Air conditioner

Abstract

Provided is an air conditioner capable of accurately detecting a refrigerant leakage. An air conditioner (100) includes a refrigerant circuit (10) and a detector (61). The refrigerant circuit includes a heat source heat exchanger (23), an expansion valve (24), and a utilization heat exchanger (51), and is filled with a refrigerant. The detector detects a refrigerant leakage in the refrigerant circuit. The detector detects the refrigerant leakage by comparing a first value (P1) corresponding to a first estimated flow rate (F1) that is an estimated flow rate (F) of the refrigerant flowing through the expansion valve in a first term (T1) with a second value (P2) corresponding to a second estimated flow rate (F2) that is an estimated flow rate of the refrigerant flowing through the expansion valve in a second term (T2) before the first term.

Description

BACKGROUND OF THE INVENTION Field of the Invention

[0001] The present disclosure relates to an air conditioner.Description of the Related Art

[0002] JP 2017-26308 A discloses a refrigeration cycle apparatus that detects a refrigerant leakage in a refrigerant circuit by comparing a predicted opening degree of an expansion valve in a case where there is no refrigerant leakage with an actually measured opening degree of the expansion valve.SUMMARY OF THE INVENTION <Technical Problem>

[0003] The opening degree of the expansion valve is likely to vary depending on a circulation amount of a refrigerant in the refrigerant circuit, the capacity of the refrigeration cycle apparatus, and the environment of an air conditioning target space. Therefore, in a case of the refrigerant leakage detection method disclosed in JP 2017-26308 A, it is difficult to accurately detect a refrigerant leakage.

[0004] An object of the present disclosure is to provide an air conditioner capable of accurately detecting a refrigerant leakage.<Solution to Problem>

[0005] An air conditioner according to a first aspect includes a refrigerant circuit and a detector. The refrigerant circuit includes a heat source heat exchanger, an expansion valve, and a utilization heat exchanger, and is filled with a refrigerant. The detector detects a refrigerant leakage in the refrigerant circuit. The detector detects the refrigerant leakage by comparing a first value corresponding to a first estimated flow rate that is an estimated flow rate of the refrigerant flowing through the expansion valve in a first term with a second value corresponding to a second estimated flow rate that is an estimated flow rate of the refrigerant flowing through the expansion valve in a second term before the first term.

[0006] The detector detects the refrigerant leakage in the refrigerant circuit by using an estimated flow rate based on the flow rate of the refrigerant flowing through the expansion valve. The flow rate of the refrigerant flowing through the expansion valve is hardly affected by a circulation amount of the refrigerant in the refrigerant circuit, a capacity of a refrigeration cycle apparatus, and an environment of an air conditioning target space. Therefore, this air conditioner can accurately detect the refrigerant leakage.

[0007] An air conditioner according to a second aspect is the air conditioner according to the first aspect, in which, in the detector, a flow rate characteristic expression specifying a relationship between an opening degree of the expansion valve and an estimated value of a flow rate of the refrigerant flowing through the expansion valve is recorded. The first estimated flow rate is calculated on the basis of the opening degree of the expansion valve in the first term and the flow rate characteristic expression. The second estimated flow rate is calculated on the basis of the opening degree of the expansion valve in the second term and the flow rate characteristic expression.

[0008] This air conditioner can accurately detect the refrigerant leakage.

[0009] An air conditioner according to a third aspect is the air conditioner according to the first or second aspect, in which the first value is calculated on the basis of the first estimated flow rate and the first estimated air conditioning capacity corresponding to an air conditioning capacity in the first term. The second value is calculated on the basis of the second estimated flow rate and the second estimated air conditioning capacity corresponding to the air conditioning capacity in the second term.

[0010] This air conditioner can more accurately detect the refrigerant leakage by further considering the estimated air conditioning capacity based on the air conditioning capacity.

[0011] An air conditioner according to a fourth aspect is the air conditioner according to the third aspect, in which the first estimated air conditioning capacity is calculated on the basis of a difference between a temperature of the utilization heat exchanger in the first term and a temperature of the air conditioning target space in which the utilization heat exchanger is installed in the first term. The second estimated air conditioning capacity is calculated on the basis of a difference between the temperature of the utilization heat exchanger in the second term and the temperature of the air conditioning target space in the second term.

[0012] This air conditioner can easily obtain the estimated air conditioning capacity on the basis of the difference between the temperature of the utilization heat exchanger and the temperature of the air conditioning target space.

[0013] An air conditioner according to a fifth aspect is the air conditioner according to the fourth aspect, in which the first value is an average value of a value obtained by dividing the first estimated flow rate by a first air conditioning capacity. The second value is an average value of a value obtained by dividing the second estimated flow rate by a second air conditioning capacity.

[0014] This air conditioner can reduce an influence of disturbance such as temperature, humidity, and air volume control on the estimated flow rate by using the average value of the estimated flow rate, and thus can detect a refrigerant leakage more accurately.

[0015] An air conditioner according to a sixth aspect is the air conditioner according to any one of the first to fifth aspects, in which the detector detects the refrigerant leakage by using a change amount of the first value from the second value.

[0016] This air conditioner can accurately detect the refrigerant leakage.

[0017] An air conditioner according to a seventh aspect is the air conditioner according to any one of the first to sixth aspects, in which the detector detects the refrigerant leakage by using a change rate of the first value with respect to the second value.

[0018] This air conditioner can accurately detect the refrigerant leakage.

[0019] An air conditioner according to an eighth aspect is the air conditioner according to any one of the first to seventh aspects, in which the refrigerant has flammability.

[0020] This air conditioner can accurately detect a leakage of a flammable refrigerant.

[0021] An air conditioner according to a ninth aspect is the air conditioner according to any one of the first to eighth aspects, in which the refrigerant is propane.

[0022] This air conditioner can accurately detect a leakage of propane which is a flammable refrigerant.

[0023] An air conditioner according to a tenth aspect is the air conditioner according to any one of the first to ninth aspects, and further includes a notifier that notifies a detection result when the detector detects the refrigerant leakage.

[0024] This air conditioner can notify a user of the detection result of the refrigerant leakage.

[0025] An air conditioner according to an eleventh aspect is the air conditioners according to any one of the first to tenth aspects, in which the air conditioner continues the air conditioning operation after the notifier issues a notification.

