Refrigeration cycle equipment

Abstract

The refrigeration cycle device comprises a refrigerant circuit having a compressor, a heat source heat exchanger, and a heat load heat exchanger, a heat source blower that blows air to the heat source heat exchanger, a first unit equipped with the heat source heat exchanger, and a control device, the first unit being installed in a heat source side air duct of a building, the control device being capable of switching between a first operation in which the heat source heat exchanger functions as an evaporator and a second operation in which the heat source heat exchanger functions as a condenser, and when the control device ends the second operation and starts the first operation, it starts the heat source blower before the heat source heat exchanger functions as an evaporator.

Description

[Technical Field]

[0001] The present disclosure relates to a refrigeration cycle device. [Background technology]

[0002] Patent Document 1 discloses an air conditioner. This air conditioner has a heat source-side heat exchanger unit, a compressor unit, and an indoor unit. The heat source-side heat exchanger unit is configured as an outdoor unit, but is placed inside the ceiling of a building. One end of the case of the heat source-side heat exchanger unit is connected to an air duct that takes in outside air. The other end of the case is connected to an air duct that exhausts air to the outside. A heat source-side heat exchanger and a fan are mounted inside the case of the heat source-side heat exchanger unit. In the heat source-side heat exchanger, heat exchange occurs between the outside air flowing through the air duct by the fan and the refrigerant. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-84410 Summary of the Invention [Problem to be solved by the invention]

[0004] In a typical air conditioner, when heating operation is performed under conditions of low outdoor air temperature, condensed water freezes and frosts in the heat source heat exchanger, making it impossible to continue heating operation. In such a situation, a defrosting operation is performed in which high-temperature refrigerant discharged from the compressor is supplied to the heat source heat exchanger. When switching from heating operation to defrosting operation, the air flow to both the heat source heat exchanger and the heat load heat exchanger is stopped, the compressor is stopped, and the refrigerant flow path is switched using a four-way valve.

[0005] However, when the heat source-side heat exchanger is placed inside the air duct as in the configuration of Patent Document 1, the low-temperature, high-humidity air after defrosting remains inside the air duct, which causes the moisture in the air to re-condense in the heat source-side heat exchanger when the heating operation is restarted, shortening the duration of the heating operation.

[0006] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a refrigeration cycle device that can extend the duration of heating operation. [Means for solving the problem]

[0007] A refrigeration cycle device according to the present disclosure includes a refrigerant circuit having a compressor, a heat source heat exchanger, and a heat load heat exchanger, a heat source blower that blows air to the heat source heat exchanger, a first unit that mounts the heat source heat exchanger, and a control device, the first unit being installed in a heat source side air passage duct of a building, and the control device being capable of switching between a first operation in which the heat source heat exchanger functions as an evaporator and a second operation in which the heat source heat exchanger functions as a condenser, and the first operation is the second operation is an operation in which frost forms on the heat source heat exchanger during the first operation, and the control device, when terminating the second operation and starting the first operation, starts the heat source blower before the heat source heat exchanger functions as an evaporator, and when terminating the second operation, the control device temporarily stops the compressor, and when starting the first operation, the control device starts the heat source blower before starting the compressor, and after starting the heat source blower, When the second operation is completed, the air remaining in the first unit is discharged from the first unit, and outdoor air is introduced into the first unit. In the first unit or in the heat source side air passage duct outside the first unit air temperature When the change in time is below the threshold, The compressor is started. [Effects of the Invention]

[0008] According to the present disclosure, the duration of the heating operation can be extended. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a circuit diagram showing a schematic configuration of a refrigeration cycle device according to a first embodiment during heating operation. [Figure 2] FIG. 10 is a diagram showing a state of a heat source heat exchanger after completion of a defrosting operation in a refrigeration cycle apparatus according to a comparative example of the first embodiment. [Figure 3] 4 is a diagram showing a state of a heat source heat exchanger after completion of a defrosting operation in the refrigeration cycle apparatus according to the first embodiment. FIG. [Figure 4] FIG. 10 is a circuit diagram showing a schematic configuration of a refrigeration cycle device according to a modified example of the first embodiment during heating operation. [Figure 5] FIG. 10 is a circuit diagram showing a schematic configuration of a refrigeration cycle device according to a second embodiment during heating operation. [Figure 6] FIG. 10 is a circuit diagram showing a schematic configuration of a refrigeration cycle device according to a second embodiment during a first defrosting operation. [Figure 7] FIG. 10 is a circuit diagram showing a schematic configuration of a refrigeration cycle device according to a first modification of the second embodiment during a first defrosting operation. [Figure 8] FIG. 10 is a diagram showing the control contents of each operation mode by the control device of the refrigeration cycle device according to the first modification of the second embodiment. [Figure 9] FIG. 10 is a circuit diagram showing a schematic configuration of a refrigeration cycle device according to a second modification of the second embodiment during a first defrosting operation. [Figure 10] FIG. 10 is a circuit diagram showing a schematic configuration of a refrigeration cycle device according to a third modification of the second embodiment during a second defrosting operation. [Figure 11] FIG. 10 is a circuit diagram showing a schematic configuration of a refrigeration cycle device according to a third embodiment during heating operation. [Figure 12] FIG. 11 is a circuit diagram showing a schematic configuration of a refrigeration cycle device according to a modification of the third embodiment during heating operation. [Figure 13] FIG. 10 is a circuit diagram showing a schematic configuration of a refrigeration cycle device according to a fourth embodiment during heating operation. DETAILED DESCRIPTION OF THE INVENTION

[0010] Embodiments of the present disclosure will be described below with reference to the drawings. The present disclosure is not limited to the following embodiments and can be modified in various ways without departing from the spirit and scope of the present disclosure. Furthermore, the present disclosure includes all possible combinations of the configurations shown in the following embodiments. In particular, the combinations of components are not limited to the combinations in each embodiment; components described in one embodiment can be applied to another embodiment. In the following description, directional terms (e.g., "up," "down," "right," "left," "front," "rear," etc.) are used as appropriate to facilitate understanding, but these are for explanatory purposes and do not limit the present disclosure. In each drawing, components designated with the same reference numerals are identical or equivalent, and this applies throughout the entire specification. Note that the relative dimensional relationships or shapes of each component in each drawing may differ from those in reality.

[0011] Embodiment 1 A refrigeration cycle device according to a first embodiment will be described. The refrigeration cycle device according to this embodiment is applied to, for example, an air conditioner using an indoor-installation air heat source machine. Fig. 1 is a circuit diagram showing a schematic configuration of the refrigeration cycle device according to this embodiment during heating operation. In Fig. 1, thick arrows indicate the flow of air, and solid arrows indicate the flow of refrigerant.

[0012] As shown in Fig. 1, the refrigeration cycle apparatus 200 of this embodiment is installed in a building 300. The building 300 has an indoor space 301 and an in-ceiling space 302. The in-ceiling space 302 is provided with an outside air duct 303 that introduces outside air and an exhaust duct 304 that exhausts the introduced air to the outside.

[0013] The refrigeration cycle apparatus 200 has a heat source unit 201, a heat load unit 202, and a gas pipe 203 and a liquid pipe 204 that connect the heat source unit 201 and the heat load unit 202. The heat source unit 201 is installed in a ceiling space 302. The heat load unit 202 is installed in an indoor space 301. The gas pipe 203 and the liquid pipe 204 are part of a refrigerant piping through which a refrigerant flows.

[0014] The heat source unit 201 has a case 201a in which an air passage is formed. One end of the case 201a is connected to an outside air duct 303. The other end of the case 201b is connected to an exhaust duct 304. The case 201a, together with the outside air duct 303 and the exhaust duct 304, constitutes an air passage duct of the building 300.

[0015] The heat source unit 201 is equipped with a compressor 10, a flow path switching device 11, a throttling device 32, heat source heat exchangers 40a and 40b, and a heat source blower 41. The heat load unit 202 is equipped with a heat load heat exchanger 20, a throttling device 31, and a heat load blower 21. The compressor 10, flow path switching device 11, heat load heat exchanger 20, the throttling device 31, the throttling device 32, and heat source heat exchangers 40a and 40b are connected via refrigerant piping. The heat source heat exchanger 40a and the heat source heat exchanger 40b are arranged in parallel in the refrigerant flow.

