AIR-CONDITIONING APPARATUS AND AIR-CONDITIONING METHOD

Abstract

An air-conditioning apparatus according to a first aspect includes a heat source device, an air-conditioning unit, a hot water supply unit, and control circuitry configured to perform a first alternate operation of alternately performing a heating operation and a hot water supply operation when a heating request and a hot water supply request are received at the same time, and to perform a second alternate operation of alternately performing a cooling operation and the hot water supply operation when a cooling request and the hot water supply request are received at the same time, in which the control circuitry is configured to perform control to make a first continuous operation time of the hot water supply operation in the first alternate operation different from a second continuous operation time of the hot water supply operation in the second alternate operation.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a U.S. National Stage Application of International Application No. PCT/JP2022/018516 filed Apr. 22, 2022, the contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an air-conditioning apparatus and an air-conditioning method.

BACKGROUND

In the related art, multi-type air-conditioning apparatuses that selectively perform an air-conditioning operation of adjusting the temperature of indoor air and a hot water supply operation of storing heat in a hot water storage tank by heating water in the hot water storage tank and boiling the water are known. Some multi-type air-conditioning apparatuses cannot perform an air-conditioning operation during a period when a hot water supply operation is performed. In such a multi-type air-conditioning apparatus, the longer a period over which the hot water supply operation is performed, the longer a period in which a hot water supply operation cannot be performed. When the hot water supply operation is performed over a long period of time, the temperature of indoor air changes, which impairs comfort.

Even when a hot water supply request for boiling water is given in response to a decrease in the amount of hot water in the hot water storage tank in the multi-type air-conditioning apparatus, technology for preventing indoor comfort from being impaired during the hot water supply request is known. For example, an air-conditioning apparatus disclosed in Patent Document 1 sets an upper limit time for continuing a hot water supply operation. This air-conditioning apparatus stops the hot water supply operation and returns to a cooling operation when the temperature of water in a hot water storage tank does not reach a target temperature even after the upper limit time is exceeded. When the hot water supply operation is stopped, the air-conditioning apparatus boils water in the hot water storage tank by electrifying an auxiliary heater provided in a hot water tank.

Patent Document

Patent Document 1

• • PCT International Publication No. WO2018/189942

However, the air-conditioning apparatus disclosed in Patent Document 1 starts a hot water supply operation using the auxiliary heater in response to returning to a cooling operation, and thus there is a problem in that the amount of electricity used increases. In particular, since the auxiliary heater is an electric heater, a hot water supply operation using the auxiliary heater consumes more power than a hot water supply operation using an air-conditioning apparatus and has lower operating efficiency, resulting in an increase in electricity consumption.

Further, even when an interruption time of an air-conditioning operation is limited to an upper limit time by setting the upper limit time for a hot water supply operation as in Patent Document 1, a cooling operation and a heating operation may differ in the amount of change in indoor temperature. That is, when an air-conditioning load is not the same between the cooling operation and the heating operation, the cooling operation and the heating operation will differ in the amount of change in indoor temperature even when an interruption time is the same between the cooling operation and the heating operation. Thus, even when an upper limit time is set for a hot water supply operation as in the air-conditioning apparatus of Patent Document 1, there is a concern that indoor comfort may be impaired.

SUMMARY

The present disclosure has been made to solve the above-described problems, and an object thereof is to provide an air-conditioning apparatus capable of suppressing an increase in power consumption and suppressing a decrease in indoor comfort even when the air-conditioning apparatus performs a hot water supply operation using an auxiliary heater, and an air-conditioning method.

An air-conditioning apparatus according to a first aspect includes a heat source device that includes a refrigerant cycle circulating a refrigerant, an air-conditioning unit configured to perform a heating operation and a cooling operation by exchanging heat between the refrigerant and indoor air, a hot water supply unit that includes a hot water storage tank and configured to perform a hot water supply operation by heating with the refrigerant, and control circuitry configured to perform a first alternate operation of alternately performing the heating operation and the hot water supply operation when a heating request and a hot water supply request are received at the same time, and to perform a second alternate operation of alternately performing the cooling operation and the hot water supply operation when a cooling request and the hot water supply request are received at the same time, in which the control circuitry is configured to perform control to make a first continuous operation time of the hot water supply operation in the first alternate operation different from a second continuous operation time of the hot water supply operation in the second alternate operation.

An air-conditioning method according to a second aspect is an air-conditioning method in an air-conditioning apparatus including a heat source device that includes a refrigerant cycle circulating a refrigerant, an air-conditioning unit configured to perform a heating operation and a cooling operation by exchanging heat between the refrigerant and indoor air, and a hot water supply unit that includes a hot water storage tank and configured to perform a hot water supply operation by heating with the refrigerant, the air-conditioning method including performing a first alternate operation of alternately performing the heating operation and the hot water supply operation when a heating request and a hot water supply request are received at the same time, and performing a second alternate operation of alternately performing the cooling operation and the hot water supply operation when a cooling request and the hot water supply request are received at the same time, in which a first continuous operation time of the hot water supply operation in the first alternate operation is different from a second continuous operation time of the hot water supply operation in the second alternate operation.

According to the present disclosure, it is possible to suppress an increase in power consumption and suppress a decrease in indoor comfort even when an air-conditioning apparatus performs a hot water supply operation using an auxiliary heater.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a circuit diagram showing an example of a configuration of an air-conditioning apparatus according to an embodiment.

FIG. 2 is a block diagram showing an example of a functional configuration of the air-conditioning apparatus according to the embodiment.

FIG. 3 is a flowchart showing an example of a specific operation procedure performed by the air-conditioning apparatus according to the embodiment.

FIG. 4 is a diagram showing an operation of the air-conditioning apparatus according to the embodiment, in which (a) is a diagram showing changes over time in an operation mode of a heat source unit, (b) is a diagram showing changes over time in water temperature in a hot water storage tank, and (c) is a diagram showing changes over time in an operation of an electric heater.