[0026] An air conditioner according to a twelfth aspect is the air conditioner according to any one of the first to tenth aspects, and further includes a refrigerant sensor that detects the refrigerant leakage. The air conditioner stops the air conditioning operation when the refrigerant sensor detects the refrigerant leakage during the air conditioning operation, and continues the air conditioning operation when the detector detects the refrigerant leakage during the air conditioning operation.

[0027] An air conditioner according to a thirteenth aspect is the air conditioner according to any one of the first to twelfth aspects, in which both of the heat source heat exchanger and the utilization heat exchanger include a heat transfer tube. At least one of the heat source heat exchanger or the utilization heat exchanger includes the heat transfer tube made of aluminum.

[0028] This air conditioner can accurately detect the refrigerant leakage even when the refrigerant leaks from the aluminum heat transfer tube.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 is a schematic configuration diagram of an air conditioner 100 according to an embodiment of the present disclosure; FIG. 2 is a block diagram of a control unit 60; FIG. 3 is a flowchart showing a control flow of sampling processing; FIG. 4 is a conceptual diagram of an average detection variable PQa; FIG. 5 is a flowchart showing a control flow of leakage determination processing; FIG. 6 is a conceptual diagram showing determination processing; FIG. 7A is a graph showing a result of evaluating an influence of an air volume on a detection variable PQ in a heating operation; FIG. 7B is a graph showing a result of evaluating an influence of the air volume on the detection variable PQ in a cooling operation; FIG. 8A is a graph showing a result of evaluating an influence of an environmental temperature on the detection variable PQ in the heating operation; and FIG. 8B is a graph showing a result of evaluating an influence of the environmental temperature on the detection variable PQ in the cooling operation. DESCRIPTION OF EMBODIMENTS <Embodiment>(1) Overall configuration

[0030] FIG. 1 is a schematic configuration diagram of an air conditioner 100 according to an embodiment of the present disclosure. The air conditioner 100 executes a vapor compression refrigeration cycle operation in a refrigerant circuit 10. The air conditioner 100 executes the refrigeration cycle operation to implement an air conditioning operation of an air conditioning target space (not shown). The air conditioning operation includes a cooling operation and a heating operation. The air conditioner 100 mainly includes one heat source unit 20, one utilization unit 50, a liquid refrigerant connection pipe 2, a gas refrigerant connection pipe 4, and a control unit 60.

[0031] The refrigerant circuit 10 is configured by connecting each device of the heat source unit 20 and the utilization unit 50 to the liquid refrigerant connection pipe 2 and the gas refrigerant connection pipe 4 via refrigerant pipes. Specifically, the refrigerant circuit 10 includes a compressor 21, a flow direction switching mechanism 22, a heat source heat exchanger 23, an expansion valve 24, a utilization heat exchanger 51, the liquid refrigerant connection pipe 2, and the gas refrigerant connection pipe 4, which are connected via the refrigerant pipes. The refrigerant is sealed in the refrigerant circuit 10. The refrigerant sealed in the refrigerant circuit 10 is a flammable refrigerant such as propane.

[0032] Although described in detail later, the control unit 60 has a function of detecting a refrigerant leakage from the refrigerant circuit 10.(2) Detailed configuration(2-1) Utilization unit 50

[0033] The utilization unit 50 includes the utilization heat exchanger 51, a utilization fan 52, a notifier 53, a first temperature sensor 54, a second temperature sensor 55, and a refrigerant sensor 56. The utilization unit 50 is installed in the air conditioning target space, for example.(2-1-1) Utilization heat exchanger 51

[0034] The utilization heat exchanger 51 exchanges heat between the refrigerant flowing inside and air in the air conditioning target space. The utilization heat exchanger 51 has a liquid side end 51a and a gas side end 51b.

[0035] The liquid side end 51a is connected to the liquid refrigerant connection pipe 2 via a refrigerant pipe. The gas side end 51b is connected to the gas refrigerant connection pipe 4 via a refrigerant pipe.(2-1-2) Utilization fan 52

[0036] The utilization fan 52 supplies air to the utilization heat exchanger 51. The utilization fan 52 is driven by a motor 52a. The number of rotations of the motor 52a is controlled by the control unit 60.(2-1-3) Notifier 53

[0037] When the control unit 60 detects a refrigerant leakage, the notifier 53 notifies a user or the like of a detection result. The notifier 53 is controlled by the control unit 60. The notifier 53 includes an LED (not shown). When detecting a refrigerant leakage, the control unit 60 causes the LED of the notifier 53 to blink. Accordingly, the notifier 53 notifies the detection result.(2-1-4) First temperature sensor 54

[0038] The first temperature sensor 54 detects a temperature Th of the utilization heat exchanger 51. The control unit 60 receives the temperature Th detected by the first temperature sensor 54.(2-1-5) Second temperature sensor 55

[0039] The second temperature sensor 55 detects a temperature Tr of the air conditioning target space. The control unit 60 receives the temperature Tr detected by the second temperature sensor 55.(2-1-6) Refrigerant sensor 56

[0040] The refrigerant sensor 56 detects the refrigerant. Specifically, the refrigerant sensor 56 detects the refrigerant when the concentration of the leaking refrigerant reaches or exceeds a predetermined value. The refrigerant sensor 56 is accommodated in the utilization unit 50 and detects (a leakage of) the refrigerant in the air conditioning target space. The control unit 60 receives a detection result of the refrigerant sensor 56.(2-2) Heat source unit 20

[0041] The heat source unit 20 includes the compressor 21, the flow direction switching mechanism 22, the heat source heat exchanger 23, the expansion valve 24, the accumulator 25, the shutoff valve 26, and a heat source fan 27. The heat source unit 20 is disposed, for example, outside the air conditioning target space.(2-2-1) Compressor 21

[0042] The compressor 21 sucks a low-pressure refrigerant in a refrigeration cycle from a suction pipe 21a, compresses the refrigerant by a compression mechanism (not shown), and discharges the refrigerant as a high-pressure refrigerant in a refrigeration cycle to a discharge pipe 21b. The capacity of the compressor 21 is controlled by the control unit 60. An operating capacity of the compressor 21 is controlled by controlling the number of rotations of a motor (not shown) that drives a compression mechanism.(2-2-2) Flow direction switching mechanism 22

[0043] The flow direction switching mechanism 22 switches between a first state and a second state to switch the direction in which the refrigerant flows. The flow direction switching mechanism 22 is switched between the first state and the second state by the control unit 60. In the present embodiment, the flow direction switching mechanism 22 is a four-way switching valve.

