WO2025196994A1 - 空気調和装置 - Google Patents

空気調和装置

Info

Publication number
WO2025196994A1
WO2025196994A1 PCT/JP2024/010894 JP2024010894W WO2025196994A1 WO 2025196994 A1 WO2025196994 A1 WO 2025196994A1 JP 2024010894 W JP2024010894 W JP 2024010894W WO 2025196994 A1 WO2025196994 A1 WO 2025196994A1
Authority
WO
WIPO (PCT)
Prior art keywords
refrigerant
heat exchangers
outdoor heat
operation mode
load
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/JP2024/010894
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
啓人 緒方
尚平 石村
直史 竹中
宗史 池田
傑 鳩村
宏亮 浅沼
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Electric Corp
Original Assignee
Mitsubishi Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Priority to JP2024554927A priority Critical patent/JP7615415B1/ja
Priority to PCT/JP2024/010894 priority patent/WO2025196994A1/ja
Publication of WO2025196994A1 publication Critical patent/WO2025196994A1/ja
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/30—Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
    • F24F11/41—Defrosting; Preventing freezing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B47/00—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
    • F25B47/02—Defrosting cycles

Definitions

  • This disclosure relates to an air conditioning device.
  • a refrigerant circuit is formed by connecting an outdoor unit, which is a heat source installed outside the building, with an indoor unit installed inside the building through pipes, and a refrigerant is circulated through this. The heat dissipation and absorption of the refrigerant is then used to heat and cool the air, thereby heating or cooling the space to be air-conditioned.
  • the heat exchanger installed in the outdoor unit acts as an evaporator, and as heat is exchanged between the low-temperature refrigerant and the air, moisture in the air condenses on the heat exchanger's fins and heat transfer tubes, causing frost to form on the heat exchanger.
  • frost forms on the heat exchanger in this way, the heat exchanger's air passage becomes blocked, reducing the heat transfer area of the heat exchanger that exchanges heat with the air, resulting in a lack of heating capacity.
  • defrosting is typically performed by stopping heating operation, switching the refrigerant flow using a refrigerant flow switching device, and using the heat exchanger installed in the outdoor unit as a condenser.
  • the temperature inside the room drops, reducing comfort.
  • Patent Document 1 describes a method for performing defrosting without stopping heating operation by dividing multiple outdoor heat exchangers with on-off valves and providing an outdoor heat exchanger that performs defrosting and an outdoor heat exchanger that evaporates refrigerant flowing in from the indoor side.
  • Patent Document 1 allows defrosting and heating operations to be performed simultaneously, but the capacity generated by the air conditioning system is not increased; instead, capacity is shared between the outdoor heat exchanger used for defrosting and the outdoor heat exchanger used for heating.
  • capacity is shared between the outdoor heat exchanger used for defrosting and the outdoor heat exchanger used for heating.
  • heating operation is stopped, the refrigerant flow is switched by the refrigerant flow switching device, and then defrosting operation is initiated.
  • the pressure difference between the high-pressure and low-pressure flow paths must be reduced, necessitating a slowdown in the compressor frequency, resulting in the issue of time required to switch between heating and defrosting operations.
  • This disclosure has been made to solve the above-mentioned problems, and aims to provide an air conditioning system that can shorten the time it takes to switch between heating operation and defrosting operation.
  • the air conditioning apparatus comprises a main circuit having a compressor, a refrigerant flow switching device, a plurality of outdoor heat exchangers, a load-side throttling device, and an indoor heat exchanger; a first bypass circuit that guides hot gas discharged from the compressor to each of the plurality of outdoor heat exchangers; a plurality of first opening/closing devices that open and close the first bypass circuit corresponding to each of the plurality of outdoor heat exchangers; and a plurality of second opening/closing devices that open and close the main circuit between the plurality of outdoor heat exchangers and the load-side throttling device corresponding to each of the plurality of outdoor heat exchangers, and is operable to perform cooling operation in which the refrigerant flow switching device is set to a first state and the plurality of outdoor heat exchangers function as condensers, and cooling operation in which the refrigerant flow switching device is set to a second state.
  • the system is capable of performing a heating operation in which the multiple outdoor heat exchangers function as evaporators, and a defrosting operation in which the hot gas is introduced into at least one of the multiple outdoor heat exchangers via the first bypass circuit.
  • the defrosting operation includes a split defrosting operation in which some of the multiple outdoor heat exchangers function as evaporators and the hot gas is introduced into other of the multiple outdoor heat exchangers via the first bypass circuit, and a full defrosting operation in which the hot gas is introduced into all of the multiple outdoor heat exchangers via the first bypass circuit.
  • the refrigerant flow switching device is set to the second state.
  • This disclosure makes it possible to shorten the time required to switch between heating and defrosting operations.
  • FIG. 1 is a refrigerant circuit diagram showing a circuit configuration in a cooling only operation mode of an air conditioning apparatus according to Embodiment 1.
  • FIG. 1 is a refrigerant circuit diagram showing a circuit configuration in a full heating operation mode of an air conditioning apparatus according to Embodiment 1.
  • FIG. 1 is a refrigerant circuit diagram showing a circuit configuration in a split defrosting operation mode of an air conditioning apparatus according to Embodiment 1.
  • FIG. 1 is a refrigerant circuit diagram showing a circuit configuration in a full defrosting operation mode of an air conditioning apparatus according to Embodiment 1.
  • FIG. FIG. 4 is a refrigerant circuit diagram showing a circuit configuration of an air conditioning apparatus according to a modified example of the first embodiment.
  • FIG. 10 is a refrigerant circuit diagram showing the circuit configuration in a cooling only operation mode of an air conditioning apparatus according to a second embodiment.
  • FIG. 10 is a refrigerant circuit diagram showing the circuit configuration in a full heating operation mode of an air conditioning apparatus according to a second embodiment.
  • FIG. 10 is a refrigerant circuit diagram showing a circuit configuration in a split defrosting operation mode of an air conditioner according to a second embodiment.
  • FIG. 10 is a refrigerant circuit diagram showing the circuit configuration in a full defrosting operation mode of an air conditioning apparatus according to a second embodiment.
  • FIG. 11 is a refrigerant circuit diagram showing the circuit configuration in a full cooling operation mode of an air conditioning apparatus according to a third embodiment.
  • FIG. 10 is a refrigerant circuit diagram showing the circuit configuration in a cooling only operation mode of an air conditioning apparatus according to a second embodiment.
  • FIG. 10 is a refrigerant circuit diagram showing the circuit configuration in a full heating operation mode of an air conditioning apparatus
  • FIG. 11 is a refrigerant circuit diagram showing the circuit configuration in a cooling-dominated operation mode of an air conditioning apparatus according to a third embodiment.
  • FIG. 11 is a refrigerant circuit diagram showing the circuit configuration in a full heating operation mode of an air conditioning apparatus according to embodiment 3.
  • FIG. 11 is a refrigerant circuit diagram showing the circuit configuration in a heating-dominated operation mode of an air conditioning apparatus according to Embodiment 3.
  • FIG. 11 is a refrigerant circuit diagram showing a circuit configuration in a split defrosting operation mode of an air conditioning apparatus according to Embodiment 3.
  • FIG. 11 is a refrigerant circuit diagram showing the circuit configuration in a full defrosting operation mode of an air conditioning apparatus according to a third embodiment.
  • FIG. 10 is a refrigerant circuit diagram showing the circuit configuration in a cooling only operation mode of an air conditioning apparatus according to embodiment 4.
  • FIG. 10 is a refrigerant circuit diagram showing the circuit configuration in a cooling-dominated operation mode of an air conditioning apparatus according to embodiment 4.
  • FIG. 10 is a refrigerant circuit diagram showing the circuit configuration in a full heating operation mode of an air conditioning apparatus according to embodiment 4.
  • FIG. 10 is a refrigerant circuit diagram showing the circuit configuration in a heating-dominated operation mode of an air conditioning apparatus according to embodiment 4.
  • FIG. 10 is a refrigerant circuit diagram showing the circuit configuration in a split defrosting operation mode of an air conditioning apparatus according to embodiment 4.
  • FIG. 10 is a refrigerant circuit diagram showing the circuit configuration in a full defrosting operation mode of an air conditioning apparatus according to a fourth embodiment.
  • FIG. 10 is a refrigerant circuit diagram showing the circuit configuration of an air conditioning apparatus according to a fifth embodiment.
  • FIG. 10 is a refrigerant circuit diagram showing the circuit configuration of an air conditioning apparatus according to a sixth embodiment.
  • FIG. 1 is a refrigerant circuit diagram showing the circuit configuration of an air conditioner according to this embodiment in an all-cooling operation mode.
  • the air conditioner 100 circulates refrigerant and performs air conditioning using a refrigeration cycle.
  • the air conditioner 100 can select an all-cooling operation mode, an all-heating operation mode, or a defrosting operation mode.
  • the all-cooling operation mode is an operation mode in which all operating indoor units 2 perform cooling.
  • the all-heating operation mode is an operation mode in which all operating indoor units 2 perform heating.
  • the defrosting operation mode is an operation mode in which the outdoor heat exchangers 12a, 12b in the outdoor unit 1 are defrosted.
  • the defrosting operation modes include a split defrosting operation mode and a all-defrosting operation mode, which will be described later.
  • the air conditioning system 100 has an outdoor unit 1, an indoor unit 2, and main pipes 5a and 5b that connect the outdoor unit 1 and the indoor unit 2.
  • a main circuit 9 is formed that includes a compressor 10, a refrigerant flow switching device 13, multiple outdoor heat exchangers 12a and 12b, a load-side expansion device 25, and an indoor heat exchanger 26.
  • the outdoor unit 1 has a compressor 10 that compresses and discharges a refrigerant.
  • the outdoor unit 1 has multiple outdoor heat exchangers 12a, 12b that exchange heat between the refrigerant and outdoor air.
  • the outdoor unit 1 has a heat source-side blower 18 that supplies outdoor air to the outdoor heat exchangers 12a, 12b. In the outdoor heat exchangers 12a, 12b, the air supplied by the heat source-side blower 18 exchanges heat with the refrigerant, causing the refrigerant to condense or evaporate.
  • the outdoor unit 1 has a refrigerant flow switching device 13 that switches the refrigerant flow path depending on the operating mode.
  • the outdoor unit 1 has an accumulator 19 that accumulates the refrigerant.
