Heat pump system

Abstract

A heat pump system according to the present disclosure comprises: a refrigeration cycle device; an electricity meter that measures the power consumption of the refrigeration cycle device; a performance detector that detects the performance of the refrigeration cycle device; and a control circuit configured to carry out COP guard control to lower the operating capacity of the refrigeration cycle device such that an actual COP calculated from the power consumption and the performance of the refrigeration cycle device does not fall to or below a COP guard value. The heat pump system carries out the COP guard control during water heating operation, which is operation to heat water by means of the refrigeration cycle device.

Description

heat pump system

[0001] The present disclosure relates to heat pump systems.

[0002] The following Patent Document 1 discloses a heat pump water heater that uses a heat pump cycle to heat a liquid for hot water supply and stores the heated liquid in a hot water storage tank, and that is characterized by having a priority control means as a control means for the heat pump cycle that switches between targeting heating capacity and targeting operating efficiency.

[0003] Japanese Patent Application Publication No. 2005-127588

[0004] In the above-mentioned conventional device, when priority is given to operational efficiency, the compressor frequency is always low from the start of hot water supply operation, and the heating capacity is reduced, increasing the possibility of running out of hot water.

[0005] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide a heat pump system that is advantageous in achieving both a short time for completing hot water supply operation and a high COP (Coefficient of Performance).

[0006] The heat pump system according to the present disclosure comprises a refrigeration cycle device, a power meter that measures the power consumption of the refrigeration cycle device, a capacity detector that detects the capacity of the refrigeration cycle device, and a control circuit configured to perform COP protection control that reduces the operating capacity of the refrigeration cycle device so that the actual COP calculated from the power consumption and the capacity of the refrigeration cycle device does not fall below the COP protection value.

[0007] According to the present disclosure, it is possible to provide a heat pump system that is advantageous in achieving both a short time for completing hot water supply operation and a high COP.

[0008] 1 is a system circuit diagram showing the flows of refrigerant, heat medium, and water in a hot water supply operation mode of a heat pump system in embodiment 1. FIG. 2 is a block diagram showing the configuration of a heat pump control device. FIG. 3 is a block diagram showing the configuration of a hydro control device. FIG. 4 is a flowchart showing control operations in embodiment 1. FIG. 5 is a graph showing fluctuations in each parameter during hot water supply operation. FIG. 6 is a diagram showing an example of a configuration that realizes the functions of a heat pump control device and a hydro control device in embodiment 1.

[0009] Hereinafter, embodiments will be described with reference to the drawings. Common or corresponding elements in each drawing are designated by the same reference numerals, and their description will be simplified or omitted. In the following description, the terms "water" and "hot water" generally refer to liquid water, and may include anything from cold water to hot water. Furthermore, the configurations shown in the following embodiments are merely examples of the technical ideas of the present disclosure, and may be combined with other known technologies, or multiple technical ideas described in the present disclosure may be combined. Furthermore, parts of the configurations may be omitted or modified without departing from the spirit of the present disclosure.

[0010] Embodiment 1. <Device Configuration> Fig. 1 is a system circuit diagram of a heat pump system 100 according to embodiment 1 of the present disclosure. As shown in Fig. 1, the heat pump system 100 includes a heat pump unit 301 equipped with a refrigerant circuit 51 and a portion of a heating circulation circuit 52 of a vapor compression refrigeration cycle (heat pump cycle), a hot water storage tank unit 302 equipped with a portion of the heating circulation circuit 52 and a hot water storage circuit 53, and heating units 305a and 305b configured with a portion of the heating circulation circuit 52 and configured to heat a room. The heat pump unit 301 and the hot water storage tank unit 302 are connected via heat medium piping 303 and heat medium piping 304. The hot water storage tank unit 302 and the heating units 305a and 305b are connected via heat medium piping 306 and heat medium piping 307. The hot water storage tank unit 302 is connected to a hot water supply pipe 308 connected to a hot water supply terminal (for example, a faucet in a kitchen or bathroom) and a water supply pipe 309 for supplying water from a water source such as a tap. The heat pump system 100 corresponds to a hot water supply and air conditioning system equipped with a hot water supply function and an air conditioning function.

[0011] The refrigerant used in the refrigerant circuit 51 of the heat pump unit 301 is not particularly limited, and for example, natural refrigerants such as R410A, R32, HFO-1234yf, hydrocarbons, or carbon dioxide can be used. The heat medium used in the heating circulation circuit 52 is also not particularly limited, and for example, liquids such as water, ethylene glycol, propylene glycol, Nybrine (Nybrine is a trademark), or mixtures thereof can be used. Ethylene glycol, propylene glycol, Nybrine, or the like can be used in any concentration.

[0012] The heat pump system 100 is installed in, for example, an ordinary house or an office building, etc. The heat pump system 100 can process a hot water supply command (hot water supply ON / OFF) or a heating command (heating ON / OFF) selected by the hot water storage tank unit 302.

