GB2549897A

GB2549897A - Air conditioning device

Info

Publication number: GB2549897A
Application number: GB1711506.4A
Authority: GB
Inventors: Matsui Ryosuke; Morimoto Osamu
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2015-02-09
Filing date: 2015-02-09
Publication date: 2017-11-01
Anticipated expiration: 2035-02-09
Also published as: WO2016129027A1; JP6257812B2; GB201711506D0; JPWO2016129027A1; GB2549897B

Abstract

An air conditioning device comprises: a plurality of shut-off devices that are each disposed between an indoor unit and a plurality of heat source devices and that shut-off the flow of refrigerant flowing in refrigerant pipes; a plurality of leak detecting units that detect refrigerant leaks from each heat source device; and a controlling device that controls the operation of the plurality of heat source devices, the indoor unit, and the shut-off devices. The controlling device comprises: a shut-off controlling unit that operates the shut-off device connected to the heat source device from which refrigerant is leaking when a refrigerant leak is detected by the leak detecting unit; a capacity setting unit that, when shut-off devices in an operating state and shut-off devices in an non-operating state are present among the plurality of shut-off devices, sets a heat exchange capacity limit for the indoor unit when a heat source device connected to a shut-off device in the non-operating state is operated; and an operation controlling unit that controls the operation of the heat source devices or the indoor unit using the heat exchange capacity limit set by the capacity setting unit as the upper limit.

Description

DESCRIPTION Title of Invention AIR-CONDITIONING APPARATUS Technical Field [0001]

The present invention relates to an air-conditioning apparatus including a plurality of heat source apparatuses and a cutoff device configured to cut off the flow of refrigerant when there is a refrigerant leakage.

Background Art [0002]

Some conventional air-conditioning apparatuses have structures in which a cutoff valve is closed and operation is stopped when a refrigerant leakage occurs, thereby minimizing the refrigerant leakage (refer to Patent Literature 1, for example). Patent Literature 1 discloses an air-conditioning apparatus including a detection unit configured to detect a refrigerant leakage, a concentration calculation unit configured to calculate the concentration of leaked refrigerant detected by the detection unit, and a cutoff device configured to cut off refrigerant circulating through a refrigeration cycle based on an output from a concentration detection unit.

Citation List Patent Literature [0003]

Patent Literature 1: WO 2012/101673 Summary of Invention Technical Problem [0004]

The air-conditioning apparatus according to Patent Literature 1 is controlled to completely cut off the flow of refrigerant and stop operation when a refrigerant leakage occurs. Thus, the comfort of an air-conditioning target space is degraded due to the refrigerant leakage.

[0005]

The present invention is intended to overcome the above-described problem by providing an air-conditioning apparatus capable of minimizing degradation in the comfort of an air-conditioning target space even when a refrigerant leakage is cut off.

Solution to Problem [0006]

An air-conditioning apparatus according to the present invention includes: a refrigerant circuit including a plurality of heat source apparatuses connected in parallel with each other and an indoor unit connected with the plurality of heat source apparatuses through refrigerant pipes, the plurality of heat source apparatuses each including a compressor and a heat source side heat exchanger, the indoor unit including a load side expansion device and a load side heat exchanger; a plurality of cutoff devices installed between each of the heat source apparatuses and the indoor unit and configured to cut off flow of refrigerant through the refrigerant pipes; a plurality of leakage detection units each being configured to detect a refrigerant leakage at corresponding one of the heat source apparatuses; and a controller configured to control operation of the heat source apparatuses, the indoor unit, and the cutoff devices, the controller including a cutoff control unit configured to activate, when a refrigerant leakage is detected by the leakage detection unit, a cutoff device of the plurality of cutoff devices, the cutoff device being connected with the heat source apparatus in which the refrigerant leakage is occurring, a capacity setting unit configured to set, when the cutoff devices include an activated cutoff device and an inactivated cutoff device, a limiting heat exchange capacity of the indoor unit when operation is performed by the heat source apparatus connected with the inactivated cutoff device, and an operation control unit configured to control operation of the plurality of heat source apparatuses or the indoor unit with an upper limit at the limiting heat exchange capacity set by the capacity setting unit.

Advantageous Effects of Invention [0007]

An air-conditioning apparatus according to the present invention can continue, when a refrigerant leakage is detected, operation while minimizing the refrigerant leakage by activating a cutoff device and controlling operation of a heat source apparatus with an upper limit at a limiting heat exchange capacity for cutting off the refrigerant leakage, and thus can minimize degradation in the comfort of an air-conditioning target space even when the refrigerant leakage is cutoff.

Brief Description of Drawings [0008] [Fig. 1] Fig. 1 is a refrigerant circuit diagram illustrating an air-conditioning apparatus according to Embodiment 1 of the present invention.

[Fig. 2] Fig. 2 is a refrigerant circuit diagram illustrating refrigerant flow at a cooling only operation mode in the air-conditioning apparatus in FIG. 1.

[Fig. 3] Fig. 3 is a refrigerant circuit diagram illustrating refrigerant flow at a heating only operation mode in the air-conditioning apparatus in Fig. 1.

[Fig. 4] Fig. 4 is a refrigerant circuit diagram illustrating refrigerant flow at a main cooling operation mode in the air-conditioning apparatus in Fig. 1.

[Fig. 5] Fig. 5 is a refrigerant circuit diagram illustrating refrigerant flow at a main heating operation mode in the air-conditioning apparatus in Fig. 1.

[Fig. 6] Fig. 6 is a block diagram illustrating an exemplary controller in the air-conditioning apparatus in Fig. 1.

[Fig. 7] Fig. 7 is a flowchart illustrating exemplary setting of a reference value at an initial refrigerant amount determination mode in the air-conditioning apparatus in Fig. 1.

[Fig. 8] Fig. 8 is a refrigerant circuit diagram illustrating an indoor unit of an air-conditioning apparatus according to Embodiment 2 of the present invention. Description of Embodiments [0009]

Embodiment 1

Preferred embodiments of an air-conditioning apparatus according to the present invention will be described below with reference to the accompanying drawings. Fig. 1 is a refrigerant circuit diagram illustrating an air-conditioning apparatus according to Embodiment 1 of the present invention. An air-conditioning apparatus 100 includes a plurality of heat source apparatuses 1A and 1B, a relay device 20 connected with the heat source apparatuses 1A and 1B through refrigerant pipes 4a and 4b, and a plurality of indoor units 30a to 30d connected with the relay device 20 through refrigerant pipes 5. The heat source apparatuses 1A and 1B, the relay device 20, and the indoor units 30a to 30d are connected through the refrigerant pipes 4a, 4b, and 5 to serve as a refrigerant circuit 100A. Cooling energy or heating energy generated by the heat source apparatuses 1A and 1B is distributed to the indoor units 30a to 30d through the relay device 20. Examples of refrigerant used in the air-conditioning apparatus 100 include a HFC refrigerant such as R410A, R407C, or R404A, a HCFC refrigerant such as R22 or R134a, or a natural refrigerant such as hydrocarbon or helium.