[0016] The compressor 10 draws in a refrigerant, compresses it, and discharges it in a high-temperature, high-pressure state. The refrigerant compressed by the compressor 10 is discharged and sent to the flow path switching device 11. The compressor 10 is configured, for example, as a rotary compressor, a scroll compressor, a screw compressor, or a reciprocating compressor. The compressor 10 may be a high-pressure shell type or a low-pressure shell type. The compressor 10 is controlled by a control device 210, which will be described later.

[0017] The flow path switching device 11 is, for example, a four-way valve that switches the flow direction of the refrigerant in the refrigerant circuit. The flow path switching device 11 is controlled by the control device 210. During heating operation, the flow path switching device 11 is switched to state A shown in FIG. 1. In state A, the discharge side of the compressor 10 is connected to the heat load heat exchanger 20, and the suction side of the compressor 10 is connected to the heat source heat exchangers 40a and 40b. During cooling operation, the flow path switching device 11 is switched to state B, in which the discharge side of the compressor 10 is connected to the heat source heat exchangers 40a and 40b, and the suction side of the compressor 10 is connected to the heat load heat exchanger 20. In this embodiment, during defrosting operation, the flow path switching device 11 is set to state B, which is the same as during cooling operation.

[0018] The heat load heat exchanger 20 is a heat exchanger that exchanges heat between the refrigerant flowing through the refrigerant circuit and indoor air supplied by the heat load blower 21. The heat load blower 21 is controlled by a control device 210.

[0019] The expansion device 31 and the expansion device 32 are provided on both sides of the liquid pipe 204. The expansion device 31 and the expansion device 32 are arranged in series in the flow of the refrigerant. Each of the expansion device 31 and the expansion device 32 functions as a pressure reducing valve or an expansion valve, and reduces the pressure of the refrigerant by expanding it. For example, electronic expansion valves are used as the expansion device 31 and the expansion device 32. The expansion device 31 and the expansion device 32 are controlled by the control device 210.

[0020] For example, during heating operation, the expansion device 31 is fully opened and the opening degree of the expansion device 32 is controlled. During cooling operation, the expansion device 32 is fully opened and the opening degree of the expansion device 31 is controlled. This allows the refrigerant in the liquid pipe 204 to be in the liquid phase in both heating and cooling operations. Therefore, the difference in the amount of refrigerant in the liquid pipe 204 during heating operation and cooling operation can be reduced, and excessive inflow of liquid refrigerant into the compressor 10 due to the generation of excess refrigerant can be suppressed.

[0021] The heat-source heat exchanger 40a and the heat-source heat exchanger 40b are arranged in an air passage in the case 201a. The heat-source heat exchanger 40a and the heat-source heat exchanger 40b are heat exchangers that exchange heat between the refrigerant flowing through the refrigerant circuit and the outdoor air supplied by the heat-source blower 41. The heat-source blower 41 is controlled by the control device 210.

[0022] The control device 210 is configured to control the entire refrigeration cycle device including the compressor 10, the flow path switching device 11, the expansion device 31, the expansion device 32, the heat load blower 21, and the heat source blower 41. These controls may be realized by a microcomputer equipped with a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., or may be realized by dedicated hardware. The control device 210 may be provided in the heat source unit 201 or in the heat load unit 202.

[0023] Next, the operation during heating operation will be described. During heating operation, high-temperature, high-pressure gas refrigerant discharged from the compressor 10 flows into the heat load heat exchanger 20 via the flow path switching device 11 and the gas pipe 203. During heating operation, the heat load heat exchanger 20 functions as a condenser. That is, in the heat load heat exchanger 20, heat is exchanged between the refrigerant circulating therein and the indoor air blown by the heat load blower 21. As a result, the gas refrigerant flowing into the heat load heat exchanger 20 becomes a high-pressure liquid refrigerant. Furthermore, the indoor air blown by the heat load blower 21 is heated by the heat dissipation effect of the refrigerant.

[0024] The high-pressure liquid refrigerant flowing out of the heat load heat exchanger 20 flows into the expansion device 32 via the fully open expansion device 31 and the liquid pipe 204, where it is decompressed and becomes a low-pressure two-phase refrigerant. The low-pressure two-phase refrigerant flows into the heat source heat exchangers 40a, 40b. During heating operation, the heat source heat exchangers 40a, 40b function as evaporators. That is, in the heat source heat exchangers 40a, 40b, heat is exchanged between the refrigerant flowing therethrough and the outdoor air blown by the heat source blowers 41a, 41b. As a result, the refrigerant flowing into the heat source heat exchangers 40a, 40b evaporates and becomes a low-pressure gas refrigerant or two-phase refrigerant. The low-pressure gas refrigerant or two-phase refrigerant flowing out of the heat source heat exchangers 40a, 40b passes through the flow switching device 11 and is drawn into the compressor 10. During heating operation, the above cycle is continuously repeated.

[0025] When heating operation is performed under conditions where the outdoor air temperature is low, condensed water freezes and frosts on the heat-source heat exchangers 40a and 40b, which may make it impossible to continue heating operation. For this reason, defrosting operation is periodically performed to defrost the heat-source heat exchangers 40a and 40b.

[0026] When switching from heating operation to defrosting operation, the control device 210 stops the compressor 10, the heat-source blower 41, and the heat-load blower 21, reduces the pressure difference between the high pressure and the low pressure in the refrigerant circuit, and then switches the flow path switching device 11 from state A to state B. Thereafter, the control device 210 starts the compressor 10 and starts the defrosting operation. For example, the heat-source blower 41 and the heat-load blower 21 remain stopped.

[0027] The high-temperature, high-pressure gas refrigerant discharged from the compressor 10 flows into the heat-source heat exchangers 40a, 40b via the flow path switching device 11. During defrosting operation, the heat-source heat exchangers 40a, 40b function as condensers. That is, in the heat-source heat exchangers 40a, 40b, heat exchange occurs between the refrigerant flowing therethrough and the frost on the surfaces, and the frost melts due to the heat of condensation of the refrigerant. This defrosts the heat-source heat exchangers 40a, 40b. The refrigerant flows out of the heat-source heat exchangers 40a, 40b as a high-pressure two-phase refrigerant or liquid refrigerant.

[0028] The high-pressure two-phase refrigerant or liquid refrigerant flowing out of the heat source heat exchangers 40a, 40b passes through the fully open expansion device 32 and the liquid pipe 204 and flows into the expansion device 31, where it is decompressed and becomes low-pressure two-phase refrigerant. The low-pressure two-phase refrigerant flows into the heat source heat exchangers 40a, 40b and evaporates, becoming low-pressure gas refrigerant. The low-pressure gas refrigerant passes through the flow path switching device 11 and is drawn into the compressor 10.

[0029] When the defrosting operation is completed, the operation returns to heating operation. When switching from the defrosting operation to the heating operation, the control device 210 stops the compressor 10, reduces the pressure difference between the high pressure and the low pressure in the refrigerant circuit, and then switches the flow path switching device 11 from state B to state A. Then, the control device 210 starts the heat source blower 41 before starting the compressor 10. In other words, the control device 210 starts the heat source blower 41 before the heat source heat exchangers 40a, 40b function as evaporators. This generates an airflow in the air passage duct including the case 201a.

[0030] Thereafter, when the compressor 10 starts up, the heating operation in which the heat source heat exchangers 40a, 40b function as evaporators is resumed. That is, in this embodiment, an operation in which the heat source heat exchangers 40a, 40b function as evaporators and an operation in which the heat source heat exchangers 40a, 40b function as condensers are alternately and repeatedly performed.

[0031] 2 is a diagram showing the state of the heat source heat exchanger after the defrosting operation in a refrigeration cycle device according to a comparative example of the present embodiment. In the configuration of this comparative example, after the defrosting operation is completed, the compressor 10 is started before the heat source blower 41 is started.

[0032] When the defrosting operation is completed, melted water remains at the bottom of the heat-source heat exchanger 40a without being drained. Furthermore, low-temperature, humid air, which has become humid due to the evaporation of water, remains in the air passage within the case 201a. If the compressor 10 is started in this state while the heat-source blower 41 is stopped, low-temperature refrigerant flows into the heat-source heat exchanger 40a, causing the moisture in the air to re-condense on the surface of the heat-source heat exchanger 40a. Therefore, in the configuration of the comparative example, the duration of the heating operation may be shortened.