  • the outdoor unit 1 has a first bypass circuit 20 that introduces hot gas to melt frost that has formed on the outdoor heat exchangers 12a, 12b.
  • the outdoor unit 1 has a control device 60 that controls various devices.
  • the compressor 10, refrigerant flow switching device 13, outdoor heat exchangers 12a and 12b, opening and closing devices 15a and 15b, and accumulator 19 are connected by refrigerant piping 4.
  • One end of the first bypass circuit 20 is connected to the refrigerant piping 4 between the discharge port of the compressor 10 and the refrigerant flow switching device 13.
  • the other end of the first bypass circuit 20 branches into two flow paths.
  • One flow path is connected between the outdoor heat exchanger 12a and the opening and closing device 15a.
  • the other flow path is connected between the outdoor heat exchanger 12b and the opening and closing device 15b.
  • the first bypass circuit 20 is provided with multiple opening and closing devices 11a and 11b.
  • the opening and closing device 11a is provided in the flow path of the first bypass circuit 20 corresponding to the outdoor heat exchanger 12a.
  • the opening and closing device 11b is provided in the flow path of the first bypass circuit 20 corresponding to the outdoor heat exchanger 12b.
  • the compressor 10 draws in refrigerant and compresses it to a high-temperature, high-pressure state.
  • the compressor 10 is, for example, a capacity-controllable inverter compressor.
  • the compressor 10 is controlled by the control device 60.
  • the refrigerant flow switching device 13 switches the refrigerant flow between the heating only operation mode and the cooling only operation mode.
  • the refrigerant flow switching device 13 is controlled by the control device 60.
  • the outdoor heat exchangers 12a and 12b function as evaporators during the heating only operation mode, and as condensers during the cooling only operation mode and the defrosting operation mode.
  • Accumulator 19 is located on the suction side of compressor 10.
  • Accumulator 19 is a receiver that stores excess refrigerant due to differences in operating conditions between heating only operation mode, cooling only operation mode, and defrosting operation mode, as well as excess refrigerant due to transient changes in operation.
  • the opening and closing devices 11a and 11b allow high-temperature gas refrigerant to flow from the discharge side of the compressor 10 through the refrigerant pipe 4 into the outdoor heat exchangers 12a and 12b during defrosting operation mode.
  • the opening and closing devices 11a and 11b are configured, for example, with two-way valves, solenoid valves, etc.
  • the opening and closing devices 11a and 11b are controlled by the control device 60.
  • One of the opening and closing devices 15a, 15b is closed during the defrosting operation mode, preventing low-pressure two-phase refrigerant from the indoor unit 2 from flowing into the outdoor heat exchangers 12a, 12b during defrosting.
  • the opening and closing devices 15a, 15b may be configured with devices capable of opening and closing the refrigerant flow path, such as a two-way valve, a solenoid valve, or an electronic expansion valve capable of adjusting the flow rate.
  • the opening and closing devices 15a, 15b are controlled by the control device 60.
  • the outdoor unit 1 is equipped with an outdoor heat exchanger temperature sensor 43, a discharge temperature sensor 42, a discharge pressure sensor 40, and an outdoor air temperature sensor 46.
  • the outdoor heat exchanger temperature sensor 43 detects the temperature of the refrigerant flowing out of the outdoor heat exchangers 12a and 12b during heating and defrosting operations, and the temperature of the refrigerant flowing into the outdoor heat exchangers 12a and 12b during cooling operation, and outputs a refrigerant temperature detection signal.
  • the discharge temperature sensor 42 detects the temperature of the refrigerant discharged from the compressor 10 and outputs a refrigerant temperature detection signal.
  • the discharge pressure sensor 40 detects the pressure of the refrigerant discharged from the compressor 10 and outputs a discharge pressure detection signal.
  • the outdoor air temperature sensor 46 is installed in the outdoor unit 1 at the air inlet portion of the outdoor heat exchangers 12a and 12b.
  • the outdoor air temperature sensor 46 detects, for example, the outdoor air temperature, which is the temperature around the outdoor unit 1, and outputs an outdoor air temperature detection signal.
  • the indoor unit 2 has an indoor heat exchanger 26 and a load-side throttle device 25.
  • the indoor heat exchanger 26 is connected to the outdoor unit 1 via main pipes 5a and 5b.
  • air supplied by a load-side blower (not shown) exchanges heat with a refrigerant to generate air for cooling or heating to be supplied to the indoor space.
  • the load-side throttle device 25 can adjust its opening degree, for example, continuously or in multiple stages.
  • an electronic expansion valve is used as the load-side throttle device 25.
  • the load-side throttle device 25 functions as a pressure reducing valve and an expansion valve.
  • the load-side throttle device 25 reduces the pressure of the refrigerant to expand it.
  • the load-side throttle device 25 is located upstream of the indoor heat exchanger 26 in the refrigerant flow in the cooling only operation mode.
  • the indoor unit 2 has a load-side first temperature sensor 31 that detects the temperature of the refrigerant flowing into the indoor heat exchanger 26.
  • the indoor unit 2 has a load-side second temperature sensor 32 that detects the temperature of the refrigerant flowing out from the indoor heat exchanger 26.
  • the load-side first temperature sensor 31 and the load-side second temperature sensor 32 are composed of, for example, a thermistor.
  • the load-side first temperature sensor 31 and the load-side second temperature sensor 32 each output a detection signal to the control device 60.
  • the compressor 10, refrigerant flow switching device 13, indoor heat exchanger 26, load-side expansion device 25, and outdoor heat exchangers 12a and 12b are sequentially connected by piping to form a main circuit 9 through which the refrigerant circulates.
  • a first bypass circuit 20 is formed, which allows high-temperature gas refrigerant discharged from the compressor 10 to flow into the outdoor heat exchangers 12a and 12b to be defrosted via opening and closing devices 11a and 11b.
  • Figure 1 shows one indoor unit 2 as an example. However, two or more indoor units 2 may be connected. Furthermore, two or more outdoor units 1 may be connected in parallel.
  • the air conditioning apparatus 100 has a control device 60 composed of a microcomputer. Based on information detected by various detection means and instructions from a remote control, the control device 60 controls the drive frequency of the compressor 10, the fan rotation speed (including on/off), the switching of the refrigerant flow switching device 13, the opening and closing of the opening and closing devices 11a and 11b, the opening degree of the load-side expansion device 25, etc. This allows the various operating modes described below to be implemented.
  • Figure 1 shows an example in which the control device 60 is installed in the outdoor unit 1, this is not limiting.
  • a control device 60 may be installed in each unit, or in the indoor unit 2. If a control device 60 is installed in each unit, it is recommended that the control devices 60 be connected to each other via wire or wirelessly to enable the exchange of information and to enable coordinated control.
  • ⁇ All cooling operation mode> The cooling-only operation mode executed by the air conditioning apparatus 100 will be described with reference to Fig. 1.
  • the cooling-only operation mode will be described using as an example a case where a cooling load is generated in the indoor heat exchanger 26.
  • the direction of refrigerant flow is indicated by solid arrows.
  • the refrigerant flow switching device 13 is switched to the first state shown by the solid line in Figure 1.
  • the opening and closing devices 11a and 11b are switched to the closed state, blocking the refrigerant.
  • the opening and closing devices 15a and 15b are set to the open state.
  • the low-temperature, low-pressure refrigerant is compressed and discharged as high-temperature, high-pressure gas refrigerant.
  • the high-temperature, high-pressure gas refrigerant discharged from the compressor 10 flows into the outdoor heat exchangers 12a, 12b via the refrigerant flow switching device 13.
  • the high-temperature, high-pressure gas refrigerant that flows into the outdoor heat exchangers 12a, 12b dissipates heat into the outdoor air in the outdoor heat exchangers 12a, 12b, becoming high-pressure liquid refrigerant.
  • the high-pressure liquid refrigerant that flows out of the outdoor heat exchangers 12a, 12b flows out of the outdoor unit 1.
  • the high-pressure liquid refrigerant flowing out of the outdoor unit 1 passes through the main pipe 5b and flows into the indoor unit 2, where it is expanded by the load-side throttle device 25, becoming a low-temperature, low-pressure two-phase refrigerant.
  • This two-phase refrigerant flows into the indoor heat exchanger 26, which functions as an evaporator, and cools the indoor air by absorbing heat from it, becoming a low-temperature, low-pressure gas refrigerant.
  • the gas refrigerant flowing out of the indoor heat exchanger 26 passes through the main pipe 5a and flows back into the outdoor unit 1.
  • the gas refrigerant that flows into the outdoor unit 1 passes through the refrigerant flow switching device 13 and accumulator 19, and is sucked back into the compressor 10.
  • the control device 60 controls the opening of the load-side throttle device 25 so that the superheat (degree of superheat), obtained as the difference between the temperatures detected by the load-side first temperature sensor 31 and the load-side second temperature sensor 32, remains constant.
  • Fig. 2 is a refrigerant circuit diagram showing the circuit configuration of the full heating operation mode of the air conditioner according to this embodiment.
  • the full heating operation mode executed by the air conditioner 100 will be explained based on Fig. 2.
  • the full heating operation mode will be explained using an example in which a heating load is generated in the indoor heat exchanger 26.
  • the direction of refrigerant flow is indicated by solid arrows.
  • the refrigerant flow switching device 13 is switched to the second state shown by the solid line in Figure 2.
  • the opening and closing devices 11a and 11b are switched to the closed state, blocking the refrigerant.
  • the opening and closing devices 15a and 15b are set to the open state.
  • the low-temperature, low-pressure refrigerant When the compressor 10 is driven, the low-temperature, low-pressure refrigerant is compressed and discharged as high-temperature, high-pressure gas refrigerant.
  • the high-temperature, high-pressure gas refrigerant discharged from the compressor 10 flows out of the outdoor unit 1 via the refrigerant flow switching device 13.
  • the high-temperature, high-pressure gas refrigerant flowing out of the outdoor unit 1 passes through the main pipe 5a and flows into the indoor unit 2, where it dissipates heat into the indoor air in the indoor heat exchanger 26, heating the indoor air and becoming liquid refrigerant.
  • the liquid refrigerant flowing out of the indoor heat exchanger 26 is expanded in the load-side throttle device 25 and becomes low-temperature, medium-pressure two-phase refrigerant or liquid refrigerant, and flows back into the outdoor unit 1 through the main pipe 5b.