[0010] [Configuration of heat source apparatuses 1A and 1B]

The heat source apparatuses 1A and 1B are disposed in space outside of, for example, a building or a house, and configured to supply cooling energy or heating energy to the indoor units 30a to 30d through the relay device 20. The heat source apparatuses 1A and 1B are connected in parallel with each other and each include a compressor 10, a first flow switching device 11, a heat source side heat exchanger 12, and an accumulator 13. Although Fig. 1 exemplarily illustrates a case in which the heat source apparatuses 1A and 1B have a same configuration, the heat source apparatuses 1A and 1B may have different configurations.

[0011]

The compressor 10 sucks and compresses refrigerant and discharges the compressed refrigerant at high temperature and high pressure. The compressor 10 has a discharge side connected with the first flow switching device 11, and a suction side connected with the accumulator 13. The compressor 10 may be constituted by, for example, an inverter compressor the capacity of which is controllable.

[0012]

The first flow switching device 11 is constituted by, for example, a four-way valve configured to switch the passage of refrigerant between operation modes. At a heating operation mode and a heating main operation mode, the first flow switching device 11 connects the discharge side of the compressor 10 with a check valve 14b and connects the heat source side heat exchanger 12 with a suction side of the accumulator 13. At a cooling operation mode and a cooling main operation mode, the first flow switching device 11 connects the discharge side of the compressor 10 with the heat source side heat exchanger 12 and connects a check valve 14d with the suction side of the accumulator 13.

[0013]

The heat source side heat exchanger 12 is constituted by, for example, a plate fin and tube heat exchanger configured to exchange heat between refrigerant flowing through a heat transfer tube and air passing through a fin. The heat source side heat exchanger 12 is connected with the first flow switching device 11 on one side and with the refrigerant pipes 4a and 4b through the check valve 14b and a check valve 14c on the other side. The heat source side heat exchanger 12 serves as an evaporator at a heating operation, and serves as a radiator (gas cooler) at a cooling operation. The heat source side heat exchanger 12 exchanges heat between refrigerant and air supplied from an air-sending device such as a fan (not illustrated).

[0014]

The accumulator 13 is connected with the suction side of the compressor 10 to store surplus refrigerant due to difference between the heating operation mode and the cooling operation mode, and surplus refrigerant due to a transitional operational change (for example, change in the number of the indoor units 30a to 30d in operation).

[0015]

The heat source apparatuses 1A and 1B each include four check valves 14a to 14d for allowing refrigerant to flow from the heat source apparatuses 1A and 1B to the relay device 20 in a constant direction at each of the cooling operation mode and the heating operation mode. At the heating operation mode, the refrigerant flows from the first flow switching device 11 to the refrigerant pipe 4a through the check valve 14a, and the refrigerant flows from the refrigerant pipe 4b to the heat source side heat exchanger 12 through the check valve 14b. On the other hand, at the cooling operation mode, the refrigerant flows from the heat source side heat exchanger 12 to the refrigerant pipe 4a through the check valve 14c, and the refrigerant flows from the refrigerant pipe 4b through the check valve 14d. In this manner, the refrigerant pipe 4a serves as a high pressure pipe, and the refrigerant pipe 4b serves as a low pressure pipe.

[0016] [Relay device 20]

The relay device 20 can be installed at a position different from an outdoor space and an indoor space separately from the heat source apparatuses 1A and 1B and the indoor units 30a to 30d. The relay device 20 is connected with the heat source apparatuses 1A and 1B through the refrigerant pipes 4a and 4b and connected with the indoor units 30a to 30d through the refrigerant pipes 5. The relay device 20 transfers, to the indoor units 30a to 30d, the cooling energy or heating energy supplied from the heat source apparatuses 1A and 1B. The relay device 20 includes a gas-liquid separator 21, a first expansion device 22, a second expansion device 23, and second flow switching devices 24a to 24d.

[0017]

The gas-liquid separator 21 is installed at an inlet of the relay device 20 and connected with the heat source apparatuses 1A and 1B through the refrigerant pipe 4a. The gas-liquid separator 21 separates, into liquid refrigerant and gas refrigerant, gas-liquid two-phase refrigerant at high pressure flowing from the heat source apparatuses 1A and 1B. The gas-liquid separator 21 has an upper part connected with a gas pipe, and a lower part connected with a liquid pipe. The liquid refrigerant obtained through the separation at the gas-liquid separator 21 flows to the indoor units 30a to 30d through the liquid pipe at the lower part to supply the cooling energy, and the gas refrigerant flows to the indoor units 30a to 30d through the gas pipe at the upper part to supply the heating energy.

[0018]

The first expansion device 22 serves as a pressure reducing valve and an opening-and-closing valve to cause the liquid refrigerant to have a predetermined pressure through pressure reduction and open and close the passage of the liquid refrigerant. The first expansion device 22 is provided on a downstream pipe to which the liquid refrigerant flows from the gas-liquid separator 21. The first expansion device 22 may be constituted by, for example, an electronic expansion valve, the opening degree of which is controllable and variable.

[0019]

The second expansion device 23 serves as a pressure reducing valve and an opening-and-closing valve, and is installed between a low pressure pipe communicating with the refrigerant pipe 4b and provided on an outlet side of the relay device 20 and a pipe communicating with an outlet side of the first expansion device 22. The second expansion device 23 opens and closes the passage of refrigerant to achieve refrigerant bypassing at a heating only operation mode. The second expansion device 23 adjusts a bypass flow rate in accordance with a load side load at the heating main operation mode. The second expansion device 23 may be constituted by, for example, an electronic expansion valve, the opening degree of which is controllable and variable.

[0020]

The second flow switching devices 24a to 24d switch passages depending on the operation modes of the indoor units 30a to 30d. The number of installed second flow switching devices is equal to the number (in this example, four) of installed indoor units. The second flow switching devices 24a to 24d are connected in parallel with the liquid and gas pipes of the gas-liquid separator 21 and each include two opening-and-closing devices 25a and 25b connected with one of the refrigerant pipes 5 and two check valves 26a and 26b connected with the other refrigerant pipe 5. The following exemplarily describes a case in which the second flow switching devices 24a to 24d each include the two opening-and-closing devices 25a and 25b and the two check valves 26a and 26b. However, the second flow switching devices 24a to 24d may be each constituted by, for example, a four-way valve.