FIG. 5 is a diagram showing an example of a relationship between an outside air temperature and a threshold value T_max (H) in the embodiment.

FIG. 6 is a diagram showing an example of a relationship between an outside air temperature and a threshold value T_max (C) in the embodiment.

DETAILED DESCRIPTION

Embodiments of the present disclosure will be described below with reference to the drawings. The scope of the present disclosure is not limited to the following embodiment, and can be arbitrarily modified within the scope of the technical idea of the present disclosure. Further, in the following drawings, in order to facilitate the understanding of each configuration, the scale, number, and the like of each structure may be different from the scale, number, and the like of the actual structure.

(Configuration of Air-Conditioning Apparatus)

FIG. 1 is a circuit diagram showing an example of a configuration of an air-conditioning apparatus according to an embodiment. The air-conditioning apparatus includes, for example, a heat source unit 100, air-conditioning units 200A and 200B, a hot water supply unit 300, an air-conditioning controller 400, and a hot water supply controller 500. The air-conditioning apparatus is, for example, a multi-type air-conditioning apparatus that performs a hot water supply operation, a cooling operation, and a heating operation by performing a vapor compression type refrigeration cycle operation. The air-conditioning apparatus is installed, for example, in general households, but is not limited thereto. Although the number of air-conditioning units is two in the embodiment, the number is not limited thereto, and may be one or three or more. A refrigerant in the air-conditioning apparatus may be, for example, a type of natural refrigerant such as R410A, R32, HFO-1234yf, or hydrocarbons, but is not limited thereto.

The heat source unit 100 functions as a heat source device in the air-conditioning apparatus. The heat source unit 100 includes, for example, a compressor 102, a four-way valve 104, a heat source side heat exchanger 106, a heat source side blower 108, an accumulator 110, and a heat source control device 112. The heat source unit 100 includes, for example, a pressure sensor 120 and temperature sensors 122, 124, 126, and 128. The pressure sensor 120 and the temperature sensor 122 are provided in a refrigerant pipe on a discharge side of the compressor 102. The pressure sensor 120 detects a refrigerant pressure on the discharge side of the compressor 102. The temperature sensor 122, the temperature sensor 126, and the temperature sensor 124 are provided on a liquid side of the heat source side heat exchanger 106 to measure a refrigerant temperature at an installation location. The temperature sensor for a refrigerant only needs to be able to detect a value equivalent to a refrigerant temperature, such as the temperature of a refrigerant pipe, or a value that can be converted to a refrigerant temperature. The temperature sensor 122 detects the temperature of the refrigerant pipe on the discharge side of the compressor 102. The temperature sensor 124 detects the temperature of the refrigerant pipe near the heat source side heat exchanger 106. The temperature sensor 126 detects the temperature of the refrigerant pipe in the heat source side heat exchanger 106. The temperature detected by the temperature sensor 126 is equivalent to a condensation temperature. The temperature sensor 128 detects the temperature of air blown by the heat source side blower 108. The heat source unit 100 is connected to the air-conditioning unit 200A via refrigerant pipes 1a and 2a. The heat source unit 100 is connected to the air-conditioning unit 200B via refrigerant pipes 1b and 2b. The heat source unit 100 is connected to the hot water supply unit 300 via refrigerant pipes 1c and 2c. A pressure reducing mechanism 130a is provided in the refrigerant pipe 2a. A pressure reducing mechanism 130b is provided in the refrigerant pipe 2b. A pressure reducing mechanism 130c is provided in the refrigerant pipe 2c.

Each of the air-conditioning units 200A and 200B includes, for example, a heat exchanger 202, a blower 204, and an air-conditioning control device 206. An air blowing amount of the blower 204 can be adjusted. When the air-conditioning units 200A and 200B are collectively referred to, they are simply referred to as “air-conditioning units 200”. Each of the air-conditioning units 200A and 200B includes temperature sensors 210, 212, and 214. The temperature sensor 210 is provided on a gas side of the heat exchanger 202. The temperature sensor 212 is provided on a liquid side of the heat exchanger 202. The temperature sensors 210 and 212 detect a refrigerant temperature at an installation location. The temperature sensor 214 is provided at an air intake port of the blower 204. The temperature sensor 214 measures an air temperature in a room corresponding to the installation location of the air-conditioning units 200A and 200B.

The hot water supply unit 300 includes, for example, a heat exchanger 302, a hot water storage tank 304, an electric heater 306, a hot water supply control device 308, and temperature sensors 310 and 312. The heat exchanger 302 exchanges heat between water stored in the hot water storage tank 304 and a refrigerant. The hot water storage tank 304 stores the heat-exchanged water. The hot water storage tank 304 discharges hot water from the top of the tank in response to a hot water supply request output from the hot water supply control device 308. Low-temperature water is supplied to the hot water storage tank 304 from a lower part of the tank in an amount equal to the amount of hot water discharged. The hot water storage tank 304 is, for example, a liquid-filled tank. The electric heater 306 is a heating unit that heats water in the hot water storage tank 304 by heating in response to the supply of electric power. The electric heater 306 functions as an auxiliary heater that assists a hot water supply operation by the heat source unit 100. Thereby, the hot water supply unit 300 can perform a boiling operation using the electric heater 306. The electric heater 306 functions as a second heat source in the air-conditioning apparatus. The temperature sensor 310 is installed in hot water storage tank 304 and measures the temperature of the water in hot water storage tank 304. The temperature sensor 312 is installed on the liquid side of the hot water storage tank 304 and detects a refrigerant temperature at the installation location.

FIG. 2 is a block diagram showing an example of a functional configuration of the air-conditioning apparatus according to the embodiment.