[0013] <Heat Pump Unit 301> The heat pump unit 301 is equipped with a refrigerant circuit 51, which includes a compressor 1, a condenser 2, an expansion valve 3, and an evaporator 4, connected in a circular arrangement by refrigerant piping. The compressor 1 draws in and compresses the refrigerant to a high-temperature, high-pressure state. The compressor 1 is preferably a type whose rotational speed is controlled, for example, by inverter control. The condenser 2 heats the heat medium and cools the refrigerant by exchanging heat between the heat medium and the refrigerant. The condenser 2 is, for example, a plate-type heat exchanger. The expansion valve 3 decompresses the refrigerant to a low-temperature, low-pressure state. The opening degree of the expansion valve 3 is variable. The evaporator 4 exchanges heat between the refrigerant and the outside air, absorbing heat from the outside air and heating the refrigerant. The evaporator 4 is, for example, a cross-fin fin-and-tube air heat exchanger composed of a heat transfer tube and multiple fins. A blower 5 is installed in the evaporator 4. The blower 5 draws in outside air, exchanges heat in the evaporator 4, and then discharges the air to the outside. The blower 5 includes a fan such as a propeller fan and a motor, such as a DC fan motor, that drives the fan. The blower 5 is configured to vary the flow rate of the air it supplies. The heat pump unit 301 corresponds to a refrigeration cycle device.

[0014] The heat pump unit 301 further includes a pressure sensor 201 that detects the pressure of the refrigerant discharged from the compressor 1, a temperature sensor 202 that detects the temperature of the refrigerant discharged from the compressor 1, a temperature sensor 203 that detects the temperature of the refrigerant flowing out from the condenser 2, a temperature sensor 204 that detects the temperature of the refrigerant flowing into the evaporator 4, a temperature sensor 205 that detects the temperature of the air flowing into the evaporator 4, i.e., the outside air temperature, a temperature sensor 206 that detects the temperature of the heat medium flowing into the condenser 2, and a temperature sensor 207 that detects the temperature of the heat medium flowing out from the condenser 2.

[0015] <Hot Water Storage Tank Unit 302> The hot water storage tank unit 302 is equipped with a heat medium pump 6, a three-way valve 7, a heating heat exchanger 8, a water pump 9, a hot water storage tank 10, and a mixing valve 11. The heat medium pump 6 circulates the heat medium through the heating circulation circuit 52. The heat medium pump 6 may be a variable-speed pump (e.g., inverter-controlled) or a constant-speed pump. The three-way valve 7 functions as a flow path switching device for switching the flow direction of the heat medium. During hot water supply operation, in which hot water is supplied to the hot water storage tank 10 and heat is stored in the hot water storage tank 10, the three-way valve 7 is switched so that the heat medium flows to the heating heat exchanger 8. During heating operation, the three-way valve 7 is switched so that the heat medium flows to the heating units 305a and 305b. The heating heat exchanger 8 exchanges heat between the heat medium and water to heat the water and cool the heat medium. The heating heat exchanger 8 is, for example, a plate-type heat exchanger. In this embodiment, the heating heat exchanger 8 is configured so that the heat medium and water flow in opposite directions. The water pump 9 circulates water through the hot water storage circuit 53. The water pump 9 may be a variable-speed pump (e.g., inverter-controlled) or a constant-speed pump. The hot water storage tank 10 stores heated hot water and unheated water. The hot water storage tank 10 is a full-capacity tank. One end of the hot water storage circuit 53 is connected to a connection point 14 at the bottom of the hot water storage tank 10. The other end of the hot water storage circuit 53 is connected to a connection point 17 at the bottom of the hot water storage tank 10, which is higher than the connection point 14. When the water pump 9 is driven, water in the hot water storage tank 10 flows out from the connection point 14, is sent to the heating heat exchanger 8, is heated, returns to the hot water storage tank 10, and flows back into the hot water storage tank 10 through the connection point 17.

[0016] The hot water outlet pipe 15 connects the top of the hot water storage tank 10 to the mixing valve 11. The water supply pipe 309 is connected to the bottom of the hot water storage tank 10 and the mixing valve 11. A hot water supply pipe 308 is also connected to the mixing valve 11. In response to a user's hot water supply request, hot water flows out from the top of the hot water storage tank 10 to the hot water outlet pipe 15 and is supplied to the mixing valve 11. At this time, low-temperature water in an amount equal to the hot water flowing out to the hot water outlet pipe 15 flows from the water supply pipe 309 into the bottom of the hot water storage tank 10. The mixing valve 11 mixes the hot water from the hot water outlet pipe 15 with the low-temperature water from the water supply pipe 309 and supplies the water to the hot water supply pipe 308. The mixing valve 11 is capable of controlling the mixing ratio of hot water and low-temperature water, and generates hot water at a preset temperature.