[0033] 3 is a diagram showing the state of the heat source heat exchanger after the end of defrosting operation in the refrigeration cycle apparatus according to this embodiment. In this embodiment, after the end of operation in which the heat source heat exchangers 40a, 40b function as condensers, the heat source blower 41 starts up before the start of operation in which the heat source heat exchangers 40a, 40b function as evaporators. In other words, the heat source blower 41 starts up after the end of defrosting operation and before the compressor 10 starts up.

[0034] In this embodiment, when the defrosting operation is completed, the low-temperature, high-humidity air remaining in the air passage in case 201a is discharged from inside case 201a to the outside through exhaust duct 304 by the airflow generated by heat-source blower 41. Low-humidity outdoor air is introduced into case 201a through outside-air duct 303. Therefore, even when compressor 10 starts and low-temperature refrigerant flows into heat-source heat exchanger 40a, re-condensation of moisture in the air is suppressed. Therefore, in this embodiment, the duration of the heating operation can be extended.

[0035] The time from when the heat source blower 41 is started until when the compressor 10 is started may be a fixed value. Alternatively, the compressor 10 may be started based on a measurement signal of a temperature sensor provided in the heat source unit 201 or in an air passage duct outside the refrigeration cycle apparatus 200. For example, the compressor 10 may be started when the amount of change per unit time in the temperature measured by the temperature sensor becomes equal to or less than a threshold value.

[0036] 4 is a circuit diagram showing a schematic configuration of a refrigeration cycle apparatus according to a modified example of the present embodiment during heating operation. As shown in FIG. 4, the refrigeration cycle apparatus 200 has a compressor mounting unit 205, a heat source heat exchanger unit 206, and a heat load unit 202.

[0037] The heat load unit 202 has two heat load heat exchangers 20a and 20b. The heat load heat exchangers 20a and 20b are connected in parallel with each other in terms of the flow of refrigerant. The heat load heat exchangers 20a and 20b are installed in an air duct on the heat load side. The air duct on the heat load side is an air duct separate from the air duct on the heat source side in which the heat source heat exchangers 40a and 40b are installed.

[0038] The building 300 has a machine room 309. The machine room 309 is isolated from the indoor space 301. In addition to an outside air duct 303 and an exhaust duct 304, the machine room 309 is provided with an intake air duct 305 that supplies conditioned air to the indoor space 301 and a return air duct 306 that returns indoor air from the indoor space 301.

[0039] The compressor mounting unit 205 is installed in the ceiling space 302. The compressor mounting unit 205 has a compressor 10 and a flow path switching device 11 mounted thereon.

[0040] The heat source heat exchanger unit 206 is equipped with an expansion device 32, heat source heat exchangers 40a and 40b, and a heat source blower 41. The heat source heat exchanger unit 206 has a case 206c having an air passage formed therein. One end of the case 206c is connected to an outside air duct 303. The other end of the case 206c is connected to an exhaust duct 304. The case 206c, together with the outside air duct 303 and the exhaust duct 304, constitutes an air passage duct on the heat source side. The heat source heat exchanger unit 206 is installed in the air passage duct on the heat source side.

[0041] The heat load unit 202 has a case 202a with an air passage formed therein. One end of the case 202a is connected to the return air duct 306. The other end of the case 202a is connected to the supply air duct 305. The case 202a, together with the return air duct 306 and the supply air duct 305, constitutes an air passage duct on the heat load side. The heat load unit 202 is installed in the air passage duct on the heat load side.

[0042] If the time between the stop of heating operation and the resumption of heating operation after defrosting becomes long, the average heating capacity of the refrigeration cycle apparatus 200 decreases. However, the air duct is maintained at a certain temperature or higher even when heating operation is stopped due to the thermal capacity of its components. Therefore, by installing the heat load heat exchangers 20a and 20b in the air duct on the heat load side, the blown air temperature can be improved when heating resumes, and the decrease in average heating capacity can be suppressed compared to a system without an air duct on the heat load side.

[0043] As described above, the refrigeration cycle apparatus 200 according to this embodiment includes a refrigerant circuit, a heat source blower 41, a heat source unit 201, a heat load unit 202, and a control device 210. The refrigerant circuit includes a compressor 10, heat source heat exchangers 40a and 40b, and a heat load heat exchanger 20. The heat source blower 41 blows air to the heat source heat exchangers 40a and 40b. The heat source unit 201 is equipped with the heat source heat exchangers 40a and 40b. The heat source unit 201 is installed in a heat source side air passage duct of the building 300. The heat load unit 202 is equipped with the heat load heat exchanger 20. The heat source unit 201 is an example of a first unit. The heat load unit 202 is an example of a second unit.

[0044] The control device 210 can switch between a heating operation in which the heat source heat exchangers 40a, 40b function as evaporators and a defrosting operation in which the heat source heat exchangers 40a, 40b function as condensers. The heating operation is an example of a first operation. The defrosting operation is an example of a second operation. When the control device 210 ends the defrosting operation and starts the heating operation, it starts the heat source blower 41 before the heat source heat exchangers 40a, 40b function as evaporators.

[0045] With this configuration, heating is performed after the low-temperature, high-humidity air remaining in the air duct after defrosting is removed from the air duct, thereby suppressing re-condensation after defrosting in the heat-source heat exchangers 40a, 40b. Furthermore, since the duration of heat exchange in the heat-source heat exchangers 40a, 40b is extended during heating operation, evaporation of the refrigerant is promoted, and excessive inflow of liquid refrigerant into the compressor 10 can be suppressed.

[0046] In the refrigeration cycle apparatus 200 according to this embodiment, when the defrosting operation is ended, the control device 210 temporarily stops the compressor 10. When the heating operation is started, the control device 210 starts the heat-source blower 41 before starting the compressor 10.

[0047] According to this configuration, the heat source blower 41 can be started before the heat source heat exchangers 40a and 40b start functioning as evaporators.

[0048] In the refrigeration cycle apparatus 200 according to this embodiment, the heat load unit 202 is installed in a heat load side air passage duct of the building 300.

[0049] According to this configuration, the thermal capacity of the components of the heat load side air passage duct can improve the temperature of the blown air when heating is resumed, and the decrease in average heating capacity can be suppressed.

[0050] In the refrigeration cycle apparatus 200 according to this embodiment, the refrigerant circuit has an expansion device 31 and an expansion device 32. The expansion device 31 is an example of a first expansion device. The expansion device 32 is an example of a second expansion device. The expansion device 32 is mounted in the heat source unit 201. The expansion device 31 is mounted in the heat load unit 202.

[0051] According to this configuration, the difference in the amount of refrigerant in the liquid pipe 204 during heating operation and cooling operation can be reduced, and therefore excessive inflow of liquid refrigerant into the compressor 10 due to the generation of excess refrigerant can be suppressed.

[0052] Embodiment 2 A refrigeration cycle device according to embodiment 2 will be described. Fig. 5 is a circuit diagram showing a schematic configuration of the refrigeration cycle device according to this embodiment during heating operation. In Fig. 5 and each drawing described later, the blackened parts of the valve symbols indicate that the flow paths are open.

[0053] The heat source unit 201 is installed in an air passage duct, as in the first embodiment. The heat source unit 201 is provided with a flow rate adjustment valve 12, a flow path switching device 13a, a flow path switching device 13b, an on-off valve 18a, an on-off valve 18b, a heat source blower 41a, and a heat source blower 41b. The flow rate adjustment valve 12, the flow path switching device 13a, the flow path switching device 13b, the on-off valve 18a, and the on-off valve 18b are controlled by a control device 210. The flow rate adjustment valve 12 is a fully closable on-off valve. The flow path switching devices 13a and 13b are, for example, four-way valves. The on-off valves 18a and 18b are fully closable on-off valves. The heat source blower 41a is a blower that supplies air to the heat source heat exchanger 40a. The heat source blower 41b is a blower that supplies air to the heat source heat exchanger 40b.

[0054] In the refrigerant circuit during heating operation, the heat source heat exchanger 40a and the heat source heat exchanger 40b are arranged in parallel. The refrigerant circuit during heating operation has, as main circuits, a first path passing through the heat source heat exchanger 40a and a second path passing through the heat source heat exchanger 40b. During heating operation, the refrigerant flows through both the first path and the second path.