The heat source control device 112 is a computer realized by, for example, a central processing unit (CPU) executing a program. The heat source control device 112 controls the heat source unit 100 based on an air-conditioning request output from the air-conditioning controller 400 or a hot water supply request output from the hot water supply controller 500. The heat source control device 112 includes, for example, a measurement unit 112a, a communication unit 112b, a control unit 112c, and a storage unit 112d. The measurement unit 112a measures various temperatures and pressures by inputting signals detected by the temperature sensors 122, 124, 126, and 128 and the pressure sensor 120, and performing calculations based on the input signals. The communication unit 112b is connected to each part of the heat source unit 100 via communication lines, and transmits and receives various data and information. The communication unit 112b inputs an air-conditioning request output from the air-conditioning controller 400 (for example, an air-conditioning remote controller) via the air-conditioning control device 206, and supplies it to the control unit 112c. The air-conditioning request is, for example, information indicating an operation mode of the air-conditioning apparatus, such as a cooling request and a heating request. The air-conditioning request may include information indicating a target temperature in the operation mode. The communication unit 112b inputs the hot water supply request output from the hot water supply controller 500 and supplies it to the control unit 112c. Alternatively, the hot water supply request output from the hot water supply controller 500 (remote controller for hot water supply) is communicated via the hot water supply control device 308 and supplied to the control unit 112c. The control unit 112c controls the compressor 102, the four-way valve 104, the pressure reducing mechanisms 130a, 130b, and 130c, and the heat source side blower 108 based on the measured temperatures and pressures, the air-conditioning request, and the hot water supply request. The storage unit 112d includes a semiconductor memory and the like. The storage unit 112d stores, for example, a refrigerant temperature of each part in the air-conditioning apparatus, a refrigerant pressure of each part in the air-conditioning apparatus, air temperatures such as an indoor temperature and an outside air temperature, an operation state amount such as a water temperature, set values such as a target temperature, and various information in the heat source unit 100.

The air-conditioning control device 206 is, for example, a computer realized by a CPU executing a program. The air-conditioning control device 206 controls the air-conditioning unit 200 based on an air-conditioning request output from the air-conditioning controller 400. The air-conditioning control device 206 includes, for example, a measurement unit 206a, a control unit 206b, and a communication unit 206c. The measurement unit 206a measures various temperatures by inputting signals detected by the temperature sensors 210, 212, and 214 and performing calculations based on the input signals. The communication unit 206c is connected to each part of the air-conditioning unit 200 via communication lines, and transmits and receives various data and information. The communication unit 206c receives an input of an air-conditioning request output from the air-conditioning controller 400. The control unit 206b controls the blower 204 based on the measured temperature and the air-conditioning request.

The hot water supply control device 308 is, for example, a computer realized by a CPU executing a program. The hot water supply control device 308 controls the hot water supply unit 300 based on the hot water supply request output from the hot water supply controller 500. The hot water supply control device 308 includes, for example, a measurement unit 308a, a control unit 308b, and a communication unit 308c. The measurement unit 308a measures various temperatures by inputting signals detected by the temperature sensors 310 and 312 and performing calculations based on the input signals. The communication unit 308c is connected to each part of the hot water supply unit 300 via communication lines, and transmits and receives various data and information. The communication unit 308c receives an input of a hot water supply request output from the hot water supply controller 500. The control unit 308b controls the electric heater 306 based on the measured temperature and the hot water supply request. Specifically, the control unit 308b outputs a hot water supply request when detecting that a water temperature in the hot water storage tank 304 has decreased, based on information output from the hot water supply controller 500. For example, when a hot water supply setting temperature is set to 55° C. and a water temperature based on a detection signal of the temperature sensor 310 is 45° C. or less, resulting in a water temperature that is 10° C. lower than the hot water supply setting temperature, the control unit 308b outputs the hot water supply request.

The air-conditioning controller 400 is, for example, a remote controller for air conditioning, but is not limited thereto, and may be a tablet, a personal computer, or a smartphone in which application software is installed. The air-conditioning controller 400 includes, for example, an input unit 410, a communication unit 420, and a display unit 430. The input unit 410 is an operation interface that receives a user's operation. The display unit 430 displays various information on air conditioning, such as input results based on operations and the state of the air-conditioning unit 200. The communication unit 420 transmits information based on the operation received by the input unit 410 to the air-conditioning control device 206 and the heat source control device 112.

The hot water supply controller 500 is, for example, a remote controller for hot water supply, but is not limited thereto, and may be a tablet, a personal computer, or a smartphone in which application software is installed. The hot water supply controller 500 includes, for example, an input unit 510, a communication unit 520, and a display unit 530. The input unit 510 is an operation interface that receives a user's operation. The display unit 530 displays various information on hot water supply, such as input results based on operations and the state of the hot water supply unit 300. The communication unit 520 transmits information based on an operation received by the input unit 510 to the hot water supply control device 308 and the heat source control device 112.

The air-conditioning apparatus supplies a cooling request or a heating request selected by the air-conditioning units 200A and 200B to the heat source control device 112, and supplies a hot water supply request of the hot water supply unit 300 to the heat source control device 112. Thereby, the air-conditioning apparatus controls each part of the heat source unit 100, the air-conditioning unit 200, and the hot water supply unit 300 by the heat source control device 112.

Hereinafter, an operation mode of the air-conditioning apparatus described above will be described.

The air-conditioning apparatus in the embodiment performs a hot water supply operation mode according to a hot water supply request set by the hot water supply controller 500, a cooling operation mode according to a cooling request set by the air-conditioning controller 400, and a heating operation mode according to a heating request set by the air-conditioning controller 400. An operation of the air-conditioning apparatus in each operation mode and a flow state of a refrigerant will be described below. When a hot water supply request and a cooling request are given at the same time, an alternate operation of alternately repeating a cooling operation and a hot water supply operation is performed, and the cooling operation is continued when there is no longer the hot water supply request. When a hot water supply request and a heating request are given at the same time, an alternate operation of alternately repeating a heating operation and a hot water supply operation is performed, and the heating operation is continued when there is no longer the hot water supply request. In principle, an air-conditioning apparatus performs a hot water supply operation with priority over a cooling operation and a heating operation. The reason why the hot water supply operation is performed with priority is to avoid the occurrence of a hot water shortage condition in which the hot water storage tank 304 runs out of hot water.