[0021]

The opening-and-closing devices 25a and 25b are constituted by, for example, solenoid valves connected with each other in parallel. The opening-and-closing devices 25a and 25b are each connected with the corresponding refrigerant pipe 5 on one side. The opening-and-closing device 25a is connected with the gas pipe of the gas-liquid separator 21 on the other side, and the opening-and-closing device 25b is connected with the refrigerant pipe 4b on the other side. When the indoor units 30a to 30d operate in the heating operation mode, the corresponding opening-and-closing device 25a side is opened and the corresponding opening-and-closing device 25b side is closed. In contrast, when the indoor units 30a to 30d operate in the cooling operation mode, the corresponding opening-and-closing device 25b side is opened and the corresponding opening-and-closing device 25a side is closed.

[0022]

The check valves 26a and 26b are each connected with the corresponding refrigerant pipe 5 on one side and connected with the first expansion device 22 and the second expansion device 23 on the other side. When the indoor units 30a to 30d operate in the cooling operation mode, refrigerant flows to the indoor units 30a to 30d through the check valve 26a side. In contrast, when the indoor units 30a to 30d perform the heating operation, refrigerant flows from the indoor units 30a to 30d to the second expansion device 23 through the check valve 26b side.

[0023] [Indoor units 30a to 30d]

The indoor units 30a to 30d are each disposed at such a position that the indoor unit can supply cooling air or heating air to an indoor space (for example, a room) being a space inside a building, and supplies cooling air or heating air to the indoor space as an air-conditioning target space. Although Fig. 1 illustrates the example in which the four indoor units 30a to 30d are connected, the number of connected indoor units is not limited to four but may be at least one.

[0024]

The indoor units 30a to 30d each include a load side heat exchanger 31 and a load side expansion device 32. The load side heat exchangers 31 are connected with the second flow switching devices 24a to 24d of the relay device 20 through the refrigerant pipes 5. Each load side heat exchanger 31 exchanges heat between refrigerant and air supplied from an air-sending device such as a fan (not illustrated), and generates heating air or cooling air to be supplied to the indoor space.

[0025]

The load side expansion device 32 is configured by, for example, an electronic expansion valve, the opening degree of which is controllable and variable. At the cooling operation mode, the load side expansion device 32 allows refrigerant to expand through pressure reduction and supplies the refrigerant to the load side heat exchanger 31. At the cooling operation mode, the opening degree of the load side expansion device 32 is controlled so that superheat (the degree of superheat), which is obtained as a difference between temperatures detected by a first temperature sensor 43 and a second temperature sensor 44, is constant.

[0026]

The air-conditioning apparatus 100 can perform the cooling operation or the heating operation of the indoor units 30a to 30d based on instructions from the respective indoor units 30a to 30d. Specifically, the air-conditioning apparatus 100 can perform an identical operation at all indoor units 30a to 30d, and can also perform different operations at the respective indoor units 30a to 30d.

[0027]

Operation modes executed by the air-conditioning apparatus 100 are a cooling only operation mode in which the cooling operation is executed at all indoor units 30a to 30d in operation, a heating only operation mode in which the heating operation is executed at all indoor units 30a to 30d in operation, a cooling main operation mode as a cooling and heating mixed operation mode with a larger cooling load, and a heating main operation mode as a cooling and heating mixed operation mode with a larger heating load. The following describes the operation modes together with heat source side refrigerant and the flow of refrigerant.

[0028]

The following description of the cooling only operation mode, the heating only operation mode, the cooling main operation mode, and the heating main operation mode will be made on an example in which the indoor units 30a and 30b operate while there is no cooling load on the indoor units 30c and 30d, and thus no refrigerant needs to flow through the indoor units 30c and 30d and the corresponding load side expansion devices 32 are closed. The load side expansion devices 32 may be opened to circulate the refrigerant when a cooling load is generated at the indoor units 30c and 30d.

[0029] [Cooling only operation mode]

Fig. 2 is a refrigerant circuit diagram illustrating refrigerant flow in the air-conditioning apparatus in Fig. 1 at the cooling only operation mode. At the cooling only operation mode, the first flow switching device 11 in each of the heat source apparatuses 1A and 1B is switched to allow heat source side refrigerant discharged from the compressor 10 to flow into the heat source side heat exchanger 12. First, refrigerant at low temperature and low pressure is compressed by the compressor 10 and discharged as gas refrigerant at high temperature and high pressure.

Having discharged from the compressor 10, the gas refrigerant at high temperature and high pressure flows into the heat source side heat exchanger 12 through the first flow switching device 11. Then, the heat source side heat exchanger 12 transfers heat from the gas refrigerant to outdoor air to produce high-pressure liquid refrigerant. Having flowed out of the heat source side heat exchanger 12, the high-pressure liquid refrigerant flows out of each of the heat source apparatuses 1A and 1B through the check valve 14c and then flows into the relay device 20 through the refrigerant pipe 4a. Having flowed into the relay device 20, the high-pressure liquid refrigerant flows into the indoor units 30a and 30b through the gas-liquid separator 21, the first expansion device 22, the check valves 26a of the second flow switching devices 24a and 24b, and the refrigerant pipes 5.

[0030]

At each of the indoor units 30a and 30b, the high-pressure liquid refrigerant is expanded through the load side expansion device 32 into gas-liquid two-phase refrigerant at low temperature and low pressure. The gas-liquid two-phase refrigerant flows into the load side heat exchanger 31 acting as an evaporator in each of the indoor units 30a and 30b, and cools indoor air by receiving heat from the indoor air to become gas refrigerant at low temperature and low pressure. Having flowed out of the indoor units 30a and 30b, the gas refrigerant flows out of the relay device 20 through the refrigerant pipes 5 and the opening-and-closing devices 25b of the second flow switching devices 24a and 24b. Then, the gas refrigerant flows in the heat source apparatuses 1A and 1B again through the refrigerant pipe 4b on the low-pressure side. Having flowed in the heat source apparatuses 1A and 1B, the refrigerant passes through the check valve 14d and is sucked by the compressor 10 again through the first flow switching device 11, and the accumulator 13.

[0031] [Heating only operation mode]

Fig. 3 is a refrigerant circuit diagram illustrating refrigerant flow in the air-conditioning apparatus in Fig. 1 at the heating only operation mode. At the heating only operation mode illustrated in Fig. 3, the first flow switching device 11 in each of the heat source apparatuses 1A and 1B is switched to allow heat source side refrigerant discharged from the compressor 10 to flow into the relay device 20 not through the heat source side heat exchanger 12. Refrigerant at low temperature and low pressure is compressed by the compressor 10 and discharged as gas refrigerant at high temperature and high pressure. Having discharged from the compressor 10, the gas refrigerant at high temperature and high pressure flows out of the heat source apparatuses 1A and 1B through the first flow switching device 11 and the check valve 14a. Having flowed out of the heat source apparatuses 1A and 1B, the gas refrigerant at high temperature and high pressure flows into the relay device 20 through the refrigerant pipe 4a on the high-pressure refrigerant side. Having flowed in the relay device 20, the gas refrigerant at high temperature and high pressure flows into the indoor units 30a and 30b through the gas-liquid separator 21, the opening-and-closing devices 25a of the second flow switching devices 24a and 24b, and the refrigerant pipes 5.