[0017] The hot water storage tank unit 302 further includes a temperature sensor 208 that detects the temperature of the heat medium flowing into the heating heat exchanger 8, a temperature sensor 209 that detects the temperature of the heat medium flowing out of the heating heat exchanger 8, a temperature sensor 210 that detects the temperature of the water flowing into the heating heat exchanger 8, a temperature sensor 211 that detects the temperature of the water flowing out of the heating heat exchanger 8, a temperature sensor 212 that detects the water temperature in the hot water storage tank 10, and a temperature sensor 216 that detects the water temperature in the hot water supply pipe 308.

[0018] <Heating Units 305a, 305b> The heating units 305a, 305b include radiators 12a, 12b (panel heaters) as heating heat exchangers. By circulating a heat medium through the radiators 12a, 12b, the air in the room is heated by radiation.

[0019] In this embodiment, two heating units are used, but one heating unit or three or more heating units may be used. Also, in this embodiment, a radiator is used as the heating heat exchanger, but other types of heating heat exchangers such as a fan coil unit or a floor heater may be used, and a configuration in which multiple types of heating heat exchangers are mixed may also be used.

[0020] <Heat pump control device 101 and hydro control device 121> The heat pump unit 301 is provided with a heat pump control device 101 configured, for example, by a microcomputer. The heat pump control device 101 corresponds to a control circuit. The hot water storage tank unit 302 is provided with a hydro control device 121 configured, for example, by a microcomputer. The hydro control device 121 corresponds to a control circuit. Figure 2 is a block diagram showing the configuration of the heat pump control device 101. The heat pump control device 101 includes a measurement means 102 that acquires pressure or temperature information based on the output of the pressure sensor 201 or temperature sensors 202, 203, 204, 205, 206, and 207; a communication means 103 that transmits the operating status (temperature, pressure, etc.) of the heat pump unit 301 or abnormal signals to the hydro control device 121 and receives the operating status (temperature, equipment operation, etc.) or abnormal signals of the hot water storage tank unit 302 from the hydro control device 121; a calculation means 104 that calculates the condensing temperature or degree of subcooling based on the measurement information acquired by the measurement means 102; and a control means 105 that controls the operating status of the heat pump unit 301 (such as the operating method of the compressor 1 or the opening degree of the expansion valve 3) based on the measurement information or the calculation results of the calculation means 104. The communication means 103 is configured to communicate with a communication means 125 (described later) via, for example, a telephone line, a LAN line, or wireless communication.

[0021] 3 is a block diagram showing the configuration of the hydro control device 121. The hydro control device 121 includes a measuring means 122 that acquires temperature information based on the outputs of the temperature sensors 208, 209, 210, 211, 212, and 216, a storage means 123 that stores the type of heat medium flowing through the heating circulation circuit 52, an input means 124 that recognizes input such as an ON / OFF command for the operation mode from the user or input information from an installation company, and a heat pump control device 101 that transmits the operating status (temperature or equipment operation, etc.) or an abnormal signal of the hot water storage tank unit 302 to the heat pump control device 101, and conversely, transmits the operating status (temperature or equipment operation, etc.) of the hot water storage tank unit 302 to the heat pump control device 101. The heat pump control device 101 has a communication means 125 for receiving the operating status (temperature, pressure, etc.) of the hot water storage tank unit 302 or abnormal signals from the heat pump control device 101, a calculation means 126 for calculating the temperature difference of the water entering and leaving the heating heat exchanger 8 and the temperature difference of the heat medium entering and leaving the heating heat exchanger 8 based on the measurement information acquired by the measurement means 122, and a control means 127 for controlling the operating status of the hot water storage tank unit 302 (the operating status of the heat medium pump 6 and the water pump 9 or switching of the three-way valve 7, etc.) based on the above measurement information or the calculation results of the calculation means 126.

[0022] The hydro control device is further connected to a power meter 141 that measures the power consumption of the heat pump unit 301, which is a refrigeration cycle device, a remote control device 251, and a flow sensor 131. The flow sensor 131 detects the volumetric flow rate of the heat medium flowing through the heating circulation circuit 52.

[0023] The remote control device 251 is an example of a user interface. By operating the remote control device 251, a person such as a user can remotely control the heat pump system 100 and perform various settings. The communication between the hydro control device 121 and the remote control device 251 may be wired or wireless. The remote control device 251 may be installed in the bathroom. The remote control device 251 may be installed in the kitchen. The heat pump system 100 may include multiple remote control devices 251 installed in different locations. The remote control device 251 includes a display unit, an operation unit, and an audio output unit. The display unit may be, for example, a liquid crystal display or an organic EL display. The display unit can display, for example, information regarding the status of the heat pump system 100, information regarding the settings of the heat pump system 100, etc. The display unit functions as a notification means for notifying a person such as a user of information. The operation unit may include buttons, dials, keys, etc. for user operation. The display unit may be a touch screen that also functions as the operation unit. The audio output unit functions as a notification unit that notifies a person such as a user by audio of information. Instead of or in addition to the remote control device 251, a configuration may be adopted in which a smartphone or other portable device can be used as a user interface.