[0055] The first path passes through the compressor 10, the flow control valve 12, the heat load heat exchanger 20, the expansion device 31, the branching section 33, the expansion device 32a, the heat source heat exchanger 40a, the flow path switching device 13a, and the branching section 42 in this order, and returns to the compressor 10. The second path passes through the compressor 10, the flow control valve 12, the heat load heat exchanger 20, the expansion device 31, the branching section 33, the expansion device 32b, the heat source heat exchanger 40b, the flow path switching device 13b, and the branching section 42 in this order, and returns to the compressor 10. The second path branches off from the first path at the branching section 33 and merges with the first path at the branching section 42.

[0056] Branching section 15 and branching section 16 are provided in the flow path from the discharge side of compressor 10 to flow control valve 12. During heating operation, the refrigerant discharged from compressor 10 branches into two flow paths at branching section 15, merges at branching section 16, and reaches flow control valve 12. One of the two flow paths is provided with on-off valve 18a and flow path switching device 13a. The other flow path is provided with on-off valve 18b and flow path switching device 13b. During heating operation, on-off valves 18a and 18b are set to a fully open state. By providing on-off valve 18a, on-off valve 18b, flow path switching device 13a, and flow path switching device 13b, first defrosting operation and second defrosting operation, which will be described later, can be performed.

[0057] The defrosting operation in this embodiment includes a first defrosting operation in which heat source heat exchanger 40a is defrosted, and a second defrosting operation in which heat source heat exchanger 40b is defrosted. In the first defrosting operation, the refrigerant flows through the third path, and in the second defrosting operation, the refrigerant flows through the fourth path. In both the first defrosting operation and the second defrosting operation, on-off valve 18a is set to a fully open state, and on-off valve 18b is set to a fully closed state.

[0058] The third path passes through the compressor 10, the on-off valve 18a, the flow path switching device 13a, the heat source heat exchanger 40a, the expansion device 32a, the expansion device 32b, the heat source heat exchanger 40b, and the flow path switching device 13b in this order, and returns to the compressor 10. The fourth path passes through the compressor 10, the on-off valve 18a, the flow path switching device 13a, the flow path switching device 13b, the heat source heat exchanger 40b, the expansion device 32b, the expansion device 32a, the heat source heat exchanger 40a, and the flow path switching device 13a in this order, and returns to the compressor 10.

[0059] The first defrosting operation and the second defrosting operation are performed alternately after the heating operation, for example. That is, the first defrosting operation is performed after the heating operation or after the second defrosting operation. The second defrosting operation is performed after the heating operation or after the first defrosting operation. After defrosting is completed by the first defrosting operation and the second defrosting operation, the operation returns to the heating operation.

[0060] FIG. 6 is a circuit diagram showing a schematic configuration of the refrigeration cycle apparatus according to this embodiment during the first defrosting operation. As shown in FIG. 6, during the first defrosting operation, the on-off valve 18a is set to a fully open state, and the on-off valve 18b is set to a fully closed state. The flow path switching device 13a is set to connect the discharge side of the compressor 10 to the heat-source heat exchanger 40a. The flow path switching device 13b is set to connect the suction side of the compressor 10 to the heat-source heat exchanger 40b. The flow control valve 12 and the expansion device 31 are set to a fully closed state. The expansion devices 32a and 32b are controlled so that a pressure difference is generated between the heat-source heat exchanger 40a and the heat-source heat exchanger 40b. The heat-source blower 41a is set to an off or on state. The heat-source blower 41b is set to an on state.

[0061] In this way, during the first defrosting operation, the compressor 10, on-off valve 18a, flow path switching device 13a, heat source heat exchanger 40a, expansion device 32a, expansion device 32b, heat source heat exchanger 40b, flow path switching device 13b, and compressor 10 are connected in this order, thereby forming a third path, which is a path for the refrigerant during the first defrosting operation.

[0062] When switching from heating operation to first defrost operation, the flow control valve 12 and the expansion device 31 are switched from fully open to fully closed. As a result, the liquid refrigerant that was present in the heat load heat exchanger 20 during heating operation is trapped between the flow control valve 12 and the expansion device 31 and remains in the heat load heat exchanger 20 during the first defrost operation. Therefore, even if the refrigerant pressure in the heat load heat exchanger 20 is higher than the refrigerant discharge pressure of the compressor 10 during the first defrost operation, the amount of liquid refrigerant flowing from the heat load heat exchanger 20 to the compressor 10 can be reduced. Therefore, breakdowns in the compressor 10 can be suppressed.

[0063] Furthermore, during the first defrosting operation, the heat-source blower 41b operates, which promotes evaporation of the refrigerant in the heat-source heat exchanger 40b. This further reduces the amount of liquid refrigerant flowing into the compressor 10. Furthermore, by operating the heat-source heat exchanger 40b, which is not the target for defrosting, as an evaporator, the latent heat of the refrigerant can be used for defrosting, thereby shortening the defrosting time. This allows for an early return from defrosting operation to heating operation, thereby improving heating capacity.

[0064] After the first defrosting operation is completed, the second defrosting operation is performed. The second defrosting operation may be performed after the first defrosting operation is completed, with a heating operation in between. Although the refrigerant circuit is not illustrated, the second defrosting operation is performed in the same manner as the first defrosting operation. During the second defrosting operation, the on-off valve 18a is set to a fully open state, and the on-off valve 18b is set to a fully closed state. The flow path switching device 13a and the flow path switching device 13b are set so that the discharge side of the compressor 10 is connected to the heat-source heat exchanger 40b and the suction side of the compressor 10 is connected to the heat-source heat exchanger 40a. The flow control valve 12 and the expansion device 31 are set to a fully closed state. The expansion devices 32a and 32b are controlled so that a pressure difference is generated between the heat-source heat exchanger 40a and the heat-source heat exchanger 40b. The heat-source blower 41a is set to an on state. The heat-source blower 41b is set to an off or on state.

[0065] During the second defrosting operation, the compressor 10, on-off valve 18a, flow path switching device 13a, flow path switching device 13b, heat source heat exchanger 40b, expansion device 32b, expansion device 32a, heat source heat exchanger 40a, flow path switching device 13a, and compressor 10 are connected in this order, thereby forming a fourth path, which is a path for the refrigerant during the second defrosting operation.

[0066] In the second defrost operation, the flow control valve 12 and the expansion device 31 are also set to fully closed. As a result, the liquid refrigerant that was present in the heat load heat exchanger 20 during the heating operation is trapped between the flow control valve 12 and the expansion device 31 and remains in the heat load heat exchanger 20 during the second defrost operation. Therefore, even if the refrigerant pressure in the heat load heat exchanger 20 is higher than the refrigerant discharge pressure of the compressor 10 during the second defrost operation, the amount of liquid refrigerant flowing from the heat load heat exchanger 20 into the compressor 10 can be reduced. Therefore, breakdowns in the compressor 10 can be suppressed.

[0067] Furthermore, during the second defrosting operation, the heat-source blower 41a operates, which promotes evaporation of the refrigerant in the heat-source heat exchanger 40a. This further reduces the amount of liquid refrigerant flowing into the compressor 10. Furthermore, by operating the heat-source heat exchanger 40a, which is not the target for defrosting, as an evaporator, the latent heat of the refrigerant can be utilized to shorten the defrosting time. This allows for an early return from defrosting operation to heating operation, thereby improving heating capacity.

[0068] After the second defrosting operation is completed, if it is determined that a certain amount of frost has formed on the heat source heat exchanger 40a, the first defrosting operation may be performed again. If it is determined that defrosting of all the heat source heat exchangers 40a, 40b is completed, the flow control valve 12 and the throttle device 31 are opened, and the heating operation is resumed.

[0069] In this embodiment, it is sufficient that the flow control valve 12 and the throttling device 31 in the first path can cause the refrigerant to remain in the heat load heat exchanger 20, and that the heat source heat exchanger 40a and the heat source heat exchanger 40b can be operated separately as an evaporator and a condenser. Therefore, the configuration of the path from the compressor 10 to the heat source heat exchangers 40a and 40b during defrosting operation may be different.

[0070] In this embodiment, the heat source heat exchanger 40a functions as an evaporator during heating operation and second defrost operation, and functions as a condenser during first defrost operation. Therefore, when focusing on the heat source heat exchanger 40a, the heating operation and second defrost operation correspond to the "first operation", and the first defrost operation corresponds to the "second operation". The heat source heat exchanger 40b functions as an evaporator during heating operation and first defrost operation, and functions as a condenser during the second defrost operation. Therefore, when focusing on the heat source heat exchanger 40b, the heating operation and first defrost operation correspond to the "first operation", and the second defrost operation corresponds to the "second operation".