  • the low-temperature, medium-pressure two-phase refrigerant or liquid refrigerant that flows into the outdoor unit 1 flows into the outdoor heat exchangers 12a, 12b.
  • the refrigerant that flows into the outdoor heat exchangers 12a, 12b absorbs heat from the outdoor air and becomes low-temperature, low-pressure gas refrigerant, which is then sucked back into the compressor 10 via the refrigerant flow switching device 13 and accumulator 19.
  • the control device 60 controls the opening of the load-side throttle device 25 so that the subcooling (degree of supercooling), which is the difference between the value obtained by converting the pressure detected by the discharge pressure sensor 40 into a saturation temperature and the temperature detected by the load-side first temperature sensor 31, is constant.
  • the defrosting operation mode is implemented when the detection result of the outdoor heat exchanger temperature sensor 43, which is provided on the outlet side of the outdoor heat exchangers 12a and 12b, is below a predetermined value. That is, when the detection result of the outdoor heat exchanger temperature sensor 43 is below a predetermined value (for example, approximately ⁇ 10°C or below) during the heating only operation mode, the control device 60 determines that a predetermined amount of frost has formed on the fins of the outdoor heat exchangers 12a and 12b, and implements the defrosting operation mode.
  • a predetermined value for example, approximately ⁇ 10°C or below
  • the outdoor heat exchanger temperature sensor 43 may be provided on the inlet side of the outdoor heat exchangers 12a and 12b, as long as it can measure the refrigerant evaporation temperature of the outdoor heat exchangers 12a and 12b during the heating only operation mode.
  • Frost formation may also be determined by other methods, such as when the saturation temperature converted from the suction pressure of the compressor 10 drops significantly compared to a preset outside air temperature, or when the temperature difference between the outside air temperature and the evaporation temperature remains above a preset value for a certain period of time.
  • the defrosting operation modes in this embodiment include a split defrosting operation mode and a full defrosting operation mode.
  • the split defrosting operation mode is an operation mode in which some of the multiple outdoor heat exchangers 12a, 12b are defrosted.
  • the full defrosting operation mode is an operation mode in which all of the multiple outdoor heat exchangers 12a, 12b are defrosted.
  • Figure 3 is a refrigerant circuit diagram showing the circuit configuration of the split defrost operation mode of the air conditioning apparatus according to this embodiment.
  • the refrigerant flow direction is indicated by solid arrows.
  • Figure 3 shows the split defrost operation mode when defrosting the outdoor heat exchanger 12b.
  • the refrigerant flow path switching device 13 is maintained in the same second state as in the heating operation mode. Opening and closing device 11a is set to the closed state, opening and closing device 11b is set to the open state, opening and closing device 15a is set to the open state, and opening and closing device 15b is set to the closed state.
  • the refrigerant discharged from the compressor 10 is divided into refrigerant that flows into the first bypass circuit 20 and refrigerant that flows into the indoor unit 2.
  • the refrigerant that flows into the first bypass circuit 20 passes through the opening and closing device 11b and flows into the outdoor heat exchanger 12b, where it is defrosted. After defrosting, the refrigerant merges with the refrigerant that has passed through the outdoor heat exchanger 12a just before the refrigerant flow switching device 13, passes through the refrigerant flow switching device 13, passes through the accumulator 19, and is drawn into the compressor 10.
  • the refrigerant flowing to the indoor unit 2 passes through the refrigerant flow switching device 13, the indoor heat exchanger 26, and the load-side throttle device 25 before returning to the outdoor unit 1.
  • the refrigerant returning to the outdoor unit 1 passes through the opening and closing device 15a, flows into the outdoor heat exchanger 12a, and evaporates.
  • the evaporated refrigerant merges with the refrigerant flowing out from the outdoor heat exchanger 12b just before the refrigerant flow switching device 13. In this way, in the split defrost operation mode, some outdoor heat exchangers 12b are defrosted, while heating continues using the other outdoor heat exchangers 12a as the heat source-side heat exchanger.
  • the determination of whether to end the split defrost operation mode is made using a timer. That is, if the execution time of the split defrost operation exceeds the threshold time, the control device 60 ends the split defrost operation mode and resumes the heating operation mode. However, if it is determined based on the outdoor air temperature sensor 46 or the outdoor heat exchanger temperature sensor 43 that defrosting is not complete, the split defrost operation mode is switched to the full defrost operation mode. This increases the defrosting capacity and shortens the defrosting time.
  • FIG. 4 is a refrigerant circuit diagram showing the circuit configuration of the air conditioner according to this embodiment in the full defrost operation mode.
  • the direction of refrigerant flow is indicated by solid arrows.
  • the refrigerant flow switching device 13 is maintained in the second state, the same as in the heating operation mode, and the load-side expansion device 25 is switched to a closed state to block the refrigerant.
  • the opening and closing devices 11a and 11b are switched to an open state to allow the refrigerant to flow.
  • the heat-source-side blower 18 and a load-side blower (not shown) are stopped. Furthermore, by switching the opening and closing devices 11a and 11b to an open state and then closing the load-side expansion device 25, blockage of the refrigerant flow path can be prevented, and pressure increases can be suppressed.
  • the high-temperature, high-pressure gas refrigerant discharged from compressor 10 is decompressed by opening and closing devices 11a, 11b to a temperature above 0°C (converted to saturation temperature) and flows into outdoor heat exchangers 12a, 12b.
  • the high-temperature gas refrigerant that flows into outdoor heat exchangers 12a, 12b melts the frost adhering to outdoor heat exchangers 12a, 12b, becoming low-temperature gas refrigerant, low-quality two-phase refrigerant, or liquid refrigerant, and flows into accumulator 19 via refrigerant flow switching device 13.
  • the liquid refrigerant remains in accumulator 19, while the gas refrigerant flows into the suction section of compressor 10.
  • the defrosting of the outdoor heat exchangers 12a, 12b can be determined to be complete when, for example, a predetermined time has elapsed, or when the temperature of the outdoor heat exchanger temperature sensor 43 reaches a predetermined value or higher (e.g., 5°C).
  • the predetermined time should be set to at least the time required for all the frost to melt when high-temperature, high-pressure refrigerant is introduced, assuming that frost has formed on the entire outdoor heat exchangers 12a, 12b without any gaps.
  • the high-temperature, high-pressure gas refrigerant discharged from the compressor 10 is decompressed by the opening and closing devices 11a and 11b to a temperature above 0°C, converted to a saturation temperature.
  • the size of the opening and closing devices 11a and 11b is small compared to the amount of gas refrigerant circulating, the pressure of the high-pressure gas refrigerant discharged from the compressor 10 will excessively increase.
  • the size of the opening and closing devices 11a and 11b is selected according to the amount of gas refrigerant circulating in the split defrost operation mode and full defrost operation mode, so that the pressure of the high-pressure gas refrigerant is lower than the operating pressure of the compressor 10. For example, if R410A refrigerant is used and the design pressure is 4.15 MPa, the size of the opening and closing devices 11a and 11b is selected so that the operating pressure is 3.8 MPa or less, lower than 4.15 MPa, taking pressure overshoot into consideration.
  • the split defrost operation mode and full defrost operation mode there may be heat transfer tube paths where frost is difficult to melt due to differences in the amount of frost formed on each path of the heat transfer tubes of the outdoor heat exchangers 12a and 12b or differences in the refrigerant flow rate in each path.
  • the temperature of the gas refrigerant flowing out of the outdoor heat exchangers 12a and 12b rises above 0°C, the frost melting point, and the temperature of the refrigerant drawn into the compressor 10 rises, causing the temperature of the refrigerant discharged from the compressor 10 to rise excessively.
  • an upper limit (e.g., 120°C) is set for the discharge temperature of the compressor 10.
  • a predetermined discharge temperature value e.g., 110°C
  • the frequency of the compressor 10 is reduced to lower the temperature of the refrigerant discharged from the compressor 10 so that the discharge temperature of the compressor 10 does not exceed the upper limit.
  • ⁇ Modification of First Embodiment> 5 is a refrigerant circuit diagram showing the circuit configuration of an air conditioner according to a modified example of the present embodiment.
  • opening and closing devices 11a and 11b are configured as electronic expansion valves capable of adjusting the refrigerant flow rate.
  • the opening degrees of opening and closing devices 11a and 11b are adjusted so that the pressure of the gas refrigerant discharged from compressor 10 is a predetermined pressure (e.g., 3.0 MPa).
  • a predetermined pressure e.g. 3.0 MPa
  • the opening degrees of opening and closing devices 11a and 11b are increased.
  • opening and closing devices 11a and 11b as electronic expansion valves capable of adjusting the refrigerant flow rate and adjusting the operating pressure of the gas refrigerant discharged from compressor 10, the increase in pressure can be suppressed, enabling stable defrosting operation.
  • the air conditioning apparatus 100 comprises a main circuit 9, a first bypass circuit 20, multiple opening and closing devices 11a, 11b, and multiple opening and closing devices 15a, 15b.
  • the main circuit 9 comprises a compressor 10, a refrigerant flow switching device 13, multiple outdoor heat exchangers 12a, 12b, a load-side expansion device 25, and an indoor heat exchanger 26.
  • the first bypass circuit 20 guides hot gas discharged from the compressor 10 to each of the multiple outdoor heat exchangers 12a, 12b.
  • the multiple opening and closing devices 11a, 11b are provided in the first bypass circuit 20 corresponding to each of the multiple outdoor heat exchangers 12a, 12b.
  • the multiple opening and closing devices 11a, 11b open and close the first bypass circuit 20 corresponding to each of the multiple outdoor heat exchangers 12a, 12b.
  • the multiple opening and closing devices 15a, 15b correspond to the multiple outdoor heat exchangers 12a, 12b, respectively, and are provided in the main circuit 9 between the multiple outdoor heat exchangers 12a, 12b and the load-side expansion device 25.
  • the multiple opening and closing devices 15a, 15b correspond to the multiple outdoor heat exchangers 12a, 12b, respectively, and open and close the main circuit 9 between the multiple outdoor heat exchangers 12a, 12b and the load-side expansion device 25.
  • the multiple opening and closing devices 11a, 11b are an example of a first opening and closing device.
  • the multiple opening and closing devices 15a, 15b are an example of a second opening and closing device.
  • the air conditioning apparatus 100 is capable of performing cooling operation, heating operation, and defrosting operation.