[0032]

The gas refrigerant at high temperature and high pressure flows into the load side heat exchanger 31 acting as a condenser in each of the indoor units 30a and 30b, and heats the indoor space by transferring heat to indoor air to become liquid refrigerant. Having flowed out of the indoor units 30a and 30b, the liquid refrigerant is expanded by the load side expansion device 32 and flows in the heat source apparatuses 1A and 1B again through the refrigerant pipes 5, the check valves 26b, the second expansion device 23, and the refrigerant pipe 4b. Having flowed in each of the heat source apparatuses 1A and 1B, the refrigerant passes through the check valve 14b and receives heat from outdoor air at the heat source side heat exchanger 12 to become gas refrigerant at low temperature and low pressure. Thereafter, the gas refrigerant at low temperature and low pressure is sucked by the compressor 10 again through the first flow switching device 11 and the accumulator 13.

[0033] [Cooling main operation mode]

Fig. 4 is a refrigerant circuit diagram illustrating refrigerant flow in the air-conditioning apparatus in Fig. 1 at the cooling main operation mode. Fig. 4 illustrates an example in which a cooling load is generated at the indoor unit 30a and a heating load is generated at the indoor unit 30b. At the cooling main operation mode illustrated in Fig. 4, the first flow switching device 11 is switched to allow refrigerant discharged from the compressor 10 to flow into the heat source side heat exchanger 12. Refrigerant at low temperature and low pressure is compressed by the compressor 10 and discharged as gas refrigerant at high temperature and high pressure. Having discharged from the compressor 10, the gas refrigerant at high temperature and high pressure flows into the heat source side heat exchanger 12 through the first flow switching device 11. The gas refrigerant at high temperature and high pressure transfers heat to outdoor air at the heat source side heat exchanger 12 to become gas-liquid two-phase refrigerant. Having flowed out of the heat source side heat exchanger 12, the refrigerant flows into the relay device 20 through the check valve 14c and the refrigerant pipe 4a. Having flowed in to the relay device 20, the two-phase refrigerant is separated into high-pressure gas refrigerant and high-pressure liquid refrigerant through the gas-liquid separator 21. The high-pressure gas refrigerant flows into the indoor unit 30b through the opening-and-closing device 25a of the second flow switching device 24b and the refrigerant pipe 5. Then, the high-pressure gas refrigerant flows into the load side heat exchanger 31 acting as a condenser in the indoor unit 30b, and heats the indoor space by transferring heat to indoor air to become liquid refrigerant.

[0034]

Having flowed out of the load side heat exchanger 31 of the indoor unit 30b, the liquid refrigerant is expanded by the load side expansion device 32 and passes through the refrigerant pipe 5 and the check valve 26b. Having passed through the check valve 26b, the liquid refrigerant merges with middle-pressure liquid refrigerant separated through the gas-liquid separator 21 and expanded to middle pressure (for example, high pressure - 0.3 MPa approximately) at the second expansion device 23. The merged liquid refrigerant passes through the check valve 26a and the refrigerant pipe 5, and then is expanded at the load side expansion device 32 to become gas-liquid two-phase refrigerant at low temperature and low pressure. This two-phase refrigerant flows into the load side heat exchanger 31 acting as an evaporator in the indoor unit 30a, and cools indoor air by receiving heat from the indoor air to become gas refrigerant at low temperature and low pressure. Having flowed out of the load side heat exchanger 31, the gas refrigerant flows out of the relay device 20 through the refrigerant pipe 5 and the opening-and-closing device 25b, and then flows into the heat source apparatuses 1A and 1B again through the refrigerant pipe 4b. Having flowed into the heat source apparatuses 1A and 1B, the refrigerant passes through the check valve 14d and is sucked by the compressor 10 again through the first flow switching device 11 and the accumulator 13.

[0035] [Heating main operation mode]

Fig. 5 is a refrigerant circuit diagram illustrating refrigerant flow in the air-conditioning apparatus in Fig. 1 at the heating main operation mode. Fig. 5 illustrates an example in which a cooling load is generated at the indoor unit 30a and a heating load is generated at the indoor unit 30b. At the heating main operation mode illustrated in Fig. 5, the first flow switching device 11 in each of the heat source apparatuses 1A and 1B is switched to allow heat source side refrigerant discharged from the compressor 10 to flow into the relay device 20 not through the heat source side heat exchanger 12. Refrigerant at low temperature and low pressure is compressed by the compressor 10 and discharged as gas refrigerant at high temperature and high pressure. Having discharged from the compressor 10, the gas refrigerant at high temperature and high pressure flows out of each of the heat source apparatuses 1A and 1B through the first flow switching device 11 and the check valve 14a. Having flowed out of the heat source apparatuses 1A and 1B, the gas refrigerant at high temperature and high pressure flows into the relay device 20 through the refrigerant pipe 4a on the high-pressure refrigerant side. Having flowed into the relay device 20, the gas refrigerant at high temperature and high pressure flows into the indoor unit 30b through the gas-liquid separator 21, the opening-and-closing device 25a of the second flow switching device 24b, and the refrigerant pipe 5. The gas refrigerant at high temperature and high pressure flows into the load side heat exchanger 31 acting as a condenser in the indoor unit 30b and heats the indoor space by transferring heat to indoor air to become liquid refrigerant.

[0036]

Having flowed out of the load side heat exchanger 31 of the indoor unit 30b, the liquid refrigerant is expanded by the load side expansion device 32 and passes through the refrigerant pipe 5 and the check valve 26b of the second flow switching device 24b and thereafter is bifurcated into the check valve 26a of the second flow switching device 24a and the second expansion device 23 used as a bypass.

Having flowed into the check valve 26a, the liquid refrigerant flows into the indoor unit 30a through the refrigerant pipe 5.

[0037]

Thereafter, the liquid refrigerant is expanded by the load side expansion device 32 to become two-phase refrigerant at low temperature and low pressure. This two-phase refrigerant flows into the load side heat exchanger 31 acting as an evaporator, and cools indoor air by receiving heat from the indoor air to become gas refrigerant at low temperature and low pressure. Having flowed out of the load side heat exchanger 31, the gas refrigerant passes through the refrigerant pipe 5 and the opening-and-closing device 25a, merges with the liquid refrigerant through the bypass at an outlet of the second expansion device 23 and flows out of the relay device 20. The merged refrigerant flows into each of the heat source apparatuses 1A and 1B again through the refrigerant pipe 4b, passes through the check valve 14b, and becomes gas refrigerant at low temperature and low pressure by receiving heat from outdoor air at the heat source side heat exchanger 12. Then, the gas refrigerant at low temperature and low pressure is sucked by the compressor 10 again through the first flow switching device 11 and the accumulator 13.