[0044] In the first state, the flow direction switching mechanism 22 causes an inlet 25a of the accumulator 25 to communicate with the gas refrigerant connection pipe 4, and causes the discharge pipe 21b of the compressor 21 to communicate with the gas side end 23b of the heat source heat exchanger 23 (see a solid line in the flow direction switching mechanism 22 in FIG. 1). In the second state, the flow direction switching mechanism 22 causes the inlet 25a of the accumulator 25 to communicate with the gas side end 23b of the heat source heat exchanger 23, and causes the discharge pipe 21b to communicate with the gas refrigerant connection pipe 4 (see a broken line in the flow direction switching mechanism 22 in FIG. 1).(2-2-3) Heat source heat exchanger 23

[0045] The heat source heat exchanger 23 causes heat exchange between a refrigerant flowing inside and air (heat source air) at an installation site of the heat source unit 20. The heat source heat exchanger 23 has the liquid side end 23a and the gas side end 23b.

[0046] The liquid side end 23a is connected to the liquid refrigerant connection pipe 2 via a refrigerant pipe. The gas side end 23b is connected to the gas refrigerant connection pipe 4 via a refrigerant pipe.(2-2-4) Expansion valve 24

[0047] The expansion valve 24 adjusts a pressure and / or a flow rate of the refrigerant flowing through the refrigerant circuit 10. The expansion valve 24 is provided in a refrigerant pipe connecting the liquid refrigerant connection pipe 2 and the liquid side end 23a of the heat source heat exchanger 23. The opening degree of the expansion valve 24 is controlled by the control unit 60.

[0048] Specifically, the expansion valve 24 is an electric expansion valve including a stepping motor and a valve body (both not shown) that opens and closes in accordance with the rotation of the stepping motor. The stepping motor receives a pulse signal output from the control unit 60 and rotates to drive the valve body. As a result, the control unit 60 controls the opening degree of the expansion valve 24 via the pulse signal.(2-2-5) Accumulator 25

[0049] The accumulator 25 separates the refrigerant flowing inside into a gas refrigerant and a liquid refrigerant. The accumulator 25 stores therein surplus refrigerant generated in response to, for example, a fluctuation in an operation load of the utilization unit 50. The accumulator 25 has the inlet 25a and an exhaust port 25b.

[0050] The inlet 25a is connected to the flow direction switching mechanism 22. The exhaust port 25b is connected to the suction pipe 21a of the compressor 21.(2-2-6) Shutoff valve 26

[0051] The shutoff valve 26 is closed to block the flow of the refrigerant flowing through the refrigerant pipe. The shutoff valve 26 includes a liquid-side shutoff valve 26a and a gas-side shutoff valve 26b. The shutoff valve 26 is, for example, a manually operated valve.

[0052] The liquid-side shutoff valve 26a is provided between the expansion valve 24 and the liquid refrigerant connection pipe 2 of the refrigerant pipe connecting the liquid side end 23a of the heat source heat exchanger 23 and the liquid refrigerant connection pipe 2.

[0053] The gas-side shutoff valve 26b is provided in a refrigerant pipe connecting the flow direction switching mechanism 22 and the gas refrigerant connection pipe 4.(2-2-7) Heat source fan 27

[0054] The heat source fan 27 supplies air to the heat source heat exchanger 23. The heat source fan 27 is driven by a motor 27a. The number of rotations of the motor 27a is controlled by the control unit 60.(2-3) Liquid refrigerant connection pipe 2 and gas refrigerant connection pipe 4

[0055] The liquid refrigerant connection pipe 2 and the gas refrigerant connection pipe 4 are pipes connecting the heat source unit 20 and the utilization unit 50.(2-4) Control unit

[0056] The control unit 60 controls the operation of each device of the heat source unit 20 and the utilization unit 50 to implement a refrigeration cycle operation and a refrigerant recovery operation, and also functions as the detector 61 that detects a refrigerant leakage in the refrigerant circuit 10. Although described in detail later, the detector 61 performs leakage detection processing of detecting a refrigerant leakage in the refrigerant circuit 10 on the basis of an estimated flow rate of the refrigerant flowing through the expansion valve 24. In the control unit 60 (detector 61), a flow rate characteristic expression specifying a relationship between the opening degree of expansion valve 24 and an estimated value of the flow rate of the refrigerant flowing through the expansion valve 24 is recorded in a storage device to be described later. As described above, since the control unit 60 controls the opening degree of the expansion valve 24 via the pulse signal, the flow rate characteristic expression may specify the relationship between a frequency of the pulse signal corresponding to the opening degree of the expansion valve 24 and the estimated value of the flow rate of the refrigerant flowing through the expansion valve 24.

[0057] FIG. 2 is a block diagram of the control unit 60. As shown in FIG. 2, the control unit 60 is electrically connected to the compressor 21, the flow direction switching mechanism 22, the expansion valve 24, the motor 27a of the heat source fan 27, the motor 52a of the utilization fan 52, and the notifier 53 so as to be able to transmit and receive control signals, and controls the operations of these units. The control unit 60 is electrically connected to the first temperature sensor 54 so as to be able to receive the temperature Th. The control unit 60 is electrically connected to the second temperature sensor 55 so as to be able to receive the temperature Tr. The control unit 60 is electrically connected to the refrigerant sensor 56 so as to be able to receive the detection result. The user of the air conditioner 100 instructs the control unit 60 via a remote controller (not shown) to cause the air conditioner 100 to start or end the refrigeration cycle operation. The control unit 60 may be accommodated in either the utilization unit 50 or the heat source unit 20, may be accommodated in both the utilization unit 50 and the heat source unit 20, or may be installed separately from the utilization unit 50 and the heat source unit 20.

[0058] The control unit 60 is implemented by a computer. The control unit 60 includes a control calculation device and a storage device (both not shown). As the control calculation device, a processor such as a CPU or a GPU can be used. The control calculation device reads a program stored in the storage device and performs predetermined calculation processing in accordance with the program. Furthermore, the control calculation device can write a calculation result in the storage device and read information stored in the storage device in accordance with the program.(2-5) Operation of air conditioner

[0059] The control of operations of the air conditioner 100 in the cooling operation, the heating operation, and the refrigerant recovery operation will be described.(2-5-1) Cooling operation

[0060] When detecting an instruction to start the cooling operation sent from the remote controller or the like, the control unit 60 sets the flow direction switching mechanism 22 to the first state and starts the operations of the compressor 21, the heat source fan 27, and the utilization fan 52.