[0024] In the first embodiment, the heat pump control device 101 is installed in the heat pump unit 301, and the hydro control device 121 is installed in the hot water storage tank unit 302. However, the present invention is not limited to this configuration, and the heat pump control device 101 may be installed in the hot water storage tank unit 302, or the hydro control device 121 may be installed in the heat pump unit 301. The heat pump control device 101 and the hydro control device 121 may also be integrated. Alternatively, a control device (not shown) may be provided in a location other than the heat pump unit 301 and the hot water storage tank unit 302, and the control device may take over some or all of the functions of the heat pump control device 101 and the hydro control device 121.

[0025] <Operation Modes> The heat pump system 100 controls the devices installed in the heat pump unit 301, the hot water storage tank unit 302, and the heating units 305a, 305b in accordance with the heating load required of the heating units 305a, 305b and the hot water supply demand required of the hot water storage tank unit 302, and executes a heating operation mode or a hot water supply operation mode. ON / OFF information for the heating operation mode or the hot water supply operation mode is input to the input means 124 of the hydro control device 121 by the user or automatically based on the time, etc. The input information is transmitted to the heat pump control device 101 by the communication means 125. The operation in each operation mode will be described below.

[0026] [Heating Operation Mode] First, the heating operation mode will be described. In the heating operation mode, the three-way valve 7 is switched so as to connect the outlet of the condenser 2 to the heating units 305a and 305b. In this state, the heat pump unit 301 and the hot water storage tank unit 302 are operated. Then, in the refrigerant circuit 51, the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the condenser 2 and is cooled by the heat medium to become a high-pressure liquid refrigerant. The refrigerant then flows out of the condenser 2 and is decompressed by the expansion valve 3 to become a low-pressure two-phase refrigerant. The refrigerant then flows into the evaporator 4, where it absorbs heat from the outside air and becomes a low-pressure gas refrigerant. The refrigerant is then drawn back into the compressor 1. The operating states of the compressor 1, the expansion valve 3, and the blower 5 are controlled by the control means 105 of the heat pump control device 101 in accordance with the temperature or pressure measured by the measurement means 102.

[0027] Meanwhile, in the heating circulation circuit 52, the heat medium sent by the heat medium pump 6 flows out of the hot water storage tank unit 302 and flows into the heat pump unit 301 via the heat medium piping 304. After flowing into the heat pump unit 301, the heat medium is heated by the refrigerant in the condenser 2 and reaches a high temperature. This high-temperature heat medium flows out of the heat pump unit 301 and flows back into the hot water storage tank unit 302 via the heat medium piping 303. The heat medium then flows out of the hot water storage tank unit 302 via the three-way valve 7 and flows into the heating units 305a, 305b via the heat medium piping 306. The heat medium exchanges heat with the indoor air in the radiators 12a, 12b, heating the room, and the heat medium becomes cold. The cold heat medium flows out of the heating units 305a, 305b, flows into the hot water storage tank unit 302 via the heat medium piping 307, and then flows back into the heat medium pump 6. The operating state of the heat medium pump 6 is controlled by the control means 127 of the hydro control device 121 in accordance with the measured temperature or pressure. In the heating operation mode, the water in the hot water storage tank 10 is not heated, so the water pump 9 is stopped and water does not flow in the hot water storage circuit 53.

[0028] [Hot Water Operation Mode] Next, the hot water operation mode will be described. Note that the arrows in FIG. 1 indicate the flow directions of the refrigerant, heat transfer medium, and water in the hot water operation mode. In the hot water operation mode, the three-way valve 7 is switched to connect the outlet of the condenser 2 to the inlet of the heating heat exchanger 8. In this state, the heat pump unit 301 and the hot water storage tank unit 302 are operated. Then, in the refrigerant circuit 51, high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the condenser 2 and is cooled by the heat transfer medium to become high-pressure liquid refrigerant. The refrigerant then flows out of the condenser 2 and is decompressed by the expansion valve 3 to become low-pressure two-phase refrigerant. The refrigerant then flows into the evaporator 4, where it absorbs heat from the outside air and becomes low-pressure gas refrigerant. The refrigerant is then drawn back into the compressor 1. The operating states of the compressor 1, the expansion valve 3, and the blower 5 are controlled by the control means 105 of the heat pump control device 101 in accordance with the temperature or pressure measured by the measurement means 102.