[0038] A controller 50 controls the above-described operation modes and the refrigerant circuit 100A. The controller 50 is configured by, for example, a microcomputer, and controls the entire device operation based on information of detection by various sensors and an instruction from a remote controller. The following exemplarily describes a case in which the controller 50 is provided to the heat source apparatus 1A, but the controller 50 may be provided to the indoor units 30a to 30d side or may be provided separately from the heat source apparatuses 1A and 1B and the indoor units 30a to 30d.

[0039]

The air-conditioning apparatus 100 includes a first pressure sensor 41 configured to detect the pressure of refrigerant flowing between the gas-liquid separator 21 and the first expansion device 22, a second pressure sensor 42 configured to detect the pressure of refrigerant having passed through the first expansion device 22, the first temperature sensor 43 provided between the load side heat exchanger 31 and the load side expansion device 32, the second temperature sensor 44 provided between the load side heat exchanger 31 and the second flow switching devices 24a to 24d, and an indoor temperature sensor 45 configured to detect the temperature of indoor air being an air conditioning load. The first pressure sensor 41, the first temperature sensor 43, and the second temperature sensor 44 serve as refrigerant temperature sensors configured to detect the temperature of refrigerant flowing through the load side heat exchanger 31.

[0040]

The controller 50 controls operation of the first expansion device 22 so that a predetermined pressure difference (for example, 0.3 MPa) is obtained between a pressure detected by the first pressure sensor 41 and a pressure detected by the second pressure sensor 42. At the heating operation of the indoor units 30a to 30d, the controller 50 controls the opening degree of the load side expansion device 32 so that a subcool (degree of subcooling) obtained as a difference between a saturation temperature converted from a pressure detected by the first pressure sensor 41 and a temperature detected by the first temperature sensor 43 is constant. At the cooling operation of the indoor units 30a to 30d, the controller 50 controls the opening degree of the load side expansion device 32 so that a superheat (degree of superheat) obtained as a difference between a temperature detected by the first temperature sensor 43 and a temperature detected by the second temperature sensor 44 is constant.

[0041]

The air-conditioning apparatus 100 includes a plurality of cutoff devices 6a, 6b, 7a, and 7b installed between the heat source apparatuses 1A and 1B and the indoor units 30a to 30d and configured to cut off the flow of refrigerant into the refrigerant pipes 4a and 4b. The cutoff devices 6a and 7a are provided on the refrigerant pipes 4a and 4b connecting the heat source apparatus 1A and the relay device 20, and the cutoff devices 6b and 7b are provided on the refrigerant pipes 4a and 4b connecting the heat source apparatus 1B and the relay device 20. The cutoff devices 6a, 6b, 7a, and 7b are configured by, for example, two-way valves, and configured to open when power supply is performed and close when power supply is stopped.

[0042]

The opening and closing operation of the cutoff devices 6a, 6b, 7a, and 7b is controlled by the controller 50. The cutoff devices 6a and 7a are closed when a refrigerant leakage occurs at the heat source apparatus 1 A, and the cutoff devices 6b and 7b are closed when a refrigerant leakage occurs at the heat source apparatus 1B. The air-conditioning apparatus 100 includes a leakage detection unit 46 installed in each of the heat source apparatuses 1A and 1B and configured to detect any refrigerant leakage. The controller 50 controls the cutoff devices 6a, 6b, 7a, and 7b based on a result of detection by the leakage detection unit 46.

[0043]

Fig. 6 is a functional block diagram illustrating an exemplary controller in the air-conditioning apparatus in Fig. 1. In FIGs. 1 and 6, the leakage detection unit 46 includes a concentration detection unit 46a including a detection member the resistance value of which changes depending on the concentration of refrigerant, and a leakage determination unit 46b configured to calculate the concentration of refrigerant based on the resistance value of the concentration detection unit 46a.

[0044]

The leakage determination unit 46b calculates the concentration of refrigerant based on the resistance value of the detection member of the concentration detection unit 46a, and determines whether there is a refrigerant leakage. The leakage determination unit 46b stores a relation between the resistance value of the detection member of the concentration detection unit 46a and the concentration of refrigerant. The leakage determination unit 46b calculates the concentration of refrigerant based on the resistance value of the concentration detection unit 46a.

The leakage determination unit 46b stores a predetermined concentration value set in advance, and determines that there is no refrigerant leakage when the concentration of refrigerant is lower than the predetermined concentration value.

On the other hand, the leakage determination unit 46b determines that there is a refrigerant leakage when the concentration of refrigerant is equal to or higher than the predetermined concentration value. The predetermined concentration value corresponds to a refrigerant leakage limit concentration or an explosion limit minimum set to the air-conditioning apparatus 100. For example, when carbon dioxide is used as refrigerant, the predetermined concentration is preferably set to 1/10 of the leak limit concentration approximately.

[0045]

When one of the heat source apparatuses 1A and 1B cannot be used but the cutoff devices of the other heat source apparatus are inactivated, the air-conditioning apparatus 100 can be operated. Making use of this, the controller 50 performs control to continue the operation of the refrigerant circuit 100A if possible even when some of the cutoff devices are activated. In this case, however, there is a refrigerant leakage, and the refrigerant circuit is partially cut off by some of the cutoff devices. Accordingly, the flow rate of refrigerant circulating through the refrigerant circuit 100A is small as compared to the normal operation, and thus the entire air-conditioning apparatus 100 has a reduced maximum capacity. When the operation is performed at the maximum capacity in the normal operation in this state, an abnormal stop is potentially caused. Thus, a capacity setting unit 53 has a function to set a limiting heat exchange capacity to be an upper limit capacity when the cutoff devices are activated.

[0046]

Specifically, the controller 50 includes a cutoff control unit 51, an operation control unit 52, and the capacity setting unit 53. When the leakage detection unit 46 determines that there is a refrigerant leakage, the cutoff control unit 51 closes the cutoff devices 6a and 7a, or 6b and 7b to cut off the flow of refrigerant.

Accordingly, the amount of refrigerant leakage can be reduced to achieve improved safety at the air-conditioning apparatus 100. The cutoff control unit 51 activates the cutoff devices for a heat source apparatus in which it is determined that there is a refrigerant leakage, and maintains inactivation of the cutoff devices for a heat source apparatus in which there is no refrigerant leakage.

[0047]

The operation control unit 52 controls the operation of the refrigerant circuit 100A, and specifically controls, for example, the driving frequency of the compressor 10, the rotation speed (including turning on and off) of the air-sending device (not illustrated), switching at the first flow switching device 11, the opening degrees of the first expansion device 22 and the second expansion device 23, switching at the second flow switching devices 24a to 24d, and the opening degree of the load side expansion device 32. The operation control unit 52 has a function to control switching between the various operation modes described above.