First, a hot water supply operation will be described. During the hot water supply operation, the heat source control device 112 connects the discharge side of the compressor 102 and the refrigerant pipe 1 by controlling the four-way valve 104, and connects a suction side of the compressor 102 and a gas side of the heat source side heat exchanger 106. Furthermore, the heat source control device 112 performs control so that the pressure reducing mechanisms 130a and 130b are set to be in a closed state (closed circuit). A high-temperature and high-pressure gas refrigerant discharged from the compressor 102 flows into the heat exchanger 302 after passing through the refrigerant pipe 1c via the four-way valve 104. Thereby, a gas medium heats the water in the hot water storage tank 304 via a wall surface of the hot water storage tank 304. Thereafter, the refrigerant flows out of the heat exchanger 302, is depressurized by the pressure reducing mechanism 130c via the refrigerant pipe 2c, and flows into the heat source side heat exchanger 106. Thereby, the refrigerant becomes a low-pressure gas refrigerant by exchanging heat with the air (also referred to as heat source air) supplied by the heat source side blower 108. The low-pressure gas refrigerant flowing out of the heat source side heat exchanger 106 passes through the accumulator 110 via the four-way valve 104, and then is suctioned into the compressor 102 again. In the hot water supply operation, heat may be exchanged between the refrigerant and a water circuit (not shown), and heat may be exchanged between the water circuit and the water in the hot water storage tank 304.

In the hot water supply operation, the heat source control device 112 performs control so that the operating frequency of the compressor 102 becomes the maximum frequency. Further, the heat source control device 112 performs control so that the rotation speed of the heat source side blower 108 is fixed at a set value. Further, the heat source control device 112 controls the opening degree of the pressure reducing mechanism 130c so that the discharge temperature of the pressure reducing mechanism 130c becomes a set value. The set value of the discharge temperature is, for example, a saturation temperature of the temperature sensor 122 provided on the discharge side of the compressor 102.

Next, a cooling operation will be described. The heat source control device 112 controls the four-way valve 104 to connect the discharge side of the compressor 102 and the gas side of the heat source side heat exchanger 106 and connect the suction side of the compressor 102 and a downstream side of the accumulator 110.

A high-temperature and high-pressure gas refrigerant discharged from the compressor 102 flows into the heat source side heat exchanger 106 via the four-way valve 104, and radiates heat to the heat source air blown by the heat source side blower 108, thereby converting the refrigerant to a high-pressure liquid refrigerant. Thereafter, the high-pressure liquid refrigerant flows out of the heat source side heat exchanger 106, and is decompressed by the pressure reducing mechanisms 130a and 130b to become a low-pressure two-phase refrigerant. The low-pressure two-phase refrigerant flows out of the heat source unit 100 and flows into the air-conditioning units 200A and 200B via the refrigerant pipes 7a and 7b. Thereafter, the low-pressure two-phase refrigerant is cooled by indoor air in the respective heat exchangers 202 and becomes a low-pressure gas refrigerant. The low-pressure gas refrigerant flows out of the air-conditioning units 200A and 200B, flows into the heat source unit 100 via the refrigerant pipes 1a and 1b, flows into the accumulator 110, and is suctioned into the compressor 102 again.

In the cooling operation, the heat source control device 112 controls the opening degree of the pressure reducing mechanisms 130a and 130b so that a discharge temperature becomes a set value. Furthermore, the heat source control device 112 controls the operating frequency of the compressor 102 so that an evaporation temperature becomes a set value. The evaporation temperature is the minimum temperature out of a temperature detected by the temperature sensor 210 and a temperature detected by the temperature sensor 212. The heat source control device 112 controls the heat source side blower 108 so that a condensation temperature becomes a set value. The condensation temperature is, for example, a temperature detected by the temperature sensor 126.

Next, an operation state of the heating operation will be described. The heat source control device 112 controls the four-way valve 104 to connect the discharge side of the compressor 102 and the refrigerant pipe 1 and connect the suction side of the compressor 102 and the gas side of the heat source side heat exchanger 106.

The high-temperature and high-pressure gas refrigerant discharged from the compressor 102 passes through the refrigerant pipes 1a and 1b via the four-way valve 104, and then flows into the heat exchanger 202 to heat indoor air and becomes a high-pressure liquid refrigerant. The high-pressure liquid medium flows out of the air-conditioning units 200A and 200B, is decompressed by the pressure reducing mechanisms 130a and 130b, and flows into the heat source side heat exchanger 106. The high-pressure liquid medium exchanges heat with the heat source air supplied by the heat source side blower 108 and becomes a low-pressure gas refrigerant. The low-pressure gas refrigerant flowing out of the heat source side heat exchanger 106 then passes through the accumulator 110 via the four-way valve 104, and then is suctioned into the compressor 102 again.

In a heating operation, the heat source control device 112 controls the opening degrees of the pressure reducing mechanisms 130a and 130b so that a discharge temperature becomes a set value, and performs control so that the pressure reducing mechanism 130c is set to be in a closed state (closed circuit). Further, the heat source control device 112 controls the operating frequency of the compressor 102 so that a condensation temperature becomes a set value. The condensation temperature is obtained as the maximum temperature out of a temperature detected by the temperature sensor 210 and a temperature detected by the temperature sensor 212.

Next, a boiling operation using the electric heater 306 will be described. The electric heater 306 is installed to be submerged inward from the inner wall surface of the hot water storage tank 304. The hot water supply unit 300 heats water in the hot water storage tank 304 by electrifying the electric heater 306. For this reason, the air-conditioning apparatus can boil water by electrifying the electric heater 306 even when the heat source unit 100 is not performing a hot water supply operation.