[0061] The control unit 60 controls the number of rotations of the motor 27a of the heat source fan 27 and the number of rotations of the motor 52a of the utilization fan 52 to predetermined numbers of rotations. For example, the control unit 60 controls the number of rotations of the motor 27a to a maximum number of rotations. The control unit 60 appropriately controls the number of rotations of the motor 52a on the basis of an air volume instruction input to the remote controller.

[0062] The control unit 60 controls the opening degree of the expansion valve 24 such that a degree of superheating of the refrigerant approaches a predetermined target degree of superheating. The control unit 60 controls the operating capacity of the compressor 21 such that an evaporation temperature approaches a predetermined target evaporation temperature.

[0063] When the operation of the compressor 21 is started, a low-pressure gas refrigerant in the refrigeration cycle is sucked into the compressor 21 from the suction pipe 21a and compressed to become a high-pressure gas refrigerant in the refrigeration cycle. When discharged from the discharge pipe 21b, the high-pressure gas refrigerant is sent to the heat source heat exchanger 23 via the flow direction switching mechanism 22. The refrigerant having flowed into the heat source heat exchanger 23 exchanges heat with the heat source air supplied by the heat source fan 27 to be condensed into a high-pressure liquid refrigerant. The high-pressure liquid refrigerant having exited the heat source heat exchanger 23 is decompressed by the expansion valve 24 to become a refrigerant in a gas-liquid two-phase state, and is sent to the liquid refrigerant connection pipe 2. The refrigerant in the gas-liquid two-phase state having passed through the liquid refrigerant connection pipe 2 and flowed into the utilization unit 50 is sent to the utilization heat exchanger 51. The refrigerant having flowed into the utilization heat exchanger 51 exchanges heat with air in the air conditioning target space supplied to the utilization heat exchanger 51 by the utilization fan 52 to be evaporated into a low-pressure gas refrigerant. The air supplied to the utilization heat exchanger 51 exchanges heat with the refrigerant flowing through the utilization heat exchanger 51 to be cooled, and then is blown out into the air conditioning target space. The low-pressure gas refrigerant having exited the utilization heat exchanger 51 is sent to the gas refrigerant connection pipe 4. The refrigerant having passed through the gas refrigerant connection pipe 4 and flowed into the heat source unit 20 flows into the accumulator 25 from the inlet 25a via the flow direction switching mechanism 22. The low-pressure gas refrigerant having flowed into the accumulator 25 exits the accumulator 25 from the exhaust port 25b, and is then sucked into the compressor 21 again.(2-5-2) Heating operation

[0064] When detecting an instruction to start the heating operation sent from the remote controller or the like, the control unit 60 sets the flow direction switching mechanism 22 to the second state and starts the operations of the compressor 21, the heat source fan 27, and the utilization fan 52.

[0065] The control unit 60 controls the number of rotations of the motor 27a of the heat source fan 27 and the number of rotations of the motor 52a of the utilization fan 52 to predetermined numbers of rotations. For example, the control unit 60 controls the number of rotations of the motor 27a to a maximum number of rotations. The control unit 60 appropriately controls the number of rotations of the motor 52a on the basis of an air volume instruction input to the remote controller.

[0066] The control unit 60 controls the opening degree of the expansion valve 24 such that a degree of subcooling of the refrigerant approaches a predetermined target degree of subcooling. The control unit 60 controls the operating capacity of the compressor 21 such that a condensation temperature approaches a predetermined target condensation temperature.

[0067] When the operation of the compressor 21 is started, a low-pressure gas refrigerant in the refrigeration cycle is sucked into the compressor 21 from the suction pipe 21a and compressed to become a high-pressure gas refrigerant in the refrigeration cycle. When discharged from the discharge pipe 21b, the high-pressure gas refrigerant is sent to the utilization heat exchanger 51 via the flow direction switching mechanism 22. The refrigerant having flowed into the utilization heat exchanger 51 exchanges heat with air in the air conditioning target space supplied by the utilization fan 52 to be condensed into a high-pressure liquid refrigerant. The air supplied to the utilization heat exchanger 51 exchanges heat with the refrigerant flowing through the utilization heat exchanger 51 to be heated, and then is blown out into the air conditioning target space. The high-pressure liquid refrigerant having exited the utilization heat exchanger 51 is sent to the liquid refrigerant connection pipe 2. The refrigerant having passed through the liquid refrigerant connection pipe 2 and flowed into the heat source unit 20 is decompressed at the expansion valve 24 to become a refrigerant in a gas-liquid two-phase state, and is sent to the heat source heat exchanger 23. The refrigerant having flowed into the heat source heat exchanger 23 exchanges heat with the heat source air supplied to the heat source heat exchanger 23 by the heat source fan 27 and to be evaporated into a low-pressure gas refrigerant. The low-pressure gas refrigerant having exited the heat source heat exchanger 23 flows into the accumulator 25 from the inlet 25a via the flow direction switching mechanism 22. The low-pressure gas refrigerant having flowed into the accumulator 25 exits the accumulator 25 from the exhaust port 25b, and is then sucked into the compressor 21 again.(2-5-3) Leakage detection processing(2-5-3-1) Outline

[0068] In the leakage detection processing, the detector 61 compares a first value P1 with a second value P2 to detect a refrigerant leakage. The first value P1 is a value corresponding to a first estimated flow rate F1 that is an estimated flow rate of the refrigerant flowing through the expansion valve in a first term T1. The second value P2 is a value corresponding to a second estimated flow rate F2 that is an estimated flow rate of the refrigerant flowing through the expansion valve in a second term T2 before the first term T1. Specifically, the detector 61 detects the refrigerant leakage by using a change amount of the first value P1 from the second value P2.

[0069] The first estimated flow rate F1 is calculated on the basis of the opening degree of the expansion valve 24 in the first term T1 and the flow rate characteristic expression. The second estimated flow rate F2 is calculated on the basis of the opening degree of the expansion valve 24 in the second term T2 and the flow rate characteristic expression.

[0070] The first value P1 is calculated on the basis of the first estimated flow rate F1 and a first estimated air conditioning capacity C1 corresponding to an air conditioning capacity in the first term T1. The second value P2 is calculated on the basis of the second estimated flow rate F2 and a second estimated air conditioning capacity C2 corresponding to the air conditioning capacity in the second term T2. Specifically, the first value P1 is an average value of a value (first average detection variable group PQa1 to be described later) obtained by dividing the first estimated flow rate F1 by the first estimated air conditioning capacity C1. The second value P2 is an average value of a value (second average detection variable group PQa2 to be described later) obtained by dividing the second estimated flow rate F2 by the second estimated air conditioning capacity C2.