[0071] 7 is a circuit diagram showing a schematic configuration of a refrigeration cycle apparatus according to Modification 1 of this embodiment during first defrosting operation. A heat source unit 201 is installed in an air passage duct. In the refrigerant circuit during heating operation, a heat source heat exchanger 40a and a heat source heat exchanger 40b are arranged in parallel. The refrigerant circuit during heating operation has, as main circuits, a first path passing through the heat source heat exchanger 40a and a second path passing through the heat source heat exchanger 40b. During heating operation, the refrigerant flows through both the first path and the second path.

[0072] The first path passes through compressor 10, flow path switching device 11, branching section 14a, branching section 14b, flow control valve 12, heat load heat exchanger 20, expansion device 31, branching section 33, expansion device 32a, heat source heat exchanger 40a, flow path switching device 13a, branching section 42, and flow path switching device 11 in this order, and returns to compressor 10. The second path passes through compressor 10, flow path switching device 11, branching section 14a, branching section 14b, flow control valve 12, heat load heat exchanger 20, expansion device 31, branching section 33, expansion device 32b, heat source heat exchanger 40b, flow path switching device 13b, branching section 42, and flow path switching device 11 in this order, and returns to compressor 10. The second path branches from the first path at branching section 33 and merges with the first path at branching section 42.

[0073] The refrigerant circuit of the refrigeration cycle apparatus 200 also has, as paths during defrosting operation, a third path for defrosting the heat source heat exchanger 40a and a fourth path for defrosting the heat source heat exchanger 40b.

[0074] The third path passes through the compressor 10, flow path switching device 11, flow path switching device 13a, heat source heat exchanger 40a, expansion device 32a, expansion device 32b, heat source heat exchanger 40b, flow path switching device 13b, and flow path switching device 11 in this order, and returns to the compressor 10. The fourth path passes through the compressor 10, flow path switching device 11, flow path switching device 13b, heat source heat exchanger 40b, expansion device 32b, expansion device 32a, heat source heat exchanger 40a, flow path switching device 13a, and flow path switching device 11 in this order, and returns to the compressor 10.

[0075] A four-way valve is used for the flow path switching device 11. The flow path switching device 11 is controlled by the control device 210. During heating operation, the flow path switching device 11 is switched to state A in which the discharge side of the compressor 10 is connected to the heat load heat exchanger 20 and the suction side of the compressor 10 is connected to the heat source heat exchangers 40a and 40b. On the other hand, during cooling operation, the flow path switching device 11 is switched to state B in which the discharge side of the compressor 10 is connected to the heat source heat exchangers 40a and 40b and the suction side of the compressor 10 is connected to the heat load heat exchanger 20. In this embodiment, during defrosting operation, the flow path switching device 11 is set to state B, which is the same as during cooling operation.

[0076] The flow path switching device 13a uses a three-way valve. The flow path switching device 13a is provided in the first path between the heat source heat exchanger 40a and the branching section 42. The flow path switching device 13a has a first port P1, a second port P2, and a third port P3. The first port P1 is connected to the branching section 42 side of the first path. The second port P2 is connected to the heat source heat exchanger 40a side of the first path. The third port P3 is connected to the branching section 14a via a refrigerant pipe. The flow path switching device 13a is controlled by the control device 210. The flow path switching device 13a can be set to at least a state C in which the first port P1 and the second port P2 are connected to each other and the third port P3 is closed, and a state D in which the second port P2 and the third port P3 are connected to each other and the first port P1 is closed. During heating operation, cooling operation, and defrosting operation of the heat source heat exchanger 40a, the flow path switching device 13a is set to state C. On the other hand, during defrosting operation of the heat source heat exchanger 40b, the flow path switching device 13a is set to state D.

[0077] A three-way valve is used for the flow path switching device 13b. The flow path switching device 13b is provided in the second path between the heat source heat exchanger 40b and the branching section 42. The flow path switching device 13b has a first port P1, a second port P2, and a third port P3. The first port P1 is connected to the branching section 42 side of the second path. The second port P2 is connected to the heat source heat exchanger 40b side of the second path. The third port P3 is connected to the branching section 14b via a refrigerant pipe. The flow path switching device 13b is controlled by the control device 210. The flow path switching device 13b can be set to at least a state C in which the first port P1 and the second port P2 are connected to each other and the third port P3 is closed, and a state D in which the second port P2 and the third port P3 are connected to each other and the first port P1 is closed. During heating operation, cooling operation, and defrosting operation of the heat source heat exchanger 40b, the flow path switching device 13b is set to state C. On the other hand, during defrosting operation of the heat source heat exchanger 40a, the flow path switching device 13b is set to state D.

[0078] FIG. 8 is a diagram showing the control contents of each operation mode by the control device of the refrigeration cycle apparatus according to the first modified example of this embodiment. As shown in FIG. 8, during heating operation, the flow path switching device 11 is set to state A. As a result, the discharge side of the compressor 10 is connected to the heat load heat exchanger 20, and the suction side of the compressor 10 is connected to the heat source heat exchangers 40a and 40b. The flow path switching devices 13a and 13b are both set to state C. The flow control valve 12 is set to fully open. The expansion device 31 is set to fully open. The expansion device 32a is controlled, for example, so that the degree of superheat of the outlet refrigerant of the heat source heat exchanger 40a is constant. The expansion device 32b is controlled, for example, so that the degree of superheat of the outlet refrigerant of the heat source heat exchanger 40b is constant. The heat source blowers 41a and 41b are set to on.

[0079] During heating operation, high-temperature, high-pressure gas refrigerant discharged from the compressor 10 flows into the heat load heat exchanger 20 via the flow path switching device 11, the flow rate control valve 12, and the gas pipe 203. During heating operation, the heat load heat exchanger 20 functions as a condenser. That is, in the heat load heat exchanger 20, heat is exchanged between the refrigerant flowing therethrough and the indoor air blown by the heat load blower 21. As a result, the refrigerant flowing into the heat load heat exchanger 20 condenses into a high-pressure liquid refrigerant. In addition, the indoor air blown by the heat load blower 21 is heated by the heat dissipation effect of the refrigerant.

[0080] The high-pressure liquid refrigerant flowing out of the heat load heat exchanger 20 flows into the throttling device 32a and the throttling device 32b via the throttling device 31 and the liquid pipe 204, respectively, and is reduced in pressure to become a low-pressure two-phase refrigerant. The low-pressure two-phase refrigerant flows into the heat-source heat exchangers 40a and 40b. During heating operation, the heat-source heat exchangers 40a and 40b function as evaporators. That is, in the heat-source heat exchangers 40a and 40b, heat is exchanged between the refrigerant flowing therethrough and the outdoor air blown by the heat-source blowers 41a and 41b. As a result, the refrigerant flowing into the heat-source heat exchangers 40a and 40b evaporates to become a low-pressure gas refrigerant or two-phase refrigerant. The low-pressure gas refrigerant or two-phase refrigerant flowing out of the heat-source heat exchanger 40a passes through the flow switching device 13a and the flow switching device 11 and is drawn into the compressor 10. The gas refrigerant or two-phase refrigerant flowing out from the heat source heat exchanger 40b passes through the flow path switching device 13b and the flow path switching device 11 and is sucked into the compressor 10. In the heating operation, the above cycle is continuously repeated.

[0081] The defrosting operation includes a first defrosting operation in which the heat source heat exchanger 40a is defrosted, and a second defrosting operation in which the heat source heat exchanger 40b is defrosted. In the first defrosting operation, the refrigerant flows through the third path, and in the second defrosting operation, the refrigerant flows through the fourth path.

[0082] During the first defrosting operation, the flow path switching device 11 is set to state B. The flow path switching device 13a is set to state C. The flow path switching device 13b is set to state D. As a result, the discharge side of the compressor 10 is connected to the heat source heat exchanger 40a, and the suction side of the compressor 10 is connected to the heat source heat exchanger 40b. The flow rate adjustment valve 12 is set to fully closed. The expansion device 31 is set to fully closed. The expansion devices 32a and 32b are controlled so that a pressure difference is formed between the heat source heat exchanger 40a and the heat source heat exchanger 40b. The heat source blower 41a is set to off or on. The heat source blower 41b is set to on.