For example, when the hot water supply controller 500 sets such a hot water temperature that it is difficult to complete boiling in the hot water supply operation by the heat source unit 100, the air-conditioning apparatus starts a boiling operation using the electric heater 306 when a water temperature rises to a set value during the hot water supply operation of the heat source unit 100. The set value for starting the boiling operation by the electric heater 306 is stored in the storage unit 112d. During the boiling operation using the electric heater 306, a hot water supply request given from the hot water supply control device 308 to the heat source control device 112 remains outputted. When no air-conditioning request is output to the heat source control device 112 during the boiling operation using the electric heater 306, the heat source unit 100 is stopped. On the other hand, when an air-conditioning request is being output from either one of the air-conditioning units 200A and 200B to the heat source control device 112, the heat source control device 112 restarts an air-conditioning operation by the heat source unit 100 even when the hot water supply request remains outputted. Thereby, the air-conditioning apparatus can restart an air-conditioning operation at an early stage, and thus it is possible to prevent indoor comfort from being impaired.

The set value (threshold value) for starting heating by the electric heater 306 during the hot water supply operation is set to, for example, 55° C. This is because, when R32 or R410A is used as a refrigerant gas, a refrigerant pressure becomes close to 4.0 MPaG and becomes close to a maximum allowable refrigerant pressure of the heat source unit 100 when a boiling temperature reaches 55° C.

FIG. 3 is a flowchart showing an example of a specific operation procedure by the air-conditioning apparatus according to the embodiment. The air-conditioning apparatus performs a heating operation based on a heating request output from the air-conditioning controller 400 (step S10). During the heating operation, a water temperature in the hot water storage tank 304 decreases, and a hot water supply request is output from the hot water supply control device 308 to the heat source control device 112 (step S12). A set value of a hot water supply temperature (also referred to as a set hot water supply temperature) corresponding to the hot water supply request is, for example, 60° C. In response to the reception of the hot water supply request, the heat source control device 112 interrupts the heating operation and starts a hot water supply operation by the heat source unit 100 (step S14).

The heat source control device 112 determines whether a hot water supply request time of the heat source unit 100 is equal to or less than a maximum hot water supply continuous time (first continuous operation time) when the heating request is given (step S16). The maximum hot water supply continuous time when the heating request is given is also described as a threshold value T_max (H). When the hot water supply operation time of the heat source unit 100 is equal to or less than the threshold value T_max (H) (step S16: YES), the heat source control device 112 determines whether a water temperature in the hot water storage tank 304 is equal to or less than a threshold temperature (for example, 55° C.) (step S18). The threshold temperature of the water temperature is, for example, 55° C., which is lower than a set hot water supply temperature of 60° C. A difference between the threshold temperature and the set hot water supply temperature is a temperature range to be increased by heating of the electric heater 306, and may be any range. When the water temperature in the hot water storage tank 304 is a threshold value (step S18: YES), the heat source control device 112 returns the processing to step S16. When the water temperature in the hot water storage tank 304 is not the threshold value (step S18: NO), the heat source control device 112 starts heating (boiling operation) by the electric heater 306, and starts (permits) a heating operation by the heat source unit 100 (step S24). The heat source control device 112 stops the electric heater 306 and continues the heating operation when there is no longer a hot water supply request during the boiling operation (step S26).

In this manner, the heat source control device 112 ends the hot water supply operation of the heat source unit 100 and starts boiling by the electric heater 306 when the water temperature increases due to the hot water supply operation and reaches the threshold temperature. Thereby, the heat source control device 112 can restart a heating operation by the heat source unit 100. Thereafter, when the water temperature in the hot water storage tank 304 reaches a set hot water supply temperature and there is no longer a hot water supply request, the air-conditioning apparatus ends boiling by the electric heater 306 and continues the heating operation.

According to the air-conditioning apparatus, a hot water supply request is prioritized over an air-conditioning request, and thus an air-conditioning operation cannot be performed during a period when a hot water request is being output, but an air-conditioning operation can be restarted before the water temperature reaches 60° C. As a result, according to the air-conditioning apparatus, it is possible to suppress a decrease in indoor comfort.

When a requested hot water supply time of the heat source unit 100 is not equal to or less than the threshold value T_max (H) (step S16: NO), the heat source control device 112 interrupts the hot water supply operation by the heat source unit 100 and restarts a heating operation (step S20). Thereafter, the heat source control device 112 determines whether a heating operation time of the heat source unit 100 is equal to or less than a maximum air-conditioning continuous time (step S22). When the heating operation time is less than or equal to the maximum air-conditioning continuous time when a hot water supply request is given (step S22: YES), the heat source control device 112 maintains the interruption of the hot water supply operation and the continuation of the heating operation by the heat source unit 100. When the heating operation time is not equal to or less than the maximum air-conditioning continuous time when the hot water supply request is given (step S22: NO), the heat source control device 112 interrupts the heating operation and restarts the hot water supply operation (step S14).

In step S18, it is determined whether to start a boiling operation using the electric heater 306 based on the water temperature in the hot water storage tank 304, but the present disclosure is not limited thereto. The air-conditioning apparatus may determine whether to switch from the hot water supply operation of the heat source unit 100 to the boiling operation using the electric heater 306 when the condensation temperature during the hot water supply operation becomes equal to or higher than a set value. The set value of the condensation temperature during the hot water supply operation is, for example, 58° C. The condensation temperature during the hot water supply operation is a saturation temperature at the pressure detected by the pressure sensor 120 (high pressure sensor) during the hot water supply operation. When an outside air temperature is low, the pressure of a refrigerant suctioned into the compressor 102 decreases, and the lower the outside air temperature is, the lower the condensation temperature becomes, regardless of the water temperature in the hot water storage tank 304. For this reason, the heat source unit 100 can continue the hot water supply operation for a longer time by determining whether to switch from the hot water supply operation of the heat source unit 100 to the boiling operation using the electric heater 306 based on whether the condensation temperature during the hot water supply operation has exceeded the set value. As a result, according to the air-conditioning apparatus, it is possible to reduce the amount of power consumed for boiling water.