[0071] The first estimated air conditioning capacity C1 is calculated on the basis of a difference between the temperature Th of the utilization heat exchanger in the first term T1 and the temperature Tr of the air conditioning target space in which the utilization heat exchanger is installed in the first term T1. The second estimated air conditioning capacity C2 is calculated on the basis of a difference between the temperature Th of the utilization heat exchanger in the second term T2 and the temperature Tr of the air conditioning target space in the second term T2.

[0072] The detector 61 executes the leakage detection processing in both the cooling operation and the heating operation. The detector 61 executes the leakage detection processing in the cooling operation and the leakage detection processing in the heating operation as separate processing.(2-5-3-2) Control flow

[0073] Hereinafter, a specific control flow of the leakage detection processing will be described. The leakage detection processing includes sampling processing and leakage determination processing.(Sampling processing)

[0074] In the sampling processing, the detector 61 calculates an average detection variable PQa, which is a variable used for refrigerant leakage determination in the leakage determination processing, from a sampled detection variable PQ, and records the average detection variable PQa in the storage device. FIG. 3 is a flowchart showing a control flow of the sampling processing. FIG. 4 is a conceptual diagram of the average detection variable PQa. The detector 61 repeats the sampling processing while the air conditioner 100 is activated.

[0075] In step S100, the detector 61 advances the processing to step S110 or step S100 on the basis of whether a predetermined sampling period Ps has been reached. Specifically, the detector 61 acquires time T1 from a start of the sampling processing and time T2 from a previous sampling (execution of the processing in step S110). When determining that one of time T1 or time T2 reaches the sampling period Ps (Yes), the detector 61 advances the processing to step S110, and when determining that one of time T1 or time T2 does not reach the sampling period Ps (No), the detector 61 advances the processing to step S100. In other words, the detector 61 repeats step S100 until the sampling period Ps has been reached. Although not limited, the sampling period Ps is, for example, 1 / 12 seconds (1 / 12 seconds).

[0076] The detector 61 acquires (samples) an estimated flow rate F of the refrigerant flowing through the expansion valve 24 during the sampling period Ps in step S110, and advances the processing to step S120. Specifically, the detector 61 calculates the estimated flow rate F from the opening degree of the expansion valve 24 during the sampling and the flow rate characteristic expression of the expansion valve 24 recorded in the storage device. The estimated flow rate F is an example of the first estimated flow rate F1 and the second estimated flow rate F2.

[0077] The detector 61 calculates an estimated air conditioning capacity C in the sampling period Ps in step S120, and advances the processing to step S130. Specifically, the detector 61 sets, as the estimated air conditioning capacity C, an absolute value of a difference between the temperature Th detected by the first temperature sensor 54 in the sampling period Ps and the temperature Tr detected by the second temperature sensor 55 in the sampling period Ps (C = |Th - Tr|). The estimated air conditioning capacity C is an example of the first estimated air conditioning capacity C1 and the second estimated air conditioning capacity C2.

[0078] The detector 61 calculates the detection variable PQ in the sampling period Ps in step S130, and advances the processing to step S140. Specifically, the detector 61 sets a value obtained by dividing the estimated flow rate F by the estimated air conditioning capacity C as the detection variable PQ (PQ = F / C).

[0079] The detector 61 records the calculated detection variable PQ in the storage device in step S140, and advances the processing to step S150.

[0080] In step S150, the detector 61 refers to the storage device to calculate the average detection variable PQa obtained by averaging all the detection variables PQ sampled on that day, stores the detection variable PQ in the storage device for each sampling date, and advances the processing to step S100. When the average detection variable PQa calculated from the detection variable PQ calculated on the same day is already recorded in the storage device, the detector 61 rewrites the old average detection variable PQa with the newly calculated average detection variable PQa.

[0081] As shown in FIG. 4, the detector 61 repeats the sampling processing, and thus, the average detection variable PQa calculated from the plurality of detection variables PQ(PQ(0), PQ(1)...) for one day is recorded in the storage device for each date (PQa(0), PQa(-1)...).

[0082] As described above, the sampling processing is executed while the air conditioner 100 is activated. Therefore, the detector 61 does not calculate and record the average detection variable PQa for the day on which the air conditioner 100 is not activated. As a result, only the average detection variable PQa for the day on which the air conditioner 100 is activated is recorded in the storage device. The detector 61 handles the plurality of average detection variables PQa recorded in the storage device as a data group PQag arranged in the order of the date on which the average detection variable PQa is calculated.

[0083] In FIG. 4, "PQ(0), PQ(1), PQ(2)..." indicates a plurality of detection variables PQ recorded on the same day. "PQa(0), PQa(-1), PQa(-2)..." indicates an array of the plurality of average detection variables PQa included in the data group PQag. "PQa(n)" indicates the average detection variable PQa of the latest date with PQa(0), and as a number n in the parentheses is smaller, "PQa(n)" indicates the average detection variable PQa of the older date.

[0084] The detector 61 may end the sampling processing at a point in time when the number of sampled detection variables PQ reaches a predetermined number or at a point in time when the time from the start has elapsed a predetermined time.(Leakage determination processing)

[0085] In the leakage determination processing, the detector 61 performs the refrigerant leakage determination using the average detection variable PQa recorded in the storage device in the sampling processing. FIG. 5 is a flowchart showing a control flow of the leakage determination processing. FIG. 6 is a conceptual diagram showing the determination processing.

[0086] The detector 61 executes the leakage determination processing once a day. Although not limited, the detector 61 can execute the leakage determination processing at a timing when the air conditioner 100 is first activated for the day, for example.

[0087] When starting the leakage determination processing, the detector 61 calculates the first value P1 in step S200 and advances the processing to step S210. The first value P1 is an average value of a group (hereinafter referred to as first average detection variable group PQa1) of the average detection variable PQa for latest X days from the day on which PQa(0), which is the latest average detection variable PQa, is calculated in the data group PQag. X is an integer greater than or equal to 2. A case where X is 3 is shown in FIG. 6 as an example. X days is an example of the first term T1.

[0088] The detector 61 calculates the second value P2 in step S210 and advances the processing to step S220. The second value P2 does not include the average detection variable PQa of the first average detection variable group PQa1, and is an average value of a group (hereinafter referred to as second average detection variable group PQa2) of the average detection variable PQa for consecutive Y days in the data group PQag.