  • cooling operation the refrigerant flow switching device 13 is set to a first state, and the multiple outdoor heat exchangers 12a, 12b function as condensers.
  • heating operation the refrigerant flow switching device 13 is set to a second state, and the multiple outdoor heat exchangers 12a, 12b function as evaporators.
  • defrosting operation hot gas is introduced into at least one of the multiple outdoor heat exchangers 12a, 12b via the first bypass circuit 20.
  • Defrosting operations include split defrosting operation and full defrosting operation.
  • split defrosting operation some of the multiple outdoor heat exchangers 12a, 12b function as evaporators, and hot gas is introduced into the other outdoor heat exchangers of the multiple outdoor heat exchangers 12a, 12b via the first bypass circuit 20.
  • full defrost operation hot gas is introduced into all of the outdoor heat exchangers 12a, 12b via the first bypass circuit 20.
  • the refrigerant flow switching device is set to the second state.
  • the refrigerant flow path switching device 13 is maintained in the second state when switching from heating operation to defrosting operation, when switching from one of split defrosting operation and defrosting operation to the other during defrosting operation, and when switching from defrosting operation to heating operation.
  • defrosting operation can be started promptly after heating operation has ended, and heating operation can be started promptly after defrosting operation has ended. This shortens the time that heating is stopped, improving user comfort.
  • the ability to select between split defrosting operation and full defrosting operation allows for efficient heating and defrosting.
  • the air conditioning apparatus 100 further includes a control device 60 that controls the refrigerant flow switching device 13.
  • the control device 60 switches to split defrosting operation if the outside air temperature is equal to or higher than the threshold temperature, and switches to full defrosting operation if the outside air temperature is below the threshold temperature. This configuration allows for efficient defrosting.
  • Embodiment 2 An air conditioning apparatus according to embodiment 2 will be described below. In embodiment 2, only the changes from embodiment 1 will be described.
  • ⁇ Configuration of outdoor unit 1> 6 is a refrigerant circuit diagram showing the circuit configuration of an air conditioner in a cooling-only operation mode according to the present embodiment.
  • a second bypass circuit 21 is provided that connects the flow path between the outdoor heat exchanger 12a and the opening/closing device 15a and the flow path between the outdoor heat exchanger 12b and the refrigerant flow switching device 13.
  • An opening/closing valve 16 is provided in the second bypass circuit 21.
  • An opening/closing valve 17 is provided in the flow path between the second bypass circuit 21 and the refrigerant flow switching device 13. The opening/closing valves 16 and 17 are controlled by a control device 60.
  • the refrigerant flow switching device 13 is set to the first state, as in Embodiment 1.
  • the on-off valve 16 is open, the on-off valve 17 is closed, the on-off device 15a is closed, and the on-off device 15b is open.
  • the refrigerant that has passed through the refrigerant flow switching device 13 exchanges heat with outside air in the outdoor heat exchanger 12a, passes through the on-off valve 16, passes through the outdoor heat exchanger 12b, passes through the on-off device 15b, and flows to the indoor unit 2.
  • ⁇ Full heating operation mode> 7 is a refrigerant circuit diagram showing the circuit configuration of the air conditioner according to this embodiment in the full heating operation mode.
  • the refrigerant flow switching device 13 is set to the second state, as in the first embodiment.
  • the on-off valve 16 is closed and the on-off valve 17 is open.
  • the refrigerant flowing from the indoor unit 2 is split and flows into the on-off device 15a and the on-off device 15b.
  • ⁇ Split defrost operation mode> 8 is a refrigerant circuit diagram showing the circuit configuration in the split defrost operation mode of an air conditioner according to the present embodiment.
  • the refrigerant flow path switching device 13 is set to the second state, as in embodiment 1.
  • the on-off valve 16 is closed and the on-off valve 17 is closed.
  • the refrigerant flow in the split defrost operation mode is the same as in embodiment 1.
  • ⁇ Full defrost operation mode> 9 is a refrigerant circuit diagram showing the circuit configuration in the full defrost operation mode of an air conditioner according to the present embodiment.
  • the refrigerant flow switching device 13 is set to the second state as in embodiment 1.
  • the on-off valve 16 is closed and the on-off valve 17 is closed.
  • the refrigerant flow in the full defrost operation mode is the same as in embodiment 1.
  • the air conditioning apparatus 100 further includes a second bypass circuit 21 and an on-off valve 16.
  • the second bypass circuit 21 connects the main circuit 9 between some of the outdoor heat exchangers 12a and the on-off devices 15a corresponding to the outdoor heat exchangers 12a, and the main circuit 9 between the other outdoor heat exchangers 12b and the refrigerant flow switching device 13.
  • the on-off valve 16 is provided in the second bypass circuit 21 and opens and closes the second bypass circuit 21. In cooling operation, multiple outdoor heat exchangers 12a, 12b are connected in series, and in heating operation, multiple outdoor heat exchangers 12a, 12b are connected in parallel.
  • the outdoor heat exchangers 12a, 12b through which high-pressure refrigerant flows are connected in series. This increases the refrigerant flow rate in the heat transfer tubes of the outdoor heat exchangers 12a, 12b, thereby promoting heat transfer. Furthermore, during heating operation, the outdoor heat exchangers 12a, 12b through which low-pressure refrigerant flows are connected in parallel. This decreases the refrigerant flow rate in the heat transfer tubes of the outdoor heat exchangers 12a, 12b, thereby reducing pressure loss.
  • FIG. 10 is a refrigerant circuit diagram showing the circuit configuration of an air conditioner according to this embodiment in cooling only operation mode. Components having the same functions and actions as those in embodiment 1 or 2 will be assigned the same reference numerals and their description will be omitted.
  • the air conditioning system 200 comprises one outdoor unit 1, which is a heat source unit, multiple indoor units 2a, 2b, 2c, and 2d, and a relay unit 3 installed between the outdoor unit 1 and the indoor units 2a to 2d.
  • the outdoor unit 1 and the relay unit 3 are connected by multiple main pipes 5a and 5b through which a refrigerant flows.
  • the relay unit 3 and each of the indoor units 2a to 2d are connected by multiple branch pipes 8a and 8b through which a refrigerant flows.
  • the cold or hot heat generated by the outdoor unit 1 is supplied to each of the indoor units 2a to 2d via the relay unit 3.
  • the outdoor unit 1 and the relay unit 3 are connected using two main pipes 5a and 5b, and the relay unit 3 and each of the indoor units 2a to 2d are connected using two branch pipes 8a and 8b.
  • the outdoor unit 1 and the relay unit 3, and the relay unit 3 and the indoor units 2a to 2d are connected using two pipes each, making it easy to install the air conditioning unit 200.
  • the outdoor unit 1 includes a compressor 10, a refrigerant flow switching device 13, outdoor heat exchangers 12a and 12b, an accumulator 19, opening and closing devices 11a and 11b, opening and closing devices 15a and 15b, and a heat source side blower 18.
  • the compressor 10, the refrigerant flow switching device 13, the outdoor heat exchangers 12a and 12b, the accumulator 19, opening and closing devices 11a and 11b, and opening and closing devices 15a and 15b are connected by refrigerant piping 4.
  • the outdoor unit 1 is provided with a first connecting pipe 22a, a second connecting pipe 22b, and backflow prevention devices 14a, 14b, 14c, and 14d.
  • backflow prevention devices 14a, 14b, 14c, and 14d are used as the backflow prevention devices 14a to 14d.
  • the first connection pipe 22a and the second connection pipe 22b are connected as follows for the refrigerant flow in the cooling only operation mode and the cooling main operation mode.
  • One end of the first connection pipe 22a is connected to a refrigerant pipe downstream of the outdoor heat exchangers 12a, 12b and the opening and closing devices 15a, 15b and upstream of the main pipe 5b.
  • the other end of the first connection pipe 22a is connected to a refrigerant pipe downstream of the main pipe 5a and upstream of the refrigerant flow switching device 13.
  • One end of the second connection pipe 22b is connected to a refrigerant pipe downstream of the outdoor heat exchangers 12a, 12b and the opening and closing devices 15a, 15b and upstream of one end of the first connection pipe 22a.
  • the other end of the second connection pipe 22b is connected to a refrigerant pipe downstream of the main pipe 5a and upstream of the other end of the first connection pipe 22a.
  • the backflow prevention device 14a is provided on the refrigerant piping between one end of the first connecting piping 22a and one end of the second connecting piping 22b.
  • the backflow prevention device 14a prevents high-temperature, high-pressure gas refrigerant from flowing back from the first connecting piping 22a to the outdoor heat exchangers 12a and 12b in the heating only operation mode and the heating-dominant operation mode.
  • the backflow prevention device 14b is provided on the first connecting pipe 22a.
  • the backflow prevention device 14b prevents high-pressure liquid or gas-liquid two-phase refrigerant from flowing back from the refrigerant pipe on the outlet side of the backflow prevention device 14a to the accumulator 19 during cooling only operation mode and cooling dominant operation mode.
  • the backflow prevention device 14c is provided on the second connecting pipe 22b.
  • the backflow prevention device 14c prevents high-pressure liquid or gas-liquid two-phase refrigerant from flowing back from the refrigerant pipe on the inlet side of the backflow prevention device 14a to the accumulator 19 during cooling only operation mode and cooling main operation mode.
  • the backflow prevention device 14d is provided on the refrigerant piping between the other end of the first connecting piping 22a and the other end of the second connecting piping 22b.
  • the backflow prevention device 14d prevents high-temperature, high-pressure gas refrigerant from flowing back into the main pipe 5a from the flow path on the discharge side of the compressor 10 during heating only operation mode and heating-dominant operation mode.
  • backflow prevention devices 14a-14d By providing backflow prevention devices 14a-14d, the flow of refrigerant flowing into the relay unit 3 can be made to flow in a constant direction regardless of the operation required by the indoor unit 2.
  • check valves are used as the backflow prevention devices 14a-14d, but the configuration of the backflow prevention devices 14a-14d is not limited to this as long as they are capable of preventing the backflow of refrigerant.
  • opening and closing devices or throttling devices with a fully closing function can also be used as the backflow prevention devices 14a-14d.
  • the multiple indoor units 2a to 2d have, for example, the same configuration.
  • the indoor unit 2a is equipped with an indoor heat exchanger 26a and a load-side throttle device 25a.
