]
Although the example which uses a solenoid valve was demonstrated as the 5th opening / closing apparatus 34 of this Embodiment 2, the valve which can change an opening degree like an electronic valve other than an solenoid valve is also used as a switching valve. May be.

[Heat source side heat exchanger]
The heat source side heat exchangers 12a and 12b of the first embodiment and the second embodiment are bent in a U shape and are arranged in two stages in the step direction (vertical direction in which each fin faces the same direction). Although the example which is located was demonstrated, this invention is not limited to this.
The heat source side heat exchanger 12 may have a structure in which a plurality of units are located, such as a structure without bending, or three or more stages in the step direction (vertical direction in which each fin faces the same direction).
Further, the arrangement of the plurality of heat source side heat exchangers 12 is not limited to the upper and lower sides, and may be arranged in the left and right direction and the front and rear direction.

Although the air conditioning apparatus 100 according to Embodiment 1 and the air conditioning apparatus 200 according to Embodiment 2 have been described using the air conditioning apparatus that switches between cooling and heating operations as an example, this is not limiting, and simultaneous cooling and heating operations are possible. The present invention can also be applied to an air conditioner having a circuit configuration. Further, the refrigerant flow switching device 11 may be omitted, and only the heating only operation mode and the defrosting operation mode may be performed.

1 outdoor unit, 2 indoor unit, 3 refrigerant pipe, 4 refrigerant main pipe, 5 hot gas bypass pipe, 6 refrigerant bypass pipe, 10 compressor, 11 refrigerant flow path switching device, 12a-b heat source side heat exchanger, 13 accumulator, 21 load side heat exchanger, 22 load side throttle device, 30a-b first switchgear, 31a-b second switchgear, 32a-b third switchgear, 33a-b fourth switchgear, 34a-b fifth Switchgear, 41, first pressure sensor, 42, second pressure sensor, 43, first temperature sensor, 44, second temperature sensor, 45, third temperature sensor, 46, fourth temperature sensor, 47, fifth temperature sensor, 48a-b, sixth Temperature sensor, 50 control device, 51 housing, 52 fan, 53 backing plate, 54 gap, 61 fin, 62 fin, 63 boundary 63, 64 Heat transfer tubes, 65 heat transfer tube lacks 66 cut, 67 slit, 100 air conditioner, 200 air conditioner.

Claims (11)