[0089] As shown in FIG. 6, the detector 61 determines the second average detection variable group PQa2 such that the average detection variable PQa for Z consecutive days in the data group PQag exists between the average detection variable PQa (PQa(-7) in FIG. 6) of the latest date of the second average detection variable group PQa2 and the average detection variable PQa (PQa(-3) in FIG. 6) of the last date of the first average detection variable group PQa1. Y is an integer greater than or equal to 2. Z is an integer greater than or equal to 0. A case where Y and Z are 3 is shown in FIG.6 as an example. Y days is an example of the second term T2.

[0090] In step S220, the detector 61 determines whether to advance the processing to step S230 or to step S260 on the basis of the change amount of the first value P1 from the second value P2. Specifically, when the first value P1 is greater than a value obtained by multiplying the second value P2 by a predetermined coefficient K (Yes), the detector 61 advances the processing to step S230, and when the first value P1 is not greater than the value obtained by multiplying the second value P2 by the coefficient K (No), the detector 61 advances the processing to step S260. The coefficient K is greater than 0.

[0091] In step S230, the detector 61 increments a counter c recorded in the storage device, and advances the processing to step S240. The incremented counter c is recorded in the storage device, and is also referred to in the leakage determination processing on and after the next day.

[0092] In step S240, the detector 61 compares the counter c with a predetermined number N, and determines whether to advance the processing to step S250 or end the control flow. Specifically, the detector 61 advances the processing to step S250 when the counter c is greater than the number N (Yes), and ends the control flow when the counter c is not greater than the number N (No). The number N is an integer greater than or equal to 1.

[0093] In step S250, the detector 61 causes the notifier 53 to notify the detection result that the refrigerant leakage has been detected, and ends the control flow.

[0094] In step S260, the detector 61 resets the counter c to 0, and ends the control flow.

[0095] As described above, in the leakage determination processing, when the average value (first value P1) of the plurality of latest average detection variables PQa is greater than the value obtained by multiplying the average value (second value P2) of the plurality of past average detection variables PQa by the coefficient K, the detector 61 determines that there is a risk of a refrigerant leakage and increments the counter c. When it is determined that there is a refrigerant leakage for N or more consecutive days (when the counter c is greater than N), the detector 61 determines that a refrigerant leakage has been detected and causes the notifier 53 to notify of the detection result.

[0096] The coefficient K is a margin rate of the first value P1 with respect to the second value P2. The smaller the coefficient K, the more easily the detector 61 determines that there is a risk of refrigerant leakage.

[0097] The number N defines sensitivity of the leakage determination in the leakage determination processing. The smaller the number N, the more easily the detector 61 determines that a refrigerant leakage has been detected.(2-5-3-3) Detection variable PQ

[0098] The inventor(s) has evaluated an influence of an air volume and an environmental temperature on the detection variable PQ used to detect a refrigerant leakage.(Influence of air volume)

[0099] FIG. 7A is a graph showing a result of evaluating the influence of the air volume on the detection variable PQ in the heating operation. FIG. 7B is a graph showing a result of evaluating the influence of the air volume on the detection variable PQ in the cooling operation. In FIGS. 7A and 7B, the horizontal axis represents the capacity of the compressor 21, and the vertical axis represents the detection variable PQ.

[0100] In this evaluation, the inventor(s) calculated the detection variable PQ when the motor 52a of the utilization fan 52 is rotated by an M tap and the detection variable PQ when the motor is rotated by an L tap for each of the refrigerant circuit 10 filled with a specified amount of refrigerant, the refrigerant circuit 10 filled with 90% of the specified amount of refrigerant, and the refrigerant circuit 10 filled with 70% of the specified amount of refrigerant. The L tap has a lower air volume than the M tap.

[0101] In FIGS. 7A and 7B, the detection variable PQ when the motor 52a of the utilization fan 52 is rotated by the M tap is indicated by a square, and an approximate line obtained from the detection variable PQ is indicated by a solid line. In FIGS. 7A and 7B, the detection variable PQ with rotation by the L tap is indicated by a circle, and an approximate line obtained from the detection variable PQ is indicated by a dotted line.

[0102] Among these approximate lines, a result obtained by using the refrigerant circuit 10 filled with a specified amount of refrigerant is denoted by reference sign "La100", a result obtained by using the refrigerant circuit 10 filled with 90% of the specified amount of refrigerant is denoted by reference sign "La90", and a result obtained by using the refrigerant circuit 10 filled with 70% of the specified amount of refrigerant is denoted by reference sign "La70".

[0103] As shown in FIGS. 7A and 7B, it has been confirmed that the change in the detection variable PQ with the change in the air volume is sufficiently smaller than the change with a refrigerant filling amount.(Influence of environmental temperature)

[0104] FIG. 8A is a graph showing a result of evaluating an influence of the environmental temperature on the detection variable PQ in the heating operation. FIG. 8B is a graph showing a result of evaluating an influence of the environmental temperature on the detection variable PQ in the cooling operation. In FIGS. 8A and 8B, the horizontal axis represents the capacity of the compressor 21, and the vertical axis represents the detection variable PQ.

[0105] In this evaluation, the inventor(s) calculated the detection variable PQ when the capacity of the compressor 21 is changed for each of the refrigerant circuit 10 filled with a specified amount of refrigerant, the refrigerant circuit 10 filled with 90% of the specified amount of refrigerant, and the refrigerant circuit 10 filled with 70% of the specified amount of refrigerant.

[0106] In FIGS. 8A and 8B, an approximate line obtained from the detection variable PQ calculated when the refrigerant circuit 10 filled with a specified amount of refrigerant is used is denoted by a reference sign "Lb100". An approximate line obtained from the detection variable PQ calculated when the refrigerant circuit 10 filled with 90% of the specified amount of refrigerant is used is denoted by a reference sign "Lb90". An approximate line obtained from the detection variable PQ calculated when the refrigerant circuit 10 filled with 70% of the specified amount of refrigerant is used is denoted by a reference sign "Lb70".