  • the indoor unit 2b is equipped with an indoor heat exchanger 26b and a load-side throttle device 25b.
  • the indoor unit 2c is equipped with an indoor heat exchanger 26c and a load-side throttle device 25c.
  • the indoor unit 2d is equipped with an indoor heat exchanger 26d and a load-side throttle device 25d.
  • Each of the indoor heat exchangers 26a-26d is connected to the outdoor unit 1 via branch pipes 8a, 8b, relay unit 3, and main pipes 5a, 5b.
  • heat is exchanged between the air supplied by a load-side blower (not shown) and the refrigerant to generate air for heating or cooling to be supplied to the indoor space.
  • the load-side throttle devices 25a-25d are capable of variably adjusting their opening, for example, continuously or in multiple stages. Electronic expansion valves, for example, are used as the load-side throttle devices 25a-25d.
  • the load-side throttle devices 25a-25d function as both pressure-reducing valves and expansion valves, reducing the pressure of the refrigerant and expanding it.
  • the load-side throttle devices 25a-25d are located upstream of the indoor heat exchangers 26a-26d in the refrigerant flow during cooling operation mode (for example, full cooling operation mode).
  • the indoor units 2a to 2d are provided with first load-side temperature sensors 31a, 31b, 31c, and 31d and second load-side temperature sensors 32a, 32b, 32c, and 32d.
  • the first load-side temperature sensors 31a to 31d detect the temperature of the refrigerant flowing into each of the indoor heat exchangers 26a to 26d.
  • the second load-side temperature sensors 32a to 32d detect the temperature of the refrigerant flowing out of each of the indoor heat exchangers 26a to 26d.
  • the first load-side temperature sensors 31a to 31d and the second load-side temperature sensors 32a to 32d are composed of, for example, a thermistor.
  • Each of the first load-side temperature sensors 31a to 31d and the second load-side temperature sensors 32a to 32d outputs a detection signal to the control device 60.
  • Figure 10 shows four indoor units 2a to 2d as an example, the number of connected indoor units may be two, three, five or more.
  • the relay unit 3 has a gas-liquid separator 29, a first relay throttling device 30, a second relay throttling device 27, a plurality of relay first opening/closing devices 23a, 23b, 23c, and 23d, and a plurality of relay second opening/closing devices 24a, 24b, 24c, and 24d.
  • the gas-liquid separator 29 separates the high-pressure two-phase gas-liquid refrigerant generated in the outdoor unit 1 into liquid refrigerant and gas refrigerant.
  • the gas-liquid separator 29 allows the separated liquid refrigerant to flow into the lower piping in the figure, supplying cold heat to some of the indoor units, and allows the separated gas refrigerant to flow into the upper piping in the figure, supplying hot heat to some of the other indoor units.
  • the gas-liquid separator 29 is located at the inlet of the relay unit 3 in the refrigerant flow.
  • the first intermediate throttle device 30 functions as a pressure reducing valve and an on-off valve.
  • the first intermediate throttle device 30 reduces the pressure of the liquid refrigerant to a predetermined pressure, and opens and closes the flow path of the liquid refrigerant.
  • the first intermediate throttle device 30 is capable of variably adjusting its opening, for example, continuously or in multiple stages.
  • An electronic expansion valve for example, is used as the first intermediate throttle device 30.
  • the first intermediate throttle device 30 is installed in the pipe through which the liquid refrigerant flows out from the gas-liquid separator 29.
  • the second intermediate throttling device 27 functions as a pressure reducing valve and an on-off valve.
  • the second intermediate throttling device 27 opens and closes the refrigerant flow path in heating only operation mode, and adjusts the bypass liquid flow rate according to the indoor load in heating main operation mode.
  • the second intermediate throttling device 27 is capable of variably adjusting its opening, for example, continuously or in multiple stages.
  • An electronic expansion valve for example, is used as the second intermediate throttling device 27.
  • the second intermediate throttling device 27 is located on the inlet side of the low-pressure flow path in heating only operation mode and heating main operation mode.
  • relay unit first opening and closing devices 23a-23d are provided, one for each of the multiple indoor units 2a-2d (a total of four in this example).
  • the relay unit first opening and closing devices 23a-23d open and close the flow path of the high-temperature, high-pressure gas refrigerant supplied to the indoor units 2a-2d, respectively.
  • the relay unit first opening and closing devices 23a-23d are configured, for example, with solenoid valves.
  • the relay unit first opening and closing devices 23a-23d are each connected to the gas-side piping of the gas-liquid separator 29. Note that the relay unit first opening and closing devices 23a-23d only need to be able to open and close the flow path, and may also be a throttling device with a full-closing function.
  • Repeater second opening and closing devices 24a-24d are provided, one for each of the multiple indoor units 2a-2d (a total of four in this example).
  • the repeater second opening and closing devices 24a-24d open and close the flow path of the low-temperature, low-pressure gas refrigerant flowing out of the indoor units 2a-2d, respectively.
  • the repeater second opening and closing devices 24a-24d are configured, for example, with solenoid valves.
  • the repeater second opening and closing devices 24a-24d are each connected to a low-pressure pipe that leads to the outlet side of the repeater 3.
  • the repeater second opening and closing devices 24a-24d only need to be able to open and close the flow path, and may also be a throttling device with a full-closing function.
  • an inlet pressure sensor 33 is provided on the inlet side of the first relay throttling device 30 in the relay unit 3.
  • the inlet pressure sensor 33 detects the pressure of the high-pressure refrigerant.
  • An outlet pressure sensor 34 is provided on the outlet side of the first relay throttling device 30. The outlet pressure sensor 34 detects the intermediate pressure of the liquid refrigerant on the outlet side of the first relay throttling device 30 in the cooling-dominated operation mode.
  • the control device 60 also controls the operation of the entire air conditioning device 200 based on detection signals from various sensors and instructions from a remote controller. For example, the control device 60 controls the drive frequency of the compressor 10, the fan rotation speed (including on and off), the switching of the refrigerant flow switching device 13, the opening and closing of the opening and closing devices 11a and 11b, the opening degree of the load-side expansion device 25, and the opening and closing of the first relay opening and closing devices 23a-23d. The control device 60 also controls the opening and closing of the second relay opening and closing devices 24a-24d, the opening and closing of the first relay expansion device 30, and the opening and closing of the second relay expansion device 27, among other things. This allows the various operating modes described below to be implemented.
  • control device 60 in this example is provided in the outdoor unit 1, the control device 60 may also be provided in the indoor units 2a-2d, the relay unit 3, or for each unit (e.g., the outdoor unit 1, the indoor units 2a-2d, and the relay unit 3).
  • the control device 60 is capable of independently performing cooling or heating operation on each of the indoor units 2a to 2d based on instructions from each of the indoor units 2a to 2d.
  • the air conditioning unit 200 can perform the same operation (cooling or heating) on all of the indoor units 2a to 2d, and can also perform different operations on each of the indoor units 2a to 2d.
  • Cooling operation mode includes an all-cooling operation mode and a cooling-dominated operation mode.
  • Heating operation mode includes an all-heating operation mode and a heating-dominated operation mode.
  • the full cooling operation mode is an operation mode in which all of the indoor units 2a to 2d that are not stopped perform cooling operation. In other words, in the full cooling operation mode, all of the indoor heat exchangers 26a to 26d that are not stopped function as evaporators.
  • the cooling-dominated operation mode is a mixed cooling and heating operation mode in which some of the indoor units 2a to 2d perform cooling operation and some of the other indoor units 2a to 2d perform heating operation, and is an operation mode in which the cooling load is greater than the heating load. In other words, in the cooling-dominated operation mode, some of the indoor heat exchangers 26a to 26d function as evaporators, and some of the other indoor heat exchangers 26a to 26d function as condensers.
  • the full heating operation mode is an operation mode in which all of the indoor units 2a to 2d that are not stopped perform heating operation. In other words, in the full heating operation mode, all of the indoor heat exchangers 26a to 26d that are not stopped function as condensers.
  • the heating-dominated operation mode is a mixed cooling and heating operation mode in which some of the indoor units 2a to 2d perform cooling operation and some of the indoor units 2a to 2d perform heating operation, and in which the heating load is greater than the cooling load. Each operation mode is explained below.
  • ⁇ All cooling operation mode> The cooling-only operation mode executed by the air conditioning apparatus 200 will be described with reference to Fig. 10.
  • the cooling-only operation mode will be described using an example in which a cooling load is generated only in the indoor heat exchanger 26a and the indoor heat exchanger 26b. Note that in Fig. 9, the direction of refrigerant flow is indicated by solid arrows.
  • control device 60 switches the refrigerant flow switching device 13 of the outdoor unit 1 to a first state in which the refrigerant discharged from the compressor 10 flows into the outdoor heat exchangers 12a and 12b.
  • low-temperature, low-pressure refrigerant is compressed by compressor 10 and becomes high-temperature, high-pressure gas refrigerant, which is then discharged.
  • the high-temperature, high-pressure gas refrigerant discharged from compressor 10 flows into outdoor heat exchangers 12a, 12b via refrigerant flow switching device 13. It then becomes high-pressure liquid refrigerant in outdoor heat exchangers 12a, 12b while dissipating heat to the outdoor air.
  • the high-pressure liquid refrigerant flowing out of outdoor heat exchangers 12a, 12b passes through backflow prevention device 14a, leaves outdoor unit 1, and flows into relay unit 3 through main pipe 5b.
  • the high-pressure liquid refrigerant that flows into the relay unit 3 passes through the gas-liquid separator 29, the first relay throttle device 30, and the branch pipe 8b, and is expanded by the load-side throttle devices 25a and 25b, becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant.
  • the gas-liquid two-phase refrigerant expanded by the load-side throttle devices 25a, 25b flows into the indoor heat exchangers 26a, 26b, which act as evaporators, and becomes a low-temperature, low-pressure gas refrigerant by absorbing heat from the indoor air, cooling it.
  • the opening of the load-side throttle device 25a is controlled so that the superheat obtained as the difference between the temperature detected by the load-side first temperature sensor 31a and the temperature detected by the load-side second temperature sensor 32a remains constant.
  • the opening of the load-side throttle device 25b is controlled so that the superheat obtained as the difference between the temperature detected by the load-side first temperature sensor 31b and the temperature detected by the load-side second temperature sensor 32b remains constant.