When the boiling operation using the electric heater 306 is started based on the fact that the condensation temperature during the hot water supply operation becomes equal to or higher than the set value in step S18, the heating capacity for water in the hot water storage tank 304 decreases when the rotation frequency of the compressor 102 is lowered, and thus the condensation temperature during the hot water supply operation is lowered. When the condensation temperature during the hot water supply operation is lowered, a hot water supply operation period becomes longer, and indoor temperature may change, leading to a decrease in comfort. The lowest value of the rotation frequency of the compressor 102 during the hot water supply operation is made larger than the lowest value of the rotation frequency during an air-conditioning operation. Thereby, the air-conditioning apparatus can prevent a period until the condensation temperature reaches the set value during the hot water supply operation from becoming longer, thereby suppressing a decrease in indoor comfort.

The air-conditioning apparatus suppresses a decrease in indoor comfort by restarting an air-conditioning operation at the same time as the electric heater 306 starts a boiling operation, but when the water temperature in the hot water storage tank 304 is low and the hot water supply operation period of the heat source unit 100 becomes longer, indoor comfort may be decreased. To avoid this, the air-conditioning apparatus interrupts the hot water supply operation of the heat source unit 100 and restarts the heating operation when the hot water supply operation period of the heat source unit 100 reaches a hot water supply continuous operation time when a heating request is given (steps S18 and S20). Thereafter, when the heating operation period reaches the maximum air-conditioning continuous time when a hot water supply request is given, the air-conditioning apparatus interrupts the heating operation again and restarts the hot water supply operation of the heat source unit 100. In this manner, the air-conditioning apparatus can suppress a decrease in indoor comfort by alternately repeating the heating operation and the hot water supply operation. However, when a load of the heating operation is high, the rate of change in indoor temperature during the interruption of the heating operation is high, and thus the air-conditioning apparatus can restart the heating operation when the electric heater 306 starts the boiling operation. Thereby, according to the air-conditioning apparatus, even when the load of the air-conditioning operation is high, it is possible to further suppress a decrease in indoor comfort.

FIG. 4 is a diagram showing an operation of the air-conditioning apparatus according to the embodiment, in which (a) is a diagram showing changes over time in an operation mode of the heat source unit 100, and (b) is a diagram showing changes over time in water temperature in the hot water storage tank 304, and (c) is a diagram showing changes over time in an operation of the electric heater 306. The operation of the air-conditioning apparatus will be described together with the processing in FIG. 3 described above.

The air-conditioning apparatus suppresses a decrease in indoor comfort by permitting (restarting) a heating operation after starting a boiling operation of the electric heater 306 (step S24). However, when the rate of increase in the water temperature in the electric heater 306 is slow, it takes time to restart a hot water supply operation, resulting in a decrease in indoor comfort. On the other hand, the air-conditioning apparatus starts a hot water supply operation when a hot water supply request is output (t1) while a heating operation is performed in response to the hot water supply request, and the air-conditioning apparatus continues the hot water supply operation until a threshold value T_max (H) is reached when the water temperature in the hot water storage tank 304 is 55° C. or lower (steps S16 and S18). When the hot water supply operation time reaches the threshold value T_max (H) (t2), the hot water supply operation is interrupted and a heating operation is restarted (step S20). Thereafter, when a heating operation time does not reach the threshold value THmax, the heating operation is continued (step S22). When the heating operation time reaches the threshold value THmax (t3), the heating operation is interrupted and the hot water supply operation is restarted (step S14). By repeating such operations, the air-conditioning apparatus can alternately perform the heating operation and the hot water supply operation.

In the operation of alternately performing the heating operation and the hot water supply operation, when the water temperature in the hot water storage tank 304 reaches 55° C. (t4, step S18), the electric heater 306 is switched to a turn-on state to start a boiling operation and restart the heating operation (step S24). When the electric heater 306 is turned on, the water temperature in the hot water storage tank 304 continues to rise, and when the water temperature reaches 60° C. which is a set hot water supply temperature (t5), there is no longer the hot water supply request and the heating of the electric heater 306 ends (step S26). Thereafter, the air-conditioning apparatus continues to perform the heating operation until there is no longer the hot water supply request.

As described above, according to the air-conditioning apparatus, a water temperature does not reach a set hot water supply temperature even when a heating operation and a hot water supply operation are performed alternately, and a heating operation can be restarted by performing heating by the electric heater 306 even when a hot water supply operation time becomes longer. As a result, the air-conditioning apparatus can achieve both suppression of a decrease in the amount of hot water in the hot water storage tank 304 and suppression of a decrease in indoor comfort.

On the other hand, the air-conditioning apparatus prohibits heating of by the electric heater 306 when a heating operation is performed in the alternate operation of alternately performing the heating operation and the hot water supply operation (step S20). The air-conditioning apparatus prohibits heating of the electric heater 306 when a cooling operation is performed in the alternate operation of alternately performing the cooling operation and the hot water supply operation (step S20). Thereby, the air-conditioning apparatus can perform boiling with power consumption that is lower than that in the heating of the electric heater 306, and can improve energy saving performance. As a result, according to the air-conditioning apparatus, it is possible to achieve all of suppression of a decrease in the amount of hot water in the hot water storage tank 304, suppression of a decrease in indoor comfort, and improvement in energy-saving performance.

In the above-described embodiment, the heating operation and the hot water supply operation are alternately performed (first alternate operation), but a “heating request” may be read as a “cooling request”, a “heating operation” may be read as a “cooling operation”, an “alternate operation of alternately performing a heating operation and a hot water supply operation” may be read as an “alternate operation of alternately performing a cooling operation and a hot water supply operation (second alternate operation)”, and a “maximum hot water supply continuous time when a heating request is given (threshold value T_max (H))” may be read as a “maximum hot water supply continuous time when a cooling request is given (threshold value T_max (C), second continuous operation time)”. Thereby, the air-conditioning apparatus can achieve both suppression of a decrease in the amount of hot water in the hot water storage tank 304 and suppression of a decrease in indoor comfort even when a colling request and a hot water supply request are given at the same time.