[0107] As shown in FIGS. 8A and 8B, it has been confirmed that the change in the detection variable PQ with the change in the environmental temperature is sufficiently smaller than the change with the refrigerant filling amount.(Summary of evaluation results)

[0108] From the above evaluation results, it has been confirmed that the influence of the change in the air volume and the change in the environmental temperature on the detection variable PQ is sufficiently smaller than the change in the refrigerant filling amount. Therefore, it has been confirmed that the refrigerant leakage in the refrigerant circuit 10 can be detected while suppressing the influence of the air volume and the environmental temperature by using the detection variable PQ. In this evaluation, a slightly flammable refrigerant R32 is used as the refrigerant to be charged in the refrigerant circuit 10. However, it is estimated that a similar result can be obtained in the refrigerant circuit 10 filled with a highly flammable refrigerant such as propane.(3) Modifications(3-1) Modification A

[0109] The detector 61 may detect the refrigerant leakage by using a change rate of the first value P1 with respect to the second value P2. Specifically, in step S220, the detector 61 may determine whether to advance the processing to step S230 or to step S260 on the basis of the change rate of the first value P1 with respect to the second value P2 instead of the change amount of the first value P1 from the second value P2.

[0110] In this case, when the value obtained by dividing the first value P1 by the second value P2 is greater than a predetermined value R (Yes), the detector 61 advances the processing to step S230, and when the value obtained by dividing the first value P1 by the second value P2 is not greater than the value R (No), the detector advances the processing to step S260.(3-2) Modification B

[0111] The notifier 53 is not limited to the above mode as long as the detection result can be notified to the user or the like. Although not limited, the notifier 53 may be configured to notify a mobile terminal such as a smartphone owned by the user of the detection result by using a computer network technology such as the Internet or Wi-Fi (registered trademark).(3-3) Modification C

[0112] The air conditioner 100 may continue the air conditioning operation after the notifier 53 issues a notification.(3-4) Modification D

[0113] The control unit 60 stops the air conditioning operation when the refrigerant sensor detects a refrigerant leakage, and continues the air conditioning operation when the detector 61 detects a refrigerant leakage during the air conditioning operation.(3-5) Modification E

[0114] For example, at least one of the heat source heat exchanger 23 or the utilization heat exchanger 51 may be a fin-and-tube heat exchanger including a plurality of heat transfer tubes and a plurality of fins (not shown). In this case, for example, the heat transfer tube may be made of aluminum.(3-6) Modification F

[0115] For example, the estimated flow rate F may be a value obtained by correcting a value calculated from the opening degree of the expansion valve 24 in the sampling period Ps and the flow rate characteristic expression recorded in the storage device on the basis of a differential pressure between the refrigerant before and after the expansion valve 24.

[0116] The flow rate of the refrigerant flowing through expansion valve 24 obtained from the flow rate characteristic expression is an estimated value as described above. This estimated value of the flow rate may have some errors from the actual flow rate mainly due to the differential pressure between the refrigerant before and after expansion valve 24. Therefore, by correcting the value calculated from the opening degree of the expansion valve 24 and the flow rate characteristic expression recorded in the storage device on the basis of the differential pressure between the refrigerant before and after the expansion valve 24 to obtain the estimated flow rate F, the detector 61 can detect the refrigerant leakage more accurately.(3-7) Modification G

[0117] The estimated air conditioning capacity C obtained from the absolute value of the difference between the temperature Th in the sampling period Ps and the temperature Tr in the sampling period Ps may be affected by the amount of air (air volume) supplied to the utilization heat exchanger 51. Therefore, for example, the estimated air conditioning capacity C may be a value obtained by correcting the absolute value of the difference between the temperature Th in the sampling period Ps and the temperature Tr in the sampling period Ps on the basis of the air volume generated by the utilization fan 52. Specifically, the detector 61 can obtain the estimated air conditioning capacity C by multiplying the absolute value of the difference between the temperature Th in the sampling period Ps and the temperature Tr in the sampling period Ps by a coefficient based on the number of rotations or a rotation tap of the utilization fan 52.(3-8) Modification H

[0118] The values of X, Y, and Z may be different from each other.(4) Characteristics

[0119] (4-1) The air conditioner 100 includes the refrigerant circuit 10 and the detector 61. The refrigerant circuit 10 includes the heat source heat exchanger 23, the expansion valve 24, and the utilization heat exchanger 51, and is filled with the refrigerant. The detector 61 detects a refrigerant leakage in the refrigerant circuit 10. The detector 61 detects a refrigerant leakage by comparing the first value P1 corresponding to the first estimated flow rate F1 that is an estimated flow rate of the refrigerant flowing through the expansion valve 24 in the first term T1 with the second value P2 corresponding to the second estimated flow rate F2 that is an estimated flow rate of the refrigerant flowing through the expansion valve 24 in the second term T2 before the first term T1.

[0120] The detector 61 detects a refrigerant leakage in the refrigerant circuit 10 by using an estimated flow rate based on the flow rate of the refrigerant flowing through the expansion valve 24. The flow rate of the refrigerant flowing through the expansion valve 24 is hardly affected by the circulation amount of the refrigerant in the refrigerant circuit 10, the capacity of the refrigeration cycle apparatus, and the environment of the air conditioning target space. Therefore, the air conditioner 100 can accurately detect the refrigerant leakage.

[0121] (4-2) In the detector 61, the flow rate characteristic expression specifying the relationship between the opening degree of the expansion valve 24 and the estimated value of the flow rate of the refrigerant flowing through the expansion valve 24 is recorded. The first estimated flow rate F1 is calculated on the basis of the opening degree of the expansion valve 24 in the first term T1 and the flow rate characteristic expression. The second estimated flow rate F2 is calculated on the basis of the opening degree of the expansion valve 24 in the second term T2 and the flow rate characteristic expression.

[0122] The air conditioner 100 can accurately detect the refrigerant leakage.

[0123] (4-3) The first value P1 is calculated on the basis of the first estimated flow rate F1 and the first estimated air conditioning capacity corresponding to the air conditioning capacity in the first term T1. The second value P2 is calculated on the basis of the second estimated flow rate F2 and the second estimated air conditioning capacity corresponding to the air conditioning capacity in the second term T2.

[0124] The air conditioner 100 can more accurately detect the refrigerant leakage by further considering the estimated air conditioning capacity based on the air conditioning capacity.

[0125] (4-4) The first estimated air conditioning capacity is calculated on the basis of a difference between the temperature of the utilization heat exchanger 51 in the first term T1 and the temperature of the air conditioning target space in which the utilization heat exchanger 51 is installed in the first term T1. The second estimated air conditioning capacity is calculated on the basis of a difference between the temperature of the utilization heat exchanger 51 in the second term T2 and the temperature of the air conditioning target space in the second term T2.

[0126] The air conditioner 100 can easily obtain the estimated air conditioning capacity on the basis of the difference between the temperature of the utilization heat exchanger 51 and the temperature of the air conditioning target space.