[0048]

The operation control unit 52 performs operation in the ranges of limiting heat exchange capacities Qe1 and Qc1 even when the flow of refrigerant to the heat source apparatus 1A as one of the heat source apparatuses 1A and 1B is cut off.

For example, the operation control unit 52 limits the maximum capacity of the indoor units 30a to 30d by performing control to reduce the number of the indoor units 30a to 30d in operation or to reduce the air volume of an indoor fan or reduce the upper limit of the operational frequency of the compressor 10. The operation control unit 52 stops operation when all of the cutoff devices 6a, 6b, 7a, and 7b are in activation.

[0049]

When there is a heat source apparatus in which the cutoff devices are inactivated, the capacity setting unit 53 sets the limiting heat exchange capacities Qe1 and Qc1 when operation is performed by driving the heat source apparatus in which the cutoff devices are inactivated. For example, in setting the limiting heat exchange capacities Qe1 and Qc1, when the cutoff devices 6a and 7a for the heat source apparatus 1A are activated, the capacity setting unit 53 sets the limiting heat exchange capacities Qe1 and Qc1 when operation is continued with the heat source apparatus 1B connected with the cutoff devices 6b and 7b being inactivated.

[0050]

When the capacity setting unit 53 sets the limiting heat exchange capacities Qe1 and Qc1, the operation control unit 52 described above performs a refrigerant state check operation in which the compressor 10 is controlled to drive at a predetermined rotation speed. At the refrigerant state check operation, the operation control unit 52 controls the refrigerant circuit so that refrigerant flows in passages for both the cooling only operation mode and the heating only operation mode. Then, the capacity setting unit 53 calculates the limiting heat exchange capacity Qe1 for the cooling operation and the limiting heat exchange capacity Qc1 for the heating operation while the heat source apparatus 1A is cut off.

[0051]

The capacity setting unit 53 includes a temperature difference calculation unit 53a configured to calculate heat exchange temperature differences ATe1 and ATc1 at the refrigerant state check operation, a capacity calculation unit 53b configured to calculate the limiting heat exchange capacities Qe1 and Qc1 based on the heat exchange temperature differences ATe1 and ATc1, and a storage unit 53c. At the cooling only operation mode in the refrigerant state check operation, the temperature difference calculation unit 53a acquires a refrigerant temperature Te1 detected by the first temperature sensor 43 and an air temperature Tairl detected by the indoor temperature sensor 45. Then, the temperature difference calculation unit 53a calculates the heat exchange temperature difference ATe1 of the load side heat exchanger 31 (evaporator) based on Expression (1) below.

[0052] ATe1 = Tairl -Te1 ... (1) [0053]

At the heating only operation mode in the refrigerant state check operation, the temperature difference calculation unit 53a acquires a refrigerant temperature Tc1 as a saturation temperature converted from a pressure detected by the first pressure sensor 41 and the air temperature Tairl detected by the indoor temperature sensor 45. Then, the temperature difference calculation unit 53a calculates the heat exchange temperature difference ATc1 of the load side heat exchanger 31 (condenser) based on Expression (2) below.

[0054] ATc1 = Tc1 - Tairl ... (2) [0055]

When a plurality of the indoor units 30a to 30d are installed, the heat exchange temperature differences ATe1 and ATc1 are calculated for each of the indoor units 30a to 30d, and then, for example, an average value thereof is used.

[0056]

The capacity calculation unit 53b sets the limiting heat exchange capacities Qe1 and Qc1 based on the heat exchange temperature differences ATe1 and ATc1 calculated by the temperature difference calculation unit 53a. The storage unit 53c stores in advance, as set heat exchange capacities, a set evaporator capacity Qestd for the cooling operation and a set condenser capacity Qestd for the heating operation under a standard air condition. The set evaporator capacity Qestd and the set condenser capacity Qestd are determined by the total capacity of the indoor units 30a to 30d connected with the heat source apparatuses 1A and 1B.

[0057]

In addition, the storage unit 53c stores initial heat exchange temperature differences ATeO and ATcO at a test operation or the initial refrigerant state check operation. The operation control unit 52 also performs the refrigerant state check operation at a test operation when the air-conditioning apparatus 100 is installed or at reception of an initial refrigerant state check signal, for example, through a button operation. The initial heat exchange temperature differences ATeO and ATcO are calculated by the above-described method at the initial refrigerant state check operation, for example, in a test operation.

[0058]

Specifically, at the cooling only operation mode in the initial refrigerant state check operation, the temperature difference calculation unit 53a calculates the initial heat exchange temperature difference ΔΤβΟ based on Expression (3) below with an initial refrigerant temperature TeO detected by the first temperature sensor 43 and an initial air temperature TairO detected by the indoor temperature sensor 45. Then, the temperature difference calculation unit 53a stores the initial heat exchange temperature difference ATeO to the storage unit 53c.

[0059] ATeO = TairO - TeO ... (3) [0060]

At the cooling only operation mode in the initial refrigerant state check operation, the temperature difference calculation unit 53a calculates the initial heat exchange temperature difference ATcO based on Expression (4) below with an initial refrigerant temperature TeO as a saturation temperature converted from a pressure detected by the first pressure sensor 41 and the initial air temperature TairO detected by the indoor temperature sensor 45.

[0061] ATc1 = Tc1 - Tairl ... (4) [0062]

As described above, the storage unit 53c stores the initial heat exchange temperature differences ATeO and ATcO obtained at an actual operation, which allows setting of limiting capacities in accordance with the place and state of installation.

[0063]

The capacity calculation unit 53b calculates the limiting heat exchange capacity Qe1 for the cooling operation from a ratio (ATe1/ATeO) of the heat exchange temperature differences based on Expression (5) below.

[0064]

Qe1 = Qestd x (ATe1/ATeO)... (5) [0065]

The capacity calculation unit 53b also calculates the limiting heat exchange capacity Qc1 for the heating operation from a ratio (ATc1/ATcO) of the heat exchange temperature differences based on Expression (6) below.

[0066]

Qc1 = Qcstd x (ATc1/ATc0)... (6) [0067]

Then, the operation control unit 52 cancels the refrigerant state check operation after the capacity setting unit 53 sets the limiting heat exchange capacities Qe1 and Qc1, and then performs the cooling operation mode or the heating operation mode described above in the ranges of the limiting heat exchange capacities Qe1 and Qc1. For example, the operation control unit 52 limits the maximum capacity of the indoor units 30a to 30d by performing control to reduce the number of the indoor units 30a to 30d in operation or to reduce the air volume of an indoor fan or reduce the upper limit of the operational frequency of the compressor 10.