[0029] Meanwhile, in the heating circulation circuit 52, the heat medium sent by the heat medium pump 6 flows out of the hot water storage tank unit 302 and flows into the heat pump unit 301 via the heat medium piping 304. After flowing into the heat pump unit 301, the heat medium is heated by the refrigerant in the condenser 2 and reaches a high temperature. This high-temperature heat medium flows out of the heat pump unit 301 and flows back into the hot water storage tank unit 302 via the heat medium piping 303. The heat medium then flows into the heating heat exchanger 8 via the three-way valve 7, where it exchanges heat with water to heat the water, and the heat medium becomes cold. This cooled heat medium then flows back into the heat medium pump 6.

[0030] Meanwhile, in the hot water storage circuit 53, water flowing out from connection point 14 of the hot water storage tank 10 is sent to the heating heat exchanger 8 by the water pump 9. This water is heated by the heat medium in the heating heat exchanger 8 to become hot water. The hot water flowing out from the heating heat exchanger 8 flows into the hot water storage tank 10 from connection point 17 and is stored there. As water continuously flows out from connection point 14 of the hot water storage tank 10 and hot water continuously flows into connection point 17, the water temperature in the hot water storage tank 10 increases. Note that in the hot water supply operation mode, room heating is not performed, and no heat medium flows through the heating units 305a and 305b.

[0031] As described above, water heated by the heating heat exchanger 8 flows into the hot water storage tank 10 through the connection point 17 at the bottom of the hot water storage tank 10. Low-temperature water exists at the bottom of the hot water storage tank 10. As the water heated by the heating heat exchanger 8 flows into the hot water storage tank 10, the water temperature of the entire hot water storage tank 10 increases. The hot water supply operation in this embodiment is an operation that gradually increases the temperature of the entire hot water storage tank 10, and hot water accumulates in the hot water storage tank 10 through multiple heat exchanges in the heating heat exchanger 8. This heating method is called circulating heating. In circulating heating, the water is heated by, for example, 5°C in the heating heat exchanger 8, thereby increasing the water temperature in the hot water storage tank 10. Therefore, the temperature of the water flowing into the heating heat exchanger 8 increases, for example, to 25°C, 30°C, etc., and the temperature of the water flowing out of the heating heat exchanger 8 also increases accordingly, for example, to 30°C, 35°C, etc. In circulating heating, at the beginning of heating, the water temperature in the hot water storage tank 10 is low, and the temperatures of the heat medium flowing into the heating heat exchanger 8 and the water flowing out of the heating heat exchanger 8 are also low, so the temperatures of the heat medium flowing out of the condenser 2 and the heat medium flowing into the condenser 2 are low. Therefore, the operating efficiency of the heat pump unit 301 is high.

[0032] The water pump 9 is controlled as follows: In order to keep the temperature of the heat medium flowing into the heating heat exchanger 8 low, the water flow rate is increased to lower the temperature of the water flowing out of the heating heat exchanger 8. In other words, the water pump 9 is operated at a constant flow rate such that the temperature difference between the water inlet and outlet of the heating heat exchanger 8 is about 5°C. For example, when the heating capacity of the heating heat exchanger 8 is 9 kW, the specific heat of water is 4.18 kJ / kgK and the density of water is 1000 kg / m ３ In this case, the required flow rate of water is 25.84 liters / minute. Therefore, a pump that can ensure a flow rate of 25.84 liters / minute is selected as the water pump 9.

[0033] In the heat medium pump 6, too, a flow rate of the heat medium equal to or greater than the flow rate of water must be ensured in order to make the temperature difference between the inlet and outlet of the heat medium equal to or less than the temperature difference between the inlet and outlet of the water in the heating heat exchanger 8. In other words, if the flow rate of water delivered by the water pump 9 is 25.84 liters / minute, a pump capable of ensuring a flow rate of 25.84 liters / minute or more must be selected as the heat medium pump 6.

[0034] The high-pressure liquid refrigerant temperature is the temperature of the refrigerant flowing through the refrigerant circuit 51 at the outlet of the condenser 2. In controlling the expansion valve 3 of the heat pump unit 301, a target value for the high-pressure liquid refrigerant temperature is set according to either the temperature of the heat medium flowing into the condenser 2 or the temperature of the heat medium flowing out of the condenser 2, and the expansion valve 3 is controlled so that the high-pressure liquid refrigerant temperature becomes the target value. The target value for the high-pressure liquid refrigerant temperature can be, for example, a value 3°C higher than the temperature of the heat medium flowing into the condenser 2. Furthermore, because the heat medium pump 6 is controlled so that the temperature difference between the inlet and outlet of the heat medium in the heating heat exchanger 8 is about 5°C, the temperature difference between the inlet and outlet of the heat medium in the condenser 2 is also about 5°C. Therefore, because the temperature of the heat medium flowing into the condenser 2 is not so low, the expansion valve 3 may be controlled so that the degree of subcooling of the condenser 2 becomes a target value (for example, 2°C). Here, the degree of subcooling of the condenser 2 is a value obtained by subtracting the temperature detected by the temperature sensor 203 from the saturation temperature of the pressure detected by the pressure sensor 201 .