1. A compressor, a load-side heat exchanger, a load-side expansion device, and a plurality of heat-source-side heat exchangers connected in parallel to each other, sequentially connected by piping, and a main circuit in which the refrigerant circulates;
   A bypass pipe that branches a part of the refrigerant discharged from the compressor and flows into the heat source side heat exchanger to be defrosted among the plurality of heat source side heat exchangers;
   The heat source side heat to be defrosted is switched by passing or blocking the flow path of the bypass pipe and passing or blocking the flow path of the pipe of the main circuit connected to the plurality of heat source side heat exchangers. A connection switching device for switching the exchange;
   With
   The heat source side heat exchanger is
   A plurality of fins spaced apart to allow air to pass through;
   A plurality of heat transfer tubes inserted into the plurality of fins and through which the refrigerant flows,
   The plurality of heat source side heat exchangers are:
   The plurality of fins are arranged next to each other so as to face the same direction,
   An air conditioner comprising a heat leakage reduction mechanism that reduces the amount of heat leakage between the adjacent heat source side heat exchangers between the plurality of adjacent fins.
2. Among the plurality of heat source side heat exchangers, the heat source side other than the defrost target during the defrost operation in which a part of the refrigerant discharged by the compressor flows into the heat source side heat exchanger to be defrosted. At least one of the heat exchangers functions as an evaporator for heating operation,
   The air conditioner according to claim 1, wherein the heat source side heat exchanger to be defrosted is sequentially switched.
3. The connection switching device is
   A plurality of first opening and closing devices for passing or blocking a flow path from the bypass pipe to the plurality of heat source side heat exchangers;
   A plurality of second opening and closing devices configured to pass or block the flow path of the piping on the load side expansion device side of the plurality of heat source side heat exchangers,
   The first switchgear corresponding to the heat source side heat exchanger to be defrosted is opened and the second switchgear is closed among the plurality of heat source side heat exchangers. The air conditioning apparatus according to 1 or 2.
4. The connection switching device is
   A plurality of first opening and closing devices for passing or blocking a flow path from the bypass pipe to the plurality of heat source side heat exchangers;
   A plurality of second opening and closing devices for passing or blocking the flow path of the piping on the suction side of the compressor of the plurality of heat source side heat exchangers;
   Of the plurality of heat source side heat exchangers, the defrosting is configured by a third switching device provided in the pipe on the load side expansion device side of the plurality of heat source side heat exchangers and having an opening degree changeable. Open the first switchgear corresponding to the target heat source side heat exchanger, close the second switchgear,
   The opening degree of the third switchgear is adjusted so that the pressure of the refrigerant flowing out of the heat source side heat exchanger to be defrosted is greater than 0 ° C in terms of saturation temperature. The air conditioning apparatus according to 1 or 2.
5. The plurality of heat source side heat exchangers are arranged adjacent to each other in the vertical direction,
   Of the plurality of heat source side heat exchangers, an end surface of the lowermost portion of the fin of the heat source side heat exchanger located on the upper side and an end surface of the uppermost portion of the fin of the heat source side heat exchanger located on the lower side The air conditioner according to any one of claims 1 to 4, wherein the air conditioner is divided.
6. The heat leakage reduction mechanism is
   Of the plurality of heat source side heat exchangers, an end surface of the lowermost portion of the fin of the heat source side heat exchanger located on the upper side and an end surface of the uppermost portion of the fin of the heat source side heat exchanger located on the lower side And the gap
   The distance (Ls) of the gap is
   The number of stages (Dd) of the plurality of heat transfer tubes when the plurality of heat source side heat exchangers are not divided, and the center of the plurality of heat transfer tubes in the stage direction when the plurality of heat source side heat exchangers are not divided The air conditioner according to claim 5, wherein the air conditioner is equal to or less than a value calculated by a product of a distance (Ld) between the parts and 0.033.
7. The plurality of heat source side heat exchangers include an end surface of the lowermost part of the fin of the heat source side heat exchanger located on the upper side, and an end surface of the uppermost part of the fin of the heat source side heat exchanger located on the lower side. Are placed in contact,
   The heat leakage reduction mechanism is
   Of the plurality of heat source side heat exchangers, the lowermost end surface of the fin of the heat source side heat exchanger located on the upper side, and the uppermost part of the fin of the heat source side heat exchanger located on the lower side 6. The air conditioner according to claim 5, wherein the air conditioner is constituted by a rough surface formed on at least one of the end surfaces.
8. The plurality of heat source side heat exchangers include an end surface of the lowermost part of the fin of the heat source side heat exchanger located on the upper side, and an end surface of the uppermost part of the fin of the heat source side heat exchanger located on the lower side. Are placed in contact,
   The heat leakage reduction mechanism is
   Of the plurality of heat source side heat exchangers, the lowermost end surface of the fin of the heat source side heat exchanger located on the upper side, and the uppermost part of the fin of the heat source side heat exchanger located on the lower side The air conditioner according to claim 5, wherein the air conditioner is configured by a notch formed in a part of at least one of the end faces.
9. The plurality of heat source side heat exchangers are arranged adjacent to each other in the vertical direction,
   Of the plurality of heat source side heat exchangers, the fins of the heat source side heat exchanger located on the upper side and the fins of the heat source side heat exchanger located on the lower side are integrated,
   The heat leakage reduction mechanism is
   Among the plurality of heat source side heat exchangers, the heat source side heat exchanger located on the upper side and the heat source side heat exchanger located on the lower side were configured by notches formed in the fins. The air conditioning apparatus according to any one of claims 1 to 4, wherein:
10. The air conditioner according to claim 8 or 9, wherein the width of the notch is at least half the width of the fin.
11. The plurality of heat source side heat exchangers are arranged adjacent to each other in the vertical direction,
    Among the plurality of heat source side heat exchangers, the heat source side heat exchanger located on the upper side functions as an evaporator and performs heating operation, while the heat source side heat exchanger located on the lower side is a defrost target. After performing the defrosting operation
    The heat source side heat exchanger located on the lower side functions as an evaporator to perform heating operation, and performs the defrosting operation on the heat source side heat exchanger located on the upper side as a defrost target. The air conditioner according to any one of claims 1 to 10.

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