  • the gas refrigerant flowing out of the indoor heat exchangers 26a and 26b passes through the branch pipe 8a and the second relay opening/closing devices 24a and 24b, flows out of the relay unit 3, and flows back into the outdoor unit 1 through the main pipe 5a.
  • the refrigerant that flows into the outdoor unit 1 passes through the backflow prevention device 14d, the refrigerant flow switching device 13, and the accumulator 19, before being sucked back into the compressor 10.
  • indoor heat exchanger 26c and indoor heat exchanger 26d which have no heat load, there is no need to flow refrigerant, and the corresponding load-side expansion device 25c and load-side expansion device 25d are closed.
  • load-side expansion device 25c or load-side expansion device 25d is opened and the refrigerant circulates.
  • the opening degree of the load-side expansion device is controlled, similar to the load-side expansion device 25a or load-side expansion device 25b described above, so that the superheat, obtained as the difference between the temperature detected by the load-side first temperature sensor and the temperature detected by the load-side second temperature sensor, remains constant.
  • Fig. 11 is a refrigerant circuit diagram showing the circuit configuration of the air conditioner in cooling-dominated operation mode according to this embodiment.
  • the direction of refrigerant flow is indicated by solid arrows.
  • a cooling load is generated only in indoor heat exchanger 26a, and a heating load is generated only in indoor heat exchanger 26b.
  • control device 60 switches the refrigerant flow switching device 13 to a first state in which the refrigerant discharged from the compressor 10 flows into the outdoor heat exchangers 12a and 12b.
  • low-temperature, low-pressure refrigerant is compressed by compressor 10 and discharged as high-temperature, high-pressure gas refrigerant.
  • the high-temperature, high-pressure gas refrigerant discharged from compressor 10 flows into outdoor heat exchangers 12a, 12b via refrigerant flow switching device 13.
  • the refrigerant then dissipates heat into the outdoor air in outdoor heat exchangers 12a, 12b, becoming a two-phase gas-liquid refrigerant.
  • the refrigerant flowing out of outdoor heat exchangers 12a, 12b passes through backflow prevention device 14a and main pipe 5b and flows into relay unit 3.
  • the gas-liquid two-phase refrigerant that flows into the relay unit 3 is separated into high-pressure gas refrigerant and high-pressure liquid refrigerant in the gas-liquid separator 29.
  • This high-pressure gas refrigerant passes through the relay unit first opening/closing device 23b and branch pipe 8a before flowing into the indoor heat exchanger 26b, which acts as a condenser.
  • the high-pressure gas refrigerant radiates heat to the indoor air, heating it and turning into liquid refrigerant.
  • the opening of the load-side throttle device 25b is controlled so that the subcooling, obtained as the difference between the value obtained by converting the pressure detected by the inlet-side pressure sensor 33 into a saturation temperature, and the temperature detected by the load-side first temperature sensor 31b, remains constant.
  • the liquid refrigerant flowing out of the indoor heat exchanger 26b is expanded by the load-side throttle device 25b and flows through the branch pipe 8b.
  • the medium-pressure liquid refrigerant that has been separated in the gas-liquid separator 29 and then expanded to intermediate pressure in the first intermediate throttle device 30 merges with the liquid refrigerant that has passed through the load-side throttle device 25b.
  • the opening of the first intermediate throttle device 30 is controlled so that the pressure difference between the pressure detected by the inlet-side pressure sensor 33 and the pressure detected by the outlet-side pressure sensor 34 is a predetermined pressure difference (e.g., 0.3 MPa).
  • the merged liquid refrigerant flows into the indoor unit 2a via branch pipe 8b.
  • the two-phase gas-liquid refrigerant expanded by the load-side throttle device 25a of the indoor unit 2a flows into the indoor heat exchanger 26a, which acts as an evaporator, and becomes a low-temperature, low-pressure gas refrigerant by absorbing heat from the indoor air, cooling it.
  • the opening of the load-side throttle device 25a is controlled so that the superheat, obtained as the difference between the temperature detected by the load-side first temperature sensor 31a and the load-side second temperature sensor 32a, remains constant.
  • the gas refrigerant flowing out of the indoor heat exchanger 26a flows through branch pipe 8a and the relay unit second opening/closing device 24a and out of the relay unit 3.
  • the gas refrigerant that flows out of the relay unit 3 passes through the main pipe 5a and flows back into the outdoor unit 1.
  • the refrigerant that flows into the outdoor unit 1 passes through the backflow prevention device 14d, the refrigerant flow switching device 13, and the accumulator 19, before being sucked back into the compressor 10.
  • indoor heat exchanger 26c and indoor heat exchanger 26d which have no heat load, there is no need to flow refrigerant, and the corresponding load-side expansion device 25c and load-side expansion device 25d are closed.
  • load-side expansion device 25c or load-side expansion device 25d is opened and the refrigerant circulates.
  • the opening degree of the load-side expansion device is controlled, similar to the load-side expansion device 25a described above, so that the superheat, obtained as the difference between the temperature detected by the load-side first temperature sensor and the temperature detected by the load-side second temperature sensor, remains constant.
  • load side throttle device 25c or load side throttle device 25d is opened and the refrigerant circulates.
  • the opening degree of the load side throttle device is controlled, similar to the load side throttle device 25b described above, so that the subcooling, obtained as the difference between the value obtained by converting the pressure detected by inlet side pressure sensor 33 into a saturation temperature, and the temperature detected by the load side first temperature sensor, remains constant.
  • Fig. 12 is a refrigerant circuit diagram showing the circuit configuration of the air conditioner according to this embodiment in the full heating operation mode.
  • the direction of refrigerant flow is indicated by solid arrows.
  • a heating load is generated only in the indoor heat exchanger 26a and the indoor heat exchanger 26b.
  • control device 60 switches the refrigerant flow switching device 13 to a second state in which the refrigerant discharged from the compressor 10 flows into the relay unit 3 without passing through the outdoor heat exchangers 12a and 12b.
  • low-temperature, low-pressure refrigerant is compressed by compressor 10 and discharged as high-temperature, high-pressure gas refrigerant.
  • the high-temperature, high-pressure gas refrigerant discharged from compressor 10 passes through refrigerant flow switching device 13 and backflow prevention device 14b, and flows out of outdoor unit 1.
  • the high-temperature, high-pressure gas refrigerant flowing out of outdoor unit 1 flows through main pipe 5b into relay unit 3.
  • the high-temperature, high-pressure gas refrigerant that flows into the relay unit 3 passes through the gas-liquid separator 29, the relay unit first opening/closing devices 23a and 23b, and the branch pipe 8a before flowing into the indoor heat exchangers 26a and 26b, which act as condensers.
  • the refrigerant that flows into the indoor heat exchangers 26a and 26b dissipates heat into the indoor air, heating it and becoming liquid refrigerant.
  • the liquid refrigerant that flows out of the indoor heat exchangers 26a and 26b is expanded by the load-side throttle devices 25a and 25b, respectively, and flows back into the outdoor unit 1 through the branch pipe 8b, the second relay throttle device 27 (which is controlled to an open state), and the main pipe 5a.
  • the opening degree of the load-side throttle device 25a is controlled so that the subcooling, obtained as the difference between the value obtained by converting the pressure detected by the inlet-side pressure sensor 33 to a saturation temperature and the temperature detected by the load-side first temperature sensor 31a, remains constant.
  • the opening of the load-side throttle device 25b is controlled so that the subcooling, obtained as the difference between the value obtained by converting the pressure detected by the inlet-side pressure sensor 33 into a saturation temperature, and the temperature detected by the load-side first temperature sensor 31b, remains constant.
  • the refrigerant that flows into the outdoor unit 1 passes through the backflow prevention device 14c and absorbs heat from the outdoor air in the outdoor heat exchangers 12a and 12b, becoming a low-temperature, low-pressure gas refrigerant. It is then sucked back into the compressor 10 via the refrigerant flow switching device 13 and accumulator 19.
  • indoor heat exchanger 26c and indoor heat exchanger 26d which have no heat load, there is no need to flow refrigerant, and the corresponding load-side throttle device 25c and load-side throttle device 25d are closed.
  • load-side throttle device 25c or load-side throttle device 25d is opened and the refrigerant circulates.
  • the opening degree of the load-side throttle device is controlled, similar to the load-side throttle devices 25a and 25b described above, so that the subcooling, obtained as the difference between the value obtained by converting the pressure detected by inlet-side pressure sensor 33 into a saturation temperature and the temperature detected by the load-side first temperature sensor, remains constant.
  • Fig. 13 is a refrigerant circuit diagram showing the circuit configuration of the air conditioner according to this embodiment in the heating-dominated operation mode.
  • the direction of refrigerant flow is indicated by solid arrows.
  • control device 60 switches the refrigerant flow switching device 13 to a second state in which the refrigerant discharged from the compressor 10 flows into the relay unit 3 without passing through the outdoor heat exchangers 12a and 12b.
  • Low-temperature, low-pressure refrigerant is compressed by compressor 10 and discharged as high-temperature, high-pressure gas refrigerant.
  • the high-temperature, high-pressure gas refrigerant discharged from compressor 10 passes through refrigerant flow switching device 13 and backflow prevention device 14b before flowing out of outdoor unit 1.
  • the high-temperature, high-pressure gas refrigerant flowing out of outdoor unit 1 flows into relay unit 3 through main pipe 5b.
  • the high-temperature, high-pressure gas refrigerant that flows into the relay unit 3 passes through the gas-liquid separator 29, the first relay unit opening/closing device 23b, and the branch pipe 8a before flowing into the indoor heat exchanger 26b, which functions as a condenser.
  • the refrigerant that flows into the indoor heat exchanger 26b dissipates heat into the indoor air, heating it and turning into liquid refrigerant.
  • the liquid refrigerant that flows out of the indoor heat exchanger 26b is expanded by the load-side throttle device 25b and flows into the relay unit 3 via the branch pipe 8b.
  • the refrigerant in a two-phase gas-liquid state expanded by the load-side throttle device 25a flows into the indoor heat exchanger 26a, which acts as an evaporator, and becomes gaseous refrigerant by absorbing heat from the indoor air, cooling it.
  • the gaseous refrigerant flowing out of the indoor heat exchanger 26a passes through the branch pipe 8a and the second relay opening/closing device 24a, and merges with the remaining refrigerant that flowed out of the second relay throttle device 27.
  • the merged refrigerant flows out of the relay unit 3, passes through the main pipe 5a, and flows back into the outdoor unit 1.