[0068]

Fig. 7 is a flowchart illustrating an exemplary operation of the air-conditioning apparatus in Fig. 1. The following describes the exemplary operation of the air-conditioning apparatus with reference to Figs. 1 to 7. In the example illustrated in Fig. 7, the initial heat exchange temperature differences ΔΤβΟ and ATcO are stored to the storage unit 53c through the initial refrigerant state check operation. First, after the air-conditioning apparatus 100 is started to operate, the leakage detection unit 46 determines whether there is any refrigerant leakage (step ST1). Then, when the leakage detection unit 46 determines that there is a refrigerant leakage, for example, in the heat source apparatus 1A (YES at step ST1), the cutoff control unit 51 cuts off the cutoff devices 6a and 7a for the heat source apparatus 1A (step ST2).

[0069]

Thereafter, the operation control unit 52 determines whether there are the cutoff devices 6b and 7b being inactivated (step ST3), and determines whether the operation can be continued. When all cutoff devices 6a, 6b, 7a, and 7b are activated, the operation of the device is stopped (NO at step ST3). When there are the cutoff devices 6b and 7b being inactivated (YES at step ST3), the operation control unit 52 starts the refrigerant state check operation (step ST4), and the capacity setting unit 53 calculates the heat exchange temperature difference ATe1 at a cooling only operation mode, and the heat exchange temperature difference ATc1 at a heating only operation (steps ST5 and ST6). Any one of the heat exchange temperature differences ATe1 and ATc1 may be calculated prior to the other.

[0070]

Then, the capacity calculation unit 53b calculates the limiting heat exchange capacities Qe1 and Qc1 for the cooling operation and the heating operation, respectively (step ST7). Thereafter, the refrigerant state check operation is canceled, and then the cooling operation or the heating operation is performed at capacities with upper limits at the limiting heat exchange capacities Qe1 and Qc1 (step ST8).

[0071]

According to Embodiment 1 described above, when there is a refrigerant leakage, a heat source apparatus in which there is no refrigerant leakage can be continuously operated while a refrigerant circuit in which the leak is occurring is cut off. In this case, the operation is performed with upper limits at the limiting heat exchange capacities Qe1 and Qc1 calculated to be lower than a normal capacity by the capacity setting unit 53. This configuration can prevent the occurrence of an abnormal stop caused by shortage of refrigerant, thereby reliably continuing the operation.

[0072]

When the capacity setting unit 53 calculates the limiting heat exchange capacities Qe1 and Qc1, the operation control unit 52 controls the refrigerant circuit 100A to execute the refrigerant state check operation in which the compressor 10 is driven at the predetermined rotation speed. The capacity setting unit 53 includes the storage unit 53c storing the set heat exchange capacities Qestd and Qcstd of the indoor units 30a to 30d. The capacity setting unit 53 sets limiting heat exchange capacities lower than the set heat exchange capacities Qestd and Qcstd in accordance with the state of the load side heat exchanger 31 at the refrigerant state check operation. Accordingly, the limiting heat exchange capacities Qe1 and Qc1 can be accurately set based on the actual amount of refrigerant after the cutoff devices 6a, 6b, 7a, and 7b are activated.

[0073]

The capacity setting unit 53 further includes the temperature difference calculation unit 53a configured to calculate the heat exchange temperature differences ATc1 and ATe1 between the respective refrigerant temperatures Tc1 and Te1 and the air temperature Tairl at the refrigerant state check operation, and the capacity calculation unit 53b configured to calculate the limiting heat exchange capacities Qe1 and Qc1 by multiplying the set evaporator capacity Qestd and the set condenser capacity Qcstd being set heat exchange capacities with ratios of the heat exchange temperature differences ATc1 and ATe1 calculated by the temperature difference calculation unit 53a to the respective initial heat exchange temperature differences ATcO and ATeO stored to the storage unit 53c. Accordingly, the limiting heat exchange capacities Qe1 and Qc1 can be accurately set based on the actual amount of refrigerant after the cutoff devices 6a, 6b, 7a, and 7b are activated.

[0074]

Since the storage unit 53c stores the initial heat exchange temperature differences ATcO and ATeO between the respective initial refrigerant temperatures TcO and TeO detected by the first pressure sensor 41 or the first temperature sensor 43 being refrigerant temperature sensors and the initial air temperature TairO detected by the indoor temperature sensor 45 at installation, the limiting heat exchange capacities Qe1 and Qc1 can be set in accordance with the place and condition of installation.

[0075]

Any of the cooling operation and the heating operation can be continued at the occurrence of a refrigerant leakage when the heat source apparatuses 1A and 1B each include a flow switching device configured to switch the passage of refrigerant in the cooling operation and the heating operation, and the capacity setting unit 53 sets the limiting heat exchange capacities Qc1 and Qe1 for the cooling operation and the heating operation, respectively.

[0076] A refrigerant leakage can be accurately detected when the leakage detection unit 46 includes the concentration detection unit 46a installed in a plurality of the heat source apparatuses 1A and 1B and configured to detect the concentration of leaked refrigerant, and the leakage determination unit 46b configured to determine that there is a refrigerant leakage when the concentration of leaked refrigerant detected by the concentration detection unit 46a is equal to or higher than a set threshold.

[0077]

Embodiment 2

Fig. 8 is a refrigerant circuit diagram illustrating an air-conditioning apparatus according to Embodiment 2 of the present invention. In this air-conditioning apparatus 200 in Fig. 8, any site having a configuration identical to that of the air-conditioning apparatus 100 in Fig. 1 is denoted by an identical reference sign, and description thereof will be omitted. The air-conditioning apparatus 200 in Fig. 8 differs from the air-conditioning apparatus 100 in Fig. 1 in that the heat source apparatuses 1A and 1B are directly connected with the indoor units 30a to 30d without the relay device 20 therebetween.

[0078]

The air-conditioning apparatus 200 in Fig. 8 includes a discharge pressure sensor 241 provided on the discharge side of the compressor 10 and configured to detect a discharge pressure of refrigerant discharged from the compressor 10. The temperature difference calculation unit 53a of the controller 50 calculates the initial heat exchange temperature difference ATcO and the heat exchange temperature difference ATc1 by using the initial refrigerant temperature TcO and the refrigerant temperature Tc1 as saturation temperatures converted from pressures detected by the discharge pressure sensor 241.

[0079]

In Embodiment 2 described above, too, similarly to Embodiment 1, when there is a refrigerant leakage, a heat source apparatus in which there is no refrigerant leakage can be continuously operated without causing, for example, an abnormal stop while a refrigerant circuit in which the leak is occurring is cut off.

[0080]

Embodiments of the present invention are not limited to the above-described embodiments, but various kinds of modifications are possible. For example, although a plurality of the indoor units 30a to 30d are provided in the above-described embodiments, at least one indoor unit 30a may be provided. In addition, the second flow switching devices 24a to 24d are built in the relay device 20 in the above-described example, but may be built in the indoor units 30a to 30d.