[0083] In the first defrosting operation, the high-temperature, high-pressure gas refrigerant discharged from the compressor 10 flows into the heat-source heat exchanger 40a via the flow path switching device 11 and the flow path switching device 13a. In the first defrosting operation, the heat-source heat exchanger 40a functions as a condenser. That is, in the heat-source heat exchanger 40a, heat exchange occurs between the refrigerant flowing inside and the frost on the surface, and the frost melts due to the heat of condensation of the refrigerant. This defrosts the heat-source heat exchanger 40a. The refrigerant flows out of the heat-source heat exchanger 40a as a high-pressure two-phase refrigerant or liquid refrigerant.

[0084] The high-pressure two-phase refrigerant or liquid refrigerant flowing out of the heat-source heat exchanger 40a is decompressed by the expansion device 32a and the expansion device 32b, and becomes a low-pressure two-phase refrigerant that flows into the heat-source heat exchanger 40b. During the first defrosting operation, the heat-source heat exchanger 40b functions as an evaporator. That is, in the heat-source heat exchanger 40b, heat is exchanged between the refrigerant flowing therethrough and the outdoor air blown by the heat-source blower 41b. The refrigerant absorbs heat from the outdoor air and evaporates, becoming a low-pressure gas refrigerant. The low-pressure gas refrigerant flowing out of the heat-source heat exchanger 40b is drawn into the compressor 10 via the flow path switching device 13b and the flow path switching device 11.

[0085] In this way, during the first defrosting operation, the compressor 10, flow path switching device 11, flow path switching device 13a, heat source heat exchanger 40a, expansion device 32a, expansion device 32b, heat source heat exchanger 40b, flow path switching device 13b, flow path switching device 11, and compressor 10 are connected in this order. This forms a third path, which is a path for the refrigerant during the first defrosting operation.

[0086] When switching from heating operation to first defrost operation, the flow control valve 12 and the expansion device 31 are switched from fully open to fully closed. As a result, the liquid refrigerant that was present in the heat load heat exchanger 20 during heating operation is trapped between the flow control valve 12 and the expansion device 31 and remains in the heat load heat exchanger 20 during the first defrost operation. Therefore, even if the refrigerant pressure in the heat load heat exchanger 20 is higher than the refrigerant discharge pressure of the compressor 10 during the first defrost operation, the amount of liquid refrigerant flowing from the heat load heat exchanger 20 to the compressor 10 can be reduced. Therefore, breakdowns in the compressor 10 can be suppressed.

[0087] Furthermore, during the first defrosting operation, the heat-source blower 41b operates, which promotes evaporation of the refrigerant in the heat-source heat exchanger 40b. This further reduces the amount of liquid refrigerant flowing into the compressor 10. Furthermore, by operating the heat-source heat exchanger 40b, which is not the target for defrosting, as an evaporator, the latent heat of the refrigerant can be used for defrosting, thereby shortening the defrosting time. This allows for an early return from defrosting operation to heating operation, thereby improving heating capacity.

[0088] After the first defrosting operation is completed, the second defrosting operation is executed. The second defrosting operation may be executed after the first defrosting operation is completed, with a heating operation in between. During the second defrosting operation, the flow path switching device 11 is set to state B. The flow path switching device 13a is set to state D. The flow path switching device 13b is set to state C. As a result, the discharge side of the compressor 10 is connected to the heat source heat exchanger 40b, and the suction side of the compressor 10 is connected to the heat source heat exchanger 40a. The flow rate adjustment valve 12 is set to fully closed. The expansion device 31 is set to fully closed. The expansion devices 32a and 32b are controlled so that a pressure difference is generated between the heat source heat exchanger 40a and the heat source heat exchanger 40b. The heat source blower 41a is set to on. The heat source blower 41b is set to off or on.

[0089] During the second defrosting operation, the compressor 10, the flow path switching device 11, the flow path switching device 13b, the heat source heat exchanger 40b, the expansion device 32b, the expansion device 32a, the heat source heat exchanger 40a, the flow path switching device 13a, the flow path switching device 11, and the compressor 10 are connected in this order. This forms a fourth path, which is a path for the refrigerant during the second defrosting operation.

[0090] In the second defrost operation, the flow control valve 12 and the expansion device 31 are also set to fully closed. As a result, the liquid refrigerant that was present in the heat load heat exchanger 20 during the heating operation is trapped between the flow control valve 12 and the expansion device 31 and remains in the heat load heat exchanger 20 during the second defrost operation. Therefore, even if the refrigerant pressure in the heat load heat exchanger 20 is higher than the refrigerant discharge pressure of the compressor 10 during the second defrost operation, the amount of liquid refrigerant flowing from the heat load heat exchanger 20 into the compressor 10 can be reduced. Therefore, breakdowns in the compressor 10 can be suppressed.

[0091] Furthermore, during the second defrosting operation, the heat-source blower 41a operates, which promotes evaporation of the refrigerant in the heat-source heat exchanger 40a. This further reduces the amount of liquid refrigerant flowing into the compressor 10. Furthermore, by operating the heat-source heat exchanger 40a, which is not the target for defrosting, as an evaporator, the latent heat of the refrigerant can be utilized to shorten the defrosting time. This allows for an early return from defrosting operation to heating operation, thereby improving heating capacity.

[0092] After the second defrosting operation is completed, if it is determined that a certain amount of frost has formed on the heat source heat exchanger 40a, the first defrosting operation may be performed again. If it is determined that defrosting of all the heat source heat exchangers 40a, 40b is completed, the flow control valve 12 and the throttle device 31 are opened, and the heating operation is resumed.

[0093] 9 is a circuit diagram showing a schematic configuration of a refrigeration cycle apparatus according to Modification 2 of this embodiment during a first defrosting operation. As shown in FIG. 9, the refrigeration cycle apparatus 200 has, as heat source-side units, a compressor-mounted unit 205 and one or more heat-source heat exchanger units 206a and 206b. The compressor-mounted unit 205, the heat-source heat exchanger unit 206a, and the heat-source heat exchanger unit 206b are formed separately from one another. The heat-source heat exchanger unit 206a and the heat-source heat exchanger unit 206b may be formed integrally. The compressor-mounted unit 205 is connected to the heat-source heat exchanger unit 206a and the heat-source heat exchanger unit 206b via refrigerant piping. The substantial circuit configuration of the refrigeration cycle apparatus 200 is similar to the circuit configuration shown in FIG. 7.

[0094] The compressor mounting unit 205 is equipped with a compressor 10, a flow path switching device 11, flow path switching devices 13a and 13b, and a flow rate adjustment valve 12. The heat source heat exchanger unit 206a is equipped with an expansion device 32a, a heat source heat exchanger 40a, and a heat source blower 41a. The heat source heat exchanger unit 206b is equipped with an expansion device 32b, a heat source heat exchanger 40b, and a heat source blower 41b. At least the heat source heat exchanger unit 206a and the heat source heat exchanger unit 206b are arranged in an air passage duct.

[0095] For example, during the second defrost operation, if frost forms on the heat source heat exchanger 40a serving as an evaporator, the capacity of the heat source heat exchanger 40a decreases. As a result, there is a risk that liquid refrigerant flowing out of the heat source heat exchanger 40a due to poor evaporation may flow into the compressor 10. In contrast, in this modification, the compressor 10 and the heat source heat exchangers 40a, 40b are mounted in separate units, thereby ensuring a large piping volume from each of the heat source heat exchangers 40a, 40b to the compressor 10. As a result, even if the capacity of the heat source heat exchanger serving as an evaporator decreases during the first defrost operation and the second defrost operation, the amount of liquid refrigerant flowing from the heat source heat exchanger to the compressor 10 can be reduced.

[0096] Fig. 10 is a circuit diagram showing a schematic configuration of a refrigeration cycle apparatus according to Modification 3 of the present embodiment during the second defrosting operation. As shown in Fig. 10, a refrigeration cycle apparatus 200 has, as heat source side units, a compressor-mounted unit 205, a relay unit 207, and one or more heat source heat exchanger units 206a, 206b. The circuit configuration in Fig. 10 is the same as the circuit configuration shown in Fig. 7, except that four-way valves are used in the flow path switching devices 13a, 13b.

[0097] The compressor mounting unit 205 is equipped with a compressor 10 and a flow path switching device 11. The relay unit 207 is equipped with flow path switching devices 13a, 13b and a flow rate adjustment valve 12. The heat source heat exchanger unit 206a is equipped with an expansion device 32a, a heat source heat exchanger 40a and a heat source blower 41a. The heat source heat exchanger unit 206b is equipped with an expansion device 32b, a heat source heat exchanger 40b and a heat source blower 41b. At least the heat source heat exchanger units 206a and 206b are arranged in an air passage duct.