  • the refrigerant that flows into the outdoor unit 1 passes through the backflow prevention device 14c, and absorbs heat from the outdoor air in the outdoor heat exchangers 12a and 12b, becoming low-temperature, low-pressure gaseous refrigerant.
  • This gaseous refrigerant passes through the refrigerant flow switching device 13 and the accumulator 19, and is again drawn into the compressor 10.
  • the opening degree of the load side expansion device 25b is controlled so that the subcooling, obtained as the difference between the value obtained by converting the pressure detected by the inlet side pressure sensor 33 into a saturation temperature, and the temperature detected by the load side first temperature sensor 31b, remains constant.
  • the opening degree of the load side expansion device 25a is controlled so that the superheat, obtained as the difference between the temperature detected by the load side first temperature sensor 31a and the temperature detected by the load side second temperature sensor 32b, remains constant.
  • the opening degree of the second intermediate throttle device 27 is controlled so that the pressure difference between the pressure detected by the inlet pressure sensor 33 and the pressure detected by the outlet pressure sensor 34 becomes a predetermined pressure difference (e.g., 0.3 MPa).
  • indoor heat exchanger 26c and indoor heat exchanger 26d which have no heat load, there is no need to flow refrigerant, and the corresponding load-side expansion device 25c and load-side expansion device 25d are closed.
  • load-side expansion device 25c or load-side expansion device 25d is opened and the refrigerant circulates.
  • the opening degree of the load-side expansion device is controlled, similar to the load-side expansion device 25a described above, so that the superheat, obtained as the difference between the temperature detected by the load-side first temperature sensor and the temperature detected by the load-side second temperature sensor, remains constant.
  • load side throttle device 25c or load side throttle device 25d is opened and the refrigerant circulates.
  • the opening degree of the load side throttle device is controlled, similar to the load side throttle device 25b described above, so that the subcooling, obtained as the difference between the value obtained by converting the pressure detected by inlet side pressure sensor 33 into a saturation temperature, and the temperature detected by the load side first temperature sensor, remains constant.
  • Fig. 14 is a refrigerant circuit diagram showing the circuit configuration of the air conditioner according to the present embodiment in the split defrosting operation mode.
  • the direction of refrigerant flow is indicated by solid arrows.
  • Fig. 14 shows the split defrosting operation mode when defrosting the outdoor heat exchanger 12b.
  • the refrigerant flow switching device 13 is maintained in the second state, which is the same as in the full heating operation mode and split heating operation mode. Opening/closing device 11a is set to the closed state, opening/closing device 11b is set to the open state, opening/closing device 15a is set to the open state, and opening/closing device 15b is set to the closed state. This causes a portion of the refrigerant discharged from the compressor 10 to flow into the outdoor heat exchanger 12b, defrosting the outdoor heat exchanger 12b.
  • Fig. 15 is a refrigerant circuit diagram showing the circuit configuration in the full defrosting operation mode of the air conditioner according to the present embodiment. In Fig. 15, the direction of refrigerant flow is indicated by solid arrows.
  • the refrigerant flow switching device 13 In the full defrost operation mode, the refrigerant flow switching device 13 is maintained in the second state, the same as in the full heating operation mode and the split heating operation mode.
  • the load side expansion devices 25a to 25d are switched to the closed state, blocking the refrigerant.
  • the opening and closing devices 11a and 11b are switched to the open state, allowing the refrigerant to flow.
  • the heat source side blower 18 and the load side blower (not shown) are stopped.
  • the flow path of the high-temperature, high-pressure gas refrigerant discharged from compressor 10 is connected to the flow path of indoor heat exchangers 26a-26d via backflow prevention device 14b, main pipe 5b, gas-liquid separator 29, first relay opening/closing devices 23a-23d, and branch pipe 8a.
  • the pressure of the high-temperature, high-pressure gas refrigerant discharged from compressor 10 is higher than the pressure of indoor heat exchangers 26a-26d, so the refrigerant that was present during heating operation mode is retained between the closed load-side throttle devices 25a-25d and gas-liquid separator 29.
  • the indoor heat exchangers 26a to 26d operate as condensers, so a large amount of refrigerant is present in the indoor heat exchangers 26a to 26d. This allows excess refrigerant to be stored in the indoor heat exchangers 26a to 26d, reducing the amount of excess refrigerant remaining in the accumulator 19.
  • the amount of excess refrigerant in the accumulator 19 can be reduced by storing excess refrigerant in the indoor heat exchangers 26a to 26d during defrosting operation mode. If the length of the main pipes 5a, 5b is long due to constraints imposed by the installation environment of the air conditioning unit 200, the amount of excess refrigerant will be large. Therefore, by storing excess refrigerant in the indoor heat exchangers 26a to 26d, it is possible to prevent liquid refrigerant from overflowing from the accumulator 19 and flowing into the suction section of the compressor 10.
  • the first relay throttle device 30, the relay second opening/closing devices 24a-24d, and the load-side throttle devices 25a-25d may be closed. This prevents the high-temperature, high-pressure gas refrigerant discharged from the compressor 10 from condensing and remaining in the refrigerant piping, including the main pipe 5a between the outlet side of the relay device 3 and the backflow prevention device 14c, which has a lower temperature than the refrigerant discharged from the compressor 10. This allows a large amount of high-temperature, high-pressure gas refrigerant discharged from the compressor 10 to flow into the outdoor heat exchangers 12a, 12b, improving defrosting capacity. Furthermore, instead of the load-side throttle devices 25a-25d, the second relay throttle device 27 may be closed and the load-side throttle devices 25a-25d may be opened, achieving the same effect.
  • the first relay throttle device 30, the second relay throttle device 27, the first relay opening/closing devices 23a-23d, the second relay opening/closing devices 24a-24d, and the load-side throttle devices 25a-25d may all be closed, and the same effect will be achieved.
  • Embodiment 4 An air conditioning apparatus according to embodiment 4 will be described below. In embodiment 4, only the changes from embodiment 3 will be described.
  • Fig. 16 is a refrigerant circuit diagram showing the circuit configuration in cooling-only operation mode of an air conditioner according to this embodiment.
  • Fig. 17 is a refrigerant circuit diagram showing the circuit configuration in cooling-dominated operation mode of an air conditioner according to this embodiment.
  • a second bypass circuit 21 is provided that connects the flow path between the outdoor heat exchanger 12a and the opening/closing device 15a and the flow path between the outdoor heat exchanger 12b and the refrigerant flow switching device 13.
  • An opening/closing valve 16 is provided in the second bypass circuit 21.
  • An opening/closing valve 17 is provided in the flow path between the second bypass circuit 21 and the refrigerant flow switching device 13. The opening/closing valves 16 and 17 are controlled by the control device 60.
  • the refrigerant flow switching device 13 is set to the first state.
  • the on-off valve 16 is open, the on-off valve 17 is closed, the on-off device 15a is closed, and the on-off device 15b is open.
  • the refrigerant that has passed through the refrigerant flow switching device 13 exchanges heat with outside air in the outdoor heat exchanger 12a, passes through the on-off valve 16, the outdoor heat exchanger 12b, and the on-off device 15b, and flows to the indoor unit 2.
  • Fig. 18 is a refrigerant circuit diagram showing the circuit configuration of the air conditioner in the heating-only operation mode according to this embodiment.
  • Fig. 19 is a refrigerant circuit diagram showing the circuit configuration of the air conditioner in the heating-dominated operation mode according to this embodiment.
  • the refrigerant flow switching device 13 is set to the second state.
  • the on-off valve 16 is closed and the on-off valve 17 is open. The refrigerant flowing from the indoor unit 2 is divided and flows into the on-off device 15a and the on-off device 15b.
  • ⁇ Split defrost operation mode> 20 is a refrigerant circuit diagram showing the circuit configuration of the split defrost operation mode of the air conditioner according to the present embodiment.
  • the refrigerant flow switching device 13 is set to the second state.
  • the on-off valve 16 is closed and the on-off valve 17 is closed.
  • ⁇ Full defrost operation mode> 21 is a refrigerant circuit diagram showing the circuit configuration in the full defrost operation mode of the air conditioner according to the present embodiment.
  • the refrigerant flow switching device 13 In the full defrost operation mode, as in the full heating operation mode and the heating-dominant operation mode, the refrigerant flow switching device 13 is set to the second state.
  • the on-off valve 16 In addition to the first embodiment, the on-off valve 16 is closed and the on-off valve 17 is closed.
  • Embodiment 5 An air conditioning apparatus according to embodiment 5 will be described.
  • Fig. 22 is a refrigerant circuit diagram showing the circuit configuration of an air conditioning apparatus according to this embodiment.
  • the same explanations as in embodiments 1 to 4 will be omitted, and only the characteristic parts will be described.
  • the relay unit 3 of the air conditioning system 300 has relay heat exchangers 35a and 35b that exchange heat between a refrigerant and a heat medium such as water or brine.
  • a liquid heat medium such as water or brine is used as the heat medium.
  • the indoor units 2a to 2d each have indoor heat exchangers 26a to 26d.
  • the indoor heat exchangers 26a to 26d are connected to the relay heat exchanger 35a and relay heat exchanger 35b via heat medium piping 70, which circulates the heat medium.
  • a heat medium circuit 102 is formed between the relay unit 3 and the indoor units 2a to 2d.
  • the outdoor unit 1 and relay unit 3 are connected via main pipes 5a and 5b, through which a refrigerant flows.
  • the main pipes 5a and 5b are connected to relay heat exchangers 35a and 35b provided in the relay unit 3.
  • the relay unit 3 and each of the indoor units 2a to 2b are connected via heat medium pipes 70, through which a heat medium flows.
  • the heat medium pipes are connected to the relay heat exchangers 35a and 35b.
  • the relay unit 3 has, as components of the refrigerant circuit 101, two relay heat exchangers 35a, 35b, two relay throttling devices 38a, 38b, two opening and closing devices 36a, 36b, and two relay flow path switching devices 39a, 39b.
  • the relay unit 3 has, as components of the heat medium circuit 102, two pumps 41a, 41b, four first heat medium flow path switching devices 50a-50d, four second heat medium flow path switching devices 51a-51d, and four heat medium flow control devices 52a-52d.
  • the relay heat exchanger 35a and the relay heat exchanger 35b function as a condenser or an evaporator.