[0127] (4-5) The first value P1 is an average value of a value obtained by dividing the first estimated flow rate F1 by the first estimated air conditioning capacity. The second value P2 is an average value of a value obtained by dividing the second estimated flow rate F2 by the second estimated air conditioning capacity.

[0128] The air conditioner 100 can reduce the influence of disturbance such as temperature, humidity, and air volume control on the estimated flow rate by using the average value of the estimated flow rate, and thus can detect a refrigerant leakage more accurately.

[0129] (4-6) The detector 61 detects a refrigerant leakage by using the change amount of the first value P1 from the second value P2.

[0130] The air conditioner 100 can accurately detect the refrigerant leakage.

[0131] (4-7) The detector 61 detects the refrigerant leakage by using the change rate of the first value P1 with respect to the second value P2.

[0132] The air conditioner 100 can accurately detect the refrigerant leakage.

[0133] (4-8) The refrigerant has flammability.

[0134] The air conditioner 100 can accurately detect a leakage of a flammable refrigerant.

[0135] (4-9) The refrigerant is propane.

[0136] The air conditioner 100 can accurately detect a leakage of propane which is a flammable refrigerant.

[0137] (4-10) The air conditioner 100 further includes the notifier that notifies a detection result when the detector 61 detects a refrigerant leakage.

[0138] The air conditioner 100 can notify the user of the detection result of the refrigerant leakage.

[0139] (4-11) The air conditioner 100 continues the air conditioning operation after the notifier issues a notification.

[0140] (4-12) The air conditioner 100 further includes the refrigerant sensor 56 that detects a refrigerant leakage. The air conditioner 100 stops the air conditioning operation when the refrigerant sensor 56 detects a refrigerant leakage during the air conditioning operation, and continues the air conditioning operation when the detector 61 detects a refrigerant leakage during the air conditioning operation.

[0141] (4-13) Both of the heat source heat exchanger 23 and the utilization heat exchanger 51 include the heat transfer tube. At least one of the heat source heat exchanger 23 or the utilization heat exchanger 51 includes a heat transfer tube made of aluminum.

[0142] The air conditioner 100 can accurately detect a refrigerant leakage even when the refrigerant leaks from the aluminum heat transfer tube.<Conclusion>

[0143] While the embodiments according to the present disclosure have been described above, it will be understood that various changes in forms and details can be made without departing from the gist and scope of the present disclosure recited in the claims.REFERENCE SIGNS LIST

[0144] 10refrigerant circuit 23heat source heat exchanger 24expansion valve 51utilization heat exchanger 53notifier 56refrigerant sensor 61detector 100air conditioner C1first estimated air conditioning capacity C2second estimated air conditioning capacity Festimated flow rate F1first estimated flow rate F2second estimated flow rate P1first value P2second value T1first term T2second term Thtemperature of utilization heat exchanger Trtemperature of air conditioning target space CITATION LIST PATENT LITERATURE

[0145] Patent Literature 1: JP 2017-26308 A

Claims

1. An air conditioner (100) comprising: a refrigerant circuit (10) that includes a heat source heat exchanger (23), an expansion valve (24), and a utilization heat exchanger (51) and is filled with a refrigerant; a detector (61) that detects a refrigerant leakage in the refrigerant circuit, wherein the detector compares a first value (P1) corresponding to a first estimated flow rate (F1) that is an estimated flow rate (F) of the refrigerant flowing through the expansion valve in a first term (T1) with a second value (P2) corresponding to a second estimated flow rate (F2) that is an estimated flow rate of the refrigerant flowing through the expansion valve in a second term (T2) before the first term, and detects the refrigerant leakage.

2. The air conditioner according to claim 1, wherein in the detector, a flow rate characteristic expression specifying a relationship between an opening degree of the expansion valve and an estimated value of a flow rate of the refrigerant flowing through the expansion valve is recorded, the first estimated flow rate is calculated on a basis of the opening degree of the expansion valve in the first term and the flow rate characteristic expression, and the second estimated flow rate is calculated on a basis of the opening degree of the expansion valve in the second term and the flow rate characteristic expression.

3. The air conditioner according to claim 1 or 2, wherein the first value is calculated on a basis of a first estimated air conditioning capacity (C1) corresponding to the first estimated flow rate and an air conditioning capacity in the first term, and the second value is calculated on a basis of a second estimated air conditioning capacity (C2) corresponding to the second estimated flow rate and the air conditioning capacity in the second term.

4. The air conditioner according to claim 3, wherein the first estimated air conditioning capacity is calculated on a basis of a difference between a temperature (Th) of the utilization heat exchanger in the first term and a temperature (Tr) of an air conditioning target space in which the utilization heat exchanger is installed in the first term, and the second estimated air conditioning capacity is calculated on a basis of a difference between the temperature of the utilization heat exchanger in the second term and the temperature of the air conditioning target space in the second term.

5. The air conditioner according to claim 4, wherein the first value is an average value of a value obtained by dividing the first estimated flow rate by the first estimated air conditioning capacity, and the second value is an average value of a value obtained by dividing the second estimated flow rate by the second estimated air conditioning capacity.

6. The air conditioner according to any one of claims 1 to 5, wherein the detector detects the refrigerant leakage by using a change amount of the first value from the second value.

7. The air conditioner according to any one of claims 1 to 6, wherein the detector detects the refrigerant leakage by using a change rate of the first value with respect to the second value.

8. The air conditioner according to any one of claims 1 to 7, wherein the refrigerant has flammability.

9. The air conditioner according to any one of claims 1 to 8, wherein the refrigerant is propane.

10. The air conditioner according to any one of claims 1 to 9, further comprising a notifier (53) that notifies a detection result when the detector detects the refrigerant leakage.

11. The air conditioner according to any one of claims 1 to 10, wherein the air conditioner continues an air conditioning operation after the notifier issues a notification.

12. The air conditioner according to any one of claims 1 to 10, further comprising a refrigerant sensor (56) that detects the refrigerant leakage, wherein the air conditioner stops the air conditioning operation when the refrigerant sensor detects the refrigerant leakage during the air conditioning operation, and the air conditioner continues the air conditioning operation when the detector detects the refrigerant leakage during the air conditioning operation.

13. The air conditioner according to any one of claims 1 to 12, wherein both of the heat source heat exchanger and the utilization heat exchanger include a heat transfer tube, and at least one of the heat source heat exchanger or the utilization heat exchanger includes the heat transfer tube made of aluminum.

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