[0098] In this modification, heat is retained during heating operation in the piping from the compressor-mounted unit 205 to the relay unit 207, which can be installed in a position closer to the heat load unit 202. This heat can be used for defrosting during defrosting operation, thereby shortening the defrosting time and shortening the time until heating is restored.

[0099] As described above, in the refrigeration cycle apparatus 200 according to this embodiment, the heat source heat exchanger includes the first heat source heat exchanger 40a and the second heat source heat exchanger 40b. The refrigerant circuit includes a first path and a second path as refrigerant paths during heating operation in which the heat load heat exchanger 20 functions as a condenser. The first path is a path from the compressor 10, passing through the flow control valve 12, the heat load heat exchanger 20, the throttling device 31, the throttling device 32a, the first heat source heat exchanger 40a, and the first flow path switching device 13a, and returning to the compressor 10. The second path is a path from the compressor 10, passing through the flow control valve 12, the heat load heat exchanger 20, the throttling device 31, the throttling device 32b, the second heat source heat exchanger 40b, and the second flow path switching device 13b, and returning to the compressor 10. The throttling device 31 is an example of a first throttling device. The throttling device 32a is an example of a second throttling device. The expansion device 32b is an example of a third expansion device.

[0100] The refrigerant circuit has a third path as a refrigerant path during the first defrosting operation in which the first heat source heat exchanger 40a functions as a condenser and the second heat source heat exchanger 40b functions as an evaporator. The third path is a path that runs from the compressor 10 through the first flow switching device 13a, the first heat source heat exchanger 40a, the expansion device 32a, the expansion device 32b, the second heat source heat exchanger 40b, and the second flow switching device 13b and returns to the compressor 10.

[0101] The refrigerant circuit has a fourth path as a refrigerant path during the second defrosting operation in which the second heat source heat exchanger 40b functions as a condenser and the first heat source heat exchanger 40a functions as an evaporator. The fourth path runs from the compressor 10 through the second flow switching device 13b, the second heat source heat exchanger 40b, the expansion device 32b, the expansion device 32a, the first heat source heat exchanger 40a, and the first flow switching device 13a and returns to the compressor 10.

[0102] In the refrigeration cycle apparatus 200 according to this embodiment, the control device 210 fully closes the flow rate adjustment valve 12 and the expansion device 31 during the first defrosting operation and the second defrosting operation.

[0103] According to this configuration, the liquid refrigerant that was present in the heat load heat exchanger 20 during heating operation is trapped between the flow control valve 12 and the expansion device 31 during the first defrost operation and the second defrost operation, and remains in the heat load heat exchanger 20. Therefore, even if the refrigerant pressure in the heat load heat exchanger 20 is higher than the refrigerant discharge pressure of the compressor 10 during the defrost operation, the amount of liquid refrigerant flowing from the heat load heat exchanger 20 into the compressor 10 can be reduced. Therefore, breakdowns in the compressor 10 can be suppressed.

[0104] In the refrigeration cycle device 200 according to this embodiment, the first heat source heat exchanger 40a and the second heat source heat exchanger 40b are mounted in a unit different from the unit (compressor mounted unit 205 or relay unit 207) that mounts the first flow path switching device 13a and the second flow path switching device 13b.

[0105] With this configuration, heat is retained during heating operation in the piping up to the relay unit 207, which can be installed closer to the heat load unit 202. This heat can be used for defrosting during defrosting operation, thereby shortening the defrosting time and shortening the time until heating is restored.

[0106] In the refrigeration cycle apparatus 200 according to this embodiment, the heat source heat exchanger unit has a heat source heat exchanger unit 206a and a heat source heat exchanger unit 206b. The heat source heat exchanger unit 206a is an example of a first sub-unit. The heat source heat exchanger unit 206b is an example of a second sub-unit. The heat source heat exchanger 40a is mounted in the heat source heat exchanger unit 206a. The heat source heat exchanger 40b is mounted in the heat source heat exchanger unit 206b.

[0107] In the refrigeration cycle apparatus 200 according to the present embodiment, air is sent to the heat source heat exchanger 40b during the first defrosting operation, and air is sent to the heat source heat exchanger 40a during the second defrosting operation.

[0108] According to this configuration, the evaporation of the refrigerant is promoted, so that the amount of liquid refrigerant flowing into the compressor 10 can be reduced.

[0109] Embodiment 3 A refrigeration cycle apparatus according to a third embodiment will be described. Fig. 11 is a circuit diagram showing a schematic configuration of the refrigeration cycle apparatus according to this embodiment during heating operation. As shown in Fig. 11, a heat source unit 201 is installed in an air passage duct extending horizontally. The heat source unit 201 has a drain receiver 43 that receives drain water from the heat source heat exchanger 40a and the heat source heat exchanger 40b. The circuit configuration of the refrigeration cycle apparatus 200 is similar to the circuit configuration shown in Fig. 1.

[0110] The heat source unit 201 can be installed not only along an air passage duct extending in the horizontal direction, but also along an air passage duct extending in another direction. In other words, the heat source unit 201 can be installed in at least two or more installation positions so as to be installed along at least two or more airflow directions.

[0111] The heat source unit 201 in FIG. 11 is installed in a horizontally extending air passage duct in an installation position along the horizontal direction. When the heat source unit 201 is installed horizontally, the drain pan 43 is disposed below the heat-source heat exchanger 40a and the heat-source heat exchanger 40b in the direction of gravity. Although not shown, the heat source unit 201 also has a drain pan other than the drain pan 43. When the heat source unit 201 is installed in a vertically extending air passage duct, this drain pan is disposed below the heat-source heat exchanger 40a and the heat-source heat exchanger 40b in the direction of gravity. For example, this drain pan is disposed to the left of the heat-source heat exchanger 40a and the heat-source heat exchanger 40b in FIG. 11. In this way, the heat source unit 201 has multiple drain pans corresponding to two or more installation positions. When the heat source unit 201 is actually installed, some of the drain receivers are not located below the heat source heat exchanger 40a and the heat source heat exchanger 40b in the direction of gravity and do not function as drain receivers. By providing multiple drain receivers redundantly in this way, drain receivers are present below the heat source heat exchanger 40a and the heat source heat exchanger 40b in the direction of gravity regardless of the installation posture of the heat source unit 201.

[0112] Fig. 12 is a circuit diagram showing a schematic configuration of a refrigeration cycle apparatus according to a modified example of this embodiment during heating operation. As shown in Fig. 12, a heat source heat exchanger unit 206 is installed in an air passage duct extending in the vertical direction. The heat source heat exchanger unit 206 has a drain receiver 44a that receives drain water from the heat source heat exchanger 40a and a drain receiver 44b that receives drain water from the heat source heat exchanger 40b. The circuit configuration of the refrigeration cycle apparatus 200 is similar to the circuit configuration shown in Fig. 4.

[0113] The heat source heat exchanger unit 206 can be installed not only along an air passage duct extending in the vertical direction, but also along an air passage duct extending in another direction. That is, the heat source heat exchanger unit 206 can be installed in at least two or more installation positions so as to be installed along at least two or more air flow directions.

[0114] The heat source heat exchanger unit 206 in FIG. 12 is installed in a vertically extending air duct in an installation position along the vertical direction. When the heat source unit 201 is installed vertically, the drain pan 44a is located below the heat source heat exchanger 40a in the direction of gravity. When the heat source unit 201 is installed vertically, the drain pan 44b is located below the heat source heat exchanger 40b in the direction of gravity. Although not shown, the heat source heat exchanger unit 206 has a drain pan other than the drain pans 44a and 44b. When the heat source heat exchanger unit 206 is installed in a horizontally extending air duct, this drain pan is located below the heat source heat exchanger 40a and the heat source heat exchanger 40b in the direction of gravity. For example, in FIG. 12, this drain pan is located to the right of the heat source heat exchanger 40a and the heat source heat exchanger 40b. In this way, the heat source heat exchanger unit 206 has drain receivers on each side of the heat source heat exchanger 40a and the heat source heat exchanger 40b, corresponding to each of the directions in which it can be installed.