Moreover, the air-conditioning apparatus 100 is capable of performing the cooling and heating mixed operation in the above description, but may be configured to perform only one of the cooling operation and the heating operation.

[0081]

Typically, air-sending devices are in many cases attached to the heat source side heat exchanger 12 and the load side heat exchanger 31 to promote condensation or evaporation by air-sending, but the present invention is not limited thereto. For example, the load side heat exchanger 31 may be, for example, a panel heater that exploits radiation, and the heat source side heat exchanger 12 may be of a water-cooled type configured to transfer heat through water or antifreeze liquid. In other words, the heat source side heat exchanger 12 and the load side heat exchanger 31 may be any kinds of structures that achieve heat transferring or heat reception.

[0082]

The leakage detection unit 46 is disposed in each of the heat source apparatuses 1A and 1B in the above-described example, but may be disposed in the indoor units 30a to 30d. This configuration can handle any refrigerant leakage in the indoor units 30a to 30d. In this case, cutoff devices may be provided on the refrigerant pipes 5 in Fig. 1.

[0083]

Although the above description is made on the example in which a refrigerant leakage determination unit determines a refrigerant leakage based on the concentration of refrigerant detected by the leakage detection unit 46, the present invention is not limited thereto, but any device that detects a refrigerant leakage is applicable. Although the above-described embodiments exemplarily describe the case in which the capacity setting unit 53 sets the limiting heat exchange capacities Qe1 and Qc1 based on the heat exchange temperature differences ATc1 and ATe1, any method is applicable that sets the limiting heat exchange capacities Qe1 and Qc1 to be lower than the set heat exchange capacities Qestd and Qcstd at installation. For example, the storage unit 53c stores, in advance, the limiting heat exchange capacities Qe1 and Qc1 for a case in which each cutoff device is activated, and the limiting heat exchange capacities Qe1 and Qc1 stored to the storage unit 53c may be set when the cutoff device is activated.

Reference Signs List [0084] 1 A, 1B heat source apparatuses 4a, 4b refrigerant pipe 5 refrigerant pipe 6a, 6b, 7a, 7b cutoff device 10 compressor 11 first flow switching device 12 heat source side heat exchanger 13 accumulator 14ato14d check valve 20 relay device 21 gas-liquid separator 22 first expansion device 23 second expansion device 24a to 24d second flow switching device 25a, 25b opening-and-closing device 26a, 26b check valve 30a to 30d indoor unit 31 load side heat exchanger 32 load side expansion device 41 first pressure sensor42 second pressure sensor 43 first temperature sensor 44 second temperature sensor 45 indoor temperature sensor 46 leakage detection unit 46a concentration detection unit 46b leakage determination unit 50 controller 51 cutoff control unit 52 operation control unit 53 capacity setting unit 53a temperature difference calculation unit53b capacity calculation unit 53c storage unit 100,200 air-conditioning apparatus 100A refrigerant circuit 241 discharge pressure sensor Qcstd set heat exchange capacity Qc1 limiting heat exchange capacity Qcstd condenser capacity Qe1 limiting heat exchange capacity Qestd evaporator capacity TairO initial air temperature Tairl air temperature TcO initial refrigerant temperature Tc1 refrigerant temperature TeO initial refrigerant temperature Te1 refrigerant temperature ATcO initial heat exchange temperature difference ATc1 heat exchange temperature difference ATeO initial heat exchange temperature difference ATe1 heat exchange temperature difference.

Claims

CLAIMS [Claim 1] An air-conditioning apparatus comprising: a refrigerant circuit including a plurality of heat source apparatuses connected in parallel with each other and an indoor unit connected with the plurality of heat source apparatuses through refrigerant pipes, the plurality of heat source apparatuses each including a compressor and a heat source side heat exchanger, the indoor unit including a load side expansion device and a load side heat exchanger; a plurality of cutoff devices installed between each of the heat source apparatuses and the indoor unit and configured to cut off flow of refrigerant through the refrigerant pipes; a plurality of leakage detection units each being configured to detect a refrigerant leakage at corresponding one of the heat source apparatuses; and a controller configured to control operation of the heat source apparatuses, the indoor unit, and the cutoff devices, the controller including a cutoff control unit configured to activate, when a refrigerant leakage is detected by the leakage detection unit, a cutoff device of the plurality of cutoff devices, the cutoff device being connected with the heat source apparatus in which the refrigerant leakage is occurring, a capacity setting unit configured to set, when the cutoff devices include an activated cutoff device and an inactivated cutoff device, a limiting heat exchange capacity of the indoor unit when operation is performed by the heat source apparatus connected with the inactivated cutoff device, and an operation control unit configured to control operation of the plurality of heat source apparatuses or the indoor unit with an upper limit at the limiting heat exchange capacity set by the capacity setting unit. [Claim 2] The air-conditioning apparatus of claim 1, wherein the operation control unit is configured to control the refrigerant circuit to execute, when the capacity setting unit calculates a limiting heat exchange capacity, a refrigerant state check operation in which the compressor is driven at a predetermined rotation speed, and the capacity setting unit includes a storage unit storing a set heat exchange capacity of the indoor unit, and sets the limiting heat exchange capacity to be lower than the set heat exchange capacity in accordance with a state of the load side heat exchanger at the refrigerant state check operation. [Claim 3] The air-conditioning apparatus of claim 2, comprising: an indoor temperature sensor configured to detect an air temperature of an air conditioning load space; and a refrigerant temperature sensor configured to detect a temperature of refrigerant flowing into the load side heat exchanger, wherein the storage unit stores an initial heat exchange temperature difference between an initial refrigerant temperature detected by the refrigerant temperature sensor and an initial air temperature detected by the indoor temperature sensor at installation, and the capacity setting unit includes a temperature difference calculation unit configured to calculate a heat exchange temperature difference between the refrigerant temperature and the air temperature at a refrigerant state check operation; and a capacity calculation unit configured to calculate the limiting heat exchange capacity by multiplying the set heat exchange capacity with a ratio of the heat exchange temperature difference calculated by the temperature difference calculation unit to the initial heat exchange temperature difference stored in the storage unit. [Claim 4] The air-conditioning apparatus of any one of claims 1 to 3, wherein each of the heat source apparatuses includes a flow switching device configured to switch a passage of refrigerant in a cooling operation and a heating operation, and the capacity setting unit sets the limiting heat exchange capacity for each of the cooling operation and the heating operation. [Claim 5] The air-conditioning apparatus of any one of claims 1 to 4, wherein the plurality of leakage detection units each include a concentration detection unit installed in a corresponding one of the plurality of heat source apparatuses and configured to detect a concentration of leaked refrigerant; and a leakage determination unit configured to determine that there is a refrigerant leakage when the concentration of leaked refrigerant detected by the concentration detection unit is equal to or higher than a set threshold.