[0035] By doing as described above, the heat pump system 100 can perform both heating operation and hot water supply operation, and can perform hot water supply operation with high efficiency. Specifically, by using the heating heat exchanger 8 installed outside the hot water storage tank 10, heat transfer performance is improved. Since the temperature of the heat medium flowing into the heat pump unit 301 can be lowered, the heat pump unit 301 can be operated with high operating efficiency. Furthermore, because the heating heat exchanger 8 is installed outside the hot water storage tank 10, it can be easily replaced if a malfunction occurs in the heating heat exchanger 8, improving maintainability.

[0036] In this embodiment, the heating capacity of the heat pump unit 301 corresponds to the capacity of the refrigeration cycle device. The hydro control device 121 can calculate the heating capacity [kW] of the heat pump unit 301 using the following formula based on the outlet water temperature detected by the temperature sensor 208, the inlet water temperature detected by the temperature sensor 209, and the flow rate of the heat medium detected by the flow sensor 131. The specific heat of the heat medium and the density of the heat medium are stored in the storage means 123. Heating capacity = Heat medium flow rate × Heat medium specific heat × Heat medium density × (Outlet water temperature - Inlet water temperature)

[0037] In this embodiment, the temperature sensors 208 and 209 and the flow sensor 131 correspond to a capacity detector that detects the capacity of the refrigeration cycle device.

[0038] In this embodiment, the heat pump control device 101 and the hydro control device 121 are configured to perform COP protection control during hot water supply operation. COP protection control is a control that reduces the operating capacity of the refrigeration cycle device so that the actual COP does not fall below the COP protection value. The COP protection value is stored in the storage means 123. The hydro control device 121 calculates the actual COP using the following formula from the power consumption of the heat pump unit 301 measured by the wattmeter 141 and the heating capacity calculated as described above. Actual COP = Heating capacity [kW] / Power consumption [kW]

[0039] The higher the frequency of the compressor 1, the higher the operating capacity of the refrigeration cycle apparatus. In this embodiment, the operating capacity of the refrigeration cycle apparatus is reduced by lowering the frequency of the compressor 1. This configuration is not limited to this, and in a system provided with multiple compressors, the operating capacity of the refrigeration cycle apparatus may be reduced by reducing the number of operating compressors.

[0040] During hot water supply operation, the temperature of the heat medium flowing into the condenser 2 gradually increases. The higher the temperature of the heat medium flowing into the condenser 2, the lower the heating capacity becomes. Therefore, the COP also gradually decreases.

[0041] The lower the frequency of the compressor 1, the higher the COP. Therefore, by lowering the frequency of the compressor 1, it is possible to prevent the actual COP from falling below the COP protection value. The COP protection value may be 3.0, for example.

[0042] In this embodiment, the heating capacity is maintained at a high level from the beginning to the middle of the hot water supply operation when the temperature of the heat medium flowing into the condenser 2 is not high, and when the temperature of the heat medium flowing into the condenser 2 becomes high, the COP is maintained at a high level, making it possible to achieve energy savings while maintaining the hot water supply operation time long enough to prevent running out of hot water.

[0043] The heating capacity protection value in this embodiment is an example of a refrigeration cycle capacity protection value. The heating capacity protection value is stored in the storage means 123. The heat pump control device 101 may be configured not to further reduce the frequency of the compressor 1 when the heating capacity falls below the heating capacity protection value during COP protection control. This prevents an extreme reduction in heating capacity due to an excessive reduction in the frequency of the compressor 1, making it possible to more reliably avoid running out of hot water. The heating capacity protection value may, for example, be a value equivalent to 50% of the rated capacity.

[0044] Generally, the lower the outdoor temperature, the higher the daily hot water supply load in a house, and the earlier the hot water supply operation needs to be completed. In view of this, the heat pump control device 101 may be configured to increase the heating capacity protection value when the outdoor temperature is low compared to when the outdoor temperature is high. This increases the heating capacity protection value when the outdoor temperature is low, limits the amount of reduction in the compressor frequency, and prevents a significant loss of heating capacity, making it possible to more reliably avoid running out of hot water.

[0045] The user may be able to select ON / OFF of the energy-saving priority mode by operating the remote control device 251. The energy-saving priority mode is a mode in which energy conservation is prioritized compared to the normal mode. The heat pump control device 101 and the hydro control device 121 may be configured to implement COP protection control when the energy-saving priority mode is ON and not implement COP protection control when the energy-saving priority mode is OFF. In other words, when the energy-saving priority mode is OFF, the heat pump control device 101 does not reduce the frequency of the compressor 1 even if the actual COP falls below the COP protection value. As a result, if the user knows in advance that hot water consumption will be high, the user can shorten the hot water supply operation time by turning off the energy-saving priority operation mode, thereby reliably avoiding hot water shortages.