[0115] In this modified example, the compressor 10 and the heat-source heat exchangers 40a, 40b are mounted in different unit housings. Therefore, compared to when the compressor 10 and the heat-source heat exchangers 40a, 40b are mounted in the same housing, changing the installation position of the heat-source heat exchanger unit 206 does not require significant changes to the installation of the compressor 10. Therefore, malfunctions of the compressor 10, such as excessive leakage of refrigeration oil, can be suppressed.

[0116] As described above, in the refrigeration cycle apparatus 200 according to this embodiment, the heat source unit 201 can be installed in two or more installation positions. The heat source unit 201 has a plurality of drain receivers 43 that receive drain water from the heat source heat exchangers 40a, 40b corresponding to the two or more installation positions.

[0117] This configuration allows the heat source unit 201 to be installed according to the house where it is to be installed. When air is blown with a vertical airflow, gravity can suppress the scattering of dew after defrosting, thereby suppressing the growth of mold in the duct. Therefore, compared to a configuration that does not use the suppression effect of gravity, the airflow volume can be increased, allowing the low-temperature, high-humidity air that remains after defrosting to be discharged from the duct sooner, thereby shortening the time that heating is stopped. Furthermore, by using a horizontal airflow, the area of ​​the drain receiver 43 can be increased without significantly obstructing the airflow path to the heat source heat exchangers 40a and 40b, thereby suppressing the accumulation of condensation water after defrosting, improving the amount of defrosting per unit time and shortening the defrosting time.

[0118] Embodiment 4 A refrigeration cycle apparatus according to a fourth embodiment will be described. Fig. 13 is a circuit diagram showing a schematic configuration of the refrigeration cycle apparatus according to this embodiment during heating operation. As shown in Fig. 13, a return air duct 306 and an outside air duct 303 are connected by a bypass duct 307. The bypass duct 307 is provided with an opening and closing device 308 that can be opened and closed. The opening and closing device 308 is controlled by the control device 210. As a result, air from the indoor space 301 can be supplied via the return air duct 306 and the bypass duct 307 to the air passage duct on the heat source side that is on the upwind side of the heat source heat exchanger unit 206.

[0119] After defrosting, outdoor air is supplied to the air duct on the heat source side, replacing the air in the air duct on the heat source side. By mixing the air supplied to the air duct on the heat source side with indoor air, the air temperature rises, facilitating the return of heating.

[0120] However, if air from the room is constantly supplied into the air duct on the heat source side during heating operation, the heating load increases and the room temperature drops. For this reason, the opening and closing device 308 is basically fully closed during heating operation. For example, the opening and closing device 308 is limited to the period from the start of defrosting operation until a specific time has passed since the compressor 10 started after the defrosting operation ends. This is effective in restoring heating capacity after defrosting while suppressing an increase in the heating load.

[0121] As described above, the refrigeration cycle apparatus 200 according to this embodiment can supply air from the indoor space 301 of the building 300 to the heat source side air passage duct on the windward side of the heat source heat exchanger unit 206.

[0122] According to this configuration, the air temperature is increased by mixing the indoor air with the air supplied to the air passage duct on the heat source side, thereby facilitating the return of heating. [Explanation of symbols]

[0123] 10 compressor, 11 flow path switching device, 12 flow rate adjustment valve, 13a flow path switching device, 13b flow path switching device, 14a branching section, 14b branching section, 15 branching section, 16 branching section, 18a on-off valve, 18b on-off valve, 20 heat load heat exchanger, 20a heat load heat exchanger, 20b heat load heat exchanger, 21 heat load blower, 31 throttle device (first throttle device), 32 throttle device (second throttle device), 32a throttle device (second throttle device), 32b throttle device (second throttle device, third throttle device), 33 branching section, 40a heat source heat exchanger, 40b heat source heat exchanger, 41 heat source blower, 41a heat source blower, 41b heat source blower, 42 branching section, 43 drain receiver, 44a Drain receiver, 44b drain receiver, 200 refrigeration cycle device, 201 heat source unit (first unit), 201a case, 201b case, 202 heat load unit (second unit), 202a case, 203 gas pipe, 204 liquid pipe, 205 compressor mounted unit, 206 heat source heat exchanger unit (first unit), 206a heat source heat exchanger unit (first sub-unit), 206b heat source heat exchanger unit (second sub-unit), 206c case, 207 relay unit, 210 control device, 300 building, 301 indoor space, 302 ceiling space, 303 outside air duct, 304 exhaust duct, 305 intake air duct, 306 return air duct, 307 bypass duct, 308 switchgear, 309 machine room.

Claims

1. a refrigerant circuit having a compressor, a heat source heat exchanger, and a heat load heat exchanger; a heat source blower that blows air to the heat source heat exchanger; a first unit including the heat source heat exchanger; a control device; Equipped with the first unit is installed in a heat source side air duct of a building, the control device is capable of switching between a first operation in which the heat source heat exchanger functions as an evaporator and a second operation in which the heat source heat exchanger functions as a condenser, The refrigeration cycle apparatus, wherein the control device, when terminating the second operation and starting the first operation, starts the heat source blower before the heat source heat exchanger functions as an evaporator.

2. When the second operation is terminated, the control device temporarily stops the compressor, The refrigeration cycle apparatus according to claim 1 , wherein the control device starts the heat source blower before starting the compressor when starting the first operation.

3. Further, a second unit is provided that includes the heat load heat exchanger; 3. The refrigeration cycle apparatus according to claim 1, wherein the second unit is installed in a heat load-side air passage duct of the building.

4. Further, a second unit is provided that includes the heat load heat exchanger; the refrigerant circuit has a first throttling device and a second throttling device, the second aperture device is mounted on the first unit, The refrigeration cycle apparatus according to claim 1 or 2, wherein the first expansion device is mounted on the second unit.

5. the heat source heat exchanger includes a first heat source heat exchanger and a second heat source heat exchanger, the refrigerant circuit has a first path and a second path as paths of the refrigerant during heating operation in which the heat load heat exchanger functions as a condenser, the first path is a path that runs from the compressor through a flow control valve, the heat load heat exchanger, a first throttle device, a second throttle device, the first heat source heat exchanger, and a first flow path switching device and returns to the compressor, the second path is a path that runs from the compressor through the flow rate control valve, the heat load heat exchanger, the first expansion device, the third expansion device, the second heat source heat exchanger, and a second flow path switching device and returns to the compressor, the refrigerant circuit has a third path as a path of the refrigerant during a first defrosting operation in which the first heat source heat exchanger functions as a condenser and the second heat source heat exchanger functions as an evaporator, the third path is a path that runs from the compressor through the first flow path switching device, the first heat source heat exchanger, the second expansion device, the third expansion device, the second heat source heat exchanger, and the second flow path switching device, and returns to the compressor; The refrigerant circuit has a fourth path as a path of the refrigerant during a second defrosting operation in which the second heat source heat exchanger functions as a condenser and the first heat source heat exchanger functions as an evaporator, 3. The refrigeration cycle apparatus according to claim 1, wherein the fourth path is a path that runs from the compressor through the second flow path switching device, the second heat source heat exchanger, the third throttling device, the second throttling device, the first heat source heat exchanger, and the first flow path switching device, and returns to the compressor.

6. The refrigeration cycle apparatus according to claim 5 , wherein the control device fully closes the flow rate adjustment valve and the first throttle device during the first defrosting operation and the second defrosting operation.

7. The refrigeration cycle apparatus according to claim 5 , wherein the first heat source heat exchanger and the second heat source heat exchanger are mounted in a unit different from a unit in which the first flow path switching device and the second flow path switching device are mounted.

8. the first unit has a first subunit and a second subunit; the first heat source heat exchanger is mounted on the first subunit, The refrigeration cycle apparatus according to claim 5 , wherein the second heat source heat exchanger is mounted on the second sub-unit.

9. During the first defrosting operation, air is sent to the second heat source heat exchanger, The refrigeration cycle apparatus according to claim 5 , wherein air is sent to the first heat source heat exchanger during the second defrosting operation.

10. the first unit can be installed in two or more installation positions; 3. The refrigeration cycle apparatus according to claim 1, wherein the first unit includes a plurality of drain receivers for receiving drain water from the heat source heat exchanger in correspondence with the two or more installation positions.

11. 3. The refrigeration cycle apparatus according to claim 1, wherein air from an indoor space of the building can be supplied to an upstream side of the heat source side air passage duct relative to the first unit.

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