  • the relay heat exchanger 35a and the relay heat exchanger 35b exchange heat between the refrigerant and the heat medium, transferring the cold or hot heat generated in the outdoor unit 1 and stored in the refrigerant to the heat medium.
  • the relay heat exchanger 35a is provided between the relay throttling device 38a and the relay flow switching device 39a in the refrigerant circuit 101.
  • the relay heat exchanger 35a is used to heat the heat medium during combined cooling and heating operation.
  • the relay heat exchanger 35b is provided between the relay throttling device 38b and the relay flow switching device 39b in the refrigerant circuit 101.
  • the relay heat exchanger 35b is used to cool the heat medium during combined cooling and heating operation.
  • Relay throttling device 38a and relay throttling device 38b function as pressure reducing valves or expansion valves, reducing the pressure and expanding the refrigerant.
  • Relay throttling device 38a is located upstream of relay heat exchanger 35a in the refrigerant flow during cooling operation.
  • Relay throttling device 38b is located upstream of relay heat exchanger 35b in the refrigerant flow during cooling operation.
  • Relay throttling device 38a and relay throttling device 38b each consist of an electronic expansion valve or the like whose opening degree can be changed.
  • Opening and closing devices 36a and 36b are composed of two-way valves or the like, and open and close the refrigerant piping 4. Opening and closing device 36a is provided on the refrigerant piping 4 on the inlet side of the refrigerant. Opening and closing device 36b is provided on the refrigerant piping 4 connecting the inlet side and outlet side of the refrigerant.
  • Relay flow path switching device 39a and relay flow path switching device 39b are composed of four-way valves or the like, and switch the refrigerant flow depending on the operating mode.
  • Relay flow path switching device 39a is located downstream of relay heat exchanger 35a in the refrigerant flow during cooling only operation.
  • Relay flow path switching device 39b is located downstream of relay heat exchanger 35b in the refrigerant flow during cooling only operation.
  • Pumps 41a and 41b pressurize and circulate the heat medium flowing through the heat medium piping 70.
  • Pump 41a is provided on the heat medium piping 70 between the relay heat exchanger 35a and the multiple second heat medium flow switching devices 51a to 51d.
  • Pump 41b is provided on the heat medium piping 70 between the relay heat exchanger 35b and the multiple second heat medium flow switching devices 51a to 51d.
  • Each of pumps 41a and 41b is configured, for example, with controllable capacity.
  • the four first heat medium flow switching devices 50a-50d are composed of three-way valves or the like and switch the heat medium flow path.
  • the number of first heat medium flow switching devices 50a-50d corresponds to the number of indoor units 2.
  • One of the three sides of each of the first heat medium flow switching devices 50a-50d is connected to the relay heat exchanger 35a, one of the three sides is connected to the relay heat exchanger 35b, and one of the three sides is connected to a heat medium flow control device 52a-52d.
  • the first heat medium flow switching devices 50a-50d are respectively provided on the outlet side of the heat medium flow path of the indoor heat exchangers 26a-26d. Note that in Figure 22, the first heat medium flow switching device 50a, first heat medium flow switching device 50b, first heat medium flow switching device 50c, and first heat medium flow switching device 50d are shown, from bottom to top, corresponding to the indoor units 2a-2d.
  • the four second heat medium flow switching devices 51a to 51d are composed of three-way valves or the like and switch the heat medium flow path.
  • the number of second heat medium flow switching devices 51a to 51d corresponds to the number of indoor units 2.
  • One of the three sides of each of the second heat medium flow switching devices 51a to 51d is connected to the relay heat exchanger 35a, one of the three sides is connected to the relay heat exchanger 35b, and one of the three sides is connected to each of the indoor heat exchangers 26a to 26d.
  • the second heat medium flow switching devices 51a to 51d are respectively provided on the inlet side of the heat medium flow path of the indoor heat exchangers 26a to 26d. Note that in Figure 22, the second heat medium flow switching device 51a, second heat medium flow switching device 51b, second heat medium flow switching device 51c, and second heat medium flow switching device 51d are shown, from bottom to top, corresponding to the indoor units 2a to 2d.
  • the four heat medium flow control devices 52a to 52d are composed of devices such as two-way valves that can control the opening area, and control the flow rate through the heat medium piping 70.
  • the heat medium flow control devices 52a to 52d are provided in numbers corresponding to the number of indoor units 2 installed.
  • One side of the heat medium flow control devices 52a to 52d is connected to the indoor heat exchangers 26a to 26d, and the other side is connected to the first heat medium flow switching devices 50a to 50d, respectively.
  • the heat medium flow control devices 52a to 52d are provided on the outlet side of the heat medium flow paths of the indoor heat exchangers 26a to 26d.
  • heat medium flow control device 52a heat medium flow control device 52b, heat medium flow control device 52c, and heat medium flow control device 52d are shown from the bottom to correspond to the indoor units 2a to 2d. Additionally, the four heat medium flow control devices 52a to 52d may be provided on the inlet side of the heat medium flow paths of the indoor heat exchangers 26a to 26d.
  • the repeater 3 is equipped with various sensors (not shown). Signals related to the detection by the sensors are sent to, for example, the control device 60.
  • the multiple indoor units 2a-2d are included in the heat medium circuit 102.
  • the multiple indoor units 2a-2d have, for example, the same configuration as one another.
  • the multiple indoor units 2a-2d each have an indoor heat exchanger 26a, 26b, 26c, 26d.
  • Each of the multiple indoor heat exchangers 26a-26d is connected to a relay unit 3 which is connected to the relay unit 3 by piping via branch pipes 8a and 8b.
  • air supplied by a load-side blower (not shown) exchanges heat with the heat medium, generating air for cooling or air for heating to be supplied to the indoor space.
  • the air conditioning apparatus 300 has four cooling and heating operation modes, just like the air conditioning apparatus 200 described in embodiment 3.
  • the first is an all-cooling operation mode in which all of the indoor units 2 that are driven are capable of performing cooling operation.
  • the second is an all-heating operation mode in which all of the indoor units 2 that are driven are capable of performing heating operation.
  • the third is a cooling-dominated operation mode that is executed when the cooling load is greater in combined cooling and heating operation.
  • the fourth is a heating-dominated operation mode that is executed when the heating load is greater in combined cooling and heating operation.
  • the relay unit 3 has a relay heat exchanger 35a and a relay heat exchanger 35b that exchange heat between the refrigerant and the heat medium.
  • the air conditioning apparatus 300 has multiple indoor heat exchangers 26a-27d connected to the relay heat exchanger 35a and the relay heat exchanger 35b of the relay unit 3 by heat medium piping 70 through which the heat medium circulates, and is equipped with one or more indoor units 2a-2d that form a heat medium circuit 102 between the relay unit 3 and the indoor units 2a-2d.
  • FIG. 23 is a refrigerant circuit diagram showing the circuit configuration of an air conditioning apparatus according to this embodiment.
  • the same explanations as in embodiments 1 to 5 will be omitted, and only the characteristic parts will be described.
  • a second bypass circuit 21 is provided to connect the flow path between the outdoor heat exchanger 12a and the opening/closing device 15a and the flow path between the outdoor heat exchanger 12b and the refrigerant flow switching device 13.
  • An opening/closing valve 16 is provided in the second bypass circuit 21.
  • An opening/closing valve 17 is provided in the flow path between the second bypass circuit 21 and the refrigerant flow switching device 13. The opening/closing valves 16 and 17 are controlled by a control device 60.
  • the refrigerant flow switching device 13 is set to the first state.
  • the on-off valve 16 is open, the on-off valve 17 is closed, the on-off device 15a is closed, and the on-off device 15b is open.
  • the refrigerant that has passed through the refrigerant flow switching device 13 exchanges heat with outside air in the outdoor heat exchanger 12a, passes through the on-off valve 16, the outdoor heat exchanger 12b, and the on-off device 15b, and flows to the indoor unit 2.
  • the refrigerant flow switching device 13 is set to the second state.
  • the on-off valve 16 is closed and the on-off valve 17 is open.
  • the refrigerant flowing from the indoor unit 2 is divided and flows into the on-off device 15a and the on-off device 15b.
  • ⁇ Split defrost operation mode> In the divided defrosting operation mode, similarly to the heating only operation mode and the heating main operation mode, the refrigerant flow switching device 13 is set to the second state. In addition to the fifth embodiment, the on-off valve 16 is closed and the on-off valve 17 is closed.
  • ⁇ Full defrost operation mode> In the full defrosting operation mode, as in the full heating operation mode and the heating-dominant operation mode, the refrigerant flow switching device 13 is set to the second state. In addition to the fifth embodiment, the on-off valve 16 is closed and the on-off valve 17 is closed.

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  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Air Conditioning Control Device (AREA)
PCT/JP2024/010894 2024-03-21 2024-03-21 空気調和装置 Pending WO2025196994A1 (ja)

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CN119901055B (zh) * 2025-02-19 2025-11-07 珠海格力电器股份有限公司 一种空调的控制方法、装置、空调、存储介质和程序产品

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5612973A (en) * 1979-07-10 1981-02-07 Sanyo Electric Co Defroster
JPH03117866A (ja) * 1989-09-29 1991-05-20 Toshiba Corp ヒートポンプ式冷凍サイクル
JP2001059664A (ja) * 1999-08-20 2001-03-06 Fujitsu General Ltd 空気調和機
JP2013061091A (ja) * 2011-09-12 2013-04-04 Daikin Industries Ltd 冷凍装置
WO2014083867A1 (ja) * 2012-11-29 2014-06-05 三菱電機株式会社 空気調和装置
WO2018029817A1 (ja) * 2016-08-10 2018-02-15 三菱電機株式会社 冷凍サイクル装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5612973A (en) * 1979-07-10 1981-02-07 Sanyo Electric Co Defroster
JPH03117866A (ja) * 1989-09-29 1991-05-20 Toshiba Corp ヒートポンプ式冷凍サイクル
JP2001059664A (ja) * 1999-08-20 2001-03-06 Fujitsu General Ltd 空気調和機
JP2013061091A (ja) * 2011-09-12 2013-04-04 Daikin Industries Ltd 冷凍装置
WO2014083867A1 (ja) * 2012-11-29 2014-06-05 三菱電機株式会社 空気調和装置
WO2018029817A1 (ja) * 2016-08-10 2018-02-15 三菱電機株式会社 冷凍サイクル装置

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