[0046] The heat pump control device 101 may be configured to reduce the rotation speed of the blower 5 when the frequency of the compressor 1 is reduced during COP protection control. This allows the air flow rate output by the blower 5 to be adjusted in accordance with the refrigerant flow rate output by the compressor 1, thereby reducing unnecessary fan blowing power and saving energy.

[0047] The heat pump control device 101 may be configured to reduce the frequency of the compressor 1 when COP protection control is being performed to 65% to 70% of the compressor frequency when COP protection control is not being performed when the outdoor temperature is 7°C or higher. That is, the heat pump control device 101 may be configured not to reduce the frequency of the compressor 1 when COP protection control is being performed to less than 65% of the maximum frequency when the outdoor temperature is 7°C or higher. It is known that the heating load at an outdoor temperature of 7°C is approximately 65% ​​of the catalog capacity as a standard load in warm regions of Europe. Therefore, it can be said that reducing the frequency of the compressor 1 to 65% does not impair heating comfort, and therefore it is preferable to limit the reduction in the compressor frequency to 65% to 70%.

[0048] Fig. 4 is a flowchart showing the control operation in the first embodiment. The following description will be given with reference to the flowchart in Fig. 4. In step S1, the heat pump control device 101 and the hydro control device 121 start hot water supply operation. Here, the compressor frequency is fixed to the hot water supply frequency, and the blower rotation speed is fixed to the hot water supply rotation speed. The hot water supply frequency may be the maximum frequency. The hot water supply rotation speed may be the maximum rotation speed.

[0049] Next, in step S2, the hydro control device 121 measures power consumption using the wattmeter 141, calculates heating capacity, and calculates the actual COP. Next, in step S3, it is determined whether the energy saving priority mode is ON. If the energy saving priority mode is not ON, the process proceeds to step S8. In step S8, the hydro control device 121 determines whether the hot water supply operation has been completed. If the hot water supply operation has not been completed, the process returns to step S2. If the hot water supply operation has been completed, the process proceeds to step S9, where the hot water supply operation is ended.

[0050] If the energy saving priority mode is ON in step S3, the hydro control device 121 determines in step S4 whether the heating capacity is equal to or greater than the heating capacity protection value. If the heating capacity is not equal to or greater than the heating capacity protection value, the process proceeds to step S8. On the other hand, if the heating capacity is equal to or greater than the heating capacity protection value, the process proceeds to step S5, where the hydro control device 121 determines whether the actual COP is equal to or less than the COP protection value. If the actual COP is equal to or less than the COP protection value, the process proceeds to step S6, where the heat pump control device 101 reduces the frequency of the compressor 1. Next, the process proceeds to step S7, where the heat pump control device 101 reduces the rotation speed of the blower 5. Thereafter, the process proceeds to step S8. If the actual COP is not equal to or less than the COP protection value in step S5, the process proceeds to step S8.

[0051] The number of times the rotation speed of the blower 5 is reduced may be less than the number of times the frequency of the compressor 1 is reduced. For example, the rotation speed of the blower 5 may be reduced once for every three times the frequency of the compressor 1 is reduced.

[0052] FIG. 5 is a graph showing the fluctuations of each parameter during hot water supply operation. Hot water supply operation begins at time t1 in FIG. 5 . During hot water supply operation, the temperature of the heat medium flowing into the condenser 2 gradually increases, and the heating capacity and COP gradually decrease accordingly. When the actual COP decreases to the COP protection value at time t2, COP protection control is initiated, and the heat pump control device 101 reduces the compressor frequency to prevent further decrease in COP. Thereafter, the heat pump control device 101 gradually reduces the compressor frequency, and when the heating capacity decreases to the heating capacity protection value at time t3, the heat pump control device 101 prevents further decrease in heating capacity by not further reducing the compressor frequency.

[0053] In the above-described embodiment, an example in which the COP protection control is performed during hot water supply operation has been described, but the COP protection control may also be performed during heating operation.

[0054] FIG. 6 is a diagram showing an example of a configuration for realizing the functions of the heat pump control device 101 and the hydro control device 121 in the first embodiment. Each function of the heat pump control device 101 and the hydro control device 121 is realized, for example, by a processing circuit. The processing circuit may be dedicated hardware 600. The processing circuit may include a processor 601 and a memory 602. A portion of the processing circuit may be formed as the dedicated hardware 600, and the processing circuit may further include the processor 601 and the memory 602. In the example shown in FIG. 6, a portion of the processing circuit is formed as the dedicated hardware 600. Furthermore, in the example shown in FIG. 6, the processing circuit further includes the processor 601 and the memory 602 in addition to the dedicated hardware 600.