A continuous operation time of a hot water supply operation in an alternate operation will be described below.

In the air-conditioning apparatus, whether the load of a heating operation in winter or the load of a cooling operation in summer is higher depends on the installation environment of the air-conditioning apparatus. For example, in summer when sunlight enters a room well and an average temperature of the outside air is high, the rate of rise in room temperature increases during an interruption period of a cooling operation in an alternate operation. On the other hand, when an average outside air temperature is low in winter, the rate of decrease in room temperature increases during an interruption period of a heating operation in the alternate operation.

For this reason, the air-conditioning apparatus performs control so that the threshold value T_max (H) in the alternate operation of alternately performing a heating operation and a hot water supply operation (step S14 to step S22) is different from the threshold value T_max (C) in the alternate operation of alternately performing a cooling operation and a hot water supply operation (step S14 to step S22). For example, the air-conditioning apparatus sets the threshold value T_max (H) and the threshold value T_max (C) to different times based on the installation environment of the air-conditioning apparatus, and stores them in the storage unit 112d. When the air-conditioning apparatus is performing a heating operation, the air-conditioning apparatus reads information on the threshold value T_max (H) from the storage unit 112d in step S16 in FIG. 3, and limits a continuous operation time of a hot water supply operation. When the air-conditioning apparatus is performing a cooling operation, the air-conditioning apparatus reads information on the threshold value T_max (C) from the storage unit 112d in step S16 in FIG. 3, and limits a continuous operation time of a hot water supply operation. Thereby, the air-conditioning apparatus can separately adjust maximum hot water supply continuous times for the heating operation and the cooling operation in the alternate operation based on the installation environment of the air-conditioning apparatus. As a result, the air-conditioning apparatus can secure indoor comfort both in summer and winter.

Assuming that the installation environment in winter (heating season) is, for example, an indoor temperature of 20° C. and an outside air temperature of 7° C., a temperature difference between the indoor temperature and the outside air temperature is 13° C. Assuming that the installation environment in summer (cooling season) is, for example, an indoor temperature of 27° C. and an outside air temperature of 35° C., a temperature difference between the indoor temperature and the outside air temperature is 8° C. In this manner, a temperature difference between the inside and the outside is higher in winter than in summer, and thus an air-conditioning load is higher in the heating operation than in the cooling operation. For this reason, the air-conditioning apparatus sets the threshold value T_max (H) to be smaller than the threshold value T_max (C). Thereby, the air-conditioning apparatus can reduce indoor comfort during a heating season when there is a large difference in temperature between the inside and the outside.

FIG. 5 is a diagram showing an example of a relationship between an outside air temperature and a threshold value T_max (H) in the embodiment. The air-conditioning apparatus may change the threshold value T_max (H) based on an outside air temperature. The air-conditioning apparatus sets the threshold value T_max (H) to be smaller as the outside air temperature decreases. This is because the lower the outside air temperature, the higher a heating load, and the greater the possibility that the room temperature will drop during a hot water supply operation.

FIG. 6 is a diagram showing an example of a relationship between an outside air temperature and a threshold value T_max (C) in the embodiment. The air-conditioning apparatus may change the threshold value T_max (C) based on the outside air temperature. The air-conditioning apparatus sets the threshold value T_max (C) to be smaller as the outside air temperature increases. This is because the higher the outside air temperature, the higher a cooling load, and the greater the possibility that the room temperature will rise during a hot water supply operation.

The air-conditioning apparatus stores the relationship between the outside air temperature and the threshold value T_max (H) shown in FIG. 5 and the relationship between the outside air temperature and the threshold value T_max (C) shown in FIG. 6 in the storage unit 112d. Thereby, the air-conditioning apparatus can limit a hot water supply operation time in an alternate operation to a value corresponding to a detected value of the outside air temperature. The threshold value T_max (H) and the threshold value T_max (C) for the outside air temperature are stored in the storage unit 112d of the heat source control device 112, and the threshold value T_max (H) and the threshold value T_max (C) can be determined with respect to the detected value of the outside air temperature. The air-conditioning apparatus may change both of the threshold value T_max (H) and the threshold value T_max (C) based on the outside air temperature, or may change at least one of the threshold values T_max (H) and T_max (C).

Specifically, the air-conditioning apparatus may store relationships of the following equations and coefficients a, b, c, and d. The coefficients a and b are set based on a change in T_max (H) with respect to the outside air temperature as shown in FIG. 5. The coefficients c and d are set based on a change in T_max (C) with respect to the outside air temperature as shown in FIG. 6.

$T_{\max }\left(H\right)=b+a\times \mathrm{outside}\mathrm{air}\mathrm{temperature}$ $T_{\max }\left(C\right)=d-c\times \mathrm{outside}\mathrm{air}\mathrm{temperature}$

The air-conditioning apparatus can set an appropriate hot water supply operation time according to changes in air-conditioning load by changing the threshold value T_max (H) and the threshold value T_max (C) based on the outside air temperature.

In step S22, when the indoor temperature reaches the set temperature during the alternate operation, the air-conditioning apparatus may restart the hot water supply operation even when the heating operation time does not reach the maximum air-conditioning continuous time. Thereby, according to the air-conditioning apparatus, it is possible to restart the hot water supply operation at an early stage without waiting for the maximum air-conditioning continuous time to be reached. As a result, according to the air-conditioning apparatus, it is possible to suppress a decrease in the amount of hot water in the hot water storage tank 304.