[0055] The processing circuitry of which at least one portion is dedicated hardware 600 may be, for example, a single circuit, multiple circuits, a programmed processor, parallel programmed processors, an ASIC, an FPGA, or a combination thereof.

[0056] When the processing circuitry includes at least one processor 601 and at least one memory 602, the functions of each part of the heat pump control device 101 and the hydro control device 121 are realized by software, firmware, or a combination of software and firmware.

[0057] The software and firmware are written as programs and stored in memory 602. The programs may be recorded on a computer-readable recording medium. The processor 601 realizes the functions of each unit by reading and executing the programs stored in memory 602. The processor 601 is also called a CPU (Central Processing Unit), central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or DSP. The memory 602 may be, for example, a non-volatile or volatile semiconductor memory such as RAM, ROM, flash memory, EPROM, or EEPROM, or a magnetic disk, flexible disk, optical disk, compact disk, minidisk, DVD, etc.

[0058] In this way, the processing circuit can realize the functions of the heat pump control device 101 and the hydro control device 121 by using hardware, software, firmware, or a combination of these. Note that each function of the heat pump control device 101 and the hydro control device 121 may be realized by multiple devices working together, or may be realized by a single device. Furthermore, at least some of the functions of the heat pump control device 101 and the hydro control device 121 may be implemented on a server or the like on an external network.

[0059] REFERENCE SIGNS LIST 1 Compressor, 2 Condenser, 3 Expansion valve, 4 Evaporator, 5 Blower, 6 Heat medium pump, 7 Three-way valve, 8 Heating heat exchanger, 9 Water pump, 10 Hot water storage tank, 11 Mixing valve, 12a, 12b Radiator, 14 Connection point, 15 Hot water outlet pipe, 17 Connection point, 51 Refrigerant circuit, 52 Heating circulation circuit, 53 Hot water storage circuit, 100 Heat pump system, 101 Heat pump control device, 102 Measuring means, 103 Communication means, 104 Calculation means, 105 Control means, 121 Hydro control device, 122 Measuring means, 123 Storage means, 124 Input means, 125 Communication means, 126 Calculation means, 127 Control means, 131 Flow sensor, 141 2. Power meter, 201 pressure sensor, 202 temperature sensor, 203 temperature sensor, 204 temperature sensor, 205 temperature sensor, 206 temperature sensor, 207 temperature sensor, 208 temperature sensor, 209 temperature sensor, 210 temperature sensor, 211 temperature sensor, 212 temperature sensor, 216 temperature sensor, 251 remote control device, 301 heat pump unit, 302 hot water storage tank unit, 303 heat medium piping, 304 heat medium piping, 305a, 305b heating unit, 306 heat medium piping, 307 heat medium piping, 308 hot water supply pipe, 309 water supply pipe, 600 dedicated hardware, 601 processor, 602 memory

Claims

1. A heat pump system comprising: a refrigeration cycle device; a power meter that measures the power consumption of the refrigeration cycle device; a capacity detector that detects the capacity of the refrigeration cycle device; and a control circuit configured to perform COP protection control that reduces the operating capacity of the refrigeration cycle device so that an actual COP calculated from the power consumption and the capacity of the refrigeration cycle device does not become equal to or lower than a COP protection value.

2. The heat pump system according to claim 1, wherein the COP protection control is performed during a hot water supply operation in which water is heated by the refrigeration cycle device.

3. A heat pump system as described in claim 1 or claim 2, wherein a user can select ON / OFF of the energy saving priority mode, and the control circuit is configured to implement the COP protection control when the energy saving priority mode is ON, and not to implement the COP protection control when the energy saving priority mode is OFF.

4. A heat pump system as described in any one of claims 1 to 3, wherein the refrigeration cycle device is provided with a compressor that compresses a refrigerant, the control circuit is configured to reduce the refrigeration cycle operating capacity by lowering the frequency of the compressor, and the control circuit is configured not to further lower the frequency of the compressor when the refrigeration cycle capacity falls below a refrigeration cycle capacity protection value during the COP protection control.

5. The heat pump system according to claim 4, wherein the control circuit is configured to increase the refrigeration cycle capacity protection value when the outdoor temperature is low compared to when the outdoor temperature is high.

6. A heat pump system as claimed in any one of claims 1 to 5, wherein the refrigeration cycle device comprises a compressor that compresses a refrigerant and a blower that blows air to an evaporator that exchanges heat between the refrigerant and air, and the control circuit is configured to reduce the rotation speed of the blower when the frequency of the compressor is reduced during the COP protection control.

7. A heat pump system as described in any one of claims 1 to 6, wherein the refrigeration cycle device is provided with a compressor that compresses a refrigerant, and the control circuit is configured to reduce the compressor frequency when the COP protection control is being implemented to 65% to 70% of the compressor frequency when the COP protection control is not being implemented when the outside air temperature is 7°C or higher.

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