In step S18, the air-conditioning apparatus determines a heating start timing of the electric heater 306 based on a water temperature in the hot water storage tank, but instead of this, the air-conditioning apparatus may determine the heating start timing of the electric heater 306 based on a hot water supply condensation temperature. The hot water supply condensation temperature is a saturation temperature of pressure detected by the pressure sensor 120 (high pressure sensor) during a hot water supply operation. When the water temperature in the hot water storage tank 304 increases during the hot water supply operation, the hot water supply condensation temperature also increases. The air-conditioning apparatus starts heating by the electric heater 306 when the hot water supply condensation temperature becomes equal to or higher than the condensation temperature (threshold value, for example, 60° C.) at which the electric heater 306 starts heating. Since an upper limit is set for an operating pressure in the heat source unit 100, the air-conditioning apparatus can continue the hot water supply operation to the extent that the heat source unit 100 can operate by determining whether to start heating of the electric heater 306 using the hot water supply condensation temperature. Thereby, the air-conditioning apparatus can further suppress power consumption during the hot water supply operation.

Furthermore, in the air-conditioning apparatus, the minimum frequency of the compressor 102 during the hot water supply operation after step S14 is set to be higher than the minimum frequency of the compressor 102 during the air-conditioning operation after step S10. In the air-conditioning apparatus, the minimum frequency of the compressor 102 during the hot water supply operation may be set to be higher than the minimum frequency of the compressor 102 during at least one of the cooling operation and the heating operation. The operating frequency of the compressor 102 increases as an air-conditioning load increases. On the other hand, the air-conditioning apparatus sets the minimum frequency at which the compressor 102 operates to be higher during the hot water supply operation than during the air-conditioning operation, for example, even when the outside air temperature is the same during the heating operation and the cooling operation.

When the operating frequency of the compressor 102 is lowered during the hot water supply operation, the heating capacity for boiling will be reduced and it will take a long time to complete hot water supply. On the other hand, it is necessary to be able to reduce the minimum frequency so that the operating frequency of the compressor 102 is suppressed when a load during the air-conditioning operation is low. According to the air-conditioning apparatus, the minimum frequency of the compressor 102 during the hot water supply operation is set to be high, and thus it is possible to prevent the heating capacity from becoming extremely low. Further, according to the air-conditioning apparatus, it is possible to start heating by the electric heater 306 at an early stage by raising a hot water supply condensation temperature a little early. Thereby, according to the air-conditioning apparatus, it is possible to suppress a decrease in the amount of hot water in the hot water storage tank 304.

As described above, according to the air-conditioning apparatus, it is possible to provide a hot water supply air-conditioning system that achieves both air-conditioning performance and hot water supply performance and has high user satisfaction, even when there are seasonal changes in installation environment.

Although the embodiment of the present disclosure has been described above in detail with reference to the drawings, the specific configuration is not limited to the above-described embodiment, and designs and the like within the scope of the gist of the present disclosure are also included.

Claims

1. An air-conditioning apparatus comprising:

a heat source device that includes a refrigerant cycle circulating a refrigerant;

an air-conditioning unit configured to perform a heating operation and a cooling operation by exchanging heat between the refrigerant and indoor air;

a hot water supply unit that includes a hot water storage tank and configured to perform a hot water supply operation by heating with the refrigerant; and

control circuitry configured to perform a first alternate operation of alternately performing the heating operation and the hot water supply operation when a heating request and a hot water supply request are received at the same time, and to perform a second alternate operation of alternately performing the cooling operation and the hot water supply operation when a cooling request and the hot water supply request are received at the same time, wherein

the control circuitry is configured to perform control to make a first continuous operation time of the hot water supply operation in the first alternate operation different from a second continuous operation time of the hot water supply operation in the second alternate operation.

2. The air-conditioning apparatus according to claim 1, wherein the control circuitry is configured to set the first continuous operation time to be shorter than the second continuous operation time.

3. The air-conditioning apparatus according to claim 1, wherein the control circuitry is configured to change at least one of the first continuous operation time and the second continuous operation time based on an outside air temperature.

4. The air-conditioning apparatus according to claim 1, wherein

the hot water supply unit includes a heating unit, and

the control circuitry is configured to cause the heating unit to start heating and start the heating operation in the first alternate operation, and to cause the heating unit to start heating and start the cooling operation in the second alternate operation.

5. The air-conditioning apparatus according to claim 4, wherein the control circuitry is configured to cause the heating unit to start heating when a water temperature in the hot water storage tank reaches a threshold value.

6. The air-conditioning apparatus according to claim 4, wherein the control circuitry is configured to cause the heating unit to start heating when a condensation temperature of the refrigerant during the hot water supply operation reaches a threshold value.

7. The air-conditioning apparatus according to claim 5, wherein the control circuitry is configured to prohibit the heating unit from starting heating when the heating operation is performed in the first alternate operation or when the cooling operation is performed in the second alternate operation.

8. The air-conditioning apparatus according to claim 7, wherein the control circuitry is configured to permit the heating unit to perform heating when the heating operation is performed in the first alternate operation or the cooling operation is performed in the second alternate operation, and an indoor temperature reaches a target temperature.

9. The air-conditioning apparatus according to claim 1, wherein

the heat source device includes a compressor,

a minimum frequency of the compressor in the hot water supply operation is greater than a minimum frequency of the compressor in the heating operation, and the minimum frequency of the compressor in the hot water supply operation is greater than a minimum frequency of the compressor in the cooling operation.

10. An air-conditioning method in an air-conditioning apparatus including a heat source device that includes a refrigerant cycle circulating a refrigerant, an air-conditioning unit configured to perform a heating operation and a cooling operation by exchanging heat between the refrigerant and indoor air, and a hot water supply unit that includes a hot water storage tank and configured to perform a hot water supply operation by heating with the refrigerant, the air-conditioning method comprising:

performing a first alternate operation of alternately performing the heating operation and the hot water supply operation when a heating request and a hot water supply request are received at the same time; and

performing a second alternate operation of alternately performing the cooling operation and the hot water supply operation when a cooling request and the hot water supply request are received at the same time, wherein

a first continuous operation time of the hot water supply operation in the first alternate operation is different from a second continuous operation time of the hot water supply operation in the second alternate operation.